Programs & Examples On #Coccinelle

How to write a cron that will run a script every day at midnight?

You can execute shell script in two ways,either by using cron job or by writing a shell script

Lets assume your script name is ""

First check the user permission of the script. use below command to check user permission of the script


If the script is in root,then use below command

sudo crontab -e

Second if the script holds the user "ubuntu", then use below command

crontab -e

Add the following line in your crontab:-

55 23 * * * /path/to/

Another way of doing this is to write a script and run it in the backgroud

Here is the script where you have to put your script name(eg:- which is going to run at 23:55pm everyday

#!/bin/bash while true do /home/modassir/ sleep 1d done

save it in a file (lets name it "")

sleep 1d - means it waits for one day and then it runs again.

now give the permission to your script.use below command:-

chmod +x

now, execute this shell script in the background by using "nohup". This will keep executing the script even after you logout from your session.

use below command to execute the script.

nohup ./ &

Note:- to run "" at 23:55pm everyday,you have to execute "" script at exactly 23:55pm.

iterating quickly through list of tuples

I wonder whether the below method is what you want.

You can use defaultdict.

>>> from collections import defaultdict
>>> s = [('red',1), ('blue',2), ('red',3), ('blue',4), ('red',1), ('blue',4)]
>>> d = defaultdict(list)
>>> for k, v in s:
>>> sorted(d.items())
[('blue', [2, 4, 4]), ('red', [1, 3, 1])]

Creating a daemon in Linux

You cannot create a process in linux that cannot be killed. The root user (uid=0) can send a signal to a process, and there are two signals which cannot be caught, SIGKILL=9, SIGSTOP=19. And other signals (when uncaught) can also result in process termination.

You may want a more general daemonize function, where you can specify a name for your program/daemon, and a path to run your program (perhaps "/" or "/tmp"). You may also want to provide file(s) for stderr and stdout (and possibly a control path using stdin).

Here are the necessary includes:

#include <stdio.h>    //printf(3)
#include <stdlib.h>   //exit(3)
#include <unistd.h>   //fork(3), chdir(3), sysconf(3)
#include <signal.h>   //signal(3)
#include <sys/stat.h> //umask(3)
#include <syslog.h>   //syslog(3), openlog(3), closelog(3)

And here is a more general function,

daemonize(char* name, char* path, char* outfile, char* errfile, char* infile )
    if(!path) { path="/"; }
    if(!name) { name="medaemon"; }
    if(!infile) { infile="/dev/null"; }
    if(!outfile) { outfile="/dev/null"; }
    if(!errfile) { errfile="/dev/null"; }
    //printf("%s %s %s %s\n",name,path,outfile,infile);
    pid_t child;
    //fork, detach from process group leader
    if( (child=fork())<0 ) { //failed fork
        fprintf(stderr,"error: failed fork\n");
    if (child>0) { //parent
    if( setsid()<0 ) { //failed to become session leader
        fprintf(stderr,"error: failed setsid\n");

    //catch/ignore signals

    //fork second time
    if ( (child=fork())<0) { //failed fork
        fprintf(stderr,"error: failed fork\n");
    if( child>0 ) { //parent

    //new file permissions
    //change to path directory

    //Close all open file descriptors
    int fd;
    for( fd=sysconf(_SC_OPEN_MAX); fd>0; --fd )

    //reopen stdin, stdout, stderr
    stdin=fopen(infile,"r");   //fd=0
    stdout=fopen(outfile,"w+");  //fd=1
    stderr=fopen(errfile,"w+");  //fd=2

    //open syslog

Here is a sample program, which becomes a daemon, hangs around, and then leaves.

    int res;
    int ttl=120;
    int delay=5;
    if( (res=daemonize("mydaemon","/tmp",NULL,NULL,NULL)) != 0 ) {
        fprintf(stderr,"error: daemonize failed\n");
    while( ttl>0 ) {
        //daemon code here
        syslog(LOG_NOTICE,"daemon ttl %d",ttl);
    syslog(LOG_NOTICE,"daemon ttl expired");

Note that SIG_IGN indicates to catch and ignore the signal. You could build a signal handler that can log signal receipt, and set flags (such as a flag to indicate graceful shutdown).

How to use radio on change event?

$(document).ready(function () {
    $('#allot').click(function () {
        if ($(this).is(':checked')) {
            alert("Allot Thai Gayo Bhai");

    $('#transfer').click(function () {
        if ($(this).is(':checked')) {
            alert("Transfer Thai Gayo");

JS Fiddle

Hive External Table Skip First Row

Just append below property in your query and the first header or line int the record will not load or it will be skipped.

Try this

tblproperties ("skip.header.line.count"="1");

Batch script: how to check for admin rights

I think the simplest way is trying to change the system date (that requires admin rights):

date %date%
if errorlevel 1 (
   echo You have NOT admin rights
) else (
   echo You have admin rights

If %date% variable may include the day of week, just get the date from last part of DATE command:

for /F "delims=" %%a in ('date ^<NUL') do set "today=%%a" & goto break
for %%a in (%today%) do set "today=%%a"
date %today%
if errorlevel 1 ...

Trying to add adb to PATH variable OSX

enter image description here

2nd solution is explained below. But when i close the terminal the change which i made in path variable gets lost. Thus i prefer the first way!

enter image description here

Password Protect a SQLite DB. Is it possible?

Why do you need to encrypt the database? The user could easily disassemble your program and figure out the key. If you're encrypting it for network transfer, then consider using PGP instead of squeezing an encryption layer into a database layer.

Can't compare naive and aware <= challenge.datetime_end

By default, the datetime object is naive in Python, so you need to make both of them either naive or aware datetime objects. This can be done using:

import datetime
import pytz


challenge.datetime_start = utc.localize(challenge.datetime_start) 
challenge.datetime_end = utc.localize(challenge.datetime_end) 
# now both the datetime objects are aware, and you can compare them

Note: This would raise a ValueError if tzinfo is already set. If you are not sure about that, just use

start_time = challenge.datetime_start.replace(tzinfo=utc)
end_time = challenge.datetime_end.replace(tzinfo=utc)

BTW, you could format a UNIX timestamp in datetime.datetime object with timezone info as following

d = datetime.datetime.utcfromtimestamp(int(unix_timestamp))
d_with_tz = datetime.datetime(

Javascript to display the current date and time

(new Date()).toLocaleString()

Will output the date and time using your local format. For example: "5/1/2020, 10:35:41 AM"

Obtaining only the filename when using OpenFileDialog property "FileName"

Use OpenFileDialog.SafeFileName

OpenFileDialog.SafeFileName Gets the file name and extension for the file selected in the dialog box. The file name does not include the path.

How do I get the n-th level parent of an element in jQuery?

If you plan on reusing this functionality, the optimal solution is to make a jQuery plugin:

$.fn.nthParent = function(n){
  var $p = $(this);
  while ( n-- >= 0 )
    $p = $p.parent();
  return $p;

Of course, you may want to extend it to allow for an optional selector and other such things.

One note: this uses a 0 based index for parents, so nthParent(0) is the same as calling parent(). If you'd rather have 1 based indexing, use n-- > 0

How do the post increment (i++) and pre increment (++i) operators work in Java?

In the above example

int a = 5,i;

i=++a + ++a + a++;        //Ans: i = 6 + 7 + 7 = 20 then a = 8 

i=a++ + ++a + ++a;        //Ans: i = 8 + 10 + 11 = 29 then a = 11

a=++a + ++a + a++;        //Ans: a = 12 + 13 + 13 = 38

System.out.println(a);    //Ans: a = 38

System.out.println(i);    //Ans: i = 29

How do I check if the user is pressing a key?

Try this:

import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class Main {

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

    JTextField textField = new JTextField();

    textField.addKeyListener(new Keychecker());

    JFrame jframe = new JFrame();


    jframe.setSize(400, 350);



class Keychecker extends KeyAdapter {

    public void keyPressed(KeyEvent event) {

        char ch = event.getKeyChar();




Codeigniter $this->db->order_by(' ','desc') result is not complete

Put the line $this->db->order_by("course_name","desc"); at top of your query. Like

return $query->result();

How to debug PDO database queries?

I've created a modern Composer-loaded project / repository for exactly this here:


Find the project's GitHub home here, see a blog post explaining it here. One line to add in your composer.json, and then you can use it like this:

echo debugPDO($sql, $parameters);

$sql is the raw SQL statement, $parameters is an array of your parameters: The key is the placeholder name (":user_id") or the number of the unnamed parameter ("?"), the value is .. well, the value.

The logic behind: This script will simply grad the parameters and replace them into the SQL string provided. Super-simple, but super-effective for 99% of your use-cases. Note: This is just a basic emulation, not a real PDO debugging (as this is not possible as PHP sends raw SQL and parameters to the MySQL server seperated).

A big thanks to bigwebguy and Mike from the StackOverflow thread Getting raw SQL query string from PDO for writing basically the entire main function behind this script. Big up!

JUNIT Test class in Eclipse - java.lang.ClassNotFoundException

I received this error because I had recently created a new workspace and my "Installed JREs" were not set up correctly. Make sure in Preferences -> Java -> Installed JREs the root folder of your JDK is selected. The default for me in a new workspace was a JRE for some reason.

Best approach to real time http streaming to HTML5 video client

I wrote an HTML5 video player around broadway h264 codec (emscripten) that can play live (no delay) h264 video on all browsers (desktop, iOS, ...).

Video stream is sent through websocket to the client, decoded frame per frame and displayed in a canva (using webgl for acceleration)

Check out on github.

Android: upgrading DB version and adding new table

1. About onCreate() and onUpgrade()

onCreate(..) is called whenever the app is freshly installed. onUpgrade is called whenever the app is upgraded and launched and the database version is not the same.

2. Incrementing the db version

You need a constructor like:

MyOpenHelper(Context context) {
   super(context, "dbname", null, 2); // 2 is the database version

IMPORTANT: Incrementing the app version alone is not enough for onUpgrade to be called!

3. Don't forget your new users!

Don't forget to add


to your onCreate() method as well or newly installed apps will lack the table.

4. How to deal with multiple database changes over time

When you have successive app upgrades, several of which have database upgrades, you want to be sure to check oldVersion:

onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
   switch(oldVersion) {
   case 1:
       // we want both updates, so no break statement here...
   case 2:

This way when a user upgrades from version 1 to version 3, they get both updates. When a user upgrades from version 2 to 3, they just get the revision 3 update... After all, you can't count on 100% of your user base to upgrade each time you release an update. Sometimes they skip an update or 12 :)

5. Keeping your revision numbers under control while developing

And finally... calling

adb uninstall <yourpackagename>

totally uninstalls the app. When you install again, you are guaranteed to hit onCreate which keeps you from having to keep incrementing the database version into the stratosphere as you develop...

Error: allowDefinition='MachineToApplication' beyond application level

I had the same problem because a new global Web.Config is automatically created for the parent folder. It was \Website\Website.

After I moved all file from the child folder to the parent and delete the child folder, now I have only one Web.Config and the problem is resolved.

Gradle: Could not determine java version from '11.0.2'

Getting this error when doing a cordova build android --release

I was able to resolve this, after trying so so many different things, by simply doing :

npm install cordova -g   # to upgrade to version 10.0.0

cordova platform rm android
cordova platform add android    # to upgrade to android version 9.0.0

Android - Activity vs FragmentActivity?

ianhanniballake is right. You can get all the functionality of Activity from FragmentActivity. In fact, FragmentActivity has more functionality.

Using FragmentActivity you can easily build tab and swap format. For each tab you can use different Fragment (Fragments are reusable). So for any FragmentActivity you can reuse the same Fragment.

Still you can use Activity for single pages like list down something and edit element of the list in next page.

Also remember to use Activity if you are using; use FragmentActivity if you are using Never attach a to an, as this will cause an exception to be thrown.

How to set a time zone (or a Kind) of a DateTime value?

You can try this as well, it is easy to implement

TimeZone time2 = TimeZone.CurrentTimeZone;
DateTime test = time2.ToUniversalTime(DateTime.Now);
var singapore = TimeZoneInfo.FindSystemTimeZoneById("Singapore Standard Time");
var singaporetime = TimeZoneInfo.ConvertTimeFromUtc(test, singapore);

Change the text to which standard time you want to change.

Use TimeZone feature of C# to implement.

PowerShell The term is not recognized as cmdlet function script file or operable program

For the benefit of searchers, there is another way you can produce this error message - by missing the $ off the script block name when calling it.

e.g. I had a script block like so:

$qa = {
    param($question, $answer)
    Write-Host "Question = $question, Answer = $answer"

I tried calling it using:

&qa -question "Do you like powershell?" -answer "Yes!"

But that errored. The correct way was:

&$qa -question "Do you like powershell?" -answer "Yes!"

Width equal to content

The solution with inline-block forces you to insert <br> after each element.
The solution with float forces you to wrap all elements with "clearfix" div.

Another elegant solution is to use display: table for elements.

With this solution you don't need to insert line breaks manually (like with inline-block), you don't need a wrapper around your elements (like with floats) and you can center your element if you need.

Add days Oracle SQL

Some disadvantage of "INTERVAL '1' DAY" is that bind variables cannot be used for the number of days added. Instead, numtodsinterval can be used, like in this small example:

select trunc(sysdate) + numtodsinterval(:x, 'day') tag
from dual

See also: NUMTODSINTERVAL in Oracle Database Online Documentation

How to run a script at a certain time on Linux?

Usually in Linux you use crontab for this kind of scduled tasks. But you have to specify the time when you "setup the timer" - so if you want it to be configurable in the file itself, you will have to create some mechanism to do that.

But in general, you would use for example:

30 1 * * 5 /path/to/script/

Would execute the script every Friday at 1:30 (AM) Here:

30 is minutes

1 is hour

next 2 *'s are day of month and month (in that order) and 5 is weekday

What is the difference between utf8mb4 and utf8 charsets in MySQL?

MySQL added this utf8mb4 code after 5.5.3, Mb4 is the most bytes 4 meaning, specifically designed to be compatible with four-byte Unicode. Fortunately, UTF8MB4 is a superset of UTF8, except that there is no need to convert the encoding to UTF8MB4. Of course, in order to save space, the general use of UTF8 is enough.

The original UTF-8 format uses one to six bytes and can encode 31 characters maximum. The latest UTF-8 specification uses only one to four bytes and can encode up to 21 bits, just to represent all 17 Unicode planes. UTF8 is a character set in Mysql that supports only a maximum of three bytes of UTF-8 characters, which is the basic multi-text plane in Unicode.

To save 4-byte-long UTF-8 characters in Mysql, you need to use the UTF8MB4 character set, but only 5.5. After 3 versions are supported (View version: Select version ();). I think that in order to get better compatibility, you should always use UTF8MB4 instead of UTF8. For char type data, UTF8MB4 consumes more space and, according to Mysql's official recommendation, uses VARCHAR instead of char.

In MariaDB utf8mb4 as the default CHARSET when it not set explicitly in the server config, hence COLLATE utf8mb4_unicode_ci is used.


CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

IndexError: too many indices for array

I think the problem is given in the error message, although it is not very easy to spot:

IndexError: too many indices for array
xs  = data[:, col["l1"     ]]

'Too many indices' means you've given too many index values. You've given 2 values as you're expecting data to be a 2D array. Numpy is complaining because data is not 2D (it's either 1D or None).

This is a bit of a guess - I wonder if one of the filenames you pass to loadfile() points to an empty file, or a badly formatted one? If so, you might get an array returned that is either 1D, or even empty (np.array(None) does not throw an Error, so you would never know...). If you want to guard against this failure, you can insert some error checking into your loadfile function.

I highly recommend in your for loop inserting:


This will work in Python 2.x or 3.x and might reveal the source of the issue. You might well find it is only one value of your outputs_l1 list (i.e. one file) that is giving the issue.

Error message "Strict standards: Only variables should be passed by reference"

The second snippet doesn't work either and that's why.

array_shift is a modifier function, that changes its argument. Therefore it expects its parameter to be a reference, and you cannot reference something that is not a variable. See Rasmus' explanations here: Strict standards: Only variables should be passed by reference

open() in Python does not create a file if it doesn't exist

I think it's r+, not rw. I'm just a starter, and that's what I've seen in the documentation.

Angular.js and HTML5 date input value -- how to get Firefox to show a readable date value in a date input?

I've used ng-change:

Date.prototype.addDays = function(days) {_x000D_
  var dat = new Date(this.valueOf());_x000D_
  dat.setDate(dat.getDate() + days);_x000D_
  return dat;_x000D_
var app = angular.module('myApp', []);_x000D_
app.controller('DateController', ['$rootScope', '$scope',_x000D_
  function($rootScope, $scope) {_x000D_
    function init() {_x000D_
      $scope.startDate = new Date();_x000D_
      $scope.endDate = $scope.startDate.addDays(14);_x000D_
    function load() {_x000D_
    // public methods_x000D_
    $scope.load = load;_x000D_
    $scope.setStart = function(date) {_x000D_
      $scope.startDate = date;_x000D_
    $scope.setEnd = function(date) {_x000D_
      $scope.endDate = date;_x000D_
<script src=""></script>_x000D_
<div data-ng-controller="DateController">_x000D_
  <label class="item-input"> <span class="input-label">Start</span>_x000D_
    <input type="date" data-ng-model="startDate" ng-change="setStart(startDate)" required validatedateformat calendar>_x000D_
  <label class="item-input"> <span class="input-label">End</span>_x000D_
    <input type="date" data-ng-model="endDate" ng-change="setEnd(endDate)" required validatedateformat calendar>_x000D_
  <button button="button" ng-disabled="planningForm.$invalid" ng-click="load()" class="button button-positive">_x000D_
</div <label class="item-input"> <span class="input-label">Start</span>_x000D_
<input type="date" data-ng-model="startDate" ng-change="setStart(startDate)" required validatedateformat calendar>_x000D_
<label class="item-input"> <span class="input-label">End</span>_x000D_
  <input type="date" data-ng-model="endDate" ng-change="setEnd(endDate)" required validatedateformat calendar>_x000D_

static function in C

When there is a need to restrict access to some functions, we'll use the static keyword while defining and declaring a function.

            /* file ab.c */ 
static void function1(void) 
  puts("function1 called"); 
And store the following code in another file ab1.c

/* file ab1.c  */ 
int main(void) 
  return 0;   
/* in this code, we'll get a "Undefined reference to function1".Because function 1 is declared static in file ab.c and can't be used in ab1.c */

what is this value means 1.845E-07 in excel?

1.84E-07 is the exact value, represented using scientific notation, also known as exponential notation.

1.845E-07 is the same as 0.0000001845. Excel will display a number very close to 0 as 0, unless you modify the formatting of the cell to display more decimals.

C# however will get the actual value from the cell. The ToString method use the e-notation when converting small numbers to a string.

You can specify a format string if you don't want to use the e-notation.

How to randomize (or permute) a dataframe rowwise and columnwise?

Random Samples and Permutations ina dataframe If it is in matrix form convert into data.frame use the sample function from the base package indexes = sample(1:nrow(df1), size=1*nrow(df1)) Random Samples and Permutations

What does %>% mean in R

matrix multiplication, see the following example:

> A <- matrix (c(1,3,4, 5,8,9, 1,3,3), 3,3)
> A
     [,1] [,2] [,3]
[1,]    1    5    1
[2,]    3    8    3
[3,]    4    9    3
> B <- matrix (c(2,4,5, 8,9,2, 3,4,5), 3,3)
> B
     [,1] [,2] [,3]
[1,]    2    8    3
[2,]    4    9    4
[3,]    5    2    5
> A %*% B
     [,1] [,2] [,3]
[1,]   27   55   28
[2,]   53  102   56
[3,]   59  119   63

> B %*% A
     [,1] [,2] [,3]
[1,]   38  101   35
[2,]   47  128   43
[3,]   31   86   26

Also see:

If this does not follow the size of matrix rule you will get the error:

> A <- matrix(c(1,2,3,4,5,6), 3,2)
    > A
     [,1] [,2]
[1,]    1    4
[2,]    2    5
[3,]    3    6

> B <- matrix (c(3,1,3,4,4,4,4,4,3), 3,3)

> B
         [,1] [,2] [,3]
    [1,]    3    4    4
    [2,]    1    4    4
    [3,]    3    4    3
    > A%*%B
    Error in A %*% B : non-conformable arguments

How to Call Controller Actions using JQuery in ASP.NET MVC

the previous response is ASP.NET only

you need a reference to jquery (perhaps from a CDN):

and then a similar block of code but simpler...

$.ajax({ url: '/Controller/Action/Id',
         success: function(data) { alert(data); }, 
         statusCode : {
             404: function(content) { alert('cannot find resource'); },
             500: function(content) { alert('internal server error'); }
         error: function(req, status, errorObj) {
               // handle status === "timeout"
               // handle other errors

I've added some necessary handlers, 404 and 500 happen all the time if you are debugging code. Also, a lot of other errors, such as timeout, will filter out through the error handler.

ASP.NET MVC Controllers handle requests, so you just need to request the correct URL and the controller will pick it up. This code sample with work in environments other than ASP.NET

Maven- No plugin found for prefix 'spring-boot' in the current project and in the plugin groups

Use mvn spring-boot:run. No mvn sprint-boot:run Error Writing.

How to change or add theme to Android Studio?

  1. Download a color theme you like - some sites host these, and some GitHub repos may offer them as well. [Editor's note: the website previously linked here has been replaced with spam]

  2. Import the theme. File -> Import Settings. Navigate to the theme-name.jar. Click the "Ok" button. This will tell you restart your application, at least it did for me, and it automatically selected the theme for my editor.

  3. Change the editor's theme color by going to File -> Settings -> Editor -> Colors & Fonts. Select the scheme and click the "Ok" button.

Note that this changes the editor's theme color, not the entire application's theme.

JavaScript Infinitely Looping slideshow with delays?

Perhps this is what you are looking for.

var pos = 0;
window.onload = function start() {
    setTimeout(slide, 3000);
function slide() {
   pos -= 600;
   if (pos === -2400)
     pos = 0;
   document.getElementById('container').style.marginLeft= pos + "px";
   setTimeout(slide, 3000);

Save classifier to disk in scikit-learn

sklearn estimators implement methods to make it easy for you to save relevant trained properties of an estimator. Some estimators implement __getstate__ methods themselves, but others, like the GMM just use the base implementation which simply saves the objects inner dictionary:

def __getstate__(self):
        state = super(BaseEstimator, self).__getstate__()
    except AttributeError:
        state = self.__dict__.copy()

    if type(self).__module__.startswith('sklearn.'):
        return dict(state.items(), _sklearn_version=__version__)
        return state

The recommended method to save your model to disc is to use the pickle module:

from sklearn import datasets
from sklearn.svm import SVC
iris = datasets.load_iris()
X =[:100, :2]
y =[:100]
model = SVC(),y)
import pickle
with open('mymodel','wb') as f:

However, you should save additional data so you can retrain your model in the future, or suffer dire consequences (such as being locked into an old version of sklearn).

From the documentation:

In order to rebuild a similar model with future versions of scikit-learn, additional metadata should be saved along the pickled model:

The training data, e.g. a reference to a immutable snapshot

The python source code used to generate the model

The versions of scikit-learn and its dependencies

The cross validation score obtained on the training data

This is especially true for Ensemble estimators that rely on the tree.pyx module written in Cython(such as IsolationForest), since it creates a coupling to the implementation, which is not guaranteed to be stable between versions of sklearn. It has seen backwards incompatible changes in the past.

If your models become very large and loading becomes a nuisance, you can also use the more efficient joblib. From the documentation:

In the specific case of the scikit, it may be more interesting to use joblib’s replacement of pickle (joblib.dump & joblib.load), which is more efficient on objects that carry large numpy arrays internally as is often the case for fitted scikit-learn estimators, but can only pickle to the disk and not to a string:

Could not load file or assembly 'xxx' or one of its dependencies. An attempt was made to load a program with an incorrect format

It's definitely an issue with some of the projects being built for x86 compatibility instead of any CPU. If I had to guess I would say that some of the references between your projects are probably referencing the dll's in some of the bin\debug folders instead of being project references.

When a project is compiled for x86 instead of 'Any CPU' the dll's go into the bin\x86\debug folder instead of bin\debug (which is probably where your references are looking).

But in any case, you should be using project references between your projects.

How to wait until WebBrowser is completely loaded in VB.NET?

I struggled with this 'fully loaded' issue for some time but found the following solution worked for me. I'm using IE7, so I'm not sure if this works in other versions, but worth a look.

I split the problem into two parts; first I needed a message from the DocumentComplete event;

Private Sub WebBrowser1_DocumentComplete(ByVal pDisp As Object, URL As Variant)
   fullyLoaded = True
End Sub

Then in the part of code where I need to wait till the web page has fully loaded I call another sub that does this;

Private Sub holdBrowserPage()
     fullyLoaded = False
     Do While fullyLoaded = False
     fullyLoaded = False
End Sub

In addition, I also needed to do the same thing whilst waiting for javascript code to complete. For instance on one page when you select an item from an html drop down list, it populated the next drop down list, but took a while to reveal itself. In that instance I found calling this;

Private Sub holdBrowser()
Do While WebBrowser1.Busy Or WebBrowser1.ReadyState <> READYSTATE_COMPLETE
End Sub

was enough to hold the browser. Not sure if this will help everyone, as a combination of IE7, the website I was loading, and the javascript that the page was running alone might have allowed this solution, but certainly worth a try.

Get data from file input in JQuery


<input type="file" name="input-file" id="input-file">


var fileToUpload = $('#input-file').prop('files')[0];

We want to get first element only, because prop('files') returns array.

Make columns of equal width in <table>

I think that this will do the trick:

    table-layout: fixed;
    width: 300px;

How to select specific form element in jQuery?

It isn't valid to have the same ID twice, that's why #name only finds the first one.

You can try:

$("#form2 input").val('Hello World!');


$("#form2 input[name=name]").val('Hello World!');

If you're stuck with an invalid page and want to select all #names, you can use the attribute selector on the id:

$("input[id=name]").val('Hello World!');

Laravel 5 Class 'form' not found

Just type the following command in terminal at the project directory and installation is done according the Laravel version:

composer require "laravelcollective/html"

Then add these lines in config/app.php

'providers' => [
    // ...
    // ...

'aliases' => [
    // ...
   'Form' => Collective\Html\FormFacade::class,
   'Html' => Collective\Html\HtmlFacade::class,
    // ...

MongoDB what are the default user and password?

In addition to previously provided answers, one option is to follow the 'localhost exception' approach to create the first user if your db is already started with access control (--auth switch). In order to do that, you need to have localhost access to the server and then run:

use admin
     user: "user_name",
     pwd: "user_pass",
     roles: [
           { role: "userAdminAnyDatabase", db: "admin" },
           { role: "readWriteAnyDatabase", db: "admin" },
           { role: "dbAdminAnyDatabase", db: "admin" }

As stated in MongoDB documentation:

The localhost exception allows you to enable access control and then create the first user in the system. With the localhost exception, after you enable access control, connect to the localhost interface and create the first user in the admin database. The first user must have privileges to create other users, such as a user with the userAdmin or userAdminAnyDatabase role. Connections using the localhost exception only have access to create the first user on the admin database.

Here is the link to that section of the docs.

Why do we need C Unions?

Unions are great. One clever use of unions I've seen is to use them when defining an event. For example, you might decide that an event is 32 bits.

Now, within that 32 bits, you might like to designate the first 8 bits as for an identifier of the sender of the event... Sometimes you deal with the event as a whole, sometimes you dissect it and compare it's components. unions give you the flexibility to do both.

union Event
  unsigned long eventCode;
  unsigned char eventParts[4];

Jquery submit form

You don't really need to do it all in jQuery to do that smoothly. Do it like this:

$(".nextbutton").click(function() { 

Use the auto keyword in C++ STL

The auto keyword gets the type from the expression on the right of =. Therefore it will work with any type, the only requirement is to initialize the auto variable when declaring it so that the compiler can deduce the type.


auto a = 0.0f;  // a is float
auto b = std::vector<int>();  // b is std::vector<int>()

MyType foo()  { return MyType(); }

auto c = foo();  // c is MyType

How to create a custom exception type in Java?

Great answers about creating custom exception classes. If you intend to reuse the exception in question then I would follow their answers/advice. However, If you only need a quick exception thrown with a message then you can use the base exception class on the spot

String word=reader.readLine();

if(word.contains(" "))
  /*create custom exeception*/
  throw new Exception("My one time exception with some message!");

implements Closeable or implements AutoCloseable

The try-with-resources Statement.

The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with-resources statement ensures that each resource is closed at the end of the statement. Any object that implements java.lang.AutoCloseable, which includes all objects which implement, can be used as a resource.

The following example reads the first line from a file. It uses an instance of BufferedReader to read data from the file. BufferedReader is a resource that must be closed after the program is finished with it:

static String readFirstLineFromFile(String path) throws IOException {
    try (BufferedReader br =
                   new BufferedReader(new FileReader(path))) {
        return br.readLine();

In this example, the resource declared in the try-with-resources statement is a BufferedReader. The declaration statement appears within parentheses immediately after the try keyword. The class BufferedReader, in Java SE 7 and later, implements the interface java.lang.AutoCloseable. Because the BufferedReader instance is declared in a try-with-resource statement, it will be closed regardless of whether the try statement completes normally or abruptly (as a result of the method BufferedReader.readLine throwing an IOException).

Prior to Java SE 7, you can use a finally block to ensure that a resource is closed regardless of whether the try statement completes normally or abruptly. The following example uses a finally block instead of a try-with-resources statement:

static String readFirstLineFromFileWithFinallyBlock(String path)
                                                     throws IOException {
    BufferedReader br = new BufferedReader(new FileReader(path));
    try {
        return br.readLine();
    } finally {
        if (br != null) br.close();


Please refer to the docs.

Sending a JSON HTTP POST request from Android

Posting parameters Using POST:-

URL url;
URLConnection urlConn;
DataOutputStream printout;
DataInputStream  input;
url = new URL (getCodeBase().toString() + "env.tcgi");
urlConn = url.openConnection();
urlConn.setDoInput (true);
urlConn.setDoOutput (true);
urlConn.setUseCaches (false);
urlConn.setRequestProperty("Host", "");
//Create JSONObject here
JSONObject jsonParam = new JSONObject();
jsonParam.put("ID", "25");
jsonParam.put("description", "Real");
jsonParam.put("enable", "true");

The part which you missed is in the the following... i.e., as follows..

// Send POST output.
printout = new DataOutputStream(urlConn.getOutputStream ());
printout.flush ();
printout.close ();

The rest of the thing you can do it.

string decode utf-8

the core functions are getBytes(String charset) and new String(byte[] data). you can use these functions to do UTF-8 decoding.

UTF-8 decoding actually is a string to string conversion, the intermediate buffer is a byte array. since the target is an UTF-8 string, so the only parameter for new String() is the byte array, which calling is equal to new String(bytes, "UTF-8")

Then the key is the parameter for input encoded string to get internal byte array, which you should know beforehand. If you don't, guess the most possible one, "ISO-8859-1" is a good guess for English user.

The decoding sentence should be

String decoded = new String(encoded.getBytes("ISO-8859-1"));

How do I clear/delete the current line in terminal?

In order to clean the whole line (2 different ways):

  • Home , Ctrl+K
  • End , Ctrl+U

How can JavaScript save to a local file?

So, your real question is: "How can JavaScript save to a local file?"

Take a look at

They save their HTML page locally after you have "changed" it internally.

[ UPDATE 2016.01.31 ]

TiddlyWiki original version saved directly. It was quite nice, and saved to a configurable backup directory with the timestamp as part of the backup filename.

TiddlyWiki current version just downloads it as any file download. You need to do your own backup management. :(


The trick is, you have to open the page as file:// not as http:// to be able to save locally.

The security on your browser will not let you save to _someone_else's_ local system, only to your own, and even then it isn't trivial.


How can I put a ListView into a ScrollView without it collapsing?

There are two issue when using a ListView inside a ScrollView.

1- ListView must fully expand to its children height. this ListView resolve this:

public class ListViewExpanded extends ListView
    public ListViewExpanded(Context context, AttributeSet attrs)
        super(context, attrs);

    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
        super.onMeasure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST));

Divider height must be 0, use padding in rows instead.

2- The ListView consumes touch events so ScrollView can't be scrolled as usual. This ScrollView resolve this issue:

public class ScrollViewInterceptor extends ScrollView
    float startY;

    public ScrollViewInterceptor(Context context, AttributeSet attrs)
        super(context, attrs);

    public boolean onInterceptTouchEvent(MotionEvent e)
        if (e.getAction() == MotionEvent.ACTION_DOWN) startY = e.getY();
        return (e.getAction() == MotionEvent.ACTION_MOVE) && (Math.abs(startY - e.getY()) > 50);

This is the best way I found to do the trick!

How to list branches that contain a given commit?

The answer for git branch -r --contains <commit> works well for normal remote branches, but if the commit is only in the hidden head namespace that GitHub creates for PRs, you'll need a few more steps.

Say, if PR #42 was from deleted branch and that PR thread has the only reference to the commit on the repo, git branch -r doesn't know about PR #42 because refs like refs/pull/42/head aren't listed as a remote branch by default.

In .git/config for the [remote "origin"] section add a new line:

fetch = +refs/pull/*/head:refs/remotes/origin/pr/*

(This gist has more context.)

Then when you git fetch you'll get all the PR branches, and when you run git branch -r --contains <commit> you'll see origin/pr/42 contains the commit.

The following artifacts could not be resolved: javax.jms:jms:jar:1.1

Try forcing updates using the mvn cpu option:

usage: mvn [options] [<goal(s)>] [<phase(s)>]

 -cpu,--check-plugin-updates            Force upToDate check for any
                                        relevant registered plugins

Java ArrayList of Arrays?

BTW. you should prefer coding against an Interface.

private ArrayList<String[]> action = new ArrayList<String[]>();

Should be

private List<String[]> action = new ArrayList<String[]>();

Passing command line arguments from Maven as properties in pom.xml

mvn clean package -DpropEnv=PROD

Then using like this in POM.xml


How to calculate the intersection of two sets?

Yes there is retainAll check out this

Set<Type> intersection = new HashSet<Type>(s1);

Set environment variables from file of key/value pairs

Problem with your approach is the export in the while loop is happening in a sub shell, and those variable will not be available in current shell (parent shell of while loop).

Add export command in the file itself:

export MINIENTREGA_FICHEROS="informe.txt programa.c"
export MINIENTREGA_DESTINO="./destino/entrega-prac1"

Then you need to source in the file in current shell using:

. ./conf/prac1


source ./conf/prac1

What is the fastest factorial function in JavaScript?

It would be probably very simple at first and maybe from this short code you would set it more better depend of your needs :


    <button  onclick="fact()">Open the Prompt</button>
    <h2 id="output"></h2>


    function fact(){ 
        var enter=prompt("Enter You Factorial Number Bellow :","");
        var Num_enter=Number(enter);

        for (var i=1,FactNumber=1;i<=Num_enter;i++){


           document.getElementById("output").textContent="the factorial of "+ Num_enter + " is: "+Num_enter+"!= "+ FactNumber;




Node.js ES6 classes with require

Yes, your example would work fine.

As for exposing your classes, you can export a class just like anything else:

class Animal {...}
module.exports = Animal;

Or the shorter:

module.exports = class Animal {


Once imported into another module, then you can treat it as if it were defined in that file:

var Animal = require('./Animal');

class Cat extends Animal {

How can I force a hard reload in Chrome for Android

As of 2018, from google help center (tested on Chrome 63) :

  1. tap on the three dots menu ;
  2. choose History > Clear browsing data ;
  3. if needed, choose the time period (above the checklist) ;
  4. uncheck all items but Cached images and files ;
  5. proceed with Clear data and confirm.

As mentioned in another answer, incognito tabs are also of great use for development.

Using a PHP variable in a text input value = statement

You need, for example:

<input type="text" name="idtest" value="<?php echo $idtest; ?>" />

The echo function is what actually outputs the value of the variable.

jQuery: Check if special characters exists in string

You are checking whether the string contains all illegal characters. Change the ||s to &&s.

Twitter bootstrap scrollable table

This example shows how to have sticky headers when using Bootstrap 4 table styling.

.table-scrollable {
    /* set the height to enable overflow of the table */
    max-height: 200px;
    overflow-x: auto;
    overflow-y: auto;
    scrollbar-width: thin;

.table-scrollable thead th {
    border: none;

.table-scrollable thead th {
    /* Set header to stick to the top of the container. */
    position: sticky; 
    top: 0px;
    /* This is needed otherwise the sticky header will be transparent 
    background-color: white;

    /* Because bootstrap adds `border-collapse: collapse` to the
     * table, the header boarders aren't sticky.
     * So, we need to make some adjustments to cover up the actual
     * header borders and created fake borders instead
    margin-top: -1px;
    margin-bottom: -1px;

    /* This is our fake border (see above comment) */
    box-shadow: inset 0 1px 0 #dee2e6,
                inset 0 -1px 0 #dee2e6;
<!-- CSS -->
<link rel="stylesheet" href="[email protected]/dist/css/bootstrap.min.css" integrity="sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2" crossorigin="anonymous">

<!-- jQuery and JS bundle w/ Popper.js -->
<script src="" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="[email protected]/dist/js/bootstrap.bundle.min.js" integrity="sha384-ho+j7jyWK8fNQe+A12Hb8AhRq26LrZ/JpcUGGOn+Y7RsweNrtN/tE3MoK7ZeZDyx" crossorigin="anonymous"></script>

<div class="dashboard-container card">
  <div class="card-body">
    <div class="table-scrollable">
      <table class="table table-hover table-sortable">
                  <th data-sort-type="text">Course</th>
                  <th data-sort-type="numeric">In Progress</th>
                  <th data-sort-type="numeric">Not Started</th>
                  <th data-sort-type="numeric">Passed</th>
                  <th data-sort-type="numeric">Failed</th>
              <td>How to be good at stuff</td>
              <td>Quantum physics for artists</td>
              <td>The best way to skin a cat</td>
              <td>Human cookbook</td>
              <td>Aristocracy rules</td>

Perl: function to trim string leading and trailing whitespace

I also use a positive lookahead to trim repeating spaces inside the text:


How to find the mime type of a file in python?

I try mimetypes library first. If it's not working, I use python-magic libary instead.

import mimetypes
def guess_type(filename, buffer=None):
mimetype, encoding = mimetypes.guess_type(filename)
if mimetype is None:
        import magic
        if buffer:
            mimetype = magic.from_buffer(buffer, mime=True)
            mimetype = magic.from_file(filename, mime=True)
    except ImportError:
return mimetype

Check if value exists in column in VBA

If you want to do this without VBA, you can use a combination of IF, ISERROR, and MATCH.

So if all values are in column A, enter this formula in column B:

=IF(ISERROR(MATCH(12345,A:A,0)),"Not Found","Value found on row " & MATCH(12345,A:A,0))

This will look for the value "12345" (which can also be a cell reference). If the value isn't found, MATCH returns "#N/A" and ISERROR tries to catch that.

If you want to use VBA, the quickest way is to use a FOR loop:

Sub FindMatchingValue()
    Dim i as Integer, intValueToFind as integer
    intValueToFind = 12345
    For i = 1 to 500    ' Revise the 500 to include all of your values
        If Cells(i,1).Value = intValueToFind then 
            MsgBox("Found value on row " & i)
            Exit Sub
        End If
    Next i

    ' This MsgBox will only show if the loop completes with no success
    MsgBox("Value not found in the range!")  
End Sub

You can use Worksheet Functions in VBA, but they're picky and sometimes throw nonsensical errors. The FOR loop is pretty foolproof.

How to handle AssertionError in Python and find out which line or statement it occurred on?

Use the traceback module:

import sys
import traceback

    assert True
    assert 7 == 7
    assert 1 == 2
    # many more statements like this
except AssertionError:
    _, _, tb = sys.exc_info()
    traceback.print_tb(tb) # Fixed format
    tb_info = traceback.extract_tb(tb)
    filename, line, func, text = tb_info[-1]

    print('An error occurred on line {} in statement {}'.format(line, text))

Automatic login script for a website on windows machine?

The code below does just that. The below is a working example to log into a game. I made a similar file to log in into Yahoo and a forum.

Just copy the login form from any webpage's source code. Add value= "your user name" and value = "your password". Normally the -input- elements in the source code do not have the value attribute, and sometime, you will see something like that: value=""

Save the file as a html on a local machine double click it, or make a bat/cmd file to launch and close them as required.

    <!doctype html>
    <!-- saved from url=(0014)about:internet -->

    <title>Ikariam Autologin</title>
    <form id="loginForm" name="loginForm" method="post"    action="">
    <select name="uni_url" id="logServer" class="validate[required]">
    <option  class=""  value="" fbUrl=""  cookieName=""  >
    <input id="loginName" name="name" type="text" value="PlayersName" class="" />
    <input id="loginPassword" name="password" type="password" value="examplepassword" class="" />
    <input type="hidden" id="loginKid" name="kid" value=""/>

Note that -script- is just -script-. I found there is no need to specify that is is JavaScript. It works anyway. I also found out that a bare-bones version that contains just two input filds: userName and password also work. But I left a hidded input field etc. just in case. Yahoo mail has a lot of hidden fields. Some are to do with password encryption, and it counts login attempts.

Security warnings and other staff, like Mark of the Web to make it work smoothly in IE are explained here:

how to execute php code within javascript

Interaction of Javascript and PHP

We all grew up knowing that Javascript ran on the Client Side (ie the browser) and PHP was a server side tool (ie the Server side). CLEARLY the two just cant interact.

But -- good news; it can be made to work and here's how.

The objective is to get some dynamic info (say server configuration items) from the server into the Javascript environment so it can be used when needed - - typically this implies DHTML modification to the presentation.

First, to clarify the DHTML usage I'll cite this DHTML example:

<script type="text/javascript">

function updateContent() {
 var frameObj = document.getElementById("frameContent");
 var y = (frameObj.contentWindow || frameObj.contentDocument);

 if (y.document) y = y.document;"red";  // demonstration of failure to alter the display

 // create a default, simplistic alteration usinga fixed string.
 var textMsg = 'Say good night Gracy';

 y.write(textMsg);"#00ee00";  // visual confirmation that the updateContent() was effective


Assuming we have an html file with the ID="frameContent" somewhere, then we can alter the display with a simple < body onload="updateContent()" >

Golly gee; we don't need PHP to do that now do we! But that creates a structure for applying PHP provided content.

We change the webpage in question into a PHTML type to allow the server side PHP access to the content:

**foo.html becomes foo.phtml**

and we add to the top of that page. We also cause the php data to be loaded into globals for later access - - like this:

   global $msg1, $msg2, $textMsgPHP;

function getContent($filename) {
    if ($theData = file_get_contents($filename, FALSE)) {
        return "$theData";
    } else {
        echo "FAILED!";
function returnContent($filename) {

  if ( $theData = getContent($filename) ) {
    // this works ONLY if $theData is one linear line (ie remove all \n)
    $textPHP = trim(preg_replace('/\r\n|\r|\n/', '', $theData));
    return "$textPHP";
  } else {
    echo '<span class="ERR">Error opening source file :(\n</span>';  # $filename!\n";

// preload the dynamic contents now for use later in the javascript (somewhere)
$msg1 =       returnContent('dummy_frame_data.txt');
$msg2 =       returnContent('dummy_frame_data_0.txt');
$textMsgPHP = returnContent('dummy_frame_data_1.txt');


Now our javascripts can get to the PHP globals like this:

// by accessig the globals var textMsg = '< ? php global $textMsgPHP; echo "$textMsgPHP"; ? >';

In the javascript, replace

var textMsg = 'Say good night Gracy';

with: // using php returnContent()

var textMsg = '< ? php $msgX = returnContent('dummy_div_data_3.txt'); echo "$msgX" ? >';


  • the webpage to be modified MUST be a phtml or some php file
  • the first thing in that file MUST be the < ? php to get the dynamic data ?>
  • the php data MUST contain its own css styling (if content is in a frame)
  • the javascript to use the dynamic data must be in this same file
  • and we drop in/outof PHP as necessary to access the dynamic data
  • Notice:- use single quotes in the outer javascript and ONLY double quotes in the dynamic php data

To be resolved: calling updateContent() with a filename and using it via onClick() instead of onLoad()

An example could be provided in the for your inspection, but didn't find a means to attach it

How to animate the change of image in an UIImageView?

Try this:

_imageView.image = image;
[_imageView.layer addAnimation:[CATransition animation] forKey:kCATransition];

Java string to date conversion

With Java 8 we get a new Date / Time API (JSR 310).

The following way can be used to parse the date in Java 8 without relying on Joda-Time:

 String str = "January 2nd, 2010";

// if we 2nd even we have changed in pattern also it is not working please workout with 2nd 
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMMM Q, yyyy", Locale.ENGLISH);
LocalDate date = LocalDate.parse(str, formatter);

// access date fields
int year = date.getYear(); // 2010
int day = date.getDayOfMonth(); // 2
Month month = date.getMonth(); // JANUARY
int monthAsInt = month.getValue(); // 1

LocalDate is the standard Java 8 class for representing a date (without time). If you want to parse values that contain date and time information you should use LocalDateTime. For values with timezones use ZonedDateTime. Both provide a parse() method similar to LocalDate:

LocalDateTime dateWithTime = LocalDateTime.parse(strWithDateAndTime, dateTimeFormatter);
ZonedDateTime zoned = ZonedDateTime.parse(strWithTimeZone, zoneFormatter);

The list formatting characters from DateTimeFormatter Javadoc:

All letters 'A' to 'Z' and 'a' to 'z' are reserved as pattern letters. 
The following pattern letters are defined:

Symbol  Meaning                     Presentation      Examples
------  -------                     ------------      -------
 G       era                         text              AD; Anno Domini; A
 u       year                        year              2004; 04
 y       year-of-era                 year              2004; 04
 D       day-of-year                 number            189
 M/L     month-of-year               number/text       7; 07; Jul; July; J
 d       day-of-month                number            10

 Q/q     quarter-of-year             number/text       3; 03; Q3; 3rd quarter
 Y       week-based-year             year              1996; 96
 w       week-of-week-based-year     number            27
 W       week-of-month               number            4
 E       day-of-week                 text              Tue; Tuesday; T
 e/c     localized day-of-week       number/text       2; 02; Tue; Tuesday; T
 F       week-of-month               number            3

 a       am-pm-of-day                text              PM
 h       clock-hour-of-am-pm (1-12)  number            12
 K       hour-of-am-pm (0-11)        number            0
 k       clock-hour-of-am-pm (1-24)  number            0

 H       hour-of-day (0-23)          number            0
 m       minute-of-hour              number            30
 s       second-of-minute            number            55
 S       fraction-of-second          fraction          978
 A       milli-of-day                number            1234
 n       nano-of-second              number            987654321
 N       nano-of-day                 number            1234000000

 V       time-zone ID                zone-id           America/Los_Angeles; Z; -08:30
 z       time-zone name              zone-name         Pacific Standard Time; PST
 O       localized zone-offset       offset-O          GMT+8; GMT+08:00; UTC-08:00;
 X       zone-offset 'Z' for zero    offset-X          Z; -08; -0830; -08:30; -083015; -08:30:15;
 x       zone-offset                 offset-x          +0000; -08; -0830; -08:30; -083015; -08:30:15;
 Z       zone-offset                 offset-Z          +0000; -0800; -08:00;

Optimistic vs. Pessimistic locking

Lot of good things have been said above about optimistic and pessimistic locking. One important point to consider is as follows:

When using optimistic locking, we need to cautious of the fact that how will application recover from these failures.

Specially in asynchronous message driven architectures, this can lead of out of order message processing or lost updates.

Failures scenarios need to be thought through.

Scrolling a div with jQuery

There's a plug-in for this if you don't want to write a bare-bones implementation yourself. It's called "scrollTo" (link). It allows you to perform programmed scrolling to certain points, or use values like -= 10px for continuous scrolling.

ScrollTo jQuery Plug-in

Maximum size of an Array in Javascript

I have built a performance framework that manipulates and graphs millions of datasets, and even then, the javascript calculation latency was on order of tens of milliseconds. Unless you're worried about going over the array size limit, I don't think you have much to worry about.

What is pipe() function in Angular

Don't get confused with the concepts of Angular and RxJS

We have pipes concept in Angular and pipe() function in RxJS.

1) Pipes in Angular: A pipe takes in data as input and transforms it to the desired output

2) pipe() function in RxJS: You can use pipes to link operators together. Pipes let you combine multiple functions into a single function.

The pipe() function takes as its arguments the functions you want to combine, and returns a new function that, when executed, runs the composed functions in sequence. (search for pipes in this URL, you can find the same)

So according to your question, you are referring pipe() function in RxJS

How do I print a datetime in the local timezone?

I believe the best way to do this is to use the LocalTimezone class defined in the datetime.tzinfo documentation (goto and scroll down to the "Example tzinfo classes" section):

Assuming Local is an instance of LocalTimezone

t = datetime.datetime(2009, 7, 10, 18, 44, 59, 193982, tzinfo=utc)
local_t = t.astimezone(Local)

then str(local_t) gives:

'2009-07-11 04:44:59.193982+10:00'

which is what you want.

(Note: this may look weird to you because I'm in New South Wales, Australia which is 10 or 11 hours ahead of UTC)

Cross-browser window resize event - JavaScript / jQuery

hope it will help in jQuery

define a function first, if there is an existing function skip to next step.

 function someFun() {
 //use your code

browser resize use like these.

 $(window).on('resize', function () {
    someFun();  //call your function.

Show data on mouseover of circle

You can pass in the data to be used in the mouseover like this- the mouseover event uses a function with your previously entered data as an argument (and the index as a second argument) so you don't need to use enter() a second time.

.attr("cx", function(d) { return x(d.x);})
.attr("cy", function(d) {return y(d.y)})
.attr("fill", "red").attr("r", 15)
.on("mouseover", function(d,i) {"text")
        .text( d.x)
        .attr("x", x(d.x))
        .attr("y", y(d.y)); 

Download a div in a HTML page as pdf using javascript

Your solution requires some ajax method to pass the html to a back-end server that has a html to pdf facility and then returning the pdf output generated back to the browser.

First setting up the client side code, we will setup the jquery code as

   var options = {
            "url": "/pdf/generate/convert_to_pdf.php",
            "data": "data=" + $("#content").html(),
            "type": "post",

Then intercept the data from the html2pdf generation script (somewhere from the internet).
convert_to_pdf.php (given as url in JQUERY code) looks like this -

    $html = $_POST['data'];
    $pdf = html2pdf($html);
    header("Content-Type: application/pdf"); //check this is the proper header for pdf
    header("Content-Disposition: attachment; filename='some.pdf';");
    echo $pdf;

PreparedStatement with Statement.RETURN_GENERATED_KEYS

You mean something like this?

long key = -1L;

PreparedStatement preparedStatement = connection.prepareStatement(YOUR_SQL_HERE, PreparedStatement.RETURN_GENERATED_KEYS);
preparedStatement.setXXX(index, VALUE);

ResultSet rs = preparedStatement.getGeneratedKeys();

if ( {
    key = rs.getLong(1);

"The breakpoint will not currently be hit. The source code is different from the original version." What does this mean?

Closing Visual Studio and reopening the solution can fix the problem, i.e. it's a bug within the IDE itself (I'm running VS2010).

If you have more than one instances of Visual Studio running, you only need to close the instance running the solution with the problem.

Free Online Team Foundation Server

You can use Visual Studio Team Services for free. Also you can import a TFS repo to this cloud space.

How can I pass parameters to a partial view in mvc 4

One of The Shortest method i found for single value while i was searching for myself, is just passing single string and setting string as model in view like this.

In your Partial calling side

@Html.Partial("ParitalAction", "String data to pass to partial")

And then binding the model with Partial View like this

@model string

and the using its value in Partial View like this


You can also play with other datatypes like array, int or more complex data types like IDictionary or something else.

Hope it helps,

How to center horizontal table-cell

Sometimes you have things other than text inside a table cell that you'd like to be horizontally centered. In order to do this, first set up some css...

    div.centered {
        margin: auto;
        width: 100%;
        display: flex;
        justify-content: center;

Then declare a div with class="centered" inside each table cell you want centered.

    <div class="centered">
        Anything: text, controls, etc... will be horizontally centered.

How to access parent Iframe from JavaScript

I would recommend using the postMessage API.

In your iframe, call:

window.parent.postMessage({message: 'Hello world'}, 'http://localhost/');

In the page you're including the iframe you can listen for events like this:

window.addEventListener('message', function(event) {
      if(event.origin === 'http://localhost/')
        alert('Received message: ' +;
        alert('Origin not allowed!');

    }, false);

By the way, it is also possible to do calls to other windows, and not only iframes.

Read more about the postMessage API on John Resigs blog here

How to remove leading whitespace from each line in a file

You can use AWK:

$ awk '{$1=$1}1' file
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)


$ sed 's|^[[:blank:]]*||g' file
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)
for (i = 0; i < 100; i++)

The shell's while/read loop

while read -r line
    echo $line
done <"file"

how to run mysql in ubuntu through terminal

You seem to just have begun using mysql.

Simple answer: for now use

mysql -u root -p password

Password is usually root by default. You may use other usernames if you have created other user using create user in mysql. For details use "help, help manage accounts, help create users" etc. If you dont want your password to be shown in open just press return key after "-p" and you will be prompted for password next. Hope this resolves the issue.

Gradle Sync failed could not find constraint-layout:1.0.0-alpha2

Alpha version is no longer available !

implementation ''

MySQL Query GROUP BY day / month / year

GROUP BY DATE_FORMAT(record_date, '%Y%m')

Note (primarily, to potential downvoters). Presently, this may not be as efficient as other suggestions. Still, I leave it as an alternative, and a one, too, that can serve in seeing how faster other solutions are. (For you can't really tell fast from slow until you see the difference.) Also, as time goes on, changes could be made to MySQL's engine with regard to optimisation so as to make this solution, at some (perhaps, not so distant) point in future, to become quite comparable in efficiency with most others.

Parse XML using JavaScript

I'm guessing from your last question, asked 20 minutes before this one, that you are trying to parse (read and convert) the XML found through using GeoNames' FindNearestAddress.

If your XML is in a string variable called txt and looks like this:

  <street>Roble Ave</street>
  <placename>Menlo Park</placename>
  <adminName2>San Mateo</adminName2>

Then you can parse the XML with Javascript DOM like this:

if (window.DOMParser)
    parser = new DOMParser();
    xmlDoc = parser.parseFromString(txt, "text/xml");
else // Internet Explorer
    xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
    xmlDoc.async = false;

And get specific values from the nodes like this:

//Gets house address number

//Gets Street name

//Gets Postal Code


Feb. 2019 edit:

In response to @gaugeinvariante's concerns about xml with Namespace prefixes. Should you have a need to parse xml with Namespace prefixes, everything should work almost identically:

NOTE: this will only work in browsers that support xml namespace prefixes such as Microsoft Edge

// XML with namespace prefixes 's', 'sn', and 'p' in a variable called txt_x000D_
txt = `_x000D_
<address xmlns:p='' xmlns:s='' xmlns:sn=''>_x000D_
  <s:street>Roble Ave</s:street>_x000D_
//Everything else the same_x000D_
if (window.DOMParser)_x000D_
    parser = new DOMParser();_x000D_
    xmlDoc = parser.parseFromString(txt, "text/xml");_x000D_
else // Internet Explorer_x000D_
    xmlDoc = new ActiveXObject("Microsoft.XMLDOM");_x000D_
    xmlDoc.async = false;_x000D_
//The prefix should not be included when you request the xml namespace_x000D_
//Gets "streetNumber" (note there is no prefix of "sn"_x000D_
//Gets Street name_x000D_
//Gets Postal Code_x000D_

Alternative for frames in html5 using iframes

Frames have been deprecated because they caused trouble for url navigation and hyperlinking, because the url would just take to you the index page (with the frameset) and there was no way to specify what was in each of the frame windows. Today, webpages are often generated by server-side technologies such as PHP, ASP.NET, Ruby etc. So instead of using frames, pages can simply be generated by merging a template with content like this:

Template File

<title>{insert script variable for title}</title>

  <div class="menu">
   {menu items inserted here by server-side scripting}
  <div class="main-content">
   {main content inserted here by server-side scripting}

If you don't have full support for a server-side scripting language, you could also use server-side includes (SSI). This will allow you to do the same thing--i.e. generate a single web page from multiple source documents.

But if you really just want to have a section of your webpage be a separate "window" into which you can load other webpages that are not necessarily located on your own server, you will have to use an iframe.

You could emulate your example like this:

Frames Example

  <title>Frames Test</title>
   .menu {
    .mainContent {
  <iframe class="menu" src="menu.html"></iframe>
  <iframe class="mainContent" src="events.html"></iframe>

There are probably better ways to achieve the layout. I've used the CSS float attribute, but you could use tables or other methods as well.

VB.NET Connection string (Web.Config, App.Config)

If it's a .mdf database and the connection string was saved when it was created, you should be able to access it via:

    Dim cn As SqlConnection = New SqlConnection(My.Settings.DatabaseNameConnectionString)

Hope that helps someone.

How can I process each letter of text using Javascript?

You can simply iterate it as in an array:

for(var i in txt){

apache server reached MaxClients setting, consider raising the MaxClients setting

Did you consider using nginx (or other event based web server) instead of apache?

nginx shall allow higher number of connections and consume much less resources (as it is event based and does not create separate process per connection). Anyway, you will need some processes, doing real work (like WSGI servers or so) and if they stay on the same server as the front end web server, you only shift the performance problem to a bit different place.

Latest apache version shall allow similar solution (configure it in event based manner), but this is not my area of expertise.

TypeError: a bytes-like object is required, not 'str'

Encoding and decoding can solve this in Python 3:

Client Side:

>>> host=''
>>> port=1337
>>> import socket
>>> s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
>>> s.connect((host,port))
>>> st='connection done'
>>> byt=st.encode()
>>> s.send(byt)

Server Side:

>>> host=''
>>> port=1337
>>> import socket
>>> s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
>>> s.bind((host,port))
>>> s.listen(1)
>>> conn ,addr=s.accept()
>>> data=conn.recv(2000)
>>> data.decode()
'connection done'

AngularJS - Find Element with attribute

Rather than querying the DOM for elements (which isn't very angular see "Thinking in AngularJS" if I have a jQuery background?) you should perform your DOM manipulation within your directive. The element is available to you in your link function.

So in your myDirective

return {
    link: function (scope, element, attr) {
        element.html('Hello world');

If you must perform the query outside of the directive then it would be possible to use querySelectorAll in modern browers


however you would need to use jquery to support IE8 and backwards


or write your own method as demonstrated here Get elements by attribute when querySelectorAll is not available without using libraries?

How do I create a folder in VB if it doesn't exist?

Try this: Directory.Exists(TheFolderName) and Directory.CreateDirectory(TheFolderName)

(You may need: Imports System.IO)

Laravel requires the Mcrypt PHP extension

If you are using Z Shell, just do the following:

  1. Open terminal
  2. sudo nano ~/.zshrc
  3. Paste this; export PATH=/Applications/MAMP/bin/php/php5.6.10/bin:$PATH
  4. Save
  5. Run source ~/.zshrc
  6. Run which php - you should get the MAMP 5.6.10 path

5.6.10 is the version of PHP you set in your MAMP.

Methods vs Constructors in Java

Constructor is special function used to initialise the data member, where the methods are functions to perform specific task.

Constructor name is the same name as the class name, where the method name may or may not or be class name.

Constructor does not allow any return type, where methods allow return type.

return in for loop or outside loop

Some people argue that a method should have a single point of exit (e.g., only one return). Personally, I think that trying to stick to that rule produces code that's harder to read. In your example, as soon as you find what you were looking for, return it immediately, it's clear and it's efficient.

Quoting the C2 wiki:

The original significance of having a single entry and single exit for a function is that it was part of the original definition of StructuredProgramming as opposed to undisciplined goto SpaghettiCode, and allowed a clean mathematical analysis on that basis.

Now that structured programming has long since won the day, no one particularly cares about that anymore, and the rest of the page is largely about best practices and aesthetics and such, not about mathematical analysis of structured programming constructs.

How to unmount a busy device

Avoid umount -l

At the time of writing, the top-voted answer recommends using umount -l.

umount -l is dangerous or at best unsafe. In summary:

  • It doesn't actually unmount the device, it just removes the filesystem from the namespace. Writes to open files can continue.
  • It can cause btrfs filesystem corruption

Work around / alternative

The useful behaviour of umount -l is hiding the filesystem from access by absolute pathnames, thereby minimising further moutpoint usage.

This same behaviour can be achieved by mounting an empty directory with permissions 000 over the directory to be unmounted.

Then any new accesses to filenames in the below the mountpoint will hit the newly overlaid directory with zero permissions - new blockers to the unmount are thereby prevented.

First try to remount,ro

The major unmount achievement to be unlocked is the read-only remount. When you gain the remount,ro badge, you know that:

  1. All pending data has been written to disk
  2. All future write attempts will fail
  3. The data is in a consistent state, should you need to physcially disconnect the device.

mount -o remount,ro /dev/device is guaranteed to fail if there are files open for writing, so try that straight up. You may be feeling lucky, punk!

If you are unlucky, focus only on processes with files open for writing:

lsof +f -- /dev/<devicename> | awk 'NR==1 || $4~/[0-9]+[uw -]/'

You should then be able to remount the device read-only and ensure a consistent state.

If you can't remount read-only at this point, investigate some of the other possible causes listed here.

Read-only re-mount achievement unlocked ?

Congratulations, your data on the mountpoint is now consistent and protected from future writing.

Why fuser is inferior to lsof

Why not use use fuser earlier? Well, you could have, but fuser operates upon a directory, not a device, so if you wanted to remove the mountpoint from the file name space and still use fuser, you'd need to:

  1. Temporarily duplicate the mountpoint with mount -o bind /media/hdd /mnt to another location
  2. Hide the original mount point and block the namespace:

Here's how:

null_dir=$(sudo mktemp --directory --tmpdir empty.XXXXX")
sudo chmod 000 "$null_dir"

# A request to remount,ro will fail on a `-o bind,ro` duplicate if there are
# still files open for writing on the original as each mounted instance is
# checked.
# So, avoid remount, and bind mount instead:
sudo mount -o bind,ro "$original" "$original_duplicate"

# Don't propagate/mirror the empty directory just about hide the original
sudo mount --make-private "$original_duplicate"

# Hide the original mountpoint
sudo mount -o bind,ro "$null_dir" "$original"

You'd then have:

  1. The original namespace hidden (no more files could be opened, the problem can't get worse)
  2. A duplicate bind mounted directory (as opposed to a device) on which to run fuser.

This is more convoluted[1], but allows you to use:

fuser -vmMkiw <mountpoint>

which will interactively ask to kill the processes with files open for writing. Of course, you could do this without hiding the mount point at all, but the above mimicks umount -l, without any of the dangers.

The -w switch restricts to writing processes, and the -i is interactive, so after a read-only remount, if you're it a hurry you could then use:

fuser -vmMk <mountpoint>

to kill all remaining processes with files open under the mountpoint.

Hopefully at this point, you can unmount the device. (You'll need to run umount on the mountpoint twice if you've bind mounted a mode 000 directory on top.)

Or use:

fuser -vmMki <mountpoint>

to interactively kill the remaining read-only processes blocking the unmount.

Dammit, I still get target is busy!

Open files aren't the only unmount blocker. See here and here for other causes and their remedies.

Even if you've got some lurking gremlin which is preventing you from fully unmounting the device, you have at least got your filesystem in a consistent state.

You can then use lsof +f -- /dev/device to list all processes with open files on the device containing the filesystem, and then kill them.

[1] It is less convoluted to use mount --move, but that requires mount --make-private /parent-mount-point which has implications. Basically, if the mountpoint is mounted under the / filesystem, you'd want to avoid this.

File URL "Not allowed to load local resource" in the Internet Browser

Follow the below steps,

  1. npm install -g http-server, install the http-server in angular project.
  2. Go to file location which needs to be accessed and open cmd prompt, use cmd http-server ./
  3. Access any of the paths with port number in browser(ex: in your angular application use the path "" Worked fine for me

Format date to MM/dd/yyyy in JavaScript

ISO compliant dateString

If your dateString is RFC282 and ISO8601 compliant:
pass your string into the Date Constructor:

const dateString = "2020-10-30T12:52:27+05:30"; // ISO8601 compliant dateString
const D = new Date(dateString);                 // {object Date}

from here you can extract the desired values by using Date Getters:

D.getMonth() + 1  // 10 (PS: +1 since Month is 0-based)
D.getDate()       // 30
D.getFullYear()   // 2020

Non-standard date string

If you use a non standard date string:
destructure the string into known parts, and than pass the variables to the Date Constructor:

new Date(year, monthIndex [, day [, hours [, minutes [, seconds [, milliseconds]]]]])

const dateString = "30/10/2020 12:52:27";
const [d, M, y, h, m, s] = dateString.match(/\d+/g);

// PS: M-1 since Month is 0-based
const D = new Date(y, M-1, d, h, m, s);  // {object Date}

D.getMonth() + 1  // 10 (PS: +1 since Month is 0-based)
D.getDate()       // 30
D.getFullYear()   // 2020

Using BigDecimal to work with currencies


How to replace a hash key with another key

Previous answers are good enough, but they might update original data. In case if you don't want the original data to be affected, you can try my code.

 newhash=hash.reject{|k| k=='_id'}.merge({id:hash['_id']})

First it will ignore the key '_id' then merge with the updated one.

How to exclude records with certain values in sql select

FROM StoreClients
  SELECT StoreId
  FROM StoreClients
  Where ClientId=5

SQL Fiddle

How do I make a MySQL database run completely in memory?

Assuming you understand the consequences of using the MEMORY engine as mentioned in comments, and here, as well as some others you'll find by searching about (no transaction safety, locking issues, etc) - you can proceed as follows:

MEMORY tables are stored differently than InnoDB, so you'll need to use an export/import strategy. First dump each table separately to a file using SELECT * FROM tablename INTO OUTFILE 'table_filename'. Create the MEMORY database and recreate the tables you'll be using with this syntax: CREATE TABLE tablename (...) ENGINE = MEMORY;. You can then import your data using LOAD DATA INFILE 'table_filename' INTO TABLE tablename for each table.

Getting started with Haskell

I can additionally recommend Yet Another Haskell Tutorial as an introduction.

Another good learning resource (probably on the intermediate level), which has helped me a lot and hasn't been mentioned in the other answers as far as I can see, is Brent Yorgey's Typeclassopedia, which can be found in The Monad Reader (Issue 13)

It is written in a very accessible style and contains (among many other things), the following introductory advice:

There are two keys to an expert Haskell hacker’s wisdom:

  1. Understand the types.

  2. Gain a deep intuition for each type class and its relationship to other type classes, backed up by familiarity with many examples.

The Monad Reader itself is an absolute treasure trove for functional programmers (not only Haskell programmers).

How do I schedule jobs in Jenkins?

*/5 * * * * means every 5 minutes

5 * * * * means the 5th minute of every hour

How do I display a wordpress page content?

This is more concise:

<?php echo get_post_field('post_content', $post->ID); ?>

and this even more:

<?= get_post_field('post_content', $post->ID) ?>

Python - Locating the position of a regex match in a string?

I don't think this question has been completely answered yet because all of the answers only give single match examples. The OP's question demonstrates the nuances of having 2 matches as well as a substring match which should not be reported because it is not a word/token.

To match multiple occurrences, one might do something like this:

iter = re.finditer(r"\bis\b", String)
indices = [m.start(0) for m in iter]

This would return a list of the two indices for the original string.

Node.js res.setHeader('content-type', 'text/javascript'); pushing the response javascript as file download

You can directly set the content type like below:

res.writeHead(200, {'Content-Type': 'text/plain'});

For reference go through the nodejs Docs link.

How do I add multiple conditions to "ng-disabled"?

this way worked for me

ng-disabled="(user.Role.ID != 1) && (user.Role.ID != 2)"

How to change port number for apache in WAMP

Change port number for Xampp Go to the file C:\xampp\apache\conf\httpd.conf

Listen 80

Change 80 to 82


Listen 82

now your url will be


What is the command to truncate a SQL Server log file?

if I remember well... in query analyzer or equivalent:


DBCC SHRINKFILE (  databasename_Log, 1)

How do I send a POST request as a JSON?

This works perfect for Python 3.5, if the URL contains Query String / Parameter value,

Request URL =
Parameter value = 21f6bb43-98a1-419d-8f0c-8133669e40ca

import requests

url = ''
data = {"name": "Value"}
r =, auth=('username', 'password'), verify=False, json=data)

How can I check that JButton is pressed? If the isEnable() is not work?

JButton#isEnabled changes the user interactivity of a component, that is, whether a user is able to interact with it (press it) or not.

When a JButton is pressed, it fires a actionPerformed event.

You are receiving Add button is pressed when you press the confirm button because the add button is enabled. As stated, it has nothing to do with the pressed start of the button.

Based on you code, if you tried to check the "pressed" start of the add button within the confirm button's ActionListener it would always be false, as the button will only be in the pressed state while the add button's ActionListeners are being called.

Based on all this information, I would suggest you might want to consider using a JCheckBox which you can then use JCheckBox#isSelected to determine if it has being checked or not.

Take a closer look at How to Use Buttons for more details

Importing packages in Java

In Java you can only import class Names, or static methods/fields.

To import class use


We can also import static methods/fields in Java and this is how to import

import static full.package.nameOfClass.staticMethod;
import static full.package.nameOfClass.staticField;

Why does intellisense and code suggestion stop working when Visual Studio is open?

I had the same issue, it turned out to be that nuget packages were not automatically downloaded for a solution i downloaded from the repository freshly, thus intellisense was not available since none of the required packages to show the right suggestions were available.

How can I repeat a character in Bash?

for i in {1..100}
  echo -n '='

Regex to replace multiple spaces with a single space

More robust:

function trim(word)
    word = word.replace(/[^\x21-\x7E]+/g, ' '); // change non-printing chars to spaces
    return word.replace(/^\s+|\s+$/g, '');      // remove leading/trailing spaces

Check whether values in one data frame column exist in a second data frame

Use %in% as follows

A$C %in% B$C

Which will tell you which values of column C of A are in B.

What is returned is a logical vector. In the specific case of your example, you get:

A$C %in% B$C

Which you can use as an index to the rows of A or as an index to A$C to get the actual values:

# as a row index
A[A$C %in% B$C,  ]  # note the comma to indicate we are indexing rows

# as an index to A$C
A$C[A$C %in% B$C]
[1] 1 3 4  # returns all values of A$C that are in B$C

We can negate it too:

A$C[!A$C %in% B$C]
[1] 2   # returns all values of A$C that are NOT in B$C

If you want to know if a specific value is in B$C, use the same function:

  2 %in% B$C   # "is the value 2 in B$C ?"  

  A$C[2] %in% B$C  # "is the 2nd element of A$C in B$C ?"  

How do I enable index downloads in Eclipse for Maven dependency search?

  1. In Eclipse, click on Windows > Preferences, and then choose Maven in the left side.
  2. Check the box "Download repository index updates on startup".
    • Optionally, check the boxes Download Artifact Sources and Download Artifact JavaDoc.
  3. Click OK. The warning won't appear anymore.
  4. Restart Eclipse.

Assertion failure in dequeueReusableCellWithIdentifier:forIndexPath:

In your storyboard you should set the 'Identifier' of your prototype cell to be the same as your CellReuseIdentifier "Cell". Then you won't get that message or need to call that registerClass: function.

How set background drawable programmatically in Android

try this.

 int res = getResources().getIdentifier("you_image", "drawable", "");
 preview = (ImageView) findViewById(;

getMinutes() 0-9 - How to display two digit numbers?

Yikes these answers aren't great, even the top post upticked. Here y'go, cross-browser and cleaner int/string conversion. Plus my advice is don't use a variable name 'date' with code like date = Date(...) where you're relying heavily on language case sensitivity (it works, but risky when you're working with server/browser code in different languages with different rules). So assuming the javascript Date in a var current_date:

mins = ('0'+current_date.getMinutes()).slice(-2);

The technique is take the rightmost 2 characters (slice(-2)) of "0" prepended onto the string value of getMinutes(). So:

"0"+"12" -> "012".slice(-2) -> "12"


"0"+"1" -> "01".slice(-2) -> "01"

Foreign Key Django Model

I would advise, it is slightly better practise to use string model references for ForeignKey relationships if utilising an app based approach to seperation of logical concerns .

So, expanding on Martijn Pieters' answer:

class Person(models.Model):
    name = models.CharField(max_length=50)
    birthday = models.DateField()
    anniversary = models.ForeignKey(
        'app_label.Anniversary', on_delete=models.CASCADE)
    address = models.ForeignKey(
        'app_label.Address', on_delete=models.CASCADE)

class Address(models.Model):
    line1 = models.CharField(max_length=150)
    line2 = models.CharField(max_length=150)
    postalcode = models.CharField(max_length=10)
    city = models.CharField(max_length=150)
    country = models.CharField(max_length=150)

class Anniversary(models.Model):
    date = models.DateField()

XPath - Selecting elements that equal a value

The XPath spec. defines the string value of an element as the concatenation (in document order) of all of its text-node descendents.

This explains the "strange results".

"Better" results can be obtained using the expressions below:

//*[text() = 'qwerty']

The above selects every element in the document that has at least one text-node child with value 'qwerty'.

//*[text() = 'qwerty' and not(text()[2])]

The above selects every element in the document that has only one text-node child and its value is: 'qwerty'.

Two versions of python on linux. how to make 2.7 the default

Enter the command

which python


cd /usr/bin
ls -l

Here you can see something like this

lrwxrwxrwx 1 root   root            9 Mar  7 17:04  python -> python2.7

your default python2.7 is soft linked to the text 'python'

So remove the softlink python

sudo rm -r python

then retry the above command

ls -l

you can see the softlink is removed

-rwxr-xr-x 1 root   root      3670448 Nov 12 20:01  python2.7

Then create a new softlink for python3.6

ln -s /usr/bin/python3.6 python

Then try the command python in terminal

Python 3.6.7 (default, Oct 22 2018, 11:32:17) 
[GCC 8.2.0] on linux

Type help, copyright, credits or license for more information.

How do I escape a single quote ( ' ) in JavaScript?

Since the values are actually inside of an HTML attribute, you should use &apos;

"<img src='something' onmouseover='change(&apos;ex1&apos;)' />";

Removing white space around a saved image in matplotlib

i followed this sequence and it worked like a charm.

fig=plt.imshow(image array,interpolation='nearest')
    bbox_inches='tight', pad_inches=0, format='pdf', dpi=1200)

How to check for changes on remote (origin) Git repository

A good way to have a synthetic view of what's going on "origin" is:

git remote show origin

What does a "Cannot find symbol" or "Cannot resolve symbol" error mean?


Using IntelliJ

Select Build->Rebuild Project will solve it

How do I shrink my SQL Server Database?

DBCC SHRINKDATABASE works for me, but this is its full syntax:

DBCC SHRINKDATABASE ( database_name, [target_percent], [truncate] )

where target_percent is the desired percentage of free space left in the database file after the database has been shrunk.

And truncate parameter can be:


Causes the freed file space to be retained in the database files. If not specified, the freed file space is released to the operating system.


Causes any unused space in the data files to be released to the operating system and shrinks the file to the last allocated extent, reducing the file size without moving any data. No attempt is made to relocate rows to unallocated pages. target_percent is ignored when TRUNCATEONLY is used.

...and yes no_one is right, shrinking datbase is not very good practice becasue for example :

shrink on data files are excellent ways to introduce significant logical fragmentation, becasue it moves pages from the end of the allocated range of a database file to somewhere at the front of the file...

shrink database can have a lot of consequence on database, server.... think a lot about it before you do it!

on the web there are a lot of blogs and articles about it.

How to run stored procedures in Entity Framework Core?

I found this extention very usefull: StoredProcedureEFCore

Then the usage is like this

List<Model> rows = null;

   .AddParam("limit", 300L)
   .AddParam("limitOut", out IOutParam<long> limitOut)
   .Exec(r => rows = r.ToList<Model>());

long limitOutValue = limitOut.Value;

   .AddParam("boolean_to_return", true)
   .ReturnValue(out IOutParam<bool> retParam)

bool b = retParam.Value;

   .AddParam("limit", 1L)
   .ExecScalar(out long l);

Difference between onStart() and onResume()

Not sure if this counts as an answer - but here is YouTube Video From Google's Course (Developing Android Apps with Kotlin) that explains the difference.

  • On Start is called when the activity becomes visible
  • On Pause is called when the activity loses focus (like a dialog pops up)
  • On Resume is called when the activity gains focus (like when a dialog disappears)

How do I run a class in a WAR from the command line?

To execute SomeClass.main(String [] args) from a deployed war file do:

Step 1: Write class that has a main method method i.e. (public static void main(String[] args) {...})

Step 2: Deploy your WAR

Step 3: cd /usr/local/yourprojectsname/tomcat/webapps/projectName/WEB-INF

Step 4: java -cp "lib/jar1.jar:lib/jar2.jar: ... :lib/jarn.jar" com.mypackage.SomeClass arg1 arg2 ... arg3

Note1: (to see if the class SomeOtherClass.class is in /usr/tomcat/webapps/projectName/WEB-INF/lib)

run --> cd /usr/tomcat/webapps/projectName/WEB-INF/lib && find . -name '*.jar' | while read jarfile; do if jar tf "$jarfile" | grep SomeOtherClass.class; then echo "$jarfile"; fi; done

Note2: Write to standard out so you can see if your main actually works via print statements to the console. This is called a back door.

Note3: The comment above by Bozhidar Bozhanov seems correct

How to kill/stop a long SQL query immediately?

You can use a keyboard shortcut ALT + Break to stop the query execution. However, this may not succeed in all cases.

How to use a wildcard in the classpath to add multiple jars?

Basename wild cards were introduced in Java 6; i.e. "foo/*" means all ".jar" files in the "foo" directory.

In earlier versions of Java that do not support wildcard classpaths, I have resorted to using a shell wrapper script to assemble a Classpath by 'globbing' a pattern and mangling the results to insert ':' characters at the appropriate points. This would be hard to do in a BAT file ...

How to initialize a struct in accordance with C programming language standards

You can do it with a compound literal. According to that page, it works in C99 (which also counts as ANSI C).


a = (MY_TYPE) { .flag = true, .value = 123, .stuff = 0.456 };
a = (MY_TYPE) { .value = 234, .stuff = 1.234, .flag = false };

The designations in the initializers are optional; you could also write:

a = (MY_TYPE) { true,  123, 0.456 };
a = (MY_TYPE) { false, 234, 1.234 };

Check if a column contains text using SQL

Try LIKE construction, e.g. (assuming StudentId is of type Char, VarChar etc.)

  select * 
    from Students
   where StudentId like '%' || TEXT || '%' -- <- TEXT - text to contain

Checking if a key exists in a JavaScript object?

A fast and easy solution is to convert your object to json then you will be able to do this easy task:

const allowed = {
    '/login' : '',
    '/register': '',
    '/resetpsw': ''
console.log('/login' in allowed); //returns true

If you use an array the object key will be converted to integers ex 0,1,2,3 etc. therefore, it will always be false

Access host database from a docker container

From Docker 17.06 onwards, a special Mac-only DNS name is available in docker containers that resolves to the IP address of the host. It is:


The documentation is here:

What is the default lifetime of a session?

it depends on your php settings...
use phpinfo() and take a look at the session chapter. There are values like session.gc_maxlifetime and session.cache_expire and session.cookie_lifetime which affects the sessions lifetime

EDIT: it's like Martin write before

Is PowerShell ready to replace my Cygwin shell on Windows?

There are lots of great great answers here, and here is my take. PowerShell is ready if you are... Examples:

grep = "Select-String -Pattern"

sort = "Sort-Object"

uniq = "Get-Unique"

file = "Get-Item"

cat = "Get-Content"

Perl/AWK/Sed are not commands, but utilities hence hard to compare, but you can do almost everything in PowerShell.

How do I test if a variable is a number in Bash?

This tests if a number is a non negative integer and is both shell independent (i.e. without bashisms) and uses only shell built-ins:


As this first answer (below) allows for integers with characters in them as long as the first are not first in the variable.

[ -z "${num##[0-9]*}" ] && echo "is a number" || echo "is not a number";


As jilles commented and suggested in his answer this is the correct way to do it using shell-patterns.

[ ! -z "${num##*[!0-9]*}" ] && echo "is a number" || echo "is not a number";

How to submit a form when the return key is pressed?

Why don't you just apply the div submit styles to a submit button? I'm sure there's a javascript for this but that would be easier.

How to make <label> and <input> appear on the same line on an HTML form?

aaa##HTML I would suggest you wrap them in a div, since you will likely end up floating them in certain contexts.

<div class="input-w">
    <label for="your-input">Your label</label>
    <input type="text" id="your-input" />


Then within that div, you can make each piece inline-block so that you can use vertical-align to center them - or set baseline etc. (your labels and input might change sizes in the future...

.input-w label, .input-w input {
    float: none; /* if you had floats before? otherwise inline-block will behave differently */
    display: inline-block;
    vertical-align: middle;    


UPDATE: mid 2016 + with mobile-first media queries and flex-box

This is how I do things these days.


<label class='input-w' for='this-input-name'>
  <span class='label'>Your label</span>
  <input class='input' type='text' id='this-input-name' placeholder='hello'>

<label class='input-w' for='this-other-input-name'>
  <span class='label'>Your label</span>
  <input class='input' type='text' id='this-other-input-name' placeholder='again'>


html { //
  box-sizing: border-box;
  *, *:before, *:after {
    box-sizing: inherit;
} // if you don't already reset your box-model, read about it

.input-w {
  display: block;
  width: 100%; // should be contained by a form or something
  margin-bottom: 1rem;
  @media (min-width: 500px) {
    display: flex;
    flex-direction: row;
    align-items: center;
  .label, .input {
    display: block;
    width: 100%;
    border: 1px solid rgba(0,0,0,.1);
    @media (min-width: 500px) {
      width: auto;
      display: flex;
  .label {
    font-size: 13px;
    @media (min-width: 500px) {
      /* margin-right: 1rem; */
      min-width: 100px; // maybe to match many?
  .input {
    padding: .5rem;
    font-size: 16px;
    @media (min-width: 500px) {
      flex-grow: 1;
      max-width: 450px; // arbitrary


How to comment lines in rails html.erb files?

ruby on rails notes has a very nice blogpost about commenting in erb-files

the short version is

to comment a single line use

<%# commented line %>

to comment a whole block use a if false to surrond your code like this

<% if false %>
code to comment
<% end %>

Could not read JSON: Can not deserialize instance of hello.Country[] out of START_OBJECT token

You need to do the following:

public class CountryInfoResponse {

   private List<Country> countries; 

   //getter - setter

RestTemplate restTemplate = new RestTemplate();
List<Country> countries = restTemplate.getForObject("",CountryInfoResponse.class).getCountries();

It would be great if you could use some kind of annotation to allow you to skip levels, but it's not yet possible (see this and this)

How to highlight cell if value duplicate in same column for google spreadsheet?

Answer of @zolley is right. Just adding a Gif and steps for the reference.

  1. Goto menu Format > Conditional formatting..
  2. Find Format cells if..
  3. Add =countif(A:A,A1)>1 in field Custom formula is
    • Note: Change the letter A with your own column.

enter image description here

Cannot open database "test" requested by the login. The login failed. Login failed for user 'xyz\ASPNET'

I have not seen this mentioned in the previous issues, so let me throw out another possibility. It could be that IFItest is not reachable or simply does not exist. For example, if one has a number of configurations, each with its own database, it could be that the database name was not changed to the correct one for the current configuration.

org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject

If you want to re-filter the json data you can use following method. Given example is getting all document data from couchdb.

    Gson gson = new Gson();
    String resultJson = restTemplate.getForObject(url+"_all_docs?include_docs=true", String.class);
    JSONObject object =  (JSONObject) new JSONParser().parse(resultJson);
    JSONArray rowdata = (JSONArray) object.get("rows");   
    List<Object>list=new ArrayList<Object>();   
    for(int i=0;i<rowdata.size();i++) {
        JSONObject index = (JSONObject) rowdata.get(i);
        JSONObject data = (JSONObject) index.get("doc");
    // convert your list to json
    String devicelist = gson.toJson(list);
    return devicelist;

How can I delete all cookies with JavaScript?

There is no 100% solution to delete browser cookies.

The problem is that cookies are uniquely identified by not just by their key "name" but also their "domain" and "path".

Without knowing the "domain" and "path" of a cookie, you cannot reliably delete it. This information is not available through JavaScript's document.cookie. It's not available through the HTTP Cookie header either!

However, if you know the name, path and domain of a cookie, then you can clear it by setting an empty cookie with an expiry date in the past, for example:

function clearCookie(name, domain, path){
    var domain = domain || document.domain;
    var path = path || "/";
    document.cookie = name + "=; expires=" + +new Date + "; domain=" + domain + "; path=" + path;

How to Iterate over a Set/HashSet without an Iterator?

To demonstrate, consider the following set, which holds different Person objects:

Set<Person> people = new HashSet<Person>();
people.add(new Person("Tharindu", 10));
people.add(new Person("Martin", 20));
people.add(new Person("Fowler", 30));

Person Model Class

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) { = name;
        this.age = age;

    //TODO - getters,setters ,overridden toString & compareTo methods

  1. The for statement has a form designed for iteration through Collections and arrays .This form is sometimes referred to as the enhanced for statement, and can be used to make your loops more compact and easy to read.
for(Person p:people){
  1. Java 8 - java.lang.Iterable.forEach(Consumer)
people.forEach(p -> System.out.println(p.getName()));
default void forEach(Consumer<? super T> action)

Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception. Unless otherwise specified by the implementing class, actions are performed in the order of iteration (if an iteration order is specified). Exceptions thrown by the action are relayed to the caller. Implementation Requirements:

The default implementation behaves as if: 

for (T t : this)

Parameters: action - The action to be performed for each element

Throws: NullPointerException - if the specified action is null

Since: 1.8

How to find the 'sizeof' (a pointer pointing to an array)?

The answer is, "No."

What C programmers do is store the size of the array somewhere. It can be part of a structure, or the programmer can cheat a bit and malloc() more memory than requested in order to store a length value before the start of the array.

How to change the value of ${user} variable used in Eclipse templates

EGit Solution

One would expect creating or changing template variables on a project-, workspace-, or environment-basis is a standard Eclipse feature. Sadly, it is not. More so, given that Eclipse plugins can define new variables and templates, there should be plugins out there providing a solution. If they are, they must be hard to find. mmm-TemplateVariable, which is available in the Eclipse Marketplace, is a step in the right direction for Maven users, giving the ability to include version, artifactId, etc. in templates.

Fortunately, EGit, which is an Eclipse tool for Git, provides very flexible means for including many different variables in code templates. The only requirement is that your project uses Git. If you don’t use Git, but are serious about software development, now is the time to learn (Pro Git book). If you are forced to use a legacy version control system, try changing some minds.

Thanks to the efforts of harmsk, EGit 4.0 and above includes the ability to use Git configuration key values in templates. This allows setting template values based on repository settings (project), user settings (account), and/or global settings (workstation).

The following example shows how to set up Eclipse and Git for a multi-user development workstation and use a custom Git configuration key in lieu of ${user} to provide more flexibility. Although the example is based on a Windows 10 installation of Eclipse Mars and Git for Windows, the example is applicable to Linux and OSX running Eclipse and Git using their respective command line tools.

To avoid possible confusion between Git’s configuration key and Java’s system property, a custom Git configuration key – – will be used to provide an author’s name and/or credentials.

Configuring Templates

The format of a Git template variable is as follows


where <name> is any arbitrary variable name and <key> is the Git configuration key whose value should be used. Given that, changing the Comments?Types template to

 * @author ${author:git_config(}
 * ${tags}

will now attempt to resolve the author’s name from Git’s configuration key. Without any further configuration, any newly created comments will not include a name after @author, since none has been defined yet.

Configuring Git

From the command line

Git System Configuration - This configuration step makes changes to Git’s system-wide configuration applicable to all accounts on the workstation unless overridden by user or repository settings. Because system-wide configurations are part the underlying Git application (e.g. Git for Windows), changes will require Administrator privileges. Run Git Bash, cmd, or PowerShell as Administrator. The following command will set the system-wide author.


The purpose of this “author” is to serve as a reminder that it should be set elsewhere. This is particularly useful when new user accounts are being used on the workstation.

To verify this setting, create an empty Java project that uses Git or open an existing Git-based project. Create a class and use Source?Generate Element Comment from the context menu, ALT-SHIFT-J, or start a JavaDoc comment. The resulting @author tag should be followed by the warning.

The remaining configuration changes can be performed without Administrator privileges.

Git Global(User) Configuration - Global, or user, configurations are those associated with a specific user and will override system-wide configurations. These settings apply to all Git-based projects unless overridden by repository settings. If the author name is different due to various project types such as for work, open source contributions, or personal, set the most frequently used here.

git config --global “Mr. John Smith”

Having configured the global value, return to the test project used early and apply a class comment. The@author tag should now show the global setting.

Git Repository(Local) Configuration - Lastly, a repository or local configuration can be used to configure an author for a specific project. Unlike the previous configurations, a repository configuration must be done from within the repository. Using Git Bash, PowerShell, etc. navigate into the test project’s repository.

git config --local “smithy”

Given this, new comments in the test project will use the locally defined author name. Other Git-based projects, will still use the global author name.

From Within Eclipse

The configuration changes above can also be set from within Eclipse through its Preferences: Team?Git-Configuration. Eclipse must be run as Administrator to change system-wide Git configurations.

In Sum

Although this example dealt specifically with the most common issue, that of changing ${user}, this approach can be used for more. However, caution should be exercised not to use Git-defined configuration keys, unless it is specifically intended.

What is the difference between NULL, '\0' and 0?

One good piece which helps me when starting with C (taken from the Expert C Programming by Linden)

The One 'l' nul and the Two 'l' null

Memorize this little rhyme to recall the correct terminology for pointers and ASCII zero:

The one "l" NUL ends an ASCII string,

The two "l" NULL points to no thing.

Apologies to Ogden Nash, but the three "l" nulll means check your spelling. 
  • The ASCII character with the bit pattern of zero is termed a "NUL".
  • The special pointer value that means the pointer points nowhere is "NULL".
  • The two terms are not interchangeable in meaning.

How to create file object from URL object (image)

In order to create a File from a HTTP URL you need to download the contents from that URL:

URL url = new URL("");
URLConnection connection = url.openConnection();
InputStream in = connection.getInputStream();
FileOutputStream fos = new FileOutputStream(new File("downloaded.jpg"));
byte[] buf = new byte[512];
while (true) {
    int len =;
    if (len == -1) {
    fos.write(buf, 0, len);

The downloaded file will be found at the root of your project: {project}/downloaded.jpg

Most efficient way to check for DBNull and then assign to a variable?

I would use the following code in C# (VB.NET is not as simple).

The code assigns the value if it is not null/DBNull, otherwise it asigns the default which could be set to the LHS value allowing the compiler to ignore the assign.

oSomeObject.IntMemeber = oRow["Value"] as int? ?? iDefault;
oSomeObject.StringMember = oRow["Name"] as string ?? sDefault;

Waiting for Target Device to Come Online

Check you don't have the deviced unauthorized, unauthorized devices reply the same error in the Android Studio, check the emulator once is on with the adb command.

$ adb devices

List of devices attached

emulator-5554 unauthorized

If you have of this way the emulator the Android Studio is waiting for be authorized and maybe this can solve the problem.

Authorized Devices

This is a error I have solved in Windows 10 with Android Studio 2.3.3

How to get the error message from the error code returned by GetLastError()?

GetLastError returns a numerical error code. To obtain a descriptive error message (e.g., to display to a user), you can call FormatMessage:

// This functions fills a caller-defined character buffer (pBuffer)
// of max length (cchBufferLength) with the human-readable error message
// for a Win32 error code (dwErrorCode).
// Returns TRUE if successful, or FALSE otherwise.
// If successful, pBuffer is guaranteed to be NUL-terminated.
// On failure, the contents of pBuffer are undefined.
BOOL GetErrorMessage(DWORD dwErrorCode, LPTSTR pBuffer, DWORD cchBufferLength)
    if (cchBufferLength == 0)
        return FALSE;

                                 NULL,  /* (not used with FORMAT_MESSAGE_FROM_SYSTEM) */
                                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
    return (cchMsg > 0);

In C++, you can simplify the interface considerably by using the std::string class:

#include <Windows.h>
#include <system_error>
#include <memory>
#include <string>
typedef std::basic_string<TCHAR> String;

String GetErrorMessage(DWORD dwErrorCode)
    LPTSTR psz{ nullptr };
    const DWORD cchMsg = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM
                                         | FORMAT_MESSAGE_IGNORE_INSERTS
                                         | FORMAT_MESSAGE_ALLOCATE_BUFFER,
                                       NULL, // (not used with FORMAT_MESSAGE_FROM_SYSTEM)
                                       MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
    if (cchMsg > 0)
        // Assign buffer to smart pointer with custom deleter so that memory gets released
        // in case String's c'tor throws an exception.
        auto deleter = [](void* p) { ::LocalFree(p); };
        std::unique_ptr<TCHAR, decltype(deleter)> ptrBuffer(psz, deleter);
        return String(ptrBuffer.get(), cchMsg);
        auto error_code{ ::GetLastError() };
        throw std::system_error( error_code, std::system_category(),
                                 "Failed to retrieve error message string.");

NOTE: These functions also work for HRESULT values. Just change the first parameter from DWORD dwErrorCode to HRESULT hResult. The rest of the code can remain unchanged.

These implementations provide the following improvements over the existing answers:

  • Complete sample code, not just a reference to the API to call.
  • Provides both C and C++ implementations.
  • Works for both Unicode and MBCS project settings.
  • Takes the error code as an input parameter. This is important, as a thread's last error code is only valid at well defined points. An input parameter allows the caller to follow the documented contract.
  • Implements proper exception safety. Unlike all of the other solutions that implicitly use exceptions, this implementation will not leak memory in case an exception is thrown while constructing the return value.
  • Proper use of the FORMAT_MESSAGE_IGNORE_INSERTS flag. See The importance of the FORMAT_MESSAGE_IGNORE_INSERTS flag for more information.
  • Proper error handling/error reporting, unlike some of the other answers, that silently ignore errors.

This answer has been incorporated from Stack Overflow Documentation. The following users have contributed to the example: stackptr, Ajay, Cody Gray?, IInspectable.

Typescript - multidimensional array initialization

Here is an example of initializing a boolean[][]:

const n = 8; // or some dynamic value
const palindrome: boolean[][] = new Array(n)
                                   .map(() => new Array(n)

Convert ArrayList<String> to String[] array

Try this

String[] arr = list.toArray(new String[list.size()]);

What is .htaccess file?


  • A settings file for the server
  • Cannot be accessed by end-user
  • There is no need to reboot the server, changes work immediately
  • It might serve as a bridge between your code and server

We can do

  • URL rewriting
  • Custom error pages
  • Caching
  • Redirections
  • Blocking ip's

Best way to do nested case statement logic in SQL Server

a user-defined function may server better, at least to hide the logic - esp. if you need to do this in more than one query

Running PowerShell as another user, and launching a script

Try adding the RunAs option to your Start-Process

Start-Process powershell.exe -Credential $Credential -Verb RunAs -ArgumentList ("-file $args")

PHP replacing special characters like à->a, è->e

As of PHP >= 5.4.0

$translatedString = transliterator_transliterate('Any-Latin; Latin-ASCII; [\u0080-\u7fff] remove', $string);

Putting a simple if-then-else statement on one line

That's more specifically a ternary operator expression than an if-then, here's the python syntax

value_when_true if condition else value_when_false

Better Example: (thanks Mr. Burns)

'Yes' if fruit == 'Apple' else 'No'

Now with assignment and contrast with if syntax

fruit = 'Apple'
isApple = True if fruit == 'Apple' else False


fruit = 'Apple'
isApple = False
if fruit == 'Apple' : isApple = True

How do you use variables in a simple PostgreSQL script?

Complete answer is located in the official PostgreSQL documentation.

You can use new PG9.0 anonymous code block feature ( )

DO $$
  v_List := 'foobar' ;
  FROM   dbo.PubLists
  WHERE  Name = v_List;
  -- ...
END $$;

Also you can get the last insert id:

DO $$
DECLARE lastid bigint;
  INSERT INTO test (name) VALUES ('Test Name') 
  RETURNING id INTO lastid;

  SELECT * FROM test WHERE id = lastid;
END $$;

Get all files that have been modified in git branch

I really liked @twalberg's answer but I didn't want to have to type the current branch name all the time. So I'm using this:

git diff --name-only $(git merge-base master HEAD)

How to convert JSON to CSV format and store in a variable

I just wanted to add some code here for people in the future since I was trying to export JSON to a CSV document and download it.

I use $.getJSON to pull json data from an external page, but if you have a basic array, you can just use that.

This uses Christian Landgren's code to create the csv data.

$(document).ready(function() {
    var JSONData = $.getJSON("GetJsonData.php", function(data) {
        var items = data;
        const replacer = (key, value) => value === null ? '' : value; // specify how you want to handle null values here
        const header = Object.keys(items[0]);
        let csv = => => JSON.stringify(row[fieldName], replacer)).join(','));
        csv = csv.join('\r\n');

        //Download the file as CSV
        var downloadLink = document.createElement("a");
        var blob = new Blob(["\ufeff", csv]);
        var url = URL.createObjectURL(blob);
        downloadLink.href = url; = "DataDump.csv";  //Name the file here

Edit: It's worth noting that JSON.stringify will escape quotes in quotes by adding \". If you view the CSV in excel, it doesn't like that as an escape character.

You can add .replace(/\\"/g, '""') to the end of JSON.stringify(row[fieldName], replacer) to display this properly in excel (this will replace \" with "" which is what excel prefers).

Full Line: let csv = => => (JSON.stringify(row[fieldName], replacer).replace(/\\"/g, '""'))).join(','));

Command for restarting all running docker containers?

To start multiple containers with the only particular container id's $ docker restart contianer-id1 container-id2 container-id3 ...

How to add button tint programmatically

For ImageButton you can use:

favoriteImageButton.setColorFilter(Color.argb(255, 255, 255, 255)); // White Tint

Delete certain lines in a txt file via a batch file

If you have sed:

sed -e '/REFERENCE/d' -e '/ERROR/d' [FILENAME]

Where FILENAME is the name of the text file with the good & bad lines

make an ID in a mysql table auto_increment (after the fact)

Yes, easy. Just run a data-definition query to update the tables, adding an AUTO_INCREMENT column.

If you have an existing database, be careful to preserve any foreign-key relationships that might already be there on the "artificially created" primary keys.

A Space between Inline-Block List Items


ul {
    font-size: 0;

ul li {
    font-size: 14px;
    display: inline-block;

You must set parent font size to 0

CSS @font-face not working with Firefox, but working with Chrome and IE

I was having the same problem getting a font to display properly in Firefox. Here is what I found to work for me. Add a slash before the directory holding the font in the url attribute. Here is my before and after versions:

B E F O R E:
{   font-family: "GrilledCheese BTN";
    src: url(fonts/grilcb__.ttf);

A F T E R:
{   font-family: "GrilledCheese BTN";
    src: url(/fonts/grilcb__.ttf);

notice the leading slash before 'fonts' in the url? This tells the browser to start at the root directory and then access the resource. At least for me - Problem Solved.

how to include glyphicons in bootstrap 3

I think your particular problem isn't how to use Glyphicons but understanding how Bootstrap files work together.

Bootstrap requires a specific file structure to work. I see from your code you have this:

<link href="bootstrap.css" rel="stylesheet" media="screen">

Your Bootstrap.css is being loaded from the same location as your page, this would create a problem if you didn't adjust your file structure.

But first, let me recommend you setup your folder structure like so:

/css      <-- Bootstrap.css here
/fonts    <-- Bootstrap fonts here
/js       <-- Bootstrap JavaScript here

If you notice, this is also how Bootstrap structures its files in its download ZIP.

You then include your Bootstrap file like so:

<link href="css/bootstrap.css" rel="stylesheet" media="screen">
<link href="./css/bootstrap.css" rel="stylesheet" media="screen">
<link href="/css/bootstrap.css" rel="stylesheet" media="screen">

Depending on your server structure or what you're going for.

The first and second are relative to your file's current directory. The second one is just more explicit by saying "here" (./) first then css folder (/css).

The third is good if you're running a web server, and you can just use relative to root notation as the leading "/" will be always start at the root folder.

So, why do this?

Bootstrap.css has this specific line for Glyphfonts:

@font-face {
    font-family: 'Glyphicons Halflings';
    src: url('../fonts/glyphicons-halflings-regular.eot');
    src: url('../fonts/glyphicons-halflings-regular.eot?#iefix') format('embedded-opentype'), url('../fonts/glyphicons-halflings-regular.woff') format('woff'), url('../fonts/glyphicons-halflings-regular.ttf') format('truetype'), url('../fonts/glyphicons-halflings-regular.svg#glyphicons-halflingsregular') format('svg');

What you can see is that that Glyphfonts are loaded by going up one directory ../ and then looking for a folder called /fonts and THEN loading the font file.

The URL address is relative to the location of the CSS file. So, if your CSS file is at the same location like this:


The CSS file is going one level deeper than looking for a /fonts folder.

So, let's say the actual location of these files are:


The CSS file would technically be looking for a folder at:


but your folder is actually in:


So see if that helps. You don't have to do anything 'special' to load Bootstrap Glyphicons, except make sure your folder structure is set up appropriately.

When you get that fixed, your HTML should simply be:

<span class="glyphicon glyphicon-comment"></span>

Note, you need both classes. The first class glyphicon sets up the basic styles while glyphicon-comment sets the specific image.

How to use FormData in react-native?

I have used form data with ImagePicker plugin. and I got it working please check below code

ImagePicker.showImagePicker(options, (response) => {
  console.log('Response = ', response);
  if (response.didCancel) {
    console.log('User cancelled photo picker');
  else if (response.error) {
    console.log('ImagePicker Error: ', response.error);
  else if (response.customButton) {
    console.log('User tapped custom button: ', response.customButton);
  else {
      method: 'post',
      headers: {
      'Accept': 'application/json',
      'Content-Type': 'application/json'
    body: JSON.stringify({
      fileName: response.fileName
      }).then(response => {
        console.log("image uploaded")
      }).catch(err => {

How to share my Docker-Image without using the Docker-Hub?

Docker images are stored as filesystem layers. Every command in the Dockerfile creates a layer. You can also create layers by using docker commit from the command line after making some changes (via docker run probably).

These layers are stored by default under /var/lib/docker. While you could (theoretically) cherry pick files from there and install it in a different docker server, is probably a bad idea to play with the internal representation used by Docker.

When you push your image, these layers are sent to the registry (the docker hub registry, by default… unless you tag your image with another registry prefix) and stored there. When pushing, the layer id is used to check if you already have the layer locally or it needs to be downloaded. You can use docker history to peek at which layers (other images) are used (and, to some extent, which command created the layer).

As for options to share an image without pushing to the docker hub registry, your best options are:

  • docker save an image or docker export a container. This will output a tar file to standard output, so you will like to do something like docker save 'dockerizeit/agent' > dk.agent.latest.tar. Then you can use docker load or docker import in a different host.

  • Host your own private registry. - Outdated, see comments See the docker registry image. We have built an s3 backed registry which you can start and stop as needed (all state is kept on the s3 bucket of your choice) which is trivial to setup. This is also an interesting way of watching what happens when pushing to a registry

  • Use another registry like (I haven't personally tried it), although whatever concerns you have with the docker hub will probably apply here too.

Using Google maps API v3 how do I get LatLng with a given address?

If you need to do this on the backend you can use the following URL structure:[STREET_ADDRESS]&key=[YOUR_API_KEY]

Sample PHP code using curl:

$curl = curl_init();

curl_setopt($curl, CURLOPT_URL, '' . rawurlencode($address) . '&key=' . $api_key);

curl_setopt ($curl, CURLOPT_RETURNTRANSFER, 1);

$json = curl_exec($curl);

curl_close ($curl);

$obj = json_decode($json);

See additional documentation for more details and expected json response.

The docs provide sample output and will assist you in getting your own API key in order to be able to make requests to the Google Maps Geocoding API.

SMTP Connect() failed. Message was not sent.Mailer error: SMTP Connect() failed

You've got no SMTPSecure setting to define the type of authentication being used, and you're running the Host setting with the unnecessary 'ssl://' (PS -- ssl is over port 465, if you need to run it over ssl instead, see the accepted answer here. Here's the lines to add/change:

+ $mail->SMTPSecure = 'tls';

- $mail->Host = "ssl://";
+ $mail->Host = "";

How to obtain the query string from the current URL with JavaScript?

Have a look at the MDN article about window.location.

The QueryString is available in

Solution that work in legacy browsers as well

MDN provide an example (no longer available in the above referenced article) of how to the get value of a single key available in the QueryString. Something like this:

function getQueryStringValue (key) {  
  return decodeURIComponent( RegExp("^(?:.*[&\\?]" + encodeURIComponent(key).replace(/[\.\+\*]/g, "\\$&") + "(?:\\=([^&]*))?)?.*$", "i"), "$1"));  

// Would write the value of the QueryString-variable called name to the console  

In modern browsers

In modern browsers you have the searchParams property of the URL interface, which returns a URLSearchParams object. The returned object has a number of convenient methods, including a get-method. So the equivalent of the above example would be:

let params = (new URL(document.location)).searchParams;
let name = params.get("name");

The URLSearchParams interface can also be used to parse strings in a querystring format, and turn them into a handy URLSearchParams object.

let paramsString = "name=foo&age=1337"
let searchParams = new URLSearchParams(paramsString);

searchParams.has("name") === true; // true
searchParams.get("age") === "1337"; // true

Notice that the browser support is still limited on this interface, so if you need to support legacy browsers, stick with the first example or use a polyfill.

Thymeleaf using path variables to th:href

The right way according to Thymeleaf documention for adding parameters is:

<a th:href="@{/category/edit/{id}(id=${category.idCategory})}">view</a>

API Gateway CORS: no 'Access-Control-Allow-Origin' header

Deploying the code after enabling CORS for both POST and OPTIONS worked for me.

Wireshark localhost traffic capture

You cannot capture loopback on Solaris, HP-UX, or Windows, however you can very easily work around this limitation by using a tool like RawCap.

RawCap can capture raw packets on any ip including (localhost/loopback). Rawcap can also generate a pcap file. You can open and analyze the pcap file with Wireshark.

See here for full details on how to monitor localhost using RawCap and Wireshark.

SQL MAX of multiple columns?

Using CROSS APPLY (for 2005+) ....

SELECT MostRecentDate 
FROM SourceTable
    CROSS APPLY (SELECT MAX(d) MostRecentDate FROM (VALUES (Date1), (Date2), (Date3)) AS a(d)) md

syntaxerror: unexpected character after line continuation character in python


f = open(D\\python\\HW\\2_1 - Copy.cp,"r");


f = open("D:\\python\\HW\\2_1 - Copy.cp", "r")

  1. File path needs to be a string (constant)
  2. need colon in Windows file path
  3. space after comma for better style
  4. ; after statement is allowed but fugly.

What tutorial are you using?

Get specific line from text file using just shell script

In parallel with William Pursell's answer, here is a simple construct which should work even in the original v7 Bourne shell (and thus also places where Bash is not available).

while read line; do
    i=`expr "$i" + 1`
    case $i in 5) echo "$line"; break;; esac
done <file

Notice also the optimization to break out of the loop when we have obtained the line we were looking for.

Python pandas insert list into a cell

Also getting

ValueError: Must have equal len keys and value when setting with an iterable,

using .at rather than .loc did not make any difference in my case, but enforcing the datatype of the dataframe column did the trick:

df['B'] = df['B'].astype(object)

Then I could set lists, numpy array and all sorts of things as single cell values in my dataframes.