I am receiving warning in Facebook Application using PHP SDK
You need to ensure that any code that modifies the HTTP headers is executed before the headers are sent. This includes statements like session_start(). The headers will be sent automatically when any HTML is output.
Your problem here is that you're sending the HTML ouput at the top of your page before you've executed any PHP at all.
Move the session_start() to the top of your document :
<?php session_start(); ?> <html> <head> <title>PHP SDK</title> </head> <body> <?php require_once 'src/facebook.php'; // more PHP code here. How do I deal with installing peer dependencies in Angular CLI?
I found that running the npm install command in the same directory where your Angular project is, eliminates these warnings. I do not know the reason why.
Specifically, I was trying to use ng2-completer
$ npm install ng2-completer --save
npm WARN saveError ENOENT: no such file or directory, open 'C:\Work\foo\package.json'
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN enoent ENOENT: no such file or directory, open 'C:\Work\foo\package.json'
npm WARN [email protected] requires a peer of @angular/common@>= 6.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of @angular/core@>= 6.0.0 but noneis installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of @angular/forms@>= 6.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN foo No description
npm WARN foo No repository field.
npm WARN foo No README data
npm WARN foo No license field.
I was unable to compile. When I tried again, this time in my Angular project directory which was in foo/foo_app, it worked fine.
cd foo/foo_app
$ npm install ng2-completer --save
Cannot open include file: 'stdio.h' - Visual Studio Community 2017 - C++ Error
Just in case you don't want to bump Windows SDK to Windows 10 (you could be for example working on an open source project where the decision isn't yours to make), you can solve this problem in a Windows SDK 8.1 project by navigating Tools -> Get Tools and Features... -> Individual Compontents tab and installing the individual components "Windows 8.1 SDK" (under SDKs, libraries and frameworks) and "Windows Universal CRT SDK" (under Compilers, build tools and runtimes):
Why does C++ code for testing the Collatz conjecture run faster than hand-written assembly?
On a rather unrelated note: more performance hacks!
[the first «conjecture» has been finally debunked by @ShreevatsaR; removed]
When traversing the sequence, we can only get 3 possible cases in the 2-neighborhood of the current element
N(shown first):- [even] [odd]
- [odd] [even]
- [even] [even]
To leap past these 2 elements means to compute
(N >> 1) + N + 1,((N << 1) + N + 1) >> 1andN >> 2, respectively.Let`s prove that for both cases (1) and (2) it is possible to use the first formula,
(N >> 1) + N + 1.Case (1) is obvious. Case (2) implies
(N & 1) == 1, so if we assume (without loss of generality) that N is 2-bit long and its bits arebafrom most- to least-significant, thena = 1, and the following holds:(N << 1) + N + 1: (N >> 1) + N + 1: b10 b1 b1 b + 1 + 1 ---- --- bBb0 bBbwhere
B = !b. Right-shifting the first result gives us exactly what we want.Q.E.D.:
(N & 1) == 1 ? (N >> 1) + N + 1 == ((N << 1) + N + 1) >> 1.As proven, we can traverse the sequence 2 elements at a time, using a single ternary operation. Another 2× time reduction.
The resulting algorithm looks like this:
uint64_t sequence(uint64_t size, uint64_t *path) {
uint64_t n, i, c, maxi = 0, maxc = 0;
for (n = i = (size - 1) | 1; i > 2; n = i -= 2) {
c = 2;
while ((n = ((n & 3)? (n >> 1) + n + 1 : (n >> 2))) > 2)
c += 2;
if (n == 2)
c++;
if (c > maxc) {
maxi = i;
maxc = c;
}
}
*path = maxc;
return maxi;
}
int main() {
uint64_t maxi, maxc;
maxi = sequence(1000000, &maxc);
printf("%llu, %llu\n", maxi, maxc);
return 0;
}
Here we compare n > 2 because the process may stop at 2 instead of 1 if the total length of the sequence is odd.
[EDIT:]
Let`s translate this into assembly!
MOV RCX, 1000000;
DEC RCX;
AND RCX, -2;
XOR RAX, RAX;
MOV RBX, RAX;
@main:
XOR RSI, RSI;
LEA RDI, [RCX + 1];
@loop:
ADD RSI, 2;
LEA RDX, [RDI + RDI*2 + 2];
SHR RDX, 1;
SHRD RDI, RDI, 2; ror rdi,2 would do the same thing
CMOVL RDI, RDX; Note that SHRD leaves OF = undefined with count>1, and this doesn't work on all CPUs.
CMOVS RDI, RDX;
CMP RDI, 2;
JA @loop;
LEA RDX, [RSI + 1];
CMOVE RSI, RDX;
CMP RAX, RSI;
CMOVB RAX, RSI;
CMOVB RBX, RCX;
SUB RCX, 2;
JA @main;
MOV RDI, RCX;
ADD RCX, 10;
PUSH RDI;
PUSH RCX;
@itoa:
XOR RDX, RDX;
DIV RCX;
ADD RDX, '0';
PUSH RDX;
TEST RAX, RAX;
JNE @itoa;
PUSH RCX;
LEA RAX, [RBX + 1];
TEST RBX, RBX;
MOV RBX, RDI;
JNE @itoa;
POP RCX;
INC RDI;
MOV RDX, RDI;
@outp:
MOV RSI, RSP;
MOV RAX, RDI;
SYSCALL;
POP RAX;
TEST RAX, RAX;
JNE @outp;
LEA RAX, [RDI + 59];
DEC RDI;
SYSCALL;
Use these commands to compile:
nasm -f elf64 file.asm
ld -o file file.o
See the C and an improved/bugfixed version of the asm by Peter Cordes on Godbolt. (editor's note: Sorry for putting my stuff in your answer, but my answer hit the 30k char limit from Godbolt links + text!)
Vue.JS: How to call function after page loaded?
If you need run code after 100% loaded with image and files, test this in mounted():
document.onreadystatechange = () => {
if (document.readyState == "complete") {
console.log('Page completed with image and files!')
// fetch to next page or some code
}
}
More info: MDN Api onreadystatechange
Read .doc file with python
One can use the textract library. It take care of both "doc" as well as "docx"
import textract
text = textract.process("path/to/file.extension")
You can even use 'antiword' (sudo apt-get install antiword) and then convert doc to first into docx and then read through docx2txt.
antiword filename.doc > filename.docx
Ultimately, textract in the backend is using antiword.
ASP.NET 5 MVC: unable to connect to web server 'IIS Express'
delete bin and obj folders from the project folder and rebuild.
Content type 'application/x-www-form-urlencoded;charset=UTF-8' not supported for @RequestBody MultiValueMap
Simply removing @RequestBody annotation solves the problem (tested on Spring Boot 2):
@RestController
public class MyController {
@PostMapping
public void method(@Valid RequestDto dto) {
// method body ...
}
}
Lazy Loading vs Eager Loading
// Using LINQ and just referencing p.Employer will lazy load
// I am not at a computer but I know I have lazy loaded in one
// query with a single query call like below.
List<Person> persons = new List<Person>();
using(MyDbContext dbContext = new MyDbContext())
{
persons = (
from p in dbcontext.Persons
select new Person{
Name = p.Name,
Email = p.Email,
Employer = p.Employer
}).ToList();
}
C++ How do I convert a std::chrono::time_point to long and back
std::chrono::time_point<std::chrono::system_clock> now = std::chrono::system_clock::now();
This is a great place for auto:
auto now = std::chrono::system_clock::now();
Since you want to traffic at millisecond precision, it would be good to go ahead and covert to it in the time_point:
auto now_ms = std::chrono::time_point_cast<std::chrono::milliseconds>(now);
now_ms is a time_point, based on system_clock, but with the precision of milliseconds instead of whatever precision your system_clock has.
auto epoch = now_ms.time_since_epoch();
epoch now has type std::chrono::milliseconds. And this next statement becomes essentially a no-op (simply makes a copy and does not make a conversion):
auto value = std::chrono::duration_cast<std::chrono::milliseconds>(epoch);
Here:
long duration = value.count();
In both your and my code, duration holds the number of milliseconds since the epoch of system_clock.
This:
std::chrono::duration<long> dur(duration);
Creates a duration represented with a long, and a precision of seconds. This effectively reinterpret_casts the milliseconds held in value to seconds. It is a logic error. The correct code would look like:
std::chrono::milliseconds dur(duration);
This line:
std::chrono::time_point<std::chrono::system_clock> dt(dur);
creates a time_point based on system_clock, with the capability of holding a precision to the system_clock's native precision (typically finer than milliseconds). However the run-time value will correctly reflect that an integral number of milliseconds are held (assuming my correction on the type of dur).
Even with the correction, this test will (nearly always) fail though:
if (dt != now)
Because dt holds an integral number of milliseconds, but now holds an integral number of ticks finer than a millisecond (e.g. microseconds or nanoseconds). Thus only on the rare chance that system_clock::now() returned an integral number of milliseconds would the test pass.
But you can instead:
if (dt != now_ms)
And you will now get your expected result reliably.
Putting it all together:
int main ()
{
auto now = std::chrono::system_clock::now();
auto now_ms = std::chrono::time_point_cast<std::chrono::milliseconds>(now);
auto value = now_ms.time_since_epoch();
long duration = value.count();
std::chrono::milliseconds dur(duration);
std::chrono::time_point<std::chrono::system_clock> dt(dur);
if (dt != now_ms)
std::cout << "Failure." << std::endl;
else
std::cout << "Success." << std::endl;
}
Personally I find all the std::chrono overly verbose and so I would code it as:
int main ()
{
using namespace std::chrono;
auto now = system_clock::now();
auto now_ms = time_point_cast<milliseconds>(now);
auto value = now_ms.time_since_epoch();
long duration = value.count();
milliseconds dur(duration);
time_point<system_clock> dt(dur);
if (dt != now_ms)
std::cout << "Failure." << std::endl;
else
std::cout << "Success." << std::endl;
}
Which will reliably output:
Success.
Finally, I recommend eliminating temporaries to reduce the code converting between time_point and integral type to a minimum. These conversions are dangerous, and so the less code you write manipulating the bare integral type the better:
int main ()
{
using namespace std::chrono;
// Get current time with precision of milliseconds
auto now = time_point_cast<milliseconds>(system_clock::now());
// sys_milliseconds is type time_point<system_clock, milliseconds>
using sys_milliseconds = decltype(now);
// Convert time_point to signed integral type
auto integral_duration = now.time_since_epoch().count();
// Convert signed integral type to time_point
sys_milliseconds dt{milliseconds{integral_duration}};
// test
if (dt != now)
std::cout << "Failure." << std::endl;
else
std::cout << "Success." << std::endl;
}
The main danger above is not interpreting integral_duration as milliseconds on the way back to a time_point. One possible way to mitigate that risk is to write:
sys_milliseconds dt{sys_milliseconds::duration{integral_duration}};
This reduces risk down to just making sure you use sys_milliseconds on the way out, and in the two places on the way back in.
And one more example: Let's say you want to convert to and from an integral which represents whatever duration system_clock supports (microseconds, 10th of microseconds or nanoseconds). Then you don't have to worry about specifying milliseconds as above. The code simplifies to:
int main ()
{
using namespace std::chrono;
// Get current time with native precision
auto now = system_clock::now();
// Convert time_point to signed integral type
auto integral_duration = now.time_since_epoch().count();
// Convert signed integral type to time_point
system_clock::time_point dt{system_clock::duration{integral_duration}};
// test
if (dt != now)
std::cout << "Failure." << std::endl;
else
std::cout << "Success." << std::endl;
}
This works, but if you run half the conversion (out to integral) on one platform and the other half (in from integral) on another platform, you run the risk that system_clock::duration will have different precisions for the two conversions.
Owl Carousel, making custom navigation
my solution is
navigationText: ["", ""]
full code is below:
var owl1 = $("#main-demo");
owl1.owlCarousel({
navigation: true, // Show next and prev buttons
slideSpeed: 300,
pagination:false,
singleItem: true, transitionStyle: "fade",
navigationText: ["", ""]
});// Custom Navigation Events
owl1.trigger('owl.play', 4500);
Fatal error: iostream: No such file or directory in compiling C program using GCC
Seems like you posted a new question after you realized that you were dealing with a simpler problem related to size_t. I am glad that you did.
Anyways, You have a .c source file, and most of the code looks as per C standards, except that #include <iostream> and using namespace std;
C equivalent for the built-in functions of C++ standard #include<iostream> can be availed through #include<stdio.h>
- Replace
#include <iostream>with#include <stdio.h>, deleteusing namespace std; With
#include <iostream>taken off, you would need a C standard alternative forcout << endl;, which can be done byprintf("\n");orputchar('\n');
Out of the two options,printf("\n");works the faster as I observed.When used
printf("\n");in the code above in place ofcout<<endl;$ time ./thread.exe 1 2 3 4 5 6 7 8 9 10 real 0m0.031s user 0m0.030s sys 0m0.030sWhen used
putchar('\n');in the code above in place ofcout<<endl;$ time ./thread.exe 1 2 3 4 5 6 7 8 9 10 real 0m0.047s user 0m0.030s sys 0m0.030s
Compiled with Cygwin gcc (GCC) 4.8.3 version. results averaged over 10 samples. (Took me 15 mins)
enum to string in modern C++11 / C++14 / C++17 and future C++20
Magic Enum header-only library provides static reflection for enums (to string, from string, iteration) for C++17.
#include <magic_enum.hpp>
enum Color { RED = 2, BLUE = 4, GREEN = 8 };
Color color = Color::RED;
auto color_name = magic_enum::enum_name(color);
// color_name -> "RED"
std::string color_name{"GREEN"};
auto color = magic_enum::enum_cast<Color>(color_name)
if (color.has_value()) {
// color.value() -> Color::GREEN
};
For more examples check home repository https://github.com/Neargye/magic_enum.
Where is the drawback?
This library uses a compiler-specific hack (based on __PRETTY_FUNCTION__ / __FUNCSIG__), which works on Clang >= 5, MSVC >= 15.3 and GCC >= 9.
Enum value must be in range [MAGIC_ENUM_RANGE_MIN, MAGIC_ENUM_RANGE_MAX].
By default
MAGIC_ENUM_RANGE_MIN = -128,MAGIC_ENUM_RANGE_MAX = 128.If need another range for all enum types by default, redefine the macro
MAGIC_ENUM_RANGE_MINandMAGIC_ENUM_RANGE_MAX.MAGIC_ENUM_RANGE_MINmust be less or equals than0and must be greater thanINT16_MIN.MAGIC_ENUM_RANGE_MAXmust be greater than0and must be less thanINT16_MAX.If need another range for specific enum type, add specialization enum_range for necessary enum type.
#include <magic_enum.hpp> enum number { one = 100, two = 200, three = 300 }; namespace magic_enum { template <> struct enum_range<number> { static constexpr int min = 100; static constexpr int max = 300; }; }
EntityType 'IdentityUserLogin' has no key defined. Define the key for this EntityType
In my case I had inherited from the IdentityDbContext correctly (with my own custom types and key defined) but had inadvertantly removed the call to the base class's OnModelCreating:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder); // I had removed this
/// Rest of on model creating here.
}
Which then fixed up my missing indexes from the identity classes and I could then generate migrations and enable migrations appropriately.
Could not install Gradle distribution from 'https://services.gradle.org/distributions/gradle-2.1-all.zip'
If you are on Windows, you can go to:
C:\Users\{your_name}\.gradle
And delete all the references of the gradle package you can find in those folders:
- caches
- daemon
- wrapper
Then re-open your project and sync gradle
Efficiently getting all divisors of a given number
//Try this,it can find divisors of verrrrrrrrrry big numbers (pretty efficiently :-))
#include<iostream>
#include<cstdio>
#include<cmath>
#include<vector>
#include<conio.h>
using namespace std;
vector<double> D;
void divs(double N);
double mod(double &n1, double &n2);
void push(double N);
void show();
int main()
{
double N;
cout << "\n Enter number: "; cin >> N;
divs(N); // find and push divisors to D
cout << "\n Divisors of "<<N<<": "; show(); // show contents of D (all divisors of N)
_getch(); // used visual studio, if it isn't supported replace it by "getch();"
return(0);
}
void divs(double N)
{
for (double i = 1; i <= sqrt(N); ++i)
{
if (!mod(N, i)) { push(i); if(i*i!=N) push(N / i); }
}
}
double mod(double &n1, double &n2)
{
return(((n1/n2)-floor(n1/n2))*n2);
}
void push(double N)
{
double s = 1, e = D.size(), m = floor((s + e) / 2);
while (s <= e)
{
if (N==D[m-1]) { return; }
else if (N > D[m-1]) { s = m + 1; }
else { e = m - 1; }
m = floor((s + e) / 2);
}
D.insert(D.begin() + m, N);
}
void show()
{
for (double i = 0; i < D.size(); ++i) cout << D[i] << " ";
}
How to implement endless list with RecyclerView?
Make these variables.
private int previousTotal = 0;
private boolean loading = true;
private int visibleThreshold = 5;
int firstVisibleItem, visibleItemCount, totalItemCount;
Set on Scroll for recycler view.
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
visibleItemCount = mRecyclerView.getChildCount();
totalItemCount = mLayoutManager.getItemCount();
firstVisibleItem = mLayoutManager.findFirstVisibleItemPosition();
if (loading) {
if (totalItemCount > previousTotal) {
loading = false;
previousTotal = totalItemCount;
}
}
if (!loading && (totalItemCount - visibleItemCount)
<= (firstVisibleItem + visibleThreshold)) {
// End has been reached
Log.i("Yaeye!", "end called");
// Do something
loading = true;
}
}
});
Note : Make sure you are using
LinearLayoutManageras layout manager forRecyclerView.
LinearLayoutManager mLayoutManager;
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
and for a grid
GridLayoutManager mLayoutManager;
mLayoutManager = new GridLayoutManager(getActivity(), spanCount);
mRecyclerView.setLayoutManager(mLayoutManager);
Have fun with your endless scrolls !! ^.^
Update : mRecyclerView.
setOnScrollListener()is deprecated just replace withmRecyclerView.addOnScrollListener()and the warning will be gone! You can read more from this SO question.
Since Android now officially support Kotlin, here is an update for the same -
Make OnScrollListener
class OnScrollListener(val layoutManager: LinearLayoutManager, val adapter: RecyclerView.Adapter<RecyclerAdapter.ViewHolder>, val dataList: MutableList<Int>) : RecyclerView.OnScrollListener() {
var previousTotal = 0
var loading = true
val visibleThreshold = 10
var firstVisibleItem = 0
var visibleItemCount = 0
var totalItemCount = 0
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
visibleItemCount = recyclerView.childCount
totalItemCount = layoutManager.itemCount
firstVisibleItem = layoutManager.findFirstVisibleItemPosition()
if (loading) {
if (totalItemCount > previousTotal) {
loading = false
previousTotal = totalItemCount
}
}
if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
val initialSize = dataList.size
updateDataList(dataList)
val updatedSize = dataList.size
recyclerView.post { adapter.notifyItemRangeInserted(initialSize, updatedSize) }
loading = true
}
}
}
and add it to your RecyclerView like this
recyclerView.addOnScrollListener(OnScrollListener(layoutManager, adapter, dataList))
For a full code example, feel free to refer this Github repo.
How to add trendline in python matplotlib dot (scatter) graphs?
as explained here
With help from numpy one can calculate for example a linear fitting.
# plot the data itself
pylab.plot(x,y,'o')
# calc the trendline
z = numpy.polyfit(x, y, 1)
p = numpy.poly1d(z)
pylab.plot(x,p(x),"r--")
# the line equation:
print "y=%.6fx+(%.6f)"%(z[0],z[1])
OperationalError, no such column. Django
Step 1: Delete the db.sqlite3 file.
Step 2 : $ python manage.py migrate
Step 3 : $ python manage.py makemigrations
Step 4: Create the super user using $ python manage.py createsuperuser
new db.sqlite3 will generates automatically
How to mount host volumes into docker containers in Dockerfile during build
There is a way to mount a volume during a build, but it doesn't involve Dockerfiles.
The technique would be to create a container from whatever base you wanted to use (mounting your volume(s) in the container with the -v option), run a shell script to do your image building work, then commit the container as an image when done.
Not only will this leave out the excess files you don't want (this is good for secure files as well, like SSH files), it also creates a single image. It has downsides: the commit command doesn't support all of the Dockerfile instructions, and it doesn't let you pick up when you left off if you need to edit your build script.
UPDATE:
For example,
CONTAINER_ID=$(docker run -dit ubuntu:16.04)
docker cp build.sh $CONTAINER_ID:/build.sh
docker exec -t $CONTAINER_ID /bin/sh -c '/bin/sh /build.sh'
docker commit $CONTAINER_ID $REPO:$TAG
docker stop $CONTAINER_ID
Make Bootstrap 3 Tabs Responsive
There is a new one: http://hayatbiralem.com/blog/2015/05/15/responsive-bootstrap-tabs/
And also Codepen sample available here: http://codepen.io/hayatbiralem/pen/KpzjOL
No needs plugin. It uses just a little css and jquery.
Here's a sample tabs markup:
<ul class="nav nav-tabs nav-tabs-responsive">
<li class="active">
<a href="#tab1" data-toggle="tab">
<span class="text">Tab 1</span>
</a>
</li>
<li class="next">
<a href="#tab2" data-toggle="tab">
<span class="text">Tab 2</span>
</a>
</li>
<li>
<a href="#tab3" data-toggle="tab">
<span class="text">Tab 3</span>
</a>
</li>
...
</ul>
.. and jQuery codes are also here:
(function($) {
'use strict';
$(document).on('show.bs.tab', '.nav-tabs-responsive [data-toggle="tab"]', function(e) {
var $target = $(e.target);
var $tabs = $target.closest('.nav-tabs-responsive');
var $current = $target.closest('li');
var $parent = $current.closest('li.dropdown');
$current = $parent.length > 0 ? $parent : $current;
var $next = $current.next();
var $prev = $current.prev();
var updateDropdownMenu = function($el, position){
$el
.find('.dropdown-menu')
.removeClass('pull-xs-left pull-xs-center pull-xs-right')
.addClass( 'pull-xs-' + position );
};
$tabs.find('>li').removeClass('next prev');
$prev.addClass('prev');
$next.addClass('next');
updateDropdownMenu( $prev, 'left' );
updateDropdownMenu( $current, 'center' );
updateDropdownMenu( $next, 'right' );
});
})(jQuery);
How to display full (non-truncated) dataframe information in html when converting from pandas dataframe to html?
Another way of viewing the full content of the cells in a pandas dataframe is to use IPython's display functions:
from IPython.display import HTML
HTML(df.to_html())
Batch script to install MSI
This is how to install a normal MSI file silently:
msiexec.exe /i c:\setup.msi /QN /L*V "C:\Temp\msilog.log"
Quick explanation:
/L*V "C:\Temp\msilog.log"= verbose logging at indicated path
/QN = run completely silently
/i = run install sequence
The msiexec.exe command line is extensive with support for a variety of options. Here is another overview of the same command line interface. Here is an annotated versions (was broken, resurrected via way back machine).
It is also possible to make a batch file a lot shorter with constructs such as for loops as illustrated here for Windows Updates.
If there are check boxes that must be checked during the setup, you must find the appropriate PUBLIC PROPERTIES attached to the check box and set it at the command line like this:
msiexec.exe /i c:\setup.msi /QN /L*V "C:\Temp\msilog.log" STARTAPP=1 SHOWHELP=Yes
These properties are different in each MSI. You can find them via the verbose log file or by opening the MSI in Orca, or another appropriate tool. You must look either in the dialog control section or in the Property table for what the property name is. Try running the setup and create a verbose log file first and then search the log for messages ala "Setting property..." and then see what the property name is there. Then add this property with the value from the log file to the command line.
Also have a look at how to use transforms to customize the MSI beyond setting command line parameters: How to make better use of MSI files
Writing .csv files from C++
As explained above by @kris, depending on the region configurations of MS Excel it won't interpret the comma as the separator character. In my case I had to change it to semi-colon
Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_u64 on Intel CPUs
First of all, try to estimate peak performance - examine https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf, in particular, Appendix C.
In your case, it's table C-10 that shows POPCNT instruction has latency = 3 clocks and throughput = 1 clock. Throughput shows your maximal rate in clocks (multiply by core frequency and 8 bytes in case of popcnt64 to get your best possible bandwidth number).
Now examine what compiler did and sum up throughputs of all other instructions in the loop. This will give best possible estimate for generated code.
At last, look at data dependencies between instructions in the loop as they will force latency-large delay instead of throughput - so split instructions of single iteration on data flow chains and calculate latency across them then naively pick up maximal from them. it will give rough estimate taking into account data flow dependencies.
However, in your case, just writing code the right way would eliminate all these complexities. Instead of accumulating to the same count variable, just accumulate to different ones (like count0, count1, ... count8) and sum them up at the end. Or even create an array of counts[8] and accumulate to its elements - perhaps, it will be vectorized even and you will get much better throughput.
P.S. and never run benchmark for a second, first warm up the core then run loop for at least 10 seconds or better 100 seconds. otherwise, you will test power management firmware and DVFS implementation in hardware :)
P.P.S. I heard endless debates on how much time should benchmark really run. Most smartest folks are even asking why 10 seconds not 11 or 12. I should admit this is funny in theory. In practice, you just go and run benchmark hundred times in a row and record deviations. That IS funny. Most people do change source and run bench after that exactly ONCE to capture new performance record. Do the right things right.
Not convinced still? Just use above C-version of benchmark by assp1r1n3 (https://stackoverflow.com/a/37026212/9706746) and try 100 instead of 10000 in retry loop.
My 7960X shows, with RETRY=100:
Count: 203182300 Elapsed: 0.008385 seconds Speed: 12.505379 GB/s
Count: 203182300 Elapsed: 0.011063 seconds Speed: 9.478225 GB/s
Count: 203182300 Elapsed: 0.011188 seconds Speed: 9.372327 GB/s
Count: 203182300 Elapsed: 0.010393 seconds Speed: 10.089252 GB/s
Count: 203182300 Elapsed: 0.009076 seconds Speed: 11.553283 GB/s
with RETRY=10000:
Count: 20318230000 Elapsed: 0.661791 seconds Speed: 15.844519 GB/s
Count: 20318230000 Elapsed: 0.665422 seconds Speed: 15.758060 GB/s
Count: 20318230000 Elapsed: 0.660983 seconds Speed: 15.863888 GB/s
Count: 20318230000 Elapsed: 0.665337 seconds Speed: 15.760073 GB/s
Count: 20318230000 Elapsed: 0.662138 seconds Speed: 15.836215 GB/s
P.P.P.S. Finally, on "accepted answer" and other mistery ;-)
Let's use assp1r1n3's answer - he has 2.5Ghz core. POPCNT has 1 clock throuhgput, his code is using 64-bit popcnt. So math is 2.5Ghz * 1 clock * 8 bytes = 20 GB/s for his setup. He is seeing 25Gb/s, perhaps due to turbo boost to around 3Ghz.
Thus go to ark.intel.com and look for i7-4870HQ: https://ark.intel.com/products/83504/Intel-Core-i7-4870HQ-Processor-6M-Cache-up-to-3-70-GHz-?q=i7-4870HQ
That core could run up to 3.7Ghz and real maximal rate is 29.6 GB/s for his hardware. So where is another 4GB/s? Perhaps, it's spent on loop logic and other surrounding code within each iteration.
Now where is this false dependency? hardware runs at almost peak rate. Maybe my math is bad, it happens sometimes :)
P.P.P.P.P.S. Still people suggesting HW errata is culprit, so I follow suggestion and created inline asm example, see below.
On my 7960X, first version (with single output to cnt0) runs at 11MB/s, second version (with output to cnt0, cnt1, cnt2 and cnt3) runs at 33MB/s. And one could say - voila! it's output dependency.
OK, maybe, the point I made is that it does not make sense to write code like this and it's not output dependency problem but dumb code generation. We are not testing hardware, we are writing code to unleash maximal performance. You could expect that HW OOO should rename and hide those "output-dependencies" but, gash, just do the right things right and you will never face any mystery.
uint64_t builtin_popcnt1a(const uint64_t* buf, size_t len)
{
uint64_t cnt0, cnt1, cnt2, cnt3;
cnt0 = cnt1 = cnt2 = cnt3 = 0;
uint64_t val = buf[0];
#if 0
__asm__ __volatile__ (
"1:\n\t"
"popcnt %2, %1\n\t"
"popcnt %2, %1\n\t"
"popcnt %2, %1\n\t"
"popcnt %2, %1\n\t"
"subq $4, %0\n\t"
"jnz 1b\n\t"
: "+q" (len), "=q" (cnt0)
: "q" (val)
:
);
#else
__asm__ __volatile__ (
"1:\n\t"
"popcnt %5, %1\n\t"
"popcnt %5, %2\n\t"
"popcnt %5, %3\n\t"
"popcnt %5, %4\n\t"
"subq $4, %0\n\t"
"jnz 1b\n\t"
: "+q" (len), "=q" (cnt0), "=q" (cnt1), "=q" (cnt2), "=q" (cnt3)
: "q" (val)
:
);
#endif
return cnt0;
}
Comparing strings, c++
.compare() returns an integer, which is a measure of the difference between the two strings.
- A return value of
0indicates that the two strings compare as equal. - A positive value means that the compared string is longer, or the first non-matching character is greater.
- A negative value means that the compared string is shorter, or the first non-matching character is lower.
operator== simply returns a boolean, indicating whether the strings are equal or not.
If you don't need the extra detail, you may as well just use ==.
Cannot get OpenCV to compile because of undefined references?
If you do the following, you will be able to use opencv build from OpenCV_INSTALL_PATH.
cmake_minimum_required(VERSION 2.8)
SET(OpenCV_INSTALL_PATH /home/user/opencv/opencv-2.4.13/release/)
SET(OpenCV_INCLUDE_DIRS "${OpenCV_INSTALL_PATH}/include/opencv;${OpenCV_INSTALL_PATH}/include")
SET(OpenCV_LIB_DIR "${OpenCV_INSTALL_PATH}/lib")
LINK_DIRECTORIES(${OpenCV_LIB_DIR})
set(OpenCV_LIBS opencv_core opencv_imgproc opencv_calib3d opencv_video opencv_features2d opencv_ml opencv_highgui opencv_objdetect opencv_contrib opencv_legacy opencv_gpu)
# find_package( OpenCV )
project(edge.cpp)
add_executable(edge edge.cpp)
Sniffing/logging your own Android Bluetooth traffic
On Xiaomi Redmi Note 9s This configuration file can also be found /storage/emulated/0/MIUI/debug_log/common named as hci_snoop20210210214303.cfa hci_snoop20210211095126.cfa
With enabled 'Settings->Developer Options, then checking the box next to "Bluetooth HCI Snoop Log." '
I was used Total Commander for taking file from Internal storage
Get ALL User Friends Using Facebook Graph API - Android
In v2.0 of the Graph API, calling /me/friends returns the person's friends who also use the app.
In addition, in v2.0, you must request the user_friends permission from each user. user_friends is no longer included by default in every login. Each user must grant the user_friends permission in order to appear in the response to /me/friends. See the Facebook upgrade guide for more detailed information, or review the summary below.
The /me/friendlists endpoint and user_friendlists permission are not what you're after. This endpoint does not return the users friends - its lets you access the lists a person has made to organize their friends. It does not return the friends in each of these lists. This API and permission is useful to allow you to render a custom privacy selector when giving people the opportunity to publish back to Facebook.
If you want to access a list of non-app-using friends, there are two options:
If you want to let your people tag their friends in stories that they publish to Facebook using your App, you can use the
/me/taggable_friendsAPI. Use of this endpoint requires review by Facebook and should only be used for the case where you're rendering a list of friends in order to let the user tag them in a post.If your App is a Game AND your Game supports Facebook Canvas, you can use the
/me/invitable_friendsendpoint in order to render a custom invite dialog, then pass the tokens returned by this API to the standard Requests Dialog.
In other cases, apps are no longer able to retrieve the full list of a user's friends (only those friends who have specifically authorized your app using the user_friends permission).
For apps wanting allow people to invite friends to use an app, you can still use the Send Dialog on Web or the new Message Dialog on iOS and Android.
How to test Spring Data repositories?
When you really want to write an i-test for a spring data repository you can do it like this:
@RunWith(SpringRunner.class)
@DataJpaTest
@EnableJpaRepositories(basePackageClasses = WebBookingRepository.class)
@EntityScan(basePackageClasses = WebBooking.class)
public class WebBookingRepositoryIntegrationTest {
@Autowired
private WebBookingRepository repository;
@Test
public void testSaveAndFindAll() {
WebBooking webBooking = new WebBooking();
webBooking.setUuid("some uuid");
webBooking.setItems(Arrays.asList(new WebBookingItem()));
repository.save(webBooking);
Iterable<WebBooking> findAll = repository.findAll();
assertThat(findAll).hasSize(1);
webBooking.setId(1L);
assertThat(findAll).containsOnly(webBooking);
}
}
To follow this example you have to use these dependencies:
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>1.4.197</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>3.9.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
Can't find file executable in your configured search path for gnc gcc compiler
Fistly, Code Blocks is not a compiler. It is just an integrated development environment.
So, you must show the path of your compiler at first, (if you dont have a compiler you have to download an install, it is not difficult to find. f.e. GCC is good one.) If code blocks could not find automatically the path of compiler it is an obligation to show it yourself.
But when you install, probably Code Blocks automatically find your compiler.
Enjoy.
Batch script to find and replace a string in text file within a minute for files up to 12 MB
Give this a shot:
@echo off
setlocal
call :FindReplace "findstr" "replacestr" input.txt
exit /b
:FindReplace <findstr> <replstr> <file>
set tmp="%temp%\tmp.txt"
If not exist %temp%\_.vbs call :MakeReplace
for /f "tokens=*" %%a in ('dir "%3" /s /b /a-d /on') do (
for /f "usebackq" %%b in (`Findstr /mic:"%~1" "%%a"`) do (
echo(&Echo Replacing "%~1" with "%~2" in file %%~nxa
<%%a cscript //nologo %temp%\_.vbs "%~1" "%~2">%tmp%
if exist %tmp% move /Y %tmp% "%%~dpnxa">nul
)
)
del %temp%\_.vbs
exit /b
:MakeReplace
>%temp%\_.vbs echo with Wscript
>>%temp%\_.vbs echo set args=.arguments
>>%temp%\_.vbs echo .StdOut.Write _
>>%temp%\_.vbs echo Replace(.StdIn.ReadAll,args(0),args(1),1,-1,1)
>>%temp%\_.vbs echo end with
Batch script to find and replace a string in text file without creating an extra output file for storing the modified file
@echo off
setlocal enableextensions disabledelayedexpansion
set "search=%1"
set "replace=%2"
set "textFile=Input.txt"
for /f "delims=" %%i in ('type "%textFile%" ^& break ^> "%textFile%" ') do (
set "line=%%i"
setlocal enabledelayedexpansion
>>"%textFile%" echo(!line:%search%=%replace%!
endlocal
)
for /f will read all the data (generated by the type comamnd) before starting to process it. In the subprocess started to execute the type, we include a redirection overwritting the file (so it is emptied). Once the do clause starts to execute (the content of the file is in memory to be processed) the output is appended to the file.
c++ and opencv get and set pixel color to Mat
You did everything except copying the new pixel value back to the image.
This line takes a copy of the pixel into a local variable:
Vec3b color = image.at<Vec3b>(Point(x,y));
So, after changing color as you require, just set it back like this:
image.at<Vec3b>(Point(x,y)) = color;
So, in full, something like this:
Mat image = img;
for(int y=0;y<img.rows;y++)
{
for(int x=0;x<img.cols;x++)
{
// get pixel
Vec3b & color = image.at<Vec3b>(y,x);
// ... do something to the color ....
color[0] = 13;
color[1] = 13;
color[2] = 13;
// set pixel
//image.at<Vec3b>(Point(x,y)) = color;
//if you copy value
}
}
This declaration has no storage class or type specifier in C++
You can declare an object of a class in another Class,that's possible but you cant initialize that object. For that you need to do something like this :--> (inside main)
Orderbook o1;
o1.m.check(side)
but that would be unnecessary. Keeping things short :-
You can't call functions inside a Class
C++ - Decimal to binary converting
#include <iostream>
// x is our number to test
// pow is a power of 2 (e.g. 128, 64, 32, etc...)
int printandDecrementBit(int x, int pow)
{
// Test whether our x is greater than some power of 2 and print the bit
if (x >= pow)
{
std::cout << "1";
// If x is greater than our power of 2, subtract the power of 2
return x - pow;
}
else
{
std::cout << "0";
return x;
}
}
int main()
{
std::cout << "Enter an integer between 0 and 255: ";
int x;
std::cin >> x;
x = printandDecrementBit(x, 128);
x = printandDecrementBit(x, 64);
x = printandDecrementBit(x, 32);
x = printandDecrementBit(x, 16);
std::cout << " ";
x = printandDecrementBit(x, 8);
x = printandDecrementBit(x, 4);
x = printandDecrementBit(x, 2);
x = printandDecrementBit(x, 1);
return 0;
}
this is a simple way to get the binary form of an int. credit to learncpp.com. im sure this could be used in different ways to get to the same point.
no match for ‘operator<<’ in ‘std::operator
Object is a collection of methods and variables.You can't print the variables in object by just cout operation . if you want to show the things inside the object you have to declare either a getter or a display text method in class.
ex
#include <iostream>
using namespace std;
class mystruct
{
private:
int m_a;
float m_b;
public:
mystruct(int x, float y)
{
m_a = x;
m_b = y;
}
public:
void getm_aAndm_b()
{
cout<<m_a<<endl;
cout<<m_b<<endl;
}
};
int main()
{
mystruct m = mystruct(5,3.14);
cout << "my structure " << endl;
m.getm_aAndm_b();
return 0;
}
Not that this is just a one way of doing it
How to use setprecision in C++
Below code runs correctly.
#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
double num1 = 3.12345678;
cout << fixed << showpoint;
cout << setprecision(2);
cout << num1 << endl;
}
How do I get the Back Button to work with an AngularJS ui-router state machine?
history.back() and switch to previous state often give effect not that you want. For example, if you have form with tabs and each tab has own state, this just switched previous tab selected, not return from form. In case nested states, you usually need so think about witch of parent states you want to rollback.
This directive solves problem
angular.module('app', ['ui-router-back'])
<span ui-back='defaultState'> Go back </span>
It returns to state, that was active before button has displayed. Optional defaultState is state name that used when no previous state in memory. Also it restores scroll position
Code
class UiBackData {
fromStateName: string;
fromParams: any;
fromStateScroll: number;
}
interface IRootScope1 extends ng.IScope {
uiBackData: UiBackData;
}
class UiBackDirective implements ng.IDirective {
uiBackDataSave: UiBackData;
constructor(private $state: angular.ui.IStateService,
private $rootScope: IRootScope1,
private $timeout: ng.ITimeoutService) {
}
link: ng.IDirectiveLinkFn = (scope, element, attrs) => {
this.uiBackDataSave = angular.copy(this.$rootScope.uiBackData);
function parseStateRef(ref, current) {
var preparsed = ref.match(/^\s*({[^}]*})\s*$/), parsed;
if (preparsed) ref = current + '(' + preparsed[1] + ')';
parsed = ref.replace(/\n/g, " ").match(/^([^(]+?)\s*(\((.*)\))?$/);
if (!parsed || parsed.length !== 4)
throw new Error("Invalid state ref '" + ref + "'");
let paramExpr = parsed[3] || null;
let copy = angular.copy(scope.$eval(paramExpr));
return { state: parsed[1], paramExpr: copy };
}
element.on('click', (e) => {
e.preventDefault();
if (this.uiBackDataSave.fromStateName)
this.$state.go(this.uiBackDataSave.fromStateName, this.uiBackDataSave.fromParams)
.then(state => {
// Override ui-router autoscroll
this.$timeout(() => {
$(window).scrollTop(this.uiBackDataSave.fromStateScroll);
}, 500, false);
});
else {
var r = parseStateRef((<any>attrs).uiBack, this.$state.current);
this.$state.go(r.state, r.paramExpr);
}
});
};
public static factory(): ng.IDirectiveFactory {
const directive = ($state, $rootScope, $timeout) =>
new UiBackDirective($state, $rootScope, $timeout);
directive.$inject = ['$state', '$rootScope', '$timeout'];
return directive;
}
}
angular.module('ui-router-back')
.directive('uiBack', UiBackDirective.factory())
.run(['$rootScope',
($rootScope: IRootScope1) => {
$rootScope.$on('$stateChangeSuccess',
(event, toState, toParams, fromState, fromParams) => {
if ($rootScope.uiBackData == null)
$rootScope.uiBackData = new UiBackData();
$rootScope.uiBackData.fromStateName = fromState.name;
$rootScope.uiBackData.fromStateScroll = $(window).scrollTop();
$rootScope.uiBackData.fromParams = fromParams;
});
}]);
Function stoi not declared
Are you running C++ 11? stoi was added in C++ 11, if you're running on an older version use atoi()
How to find sum of several integers input by user using do/while, While statement or For statement
#include<iostream>
int main()
{//initialize variables
int limit;
int num;
int sum=0;
int counter=0;
cout<<"Enter limit of numbers you wish to see"<<" ";
cin>>limit;
cout<<endl;
while(counter<limit)
{
cout<<"Enter number "<<endl;
cin>>num;
sum=sum+num;
counter++;
}
cout<<"The sum of numbers is "<<" "<<endl
return 0;
}
Error: Expression must have integral or unscoped enum type
Your variable size is declared as: float size;
You can't use a floating point variable as the size of an array - it needs to be an integer value.
You could cast it to convert to an integer:
float *temp = new float[(int)size];
Your other problem is likely because you're writing outside of the bounds of the array:
float *temp = new float[size];
//Getting input from the user
for (int x = 1; x <= size; x++){
cout << "Enter temperature " << x << ": ";
// cin >> temp[x];
// This should be:
cin >> temp[x - 1];
}
Arrays are zero based in C++, so this is going to write beyond the end and never write the first element in your original code.
Linux bash script to extract IP address
To just get your IP address:
echo `ifconfig eth0 2>/dev/null|awk '/inet addr:/ {print $2}'|sed 's/addr://'`
This will give you the IP address of eth0.
Edit: Due to name changes of interfaces in recent versions of Ubuntu, this doesn't work anymore. Instead, you could just use this:
hostname --all-ip-addresses or hostname -I, which does the same thing (gives you ALL IP addresses of the host).
no operator "<<" matches these operands
You're not including the standard <string> header.
You got [un]lucky that some of its pertinent definitions were accidentally made available by the other standard headers that you did include ... but operator<< was not.
Using getline() with file input in C++
getline, as it name states, read a whole line, or at least till a delimiter that can be specified.
So the answer is "no", getlinedoes not match your need.
But you can do something like:
inFile >> first_name >> last_name >> age;
name = first_name + " " + last_name;
CSS - display: none; not working
In the HTML source provided, the element #tfl has an inline style "display:block". Inline style will always override stylesheets styles…
Then, you have some options (while as you said you can't modify the html code nor using javascript):
- force
display:nonewith!importantrule (not recommended) put the div offscreen with theses rules :
#tfl { position: absolute; left: -9999px; }
What exactly does stringstream do?
You entered an alphanumeric and int, blank delimited in mystr.
You then tried to convert the first token (blank delimited) into an int.
The first token was RS which failed to convert to int, leaving a zero for myprice, and we all know what zero times anything yields.
When you only entered int values the second time, everything worked as you expected.
It was the spurious RS that caused your code to fail.
read word by word from file in C++
As others have said, you are likely reading past the end of the file as you're only checking for x != ' '. Instead you also have to check for EOF in the inner loop (but in this case don't use a char, but a sufficiently large type):
while ( ! file.eof() )
{
std::ifstream::int_type x = file.get();
while ( x != ' ' && x != std::ifstream::traits_type::eof() )
{
word += static_cast<char>(x);
x = file.get();
}
std::cout << word << '\n';
word.clear();
}
But then again, you can just employ the stream's streaming operators, which already separate at whitespace (and better account for multiple spaces and other kinds of whitepsace):
void readFile( )
{
std::ifstream file("program.txt");
for(std::string word; file >> word; )
std::cout << word << '\n';
}
And even further, you can employ a standard algorithm to get rid of the manual loop altogether:
#include <algorithm>
#include <iterator>
void readFile( )
{
std::ifstream file("program.txt");
std::copy(std::istream_iterator<std::string>(file),
std::istream_itetator<std::string>(),
std::ostream_iterator<std::string>(std::cout, "\n"));
}
Correct way of looping through C++ arrays
sizeof tells you the size of a thing, not the number of elements in it. A more C++11 way to do what you are doing would be:
#include <array>
#include <string>
#include <iostream>
int main()
{
std::array<std::string, 3> texts { "Apple", "Banana", "Orange" };
for (auto& text : texts) {
std::cout << text << '\n';
}
return 0;
}
ideone demo: http://ideone.com/6xmSrn
Endless loop in C/C++
It is very subjective. I write this:
while(true) {} //in C++
Because its intent is very much clear and it is also readable: you look at it and you know infinite loop is intended.
One might say for(;;) is also clear. But I would argue that because of its convoluted syntax, this option requires extra knowledge to reach the conclusion that it is an infinite loop, hence it is relatively less clear. I would even say there are more number of programmers who don't know what for(;;) does (even if they know usual for loop), but almost all programmers who knows while loop would immediately figure out what while(true) does.
To me, writing for(;;) to mean infinite loop, is like writing while() to mean infinite loop — while the former works, the latter does NOT. In the former case, empty condition turns out to be true implicitly, but in the latter case, it is an error! I personally didn't like it.
Now while(1) is also there in the competition. I would ask: why while(1)? Why not while(2), while(3) or while(0.1)? Well, whatever you write, you actually mean while(true) — if so, then why not write it instead?
In C (if I ever write), I would probably write this:
while(1) {} //in C
While while(2), while(3) and while(0.1) would equally make sense. But just to be conformant with other C programmers, I would write while(1), because lots of C programmers write this and I find no reason to deviate from the norm.
fatal error C1010 - "stdafx.h" in Visual Studio how can this be corrected?
Create a new "Empty Project" , Add your Cpp file to the new project, delete the line that includes stdafx.
Done.
The project no longer needs the stdafx. It is added automatically when you create projects with installed templates.
Is there 'byte' data type in C++?
Yes, there is std::byte (defined in <cstddef>).
C++ 17 introduced it.
undefined reference to WinMain@16 (codeblocks)
I was interested in setting up graphics for Code Blocks when I ran into a this error: (took me 2 hrs to solve it)
I guess you need to have a bit of luck with this. In my case i just changed the order of contents in Settings menu->Compiler and Debugger->Global compiler settings->Linker settings->Other Linker Options: The working sequence is: -lmingw32 -lSDL -lSDLmain
How can I solve the error LNK2019: unresolved external symbol - function?
Another way you can get this linker error (as I was) is if you are exporting an instance of a class from a DLL file, but have not declared that class itself as import/export.
#ifdef MYDLL_EXPORTS
#define DLLEXPORT __declspec(dllexport)
#else
#define DLLEXPORT __declspec(dllimport)
#endif
class DLLEXPORT Book // <--- This class must also be declared as export/import
{
public:
Book();
~Book();
int WordCount();
};
DLLEXPORT extern Book book; // <-- This is what I really wanted, to export book object
So even though primarily I was exporting just an instance of the Book class called book above, I had to declare the Book class as export/import class as well otherwise calling book.WordCount() in the other DLL file was causing a link error.
Playing m3u8 Files with HTML Video Tag
Adding to ben.bourdin answer, you can at least in any HTML based application, check if the browser supports HLS in its video element:
Let´s assume that your video element ID is "myVideo", then through javascript you can use the "canPlayType" function (http://www.w3schools.com/tags/av_met_canplaytype.asp)
var videoElement = document.getElementById("myVideo");
if(videoElement.canPlayType('application/vnd.apple.mpegurl') === "probably" || videoElement.canPlayType('application/vnd.apple.mpegurl') === "maybe"){
//Actions like playing the .m3u8 content
}
else{
//Actions like playing another video type
}
The canPlayType function, returns:
"" when there is no support for the specified audio/video type
"maybe" when the browser might support the specified audio/video type
"probably" when it most likely supports the specified audio/video type (you can use just this value in the validation to be more sure that your browser supports the specified type)
Hope this help :)
Best regards!
How to create a sticky footer that plays well with Bootstrap 3
Since it's in bootstrap 3, the site will be using jQuery. So the solution could also be the following, instead of trying to play with complex CSS:
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<link href="css/bootstrap.min.css" rel="stylesheet" />
<style>
.my-footer {
border-radius : 0px;
margin : 0px; /* pesky margin below .navbar */
position : absolute;
width : 100%;
}
</style>
</head>
<body>
<div class="container-fluid">
<div class="row">
<!-- Content of any length -->
asdfasdfasdfasdfs <br />
asdfasdfasdfasdfs <br />
asdfasdfasdfasdfs <br />
</div>
</div>
<div class="navbar navbar-inverse my-footer">
<div class="container-fluid">
<div class="row">
<p class="navbar-text">My footer content goes here...</p>
</div>
</div>
</div>
<script src="js/jquery-1.11.0.min.js"></script>
<script src="js/bootstrap.min.js"></script>
<script type="text/javascript">
$(document).ready(function () {
var $docH = $(document).height();
// The document height will grow as the content on the page grows.
$('.my-footer').css({
/*
The default height of .navbar is 50px with a 1px border,
change this 52 if you change the height of your footer.
*/
top: ($docH - 52) + 'px'
});
});
</script>
</body>
</html>
A different take on it, hope it helps.
Kind regards.
Bootstrap NavBar with left, center or right aligned items
Smack my head, just reread my answer and realized the OP was asking for two logo's one on the left one on the right with a center menu, not the other way around.
This can be accomplished strictly in the HTML by using Bootstrap's "navbar-right" and "navbar-left" for the logos and then "nav-justified" instead of "navbar-nav" for your UL. No addtional CSS needed (unless you want to put the navbar-collapse toggle in the center in the xs viewport, then you need to override a bit, but will leave that up to you).
<nav class="navbar navbar-default" role="navigation">
<div class="navbar-header">
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<div class="navbar-brand navbar-left"><a href="#"><img src="http://placehold.it/150x30"></a></div>
</div>
<div class="navbar-brand navbar-right"><a href="#"><img src="http://placehold.it/150x30"></a></div>
<div class="navbar-collapse collapse">
<ul class="nav nav-justified">
<li><a href="#">home</a></li>
<li><a href="#about">about</a></li>
</ul>
</div>
</nav>
Bootply: http://www.bootply.com/W6uB8YfKxm
For those who got here trying to center the "brand" here is my old answer:
I know this thread is a little old, but just to post my findings when working on this. I decided to base my solution on skelly's answer since tomaszbak's breaks on collaspe. First I created my "navbar-center" and turned off float for the normal navbar in my CSS:
.navbar-center
{
position: absolute;
width: 100%;
left: 0;
text-align: center;
margin: auto;
}
.navbar-brand{
float:none;
}
However the issue with skelly's answer is if you have a really long brand name (or you wanted to use an image for your brand) then once you get to the the sm viewport there could be overlapping due to the absolute position and as the commenters have said, once you get to the xs viewport the toggle switch breaks (unless you use Z positioning but I really didn't want to have to worry about it).
So what I did was utilize the bootstrap responsive utilities to create multiple version of the brand block:
<nav class="navbar navbar-default" role="navigation">
<div class="navbar-header">
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<div class="navbar-brand visible-xs"><a href="#">Brand That is Really Long</a></div>
</div>
<div class="navbar-brand visible-sm text-center"><a href="#">Brand That is Really Long</a></div>
<div class="navbar-brand navbar-center hidden-xs hidden-sm"><a href="#">Brand That is Really Long</a></div>
<div class="navbar-collapse collapse">
<ul class="nav navbar-nav navbar-left">
<li><a href="#">Left</a></li>
<li><a href="#about">Left</a></li>
<li><a href="#">Left</a></li>
<li><a href="#about">Left</a></li>
<li><a href="#">Left</a></li>
<li><a href="#about">Left</a></li>
</ul>
<ul class="nav navbar-nav navbar-right">
<li><a href="#about">Right</a></li>
<li><a href="#contact">Right</a></li>
<li><a href="#about">Right</a></li>
<li><a href="#contact">Right</a></li>
<li><a href="#about">Right</a></li>
<li><a href="#contact">Right</a></li>
</ul>
</div>
So now the lg and md viewports have the brand centered with links to the left and right, once you get to the sm viewport your links drop to the next line so that you don't overlap with your brand, and then finally at the xs viewport the collaspe kicks in and you are able to use the toggle. You could take this a step further and modify the media queries for the navbar-right and navbar-left when used with navbar-brand so that in the sm viewport the links are all centered but didn't have the time to vet it out.
You can check my old bootply here: www.bootply.com/n3PXXropP3
I guess having 3 brands might be just as much hassle as the "z" but I feel like in the world of responsive design this solution fits my style better.
How to get current timestamp in milliseconds since 1970 just the way Java gets
Include <ctime> and use the time function.
Including .cpp files
What include does is copying all the contents from the file (which is the argument inside the <> or the "" ), so when the preproccesor finishes its work main.cpp will look like:
// iostream stuff
int foo(int a){
return ++a;
}
int main(int argc, char *argv[])
{
int x=42;
std::cout << x <<std::endl;
std::cout << foo(x) << std::endl;
return 0;
}
So foo will be defined in main.cpp, but a definition also exists in foop.cpp, so the compiler "gets confused" because of the function duplication.
Debug assertion failed. C++ vector subscript out of range
v has 10 element, the index starts from 0 to 9.
for(int j=10;j>0;--j)
{
cout<<v[j]; // v[10] out of range
}
you should update for loop to
for(int j=9; j>=0; --j)
// ^^^^^^^^^^
{
cout<<v[j]; // out of range
}
Or use reverse iterator to print element in reverse order
for (auto ri = v.rbegin(); ri != v.rend(); ++ri)
{
std::cout << *ri << std::endl;
}
How to disable Google asking permission to regularly check installed apps on my phone?
On Android prior to 4.2, go to Google Settings, tap Verify apps and uncheck the option Verify apps.
On Android 4.2+, uncheck the option Settings > Security > Verify apps and/or Settings > Developer options > Verify apps over USB.
Best practice multi language website
A really simple option that works with any website where you can upload Javascript is www.multilingualizer.com
It lets you put all text for all languages onto one page and then hides the languages the user doesn't need to see. Works well.
error : expected unqualified-id before return in c++
if (chapeau) {
You forgot the ending brace to this if statement, so the subsequent else if is considered a syntax error. You need to add the brace when the if statement body is complete:
if (chapeau) {
cout << "le Professeur Violet";
}
else if (moustaches) {
cout << "le Colonel Moutarde";
}
// ...
Django: ImproperlyConfigured: The SECRET_KEY setting must not be empty
To throw another potential solution into the mix, I had a settings folder as well as a settings.py in my project dir. (I was switching back from environment-based settings files to one file. I have since reconsidered.)
Python was getting confused about whether I wanted to import project/settings.py or project/settings/__init__.py. I removed the settings dir and everything now works fine.
Undefined Symbols for architecture x86_64: Compiling problems
There's no mystery here, the linker is telling you that you haven't defined the missing symbols, and you haven't.
Similarity::Similarity() or Similarity::~Similarity() are just missing and you have defined the others incorrectly,
void Similarity::readData(Scanner& inStream){
}
not
void readData(Scanner& inStream){
}
etc. etc.
The second one is a function called readData, only the first is the readData method of the Similarity class.
To be clear about this, in Similarity.h
void readData(Scanner& inStream);
but in Similarity.cpp
void Similarity::readData(Scanner& inStream){
}
Checking cin input stream produces an integer
If istream fails to insert, it will set the fail bit.
int i = 0;
std::cin >> i; // type a and press enter
if (std::cin.fail())
{
std::cout << "I failed, try again ..." << std::endl
std::cin.clear(); // reset the failed state
}
You can set this up in a do-while loop to get the correct type (int in this case) propertly inserted.
For more information: http://augustcouncil.com/~tgibson/tutorial/iotips.html#directly
C++ String array sorting
As many here have stated, you could use std::sort to sort, but what is going to happen when you, for instance, want to sort from z-a? This code may be useful
bool cmp(string a, string b)
{
if(a.compare(b) > 0)
return true;
else
return false;
}
int main()
{
string words[] = {"this", "a", "test", "is"};
int length = sizeof(words) / sizeof(string);
sort(words, words + length, cmp);
for(int i = 0; i < length; i++)
cout << words[i] << " ";
cout << endl;
// output will be: this test is a
}
If you want to reverse the order of sorting just modify the sign in the cmp function.
Hope this is helpful :)
Cheers!!!
Reading and writing to serial port in C on Linux
I've solved my problems, so I post here the correct code in case someone needs similar stuff.
Open Port
int USB = open( "/dev/ttyUSB0", O_RDWR| O_NOCTTY );
Set parameters
struct termios tty;
struct termios tty_old;
memset (&tty, 0, sizeof tty);
/* Error Handling */
if ( tcgetattr ( USB, &tty ) != 0 ) {
std::cout << "Error " << errno << " from tcgetattr: " << strerror(errno) << std::endl;
}
/* Save old tty parameters */
tty_old = tty;
/* Set Baud Rate */
cfsetospeed (&tty, (speed_t)B9600);
cfsetispeed (&tty, (speed_t)B9600);
/* Setting other Port Stuff */
tty.c_cflag &= ~PARENB; // Make 8n1
tty.c_cflag &= ~CSTOPB;
tty.c_cflag &= ~CSIZE;
tty.c_cflag |= CS8;
tty.c_cflag &= ~CRTSCTS; // no flow control
tty.c_cc[VMIN] = 1; // read doesn't block
tty.c_cc[VTIME] = 5; // 0.5 seconds read timeout
tty.c_cflag |= CREAD | CLOCAL; // turn on READ & ignore ctrl lines
/* Make raw */
cfmakeraw(&tty);
/* Flush Port, then applies attributes */
tcflush( USB, TCIFLUSH );
if ( tcsetattr ( USB, TCSANOW, &tty ) != 0) {
std::cout << "Error " << errno << " from tcsetattr" << std::endl;
}
Write
unsigned char cmd[] = "INIT \r";
int n_written = 0,
spot = 0;
do {
n_written = write( USB, &cmd[spot], 1 );
spot += n_written;
} while (cmd[spot-1] != '\r' && n_written > 0);
It was definitely not necessary to write byte per byte, also int n_written = write( USB, cmd, sizeof(cmd) -1) worked fine.
At last, read:
int n = 0,
spot = 0;
char buf = '\0';
/* Whole response*/
char response[1024];
memset(response, '\0', sizeof response);
do {
n = read( USB, &buf, 1 );
sprintf( &response[spot], "%c", buf );
spot += n;
} while( buf != '\r' && n > 0);
if (n < 0) {
std::cout << "Error reading: " << strerror(errno) << std::endl;
}
else if (n == 0) {
std::cout << "Read nothing!" << std::endl;
}
else {
std::cout << "Response: " << response << std::endl;
}
This one worked for me. Thank you all!
How to hide command output in Bash
You can redirect stdout to /dev/null.
yum install nano > /dev/null
Or you can redirect both stdout and stderr,
yum install nano &> /dev/null.
But if the program has a quiet option, that's even better.
Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
I resolved this issue by excluding byte-buddy dependency from springfox
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger2</artifactId>
<version>2.7.0</version>
<exclusions>
<exclusion>
<groupId>net.bytebuddy</groupId>
<artifactId>byte-buddy</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger-ui</artifactId>
<version>2.7.0</version>
<exclusions>
<exclusion>
<groupId>net.bytebuddy</groupId>
<artifactId>byte-buddy</artifactId>
</exclusion>
</exclusions>
</dependency>
What is the difference between `Enum.name()` and `Enum.toString()`?
The main difference between name() and toString() is that name() is a final method, so it cannot be overridden. The toString() method returns the same value that name() does by default, but toString() can be overridden by subclasses of Enum.
Therefore, if you need the name of the field itself, use name(). If you need a string representation of the value of the field, use toString().
For instance:
public enum WeekDay {
MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY;
public String toString() {
return name().charAt(0) + name().substring(1).toLowerCase();
}
}
In this example,
WeekDay.MONDAY.name() returns "MONDAY", and
WeekDay.MONDAY.toString() returns "Monday".
WeekDay.valueOf(WeekDay.MONDAY.name()) returns WeekDay.MONDAY, but WeekDay.valueOf(WeekDay.MONDAY.toString()) throws an IllegalArgumentException.
Creating a daemon in Linux
Try using the daemon function:
#include <unistd.h>
int daemon(int nochdir, int noclose);
From the man page:
The daemon() function is for programs wishing to detach themselves from the controlling terminal and run in the background as system daemons.
If nochdir is zero, daemon() changes the calling process's current working directory to the root directory ("/"); otherwise, the current working directory is left unchanged.
If noclose is zero, daemon() redirects standard input, standard output and standard error to /dev/null; otherwise, no changes are made to these file descriptors.
Displaying a vector of strings in C++
vector.size() returns the size of a vector. You didn't put any string in the vector before the loop , so the size of the vector is 0. It will never enter the loop. First put some data in the vector and then try to add them. You can take input from the user for the number of string user wants to enter.
#include <iostream>
#include <vector>
#include <string>
#include <cctype>
using namespace std;
int main(int a, char* b [])
{
vector<string> userString;
string word;
string sentence = "";
int SIZE;
cin>>SIZE; //what will be the size of the vector
for (int i = 0; i < SIZE; i++)
{
cin >> word;
userString.push_back(word);
sentence += userString[i] + " ";
}
cout << sentence;
system("PAUSE");
return 0;
}
another thing, actually you don't have to use a vector to do this.Two strings can do the job for you.
#include <iostream>
#include <vector>
#include <string>
#include <cctype>
using namespace std;
int main(int a, char* b [])
{
// vector<string> userString;
string word;
string sentence = "";
int SIZE;
cin>>SIZE; //what will be the size of the vector
for (int i = 0; i < SIZE; i++)
{
cin >> word;
sentence += word+ " ";
}
cout << sentence;
system("PAUSE");
return 0;
}
and if you want to enter string until the user wish , code will be like this:
#include <iostream>
#include <vector>
#include <string>
#include <cctype>
using namespace std;
int main(int a, char* b [])
{
// vector<string> userString;
string word;
string sentence = "";
//int SIZE;
//cin>>SIZE; //what will be the size of the vector
while(cin>>word)
{
//cin >> word;
sentence += word+ " ";
}
cout << sentence;
// system("PAUSE");
return 0;
}
Error with multiple definitions of function
Here is a highly simplified but hopefully relevant view of what happens when you build your code in C++.
C++ splits the load of generating machine executable code in following different phases -
Preprocessing - This is where any macros -
#defines etc you might be using get expanded.Compiling - Each cpp file along with all the
#included files in that file directly or indirectly (together called a compilation unit) is converted into machine readable object code.This is where C++ also checks that all functions defined (i.e. containing a body in
{}e.g.void Foo( int x){ return Boo(x); })are referring to other functions in a valid manner.The way it does that is by insisting that you provide at least a declaration of these other functions (e.g.
void Boo(int);) before you call it so it can check that you are calling it properly among other things. This can be done either directly in the cpp file where it is called or usually in an included header file.Note that only the machine code that corresponds to functions defined in this cpp and included files gets built as the object (binary) version of this compilation unit (e.g. Foo) and not the ones that are merely declared (e.g. Boo).
Linking - This is the stage where C++ goes hunting for stuff declared and called in each compilation unit and links it to the places where it is getting called. Now if there was no definition found of this function the linker gives up and errors out. Similarly if it finds multiple definitions of the same function signature (essentially the name and parameter types it takes) it also errors out as it considers it ambiguous and doesn't want to pick one arbitrarily.
The latter is what is happening in your case. By doing a #include of the fun.cpp file, both fun.cpp and mainfile.cpp have a definition of funct() and the linker doesn't know which one to use in your program and is complaining about it.
The fix as Vaughn mentioned above is to not include the cpp file with the definition of funct() in mainfile.cpp and instead move the declaration of funct() in a separate header file and include that in mainline.cpp. This way the compiler will get the declaration of funct() to work with and the linker would get just one definition of funct() from fun.cpp and will use it with confidence.
How to check if a file exists before creating a new file
Try this (copied-ish from Erik Garrison: https://stackoverflow.com/a/3071528/575530)
#include <sys/stat.h>
bool FileExists(char* filename)
{
struct stat fileInfo;
return stat(filename, &fileInfo) == 0;
}
stat returns 0 if the file exists and -1 if not.
C++ initial value of reference to non-const must be an lvalue
When you call test with &nKByte, the address-of operator creates a temporary value, and you can't normally have references to temporary values because they are, well, temporary.
Either do not use a reference for the argument, or better yet don't use a pointer.
WCF Service, the type provided as the service attribute values…could not be found
I just hit this issue myself, and neither this nor any of the other answers on the net solved my issue. For me it was a strange one whereby the virtual directory had been created on a different branch in another source control server (basically, we upgraded from TFS 2010 to 2013) and the solution somehow remembered it's mapping.
Anyway, I clicked the "Create Virtual Directory" button again, in the Properties of the Service project. It gave me a message about being mapped to a different folder and would I like to update it. I clicked yes, and that fixed the issue.
Class has no member named
The reason that the error is occuring is because all the files are not being recognized as being in the same project directory. The easiest way to fix this is to simply create a new project.
File -> Project -> Console application -> Next -> select C or C++ -> Name the project and select the folder to create the project in -> then click finish.
Then to create the class and header files by clicking New -> Class. Give the class a name and uncheck "Use relative path." Make sure you are creating the class and header file in the same project folder.
After these steps, the left side of the IDE will display the Sources and Headers folders, with main.cpp, theclassname.cpp, and theclassname.h all conviently arranged.
How to draw interactive Polyline on route google maps v2 android
Using the google maps projection api to draw the polylines on an overlay view enables us to do a lot of things. Check this repo that has an example.
How to fill Matrix with zeros in OpenCV?
I presume you are talking about filling zeros of some existing mat? How about this? :)
mat *= 0;
What is a "cache-friendly" code?
In addition to @Marc Claesen's answer, I think that an instructive classic example of cache-unfriendly code is code that scans a C bidimensional array (e.g. a bitmap image) column-wise instead of row-wise.
Elements that are adjacent in a row are also adjacent in memory, thus accessing them in sequence means accessing them in ascending memory order; this is cache-friendly, since the cache tends to prefetch contiguous blocks of memory.
Instead, accessing such elements column-wise is cache-unfriendly, since elements on the same column are distant in memory from each other (in particular, their distance is equal to the size of the row), so when you use this access pattern you are jumping around in memory, potentially wasting the effort of the cache of retrieving the elements nearby in memory.
And all that it takes to ruin the performance is to go from
// Cache-friendly version - processes pixels which are adjacent in memory
for(unsigned int y=0; y<height; ++y)
{
for(unsigned int x=0; x<width; ++x)
{
... image[y][x] ...
}
}
to
// Cache-unfriendly version - jumps around in memory for no good reason
for(unsigned int x=0; x<width; ++x)
{
for(unsigned int y=0; y<height; ++y)
{
... image[y][x] ...
}
}
This effect can be quite dramatic (several order of magnitudes in speed) in systems with small caches and/or working with big arrays (e.g. 10+ megapixels 24 bpp images on current machines); for this reason, if you have to do many vertical scans, often it's better to rotate the image of 90 degrees first and perform the various analysis later, limiting the cache-unfriendly code just to the rotation.
How to return a string from a C++ function?
Assign something to your strings. This will definitely help.
URL rewriting with PHP
this is an .htaccess file that forward almost all to index.php
# if a directory or a file exists, use it directly
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-l
RewriteCond %{REQUEST_URI} !-l
RewriteCond %{REQUEST_FILENAME} !\.(ico|css|png|jpg|gif|js)$ [NC]
# otherwise forward it to index.php
RewriteRule . index.php
then is up to you parse $_SERVER["REQUEST_URI"] and route to picture.php or whatever
Evaluate a string with a switch in C++
As said before, switch can be used only with integer values. So, you just need to convert your "case" values to integer. You can achieve it by using constexpr from c++11, thus some calls of constexpr functions can be calculated in compile time.
something like that...
switch (str2int(s))
{
case str2int("Value1"):
break;
case str2int("Value2"):
break;
}
where str2int is like (implementation from here):
constexpr unsigned int str2int(const char* str, int h = 0)
{
return !str[h] ? 5381 : (str2int(str, h+1) * 33) ^ str[h];
}
Another example, the next function can be calculated in compile time:
constexpr int factorial(int n)
{
return n <= 1 ? 1 : (n * factorial(n-1));
}
int f5{factorial(5)};
// Compiler will run factorial(5)
// and f5 will be initialized by this value.
// so programm instead of wasting time for running function,
// just will put the precalculated constant to f5
Find largest and smallest number in an array
You assign to big and small before the array is initialized, i.e., big and small assume the value of whatever is on the stack at this point. As they are just plain value types and no references, they won't assume a new value once values[0] is written to via cin >>.
Just move the assignment after your first loop and it should be fine.
Regular expression replace in C#
Try this::
sb_trim = Regex.Replace(stw, @"(\D+)\s+\$([\d,]+)\.\d+\s+(.)",
m => string.Format(
"{0},{1},{2}",
m.Groups[1].Value,
m.Groups[2].Value.Replace(",", string.Empty),
m.Groups[3].Value));
This is about as clean an answer as you'll get, at least with regexes.
(\D+): First capture group. One or more non-digit characters.\s+\$: One or more spacing characters, then a literal dollar sign ($).([\d,]+): Second capture group. One or more digits and/or commas.\.\d+: Decimal point, then at least one digit.\s+: One or more spacing characters.(.): Third capture group. Any non-line-breaking character.
The second capture group additionally needs to have its commas stripped. You could do this with another regex, but it's really unnecessary and bad for performance. This is why we need to use a lambda expression and string format to piece together the replacement. If it weren't for that, we could just use this as the replacement, in place of the lambda expression:
"$1,$2,$3"
splitting a string into an array in C++ without using vector
#include <iostream>
#include <sstream>
#include <vector>
using namespace std;
int main() {
string s1="split on whitespace";
istringstream iss(s1);
vector<string> result;
for(string s;iss>>s;)
result.push_back(s);
int n=result.size();
for(int i=0;i<n;i++)
cout<<result[i]<<endl;
return 0;
}
Output:-
split
on
whitespace
Parsing huge logfiles in Node.js - read in line-by-line
I searched for a solution to parse very large files (gbs) line by line using a stream. All the third-party libraries and examples did not suit my needs since they processed the files not line by line (like 1 , 2 , 3 , 4 ..) or read the entire file to memory
The following solution can parse very large files, line by line using stream & pipe. For testing I used a 2.1 gb file with 17.000.000 records. Ram usage did not exceed 60 mb.
First, install the event-stream package:
npm install event-stream
Then:
var fs = require('fs')
, es = require('event-stream');
var lineNr = 0;
var s = fs.createReadStream('very-large-file.csv')
.pipe(es.split())
.pipe(es.mapSync(function(line){
// pause the readstream
s.pause();
lineNr += 1;
// process line here and call s.resume() when rdy
// function below was for logging memory usage
logMemoryUsage(lineNr);
// resume the readstream, possibly from a callback
s.resume();
})
.on('error', function(err){
console.log('Error while reading file.', err);
})
.on('end', function(){
console.log('Read entire file.')
})
);
Please let me know how it goes!
Pointer-to-pointer dynamic two-dimensional array
This code works well with very few requirements on external libraries and shows a basic use of int **array.
This answer shows that each array is dynamically sized, as well as how to assign a dynamically sized leaf array into the dynamically sized branch array.
This program takes arguments from STDIN in the following format:
2 2
3 1 5 4
5 1 2 8 9 3
0 1
1 3
Code for program below...
#include <iostream>
int main()
{
int **array_of_arrays;
int num_arrays, num_queries;
num_arrays = num_queries = 0;
std::cin >> num_arrays >> num_queries;
//std::cout << num_arrays << " " << num_queries;
//Process the Arrays
array_of_arrays = new int*[num_arrays];
int size_current_array = 0;
for (int i = 0; i < num_arrays; i++)
{
std::cin >> size_current_array;
int *tmp_array = new int[size_current_array];
for (int j = 0; j < size_current_array; j++)
{
int tmp = 0;
std::cin >> tmp;
tmp_array[j] = tmp;
}
array_of_arrays[i] = tmp_array;
}
//Process the Queries
int x, y;
x = y = 0;
for (int q = 0; q < num_queries; q++)
{
std::cin >> x >> y;
//std::cout << "Current x & y: " << x << ", " << y << "\n";
std::cout << array_of_arrays[x][y] << "\n";
}
return 0;
}
It's a very simple implementation of int main and relies solely on std::cin and std::cout. Barebones, but good enough to show how to work with simple multidimensional arrays.
C++ printing boolean, what is displayed?
0 will get printed.
As in C++ true refers to 1 and false refers to 0.
In case, you want to print false instead of 0,then you have to sets the boolalpha format flag for the str stream.
When the boolalpha format flag is set, bool values are inserted/extracted by their textual representation: either true or false, instead of integral values.
#include <iostream>
int main()
{
std::cout << std::boolalpha << false << std::endl;
}
output:
false
C++ printing spaces or tabs given a user input integer
Simply add spaces for { 2 3 4 5 6 } like these:
cout<<"{";
for(){
cout<<" "<<n; //n is the element to print !
}
cout<<" }";
How can I create objects while adding them into a vector?
I know the thread is already all, but as I was checking through I've come up with a solution (code listed below). Hope it can help.
#include <iostream>
#include <vector>
class Box
{
public:
static int BoxesTotal;
static int BoxesEver;
int Id;
Box()
{
++BoxesTotal;
++BoxesEver;
Id = BoxesEver;
std::cout << "Box (" << Id << "/" << BoxesTotal << "/" << BoxesEver << ") initialized." << std::endl;
}
~Box()
{
std::cout << "Box (" << Id << "/" << BoxesTotal << "/" << BoxesEver << ") ended." << std::endl;
--BoxesTotal;
}
};
int Box::BoxesTotal = 0;
int Box::BoxesEver = 0;
int main(int argc, char* argv[])
{
std::cout << "Objects (Boxes) example." << std::endl;
std::cout << "------------------------" << std::endl;
std::vector <Box*> BoxesTab;
Box* Indicator;
for (int i = 1; i<4; ++i)
{
std::cout << "i = " << i << ":" << std::endl;
Box* Indicator = new(Box);
BoxesTab.push_back(Indicator);
std::cout << "Adres Blowera: " << BoxesTab[i-1] << std::endl;
}
std::cout << "Summary" << std::endl;
std::cout << "-------" << std::endl;
for (int i=0; i<3; ++i)
{
std::cout << "Adres Blowera: " << BoxesTab[i] << std::endl;
}
std::cout << "Deleting" << std::endl;
std::cout << "--------" << std::endl;
for (int i=0; i<3; ++i)
{
std::cout << "Deleting Box: " << i+1 << " (" << BoxesTab[i] << ") " << std::endl;
Indicator = (BoxesTab[i]);
delete(Indicator);
}
return 0;
}
And the result it produces is:
Objects (Boxes) example.
------------------------
i = 1:
Box (1/1/1) initialized.
Adres Blowera: 0xdf8ca0
i = 2:
Box (2/2/2) initialized.
Adres Blowera: 0xdf8ce0
i = 3:
Box (3/3/3) initialized.
Adres Blowera: 0xdf8cc0
Summary
-------
Adres Blowera: 0xdf8ca0
Adres Blowera: 0xdf8ce0
Adres Blowera: 0xdf8cc0
Deleting
--------
Deleting Box: 1 (0xdf8ca0)
Box (1/3/3) ended.
Deleting Box: 2 (0xdf8ce0)
Box (2/2/3) ended.
Deleting Box: 3 (0xdf8cc0)
Box (3/1/3) ended.
C++ calling base class constructors
When objects are constructed, it is always first construct base class subobject, therefore, base class constructor is called first, then call derived class constructors. The reason is that derived class objects contain subobjects inherited from base class. You always need to call the base class constructor to initialze base class subobjects. We usually call the base class constructor on derived class's member initialization list. If you do not call base class constructor explicitly, the compile will call the default constructor of base class to initialize base class subobject. However, implicit call on default constructor does not necessary work at all times (for example, if base class defines a constructor that could not be called without arguments).
When objects are out of scope, it will first call destructor of derived class,then call destructor of base class.
What is the simplest way to write the contents of a StringBuilder to a text file in .NET 1.1?
If you need to write line by line from string builder
StringBuilder sb = new StringBuilder();
sb.AppendLine("New Line!");
using (var sw = new StreamWriter(@"C:\MyDir\MyNewTextFile.txt", true))
{
sw.Write(sb.ToString());
}
If you need to write all text as single line from string builder
StringBuilder sb = new StringBuilder();
sb.Append("New Text line!");
using (var sw = new StreamWriter(@"C:\MyDir\MyNewTextFile.txt", true))
{
sw.Write(sb.ToString());
}
Exception in thread "main" java.util.NoSuchElementException
You close the second Scanner which closes the underlying InputStream, therefore the first Scanner can no longer read from the same InputStream and a NoSuchElementException results.
The solution: For console apps, use a single Scanner to read from System.in.
Aside: As stated already, be aware that Scanner#nextInt does not consume newline characters. Ensure that these are consumed before attempting to call nextLine again by using Scanner#newLine().
See: Do not create multiple buffered wrappers on a single InputStream
How to write std::string to file?
Assuming you're using a std::ofstream to write to file, the following snippet will write a std::string to file in human readable form:
std::ofstream file("filename");
std::string my_string = "Hello text in file\n";
file << my_string;
How to Code Double Quotes via HTML Codes
There is no difference, in browsers that you can find in the wild these days (that is, excluding things like Netscape 1 that you might find in a museum). There is no reason to suspect that any of them would be deprecated ever, especially since they are all valid in XML, in HTML 4.01, and in HTML5 CR.
There is no reason to use any of them, as opposite to using the Ascii quotation mark (") directly, except in the very special case where you have an attribute value enclosed in such marks and you would like to use the mark inside the value (e.g., title="Hello "world""), and even then, there are almost always better options (like title='Hello "word"' or title="Hello “word”".
If you want to use “smart” quotation marks instead, then it’s a different question, and none of the constructs has anything to do with them. Some people expect notations like " to produce “smart” quotes, but it is easy to see that they don’t; the notations unambiguously denote the Ascii quote ("), as used in computer languages.
no matching function for call to ' '
You are passing pointers (Complex*) when your function takes references (const Complex&). A reference and a pointer are entirely different things. When a function expects a reference argument, you need to pass it the object directly. The reference only means that the object is not copied.
To get an object to pass to your function, you would need to dereference your pointers:
Complex::distanta(*firstComplexNumber, *secondComplexNumber);
Or get your function to take pointer arguments.
However, I wouldn't really suggest either of the above solutions. Since you don't need dynamic allocation here (and you are leaking memory because you don't delete what you have newed), you're better off not using pointers in the first place:
Complex firstComplexNumber(81, 93);
Complex secondComplexNumber(31, 19);
Complex::distanta(firstComplexNumber, secondComplexNumber);
How to get position of a certain element in strings vector, to use it as an index in ints vector?
To get a position of an element in a vector knowing an iterator pointing to the element, simply subtract v.begin() from the iterator:
ptrdiff_t pos = find(Names.begin(), Names.end(), old_name_) - Names.begin();
Now you need to check pos against Names.size() to see if it is out of bounds or not:
if(pos >= Names.size()) {
//old_name_ not found
}
vector iterators behave in ways similar to array pointers; most of what you know about pointer arithmetic can be applied to vector iterators as well.
Starting with C++11 you can use std::distance in place of subtraction for both iterators and pointers:
ptrdiff_t pos = distance(Names.begin(), find(Names.begin(), Names.end(), old_name_));
how to print a string to console in c++
All you have to do is add:
#include <string>
using namespace std;
at the top. (BTW I know this was posted in 2013 but I just wanted to answer)
How to change line width in ggplot?
Whilst @Didzis has the correct answer, I will expand on a few points
Aesthetics can be set or mapped within a ggplot call.
An aesthetic defined within aes(...) is mapped from the data, and a legend created.
An aesthetic may also be set to a single value, by defining it outside aes().
As far as I can tell, what you want is to set size to a single value, not map within the call to aes()
When you call aes(size = 2) it creates a variable called `2` and uses that to create the size, mapping it from a constant value as it is within a call to aes (thus it appears in your legend).
Using size = 1 (and without reg_labeller which is perhaps defined somewhere in your script)
Figure29 +
geom_line(aes(group=factor(tradlib)),size=1) +
facet_grid(regionsFull~., scales="free_y") +
scale_colour_brewer(type = "div") +
theme(axis.text.x = element_text(
colour = 'black', angle = 90, size = 13,
hjust = 0.5, vjust = 0.5),axis.title.x=element_blank()) +
ylab("FSI (%Change)") +
theme(axis.text.y = element_text(colour = 'black', size = 12),
axis.title.y = element_text(size = 12,
hjust = 0.5, vjust = 0.2)) +
theme(strip.text.y = element_text(size = 11, hjust = 0.5,
vjust = 0.5, face = 'bold'))
and with size = 2
Figure29 +
geom_line(aes(group=factor(tradlib)),size=2) +
facet_grid(regionsFull~., scales="free_y") +
scale_colour_brewer(type = "div") +
theme(axis.text.x = element_text(colour = 'black', angle = 90,
size = 13, hjust = 0.5, vjust =
0.5),axis.title.x=element_blank()) +
ylab("FSI (%Change)") +
theme(axis.text.y = element_text(colour = 'black', size = 12),
axis.title.y = element_text(size = 12,
hjust = 0.5, vjust = 0.2)) +
theme(strip.text.y = element_text(size = 11, hjust = 0.5,
vjust = 0.5, face = 'bold'))
You can now define the size to work appropriately with the final image size and device type.
Linker Error C++ "undefined reference "
Your error shows you are not compiling file with the definition of the insert function. Update your command to include the file which contains the definition of that function and it should work.
How to initialize const member variable in a class?
If a member is a Array it will be a little bit complex than the normal is:
class C
{
static const int ARRAY[10];
public:
C() {}
};
const unsigned int C::ARRAY[10] = {0,1,2,3,4,5,6,7,8,9};
or
int* a = new int[N];
// fill a
class C {
const std::vector<int> v;
public:
C():v(a, a+N) {}
};
C++ callback using class member
Instead of having static methods and passing around a pointer to the class instance, you could use functionality in the new C++11 standard: std::function and std::bind:
#include <functional>
class EventHandler
{
public:
void addHandler(std::function<void(int)> callback)
{
cout << "Handler added..." << endl;
// Let's pretend an event just occured
callback(1);
}
};
The addHandler method now accepts a std::function argument, and this "function object" have no return value and takes an integer as argument.
To bind it to a specific function, you use std::bind:
class MyClass
{
public:
MyClass();
// Note: No longer marked `static`, and only takes the actual argument
void Callback(int x);
private:
int private_x;
};
MyClass::MyClass()
{
using namespace std::placeholders; // for `_1`
private_x = 5;
handler->addHandler(std::bind(&MyClass::Callback, this, _1));
}
void MyClass::Callback(int x)
{
// No longer needs an explicit `instance` argument,
// as `this` is set up properly
cout << x + private_x << endl;
}
You need to use std::bind when adding the handler, as you explicitly needs to specify the otherwise implicit this pointer as an argument. If you have a free-standing function, you don't have to use std::bind:
void freeStandingCallback(int x)
{
// ...
}
int main()
{
// ...
handler->addHandler(freeStandingCallback);
}
Having the event handler use std::function objects, also makes it possible to use the new C++11 lambda functions:
handler->addHandler([](int x) { std::cout << "x is " << x << '\n'; });
java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
For what it's worth; I had this error on a app that was running services in the background. On one of them a timeout dialog had to be shown to the user. That dialog was the issue causing this error if the app was no longer running in the foreground.
In our case showing the dialog wasn't useful when app was in background so we just kept track of that (boolean flagged onPause en onResume) and then only show the dialog when the app is actually visible to the user.
Meaning of "[: too many arguments" error from if [] (square brackets)
Some times If you touch the keyboard accidentally and removed a space.
if [ "$myvar" = "something"]; then
do something
fi
Will trigger this error message. Note the space before ']' is required.
how to set width for PdfPCell in ItextSharp
try this code I think it is more optimal.
HeaderRow is used to repeat the header of the table for each new page automatically
BaseFont bfTimes = BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.CP1252, false);
iTextSharp.text.Font times = new iTextSharp.text.Font(bfTimes, 6, iTextSharp.text.Font.NORMAL, iTextSharp.text.BaseColor.BLACK);
PdfPTable table = new PdfPTable(10) { HorizontalAlignment = Element.ALIGN_CENTER, WidthPercentage = 100, HeaderRows = 2 };
table.SetWidths(new float[] { 2f, 6f, 6f, 3f, 5f, 8f, 5f, 5f, 5f, 5f });
table.AddCell(new PdfPCell(new Phrase("SER.\nNO.", times)) { Rowspan = 2, GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("TYPE OF SHIPPING", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("ORDER NO.", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("QTY.", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("DISCHARGE PPORT", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("DESCRIPTION OF GOODS", times)) { Rowspan = 2, GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("LINE DOC. RECL DATE", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("CLEARANCE DATE", times)) { Rowspan = 2, GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("CUSTOM PERMIT NO.", times)) { Rowspan = 2, GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("DISPATCH DATE", times)) { Rowspan = 2, GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("AWB/BL NO.", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("COMPLEX NAME", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("G. W. Kgs.", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("DESTINATION", times)) { GrayFill = 0.95f });
table.AddCell(new PdfPCell(new Phrase("OWNER DOC. RECL DATE", times)) { GrayFill = 0.95f });
Read text file into string. C++ ifstream
getline(fin, buffer, '\n')
where fin is opened file(ifstream object) and buffer is of string/char type where you want to copy line.
Downloading MySQL dump from command line
For Windows users you can go to your mysql folder to run the command
e.g.
cd c:\wamp64\bin\mysql\mysql5.7.26\bin
mysqldump -u root -p databasename > dbname_dump.sql
How would I stop a while loop after n amount of time?
I have read this but I just want to ask something, wouldn't something like I have written work at all? I have done the testing for 5,10 and 20 seconds. Its time isn't exactly accurate but they are really close to the actual values.
import time
begin_time=0
while begin_time<5:
begin_time+=1
time.sleep(1.0)
print("The Work is Done")
Java enum - why use toString instead of name
Use name() when you want to make a comparison or use the hardcoded value for some internal use in your code.
Use toString() when you want to present information to a user (including a developper looking at a log). Never rely in your code on toString() giving a specific value. Never test it against a specific string. If your code breaks when someone correctly changes the toString() return, then it was already broken.
From the javadoc (emphasis mine) :
Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
Deleting a pointer in C++
- You are trying to delete a variable allocated on the stack. You can not do this
- Deleting a pointer does not destruct a pointer actually, just the memory occupied is given back to the OS. You can access it untill the memory is used for another variable, or otherwise manipulated. So it is good practice to set a pointer to NULL (0) after deleting.
- Deleting a NULL pointer does not delete anything.
The #include<iostream> exists, but I get an error: identifier "cout" is undefined. Why?
cout is in std namespace, you shall use std::cout in your code.
And you shall not add using namespace std; in your header file, it's bad to mix your code with std namespace, especially don't add it in header file.
Read input numbers separated by spaces
I would recommend reading in the line into a string, then splitting it based on the spaces. For this, you can use the getline(...) function. The trick is having a dynamic sized data structure to hold the strings once it's split. Probably the easiest to use would be a vector.
#include <string>
#include <vector>
...
string rawInput;
vector<String> numbers;
while( getline( cin, rawInput, ' ' ) )
{
numbers.push_back(rawInput);
}
So say the input looks like this:
Enter a number, or numbers separated by a space, between 1 and 1000.
10 5 20 1 200 7
You will now have a vector, numbers, that contains the elements: {"10","5","20","1","200","7"}.
Note that these are still strings, so not useful in arithmetic. To convert them to integers, we use a combination of the STL function, atoi(...), and because atoi requires a c-string instead of a c++ style string, we use the string class' c_str() member function.
while(!numbers.empty())
{
string temp = numbers.pop_back();//removes the last element from the string
num = atoi( temp.c_str() ); //re-used your 'num' variable from your code
...//do stuff
}
Now there's some problems with this code. Yes, it runs, but it is kind of clunky, and it puts the numbers out in reverse order. Lets re-write it so that it is a little more compact:
#include <string>
...
string rawInput;
cout << "Enter a number, or numbers separated by a space, between 1 and 1000." << endl;
while( getline( cin, rawInput, ' ') )
{
num = atoi( rawInput.c_str() );
...//do your stuff
}
There's still lots of room for improvement with error handling (right now if you enter a non-number the program will crash), and there's infinitely more ways to actually handle the input to get it in a usable number form (the joys of programming!), but that should give you a comprehensive start. :)
Note: I had the reference pages as links, but I cannot post more than two since I have less than 15 posts :/
Edit: I was a little bit wrong about the atoi behavior; I confused it with Java's string->Integer conversions which throw a Not-A-Number exception when given a string that isn't a number, and then crashes the program if the exception isn't handled. atoi(), on the other hand, returns 0, which is not as helpful because what if 0 is the number they entered? Let's make use of the isdigit(...) function. An important thing to note here is that c++ style strings can be accessed like an array, meaning rawInput[0] is the first character in the string all the way up to rawInput[length - 1].
#include <string>
#include <ctype.h>
...
string rawInput;
cout << "Enter a number, or numbers separated by a space, between 1 and 1000." << endl;
while( getline( cin, rawInput, ' ') )
{
bool isNum = true;
for(int i = 0; i < rawInput.length() && isNum; ++i)
{
isNum = isdigit( rawInput[i]);
}
if(isNum)
{
num = atoi( rawInput.c_str() );
...//do your stuff
}
else
cout << rawInput << " is not a number!" << endl;
}
The boolean (true/false or 1/0 respectively) is used as a flag for the for-loop, which steps through each character in the string and checks to see if it is a 0-9 digit. If any character in the string is not a digit, the loop will break during it's next execution when it gets to the condition "&& isNum" (assuming you've covered loops already). Then after the loop, isNum is used to determine whether to do your stuff, or to print the error message.
More than 1 row in <Input type="textarea" />
Although <input> ignores the rows attribute, you can take advantage of the fact that <textarea> doesn't have to be inside <form> tags, but can still be a part of a form by referencing the form's id:
<form method="get" id="testformid">
<input type="submit" />
</form>
<textarea form ="testformid" name="taname" id="taid" cols="35" wrap="soft"></textarea>
Of course, <textarea> now appears below "submit" button, but maybe you'll find a way to reposition it.
C++ correct way to return pointer to array from function
Your code is OK. Note though that if you return a pointer to an array, and that array goes out of scope, you should not use that pointer anymore. Example:
int* test (void)
{
int out[5];
return out;
}
The above will never work, because out does not exist anymore when test() returns. The returned pointer must not be used anymore. If you do use it, you will be reading/writing to memory you shouldn't.
In your original code, the arr array goes out of scope when main() returns. Obviously that's no problem, since returning from main() also means that your program is terminating.
If you want something that will stick around and cannot go out of scope, you should allocate it with new:
int* test (void)
{
int* out = new int[5];
return out;
}
The returned pointer will always be valid. Remember do delete it again when you're done with it though, using delete[]:
int* array = test();
// ...
// Done with the array.
delete[] array;
Deleting it is the only way to reclaim the memory it uses.
How to clone object in C++ ? Or Is there another solution?
If your object is not polymorphic (and a stack implementation likely isn't), then as per other answers here, what you want is the copy constructor. Please note that there are differences between copy construction and assignment in C++; if you want both behaviors (and the default versions don't fit your needs), you'll have to implement both functions.
If your object is polymorphic, then slicing can be an issue and you might need to jump through some extra hoops to do proper copying. Sometimes people use as virtual method called clone() as a helper for polymorphic copying.
Finally, note that getting copying and assignment right, if you need to replace the default versions, is actually quite difficult. It is usually better to set up your objects (via RAII) in such a way that the default versions of copy/assign do what you want them to do. I highly recommend you look at Meyer's Effective C++, especially at items 10,11,12.
Expression must be a modifiable lvalue
In C, you will also experience the same error if you declare a:
char array[size];
and than try to assign a value without specifying an index position:
array = '\0';
By doing:
array[index] = '0\';
You're specifying the accessible/modifiable address previously declared.
Eclipse CDT: no rule to make target all
Sometimes if you are making a target via make files double check that all c files are named correctly with correct file structure.
How does the modulus operator work?
It gives you the remainder of a division.
int c=11, d=5;
cout << (c/d) * d + c % d; // gives you the value of c
Dividing two integers to produce a float result
Cast the operands to floats:
float ans = (float)a / (float)b;
Reference member variables as class members
Member references are usually considered bad. They make life hard compared to member pointers. But it's not particularly unsual, nor is it some special named idiom or thing. It's just aliasing.
Pointer to incomplete class type is not allowed
Check out if you are missing some import.
How to print Unicode character in C++?
In Linux, I can just do:
std::cout << "?";
I just copy-pasted characters from here and it didn't fail for at least the random sample that I tried on.
What is the difference between "::" "." and "->" in c++
1.-> for accessing object member variables and methods via pointer to object
Foo *foo = new Foo();
foo->member_var = 10;
foo->member_func();
2.. for accessing object member variables and methods via object instance
Foo foo;
foo.member_var = 10;
foo.member_func();
3.:: for accessing static variables and methods of a class/struct or namespace. It can also be used to access variables and functions from another scope (actually class, struct, namespace are scopes in that case)
int some_val = Foo::static_var;
Foo::static_method();
int max_int = std::numeric_limits<int>::max();
How do I replace a double-quote with an escape-char double-quote in a string using JavaScript?
Try this:
str.replace("\"", "\\\""); // (Escape backslashes and embedded double-quotes)
Or, use single-quotes to quote your search and replace strings:
str.replace('"', '\\"'); // (Still need to escape the backslash)
As pointed out by helmus, if the first parameter passed to .replace() is a string it will only replace the first occurrence. To replace globally, you have to pass a regex with the g (global) flag:
str.replace(/"/g, "\\\"");
// or
str.replace(/"/g, '\\"');
But why are you even doing this in JavaScript? It's OK to use these escape characters if you have a string literal like:
var str = "Dude, he totally said that \"You Rock!\"";
But this is necessary only in a string literal. That is, if your JavaScript variable is set to a value that a user typed in a form field you don't need to this escaping.
Regarding your question about storing such a string in an SQL database, again you only need to escape the characters if you're embedding a string literal in your SQL statement - and remember that the escape characters that apply in SQL aren't (usually) the same as for JavaScript. You'd do any SQL-related escaping server-side.
Cannot create JDBC driver of class ' ' for connect URL 'null' : I do not understand this exception
I was getting this problem because I put context.xml into the wrong path:
./src/main/resources/META-INF/context.xml
The correct path was:
./src/main/webapp/META-INF/context.xml
C++ -- expected primary-expression before ' '
You should not be repeating the string part when sending parameters.
int wordLength = wordLengthFunction(word); //you do not put string word here.
How can I output the value of an enum class in C++11
(I'm not allowed to comment yet.) I would suggest the following improvements to the already great answer of James McNellis:
template <typename Enumeration>
constexpr auto as_integer(Enumeration const value)
-> typename std::underlying_type<Enumeration>::type
{
static_assert(std::is_enum<Enumeration>::value, "parameter is not of type enum or enum class");
return static_cast<typename std::underlying_type<Enumeration>::type>(value);
}
with
constexpr: allowing me to use an enum member value as compile-time array sizestatic_assert+is_enum: to 'ensure' compile-time that the function does sth. with enumerations only, as suggested
By the way I'm asking myself: Why should I ever use enum class when I would like to assign number values to my enum members?! Considering the conversion effort.
Perhaps I would then go back to ordinary enum as I suggested here: How to use enums as flags in C++?
Yet another (better) flavor of it without static_assert, based on a suggestion of @TobySpeight:
template <typename Enumeration>
constexpr std::enable_if_t<std::is_enum<Enumeration>::value,
std::underlying_type_t<Enumeration>> as_number(const Enumeration value)
{
return static_cast<std::underlying_type_t<Enumeration>>(value);
}
Pass a simple string from controller to a view MVC3
Why not create a viewmodel with a simple string parameter and then pass that to the view? It has the benefit of being extensible (i.e. you can then add any other things you may want to set in your controller) and it's fairly simple.
public class MyViewModel
{
public string YourString { get; set; }
}
In the view
@model MyViewModel
@Html.Label(model => model.YourString)
In the controller
public ActionResult Index()
{
myViewModel = new MyViewModel();
myViewModel.YourString = "However you are setting this."
return View(myViewModel)
}
Multi-dimensional arrays in Bash
Independent of the shell being used (sh, ksh, bash, ...) the following approach works pretty well for n-dimensional arrays (the sample covers a 2-dimensional array).
In the sample the line-separator (1st dimension) is the space character. For introducing a field separator (2nd dimension) the standard unix tool tr is used. Additional separators for additional dimensions can be used in the same way.
Of course the performance of this approach is not very well, but if performance is not a criteria this approach is quite generic and can solve many problems:
array2d="1.1:1.2:1.3 2.1:2.2 3.1:3.2:3.3:3.4"
function process2ndDimension {
for dimension2 in $*
do
echo -n $dimension2 " "
done
echo
}
function process1stDimension {
for dimension1 in $array2d
do
process2ndDimension `echo $dimension1 | tr : " "`
done
}
process1stDimension
The output of that sample looks like this:
1.1 1.2 1.3
2.1 2.2
3.1 3.2 3.3 3.4
Why is processing a sorted array faster than processing an unsorted array?
In the same line (I think this was not highlighted by any answer) it's good to mention that sometimes (specially in software where the performance matters—like in the Linux kernel) you can find some if statements like the following:
if (likely( everything_is_ok ))
{
/* Do something */
}
or similarly:
if (unlikely(very_improbable_condition))
{
/* Do something */
}
Both likely() and unlikely() are in fact macros that are defined by using something like the GCC's __builtin_expect to help the compiler insert prediction code to favour the condition taking into account the information provided by the user. GCC supports other builtins that could change the behavior of the running program or emit low level instructions like clearing the cache, etc. See this documentation that goes through the available GCC's builtins.
Normally this kind of optimizations are mainly found in hard-real time applications or embedded systems where execution time matters and it's critical. For example, if you are checking for some error condition that only happens 1/10000000 times, then why not inform the compiler about this? This way, by default, the branch prediction would assume that the condition is false.
How to check if JavaScript object is JSON
Try this
if ( typeof is_json != "function" )
function is_json( _obj )
{
var _has_keys = 0 ;
for( var _pr in _obj )
{
if ( _obj.hasOwnProperty( _pr ) && !( /^\d+$/.test( _pr ) ) )
{
_has_keys = 1 ;
break ;
}
}
return ( _has_keys && _obj.constructor == Object && _obj.constructor != Array ) ? 1 : 0 ;
}
It works for the example below
var _a = { "name" : "me",
"surname" : "I",
"nickname" : {
"first" : "wow",
"second" : "super",
"morelevel" : {
"3level1" : 1,
"3level2" : 2,
"3level3" : 3
}
}
} ;
var _b = [ "name", "surname", "nickname" ] ;
var _c = "abcdefg" ;
console.log( is_json( _a ) );
console.log( is_json( _b ) );
console.log( is_json( _c ) );
OpenMP set_num_threads() is not working
Besides calling omp_get_num_threads() outside of the parallel region in your case, calling omp_set_num_threads() still doesn't guarantee that the OpenMP runtime will use exactly the specified number of threads. omp_set_num_threads() is used to override the value of the environment variable OMP_NUM_THREADS and they both control the upper limit of the size of the thread team that OpenMP would spawn for all parallel regions (in the case of OMP_NUM_THREADS) or for any consequent parallel region (after a call to omp_set_num_threads()). There is something called dynamic teams that could still pick smaller number of threads if the run-time system deems it more appropriate. You can disable dynamic teams by calling omp_set_dynamic(0) or by setting the environment variable OMP_DYNAMIC to false.
To enforce a given number of threads you should disable dynamic teams and specify the desired number of threads with either omp_set_num_threads():
omp_set_dynamic(0); // Explicitly disable dynamic teams
omp_set_num_threads(4); // Use 4 threads for all consecutive parallel regions
#pragma omp parallel ...
{
... 4 threads used here ...
}
or with the num_threads OpenMP clause:
omp_set_dynamic(0); // Explicitly disable dynamic teams
// Spawn 4 threads for this parallel region only
#pragma omp parallel ... num_threads(4)
{
... 4 threads used here ...
}
The type or namespace name does not exist in the namespace 'System.Web.Mvc'
I had the same problem, but in my case was originated by other factor. I write this to help other people with the same problem. I have a solutions with multiple projects. two of them work with the System.Web.Mvc, Normally our reference was pointing to external packages where we controlled the used version. For some reason one of the project reference goes to GAC and point to the GAC dll (version 4.0.0.1) and the program got the error. To correct it:
Simple check if the references to System.Web.Mvc point to the same dll in the same directory path.
I hope that help.
static and extern global variables in C and C++
Global variables are not extern nor static by default on C and C++.
When you declare a variable as static, you are restricting it to the current source file. If you declare it as extern, you are saying that the variable exists, but are defined somewhere else, and if you don't have it defined elsewhere (without the extern keyword) you will get a link error (symbol not found).
Your code will break when you have more source files including that header, on link time you will have multiple references to varGlobal. If you declare it as static, then it will work with multiple sources (I mean, it will compile and link), but each source will have its own varGlobal.
What you can do in C++, that you can't in C, is to declare the variable as const on the header, like this:
const int varGlobal = 7;
And include in multiple sources, without breaking things at link time. The idea is to replace the old C style #define for constants.
If you need a global variable visible on multiple sources and not const, declare it as extern on the header, and then define it, this time without the extern keyword, on a source file:
Header included by multiple files:
extern int varGlobal;
In one of your source files:
int varGlobal = 7;
C++: Converting Hexadecimal to Decimal
Use std::hex manipulator:
#include <iostream>
#include <iomanip>
int main()
{
int x;
std::cin >> std::hex >> x;
std::cout << x << std::endl;
return 0;
}
Why std::cout instead of simply cout?
In the C++ standard, cout is defined in the std namespace, so you need to either say std::cout or put
using namespace std;
in your code in order to get at it.
However, this was not always the case, and in the past cout was just in the global namespace (or, later on, in both global and std). I would therefore conclude that your classes used an older C++ compiler.
printf with std::string?
The main reason is probably that a C++ string is a struct that includes a current-length value, not just the address of a sequence of chars terminated by a 0 byte. Printf and its relatives expect to find such a sequence, not a struct, and therefore get confused by C++ strings.
Speaking for myself, I believe that printf has a place that can't easily be filled by C++ syntactic features, just as table structures in html have a place that can't easily be filled by divs. As Dykstra wrote later about the goto, he didn't intend to start a religion and was really only arguing against using it as a kludge to make up for poorly-designed code.
It would be quite nice if the GNU project would add the printf family to their g++ extensions.
Eclipse CDT: Symbol 'cout' could not be resolved
Thanks loads for the answers above. I'm adding an answer for a specific use-case...
On a project with two target architectures each with its own build configuration (the main target is an embedded AVR platform; the second target is my local Linux PC for running unit tests) I found it necessary to set Preferences -> C/C++ -> Indexer -> Use active build configuration as well as to add /usr/include/c++/4.7, /usr/include and /usr/include/c++/4.7/x86_64-linux-gnu to Project Properties -> C/C++ General -> Paths and Symbols and then to rebuild the index.
How to get the bluetooth devices as a list?
In this code you just need to call this in your button click.
private void list_paired_Devices() {
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
ArrayList<String> devices = new ArrayList<>();
for (BluetoothDevice bt : pairedDevices) {
devices.add(bt.getName() + "\n" + bt.getAddress());
}
ArrayAdapter arrayAdapter = new ArrayAdapter(bluetooth.this, android.R.layout.simple_list_item_1, devices);
emp.setAdapter(arrayAdapter);
}
Running the new Intel emulator for Android
Complete step-by-step instructions for running the accelerated emulator can be found on the official Android developers website:
Caution: As of SDK Tools Revision 17, the virtual machine acceleration feature for the emulator is experimental; be alert for incompatibilities and errors when using this feature.
How do I print out the contents of a vector?
For those that are interested: I wrote a generalized solution that takes the best of both worlds, is more generalized to any type of range and puts quotes around non-arithmetic types (desired for string-like types). Additionally, this approach should not have any ADL issues and also avoid 'surprises' (since it's added explicitly on a case-by-case basis):
template <typename T>
inline constexpr bool is_string_type_v = std::is_convertible_v<const T&, std::string_view>;
template<class T>
struct range_out {
range_out(T& range) : r_(range) {
}
T& r_;
static_assert(!::is_string_type_v<T>, "strings and string-like types should use operator << directly");
};
template <typename T>
std::ostream& operator<< (std::ostream& out, range_out<T>& range) {
constexpr bool is_string_like = is_string_type_v<T::value_type>;
constexpr std::string_view sep{ is_string_like ? "', '" : ", " };
if (!range.r_.empty()) {
out << (is_string_like ? "['" : "[");
out << *range.r_.begin();
for (auto it = range.r_.begin() + 1; it != range.r_.end(); ++it) {
out << sep << *it;
}
out << (is_string_like ? "']" : "]");
}
else {
out << "[]";
}
return out;
}
Now it's fairly easy to use on any range:
std::cout << range_out{ my_vector };
The string-like check leaves room for improvement.
I do also have static_assert check in my solution to avoid std::basic_string<>, but I left it out here for simplicity.
Class constants in python
Expanding on betabandido's answer, you could write a function to inject the attributes as constants into the module:
def module_register_class_constants(klass, attr_prefix):
globals().update(
(name, getattr(klass, name)) for name in dir(klass) if name.startswith(attr_prefix)
)
class Animal(object):
SIZE_HUGE = "Huge"
SIZE_BIG = "Big"
module_register_class_constants(Animal, "SIZE_")
class Horse(Animal):
def printSize(self):
print SIZE_BIG
cin and getline skipping input
The structure of your menu code is the issue:
cin >> choice; // new line character is left in the stream
switch ( ... ) {
// We enter the handlers, '\n' still in the stream
}
cin.ignore(); // Put this right after cin >> choice, before you go on
// getting input with getline.
How to use Macro argument as string literal?
#define NAME(x) printf("Hello " #x);
main(){
NAME(Ian)
}
//will print: Hello Ian
reading from stdin in c++
You have not defined the variable input_line.
Add this:
string input_line;
And add this include.
#include <string>
Here is the full example. I also removed the semi-colon after the while loop, and you should have getline inside the while to properly detect the end of the stream.
#include <iostream>
#include <string>
int main() {
for (std::string line; std::getline(std::cin, line);) {
std::cout << line << std::endl;
}
return 0;
}
Setting up redirect in web.config file
You probably want to look at something like URL Rewrite to rewrite URLs to more user friendly ones rather than using a simple httpRedirect. You could then make a rule like this:
<system.webServer>
<rewrite>
<rules>
<rule name="Rewrite to Category">
<match url="^Category/([_0-9a-z-]+)/([_0-9a-z-]+)" />
<action type="Rewrite" url="category.aspx?cid={R:2}" />
</rule>
</rules>
</rewrite>
</system.webServer>
How to fix C++ error: expected unqualified-id
There should be no semicolon here:
class WordGame;
...but there should be one at the end of your class definition:
...
private:
string theWord;
}; // <-- Semicolon should be at the end of your class definition
How to change text and background color?
You can use the function system.
system("color *background**foreground*");
For background and foreground, type in a number from 0 - 9 or a letter from A - F.
For example:
system("color A1");
std::cout<<"hi"<<std::endl;
That would display the letters "hi" with a green background and blue text.
To see all the color choices, just type in:
system("color %");
to see what number or letter represents what color.
MySQL date formats - difficulty Inserting a date
Put the date in single quotes and move the parenthesis (after the 'yes') to the end:
INSERT INTO custorder
VALUES ('Kevin', 'yes' , STR_TO_DATE('1-01-2012', '%d-%m-%Y') ) ;
^ ^
---parenthesis removed--| and added here ------|
But you can always use dates without STR_TO_DATE() function, just use the (Y-m-d) '20120101' or '2012-01-01' format. Check the MySQL docs: Date and Time Literals
INSERT INTO custorder
VALUES ('Kevin', 'yes', '2012-01-01') ;
rand() between 0 and 1
No, because RAND_MAX is typically expanded to MAX_INT. So adding one (apparently) puts it at MIN_INT (although it should be undefined behavior as I'm told), hence the reversal of sign.
To get what you want you will need to move the +1 outside the computation:
r = ((double) rand() / (RAND_MAX)) + 1;
bash: pip: command not found
Not sure why this wasnt mentioned before, but the only thing that worked for me (on my NVIDIA Xavier) was:
sudo apt-get install python3-pip
(or sudo apt-get install python-pip for python 2)
C++ variable has initializer but incomplete type?
You cannot define a variable of an incomplete type. You need to bring the whole definition of Cat into scope before you can create the local variable in main. I recommend that you move the definition of the type Cat to a header and include it from the translation unit that has main.
How to check Network port access and display useful message?
You can check if the Connected property is set to $true and display a friendly message:
$t = New-Object Net.Sockets.TcpClient "10.45.23.109", 443
if($t.Connected)
{
"Port 443 is operational"
}
else
{
"..."
}
expected constructor, destructor, or type conversion before ‘(’ token
The first constructor in the header should not end with a semicolon. #include <string> is missing in the header. string is not qualified with std:: in the .cpp file. Those are all simple syntax errors. More importantly: you are not using references, when you should. Also the way you use the ifstream is broken. I suggest learning C++ before trying to use it.
Let's fix this up:
//polygone.h
# if !defined(__POLYGONE_H__)
# define __POLYGONE_H__
#include <iostream>
#include <string>
class Polygone {
public:
// declarations have to end with a semicolon, definitions do not
Polygone(){} // why would we needs this?
Polygone(const std::string& fichier);
};
# endif
and
//polygone.cc
// no need to include things twice
#include "polygone.h"
#include <fstream>
Polygone::Polygone(const std::string& nom)
{
std::ifstream fichier (nom, ios::in);
if (fichier.is_open())
{
// keep the scope as tiny as possible
std::string line;
// getline returns the stream and streams convert to booleans
while ( std::getline(fichier, line) )
{
std::cout << line << std::endl;
}
}
else
{
std::cerr << "Erreur a l'ouverture du fichier" << std::endl;
}
}
"Undefined reference to" template class constructor
This link explains where you're going wrong:
Place the definition of your constructors, destructors methods and whatnot in your header file, and that will correct the problem.
This offers another solution:
How can I avoid linker errors with my template functions?
However this requires you to anticipate how your template will be used and, as a general solution, is counter-intuitive. It does solve the corner case though where you develop a template to be used by some internal mechanism, and you want to police the manner in which it is used.
Dynamically load a function from a DLL
This is not exactly a hot topic, but I have a factory class that allows a dll to create an instance and return it as a DLL. It is what I came looking for but couldn't find exactly.
It is called like,
IHTTP_Server *server = SN::SN_Factory<IHTTP_Server>::CreateObject();
IHTTP_Server *server2 =
SN::SN_Factory<IHTTP_Server>::CreateObject(IHTTP_Server_special_entry);
where IHTTP_Server is the pure virtual interface for a class created either in another DLL, or the same one.
DEFINE_INTERFACE is used to give a class id an interface. Place inside interface;
An interface class looks like,
class IMyInterface
{
DEFINE_INTERFACE(IMyInterface);
public:
virtual ~IMyInterface() {};
virtual void MyMethod1() = 0;
...
};
The header file is like this
#if !defined(SN_FACTORY_H_INCLUDED)
#define SN_FACTORY_H_INCLUDED
#pragma once
The libraries are listed in this macro definition. One line per library/executable. It would be cool if we could call into another executable.
#define SN_APPLY_LIBRARIES(L, A) \
L(A, sn, "sn.dll") \
L(A, http_server_lib, "http_server_lib.dll") \
L(A, http_server, "")
Then for each dll/exe you define a macro and list its implementations. Def means that it is the default implementation for the interface. If it is not the default, you give a name for the interface used to identify it. Ie, special, and the name will be IHTTP_Server_special_entry.
#define SN_APPLY_ENTRYPOINTS_sn(M) \
M(IHTTP_Handler, SNI::SNI_HTTP_Handler, sn, def) \
M(IHTTP_Handler, SNI::SNI_HTTP_Handler, sn, special)
#define SN_APPLY_ENTRYPOINTS_http_server_lib(M) \
M(IHTTP_Server, HTTP::server::server, http_server_lib, def)
#define SN_APPLY_ENTRYPOINTS_http_server(M)
With the libraries all setup, the header file uses the macro definitions to define the needful.
#define APPLY_ENTRY(A, N, L) \
SN_APPLY_ENTRYPOINTS_##N(A)
#define DEFINE_INTERFACE(I) \
public: \
static const long Id = SN::I##_def_entry; \
private:
namespace SN
{
#define DEFINE_LIBRARY_ENUM(A, N, L) \
N##_library,
This creates an enum for the libraries.
enum LibraryValues
{
SN_APPLY_LIBRARIES(DEFINE_LIBRARY_ENUM, "")
LastLibrary
};
#define DEFINE_ENTRY_ENUM(I, C, L, D) \
I##_##D##_entry,
This creates an enum for interface implementations.
enum EntryValues
{
SN_APPLY_LIBRARIES(APPLY_ENTRY, DEFINE_ENTRY_ENUM)
LastEntry
};
long CallEntryPoint(long id, long interfaceId);
This defines the factory class. Not much to it here.
template <class I>
class SN_Factory
{
public:
SN_Factory()
{
}
static I *CreateObject(long id = I::Id )
{
return (I *)CallEntryPoint(id, I::Id);
}
};
}
#endif //SN_FACTORY_H_INCLUDED
Then the CPP is,
#include "sn_factory.h"
#include <windows.h>
Create the external entry point. You can check that it exists using depends.exe.
extern "C"
{
__declspec(dllexport) long entrypoint(long id)
{
#define CREATE_OBJECT(I, C, L, D) \
case SN::I##_##D##_entry: return (int) new C();
switch (id)
{
SN_APPLY_CURRENT_LIBRARY(APPLY_ENTRY, CREATE_OBJECT)
case -1:
default:
return 0;
}
}
}
The macros set up all the data needed.
namespace SN
{
bool loaded = false;
char * libraryPathArray[SN::LastLibrary];
#define DEFINE_LIBRARY_PATH(A, N, L) \
libraryPathArray[N##_library] = L;
static void LoadLibraryPaths()
{
SN_APPLY_LIBRARIES(DEFINE_LIBRARY_PATH, "")
}
typedef long(*f_entrypoint)(long id);
f_entrypoint libraryFunctionArray[LastLibrary - 1];
void InitlibraryFunctionArray()
{
for (long j = 0; j < LastLibrary; j++)
{
libraryFunctionArray[j] = 0;
}
#define DEFAULT_LIBRARY_ENTRY(A, N, L) \
libraryFunctionArray[N##_library] = &entrypoint;
SN_APPLY_CURRENT_LIBRARY(DEFAULT_LIBRARY_ENTRY, "")
}
enum SN::LibraryValues libraryForEntryPointArray[SN::LastEntry];
#define DEFINE_ENTRY_POINT_LIBRARY(I, C, L, D) \
libraryForEntryPointArray[I##_##D##_entry] = L##_library;
void LoadLibraryForEntryPointArray()
{
SN_APPLY_LIBRARIES(APPLY_ENTRY, DEFINE_ENTRY_POINT_LIBRARY)
}
enum SN::EntryValues defaultEntryArray[SN::LastEntry];
#define DEFINE_ENTRY_DEFAULT(I, C, L, D) \
defaultEntryArray[I##_##D##_entry] = I##_def_entry;
void LoadDefaultEntries()
{
SN_APPLY_LIBRARIES(APPLY_ENTRY, DEFINE_ENTRY_DEFAULT)
}
void Initialize()
{
if (!loaded)
{
loaded = true;
LoadLibraryPaths();
InitlibraryFunctionArray();
LoadLibraryForEntryPointArray();
LoadDefaultEntries();
}
}
long CallEntryPoint(long id, long interfaceId)
{
Initialize();
// assert(defaultEntryArray[id] == interfaceId, "Request to create an object for the wrong interface.")
enum SN::LibraryValues l = libraryForEntryPointArray[id];
f_entrypoint f = libraryFunctionArray[l];
if (!f)
{
HINSTANCE hGetProcIDDLL = LoadLibraryA(libraryPathArray[l]);
if (!hGetProcIDDLL) {
return NULL;
}
// resolve function address here
f = (f_entrypoint)GetProcAddress(hGetProcIDDLL, "entrypoint");
if (!f) {
return NULL;
}
libraryFunctionArray[l] = f;
}
return f(id);
}
}
Each library includes this "cpp" with a stub cpp for each library/executable. Any specific compiled header stuff.
#include "sn_pch.h"
Setup this library.
#define SN_APPLY_CURRENT_LIBRARY(L, A) \
L(A, sn, "sn.dll")
An include for the main cpp. I guess this cpp could be a .h. But there are different ways you could do this. This approach worked for me.
#include "../inc/sn_factory.cpp"
Solution for "Fatal error: Maximum function nesting level of '100' reached, aborting!" in PHP
You could convert your recursive code into an iterative code, which simulates the recursion. This means that you have to push the current status (url, document, position in document etc.) into an array, when you reach a link, and pop it out of the array, when this link has finished.
Python ImportError: No module named wx
In fedora you can use following command to install wx
pip install -U \
-f https://extras.wxpython.org/wxPython4/extras/linux/gtk3/ubuntu-16.04 \
wxPython
Parsing Query String in node.js
Starting with Node.js 11, the url.parse and other methods of the Legacy URL API were deprecated (only in the documentation, at first) in favour of the standardized WHATWG URL API. The new API does not offer parsing the query string into an object. That can be achieved using tthe querystring.parse method:
// Load modules to create an http server, parse a URL and parse a URL query.
const http = require('http');
const { URL } = require('url');
const { parse: parseQuery } = require('querystring');
// Provide the origin for relative URLs sent to Node.js requests.
const serverOrigin = 'http://localhost:8000';
// Configure our HTTP server to respond to all requests with a greeting.
const server = http.createServer((request, response) => {
// Parse the request URL. Relative URLs require an origin explicitly.
const url = new URL(request.url, serverOrigin);
// Parse the URL query. The leading '?' has to be removed before this.
const query = parseQuery(url.search.substr(1));
response.writeHead(200, { 'Content-Type': 'text/plain' });
response.end(`Hello, ${query.name}!\n`);
});
// Listen on port 8000, IP defaults to 127.0.0.1.
server.listen(8000);
// Print a friendly message on the terminal.
console.log(`Server running at ${serverOrigin}/`);
If you run the script above, you can test the server response like this, for example:
curl -q http://localhost:8000/status?name=ryan
Hello, ryan!
Why are elementwise additions much faster in separate loops than in a combined loop?
OK, the right answer definitely has to do something with the CPU cache. But to use the cache argument can be quite difficult, especially without data.
There are many answers, that led to a lot of discussion, but let's face it: Cache issues can be very complex and are not one dimensional. They depend heavily on the size of the data, so my question was unfair: It turned out to be at a very interesting point in the cache graph.
@Mysticial's answer convinced a lot of people (including me), probably because it was the only one that seemed to rely on facts, but it was only one "data point" of the truth.
That's why I combined his test (using a continuous vs. separate allocation) and @James' Answer's advice.
The graphs below shows, that most of the answers and especially the majority of comments to the question and answers can be considered completely wrong or true depending on the exact scenario and parameters used.
Note that my initial question was at n = 100.000. This point (by accident) exhibits special behavior:
It possesses the greatest discrepancy between the one and two loop'ed version (almost a factor of three)
It is the only point, where one-loop (namely with continuous allocation) beats the two-loop version. (This made Mysticial's answer possible, at all.)
The result using initialized data:
The result using uninitialized data (this is what Mysticial tested):
And this is a hard-to-explain one: Initialized data, that is allocated once and reused for every following test case of different vector size:
Proposal
Every low-level performance related question on Stack Overflow should be required to provide MFLOPS information for the whole range of cache relevant data sizes! It's a waste of everybody's time to think of answers and especially discuss them with others without this information.
How to cin to a vector
I ran into a similar problem and this is how I did it. Using &modifying your code appropriately:
int main()
{
int input;
vector<int> V;
cout << "Enter your numbers to be evaluated: "
<< '\n' << "type "done" & keyboard Enter to stop entry"
<< '\n';
while ( (cin >> input) && input != "done") {
V.push_back(input);
}
write_vector(V);
return 0;
}
How to automatically convert strongly typed enum into int?
TLDR;
There are no implicit conversions from the values of a scoped enumerator [AKA: "strong enum"] to integral types, although
static_castmay be used to obtain the numeric value of the enumerator.
(emphasis added)
Source: https://en.cppreference.com/w/cpp/language/enum --> under the section "Scoped enumerations".
Going further
In C++ there are two types of enums:
- "regular", "weak", "weakly typed", or "C-style" enums, and
- "scoped", "strong", "strongly typed", "enum class", or "C++-style" enums.
"Scoped" enums, or "strong" enums, give two additional "features" beyond what "regular" enums give you. Scoped enums:
- don't allow implicit casting from the enum type to an integer type (so you can't do what you want to do implicitly!), and
- they "scope" the enum so that you have to access the enum through its enum type name.
Example of an enum class:
// enum class (AKA: "strong" or "scoped" enum)
enum class my_enum
{
A = 0,
B,
C,
};
my_enum e = my_enum::A; // scoped through `my_enum::`
e = my_enum::B;
// NOT ALLOWED!:
// error: cannot convert ‘my_enum’ to ‘int’ in initialization
// int i = e;
// But this works fine:
int i = static_cast<int>(e);
The first "feature" may actually be something you don't want, in which case you just need to use a regular C-style enum instead! And the nice thing is: you can still "scope" or "namespace" the enum, as has been done in C for decades, by simply prepending its name with the enum type name, like this:
Example of a regular enum:
// regular enum (AKA: "weak" or "C-style" enum)
enum my_enum
{
MY_ENUM_A = 0,
MY_ENUM_B,
MY_ENUM_C,
};
my_enum e = MY_ENUM_A; // scoped through `MY_ENUM_`
e = MY_ENUM_B;
// This works fine!
int i = e;
Notice you still get the benefit of "scoping" simply by adding the MY_ENUM_ "scope" to the front of each enum!
Test the above code here: https://onlinegdb.com/SJQ7uthcP.
Identifier not found error on function call
Add this line before main function:
void swapCase (char* name);
int main()
{
...
swapCase(name); // swapCase prototype should be known at this point
...
}
This is called forward declaration: compiler needs to know function prototype when function call is compiled.
Clang vs GCC for my Linux Development project
I use both Clang and GCC, I find Clang has some useful warnings, but for my own ray-tracing benchmarks - its consistently 5-15% slower then GCC (take that with grain of salt of course, but attempted to use similar optimization flags for both).
So for now I use Clang static analysis and its warnings with complex macros: (though now GCC's warnings are pretty much as good - gcc4.8 - 4.9).
Some considerations:
- Clang has no OpenMP support, only matters if you take advantage of that but since I do, its a limitation for me. (*****)
- Cross compilation may not be as well supported (FreeBSD 10 for example still use GCC4.x for ARM), gcc-mingw for example is available on Linux... (YMMV).
- Some IDE's don't yet support parsing Clangs output (
QtCreator for example*****). EDIT: QtCreator now supports Clang's output - Some aspects of GCC are better documented and since GCC has been around for longer and is widely used, you might find it easier to get help with warnings / error messages.
***** - these areas are in active development and may soon be supported
what is the size of an enum type data in C++?
I like the explanation From EdX (Microsoft: DEV210x Introduction to C++) for a similar problem:
"The enum represents the literal values of days as integers. Referring to the numeric types table, you see that an int takes 4 bytes of memory. 7 days x 4 bytes each would require 28 bytes of memory if the entire enum were stored but the compiler only uses a single element of the enum, therefore the size in memory is actually 4 bytes."
Know relationships between all the tables of database in SQL Server
My solution is based on @marc_s solution, i just concatenated columns in cases that a constraint is based on more than one column:
SELECT
FK.[name] AS ForeignKeyConstraintName
,SCHEMA_NAME(FT.schema_id) + '.' + FT.[name] AS ForeignTable
,STUFF(ForeignColumns.ForeignColumns, 1, 2, '') AS ForeignColumns
,SCHEMA_NAME(RT.schema_id) + '.' + RT.[name] AS ReferencedTable
,STUFF(ReferencedColumns.ReferencedColumns, 1, 2, '') AS ReferencedColumns
FROM
sys.foreign_keys FK
INNER JOIN sys.tables FT
ON FT.object_id = FK.parent_object_id
INNER JOIN sys.tables RT
ON RT.object_id = FK.referenced_object_id
CROSS APPLY
(
SELECT
', ' + iFC.[name] AS [text()]
FROM
sys.foreign_key_columns iFKC
INNER JOIN sys.columns iFC
ON iFC.object_id = iFKC.parent_object_id
AND iFC.column_id = iFKC.parent_column_id
WHERE
iFKC.constraint_object_id = FK.object_id
ORDER BY
iFC.[name]
FOR XML PATH('')
) ForeignColumns (ForeignColumns)
CROSS APPLY
(
SELECT
', ' + iRC.[name]AS [text()]
FROM
sys.foreign_key_columns iFKC
INNER JOIN sys.columns iRC
ON iRC.object_id = iFKC.referenced_object_id
AND iRC.column_id = iFKC.referenced_column_id
WHERE
iFKC.constraint_object_id = FK.object_id
ORDER BY
iRC.[name]
FOR XML PATH('')
) ReferencedColumns (ReferencedColumns)
Calculating distance between two geographic locations
private static Double _MilesToKilometers = 1.609344;
private static Double _MilesToNautical = 0.8684;
/// <summary>
/// Calculates the distance between two points of latitude and longitude.
/// Great Link - http://www.movable-type.co.uk/scripts/latlong.html
/// </summary>
/// <param name="coordinate1">First coordinate.</param>
/// <param name="coordinate2">Second coordinate.</param>
/// <param name="unitsOfLength">Sets the return value unit of length.</param>
public static Double Distance(Coordinate coordinate1, Coordinate coordinate2, UnitsOfLength unitsOfLength)
{
double theta = coordinate1.getLongitude() - coordinate2.getLongitude();
double distance = Math.sin(ToRadian(coordinate1.getLatitude())) * Math.sin(ToRadian(coordinate2.getLatitude())) +
Math.cos(ToRadian(coordinate1.getLatitude())) * Math.cos(ToRadian(coordinate2.getLatitude())) *
Math.cos(ToRadian(theta));
distance = Math.acos(distance);
distance = ToDegree(distance);
distance = distance * 60 * 1.1515;
if (unitsOfLength == UnitsOfLength.Kilometer)
distance = distance * _MilesToKilometers;
else if (unitsOfLength == UnitsOfLength.NauticalMiles)
distance = distance * _MilesToNautical;
return (distance);
}
HTML-parser on Node.js
If you want to build DOM you can use jsdom.
There's also cheerio, it has the jQuery interface and it's a lot faster than older versions of jsdom, although these days they are similar in performance.
You might wanna have a look at htmlparser2, which is a streaming parser, and according to its benchmark, it seems to be faster than others, and no DOM by default. It can also produce a DOM, as it is also bundled with a handler that creates a DOM. This is the parser that is used by cheerio.
parse5 also looks like a good solution. It's fairly active (11 days since the last commit as of this update), WHATWG-compliant, and is used in jsdom, Angular, and Polymer.
And if you want to parse HTML for web scraping, you can use YQL1. There is a node module for it. YQL I think would be the best solution if your HTML is from a static website, since you are relying on a service, not your own code and processing power. Though note that it won't work if the page is disallowed by the robot.txt of the website, YQL won't work with it.
If the website you're trying to scrape is dynamic then you should be using a headless browser like phantomjs. Also have a look at casperjs, if you're considering phantomjs. And you can control casperjs from node with SpookyJS.
Beside phantomjs there's zombiejs. Unlike phantomjs that cannot be embedded in nodejs, zombiejs is just a node module.
There's a nettuts+ toturial for the latter solutions.
1 Since Aug. 2014, YUI library, which is a requirement for YQL, is no longer actively maintained, source
Spring RestTemplate - how to enable full debugging/logging of requests/responses?
You can use spring-rest-template-logger to log RestTemplate HTTP traffic.
Add a dependency to your Maven project:
<dependency>
<groupId>org.hobsoft.spring</groupId>
<artifactId>spring-rest-template-logger</artifactId>
<version>2.0.0</version>
</dependency>
Then customize your RestTemplate as follows:
RestTemplate restTemplate = new RestTemplateBuilder()
.customizers(new LoggingCustomizer())
.build()
Ensure that debug logging is enabled in application.properties:
logging.level.org.hobsoft.spring.resttemplatelogger.LoggingCustomizer = DEBUG
Now all RestTemplate HTTP traffic will be logged to org.hobsoft.spring.resttemplatelogger.LoggingCustomizer at debug level.
DISCLAIMER: I wrote this library.
Using member variable in lambda capture list inside a member function
I believe VS2010 to be right this time, and I'd check if I had the standard handy, but currently I don't.
Now, it's exactly like the error message says: You can't capture stuff outside of the enclosing scope of the lambda.† grid is not in the enclosing scope, but this is (every access to grid actually happens as this->grid in member functions). For your usecase, capturing this works, since you'll use it right away and you don't want to copy the grid
auto lambda = [this](){ std::cout << grid[0][0] << "\n"; }
If however, you want to store the grid and copy it for later access, where your puzzle object might already be destroyed, you'll need to make an intermediate, local copy:
vector<vector<int> > tmp(grid);
auto lambda = [tmp](){}; // capture the local copy per copy
† I'm simplifying - Google for "reaching scope" or see §5.1.2 for all the gory details.
Modulo operator with negative values
a % b
in c++ default:
(-7/3) => -2
-2 * 3 => -6
so a%b => -1
(7/-3) => -2
-2 * -3 => 6
so a%b => 1
in python:
-7 % 3 => 2
7 % -3 => -2
in c++ to python:
(b + (a%b)) % b
Sum of Numbers C++
int result = 0;
for (int i=0; i < positiveInteger; i++)
{
result = startingNumber + 1;
cout << result;
}
What is a constant reference? (not a reference to a constant)
By "constant reference" I am guessing you really mean "reference to constant data". Pointers on the other hand, can be a constant pointer (the pointer itself is constant, not the data it points to), a pointer to constant data, or both.
C++ Fatal Error LNK1120: 1 unresolved externals
I have faced this particular error when I didn't defined the main() function. Check if the main() function exists or check the name of the function letter by letter as Timothy described above or check if the file where the main function is located is included to your project.
How to avoid precompiled headers
The .cpp file is configured to use precompiled header, therefore it must be included first (before iostream). For Visual Studio, it's name is usually "stdafx.h".
If there are no stdafx* files in your project, you need to go to this file's options and set it as “Not using precompiled headers”.
Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/security]
I had the same problem. The only thing that solved it was merge the content of META-INF/spring.handler and META-INF/spring.schemas of each spring jar file into same file names under my META-INF project.
This two threads explain it better:
How to format a number as percentage in R?
Here's my solution for defining a new function (mostly so I can play around with Curry and Compose :-) ):
library(roxygen)
printpct <- Compose(function(x) x*100, Curry(sprintf,fmt="%1.2f%%"))
SOAP request in PHP with CURL
Tested and working!
with https, user & password
<?php //Data, connection, auth $dataFromTheForm = $_POST['fieldName']; // request data from the form $soapUrl = "https://connecting.website.com/soap.asmx?op=DoSomething"; // asmx URL of WSDL $soapUser = "username"; // username $soapPassword = "password"; // password // xml post structure $xml_post_string = '<?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <GetItemPrice xmlns="http://connecting.website.com/WSDL_Service"> // xmlns value to be set to your WSDL URL <PRICE>'.$dataFromTheForm.'</PRICE> </GetItemPrice > </soap:Body> </soap:Envelope>'; // data from the form, e.g. some ID number $headers = array( "Content-type: text/xml;charset=\"utf-8\"", "Accept: text/xml", "Cache-Control: no-cache", "Pragma: no-cache", "SOAPAction: http://connecting.website.com/WSDL_Service/GetPrice", "Content-length: ".strlen($xml_post_string), ); //SOAPAction: your op URL $url = $soapUrl; // PHP cURL for https connection with auth $ch = curl_init(); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_USERPWD, $soapUser.":".$soapPassword); // username and password - declared at the top of the doc curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY); curl_setopt($ch, CURLOPT_TIMEOUT, 10); curl_setopt($ch, CURLOPT_POST, true); curl_setopt($ch, CURLOPT_POSTFIELDS, $xml_post_string); // the SOAP request curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); // converting $response = curl_exec($ch); curl_close($ch); // converting $response1 = str_replace("<soap:Body>","",$response); $response2 = str_replace("</soap:Body>","",$response1); // convertingc to XML $parser = simplexml_load_string($response2); // user $parser to get your data out of XML response and to display it. ?>
How to specify the default error page in web.xml?
You can also specify <error-page> for exceptions using <exception-type>, eg below:
<error-page>
<exception-type>java.lang.Exception</exception-type>
<location>/errorpages/exception.html</location>
</error-page>
Or map a error code using <error-code>:
<error-page>
<error-code>404</error-code>
<location>/errorpages/404error.html</location>
</error-page>
std::enable_if to conditionally compile a member function
For those late-comers that are looking for a solution that "just works":
#include <utility>
#include <iostream>
template< typename T >
class Y {
template< bool cond, typename U >
using resolvedType = typename std::enable_if< cond, U >::type;
public:
template< typename U = T >
resolvedType< true, U > foo() {
return 11;
}
template< typename U = T >
resolvedType< false, U > foo() {
return 12;
}
};
int main() {
Y< double > y;
std::cout << y.foo() << std::endl;
}
Compile with:
g++ -std=gnu++14 test.cpp
Running gives:
./a.out
11
How to use range-based for() loop with std::map?
From this paper: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2049.pdf
for( type-speci?er-seq simple-declarator : expression ) statement
is syntactically equivalent to
{
typedef decltype(expression) C;
auto&& rng(expression);
for (auto begin(std::For<C>::begin(rng)), end(std::For<C>::end(rng)); begin != end; ++ begin) {
type-speci?er-seq simple-declarator(*begin);
statement
}
}
So you can clearly see that what is abc in your case will be std::pair<key_type, value_type >.
So for printing you can do access each element by abc.first and abc.second
Recommended way to insert elements into map
Use insert if you want to insert a new element. insert will not
overwrite an existing element, and you can verify that there was no
previously exising element:
if ( !myMap.insert( std::make_pair( key, value ) ).second ) {
// Element already present...
}
Use [] if you want to overwrite a possibly existing element:
myMap[ key ] = value;
assert( myMap.find( key )->second == value ); // post-condition
This form will overwrite any existing entry.
How to run script as another user without password?
Call visudo and add this:
user1 ALL=(user2) NOPASSWD: /home/user2/bin/test.sh
The command paths must be absolute! Then call sudo -u user2 /home/user2/bin/test.sh from a user1 shell. Done.
reading a line from ifstream into a string variable
Use the std::getline() from <string>.
istream & getline(istream & is,std::string& str)
So, for your case it would be:
std::getline(read,x);
Why is Python running my module when I import it, and how do I stop it?
Because this is just how Python works - keywords such as class and def are not declarations. Instead, they are real live statements which are executed. If they were not executed your module would be .. empty :-)
Anyway, the idiomatic approach is:
# stuff to run always here such as class/def
def main():
pass
if __name__ == "__main__":
# stuff only to run when not called via 'import' here
main()
See What is if __name__ == "__main__" for?
It does require source control over the module being imported, however.
Happy coding.
CSS endless rotation animation
<style>
div
{
height:200px;
width:200px;
-webkit-animation: spin 2s infinite linear;
}
@-webkit-keyframes spin {
0% {-webkit-transform: rotate(0deg);}
100% {-webkit-transform: rotate(360deg);}
}
</style>
</head>
<body>
<div><img src="1.png" height="200px" width="200px"/></div>
</body>
Why I cannot cout a string?
Above answers are good but If you do not want to add string include, you can use the following
ostream& operator<<(ostream& os, string& msg)
{
os<<msg.c_str();
return os;
}
'foo' was not declared in this scope c++
In general, in C++ functions have to be declared before you call them. So sometime before the definition of getSkewNormal(), the compiler needs to see the declaration:
double integrate (double start, double stop, int numSteps, Evaluatable evalObj);
Mostly what people do is put all the declarations (only) in the header file, and put the actual code -- the definitions of the functions and methods -- into a separate source (*.cc or *.cpp) file. This neatly solves the problem of needing all the functions to be declared.
How to solve munmap_chunk(): invalid pointer error in C++
This happens when the pointer passed to free() is not valid or has been modified somehow. I don't really know the details here. The bottom line is that the pointer passed to free() must be the same as returned by malloc(), realloc() and their friends. It's not always easy to spot what the problem is for a novice in their own code or even deeper in a library. In my case, it was a simple case of an undefined (uninitialized) pointer related to branching.
The free() function frees the memory space pointed to by ptr, which must have been returned by a previous call to malloc(), calloc() or realloc(). Otherwise, or if free(ptr) has already been called before, undefined behavior occurs. If ptr is NULL, no operation is performed. GNU 2012-05-10 MALLOC(3)
char *words; // setting this to NULL would have prevented the issue
if (condition) {
words = malloc( 512 );
/* calling free sometime later works here */
free(words)
} else {
/* do not allocate words in this branch */
}
/* free(words); -- error here --
*** glibc detected *** ./bin: munmap_chunk(): invalid pointer: 0xb________ ***/
There are many similar questions here about the related free() and rellocate() functions. Some notable answers providing more details:
*** glibc detected *** free(): invalid next size (normal): 0x0a03c978 ***
*** glibc detected *** sendip: free(): invalid next size (normal): 0x09da25e8 ***
glibc detected, realloc(): invalid pointer
IMHO running everything in a debugger (Valgrind) is not the best option because errors like this are often caused by inept or novice programmers. It's more productive to figure out the issue manually and learn how to avoid it in the future.
Most Pythonic way to provide global configuration variables in config.py?
Let's be honest, we should probably consider using a Python Software Foundation maintained library:
https://docs.python.org/3/library/configparser.html
Config example: (ini format, but JSON available)
[DEFAULT]
ServerAliveInterval = 45
Compression = yes
CompressionLevel = 9
ForwardX11 = yes
[bitbucket.org]
User = hg
[topsecret.server.com]
Port = 50022
ForwardX11 = no
Code example:
>>> import configparser
>>> config = configparser.ConfigParser()
>>> config.read('example.ini')
>>> config['DEFAULT']['Compression']
'yes'
>>> config['DEFAULT'].getboolean('MyCompression', fallback=True) # get_or_else
Making it globally-accessible:
import configpaser
class App:
__conf = None
@staticmethod
def config():
if App.__conf is None: # Read only once, lazy.
App.__conf = configparser.ConfigParser()
App.__conf.read('example.ini')
return App.__conf
if __name__ == '__main__':
App.config()['DEFAULT']['MYSQL_PORT']
# or, better:
App.config().get(section='DEFAULT', option='MYSQL_PORT', fallback=3306)
....
Downsides:
- Uncontrolled global mutable state.
How to read and write to a text file in C++?
Default c++ mechanism for file IO is called streams.
Streams can be of three flavors: input, output and inputoutput.
Input streams act like sources of data. To read data from an input stream you use >> operator:
istream >> my_variable; //This code will read a value from stream into your variable.
Operator >> acts different for different types. If in the example above my_variable was an int, then a number will be read from the strem, if my_variable was a string, then a word would be read, etc.
You can read more then one value from the stream by writing istream >> a >> b >> c; where a, b and c would be your variables.
Output streams act like sink to which you can write your data. To write your data to a stream, use << operator.
ostream << my_variable; //This code will write a value from your variable into stream.
As with input streams, you can write several values to the stream by writing something like this:
ostream << a << b << c;
Obviously inputoutput streams can act as both.
In your code sample you use cout and cin stream objects.
cout stands for console-output and cin for console-input. Those are predefined streams for interacting with default console.
To interact with files, you need to use ifstream and ofstream types.
Similar to cin and cout, ifstream stands for input-file-stream and ofstream stands for output-file-stream.
Your code might look like this:
#include <iostream>
#include <fstream>
using namespace std;
int start()
{
cout << "Welcome...";
// do fancy stuff
return 0;
}
int main ()
{
string usreq, usr, yn, usrenter;
cout << "Is this your first time using TEST" << endl;
cin >> yn;
if (yn == "y")
{
ifstream iusrfile;
ofstream ousrfile;
iusrfile.open("usrfile.txt");
iusrfile >> usr;
cout << iusrfile; // I'm not sure what are you trying to do here, perhaps print iusrfile contents?
iusrfile.close();
cout << "Please type your Username. \n";
cin >> usrenter;
if (usrenter == usr)
{
start ();
}
}
else
{
cout << "THAT IS NOT A REGISTERED USERNAME.";
}
return 0;
}
For further reading you might want to look at c++ I/O reference
Is it possible to force Excel recognize UTF-8 CSV files automatically?
This is an old question but I've just encountered had a similar problem and the solution may help others:
Had the same issue where writing out CSV text data to a file, then opening the resulting .csv in Excel shifts all the text into a single column. After having a read of the above answers I tried the following, which seems to sort the problem out.
Apply an encoding of UTF-8 when you create your StreamWriter. That's it.
Example:
using (StreamWriter output = new StreamWriter(outputFileName, false, Encoding.UTF8, 2 << 22)) {
/* ... do stuff .... */
output.Close();
}
What are callee and caller saved registers?
Caller-saved registers (AKA volatile registers, or call-clobbered) are used to hold temporary quantities that need not be preserved across calls.
For that reason, it is the caller's responsibility to push these registers onto the stack or copy them somewhere else if it wants to restore this value after a procedure call.
It's normal to let a call destroy temporary values in these registers, though.
Callee-saved registers (AKA non-volatile registers, or call-preserved) are used to hold long-lived values that should be preserved across calls.
When the caller makes a procedure call, it can expect that those registers will hold the same value after the callee returns, making it the responsibility of the callee to save them and restore them before returning to the caller. Or to not touch them.
SoapFault exception: Could not connect to host
This work for me
$opts = array(
'ssl' => array('verify_peer' => false, 'verify_peer_name' => false)
);
if (!isset($this->soap_client)) {
$this->soap_client = new SoapClient($this->WSDL, array(
'soap_version' => $this->soap_version,
'location' => $this->URL,
'trace' => 1,
'exceptions' => 0,
'stream_context' => stream_context_create($opts)
));
How to conclude your merge of a file?
I just did:
git merge --continue
At which point vi launched to edit a merge comment. A quick :wq and the merge was done.
How to add header data in XMLHttpRequest when using formdata?
Use: xmlhttp.setRequestHeader(key, value);
What tools do you use to test your public REST API?
I use http://hurl.it/
Ha. Sorry, I mis-read your post. I've used cucumber to test it before. It worked out nicely.
How to change collation of database, table, column?
I used the following shell script. It takes database name as a parameter and converts all tables to another charset and collation (given by another parameters or default value defined in the script).
#!/bin/bash
# mycollate.sh <database> [<charset> <collation>]
# changes MySQL/MariaDB charset and collation for one database - all tables and
# all columns in all tables
DB="$1"
CHARSET="$2"
COLL="$3"
[ -n "$DB" ] || exit 1
[ -n "$CHARSET" ] || CHARSET="utf8mb4"
[ -n "$COLL" ] || COLL="utf8mb4_general_ci"
echo $DB
echo "ALTER DATABASE $DB CHARACTER SET $CHARSET COLLATE $COLL;" | mysql
echo "USE $DB; SHOW TABLES;" | mysql -s | (
while read TABLE; do
echo $DB.$TABLE
echo "ALTER TABLE $TABLE CONVERT TO CHARACTER SET $CHARSET COLLATE $COLL;" | mysql $DB
done
)
What characters are allowed in an email address?
The accepted answer refers to a Wikipedia article when discussing the valid local-part of an email address, but Wikipedia is not an authority on this.
IETF RFC 3696 is an authority on this matter, and should be consulted at section 3. Restrictions on email addresses on page 5:
Contemporary email addresses consist of a "local part" separated from a "domain part" (a fully-qualified domain name) by an at-sign ("@"). The syntax of the domain part corresponds to that in the previous section. The concerns identified in that section about filtering and lists of names apply to the domain names used in an email context as well. The domain name can also be replaced by an IP address in square brackets, but that form is strongly discouraged except for testing and troubleshooting purposes.
The local part may appear using the quoting conventions described below. The quoted forms are rarely used in practice, but are required for some legitimate purposes. Hence, they should not be rejected in filtering routines but, should instead be passed to the email system for evaluation by the destination host.
The exact rule is that any ASCII character, including control characters, may appear quoted, or in a quoted string. When quoting is needed, the backslash character is used to quote the following character. For example
Abc\@[email protected]is a valid form of an email address. Blank spaces may also appear, as in
Fred\ [email protected]The backslash character may also be used to quote itself, e.g.,
Joe.\\[email protected]In addition to quoting using the backslash character, conventional double-quote characters may be used to surround strings. For example
"Abc@def"@example.com "Fred Bloggs"@example.comare alternate forms of the first two examples above. These quoted forms are rarely recommended, and are uncommon in practice, but, as discussed above, must be supported by applications that are processing email addresses. In particular, the quoted forms often appear in the context of addresses associated with transitions from other systems and contexts; those transitional requirements do still arise and, since a system that accepts a user-provided email address cannot "know" whether that address is associated with a legacy system, the address forms must be accepted and passed into the email environment.
Without quotes, local-parts may consist of any combination of
alphabetic characters, digits, or any of the special characters! # $ % & ' * + - / = ? ^ _ ` . { | } ~period (".") may also appear, but may not be used to start or end the local part, nor may two or more consecutive periods appear. Stated differently, any ASCII graphic (printing) character other than the at-sign ("@"), backslash, double quote, comma, or square brackets may appear without quoting. If any of that list of excluded characters are to appear, they must be quoted. Forms such as
[email protected] customer/[email protected] [email protected] !def!xyz%[email protected] [email protected]are valid and are seen fairly regularly, but any of the characters listed above are permitted.
As others have done, I submit a regex that works for both PHP and JavaScript to validate email addresses:
/^[a-z0-9!'#$%&*+\/=?^_`{|}~-]+(?:\.[a-z0-9!'#$%&*+\/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-zA-Z]{2,}$/i
If...Then...Else with multiple statements after Then
This works with multiple statements:
if condition1 Then stmt1:stmt2 Else if condition2 Then stmt3:stmt4 Else stmt5:stmt6
Or you can split it over multiple lines:
if condition1 Then stmt1:stmt2
Else if condition2 Then stmt3:stmt4
Else stmt5:stmt6
How to use background thread in swift?
dispatch_async(dispatch_get_global_queue(QOS_CLASS_BACKGROUND, 0), {
// Conversion into base64 string
self.uploadImageString = uploadPhotoDataJPEG.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.EncodingEndLineWithCarriageReturn)
})
How to test if JSON object is empty in Java
If you're okay with a hack -
obj.toString().equals("{}");
Serializing the object is expensive and moreso for large objects, but it's good to understand that JSON is transparent as a string, and therefore looking at the string representation is something you can always do to solve a problem.
Safest way to run BAT file from Powershell script
What about invoke-item script.bat.
Simple Random Samples from a Sql database
Select 3000 random records in Netezza:
WITH IDS AS (
SELECT ID
FROM MYTABLE;
)
SELECT ID FROM IDS ORDER BY mt_random() LIMIT 3000
How to send cookies in a post request with the Python Requests library?
The latest release of Requests will build CookieJars for you from simple dictionaries.
import requests
cookies = {'enwiki_session': '17ab96bd8ffbe8ca58a78657a918558'}
r = requests.post('http://wikipedia.org', cookies=cookies)
Enjoy :)
Copying an array of objects into another array in javascript
If you want to keep reference:
Array.prototype.push.apply(destinationArray, sourceArray);
Biggest differences of Thrift vs Protocol Buffers?
For one, protobuf isn't a full RPC implementation. It requires something like gRPC to go with it.
gPRC is very slow compared to Thrift:
Prevent flex items from overflowing a container
Instead of flex: 1 0 auto just use flex: 1
main, aside, article {_x000D_
margin: 10px;_x000D_
border: solid 1px #000;_x000D_
border-bottom: 0;_x000D_
height: 50px;_x000D_
}_x000D_
main {_x000D_
display: flex;_x000D_
}_x000D_
aside {_x000D_
flex: 0 0 200px;_x000D_
}_x000D_
article {_x000D_
flex: 1;_x000D_
}<main>_x000D_
<aside>x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x </aside>_x000D_
<article>don't let flex item overflow container.... y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y </article>_x000D_
</main>Can I run Keras model on gpu?
See if your script is running GPU in Task manager. If not, suspect your CUDA version is right one for the tensorflow version you are using, as the other answers suggested already.
Additionally, a proper CUDA DNN library for the CUDA version is required to run GPU with tensorflow. Download/extract it from here and put the DLL (e.g., cudnn64_7.dll) into CUDA bin folder (e.g., C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v10.1\bin).
Determine on iPhone if user has enabled push notifications
Call enabledRemoteNotificationsTypes and check the mask.
For example:
UIRemoteNotificationType types = [[UIApplication sharedApplication] enabledRemoteNotificationTypes];
if (types == UIRemoteNotificationTypeNone)
// blah blah blah
iOS8 and above:
[[UIApplication sharedApplication] isRegisteredForRemoteNotifications]
Password Protect a SQLite DB. Is it possible?
You can encrypt your SQLite database with the SEE addon. This way you prevent unauthorized access/modification.
Quoting SQLite documentation:
The SQLite Encryption Extension (SEE) is an enhanced version of SQLite that encrypts database files using 128-bit or 256-Bit AES to help prevent unauthorized access or modification. The entire database file is encrypted so that to an outside observer, the database file appears to contain white noise. There is nothing that identifies the file as an SQLite database.
You can find more info about this addon in this link.
SSL received a record that exceeded the maximum permissible length. (Error code: ssl_error_rx_record_too_long)
In my case, I needed to install mod_ssl first
yum install mod_ssl
right align an image using CSS HTML
<img style="float: right;" alt="" src="http://example.com/image.png" />
<div style="clear: right">
...text...
</div>
git - Your branch is ahead of 'origin/master' by 1 commit
git reset HEAD <file1> <file2> ...
remove the specified files from the next commit
How to convert current date into string in java?
// On the form: dow mon dd hh:mm:ss zzz yyyy
new Date().toString();
Random date in C#
This is in slight response to Joel's comment about making a slighly more optimized version. Instead of returning a random date directly, why not return a generator function which can be called repeatedly to create a random date.
Func<DateTime> RandomDayFunc()
{
DateTime start = new DateTime(1995, 1, 1);
Random gen = new Random();
int range = ((TimeSpan)(DateTime.Today - start)).Days;
return () => start.AddDays(gen.Next(range));
}
Could not resolve '...' from state ''
Had the same issue with Ionic routing.
Simple solution is to use the name of the state - basically state.go(state name)
.state('tab.search', {
url: '/search',
views: {
'tab-search': {
templateUrl: 'templates/search.html',
controller: 'SearchCtrl'
}
}
})
And in controller you can use $state.go('tab.search');
ImportError: No module named matplotlib.pyplot
You have two pythons installed on your machine, one is the standard python that comes with Mac OSX and the second is the one you installed with ports (this is the one that has matplotlib installed in its library, the one that comes with macosx does not).
/usr/bin/python
Is the standard mac python and since it doesn't have matplotlib you should always start your script with the one installed with ports.
If python your_script.py works then change the #! to:
#!/usr/bin/env python
Or put the full path to the python interpreter that has the matplotlib installed in its library.
Is there a regular expression to detect a valid regular expression?
/
^ # start of string
( # first group start
(?:
(?:[^?+*{}()[\]\\|]+ # literals and ^, $
| \\. # escaped characters
| \[ (?: \^?\\. | \^[^\\] | [^\\^] ) # character classes
(?: [^\]\\]+ | \\. )* \]
| \( (?:\?[:=!]|\?<[=!]|\?>)? (?1)?? \) # parenthesis, with recursive content
| \(\? (?:R|[+-]?\d+) \) # recursive matching
)
(?: (?:[?+*]|\{\d+(?:,\d*)?\}) [?+]? )? # quantifiers
| \| # alternative
)* # repeat content
) # end first group
$ # end of string
/
This is a recursive regex, and is not supported by many regex engines. PCRE based ones should support it.
Without whitespace and comments:
/^((?:(?:[^?+*{}()[\]\\|]+|\\.|\[(?:\^?\\.|\^[^\\]|[^\\^])(?:[^\]\\]+|\\.)*\]|\((?:\?[:=!]|\?<[=!]|\?>)?(?1)??\)|\(\?(?:R|[+-]?\d+)\))(?:(?:[?+*]|\{\d+(?:,\d*)?\})[?+]?)?|\|)*)$/
.NET does not support recursion directly. (The (?1) and (?R) constructs.) The recursion would have to be converted to counting balanced groups:
^ # start of string
(?:
(?: [^?+*{}()[\]\\|]+ # literals and ^, $
| \\. # escaped characters
| \[ (?: \^?\\. | \^[^\\] | [^\\^] ) # character classes
(?: [^\]\\]+ | \\. )* \]
| \( (?:\?[:=!]
| \?<[=!]
| \?>
| \?<[^\W\d]\w*>
| \?'[^\W\d]\w*'
)? # opening of group
(?<N>) # increment counter
| \) # closing of group
(?<-N>) # decrement counter
)
(?: (?:[?+*]|\{\d+(?:,\d*)?\}) [?+]? )? # quantifiers
| \| # alternative
)* # repeat content
$ # end of string
(?(N)(?!)) # fail if counter is non-zero.
Compacted:
^(?:(?:[^?+*{}()[\]\\|]+|\\.|\[(?:\^?\\.|\^[^\\]|[^\\^])(?:[^\]\\]+|\\.)*\]|\((?:\?[:=!]|\?<[=!]|\?>|\?<[^\W\d]\w*>|\?'[^\W\d]\w*')?(?<N>)|\)(?<-N>))(?:(?:[?+*]|\{\d+(?:,\d*)?\})[?+]?)?|\|)*$(?(N)(?!))
From the comments:
Will this validate substitutions and translations?
It will validate just the regex part of substitutions and translations. s/<this part>/.../
It is not theoretically possible to match all valid regex grammars with a regex.
It is possible if the regex engine supports recursion, such as PCRE, but that can't really be called regular expressions any more.
Indeed, a "recursive regular expression" is not a regular expression. But this an often-accepted extension to regex engines... Ironically, this extended regex doesn't match extended regexes.
"In theory, theory and practice are the same. In practice, they're not." Almost everyone who knows regular expressions knows that regular expressions does not support recursion. But PCRE and most other implementations support much more than basic regular expressions.
using this with shell script in the grep command , it shows me some error.. grep: Invalid content of {} . I am making a script that could grep a code base to find all the files that contain regular expressions
This pattern exploits an extension called recursive regular expressions. This is not supported by the POSIX flavor of regex. You could try with the -P switch, to enable the PCRE regex flavor.
Regex itself "is not a regular language and hence cannot be parsed by regular expression..."
This is true for classical regular expressions. Some modern implementations allow recursion, which makes it into a Context Free language, although it is somewhat verbose for this task.
I see where you're matching
[]()/\. and other special regex characters. Where are you allowing non-special characters? It seems like this will match^(?:[\.]+)$, but not^abcdefg$. That's a valid regex.
[^?+*{}()[\]\\|] will match any single character, not part of any of the other constructs. This includes both literal (a - z), and certain special characters (^, $, .).
How can I display an RTSP video stream in a web page?
VLC also comes with an ActiveX plugin that can display the feed in a web page:
http://wiki.videolan.org/ActiveX/HTML
<OBJECT classid="clsid:9BE31822-FDAD-461B-AD51-BE1D1C159921"
codebase="http://downloads.videolan.org/pub/videolan/vlc/latest/win32/axvlc.cab"
width="640" height="480" id="vlc" events="True">
<param name="Src" value="rtsp://cameraipaddress" />
<param name="ShowDisplay" value="True" />
<param name="AutoLoop" value="False" />
<param name="AutoPlay" value="True" />
<embed id="vlcEmb" type="application/x-google-vlc-plugin" version="VideoLAN.VLCPlugin.2" autoplay="yes" loop="no" width="640" height="480"
target="rtsp://cameraipaddress" ></embed>
</OBJECT>
Save array in mysql database
You can store the array using serialize/unserialize. With that solution they cannot easily be used from other programming languages, so you may consider using json_encode/json_decode instead (which gives you a widely supported format). Avoid using implode/explode for this since you'll probably end up with bugs or security flaws.
Note that this makes your table non-normalized, which may be a bad idea since you cannot easily query the data. Therefore consider this carefully before going forward. May you need to query the data for statistics or otherwise? Are there other reasons to normalize the data?
Also, don't save the raw $_POST array. Someone can easily make their own web form and post data to your site, thereby sending a really large form which takes up lots of space. Save those fields you want and make sure to validate the data before saving it (so you won't get invalid values).
Reading and writing environment variables in Python?
First things first :) reading books is an excellent approach to problem solving; it's the difference between band-aid fixes and long-term investments in solving problems. Never miss an opportunity to learn. :D
You might choose to interpret the 1 as a number, but environment variables don't care. They just pass around strings:
The argument envp is an array of character pointers to null-
terminated strings. These strings shall constitute the
environment for the new process image. The envp array is
terminated by a null pointer.
(From environ(3posix).)
You access environment variables in python using the os.environ dictionary-like object:
>>> import os
>>> os.environ["HOME"]
'/home/sarnold'
>>> os.environ["PATH"]
'/home/sarnold/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games'
>>> os.environ["PATH"] = os.environ["PATH"] + ":/silly/"
>>> os.environ["PATH"]
'/home/sarnold/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/silly/'
jQuery: Selecting by class and input type
You have to use (for checkboxes) :checkbox and the .name attribute to select by class.
For example:
$("input.aclass:checkbox")
The :checkbox selector:
Matches all input elements of type checkbox. Using this psuedo-selector like
$(':checkbox')is equivalent to$('*:checkbox')which is a slow selector. It's recommended to do$('input:checkbox').
You should read jQuery documentation to know about selectors.
TABLOCK vs TABLOCKX
Quite an old article on mssqlcity attempts to explain the types of locks:
Shared locks are used for operations that do not change or update data, such as a SELECT statement.
Update locks are used when SQL Server intends to modify a page, and later promotes the update page lock to an exclusive page lock before actually making the changes.
Exclusive locks are used for the data modification operations, such as UPDATE, INSERT, or DELETE.
What it doesn't discuss are Intent (which basically is a modifier for these lock types). Intent (Shared/Exclusive) locks are locks held at a higher level than the real lock. So, for instance, if your transaction has an X lock on a row, it will also have an IX lock at the table level (which stops other transactions from attempting to obtain an incompatible lock at a higher level on the table (e.g. a schema modification lock) until your transaction completes or rolls back).
The concept of "sharing" a lock is quite straightforward - multiple transactions can have a Shared lock for the same resource, whereas only a single transaction may have an Exclusive lock, and an Exclusive lock precludes any transaction from obtaining or holding a Shared lock.
Why am I getting tree conflicts in Subversion?
I don't know if this is happening to you, but sometimes I choose the wrong directory to merge and I get this error even though all the files appear completely fine.
Example:
Merge /svn/Project/branches/some-branch/Sources to /svn/Project/trunk ---> Tree conflict
Merge /svn/Project/branches/some-branch to /svn/Project/trunk ---> OK
This might be a stupid mistake, but it's not always obvious because you think it's something more complicated.
HAX kernel module is not installed
If you are running a modern Intel processor make sure HAXM (Intel® Hardware Accelerated Execution Manager) is installed:
In Android SDK Manager, ensure the option is ticked (and then installed)
Run the HAXM installer via the path below:
your_sdk_folder\extras\intel\Hardware_Accelerated_Execution_Manager\intelhaxm.exe or your_sdk_folder\extras\intel\Hardware_Accelerated_Execution_Manager\intelhaxm-android.exe
This video shows all the required steps which may help you to solve the problem.
For AMD CPUs (or older Intel CPUs without VT-x technology), you will not be able to install this and the best option is to emulate your apps using Genymotion. See: Intel's HAXM equivalent for AMD on Windows OS
Rename column SQL Server 2008
Since I often come here and then wondering how to use the brackets, this answer might be useful for those like me.
EXEC sp_rename '[DB].[dbo].[Tablename].OldColumnName', 'NewColumnName', 'COLUMN';
- The
OldColumnNamemust not be in[]. It will not work. - Don't put
NewColumnNameinto[], it will result into[[NewColumnName]].
When to use StringBuilder in Java
The problem with String concatenation is that it leads to copying of the String object with all the associated cost. StringBuilder is not threadsafe and is therefore faster than StringBuffer, which used to be the preferred choice before Java 5. As a rule of thumb, you should not do String concatenation in a loop, which will be called often. I guess doing a few concatenations here and there will not hurt you as long as you are not talking about hundreds and this of course depends on your performance requirements. If you are doing real time stuff, you should be very careful.
How to initialize an array in Kotlin with values?
In Java an array can be initialized such as:
int numbers[] = new int[] {10, 20, 30, 40, 50}
But In Kotlin an array initialized many way such as:
Any generic type of array you can use arrayOf() function :
val arr = arrayOf(10, 20, 30, 40, 50)
val genericArray = arrayOf(10, "Stack", 30.00, 40, "Fifty")
Using utility functions of Kotlin an array can be initialized
val intArray = intArrayOf(10, 20, 30, 40, 50)
Python URLLib / URLLib2 POST
u = urllib2.urlopen('http://myserver/inout-tracker', data)
h.request('POST', '/inout-tracker/index.php', data, headers)
Using the path /inout-tracker without a trailing / doesn't fetch index.php. Instead the server will issue a 302 redirect to the version with the trailing /.
Doing a 302 will typically cause clients to convert a POST to a GET request.
A required class was missing while executing org.apache.maven.plugins:maven-war-plugin:2.1.1:war
this happened to me too after adding the version tag, that was missing, to the maven-war-plugin (not sure what version was using by default, i changed to the latest, 2.6 in my case). I had to wipe .m2/repository to have the build succeed again.
I tried first to clean the maven-filtering folder (in the repo) but then instead of a MavenFilterException i was getting an ArchiverException. So i concluded the local repository was corrupted (for a version upgrade?) and i deleted everything.
That fixed it for me. Just clean your local repo.
Android SDK Manager Not Installing Components
I was getting a similar permission issue and SDK Manager could not download and install new components. Error message was (I'm running Android Studio (I/O Preview) 0.2.9)
"Unable to create C:\Program Files (x86)\Android\android-studio\sdk\temp"
Although solution was infact what @william-tate's answer says, I could not run the 'SDK Manager' directly. It fails with message:
Failed to execute tools\android.bat The system cannot find the file specified.
Instead I ran the 'tools\android.bat' as Administrator, which in turn launched SDK Manager with same permissions which fixed the issue.
Hope this helps for someone who faces the issue I faced.
What does EntityManager.flush do and why do I need to use it?
The EntityManager.flush() operation can be used the write all changes to the database before the transaction is committed. By default JPA does not normally write changes to the database until the transaction is committed. This is normally desirable as it avoids database access, resources and locks until required. It also allows database writes to be ordered, and batched for optimal database access, and to maintain integrity constraints and avoid deadlocks. This means that when you call persist, merge, or remove the database DML INSERT, UPDATE, DELETE is not executed, until commit, or until a flush is triggered.
Join between tables in two different databases?
SELECT <...>
FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;
Just make sure that in the SELECT line you specify which table columns you are using, either by full reference, or by alias. Any of the following will work:
SELECT *
SELECT t1.*,t2.column2
SELECT A.table1.column1, t2.*
etc.
How to loop through files matching wildcard in batch file
Easiest way, as I see it, is to use a for loop that calls a second batch file for processing, passing that second file the base name.
According to the for /? help, basename can be extracted using the nifty ~n option. So, the base script would read:
for %%f in (*.in) do call process.cmd %%~nf
Then, in process.cmd, assume that %0 contains the base name and act accordingly. For example:
echo The file is %0
copy %0.in %0.out
ren %0.out monkeys_are_cool.txt
There might be a better way to do this in one script, but I've always been a bit hazy on how to pull of multiple commands in a single for loop in a batch file.
EDIT: That's fantastic! I had somehow missed the page in the docs that showed that you could do multi-line blocks in a FOR loop. I am going to go have to go back and rewrite some batch files now...
Usage of unicode() and encode() functions in Python
Make sure you've set your locale settings right before running the script from the shell, e.g.
$ locale -a | grep "^en_.\+UTF-8"
en_GB.UTF-8
en_US.UTF-8
$ export LC_ALL=en_GB.UTF-8
$ export LANG=en_GB.UTF-8
Docs: man locale, man setlocale.
How do I fetch lines before/after the grep result in bash?
You can use the -B and -A to print lines before and after the match.
grep -i -B 10 'error' data
Will print the 10 lines before the match, including the matching line itself.
SQL - Select first 10 rows only?
SELECT *
FROM (SELECT ROW_NUMBER () OVER (ORDER BY user_id) user_row_no, a.* FROM temp_emp a)
WHERE user_row_no > 1 and user_row_no <11
This worked for me.If i may,i have few useful dbscripts that you can have look at
What is the use of style="clear:both"?
clear:both makes the element drop below any floated elements that precede it in the document.
You can also use clear:left or clear:right to make it drop below only those elements that have been floated left or right.
+------------+ +--------------------+
| | | |
| float:left | | without clear |
| | | |
| | +--------------------+
| | +--------------------+
| | | |
| | | with clear:right |
| | | (no effect here, |
| | | as there is no |
| | | float:right |
| | | element) |
| | | |
| | +--------------------+
| |
+------------+
+---------------------+
| |
| with clear:left |
| or clear:both |
| |
+---------------------+
Equal sized table cells to fill the entire width of the containing table
Using table-layout: fixed as a property for table and width: calc(100%/3); for td (assuming there are 3 td's). With these two properties set, the table cells will be equal in size.
Refer to the demo.
How to generate auto increment field in select query
here's for SQL server, Oracle, PostgreSQL which support window functions.
SELECT ROW_NUMBER() OVER (ORDER BY first_name, last_name) Sequence_no,
first_name,
last_name
FROM tableName
How do I read all classes from a Java package in the classpath?
Bill Burke has written a (nice article about class scanning] and then he wrote Scannotation.
Hibernate has this already written:
- org.hibernate.ejb.packaging.Scanner
- org.hibernate.ejb.packaging.NativeScanner
CDI might solve this, but don't know - haven't investigated fully yet
.
@Inject Instance< MyClass> x;
...
x.iterator()
Also for annotations:
abstract class MyAnnotationQualifier
extends AnnotationLiteral<Entity> implements Entity {}
What is the memory consumption of an object in Java?
no, 100 small objects needs more information (memory) than one big.
Access restriction: The type 'Application' is not API (restriction on required library rt.jar)
In the Eclipse top menu bar:
Windows -> Preferences -> Java -> Compiler -> Errors/Warnings ->
Deprecated and restricted API -> Forbidden reference (access rules): -> change to warning
How to convert time milliseconds to hours, min, sec format in JavaScript?
my solution
var sunriseMills = 1517573074000; // sunrise in NewYork on Feb 3, 2018 - UTC time
var offsetCityMills = -5 * 3600 * 1000; // NewYork delay to UTC
var offsetDeviceMills = new Date().getTimezoneOffset() * 60 * 1000 ; // eg. I live in Romania (UTC+2) >> getTimezoneOffset() = 120
var textTime = new Date(sunriseMills + offsetCityMills + offsetDeviceMills)
.toLocaleTimeString('en-US', { hour: 'numeric', minute: 'numeric' });
textTime will become '7.04 AM'
Ajax LARAVEL 419 POST error
I had the same issue, and it ended up being a problem with the php max post size. Increasing it solved the problem.
How to check if a value exists in a dictionary (python)
Python dictionary has get(key) function
>>> d.get(key)
For Example,
>>> d = {'1': 'one', '3': 'three', '2': 'two', '5': 'five', '4': 'four'}
>>> d.get('3')
'three'
>>> d.get('10')
None
If your key does'nt exist, will return None value.
foo = d[key] # raise error if key doesn't exist
foo = d.get(key) # return None if key doesn't exist
Content relevant to versions less than 3.0 and greater than 5.0.
.ECMAScript 6 arrow function that returns an object
You can always check this out for more custom solutions:
x => ({}[x.name] = x);
Cannot set content-type to 'application/json' in jQuery.ajax
I found the solution for this problem here. Don't forget to allow verb OPTIONS on IIS app service handler.
Works fine. Thank you André Pedroso. :-)
Why doesn't indexOf work on an array IE8?
Please careful with $.inArray if you want to use it. I just found out that the $.inArray is only works with "Array", not with String. That's why this function will not working in IE8!
The jQuery API make confusion
The $.inArray() method is similar to JavaScript's native .indexOf() method in that it returns -1 when it doesn't find a match. If the first element within the array matches value, $.inArray() returns 0
--> They shouldn't say it "Similar". Since indexOf support "String" also!
How to get image height and width using java?
Having struggled with ImageIO a lot in the past years, I think Andrew Taylor's solution is by far the best compromise (fast: not using ImageIO#read, and versatile). Thanks man!!
But I was a little frustrated to be compelled to use a local file (File/String), especially in cases where you want to check image sizes coming from, say, a multipart/form-data request where you usually retrieve InputPart/InputStream's. So I quickly made a variant that accepts File, InputStream and RandomAccessFile, based on the ability of ImageIO#createImageInputStream to do so.
Of course, such a method with Object input, may only remain private and you shall create as many polymorphic methods as needed, calling this one. You can also accept Path with Path#toFile() and URL with URL#openStream() prior to passing to this method:
private static Dimension getImageDimensions(Object input) throws IOException {
try (ImageInputStream stream = ImageIO.createImageInputStream(input)) { // accepts File, InputStream, RandomAccessFile
if(stream != null) {
IIORegistry iioRegistry = IIORegistry.getDefaultInstance();
Iterator<ImageReaderSpi> iter = iioRegistry.getServiceProviders(ImageReaderSpi.class, true);
while (iter.hasNext()) {
ImageReaderSpi readerSpi = iter.next();
if (readerSpi.canDecodeInput(stream)) {
ImageReader reader = readerSpi.createReaderInstance();
try {
reader.setInput(stream);
int width = reader.getWidth(reader.getMinIndex());
int height = reader.getHeight(reader.getMinIndex());
return new Dimension(width, height);
} finally {
reader.dispose();
}
}
}
throw new IllegalArgumentException("Can't find decoder for this image");
} else {
throw new IllegalArgumentException("Can't open stream for this image");
}
}
}
Cursor adapter and sqlite example
In Android, How to use a Cursor with a raw query in sqlite:
Cursor c = sampleDB.rawQuery("SELECT FirstName, Age FROM mytable " +
"where Age > 10 LIMIT 5", null);
if (c != null ) {
if (c.moveToFirst()) {
do {
String firstName = c.getString(c.getColumnIndex("FirstName"));
int age = c.getInt(c.getColumnIndex("Age"));
results.add("" + firstName + ",Age: " + age);
}while (c.moveToNext());
}
}
c.close();
Javascript onload not working
Try this one:
<body onload="imageRefreshBig();">
Also you might want to check Javascript console for errors (in Chrome it's under Shift + Ctrl + J).
Making the Android emulator run faster
I've been using the Intel(86) CPU/ABI. I created another emulator using the ARM(armeabi-v7a) and i found quite an improvement with the speed. I'm using platform 4.1.2 API level 16
How do I set a JLabel's background color?
For the Background, make sure you have imported java.awt.Color into your package.
In your main method, i.e. public static void main(String[] args), call the already imported method:
JLabel name_of_your_label=new JLabel("the title of your label");
name_of_your_label.setBackground(Color.the_color_you_wish);
name_of_your_label.setOpaque(true);
NB: Setting opaque will affect its visibility. Remember the case sensitivity in Java.
How do you make Vim unhighlight what you searched for?
I think the best answer is to have a leader shortcut:
<leader>c :nohl<CR>
Now whenever you have your document all junked up with highlighted terms, you just hit , + C (I have my leader mapped to a comma). It works perfectly.
Vertical Align text in a Label
You can use flexbox in 2018+:
.label-class {
display: flex;
align-items: center;
}
Browser support: https://caniuse.com/#search=flexbox
How to get DropDownList SelectedValue in Controller in MVC
I was having the same issue in asp.NET razor C#
I had a ComboBox filled with titles from an EventMessage, and I wanted to show the Content of this message with its selected value to show it in a label or TextField or any other Control...
My ComboBox was filled like this:
@Html.DropDownList("EventBerichten", new SelectList(ViewBag.EventBerichten, "EventBerichtenID", "Titel"), new { @class = "form-control", onchange = "$(this.form).submit();" })
In my EventController I had a function to go to the page, in which I wanted to show my ComboBox (which is of a different model type, so I had to use a partial view)?
The function to get from index to page in which to load the partial view:
public ActionResult EventDetail(int id)
{
Event eventOrg = db.Event.Include(s => s.Files).SingleOrDefault(s => s.EventID == id);
// EventOrg eventOrg = db.EventOrgs.Find(id);
if (eventOrg == null)
{
return HttpNotFound();
}
ViewBag.EventBerichten = GetEventBerichtenLijst(id);
ViewBag.eventOrg = eventOrg;
return View(eventOrg);
}
The function for the partial view is here:
public PartialViewResult InhoudByIdPartial(int id)
{
return PartialView(
db.EventBericht.Where(r => r.EventID == id).ToList());
}
The function to fill EventBerichten:
public List<EventBerichten> GetEventBerichtenLijst(int id)
{
var eventLijst = db.EventBericht.ToList();
var berLijst = new List<EventBerichten>();
foreach (var ber in eventLijst)
{
if (ber.EventID == id )
{
berLijst.Add(ber);
}
}
return berLijst;
}
The partialView Model looks like this:
@model IEnumerable<STUVF_back_end.Models.EventBerichten>
<table>
<tr>
<th>
EventID
</th>
<th>
Titel
</th>
<th>
Inhoud
</th>
<th>
BerichtDatum
</th>
<th>
BerichtTijd
</th>
</tr>
@foreach (var item in Model)
{
<tr>
<td>
@Html.DisplayFor(modelItem => item.EventID)
</td>
<td>
@Html.DisplayFor(modelItem => item.Titel)
</td>
<td>
@Html.DisplayFor(modelItem => item.Inhoud)
</td>
<td>
@Html.DisplayFor(modelItem => item.BerichtDatum)
</td>
<td>
@Html.DisplayFor(modelItem => item.BerichtTijd)
</td>
</tr>
}
</table>
VIEUW: This is the script used to get my output in the view
<script type="text/javascript">
$(document).ready(function () {
$("#EventBerichten").change(function () {
$("#log").ajaxError(function (event, jqxhr, settings, exception) {
alert(exception);
});
var BerichtSelected = $("select option:selected").first().text();
$.get('@Url.Action("InhoudByIdPartial")',
{ EventBerichtID: BerichtSelected }, function (data) {
$("#target").html(data);
});
});
});
</script>
@{
Html.RenderAction("InhoudByIdPartial", Model.EventID);
}
<fieldset>
<legend>Berichten over dit Evenement</legend>
<div>
@Html.DropDownList("EventBerichten", new SelectList(ViewBag.EventBerichten, "EventBerichtenID", "Titel"), new { @class = "form-control", onchange = "$(this.form).submit();" })
</div>
<br />
<div id="target">
</div>
<div id="log">
</div>
</fieldset>
When should static_cast, dynamic_cast, const_cast and reinterpret_cast be used?
It might help if you know little bit of internals...
static_cast
- C++ compiler already knows how to convert between scaler types such as
floattoint. Usestatic_castfor them. - When you ask compiler to convert from type
AtoB,static_castcallsB's constructor passingAas param. Alternatively,Acould have a conversion operator (i.e.A::operator B()). IfBdoesn't have such constructor, orAdoesn't have a conversion operator, then you get compile time error. - Cast from
A*toB*always succeeds if A and B are in inheritance hierarchy (or void) otherwise you get compile error. - Gotcha: If you cast base pointer to derived pointer but if actual object is not really derived type then you don't get error. You get bad pointer and very likely a segfault at runtime. Same goes for
A&toB&. - Gotcha: Cast from Derived to Base or viceversa creates new copy! For people coming from C#/Java, this can be a huge surprise because the result is basically a chopped off object created from Derived.
dynamic_cast
- dynamic_cast uses runtime type information to figure out if cast is valid. For example,
(Base*)to(Derived*)may fail if pointer is not actually of derived type. - This means, dynamic_cast is very expensive compared to static_cast!
- For
A*toB*, if cast is invalid then dynamic_cast will return nullptr. - For
A&toB&if cast is invalid then dynamic_cast will throw bad_cast exception. - Unlike other casts, there is runtime overhead.
const_cast
- While static_cast can do non-const to const it can't go other way around. The const_cast can do both ways.
- One example where this comes handy is iterating through some container like
set<T>which only returns its elements as const to make sure you don't change its key. However if your intent is to modify object's non-key members then it should be ok. You can use const_cast to remove constness. - Another example is when you want to implement
T& SomeClass::foo()as well asconst T& SomeClass::foo() const. To avoid code duplication, you can apply const_cast to return value of one function from another.
reinterpret_cast
- This basically says that take these bytes at this memory location and think of it as given object.
- For example, you can load 4 bytes of
floatto 4 bytes ofintto see how bits infloatlooks like. - Obviously, if data is not correct for the type, you may get segfault.
- There is no runtime overhead for this cast.
How to get resources directory path programmatically
I'm assuming the contents of src/main/resources/ is copied to WEB-INF/classes/ inside your .war at build time. If that is the case you can just do (substituting real values for the classname and the path being loaded).
URL sqlScriptUrl = MyServletContextListener.class
.getClassLoader().getResource("sql/script.sql");
Microsoft Excel mangles Diacritics in .csv files?
If you have legacy code in vb.net like I have, the following code worked for me:
Response.Clear()
Response.ClearHeaders()
Response.ContentType = "text/csv"
Response.Expires = 0
Response.AddHeader("Content-Disposition", "attachment; filename=export.csv;")
Using sw As StreamWriter = New StreamWriter(Context.Response.OutputStream, System.Text.Encoding.Unicode)
sw.Write(csv)
sw.Close()
End Using
Response.End()
Shuffling a list of objects
from random import random
my_list = range(10)
shuffled_list = sorted(my_list, key=lambda x: random())
This alternative may be useful for some applications where you want to swap the ordering function.
How much overhead does SSL impose?
I second @erickson: The pure data-transfer speed penalty is negligible. Modern CPUs reach a crypto/AES throughput of several hundred MBit/s. So unless you are on resource constrained system (mobile phone) TLS/SSL is fast enough for slinging data around.
But keep in mind that encryption makes caching and load balancing much harder. This might result in a huge performance penalty.
But connection setup is really a show stopper for many application. On low bandwidth, high packet loss, high latency connections (mobile device in the countryside) the additional roundtrips required by TLS might render something slow into something unusable.
For example we had to drop the encryption requirement for access to some of our internal web apps - they where next to unusable if used from china.
anaconda - graphviz - can't import after installation
for me the problem was solved by installing another supportive package.
so I installed graphviz package through anaconda then I failed to import it
after that I installed a second package named python-graphviz also through anaconda
then I succeeded in importing graphviz module into my code
I hope this will help someone :)
How can I view all historical changes to a file in SVN
Start with
svn log -q file | grep '^r' | cut -f1 -d' '
That will get you a list of revisions where the file changed, which you can then use to script repeated calls to svn diff.
Twig for loop for arrays with keys
There's this example in the SensioLab page on the for tag:
<h1>Members</h1>
<ul>
{% for key, user in users %}
<li>{{ key }}: {{ user.username|e }}</li>
{% endfor %}
</ul>
http://twig.sensiolabs.org/doc/tags/for.html#iterating-over-keys
How to get relative path of a file in visual studio?
I also met the same problem and I was able to get it through. So let me explain the steps I applied. I shall explain it according to your scenario.
According to my method we need to use 'Path' class and 'Assembly' class in order to get the relative path.
So first Import System.IO and System.Reflection in using statements.
Then type the below given code line.
var outPutDirectory = Path.GetDirectoryName(Assembly.GetExecutingAssembly(). CodeBase);
Actually above given line stores the path of the output directory of your project.(Here 'output' directory refers to the Debug folder of your project).
Now copy your FolderIcon directory in to the Debug folder. Then type the below given Line.
var iconPath = Path.Combine(outPutDirectory, "FolderIcon\\Folder.ico");
Now this 'iconPath ' variable contains the entire path of your Folder.ico. All you have to do is store it in a string variable. Use the line of code below for that.
string icon_path = new Uri(iconPath ).LocalPath;
Now you can use this icon_path string variable as your relative path to the icon.
Thanks.
How to show loading spinner in jQuery?
You can just use the jQuery's .ajax function and use its option beforeSend and define some function in which you can show something like a loader div and on success option you can hide that loader div.
jQuery.ajax({
type: "POST",
url: 'YOU_URL_TO_WHICH_DATA_SEND',
data:'YOUR_DATA_TO_SEND',
beforeSend: function() {
$("#loaderDiv").show();
},
success: function(data) {
$("#loaderDiv").hide();
}
});
You can have any Spinning Gif image. Here is a website that is a great AJAX Loader Generator according to your color scheme: http://ajaxload.info/
Align text in JLabel to the right
To me, it seems as if your actual intention is to put different words on different lines. But let me answer your first question:
JLabel lab=new JLabel("text");
lab.setHorizontalAlignment(SwingConstants.LEFT);
And if you have an image:
JLabel lab=new Jlabel("text");
lab.setIcon(new ImageIcon("path//img.png"));
lab.setHorizontalTextPosition(SwingConstants.LEFT);
But, I believe you want to make the label such that there are only 2 words on 1 line.
In that case try this:
String urText="<html>You can<br>use basic HTML<br>in Swing<br> components,"
+"Hope<br> I helped!";
JLabel lac=new JLabel(urText);
lac.setAlignmentX(Component.RIGHT_ALIGNMENT);
Initialising a multidimensional array in Java
I'll add that if you want to read the dimensions, you can do this:
int[][][] a = new int[4][3][2];
System.out.println(a.length); // 4
System.out.println(a[0].length); // 3
System.out.println(a[0][0].length); //2
You can also have jagged arrays, where different rows have different lengths, so a[0].length != a[1].length.
Javascript onclick hide div
Simple & Best way:
onclick="parentNode.remove()"
Deletes the complete parent from html
Should I use string.isEmpty() or "".equals(string)?
It doesn't really matter. "".equals(str) is more clear in my opinion.
isEmpty() returns count == 0;
Sending and Parsing JSON Objects in Android
GSON is easiest to use and the way to go if the data have a definite structure.
Download gson.
Add it to the referenced libraries.
package com.tut.JSON;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
public class SimpleJson extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
String jString = "{\"username\": \"tom\", \"message\": \"roger that\"} ";
GsonBuilder gsonb = new GsonBuilder();
Gson gson = gsonb.create();
Post pst;
try {
pst = gson.fromJson(jString, Post.class);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Code for Post class
package com.tut.JSON;
public class Post {
String message;
String time;
String username;
Bitmap icon;
}
How to change default install location for pip
Open Terminal and type:
pip config set global.target /Users/Bob/Library/Python/3.8/lib/python/site-packages
except instead of
/Users/Bob/Library/Python/3.8/lib/python/site-packages
you would use whatever directory you want.
PHP Change Array Keys
Use array array_flip in php
$array = array ( [1] => Sell [2] => Buy [3] => Rent [4] => Jobs )
print_r(array_flip($array));
Array ( [Sell] => 1 [Buy] => 2 [Rent] => 3 [Jobs] => 4 )
Dynamic Height Issue for UITableView Cells (Swift)
For Swift 4.2
@IBOutlet weak var tableVw: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
// Set self as tableView delegate
tableVw.delegate = self
tableVw.rowHeight = UITableView.automaticDimension
tableVw.estimatedRowHeight = UITableView.automaticDimension
}
// UITableViewDelegate Method
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableView.automaticDimension
}
Happy Coding :)
Why is Android Studio reporting "URI is not registered"?
i had the same error. I solved it by importing the project again to the android studio.
How can I specify working directory for popen
subprocess.Popen takes a cwd argument to set the Current Working Directory; you'll also want to escape your backslashes ('d:\\test\\local'), or use r'd:\test\local' so that the backslashes aren't interpreted as escape sequences by Python. The way you have it written, the \t part will be translated to a tab.
So, your new line should look like:
subprocess.Popen(r'c:\mytool\tool.exe', cwd=r'd:\test\local')
To use your Python script path as cwd, import os and define cwd using this:
os.path.dirname(os.path.realpath(__file__))
How to configure Glassfish Server in Eclipse manually
I had the same problem, to resolve it, go windows -> preferences -> servers and select runtime environment, and now you will see a new window, in the upper right you will see a option: Download additional server adapter, click and install the glassfish server.
How to verify an XPath expression in Chrome Developers tool or Firefox's Firebug?
Another option to check your xpath is to use selenium IDE.
- Install Firefox Selenium IDE
- Open your application in FireFox and open IDE
- In IDE, on a new line, paste your xpath to the target and click Find. The corresponding element would be highlighted in your application
Could not load file or assembly "System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
If you have multiple projects in your solution, then right-click on the solution icon in Visual Studio and select 'Manage NuGet Packages for Solution', then click on the fourth tab 'Consolidate' to consolidate all your projects to the same version of the DLLs. This will give you a list of referenced assemblies to consolidate. Click on each item in the list, then click install in the tab that appears to the right.
Accidentally committed .idea directory files into git
You should add a .gitignore file to your project and add /.idea to it. You should add each directory / file in one line.
If you have an existing .gitignore file then you should simply add a new line to the file and put /.idea to the new line.
After that run git rm -r --cached .idea command.
If you faced an error you can run git rm -r -f --cached .idea command. After all run git add . and then git commit -m "Removed .idea directory and added a .gitignore file" and finally push the changes by running git push command.
"Exception has been thrown by the target of an invocation" error (mscorlib)
Got same error, solved changing target platform from "Mixed Platforms" to "Any CPU"
Visually managing MongoDB documents and collections
MongoVUE download is now available @ http://blog.mongovue.com/downloads
Node.js Error: connect ECONNREFUSED
Check with starting mysql in terminal. Use below command
mysql-ctl start
In my case its worked
Labels for radio buttons in rails form
This an example from my project for rating using radio buttons and its labels
<div class="rating">
<%= form.radio_button :star, '1' %>
<%= form.label :star, '?', value: '1' %>
<%= form.radio_button :star, '2' %>
<%= form.label :star, '?', value: '2' %>
<%= form.radio_button :star, '3' %>
<%= form.label :star, '?', value: '3' %>
<%= form.radio_button :star, '4' %>
<%= form.label :star, '?', value: '4' %>
<%= form.radio_button :star, '5' %>
<%= form.label :star, '?', value: '5' %>
</div>
List of tables, db schema, dump etc using the Python sqlite3 API
I'm not familiar with the Python API but you can always use
SELECT * FROM sqlite_master;
jsPDF multi page PDF with HTML renderer
html2canvas(element[0], {
onrendered: function (canvas) {
pages = Math.ceil(element[0].clientHeight / 1450);
for (i = 0; i <= pages; i += 1) {
if (i > 0) {
pdf.addPage();
}
srcImg = canvas;
sX = 0;
sY = 1450 * i;
sWidth = 1100;
sHeight = 1450;
dX = 0;
dY = 0;
dWidth = 1100;
dHeight = 1450;
window.onePageCanvas = document.createElement("canvas");
onePageCanvas.setAttribute('width', 1100);
onePageCanvas.setAttribute('height', 1450);
ctx = onePageCanvas.getContext('2d');
ctx.drawImage(srcImg, sX, sY, sWidth, sHeight, dX, dY, dWidth, dHeight);
canvasDataURL = onePageCanvas.toDataURL("image/png");
width = onePageCanvas.width;
height = onePageCanvas.clientHeight;
pdf.setPage(i + 1);
pdf.addImage(canvasDataURL, 'PNG', 35, 30, (width * 0.5), (height * 0.5));
}
pdf.save('testfilename.pdf');
}
});
Accessing clicked element in angularjs
While AngularJS allows you to get a hand on a click event (and thus a target of it) with the following syntax (note the $event argument to the setMaster function; documentation here: http://docs.angularjs.org/api/ng.directive:ngClick):
function AdminController($scope) {
$scope.setMaster = function(obj, $event){
console.log($event.target);
}
}
this is not very angular-way of solving this problem. With AngularJS the focus is on the model manipulation. One would mutate a model and let AngularJS figure out rendering.
The AngularJS-way of solving this problem (without using jQuery and without the need to pass the $event argument) would be:
<div ng-controller="AdminController">
<ul class="list-holder">
<li ng-repeat="section in sections" ng-class="{active : isSelected(section)}">
<a ng-click="setMaster(section)">{{section.name}}</a>
</li>
</ul>
<hr>
{{selected | json}}
</div>
where methods in the controller would look like this:
$scope.setMaster = function(section) {
$scope.selected = section;
}
$scope.isSelected = function(section) {
return $scope.selected === section;
}
Here is the complete jsFiddle: http://jsfiddle.net/pkozlowski_opensource/WXJ3p/15/
How to exclude file only from root folder in Git
If the above solution does not work for you, try this:
#1.1 Do NOT ignore file pattern in any subdirectory
!*/config.php
#1.2 ...only ignore it in the current directory
/config.php
##########################
# 2.1 Ignore file pattern everywhere
config.php
# 2.2 ...but NOT in the current directory
!/config.php
ASP.NET MVC - Extract parameter of an URL
public ActionResult Index(int id,string value)
This function get values form URL After that you can use below function
Request.RawUrl - Return complete URL of Current page
RouteData.Values - Return Collection of Values of URL
Request.Params - Return Name Value Collections
Phonegap Cordova installation Windows
Phonegap Cordova Installation on Windows
Requirements
- Eclipse + ADT Plugin
- Android SDK Tool
- Android Platform Tools
- Latest PhoneGap zip folder. Extract its contents.
Supported Android Devices
Android 2.2 Android 2.3 Android 4.x Phonegap Cordova Installation
Set PATH environment variable for android
From desktop, right click My Computer and click Properties.
Click Advance System Settings link in the left column.
In the system properties window click the environment variables button.
Select the PATH variable from the System variables section. Select the Edit button. You need to add the path to your Android SDK platform-tools and tools directory. For Example: D:\adt-bundle-windows-x86_64-20130219\sdk\platform-tools;D:\adt-bundle-windows-x86_64-20130219\sdk\tools Save your Edit. Close the Environment Variable dialog.
- Additionally, you may need to include %JAVA_HOME%\bin to your PATH as well. To check to see if this is required run a command prompt and type java. If the program could not be found add %JAVA_HOME%\bin to the PATH. You may need to specify the full path instead of using %JAVA_HOME% environment variable.
- Finally, you may need to include %ANT_HOME%\bin to your PATH as well. To check to see if this is required run a command prompt and type ant. If program cannot be found then add %ANT_HOME%\bin to the PATH. You may need to specify the full path instead of using the %ANT_HOME% environment variable. Set-up New Project
Open Command Prompt, navigate to bin directory within the android sub-folder of the Cordova distribution.
Type in: ./create
Then press Enter.Launch Eclipse. In File Menu Item and select to Import…
Import Select “Existing Android Code into Workspace” and click ‘Next >’.
Browse the project created through command prompt. And click ‘Finish’. Deploy to Emulator From within Eclipse, press this toolbar icon.
Once open, the Android SDK Manager displays various runtime libraries Install the APIs as per requirement from here. From within Eclipse, press this toolbar icon.
Choose and device definition from the list which comes. (There is only one item in the current list.) Press New… in the above window to create new Android Virtual Device(AVD) and use it to run your project.
To open the emulator as a separate application, Select the AVD and press Start. It launches much as it would on device, with additional controls available for hardware buttons:
Deploy to Device:
Make sure USB debugging is enabled on your device and plug it into your system. Right Click the Project and go to Run As > Android Application.
Java Enum return Int
In my opinion the most readable version
public enum PIN_PULL_RESISTANCE {
PULL_UP {
@Override
public int getValue() {
return 1;
}
},
PULL_DOWN {
@Override
public int getValue() {
return 0;
}
};
public abstract int getValue();
}
How to show code but hide output in RMarkdown?
For what it's worth.
```{r eval=FALSE}
The document will display the code by default but will prevent the code block from being executed, and thus will also not display any results.
DateTime.Today.ToString("dd/mm/yyyy") returns invalid DateTime Value
Lower mm means minutes, so
DateTime.Now.ToString("dd/MM/yyyy");
or
DateTime.Now.ToString("d");
or
DateTime.Now.ToShortDateString()
WinSCP: Permission denied. Error code: 3 Error message from server: Permission denied
You possibly do not have create permissions to the folder. So WinSCP fails to create a temporary file for the transfer.
You have two options:
Grant write permissions to the folder to the user or group you log in with (
myuser), or change the ownership of the folder to the user, orDisable a transfer to temporary file.
In Preferences, go to Transfer > Endurance page and in Enable transfer resume/transfer to temporary file name for select Disable:
How to format date with hours, minutes and seconds when using jQuery UI Datepicker?
If don't like to add time picker, we can use just javascript for time part.
var dateObj=new Date();
var date = $.datepicker.formatDate('dd M yy', dateObj);
var time = dateObj.getHours()+":"+dateObj.getMinutes()+":"+dateObj.getSeconds();
console.log(date," ",time);
Pointers in JavaScript?
It just doesn't support pointers, end of story :-(.
I would like to add that, while I'm brand new and coming from a C background, from what I'm reading about the event loop and stack, you should keep whichever object as close to its caller as possible. As I'm brand new, I could have this wrong.
A lot of answers here suggest to make it global, but again if I'm reading correctly, that could possibly increase the stack hops and in a way, possibly fragment your event loop needlessly (depending on what the called object is currently doing) .
Also, any example given that mimics pointers, is just 1 in many ways to do the same thing, which will not be a pointer.
Make cross-domain ajax JSONP request with jQuery
You need to use the ajax-cross-origin plugin: http://www.ajax-cross-origin.com/
Just add the option crossOrigin: true
$.ajax({
crossOrigin: true,
url: url,
success: function(data) {
console.log(data);
}
});
Print debugging info from stored procedure in MySQL
One workaround is just to use select without any other clauses.
Establish a VPN connection in cmd
I know this is a very old thread but I was looking for a solution to the same problem and I came across this before eventually finding the answer and I wanted to just post it here so somebody else in my shoes would have a shorter trek across the internet.
****Note that you probably have to run cmd.exe as an administrator for this to work**
So here we go, open up the prompt (as an adminstrator) and go to your System32 directory. Then run
C:\Windows\System32>cd ras
Now you'll be in the ras directory. Now it's time to create a temporary file with our connection info that we will then append onto the rasphone.pbk file that will allow us to use the rasdial command.
So to create our temp file run:
C:\Windows\System32\ras>copy con temp.txt
Now it will let you type the contents of the file, which should look like this:
[CONNECTION NAME]
MEDIA=rastapi
Port=VPN2-0
Device=WAN Miniport (IKEv2)
DEVICE=vpn
PhoneNumber=vpn.server.address.com
So replace CONNECTION NAME and vpn.server.address.com with the desired connection name and the vpn server address you want.
Make a new line and press Ctrl+Z to finish and save.
Now we will append this onto the rasphone.pbk file that may or may not exist depending on if you already have network connections configured or not. To do this we will run the following command:
C:\Windows\System32\ras>type temp.txt >> rasphone.pbk
This will append the contents of temp.txt to the end of rasphone.pbk, or if rasphone.pbk doesn't exist it will be created. Now we might as well delete our temp file:
C:\Windows\System32\ras>del temp.txt
Now we can connect to our newly configured VPN server with the following command:
C:\Windows\System32\ras>rasdial "CONNECTION NAME" myUsername myPassword
When we want to disconnect we can run:
C:\Windows\System32\ras>rasdial /DISCONNECT
That should cover it! I've included a direct copy and past from the command line of me setting up a connection for and connecting to a canadian vpn server with this method:
Microsoft Windows [Version 6.2.9200]
(c) 2012 Microsoft Corporation. All rights reserved.
C:\Windows\system32>cd ras
C:\Windows\System32\ras>copy con temp.txt
[Canada VPN Connection]
MEDIA=rastapi
Port=VPN2-0
Device=WAN Miniport (IKEv2)
DEVICE=vpn
PhoneNumber=ca.justfreevpn.com
^Z
1 file(s) copied.
C:\Windows\System32\ras>type temp.txt >> rasphone.pbk
C:\Windows\System32\ras>del temp.txt
C:\Windows\System32\ras>rasdial "Canada VPN Connection" justfreevpn 2932
Connecting to Canada VPN Connection...
Verifying username and password...
Connecting to Canada VPN Connection...
Connecting to Canada VPN Connection...
Verifying username and password...
Registering your computer on the network...
Successfully connected to Canada VPN Connection.
Command completed successfully.
C:\Windows\System32\ras>rasdial /DISCONNECT
Command completed successfully.
C:\Windows\System32\ras>
Hope this helps.
How can I print out just the index of a pandas dataframe?
You can access the index attribute of a df using df.index[i]
>> import pandas as pd
>> import numpy as np
>> df = pd.DataFrame({'a':np.arange(5), 'b':np.random.randn(5)})
a b
0 0 1.088998
1 1 -1.381735
2 2 0.035058
3 3 -2.273023
4 4 1.345342
>> df.index[1] ## Second index
>> df.index[-1] ## Last index
>> for i in xrange(len(df)):print df.index[i] ## Using loop
...
0
1
2
3
4
Observable Finally on Subscribe
I'm now using RxJS 5.5.7 in an Angular application and using finalize operator has a weird behavior for my use case since is fired before success or error callbacks.
Simple example:
// Simulate an AJAX callback...
of(null)
.pipe(
delay(2000),
finalize(() => {
// Do some work after complete...
console.log('Finalize method executed before "Data available" (or error thrown)');
})
)
.subscribe(
response => {
console.log('Data available.');
},
err => {
console.error(err);
}
);
I have had to use the add medhod in the subscription to accomplish what I want. Basically a finally callback after the success or error callbacks are done. Like a try..catch..finally block or Promise.finally method.
Simple example:
// Simulate an AJAX callback...
of(null)
.pipe(
delay(2000)
)
.subscribe(
response => {
console.log('Data available.');
},
err => {
console.error(err);
}
);
.add(() => {
// Do some work after complete...
console.log('At this point the success or error callbacks has been completed.');
});
Rebuild Docker container on file changes
You can run build for a specific service by running docker-compose up --build <service name> where the service name must match how did you call it in your docker-compose file.
Example
Let's assume that your docker-compose file contains many services (.net app - database - let's encrypt... etc) and you want to update only the .net app which named as application in docker-compose file.
You can then simply run docker-compose up --build application
Extra parameters
In case you want to add extra parameters to your command such as -d for running in the background, the parameter must be before the service name:
docker-compose up --build -d application
Where to get this Java.exe file for a SQL Developer installation
I found my java.exe that worked for SQL Developer at C:\ORACLE11G\product\11.2.0\client_1\jdk\bin where C:\ORACLE11G is my Oracle Home. The client that I have installed is 11.2.0.
Hope this helps.
What does the DOCKER_HOST variable do?
Ok, I think I got it.
The client is the docker command installed into OS X.
The host is the Boot2Docker VM.
The daemon is a background service running inside Boot2Docker.
This variable tells the client how to connect to the daemon.
When starting Boot2Docker, the terminal window that pops up already has DOCKER_HOST set, so that's why docker commands work. However, to run Docker commands in other terminal windows, you need to set this variable in those windows.
Failing to set it gives a message like this:
$ docker run hello-world
2014/08/11 11:41:42 Post http:///var/run/docker.sock/v1.13/containers/create:
dial unix /var/run/docker.sock: no such file or directory
One way to fix that would be to simply do this:
$ export DOCKER_HOST=tcp://192.168.59.103:2375
But, as pointed out by others, it's better to do this:
$ $(boot2docker shellinit)
$ docker run hello-world
Hello from Docker. [...]
To spell out this possibly non-intuitive Bash command, running boot2docker shellinit returns a set of Bash commands that set environment variables:
export DOCKER_HOST=tcp://192.168.59.103:2376
export DOCKER_CERT_PATH=/Users/ddavison/.boot2docker/certs/boot2docker-vm
export DOCKER_TLS_VERIFY=1
Hence running $(boot2docker shellinit) generates those commands, and then runs them.
Is there any pythonic way to combine two dicts (adding values for keys that appear in both)?
A more generic solution, which works for non-numeric values as well:
a = {'a': 'foo', 'b':'bar', 'c': 'baz'}
b = {'a': 'spam', 'c':'ham', 'x': 'blah'}
r = dict(a.items() + b.items() +
[(k, a[k] + b[k]) for k in set(b) & set(a)])
or even more generic:
def combine_dicts(a, b, op=operator.add):
return dict(a.items() + b.items() +
[(k, op(a[k], b[k])) for k in set(b) & set(a)])
For example:
>>> a = {'a': 2, 'b':3, 'c':4}
>>> b = {'a': 5, 'c':6, 'x':7}
>>> import operator
>>> print combine_dicts(a, b, operator.mul)
{'a': 10, 'x': 7, 'c': 24, 'b': 3}
jQuery: print_r() display equivalent?
How about something like:
<script src='http://code.jquery.com/jquery-latest.js'></script>
function print_r(o){
return JSON.stringify(o,null,'\t').replace(/\n/g,'<br>').replace(/\t/g,' '); }
Android Debug Bridge (adb) device - no permissions
...the OP’s own answer is wrong in so far, that there are no “special system permissions”. – The “no permission” problem boils down to ... no permissions.
Unfortunately it is not easy to debug, because adb makes it a secret which device it tries to access! On Linux, it tries to open the “USB serial converter” device of the phone, which is e.g. /dev/bus/usb/001/115 (your bus number and device address will vary). This is sometimes linked and used from /dev/android_adb.
lsusb will help to find bus number and device address. Beware that the device address will change for sure if you re-plug, as might the bus number if the port gets confused about which speed to use (e.g. one physical port ends up on one logical bus or another).
An lsusb-line looks similar to this: Bus 001 Device 115: ID 4321:fedc bla bla bla
lsusb -v might help you to find the device if the “bla bla bla” is not hint enough (sometimes it does neither contain the manufacturer, nor the model of the phone).
Once you know the device, check with your own eyes that ls -a /dev/bus/usb/001/115 is really accessible for the user in question! Then check that it works with chmod and fix your udev setup.
PS1: /dev/android_adb can only point to one device, so make sure it does what you want.
PS2: Unrelated to this question, but less well known: adb has a fixed list of vendor ids it goes through. This list can be extended from ~/.android/adb_usb.ini, which should contain 0x4321 (if we follow my example lsusb line from above). – Not needed here, as you don’t even get a “no permissions” if the vendor id is not known.
What's the difference between a Python module and a Python package?
A late answer, yet another definition:
A package is represented by an imported top-entity which could either be a self-contained module, or the
__init__.pyspecial module as the top-entity from a set of modules within a sub directory structure.
So physically a package is a distribution unit, which provides one or more modules.
get client time zone from browser
Often when people are looking for "timezones", what will suffice is just "UTC offset". e.g., their server is in UTC+5 and they want to know that their client is running in UTC-8.
In plain old javascript (new Date()).getTimezoneOffset()/60 will return the current number of hours offset from UTC.
It's worth noting a possible "gotcha" in the sign of the getTimezoneOffset() return value (from MDN docs):
The time-zone offset is the difference, in minutes, between UTC and local time. Note that this means that the offset is positive if the local timezone is behind UTC and negative if it is ahead. For example, for time zone UTC+10:00 (Australian Eastern Standard Time, Vladivostok Time, Chamorro Standard Time), -600 will be returned.
However, I recommend you use the day.js for time/date related Javascript code. In which case you can get an ISO 8601 formatted UTC offset by running:
> dayjs().format("Z")
"-08:00"
It probably bears mentioning that the client can easily falsify this information.
(Note: this answer originally recommended https://momentjs.com/, but dayjs is a more modern, smaller alternative.)
python JSON object must be str, bytes or bytearray, not 'dict
import json
data = json.load(open('/Users/laxmanjeergal/Desktop/json.json'))
jtopy=json.dumps(data) #json.dumps take a dictionary as input and returns a string as output.
dict_json=json.loads(jtopy) # json.loads take a string as input and returns a dictionary as output.
print(dict_json["shipments"])
Get all child elements
Another veneration of find_elements_by_xpath(".//*") is:
from selenium.webdriver.common.by import By
find_elements(By.XPATH, ".//*")
Angular directives - when and how to use compile, controller, pre-link and post-link
What else happens between these function calls?
The various directive functions are executed from within two other angular functions called $compile (where the directive's compile is executed) and an internal function called nodeLinkFn (where the directive's controller, preLink and postLink are executed). Various things happen within the angular function before and after the directive functions are called. Perhaps most notably is the child recursion. The following simplified illustration shows key steps within the compile and link phases:
To demonstrate the these steps, let's use the following HTML markup:
<div ng-repeat="i in [0,1,2]">
<my-element>
<div>Inner content</div>
</my-element>
</div>
With the following directive:
myApp.directive( 'myElement', function() {
return {
restrict: 'EA',
transclude: true,
template: '<div>{{label}}<div ng-transclude></div></div>'
}
});
Compile
The compile API looks like so:
compile: function compile( tElement, tAttributes ) { ... }
Often the parameters are prefixed with t to signify the elements and attributes provided are those of the source template, rather than that of the instance.
Prior to the call to compile transcluded content (if any) is removed, and the template is applied to the markup. Thus, the element provided to the compile function will look like so:
<my-element>
<div>
"{{label}}"
<div ng-transclude></div>
</div>
</my-element>
Notice that the transcluded content is not re-inserted at this point.
Following the call to the directive's .compile, Angular will traverse all child elements, including those that may have just been introduced by the directive (the template elements, for instance).
Instance creation
In our case, three instances of the source template above will be created (by ng-repeat). Thus, the following sequence will execute three times, once per instance.
Controller
The controller API involves:
controller: function( $scope, $element, $attrs, $transclude ) { ... }
Entering the link phase, the link function returned via $compile is now provided with a scope.
First, the link function create a child scope (scope: true) or an isolated scope (scope: {...}) if requested.
The controller is then executed, provided with the scope of the instance element.
Pre-link
The pre-link API looks like so:
function preLink( scope, element, attributes, controller ) { ... }
Virtually nothing happens between the call to the directive's .controller and the .preLink function. Angular still provide recommendation as to how each should be used.
Following the .preLink call, the link function will traverse each child element - calling the correct link function and attaching to it the current scope (which serves as the parent scope for child elements).
Post-link
The post-link API is similar to that of the pre-link function:
function postLink( scope, element, attributes, controller ) { ... }
Perhaps worth noticing that once a directive's .postLink function is called, the link process of all its children elements has completed, including all the children's .postLink functions.
This means that by the time .postLink is called, the children are 'live' are ready. This includes:
- data binding
- transclusion applied
- scope attached
The template at this stage will thus look like so:
<my-element>
<div class="ng-binding">
"{{label}}"
<div ng-transclude>
<div class="ng-scope">Inner content</div>
</div>
</div>
</my-element>
Disable developer mode extensions pop up in Chrome
1) Wait for the popup balloon to appear.
2) Open a new tab.
3) Close the a new tab. The popup will be gone from the original tab.
A small Chrome extension can automate these steps:
manifest.json
{
"name": "Open and close tab",
"description": "After Chrome starts, open and close a new tab.",
"version": "1.0",
"manifest_version": 2,
"permissions": ["tabs"],
"background": {
"scripts": ["background.js"],
"persistent": false
}
}
background.js
// This runs when Chrome starts up
chrome.runtime.onStartup.addListener(function() {
// Execute the inner function after a few seconds
setTimeout(function() {
// Open new tab
chrome.tabs.create({url: "about:blank"});
// Get tab ID of newly opened tab, then close the tab
chrome.tabs.query({'currentWindow': true}, function(tabs) {
var newTabId = tabs[1].id;
chrome.tabs.remove(newTabId);
});
}, 5000);
});
With this extension installed, launch Chrome and immediately switch apps before the popup appears... a few seconds later, the popup will be gone and you won't see it when you switch back to Chrome.
Draw path between two points using Google Maps Android API v2
in below code midpointsList is an ArrayList of waypoints
private String getMapsApiDirectionsUrl(GoogleMap googleMap, LatLng startLatLng, LatLng endLatLng, ArrayList<LatLng> midpointsList) {
String origin = "origin=" + startLatLng.latitude + "," + startLatLng.longitude;
String midpoints = "";
for (int mid = 0; mid < midpointsList.size(); mid++) {
midpoints += "|" + midpointsList.get(mid).latitude + "," + midpointsList.get(mid).longitude;
}
String waypoints = "waypoints=optimize:true" + midpoints + "|";
String destination = "destination=" + endLatLng.latitude + "," + endLatLng.longitude;
String key = "key=AIzaSyCV1sOa_7vASRBs6S3S6t1KofFvDhjohvI";
String sensor = "sensor=false";
String params = origin + "&" + waypoints + "&" + destination + "&" + sensor + "&" + key;
String output = "json";
String url = "https://maps.googleapis.com/maps/api/directions/" + output + "?" + params;
Log.e("url", url);
parseDirectionApidata(url, googleMap);
return url;
}
Then copy and paste this url in your browser to check And the below code is to parse the url
private void parseDirectionApidata(String url, final GoogleMap googleMap) {
final JSONObject jsonObject = new JSONObject();
try {
AppUtill.getJsonWithHTTPPost(ViewMapActivity.this, 1, new ServiceCallBack() {
@Override
public void serviceCallBack(int id, JSONObject jsonResult) throws JSONException {
if (jsonResult != null) {
Log.e("jsonRes", jsonResult.toString());
String status = jsonResult.optString("status");
if (status.equalsIgnoreCase("ok")) {
drawPath(jsonResult, googleMap);
}
} else {
Toast.makeText(ViewMapActivity.this, "Unable to parse Directions Data", Toast.LENGTH_LONG).show();
}
}
}, url, jsonObject);
} catch (Exception e) {
e.printStackTrace();
}
}
And then pass the result to the drawPath method
public void drawPath(JSONObject jObject, GoogleMap googleMap) {
List<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String, String>>>();
JSONArray jRoutes = null;
JSONArray jLegs = null;
JSONArray jSteps = null;
List<LatLng> list = null;
try {
Toast.makeText(ViewMapActivity.this, "Drawing Path...", Toast.LENGTH_SHORT).show();
jRoutes = jObject.getJSONArray("routes");
/** Traversing all routes */
for (int i = 0; i < jRoutes.length(); i++) {
jLegs = ((JSONObject) jRoutes.get(i)).getJSONArray("legs");
List path = new ArrayList<HashMap<String, String>>();
/** Traversing all legs */
for (int j = 0; j < jLegs.length(); j++) {
jSteps = ((JSONObject) jLegs.get(j)).getJSONArray("steps");
/** Traversing all steps */
for (int k = 0; k < jSteps.length(); k++) {
String polyline = "";
polyline = (String) ((JSONObject) ((JSONObject) jSteps.get(k)).get("polyline")).get("points");
list = decodePoly(polyline);
}
Log.e("list", list.toString());
routes.add(path);
Log.e("routes", routes.toString());
if (list != null) {
Polyline line = googleMap.addPolyline(new PolylineOptions()
.addAll(list)
.width(12)
.color(Color.parseColor("#FF0000"))//Google maps blue color #05b1fb
.geodesic(true)
);
}
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<LatLng>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return poly;
}
decode poly function is to decode the points(lat and long) provided by Directions API in encoded form
'setInterval' vs 'setTimeout'
setTimeout(expression, timeout); runs the code/function once after the timeout.
setInterval(expression, timeout); runs the code/function in intervals, with the length of the timeout between them.
Example:
var intervalID = setInterval(alert, 1000); // Will alert every second.
// clearInterval(intervalID); // Will clear the timer.
setTimeout(alert, 1000); // Will alert once, after a second.
How to convert int[] into List<Integer> in Java?
Also from guava libraries... com.google.common.primitives.Ints:
List<Integer> Ints.asList(int...)
What is "406-Not Acceptable Response" in HTTP?
If you are using 'request.js' you might use the following:
var options = {
url: 'localhost',
method: 'GET',
headers:{
Accept: '*/*'
}
}
request(options, function (error, response, body) {
...
})
How to set delay in android?
Here's an example where I change the background image from one to another with a 2 second alpha fade delay both ways - 2s fadeout of the original image into a 2s fadein into the 2nd image.
public void fadeImageFunction(View view) {
backgroundImage = (ImageView) findViewById(R.id.imageViewBackground);
backgroundImage.animate().alpha(0f).setDuration(2000);
// A new thread with a 2-second delay before changing the background image
new Timer().schedule(
new TimerTask(){
@Override
public void run(){
// you cannot touch the UI from another thread. This thread now calls a function on the main thread
changeBackgroundImage();
}
}, 2000);
}
// this function runs on the main ui thread
private void changeBackgroundImage(){
runOnUiThread(new Runnable() {
@Override
public void run() {
backgroundImage = (ImageView) findViewById(R.id.imageViewBackground);
backgroundImage.setImageResource(R.drawable.supes);
backgroundImage.animate().alpha(1f).setDuration(2000);
}
});
}
"No resource identifier found for attribute 'showAsAction' in package 'android'"
Add "android-support-v7-appcompat.jar" to Android Private Libraries
index.php not loading by default
While adding 'DirectoryIndex index.php' to a .htaccess file may work,
NOTE:
In general, you should never use .htaccess files
This is quoted from http://httpd.apache.org/docs/1.3/howto/htaccess.html
Although this refers to an older version of apache, I believe the principle still applies.
Adding the following to your httpd.conf (if you have access to it) is considered better form, causes less server overhead and has the exact same effect:
<Directory /myapp>
DirectoryIndex index.php
</Directory>
Changing navigation bar color in Swift
If you have customized navigation controller, you can use above code snippet. So in my case, I've used as following code pieces.
Swift 3.0, XCode 8.1 version
navigationController.navigationBar.barTintColor = UIColor.green
Navigation Bar Text:
navigationController.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.orange]
It is very helpful talks.
Simple way to measure cell execution time in ipython notebook
%time and %timeit now come part of ipython's built-in magic commands
AngularJS - Building a dynamic table based on a json
TGrid is another option that people don't usually find in a google search. If the other grids you find don't suit your needs, you can give it a try, its free
Pure CSS collapse/expand div
Depending on what browsers/devices you are looking to support, or what you are prepared to put up with for non-compliant browsers you may want to check out the <summary> and <detail> tags. They are for exactly this purpose. No css is required at all as the collapsing and showing are part of the tags definition/formatting.
I've made an example here:
<details>
<summary>This is what you want to show before expanding</summary>
<p>This is where you put the details that are shown once expanded</p>
</details>
Browser support varies. Try in webkit for best results. Other browsers may default to showing all the solutions. You can perhaps fallback to the hide/show method described above.
Fastest way to update 120 Million records
set rowcount 1000000
Update table set int_field = -1 where int_field<>-1
see how fast that takes, adjust and repeat as necessary
Visual Studio 2013 error MS8020 Build tools v140 cannot be found
That's the platform toolset for VS2015. You uninstalled it, therefore it is no longer available.
To change your Platform Toolset:
- Right click your project, go to Properties.
- Under Configuration Properties, go to General.
- Change your Platform Toolset to one of the available ones.
Force table column widths to always be fixed regardless of contents
You can also use percentages, and/or specify in the column headers:
<table width="300">
<tr>
<th width="20%">Column 1</th>
<th width="20%">Column 2</th>
<th width="20%">Column 3</th>
<th width="20%">Column 4</th>
<th width="20%">Column 5</th>
</tr>
<tr>
<!--- row data -->
</tr>
</table>
The bonus with percentages is lower code maintenance: you can change your table width without having to re-specify the column widths.
Caveat: It is my understanding that table width specified in pixels isn't supported in HTML 5; you need to use CSS instead.
Can I pass column name as input parameter in SQL stored Procedure
This is not possible. Either use dynamic SQL (dangerous) or a gigantic case expression (slow).
How to play YouTube video in my Android application?
MediaPlayer mp=new MediaPlayer();
mp.setDataSource(path);
mp.setScreenOnWhilePlaying(true);
mp.setDisplay(holder);
mp.prepare();
mp.start();
Concatenating elements in an array to a string
Arrays.toString() can be used to convert String Array to String. The extra characters can be removed by using Regex expressions or simply by using replace method.
Arrays.toString(strArray).replace(",", "").replace("[", "").replace("]", "");
Java 8 has introduced new method for String join public static String join(CharSequence delimiter, CharSequence... elements)
String.join("", strArray);
What is the 'pythonic' equivalent to the 'fold' function from functional programming?
You can reinvent the wheel as well:
def fold(f, l, a):
"""
f: the function to apply
l: the list to fold
a: the accumulator, who is also the 'zero' on the first call
"""
return a if(len(l) == 0) else fold(f, l[1:], f(a, l[0]))
print "Sum:", fold(lambda x, y : x+y, [1,2,3,4,5], 0)
print "Any:", fold(lambda x, y : x or y, [False, True, False], False)
print "All:", fold(lambda x, y : x and y, [False, True, False], True)
# Prove that result can be of a different type of the list's elements
print "Count(x==True):",
print fold(lambda x, y : x+1 if(y) else x, [False, True, True], 0)
MySql Query Replace NULL with Empty String in Select
I have nulls (NULL as default value) in a non-required field in a database. They do not cause the value "null" to show up in a web page. However, the value "null" is put in place when creating data via a web page input form. This was due to the JavaScript taking null and transcribing it to the string "null" when submitting the data via AJAX and jQuery. Make sure that this is not the base issue as simply doing the above is only a band-aid to the actual issue. I also implemented the above solution IFNULL(...) as a double measure. Thanks.
How to create a CPU spike with a bash command
:(){ :|:& };:
This fork bomb will cause havoc to the CPU and will likely crash your computer.
Python: finding an element in a list
I found this by adapting some tutos. Thanks to google, and to all of you ;)
def findall(L, test):
i=0
indices = []
while(True):
try:
# next value in list passing the test
nextvalue = filter(test, L[i:])[0]
# add index of this value in the index list,
# by searching the value in L[i:]
indices.append(L.index(nextvalue, i))
# iterate i, that is the next index from where to search
i=indices[-1]+1
#when there is no further "good value", filter returns [],
# hence there is an out of range exeption
except IndexError:
return indices
A very simple use:
a = [0,0,2,1]
ind = findall(a, lambda x:x>0))
[2, 3]
P.S. scuse my english
In Bootstrap 3,How to change the distance between rows in vertical?
If it was me I would introduce new CSS class and use along with unmodified bootstrap row class.
HTML
<div class="row extra-bottom-padding" id="a">
<img>...</img>
<div>
<div class="row" id="b">
<button>..</button>
<div>
CSS
.row.extra-bottom-padding{
margin-bottom: 20px;
}
Which selector do I need to select an option by its text?
This worked for me: $("#test").find("option:contains('abc')");
Convert Numeric value to Varchar
First convert the numeric value then add the 'S':
select convert(varchar(10),StandardCost) +'S'
from DimProduct where ProductKey = 212
How to make for loops in Java increase by increments other than 1
Change
for(j = 0; j<=90; j+3)
to
for(j = 0; j<=90; j=j+3)
Capturing "Delete" Keypress with jQuery
Javascript Keycodes
- e.keyCode == 8 for backspace
- e.keyCode == 46 for forward backspace or delete button in PC's
Except this detail Colin & Tod's answer is working.
in python how do I convert a single digit number into a double digits string?
In Python 3.6 you can use so called f-strings. In my opinion this method is much clearer to read.
>>> f'{a:02d}'
'05'
Advantages of using display:inline-block vs float:left in CSS
There is one characteristic about inline-block which may not be straight-forward though. That is that the default value for vertical-align in CSS is baseline. This may cause some unexpected alignment behavior. Look at this article.
http://www.brunildo.org/test/inline-block.html
Instead, when you do a float:left, the divs are independent of each other and you can align them using margin easily.
Center text in div?
display: block;
text-align: center;
java.io.IOException: Invalid Keystore format
I think the keystore file you want to use has a different or unsupported format in respect to your Java version. Could you post some more info of your task?
In general, to solve this issue you might need to recreate the whole keystore (using some other JDK version for example). In export-import the keys between the old and the new one - if you manage to open the old one somewhere else.
If it is simply an unsupported version, try the BouncyCastle crypto provider for example (although I'm not sure If it adds support to Java for more keystore types?).
Edit: I looked at the feature spec of BC.
How to delete all files and folders in a directory?
It's not the best way to deal with the issue above. But it's an alternative one...
while (Directory.GetDirectories(dirpath).Length > 0)
{
//Delete all files in directory
while (Directory.GetFiles(Directory.GetDirectories(dirpath)[0]).Length > 0)
{
File.Delete(Directory.GetFiles(dirpath)[0]);
}
Directory.Delete(Directory.GetDirectories(dirpath)[0]);
}
PHP Adding 15 minutes to Time value
To expand on previous answers, a function to do this could work like this (changing the time and interval formats however you like them according to this for function.date, and this for DateInterval):
(I've also written an alternate form of the below function here.)
// Return adjusted time.
function addMinutesToTime( $time, $plusMinutes ) {
$time = DateTime::createFromFormat( 'g:i:s', $time );
$time->add( new DateInterval( 'PT' . ( (integer) $plusMinutes ) . 'M' ) );
$newTime = $time->format( 'g:i:s' );
return $newTime;
}
$adjustedTime = addMinutesToTime( '9:15:00', 15 );
echo '<h1>Adjusted Time: ' . $adjustedTime . '</h1>' . PHP_EOL . PHP_EOL;
How to empty a list in C#?
If by "list" you mean a List<T>, then the Clear method is what you want:
List<string> list = ...;
...
list.Clear();
You should get into the habit of searching the MSDN documentation on these things.
Here's how to quickly search for documentation on various bits of that type:
- List Class - provides the
List<T>class itself (this is where you should've started) - List.Clear Method - provides documentation on the method Clear
- List.Count Property - provides documentation on the property Count
All of these Google queries lists a bundle of links, but typically you want the first one that google gives you in each case.
How do you clear the focus in javascript?
document.activeElement.blur();
Works wrong on IE9 - it blurs the whole browser window if active element is document body. Better to check for this case:
if (document.activeElement != document.body) document.activeElement.blur();
Print Html template in Angular 2 (ng-print in Angular 2)
Windows applications usually come with build in print capability, but for a web application, I would choose to simply generate a PDF file.
The simplest way that I found is to generate a PDf file using PDFMake (www.pdfmake.org). You can then offer the user the choice to open or download the generated PDF file.
How to read .pem file to get private and public key
To get the public key you can simply do:
public static PublicKey getPublicKeyFromCertFile(final String certfile){
return new X509CertImpl(new FileInputStream(new File(certfile))).getPublicKey();
To get the private key is trickier, you can:
public static PrivateKey getPrivateKeyFromKeyFile(final String keyfile){
try {
Process p;
p = Runtime.getRuntime().exec("openssl pkcs8 -nocrypt -topk8 -inform PEM " +
"-in " + keyfile + " -outform DER -out " + keyfile + ".der");
p.waitFor();
System.out.println("Command executed" + (p.exitValue() == 0 ? " successfully" : " with error" ));
} catch ( IOException | InterruptedException e) {
e.printStackTrace();
System.exit(1);
}
PrivateKey myPrivKey = null;
try {
byte[] keyArray = Files.readAllBytes(Paths.get(keyfile + ".der"));
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyArray);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
myPrivKey = keyFactory.generatePrivate(keySpec);
} catch (IOException | NoSuchAlgorithmException | InvalidKeySpecException e){
e.printStackTrace();
System.exit(1);
}
return myPrivKey;
}
XAMPP keeps showing Dashboard/Welcome Page instead of the Configuration Page
I had the same problem. I uninstalled the 6.8.14 and installed back older version 5.6.8, and it worked.
Can I make a <button> not submit a form?
<form class="form-horizontal" method="post">
<div class="control-group">
<input type="text" name="subject_code" id="inputEmail" placeholder="Subject Code">
</div>
<div class="control-group">
<input type="text" class="span8" name="title" id="inputPassword" placeholder="Subject Title" required>
</div>
<div class="control-group">
<input type="text" class="span1" name="unit" id="inputPassword" required>
</div>
<div class="control-group">
<label class="control-label" for="inputPassword">Semester</label>
<div class="controls">
<select name="semester">
<option></option>
<option>1st</option>
<option>2nd</option>
</select>
</div>
</div>
<div class="control-group">
<label class="control-label" for="inputPassword">Deskripsi</label>
<div class="controls">
<textarea name="description" id="ckeditor_full"></textarea>
<script>CKEDITOR.replace('ckeditor_full');</script>
</div>
</div>
<div class="control-group">
<div class="controls">
<button name="save" type="submit" class="btn btn-info"><i class="icon-save"></i> Simpan</button>
</div>
</div>
</form>
<?php
if (isset($_POST['save'])){
$subject_code = $_POST['subject_code'];
$title = $_POST['title'];
$unit = $_POST['unit'];
$description = $_POST['description'];
$semester = $_POST['semester'];
$query = mysql_query("select * from subject where subject_code = '$subject_code' ")or die(mysql_error());
$count = mysql_num_rows($query);
if ($count > 0){ ?>
<script>
alert('Data Sudah Ada');
</script>
<?php
}else{
mysql_query("insert into subject (subject_code,subject_title,description,unit,semester) values('$subject_code','$title','$description','$unit','$semester')")or die(mysql_error());
mysql_query("insert into activity_log (date,username,action) values(NOW(),'$user_username','Add Subject $subject_code')")or die(mysql_error());
?>
<script>
window.location = "subjects.php";
</script>
<?php
}
}
?>
Dockerfile if else condition with external arguments
Just use the "test" binary directly to do this. You also should use the noop command ":" if you don't want to specify an "else" condition, so docker does not stop with a non zero return value error.
RUN test -z "$YOURVAR" || echo "var is set" && echo "var is not set"
RUN test -z "$YOURVAR" && echo "var is not set" || :
RUN test -z "$YOURVAR" || echo "var is set" && :
How can I print out all possible letter combinations a given phone number can represent?
I am rather a newbie so please correct me wherever I am wrong.
First thing is looking into space & time complexity. Which is really bad since it's factorial so for factorial(7) = 5040 any recursive algorithm would do. But for factorial(12) ~= 4 * 10^8 which can cause stack overflow in recursive solution.
So I would not attempt a recursive algorithm. Looping solution is very straight forward using "Next Permutation".
So I would create and array {0, 1, 2, 3, 4, 5} and generate all permutation and while printing replace them with respective characters eg. 0=A, 5=F
Next Perm algorithm works as follows. eg Given 1,3,5,4 next permutation is 1,4,3,5
Steps for finding next perm.
From right to left, find first decreasing number. eg 3
From left to right, find lowest number bigger than 3 eg. 4
Swap these numbers as reverse the subset. 1,4,5,3 reverse subset 1,4,3,5
Using Next permutation ( or rotation) you generate specific subset of permutations, say you want to show 1000 permutations starting from a particular phone number. This can save you from having all numbers in memory. If I store numbers as 4 byte integers, 10^9 bytes = 1 GB !.
How to use protractor to check if an element is visible?
If there are multiple elements in DOM with same class name. But only one of element is visible.
element.all(by.css('.text-input-input')).filter(function(ele){
return ele.isDisplayed();
}).then(function(filteredElement){
filteredElement[0].click();
});
In this example filter takes a collection of elements and returns a single visible element using isDisplayed().
Android ImageView's onClickListener does not work
Please Try this one.
ImageView imageview1 = findViewById(R.id.imageView1);
imageview1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(YourActivity.this, "Here is your Text",Toast.LENGTH_SHORT).show();
}
});
Prevent wrapping of span or div
As mentioned you can use:
overflow: scroll;
If you only want the scroll bar to appear when necessary, you can use the "auto" option:
overflow: auto;
I don't think you should be using the "float" property with "overflow", but I'd have to try out your example first.
MVC 4 @Scripts "does not exist"
That has an obvious solution. I had the same problem later. Not related to Assembly References or ... .It'll occur In hierarchy calling of MVC Partial views, when you have complicated page structures. So calling/rendering each part separately on each page (maybe a master page or partial) will cause to not see required parts of page like the bellow code :
@RenderSection("Scripts", required: false)
That simply forces page to find and render related section and in case of failure shows you an error message like you.
So I suggest you to trace your pages (like program trace) from master to all of its partials to Detect Dependencies. Maybe it be a terrible work, but no other choices available here.
Not that according to my experience, some conditional situations in programming causes not to show you the right error causes the problem.
How to properly make a http web GET request
Simpliest way for my opinion
var web = new WebClient();
var url = $"{hostname}/LoadDataSync?systemID={systemId}";
var responseString = web.DownloadString(url);
OR
var bytes = web.DownloadData(url);
TypeError: 'str' object cannot be interpreted as an integer
A simplest fix would be:
x = input("Give starting number: ")
y = input("Give ending number: ")
x = int(x) # parse string into an integer
y = int(y) # parse string into an integer
for i in range(x,y):
print(i)
input returns you a string (raw_input in Python 2). int tries to parse it into an integer. This code will throw an exception if the string doesn't contain a valid integer string, so you'd probably want to refine it a bit using try/except statements.
How to order a data frame by one descending and one ascending column?
I use rank:
rum <- read.table(textConnection("P1 P2 P3 T1 T2 T3 I1 I2
2 3 5 52 43 61 6 b
6 4 3 72 NA 59 1 a
1 5 6 55 48 60 6 f
2 4 4 65 64 58 2 b
1 5 6 55 48 60 6 c"), header = TRUE)
> rum[order(rum$I1, -rank(rum$I2), decreasing = TRUE), ]
P1 P2 P3 T1 T2 T3 I1 I2
1 2 3 5 52 43 61 6 b
5 1 5 6 55 48 60 6 c
3 1 5 6 55 48 60 6 f
4 2 4 4 65 64 58 2 b
2 6 4 3 72 NA 59 1 a
How do I install Eclipse with C++ in Ubuntu 12.10 (Quantal Quetzal)?
I was in the same boat. Installed Eclipse, realized need CDT.
sudo apt-get install eclipse eclipse-cdt g++
This just adds the CDT package on top of existing installation - no un-installation etc. required.
How do I select a MySQL database through CLI?
While invoking the mysql CLI, you can specify the database name through the -D option. From mysql --help:
-D, --database=name Database to use.
I use this command:
mysql -h <db_host> -u <user> -D <db_name> -p
iOS Remote Debugging
There is an open bug on Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=584905
Unfortunately they depend on Apple to open up an API in WKView for this to happen, after which maybe debugging will be available from Safari.
Get the string within brackets in Python
You could use str.split to do this.
s = "<alpha.Customer[cus_Y4o9qMEZAugtnW] active_card=<alpha.AlphaObject[card]\
...>, created=1324336085, description='Customer for My Test App',\
livemode=False>"
val = s.split('[', 1)[1].split(']')[0]
Then we have:
>>> val
'cus_Y4o9qMEZAugtnW'
store return json value in input hidden field
If you use the JSON Serializer, you can simply store your object in string format as such
myHiddenText.value = JSON.stringify( myObject );
You can then get the value back with
myObject = JSON.parse( myHiddenText.value );
However, if you're not going to pass this value across page submits, it might be easier for you, and you'll save yourself a lot of serialization, if you just tuck it away as a global javascript variable.
How can I move all the files from one folder to another using the command line?
use move
then move <file or folder> <destination directory>
Get div's offsetTop positions in React
Eugene's answer uses the correct function to get the data, but for posterity I'd like to spell out exactly how to use it in React v0.14+ (according to this answer):
import ReactDOM from 'react-dom';
//...
componentDidMount() {
var rect = ReactDOM.findDOMNode(this)
.getBoundingClientRect()
}
Is working for me perfectly, and I'm using the data to scroll to the top of the new component that just mounted.
How to change onClick handler dynamically?
OMG... It's not only a problem of "jQuery Library" and "getElementById".
Sure, jQuery helps us to put cross-browser problems aside, but using the traditional way without libraries can still work well, if you really understand JavaScript ENOUGH!!!
Both @Már Örlygsson and @Darryl Hein gave you good ALTARNATIVES(I'd say, they're just altarnatives, not anwsers), where the former used the traditional way, and the latter jQuery way. But do you really know the answer to your problem? What is wrong with your code?
First, .click is a jQuery way. If you want to use traditional way, use .onclick instead. Or I recommend you concentrating on learning to use jQuery only, in case of confusing. jQuery is a good tool to use without knowing DOM enough.
The second problem, also the critical one, new function(){} is a very bad syntax, or say it is a wrong syntax.
No matter whether you want to go with jQuery or without it, you need to clarify it.
There are 3 basic ways declaring function:
function name () {code}
... = function() {code} // known as anonymous function or function literal
... = new Function("code") // Function Object
Note that javascript is case-sensitive, so new function() is not a standard syntax of javascript. Browsers may misunderstand the meaning.
Thus your code can be modified using the second way as
= function(){alert();}
Or using the third way as
= new Function("alert();");
Elaborating on it, the second way works almost the same as the third way, and the second way is very common, while the third is rare. Both of your best answers use the second way.
However, the third way can do something that the second can't do, because of "runtime" and "compile time". I just hope you know new Function() can be useful sometimes. One day you meet problems using function(){}, don't forget new Function().
To understand more, you are recommended read << JavaScript: The Definitive Guide, 6th Edition >>, O'Reilly.
Deleting all records in a database table
More recent answer in the case you want to delete every entries in every tables:
def reset
Rails.application.eager_load!
ActiveRecord::Base.descendants.each { |c| c.delete_all unless c == ActiveRecord::SchemaMigration }
end
More information about the eager_load here.
After calling it, we can access to all of the descendants of ActiveRecord::Base and we can apply a delete_all on all the models.
Note that we make sure not to clear the SchemaMigration table.
Can I rollback a transaction I've already committed? (data loss)
No, you can't undo, rollback or reverse a commit.
STOP THE DATABASE!
(Note: if you deleted the data directory off the filesystem, do NOT stop the database. The following advice applies to an accidental commit of a DELETE or similar, not an rm -rf /data/directory scenario).
If this data was important, STOP YOUR DATABASE NOW and do not restart it. Use pg_ctl stop -m immediate so that no checkpoint is run on shutdown.
You cannot roll back a transaction once it has commited. You will need to restore the data from backups, or use point-in-time recovery, which must have been set up before the accident happened.
If you didn't have any PITR / WAL archiving set up and don't have backups, you're in real trouble.
Urgent mitigation
Once your database is stopped, you should make a file system level copy of the whole data directory - the folder that contains base, pg_clog, etc. Copy all of it to a new location. Do not do anything to the copy in the new location, it is your only hope of recovering your data if you do not have backups. Make another copy on some removable storage if you can, and then unplug that storage from the computer. Remember, you need absolutely every part of the data directory, including pg_xlog etc. No part is unimportant.
Exactly how to make the copy depends on which operating system you're running. Where the data dir is depends on which OS you're running and how you installed PostgreSQL.
Ways some data could've survived
If you stop your DB quickly enough you might have a hope of recovering some data from the tables. That's because PostgreSQL uses multi-version concurrency control (MVCC) to manage concurrent access to its storage. Sometimes it will write new versions of the rows you update to the table, leaving the old ones in place but marked as "deleted". After a while autovaccum comes along and marks the rows as free space, so they can be overwritten by a later INSERT or UPDATE. Thus, the old versions of the UPDATEd rows might still be lying around, present but inaccessible.
Additionally, Pg writes in two phases. First data is written to the write-ahead log (WAL). Only once it's been written to the WAL and hit disk, it's then copied to the "heap" (the main tables), possibly overwriting old data that was there. The WAL content is copied to the main heap by the bgwriter and by periodic checkpoints. By default checkpoints happen every 5 minutes. If you manage to stop the database before a checkpoint has happened and stopped it by hard-killing it, pulling the plug on the machine, or using pg_ctl in immediate mode you might've captured the data from before the checkpoint happened, so your old data is more likely to still be in the heap.
Now that you have made a complete file-system-level copy of the data dir you can start your database back up if you really need to; the data will still be gone, but you've done what you can to give yourself some hope of maybe recovering it. Given the choice I'd probably keep the DB shut down just to be safe.
Recovery
You may now need to hire an expert in PostgreSQL's innards to assist you in a data recovery attempt. Be prepared to pay a professional for their time, possibly quite a bit of time.
I posted about this on the Pg mailing list, and ?????? ?????? linked to depesz's post on pg_dirtyread, which looks like just what you want, though it doesn't recover TOASTed data so it's of limited utility. Give it a try, if you're lucky it might work.
See: pg_dirtyread on GitHub.
I've removed what I'd written in this section as it's obsoleted by that tool.
See also PostgreSQL row storage fundamentals
Prevention
See my blog entry Preventing PostgreSQL database corruption.
On a semi-related side-note, if you were using two phase commit you could ROLLBACK PREPARED for a transction that was prepared for commit but not fully commited. That's about the closest you get to rolling back an already-committed transaction, and does not apply to your situation.
How can getContentResolver() be called in Android?
getContentResolver() is method of class android.content.Context, so to call it you definitely need an instance
of Context ( Activity or Service for example).
Run a shell script with an html button
PHP is likely the easiest.
Just make a file script.php that contains <?php shell_exec("yourscript.sh"); ?> and send anybody who clicks the button to that destination. You can return the user to the original page with header:
<?php
shell_exec("yourscript.sh");
header('Location: http://www.website.com/page?success=true');
?>
Replace all particular values in a data frame
If you want to replace multiple values in a data frame, looping through all columns might help.
Say you want to replace "" and 100:
na_codes <- c(100, "")
for (i in seq_along(df)) {
df[[i]][df[[i]] %in% na_codes] <- NA
}
how to query for a list<String> in jdbctemplate
Use following code
List data = getJdbcTemplate().queryForList(query,String.class)
How to extract HTTP response body from a Python requests call?
import requests
site_request = requests.get("https://abhiunix.in")
site_response = str(site_request.content)
print(site_response)
You can do it either way.
Docker: How to delete all local Docker images
To delete all images :
docker rmi $(docker images -a -q)
where -a is all, and -q is return only image ids
To remove unused images, and containers :
docker system prune
beware as if you are using docker swarm, and your local machine is joining remote swarm (as manager/worker), your local will be the deployed repo. executing this thus removes the deployed images.
PHP save image file
Note: you should use the accepted answer if possible. It's better than mine.
It's quite easy with the GD library.
It's built in usually, you probably have it (use phpinfo() to check)
$image = imagecreatefromjpeg("http://images.websnapr.com/?size=size&key=Y64Q44QLt12u&url=http://google.com");
imagejpeg($image, "folder/file.jpg");
The above answer is better (faster) for most situations, but with GD you can also modify it in some form (cropping for example).
$image = imagecreatefromjpeg("http://images.websnapr.com/?size=size&key=Y64Q44QLt12u&url=http://google.com");
imagecopy($image, $image, 0, 140, 0, 0, imagesx($image), imagesy($image));
imagejpeg($image, "folder/file.jpg");
This only works if allow_url_fopen is true (it is by default)
Make element fixed on scroll
You can go to LESS CSS website http://lesscss.org/
Their dockable menu is light and performs well. The only caveat is that the effect takes place after the scroll is complete. Just do a view source to see the js.
jQuery see if any or no checkboxes are selected
JQuery .is will test all specified elements and return true if at least one of them matches selector:
if ($(":checkbox[name='choices']", form).is(":checked"))
{
// one or more checked
}
else
{
// nothing checked
}
Connect to SQL Server database from Node.js
//start the program
var express = require('express');
var app = express();
app.get('/', function (req, res) {
var sql = require("mssql");
// config for your database
var config = {
user: 'datapullman',
password: 'system',
server: 'localhost',
database: 'chat6'
};
// connect to your database
sql.connect(config, function (err) {
if (err) console.log(err);
// create Request object
var request = new sql.Request();
// query to the database and get the records
request.query("select * From emp", function (err, recordset) {
if (err) console.log(err)
// send records as a response
res.send(recordset);
});
});
});
var server = app.listen(5000, function () {
console.log('Server is running..');
});
//create a table as emp in a database (i have created as chat6)
// programs ends here
//save it as app.js and run as node app.js //open in you browser as localhost:5000
How can I implement prepend and append with regular JavaScript?
Here's a snippet to get you going:
theParent = document.getElementById("theParent");
theKid = document.createElement("div");
theKid.innerHTML = 'Are we there yet?';
// append theKid to the end of theParent
theParent.appendChild(theKid);
// prepend theKid to the beginning of theParent
theParent.insertBefore(theKid, theParent.firstChild);
theParent.firstChild will give us a reference to the first element within theParent and put theKid before it.
How to pass Multiple Parameters from ajax call to MVC Controller
I did that with helping from this question
jquery get querystring from URL
so let see how we will use this function
// Read a page's GET URL variables and return them as an associative array.
function getUrlVars()
{
var vars = [], hash;
var hashes = window.location.href.slice(window.location.href.indexOf('?') + 1).split('&');
for(var i = 0; i < hashes.length; i++)
{
hash = hashes[i].split('=');
vars.push(hash[0]);
vars[hash[0]] = hash[1];
}
return vars;
}
and now just use it in Ajax call
"ajax": {
url: '/Departments/GetAllDepartments/',
type: 'GET',
dataType: 'json',
data: getUrlVars()// here is the tricky part
},
thats all, but if you want know how to use this function or not send all the query string parameters back to actual answer
How to set a text box for inputing password in winforms?
Just set the TextBox.PasswordChar property to '*'.
fatal: Not a valid object name: 'master'
First off, when you create a "bare repository", you're not going to be doing any work with it (it doesn't contain a working copy, so the git branch command is not useful).
Now, the reason you wouldn't have a master branch even after doing a git init is that there are no commits: when you create your first commit, you will then have a master branch.
Split string on whitespace in Python
Another method through re module. It does the reverse operation of matching all the words instead of spitting the whole sentence by space.
>>> import re
>>> s = "many fancy word \nhello \thi"
>>> re.findall(r'\S+', s)
['many', 'fancy', 'word', 'hello', 'hi']
Above regex would match one or more non-space characters.
jquery - How to determine if a div changes its height or any css attribute?
Another simple example.
For this sample we can use 100x100 DIV-box:
<div id="box" style="width: 100px; height: 100px; border: solid 1px red;">
// Red box contents here...
</div>
And small jQuery trick:
<script type="text/javascript">
jQuery("#box").bind("resize", function() {
alert("Box was resized from 100x100 to 200x200");
});
jQuery("#box").width(200).height(200).trigger("resize");
</script>
Steps:
- We created DIV block element for resizing operatios
- Add simple JavaScript code with:
- jQuery bind
- jQuery resizer with trigger action "resize" - trigger is most important thing in my example
- After resize you can check the browser alert information
That's all. ;-)
What does "opt" mean (as in the "opt" directory)? Is it an abbreviation?
In the old days, "/opt" was used by UNIX vendors like AT&T, Sun, DEC and 3rd-party vendors to hold "Option" packages; i.e. packages that you might have paid extra money for. I don't recall seeing "/opt" on Berkeley BSD UNIX. They used "/usr/local" for stuff that you installed yourself.
But of course, the true "meaning" of the different directories has always been somewhat vague. That is arguably a good thing, because if these directories had precise (and rigidly enforced) meanings you'd end up with a proliferation of different directory names.
According to the Filesystem Hierarchy Standard, /opt is for "the installation of add-on application software packages". /usr/local is "for use by the system administrator when installing software locally".
Where can I find a list of escape characters required for my JSON ajax return type?
Take a look at http://json.org/. It claims a bit different list of escaped characters than Chris proposed.
\"
\\
\/
\b
\f
\n
\r
\t
\u four-hex-digits
add title attribute from css
It is possible to imitate this with HTML & CSS
If you really really want dynamically applied tooltips to work, this (not so performance and architecture friendly) solution can allow you to use browser rendered tooltips without resorting to JS. I can imagine situations where this would be better than JS.
If you have a fixed subset of title attribute values, then you can generate additional elements server-side and let the browser read title from another element positioned above the original one using CSS.
Example:
div{_x000D_
position: relative;_x000D_
}_x000D_
div > span{_x000D_
display: none;_x000D_
}_x000D_
_x000D_
.pick-tooltip-1 > .tooltip-1, .pick-tooltip-2 > .tooltip-2{_x000D_
display: block;_x000D_
position: absolute;_x000D_
width: 100%;_x000D_
height: 100%;_x000D_
top: 0;_x000D_
left: 0;_x000D_
}<div class="pick-tooltip-1">_x000D_
Hover to see first tooltip_x000D_
<span class="tooltip-1" title="Tooltip 1"></span>_x000D_
<span class="tooltip-2" title="Tooltip 2"></span>_x000D_
</div>_x000D_
_x000D_
<div class="pick-tooltip-2">_x000D_
Hover to see second tooltip_x000D_
<span class="tooltip-1" title="Tooltip 1"></span>_x000D_
<span class="tooltip-2" title="Tooltip 2"></span>_x000D_
</div>Note: It's not recommended for large scale applications because of unnecessary HTML, possible content repetitions and the fact that your extra elements for tooltip would steal mouse events (text selection, etc)
How to import a module given the full path?
If we have scripts in the same project but in different directory means, we can solve this problem by the following method.
In this situation utils.py is in src/main/util/
import sys
sys.path.append('./')
import src.main.util.utils
#or
from src.main.util.utils import json_converter # json_converter is example method