Programs & Examples On #Brk

brk() and sbrk() change the location of the program break, which defines the end of the process's data segment (i.e., the program break is the first location after the end of the uninitialized data segment).

Visual Studio 2017 errors on standard headers

I upgraded VS2017 from version 15.2 to 15.8. With version 15.8 here's what happened:

Project -> Properties -> General -> Windows SDK Version -> select 10.0.15063.0 no longer worked for me! I had to change it to 10.0.17134.0 and then everything built again. After the upgrade and without making this change, I was getting the same header file errors.

I would have submitted this as a comment on one of the other answers but I don't have enough reputation yet.

Why does C++ code for testing the Collatz conjecture run faster than hand-written assembly?

On a rather unrelated note: more performance hacks!

  • [the first «conjecture» has been finally debunked by @ShreevatsaR; removed]

  • When traversing the sequence, we can only get 3 possible cases in the 2-neighborhood of the current element N (shown first):

    1. [even] [odd]
    2. [odd] [even]
    3. [even] [even]

    To leap past these 2 elements means to compute (N >> 1) + N + 1, ((N << 1) + N + 1) >> 1 and N >> 2, respectively.

    Let`s prove that for both cases (1) and (2) it is possible to use the first formula, (N >> 1) + N + 1.

    Case (1) is obvious. Case (2) implies (N & 1) == 1, so if we assume (without loss of generality) that N is 2-bit long and its bits are ba from most- to least-significant, then a = 1, and the following holds:

    (N << 1) + N + 1:     (N >> 1) + N + 1:
    
            b10                    b1
             b1                     b
           +  1                   + 1
           ----                   ---
           bBb0                   bBb
    

    where B = !b. Right-shifting the first result gives us exactly what we want.

    Q.E.D.: (N & 1) == 1 ? (N >> 1) + N + 1 == ((N << 1) + N + 1) >> 1.

    As proven, we can traverse the sequence 2 elements at a time, using a single ternary operation. Another 2× time reduction.

The resulting algorithm looks like this:

uint64_t sequence(uint64_t size, uint64_t *path) {
    uint64_t n, i, c, maxi = 0, maxc = 0;

    for (n = i = (size - 1) | 1; i > 2; n = i -= 2) {
        c = 2;
        while ((n = ((n & 3)? (n >> 1) + n + 1 : (n >> 2))) > 2)
            c += 2;
        if (n == 2)
            c++;
        if (c > maxc) {
            maxi = i;
            maxc = c;
        }
    }
    *path = maxc;
    return maxi;
}

int main() {
    uint64_t maxi, maxc;

    maxi = sequence(1000000, &maxc);
    printf("%llu, %llu\n", maxi, maxc);
    return 0;
}

Here we compare n > 2 because the process may stop at 2 instead of 1 if the total length of the sequence is odd.

[EDIT:]

Let`s translate this into assembly!

MOV RCX, 1000000;



DEC RCX;
AND RCX, -2;
XOR RAX, RAX;
MOV RBX, RAX;

@main:
  XOR RSI, RSI;
  LEA RDI, [RCX + 1];

  @loop:
    ADD RSI, 2;
    LEA RDX, [RDI + RDI*2 + 2];
    SHR RDX, 1;
    SHRD RDI, RDI, 2;    ror rdi,2   would do the same thing
    CMOVL RDI, RDX;      Note that SHRD leaves OF = undefined with count>1, and this doesn't work on all CPUs.
    CMOVS RDI, RDX;
    CMP RDI, 2;
  JA @loop;

  LEA RDX, [RSI + 1];
  CMOVE RSI, RDX;

  CMP RAX, RSI;
  CMOVB RAX, RSI;
  CMOVB RBX, RCX;

  SUB RCX, 2;
JA @main;



MOV RDI, RCX;
ADD RCX, 10;
PUSH RDI;
PUSH RCX;

@itoa:
  XOR RDX, RDX;
  DIV RCX;
  ADD RDX, '0';
  PUSH RDX;
  TEST RAX, RAX;
JNE @itoa;

  PUSH RCX;
  LEA RAX, [RBX + 1];
  TEST RBX, RBX;
  MOV RBX, RDI;
JNE @itoa;

POP RCX;
INC RDI;
MOV RDX, RDI;

@outp:
  MOV RSI, RSP;
  MOV RAX, RDI;
  SYSCALL;
  POP RAX;
  TEST RAX, RAX;
JNE @outp;

LEA RAX, [RDI + 59];
DEC RDI;
SYSCALL;

Use these commands to compile:

nasm -f elf64 file.asm
ld -o file file.o

See the C and an improved/bugfixed version of the asm by Peter Cordes on Godbolt. (editor's note: Sorry for putting my stuff in your answer, but my answer hit the 30k char limit from Godbolt links + text!)

Docker - Container is not running

Container 79b3fa70b51d seems to only do an echo.

That means it starts, echo and then exits immediately.

The next docker exec command wouldn't find it running in order to attach itself to that container and execute any command: it is too late. The container has already exited.

The docker exec command runs a new command in a running container.

The command started using docker exec will only run while the container's primary process (PID 1) is running

error CS0234: The type or namespace name 'Script' does not exist in the namespace 'System.Web'

I had the same. Script been underlined. I added a reference to System.Web.Extensions. Thereafter the Script was no longer underlined. Hope this helps someone.

How to convert image into byte array and byte array to base64 String in android?

Try this:

// convert from bitmap to byte array
public byte[] getBytesFromBitmap(Bitmap bitmap) {
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bitmap.compress(CompressFormat.JPEG, 70, stream);
    return stream.toByteArray();
}

// get the base 64 string
String imgString = Base64.encodeToString(getBytesFromBitmap(someImg), 
                       Base64.NO_WRAP);

How is malloc() implemented internally?

Simplistically malloc and free work like this:

malloc provides access to a process's heap. The heap is a construct in the C core library (commonly libc) that allows objects to obtain exclusive access to some space on the process's heap.

Each allocation on the heap is called a heap cell. This typically consists of a header that hold information on the size of the cell as well as a pointer to the next heap cell. This makes a heap effectively a linked list.

When one starts a process, the heap contains a single cell that contains all the heap space assigned on startup. This cell exists on the heap's free list.

When one calls malloc, memory is taken from the large heap cell, which is returned by malloc. The rest is formed into a new heap cell that consists of all the rest of the memory.

When one frees memory, the heap cell is added to the end of the heap's free list. Subsequent malloc's walk the free list looking for a cell of suitable size.

As can be expected the heap can get fragmented and the heap manager may from time to time, try to merge adjacent heap cells.

When there is no memory left on the free list for a desired allocation, malloc calls brk or sbrk which are the system calls requesting more memory pages from the operating system.

Now there are a few modification to optimize heap operations.

  • For large memory allocations (typically > 512 bytes, the heap manager may go straight to the OS and allocate a full memory page.
  • The heap may specify a minimum size of allocation to prevent large amounts of fragmentation.
  • The heap may also divide itself into bins one for small allocations and one for larger allocations to make larger allocations quicker.
  • There are also clever mechanisms for optimizing multi-threaded heap allocation.

Viewing full output of PS command

Using the auxww flags, you will see the full path to output in both your terminal window and from shell scripts.

darragh@darraghserver ~ $uname -a
SunOS darraghserver 5.10 Generic_142901-13 i86pc i386 i86pc

darragh@darraghserver ~ $which ps
/usr/bin/ps<br>

darragh@darraghserver ~ $/usr/ucb/ps auxww | grep ps
darragh 13680  0.0  0.0 3872 3152 pts/1    O 14:39:32  0:00 /usr/ucb/ps -auxww
darragh 13681  0.0  0.0 1420  852 pts/1    S 14:39:32  0:00 grep ps

ps aux lists all processes executed by all users. See man ps for details. The ww flag sets unlimited width.

-w         Wide output. Use this option twice for unlimited width.
w          Wide output. Use this option twice for unlimited width.

I found the answer on the following blog:
http://www.snowfrog.net/2010/06/10/solaris-ps-output-truncated-at-80-columns/

Python subprocess.Popen "OSError: [Errno 12] Cannot allocate memory"

I continue to suspect that your customer/user has some kernel module or driver loaded which is interfering with the clone() system call (perhaps some obscure security enhancement, something like LIDS but more obscure?) or is somehow filling up some of the kernel data structures that are necessary for fork()/clone() to operate (process table, page tables, file descriptor tables, etc).

Here's the relevant portion of the fork(2) man page:

ERRORS
       EAGAIN fork() cannot allocate sufficient memory to copy the parent's page tables and allocate a task  structure  for  the
              child.

       EAGAIN It  was not possible to create a new process because the caller's RLIMIT_NPROC resource limit was encountered.  To
              exceed this limit, the process must have either the CAP_SYS_ADMIN or the CAP_SYS_RESOURCE capability.

       ENOMEM fork() failed to allocate the necessary kernel structures because memory is tight.

I suggest having the user try this after booting into a stock, generic kernel and with only a minimal set of modules and drivers loaded (minimum necessary to run your application/script). From there, assuming it works in that configuration, they can perform a binary search between that and the configuration which exhibits the issue. This is standard sysadmin troubleshooting 101.

The relevant line in your strace is:

clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb7f12708) = -1 ENOMEM (Cannot allocate memory)

... I know others have talked about swap and memory availability (and I would recommend that you set up at least a small swap partition, ironically even if it's on a RAM disk ... the code paths through the Linux kernel when it has even a tiny bit of swap available have been exercised far more extensively than those (exception handling paths) in which there is zero swap available.

However I suspect that this is still a red herring.

The fact that free is reporting 0 (ZERO) memory in use by the cache and buffers is very disturbing. I suspect that the free output ... and possibly your application issue here, are caused by some proprietary kernel module which is interfering with the memory allocation in some way.

According to the man pages for fork()/clone() the fork() system call should return EAGAIN if your call would cause a resource limit violation (RLIMIT_NPROC) ... however, it doesn't say if EAGAIN is to be returned by other RLIMIT* violations. In any event if your target/host has some sort of weird Vormetric or other security settings (or even if your process is running under some weird SELinux policy) then it might be causing this -ENOMEM failure.

It's pretty unlikely to be a normal run-of-the-mill Linux/UNIX issue. You've got something non-standard going on there.

What is the difference between `sorted(list)` vs `list.sort()`?

What is the difference between sorted(list) vs list.sort()?

  • list.sort mutates the list in-place & returns None
  • sorted takes any iterable & returns a new list, sorted.

sorted is equivalent to this Python implementation, but the CPython builtin function should run measurably faster as it is written in C:

def sorted(iterable, key=None):
    new_list = list(iterable)    # make a new list
    new_list.sort(key=key)       # sort it
    return new_list              # return it

when to use which?

  • Use list.sort when you do not wish to retain the original sort order (Thus you will be able to reuse the list in-place in memory.) and when you are the sole owner of the list (if the list is shared by other code and you mutate it, you could introduce bugs where that list is used.)
  • Use sorted when you want to retain the original sort order or when you wish to create a new list that only your local code owns.

Can a list's original positions be retrieved after list.sort()?

No - unless you made a copy yourself, that information is lost because the sort is done in-place.

"And which is faster? And how much faster?"

To illustrate the penalty of creating a new list, use the timeit module, here's our setup:

import timeit
setup = """
import random
lists = [list(range(10000)) for _ in range(1000)]  # list of lists
for l in lists:
    random.shuffle(l) # shuffle each list
shuffled_iter = iter(lists) # wrap as iterator so next() yields one at a time
"""

And here's our results for a list of randomly arranged 10000 integers, as we can see here, we've disproven an older list creation expense myth:

Python 2.7

>>> timeit.repeat("next(shuffled_iter).sort()", setup=setup, number = 1000)
[3.75168503401801, 3.7473005310166627, 3.753129180986434]
>>> timeit.repeat("sorted(next(shuffled_iter))", setup=setup, number = 1000)
[3.702025591977872, 3.709248117986135, 3.71071034099441]

Python 3

>>> timeit.repeat("next(shuffled_iter).sort()", setup=setup, number = 1000)
[2.797430992126465, 2.796825885772705, 2.7744789123535156]
>>> timeit.repeat("sorted(next(shuffled_iter))", setup=setup, number = 1000)
[2.675589084625244, 2.8019039630889893, 2.849375009536743]

After some feedback, I decided another test would be desirable with different characteristics. Here I provide the same randomly ordered list of 100,000 in length for each iteration 1,000 times.

import timeit
setup = """
import random
random.seed(0)
lst = list(range(100000))
random.shuffle(lst)
"""

I interpret this larger sort's difference coming from the copying mentioned by Martijn, but it does not dominate to the point stated in the older more popular answer here, here the increase in time is only about 10%

>>> timeit.repeat("lst[:].sort()", setup=setup, number = 10000)
[572.919036605, 573.1384446719999, 568.5923951]
>>> timeit.repeat("sorted(lst[:])", setup=setup, number = 10000)
[647.0584738299999, 653.4040515829997, 657.9457361929999]

I also ran the above on a much smaller sort, and saw that the new sorted copy version still takes about 2% longer running time on a sort of 1000 length.

Poke ran his own code as well, here's the code:

setup = '''
import random
random.seed(12122353453462456)
lst = list(range({length}))
random.shuffle(lst)
lists = [lst[:] for _ in range({repeats})]
it = iter(lists)
'''
t1 = 'l = next(it); l.sort()'
t2 = 'l = next(it); sorted(l)'
length = 10 ** 7
repeats = 10 ** 2
print(length, repeats)
for t in t1, t2:
    print(t)
    print(timeit(t, setup=setup.format(length=length, repeats=repeats), number=repeats))

He found for 1000000 length sort, (ran 100 times) a similar result, but only about a 5% increase in time, here's the output:

10000000 100
l = next(it); l.sort()
610.5015971539542
l = next(it); sorted(l)
646.7786222379655

Conclusion:

A large sized list being sorted with sorted making a copy will likely dominate differences, but the sorting itself dominates the operation, and organizing your code around these differences would be premature optimization. I would use sorted when I need a new sorted list of the data, and I would use list.sort when I need to sort a list in-place, and let that determine my usage.

How to parse XML in Bash?

Another command line tool is my new Xidel. It also supports XPath 2 and XQuery, contrary to the already mentioned xpath/xmlstarlet.

The title can be read like:

xidel xhtmlfile.xhtml -e /html/head/title > titleOfXHTMLPage.txt

And it also has a cool feature to export multiple variables to bash. For example

eval $(xidel xhtmlfile.xhtml -e 'title := //title, imgcount := count(//img)' --output-format bash )

sets $title to the title and $imgcount to the number of images in the file, which should be as flexible as parsing it directly in bash.

How to check if a file exists from inside a batch file

if exist <insert file name here> (
    rem file exists
) else (
    rem file doesn't exist
)

Or on a single line (if only a single action needs to occur):

if exist <insert file name here> <action>

for example, this opens notepad on autoexec.bat, if the file exists:

if exist c:\autoexec.bat notepad c:\autoexec.bat

Google Chrome "window.open" workaround?

As far as I can tell, chrome doesn't work properly if you are referencing localhost (say, you're developing a site locally)

This works:

var windowObjectReference;
var strWindowFeatures = "menubar=yes,location=yes,resizable=yes,scrollbars=yes,status=yes";

function openRequestedPopup() {
  windowObjectReference = window.open("http://www.cnn.com/", "CNN_WindowName", strWindowFeatures);
}

This does not work

var windowObjectReference;
var strWindowFeatures = "menubar=yes,location=yes,resizable=yes,scrollbars=yes,status=yes";

function openRequestedPopup() {
  windowObjectReference = window.open("http://localhost/webappFolder/MapViewer.do", "CNN_WindowName", strWindowFeatures);
}

This also does not work, when loaded from http://localhost/webappFolder/Landing.do

var windowObjectReference;
var strWindowFeatures = "menubar=yes,location=yes,resizable=yes,scrollbars=yes,status=yes";

function openRequestedPopup() {
  windowObjectReference = window.open("/webappFolder/MapViewer.do", "CNN_WindowName", strWindowFeatures);
}

Div Background Image Z-Index Issue

Set your header and footer position to "absolute" and that should do the trick. Hope it helps and good luck with your project!

VB.NET Switch Statement GoTo Case

Select Case parameter 
    Case "userID"
        ' does something here.
    Case "packageID"
        ' does something here.
    Case "mvrType" 
        If otherFactor Then 
            ' does something here.
        End If 
    Case Else 
        ' does some processing... 
        Exit Select 
End Select

Is there a reason for the goto? If it doesn't meet the if criterion, it will simply not perform the function and go to the next case.

Specify path to node_modules in package.json

In short: It is not possible, and as it seems won't ever be supported (see here https://github.com/npm/npm/issues/775).

There are some hacky work-arrounds with using the CLI or ENV-Variables (see the current selected answer), .npmrc-Config-Files or npm link - what they all have in common: They are never just project-specific, but always some kind of global Solutions.

For me, none of those solutions are really clean because contributors to your project always need to create some special configuration or have some special knowledge - they can't just npm install and it works.

So: Either you will have to put your package.json in the same directory where you want your node_modules installed, or live with the fact that they will always be in the root-dir of your project.

Google MAP API Uncaught TypeError: Cannot read property 'offsetWidth' of null

For others that might still be having this issue, even after trying the above recommendations, using an incorrect selector for your map canvas in the initialize function can cause this same issue as the function is trying to access something that doesn't exist. Double-check that your map Id matches in your initialize function and your HTML or this same error may be thrown.

In other words, make sure your IDs match up. ;)

How to turn off INFO logging in Spark?

Programmatic way

spark.sparkContext.setLogLevel("WARN")

Available Options

ERROR
WARN 
INFO 

Count Rows in Doctrine QueryBuilder

Adding the following method to your repository should allow you to call $repo->getCourseCount() from your Controller.

/**
 * @return array
 */
public function getCourseCount()
{
    $qb = $this->getEntityManager()->createQueryBuilder();

    $qb
        ->select('count(course.id)')
        ->from('CRMPicco\Component\Course\Model\Course', 'course')
    ;

    $query = $qb->getQuery();

    return $query->getSingleScalarResult();
}

How do I find the parent directory in C#?

string parent = System.IO.Directory.GetParent(str_directory).FullName;

See BOL

Delete dynamically-generated table row using jQuery

  $(document.body).on('click', 'buttontrash', function () { // <-- changes
    alert("aa");
   /$(this).closest('tr').remove();
    return false;
});

This works perfectly, take not of document.body

Using comma as list separator with AngularJS

If you are using ng-show to limit the values, the {{$last ? '' : ', '}} won`t work since it will still take into consideration all the values.Example

<div ng-repeat="x in records" ng-show="x.email == 1">{{x}}{{$last ? '' : ', '}}</div>

var myApp = angular.module("myApp", []);
myApp.controller("myCtrl", function($scope) {
  $scope.records = [
    {"email": "1"},
    {"email": "1"},
    {"email": "2"},
    {"email": "3"}
  ]
});

Results in adding a comma after the "last" value,since with ng-show it still takes into consideration all 4 values

{"email":"1"},
{"email":"1"},

One solution is to add a filter directly into ng-repeat

<div ng-repeat="x in records | filter: { email : '1' } ">{{x}}{{$last ? '' : ', '}}</div>

Results

{"email":"1"},
{"email":"1"}

How do I iterate through lines in an external file with shell?

cat names.txt|while read line; do
    echo "$line";
done

whitespaces in the path of windows filepath

path = r"C:\Users\mememe\Google Drive\Programs\Python\file.csv"

Closing the path in r"string" also solved this problem very well.

Writing .csv files from C++

There is nothing special about a CSV file. You can create them using a text editor by simply following the basic rules. The RFC 4180 (tools.ietf.org/html/rfc4180) accepted separator is the comma ',' not the semi-colon ';'. Programs like MS Excel expect a comma as a separator.

There are some programs that treat the comma as a decimal and the semi-colon as a separator, but these are technically outside of the "accepted" standard for CSV formatted files.

So, when creating a CSV you create your filestream and add your lines like so:

#include <iostream>
#include <fstream>
int main( int argc, char* argv[] )
{
      std::ofstream myfile;
      myfile.open ("example.csv");
      myfile << "This is the first cell in the first column.\n";
      myfile << "a,b,c,\n";
      myfile << "c,s,v,\n";
      myfile << "1,2,3.456\n";
      myfile << "semi;colon";
      myfile.close();
      return 0;
}

This will result in a CSV file that looks like this when opened in MS Excel:

Image of CSV file created with C++

How to get package name from anywhere?

Create a java module to be initially run when starting your app. This module would be extending the android Application class and would initialize any global app variables and also contain app-wide utility routines -

public class MyApplicationName extends Application {

    private final String PACKAGE_NAME = "com.mysite.myAppPackageName";

    public String getPackageName() { return PACKAGE_NAME; }
}

Of course, this could include logic to obtain the package name from the android system; however, the above is smaller, faster and cleaner code than obtaining it from android.

Be sure to place an entry in your AndroidManifest.xml file to tell android to run your application module before running any activities -

<application 
    android:name=".MyApplicationName" 
    ...
>

Then, to obtain the package name from any other module, enter

MyApp myApp = (MyApp) getApplicationContext();
String myPackage = myApp.getPackageName();

Using an application module also gives you a context for modules that need but don't have a context.

visual c++: #include files from other projects in the same solution

Try to avoid complete path references in the #include directive, whether they are absolute or relative. Instead, add the location of the other project's include folder in your project settings. Use only subfolders in path references when necessary. That way, it is easier to move things around without having to update your code.

C#: How to make pressing enter in a text box trigger a button, yet still allow shortcuts such as "Ctrl+A" to get through?

You can Use KeyPress instead of KeyUp or KeyDown its more efficient and here's how to handle

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (e.KeyChar == (char)Keys.Enter)
        {
            e.Handled = true;
            button1.PerformClick();
        }
    }

hope it works

Freeing up a TCP/IP port?

If you really want to kill a process immediately, you send it a KILL signal instead of a TERM signal (the latter a request to stop, the first will take effect immediately without any cleanup). It is easy to do:

kill -KILL <pid>

Be aware however that depending on the program you are stopping, its state may get badly corrupted when doing so. You normally only want to send a KILL signal when normal termination does not work. I'm wondering what the underlying problem is that you try to solve and whether killing is the right solution.

How to load up CSS files using Javascript?

In a modern browser you can use promise like this. Create a loader function with a promise in it:

function LoadCSS( cssURL ) {

    // 'cssURL' is the stylesheet's URL, i.e. /css/styles.css

    return new Promise( function( resolve, reject ) {

        var link = document.createElement( 'link' );

        link.rel  = 'stylesheet';

        link.href = cssURL;

        document.head.appendChild( link );

        link.onload = function() { 

            resolve(); 

            console.log( 'CSS has loaded!' ); 
        };
    } );
}

Then obviously you want something done after the CSS has loaded. You can call the function that needs to run after CSS has loaded like this:

LoadCSS( 'css/styles.css' ).then( function() {

    console.log( 'Another function is triggered after CSS had been loaded.' );

    return DoAfterCSSHasLoaded();
} );

Useful links if you want to understand in-depth how it works:

Official docs on promises

Useful guide to promises

A great intro video on promises

How can I use delay() with show() and hide() in Jquery

Why don't you try the fadeIn() instead of using a show() with delay(). I think what you are trying to do can be done with this. Here is the jQuery code for fadeIn and FadeOut() which also has inbuilt method for delaying the process.

$(document).ready(function(){
   $('element').click(function(){
      //effects take place in 3000ms
      $('element_to_hide').fadeOut(3000);
      $('element_to_show').fadeIn(3000);
   });
}

spark submit add multiple jars in classpath

I was trying to connect to mysql from the python code that was executed using spark-submit.

I was using HDP sandbox that was using Ambari. Tried lot of options such as --jars, --driver-class-path, etc, but none worked.

Solution

Copy the jar in /usr/local/miniconda/lib/python2.7/site-packages/pyspark/jars/

As of now I'm not sure if it's a solution or a quick hack, but since I'm working on POC so it kind of works for me.

How to convert image to byte array

Another way to get Byte array from image path is

byte[] imgdata = System.IO.File.ReadAllBytes(HttpContext.Current.Server.MapPath(path));

Laravel 5.4 ‘cross-env’ Is Not Recognized as an Internal or External Command

Just npm install --save-dev cross-env in the root directory of your project.

How to Convert string "07:35" (HH:MM) to TimeSpan

Try

var ts = TimeSpan.Parse(stringTime);

With a newer .NET you also have

TimeSpan ts;

if(!TimeSpan.TryParse(stringTime, out ts)){
     // throw exception or whatnot
}
// ts now has a valid format

This is the general idiom for parsing strings in .NET with the first version handling erroneous string by throwing FormatException and the latter letting the Boolean TryParse give you the information directly.

How to check if element in groovy array/hash/collection/list?

You can also use matches with regular expression like this:

boolean bool = List.matches("(?i).*SOME STRING HERE.*")

How to merge a Series and DataFrame

You can easily set a pandas.DataFrame column to a constant. This constant can be an int such as in your example. If the column you specify isn't in the df, then pandas will create a new column with the name you specify. So after your dataframe is constructed, (from your question):

df = pd.DataFrame({'a':[np.nan, 2, 3], 'b':[4, 5, 6]}, index=[3, 5, 6])

You can just run:

df['s1'], df['s2'] = 5, 6

You could write a loop or comprehension to make it do this for all the elements in a list of tuples, or keys and values in a dictionary depending on how you have your real data stored.

How to get unique device hardware id in Android?

Update: 19 -11-2019

The below answer is no more relevant to present day.

So for any one looking for answers you should look at the documentation linked below

https://developer.android.com/training/articles/user-data-ids


Old Answer - Not relevant now. You check this blog in the link below

http://android-developers.blogspot.in/2011/03/identifying-app-installations.html

ANDROID_ID

import android.provider.Settings.Secure;

private String android_id = Secure.getString(getContext().getContentResolver(),
                                                    Secure.ANDROID_ID); 

The above is from the link @ Is there a unique Android device ID?

More specifically, Settings.Secure.ANDROID_ID. This is a 64-bit quantity that is generated and stored when the device first boots. It is reset when the device is wiped.

ANDROID_ID seems a good choice for a unique device identifier. There are downsides: First, it is not 100% reliable on releases of Android prior to 2.2 (“Froyo”). Also, there has been at least one widely-observed bug in a popular handset from a major manufacturer, where every instance has the same ANDROID_ID.

The below solution is not a good one coz the value survives device wipes (“Factory resets”) and thus you could end up making a nasty mistake when one of your customers wipes their device and passes it on to another person.

You get the imei number of the device using the below

  TelephonyManager telephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
  telephonyManager.getDeviceId();

http://developer.android.com/reference/android/telephony/TelephonyManager.html#getDeviceId%28%29

Add this is manifest

<uses-permission android:name="android.permission.READ_PHONE_STATE"/>

Spring-Boot: How do I set JDBC pool properties like maximum number of connections?

It turns out setting these configuration properties is pretty straight forward, but the official documentation is more general so it might be hard to find when searching specifically for connection pool configuration information.

To set the maximum pool size for tomcat-jdbc, set this property in your .properties or .yml file:

spring.datasource.maxActive=5

You can also use the following if you prefer:

spring.datasource.max-active=5

You can set any connection pool property you want this way. Here is a complete list of properties supported by tomcat-jdbc.

To understand how this works more generally you need to dig into the Spring-Boot code a bit.

Spring-Boot constructs the DataSource like this (see here, line 102):

@ConfigurationProperties(prefix = DataSourceAutoConfiguration.CONFIGURATION_PREFIX)
@Bean
public DataSource dataSource() {
    DataSourceBuilder factory = DataSourceBuilder
            .create(this.properties.getClassLoader())
            .driverClassName(this.properties.getDriverClassName())
            .url(this.properties.getUrl())
            .username(this.properties.getUsername())
            .password(this.properties.getPassword());
    return factory.build();
}

The DataSourceBuilder is responsible for figuring out which pooling library to use, by checking for each of a series of know classes on the classpath. It then constructs the DataSource and returns it to the dataSource() function.

At this point, magic kicks in using @ConfigurationProperties. This annotation tells Spring to look for properties with prefix CONFIGURATION_PREFIX (which is spring.datasource). For each property that starts with that prefix, Spring will try to call the setter on the DataSource with that property.

The Tomcat DataSource is an extension of DataSourceProxy, which has the method setMaxActive().

And that's how your spring.datasource.maxActive=5 gets applied correctly!

What about other connection pools

I haven't tried, but if you are using one of the other Spring-Boot supported connection pools (currently HikariCP or Commons DBCP) you should be able to set the properties the same way, but you'll need to look at the project documentation to know what is available.

A reference to the dll could not be added

For anyone else looking for help on this matter, or experiencing a FileNotFoundException or a FirstChanceException, check out my answer here:

A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.ni.dll - windows phone

In general you must be absolutely certain that you are meeting all of the requirements for making the reference - I know it's the obvious answer, but you're probably overlooking a relatively simple requirement.

php mail setup in xampp

XAMPP should have come with a "fake" sendmail program. In that case, you can use sendmail as well:

[mail function]
; For Win32 only.
; http://php.net/smtp
;SMTP = localhost
; http://php.net/smtp-port
;smtp_port = 25

; For Win32 only.
; http://php.net/sendmail-from
;sendmail_from = [email protected]

; For Unix only.  You may supply arguments as well (default: "sendmail -t -i").
; http://php.net/sendmail-path
sendmail_path = "C:/xampp/sendmail/sendmail.exe -t -i"

Sendmail should have a sendmail.ini with it; it should be configured as so:

# Example for a user configuration file

# Set default values for all following accounts.
defaults
logfile "C:\xampp\sendmail\sendmail.log"

# Mercury
#account Mercury
#host localhost
#from postmaster@localhost
#auth off

# A freemail service example
account ACCOUNTNAME_HERE
tls on
tls_certcheck off
host smtp.gmail.com
from EMAIL_HERE
auth on
user EMAIL_HERE
password PASSWORD_HERE

# Set a default account
account default : ACCOUNTNAME_HERE

Of course, replace ACCOUNTNAME_HERE with an arbitrary account name, replace EMAIL_HERE with a valid email (such as a Gmail or Hotmail), and replace PASSWORD_HERE with the password to your email. Now, you should be able to send mail. Remember to restart Apache (from the control panel or the batch files) to allow the changes to PHP to work.

Shortest distance between a point and a line segment

Here's the code I ended up writing. This code assumes that a point is defined in the form of {x:5, y:7}. Note that this is not the absolute most efficient way, but it's the simplest and easiest-to-understand code that I could come up with.

// a, b, and c in the code below are all points

function distance(a, b)
{
    var dx = a.x - b.x;
    var dy = a.y - b.y;
    return Math.sqrt(dx*dx + dy*dy);
}

function Segment(a, b)
{
    var ab = {
        x: b.x - a.x,
        y: b.y - a.y
    };
    var length = distance(a, b);

    function cross(c) {
        return ab.x * (c.y-a.y) - ab.y * (c.x-a.x);
    };

    this.distanceFrom = function(c) {
        return Math.min(distance(a,c),
                        distance(b,c),
                        Math.abs(cross(c) / length));
    };
}

How to get value from form field in django framework?

Take your pick:

def my_view(request):

    if request.method == 'POST':
        print request.POST.get('my_field')

        form = MyForm(request.POST)

        print form['my_field'].value()
        print form.data['my_field']

        if form.is_valid():

            print form.cleaned_data['my_field']
            print form.instance.my_field

            form.save()
            print form.instance.id  # now this one can access id/pk

Note: the field is accessed as soon as it's available.

Setting onClickListener for the Drawable right of an EditText

public class CustomEditText extends androidx.appcompat.widget.AppCompatEditText {

    private Drawable drawableRight;
    private Drawable drawableLeft;
    private Drawable drawableTop;
    private Drawable drawableBottom;

    int actionX, actionY;

    private DrawableClickListener clickListener;

    public CustomEditText (Context context, AttributeSet attrs) {
        super(context, attrs);
        // this Contructure required when you are using this view in xml
    }

    public CustomEditText(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);        
    }

    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
    }

    @Override
    public void setCompoundDrawables(Drawable left, Drawable top,
            Drawable right, Drawable bottom) {
        if (left != null) {
            drawableLeft = left;
        }
        if (right != null) {
            drawableRight = right;
        }
        if (top != null) {
            drawableTop = top;
        }
        if (bottom != null) {
            drawableBottom = bottom;
        }
        super.setCompoundDrawables(left, top, right, bottom);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Rect bounds;
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            actionX = (int) event.getX();
            actionY = (int) event.getY();
            if (drawableBottom != null
                    && drawableBottom.getBounds().contains(actionX, actionY)) {
                clickListener.onClick(DrawablePosition.BOTTOM);
                return super.onTouchEvent(event);
            }

            if (drawableTop != null
                    && drawableTop.getBounds().contains(actionX, actionY)) {
                clickListener.onClick(DrawablePosition.TOP);
                return super.onTouchEvent(event);
            }

            // this works for left since container shares 0,0 origin with bounds
            if (drawableLeft != null) {
                bounds = null;
                bounds = drawableLeft.getBounds();

                int x, y;
                int extraTapArea = (int) (13 * getResources().getDisplayMetrics().density  + 0.5);

                x = actionX;
                y = actionY;

                if (!bounds.contains(actionX, actionY)) {
                    /** Gives the +20 area for tapping. */
                    x = (int) (actionX - extraTapArea);
                    y = (int) (actionY - extraTapArea);

                    if (x <= 0)
                        x = actionX;
                    if (y <= 0)
                        y = actionY;

                    /** Creates square from the smallest value */
                    if (x < y) {
                        y = x;
                    }
                }

                if (bounds.contains(x, y) && clickListener != null) {
                    clickListener
                            .onClick(DrawableClickListener.DrawablePosition.LEFT);
                    event.setAction(MotionEvent.ACTION_CANCEL);
                    return false;

                }
            }

            if (drawableRight != null) {

                bounds = null;
                bounds = drawableRight.getBounds();

                int x, y;
                int extraTapArea = 13;

                /**
                 * IF USER CLICKS JUST OUT SIDE THE RECTANGLE OF THE DRAWABLE
                 * THAN ADD X AND SUBTRACT THE Y WITH SOME VALUE SO THAT AFTER
                 * CALCULATING X AND Y CO-ORDINATE LIES INTO THE DRAWBABLE
                 * BOUND. - this process help to increase the tappable area of
                 * the rectangle.
                 */
                x = (int) (actionX + extraTapArea);
                y = (int) (actionY - extraTapArea);

                /**Since this is right drawable subtract the value of x from the width 
                * of view. so that width - tappedarea will result in x co-ordinate in drawable bound. 
                */
                x = getWidth() - x;
                
                 /*x can be negative if user taps at x co-ordinate just near the width.
                 * e.g views width = 300 and user taps 290. Then as per previous calculation
                 * 290 + 13 = 303. So subtract X from getWidth() will result in negative value.
                 * So to avoid this add the value previous added when x goes negative.
                 */
                 
                if(x <= 0){
                    x += extraTapArea;
                }
                
                 /* If result after calculating for extra tappable area is negative.
                 * assign the original value so that after subtracting
                 * extratapping area value doesn't go into negative value.
                 */               
                 
                if (y <= 0)
                    y = actionY;                

                /**If drawble bounds contains the x and y points then move ahead.*/
                if (bounds.contains(x, y) && clickListener != null) {
                    clickListener
                            .onClick(DrawableClickListener.DrawablePosition.RIGHT);
                    event.setAction(MotionEvent.ACTION_CANCEL);
                    return false;
                }
                return super.onTouchEvent(event);
            }           

        }
        return super.onTouchEvent(event);
    }

    @Override
    protected void finalize() throws Throwable {
        drawableRight = null;
        drawableBottom = null;
        drawableLeft = null;
        drawableTop = null;
        super.finalize();
    }

    public void setDrawableClickListener(DrawableClickListener listener) {
        this.clickListener = listener;
    }

}

Also Create an Interface with

public interface DrawableClickListener {

    public static enum DrawablePosition { TOP, BOTTOM, LEFT, RIGHT };
    public void onClick(DrawablePosition target); 
    }

Still if u need any help, comment

Also set the drawableClickListener on the view in activity file.

editText.setDrawableClickListener(new DrawableClickListener() {
        
         
        public void onClick(DrawablePosition target) {
            switch (target) {
            case LEFT:
                //Do something here
                break;

            default:
                break;
            }
        }
        
    });

Can a background image be larger than the div itself?

No, you can't.

But as a solid workaround, I would suggest to classify that first div as position:relative and use div::before to create an underlying element containing your image. Classified as position:absolute you can move it anywhere relative to your initial div.

Don't forget to add content to that new element. Here's some example:

div {
  position: relative;
}    

div::before {
  content: ""; /* empty but necessary */
  position: absolute;
  background: ...
}

Note: if you want it to be 'on top' of the parent div, use div::after instead.

How to check that Request.QueryString has a specific value or not in ASP.NET?

You can also try:

if (!Request.QueryString.AllKeys.Contains("aspxerrorpath"))
   return;

How do you change the server header returned by nginx?

Are you asking about the Server header value in the response? You can try changing that with an add_header directive, but I'm not sure if it'll work. http://wiki.codemongers.com/NginxHttpHeadersModule

Switch/toggle div (jQuery)

Since one div is initially hidden, you can simply call toggle for both divs:

<a href="javascript:void(0);" id="forgot-password">forgot password?</a>
<div id="login-form">login form</div>

<div id="recover-password" style="display:none;">recover password</div>

<script type="text/javascript">
$(function(){
  $('#forgot-password').click(function(){
     $('#login-form').toggle();
     $('#recover-password').toggle(); 
  });
});
</script>

YAML equivalent of array of objects in JSON

Great answer above. Another way is to use the great yaml jq wrapper tool, yq at https://github.com/kislyuk/yq

Save your JSON example to a file, say ex.json and then

yq -y '.' ex.json

AAPL:
- shares: -75.088
  date: 11/27/2015
- shares: 75.088
  date: 11/26/2015

What is the Python equivalent for a case/switch statement?

While the official docs are happy not to provide switch, I have seen a solution using dictionaries.

For example:

# define the function blocks
def zero():
    print "You typed zero.\n"

def sqr():
    print "n is a perfect square\n"

def even():
    print "n is an even number\n"

def prime():
    print "n is a prime number\n"

# map the inputs to the function blocks
options = {0 : zero,
           1 : sqr,
           4 : sqr,
           9 : sqr,
           2 : even,
           3 : prime,
           5 : prime,
           7 : prime,
}

Then the equivalent switch block is invoked:

options[num]()

This begins to fall apart if you heavily depend on fall through.

Linker Error C++ "undefined reference "

Your header file Hash.h declares "what class hash should look like", but not its implementation, which is (presumably) in some other source file we'll call Hash.cpp. By including the header in your main file, the compiler is informed of the description of class Hash when compiling the file, but not how class Hash actually works. When the linker tries to create the entire program, it then complains that the implementation (toHash::insert(int, char)) cannot be found.

The solution is to link all the files together when creating the actual program binary. When using the g++ frontend, you can do this by specifying all the source files together on the command line. For example:

g++ -o main Hash.cpp main.cpp

will create the main program called "main".

Psql list all tables

To see the public tables you can do

list tables

\dt

list table, view, and access privileges

\dp or \z

or just the table names

select table_name from information_schema.tables where table_schema = 'public';

How to securely save username/password (local)?

DPAPI is just for this purpose. Use DPAPI to encrypt the password the first time the user enters is, store it in a secure location (User's registry, User's application data directory, are some choices). Whenever the app is launched, check the location to see if your key exists, if it does use DPAPI to decrypt it and allow access, otherwise deny it.

How do I use CREATE OR REPLACE?

'Create or replace table' is not possible. As others stated, you can write a procedure and/or use begin execute immediately (...). Because I don't see an answer with how to (re)create the table, I putted a script as an answer.

PS: in line of what jeffrey-kemp mentioned: this beneath script will NOT save data that is already present in the table you are going to drop. Because of the risk of loosing data, at our company it is only allowed to alter existing tables on the production environment, and it is not allowed to drop tables. By using the drop table statement, sooner or later you will get the company police standing at your desk.

--Create the table 'A_TABLE_X', and drop the table in case it already is present
BEGIN
EXECUTE IMMEDIATE 
'
CREATE TABLE A_TABLE_X
(
COLUMN1 NUMBER(15,0),
COLUMN2  VARCHAR2(255 CHAR),
COLUMN3  VARCHAR2(255 CHAR)
)';

EXCEPTION
WHEN OTHERS THEN
  IF SQLCODE != -955 THEN -- ORA-00955: object name already used
     EXECUTE IMMEDIATE 'DROP TABLE A_TABLE_X';
  END IF;
END;

SQLAlchemy ORDER BY DESCENDING?

Complementary at @Radu answer, As in SQL, you can add the table name in the parameter if you have many table with the same attribute.

.order_by("TableName.name desc")

How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

It's an ancient piece of code that I've used a few times:

if (parent.location.href == self.location.href) {
    window.location.href = 'https://www.facebook.com/pagename?v=app_1357902468';
}

Java program to get the current date without timestamp

You could always use apache commons' DateUtils class. It has the static method isSameDay() which "Checks if two date objects are on the same day ignoring time."

static boolean isSameDay(Date date1, Date date2) 

Calculate the execution time of a method

Following this Microsoft Doc:

using System;
using System.Diagnostics;
using System.Threading;
class Program
{
    static void Main(string[] args)
    {
        Stopwatch stopWatch = new Stopwatch();
        stopWatch.Start();
        Thread.Sleep(10000);
        stopWatch.Stop();
        // Get the elapsed time as a TimeSpan value.
        TimeSpan ts = stopWatch.Elapsed;

        // Format and display the TimeSpan value.
        string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
            ts.Hours, ts.Minutes, ts.Seconds,
            ts.Milliseconds / 10);
        Console.WriteLine("RunTime " + elapsedTime);
    }
}

Output: RunTime 00:00:09.94

Can I define a class name on paragraph using Markdown?

Dupe: How do I set an HTML class attribute in Markdown?


Natively? No. But...

No, Markdown's syntax can't. You can set ID values with Markdown Extra through.

You can use regular HTML if you like, and add the attribute markdown="1" to continue markdown-conversion within the HTML element. This requires Markdown Extra though.

<p class='specialParagraph' markdown='1'>
**Another paragraph** which allows *Markdown* within it.
</p>

Possible Solution: (Untested and intended for <blockquote>)

I found the following online:

Function

function _DoBlockQuotes_callback($matches) {

    ...cut...

    //add id and class details...
    $id = $class = '';
    if(preg_match_all('/\{(?:([#.][-_:a-zA-Z0-9 ]+)+)\}/',$bq,$matches)) {
        foreach ($matches[1] as $match) {
            if($match[0]=='#') $type = 'id';
            else $type = 'class';
            ${$type} = ' '.$type.'="'.trim($match,'.# ').'"';
        }
        foreach ($matches[0] as $match) {
            $bq = str_replace($match,'',$bq);
        }
    }

    return _HashBlock(
        "<blockquote{$id}{$class}>\n$bq\n</blockquote>"
    ) . "\n\n";
}

Markdown

>{.className}{#id}This is the blockquote

Result

<blockquote id="id" class="className">
    <p>This is the blockquote</p>
</blockquote>

JavaScript check if value is only undefined, null or false

Well, you can always "give up" :)

function b(val){
    return (val==null || val===false);
}

Delete column from pandas DataFrame

Use:

columns = ['Col1', 'Col2', ...]
df.drop(columns, inplace=True, axis=1)

This will delete one or more columns in-place. Note that inplace=True was added in pandas v0.13 and won't work on older versions. You'd have to assign the result back in that case:

df = df.drop(columns, axis=1)

Reading integers from binary file in Python

As you are reading the binary file, you need to unpack it into a integer, so use struct module for that

import struct
fin = open("hi.bmp", "rb")
firm = fin.read(2)  
file_size, = struct.unpack("i",fin.read(4))

$_POST not working. "Notice: Undefined index: username..."

first of all,

be sure that there is a post

if(isset($_POST['username'])) { 
    // check if the username has been set
}

second, and most importantly, sanitize the data, meaning that

$query = "SELECT password FROM users WHERE username='".$_POST['username']."'";

is deadly dangerous, instead use

$query = "SELECT password FROM users WHERE username='".mysql_real_escape_string($_POST['username'])."'";

and please research the subject sql injection

How to link a folder with an existing Heroku app

I've my project in github and heroku, for upload an heroku use :

heroku git:remote -a <project>

The doc it is:

https://devcenter.heroku.com/articles/git

Using getResources() in non-activity class

In simple class declare context and get data from file from res folder

public class FileData
{
      private Context context;

        public FileData(Context current){
            this.context = current;
        }
        void  getData()
        {
        InputStream in = context.getResources().openRawResource(R.raw.file11);
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        //write stuff to get Data

        }
}

In the activity class declare like this

public class MainActivity extends AppCompatActivity 
{
 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        FileData fileData=new FileData(this);
     }

}

Split string into list in jinja?

After coming back to my own question after 5 year and seeing so many people found this useful, a little update.

A string variable can be split into a list by using the split function (it can contain similar values, set is for the assignment) . I haven't found this function in the official documentation but it works similar to normal Python. The items can be called via an index, used in a loop or like Dave suggested if you know the values, it can set variables like a tuple.

{% set list1 = variable1.split(';') %}
The grass is {{ list1[0] }} and the boat is {{ list1[1] }}

or

{% set list1 = variable1.split(';') %}
{% for item in list1 %}
    <p>{{ item }}<p/>
{% endfor %} 

or

{% set item1, item2 = variable1.split(';') %}
The grass is {{ item1 }} and the boat is {{ item2 }}

Why doesn't Python have a sign function?

You dont need one, you can just use:

if not number == 0:
    sig = number/abs(number)
else:
    sig = 0

Or create a function as described by others:

sign = lambda x: bool(x > 0) - bool(x < 0)

def sign(x):
    return bool(x > 0) - bool(x < 0)

Adding a HTTP header to the Angular HttpClient doesn't send the header, why?

I was struggling with this as well. I used an interceptor, it captures the response headers, then clone the headers(since headers are immutable objects) and then sends the modified headers. https://angular.io/guide/http#intercepting-requests-and-responses

How to mark-up phone numbers?

this worked for me:

1.make a standards compliant link:

        <a href="tel:1500100900">

2.replace it when mobile browser is not detected, for skype:

$("a.phone")
    .each(function()
{ 
  this.href = this.href.replace(/^tel/, 
     "callto");
});

Selecting link to replace via class seems more efficient. Of course it works only on anchors with .phone class.

I have put it in function if( !isMobile() ) { ... so it triggers only when detects desktop browser. But this one is problably obsolete...

function isMobile() {
    return (
        ( navigator.userAgent.indexOf( "iPhone" ) > -1 ) ||
        ( navigator.userAgent.indexOf( "iPod" ) > -1 ) ||
        ( navigator.userAgent.indexOf( "iPad" ) > -1 ) ||
        ( navigator.userAgent.indexOf( "Android" ) > -1 ) ||
        ( navigator.userAgent.indexOf( "webOS" ) > -1 )
    );
}

How to make Firefox headless programmatically in Selenium with Python?

The first answer does't work anymore.

This worked for me:

from selenium.webdriver.firefox.options import Options as FirefoxOptions
from selenium import webdriver

options = FirefoxOptions()
options.add_argument("--headless")
driver = webdriver.Firefox(options=options)
driver.get("http://google.com")

'sudo gem install' or 'gem install' and gem locations

Installing Ruby gems on a Mac is a common source of confusion and frustration. Unfortunately, most solutions are incomplete, outdated, and provide bad advice. I'm glad the accepted answer here says to NOT use sudo, which you should never need to do, especially if you don't understand what it does. While I used RVM years ago, I would recommend chruby in 2020.

Some of the other answers here provide alternative options for installing gems, but they don't mention the limitations of those solutions. What's missing is an explanation and comparison of the various options and why you might choose one over the other. I've attempted to cover most common scenarios in my definitive guide to installing Ruby gems on a Mac.

Check if string begins with something?

Have a look at JavaScript substring() method.

Integrate ZXing in Android Studio

I was integrating ZXING into an Android application and there were no good sources for the input all over, I will give you a hint on what worked for me - because it turned out to be very easy.

There is a real handy git repository that provides the zxing android library project as an AAR archive.

All you have to do is add this to your build.gradle

repositories {
    jcenter()
}

dependencies {
    implementation 'com.journeyapps:zxing-android-embedded:3.0.2@aar'
    implementation 'com.google.zxing:core:3.2.0'
}

and Gradle does all the magic to compile the code and makes it accessible in your app.

To start the Scanner afterwards, use this class/method: From the Activity:

new IntentIntegrator(this).initiateScan(); // `this` is the current Activity

From a Fragment:

IntentIntegrator.forFragment(this).initiateScan(); // `this` is the current Fragment
// If you're using the support library, use IntentIntegrator.forSupportFragment(this) instead.

There are several customizing options:

IntentIntegrator integrator = new IntentIntegrator(this);
integrator.setDesiredBarcodeFormats(IntentIntegrator.ONE_D_CODE_TYPES);
integrator.setPrompt("Scan a barcode");
integrator.setCameraId(0);  // Use a specific camera of the device
integrator.setBeepEnabled(false);
integrator.setBarcodeImageEnabled(true);
integrator.initiateScan();

They have a sample-project and are providing several integration examples:

If you already visited the link you going to see that I just copy&pasted the code from the git README. If not, go there to get some more insight and code examples.

TypeError: no implicit conversion of Symbol into Integer

You probably meant this:

require 'active_support/core_ext' # for titleize

myHash = {company_name:"MyCompany", street:"Mainstreet", postcode:"1234", city:"MyCity", free_seats:"3"}

def cleanup string
  string.titleize
end

def format(hash)
  output = {}
  output[:company_name] = cleanup(hash[:company_name])
  output[:street] = cleanup(hash[:street])
  output
end

format(myHash) # => {:company_name=>"My Company", :street=>"Mainstreet"}

Please read documentation on Hash#each

An internal error occurred during: "Updating Maven Project". Unsupported IClasspathEntry kind=4

Your command line mvn eclipse project generator may not be the same version as that of your eclipse, and eclipse doesn't understand for your command line tool is generating. Just use eclipse's in this case:

  • remove the project from eclipse (including all modules if multi-module)
  • run: rm -rf .settings/ .project .classpath to delete eclipse project files, also from modules
  • import your project as an existing maven project

How to disable submit button once it has been clicked?

You need to disable the button in the onsubmit event of the <form>:

<form action='/' method='POST' onsubmit='disableButton()'>
    <input name='txt' type='text' required />
    <button id='btn' type='submit'>Post</button>
</form>

<script>
    function disableButton() {
        var btn = document.getElementById('btn');
        btn.disabled = true;
        btn.innerText = 'Posting...'
    }
</script>

Note: this way if you have a form element which has the required attribute will work.

What is the difference between HTML tags <div> and <span>?

The real important difference is already mentioned in Chris' answer. However, the implications won't be obvious for everybody.

As an inline element, <span> may only contain other inline elements. The following code is therefore wrong:

<span><p>This is a paragraph</p></span>

The above code isn't valid. To wrap block-level elements, another block-level element must be used (such as <div>). On the other hand, <div> may only be used in places where block-level elements are legal.

Furthermore, these rules are fixed in (X)HTML and they are not altered by the presence of CSS rules! So the following codes are also wrong!

<span style="display: block"><p>Still wrong</p></span>
<span><p style="display: inline">Just as wrong</p></span>

What is the best method to merge two PHP objects?

Here is a function that will flatten an object or array. Use this only if you are sure your keys are unique. If you have keys with the same name they will be overwritten. You will need to place this in a class and replace "Functions" with the name of your class. Enjoy...

function flatten($array, $preserve_keys=1, &$out = array(), $isobject=0) {
        # Flatten a multidimensional array to one dimension, optionally preserving keys.
        #
        # $array - the array to flatten
        # $preserve_keys - 0 (default) to not preserve keys, 1 to preserve string keys only, 2 to preserve all keys
        # $out - internal use argument for recursion
        # $isobject - is internally set in order to remember if we're using an object or array
        if(is_array($array) || $isobject==1)
        foreach($array as $key => $child)
            if(is_array($child))
                $out = Functions::flatten($child, $preserve_keys, $out, 1); // replace "Functions" with the name of your class
            elseif($preserve_keys + is_string($key) > 1)
                $out[$key] = $child;
            else
                $out[] = $child;

        if(is_object($array) || $isobject==2)
        if(!is_object($out)){$out = new stdClass();}
        foreach($array as $key => $child)
            if(is_object($child))
                $out = Functions::flatten($child, $preserve_keys, $out, 2); // replace "Functions" with the name of your class
            elseif($preserve_keys + is_string($key) > 1)
                $out->$key = $child;
            else
                $out = $child;

        return $out;
}

Angular 2: How to write a for loop, not a foreach loop

You could dynamically generate an array of however time you wanted to render <li>Something</li>, and then do ngFor over that collection. Also you could take use of index of current element too.

Markup

<ul>
   <li *ngFor="let item of createRange(5); let currentElementIndex=index+1">
      {{currentElementIndex}} Something
   </li>
</ul>

Code

createRange(number){
  var items: number[] = [];
  for(var i = 1; i <= number; i++){
     items.push(i);
  }
  return items;
}

Demo Here

Under the hood angular de-sugared this *ngFor syntax to ng-template version.

<ul>
    <ng-template ngFor let-item [ngForOf]="createRange(5)" let-currentElementIndex="(index + 1)" [ngForTrackBy]="trackByFn">
      {{currentElementIndex}} Something
    </ng-template>
</ul>

Sorting rows in a data table

 table.DefaultView.Sort = "[occr] DESC";

How do I get current date/time on the Windows command line in a suitable format for usage in a file/folder name?

This isn't really briefer but might be a more flexible way (credit):

FOR /F "TOKENS=1* DELIMS= " %%A IN ('DATE/T') DO SET CDATE=%%B
FOR /F "TOKENS=1,2 eol=/ DELIMS=/ " %%A IN ('DATE/T') DO SET mm=%%B
FOR /F "TOKENS=1,2 DELIMS=/ eol=/" %%A IN ('echo %CDATE%') DO SET dd=%%B
FOR /F "TOKENS=2,3 DELIMS=/ " %%A IN ('echo %CDATE%') DO SET yyyy=%%B
SET date=%mm%%dd%%yyyy%

How to display a loading screen while site content loads

First, set up a loading image in a div. Next, get the div element. Then, set a function that edits the css to make the visibility to "hidden". Now, in the <body>, put the onload to the function name.

Selenium and xpath: finding a div with a class/id and verifying text inside

To account for leading and trailing whitespace, you probably want to use normalize-space()

//div[contains(@class, 'Caption') and normalize-space(.)='Model saved']

and

//div[@id='alertLabel' and normalize-space(.)='Save to server successful']

Note that //div[contains(@class, 'Caption') and normalize-space(.//text())='Model saved'] also works.

How do I bind the enter key to a function in tkinter?

Another alternative is to use a lambda:

ent.bind("<Return>", (lambda event: name_of_function()))

Full code:

from tkinter import *
from tkinter.messagebox import showinfo

def reply(name):
    showinfo(title="Reply", message = "Hello %s!" % name)


top = Tk()
top.title("Echo")
top.iconbitmap("Iconshock-Folder-Gallery.ico")

Label(top, text="Enter your name:").pack(side=TOP)
ent = Entry(top)
ent.bind("<Return>", (lambda event: reply(ent.get())))
ent.pack(side=TOP)
btn = Button(top,text="Submit", command=(lambda: reply(ent.get())))
btn.pack(side=LEFT)

top.mainloop()

As you can see, creating a lambda function with an unused variable "event" solves the problem.

Overlay with spinner

#overlay {
    position: fixed;
    width: 100%;
    height: 100%;
    background: black url(spinner.gif) center center no-repeat;
    opacity: .5;
}

it's better to use rgba color instead of opacity to prevent applying alpha to spinner image.

background: rgba(0,0,0,.5) url(spinner.gif) center center no-repeat;

Passing Arrays to Function in C++

The question has already been answered, but I thought I'd add an answer with more precise terminology and references to the C++ standard.

Two things are going on here, array parameters being adjusted to pointer parameters, and array arguments being converted to pointer arguments. These are two quite different mechanisms, the first is an adjustment to the actual type of the parameter, whereas the other is a standard conversion which introduces a temporary pointer to the first element.

Adjustments to your function declaration:

dcl.fct#5:

After determining the type of each parameter, any parameter of type “array of T” (...) is adjusted to be “pointer to T”.

So int arg[] is adjusted to be int* arg.

Conversion of your function argument:

conv.array#1

An lvalue or rvalue of type “array of N T” or “array of unknown bound of T” can be converted to a prvalue of type “pointer to T”. The temporary materialization conversion is applied. The result is a pointer to the first element of the array.

So in printarray(firstarray, 3);, the lvalue firstarray of type "array of 3 int" is converted to a prvalue (temporary) of type "pointer to int", pointing to the first element.

How do I clear a search box with an 'x' in bootstrap 3?

Super-simple HTML 5 Solution:

_x000D_
_x000D_
<input type="search" placeholder="Search..." />
_x000D_
_x000D_
_x000D_

Source: HTML 5 Tutorial - Input Type: Search

That works in at least Chrome 8, Edge 14, IE 10, and Safari 5 and does not require Bootstrap or any other library. (Unfortunately, it seems Firefox does not support the search clear button yet.)

After typing in the search box, an 'x' will appear which can be clicked to clear the text. This will still work as an ordinary edit box (without the 'x' button) in other browsers, such as Firefox, so Firefox users could instead select the text and press delete, or...

If you really need this nice-to-have feature supported in Firefox, then you could implement one of the other solutions posted here as a polyfill for input[type=search] elements. A polyfill is code that automatically adds a standard browser feature when the user's browser doesn't support the feature. Over time, the hope is that you'd be able to remove polyfills as browsers implement the respective features. And in any case, a polyfill implementation can help to keep the HTML code cleaner.

By the way, other HTML 5 input types (such as "date", "number", "email", etc.) will also degrade gracefully to a plain edit box. Some browsers might give you a fancy date picker, a spinner control with up/down buttons, or (on mobile phones) a special keyboard that includes the '@' sign and a '.com' button, but to my knowledge, all browsers will at least show a plain text box for any unrecognized input type.


Bootstrap 3 & HTML 5 Solution

Bootstrap 3 resets a lot of CSS and breaks the HTML 5 search cancel button. After the Bootstrap 3 CSS has been loaded, you can restore the search cancel button with the CSS used in the following example:

_x000D_
_x000D_
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>_x000D_
<style>_x000D_
  input[type="search"]::-webkit-search-cancel-button {_x000D_
    -webkit-appearance: searchfield-cancel-button;_x000D_
  }_x000D_
</style>_x000D_
<div class="form-inline">_x000D_
  <input type="search" placeholder="Search..." class="form-control" />_x000D_
</div>
_x000D_
_x000D_
_x000D_

Source: HTML 5 Search Input Does Not Work with Bootstrap

I have tested that this solution works in the latest versions of Chrome, Edge, and Internet Explorer. I am not able to test in Safari. Unfortunately, the 'x' button to clear the search does not appear in Firefox, but as above, a polyfill could be implemented for browsers that don't support this feature natively (i.e. Firefox).

laravel 5.5 The page has expired due to inactivity. Please refresh and try again

Tried different solutions to solve the problem for several weeks without success.

The problem I was facing was caused by upgrading from laravel 5.0 to 5.5 and forgot to update config/session.php

If anyone is facing the problem, try to update the config/session.php to match the version on Laravel you are running

Create Django model or update if exists

If one of the input when you create is a primary key, this will be enough:

Person.objects.get_or_create(id=1)

It will automatically update if exist since two data with the same primary key is not allowed.

How to install Hibernate Tools in Eclipse?

Installing Hibernate Tools on Eclipse Neon (4.6)

Go to the menu Help > Install New Software and click the Add button.

Use something like JBoss Hibernate for the name and insert the following URL for the location:

http://download.jboss.org/jbosstools/neon/stable/updates/ 

Wait for the product tree to load and then expand the JBoss Web and Java EE Development folder and select the Hibernate Tools product and click the Next > button. Then follow on accepting all the subsequent questions, licence, etc.

When the installation is finished, restart Eclipse as required. After that, to open the Hibernate perspective go to the menu Window > Perspective > Open Perspective > Others and search for Hibernate.

Where is Maven's settings.xml located on Mac OS?

It doesn't exist at first. You have to create it in your home folder, /Users/usename/.m2/ (or ~/.m2)

For example :

alt text

How to use FormData for AJAX file upload?

<form id="upload_form" enctype="multipart/form-data">

jQuery with CodeIgniter file upload:

var formData = new FormData($('#upload_form')[0]);

formData.append('tax_file', $('input[type=file]')[0].files[0]);

$.ajax({
    type: "POST",
    url: base_url + "member/upload/",
    data: formData,
    //use contentType, processData for sure.
    contentType: false,
    processData: false,
    beforeSend: function() {
        $('.modal .ajax_data').prepend('<img src="' +
            base_url +
            '"asset/images/ajax-loader.gif" />');
        //$(".modal .ajax_data").html("<pre>Hold on...</pre>");
        $(".modal").modal("show");
    },
    success: function(msg) {
        $(".modal .ajax_data").html("<pre>" + msg +
            "</pre>");
        $('#close').hide();
    },
    error: function() {
        $(".modal .ajax_data").html(
            "<pre>Sorry! Couldn't process your request.</pre>"
        ); // 
        $('#done').hide();
    }
});

you can use.

var form = $('form')[0]; 
var formData = new FormData(form);     
formData.append('tax_file', $('input[type=file]')[0].files[0]);

or

var formData = new FormData($('#upload_form')[0]);
formData.append('tax_file', $('input[type=file]')[0].files[0]); 

Both will work.

Expansion of variables inside single quotes in a command in Bash

Variables can contain single quotes.

myvar=\'....$variable\'

repo forall -c $myvar

unable to start mongodb local server

You already have a process running. You can kill it with the command :

killall mongod

how to add super privileges to mysql database?

On Centos 5 I was getting all sorts of errors trying to make changes to some variable values from the MySQL shell, after having logged in with the proper uid and pw (with root access). The error that I was getting was something like this:

mysql> -- Set some variable value, for example
mysql> SET GLOBAL general_log='ON';
ERROR 1227 (42000): Access denied; you need (at least one of) the SUPER privilege(s) for this operation

In a moment of extreme serendipity I did the following:

OS-Shell> sudo mysql                          # no DB uid, no DB pw

Kindly note that I did not provide the DB uid and password

mysql> show variables;
mysql> -- edit the variable of interest to the desired value, for example
mysql> SET GLOBAL general_log='ON';

It worked like a charm

Java: Why is the Date constructor deprecated, and what do I use instead?

The Date constructor expects years in the format of years since 1900, zero-based months, one-based days, and sets hours/minutes/seconds/milliseconds to zero.

Date result = new Date(year, month, day);

So using the Calendar replacement (zero-based years, zero-based months, one-based days) for the deprecated Date constructor, we need something like:

Calendar calendar = Calendar.getInstance();
calendar.clear(); // Sets hours/minutes/seconds/milliseconds to zero
calendar.set(year + 1900, month, day);
Date result = calendar.getTime();

Or using Java 1.8 (which has zero-based year, and one-based months and days):

Date result = Date.from(LocalDate.of(year + 1900, month + 1, day).atStartOfDay(ZoneId.systemDefault()).toInstant());

Here are equal versions of Date, Calendar, and Java 1.8:

int year = 1985; // 1985
int month = 1; // January
int day = 1; // 1st

// Original, 1900-based year, zero-based month, one-based day
Date date1 = new Date(year - 1900, month - 1, day);

// Calendar, zero-based year, zero-based month, one-based day
Calendar calendar = Calendar.getInstance();
calendar.clear(); // Sets hours/minutes/seconds/milliseconds to zero
calendar.set(year, month - 1, day);
Date date2 = calendar.getTime();

// Java-time back to Date, zero-based year, one-based month, one-based day
Date date3 = Date.from(LocalDate.of(year, month, day).atStartOfDay(ZoneId.systemDefault()).toInstant());

SimpleDateFormat format = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss.SSS");

// All 3 print "1985-Jan-01 00:00:00.000"
System.out.println(format.format(date1));
System.out.println(format.format(date2));
System.out.println(format.format(date3));

How long do browsers cache HTTP 301s?

as answer of @thomasrutter

If you previously issued a 301 redirect but want to un-do that

If people still have the cached 301 redirect in their browser they will continue to be taken to the target page regardless of whether the source page still has the redirect in place. Your options for fixing this include:

The simplest and best solution is to issue another 301 redirect back again.

The browser will realise it is being directed back to what it previously thought was a decommissioned URL, and this should cause it re-fetch that URL again to confirm that the old redirect isn't still there.

If you don't have control over the site where the previous redirect target went to, then you are outta luck. Try and beg the site owner to redirect back to you.

In fact, this means:

  1. a.com 301 to b.com

  2. delete a.com 's 301

  3. add b.com 301 to a.com

Then it works.

sqlplus statement from command line

I'm able to execute your exact query by just making sure there is a semicolon at the end of my select statement. (Output is actual, connection params removed.)

echo "select 1 from dual;" | sqlplus -s username/password@host:1521/service 

Output:

         1
----------
         1

Note that is should matter but this is running on Mac OS X Snow Leopard and Oracle 11g.

Add timer to a Windows Forms application

Download http://download.cnet.com/Free-Desktop-Timer/3000-2350_4-75415517.html

Then add a button or something on the form and inside its event, just open this app ie:

{

Process.Start(@"C:\Program Files (x86)\Free Desktop Timer\DesktopTimer");

}

How to convert file to base64 in JavaScript?

Building up on Dmitri Pavlutin and joshua.paling answers, here's an extended version that extracts the base64 content (removes the metadata at the beginning) and also ensures padding is done correctly.

function getBase64(file) {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.readAsDataURL(file);
    reader.onload = () => {
      let encoded = reader.result.toString().replace(/^data:(.*,)?/, '');
      if ((encoded.length % 4) > 0) {
        encoded += '='.repeat(4 - (encoded.length % 4));
      }
      resolve(encoded);
    };
    reader.onerror = error => reject(error);
  });
}

What is `related_name` used for in Django?

prefetch_related use for prefetch data for Many to many and many to one relationship data. select_related is to select data from a single value relationship. Both of these are used to fetch data from their relationships from a model. For example, you build a model and a model that has a relationship with other models. When a request comes you will also query for their relationship data and Django has very good mechanisms To access data from their relationship like book.author.name but when you iterate a list of models for fetching their relationship data Django create each request for every single relationship data. To overcome this we do have prefetchd_related and selected_related

C++ - Decimal to binary converting

You can use std::bitset to convert a number to its binary format.

Use the following code snippet:

std::string binary = std::bitset<8>(n).to_string();

I found this on stackoverflow itself. I am attaching the link.

MySQL Multiple Left Joins

You're missing a GROUP BY clause:

SELECT news.id, users.username, news.title, news.date, news.body, COUNT(comments.id)
FROM news
LEFT JOIN users
ON news.user_id = users.id
LEFT JOIN comments
ON comments.news_id = news.id
GROUP BY news.id

The left join is correct. If you used an INNER or RIGHT JOIN then you wouldn't get news items that didn't have comments.

How to plot multiple functions on the same figure, in Matplotlib?

Just use the function plot as follows

figure()
...
plot(t, a)
plot(t, b)
plot(t, c)

What does the fpermissive flag do?

Right from the docs:

-fpermissive
Downgrade some diagnostics about nonconformant code from errors to warnings. Thus, using -fpermissive will allow some nonconforming code to compile.

Bottom line: don't use it unless you know what you are doing!

Checking out Git tag leads to "detached HEAD state"

Okay, first a few terms slightly oversimplified.

In git, a tag (like many other things) is what's called a treeish. It's a way of referring to a point in in the history of the project. Treeishes can be a tag, a commit, a date specifier, an ordinal specifier or many other things.

Now a branch is just like a tag but is movable. When you are "on" a branch and make a commit, the branch is moved to the new commit you made indicating it's current position.

Your HEAD is pointer to a branch which is considered "current". Usually when you clone a repository, HEAD will point to master which in turn will point to a commit. When you then do something like git checkout experimental, you switch the HEAD to point to the experimental branch which might point to a different commit.

Now the explanation.

When you do a git checkout v2.0, you are switching to a commit that is not pointed to by a branch. The HEAD is now "detached" and not pointing to a branch. If you decide to make a commit now (as you may), there's no branch pointer to update to track this commit. Switching back to another commit will make you lose this new commit you've made. That's what the message is telling you.

Usually, what you can do is to say git checkout -b v2.0-fixes v2.0. This will create a new branch pointer at the commit pointed to by the treeish v2.0 (a tag in this case) and then shift your HEAD to point to that. Now, if you make commits, it will be possible to track them (using the v2.0-fixes branch) and you can work like you usually would. There's nothing "wrong" with what you've done especially if you just want to take a look at the v2.0 code. If however, you want to make any alterations there which you want to track, you'll need a branch.

You should spend some time understanding the whole DAG model of git. It's surprisingly simple and makes all the commands quite clear.

Copy text from nano editor to shell

nano does not seem to have the ability to copy/paste from the global/system clipboard or shell.

However, you can copy text from one file to another using nano's file buffers. When you open another file buffer with ^R (Ctrl + r), you can use nanos built-in copy/paste functionality (outlined below) to copy between files:

  • M-6 (Meta + 6) to copy lines to nano's clipboard.
  • ^K (Ctrl + k) to cut the current line and store it in nano's clipboard.
  • ^^ (Ctrl + Shift + 6) to select text. Once you have selected the text, you can use the above commands to copy it or cut it.
  • ^U (Ctrl + u) to paste the text from nano's clipboard.

Finally, if the above solution will not work for you and you are using a terminal emulator, you may be able to copy/paste from the global clipboard with Ctrl + Shift + c and Ctrl + Shift + v (Cmd + c and Cmd + v on OSX) respectively. screen also provides an external copy/paste that should work in nano. Finally if all you need to do is capture certain lines or text from a file, consider using grep to find the lines and xclip or xsel (or pbcopy/pbpaste on OSX) to copy them to the global clipboard (and/or paste from the clipboard) instead of nano.

Error while trying to retrieve text for error ORA-01019

Well,

Just worked it out. While having both installations we have two ORACLE_HOME directories and both have SQAORA32.dll files. While looking up for ORACLE_HOMe my app was getting confused..I just removed the Client oracle home entry as oracle client is by default present in oracle DB Now its working...Thanks!!

ORA-01438: value larger than specified precision allows for this column

One issue I've had, and it was horribly tricky, was that the OCI call to describe a column attributes behaves diffrently depending on Oracle versions. Describing a simple NUMBER column created without any prec or scale returns differenlty on 9i, 1Og and 11g

How to choose an AWS profile when using boto3 to connect to CloudFront

Just add profile to session configuration before client call. boto3.session.Session(profile_name='YOUR_PROFILE_NAME').client('cloudwatch')

Apache 2.4.6 on Ubuntu Server: Client denied by server configuration (PHP FPM) [While loading PHP file]

And I simply got this error because I used a totally different DocumentRoot directory.

My main DocumentRoot was the default /var/www/html and on the VirtualHost I used /sites/example.com

I have created a link on /var/www/html/example.com (to /sites/example.com). DocumentRoot was set to /var/www/html/example.com

It worked like a charm.

Add column with number of days between dates in DataFrame pandas

To remove the 'days' text element, you can also make use of the dt() accessor for series: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.dt.html

So,

df[['A','B']] = df[['A','B']].apply(pd.to_datetime) #if conversion required
df['C'] = (df['B'] - df['A']).dt.days

which returns:

             A          B   C
one 2014-01-01 2014-02-28  58
two 2014-02-03 2014-03-01  26

What use is find_package() if you need to specify CMAKE_MODULE_PATH anyway?

You don't need to specify the module path per se. CMake ships with its own set of built-in find_package scripts, and their location is in the default CMAKE_MODULE_PATH.

The more normal use case for dependent projects that have been CMakeified would be to use CMake's external_project command and then include the Use[Project].cmake file from the subproject. If you just need the Find[Project].cmake script, copy it out of the subproject and into your own project's source code, and then you won't need to augment the CMAKE_MODULE_PATH in order to find the subproject at the system level.

Dynamic type languages versus static type languages

Perhaps the single biggest "benefit" of dynamic typing is the shallower learning curve. There is no type system to learn and no non-trivial syntax for corner cases such as type constraints. That makes dynamic typing accessible to a lot more people and feasible for many people for whom sophisticated static type systems are out of reach. Consequently, dynamic typing has caught on in the contexts of education (e.g. Scheme/Python at MIT) and domain-specific languages for non-programmers (e.g. Mathematica). Dynamic languages have also caught on in niches where they have little or no competition (e.g. Javascript).

The most concise dynamically-typed languages (e.g. Perl, APL, J, K, Mathematica) are domain specific and can be significantly more concise than the most concise general-purpose statically-typed languages (e.g. OCaml) in the niches they were designed for.

The main disadvantages of dynamic typing are:

  • Run-time type errors.

  • Can be very difficult or even practically impossible to achieve the same level of correctness and requires vastly more testing.

  • No compiler-verified documentation.

  • Poor performance (usually at run-time but sometimes at compile time instead, e.g. Stalin Scheme) and unpredictable performance due to dependence upon sophisticated optimizations.

Personally, I grew up on dynamic languages but wouldn't touch them with a 40' pole as a professional unless there were no other viable options.

Fully custom validation error message with Rails

Related to the accepted answer and another answer down the list:

I'm confirming that nanamkim's fork of custom-err-msg works with Rails 5, and with the locale setup.

You just need to start the locale message with a caret and it shouldn't display the attribute name in the message.

A model defined as:

class Item < ApplicationRecord
  validates :name, presence: true
end

with the following en.yml:

en:
  activerecord:
    errors:
      models:
        item:
          attributes:
            name:
              blank: "^You can't create an item without a name."

item.errors.full_messages will display:

You can't create an item without a name

instead of the usual Name You can't create an item without a name

Mockito: Mock private field initialization

Using @Jarda's guide you can define this if you need to set the variable the same value for all tests:

@Before
public void setClientMapper() throws NoSuchFieldException, SecurityException{
    FieldSetter.setField(client, client.getClass().getDeclaredField("mapper"), new Mapper());
}

But beware that setting private values to be different should be handled with care. If they are private are for some reason.

Example, I use it, for example, to change the wait time of a sleep in the unit tests. In real examples I want to sleep for 10 seconds but in unit-test I'm satisfied if it's immediate. In integration tests you should test the real value.

How to create a temporary directory?

The following snippet will safely create a temporary directory (-d) and store its name into the TMPDIR. (An example use of TMPDIR variable is shown later in the code where it's used for storing original files that will be possibly modified.)

The first trap line executes exit 1 command when any of the specified signals is received. The second trap line removes (cleans up) the $TMPDIR on program's exit (both normal and abnormal). We initialize these traps after we check that mkdir -d succeeded to avoid accidentally executing the exit trap with $TMPDIR in an unknown state.

#!/bin/bash

# Create a temporary directory and store its name in a variable ...
TMPDIR=$(mktemp -d)

# Bail out if the temp directory wasn't created successfully.
if [ ! -e $TMPDIR ]; then
    >&2 echo "Failed to create temp directory"
    exit 1
fi

# Make sure it gets removed even if the script exits abnormally.
trap "exit 1"           HUP INT PIPE QUIT TERM
trap 'rm -rf "$TMPDIR"' EXIT

# Example use of TMPDIR:
for f in *.csv; do
    cp "$f" "$TMPDIR"
    # remove duplicate lines but keep order
    perl -ne 'print if ++$k{$_}==1' "$TMPDIR/$f" > "$f"
done

How to run test methods in specific order in JUnit4?

If you get rid of your existing instance of Junit, and download JUnit 4.11 or greater in the build path, the following code will execute the test methods in the order of their names, sorted in ascending order:

@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class SampleTest {

    @Test
    public void testAcreate() {
        System.out.println("first");
    }
    @Test
    public void testBupdate() {
        System.out.println("second");
    }
    @Test
    public void testCdelete() {
        System.out.println("third");
    }
}

Best way to get identity of inserted row?

I believe the safest and most accurate method of retrieving the inserted id would be using the output clause.

for example (taken from the following MSDN article)

USE AdventureWorks2008R2;
GO
DECLARE @MyTableVar table( NewScrapReasonID smallint,
                           Name varchar(50),
                           ModifiedDate datetime);
INSERT Production.ScrapReason
    OUTPUT INSERTED.ScrapReasonID, INSERTED.Name, INSERTED.ModifiedDate
        INTO @MyTableVar
VALUES (N'Operator error', GETDATE());

--Display the result set of the table variable.
SELECT NewScrapReasonID, Name, ModifiedDate FROM @MyTableVar;
--Display the result set of the table.
SELECT ScrapReasonID, Name, ModifiedDate 
FROM Production.ScrapReason;
GO

How to replace plain URLs with links?

Replace URLs in text with HTML links, ignore the URLs within a href/pre tag. https://github.com/JimLiu/auto-link

How to preserve insertion order in HashMap?

HashMap is unordered per the second line of the documentation:

This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.

Perhaps you can do as aix suggests and use a LinkedHashMap, or another ordered collection. This link can help you find the most appropriate collection to use.

Capturing count from an SQL query

SqlConnection conn = new SqlConnection("ConnectionString");
conn.Open();
SqlCommand comm = new SqlCommand("SELECT COUNT(*) FROM table_name", conn);
Int32 count = (Int32) comm .ExecuteScalar();

Stopword removal with NLTK

You can use string.punctuation with built-in NLTK stopwords list:

from nltk.tokenize import word_tokenize, sent_tokenize
from nltk.corpus import stopwords
from string import punctuation

words = tokenize(text)
wordsWOStopwords = removeStopWords(words)

def tokenize(text):
        sents = sent_tokenize(text)
        return [word_tokenize(sent) for sent in sents]

def removeStopWords(words):
        customStopWords = set(stopwords.words('english')+list(punctuation))
        return [word for word in words if word not in customStopWords]

NLTK stopwords complete list

Android webview slow

Adding this android:hardwareAccelerated="true" in the manifest was the only thing that significantly improved the performance for me

More info here: http://developer.android.com/guide/topics/manifest/application-element.html#hwaccel

Hash table in JavaScript

You could use my JavaScript hash table implementation, jshashtable. It allows any object to be used as a key, not just strings.

Regular expression to remove HTML tags from a string

A trivial approach would be to replace

<[^>]*>

with nothing. But depending on how ill-structured your input is that may well fail.

Open CSV file via VBA (performance)

This function reads a CSV file of 15MB and copies its content into a sheet in about 3 secs. What is probably taking a lot of time in your code is the fact that you copy data cell by cell instead of putting the whole content at once.

Option Explicit

Public Sub test()

  copyDataFromCsvFileToSheet "C:\temp\test.csv", ",", "Sheet1"

End Sub

Private Sub copyDataFromCsvFileToSheet(parFileName As String, parDelimiter As String, parSheetName As String)

  Dim data As Variant

  data = getDataFromFile(parFileName, parDelimiter)
  If Not isArrayEmpty(data) Then
    With Sheets(parSheetName)
      .Cells.ClearContents
      .Cells(1, 1).Resize(UBound(data, 1), UBound(data, 2)) = data
    End With
  End If

End Sub

Public Function isArrayEmpty(parArray As Variant) As Boolean
'Returns false if not an array or dynamic array that has not been initialised (ReDim) or has been erased (Erase)

  If IsArray(parArray) = False Then isArrayEmpty = True
  On Error Resume Next
  If UBound(parArray) < LBound(parArray) Then isArrayEmpty = True: Exit Function Else: isArrayEmpty = False

End Function

Private Function getDataFromFile(parFileName As String, parDelimiter As String, Optional parExcludeCharacter As String = "") As Variant
'parFileName is supposed to be a delimited file (csv...)
'parDelimiter is the delimiter, "," for example in a comma delimited file
'Returns an empty array if file is empty or can't be opened
'number of columns based on the line with the largest number of columns, not on the first line
'parExcludeCharacter: sometimes csv files have quotes around strings: "XXX" - if parExcludeCharacter = """" then removes the quotes


  Dim locLinesList() As Variant
  Dim locData As Variant
  Dim i As Long
  Dim j As Long
  Dim locNumRows As Long
  Dim locNumCols As Long
  Dim fso As Variant
  Dim ts As Variant
  Const REDIM_STEP = 10000

  Set fso = CreateObject("Scripting.FileSystemObject")

  On Error GoTo error_open_file
  Set ts = fso.OpenTextFile(parFileName)
  On Error GoTo unhandled_error

  'Counts the number of lines and the largest number of columns
  ReDim locLinesList(1 To 1) As Variant
  i = 0
  Do While Not ts.AtEndOfStream
    If i Mod REDIM_STEP = 0 Then
      ReDim Preserve locLinesList(1 To UBound(locLinesList, 1) + REDIM_STEP) As Variant
    End If
    locLinesList(i + 1) = Split(ts.ReadLine, parDelimiter)
    j = UBound(locLinesList(i + 1), 1) 'number of columns
    If locNumCols < j Then locNumCols = j
    i = i + 1
  Loop

  ts.Close

  locNumRows = i

  If locNumRows = 0 Then Exit Function 'Empty file

  ReDim locData(1 To locNumRows, 1 To locNumCols + 1) As Variant

  'Copies the file into an array
  If parExcludeCharacter <> "" Then

    For i = 1 To locNumRows
      For j = 0 To UBound(locLinesList(i), 1)
        If Left(locLinesList(i)(j), 1) = parExcludeCharacter Then
          If Right(locLinesList(i)(j), 1) = parExcludeCharacter Then
            locLinesList(i)(j) = Mid(locLinesList(i)(j), 2, Len(locLinesList(i)(j)) - 2)       'If locTempArray = "", Mid returns ""
          Else
            locLinesList(i)(j) = Right(locLinesList(i)(j), Len(locLinesList(i)(j)) - 1)
          End If
        ElseIf Right(locLinesList(i)(j), 1) = parExcludeCharacter Then
          locLinesList(i)(j) = Left(locLinesList(i)(j), Len(locLinesList(i)(j)) - 1)
        End If
        locData(i, j + 1) = locLinesList(i)(j)
      Next j
    Next i

  Else

    For i = 1 To locNumRows
      For j = 0 To UBound(locLinesList(i), 1)
        locData(i, j + 1) = locLinesList(i)(j)
      Next j
    Next i

  End If

  getDataFromFile = locData

  Exit Function

error_open_file:             'returns empty variant
unhandled_error:             'returns empty variant

End Function

What is an ORM, how does it work, and how should I use one?

An ORM (Object Relational Mapper) is a piece/layer of software that helps map your code Objects to your database.

Some handle more aspects than others...but the purpose is to take some of the weight of the Data Layer off of the developer's shoulders.

Here's a brief clip from Martin Fowler (Data Mapper):

Patterns of Enterprise Application Architecture Data Mappers

How to write a:hover in inline CSS?

This is the best code example:

_x000D_
_x000D_
<a_x000D_
 style="color:blue;text-decoration: underline;background: white;"_x000D_
 href="http://aashwin.com/index.php/education/library/"_x000D_
 onmouseover="this.style.color='#0F0'"_x000D_
 onmouseout="this.style.color='#00F'">_x000D_
   Library_x000D_
</a>
_x000D_
_x000D_
_x000D_

Moderator Suggestion: Keep your separation of concerns.

HTML

_x000D_
_x000D_
<a_x000D_
 style="color:blue;text-decoration: underline;background: white;"_x000D_
 href="http://aashwin.com/index.php/education/library/"_x000D_
 class="lib-link">_x000D_
   Library_x000D_
</a>
_x000D_
_x000D_
_x000D_

JS

_x000D_
_x000D_
const libLink = document.getElementsByClassName("lib-link")[0];_x000D_
// The array 0 assumes there is only one of these links,_x000D_
// you would have to loop or use event delegation for multiples_x000D_
// but we won't go into that here_x000D_
libLink.onmouseover = function () {_x000D_
  this.style.color='#0F0'_x000D_
}_x000D_
libLink.onmouseout = function () {_x000D_
  this.style.color='#00F'_x000D_
}
_x000D_
_x000D_
_x000D_

Difference between "read commited" and "repeatable read"

Repeatable Read

The state of the database is maintained from the start of the transaction. If you retrieve a value in session1, then update that value in session2, retrieving it again in session1 will return the same results. Reads are repeatable.

session1> BEGIN;
session1> SELECT firstname FROM names WHERE id = 7;
Aaron

session2> BEGIN;
session2> SELECT firstname FROM names WHERE id = 7;
Aaron
session2> UPDATE names SET firstname = 'Bob' WHERE id = 7;
session2> SELECT firstname FROM names WHERE id = 7;
Bob
session2> COMMIT;

session1> SELECT firstname FROM names WHERE id = 7;
Aaron

Read Committed

Within the context of a transaction, you will always retrieve the most recently committed value. If you retrieve a value in session1, update it in session2, then retrieve it in session1again, you will get the value as modified in session2. It reads the last committed row.

session1> BEGIN;
session1> SELECT firstname FROM names WHERE id = 7;
Aaron

session2> BEGIN;
session2> SELECT firstname FROM names WHERE id = 7;
Aaron
session2> UPDATE names SET firstname = 'Bob' WHERE id = 7;
session2> SELECT firstname FROM names WHERE id = 7;
Bob
session2> COMMIT;

session1> SELECT firstname FROM names WHERE id = 7;
Bob

Makes sense?

Shall we always use [unowned self] inside closure in Swift

Here is brilliant quotes from Apple Developer Forums described delicious details:

unowned vs unowned(safe) vs unowned(unsafe)

unowned(safe) is a non-owning reference that asserts on access that the object is still alive. It's sort of like a weak optional reference that's implicitly unwrapped with x! every time it's accessed. unowned(unsafe) is like __unsafe_unretained in ARC—it's a non-owning reference, but there's no runtime check that the object is still alive on access, so dangling references will reach into garbage memory. unowned is always a synonym for unowned(safe) currently, but the intent is that it will be optimized to unowned(unsafe) in -Ofast builds when runtime checks are disabled.

unowned vs weak

unowned actually uses a much simpler implementation than weak. Native Swift objects carry two reference counts, and unowned references bump the unowned reference count instead of the strong reference count. The object is deinitialized when its strong reference count reaches zero, but it isn't actually deallocated until the unowned reference count also hits zero. This causes the memory to be held onto slightly longer when there are unowned references, but that isn't usually a problem when unowned is used because the related objects should have near-equal lifetimes anyway, and it's much simpler and lower-overhead than the side-table based implementation used for zeroing weak references.

Update: In modern Swift weak internally uses the same mechanism as unowned does. So this comparison is incorrect because it compares Objective-C weak with Swift unonwed.

Reasons

What is the purpose of keeping the memory alive after owning references reach 0? What happens if code attempts to do something with the object using an unowned reference after it is deinitialized?

The memory is kept alive so that its retain counts are still available. This way, when someone attempts to retain a strong reference to the unowned object, the runtime can check that the strong reference count is greater than zero in order to ensure that it is safe to retain the object.

What happens to owning or unowned references held by the object? Is their lifetime decoupled from the object when it is deinitialized or is their memory also retained until the object is deallocated after the last unowned reference is released?

All resources owned by the object are released as soon as the object's last strong reference is released, and its deinit is run. Unowned references only keep the memory alive—aside from the header with the reference counts, its contents is junk.

Excited, huh?

Getter and Setter?

Generally speaking, the first way is more popular overall because those with prior programming knowledge can easily transition to PHP and get work done in an object-oriented fashion. The first way is more universal. My advice would be to stick with what is tried and true across many languages. Then, when and if you use another language, you'll be ready to get something accomplished (instead of spending time reinventing the wheel).

LOAD DATA INFILE Error Code : 13

There is one property in mysql configuration file under section [mysqld] with name - tmpdir

for example:

tmpdir = c:/temp (Windows) or tmpdir = /tmp (Linux)

and LOAD DATA INFILE command can perform read and write on this location only.

so if you put your file at that specified location then LOAD DATA INFILE can read/write any file easily.

One more solution

we can import data by following command too

load data local infile

In this case there is no need to move file to tmpdir, you can give the absolute path of file, but to execute this command, you need to change one flag value. The flag is

--local-infile

you can change its value by command prompt while getting access of mysql

mysql -u username -p --local-infile=1

Cheers

How can I wait for 10 second without locking application UI in android

You can use this:

Handler handler = new Handler();
handler.postDelayed(new Runnable() {
    public void run() {
     // Actions to do after 10 seconds
    }
}, 10000);

For Stop the Handler, You can try this: handler.removeCallbacksAndMessages(null);

MySQL Select Date Equal to Today

You can use the CONCAT with CURDATE() to the entire time of the day and then filter by using the BETWEEN in WHERE condition:

SELECT users.id, DATE_FORMAT(users.signup_date, '%Y-%m-%d') 
FROM users 
WHERE (users.signup_date BETWEEN CONCAT(CURDATE(), ' 00:00:00') AND CONCAT(CURDATE(), ' 23:59:59'))

How do I increment a DOS variable in a FOR /F loop?

set TEXT_T="myfile.txt"
set /a c=1

FOR /F "tokens=1 usebackq" %%i in (%TEXT_T%) do (
    set /a c+=1
    set OUTPUT_FILE_NAME=output_%c%.txt
    echo Output file is %OUTPUT_FILE_NAME%
    echo %%i, %c%
)

How create a new deep copy (clone) of a List<T>?

Well,

If you mark all involved classes as serializable you can :

public static List<T> CloneList<T>(List<T> oldList)  
{  
BinaryFormatter formatter = new BinaryFormatter();  
MemoryStream stream = new MemoryStream();  
formatter.Serialize(stream, oldList);  
stream.Position = 0;  
return (List<T>)formatter.Deserialize(stream);      
} 

Source:

https://social.msdn.microsoft.com/Forums/en-US/5c9b4c31-850d-41c4-8ea3-fae734b348c4/copy-listsomeobject-to-clone-list?forum=csharpgeneral

CSS image resize percentage of itself?

This is a not-hard approach:

<div>
    <img src="sample.jpg" />
</div>

then in css:
div {
    position: absolute;
}

img, div {
   width: ##%;
   height: ##%;
}

How to cherry pick a range of commits and merge into another branch?

Assume that you have 2 branches,

"branchA" : includes commits you want to copy (from "commitA" to "commitB"

"branchB" : the branch you want the commits to be transferred from "branchA"

1)

 git checkout <branchA>

2) get the IDs of "commitA" and "commitB"

3)

git checkout <branchB>

4)

git cherry-pick <commitA>^..<commitB>

5) In case you have a conflict, solve it and type

git cherry-pick --continue

to continue the cherry-pick process.

Do you (really) write exception safe code?

  • Do you really write exception safe code?

Well, I certainly intend to.

  • Are you sure your last "production ready" code is exception safe?

I'm sure that my 24/7 servers built using exceptions run 24/7 and don't leak memory.

  • Can you even be sure, that it is?

It's very difficult to be sure that any code is correct. Typically, one can only go by results

  • Do you know and/or actually use alternatives that work?

No. Using exceptions is cleaner and easier than any of the alternatives I've used over the last 30 years in programming.

How to use SQL Select statement with IF EXISTS sub query?

Use a CASE statement and do it like this:

SELECT 
    T1.Id [Id]
    ,CASE WHEN T2.Id IS NOT NULL THEN 'TRUE' ELSE 'FALSE' END [Has Foreign Key in T2]
FROM
    TABLE1 [T1]
    LEFT OUTER JOIN
        TABLE2 [T2]
        ON
        T2.Id = T1.Id

How can I scroll a web page using selenium webdriver in python?

element=find_element_by_xpath("xpath of the li you are trying to access")

element.location_once_scrolled_into_view

this helped when I was trying to access a 'li' that was not visible.

Difference between h:button and h:commandButton

This is taken from the book - The Complete Reference by Ed Burns & Chris Schalk

h:commandButton vs h:button

What’s the difference between h:commandButton|h:commandLink and h:button|h:link ?

The latter two components were introduced in 2.0 to enable bookmarkable JSF pages, when used in concert with the View Parameters feature.

There are 3 main differences between h:button|h:link and h:commandButton|h:commandLink.

First, h:button|h:link causes the browser to issue an HTTP GET request, while h:commandButton|h:commandLink does a form POST. This means that any components in the page that have values entered by the user, such as text fields, checkboxes, etc., will not automatically be submitted to the server when using h:button|h:link. To cause values to be submitted with h:button|h:link, extra action has to be taken, using the “View Parameters” feature.

The second main difference between the two kinds of components is that h:button|h:link has an outcome attribute to describe where to go next while h:commandButton|h:commandLink uses an action attribute for this purpose. This is because the former does not result in an ActionEvent in the event system, while the latter does.

Finally, and most important to the complete understanding of this feature, the h:button|h:link components cause the navigation system to be asked to derive the outcome during the rendering of the page, and the answer to this question is encoded in the markup of the page. In contrast, the h:commandButton|h:commandLink components cause the navigation system to be asked to derive the outcome on the POSTBACK from the page. This is a difference in timing. Rendering always happens before POSTBACK.

How to make a pure css based dropdown menu?

Create simple drop-down menu using HTML and CSS

CSS:

<style>
.dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    padding: 12px 16px;
    z-index: 1;
}

.dropdown:hover .dropdown-content {
    display: block;
}
</style>

and HTML:

<div class="dropdown">
  <span>Mouse over me</span>
  <div class="dropdown-content">
    <p>Hello World!</p>
  </div>
</div>

View demo online

How to stop/terminate a python script from running?

If you are working with Spyder, use CTRL + . (DOT) and you will restart the kernel, also you will stop the program.

How to check if the key pressed was an arrow key in Java KeyListener?

Just to complete the answer (using the KeyEvent is the way to go) but up arrow is 38 and down arrow is 40 so:

    else if (e.getKeyCode()==38)
    {
            //Up arrow key code
    }
    else if (e.getKeyCode()==40)
    {
            //down arrow key code
    }

Don't reload application when orientation changes

just use : android:configChanges="keyboardHidden|orientation"

What is the best way to remove the first element from an array?

To sum up, the quick linkedlist method:

List<String> llist = new LinkedList<String>(Arrays.asList(oldArray));
llist.remove(0);

Retrofit 2.0 how to get deserialised error response.body

In Retrofit 2.0 beta2 this is the way that I'm getting error responses:

  1. Synchronous

    try {
       Call<RegistrationResponse> call = backendServiceApi.register(data.in.account, data.in.password,
               data.in.email);
       Response<RegistrationResponse> response = call.execute();
       if (response != null && !response.isSuccess() && response.errorBody() != null) {
           Converter<ResponseBody, BasicResponse> errorConverter =
                   MyApplication.getRestClient().getRetrofitInstance().responseConverter(BasicResponse.class, new Annotation[0]);
           BasicResponse error = errorConverter.convert(response.errorBody());
           //DO ERROR HANDLING HERE
           return;
       }
       RegistrationResponse registrationResponse = response.body();
       //DO SUCCESS HANDLING HERE
    } catch (IOException e) {
       //DO NETWORK ERROR HANDLING HERE
    }
    
  2. Asynchronous

    Call<BasicResponse> call = service.loadRepo();
    call.enqueue(new Callback<BasicResponse>() {
        @Override
        public void onResponse(Response<BasicResponse> response, Retrofit retrofit) {
            if (response != null && !response.isSuccess() && response.errorBody() != null) {
                Converter<ResponseBody, BasicResponse> errorConverter =
                    retrofit.responseConverter(BasicResponse.class, new Annotation[0]);
                BasicResponse error = errorConverter.convert(response.errorBody());
                //DO ERROR HANDLING HERE
                return;
            }
            RegistrationResponse registrationResponse = response.body();
            //DO SUCCESS HANDLING HERE
        }
    
        @Override
        public void onFailure(Throwable t) {
            //DO NETWORK ERROR HANDLING HERE
        }
    });
    

Update for Retrofit 2 beta3:

  1. Synchronous - not changed
  2. Asynchronous - Retrofit parameter was removed from onResponse

    Call<BasicResponse> call = service.loadRepo();
    call.enqueue(new Callback<BasicResponse>() {
        @Override
        public void onResponse(Response<BasicResponse> response) {
            if (response != null && !response.isSuccess() && response.errorBody() != null) {
                Converter<ResponseBody, BasicResponse> errorConverter =
                    MyApplication.getRestClient().getRetrofitInstance().responseConverter(BasicResponse.class, new Annotation[0]);
                BasicResponse error = errorConverter.convert(response.errorBody());
                //DO ERROR HANDLING HERE
                return;
            }
            RegistrationResponse registrationResponse = response.body();
            //DO SUCCESS HANDLING HERE
        }
    
        @Override
        public void onFailure(Throwable t) {
            //DO NETWORK ERROR HANDLING HERE
        }
    });
    

Python base64 data decode

Interesting if maddening puzzle...but here's the best I could get:

The data seems to repeat every 8 bytes or so.

import struct
import base64

target = \
r'''Q5YACgAAAABDlgAbAAAAAEOWAC0AAAAAQ5YAPwAAAABDlgdNAAAAAEOWB18AAAAAQ5YH 
[snip.]
ZAAAAABExxniAAAAAETH/rQAAAAARMf/MwAAAABEx/+yAAAAAETIADEAAAAA''' 

data = base64.b64decode(target)

cleaned_data = []
struct_format = ">ff"
for i in range(len(data) // 8):
   cleaned_data.append(struct.unpack_from(struct_format, data, 8*i))

That gives output like the following (a sampling of lines from the first 100 or so):

(300.00030517578125, 0.0)
(300.05975341796875, 241.93943786621094)
(301.05612182617187, 0.0)
(301.05667114257812, 8.7439727783203125)
(326.9617919921875, 0.0)
(326.96826171875, 0.0)
(328.34432983398438, 280.55218505859375)

That first number does seem to monotonically increase through the entire set. If you plot it:

import matplotlib.pyplot as plt
f, ax = plt.subplots()
ax.plot(*zip(*cleaned_data))

enter image description here

format = 'hhhh' (possibly with various paddings/directions (e.g. '<hhhh', '<xhhhh') also might be worth a look (again, random lines):

(-27069, 2560, 0, 0)
(-27069, 8968, 0, 0)
(-27069, 13576, 3139, -18487)
(-27069, 18184, 31043, -5184)
(-27069, -25721, -25533, -8601)
(-27069, -7289, 0, 0)
(-25533, 31066, 0, 0)
(-25533, -29350, 0, 0)
(-25533, 25179, 0, 0)
(-24509, -1888, 0, 0)
(-24509, -4447, 0, 0)
(-23741, -14725, 32067, 27475)
(-23741, -3973, 0, 0)
(-23485, 4908, -29629, -20922)

jquery beforeunload when closing (not leaving) the page?

You can do this by using JQuery.

For example ,

<a href="your URL" id="navigate"> click here </a>

Your JQuery will be,

$(document).ready(function(){

    $('a').on('mousedown', stopNavigate);

    $('a').on('mouseleave', function () {
           $(window).on('beforeunload', function(){
                  return 'Are you sure you want to leave?';
           });
    });
});

function stopNavigate(){    
    $(window).off('beforeunload');
}

And to get the Leave message alert will be,

$(window).on('beforeunload', function(){
      return 'Are you sure you want to leave?';
});

$(window).on('unload', function(){

         logout();

});

This solution works in all browsers and I have tested it.

How to detect when cancel is clicked on file input?

A lot of people keep suggesting the change event... even though OP specified that this doesn't work in the question:

CLICKING CANCEL DOES NOT SELECT A FILE AND THUS WILL NOT TRIGGER A CHANGE TO FILE INPUT!!!

all the code most people are suggesting will NOT run when cancel is clicked.

After a lot of experimentation based on suggestions from people who actually read OP's question, I've come up with this class to wrap the functionality of the file input and added two custom events:

  • choose: The user has chosen a file (still triggers if they select the same file again).
  • cancel: The user has clicked cancel or otherwise closed the file dialog with no selection.

I've also added redundancy (listen to multiple events to try and determine if cancel was pressed). Might not always respond right away but should at least guarantee that a cancel event is registered when the user re-engages the page.

Finally I noticed that events are not always guaranteed to happen in the same order (especially when the dialog closing triggers them all at nearly the same instant). This class waits for 100ms to make sure that the change event has fired before it checks for a success flag.

Uses ES6 class so probably won't work for anything before that FYI, though you could probably edit it if you wanna waste your time making it work on IE .

The Class:

class FileManager {
    // Keep important properties from being overwritten
    constructor() {
        Object.defineProperties(this, {
            // The file input element (hidden)
            _fileInput: {
                value: document.createElement('input'),
                writeable: false,
                enumerable: false,
                configurable: false
            },
            // Flag to denote if a file was chosen
            _chooseSuccess: {
                value: false,
                writable: true,
            },
            // Keeps events from mult-firing
            // Don't want to consume just incase!
            _eventFiredOnce: {
                value: false,
                writable: true,
            },
            // Called BEFORE dialog is shown
            _chooseStart_handler: {
                value: (event) => {
                    // Choose might happen, assume it won't
                    this._chooseSuccess = false;

                    // Allow a single fire
                    this._eventFiredOnce = false;

                    // Reset value so repeat files also trigger a change/choose
                    this._fileInput.value = '';



                    /* File chooser is semi-modal and will stall events while it's opened */
                    /* Beware, some code can still run while the dialog is opened! */

                    // Window will usually focus on dialog close
                    // If it works this is best becuase the event will trigger as soon as the dialog is closed
                    // Even the user has moved the dialog off of the browser window is should still refocus
                    window.addEventListener('focus', this._chooseEnd_handler);

                    // This will always fire when the mouse first enters the body
                    // A good redundancy but will not fire immeditely if the cance button is not...
                    // in window when clicked
                    document.body.addEventListener('mouseenter', this._chooseEnd_handler);

                    // Again almost a guarantee that this will fire but it will not do so...
                    // imediately if the dialog is out of window!
                    window.addEventListener('mousemove', this._chooseEnd_handler);
                },
                writeable: false,
                enumerable: false,
                configurable: false
            },
            _chooseEnd_handler: {
                // Focus event may beat change event
                // Wait 1/10th of a second to make sure change registers!
                value: (event) => {
                    // queue one event to fire
                    if (this._eventFiredOnce)
                        return;

                    // Mark event as fired once
                    this._eventFiredOnce = true;
                    // double call prevents 'this' context swap, IHT!
                    setTimeout((event) => {
                        this._timeout_handler(event);
                    }, 100);
                },
                writeable: false,
                enumerable: false,
                configurable: false
            },
            _choose_handler: {
                value: (event) => {
                    // A file was chosen by the user
                    // Set flag
                    this._chooseSuccess = true;
                    // End the choose
                    this._chooseEnd_handler(event);
                },
                writeable: false,
                enumerable: false,
                configurable: false
            },
            _timeout_handler: {
                value: (event) => {
                    if (!this._chooseSuccess) {
                        // Choose process done, no file selected
                        // Fire cancel event on input
                        this._fileInput.dispatchEvent(new Event('cancel'));
                    } else {
                        // Choose process done, file was selected
                        // Fire chosen event on input
                        this._fileInput.dispatchEvent(new Event('choose'));
                    }

                    // remove listeners or cancel will keep firing
                    window.removeEventListener('focus', this._chooseEnd_handler);
                    document.body.removeEventListener('mouseenter', this._chooseEnd_handler);
                    window.removeEventListener('mousemove', this._chooseEnd_handler);
                },
                writeable: false,
                enumerable: false,
                configurable: false
            },
            addEventListener: {
                value: (type, handle) => {
                    this._fileInput.addEventListener(type, handle);
                },
                writeable: false,
                enumerable: false,
                configurable: false
            },
            removeEventListener: {
                value: (type, handle) => {
                    this._fileInput.removeEventListener(type, handle);
                },
                writeable: false,
                enumerable: false,
                configurable: false
            },
            // Note: Shadow clicks must be called from a user input event stack!
            openFile: {
                value: () => {
                    // Trigger custom pre-click event
                    this._chooseStart_handler();

                    // Show file dialog
                    this._fileInput.click();
                    // ^^^ Code will still run after this part (non halting)
                    // Events will not trigger though until the dialog is closed
                }
            }
        });
        this._fileInput.type = 'file';
        this._fileInput.addEventListener('change', this._choose_handler);
    }

    // Get all files
    get files() {
        return this._input.files;
    }

    // Get input element (reccomended to keep hidden);
    get domElement(){
        return this._fileInput;
    }

    // Get specific file
    getFile(index) {
        return index === undefined ? this._fileInput.files[0] : this._fileInput.files[index];
    }

    // Set multi-select
    set multiSelect(value) {
        let val = value ? 'multiple' : '';
        this._fileInput.setAttribute('multiple', val);
    }

    // Get multi-select
    get multiSelect() {
        return this._fileInput.multiple === 'multiple' ? true : false;
    }
}

Usage Example:

// Instantiate
let fm = new FileManager();

// Bind to something that triggers a user input event (buttons are good)
let btn = document.getElementById('btn');

// Call openFile on intance to show the dialog to the user
btn.addEventListener('click', (event) => {
  fm.openFile();
});

// Fires if the user selects a file and clicks the 'okay' button
fm.addEventListener('choose', (event) => {
  console.log('file chosen: ' + fm.getFile(0).name);
});

// Fires if the user clicks 'cancel' or closes the file dialog
fm.addEventListener('cancel', (event) => {
  console.log('File choose has been canceled!');
});

Might be very late but I think this is a decent solution that covers most of the crippling edge cases. I'll be using this solution myself so I might come back with a git repo eventually after I play with it and refine it more.

Find a file in python

In Python 3.4 or newer you can use pathlib to do recursive globbing:

>>> import pathlib
>>> sorted(pathlib.Path('.').glob('**/*.py'))
[PosixPath('build/lib/pathlib.py'),
 PosixPath('docs/conf.py'),
 PosixPath('pathlib.py'),
 PosixPath('setup.py'),
 PosixPath('test_pathlib.py')]

Reference: https://docs.python.org/3/library/pathlib.html#pathlib.Path.glob

In Python 3.5 or newer you can also do recursive globbing like this:

>>> import glob
>>> glob.glob('**/*.txt', recursive=True)
['2.txt', 'sub/3.txt']

Reference: https://docs.python.org/3/library/glob.html#glob.glob

AngularJS/javascript converting a date String to date object

This is what I did on the controller

var collectionDate = '2002-04-26T09:00:00';
var date = new Date(collectionDate);
//then pushed all my data into an array $scope.rows which I then used in the directive

I ended up formatting the date to my desired pattern on the directive as follows.

var data = new google.visualization.DataTable();
                    data.addColumn('date', 'Dates');
                    data.addColumn('number', 'Upper Normal');
                    data.addColumn('number', 'Result');
                    data.addColumn('number', 'Lower Normal');
                    data.addRows(scope.rows);
                    var formatDate = new google.visualization.DateFormat({pattern: "dd/MM/yyyy"});
                    formatDate.format(data, 0);
//set options for the line chart
var options = {'hAxis': format: 'dd/MM/yyyy'}

//Instantiate and draw the chart passing in options
var chart = new google.visualization.LineChart($elm[0]);
                    chart.draw(data, options);

This gave me dates ain the format of dd/MM/yyyy (26/04/2002) on the x axis of the chart.

Get Return Value from Stored procedure in asp.net

If you want to to know how to return a value from stored procedure to Visual Basic.NET. Please read this tutorial: How to return a value from stored procedure

I used the following stored procedure to return the value.

CREATE PROCEDURE usp_get_count

AS
BEGIN
 DECLARE @VALUE int;

 SET @VALUE=(SELECT COUNT(*) FROM tblCar);

 RETURN @VALUE;

END
GO

ORA-01653: unable to extend table by in tablespace ORA-06512

To resolve this error:

ORA-01653 unable to extend table by 1024 in tablespace your-tablespace-name

Just run this PL/SQL command for extended tablespace size automatically on-demand:

alter database datafile '<your-tablespace-name>.dbf' autoextend on maxsize unlimited;

I get this error in import big dump file, just run this command without stopping import routine or restarting the database.

Note: each data file has a limit of 32GB of size if you need more than 32GB you should add a new data file to your existing tablespace.

More info: alter_autoextend_on

read word by word from file in C++

If I may I could give you some new code for the same task, in my code you can create a so called 'document'(not really)and it is saved, and can be opened up again. It is also stored as a string file though(not a document). Here is the code:

#include "iostream"

#include "windows.h"

#include "string"

#include "fstream"

using namespace std;

int main() {

string saveload;


cout << "---------------------------" << endl;
cout << "|enter 'text' to write your document    |" << endl;
cout << "|enter 'open file' to open the document |" << endl;
cout << "----------------------------------------" << endl;
while (true){
    getline(cin, saveload);

    if (saveload == "open file"){
        string filenamet;
        cout << "file name? " << endl;
        getline(cin, filenamet, '*');
        ifstream loadFile;

        loadFile.open(filenamet, ifstream::in);

        cout << "the text you entered was: ";

        while (loadFile.good()){

            cout << (char)loadFile.get();

            Sleep(100);
        }

        cout << "" << endl;

        loadFile.close();

    }

    if (saveload == "text") {
        string filename;
        cout << "file name: " << endl;
        getline(cin, filename,'*');
        string textToSave;
        cout << "Enter your text: " << endl;
        getline(cin, textToSave,'*');

        ofstream saveFile(filename);

        saveFile << textToSave;

        saveFile.close();

    }
}
return 0;
}

Just take this code and change it to serve your purpose. DREAM BIG,THINK BIG, DO BIG

How to upper case every first letter of word in a string?

import org.apache.commons.lang.WordUtils;

public class CapitalizeFirstLetterInString {
    public static void main(String[] args) {
        // only the first letter of each word is capitalized.
        String wordStr = WordUtils.capitalize("this is first WORD capital test.");
        //Capitalize method capitalizes only first character of a String
        System.out.println("wordStr= " + wordStr);

        wordStr = WordUtils.capitalizeFully("this is first WORD capital test.");
        // This method capitalizes first character of a String and make rest of the characters lowercase
        System.out.println("wordStr = " + wordStr );
    }
}

Output :

This Is First WORD Capital Test.

This Is First Word Capital Test.

Use dynamic (variable) string as regex pattern in JavaScript

To create the regex from a string, you have to use JavaScript's RegExp object.

If you also want to match/replace more than one time, then you must add the g (global match) flag. Here's an example:

var stringToGoIntoTheRegex = "abc";
var regex = new RegExp("#" + stringToGoIntoTheRegex + "#", "g");
// at this point, the line above is the same as: var regex = /#abc#/g;

var input = "Hello this is #abc# some #abc# stuff.";
var output = input.replace(regex, "!!");
alert(output); // Hello this is !! some !! stuff.

JSFiddle demo here.


In the general case, escape the string before using as regex:

Not every string is a valid regex, though: there are some speciall characters, like ( or [. To work around this issue, simply escape the string before turning it into a regex. A utility function for that goes in the sample below:

function escapeRegExp(stringToGoIntoTheRegex) {
    return stringToGoIntoTheRegex.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
}

var stringToGoIntoTheRegex = escapeRegExp("abc"); // this is the only change from above
var regex = new RegExp("#" + stringToGoIntoTheRegex + "#", "g");
// at this point, the line above is the same as: var regex = /#abc#/g;

var input = "Hello this is #abc# some #abc# stuff.";
var output = input.replace(regex, "!!");
alert(output); // Hello this is !! some !! stuff.

JSFiddle demo here.



Note: the regex in the question uses the s modifier, which didn't exist at the time of the question, but does exist -- a s (dotall) flag/modifier in JavaScript -- today.

Where can I find php.ini?

You can get more info about your config files using something like:

$ -> php -i | ack config # Use fgrep -i if you don't have ack

Configure Command =>  './configure'  ...
Loaded Configuration File => /path/to/php.ini

Find multiple files and rename them in Linux

small script i wrote to replace all files with .txt extension to .cpp extension under /tmp and sub directories recursively

#!/bin/bash

for file in $(find /tmp -name '*.txt')
do
  mv $file $(echo "$file" | sed -r 's|.txt|.cpp|g')
done

Where to find htdocs in XAMPP Mac

There are two ways to find it:

One way is to open Finder>Applications>XAMPP(FolderNotTheInstaller)>htdocs

Another way is cmd+space and searches for manager-osx,

go to Welcome and click the Open Application Folder.

enter image description here

inherit from two classes in C#

An common alternative to inheritance is delegation (also called composition): X "has a" Y rather than X "is a" Y. So if A has functionality for dealing with Foos, and B has functionality for dealing with Bars, and you want both in C, then something like this:

public class A() {
  private FooManager fooManager = new FooManager(); // (or inject, if you have IoC)

  public void handleFoo(Foo foo) {
    fooManager.handleFoo(foo);
  }
}

public class B() {
  private BarManager barManager = new BarManager(); // (or inject, if you have IoC)

  public void handleBar(Bar bar) {
    barManager.handleBar(bar);
  }
}

public class C() {
  private FooManager fooManager = new FooManager(); // (or inject, if you have IoC)
  private BarManager barManager = new BarManager(); // (or inject, if you have IoC)

  ... etc
}

How to compare objects by multiple fields

Following blog given good chained Comparator example

http://www.codejava.net/java-core/collections/sorting-a-list-by-multiple-attributes-example

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

/**
 * This is a chained comparator that is used to sort a list by multiple
 * attributes by chaining a sequence of comparators of individual fields
 * together.
 *
 */
public class EmployeeChainedComparator implements Comparator<Employee> {

    private List<Comparator<Employee>> listComparators;

    @SafeVarargs
    public EmployeeChainedComparator(Comparator<Employee>... comparators) {
        this.listComparators = Arrays.asList(comparators);
    }

    @Override
    public int compare(Employee emp1, Employee emp2) {
        for (Comparator<Employee> comparator : listComparators) {
            int result = comparator.compare(emp1, emp2);
            if (result != 0) {
                return result;
            }
        }
        return 0;
    }
}

Calling Comparator:

Collections.sort(listEmployees, new EmployeeChainedComparator(
                new EmployeeJobTitleComparator(),
                new EmployeeAgeComparator(),
                new EmployeeSalaryComparator())
        );

SQL Server: combining multiple rows into one row

CREATE VIEW  [dbo].[ret_vwSalariedForReport]
AS
     WITH temp1 AS (SELECT
     salaried.*,
     operationalUnits.Title as OperationalUnitTitle
FROM
    ret_vwSalaried salaried LEFT JOIN
    prs_operationalUnitFeatures operationalUnitFeatures on salaried.[Guid] = operationalUnitFeatures.[FeatureGuid] LEFT JOIN 
    prs_operationalUnits operationalUnits ON operationalUnits.id = operationalUnitFeatures.OperationalUnitID 
    ), 
temp2 AS (SELECT
    t2.*,
    STUFF ((SELECT ' - ' + t1.OperationalUnitTitle
        FROM
            temp1 t1 
        WHERE t1.[ID] = t2.[ID]  
        For XML PATH('')), 2, 2, '') OperationalUnitTitles from temp1 t2) 
SELECT 
    [Guid],
    ID,
    Title,
    PersonnelNo,
    FirstName,
    LastName,
    FullName,
    Active,
    SSN,
    DeathDate,
    SalariedType,
    OperationalUnitTitles
FROM 
    temp2
GROUP BY 
    [Guid],
    ID,
    Title,
    PersonnelNo,
    FirstName,
    LastName,
    FullName,
    Active,
    SSN,
    DeathDate,
    SalariedType,
    OperationalUnitTitles

(SC) DeleteService FAILED 1072

make sure the service is stopped, the services control panel is closed, and no open file handles are open by the service.

Also make sure ProcessExplorer is not running.

Difference between java.exe and javaw.exe

java.exe is the command where it waits for application to complete untill it takes the next command. javaw.exe is the command which will not wait for the application to complete. you can go ahead with another commands.

ASP.NET email validator regex

For regex, I first look at this web site: RegExLib.com

Cannot instantiate the type List<Product>

Interfaces can not be directly instantiated, you should instantiate classes that implements such Interfaces.

Try this:

NameValuePair[] params = new BasicNameValuePair[] {
        new BasicNameValuePair("param1", param1),
        new BasicNameValuePair("param2", param2),
};

How to detect scroll direction

$(function(){
    var _top = $(window).scrollTop();
    var _direction;
    $(window).scroll(function(){
        var _cur_top = $(window).scrollTop();
        if(_top < _cur_top)
        {
            _direction = 'down';
        }
        else
        {
            _direction = 'up';
        }
        _top = _cur_top;
        console.log(_direction);
    });
});

Demo: http://jsfiddle.net/AlienWebguy/Bka6F/

How to get the first line of a file in a bash script?

Just echo the first list of your source file into your target file.

echo $(head -n 1 source.txt) > target.txt

cannot load such file -- bundler/setup (LoadError)

Bundler Version maybe cause the issue.

Please install bundler with other version number.

For example,

gem install bundler -v 1.0.10

Spring cannot find bean xml configuration file when it does exist

use it ApplicationContext context = new FileSystemXmlApplicationContext("Beans.xml");

How can I remove punctuation from input text in Java?

If you don't want to use RegEx (which seems highly unnecessary given your problem), perhaps you should try something like this:

public String modified(final String input){
    final StringBuilder builder = new StringBuilder();
    for(final char c : input.toCharArray())
        if(Character.isLetterOrDigit(c))
            builder.append(Character.isLowerCase(c) ? c : Character.toLowerCase(c));
    return builder.toString();
}

It loops through the underlying char[] in the String and only appends the char if it is a letter or digit (filtering out all symbols, which I am assuming is what you are trying to accomplish) and then appends the lower case version of the char.

Where does application data file actually stored on android device?

This is a simple way to identify the application related storage paths of a particular app.

Steps:

  1. Have the android device connected to your mac or android emulator open
  2. Open the terminal
  3. adb shell
  4. find .

The "find ." command will list all the files with their paths in the terminal.

./apex/com.android.media.swcodec
./apex/com.android.media.swcodec/etc
./apex/com.android.media.swcodec/etc/init.rc
./apex/com.android.media.swcodec/etc/seccomp_policy
./apex/com.android.media.swcodec/etc/seccomp_policy/mediaswcodec.policy
./apex/com.android.media.swcodec/etc/ld.config.txt
./apex/com.android.media.swcodec/etc/media_codecs.xml
./apex/com.android.media.swcodec/apex_manifest.json
./apex/com.android.media.swcodec/lib
./apex/com.android.media.swcodec/lib/[email protected]
./apex/com.android.media.swcodec/lib/libcodec2_soft_common.so
./apex/com.android.media.swcodec/lib/[email protected]
./apex/com.android.media.swcodec/lib/libcodec2_soft_vorbisdec.so
./apex/com.android.media.swcodec/lib/libcodec2_soft_h263dec.so
./apex/com.android.media.swcodec/lib/libhidltransport.so
./apex/com.android.media.swcodec/lib/libcodec2_soft_h263enc.so
./apex/com.android.media.swcodec/lib/libcodec2_vndk.so
./apex/com.android.media.swcodec/lib/[email protected]
./apex/com.android.media.swcodec/lib/libmedia_codecserviceregistrant.so
./apex/com.android.media.swcodec/lib/libhidlbase.so
./apex/com.android.media.swcodec/lib/libcodec2_soft_aacdec.so
./apex/com.android.media.swcodec/lib/libcodec2_soft_vp9dec.so
.....

After this, just search for your app with the bundle identifier and you can use adb pull command to download the files to your local directory.

How to set a Javascript object values dynamically?

myObj[prop] = value;

That should work. You mixed up the name of the variable and its value. But indexing an object with strings to get at its properties works fine in JavaScript.

gcc error: wrong ELF class: ELFCLASS64

You can specify '-m32' or '-m64' to select the compilation mode.

When dealing with autoconf (configure) scripts, I usually set CC="gcc -m64" (or CC="gcc -m32") in the environment so that everything is compiled with the correct bittiness. At least, usually...people find endless ways to make that not quite work, but my batting average is very high (way over 95%) with it.

How do I escape double and single quotes in sed?

The s/// command in sed allows you to use other characters instead of / as the delimiter, as in

sed 's#"http://www\.fubar\.com"#URL_FUBAR#g'

or

sed 's,"http://www\.fubar\.com",URL_FUBAR,g'

The double quotes are not a problem. For matching single quotes, switch the two types of quotes around. Note that a single quoted string may not contain single quotes (not even escaped ones).

The dots need to be escaped if sed is to interpret them as literal dots and not as the regular expression pattern . which matches any one character.

Can I pass an argument to a VBScript (vbs file launched with cscript)?

You can also use named arguments which are optional and can be given in any order.

Set namedArguments = WScript.Arguments.Named

Here's a little helper function:

Function GetNamedArgument(ByVal argumentName, ByVal defaultValue)
  If WScript.Arguments.Named.Exists(argumentName) Then
    GetNamedArgument = WScript.Arguments.Named.Item(argumentName) 
  Else  
    GetNamedArgument = defaultValue
  End If
End Function

Example VBS:

'[test.vbs]
testArg = GetNamedArgument("testArg", "-unknown-")
wscript.Echo now &": "& testArg

Example Usage:

test.vbs /testArg:123

Structuring online documentation for a REST API

That's a very complex question for a simple answer.

You may want to take a look at existing API frameworks, like Swagger Specification (OpenAPI), and services like apiary.io and apiblueprint.org.

Also, here's an example of the same REST API described, organized and even styled in three different ways. It may be a good start for you to learn from existing common ways.

At the very top level I think quality REST API docs require at least the following:

  • a list of all your API endpoints (base/relative URLs)
  • corresponding HTTP GET/POST/... method type for each endpoint
  • request/response MIME-type (how to encode params and parse replies)
  • a sample request/response, including HTTP headers
  • type and format specified for all params, including those in the URL, body and headers
  • a brief text description and important notes
  • a short code snippet showing the use of the endpoint in popular web programming languages

Also there are a lot of JSON/XML-based doc frameworks which can parse your API definition or schema and generate a convenient set of docs for you. But the choice for a doc generation system depends on your project, language, development environment and many other things.

Posting a File and Associated Data to a RESTful WebService preferably as JSON

Here is my approach API (i use example) - as you can see, you I don't use any file_id (uploaded file identifier to the server) in API:

  1. Create photo object on server:

     POST: /projects/{project_id}/photos   
     body: { name: "some_schema.jpg", comment: "blah"}
     response: photo_id
    
  2. Upload file (note that file is in singular form because it is only one per photo):

     POST: /projects/{project_id}/photos/{photo_id}/file
     body: file to upload
     response: -
    

And then for instance:

  1. Read photos list

     GET: /projects/{project_id}/photos
     response: [ photo, photo, photo, ... ] (array of objects)
    
  2. Read some photo details

     GET: /projects/{project_id}/photos/{photo_id}
     response: { id: 666, name: 'some_schema.jpg', comment:'blah'} (photo object)
    
  3. Read photo file

     GET: /projects/{project_id}/photos/{photo_id}/file
     response: file content
    

So the conclusion is that, first you create an object (photo) by POST, and then you send second request with the file (again POST). To not have problems with CACHE in this approach we assume that we can only delete old photos and add new - no update binary photo files (because new binary file is in fact... NEW photo). However if you need to be able to update binary files and cache them, then in point 4 return also fileId and change 5 to GET: /projects/{project_id}/photos/{photo_id}/files/{fileId}.

NPM global install "cannot find module"

For anyone else running into this, I had this problem due to my npm installing into a location that's not on my NODE_PATH.

[root@uberneek ~]# which npm
/opt/bin/npm
[root@uberneek ~]# which node
/opt/bin/node
[root@uberneek ~]# echo $NODE_PATH

My NODE_PATH was empty, and running npm install --global --verbose promised-io showed that it was installing into /opt/lib/node_modules/promised-io:

[root@uberneek ~]# npm install --global --verbose promised-io
npm info it worked if it ends with ok
npm verb cli [ '/opt/bin/node',
npm verb cli   '/opt/bin/npm',
npm verb cli   'install',
npm verb cli   '--global',
npm verb cli   '--verbose',
npm verb cli   'promised-io' ]
npm info using [email protected]
npm info using [email protected]
[cut]
npm info build /opt/lib/node_modules/promised-io
npm verb from cache /opt/lib/node_modules/promised-io/package.json
npm verb linkStuff [ true, '/opt/lib/node_modules', true, '/opt/lib/node_modules' ]
[cut]

My script fails on require('promised-io/promise'):

[neek@uberneek project]$ node buildscripts/stringsmerge.js 

module.js:340
    throw err;
          ^
Error: Cannot find module 'promised-io/promise'
    at Function.Module._resolveFilename (module.js:338:15)

I probably installed node and npm from source using configure --prefix=/opt. I've no idea why this has made them incapable of finding installed modules. The fix for now is to point NODE_PATH at the right directory:

export NODE_PATH=/opt/lib/node_modules

My require('promised-io/promise') now succeeds.

iOS 7 App Icons, Launch images And Naming Convention While Keeping iOS 6 Icons

Okay adding to @null's awesome post about using the Asset Catalog.

You may need to do the following to get the App's Icon linked and working for Ad-Hoc distributions / production to be seen in Organiser, Test flight and possibly unknown AppStore locations.


After creating the Asset Catalog, take note of the name of the Launch Images and App Icon names listed in the .xassets in Xcode.

By Default this should be

  • AppIcon
  • LaunchImage

[To see this click on your .xassets folder/icon in Xcode.] (this can be changed, so just take note of this variable for later)


What is created now each build is the following data structures in your .app:

For App Icons:

iPhone

  • AppIcon57x57.png (iPhone non retina) [Notice the Icon name prefix]
  • [email protected] (iPhone retina)

And the same format for each of the other icon resolutions.

iPad

  • AppIcon72x72~ipad.png (iPad non retina)
  • AppIcon72x72@2x~ipad.png (iPad retina)

(For iPad it is slightly different postfix)


Main Problem

Now I noticed that in my Info.plist in Xcode 5.0.1 it automatically attempted and failed to create a key for "Icon files (iOS 5)" after completing the creation of the Asset Catalog.

If it did create a reference successfully / this may have been patched by Apple or just worked, then all you have to do is review the image names to validate the format listed above.

Final Solution:

Add the following key to you main .plist

I suggest you open your main .plist with a external text editor such as TextWrangler rather than in Xcode to copy and paste the following key in.

<key>CFBundleIcons</key>
<dict>
    <key>CFBundlePrimaryIcon</key>
    <dict>
        <key>CFBundleIconFiles</key>
        <array>
            <string>AppIcon57x57.png</string>
            <string>[email protected]</string>
            <string>AppIcon72x72~ipad.png</string>
            <string>AppIcon72x72@2x~ipad.png</string>
        </array>
    </dict>
</dict>

Please Note I have only included my example resolutions, you will need to add them all.


If you want to add this Key in Xcode without an external editor, Use the following:

  • Icon files (iOS 5) - Dictionary
  • Primary Icon - Dictionary
  • Icon files - Array
  • Item 0 - String = AppIcon57x57.png And for each other item / app icon.

Now when you finally archive your project the final .xcarchive payload .plist will now include the above stated icon locations to build and use.

Do not add the following to any .plist: Just an example of what Xcode will now generate for your final payload

<key>IconPaths</key>
<array>
    <string>Applications/Example.app/AppIcon57x57.png</string>
    <string>Applications/Example.app/[email protected]</string>
    <string>Applications/Example.app/AppIcon72x72~ipad.png</string>
    <string>Applications/Example.app/AppIcon72x72@2x~ipad.png</string>
</array>

HTML button to NOT submit form

For accessibility reason, I could not pull it off with multiple type=submit buttons. The only way to work natively with a form with multiple buttons but ONLY one can submit the form when hitting the Enter key is to ensure that only one of them is of type=submit while others are in other type such as type=button. By this way, you can benefit from the better user experience in dealing with a form on a browser in terms of keyboard support.

Setting a PHP $_SESSION['var'] using jQuery

It works on firefox, if you change onClick() to click() in javascript part.

_x000D_
_x000D_
$("img.foo").click(function()_x000D_
{_x000D_
    // Get the src of the image_x000D_
    var src = $(this).attr("src");_x000D_
_x000D_
    // Send Ajax request to backend.php, with src set as "img" in the POST data_x000D_
    $.post("/backend.php", {"img": src});_x000D_
});
_x000D_
_x000D_
_x000D_

for each loop in Objective-C for accessing NSMutable dictionary

for (NSString* key in xyz) {
    id value = xyz[key];
    // do stuff
}

This works for every class that conforms to the NSFastEnumeration protocol (available on 10.5+ and iOS), though NSDictionary is one of the few collections which lets you enumerate keys instead of values. I suggest you read about fast enumeration in the Collections Programming Topic.

Oh, I should add however that you should NEVER modify a collection while enumerating through it.

How to assign a select result to a variable?

Try This

SELECT @PrimaryContactKey = c.PrimaryCntctKey
FROM tarcustomer c, tarinvoice i
WHERE i.custkey = c.custkey 
    AND i.invckey = @tmp_key

UPDATE tarinvoice SET confirmtocntctkey = @PrimaryContactKey 
WHERE invckey = @tmp_key
FETCH NEXT FROM @get_invckey INTO @tmp_key

You would declare this variable outside of your loop as just a standard TSQL variable.

I should also note that this is how you would do it for any type of select into a variable, not just when dealing with cursors.

Evaluating string "3*(4+2)" yield int 18

Short answer: I don't think so. C# .Net is compiled (to bytecode) and can't evaluate strings at runtime, as far as I know. JScript .Net can, however; but I would still advise you to code a parser and stack-based evaluator yourself.

Is a URL allowed to contain a space?

Why does it have to be encoded? A request looks like this:

GET /url HTTP/1.1
(Ignoring headers)

There are 3 fields separated by a white space. If you put a space in your url:

GET /url end_url HTTP/1.1

You know have 4 fields, the HTTP server will tell you it is an invalid request.

GET /url%20end_url HTTP/1.1

3 fields => valid

Note: in the query string (after ?), a space is usually encoded as a +

GET /url?var=foo+bar HTTP/1.1 

rather than

GET /url?var=foo%20bar HTTP/1.1 

Get mouse wheel events in jQuery?

Answers talking about "mousewheel" event are refering to a deprecated event. The standard event is simply "wheel". See https://developer.mozilla.org/en-US/docs/Web/Reference/Events/wheel

Building and running app via Gradle and Android Studio is slower than via Eclipse

The accepted answer is for older versions of android studio and most of them works still now. Updating android studio made it a little bit faster. Don't bother to specify heap size as it'll increase automatically with the increase of Xms and Xmx. Here's some modification with the VMoptions

  1. In bin folder there's a studio.vmoptions file to set the environment configuration. In my case this is studio64.vmoptions Add the following lines if they're not added already and save the file. In my case I've 8GB RAM.

    -Xms4096m
    -Xmx4096m
    -XX:MaxPermSize=2048m
    -XX:+CMSClassUnloadingEnabled
    -XX:+CMSPermGenSweepingEnabled 
    -XX:+HeapDumpOnOutOfMemoryError
    -Dfile.encoding=utf-8`
    
  2. Start android studio. Go to File-> Settings-> Build, Execution, Deployment-> Compiler

    • Check compile independent modules in parallel
    • In command-line Options write: --offline
    • Check Make project automatically
    • Check configure on demand

In case of using mac, at first I couldn't find the vmoptions. Anyway, here's a nice article about how we can change the vmoptions in MAC OSX. Quoting from this article here.

Open your terminal and put this command to open the vmoptions in MAC OSX:

open -e /Applications/Android\ Studio.app/Contents/bin/studio.vmoptions

Convert JavaScript string in dot notation into an object reference

A little more involved example with recursion.

function recompose(obj,string){
    var parts = string.split('.');
    var newObj = obj[parts[0]];
    if(parts[1]){
        parts.splice(0,1);
        var newString = parts.join('.');
        return recompose(newObj,newString);
    }
    return newObj;
}


var obj = { a: { b: '1', c: '2', d:{a:{b:'blah'}}}};

alert(recompose(obj,'a.d.a.b')); //blah

TypeError: object of type 'int' has no len() error assistance needed

Abstract:

The reason why you are getting this error message is because you are trying to call a method on an int type of a variable. This would work if would have called len() function on a list type of a variable. Let's examin the two cases:

Fail:

num = 10

print(len(num))

The above will produce an error similar to yours due to calling len() function on an int type of a variable;

Success:

data = [0, 4, 8, 9, 12]

print(len(data))

The above will work since you are calling a function on a list type of a variable;

Create HTTP post request and receive response using C# console application

HttpWebRequest request =(HttpWebRequest)WebRequest.Create("some url");
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.UserAgent = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 7.1; Trident/5.0)";
request.Accept = "/";
request.UseDefaultCredentials = true;
request.Proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;
doc.Save(request.GetRequestStream());
HttpWebResponse resp = request.GetResponse() as HttpWebResponse;

Hope it helps

How can I add a string to the end of each line in Vim?

:%s/$/\*/g

should work and so should :%s/$/*/g.

How can I extract the folder path from file path in Python?

Here is my little utility helper for splitting paths int file, path tokens:

import os    
# usage: file, path = splitPath(s)
def splitPath(s):
    f = os.path.basename(s)
    p = s[:-(len(f))-1]
    return f, p

ggplot geom_text font size control

Here are a few options for changing text / label sizes

library(ggplot2)

# Example data using mtcars

a <- aggregate(mpg ~ vs + am , mtcars, function(i) round(mean(i)))

p <- ggplot(mtcars, aes(factor(vs), y=mpg, fill=factor(am))) + 
            geom_bar(stat="identity",position="dodge") + 
            geom_text(data = a, aes(label = mpg), 
                            position = position_dodge(width=0.9),  size=20)

The size in the geom_text changes the size of the geom_text labels.

p <- p + theme(axis.text = element_text(size = 15)) # changes axis labels

p <- p + theme(axis.title = element_text(size = 25)) # change axis titles

p <- p + theme(text = element_text(size = 10)) # this will change all text size 
                                                             # (except geom_text)


For this And why size of 10 in geom_text() is different from that in theme(text=element_text()) ?

Yes, they are different. I did a quick manual check and they appear to be in the ratio of ~ (14/5) for geom_text sizes to theme sizes.

So a horrible fix for uniform sizes is to scale by this ratio

geom.text.size = 7
theme.size = (14/5) * geom.text.size

ggplot(mtcars, aes(factor(vs), y=mpg, fill=factor(am))) + 
  geom_bar(stat="identity",position="dodge") + 
  geom_text(data = a, aes(label = mpg), 
            position = position_dodge(width=0.9),  size=geom.text.size) + 
  theme(axis.text = element_text(size = theme.size, colour="black")) 

This of course doesn't explain why? and is a pita (and i assume there is a more sensible way to do this)

MySQL Removing Some Foreign keys

As everyone said above, you can easily delete a FK. However, I just noticed that it can be necessary to drop the KEY itself at some point. If you have any error message to create another index like the last one, I mean with the same name, it would be useful dropping everything related to that index.

ALTER TABLE your_table_with_fk
  drop FOREIGN KEY name_of_your_fk_from_show_create_table_command_result,
  drop KEY the_same_name_as_above

Download File to server from URL

private function downloadFile($url, $path)
{
    $newfname = $path;
    $file = fopen ($url, 'rb');
    if ($file) {
        $newf = fopen ($newfname, 'wb');
        if ($newf) {
            while(!feof($file)) {
                fwrite($newf, fread($file, 1024 * 8), 1024 * 8);
            }
        }
    }
    if ($file) {
        fclose($file);
    }
    if ($newf) {
        fclose($newf);
    }
}

How can I find out the total physical memory (RAM) of my linux box suitable to be parsed by a shell script?

These are the ways :

1. /proc/meminfo

MemTotal: 8152200 kB

MemFree: 760808 kB

You can write a code or script to parse it.

2. Use sysconf by using below macros

sysconf (_SC_PHYS_PAGES) * sysconf (_SC_PAGESIZE);

3. By using sysinfo system call

int sysinfo(struct sysinfo *info);

struct sysinfo { .

   .

   unsigned long totalram;  /*Total memory size to use */

   unsigned long freeram;   /* Available memory size*/

   .

   . 

  }; 

How to get response using cURL in PHP

If anyone else comes across this, I'm adding another answer to provide the response code or other information that might be needed in the "response".

http://php.net/manual/en/function.curl-getinfo.php

// init curl object        
$ch = curl_init();

// define options
$optArray = array(
    CURLOPT_URL => 'http://www.google.com',
    CURLOPT_RETURNTRANSFER => true
);

// apply those options
curl_setopt_array($ch, $optArray);

// execute request and get response
$result = curl_exec($ch);

// also get the error and response code
$errors = curl_error($ch);
$response = curl_getinfo($ch, CURLINFO_HTTP_CODE);

curl_close($ch);

var_dump($errors);
var_dump($response);

Output:

string(0) ""
int(200)

// change www.google.com to www.googlebofus.co
string(42) "Could not resolve host: www.googlebofus.co"
int(0)

ActiveRecord OR query

I'd like to add this is a solution to search multiple attributes of an ActiveRecord. Since

.where(A: param[:A], B: param[:B])

will search for A and B.

How do I kill a process using Vb.NET or C#?

Something like this will work:

foreach ( Process process in Process.GetProcessesByName( "winword" ) )
{
    process.Kill();
    process.WaitForExit();
}

Change image source in code behind - Wpf

None of the above solutions worked for me. But this did:

myImage.Source = new BitmapImage(new Uri(@"/Images/foo.png", UriKind.Relative));

When do I use super()?

You could use it to call a superclass's method (such as when you are overriding such a method, super.foo() etc) -- this would allow you to keep that functionality and add on to it with whatever else you have in the overriden method.