How to return a custom object from a Spring Data JPA GROUP BY query
define a custom pojo class say sureveyQueryAnalytics and store the query returned value in your custom pojo class
@Query(value = "select new com.xxx.xxx.class.SureveyQueryAnalytics(s.answer, count(sv)) from Survey s group by s.answer")
List<SureveyQueryAnalytics> calculateSurveyCount();
How do I create a self-signed certificate for code signing on Windows?
It's fairly easy using the New-SelfSignedCertificate command in Powershell.
Open powershell and run these 3 commands.
1) Create certificate:
$cert = New-SelfSignedCertificate -DnsName www.yourwebsite.com
-Type CodeSigning -CertStoreLocation Cert:\CurrentUser\My
2) set the password for it:
$CertPassword = ConvertTo-SecureString
-String "my_passowrd" -Force –AsPlainText
3) Export it:
Export-PfxCertificate -Cert "cert:\CurrentUser\My\$($cert.Thumbprint)"
-FilePath "d:\selfsigncert.pfx" -Password $CertPassword
Your certificate selfsigncert.pfx will be located @ D:/
Optional step: You would also require to add certificate password to system environment variables. do so by entering below in cmd: setx CSC_KEY_PASSWORD "my_password"
how do I use an enum value on a switch statement in C++
- Note: I do know that this doesn't answer this specific question. But it is a question that people come to via a search engine. So i'm posting this here believing it will help those users.
You should keep in mind that if you are accessing class-wide enum from another function even if it is a friend, you need to provide values with a class name:
class PlayingCard
{
private:
enum Suit { CLUBS, DIAMONDS, HEARTS, SPADES };
int rank;
Suit suit;
friend std::ostream& operator<< (std::ostream& os, const PlayingCard &pc);
};
std::ostream& operator<< (std::ostream& os, const PlayingCard &pc)
{
// output the rank ...
switch(pc.suit)
{
case PlayingCard::HEARTS:
os << 'h';
break;
case PlayingCard::DIAMONDS:
os << 'd';
break;
case PlayingCard::CLUBS:
os << 'c';
break;
case PlayingCard::SPADES:
os << 's';
break;
}
return os;
}
Note how it is PlayingCard::HEARTS and not just HEARTS.
How to add a class to a given element?
When the work I'm doing doesn't warrant using a library, I use these two functions:
function addClass( classname, element ) {
var cn = element.className;
//test for existance
if( cn.indexOf( classname ) != -1 ) {
return;
}
//add a space if the element already has class
if( cn != '' ) {
classname = ' '+classname;
}
element.className = cn+classname;
}
function removeClass( classname, element ) {
var cn = element.className;
var rxp = new RegExp( "\\s?\\b"+classname+"\\b", "g" );
cn = cn.replace( rxp, '' );
element.className = cn;
}
Does the target directory for a git clone have to match the repo name?
Yes, it is possible:
git clone https://github.com/pitosalas/st3_packages Packages
You can specify the local root directory when using git clone.
<directory>
The name of a new directory to clone into.
The "humanish" part of the source repository is used if no directory is explicitly given (repo for /path/to/repo.git and foo for host.xz:foo/.git).
Cloning into an existing directory is only allowed if the directory is empty.
As Chris comments, you can then rename that top directory.
Git only cares about the .git within said top folder, which you can get with various commands:
git rev-parse --show-toplevel git rev-parse --git-dir
Listing all permutations of a string/integer
Here's a high level example I wrote which illustrates the human language explanation Peter gave:
public List<string> FindPermutations(string input)
{
if (input.Length == 1)
return new List<string> { input };
var perms = new List<string>();
foreach (var c in input)
{
var others = input.Remove(input.IndexOf(c), 1);
perms.AddRange(FindPermutations(others).Select(perm => c + perm));
}
return perms;
}
What is the regex pattern for datetime (2008-09-01 12:35:45 )?
regarding to Imran answer from Sep 1th 2008 at 12:33
there is a missing : in the pattern
the correct patterns are
preg_match('/\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}/', '2008-09-01 12:35:45', $m1);
print_r( $m1 );
preg_match('/\d{4}-\d{2}-\d{2} \d{1,2}:\d{2}:\d{2}/', '2008-09-01 12:35:45', $m2);
print_r( $m2 );
preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/', '2008-09-01 12:35:45', $m3);
print_r( $m3 );
this returns
Array ( [0] => 2008-09-01 12:35:45 )
Array ( [0] => 2008-09-01 12:35:45 )
Array ( [0] => 2008-09-01 12:35:45 )
Disable copy constructor
If you don't mind multiple inheritance (it is not that bad, after all), you may write simple class with private copy constructor and assignment operator and additionally subclass it:
class NonAssignable {
private:
NonAssignable(NonAssignable const&);
NonAssignable& operator=(NonAssignable const&);
public:
NonAssignable() {}
};
class SymbolIndexer: public Indexer, public NonAssignable {
};
For GCC this gives the following error message:
test.h: In copy constructor ‘SymbolIndexer::SymbolIndexer(const SymbolIndexer&)’:
test.h: error: ‘NonAssignable::NonAssignable(const NonAssignable&)’ is private
I'm not very sure for this to work in every compiler, though. There is a related question, but with no answer yet.
UPD:
In C++11 you may also write NonAssignable class as follows:
class NonAssignable {
public:
NonAssignable(NonAssignable const&) = delete;
NonAssignable& operator=(NonAssignable const&) = delete;
NonAssignable() {}
};
The delete keyword prevents members from being default-constructed, so they cannot be used further in a derived class's default-constructed members. Trying to assign gives the following error in GCC:
test.cpp: error: use of deleted function
‘SymbolIndexer& SymbolIndexer::operator=(const SymbolIndexer&)’
test.cpp: note: ‘SymbolIndexer& SymbolIndexer::operator=(const SymbolIndexer&)’
is implicitly deleted because the default definition would
be ill-formed:
UPD:
Boost already has a class just for the same purpose, I guess it's even implemented in similar way. The class is called boost::noncopyable and is meant to be used as in the following:
#include <boost/core/noncopyable.hpp>
class SymbolIndexer: public Indexer, private boost::noncopyable {
};
I'd recommend sticking to the Boost's solution if your project policy allows it. See also another boost::noncopyable-related question for more information.
MySQL Fire Trigger for both Insert and Update
In response to @Zxaos request, since we can not have AND/OR operators for MySQL triggers, starting with your code, below is a complete example to achieve the same.
1. Define the INSERT trigger:
DELIMITER //
DROP TRIGGER IF EXISTS my_insert_trigger//
CREATE DEFINER=root@localhost TRIGGER my_insert_trigger
AFTER INSERT ON `table`
FOR EACH ROW
BEGIN
-- Call the common procedure ran if there is an INSERT or UPDATE on `table`
-- NEW.id is an example parameter passed to the procedure but is not required
-- if you do not need to pass anything to your procedure.
CALL procedure_to_run_processes_due_to_changes_on_table(NEW.id);
END//
DELIMITER ;
2. Define the UPDATE trigger
DELIMITER //
DROP TRIGGER IF EXISTS my_update_trigger//
CREATE DEFINER=root@localhost TRIGGER my_update_trigger
AFTER UPDATE ON `table`
FOR EACH ROW
BEGIN
-- Call the common procedure ran if there is an INSERT or UPDATE on `table`
CALL procedure_to_run_processes_due_to_changes_on_table(NEW.id);
END//
DELIMITER ;
3. Define the common PROCEDURE used by both these triggers:
DELIMITER //
DROP PROCEDURE IF EXISTS procedure_to_run_processes_due_to_changes_on_table//
CREATE DEFINER=root@localhost PROCEDURE procedure_to_run_processes_due_to_changes_on_table(IN table_row_id VARCHAR(255))
READS SQL DATA
BEGIN
-- Write your MySQL code to perform when a `table` row is inserted or updated here
END//
DELIMITER ;
You note that I take care to restore the delimiter when I am done with my business defining the triggers and procedure.
Get resultset from oracle stored procedure
FYI as of Oracle 12c, you can do this:
CREATE OR REPLACE PROCEDURE testproc(n number)
AS
cur SYS_REFCURSOR;
BEGIN
OPEN cur FOR SELECT object_id,object_name from all_objects where rownum < n;
DBMS_SQL.RETURN_RESULT(cur);
END;
/
EXEC testproc(3);
OBJECT_ID OBJECT_NAME
---------- ------------
100 ORA$BASE
116 DUAL
This was supposed to get closer to other databases, and ease migrations.
But it's not perfect to me, for instance SQL developer won't display it nicely as a normal SELECT.
I prefer the output of pipeline functions, but they need more boilerplate to code.
more info:
https://oracle-base.com/articles/12c/implicit-statement-results-12cr1
How to define several include path in Makefile
You need to use -I with each directory. But you can still delimit the directories with whitespace if you use (GNU) make's foreach:
INC=$(DIR1) $(DIR2) ...
INC_PARAMS=$(foreach d, $(INC), -I$d)
How to specify an element after which to wrap in css flexbox?
There is part of the spec that sure sounds like this... right in the "flex layout algorithm" and "main sizing" sections:
Otherwise, starting from the first uncollected item, collect
consecutive items one by one until the first time that the next
collected item would not fit into the flex container’s inner main
size, or until a forced break is encountered. If the very first
uncollected item wouldn’t fit, collect just it into the line. A break
is forced wherever the CSS2.1 page-break-before/page-break-after
[CSS21] or the CSS3 break-before/break-after [CSS3-BREAK] properties
specify a fragmentation break.
From http://www.w3.org/TR/css-flexbox-1/#main-sizing
It sure sounds like (aside from the fact that page-breaks ought to be for printing), when laying out a potentially multi-line flex layout (which I take from another portion of the spec is one without flex-wrap: nowrap) a page-break-after: always or break-after: always should cause a break, or wrap to the next line.
.flex-container {
display: flex;
flex-flow: row wrap;
}
.child {
flex-grow: 1;
}
.child.break-here {
page-break-after: always;
break-after: always;
}
However, I have tried this and it hasn't been implemented that way in...
- Safari (up to 7)
- Chrome (up to 43 dev)
- Opera (up to 28 dev & 12.16)
- IE (up to 11)
It does work the way it sounds (to me, at least) like in:
Sample at http://codepen.io/morewry/pen/JoVmVj.
I didn't find any other requests in the bug tracker, so I reported it at https://code.google.com/p/chromium/issues/detail?id=473481.
But the topic took to the mailing list and, regardless of how it sounds, that's not what apparently they meant to imply, except I guess for pagination. So there's no way to wrap before or after a particular box in flex layout without nesting successive flex layouts inside flex children or fiddling with specific widths (e.g. flex-basis: 100%).
This is deeply annoying, of course, since working with the Firefox implementation confirms my suspicion that the functionality is incredibly useful. Aside from the improved vertical alignment, the lack obviates a good deal of the utility of flex layout in numerous scenarios. Having to add additional wrapping tags with nested flex layouts to control the point at which a row wraps increases the complexity of both the HTML and CSS and, sadly, frequently renders order useless. Similarly, forcing the width of an item to 100% reduces the "responsive" potential of the flex layout or requires a lot of highly specific queries or count selectors (e.g. the techniques that may accomplish the general result you need that are mentioned in the other answers).
At least floats had clear. Something may get added at some point or another for this, one hopes.
Execute a large SQL script (with GO commands)
I also faced the same problem, and I could not find any other way but splitting the single SQL operation in separate files, then executing all of them in sequence.
Obviously the problem is not with lists of DML commands, they can be executed without GO in between; different story with DDL (create, alter, drop...)
How to pass an array to a function in VBA?
Your function worked for me after changing its declaration to this ...
Function processArr(Arr As Variant) As String
You could also consider a ParamArray like this ...
Function processArr(ParamArray Arr() As Variant) As String
'Dim N As Variant
Dim N As Long
Dim finalStr As String
For N = LBound(Arr) To UBound(Arr)
finalStr = finalStr & Arr(N)
Next N
processArr = finalStr
End Function
And then call the function like this ...
processArr("foo", "bar")
How can I see function arguments in IPython Notebook Server 3?
In 1.0, the functionality was bound to ( and tab and shift-tab, in 2.0 tab was deprecated but still functional in some unambiguous cases completing or inspecting were competing in many cases. Recommendation was to always use shift-Tab. ( was also added as deprecated as confusing in Haskell-like syntax to also push people toward Shift-Tab as it works in more cases. in 3.0 the deprecated bindings have been remove in favor of the official, present for 18+ month now Shift-Tab.
So press Shift-Tab.
What does the "__block" keyword mean?
From the Block Language Spec:
In addition to the new Block type we also introduce a new storage qualifier, __block, for local variables. [testme: a __block declaration within a block literal] The __block storage qualifier is mutually exclusive to the existing local storage qualifiers auto, register, and static.[testme] Variables qualified by __block act as if they were in allocated storage and this storage is automatically recovered after last use of said variable. An implementation may choose an optimization where the storage is initially automatic and only "moved" to allocated (heap) storage upon a Block_copy of a referencing Block. Such variables may be mutated as normal variables are.
In the case where a __block variable is a Block one must assume that the __block variable resides in allocated storage and as such is assumed to reference a Block that is also in allocated storage (that it is the result of a Block_copy operation). Despite this there is no provision to do a Block_copy or a Block_release if an implementation provides initial automatic storage for Blocks. This is due to the inherent race condition of potentially several threads trying to update the shared variable and the need for synchronization around disposing of older values and copying new ones. Such synchronization is beyond the scope of this language specification.
For details on what a __block variable should compile to, see the Block Implementation Spec, section 2.3.
How do I solve this "Cannot read property 'appendChild' of null" error?
For all those facing a similar issue, I came across this same issue when i was trying to run a particular code snippet, shown below.
<html>
<head>
<script>
var div, container = document.getElementById("container")
for(var i=0;i<5;i++){
div = document.createElement("div");
div.onclick = function() {
alert("This is a box #"+i);
};
container.appendChild(div);
}
</script>
</head>
<body>
<div id="container"></div>
</body>
</html>
https://codepen.io/pcwanderer/pen/MMEREr
Looking at the error in the console for the above code.
Since the document.getElementById is returning a null and as null does not have a attribute named appendChild, therefore a error is thrown. To solve the issue see the code below.
<html>
<head>
<style>
#container{
height: 200px;
width: 700px;
background-color: red;
margin: 10px;
}
div{
height: 100px;
width: 100px;
background-color: purple;
margin: 20px;
display: inline-block;
}
</style>
</head>
<body>
<div id="container"></div>
<script>
var div, container = document.getElementById("container")
for(let i=0;i<5;i++){
div = document.createElement("div");
div.onclick = function() {
alert("This is a box #"+i);
};
container.appendChild(div);
}
</script>
</body>
</html>
https://codepen.io/pcwanderer/pen/pXWBQL
I hope this helps. :)
Showing data values on stacked bar chart in ggplot2
From ggplot 2.2.0 labels can easily be stacked by using position = position_stack(vjust = 0.5) in geom_text.
ggplot(Data, aes(x = Year, y = Frequency, fill = Category, label = Frequency)) +
geom_bar(stat = "identity") +
geom_text(size = 3, position = position_stack(vjust = 0.5))
Also note that "position_stack() and position_fill() now stack values in the reverse order of the grouping, which makes the default stack order match the legend."
Answer valid for older versions of ggplot:
Here is one approach, which calculates the midpoints of the bars.
library(ggplot2)
library(plyr)
# calculate midpoints of bars (simplified using comment by @DWin)
Data <- ddply(Data, .(Year),
transform, pos = cumsum(Frequency) - (0.5 * Frequency)
)
# library(dplyr) ## If using dplyr...
# Data <- group_by(Data,Year) %>%
# mutate(pos = cumsum(Frequency) - (0.5 * Frequency))
# plot bars and add text
p <- ggplot(Data, aes(x = Year, y = Frequency)) +
geom_bar(aes(fill = Category), stat="identity") +
geom_text(aes(label = Frequency, y = pos), size = 3)
accessing a variable from another class
I had the same problem. In order to modify variables from different classes, I made them extend the class they were to modify. I also made the super class's variables static so they can be changed by anything that inherits them. I also made them protected for more flexibility.
Source: Bad experiences. Good lessons.
How to loop through an array containing objects and access their properties
_x000D_
_x000D_
const jobs = [_x000D_
{_x000D_
name: "sipher",_x000D_
family: "sipherplus",_x000D_
job: "Devops"_x000D_
},_x000D_
{_x000D_
name: "john",_x000D_
family: "Doe",_x000D_
job: "Devops"_x000D_
},_x000D_
{_x000D_
name: "jim",_x000D_
family: "smith",_x000D_
job: "Devops"_x000D_
}_x000D_
];_x000D_
_x000D_
const txt = _x000D_
` <ul>_x000D_
${jobs.map(job => `<li>${job.name} ${job.family} -> ${job.job}</li>`).join('')}_x000D_
</ul>`_x000D_
;_x000D_
_x000D_
document.body.innerHTML = txt;
_x000D_
_x000D_
_x000D_
Be careful about the back Ticks (`)
node: command not found
The problem is that your PATH does not include the location of the node executable.
You can likely run node as "/usr/local/bin/node".
You can add that location to your path by running the following command to add a single line to your bashrc file:
echo 'export PATH=$PATH:/usr/local/bin' >> $HOME/.bashrc
How to fix curl: (60) SSL certificate: Invalid certificate chain
Another cause of this can be duplicate keys in your KeyChain. I've seen this problem on two macs where there were duplicate "DigiCert High Assurance EV Root CA". One was in the login keychain, the other in the system one. Removing the certificate from the login keychain solved the problem.
This affected Safari browser as well as git on the command line.
addEventListener vs onclick
As far as I know, the DOM "load" event still does only work very limited. That means it'll only fire for the window object, images and <script> elements for instance. The same goes for the direct onload assignment. There is no technical difference between those two. Probably .onload = has a better cross-browser availabilty.
However, you cannot assign a load event to a <div> or <span> element or whatnot.
Why is the use of alloca() not considered good practice?
In my opinion, alloca(), where available, should be used only in a constrained manner. Very much like the use of "goto", quite a large number of otherwise reasonable people have strong aversion not just to the use of, but also the existence of, alloca().
For embedded use, where the stack size is known and limits can be imposed via convention and analysis on the size of the allocation, and where the compiler cannot be upgraded to support C99+, use of alloca() is fine, and I've been known to use it.
When available, VLAs may have some advantages over alloca(): The compiler can generate stack limit checks that will catch out-of-bounds access when array style access is used (I don't know if any compilers do this, but it can be done), and analysis of the code can determine whether the array access expressions are properly bounded. Note that, in some programming environments, such as automotive, medical equipment, and avionics, this analysis has to be done even for fixed size arrays, both automatic (on the stack) and static allocation (global or local).
On architectures that store both data and return addresses/frame pointers on the stack (from what I know, that's all of them), any stack allocated variable can be dangerous because the address of the variable can be taken, and unchecked input values might permit all sorts of mischief.
Portability is less of a concern in the embedded space, however it is a good argument against use of alloca() outside of carefully controlled circumstances.
Outside of the embedded space, I've used alloca() mostly inside logging and formatting functions for efficiency, and in a non-recursive lexical scanner, where temporary structures (allocated using alloca() are created during tokenization and classification, then a persistent object (allocated via malloc()) is populated before the function returns. The use of alloca() for the smaller temporary structures greatly reduces fragmentation when the persistent object is allocated.
Get local href value from anchor (a) tag
The below code gets the full path, where the anchor points:
document.getElementById("aaa").href; // http://example.com/sec/IF00.html
while the one below gets the value of the href attribute:
document.getElementById("aaa").getAttribute("href"); // sec/IF00.html
Reload a DIV without reloading the whole page
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.0/jquery.min.js" />
<div class="View"><?php include 'Small.php'; ?></div>
<script type="text/javascript">
$(document).ready(function() {
$('.View').load('Small.php');
var auto_refresh = setInterval(
function ()
{
$('.View').load('Small.php').fadeIn("slow");
}, 15000); // refresh every 15000 milliseconds
$.ajaxSetup({ cache: true });
});
</script>
OnChange event handler for radio button (INPUT type="radio") doesn't work as one value
If you want to avoid inline script, you can simply listen for a click event on the radio. This can be achieved with plain Javascript by listening to a click event on
for (var radioCounter = 0 ; radioCounter < document.getElementsByName('myRadios').length; radioCounter++) {
document.getElementsByName('myRadios')[radioCounter].onclick = function() {
//VALUE OF THE CLICKED RADIO ELEMENT
console.log('this : ',this.value);
}
}
Maven: The packaging for this project did not assign a file to the build artifact
I have same issue.
Error message for me is not complete. But in my case, I've added generation jar with sources. By placing this code in pom.xml:
<build>
<pluginManagement>
<plugins>
<plugin>
<artifactId>maven-source-plugin</artifactId>
<version>2.1.2</version>
<executions>
<execution>
<phase>deploy</phase>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
So in deploy phase I execute source:jar goal which produces jar with sources. And deploy ends with BUILD SUCCESS
What does the colon (:) operator do?
It is used in the new short hand for/loop
final List<String> list = new ArrayList<String>();
for (final String s : list)
{
System.out.println(s);
}
and the ternary operator
list.isEmpty() ? true : false;
JSLint is suddenly reporting: Use the function form of "use strict"
Include 'use strict'; as the first statement in a wrapping function, so it only affects that function. This prevents problems when concatenating scripts that aren't strict.
See Douglas Crockford's latest blog post Strict Mode Is Coming To Town.
Example from that post:
(function () {
'use strict';
// this function is strict...
}());
(function () {
// but this function is sloppy...
}());
Update:
In case you don't want to wrap in immediate function (e.g. it is a node module), then you can disable the warning.
For JSLint (per Zhami):
/*jslint node: true */
For JSHint:
/*jshint strict:false */
or (per Laith Shadeed)
/* jshint -W097 */
To disable any arbitrary warning from JSHint, check the map in JSHint source code (details in docs).
Update 2: JSHint supports node:boolean option. See .jshintrc at github.
/* jshint node: true */
Iterating through all nodes in XML file
This is what I quickly wrote for myself:
public static class XmlDocumentExtensions
{
public static void IterateThroughAllNodes(
this XmlDocument doc,
Action<XmlNode> elementVisitor)
{
if (doc != null && elementVisitor != null)
{
foreach (XmlNode node in doc.ChildNodes)
{
doIterateNode(node, elementVisitor);
}
}
}
private static void doIterateNode(
XmlNode node,
Action<XmlNode> elementVisitor)
{
elementVisitor(node);
foreach (XmlNode childNode in node.ChildNodes)
{
doIterateNode(childNode, elementVisitor);
}
}
}
To use it, I've used something like:
var doc = new XmlDocument();
doc.Load(somePath);
doc.IterateThroughAllNodes(
delegate(XmlNode node)
{
// ...Do something with the node...
});
Maybe it helps someone out there.
<hr> tag in Twitter Bootstrap not functioning correctly?
You may want one of these, so to correspond to the Bootstrap layout:
<div class="col-xs-12">
<hr >
</div>
<!-- or -->
<div class="col-xs-12">
<hr style="border-style: dashed; border-top-width: 2px;">
</div>
<!-- or -->
<div class="col-xs-12">
<hr class="col-xs-1" style="border-style: dashed; border-top-width: 2px;">
</div>
Without a DIV grid element included, layout may brake on different devices.
What does the term "canonical form" or "canonical representation" in Java mean?
Wikipedia points to the term Canonicalization.
A process for converting data that has more than one possible representation into a "standard" canonical representation. This can be done to compare different representations for equivalence, to count the number of distinct data structures, to improve the efficiency of various algorithms by eliminating repeated calculations, or to make it possible to impose a meaningful sorting order.
The Unicode example made the most sense to me:
Variable-length encodings in the Unicode standard, in particular UTF-8, have more than one possible encoding for most common characters. This makes string validation more complicated, since every possible encoding of each string character must be considered. A software implementation which does not consider all character encodings runs the risk of accepting strings considered invalid in the application design, which could cause bugs or allow attacks. The solution is to allow a single encoding for each character. Canonicalization is then the process of translating every string character to its single allowed encoding. An alternative is for software to determine whether a string is canonicalized, and then reject it if it is not. In this case, in a client/server context, the canonicalization would be the responsibility of the client.
In summary, a standard form of representation for data. From this form you can then convert to any representation you may need.
*.h or *.hpp for your class definitions
I use .hpp because I want the user to differentiate what headers are C++ headers, and what headers are C headers.
This can be important when your project is using both C and C++ modules: Like someone else explained before me, you should do it very carefully, and its starts by the "contract" you offer through the extension
.hpp : C++ Headers
(Or .hxx, or .hh, or whatever)
This header is for C++ only.
If you're in a C module, don't even try to include it. You won't like it, because no effort is done to make it C-friendly (too much would be lost, like function overloading, namespaces, etc. etc.).
.h : C/C++ compatible or pure C Headers
This header can be included by both a C source, and a C++ source, directly or indirectly.
It can included directly, being protected by the __cplusplus macro:
- Which mean that, from a C++ viewpoint, the C-compatible code will be defined as
extern "C".
- From a C viewpoint, all the C code will be plainly visible, but the C++ code will be hidden (because it won't compile in a C compiler).
For example:
#ifndef MY_HEADER_H
#define MY_HEADER_H
#ifdef __cplusplus
extern "C"
{
#endif
void myCFunction() ;
#ifdef __cplusplus
} // extern "C"
#endif
#endif // MY_HEADER_H
Or it could be included indirectly by the corresponding .hpp header enclosing it with the extern "C" declaration.
For example:
#ifndef MY_HEADER_HPP
#define MY_HEADER_HPP
extern "C"
{
#include "my_header.h"
}
#endif // MY_HEADER_HPP
and:
#ifndef MY_HEADER_H
#define MY_HEADER_H
void myCFunction() ;
#endif // MY_HEADER_H
Automatically get loop index in foreach loop in Perl
No, you must make your own counter. Yet another example:
my $index;
foreach (@x) {
print $index++;
}
when used for indexing
my $index;
foreach (@x) {
print $x[$index]+$y[$index];
$index++;
}
And of course you can use local $index; instead my $index; and so and so.
C# code to validate email address
public static bool IsEmail(string strEmail)
{
Regex rgxEmail = new Regex(@"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
@"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +
@".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$");
return rgxEmail.IsMatch(strEmail);
}
mat-form-field must contain a MatFormFieldControl
You need to import the MatInputModule into your app.module.ts file
import { MatInputModule} from '@angular/material';
import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { IonicModule } from '@ionic/angular';
import { CustomerPage } from './components/customer/customer';
import { CustomerDetailsPage } from "./components/customer-details/customer-details";
import { CustomerManagementPageRoutingModule } from './customer-management-routing.module';
import { MatAutocompleteModule } from '@angular/material/autocomplete'
import { ReactiveFormsModule } from '@angular/forms';
import { MatFormFieldModule } from '@angular/material/form-field';
import { MatInputModule} from '@angular/material';
@NgModule({
imports: [
CommonModule,
FormsModule,
IonicModule,
CustomerManagementPageRoutingModule,
MatAutocompleteModule,
MatInputModule,
ReactiveFormsModule,
MatFormFieldModule
],
Access 2013 - Cannot open a database created with a previous version of your application
As noted in another answer, the official word from Microsoft is to open an Access 97 file in Access 2003 and upgrade it to a newer file format. Unfortunately, from now on many people will have difficulty getting their hands on a legitimate copy of Access 2003 (or any other version prior to Access 2013, or whatever the latest version happens to be).
In that case, a possible workaround would be to
- install a 32-bit version of SQL Server Express Edition, and then
- have the SQL Server import utility use Jet* ODBC to import the tables into SQL Server.
I just tried that with a 32-bit version of SQL Server 2008 R2 Express Edition and it worked for me. Access 2013 adamantly refused to have anything to do with the Access 97 file, but SQL Server imported the tables without complaint.
At that point you could import the tables from SQL Server into an Access 2013 database. Or, if your goal was simply to get the data out of the Access 97 file then you could continue to work with it in SQL Server, or move it to some other platform, or whatever.
*Important: The import needs to be done using the older Jet ODBC driver ...
Microsoft Access Driver (*.mdb)
... which ships with Windows but is only available to 32-bit applications. The Access 2013 version of the newer Access Database Engine ("ACE") ODBC driver ...
Microsoft Access Driver (*.mdb, *.accdb)
also refuses to read Access 97 files (with the same error message cited in the question).
Generate 'n' unique random numbers within a range
If you just need sampling without replacement:
>>> import random
>>> random.sample(range(1, 100), 3)
[77, 52, 45]
random.sample takes a population and a sample size k and returns k random members of the population.
If you have to control for the case where k is larger than len(population), you need to be prepared to catch a ValueError:
>>> try:
... random.sample(range(1, 2), 3)
... except ValueError:
... print('Sample size exceeded population size.')
...
Sample size exceeded population size
How do I write out a text file in C# with a code page other than UTF-8?
You can have something like this
switch (EncodingFormat.Trim().ToLower())
{
case "utf-8":
File.WriteAllBytes(fileName, ASCIIEncoding.Convert(ASCIIEncoding.ASCII, new UTF8Encoding(false), convertToCSV(result, fileName)));
break;
case "utf-8+bom":
File.WriteAllBytes(fileName, ASCIIEncoding.Convert(ASCIIEncoding.ASCII, new UTF8Encoding(true), convertToCSV(result, fileName)));
break;
case "ISO-8859-1":
File.WriteAllBytes(fileName, ASCIIEncoding.Convert(ASCIIEncoding.ASCII, Encoding.GetEncoding("iso-8859-1"), convertToCSV(result, fileName)));
break;
case ..............
}
Where's the DateTime 'Z' format specifier?
Round tripping dates through strings has always been a pain...but the docs to indicate that the 'o' specifier is the one to use for round tripping which captures the UTC state. When parsed the result will usually have Kind == Utc if the original was UTC. I've found that the best thing to do is always normalize dates to either UTC or local prior to serializing then instruct the parser on which normalization you've chosen.
DateTime now = DateTime.Now;
DateTime utcNow = now.ToUniversalTime();
string nowStr = now.ToString( "o" );
string utcNowStr = utcNow.ToString( "o" );
now = DateTime.Parse( nowStr );
utcNow = DateTime.Parse( nowStr, null, DateTimeStyles.AdjustToUniversal );
Debug.Assert( now == utcNow );
Regex how to match an optional character
Use
[A-Z]?
to make the letter optional. {1} is redundant. (Of course you could also write [A-Z]{0,1} which would mean the same, but that's what the ? is there for.)
You could improve your regex to
^([0-9]{5})+\s+([A-Z]?)\s+([A-Z])([0-9]{3})([0-9]{3})([A-Z]{3})([A-Z]{3})\s+([A-Z])[0-9]{3}([0-9]{4})([0-9]{2})([0-9]{2})
And, since in most regex dialects, \d is the same as [0-9]:
^(\d{5})+\s+([A-Z]?)\s+([A-Z])(\d{3})(\d{3})([A-Z]{3})([A-Z]{3})\s+([A-Z])\d{3}(\d{4})(\d{2})(\d{2})
But: do you really need 11 separate capturing groups? And if so, why don't you capture the fourth-to-last group of digits?
Setting environment variable in react-native?
React native does not have the concept of global variables.
It enforces modular scope strictly, in order to promote component modularity and reusability.
Sometimes, though, you need components to be aware of their environment. In this case it's very simple to define an Environment module which components can then call to get environment variables, for example:
environment.js
var _Environments = {
production: {BASE_URL: '', API_KEY: ''},
staging: {BASE_URL: '', API_KEY: ''},
development: {BASE_URL: '', API_KEY: ''},
}
function getEnvironment() {
// Insert logic here to get the current platform (e.g. staging, production, etc)
var platform = getPlatform()
// ...now return the correct environment
return _Environments[platform]
}
var Environment = getEnvironment()
module.exports = Environment
my-component.js
var Environment = require('./environment.js')
...somewhere in your code...
var url = Environment.BASE_URL
This creates a singleton environment which can be accessed from anywhere inside the scope of your app. You have to explicitly require(...) the module from any components that use Environment variables, but that is a good thing.
Import Libraries in Eclipse?
For the Android library projects, I do it as in the attached screenshot:
Right click the project, select Properties->Android and in the library section click Add. From here you can select the available libraries.
If you are importing a jar file, then importing them as jar or external jar, as other posters posted would work. I prefer to copy/paste jar file in the libs folder (create one if it doesn't exist) and then import as jar.
Install windows service without InstallUtil.exe
This is a base service class (ServiceBase subclass) that can be subclassed to build a windows service that can be easily installed from the command line, without installutil.exe. This solution is derived from How to make a .NET Windows Service start right after the installation?, adding some code to get the service Type using the calling StackFrame
public abstract class InstallableServiceBase:ServiceBase
{
/// <summary>
/// returns Type of the calling service (subclass of InstallableServiceBase)
/// </summary>
/// <returns></returns>
protected static Type getMyType()
{
Type t = typeof(InstallableServiceBase);
MethodBase ret = MethodBase.GetCurrentMethod();
Type retType = null;
try
{
StackFrame[] frames = new StackTrace().GetFrames();
foreach (StackFrame x in frames)
{
ret = x.GetMethod();
Type t1 = ret.DeclaringType;
if (t1 != null && !t1.Equals(t) && !t1.IsSubclassOf(t))
{
break;
}
retType = t1;
}
}
catch
{
}
return retType;
}
/// <summary>
/// returns AssemblyInstaller for the calling service (subclass of InstallableServiceBase)
/// </summary>
/// <returns></returns>
protected static AssemblyInstaller GetInstaller()
{
Type t = getMyType();
AssemblyInstaller installer = new AssemblyInstaller(
t.Assembly, null);
installer.UseNewContext = true;
return installer;
}
private bool IsInstalled()
{
using (ServiceController controller =
new ServiceController(this.ServiceName))
{
try
{
ServiceControllerStatus status = controller.Status;
}
catch
{
return false;
}
return true;
}
}
private bool IsRunning()
{
using (ServiceController controller =
new ServiceController(this.ServiceName))
{
if (!this.IsInstalled()) return false;
return (controller.Status == ServiceControllerStatus.Running);
}
}
/// <summary>
/// protected method to be called by a public method within the real service
/// ie: in the real service
/// new internal void InstallService()
/// {
/// base.InstallService();
/// }
/// </summary>
protected void InstallService()
{
if (this.IsInstalled()) return;
try
{
using (AssemblyInstaller installer = GetInstaller())
{
IDictionary state = new Hashtable();
try
{
installer.Install(state);
installer.Commit(state);
}
catch
{
try
{
installer.Rollback(state);
}
catch { }
throw;
}
}
}
catch
{
throw;
}
}
/// <summary>
/// protected method to be called by a public method within the real service
/// ie: in the real service
/// new internal void UninstallService()
/// {
/// base.UninstallService();
/// }
/// </summary>
protected void UninstallService()
{
if (!this.IsInstalled()) return;
if (this.IsRunning()) {
this.StopService();
}
try
{
using (AssemblyInstaller installer = GetInstaller())
{
IDictionary state = new Hashtable();
try
{
installer.Uninstall(state);
}
catch
{
throw;
}
}
}
catch
{
throw;
}
}
private void StartService()
{
if (!this.IsInstalled()) return;
using (ServiceController controller =
new ServiceController(this.ServiceName))
{
try
{
if (controller.Status != ServiceControllerStatus.Running)
{
controller.Start();
controller.WaitForStatus(ServiceControllerStatus.Running,
TimeSpan.FromSeconds(10));
}
}
catch
{
throw;
}
}
}
private void StopService()
{
if (!this.IsInstalled()) return;
using (ServiceController controller =
new ServiceController(this.ServiceName))
{
try
{
if (controller.Status != ServiceControllerStatus.Stopped)
{
controller.Stop();
controller.WaitForStatus(ServiceControllerStatus.Stopped,
TimeSpan.FromSeconds(10));
}
}
catch
{
throw;
}
}
}
}
All you have to do is to implement two public/internal methods in your real service:
new internal void InstallService()
{
base.InstallService();
}
new internal void UninstallService()
{
base.UninstallService();
}
and then call them when you want to install the service:
static void Main(string[] args)
{
if (Environment.UserInteractive)
{
MyService s1 = new MyService();
if (args.Length == 1)
{
switch (args[0])
{
case "-install":
s1.InstallService();
break;
case "-uninstall":
s1.UninstallService();
break;
default:
throw new NotImplementedException();
}
}
}
else {
ServiceBase[] ServicesToRun;
ServicesToRun = new ServiceBase[]
{
new MyService()
};
ServiceBase.Run(MyService);
}
}
NodeJS: How to decode base64 encoded string back to binary?
As of Node.js v6.0.0 using the constructor method has been deprecated and the following method should instead be used to construct a new buffer from a base64 encoded string:
var b64string = /* whatever */;
var buf = Buffer.from(b64string, 'base64'); // Ta-da
For Node.js v5.11.1 and below
Construct a new Buffer and pass 'base64' as the second argument:
var b64string = /* whatever */;
var buf = new Buffer(b64string, 'base64'); // Ta-da
If you want to be clean, you can check whether from exists :
if (typeof Buffer.from === "function") {
// Node 5.10+
buf = Buffer.from(b64string, 'base64'); // Ta-da
} else {
// older Node versions, now deprecated
buf = new Buffer(b64string, 'base64'); // Ta-da
}
How to bind DataTable to Datagrid
using (SqlCeConnection con = new SqlCeConnection())
{
con.ConnectionString = connectionString;
con.Open();
SqlCeCommand com = new SqlCeCommand("SELECT S_no,Name,Father_Name")
SqlCeDataAdapter sda = new SqlCeDataAdapter(com);
System.Data.DataTable dt = new System.Data.DataTable();
sda.Fill(dt);
dataGrid1.ItemsSource = dt.DefaultView;
dataGrid1.AutoGenerateColumns = true;
dataGrid1.CanUserAddRows = false;
}
select2 onchange event only works once
As of version 4.0.0, events such as select2-selecting, no longer work. They are renamed as follows:
- select2-close is now select2:close
- select2-open is now select2:open
- select2-opening is now select2:opening
- select2-selecting is now select2:selecting
- select2-removed is now select2:removed
- select2-removing is now select2:unselecting
Ref: https://select2.org/programmatic-control/events
_x000D_
_x000D_
(function($){_x000D_
$('.select2').select2();_x000D_
_x000D_
$('.select2').on('select2:selecting', function(e) {_x000D_
console.log('Selecting: ' , e.params.args.data);_x000D_
});_x000D_
})(jQuery);
_x000D_
body{_x000D_
font-family: sans-serif;_x000D_
}_x000D_
_x000D_
.select2{_x000D_
width: 100%;_x000D_
}
_x000D_
<link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.min.css" rel="stylesheet">_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/js/select2.full.min.js"></script>_x000D_
_x000D_
<select class="select2" multiple="multiple">_x000D_
<option value="1">Option 1</option>_x000D_
<option value="2">Option 2</option>_x000D_
<option value="3">Option 3</option>_x000D_
<option value="4">Option 4</option>_x000D_
<option value="5">Option 5</option>_x000D_
<option value="6">Option 6</option>_x000D_
<option value="7">Option 7</option>_x000D_
</select>
_x000D_
_x000D_
_x000D_
Breaking out of nested loops
In this particular case, you can merge the loops with a modern python (3.0 and probably 2.6, too) by using itertools.product.
I for myself took this as a rule of thumb, if you nest too many loops (as in, more than 2), you are usually able to extract one of the loops into a different method or merge the loops into one, as in this case.
Getting all documents from one collection in Firestore
Two years late but I just began reading the Firestore documentation recently cover to cover for fun and found withConverter which I saw wasn't posted in any of the above answers. Thus:
If you want to include ids and also use withConverter (Firestore's version of ORMs, like ActiveRecord for Ruby on Rails, Entity Framework for .NET, etc), then this might be useful for you:
Somewhere in your project, you probably have your Event model properly defined. For example, something like:
Your model (in TypeScript):
./models/Event.js
export class Event {
constructor (
public id: string,
public title: string,
public datetime: Date
)
}
export const eventConverter = {
toFirestore: function (event: Event) {
return {
// id: event.id, // Note! Not in ".data()" of the model!
title: event.title,
datetime: event.datetime
}
},
fromFirestore: function (snapshot: any, options: any) {
const data = snapshot.data(options)
const id = snapshot.id
return new Event(id, data.title, data.datetime)
}
}
And then your client-side TypeScript code:
import { eventConverter } from './models/Event.js'
...
async function loadEvents () {
const qs = await firebase.firestore().collection('events')
.orderBy('datetime').limit(3) // Remember to limit return sizes!
.withConverter(eventConverter).get()
const events = qs.docs.map((doc: any) => doc.data())
...
}
Two interesting quirks of Firestore to notice (or at least, I thought were interesting):
Your event.id is actually stored "one-level-up" in snapshot.id and not snapshot.data().
If you're using TypeScript, the TS linter (or whatever it's called) sadly isn't smart enough to understand:
const events = qs.docs.map((doc: Event) => doc.data())
even though right above it you explicitly stated:
.withConverter(eventConverter)
Which is why it needs to be doc: any.
(But! You will actually get Array<Event> back! (Not Array<Map> back.) That's the entire point of withConverter... That way if you have any object methods (not shown here in this example), you can immediately use them.)
It makes sense to me but I guess I've gotten so greedy/spoiled that I just kinda expect my VS Code, ESLint, and the TS Watcher to literally do everything for me. Oh well.
Formal docs (about withConverter and more) here: https://firebase.google.com/docs/firestore/query-data/get-data#custom_objects
What is the { get; set; } syntax in C#?
Such { get; set; } syntax is called automatic properties, C# 3.0 syntax
You must use Visual C# 2008 / csc v3.5 or above to compile.
But you can compile output that targets as low as .NET Framework 2.0 (no runtime or classes required to support this feature).
How to set space between listView Items in Android
I found a not-so-good solution for this in case you are using a HorizontalListView, since dividers don't seem to work with it, but I think it'll work either way for the more common ListView.
Just adding:
<View
android:layout_marginBottom="xx dp/sp"/>
in the bottomest View of the Layout you inflate in the adapter class will create spacing between items
cut or awk command to print first field of first row
Specify NR if you want to capture output from selected rows:
awk 'NR==1{print $1}' /etc/*release
An alternative (ugly) way of achieving the same would be:
awk '{print $1; exit}'
An efficient way of getting the first string from a specific line, say line 42, in the output would be:
awk 'NR==42{print $1; exit}'
Could not establish secure channel for SSL/TLS with authority '*'
Problem
I was running into the same error message while calling a third party API from my ASP.NET Core MVC project.
Could not establish secure channel for SSL/TLS with authority
'{base_url_of_WS}'.
Solution
It turned out that the third party API's server required TLS 1.2. To resolve this issue, I added the following line of code to my controller's constructor:
System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;
Decode Base64 data in Java
This is a late answer, but Joshua Bloch committed his Base64 class (when he was working for Sun, ahem, Oracle) under the java.util.prefs package. This class existed since JDK 1.4.
E.g.
String currentString = "Hello World";
String base64String = java.util.prefs.Base64.byteArrayToBase64(currentString.getBytes("UTF-8"));
Using wire or reg with input or output in Verilog
reg and wire specify how the object will be assigned and are therefore only meaningful for outputs.
If you plan to assign your output in sequential code,such as within an always block, declare it as a reg (which really is a misnomer for "variable" in Verilog). Otherwise, it should be a wire, which is also the default.
Excel formula to get cell color
No, you can only get to the interior color of a cell by using a Macro. I am afraid. It's really easy to do (cell.interior.color) so unless you have a requirement that restricts you from using VBA, I say go for it.
Declaring an unsigned int in Java
Whether a value in an int is signed or unsigned depends on how the bits are interpreted - Java interprets bits as a signed value (it doesn't have unsigned primitives).
If you have an int that you want to interpret as an unsigned value (e.g. you read an int from a DataInputStream that you know should be interpreted as an unsigned value) then you can do the following trick.
int fourBytesIJustRead = someObject.getInt();
long unsignedValue = fourBytesIJustRead & 0xffffffffL;
Note, that it is important that the hex literal is a long literal, not an int literal - hence the 'L' at the end.
How to convert a std::string to const char* or char*?
If you just want to pass a std::string to a function that needs const char* you can use
std::string str;
const char * c = str.c_str();
If you want to get a writable copy, like char *, you can do that with this:
std::string str;
char * writable = new char[str.size() + 1];
std::copy(str.begin(), str.end(), writable);
writable[str.size()] = '\0'; // don't forget the terminating 0
// don't forget to free the string after finished using it
delete[] writable;
Edit: Notice that the above is not exception safe. If anything between the new call and the delete call throws, you will leak memory, as nothing will call delete for you automatically. There are two immediate ways to solve this.
boost::scoped_array
boost::scoped_array will delete the memory for you upon going out of scope:
std::string str;
boost::scoped_array<char> writable(new char[str.size() + 1]);
std::copy(str.begin(), str.end(), writable.get());
writable[str.size()] = '\0'; // don't forget the terminating 0
// get the char* using writable.get()
// memory is automatically freed if the smart pointer goes
// out of scope
std::vector
This is the standard way (does not require any external library). You use std::vector, which completely manages the memory for you.
std::string str;
std::vector<char> writable(str.begin(), str.end());
writable.push_back('\0');
// get the char* using &writable[0] or &*writable.begin()
How to remove whitespace from a string in typescript?
Problem
The trim() method removes whitespace from both sides of a string.
Source
Solution
You can use a Javascript replace method to remove white space like
"hello world".replace(/\s/g, "");
Example
_x000D_
_x000D_
var out = "hello world".replace(/\s/g, "");_x000D_
console.log(out);
_x000D_
_x000D_
_x000D_
How to destroy JWT Tokens on logout?
You cannot manually expire a token after it has been created. Thus, you cannot log out with JWT on the server-side as you do with sessions.
JWT is stateless, meaning that you should store everything you need in the payload and skip performing a DB query on every request. But if you plan to have a strict log out functionality, that cannot wait for the token auto-expiration, even though you have cleaned the token from the client-side, then you might need to neglect the stateless logic and do some queries. so what's a solution?
Set a reasonable expiration time on tokens
Delete the stored token from client-side upon log out
Query provided token against The Blacklist on every authorized request
Blacklist
“Blacklist” of all the tokens that are valid no more and have not expired yet. You can use a DB that has a TTL option on documents which would be set to the amount of time left until the token is expired.
Redis
Redis is a good option for blacklist, which will allow fast in-memory access to the list. Then, in the middleware of some kind that runs on every authorized request, you should check if the provided token is in The Blacklist. If it is you should throw an unauthorized error. And if it is not, let it go and the JWT verification will handle it and identify if it is expired or still active.
For more information, see How to log out when using JWT. by Arpy Vanyan
What's the best way to center your HTML email content in the browser window (or email client preview pane)?
I was struggling with Outlook and Office365. Surprisingly the thing that seemed to work was:
<table align='center' style='text-align:center'>
<tr>
<td align='center' style='text-align:center'>
<!-- AMAZING CONTENT! -->
</td>
</tr>
</table>
I only listed some of the key things that resolved my Microsoft email issues.
Might I add that building an email that looks nice on all emails is a pain. This website was super nice for testing: https://putsmail.com/
It allows you to list all the emails you'd like to send your test email to. You can paste your code right into the window, edit, send, and resend. It helped me a ton.
How do I write a for loop in bash
The bash for consists on a variable (the iterator) and a list of words where the iterator will, well, iterate.
So, if you have a limited list of words, just put them in the following syntax:
for w in word1 word2 word3
do
doSomething($w)
done
Probably you want to iterate along some numbers, so you can use the seq command to generate a list of numbers for you: (from 1 to 100 for example)
seq 1 100
and use it in the FOR loop:
for n in $(seq 1 100)
do
doSomething($n)
done
Note the $(...) syntax. It's a bash behaviour, it allows you to pass the output from one command (in our case from seq) to another (the for)
This is really useful when you have to iterate over all directories in some path, for example:
for d in $(find $somepath -type d)
do
doSomething($d)
done
The possibilities are infinite to generate the lists.
Console output in a Qt GUI app?
Make sure Qt5Core.dll is in the same directory with your application executable.
I had a similar issue in Qt5 with a console application:
if I start the application from Qt Creator, the output text is visible,
if I open cmd.exe and start the same application there, no output is visible.
Very strange!
I solved it by copying Qt5Core.dll to the directory with the application executable.
Here is my tiny console application:
#include <QCoreApplication>
#include <QDebug>
int main(int argc, char *argv[])
{
int x=343;
QString str("Hello World");
qDebug()<< str << x<<"lalalaa";
QTextStream out(stdout);
out << "aldfjals alsdfajs...";
}
How to use LDFLAGS in makefile
Your linker (ld) obviously doesn't like the order in which make arranges the GCC arguments so you'll have to change your Makefile a bit:
CC=gcc
CFLAGS=-Wall
LDFLAGS=-lm
.PHONY: all
all: client
.PHONY: clean
clean:
$(RM) *~ *.o client
OBJECTS=client.o
client: $(OBJECTS)
$(CC) $(CFLAGS) $(OBJECTS) -o client $(LDFLAGS)
In the line defining the client target change the order of $(LDFLAGS) as needed.
Error: Failed to lookup view in Express
This problem is basically seen because of case sensitive file name.
for example if you save file as index.jadge than its mane on route it should be "index" not "Index" in windows this is okay but in linux like server this will create issue.
1) if file name is index.jadge
app.get('/', function(req, res){
res.render("index");
});
2) if file name is Index.jadge
app.get('/', function(req, res){
res.render("Index");
});
Using variable in SQL LIKE statement
This works for me on the Northwind sample DB, note that SearchLetter has 2 characters to it and SearchLetter also has to be declared for this to run:
declare @SearchLetter2 char(2)
declare @SearchLetter char(1)
Set @SearchLetter = 'A'
Set @SearchLetter2 = @SearchLetter+'%'
select * from Customers where ContactName like @SearchLetter2 and Region='WY'
Attach to a processes output for viewing
I was looking for this exact same thing and found that you can do:
strace -ewrite -p $PID
It's not exactly what you needed, but it's quite close.
I tried the redirecting output, but that didn't work for me.
Maybe because the process was writing to a socket, I don't know.
Fastest way to determine if an integer's square root is an integer
If you want speed, given that your integers are of finite size, I suspect that the quickest way would involve (a) partitioning the parameters by size (e.g. into categories by largest bit set), then checking the value against an array of perfect squares within that range.
Can I bind an array to an IN() condition?
I took it a bit further to get the answer closer to the original question of using placeholders to bind the params.
This answer will have to make two loops through the array to be used in the query. But it does solve the issue of having other column placeholders for more selective queries.
//builds placeholders to insert in IN()
foreach($array as $key=>$value) {
$in_query = $in_query . ' :val_' . $key . ', ';
}
//gets rid of trailing comma and space
$in_query = substr($in_query, 0, -2);
$stmt = $db->prepare(
"SELECT *
WHERE id IN($in_query)";
//pind params for your placeholders.
foreach ($array as $key=>$value) {
$stmt->bindParam(":val_" . $key, $array[$key])
}
$stmt->execute();
How do you give iframe 100% height
You can do it with CSS:
<iframe style="position: absolute; height: 100%; border: none"></iframe>
Be aware that this will by default place it in the upper-left corner of the page, but I guess that is what you want to achieve. You can position with the left,right, top and bottom CSS properties.
When should the xlsm or xlsb formats be used?
Just for posterity, here's the text from several external sources regarding the Excel file formats. Some of these have been mentioned in other answers to this question but without reproducing the essential content.
1. From Doug Mahugh, August 22, 2006:
...the new XLSB binary format. Like Open XML, it’s a
full-fidelity file format that can store anything you can create in
Excel, but the XLSB format is optimized for performance in ways that
aren’t possible with a pure XML format.
The XLSB format (also sometimes referred to as BIFF12, as in “binary
file format for Office 12”) uses the same Open Packaging Convention
used by the Open XML formats and XPS. So it’s basically a ZIP
container, and you can open it with any ZIP tool to see what’s inside.
But instead of .XML parts within the package, you’ll find .BIN parts...
This article also refers to documentation about the BIN format, too lengthy to reproduce here.
2. From MSDN Archive, August 29, 2006 which in turn cites an already-missing blog post regarding the XLSB format:
Even though we’ve done a lot of work to make sure that our XML formats
open quickly and efficiently, this binary format is still more
efficient for Excel to open and save, and can lead to some performance
improvements for workbooks that contain a lot of data, or that would
require a lot of XML parsing during the Open process. (In fact, we’ve
found that the new binary format is faster than the old XLS format in
many cases.) Also, there is no macro-free version of this file format
– all XLSB files can contain macros (VBA and XLM). In all other
respects, it is functionally equivalent to the XML file format above:
File size – file size of both formats is approximately the same, since
both formats are saved to disk using zip compression Architecture –
both formats use the same packaging structure, and both have the same
part-level structures. Feature support – both formats support exactly
the same feature set Runtime performance – once loaded into memory,
the file format has no effect on application/calculation speed
Converters – both formats will have identical converter support
Using the last-child selector
As an alternative to using a class you could use a detailed list, setting the child dt elements to have one style and the child dd elements to have another. Your example would become:
#refundReasonMenu #nav li:dd
{
border-bottom: 1px solid #b5b5b5;
}
html:
<div id="refundReasonMenu">
<dl id="nav">
<dt><a id="abc" href="#">abcde</a></dt>
<dd><a id="def" href="#">xyz</a></dd>
</dl>
</div>
Neither method is better than the other and it is just down to personal preference.
How to solve "Connection reset by peer: socket write error"?
I've got the same exception and in my case the problem was in a renegotiation procecess. In fact my client closed a connection when the server tried to change a cipher suite. After digging it appears that in the jdk 1.6 update 22 renegotiation process is disabled by default. If your security constraints can effort this, try to enable the unsecure renegotiation by setting the sun.security.ssl.allowUnsafeRenegotiation system property to true. Here is some information about the process:
Session renegotiation is a mechanism within the SSL protocol that
allows the client or the server to trigger a new SSL handshake during
an ongoing SSL communication. Renegotiation was initially designed as
a mechanism to increase the security of an ongoing SSL channel, by
triggering the renewal of the crypto keys used to secure that channel.
However, this security measure isn't needed with modern cryptographic
algorithms. Additionally, renegotiation can be used by a server to
request a client certificate (in order to perform client
authentication) when the client tries to access specific, protected
resources on the server.
Additionally there is the excellent post about this issue in details and written in (IMHO) understandable language.
Usages of doThrow() doAnswer() doNothing() and doReturn() in mockito
To add a bit to accepted answer ...
If you get an UnfinishedStubbingException, be sure to set the method to be stubbed after the when closure, which is different than when you write Mockito.when
Mockito.doNothing().when(mock).method() //method is declared after 'when' closes
Mockito.when(mock.method()).thenReturn(something) //method is declared inside 'when'
Difference between binary tree and binary search tree
A binary tree is made of nodes, where each node contains a "left" pointer, a "right" pointer, and a data element. The "root" pointer points to the topmost node in the tree. The left and right pointers recursively point to smaller "subtrees" on either side. A null pointer represents a binary tree with no elements -- the empty tree. The formal recursive definition is: a binary tree is either empty (represented by a null pointer), or is made of a single node, where the left and right pointers (recursive definition ahead) each point to a binary tree.
A binary search tree (BST) or "ordered binary tree" is a type of binary tree where the nodes are arranged in order: for each node, all elements in its left subtree are less to the node (<), and all the elements in its right subtree are greater than the node (>).
5
/ \
3 6
/ \ \
1 4 9
The tree shown above is a binary search tree -- the "root" node is a 5, and its left subtree nodes (1, 3, 4) are < 5, and its right subtree nodes (6, 9) are > 5. Recursively, each of the subtrees must also obey the binary search tree constraint: in the (1, 3, 4) subtree, the 3 is the root, the 1 < 3 and 4 > 3.
Watch out for the exact wording in the problems -- a "binary search tree" is different from a "binary tree".
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);
}
Is the 'as' keyword required in Oracle to define an alias?
There is no difference between both, AS is just a more explicit way of mentioning the alias which is good because some dependent libraries depends on this small keyword. e.g. JDBC 4.0. Depend on use of it, different behaviour can be observed.
See this. I would always suggest to use the full form of semantic to avoid such issues.
Blur or dim background when Android PopupWindow active
The question was about the Popupwindow class, yet everybody has given answers that use the Dialog class. Thats pretty much useless if you need to use the Popupwindow class, because Popupwindow doesn't have a getWindow() method.
I've found a solution that actually works with Popupwindow. It only requires that the root of the xml file you use for the background activity is a FrameLayout. You can give the Framelayout element an android:foreground tag. What this tag does is specify a drawable resource that will be layered on top of the entire activity (that is, if the Framelayout is the root element in the xml file). You can then control the opacity (setAlpha()) of the foreground drawable.
You can use any drawable resource you like, but if you just want a dimming effect, create an xml file in the drawable folder with the <shape> tag as root.
<?xml version="1.0" encoding="utf-8"?>
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="#000000" />
</shape>
(See http://developer.android.com/guide/topics/resources/drawable-resource.html#Shape for more info on the shape element).
Note that I didn't specify an alpha value in the color tag that would make the drawable item transparent (e.g #ff000000). The reason for this is that any hardcoded alpha value seems to override any new alpha values we set via the setAlpha() in our code, so we don't want that.
However, that means that the drawable item will initially be opaque (solid, non-transparent). So we need to make it transparent in the activity's onCreate() method.
Here's the Framelayout xml element code:
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/mainmenu"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:foreground="@drawable/shape_window_dim" >
...
... your activity's content
...
</FrameLayout>
Here's the Activity's onCreate() method:
public void onCreate( Bundle savedInstanceState)
{
super.onCreate( savedInstanceState);
setContentView( R.layout.activity_mainmenu);
//
// Your own Activity initialization code
//
layout_MainMenu = (FrameLayout) findViewById( R.id.mainmenu);
layout_MainMenu.getForeground().setAlpha( 0);
}
Finally, the code to dim the activity:
layout_MainMenu.getForeground().setAlpha( 220); // dim
layout_MainMenu.getForeground().setAlpha( 0); // restore
The alpha values go from 0 (opaque) to 255 (invisible).
You should un-dim the activity when you dismiss the Popupwindow.
I haven't included code for showing and dismissing the Popupwindow, but here's a link to how it can be done: http://www.mobilemancer.com/2011/01/08/popup-window-in-android/
How to use *ngIf else?
For Angular 9/8
Source Link with Examples
export class AppComponent {
isDone = true;
}
1) *ngIf
<div *ngIf="isDone">
It's Done!
</div>
<!-- Negation operator-->
<div *ngIf="!isDone">
It's Not Done!
</div>
2) *ngIf and Else
<ng-container *ngIf="isDone; else elseNotDone">
It's Done!
</ng-container>
<ng-template #elseNotDone>
It's Not Done!
</ng-template>
3) *ngIf, Then and Else
<ng-container *ngIf="isDone; then iAmDone; else iAmNotDone">
</ng-container>
<ng-template #iAmDone>
It's Done!
</ng-template>
<ng-template #iAmNotDone>
It's Not Done!
</ng-template>
Is there a Python equivalent of the C# null-coalescing operator?
I realize this is answered, but there is another option when you're dealing with objects.
If you have an object that might be:
{
name: {
first: "John",
last: "Doe"
}
}
You can use:
obj.get(property_name, value_if_null)
Like:
obj.get("name", {}).get("first", "Name is missing")
By adding {} as the default value, if "name" is missing, an empty object is returned and passed through to the next get. This is similar to null-safe-navigation in C#, which would be like obj?.name?.first.
Remove part of string in Java
You could use replace to fix your string. The following will return everything before a "(" and also strip all leading and trailing whitespace. If the string starts with a "(" it will just leave it as is.
str = "manchester united (with nice players)"
matched = str.match(/.*(?=\()/)
str.replace(matched[0].strip) if matched
How to generate UL Li list from string array using jquery?
<script type="text/javascript" >
function aa()
{
var YourArray = ['United States', 'Canada', 'Argentina', 'Armenia'];
var ObjUl = $('<ul></ul>');
for (i = 0; i < YourArray.length; i++)
{
var Objli = $('<li></li>');
var Obja = $('<a></a>');
ObjUl.addClass("ui-menu-item");
ObjUl.attr("role", "menuitem");
Obja.addClass("ui-all");
Obja.attr("tabindex", "-1");
Obja.text(YourArray[i]);
Objli.append(Obja);
ObjUl.append(Objli);
}
$('.DivSai').append(ObjUl);
}
</script>
</head>
<body onload="aa()">
<form id="form1" runat="server">
<div class="DivSai" >
</div>
</form>
</body>
Get folder name from full file path
I figured there's no way except going into the file system to find out if text.txt is a directory or just a file. If you wanted something simple, maybe you can just use:
s.Substring(s.LastIndexOf(@"\"));
Pandas Merging 101
This post will go through the following topics:
- Merging with index under different conditions
- options for index-based joins:
merge, join, concat
- merging on indexes
- merging on index of one, column of other
- effectively using named indexes to simplify merging syntax
BACK TO TOP
Index-based joins
TL;DR
There are a few options, some simpler than others depending on the use
case.
DataFrame.merge with left_index and right_index (or left_on and right_on using names indexes)
- supports inner/left/right/full
- can only join two at a time
- supports column-column, index-column, index-index joins
DataFrame.join (join on index)
- supports inner/left (default)/right/full
- can join multiple DataFrames at a time
- supports index-index joins
pd.concat (joins on index)
- supports inner/full (default)
- can join multiple DataFrames at a time
- supports index-index joins
Index to index joins
Setup & Basics
import pandas as pd
import numpy as np
np.random.seed([3, 14])
left = pd.DataFrame(data={'value': np.random.randn(4)},
index=['A', 'B', 'C', 'D'])
right = pd.DataFrame(data={'value': np.random.randn(4)},
index=['B', 'D', 'E', 'F'])
left.index.name = right.index.name = 'idxkey'
left
value
idxkey
A -0.602923
B -0.402655
C 0.302329
D -0.524349
right
value
idxkey
B 0.543843
D 0.013135
E -0.326498
F 1.385076
Typically, an inner join on index would look like this:
left.merge(right, left_index=True, right_index=True)
value_x value_y
idxkey
B -0.402655 0.543843
D -0.524349 0.013135
Other joins follow similar syntax.
Notable Alternatives
DataFrame.join defaults to joins on the index. DataFrame.join does a LEFT OUTER JOIN by default, so how='inner' is necessary here.
left.join(right, how='inner', lsuffix='_x', rsuffix='_y')
value_x value_y
idxkey
B -0.402655 0.543843
D -0.524349 0.013135
Note that I needed to specify the lsuffix and rsuffix arguments since join would otherwise error out:
left.join(right)
ValueError: columns overlap but no suffix specified: Index(['value'], dtype='object')
Since the column names are the same. This would not be a problem if they were differently named.
left.rename(columns={'value':'leftvalue'}).join(right, how='inner')
leftvalue value
idxkey
B -0.402655 0.543843
D -0.524349 0.013135
pd.concat joins on the index and can join two or more DataFrames at once. It does a full outer join by default, so how='inner' is required here..
pd.concat([left, right], axis=1, sort=False, join='inner')
value value
idxkey
B -0.402655 0.543843
D -0.524349 0.013135
For more information on concat, see this post.
Index to Column joins
To perform an inner join using index of left, column of right, you will use DataFrame.merge a combination of left_index=True and right_on=....
right2 = right.reset_index().rename({'idxkey' : 'colkey'}, axis=1)
right2
colkey value
0 B 0.543843
1 D 0.013135
2 E -0.326498
3 F 1.385076
left.merge(right2, left_index=True, right_on='colkey')
value_x colkey value_y
0 -0.402655 B 0.543843
1 -0.524349 D 0.013135
Other joins follow a similar structure. Note that only merge can perform index to column joins. You can join on multiple columns, provided the number of index levels on the left equals the number of columns on the right.
join and concat are not capable of mixed merges. You will need to set the index as a pre-step using DataFrame.set_index.
Effectively using Named Index [pandas >= 0.23]
If your index is named, then from pandas >= 0.23, DataFrame.merge allows you to specify the index name to on (or left_on and right_on as necessary).
left.merge(right, on='idxkey')
value_x value_y
idxkey
B -0.402655 0.543843
D -0.524349 0.013135
For the previous example of merging with the index of left, column of right, you can use left_on with the index name of left:
left.merge(right2, left_on='idxkey', right_on='colkey')
value_x colkey value_y
0 -0.402655 B 0.543843
1 -0.524349 D 0.013135
Continue Reading
Jump to other topics in Pandas Merging 101 to continue learning:
* you are here
How do I make a batch file terminate upon encountering an error?
One minor update, you should change the checks for "if errorlevel 1" to the following...
IF %ERRORLEVEL% NEQ 0
This is because on XP you can get negative numbers as errors. 0 = no problems, anything else is a problem.
And keep in mind the way that DOS handles the "IF ERRORLEVEL" tests. It will return true if the number you are checking for is that number or higher so if you are looking for specific error numbers you need to start with 255 and work down.
JAX-RS — How to return JSON and HTTP status code together?
In case you want to change the status code because of an exception, with JAX-RS 2.0 you can implement an ExceptionMapper like this. This handles this kind of exception for the whole app.
@Provider
public class UnauthorizedExceptionMapper implements ExceptionMapper<EJBAccessException> {
@Override
public Response toResponse(EJBAccessException exception) {
return Response.status(Response.Status.UNAUTHORIZED.getStatusCode()).build();
}
}
Remove Unnamed columns in pandas dataframe
The approved solution doesn't work in my case, so my solution is the following one:
''' The column name in the example case is "Unnamed: 7"
but it works with any other name ("Unnamed: 0" for example). '''
df.rename({"Unnamed: 7":"a"}, axis="columns", inplace=True)
# Then, drop the column as usual.
df.drop(["a"], axis=1, inplace=True)
Hope it helps others.
How to set focus on an input field after rendering?
Simple solution without autofocus:
<input ref={ref => ref && ref.focus()}
onFocus={(e)=>e.currentTarget.setSelectionRange(e.currentTarget.value.length, e.currentTarget.value.length)}
/>
ref triggers focus, and that triggers onFocus to calculate the end and set the cursor accordingly.
Pan & Zoom Image
One addition to the superb solution provided by @Wieslaw Šoltés answer above
The existing code resets the image position using right click, but I am more accustomed to doing that with a double click. Just replace the existing child_MouseLeftButtonDown handler:
private void child_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
if (child != null)
{
var tt = GetTranslateTransform(child);
start = e.GetPosition(this);
origin = new Point(tt.X, tt.Y);
this.Cursor = Cursors.Hand;
child.CaptureMouse();
}
}
With this:
private void child_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
if ((e.ChangedButton == MouseButton.Left && e.ClickCount == 1))
{
if (child != null)
{
var tt = GetTranslateTransform(child);
start = e.GetPosition(this);
origin = new Point(tt.X, tt.Y);
this.Cursor = Cursors.Hand;
child.CaptureMouse();
}
}
if ((e.ChangedButton == MouseButton.Left && e.ClickCount == 2))
{
this.Reset();
}
}
How do I use a delimiter with Scanner.useDelimiter in Java?
With Scanner the default delimiters are the whitespace characters.
But Scanner can define where a token starts and ends based on a set of delimiter, wich could be specified in two ways:
- Using the Scanner method: useDelimiter(String pattern)
- Using the Scanner method : useDelimiter(Pattern pattern) where Pattern is a regular expression that specifies the delimiter set.
So useDelimiter() methods are used to tokenize the Scanner input, and behave like StringTokenizer class, take a look at these tutorials for further information:
And here is an Example:
public static void main(String[] args) {
// Initialize Scanner object
Scanner scan = new Scanner("Anna Mills/Female/18");
// initialize the string delimiter
scan.useDelimiter("/");
// Printing the tokenized Strings
while(scan.hasNext()){
System.out.println(scan.next());
}
// closing the scanner stream
scan.close();
}
Prints this output:
Anna Mills
Female
18
How do I break a string in YAML over multiple lines?
To preserve newlines use |, for example:
|
This is a very long sentence
that spans several lines in the YAML
but which will be rendered as a string
with newlines preserved.
is translated to "This is a very long sentence?\n that spans several lines in the YAML?\n but which will be rendered as a string?\n with newlines preserved.\n"
How to properly use unit-testing's assertRaises() with NoneType objects?
Complete snippet would look like the following. It expands @mouad's answer to asserting on error's message (or generally str representation of its args), which may be useful.
from unittest import TestCase
class TestNoneTypeError(TestCase):
def setUp(self):
self.testListNone = None
def testListSlicing(self):
with self.assertRaises(TypeError) as ctx:
self.testListNone[:1]
self.assertEqual("'NoneType' object is not subscriptable", str(ctx.exception))
How to draw border on just one side of a linear layout?
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="true" >
<shape>
<solid
android:color="#f28b24" />
<stroke
android:width="1dp"
android:color="#f28b24" />
<corners
android:radius="0dp"/>
<padding
android:left="0dp"
android:top="0dp"
android:right="0dp"
android:bottom="0dp" />
</shape>
</item>
<item>
<shape>
<gradient
android:startColor="#f28b24"
android:endColor="#f28b24"
android:angle="270" />
<stroke
android:width="0dp"
android:color="#f28b24" />
<corners
android:bottomLeftRadius="8dp"
android:bottomRightRadius="0dp"
android:topLeftRadius="0dp"
android:topRightRadius="0dp"/>
<padding
android:left="10dp"
android:top="10dp"
android:right="10dp"
android:bottom="10dp" />
</shape>
</item>
</selector>
How can I print the contents of a hash in Perl?
The easiest way in my experiences is to just use Dumpvalue.
use Dumpvalue;
...
my %hash = { key => "value", foo => "bar" };
my $dumper = new DumpValue();
$dumper->dumpValue(\%hash);
Works like a charm and you don't have to worry about formatting the hash, as it outputs it like the Perl debugger does (great for debugging). Plus, Dumpvalue is included with the stock set of Perl modules, so you don't have to mess with CPAN if you're behind some kind of draconian proxy (like I am at work).
What is the difference between "px", "dip", "dp" and "sp"?
sp = scale independent pixel
dp = dip = density independent pixels
dpi = dots per inch
We should avoid to use sp.
We should use dp to support multiple screens.
Android supports different screen resolutions
- ldpi (low) ~120 dpi
- mdpi (medium) ~160 dpi
- hdpi (high) ~240 dpi
- xhdpi (extra-high) ~320 dpi
- xxhdpi (extra-extra-high) ~480 dpi
- xxxhdpi (extra-extra-extra-high) ~640 dpi
An 120 dp ldpi device has 120 pixels in 1 inch size.
The same for other densities...
We as software engineers should use this conversion formula:
pixel = dp * (density / 160)
So 240 dpi device's 1 dp will have = 1 * (240/160) = 3/2 = 1.5 pixels.
And 480 dpi device's 1 dp will have = 1 * (480/160) = 3 pixels.
Using this 1.5 and 3 pixels knowledge, a software engineer can design layouts for different densities.
To check screen parameters of any device:
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
Toast.makeText(
this,
"4:" + metrics.heightPixels + "," + metrics.density + ","
+ metrics.densityDpi, Toast.LENGTH_LONG).show();
How to save and extract session data in codeigniter
initialize the Session class in the constructor of controller using
$this->load->library('session');
for example :
function __construct()
{
parent::__construct();
$this->load->model('user','',TRUE);
$this->load->model('user_activity','',TRUE);
$this->load->library('session');
}
Using Jquery AJAX function with datatype HTML
var datos = $("#id_formulario").serialize();
$.ajax({
url: "url.php",
type: "POST",
dataType: "html",
data: datos,
success: function (prueba) {
alert("funciona!");
}//FIN SUCCES
});//FIN AJAX
Scroll back to the top of scrollable div
For me the scrollTop way did not work, but I found other:
element.style.display = 'none';
setTimeout(function() { element.style.display = 'block' }, 100);
Did not check the minimum time for reliable css rendering though, 100ms might be overkill.
Generate a random letter in Python
You can use this to get one or more random letter(s)
import random
import string
random.seed(10)
letters = string.ascii_lowercase
rand_letters = random.choices(letters,k=5) # where k is the number of required rand_letters
print(rand_letters)
['o', 'l', 'p', 'f', 'v']
Creating a Custom Event
Based on @ionden's answer, the call to the delegate could be simplified using null propagation since C# 6.0.
Your code would simply be:
class MyClass {
public event EventHandler MyEvent;
public void Method() {
MyEvent?.Invoke(this, EventArgs.Empty);
}
}
Use it like this:
MyClass myObject = new MyClass();
myObject.MyEvent += new EventHandler(myObject_MyEvent);
myObject.Method();
Python + Regex: AttributeError: 'NoneType' object has no attribute 'groups'
import re
htmlString = '</dd><dt> Fine, thank you. </dt><dd> Molt bé, gràcies. (<i>mohl behh, GRAH-syuhs</i>)'
SearchStr = '(\<\/dd\>\<dt\>)+ ([\w+\,\.\s]+)([\&\#\d\;]+)(\<\/dt\>\<dd\>)+ ([\w\,\s\w\s\w\?\!\.]+) (\(\<i\>)([\w\s\,\-]+)(\<\/i\>\))'
Result = re.search(SearchStr.decode('utf-8'), htmlString.decode('utf-8'), re.I | re.U)
print Result.groups()
Works that way. The expression contains non-latin characters, so it usually fails. You've got to decode into Unicode and use re.U (Unicode) flag.
I'm a beginner too and I faced that issue a couple of times myself.
Single quotes vs. double quotes in C or C++
Some compilers also implement an extension, that allows multi-character constants. The C99 standard says:
6.4.4.4p10: "The value of an integer character constant containing more
than one character (e.g., 'ab'), or
containing a character or escape
sequence that does not map to a
single-byte execution character, is
implementation-defined."
This could look like this, for instance:
const uint32_t png_ihdr = 'IHDR';
The resulting constant (in GCC, which implements this) has the value you get by taking each character and shifting it up, so that 'I' ends up in the most significant bits of the 32-bit value. Obviously, you shouldn't rely on this if you are writing platform independent code.
How to make an Android Spinner with initial text "Select One"?
I have a spinner on my main.xml and its id is @+id/spinner1
this is what i write in my OnCreate function :
spinner1 = (Spinner)this.findViewById(R.id.spinner1);
final String[] groupes = new String[] {"A", "B", "C", "D", "E", "F", "G", "H"};
ArrayAdapter<CharSequence> featuresAdapter = new ArrayAdapter<CharSequence>(this, android.R.layout.simple_spinner_item, new ArrayList<CharSequence>());
featuresAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner1.setAdapter(featuresAdapter);
for (String s : groupes) featuresAdapter.add(s);
spinner1.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> arg0, View arg1, int position, long id) {
// Here go your instructions when the user chose something
Toast.makeText(getBaseContext(), groupes[position], 0).show();
}
public void onNothingSelected(AdapterView<?> arg0) { }
});
It doesn't need any implementation in the class.
Deleting an object in java?
You should remove the references to it by assigning null or leaving the block where it was declared. After that, it will be automatically deleted by the garbage collector (not immediately, but eventually).
Example 1:
Object a = new Object();
a = null; // after this, if there is no reference to the object,
// it will be deleted by the garbage collector
Example 2:
if (something) {
Object o = new Object();
} // as you leave the block, the reference is deleted.
// Later on, the garbage collector will delete the object itself.
Not something that you are currently looking for, but FYI: you can invoke the garbage collector with the call System.gc()
Database development mistakes made by application developers
I'd like to add:
Favoring "Elegant" code over highly performing code. The code that works best against databases is often ugly to the application developer's eye.
Believing that nonsense about premature optimization. Databases must consider performance in the original design and in any subsequent development. Performance is 50% of database design (40% is data integrity and the last 10% is security) in my opinion. Databases which are not built from the bottom up to perform will perform badly once real users and real traffic are placed against the database. Premature optimization doesn't mean no optimization! It doesn't mean you should write code that will almost always perform badly because you find it easier (cursors for example which should never be allowed in a production database unless all else has failed). It means you don't need to look at squeezing out that last little bit of performance until you need to. A lot is known about what will perform better on databases, to ignore this in design and development is short-sighted at best.
Android Endless List
Just wanted to contribute a solution that I used for my app.
It is also based on the OnScrollListener interface, but I found it to have a much better scrolling performance on low-end devices, since none of the visible/total count calculations are carried out during the scroll operations.
- Let your
ListFragment or ListActivity implement OnScrollListener
Add the following methods to that class:
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
//leave this empty
}
@Override
public void onScrollStateChanged(AbsListView listView, int scrollState) {
if (scrollState == SCROLL_STATE_IDLE) {
if (listView.getLastVisiblePosition() >= listView.getCount() - 1 - threshold) {
currentPage++;
//load more list items:
loadElements(currentPage);
}
}
}
where currentPage is the page of your datasource that should be added to your list, and threshold is the number of list items (counted from the end) that should, if visible, trigger the loading process. If you set threshold to 0, for instance, the user has to scroll to the very end of the list in order to load more items.
(optional) As you can see, the "load-more check" is only called when the user stops scrolling. To improve usability, you may inflate and add a loading indicator to the end of the list via listView.addFooterView(yourFooterView). One example for such a footer view:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/footer_layout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="10dp" >
<ProgressBar
android:id="@+id/progressBar1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_gravity="center_vertical" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_toRightOf="@+id/progressBar1"
android:padding="5dp"
android:text="@string/loading_text" />
</RelativeLayout>
(optional) Finally, remove that loading indicator by calling listView.removeFooterView(yourFooterView) if there are no more items or pages.
How to add favicon.ico in ASP.NET site
_x000D_
_x000D_
<link rel="shortcut icon" type="image/x-icon" href="~/favicon.ico" />
_x000D_
_x000D_
_x000D_
This worked for me. If anyone is troubleshooting while reading this - I found issues when my favicon.ico was not nested in the root folder. I had mine in the Resources folder and was struggling at that point.
Remove the complete styling of an HTML button/submit
Your question says "Internet Explorer," but for those interested in other browsers, you can now use all: unset on buttons to unstyle them.
It doesn't work in IE, but it's well-supported everywhere else.
https://caniuse.com/#feat=css-all
Old Safari color warning: Setting the text color of the button after using all: unset can fail in Safari 13.1, due to a bug in WebKit. (The bug is fixed in Safari 14 and up.) "all: unset is setting -webkit-text-fill-color to black, and that overrides color." If you need to set text color after using all: unset, be sure to set both the color and the -webkit-text-fill-color to the same color.
Accessibility warning: For the sake of users who aren't using a mouse pointer, be sure to re-add some :focus styling, e.g. button:focus { outline: orange auto 5px } for keyboard accessibility.
And don't forget cursor: pointer. all: unset removes all styling, including the cursor: pointer, which makes your mouse cursor look like a pointing hand when you hover over the button. You almost certainly want to bring that back.
_x000D_
_x000D_
button {
all: unset;
color: blue;
-webkit-text-fill-color: blue;
cursor: pointer;
}
button:focus {
outline: orange 5px auto;
}
_x000D_
<button>check it out</button>
_x000D_
_x000D_
_x000D_
What's the "Content-Length" field in HTTP header?
From this page
The most common use of POST, by far,
is to submit HTML form data to CGI
scripts. In this case, the
Content-Type: header is usually
application/x-www-form-urlencoded,
and the Content-Length: header gives
the length of the URL-encoded form
data (here's a note on URL-encoding).
The CGI script receives the message
body through STDIN, and decodes it.
Here's a typical form submission,
using POST:
POST /path/script.cgi HTTP/1.0
From: [email protected]
User-Agent: HTTPTool/1.0
Content-Type: application/x-www-form-urlencoded
Content-Length: 32
Making interface implementations async
Better solution is to introduce another interface for async operations. New interface must inherit from original interface.
Example:
interface IIO
{
void DoOperation();
}
interface IIOAsync : IIO
{
Task DoOperationAsync();
}
class ClsAsync : IIOAsync
{
public void DoOperation()
{
DoOperationAsync().GetAwaiter().GetResult();
}
public async Task DoOperationAsync()
{
//just an async code demo
await Task.Delay(1000);
}
}
class Program
{
static void Main(string[] args)
{
IIOAsync asAsync = new ClsAsync();
IIO asSync = asAsync;
Console.WriteLine(DateTime.Now.Second);
asAsync.DoOperation();
Console.WriteLine("After call to sync func using Async iface: {0}",
DateTime.Now.Second);
asAsync.DoOperationAsync().GetAwaiter().GetResult();
Console.WriteLine("After call to async func using Async iface: {0}",
DateTime.Now.Second);
asSync.DoOperation();
Console.WriteLine("After call to sync func using Sync iface: {0}",
DateTime.Now.Second);
Console.ReadKey(true);
}
}
P.S.
Redesign your async operations so they return Task instead of void, unless you really must return void.
How to get a unix script to run every 15 seconds?
Since my previous answer I came up with another solution that is different and perhaps better. This code allows processes to be run more than 60 times a minute with microsecond precision. You need the usleep program to make this work. Should be good to up to 50 times a second.
#! /bin/sh
# Microsecond Cron
# Usage: cron-ms start
# Copyright 2014 by Marc Perkel
# docs at http://wiki.junkemailfilter.com/index.php/How_to_run_a_Linux_script_every_few_seconds_under_cron"
# Free to use with attribution
basedir=/etc/cron-ms
if [ $# -eq 0 ]
then
echo
echo "cron-ms by Marc Perkel"
echo
echo "This program is used to run all programs in a directory in parallel every X times per minute."
echo "Think of this program as cron with microseconds resolution."
echo
echo "Usage: cron-ms start"
echo
echo "The scheduling is done by creating directories with the number of"
echo "executions per minute as part of the directory name."
echo
echo "Examples:"
echo " /etc/cron-ms/7 # Executes everything in that directory 7 times a minute"
echo " /etc/cron-ms/30 # Executes everything in that directory 30 times a minute"
echo " /etc/cron-ms/600 # Executes everything in that directory 10 times a second"
echo " /etc/cron-ms/2400 # Executes everything in that directory 40 times a second"
echo
exit
fi
# If "start" is passed as a parameter then run all the loops in parallel
# The number of the directory is the number of executions per minute
# Since cron isn't accurate we need to start at top of next minute
if [ $1 = start ]
then
for dir in $basedir/* ; do
$0 ${dir##*/} 60000000 &
done
exit
fi
# Loops per minute and the next interval are passed on the command line with each loop
loops=$1
next_interval=$2
# Sleeps until a specific part of a minute with microsecond resolution. 60000000 is full minute
usleep $(( $next_interval - 10#$(date +%S%N) / 1000 ))
# Run all the programs in the directory in parallel
for program in $basedir/$loops/* ; do
if [ -x $program ]
then
$program &> /dev/null &
fi
done
# Calculate next_interval
next_interval=$(($next_interval % 60000000 + (60000000 / $loops) ))
# If minute is not up - call self recursively
if [ $next_interval -lt $(( 60000000 / $loops * $loops)) ]
then
. $0 $loops $next_interval &
fi
# Otherwise we're done
How can I get my Android device country code without using GPS?
You can simply use this code,
TelephonyManager tm = (TelephonyManager)this.getSystemService(Context.TELEPHONY_SERVICE);
String countryCodeValue = tm.getNetworkCountryIso();
This will return 'US' if your current connected network is in the United States. This works without a SIM card even.
How to move table from one tablespace to another in oracle 11g
I tried many scripts but they didn't work for all objects. You can't move clustered objects from one tablespace to another. For that you will have to use expdp, so I will suggest expdp is the best option to move all objects to a different tablespace.
Below is the command:
nohup expdp \"/ as sysdba\" DIRECTORY=test_dir DUMPFILE=users.dmp LOGFILE=users.log TABLESPACES=USERS &
You can check this link for details.
How to use mouseover and mouseout in Angular 6
Adding to what was already said.
if you want to *ngFor an element , and hide \ show elements in it, on hover, like you added in the comments, you should re-think the whole concept.
a more appropriate way to do it, does not involve angular at all.
I would go with pure CSS instead, using its native :hover property.
something like:
App.Component.css
div span.only-show-on-hover {
visibility: hidden;
}
div:hover span.only-show-on-hover {
visibility: visible;
}
App.Component.html
<div *ngFor="let i of [1,2,3,4]" > hover me please.
<span class="only-show-on-hover">you only see me when hovering</span>
</div>
added a demo: https://stackblitz.com/edit/hello-angular-6-hvgx7n?file=src%2Fapp%2Fapp.component.html
Truncate with condition
No, TRUNCATE is all or nothing. You can do a DELETE FROM <table> WHERE <conditions> but this loses the speed advantages of TRUNCATE.
How to load data to hive from HDFS without removing the source file?
An alternative to 'LOAD DATA' is available in which the data will not be moved from your existing source location to hive data warehouse location.
You can use ALTER TABLE command with 'LOCATION' option. Here is below required command
ALTER TABLE table_name ADD PARTITION (date_col='2017-02-07') LOCATION 'hdfs/path/to/location/'
The only condition here is, the location should be a directory instead of file.
Hope this will solve the problem.
What is object slicing?
Most answers here fail to explain what the actual problem with slicing is. They only explain the benign cases of slicing, not the treacherous ones. Assume, like the other answers, that you're dealing with two classes A and B, where B derives (publicly) from A.
In this situation, C++ lets you pass an instance of B to A's assignment operator (and also to the copy constructor). This works because an instance of B can be converted to a const A&, which is what assignment operators and copy-constructors expect their arguments to be.
The benign case
B b;
A a = b;
Nothing bad happens there - you asked for an instance of A which is a copy of B, and that's exactly what you get. Sure, a won't contain some of b's members, but how should it? It's an A, after all, not a B, so it hasn't even heard about these members, let alone would be able to store them.
The treacherous case
B b1;
B b2;
A& a_ref = b2;
a_ref = b1;
//b2 now contains a mixture of b1 and b2!
You might think that b2 will be a copy of b1 afterward. But, alas, it's not! If you inspect it, you'll discover that b2 is a Frankensteinian creature, made from some chunks of b1 (the chunks that B inherits from A), and some chunks of b2 (the chunks that only B contains). Ouch!
What happened? Well, C++ by default doesn't treat assignment operators as virtual. Thus, the line a_ref = b1 will call the assignment operator of A, not that of B. This is because, for non-virtual functions, the declared (formally: static) type (which is A&) determines which function is called, as opposed to the actual (formally: dynamic) type (which would be B, since a_ref references an instance of B). Now, A's assignment operator obviously knows only about the members declared in A, so it will copy only those, leaving the members added in B unchanged.
A solution
Assigning only to parts of an object usually makes little sense, yet C++, unfortunately, provides no built-in way to forbid this. You can, however, roll your own. The first step is making the assignment operator virtual. This will guarantee that it's always the actual type's assignment operator which is called, not the declared type's. The second step is to use dynamic_cast to verify that the assigned object has a compatible type. The third step is to do the actual assignment in a (protected!) member assign(), since B's assign() will probably want to use A's assign() to copy A's, members.
class A {
public:
virtual A& operator= (const A& a) {
assign(a);
return *this;
}
protected:
void assign(const A& a) {
// copy members of A from a to this
}
};
class B : public A {
public:
virtual B& operator= (const A& a) {
if (const B* b = dynamic_cast<const B*>(&a))
assign(*b);
else
throw bad_assignment();
return *this;
}
protected:
void assign(const B& b) {
A::assign(b); // Let A's assign() copy members of A from b to this
// copy members of B from b to this
}
};
Note that, for pure convenience, B's operator= covariantly overrides the return type, since it knows that it's returning an instance of B.
How to get list of dates between two dates in mysql select query
Try:
select * from
(select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) selected_date from
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4) v
where selected_date between '2012-02-10' and '2012-02-15'
-for date ranges up to nearly 300 years in the future.
[Corrected following a suggested edit by UrvishAtSynapse.]
Adding dictionaries together, Python
If you're interested in creating a new dict without using intermediary storage: (this is faster, and in my opinion, cleaner than using dict.items())
dic2 = dict(dic0, **dic1)
Or if you're happy to use one of the existing dicts:
dic0.update(dic1)
compareTo() vs. equals()
This is an experiment in necromancy :-)
Most answers compare performance and API differences. They miss the fundamental point that the two operations simply have different semantics.
Your intuition is correct. x.equals(y) is not interchangeable with x.compareTo(y) == 0.
The first compares identity, while the other compares the notion of 'size'. It is true that in many cases, especially with primitive types, these two co-align.
The general case is this:
If x and y are identical, they share the same 'size': if x.equals(y) is true => x.compareTo(y) is 0.
However, if x and y share the same size, it does not mean they are identical.
if x.compareTo(y) is 0 does not necessarily mean x.equals(y) is true.
A compelling example where identity differs from size would be complex numbers. Assume that the comparison is done by their absolute value. So given two complex numbers: Z1 = a1 + b1*i and Z2 = a2 + b2*i:
Z1.equals(z2) returns true if and only if a1 = a2 and b1 = b2.
However Z1.compareTo(Z2) returns 0 for and infinite number of (a1,b1) and (a2,b2) pairs as long as they satisfy the condition a1^2 + b1^2 == a2^2 + b2^2.
What does string::npos mean in this code?
std::string::npos is implementation defined index that is always out of bounds of any std::string instance. Various std::string functions return it or accept it to signal beyond the end of the string situation. It is usually of some unsigned integer type and its value is usually std::numeric_limits<std::string::size_type>::max () which is (thanks to the standard integer promotions) usually comparable to -1.
Git command to display HEAD commit id?
According to https://git-scm.com/docs/git-log,
for more pretty output in console you can use --decorate argument of git-log command:
git log --pretty=oneline --decorate
will print:
2a5ccd714972552064746e0fb9a7aed747e483c7 (HEAD -> master) New commit
fe00287269b07e2e44f25095748b86c5fc50a3ef (tag: v1.1-01) Commit 3
08ed8cceb27f4f5e5a168831d20a9d2fa5c91d8b (tag: v1.1, tag: v1.0-0.1) commit 1
116340f24354497af488fd63f4f5ad6286e176fc (tag: v1.0) second
52c1cdcb1988d638ec9e05a291e137912b56b3af test
Laravel update model with unique validation rule for attribute
I have BaseModel class, so I needed something more generic.
//app/BaseModel.php
public function rules()
{
return $rules = [];
}
public function isValid($id = '')
{
$validation = Validator::make($this->attributes, $this->rules($id));
if($validation->passes()) return true;
$this->errors = $validation->messages();
return false;
}
In user class let's suppose I need only email and name to be validated:
//app/User.php
//User extends BaseModel
public function rules($id = '')
{
$rules = [
'name' => 'required|min:3',
'email' => 'required|email|unique:users,email',
'password' => 'required|alpha_num|between:6,12',
'password_confirmation' => 'same:password|required|alpha_num|between:6,12',
];
if(!empty($id))
{
$rules['email'].= ",$id";
unset($rules['password']);
unset($rules['password_confirmation']);
}
return $rules;
}
I tested this with phpunit and works fine.
//tests/models/UserTest.php
public function testUpdateExistingUser()
{
$user = User::find(1);
$result = $user->id;
$this->assertEquals(true, $result);
$user->name = 'test update';
$user->email = '[email protected]';
$user->save();
$this->assertTrue($user->isValid($user->id), 'Expected to pass');
}
I hope will help someone, even if for getting a better idea. Thanks for sharing yours as well.
(tested on Laravel 5.0)
java.lang.IllegalStateException: Cannot (forward | sendRedirect | create session) after response has been committed
Typically you see this error after you have already done a redirect and then try to output some more data to the output stream. In the cases where I have seen this in the past, it is often one of the filters that is trying to redirect the page, and then still forwards through to the servlet. I cannot see anything immediately wrong with the servlet, so you might want to try having a look at any filters that you have in place as well.
Edit: Some more help in diagnosing the problem…
The first step to diagnosing this problem is to ascertain exactly where the exception is being thrown. We are assuming that it is being thrown by the line
getServletConfig().getServletContext()
.getRequestDispatcher("/GroupCopiedUpdt.jsp")
.forward(request, response);
But you might find that it is being thrown later in the code, where you are trying to output to the output stream after you have tried to do the forward. If it is coming from the above line, then it means that somewhere before this line you have either:
- output data to the output stream, or
- done another redirect beforehand.
Good luck!
Chmod 777 to a folder and all contents
You can give permission to folder and all its contents using option -R i.e Recursive permissions.
But I would suggest not to give 777 permission to all folder and it's all contents. You should give specific permission to each sub-folder in www directory folders.
Ideally, give 755 permission for security reasons to the web folder.
sudo chmod -R 755 /www/store
Each number has meaning in permission. Do not give full permission.
N Description ls binary
0 No permissions at all --- 000
1 Only execute --x 001
2 Only write -w- 010
3 Write and execute -wx 011
4 Only read r-- 100
5 Read and execute r-x 101
6 Read and write rw- 110
7 Read, write, and execute rwx 111
- First Number 7 - Read, write, and execute for the user.
- Second Number 5 - Read and execute for the group.
- Third Number 5 - Read and execute for others.
If your production web folder has multiple users, then you can set permissions and user groups accordingly.
More info :
- Understanding File Permissions: What Does “Chmod 777" Mean?
- What file permissions should I set on web root?
- Why shouldn't /var/www have chmod 777
What is the maximum recursion depth in Python, and how to increase it?
I'm not sure I'm repeating someone but some time ago some good soul wrote Y-operator for recursively called function like:
def tail_recursive(func):
y_operator = (lambda f: (lambda y: y(y))(lambda x: f(lambda *args: lambda: x(x)(*args))))(func)
def wrap_func_tail(*args):
out = y_operator(*args)
while callable(out): out = out()
return out
return wrap_func_tail
and then recursive function needs form:
def my_recursive_func(g):
def wrapped(some_arg, acc):
if <condition>: return acc
return g(some_arg, acc)
return wrapped
# and finally you call it in code
(tail_recursive(my_recursive_func))(some_arg, acc)
for Fibonacci numbers your function looks like this:
def fib(g):
def wrapped(n_1, n_2, n):
if n == 0: return n_1
return g(n_2, n_1 + n_2, n-1)
return wrapped
print((tail_recursive(fib))(0, 1, 1000000))
output:
..684684301719893411568996526838242546875
(actually tones of digits)
Python Web Crawlers and "getting" html source code
An Example with python3 and the requests library as mentioned by @leoluk:
pip install requests
Script req.py:
import requests
url='http://localhost'
# in case you need a session
cd = { 'sessionid': '123..'}
r = requests.get(url, cookies=cd)
# or without a session: r = requests.get(url)
r.content
Now,execute it and you will get the html source of localhost!
python3 req.py
php return 500 error but no error log
Scan your source files to find @.
From php documentation site
Currently the "@" error-control operator prefix will even disable
error reporting for critical errors that will terminate script
execution. Among other things, this means that if you use "@" to
suppress errors from a certain function and either it isn't available
or has been mistyped, the script will die right there with no
indication as to why.
Close Current Tab
As of Chrome 46, a simple onclick=window.close() does the trick. This only closes the tab, and not the entire browser, if multiple tabs are opened.
Access properties file programmatically with Spring?
create .properties file in classpath of your project and add path configuration in xml`<context:property-placeholder location="classpath*:/*.properties" />`
in servlet-context.xml after that u can directly use your file everywhere
How to run iPhone emulator WITHOUT starting Xcode?
With Xcode 6 the location of the simulator has changed to:
/Applications/Xcode.app/Contents/Developer/Applications/iOS Simulator.app
It can no longer be found here:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Applications/iPhone Simulator.app
I hope this helps someone since I sometimes want to start the simulator from terminal.
Javascript Object push() function
Javascript programming language supports functional programming paradigm so you can do easily with these codes.
var data = [
{"Id": "1", "Status": "Valid"},
{"Id": "2", "Status": "Invalid"}
];
var isValid = function(data){
return data.Status === "Valid";
};
var valids = data.filter(isValid);
POSTing JsonObject With HttpClient From Web API
With the new version of HttpClient and without the WebApi package it would be:
var content = new StringContent(jsonObject.ToString(), Encoding.UTF8, "application/json");
var result = client.PostAsync(url, content).Result;
Or if you want it async:
var result = await client.PostAsync(url, content);
CKEditor instance already exists
This is the fully working code for jquery .load() api and ckeditor, in my case I am loading a page with ckeditor into div with some jquery effects. I hope it will help you.
$(function() {
runEffect = function(fileload,lessonid,act) {
var selectedEffect = 'drop';
var options = {};
$( "#effect" ).effect( selectedEffect, options, 200, callback(fileload,lessonid,act) );
};
function callback(fileload,lessonid,act) {
setTimeout(function() {//load the page in effect div
$( "#effect" ).load(fileload,{lessonid:lessonid,act:act});
$("#effect").show( "drop",
{direction: "right"}, 200 );
$("#effect").ajaxComplete(function(event, XMLHttpRequest, ajaxOptions) {
loadCKeditor(); //call the function after loading page
});
}, 100 );
};
function loadCKeditor()
{//you need to destroy the instance if already exist
if (CKEDITOR.instances['introduction'])
{
CKEDITOR.instances['introduction'].destroy();
}
CKEDITOR.replace('introduction').getSelection().getSelectedText();
}
});
===================== button for call the function ================================
<input type="button" name="button" id="button" onclick="runEffect('lesson.php','','add')" >
GCC fatal error: stdio.h: No such file or directory
Mac OS Mojave
The accepted answer no longer works. When running the command xcode-select --install it tells you to use "Software Update" to install updates.
In this link is the updated method:
Open a Terminal and then:
cd /Library/Developer/CommandLineTools/Packages/
open macOS_SDK_headers_for_macOS_10.14.pkg
This will open an installation Wizard.
Update 12/2019
After updating to Mojave 10.15.1 it seems that using xcode-select --install works as intended.
Postgres where clause compare timestamp
Assuming you actually mean timestamp because there is no datetime in Postgres
Cast the timestamp column to a date, that will remove the time part:
select *
from the_table
where the_timestamp_column::date = date '2015-07-15';
This will return all rows from July, 15th.
Note that the above will not use an index on the_timestamp_column. If performance is critical, you need to either create an index on that expression or use a range condition:
select *
from the_table
where the_timestamp_column >= timestamp '2015-07-15 00:00:00'
and the_timestamp_column < timestamp '2015-07-16 00:00:00';
Play local (hard-drive) video file with HTML5 video tag?
Ran in to this problem a while ago.
Website couldn't access video file on local PC due to security settings (understandable really)
ONLY way I could get around it was to run a webserver on the local PC (server2Go) and all references to the video file from the web were to the localhost/video.mp4
<div id="videoDiv">
<video id="video" src="http://127.0.0.1:4001/videos/<?php $videoFileName?>" width="70%" controls>
</div>
<!--End videoDiv-->
Not an ideal solution but worked for me.
Make a borderless form movable?
Let's not make things any more difficult than they need to be. I've come across so many snippets of code that allow you to drag a form around (or another Control). And many of them have their own drawbacks/side effects. Especially those ones where they trick Windows into thinking that a Control on a form is the actual form.
That being said, here is my snippet. I use it all the time. I'd also like to note that you should not use this.Invalidate(); as others like to do because it causes the form to flicker in some cases. And in some cases so does this.Refresh. Using this.Update, I have not had any flickering issues:
private bool mouseDown;
private Point lastLocation;
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
mouseDown = true;
lastLocation = e.Location;
}
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
if(mouseDown)
{
this.Location = new Point(
(this.Location.X - lastLocation.X) + e.X, (this.Location.Y - lastLocation.Y) + e.Y);
this.Update();
}
}
private void Form1_MouseUp(object sender, MouseEventArgs e)
{
mouseDown = false;
}
On localhost, how do I pick a free port number?
For the sake of snippet of what the guys have explained above:
import socket
from contextlib import closing
def find_free_port():
with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
s.bind(('', 0))
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
return s.getsockname()[1]
Sql Query to list all views in an SQL Server 2005 database
Run this adding DatabaseName in where condition.
SELECT TABLE_NAME, ROW_NUMBER() OVER(ORDER BY TABLE_NAME) AS 'RowNumber'
FROM INFORMATION_SCHEMA.VIEWS
WHERE TABLE_CATALOG = 'DatabaseName'
or remove where condition adding use.
use DataBaseName
SELECT TABLE_NAME, ROW_NUMBER() OVER(ORDER BY TABLE_NAME) AS 'RowNumber'
FROM INFORMATION_SCHEMA.VIEWS
Using JQuery hover with HTML image map
This question is old but I wanted to add an alternative to the accepted answer which didn't exist at the time.
Image Mapster is a jQuery plugin that I wrote to solve some of the shortcomings of Map Hilight (and it was initially an extension of that plugin, though it's since been almost completely rewritten). Initially, this was just the ability to maintain selection state for areas, fix browser compatibility problems. Since its initial release a few months ago, though, I have added a lot of features including the ability to use an alternate image as the source for the highlights.
It also has the ability to identify areas as "masks," meaning you can create areas with "holes", and additionally create complex groupings of areas. For example, area A could cause another area B to be highlighted, but area B itself would not respond to mouse events.
There are a few examples on the web site that show most of the features. The github repository also has more examples and complete documentation.
mysqldump with create database line
By default mysqldump always creates the CREATE DATABASE IF NOT EXISTS db_name; statement at the beginning of the dump file.
[EDIT] Few things about the mysqldump file and it's options:
--all-databases, -A
Dump all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.
--add-drop-database
Add a DROP DATABASE statement before each CREATE DATABASE statement. This option is typically used in conjunction with the --all-databases or --databases option because no CREATE DATABASE statements are written unless one of those options is specified.
--databases, -B
Dump several databases. Normally, mysqldump treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names. CREATE DATABASE and USE statements are included in the output before each new database.
--no-create-db, -n
This option suppresses the CREATE DATABASE statements that are otherwise included in the output if the --databases or --all-databases option is given.
Some time ago, there was similar question actually asking about not having such statement on the beginning of the file (for XML file). Link to that question is here.
So to answer your question:
- if you have one database to dump, you should have the
--add-drop-database option in your mysqldump statement.
- if you have multiple databases to dump, you should use the option
--databases or --all-databases and the CREATE DATABASE syntax will be added
automatically
More information at MySQL Reference Manual
Authentication issues with WWW-Authenticate: Negotiate
The web server is prompting you for a SPNEGO (Simple and Protected GSSAPI Negotiation Mechanism) token.
This is a Microsoft invention for negotiating a type of authentication to use for Web SSO (single-sign-on):
See:
How do I put text on ProgressBar?
I have written a no blinking/flickering TextProgressBar
You can find the source code here: https://github.com/ukushu/TextProgressBar
WARNING: It's a little bit buggy! But still, I think it's better than another answers here. As I have no time for fixes, if you will do sth with them, please send me update by some way:) Thanks.
Samples:
How can I decrypt MySQL passwords
How can I decrypt MySQL passwords
You can't really because they are hashed and not encrypted.
Here's the essence of the PASSWORD function that current MySQL uses. You can execute it from the sql terminal:
mysql> SELECT SHA1(UNHEX(SHA1("password")));
+------------------------------------------+
| SHA1(UNHEX(SHA1("password"))) |
+------------------------------------------+
| 2470C0C06DEE42FD1618BB99005ADCA2EC9D1E19 |
+------------------------------------------+
1 row in set (0.00 sec)
How can I change or retrieve these?
If you are having trouble logging in on a debian or ubuntu system, first try this (thanks to tohuwawohu at https://askubuntu.com/questions/120718/cant-log-to-mysql):
$ sudo cat /etc/mysql/debian.conf | grep -i password
...
password: QWERTY12345...
Then, log in with the debian maintenance user:
$ mysql -u debian-sys-maint -p
password:
Finally, change the user's password:
mysql> UPDATE mysql.user SET Password=PASSWORD('new password') WHERE User='root';
mysql> FLUSH PRIVILEGES;
mysql> quit;
When I look in the PHPmyAdmin the passwords are encrypted
Related, if you need to dump the user database for the relevant information, try:
mysql> SELECT User,Host,Password FROM mysql.user;
+------------------+-----------+----------------------+
| User | Host | Password |
+------------------+-----------+----------------------+
| root | localhost | *0123456789ABCDEF... |
| root | 127.0.0.1 | *0123456789ABCDEF... |
| root | ::1 | *0123456789ABCDEF... |
| debian-sys-maint | localhost | *ABCDEF0123456789... |
+------------------+-----------+----------------------+
And yes, those passwords are NOT salted. So an attacker can prebuild the tables and apply them to all MySQL installations. In addition, the adversary can learn which users have the same passwords.
Needles to say, the folks at mySQL are not following best practices. John Steven did an excellent paper on Password Storage Best Practice at OWASP's Password Storage Cheat Sheet. In fairness to the MySQL folks, they may be doing it because of pain points in the architecture, design or implementation (I simply don't know).
If you use the PASSWORD and UPDATE commands and the change does not work, then see http://dev.mysql.com/doc/refman/5.0/en/resetting-permissions.html. Even though the page is named "resetting permissions", its really about how to change a password. (Its befuddling the MySQL password change procedure is so broken that you have to jump through the hoops, but it is what it is).
turn typescript object into json string
TS gets compiled to JS which then executed. Therefore you have access to all of the objects in the JS runtime. One of those objects is the JSON object. This contains the following methods:
JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string.JSON.stringify() method converts a JavaScript object or value to a JSON string.
Example:
_x000D_
_x000D_
const jsonString = '{"employee":{ "name":"John", "age":30, "city":"New York" }}';_x000D_
_x000D_
_x000D_
const JSobj = JSON.parse(jsonString);_x000D_
_x000D_
console.log(JSobj);_x000D_
console.log(typeof JSobj);_x000D_
_x000D_
const JSON_string = JSON.stringify(JSobj);_x000D_
_x000D_
console.log(JSON_string);_x000D_
console.log(typeof JSON_string);
_x000D_
_x000D_
_x000D_
.png){kind=link}