Programs & Examples On #Typeclass

Type classes in Haskell are a language mechanism to support ad hoc polymorphism. They also exist in Scala, Coq, and Isabelle.

How to fix warning from date() in PHP"

This just happen to me because in the php.ini the date.timezone was not set!


Using the php date() function triggered that warning.

Exception: "URI formats are not supported"

I solved the same error with the Path.Combine(MapPath()) to get the physical file path instead of the http:/// www one.

docker error: /var/run/docker.sock: no such file or directory

If you're using CentOS 7, and you've installed Docker via yum, don't forget to run:

$ sudo systemctl start docker
$ sudo systemctl enable docker

This will start the server, as well as re-start it automatically on boot.

ParseError: not well-formed (invalid token) using cElementTree

A solution for gottcha for me, using Python's ElementTree... this has the invalid token error:

# -*- coding: utf-8 -*-
import xml.etree.ElementTree as ET

xml = u"""<?xml version='1.0' encoding='utf8'?>
<osm generator="pycrocosm server" version="0.6"><changeset created_at="2017-09-06T19:26:50.302136+00:00" id="273" max_lat="0.0" max_lon="0.0" min_lat="0.0" min_lon="0.0" open="true" uid="345" user="john"><tag k="test" v="????? ?? ??? ???? ?????? ??????????? ????? ?? ????? ???" /><tag k="foo" v="bar" /><discussion><comment data="2015-01-01T18:56:48Z" uid="1841" user="metaodi"><text>Did you verify those street names?</text></comment></discussion></changeset></osm>"""

xmltest = ET.fromstring(xml.encode("utf-8"))

However, it works with the addition of a hyphen in the encoding type:

<?xml version='1.0' encoding='utf-8'?>

Most odd. Someone found this footnote in the python docs:

The encoding string included in XML output should conform to the appropriate standards. For example, “UTF-8” is valid, but “UTF8” is not.

How to resolve Nodejs: Error: ENOENT: no such file or directory

In my case the issue was caused by using a file path starting at the directory where the script was executing rather than at the root of the project.

My directory stucture was like this: projectfolder/ +-- package.json +-- scriptFolder/ ¦ +-- myScript.js

And I was calling fs.createReadStream('users.csv') instead of the correct fs.createReadStream('scriptFolder/users.csv')

How to handle :java.util.concurrent.TimeoutException: android.os.BinderProxy.finalize() timed out after 10 seconds errors?

One thing which is invariably true is that at this time, the device would be suffocating for some memory (which is usually the reason for GC to most likely get triggered).

As mentioned by almost all authors earlier, this issue surfaces when Android tries to run GC while the app is in background. In most of the cases where we observed it, user paused the app by locking their screen. This might also indicate memory leak somewhere in the application, or the device being too loaded already. So the only legitimate way to minimize it is:

  • to ensure there are no memory leaks, and
  • to reduce the memory footprint of the app in general.

How to kill a process running on particular port in Linux?

Use the command

 sudo netstat -plten |grep java

used grep java as tomcat uses java as their processes.

It will show the list of processes with port number and process id

tcp6       0      0 :::8080                 :::*                    LISTEN      
1000       30070621    16085/java

the number before /java is a process id. Now use kill command to kill the process

kill -9 16085

-9 implies the process will be killed forcefully.

position: fixed doesn't work on iPad and iPhone

Had the same issue on Iphone X. To fixed it I just add height to the container

top: 0;
height: 200px;
position: fixed;

I just added top:0 because i need my div to stay at top

ImportError: No module named 'pygame'

I was trying to figure this out for at least an hour. And you're right the problem is that the installation files are all for 32 bit.

Luckily I found a link to the 64 pygame download! Here it is:

Just pick the corresponding version according to your python version and it should work like magic. The installation feature will bring you to a bright-blue screen as the installation (at this point you know that the installation is correct for you.

Then go into the Python IDLE and type "import pygame" and you should not get any more errors.

Props go to @yuvi who shared the link with StackOverflow.

What is the correct way to restore a deleted file from SVN?

For completeness, this is what you would have found in the svn book, had you known what to look for. It's what you've discovered already:

Undoing Changes

Resurrecting Deleted Items

Same thing, from the more recent (and detailed) version of the book:

Undoing Changes

Resurrecting Deleted Items

Adding headers when using httpClient.GetAsync

You can add whatever headers you need to the HttpClient.

Here is a nice tutorial about it.

This doesn't just reference to POST-requests, you can also use it for GET-requests.

Creating stored procedure and SQLite?

Answer: NO

Here's Why ... I think a key reason for having stored procs in a database is that you're executing SP code in the same process as the SQL engine. This makes sense for database engines designed to work as a network connected service but the imperative for SQLite is much less given that it runs as a DLL in your application process rather than in a separate SQL engine process. So it makes more sense to implement all your business logic including what would have been SP code in the host language.

You can however extend SQLite with your own user defined functions in the host language (PHP, Python, Perl, C#, Javascript, Ruby etc). You can then use these custom functions as part of any SQLite select/update/insert/delete. I've done this in C# using DevArt's SQLite to implement password hashing.

Splitting strings using a delimiter in python

So, your input is 'dan|warrior|54' and you want "warrior". You do this like so:

>>> dan = 'dan|warrior|54'
>>> dan.split('|')[1]

Error loading the SDK when Eclipse starts

The issue is still coming for API 23. To get rid from this we have to uninstall android Wear packages for both API 22 and API 23 also (till current update).

enter image description here

Item frequency count in Python

Standard approach:

from collections import defaultdict

words = "apple banana apple strawberry banana lemon"
words = words.split()
result = defaultdict(int)
for word in words:
    result[word] += 1

print result

Groupby oneliner:

from itertools import groupby

words = "apple banana apple strawberry banana lemon"
words = words.split()

result = dict((key, len(list(group))) for key, group in groupby(sorted(words)))
print result

ImportError: No module named sqlalchemy

Very late to the party but hopefully this will help someone, was in the same situation for about a hour without any of the solutions mentioned above working. (On a Windows 10 machine).

In the Settings/Preferences dialog (Ctrl+Alt+S), from the side menu select Project: | Project Interpreter.

Check which packages you currently have installed (You need SQLAlchemy and Flask-SQLAlchemy). Double click on any package name, an 'Available Packages' menu will open.

Search for the missing package(s) and click install.

Cannot connect to SQL Server named instance from another SQL Server

  1. I had to specify a port in the SQL Configuration manager > TCP/IP
  2. Open the port on your firewall
  3. Then connect remotely using: "server name\other database instance,(port number)"
  4. Connected!

Allow scroll but hide scrollbar

Try this:


<div id="container">
    <div id="content">
        // Content here


    height: 100%;
    width: 100%;
    overflow: hidden;

    width: 100%;
    height: 99%;
    overflow: auto;
    padding-right: 15px;

html, body{
    height: 99%;

JSFiddle Demo

Tested on FF and Safari.

UICollectionView auto scroll to cell at IndexPath

this seemed to work for me, its similar to another answer but has some distinct differences:

- (void)viewDidLayoutSubviews
   [self.collectionView layoutIfNeeded];
   NSArray *visibleItems = [self.collectionView indexPathsForVisibleItems];
   NSIndexPath *currentItem = [visibleItems objectAtIndex:0];
   NSIndexPath *nextItem = [NSIndexPath indexPathForItem:someInt inSection:currentItem.section];

   [self.collectionView scrollToItemAtIndexPath:nextItem atScrollPosition:UICollectionViewScrollPositionNone animated:YES];

Extract every nth element of a vector

I think you are asking two things which are not necessarily the same

I want to extract every 6th element of the original

You can do this by indexing a sequence:

foo <- 1:120

I would like to create a vector in which each element is the i+6th element of another vector.

An easy way to do this is to supplement a logical factor with FALSEs until i+6:

foo <- 1:120
i <- 1
[1]   7  14  21  28  35  42  49  56  63  70  77  84  91  98 105 112 119

i <- 10
[1]  16  32  48  64  80  96 112

How to convert from java.sql.Timestamp to java.util.Date?

You should use a Calendar instead:

Calendar start = Calendar.getInstance();
start.setTimeInMillis( timeStampValue.getTime() );

Displaying the Indian currency symbol on a website


A simple jQuery plug-in for convert Rs. to standard Indian rupee symbol through out the web page. Simple to use and simple instillation

The Indian Rupee sign is the currency sign: ? for the Indian Rupee, the official currency of India. Designed by D. Udaya Kumar, it was presented to the public by the Government of India on 15 July 2010,[1] following its selection through an “open” competition among Indian residents. Before its adoption, the most commonly used symbols for the rupee were Rs, Re or, if the text was in an Indian language, an appropriate abbreviation in that language. The new sign relates solely to the Indian rupee; other countries that use a rupee, such as Sri Lanka, Pakistan and Nepal, still use the generic U+20A8 ? rupee sign character. The design resembles both the Devanagari letter "?" (ra) and the Latin capital letter "R", with a double horizontal line at the top.


  1. Download the “” and extract.
  2. copy images (“rupee.svg, rupee.gif”) to your images folder.
  3. cope scripts folder to your project path or else copy the .js files to your script folder.
  4. Download the “” and extract.
  5. copy images (“rupee.svg, rupee.gif”) to your images folder.
  6. cope scripts folder to your project path or else copy the .js files to your script folder.
  7. Include jQuery min and jQuery Ui to your page first

    eg: NB: use jQuery stable version only

  8. include the “indianRupee_v1.2.js” and “indianRupee_ctrl.js” after the jQuery library eg:

  9. Use Span tag to wrap Rs through out the web it will replace with the symbol eg: Rs 1280000/-


Pay Him Rs 1280000/-

Pay Him Rs 528500/-

Pay Him Rs 1250/-

Pay Him Rs 1280000/-


Plug-in Options:

$("body").indianRupee({ targets:"span",// use as default we can also use [p, div, h1 , li etc...] vector:"on"//[on/off] of [true/false] NB: {vector not support in Internet Explore } });

How to use store and use session variables across pages?

Every time you start a session (applies to PHP version 5.2.54), session_start() creates a new session id.

Here is the fix that worked for me.


session_id('mySessionID'); //SET id first before calling  session start

$name = "Nitin Hurkadli";
$_SESSION['username'] = $name;



$name = $_SESSION['username'];
echo "Hello  " . $name;

How to make a checkbox checked with jQuery?

You don't need to control your checkBoxes with jQuery. You can do it with some simple JavaScript.

This JS snippet should work fine:

document.TheFormHere.test.Value = true;

Hadoop: «ERROR : JAVA_HOME is not set»

The solution that worked for me was setting my JAVA_HOME in /etc/environment

Though JAVA_HOME can be set inside the /etc/profile files, the preferred location for JAVA_HOME or any system variable is /etc/environment.

Open /etc/environment in any text editor like nano or vim and add the following line:


Load the variables:

source /etc/environment

Check if the variable loaded correctly:


Cropping an UIImage

I use the method below.

  -(UIImage *)getNeedImageFrom:(UIImage*)image cropRect:(CGRect)rect
    CGSize cropSize = rect.size;
    CGFloat widthScale =  
    CGFloat heightScale = 
    cropSize = CGSizeMake(rect.size.width*widthScale,  
    CGPoint  pointCrop = CGPointMake(rect.origin.x*widthScale, 
    rect = CGRectMake(pointCrop.x, pointCrop.y, cropSize.width, 
    CGImageRef subImage = CGImageCreateWithImageInRect(image.CGImage, rect);
    UIImage *croppedImage = [UIImage imageWithCGImage:subImage];
    return croppedImage;


R: how to label the x-axis of a boxplot

If you read the help file for ?boxplot, you'll see there is a names= parameter.

     boxplot(apple, banana, watermelon, names=c("apple","banana","watermelon"))

enter image description here

npm - how to show the latest version of a package

As of October 2014:

npm view illustration

For latest remote version:

npm view <module_name> version  

Note, version is singular.

If you'd like to see all available (remote) versions, then do:

npm view <module_name> versions

Note, versions is plural. This will give you the full listing of versions to choose from.

To get the version you actually have locally you could use:

npm list --depth=0 | grep <module_name>

Note, even with package.json declaring your versions, the installed version might actually differ slightly - for instance if tilda was used in the version declaration

Should work across NPM versions 1.3.x, 1.4.x, 2.x and 3.x

php create object without class

you can always use new stdClass(). Example code:

   $object = new stdClass();
   $object->property = 'Here we go';


   object(stdClass)#2 (1) {
      string(10) "Here we go"

Also as of PHP 5.4 you can get same output with:

$object = (object) ['property' => 'Here we go'];

How to close a GUI when I push a JButton?

By using System.exit(0); you would close the entire process. Is that what you wanted or did you intend to close only the GUI window and allow the process to continue running?

The quickest, easiest and most robust way to simply close a JFrame or JPanel with the click of a JButton is to add an actionListener to the JButton which will execute the line of code below when the JButton is clicked:


If you are using the NetBeans GUI designer, the easiest way to add this actionListener is to enter the GUI editor window and double click the JButton component. Doing this will automatically create an actionListener and actionEvent, which can be modified manually by you.

How do I reference tables in Excel using VBA?

In addition, it's convenient to define variables referring to objects. For instance,

Sub CreateTable()
    Dim lo as ListObject
    Set lo = ActiveSheet.ListObjects.Add(xlSrcRange, Range("$B$1:$D$16"), , xlYes)
    lo.Name = "Table1"
    lo.TableStyle = "TableStyleLight2"
End Sub

You will probably find it advantageous at once. local class incompatible:

Serialisation in java is not meant as long term persistence or transport format - it is too fragile for this. With the slightest difference in class bytecode and JVM, your data is not readable anymore. Use XML or JSON data-binding for your task (XStream is fast and easy to use, and there are a ton of alternatives)

Getting strings recognized as variable names in R

If you want to use a string as a variable name, you can use assign:


assign(var1, c(5,4,5,6,7))


[1] 5 4 5 6 7

How can I put CSS and HTML code in the same file?

You can include CSS styles in an html document with <style></style> tags.


  .myClass { background: #f00; }

  .myOtherClass { font-size: 12px; }

Javascript: convert 24-hour time-of-day string to 12-hour time with AM/PM and no timezone

Nothing built in, my solution would be as follows :

function tConvert (time) {
  // Check correct time format and split into components
  time = time.toString ().match (/^([01]\d|2[0-3])(:)([0-5]\d)(:[0-5]\d)?$/) || [time];

  if (time.length > 1) { // If time format correct
    time = time.slice (1);  // Remove full string match value
    time[5] = +time[0] < 12 ? 'AM' : 'PM'; // Set AM/PM
    time[0] = +time[0] % 12 || 12; // Adjust hours
  return time.join (''); // return adjusted time or original string

tConvert ('18:00:00');

This function uses a regular expression to validate the time string and to split it into its component parts. Note also that the seconds in the time may optionally be omitted. If a valid time was presented, it is adjusted by adding the AM/PM indication and adjusting the hours.

The return value is the adjusted time if a valid time was presented or the original string.

Working example

(function() {_x000D_
  function tConvert(time) {_x000D_
    // Check correct time format and split into components_x000D_
    time = time.toString().match(/^([01]\d|2[0-3])(:)([0-5]\d)(:[0-5]\d)?$/) || [time];_x000D_
    if (time.length > 1) { // If time format correct_x000D_
      time = time.slice(1); // Remove full string match value_x000D_
      time[5] = +time[0] < 12 ? 'AM' : 'PM'; // Set AM/PM_x000D_
      time[0] = +time[0] % 12 || 12; // Adjust hours_x000D_
    return time.join(''); // return adjusted time or original string_x000D_
  var tel = document.getElementById('tests');_x000D_
  tel.innerHTML = tel.innerHTML.split(/\r*\n|\n\r*|\r/).map(function(v) {_x000D_
    return v ? v + ' => "' + tConvert(v.trim()) + '"' : v;_x000D_
<h3>tConvert tests : </h3>_x000D_
<pre id="tests">_x000D_

Java Replace Line In Text File

I was going to answer this question. Then I saw it get marked as a duplicate of this question, after I'd written the code, so I am going to post my solution here.

Keeping in mind that you have to re-write the text file. First I read the entire file, and store it in a string. Then I store each line as a index of a string array, ex line one = array index 0. I then edit the index corresponding to the line that you wish to edit. Once this is done I concatenate all the strings in the array into a single string. Then I write the new string into the file, which writes over the old content. Don't worry about losing your old content as it has been written again with the edit. below is the code I used.

public class App {

public static void main(String[] args) {

    String file = "file.txt";
    String newLineContent = "Hello my name is bob";
    int lineToBeEdited = 3;

    ChangeLineInFile changeFile = new ChangeLineInFile();
    changeFile.changeALineInATextFile(file, newLineContent, lineToBeEdited);



And the class.


public class ChangeLineInFile {

public void changeALineInATextFile(String fileName, String newLine, int lineNumber) {
        String content = new String();
        String editedContent = new String();
        content = readFile(fileName);
        editedContent = editLineInContent(content, newLine, lineNumber);
        writeToFile(fileName, editedContent);


private static int numberOfLinesInFile(String content) {
    int numberOfLines = 0;
    int index = 0;
    int lastIndex = 0;

    lastIndex = content.length() - 1;

    while (true) {

        if (content.charAt(index) == '\n') {


        if (index == lastIndex) {
            numberOfLines = numberOfLines + 1;


    return numberOfLines;

private static String[] turnFileIntoArrayOfStrings(String content, int lines) {
    String[] array = new String[lines];
    int index = 0;
    int tempInt = 0;
    int startIndext = 0;
    int lastIndex = content.length() - 1;

    while (true) {

        if (content.charAt(index) == '\n') {

            String temp2 = new String();
            for (int i = 0; i < index - startIndext; i++) {
                temp2 += content.charAt(startIndext + i);
            startIndext = index;
            array[tempInt - 1] = temp2;


        if (index == lastIndex) {


            String temp2 = new String();
            for (int i = 0; i < index - startIndext + 1; i++) {
                temp2 += content.charAt(startIndext + i);
            array[tempInt - 1] = temp2;



    return array;

private static String editLineInContent(String content, String newLine, int line) {

    int lineNumber = 0;
    lineNumber = numberOfLinesInFile(content);

    String[] lines = new String[lineNumber];
    lines = turnFileIntoArrayOfStrings(content, lineNumber);

    if (line != 1) {
        lines[line - 1] = "\n" + newLine;
    } else {
        lines[line - 1] = newLine;
    content = new String();

    for (int i = 0; i < lineNumber; i++) {
        content += lines[i];

    return content;

private static void writeToFile(String file, String content) {

    try (Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), "utf-8"))) {
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
    } catch (IOException e) {
        // TODO Auto-generated catch block

private static String readFile(String filename) {
    String content = null;
    File file = new File(filename);
    FileReader reader = null;
    try {
        reader = new FileReader(file);
        char[] chars = new char[(int) file.length()];;
        content = new String(chars);
    } catch (IOException e) {
    } finally {
        if (reader != null) {
            try {
            } catch (IOException e) {
                // TODO Auto-generated catch block
    return content;


registerForRemoteNotificationTypes: is not supported in iOS 8.0 and later

Building on @Prasath's answer. This is how you do it in Swift:

if application.respondsToSelector("isRegisteredForRemoteNotifications")
    // iOS 8 Notifications
    application.registerUserNotificationSettings(UIUserNotificationSettings(forTypes: (.Badge | .Sound | .Alert), categories: nil));
    // iOS < 8 Notifications
    application.registerForRemoteNotificationTypes(.Badge | .Sound | .Alert)

SQL Server database backup restore on lower version

You can use functionality called Export Data-Tier Application which generates .bacpac file consisting database schema and data.

On destination server, you can use Import Data-Tier Application option which creates and populates new database from pre-created .bacpac file

If you want just to transfer database schema, you can use Extract Data-Tier Application for creating file and Deploy Data-Tier Application for deploying created database schema.

I've tried this process on different versions of SQL Server from SQL 2014 to SQL 2012 and from SQL 2014 to SQL 2008R2 and worked well.

How do I implement basic "Long Polling"?

I think the client looks like a normal asynchronous AJAX request, but you expect it to take a "long time" to come back.

The server then looks like this.

while (!hasNewData())


So, the AJAX request goes to the server, probably including a timestamp of when it was last update so that your hasNewData() knows what data you have already got. The server then sits in a loop sleeping until new data is available. All the while, your AJAX request is still connected, just hanging there waiting for data. Finally, when new data is available, the server gives it to your AJAX request and closes the connection.

.NET Console Application Exit Event

If you are using a console application and you are pumping messages, can't you use the WM_QUIT message?

How to make a movie out of images in python

I use the ffmpeg-python binding. You can find more information here.

import ffmpeg
    .input('/path/to/jpegs/*.jpg', pattern_type='glob', framerate=25)

AngularJS - $ send data as json

Consider explicitly setting the header in the $ (I put application/json, as I am not sure which of the two versions in your example is the working one, but you can use application/x-www-form-urlencoded if it's the other one):

$"/customer/data/autocomplete", {term: searchString}, {headers: {'Content-Type': 'application/json'} })
        .then(function (response) {
            return response;

How can I check if a program exists from a Bash script?

The hash-variant has one pitfall: On the command line you can for example type in


to have process executed. For this the parent folder of one_folder must be in $PATH. But when you try to hash this command, it will always succeed:

hash one_folder/process; echo $? # will always output '0'

Cannot use a leading ../ to exit above the top directory

I had the problem occur on my system in a very strange way. In my system customers create products that sit inside a directory structure of product categories. So ProductA might sit in the folder CategoryInner inside the folder CategoryOuter. I had just added a feature where my URL would show the category nesting on the URL thusly:

Obviously the nesting on the URL was just for SEO purposes (and to show the user what category their product was sitting in. But when I used ResolveClientUrl on some URLs that used to work, it must've been confused by the extra fake pathing. The error message was popping up in the debugger on some line that was never the problem so it took me quite some time to figure out what was going on. I wnet through and removed all of my ResolveClientUrl calls that acted on anything that didn't start with a ~ and made the rest of the paths absolute paths.

What does -Xmn jvm option stands for

From GC Performance Tuning training documents of Oracle:

-Xmn[size]: Size of young generation heap space.

Applications with emphasis on performance tend to use -Xmn to size the young generation, because it combines the use of -XX:MaxNewSize and -XX:NewSize and almost always explicitly sets -XX:PermSize and -XX:MaxPermSize to the same value.

In short, it sets the NewSize and MaxNewSize values of New generation to the same value.

Python - add PYTHONPATH during command line module run

You may try this to execute a function inside your script

python -c "import sys; sys.path.append('/your/script/path'); import yourscript; yourscript.yourfunction()"

Regex to Match Symbols: !$%^&*()_+|~-=`{}[]:";'<>?,./

Replace all latters from any language in 'A', and if you wish for example all digits to 0:

return str.replace(/[^\s!-@[-`{-~]/g, "A").replace(/\d/g, "0");

Best way to use Google's hosted jQuery, but fall back to my hosted library on Google fail

The inability to load the resource from an external data store beyond your control is difficult. Looking for missing functions is totally fallacious as a means to avoid suffering a timeout, as described herein:

How to install Cmake C compiler and CXX compiler

Even though I had gcc already installed, I had to run

sudo apt-get install build-essential

to get rid of that error

Retina displays, high-res background images

Here's a solution that also includes High(er)DPI (MDPI) devices > ~160 dots per inch like quite a few non-iOS Devices (f.e.: Google Nexus 7 2012):

.box {
    background: url( 'img/box-bg.png' ) no-repeat top left;
    width: 200px;
    height: 200px;
@media only screen and ( -webkit-min-device-pixel-ratio: 1.3 ),
       only screen and (    min--moz-device-pixel-ratio: 1.3 ),
       only screen and (      -o-min-device-pixel-ratio: 2.6/2 ), /* returns 1.3, see Dev.Opera */
       only screen and (         min-device-pixel-ratio: 1.3 ),
       only screen and ( min-resolution: 124.8dpi ),
       only screen and ( min-resolution: 1.3dppx ) {

       .box {
           background: url( 'img/[email protected]' ) no-repeat top left / 200px 200px;


As @3rror404 included in his edit after receiving feedback from the comments, there's a world beyond Webkit/iPhone. One thing that bugs me with most solutions around so far like the one referenced as source above at CSS-Tricks, is that this isn't taken fully into account.
The original source went already further.

As an example the Nexus 7 (2012) screen is a TVDPI screen with a weird device-pixel-ratio of 1.325. When loading the images with normal resolution they are upscaled via interpolation and therefore blurry. For me applying this rule in the media query to include those devices succeeded in best customer feedback.

How to Edit a row in the datatable

Try the SetField method:

By passing column object :

table.Rows[rowIndex].SetField(column, value);

By Passing column index :

table.Rows[rowIndex].SetField(0 /*column index*/, value);

By Passing column name as string :

table.Rows[rowIndex].SetField("product_name" /*columnName*/, value);

How do I correct this Illegal String Offset?

I get the same error in WP when I use php ver 7.1.6 - just take your php version back to 7.0.20 and the error will disappear.

Reducing video size with same format and reducing frame size

I found myself wanting to do this too recently, so I created a tool called Shrinkwrap that uses FFmpeg to transcode videos, while preserving as much of the original metadata as possible (including file modification timestamps).

You can run it as a docker container:

docker run -v /path/to/your/videos:/vids bennetimo/shrinkwrap \
--input-extension mp4 --ffmpeg-opts crf=22,preset=fast /vids


  • /path/to/your/videos/ is where the videos are that you want to convert
  • --input-extension is the type of videos you want to process, here .mp4
  • --ffmpeg-opts is any arbitrary FFmpeg options you want to use to customise the transcode

Then it will recursively find all of the video files that match the extension and transcode them all into files of the same name with a -tc suffix.

For more configuration options, presets for GoPro etc, see the readme.

Hope this helps someone!

How do I count unique values inside a list

I'd use a set myself, but here's yet another way:

uniquewords = []
while True:
    ipta = raw_input("Word: ")
    if ipta == "":
    if not ipta in uniquewords:
print "There are", len(uniquewords), "unique words!"

Fragment Inside Fragment

AFAIK, fragments cannot hold other fragments.


With current versions of the Android Support package -- or native fragments on API Level 17 and higher -- you can nest fragments, by means of getChildFragmentManager(). Note that this means that you need to use the Android Support package version of fragments on API Levels 11-16, because even though there is a native version of fragments on those devices, that version does not have getChildFragmentManager().

calculating number of days between 2 columns of dates in data frame

Without your seeing your data (you can use the output of dput(head(survey)) to show us) this is a shot in the dark:

survey <- data.frame(date=c("2012/07/26","2012/07/25"),tx_start=c("2012/01/01","2012/01/01"))

survey$date_diff <- as.Date(as.character(survey$date), format="%Y/%m/%d")-
                  as.Date(as.character(survey$tx_start), format="%Y/%m/%d")
       date   tx_start date_diff
1 2012/07/26 2012/01/01  207 days
2 2012/07/25 2012/01/01  206 days

how to specify local modules as npm package dependencies

At work we have a common library that is used by a few different projects all in a single repository. Originally we used the published (private) version (npm install --save rp-utils) but that lead to a lot of needless version updates as we developed. The library lives in a sister directory to the applications and we are able to use a relative path instead of a version. Instead of "rp-utils": "^1.3.34" in package.json it now is:

  "dependencies": { ...
    "rp-utils": "../rp-utils",

the rp-utils directory contains a publishable npm package

How can I jump to class/method definition in Atom text editor?

I also had the same problem. And I find the solution:



Thanks to @Joost, install Atom package python-tools to make it work

Difference in boto3 between resource, client, and session?

I'll try and explain it as simple as possible. So there is no guarantee of the accuracy of the actual terms.

Session is where to initiate the connectivity to AWS services. E.g. following is default session that uses the default credential profile(e.g. ~/.aws/credentials, or assume your EC2 using IAM instance profile )

sqs = boto3.client('sqs')
s3 = boto3.resource('s3')

Because default session is limit to the profile or instance profile used, sometimes you need to use the custom session to override the default session configuration (e.g. region_name, endpoint_url, etc. ) e.g.

# custom resource session must use boto3.Session to do the override
my_west_session = boto3.Session(region_name = 'us-west-2')
my_east_session = boto3.Session(region_name = 'us-east-1')
backup_s3 = my_west_session.resource('s3')
video_s3 = my_east_session.resource('s3')

# you have two choices of create custom client session. 
backup_s3c = my_west_session.client('s3')
video_s3c = boto3.client("s3", region_name = 'us-east-1')

Resource : This is the high-level service class recommended to be used. This allows you to tied particular AWS resources and passes it along, so you just use this abstraction than worry which target services are pointed to. As you notice from the session part, if you have a custom session, you just pass this abstract object than worrying about all custom regions,etc to pass along. Following is a complicated example E.g.

import boto3 
my_west_session = boto3.Session(region_name = 'us-west-2')
my_east_session = boto3.Session(region_name = 'us-east-1')
backup_s3 = my_west_session.resource("s3")
video_s3 = my_east_session.resource("s3")
backup_bucket = backup_s3.Bucket('backupbucket') 
video_bucket = video_s3.Bucket('videobucket')

# just pass the instantiated bucket object
def list_bucket_contents(bucket):
   for object in bucket.objects.all():


Client is a low level class object. For each client call, you need to explicitly specify the targeting resources, the designated service target name must be pass long. You will lose the abstraction ability.

For example, if you only deal with the default session, this looks similar to boto3.resource.

import boto3 
s3 = boto3.client('s3')

def list_bucket_contents(bucket_name):
   for object in s3.list_objects_v2(Bucket=bucket_name) :


However, if you want to list objects from a bucket in different regions, you need to specify the explicit bucket parameter required for the client.

import boto3 
backup_s3 = my_west_session.client('s3',region_name = 'us-west-2')
video_s3 = my_east_session.client('s3',region_name = 'us-east-1')

# you must pass boto3.Session.client and the bucket name 
def list_bucket_contents(s3session, bucket_name):
   response = s3session.list_objects_v2(Bucket=bucket_name)
   if 'Contents' in response:
     for obj in response['Contents']:

list_bucket_contents(backup_s3, 'backupbucket')
list_bucket_contents(video_s3 , 'videobucket') 

How do I check if string contains substring?

you can define an extension method and use it later.

String.prototype.contains = function(it) 
   return this.indexOf(it) != -1; 

so that you can use in your page anywhere like:

var str="hello how are you";

which returns true.

Refer below post for more extension helper methods. Javascript helper methods

How do I make an http request using cookies on Android?

It turns out that Google Android ships with Apache HttpClient 4.0, and I was able to figure out how to do it using the "Form based logon" example in the HttpClient docs:

import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.cookie.Cookie;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;

 * A example that demonstrates how HttpClient APIs can be used to perform
 * form-based logon.
public class ClientFormLogin {

    public static void main(String[] args) throws Exception {

        DefaultHttpClient httpclient = new DefaultHttpClient();

        HttpGet httpget = new HttpGet("");

        HttpResponse response = httpclient.execute(httpget);
        HttpEntity entity = response.getEntity();

        System.out.println("Login form get: " + response.getStatusLine());
        if (entity != null) {
        System.out.println("Initial set of cookies:");
        List<Cookie> cookies = httpclient.getCookieStore().getCookies();
        if (cookies.isEmpty()) {
        } else {
            for (int i = 0; i < cookies.size(); i++) {
                System.out.println("- " + cookies.get(i).toString());

        HttpPost httpost = new HttpPost("" +
                "org=self_registered_users&" +
                "goto=/portal/dt&" +

        List <NameValuePair> nvps = new ArrayList <NameValuePair>();
        nvps.add(new BasicNameValuePair("IDToken1", "username"));
        nvps.add(new BasicNameValuePair("IDToken2", "password"));

        httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8));

        response = httpclient.execute(httpost);
        entity = response.getEntity();

        System.out.println("Login form get: " + response.getStatusLine());
        if (entity != null) {

        System.out.println("Post logon cookies:");
        cookies = httpclient.getCookieStore().getCookies();
        if (cookies.isEmpty()) {
        } else {
            for (int i = 0; i < cookies.size(); i++) {
                System.out.println("- " + cookies.get(i).toString());

        // When HttpClient instance is no longer needed, 
        // shut down the connection manager to ensure
        // immediate deallocation of all system resources

javascript cell number validation

This function check the special chars on key press and eliminates the value if it is not a number

function mobilevalid(id) {

    var feild = document.getElementById(id);

    if (isNaN(feild.value) == false) {
        if (feild.value.length == 1) {
            if (feild.value < 7) {
                feild.value = "";
        } else if (feild.value.length > 10) {
            feild.value = feild.value.substr(0, feild.value.length - 1);
        if (feild.value.charAt(0) < 7) {
            feild.value = "";
    } else {
        feild.value = "";


NSCameraUsageDescription in iOS 10.0 runtime crash?

Use these raw values and copy in info.plist

      <string>$(PRODUCT_NAME) calendar events</string>
      <string>$(PRODUCT_NAME) reminder use</string>
      <string>This app requires to access your photo library to show image on profile and send via chat</string>
      <string>This app requires to access your microphone to record video with your voice send via chat</string>
      <string>This app requires to access your photo library to show image on profile and send via chat</string>
       <string>$(PRODUCT_NAME) contact use</string>
      <string>$(PRODUCT_NAME) location use</string>
      <string>$(PRODUCT_NAME) location use</string>

How to call another components function in angular2

It depends on the relation between your components (parent / child) but the best / generic way to make communicate components is to use a shared service.

See this doc for more details:

That being said, you could use the following to provide an instance of the com1 into com2:

  <com1 #com1>...</com1>
  <com2 [com1ref]="com1">...</com2>

In com2, you can use the following:

export class com2{

    // i want to call function 1 from com1 here
} has not been called yet

In my case, I was trying to call plot(x, y) and lines(x, predict(yx.lm), col="red") in two separate chunks in Rmarkdown file. It worked without problems when running chunk by chunk, but the corresponding document wouldn't knit. After I moved all plotting calls within one chunk, problem was resolved.

SQL Plus change current directory

I think that the SQLPATH environment variable is the best way for this - if you have multiple paths, enter them separated by semi-colons (;). Keep in mind that if there are script files named the same in among the directories, the first one encountered (by order the paths are entered) will be executed, the second one will be ignored.

How to check if a column exists before adding it to an existing table in PL/SQL?

Normally, I'd suggest trying the ANSI-92 standard meta tables for something like this but I see now that Oracle doesn't support it.

-- this works against most any other database
    C.COLUMN_NAME = 'columnname'
    AND T.TABLE_NAME = 'tablename'

Instead, it looks like you need to do something like

-- Oracle specific table/column query
    TABLE_NAME = 'tablename'
    AND COLUMN_NAME = 'columnname'

I do apologize in that I don't have an Oracle instance to verify the above. If it does not work, please let me know and I will delete this post.

Copy entire directory contents to another directory?

If you're open to using a 3rd party library, check out javaxt-core. The class can be used to copy directories like this: input = new"/source"); output = new"/destination");
input.copyTo(output, true); //true to overwrite any existing files

You can also provide a file filter to specify which files you want to copy. There are more examples here:

Dynamic classname inside ngClass in angular 2

This one should work

<button [ngClass]="{[namespace + '-mybutton']: type === 'mybutton'}"></button>

but Angular throws on this syntax. I'd consider this a bug. See also

The others are invalid. You can't use [] together with {{}}. Either one or the other. {{}} binds the result stringified which doesn't lead to the desired result in this case because an object needs to be passed to ngClass.

Plunker example

As workaround the syntax shown by @A_Sing or

<button [ngClass]="type === 'mybutton' ? namespace + '-mybutton' : ''"></button>

can be used.

How to validate an Email in PHP?

See the notes at


As of PHP 5.3.0, the regex extension is deprecated in favor of the PCRE extension. Calling this function will issue an E_DEPRECATED notice. See the list of differences for help on converting to PCRE.


preg_match(), which uses a Perl-compatible regular expression syntax, is often a faster alternative to ereg().

Undefined reference to 'vtable for xxx'

it suggests that you fail to link the explicitly instantiated basetype public gameCore (whereas the header file forward declares it).

Since we know nothing about your build config/library dependencies, we can't really tell which link flags/source files are missing, but I hope the hint alone helps you fix ti.

Pass props in Link react-router


For approach mentioned like this in many answers,

        pathname: "/my-path",
        myProps: {
            hello: "Hello World"
    Press Me

I was getting error,

Object literal may only specify known properties, and 'myProps' does not exist in type 'LocationDescriptorObject | ((location: Location) => LocationDescriptor)'

Then I checked in the official documentation they have provided state for the same purpose.

So it worked like this,

        pathname: "/my-path",
        state: {
            hello: "Hello World"
    Press Me

And in your next component you can get this value as following,

componentDidMount() {
    console.log("received "+this.props.location.state.hello);

What is the use of static constructors?

No you can't overload it; a static constructor is useful for initializing any static fields associated with a type (or any other per-type operations) - useful in particular for reading required configuration data into readonly fields, etc.

It is run automatically by the runtime the first time it is needed (the exact rules there are complicated (see "beforefieldinit"), and changed subtly between CLR2 and CLR4). Unless you abuse reflection, it is guaranteed to run at most once (even if two threads arrive at the same time).

Converting string to numeric

As csgillespie said. stringsAsFactors is default on TRUE, which converts any text to a factor. So even after deleting the text, you still have a factor in your dataframe.

Now regarding the conversion, there's a more optimal way to do so. So I put it here as a reference :

> x <- factor(sample(4:8,10,replace=T))
> x
 [1] 6 4 8 6 7 6 8 5 8 4
Levels: 4 5 6 7 8
> as.numeric(levels(x))[x]
 [1] 6 4 8 6 7 6 8 5 8 4

To show it works.

The timings :

> x <- factor(sample(4:8,500000,replace=T))
> system.time(as.numeric(as.character(x)))
   user  system elapsed 
   0.11    0.00    0.11 
> system.time(as.numeric(levels(x))[x])
   user  system elapsed 
      0       0       0 

It's a big improvement, but not always a bottleneck. It gets important however if you have a big dataframe and a lot of columns to convert.

How to handle click event in Button Column in Datagridview?

You will add button column like this in your dataGridView

        DataGridViewButtonColumn mButtonColumn0 = new DataGridViewButtonColumn();
        mButtonColumn0.Name = "ColumnA";
        mButtonColumn0.Text = "ColumnA";

        if (dataGridView.Columns["ColumnA"] == null)
            dataGridView.Columns.Insert(2, mButtonColumn0);

Then you can add some actions inside cell click event. I found this is easiest way of doing it.

    private void dataGridView_CellClick(object sender, DataGridViewCellEventArgs e)

        int rowIndex = e.RowIndex;
        int columnIndex = e.ColumnIndex;

        if (dataGridView.Rows[rowIndex].Cells[columnIndex].Selected == true && dataGridView.Columns[columnIndex].Name == "ColumnA")
               //.... do any thing here.


I found that Cell Click event is automatically subscribed often. So I did not need this code below. However, if your cell click event is not subscribed, then add this line of code for your dataGridView.

     this.dataGridView.CellClick += new System.Windows.Forms.DataGridViewCellEventHandler(this.dataGridView_CellClick);

Check if a String contains numbers Java

.matches(".*\\d+.*") only works for numbers but not other symbols like // or * etc.

How to draw an overlay on a SurfaceView used by Camera on Android?

Try calling setWillNotDraw(false) from surfaceCreated:

public void surfaceCreated(SurfaceHolder holder) {
    try {
    } catch (Exception e) {
        Log.d(TAG,"Surface not created");

protected void onDraw(Canvas canvas) {

    canvas.drawRect(area, rectanglePaint);
    Log.w(this.getClass().getName(), "On Draw Called");

and calling invalidate from onTouchEvent:

public boolean onTouch(View v, MotionEvent event) {

    return true;

Import JSON file in React

Please store your JSON file with the .js extension and make sure that your JSON should be in same directory.

JavaScript: How to join / combine two arrays to concatenate into one array?

var a = ['a','b','c'];
var b = ['d','e','f'];
var c = a.concat(b); //c is now an an array with: ['a','b','c','d','e','f']
console.log( c[3] ); //c[3] will be 'd'

use of entityManager.createNativeQuery(query,foo.class)

JPA was designed to provide an automatic mapping between Objects and a relational database. Since Integer is not a persistant entity, why do you need to use JPA ? A simple JDBC request will work fine.

How do I best silence a warning about unused variables?

In GCC and Clang you can use the __attribute__((unused)) preprocessor directive to achieve your goal.
For example:

int foo (__attribute__((unused)) int bar) {
   return 0;

Understanding Fragment's setRetainInstance(boolean)

SetRetainInstance(true) allows the fragment sort of survive. Its members will be retained during configuration change like rotation. But it still may be killed when the activity is killed in the background. If the containing activity in the background is killed by the system, it's instanceState should be saved by the system you handled onSaveInstanceState properly. In another word the onSaveInstanceState will always be called. Though onCreateView won't be called if SetRetainInstance is true and fragment/activity is not killed yet, it still will be called if it's killed and being tried to be brought back.

Here are some analysis of the android activity/fragment hope it helps.

Capturing browser logs with Selenium WebDriver using Java

In a more concise way, you can do:

LogEntries logs = driver.manage().logs().get(LogType.BROWSER);

For me it worked wonderfully for catching JS errors in console. Then you can add some verification for its size. For example, if it is > 0, add some error output.

How to send Request payload to REST API in java?

The following code works for me.

//escape the double quotes in json string
String payload="{\"jsonrpc\":\"2.0\",\"method\":\"changeDetail\",\"params\":[{\"id\":11376}],\"id\":2}";
String requestUrl="";
sendPostRequest(requestUrl, payload);

method implementation:

public static String sendPostRequest(String requestUrl, String payload) {
    try {
        URL url = new URL(requestUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        connection.setRequestProperty("Accept", "application/json");
        connection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
        OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
        BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        StringBuffer jsonString = new StringBuffer();
        String line;
        while ((line = br.readLine()) != null) {
        return jsonString.toString();
    } catch (Exception e) {
            throw new RuntimeException(e.getMessage());


Return datetime object of previous month

A vectorized, pandas solution is very simple:

df['date'] - pd.DateOffset(months=1)

Finding even or odd ID values

For finding the even number we should use

select num from table where ( num % 2 ) = 0

How to cut first n and last n columns?

You can use Bash for that:

while read -a cols; do echo ${cols[@]:0:1} ${cols[@]:1,-1}; done < file.txt

Repeat rows of a data.frame

df <- data.frame(a = 1:2, b = letters[1:2]) 
df[rep(seq_len(nrow(df)), each = 2), ]

WPF ListView turn off selection

Use the code below:

    <Style TargetType="{x:Type ListViewItem}">
        <Setter Property="Background" Value="Transparent" />
        <Setter Property="Template">
                <ControlTemplate TargetType="{x:Type ListViewItem}">
                    <ContentPresenter />

How to determine device screen size category (small, normal, large, xlarge) using code?

In 2018, if you need Jeff's answer in Kotlin, here it is:

  private fun determineScreenSize(): String {
    // Thanks to
    val screenLayout = resources.configuration.screenLayout
    return when {
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_SMALL -> "Small"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_NORMAL -> "Normal"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_LARGE -> "Large"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_XLARGE -> "Xlarge"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_UNDEFINED -> "Undefined"
      else -> error("Unknown screenLayout: $screenLayout")

writing a batch file that opens a chrome URL

start "Chrome" "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --profile-directory="Profile 2"

start "webpage name" ""

start "Chrome" "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --profile-directory="Profile 3"

start "webpage name" ""

How can I find the link URL by link text with XPath?

Too late for you, but for anyone else with the same question...

//a[contains(text(), 'programming')]/@href

Of course, 'programming' can be any text fragment.

How can I output the value of an enum class in C++11

(I'm not allowed to comment yet.) I would suggest the following improvements to the already great answer of James McNellis:

template <typename Enumeration>
constexpr auto as_integer(Enumeration const value)
    -> typename std::underlying_type<Enumeration>::type
    static_assert(std::is_enum<Enumeration>::value, "parameter is not of type enum or enum class");
    return static_cast<typename std::underlying_type<Enumeration>::type>(value);


  • constexpr: allowing me to use an enum member value as compile-time array size
  • static_assert+is_enum: to 'ensure' compile-time that the function does sth. with enumerations only, as suggested

By the way I'm asking myself: Why should I ever use enum class when I would like to assign number values to my enum members?! Considering the conversion effort.

Perhaps I would then go back to ordinary enum as I suggested here: How to use enums as flags in C++?

Yet another (better) flavor of it without static_assert, based on a suggestion of @TobySpeight:

template <typename Enumeration>
constexpr std::enable_if_t<std::is_enum<Enumeration>::value,
std::underlying_type_t<Enumeration>> as_number(const Enumeration value)
    return static_cast<std::underlying_type_t<Enumeration>>(value);

Unable to launch the IIS Express Web server, Failed to register URL, Access is denied

Got the same issue where IIS express complained about http://localhost:50418/ and none of above solutions worked for me..

Went to projektFolder --> .vs --> config --> applicationhost.xml

In the tag <sites> I found that my web app had two bindnings registered.

<site name="myApp.Web" id="2">
    <application path="/" applicationPool="Clr4IntegratedAppPool">
        <virtualDirectory path="/" physicalPath="C:\git\myApp\myApp.Web" />
        <binding protocol="https" bindingInformation="*:44332:localhost" />
        <binding protocol="http" bindingInformation="*:50418:localhost" />

Removing the binding pointing to *:50418:localhost solved the issue.

Using VS2017 and IISExpress v10.

MVC 4 Razor File Upload

I think, better way is use HttpPostedFileBase in your controller or API. After this you can simple detect size, type etc.

File properties you can find here:

MVC3 How to check if HttpPostedFileBase is an image

For example ImageApi:

public ActionResult Index(HttpPostedFileBase file)  
    if (file != null && file.ContentLength > 0)  
            string path = Path.Combine(Server.MapPath("~/Images"),  

            ViewBag.Message = "Your message for success";  
        catch (Exception ex)  
            ViewBag.Message = "ERROR:" + ex.Message.ToString();  
        ViewBag.Message = "Please select file";  
    return View();  

Hope it help.

Returning a boolean from a Bash function

Use 0 for true and 1 for false.



isdirectory() {
  if [ -d "$1" ]
    # 0 = true
    return 0 
    # 1 = false
    return 1

if isdirectory $1; then echo "is directory"; else echo "nopes"; fi


From @amichair's comment, these are also possible

isdirectory() {
  if [ -d "$1" ]

isdirectory() {
  [ -d "$1" ]

What's the purpose of git-mv?

git mv oldname newname

is just shorthand for:

mv oldname newname
git add newname
git rm oldname

i.e. it updates the index for both old and new paths automatically.

MySQL and PHP - insert NULL rather than empty string

Check the variables before building the query, if they are empty, change them to the string NULL

Check if an element is present in an array

I benchmarked it multiple times on Google Chrome 52, but feel free to copypaste it into any other browser's console.

~ 1500 ms, includes (~ 2700 ms when I used the polyfill)

var array = [0,1,2,3,4,5,6,7,8,9]; 
var result = 0;

var start = new Date().getTime();
for(var i = 0; i < 10000000; i++)
  if(array.includes("test") === true){ result++; }
console.log(new Date().getTime() - start);

~ 1050 ms, indexOf

var array = [0,1,2,3,4,5,6,7,8,9]; 
var result = 0;

var start = new Date().getTime();
for(var i = 0; i < 10000000; i++)
  if(array.indexOf("test") > -1){ result++; }
console.log(new Date().getTime() - start);

~ 650 ms, custom function

function inArray(target, array)

/* Caching array.length doesn't increase the performance of the for loop on V8 (and probably on most of other major engines) */

  for(var i = 0; i < array.length; i++) 
    if(array[i] === target)
      return true;

  return false; 

var array = [0,1,2,3,4,5,6,7,8,9]; 
var result = 0;

var start = new Date().getTime();
for(var i = 0; i < 10000000; i++)
  if(inArray("test", array) === true){ result++; }
console.log(new Date().getTime() - start);

Does Java SE 8 have Pairs or Tuples?

It appears that the full example can be solved without the use of any kind of Pair structure. The key is to filter on the column indexes, with the predicate checking the entire column, instead of mapping the column indexes to the number of false entries in that column.

The code that does this is here:

        IntStream.range(0, acyclic_graph.length)
            .filter(i -> IntStream.range(0, acyclic_graph.length)
                                  .noneMatch(j -> acyclic_graph[j][i]))

This results in output of [0, 2, 4] which is I think the correct result requested by the OP.

Also note the boxed() operation that boxes the int values into Integer objects. This enables one to use the pre-existing toList() collector instead having to write out collector functions that do the boxing themselves.

Increment variable value by 1 ( shell programming)

you can use bc as it can also do floats

var=$(echo "1+2"|bc)

What is the difference between syntax and semantics in programming languages?

The syntax of a programming language is the form of its expressions, statements, and program units. Its semantics is the meaning of those expressions, statements, and program units. For example, the syntax of a Java while statement is

while (boolean_expr) statement

The semantics of this statement form is that when the current value of the Boolean expression is true, the embedded statement is executed. Then control implicitly returns to the Boolean expression to repeat the process. If the Boolean expression is false, control transfers to the statement following the while construct.

input type="submit" Vs button tag are they interchangeable?

If you are talking about <input type=button>, it won't automatically submit the form

if you are talking about the <button> tag, that's newer and doesn't automatically submit in all browsers.

Bottom line, if you want the form to submit on click in all browsers, use <input type="submit">

Converting from a string to boolean in Python?

If you like me just need boolean from variable which is string. You can use distils as mentioned earlier by @jzwiener. However I could not import and use the module as he suggested.

Instead I end up using it this way on python3.7

distutils string to bool in python

from distutils import util # to handle str to bool conversion
enable_deletion = 'False'
enable_deletion = bool(util.strtobool(enable_deletion))

distutils is part of the python std lib so no need of installation. Which is great!

Inserting a blank table row with a smaller height

Try this:

<td bgcolor="#FFFFFF" style="line-height:10px;" colspan=3>&nbsp;</td>

How to Free Inode Usage?

eaccelerator could be causing the problem since it compiles PHP into blocks...I've had this problem with an Amazon AWS server on a site with heavy load. Free up Inodes by deleting the eaccelerator cache in /var/cache/eaccelerator if you continue to have issues.

rm -rf /var/cache/eaccelerator/*

(or whatever your cache dir)

Run a php app using tomcat?

tomcat is designed as JSP servlet container. Apache is designed PHP web server. Use apache as web server, responding for PHP request, and direct JSP servlet request to tomcat container. should be better implementation.

How to save username and password in Git?

After reading the thread in full and experimenting with most of the answers to this question, I eventually found the procedure that works for me. I want to share it in case someone has to deal with a complex use case but still do not want to go through the full thread and the gitcredentials, gitcredentials-store etc. man pages, as I did.

Find below the procedure I suggest IF you (like me) have to deal with several repositories from several providers (GitLab, GitHub, Bitbucket, etc.) using several different username / password combinations. If you instead have only a single account to work with, then you might be better off employing the git config --global credential.helper store or git config --global "your username" etc. solutions that have been very well explained in previous answers.

My solution:

  1. unset global credentials helper, in case some former experimentation gets in the way :)

> git config --global --unset credentials.helper

  1. move to the root directory of your repo and disable the local credential helper (if needed)

> cd /path/to/my/repo

> git config --unset credential.helper

  1. create a file to store your repo's credentials into

> git config credential.helper 'store --file ~/.git_repo_credentials'

Note: this command creates a new file named ".git_repo_credentials" into your home directory, to which Git stores your credentials. If you do not specify a file name, Git uses the default ".git_credentials". In this case simply issuing the following command will do:

> git config credential.helper store

  1. set your username

git config credential.*.username my_user_name

Note: using "*" is usually ok if your repositories are from the same provider (e.g. GitLab). If instead your repositories are hosted by different providers then I suggest to explicitly set the link to the provider for every repository, like in the following example (for GitLab):

git config credential. my_user_name

At this point if you issue a command requiring your credentials (e.g. git pull) you will be asked for the password corresponding to "my_user_name". This is only required once because git stores the credentials to ".git_repo_credentials" and automatically uses the same data at subsequent accesses.

C++ [Error] no matching function for call to

You are trying to call DeckOfCards::shuffle with a deckOfCards parameter:

deckOfCards cardDeck; // create DeckOfCards object
cardDeck.shuffle(cardDeck); // shuffle the cards in the deck

But the method takes a vector<Card>&:

void deckOfCards::shuffle(vector<Card>& deck)

The compiler error messages are quite clear on this. I'll paraphrase the compiler as it talks to you.


[Error] no matching function for call to 'deckOfCards::shuffle(deckOfCards&)'


Hey, pal. You're trying to call a function called shuffle which apparently takes a single parameter of type reference-to-deckOfCards, but there is no such function.


[Note] candidate is:

In file included from main.cpp

[Note] void deckOfCards::shuffle(std::vector&)


I mean, maybe you meant this other function called shuffle, but that one takes a reference-tovector<something>.


[Note] no known conversion for argument 1 from 'deckOfCards' to 'std::vector&'

Which I'd be happy to call if I knew how to convert from a deckOfCards to a vector; but I don't. So I won't.

What's the difference between "Request Payload" vs "Form Data" as seen in Chrome dev tools Network tab

In Chrome, request with 'Content-Type:application/json' shows as Request PayedLoad and sends data as json object.

But request with 'Content-Type:application/x-www-form-urlencoded' shows Form Data and sends data as Key:Value Pair, so if you have array of object in one key it flats that key's value:

{ Id: 1, 


{ Id: 1, 
phones:[object object]
phones:[object object]

tslint / codelyzer / ng lint error: "for (... in ...) statements must be filtered with an if statement"

use Object.keys:

Object.keys(this.formErrors).map(key => {
  this.formErrors[key] = '';
  const control = form.get(key);

  if(control && control.dirty && !control.valid) {
    const messages = this.validationMessages[key];
    Object.keys(control.errors).map(key2 => {
      this.formErrors[key] += messages[key2] + ' ';

Problems with a PHP shell script: "Could not open input file"

Due to windows encoding issue for me

I experienced this "Could not open input file" error. Then I obtained the file using wget from another linux system, and the error did not occur.

The error ws only occurring for me when the file transited through windows.

Get specific ArrayList item

We print the value using mainList.get(index) where index starts with '0'. For Example: mainList.get(2) prints the 3rd element in the list.

OnChange event using React JS for drop down

Thank you Felix Kling, but his answer need a little change:

var MySelect = React.createClass({
 getInitialState: function() {
     return {
         value: 'select'
 change: function(event){
 render: function(){
           <select id="lang" onChange={this.change.bind(this)} value={this.state.value}>
              <option value="select">Select</option>
              <option value="Java">Java</option>
              <option value="C++">C++</option>
React.render(<MySelect />, document.body); 

How to create directory automatically on SD card

Don't forget to make sure that you have no special characters in your file/folder names. Happened to me with ":" when I was setting folder names using variable(s)

not allowed characters in file/folder names

" * / : < > ? \ |

U may find this code helpful in such a case.

The below code removes all ":" and replaces them with "-"

//actualFileName = "qwerty:asdfg:zxcvb" say...

    String[] tempFileNames;
    String tempFileName ="";
    String delimiter = ":";
    tempFileNames = actualFileName.split(delimiter);
    tempFileName = tempFileNames[0];
    for (int j = 1; j < tempFileNames.length; j++){
        tempFileName = tempFileName+" - "+tempFileNames[j];
    File file = new File(Environment.getExternalStorageDirectory(), "/MyApp/"+ tempFileName+ "/");
    if (!file.exists()) {
        if (!file.mkdirs()) {
        Log.e("TravellerLog :: ", "Problem creating Image folder");

How to horizontally center an element

I've created this example to show how to vertically and horizontally align.

The code is basically this:

#outer {
  position: relative;


#inner {
  margin: auto;
  position: absolute;
  right: 0;
  top: 0;
  bottom: 0;

And it will stay in the center even when you resize your screen.

How do you resize a form to fit its content automatically?

By using the various sizing properties (Dock, Anchor) or container controls (Panel, TableLayoutPanel, FlowLayoutPanel, etc.) you can only dictate the size from the outer control down to the inner controls. But there is nothing (working) within the .Net framework that allows to dictate the size of a container through the size of the child control. I also missed this a few times and tried the AutoSize property, but it never worked.

So all you can do is trying to get this stuff done manually, sorry.

Illegal mix of collations error in MySql

HAvING TheCount > 4 AND username IN (SELECT username FROM users WHERE gender=1)

but why i am answering, you dont voted me as right answer :)

WPF User Control Parent

DependencyObject GetTopParent(DependencyObject current)
    while (VisualTreeHelper.GetParent(current) != null)
        current = VisualTreeHelper.GetParent(current);
    return current;

DependencyObject parent = GetTopParent(thisUserControl);

How to fill background image of an UIView

You need to process the image beforehand, to make a centered and stretched image. Try this:

[[UIImage imageNamed:@"image.png"] drawInRect:self.view.bounds];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

self.view.backgroundColor = [UIColor colorWithPatternImage:image];

How to prevent IFRAME from redirecting top-level window

By doing so you'd be able to control any action of the framed page, which you cannot. Same-domain origin policy applies.

C# windows application Event: CLR20r3 on application start

Have been fighting this all morning and now have it solved and why it happened. Posting with the hope it helps others

I installed the Krypton.Toolkit which added the tools to the Visual studio toolbox automatically. I then added the tools to the designer, which automatically added the dll to the projrect references, however the toolkit was marked as CopyLocal=false

I built an installer, using all dlls in the release build folder (of course the above dll wasn't there).

Setting copylocal=true, then rebuilding the installer, everything worked fine.

Add space between <li> elements

You can use the margin property: {
   margin:0 0 10px 0;   


JavaScriptSerializer - JSON serialization of enum as string

ASP.NET Core way:

public class Startup
  public IServiceProvider ConfigureServices(IServiceCollection services)
    services.AddMvc().AddJsonOptions(options =>
      options.SerializerSettings.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter());

How can I set a proxy server for gem?

In Addition to @Yifei answer. If you have special character like @, &, $

You have to go with percent-encode | encode the special characters. E.g. instead of this:

http://foo:B@[email protected]:80

you write this:

http://foo:B%[email protected]:80

So @ gets replaced with %40.

What's an object file in C?

An object file is the real output from the compilation phase. It's mostly machine code, but has info that allows a linker to see what symbols are in it as well as symbols it requires in order to work. (For reference, "symbols" are basically names of global objects, functions, etc.)

A linker takes all these object files and combines them to form one executable (assuming that it can, ie: that there aren't any duplicate or undefined symbols). A lot of compilers will do this for you (read: they run the linker on their own) if you don't tell them to "just compile" using command-line options. (-c is a common "just compile; don't link" option.)

Tomcat: LifecycleException when deploying

I done in same way and its working now. Actually web.xml file having wrong url-pattern. you can remove one url-pattern either annotation form servlet or web.xml.It worked for me.

Check with jquery if div has overflowing elements

I fixed this by adding another div in the one that overflows. Then you compare the heights of the 2 divs.

<div class="AAAA overflow-hidden" style="height: 20px;" >
    <div class="BBBB" >
        Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

and the js

    if ($('.AAAA').height() < $('.BBBB').height()) {
        console.log('we have overflow')
    } else {
        console.log('NO overflow')

This looks easier...

Change date format in a Java string

   String str = "2000-12-12";
   Date dt = null;
   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");

         dt = formatter.parse(str);
    catch (Exception e)

    JOptionPane.showMessageDialog(null, formatter.format(dt));

C++11 rvalues and move semantics confusion (return statement)

The simple answer is you should write code for rvalue references like you would regular references code, and you should treat them the same mentally 99% of the time. This includes all the old rules about returning references (i.e. never return a reference to a local variable).

Unless you are writing a template container class that needs to take advantage of std::forward and be able to write a generic function that takes either lvalue or rvalue references, this is more or less true.

One of the big advantages to the move constructor and move assignment is that if you define them, the compiler can use them in cases were the RVO (return value optimization) and NRVO (named return value optimization) fail to be invoked. This is pretty huge for returning expensive objects like containers & strings by value efficiently from methods.

Now where things get interesting with rvalue references, is that you can also use them as arguments to normal functions. This allows you to write containers that have overloads for both const reference (const foo& other) and rvalue reference (foo&& other). Even if the argument is too unwieldy to pass with a mere constructor call it can still be done:

std::vector vec;
for(int x=0; x<10; ++x)
    // automatically uses rvalue reference constructor if available
    // because MyCheapType is an unamed temporary variable

std::vector vec;
for(int x=0; x<10; ++x)
    MyExpensiveType temp(1.0, 3.0);

    // old way, passed via const reference, expensive copy

    // new way, passed via rvalue reference, cheap move
    // just don't use temp again,  not difficult in a loop like this though . . .

The STL containers have been updated to have move overloads for nearly anything (hash key and values, vector insertion, etc), and is where you will see them the most.

You can also use them to normal functions, and if you only provide an rvalue reference argument you can force the caller to create the object and let the function do the move. This is more of an example than a really good use, but in my rendering library, I have assigned a string to all the loaded resources, so that it is easier to see what each object represents in the debugger. The interface is something like this:

TextureHandle CreateTexture(int width, int height, ETextureFormat fmt, string&& friendlyName)
    std::unique_ptr<TextureObject> tex = D3DCreateTexture(width, height, fmt);
    tex->friendlyName = std::move(friendlyName);
    return tex;

It is a form of a 'leaky abstraction' but allows me to take advantage of the fact I had to create the string already most of the time, and avoid making yet another copying of it. This isn't exactly high-performance code but is a good example of the possibilities as people get the hang of this feature. This code actually requires that the variable either be a temporary to the call, or std::move invoked:

// move from temporary
TextureHandle htex = CreateTexture(128, 128, A8R8G8B8, string("Checkerboard"));


// explicit move (not going to use the variable 'str' after the create call)
string str("Checkerboard");
TextureHandle htex = CreateTexture(128, 128, A8R8G8B8, std::move(str));


// explicitly make a copy and pass the temporary of the copy down
// since we need to use str again for some reason
string str("Checkerboard");
TextureHandle htex = CreateTexture(128, 128, A8R8G8B8, string(str));

but this won't compile!

string str("Checkerboard");
TextureHandle htex = CreateTexture(128, 128, A8R8G8B8, str);

Python read in string from file and split it into values

Something like this - for each line read into string variable a:

>>> a = "123,456"
>>> b = a.split(",")
>>> b
['123', '456']
>>> c = [int(e) for e in b]
>>> c
[123, 456]
>>> x, y = c
>>> x
>>> y

Now you can do what is necessary with x and y as assigned, which are integers.

Create Directory When Writing To File In Node.js

My advise is: try not to rely on dependencies when you can easily do it with few lines of codes

Here's what you're trying to achieve in 14 lines of code:

fs.isDir = function(dpath) {
    try {
        return fs.lstatSync(dpath).isDirectory();
    } catch(e) {
        return false;
fs.mkdirp = function(dirname) {
    dirname = path.normalize(dirname).split(path.sep);
        var pathInQuestion = dirname.slice(0,index+1).join(path.sep);
        if((!fs.isDir(pathInQuestion)) && pathInQuestion) fs.mkdirSync(pathInQuestion);

Can I get Unix's pthread.h to compile in Windows?

Just pick up the TDM-GCC 64x package. (It constains both the 32 and 64 bit versions of the MinGW toolchain and comes within a neat installer.) More importantly, it contains something called the "winpthread" library.

It comprises of the pthread.h header, libwinpthread.a, libwinpthread.dll.a static libraries for both 32-bit and 64-bit and the required .dlls libwinpthread-1.dll and libwinpthread_64-1.dll(this, as of 01-06-2016).

You'll need to link to the libwinpthread.a library during build. Other than that, your code can be the same as for native Pthread code on Linux. I've so far successfully used it to compile a few basic Pthread programs in 64-bit on windows.

Alternatively, you can use the following library which wraps the windows threading API into the pthreads API: pthreads-win32.

The above two seem to be the most well known ways for this.

Hope this helps.

Change the icon of the exe file generated from Visual Studio 2010

I found it easier to edit the project file directly e.g. YourApp.csproj.

You can do this by modifying ApplicationIcon property element:


Also, if you create an MSI installer for your application e.g. using WiX, you can use the same icon again for display in Add/Remove Programs. See tip 5 here.

"No such file or directory" but it exists

Hit this error trying to run terraform/terragrunt (Single go binary).

Using which terragrunt to find where executable was, got strange error when running it in local dir or with full path

bash: ./terragrunt: No such file or directory

Problem was that there was two installations of terragrunt, used brew uninstall terragrunt to remove one fixed it.

After removing the one, which terragrunt showed the new path /usr/bin/terragrunt everything worked fine.

How to test if a list contains another list?

Smallest code:

def contains(a,b):

git ignore exception

Just add ! before an exclusion rule.

According to the gitignore man page:

Patterns have the following format:


  • An optional prefix ! which negates the pattern; any matching file excluded by a previous pattern will become included again. If a negated pattern matches, this will override lower precedence patterns sources.

GET URL parameter in PHP

To make sure you're always on the safe side, without getting all kinds of unwanted code insertion use FILTERS:

echo filter_input(INPUT_GET,"link",FILTER_SANITIZE_STRING);

More reading on function filter_input, or check out the description of the different filters

Get average color of image via Javascript

Less accurate but fastest way to get average color of the image with datauri support:

function get_average_rgb(img) {
    var context = document.createElement('canvas').getContext('2d');
    if (typeof img == 'string') {
        var src = img;
        img = new Image;
        img.setAttribute('crossOrigin', ''); 
        img.src = src;
    context.imageSmoothingEnabled = true;
    context.drawImage(img, 0, 0, 1, 1);
    return context.getImageData(1, 1, 1, 1).data.slice(0,3);

Importing class/java files in Eclipse

create a new java project in Eclipse and copy .java files to its src directory, if you don't know where those source files should be placed, right click on the root of the project and choose new->class to create a test class and see where its .java file is placed, then put other files with it, in the same directory, you may have to adjust the package in those source files according to the new project directory structure.

if you use external libraries in your code, you have two options: either copy / download jar files or use maven if you use maven you'll have to create the project at maven project in the first place, creating java projects as maven projects are the way to go anyway but that's for another post...

Determining if Swift dictionary contains key and obtaining any of its values

You don't need any special code to do this, because it is what a dictionary already does. When you fetch dict[key] you know whether the dictionary contains the key, because the Optional that you get back is not nil (and it contains the value).

So, if you just want to answer the question whether the dictionary contains the key, ask:

let keyExists = dict[key] != nil

If you want the value and you know the dictionary contains the key, say:

let val = dict[key]!

But if, as usually happens, you don't know it contains the key - you want to fetch it and use it, but only if it exists - then use something like if let:

if let val = dict[key] {
    // now val is not nil and the Optional has been unwrapped, so use it

Return 0 if field is null in MySQL

You can try something like this


Attribute X is assumed to be empty if it is an empty String, so after that you can declare as a zero instead of last value. In another case, it would remain its original value.

Anyway, just to give another way to do that.

The 'packages' element is not declared

You can also find a copy of the nuspec.xsd here as it seems to no longer be available:

Can I use an image from my local file system as background in HTML?

Jeff Bridgman is correct. All you need is
background: url('pic.jpg')
and this assumes that pic is in the same folder as your html.

Also, Roberto's answer works fine. Tested in Firefox, and IE. Thanks to Raptor for adding formatting that displays full picture fit to screen, and without scrollbars... In a folder f, on the desktop is this html and a picture, pic.jpg, using your userid. Make those substitutions in the below:

        body {

        background: url('file:///C:/Users/userid/desktop/f/pic.jpg') no-repeat center center fixed;

        background-size: cover; /* for IE9+, Safari 4.1+, Chrome 3.0+, Firefox 3.6+ */
        -webkit-background-size: cover; /* for Safari 3.0 - 4.0 , Chrome 1.0 - 3.0 */
        -moz-background-size: cover; /* optional for Firefox 3.6 */ 
        -o-background-size: cover; /* for Opera 9.5 */
        margin: 0; /* to remove the default white margin of body */
        padding: 0; /* to remove the default white margin of body */
        overflow: hidden;

C++ IDE for Linux?

Having been raised on Visual Studio, I've found the relatively young Code::Blocks to be very familiar.

Python: Random numbers into a list

This is way late but in-case someone finds this helpful.

You could use list comprehension.

rand = [random.randint(0, 100) for x in range(1, 11)]


[974, 440, 305, 102, 822, 128, 205, 362, 948, 751]


NuGet Packages are missing

BEWARE - this updates packages for the entire solution not just the project.

If you have one more missing nuget package that giving your error while building your solution use following command using Nuget Command Console from Tools > Nuget Package Manager > Package Manager Console. It will reinstall your all current packages.

Update-Package –reinstall


You can pass specific project name as a parameter.

Update-Package –reinstall -ProjectName SampleApp

Pod install is staying on "Setting up CocoaPods Master repo"

What I tried and faster than clonning the repo:

  1. pod setup
  2. Ctrl +C after creating the master directory
  3. Download .zip from master
  4. Copy the content to ~/.cocoapods/repos
  5. pod install --no-repo-update in my project folder

After that I finally could see the pods being installed

Good luck!

EDIT: The zip size is 144 MB (Jul 6 2017)

Favicon dimensions?

16x16 pixels, *.ico format.

Tomcat 404 error: The origin server did not find a current representation for the target resource or is not willing to disclose that one exists

Hope this helps. From eclipse, you right click the project -> Run As -> Run on Server and then it worked for me. I used Eclipse Jee Neon and Apache Tomcat 9.0. :)

I just removed the head portion in index.html file and it worked fine.This is the head tag in html file

Load an image from a url into a PictureBox

Here's the solution I use. I can't remember why I couldn't just use the PictureBox.Load methods. I'm pretty sure it's because I wanted to properly scale & center the downloaded image into the PictureBox control. If I recall, all the scaling options on PictureBox either stretch the image, or will resize the PictureBox to fit the image. I wanted a properly scaled and centered image in the size I set for PictureBox.

Now, I just need to make a async version...

Here's my methods:

   #region Image Utilities

    /// <summary>
    /// Loads an image from a URL into a Bitmap object.
    /// Currently as written if there is an error during downloading of the image, no exception is thrown.
    /// </summary>
    /// <param name="url"></param>
    /// <returns></returns>
    public static Bitmap LoadPicture(string url)
        System.Net.HttpWebRequest wreq;
        System.Net.HttpWebResponse wresp;
        Stream mystream;
        Bitmap bmp;

        bmp = null;
        mystream = null;
        wresp = null;
            wreq = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(url);
            wreq.AllowWriteStreamBuffering = true;

            wresp = (System.Net.HttpWebResponse)wreq.GetResponse();

            if ((mystream = wresp.GetResponseStream()) != null)
                bmp = new Bitmap(mystream);
            // Do nothing... 
            if (mystream != null)

            if (wresp != null)

        return (bmp);

    /// <summary>
    /// Takes in an image, scales it maintaining the proper aspect ratio of the image such it fits in the PictureBox's canvas size and loads the image into picture box.
    /// Has an optional param to center the image in the picture box if it's smaller then canvas size.
    /// </summary>
    /// <param name="image">The Image you want to load, see LoadPicture</param>
    /// <param name="canvas">The canvas you want the picture to load into</param>
    /// <param name="centerImage"></param>
    /// <returns></returns>

    public static Image ResizeImage(Image image, PictureBox canvas, bool centerImage ) 
        if (image == null || canvas == null)
            return null;

        int canvasWidth = canvas.Size.Width;
        int canvasHeight = canvas.Size.Height;
        int originalWidth = image.Size.Width;
        int originalHeight = image.Size.Height;

        System.Drawing.Image thumbnail =
            new Bitmap(canvasWidth, canvasHeight); // changed parm names
        System.Drawing.Graphics graphic =

        graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
        graphic.SmoothingMode = SmoothingMode.HighQuality;
        graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
        graphic.CompositingQuality = CompositingQuality.HighQuality;

        /* ------------------ new code --------------- */

        // Figure out the ratio
        double ratioX = (double)canvasWidth / (double)originalWidth;
        double ratioY = (double)canvasHeight / (double)originalHeight;
        double ratio = ratioX < ratioY ? ratioX : ratioY; // use whichever multiplier is smaller

        // now we can get the new height and width
        int newHeight = Convert.ToInt32(originalHeight * ratio);
        int newWidth = Convert.ToInt32(originalWidth * ratio);

        // Now calculate the X,Y position of the upper-left corner 
        // (one of these will always be zero)
        int posX = Convert.ToInt32((canvasWidth - (image.Width * ratio)) / 2);
        int posY = Convert.ToInt32((canvasHeight - (image.Height * ratio)) / 2);

        if (!centerImage)
            posX = 0;
            posY = 0;
        graphic.Clear(Color.White); // white padding
        graphic.DrawImage(image, posX, posY, newWidth, newHeight);

        /* ------------- end new code ---------------- */

        System.Drawing.Imaging.ImageCodecInfo[] info =
        EncoderParameters encoderParameters;
        encoderParameters = new EncoderParameters(1);
        encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality,

        Stream s = new System.IO.MemoryStream();
        thumbnail.Save(s, info[1],

        return Image.FromStream(s);


Here's the required includes. (Some might be needed by other code, but including all to be safe)

using System.Windows.Forms;
using System.Drawing.Drawing2D;
using System.IO;
using System.Drawing.Imaging;
using System.Text.RegularExpressions;
using System.Drawing;

How I generally use it:

 ImageUtil.ResizeImage(ImageUtil.LoadPicture( "http://someurl/img.jpg", pictureBox1, true);

How to set a single, main title above all the subplots with Pyplot?

Use pyplot.suptitle or Figure.suptitle:

import matplotlib.pyplot as plt
import numpy as np

for i in range(1,5):

fig.suptitle('Main title') # or plt.suptitle('Main title')

enter image description here

Importing large sql file to MySql via command line

The solution I use for large sql restore is a mysqldumpsplitter script. I split my sql.gz into individual tables. then load up something like mysql workbench and process it as a restore to the desired schema.

Here is the script

And this works for larger sql restores, my average on one site I work with is a 2.5gb sql.gz file, 20GB uncompressed, and ~100Gb once restored fully

Bash script to check running process

Those are helpful hints. I just needed to know if a service was running when I started the script, so I could leave the service in the same state when I left. I ended up using this:

   HTTPDSERVICE=$(ps -A | grep httpd | head -1)

   [ -z "$HTTPDSERVICE" ] &&  echo "No apache service running." 

Is there a Boolean data type in Microsoft SQL Server like there is in MySQL?

You could use the BIT datatype to represent boolean data. A BIT field's value is either 1, 0, or null.

How to update record using Entity Framework 6?

Not related to this specific example, but I came across a challenge when trying to use EF and a DateTime field as the concurrency check field. It appears the EF concurrency code doesn't honor the precision setting from the metadata (edmx) i.e. Type="DateTime" Precision="3". The database datetime field will store a millisecond component within the field (i.e. 2020-10-18 15:49:02.123). Even if you set the original value of the Entity to a DateTime that includes the millisecond component, the SQL EF generates is this:

UPDATE [dbo].[People]
SET [dateUpdated] = @0
WHERE (([PeopleID] = @1) AND ([dateUpdated] = @2))
-- @0: '10/19/2020 1:07:00 AM' (Type = DateTime2)
-- @1: '3182' (Type = Int32)
-- @2: '10/19/2020 1:06:10 AM' (Type = DateTime2)

As you can see, @2 is a STRING representation without a millisecond component. This will cause your updates to fail.

Therefore, if you're going to use a DateTime field as a concurrency key, you must STRIP off the milliseconds/Ticks from the database field when retrieving the record and only pass/update the field with a similar stripped DateTime.

    //strip milliseconds due to EF concurrency handling
    PeopleModel p = db.people.Where(x => x.PeopleID = id);
    if (p.dateUpdated.Millisecond > 0)
        DateTime d = new DateTime(p.dateUpdated.Ticks / 10000000 * 10000000);
        object[] b = {p.PeopleID, d};
        int upd = db.Database.ExecuteSqlCommand("Update People set dateUpdated=@p1 where peopleId=@p0", b);
        if (upd == 1)
            p.dateUpdated = d;
            return InternalServerError(new Exception("Unable to update dateUpdated"));
return Ok(p);

And when updating the field with a new value, strip the milliseconds also

(param)int id, PeopleModel person;
People tbl = db.People.Where(x => x.PeopleID == id).FirstOrDefault();
db.Entry(tbl).OriginalValues["dateUpdated"] = person.dateUpdated;
//strip milliseconds from dateUpdated since EF doesn't preserve them
tbl.dateUpdated = new DateTime(DateTime.Now.Ticks / 10000000 * 10000000);

How to collapse blocks of code in Eclipse?

In CFEclipse: Preferences > CFEclipse > Editor > Code Folding > Initially Collapse column, you can uncheck to see all expanded when opening, or check all boxes to close all when opening a file.

How to get xdebug var_dump to show full object/array

These are configurable variables in php.ini:

; with sane limits
xdebug.var_display_max_depth = 10
xdebug.var_display_max_children = 256
xdebug.var_display_max_data = 1024 

; with no limits
; (maximum nesting is 1023)
xdebug.var_display_max_depth = -1 
xdebug.var_display_max_children = -1
xdebug.var_display_max_data = -1 

Of course, these may also be set at runtime via ini_set(), useful if you don't want to modify php.ini and restart your web server but need to quickly inspect something more deeply.

ini_set('xdebug.var_display_max_depth', '10');
ini_set('xdebug.var_display_max_children', '256');
ini_set('xdebug.var_display_max_data', '1024');

Xdebug settings are explained in the official documentation.

Windows Task Scheduler doesn't start batch file task

Try the code below:


cd c:\batchfilepath
net stop "SQL Server Reporting Services (MSSQLSERVER)" 
timeout /t 10
net start "SQL Server Reporting Services (MSSQLSERVER)"

AngularJS view not updating on model change

Just use $interval

Here is your code modified.

var app = angular.module('test', []);

app.controller('TestCtrl', function ($scope, $interval) {
   $scope.testValue = 0;

    $interval(function() {
    }, 500);

Find indices of elements equal to zero in a NumPy array

You can use numpy.nonzero to find zero.

>>> import numpy as np
>>> x = np.array([1,0,2,0,3,0,0,4,0,5,0,6]).reshape(4, 3)
>>> np.nonzero(x==0)  # this is what you want
(array([0, 1, 1, 2, 2, 3]), array([1, 0, 2, 0, 2, 1]))
>>> np.nonzero(x)
(array([0, 0, 1, 2, 3, 3]), array([0, 2, 1, 1, 0, 2]))

How to block until an event is fired in c#

If you're happy to use the Microsoft Reactive Extensions, then this can work nicely:

public class Foo
    public delegate void MyEventHandler(object source, MessageEventArgs args);
    public event MyEventHandler _event;
    public string ReadLine()
        return Observable
            .FromEventPattern<MyEventHandler, MessageEventArgs>(
                h => this._event += h,
                h => this._event -= h)
            .Select(ep => ep.EventArgs.Message)
    public void SendLine(string message)
        _event(this, new MessageEventArgs() { Message = message });

public class MessageEventArgs : EventArgs
    public string Message;

I can use it like this:

var foo = new Foo();

        () => foo.SendLine("Bar!"));

var resp = foo.ReadLine();


I needed to call the SendLine message on a different thread to avoid locking, but this code shows that it works as expected.

When should the xlsm or xlsb formats be used?

.xlsx loads 4 times longer than .xlsb and saves 2 times longer and has 1.5 times a bigger file. I tested this on a generated worksheet with 10'000 rows * 1'000 columns = 10'000'000 (10^7) cells of simple chained =…+1 formulas:

¦              ¦ .xlsx  ¦ .xlsb  ¦
¦ loading time ¦ 165s   ¦  43s   ¦
¦ saving time  ¦ 115s   ¦  61s   ¦
¦ file size    ¦  91 MB ¦  65 MB ¦

(Hardware: Core2Duo 2.3 GHz, 4 GB RAM, 5.400 rpm SATA II HD; Windows 7, under somewhat heavy load from other processes.)

Beside this, there should be no differences. More precisely,

both formats support exactly the same feature set

cites this blog post from 2006-08-29. So maybe the info that .xlsb does not support Ribbon code is newer than the upper citation, but I figure that forum source of yours is just wrong. When cracking open the binary file, it seems to condensedly mimic the OOXML file structure 1-to-1: Blog article from 2006-08-07

jQuery find() method not working in AngularJS directive

You can easily solve that in 2 steps:

1- Reach the child element using querySelector like that: var target = element[0].querySelector('tbody tr:first-child td')

2- Transform it to an angular.element object again by doing: var targetElement = angular.element(target)

You will then have access to all expected methods on the targetElement variable.

How to configure Eclipse build path to use Maven dependencies?

Right click on the project Configure > convert to Maven project

Then you can see all the Maven related Menu for you project.

How to create a .jar file or export JAR in IntelliJ IDEA (like Eclipse Java archive export)?

For Intellij IDEA version 11.0.2

File | Project Structure | Artifacts then you should press alt+insert or click the plus icon and create new artifact choose --> jar --> From modules with dependencies.

Next goto Build | Build artifacts --> choose your artifact.


error: No resource identifier found for attribute 'adSize' in package '' main.xml

I am adding the solution that worked for me for this same error.

I right clicked project > properties > (left panel) Android

Right panel under Library I removed the faulty library and added it again.

For me this error occurred after a corrupt workspace eclipse file where I had to import all projects again.

How to make HTML table cell editable?

This is a runnable example.

    if($(this).children("input").length > 0)
          return false;

    var tdObj = $(this);
    var preText = tdObj.html();
    var inputObj = $("<input type='text' />");


      if(13 == event.which) { // press ENTER-key
        var text = $(this).val();
      else if(27 == event.which) {  // press ESC-key
      return false;
        <!-- jQuery source -->
        <script src=""></script>
        <table align="center">
            <tr> <td>id</td> <td>name</td> </tr>
            <tr> <td>001</td> <td>dog</td> </tr>
            <tr> <td>002</td> <td>cat</td> </tr>
            <tr> <td>003</td> <td>pig</td> </tr>

source of historical stock data

I use the Its pretty decently priced. For 30 dollars a month you get 30 days of 1,5 and 60 minute bars for all US exchanges and 1 year of EOD data for most others.

Safely remove migration In Laravel

I accidentally created a migration with a bad name (command: php artisan migrate:make). I did not run (php artisan migrate) the migration, so I decided to remove it. My steps:

  1. Manually delete the migration file under app/database/migrations/my_migration_file_name.php
  2. Reset the composer autoload files: composer dump-autoload
  3. Relax

If you did run the migration (php artisan migrate), you may do this:

a) Run migrate:rollback - it is the right way to undo the last migration (Thnx @Jakobud)

b) If migrate:rollback does not work, do it manually (I remember bugs with migrate:rollback in previous versions):

  1. Manually delete the migration file under app/database/migrations/my_migration_file_name.php
  2. Reset the composer autoload files: composer dump-autoload
  3. Modify your database: Remove the last entry from the migrations table

How to send cookies in a post request with the Python Requests library?

The latest release of Requests will build CookieJars for you from simple dictionaries.

import requests

cookies = {'enwiki_session': '17ab96bd8ffbe8ca58a78657a918558'}

r ='', cookies=cookies)

Enjoy :)

Date vs DateTime

DateTime has a Date property that you can use to isolate the date part. The ToString method also does a good job of only displaying the Date part when the time part is empty.

How do I call Objective-C code from Swift?

Quote from the documentation:

Any Objective-C framework (or C library) that’s accessible as a module can be imported directly into Swift. This includes all of the Objective-C system frameworks—such as Foundation, UIKit, and SpriteKit—as well as common C libraries supplied with the system. For example, to import Foundation, simply add this import statement to the top of the Swift file you’re working in:

import Foundation

This import makes all of the Foundation APIs—including NSDate, NSURL, NSMutableData, and all of their methods, properties, and categories—directly available in Swift.

How to save as a new file and keep working on the original one in Vim?

The following command will create a copy in a new window. So you can continue see both original file and the new file.

:w {newfilename} | sp #

How to get different colored lines for different plots in a single figure?

I would like to offer a minor improvement on the last loop answer given in the previous post (that post is correct and should still be accepted). The implicit assumption made when labeling the last example is that plt.label(LIST) puts label number X in LIST with the line corresponding to the Xth time plot was called. I have run into problems with this approach before. The recommended way to build legends and customize their labels per matplotlibs documentation ( is to have a warm feeling that the labels go along with the exact plots you think they do:

# Plot several different functions...
labels = []
plotHandles = []
for i in range(1, num_plots + 1):
    x, = plt.plot(some x vector, some y vector) #need the ',' per ** below
    labels.append(some label)
plt.legend(plotHandles, labels, 'upper left',ncol=1)

**: Matplotlib Legends not working

how to set textbox value in jquery

I think you want to set the response of the call to the URL 'compz.php?prodid=' + x + '&qbuys=' + y as value of the textbox right? If so, you have to do something like:

$.get('compz.php?prodid=' + x + '&qbuys=' + y, function(data) {

Reference: get()

You have two errors in your code:

  • load() puts the HTML returned from the Ajax into the specified element:

    Load data from the server and place the returned HTML into the matched element.

    You cannot set the value of a textbox with that method.

  • $(selector).load() returns the a jQuery object. By default an object is converted to [object Object] when treated as string.

Further clarification:

Assuming your URL returns 5.

If your HTML looks like:

<div id="foo"></div>

then the result of


will be

<div id="foo">5</div>

But in your code, you have an input element. Theoretically (it is not valid HTML and does not work as you noticed), an equivalent call would result in

<input id="foo">5</input>

But you actually need

<input id="foo" value="5" />

Therefore, you cannot use load(). You have to use another method, get the response and set it as value yourself.

How do I get a decimal value when using the division operator in Python?

You need to tell Python to use floating point values, not integers. You can do that simply by using a decimal point yourself in the inputs:

>>> 4/100.0

Setting CSS pseudo-class rules from JavaScript

Switching stylesheets in and out is the way to do it. Here is a library to build stylesheets dynamically, so you can set styles on the fly:

Unique constraint violation during insert: why? (Oracle)

Your error looks like you are duplicating an already existing Primary Key in your DB. You should modify your sql code to implement its own primary key by using something like the IDENTITY keyword.

    [DBId] bigint NOT NULL IDENTITY,



How do I convert an Array to a List<object> in C#?

private List<object> ConvertArrayToList(object[] array)
  List<object> list = new List<object>();

  foreach(object obj in array)

  return list;

Convert pandas dataframe to NumPy array

Further to meteore's answer, I found the code

df.index = df.index.astype('i8')

doesn't work for me. So I put my code here for the convenience of others stuck with this issue.

city_cluster_df = pd.read_csv(text_filepath, encoding='utf-8')
# the field 'city_en' is a string, when converted to Numpy array, it will be an object
city_cluster_arr = city_cluster_df[['city_en','lat','lon','cluster','cluster_filtered']].to_records()
# change the field 'city_en' to string type (the index for 'city_en' here is 1 because before the field is the row index of dataframe)
descr[1]=(descr[1][0], "S20")

Cosine Similarity between 2 Number Lists

You can do this in Python using simple function:

def get_cosine(text1, text2):
  vec1 = text1
  vec2 = text2
  intersection = set(vec1.keys()) & set(vec2.keys())
  numerator = sum([vec1[x] * vec2[x] for x in intersection])
  sum1 = sum([vec1[x]**2 for x in vec1.keys()])
  sum2 = sum([vec2[x]**2 for x in vec2.keys()])
  denominator = math.sqrt(sum1) * math.sqrt(sum2)
  if not denominator:
     return 0.0
     return round(float(numerator) / denominator, 3)
dataSet1 = [3, 45, 7, 2]
dataSet2 = [2, 54, 13, 15]
get_cosine(dataSet1, dataSet2)

What is deserialize and serialize in JSON?

In the context of data storage, serialization (or serialisation) is the process of translating data structures or object state into a format that can be stored (for example, in a file or memory buffer) or transmitted (for example, across a network connection link) and reconstructed later. [...]
The opposite operation, extracting a data structure from a series of bytes, is deserialization. From Wikipedia

In Python "serialization" does nothing else than just converting the given data structure (e.g. a dict) into its valid JSON pendant (object).

  • Python's True will be converted to JSONs true and the dictionary itself will then be encapsulated in quotes.
  • You can easily spot the difference between a Python dictionary and JSON by their Boolean values:
    • Python: True / False,
    • JSON: true / false
  • Python builtin module json is the standard way to do serialization:

Code example:

data = {
    "president": {
        "name": "Zaphod Beeblebrox",
        "species": "Betelgeusian",
        "male": True,

import json
json_data = json.dumps(data, indent=2) # serialize
restored_data = json.loads(json_data) # deserialize

# serialized json_data now looks like:
# {
#   "president": {
#     "name": "Zaphod Beeblebrox",
#     "species": "Betelgeusian",
#     "male": true
#   }
# }


jackson deserialization json to java-objects

You have to change the line

product userFromJSON = mapper.readValue(userDataJSON, product.class);


product[] userFromJSON = mapper.readValue(userDataJSON, product[].class);

since you are deserializing an array (btw: you should start your class names with upper case letters as mentioned earlier). Additionally you have to create setter methods for your fields or mark them as public in order to make this work.

Edit: You can also go with Steven Schlansker's suggestion and use

List<product> userFromJSON =
        mapper.readValue(userDataJSON, new TypeReference<List<product>>() {});

instead if you want to avoid arrays.

Wipe data/Factory reset through ADB

After a lot of digging around I finally ended up downloading the source code of the recovery section of Android. Turns out you can actually send commands to the recovery.

 * The arguments which may be supplied in the recovery.command file:
 *   --send_intent=anystring - write the text out to recovery.intent
 *   --update_package=path - verify install an OTA package file
 *   --wipe_data - erase user data (and cache), then reboot
 *   --wipe_cache - wipe cache (but not user data), then reboot
 *   --set_encrypted_filesystem=on|off - enables / diasables encrypted fs

Those are the commands you can use according to the one I found but that might be different for modded files. So using adb you can do this:

adb shell
recovery --wipe_data

Using --wipe_data seemed to do what I was looking for which was handy although I have not fully tested this as of yet.


For anyone still using this topic, these commands may change based on which recovery you are using. If you are using Clockword recovery, these commands should still work. You can find other commands in /cache/recovery/command

For more information please see here:

How to detect a mobile device with JavaScript?

Testing for user agent is complex, messy and invariably fails. I also didn't find that the media match for "handheld" worked for me. The simplest solution was to detect if the mouse was available. And that can be done like this:

var result = window.matchMedia("(any-pointer:coarse)").matches;

That will tell you if you need to show hover items or not and anything else that requires a physical pointer. The sizing can then be done on further media queries based on width.

The following little library is a belt braces version of the query above, should cover most "are you a tablet or a phone with no mouse" scenarios.

Media matches have been supported since 2015 and you can check the compatibility here:

In short you should maintain variables relating to whether the screen is touch screen and also what size the screen is. In theory I could have a tiny screen on a mouse operated desktop.

Django error - matching query does not exist

your line raising the error is here:

comment = Comment.objects.get(pk=comment_id)

you try to access a non-existing comment.

from django.shortcuts import get_object_or_404

comment = get_object_or_404(Comment, pk=comment_id)

Instead of having an error on your server, your user will get a 404 meaning that he tries to access a non existing resource.

Ok up to here I suppose you are aware of this.

Some users (and I'm part of them) let tabs running for long time, if users are authorized to delete data, it may happens. A 404 error may be a better error to handle a deleted resource error than sending an email to the admin.

Other users go to addresses from their history, (same if data have been deleted since it may happens).

C++ printing boolean, what is displayed?

0 will get printed.

As in C++ true refers to 1 and false refers to 0.

In case, you want to print false instead of 0,then you have to sets the boolalpha format flag for the str stream.

When the boolalpha format flag is set, bool values are inserted/extracted by their textual representation: either true or false, instead of integral values.

#include <iostream>
int main()
  std::cout << std::boolalpha << false << std::endl;




Disabling tab focus on form elements

My case may not be typical but what I wanted to do was to have certain columns in a TABLE completely "inert": impossible to tab into them, and impossible to select anything in them. I had found class "unselectable" from other SO answers:

.unselectable {
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;

This actually prevents the user using the mouse to put the focus in the TD ... but I couldn't find a way on SO to prevent tabbing into cells. The TDs in my TABLE actually each has a DIV as their sole child, and using console.log I found that in fact the DIVs would get the focus (without the focus first being obtained by the TDs).

My solution involves keeping track of the "previously focused" element (anywhere on the page):

window.currFocus = document;
//Catch any bubbling focusin events (focus does not bubble)
$(window).on('focusin', function () {
  window.prevFocus = window.currFocus;
  window.currFocus = document.activeElement;

I can't really see how you'd get by without a mechanism of this kind... jolly useful for all sorts of purposes ... and of course it'd be simple to transform it into a stack of recently focused elements, if you wanted that...

The simplest answer is then just to do this (to the sole DIV child in every newly created TD):

jqNewCellDiv[ 0 ].classList.add( 'unselectable' );
jqNewCellDiv.focus( function() {

So far so good. It should be clear that this would work if you just have a TD (with no DIV child). Slight issue: this just stops tabbing dead in its tracks. Clearly if the table has any more cells on that row or rows below the most obvious action you'd want is to making tabbing tab to the next non-unselectable cell ... either on the same row or, if there are other rows, on the row below. If it's the very end of the table it gets a bit more tricky: i.e. where should tabbing go then. But all good clean fun.

In Python, how do I index a list with another list?

If you are using numpy, you can perform extended slicing like that:

>>> import numpy
>>> a=numpy.array(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'])
>>> Idx = [0, 3, 7]
>>> a[Idx]
array(['a', 'd', 'h'], 

...and is probably much faster (if performance is enough of a concern to to bother with the numpy import)

How to find/identify large commits in git history?

How can I track down the large files in the git history?

Start by analyzing, validating and selecting the root cause. Use git-repo-analysis to help.

You may also find some value in the detailed reports generated by BFG Repo-Cleaner, which can be run very quickly by cloning to a Digital Ocean droplet using their 10MiB/s network throughput.

Shell Script Syntax Error: Unexpected End of File

In my case, I found that placing a here document (like sqplus ... << EOF) statements indented also raise the same error as shown below:

./dbuser_case.ksh: line 25: syntax error: unexpected end of file

So after removing the indentation for this, then it went fine.

Hope it helps...

Add new column with foreign key constraint in one command

For SQL Server it should be something like

ADD two_id integer constraint fk foreign key references two(id)

Is there a way to collapse all code blocks in Eclipse?

The question is a bit old, but let me add a different approach. In addition to the above hot-key approaches, there are default preference settings that can be toggled.

As of Eclipse Galileo (and definitely in my Eclipse Version: Indigo Service Release 2 Build id: 20120216-1857) language specific preferences can open up new files to edit which are already collapsed or expanded.

Here is a link to Eclipse Galileo online docs showing the feature for C/C++: .

In my Eclipse Indigo I can open the Folding Preferences window via : menu/ Window/ Preferences/ Java/ Editor/ Folding and set all options on so I can open files by default that are completely collapsed.