Programs & Examples On #Phpwebsocket

phpwebsocket is a server-side implementation of a WebSocket server using the PHP language. WebSocket is an API and a protocol for bi-directional, full-duplex communication that is closely associated with HTML5 and implemented in recent versions of most web browsers.

How to create websockets server in PHP

I was in your shoes for a while and finally ended up using node.js, because it can do hybrid solutions like having web and socket server in one. So php backend can submit requests thru http to node web server and then broadcast it with websocket. Very efficiant way to go.

How can I get the latest JRE / JDK as a zip file rather than EXE or MSI installer?

JDK is not available as a portable ZIP file, unfortunately. However, you can follow these steps:

  • Create working JDK directory (C:\JDK in this case)
  • Download latest version of JDK from Oracle (for example jdk-7u7-windows-x64.exe)
  • Download and install 7-Zip (or download 7-Zip portable version if you are not administrator)
  • With 7-Zip extract all the files from jdk-XuXX-windows-x64.exe into the directory C:\JDK
  • Execute the following commands in cmd.exe:
    • cd C:\JDK\.rsrc\1033\JAVA_CAB10
    • extrac32 111
  • Unpack C:\JDK\.rsrc\1033\JAVA_CAB10\ with 7-zip
  • Execute the following commands in cmd.exe:
    • cd C:\JDK\.rsrc\1033\JAVA_CAB10\tools\
    • for /r %x in (*.pack) do .\bin\unpack200 -r "%x" "%~dx%~px%~nx.jar" (this will convert all .pack files into .jar files)
  • Copy all contents of C:\JDK\.rsrc\1033\JAVA_CAB10\tools where you want your JDK to be
  • Setup JAVA_HOME and PATH manually to point to your JDK dir and its BIN subdirectory.

How to inherit constructors?

Yes, you have to copy all 387 constructors. You can do some reuse by redirecting them:

  public Bar(int i): base(i) {}
  public Bar(int i, int j) : base(i, j) {}

but that's the best you can do.

JQuery Parsing JSON array

with parse.JSON

var obj = jQuery.parseJSON( '{ "name": "John" }' );
alert( === "John" );

Access Control Request Headers, is added to header in AJAX request with jQuery

And that is why you can't create a bot with JavaScript, because your options are limited to what the browser allows you to do. You can't just order a browser that follows the CORS policy, which most browsers follow, to send random requests to other origins and allow you to get the response that simply!

Additionally, if you tried to edit some request headers manually, like origin-header from the developers tools that come with the browsers, the browser will refuse your edit and may send a preflight OPTIONS request.

How can I get the name of an html page in Javascript?

var path = window.location.pathname;
var page = path.split("/").pop();
console.log( page );

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

if you are using html agility pack use getattributeValue:


Platform.runLater and Task in JavaFX

One reason to use an explicite Platform.runLater() could be that you bound a property in the ui to a service (result) property. So if you update the bound service property, you have to do this via runLater():

In UI thread also known as the JavaFX Application thread:


in Service implementation (background worker):

Platform.runLater(() -> result.add("Element " + finalI));

jQuery’s .bind() vs. .on()

As of Jquery 3.0 and above .bind has been deprecated and they prefer using .on instead. As @Blazemonger answered earlier that it may be removed and its for sure that it will be removed. For the older versions .bind would also call .on internally and there is no difference between them. Please also see the api for more detail.

jQuery API documentation for .bind()

How does Facebook Sharer select Images and other metadata when sharing my URL?

When you share for Facebook, you have to add in your html into the head section next meta tags:

<meta property="og:title" content="title" />
<meta property="og:description" content="description" />
<meta property="og:image" content="thumbnail_image" />

And that's it!

Add the button as you should according to what FB tells you.

All the info you need is in

How to remove the arrows from input[type="number"] in Opera

Those arrows are part of the Shadow DOM, which are basically DOM elements on your page which are hidden from you. If you're new to the idea, a good introductory read can be found here.

For the most part, the Shadow DOM saves us time and is good. But there are instances, like this question, where you want to modify it.

You can modify these in Webkit now with the right selectors, but this is still in the early stages of development. The Shadow DOM itself has no unified selectors yet, so the webkit selectors are proprietary (and it isn't just a matter of appending -webkit, like in other cases).

Because of this, it seems likely that Opera just hasn't gotten around to adding this yet. Finding resources about Opera Shadow DOM modifications is tough, though. A few unreliable internet sources I've found all say or suggest that Opera doesn't currently support Shadow DOM manipulation.

I spent a bit of time looking through the Opera website to see if there'd be any mention of it, along with trying to find them in Dragonfly...neither search had any luck. Because of the silence on this issue, and the developing nature of the Shadow DOM + Shadow DOM manipulation, it seems to be a safe conclusion that you just can't do it in Opera, at least for now.

How to correct indentation in IntelliJ

Code ? Reformat Code... (default Ctrl + Alt + L) for the whole file or Code ? Auto-Indent Lines (default Ctrl + Alt + I) for the current line or selection.

You can customise the settings for how code is auto-formatted under File ? Settings ? Editor ? Code Style.

To ensure comments are also indented to the same level as the code, you can simply do as follows:

UI screenshot (example for JavaScript)

<button> background image

Delete "button" before # rock:

button #rock {
    background: url(img/rock.png) no-repeat;

Worked for me in Google Chrome.

Regular Expression - 2 letters and 2 numbers in C#

Just for fun, here's a non-regex (more readable/maintainable for simpletons like me) solution:

string myString = "AB12";

if( Char.IsLetter(myString, 0) && 
    Char.IsLetter(myString, 1) && 
    Char.IsNumber(myString, 2) &&
    Char.IsNumber(myString, 3)) {
    // First two are letters, second two are numbers
else {
    // Validation failed


It seems that I've misunderstood the requirements. The code below will ensure that the first two characters and last two characters of a string validate (so long as the length of the string is > 3)

string myString = "AB12";

if(myString.Length > 3) {    
    if( Char.IsLetter(myString, 0) && 
        Char.IsLetter(myString, 1) && 
        Char.IsNumber(myString, (myString.Length - 2)) &&
        Char.IsNumber(myString, (myString.Length - 1))) {
        // First two are letters, second two are numbers
      else {
        // Validation failed
else {
   // Validation failed

How do I find out if first character of a string is a number?

To verify only first letter is number or character -- For number Character.isDigit(str.charAt(0)) --return true

For character Character.isLetter(str.charAt(0)) --return true

phpinfo() - is there an easy way for seeing it?

If you have php installed on your local machine try:

$ php -a
Interactive shell

php > phpinfo();

replace String with another in java

Try this:,%20java.lang.CharSequence%29

String a = "HelloBrother How are you!";
String r = a.replace("HelloBrother","Brother");


This would print out "Brother How are you!"

Moving matplotlib legend outside of the axis makes it cutoff by the figure box

Here is another, very manual solution. You can define the size of the axis and paddings are considered accordingly (including legend and tickmarks). Hope it is of use to somebody.

Example (axes size are the same!):

enter image description here


# Plot table

colmap = [(0,0,1) #blue
         ,(1,0,0) #red
         ,(0,1,0) #green
         ,(1,1,0) #yellow
         ,(1,0,1) #magenta
         ,(1,0.5,0.5) #pink
         ,(0.5,0.5,0.5) #gray
         ,(0.5,0,0) #brown
         ,(1,0.5,0) #orange

import matplotlib.pyplot as plt
import numpy as np

import collections
df = collections.OrderedDict()
df['labels']        = ['GWP100a\n[kgCO2eq]\n\nasedf\nasdf\nadfs','human\n[pts]','ressource\n[pts]'] 
df['all-petroleum long name'] = [3,5,2]
df['all-electric']  = [5.5, 1, 3]
df['HEV']           = [3.5, 2, 1]
df['PHEV']          = [3.5, 2, 1]

numLabels = len(df.values()[0])
numItems = len(df)-1
posX = np.arange(numLabels)+1
width = 1.0/(numItems+1)

fig = plt.figure(figsize=(2,2))
ax = fig.add_subplot(111)
for iiItem in range(1,numItems+1):*width, df.values()[iiItem], width, color=colmap[iiItem-1], label=df.keys()[iiItem])
ax.set(xticks=posX+width*(0.5*numItems), xticklabels=df['labels'])

# Change padding and margins, insert legend

fig.tight_layout() #tight margins
leg = ax.legend(loc='upper left', bbox_to_anchor=(1.02, 1), borderaxespad=0)
plt.draw() #to know size of legend

padLeft   = ax.get_position().x0 * fig.get_size_inches()[0]
padBottom = ax.get_position().y0 * fig.get_size_inches()[1]
padTop    = ( 1 - ax.get_position().y0 - ax.get_position().height ) * fig.get_size_inches()[1]
padRight  = ( 1 - ax.get_position().x0 - ax.get_position().width ) * fig.get_size_inches()[0]
dpi       = fig.get_dpi()
padLegend = ax.get_legend().get_frame().get_width() / dpi 

widthAx = 3 #inches
heightAx = 3 #inches
widthTot = widthAx+padLeft+padRight+padLegend
heightTot = heightAx+padTop+padBottom

# resize ipython window (optional)
posScreenX = 1366/2-10 #pixel
posScreenY = 0 #pixel
canvasPadding = 6 #pixel
canvasBottom = 40 #pixel
ipythonWindowSize = '{0}x{1}+{2}+{3}'.format(int(round(widthTot*dpi))+2*canvasPadding
plt.draw() #to resize ipython window. Has to be done BEFORE figure resizing!

# set figure size and ax position
ax.set_position([padLeft/widthTot, padBottom/heightTot, widthAx/widthTot, heightAx/heightTot])

Get values from other sheet using VBA


did not work. However the following code only worked for me.

SomeVal = ThisWorkbook.Sheets(2).cells(aRow,aCol).Value

How to put a horizontal divisor line between edit text's in a activity

If this didn't work:

    android:src="@android:drawable/divider_horizontal_bright" />

Try this raw View:

    android:background="#000000" />

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

swap may not be the red herring previously suggested. How big is the python process in question just before the ENOMEM?

Under kernel 2.6, /proc/sys/vm/swappiness controls how aggressively the kernel will turn to swap, and overcommit* files how much and how precisely the kernel may apportion memory with a wink and a nod. Like your facebook relationship status, it's complicated.

...but swap is actually available on demand (according to the web host)...

but not according to the output of your free(1) command, which shows no swap space recognized by your server instance. Now, your web host may certainly know much more than I about this topic, but virtual RHEL/CentOS systems I've used have reported swap available to the guest OS.

Adapting Red Hat KB Article 15252:

A Red Hat Enterprise Linux 5 system will run just fine with no swap space at all as long as the sum of anonymous memory and system V shared memory is less than about 3/4 the amount of RAM. .... Systems with 4GB of ram or less [are recommended to have] a minimum of 2GB of swap space.

Compare your /proc/sys/vm settings to a plain CentOS 5.3 installation. Add a swap file. Ratchet down swappiness and see if you live any longer.

Convert array of strings to List<string>

From .Net 3.5 you can use LINQ extension method that (sometimes) makes code flow a bit better.

Usage looks like this:

using System.Linq; 

// ...

public void My()
    var myArray = new[] { "abc", "123", "zyx" };
    List<string> myList = myArray.ToList();

PS. There's also ToArray() method that works in other way.

Is a Java hashmap search really O(1)?

This basically goes for most hash table implementations in most programming languages, as the algorithm itself doesn't really change.

If there are no collisions present in the table, you only have to do a single look-up, therefore the running time is O(1). If there are collisions present, you have to do more than one look-up, which drives down the performance towards O(n).

Label word wrapping

Refer to Automatically Wrap Text in Label. It describes how to create your own growing label.

Here is the full source taken from the above reference:

using System;
using System.Text;
using System.Drawing;
using System.Windows.Forms;

public class GrowLabel : Label {
  private bool mGrowing;
  public GrowLabel() {
    this.AutoSize = false;
  private void resizeLabel() {
    if (mGrowing) return;
    try {
      mGrowing = true;
      Size sz = new Size(this.Width, Int32.MaxValue);
      sz = TextRenderer.MeasureText(this.Text, this.Font, sz, TextFormatFlags.WordBreak);
      this.Height = sz.Height;
    finally {
      mGrowing = false;
  protected override void OnTextChanged(EventArgs e) {
  protected override void OnFontChanged(EventArgs e) {
  protected override void OnSizeChanged(EventArgs e) {

Java equivalent to JavaScript's encodeURIComponent that produces identical output?

I came up with my own version of the encodeURIComponent, because the posted solution has one problem, if there was a + present in the String, which should be encoded, it will converted to a space.

So here is my class:

import java.util.BitSet;

public final class EscapeUtils
    /** used for the encodeURIComponent function */
    private static final BitSet dontNeedEncoding;

        dontNeedEncoding = new BitSet(256);

        // a-z
        for (int i = 97; i <= 122; ++i)
        // A-Z
        for (int i = 65; i <= 90; ++i)
        // 0-9
        for (int i = 48; i <= 57; ++i)

        // '()*
        for (int i = 39; i <= 42; ++i)
        dontNeedEncoding.set(33); // !
        dontNeedEncoding.set(45); // -
        dontNeedEncoding.set(46); // .
        dontNeedEncoding.set(95); // _
        dontNeedEncoding.set(126); // ~

     * A Utility class should not be instantiated.
    private EscapeUtils()


     * Escapes all characters except the following: alphabetic, decimal digits, - _ . ! ~ * ' ( )
     * @param input
     *            A component of a URI
     * @return the escaped URI component
    public static String encodeURIComponent(String input)
        if (input == null)
            return input;

        StringBuilder filtered = new StringBuilder(input.length());
        char c;
        for (int i = 0; i < input.length(); ++i)
            c = input.charAt(i);
            if (dontNeedEncoding.get(c))
                final byte[] b = charToBytesUTF(c);

                for (int j = 0; j < b.length; ++j)
                    filtered.append("0123456789ABCDEF".charAt(b[j] >> 4 & 0xF));
                    filtered.append("0123456789ABCDEF".charAt(b[j] & 0xF));
        return filtered.toString();

    private static byte[] charToBytesUTF(char c)
            return new String(new char[] { c }).getBytes("UTF-8");
        catch (UnsupportedEncodingException e)
            return new byte[] { (byte) c };

how to assign a block of html code to a javascript variable

I recommend to use mustache templating frame work.

       <!--Put your html variable in a script and set the type to "x-tmpl-mustache"-->
       <script id="template" type="x-tmpl-mustache">
           <div class='saved' >
           <div >test.test</div> <div class='remove'>[Remove]</div></div>

  //You can use it without jquery.
  var template = $('#template').html();
  var rendered = Mustache.render(template);

Why I recommend this?

Soon or latter you will try to replace some part of the HTML variable and make it dynamic. Dealing with this as an HTML String will be a headache. Here is where Mustache magic can help you.

<script id="template" type="x-tmpl-mustache">
 <div class='remove'>  {{ name }}! </div> ....


 var template = $('#template').html();
 // You can pass dynamic template values
  var rendered = Mustache.render(template, {name: "Luke"});

There are lot more features.

Module AppRegistry is not registered callable module (calling runApplication)

I was also suffering from the same error for windows OS. I resolved this by cleaning gradlew.

The steps are:

  • step 1: cd android
  • step 2: gradlew clean
  • step 3: cd..

Can't concatenate 2 arrays in PHP

Try array_merge.

$array1 = array('Item 1');

$array2 = array('Item 2');

$array3 = array_merge($array1, $array2);

I think its because you are not assigning a key to either, so they both have key of 0, and the + does not re-index, so its trying to over write it.

show all tables in DB2 using the LIST command

I'm using db2 7.1 and SQuirrel. This is the only query that worked for me.

select * from SYSIBM.tables where table_schema = 'my_schema' and table_type = 'BASE TABLE';

Does not contain a static 'main' method suitable for an entry point

After placing the above code in Program.cs, follow these steps:

  1. Right click on the project

  2. Select "Properties"

  3. Set "Output Type" to "Windows Application"

  4. Startup object : namepace.Program

Can't access Tomcat using IP address

Firewalls are often the problem in these situations. Personally, the Mcafee enterprise firewall was causing this issue even for requests within the network.

Disable your firewalls or add a rule for tomcat and see if this helps.

Express.js: how to get remote client address

This worked for me better than the rest. My sites are behind CloudFlare and it seemed to require cf-connecting-ip.

req.headers['cf-connecting-ip'] || req.headers['x-forwarded-for'] || req.connection.remoteAddress

Didn't test Express behind proxies as it didn't say anything about this cf-connecting-ip header.

Set a request header in JavaScript

For people looking this up now:

It seems that now setting the User-Agent header is allowed since Firefox 43. See for the current list of forbidden headers.

How do you fadeIn and animate at the same time?

$('.tooltip').animate({ opacity: 1, top: "-10px" }, 'slow');

However, this doesn't appear to work on display: none elements (as fadeIn does). So, you might need to put this beforehand:

$('.tooltip').css('display', 'block');
$('.tooltip').animate({ opacity: 0 }, 0);

Comparing double values in C#

Comparing floating point number can't always be done precisely because of rounding. To compare

(x == .1)

the computer really compares

(x - .1) vs 0

Result of sybtraction can not always be represeted precisely because of how floating point number are represented on the machine. Therefore you get some nonzero value and the condition evaluates to false.

To overcome this compare

Math.Abs(x- .1) vs some very small threshold ( like 1E-9)

Does JavaScript guarantee object property order?

At the time of writing, most browsers did return properties in the same order as they were inserted, but it was explicitly not guaranteed behaviour so shouldn't have been relied upon.

The ECMAScript specification used to say:

The mechanics and order of enumerating the properties ... is not specified.

However in ES2015 and later non-integer keys will be returned in insertion order.

How to clear cache of Eclipse Indigo

you can use -clean parameter while starting eclipse like

C:\eclipse\eclipse.exe -vm "C:\Program Files\Java\jdk1.6.0_24\bin" -clean

How to make a div center align in HTML

how about something along these lines

<style type="text/css">
  #container {
    margin: 0 auto;
    text-align: center; /* for IE */

  #yourdiv {
    width: 400px;
    border: 1px solid #000;


<div id="container">
  <div id="yourdiv">

Getting error: ISO C++ forbids declaration of with no type

You forgot the return types in your member function definitions:

int ttTree::ttTreeInsert(int value) { ... }

and so on.

Explain why constructor inject is better than other options

With examples? Here's a simple one:

public class TwoInjectionStyles {
    private Foo foo;

    // Constructor injection
    public TwoInjectionStyles(Foo f) { = f;

    // Setting injection
    public void setFoo(Foo f) { = f; }

Personally, I prefer constructor injection when I can.

In both cases, the bean factory instantiates the TwoInjectionStyles and Foo instances and gives the former its Foo dependency.

How to Split Image Into Multiple Pieces in Python

I find it easier to skimage.util.view_as_windows or `skimage.util.view_as_blocks which also allows you to configure the step

Static variable inside of a function in C


Why ...? Reason is that static variable is initialized only once, and maintains its value throughout the program. means, you can use static variable between function calls. also it can be used to count "how many times a function is called"

   static int var = 5;
   printf("%d ",var--);

and answer is 5 4 3 2 1 and not 5 5 5 5 5 5 .... (infinite loop) as you are expecting. again, reason is static variable is initialized once, when next time main() is called it will not be initialize to 5 because it is already initialized in the program.So we can change the value but can not reinitialized. Thats how static variable works.

or you can consider as per storage: static variables are stored on Data Section of a program and variables which are stored in Data Section are initialized once. and before initialization they are kept in BSS section.

In turn Auto(local) variables are stored on Stack and all the variables on stack reinitialized all time when function is called as new FAR(function activation record) is created for that.

okay for more understanding, do the above example without "static" and let you know what will be the output. That make you to understand the difference between these two.

Thanks Javed

How to change max_allowed_packet size

set global max_allowed_packet=10000000000;

WhatsApp API (java/python)

From my blog


There is a secret pilot program which WhatsApp is working on with selected businesses

News coverage:

For some of my technical experiments, I was trying to figure out how beneficial and feasible it is to implement bots for different chat platforms in terms of market share and so possibilities of adaptation. Especially when you have bankruptly failed twice, it's important to validate ideas and fail more faster.

Popular chat platforms like Messenger, Slack, Skype etc. have happily (in the sense officially) provided APIs for bots to interact with, but WhatsApp has not yet provided any API.

However, since many years, a lot of activities has happened around this - struggle towards automated interaction with WhatsApp platform:

  1. Bots App Bots App is interesting because it shows that something is really tried and tested.

  2. Yowsup A project still actively developed to interact with WhatsApp platform.

  3. Yallagenie Yallagenie claim that there is a demo bot which can be interacted with at +971 56 112 6652

  4. Hubtype Hubtype is working towards having a bot platform for WhatsApp for business.

  5. Fred Fred's task was to automate WhatsApp conversations, however since it was not officially supported by WhatsApp - it was shut down.

  6. Oye Gennie A bot blocked by WhatsApp.

  7. App/Website to WhatsApp We can use custom URL schemes and Android intent system to interact with WhatsApp but still NOT WhatsApp API.

  8. Chat API daemon Probably created by inspecting the API calls in WhatsApp web version. NOT affiliated with WhatsApp.

  9. WhatsBot Deactivated WhatsApp bot. Created during a hackathon.

  10. No API claim WhatsApp co-founder clearly stated this in a conference that they did not had any plans for APIs for WhatsApp.

  11. Bot Ware They probably are expecting WhatsApp to release their APIs for chat bot platforms.

  12. Vixi They seems to be talking about how some platform which probably would work for WhatsApp. There is no clarity as such.

  13. Unofficial API This API can shut off any time.

    And the number goes on...

Django - filtering on foreign key properties

This has been possible since the queryset-refactor branch landed pre-1.0. Ticket 4088 exposed the problem. This should work:


The Django Many-to-one documentation has this and other examples of following Foreign Keys using the Model API.

How do I read configuration settings from Symfony2 config.yml?

Rather than defining contact_email within app.config, define it in a parameters entry:

    contact_email: [email protected]

You should find the call you are making within your controller now works.

How can I get a character in a string by index?

Do you mean like this

int index = 2;
string s = "hello";

string also implements IEnumberable<char> so you can also enumerate it like this

foreach (char c in s)

JSF rendered multiple combined conditions

Assuming that "a" and "b" are bean properties

rendered="#{bean.a==12 and (bean.b==13 or bean.b==15)}"

You may look at JSF EL operators

How to send a correct authorization header for basic authentication

PHP - curl:

$username = 'myusername';
$password = 'mypassword';
curl_setopt($ch, CURLOPT_USERPWD, $username . ":" . $password);

PHP - POST in WordPress:

$username = 'myusername';
$password = 'mypassword';
wp_remote_post('https://...some...api...endpoint...', array(
  'headers' => array(
    'Authorization' => 'Basic ' . base64_encode("$username:$password")

Finding diff between current and last version

Just use the cached flag if you added, but haven't committed yet:

git diff --cached --color

Recyclerview inside ScrollView not scrolling smoothly

Summary of all answers (Advantages & Disadvantages)

For single recyclerview

you can use it inside Coordinator layout.

Advantage - it will not load entire recyclerview items. So smooth loading.

Disadvantage - you can't load two recyclerview inside Coordinator layout - it produce scrolling problems

reference -

For multiple recylerview with minimum rows

you can load inside NestedScrollView

Advantage - it will scroll smoothly

Disadvantage - It load all rows of recyclerview so your activity open with delay

reference -

For multiple recylerview with large rows(more than 100)

You must go with recyclerview.

Advantage - Scroll smoothly, load smoothly

Disadvantage - You need to write more code and logic

Load each recylerview inside main recyclerview with help of multi-viewholders



-ChildRecyclerview1 (ViewHolder1)

-ChildRecyclerview2 (ViewHolder2)

-ChildRecyclerview3 (ViewHolder3) 

-Any other layout   (ViewHolder4)

Reference for multi-viewHolder -

How do Mockito matchers work?

Mockito matchers are static methods and calls to those methods, which stand in for arguments during calls to when and verify.

Hamcrest matchers (archived version) (or Hamcrest-style matchers) are stateless, general-purpose object instances that implement Matcher<T> and expose a method matches(T) that returns true if the object matches the Matcher's criteria. They are intended to be free of side effects, and are generally used in assertions such as the one below.

/* Mockito */  verify(foo).setPowerLevel(gt(9000));
/* Hamcrest */ assertThat(foo.getPowerLevel(), is(greaterThan(9000)));

Mockito matchers exist, separate from Hamcrest-style matchers, so that descriptions of matching expressions fit directly into method invocations: Mockito matchers return T where Hamcrest matcher methods return Matcher objects (of type Matcher<T>).

Mockito matchers are invoked through static methods such as eq, any, gt, and startsWith on org.mockito.Matchers and org.mockito.AdditionalMatchers. There are also adapters, which have changed across Mockito versions:

  • For Mockito 1.x, Matchers featured some calls (such as intThat or argThat) are Mockito matchers that directly accept Hamcrest matchers as parameters. ArgumentMatcher<T> extended org.hamcrest.Matcher<T>, which was used in the internal Hamcrest representation and was a Hamcrest matcher base class instead of any sort of Mockito matcher.
  • For Mockito 2.0+, Mockito no longer has a direct dependency on Hamcrest. Matchers calls phrased as intThat or argThat wrap ArgumentMatcher<T> objects that no longer implement org.hamcrest.Matcher<T> but are used in similar ways. Hamcrest adapters such as argThat and intThat are still available, but have moved to MockitoHamcrest instead.

Regardless of whether the matchers are Hamcrest or simply Hamcrest-style, they can be adapted like so:

/* Mockito matcher intThat adapting Hamcrest-style matcher is(greaterThan(...)) */

In the above statement: foo.setPowerLevel is a method that accepts an int. is(greaterThan(9000)) returns a Matcher<Integer>, which wouldn't work as a setPowerLevel argument. The Mockito matcher intThat wraps that Hamcrest-style Matcher and returns an int so it can appear as an argument; Mockito matchers like gt(9000) would wrap that entire expression into a single call, as in the first line of example code.

What matchers do/return

when(foo.quux(3, 5)).thenReturn(true);

When not using argument matchers, Mockito records your argument values and compares them with their equals methods.

when(foo.quux(eq(3), eq(5))).thenReturn(true);    // same as above
when(foo.quux(anyInt(), gt(5))).thenReturn(true); // this one's different

When you call a matcher like any or gt (greater than), Mockito stores a matcher object that causes Mockito to skip that equality check and apply your match of choice. In the case of argumentCaptor.capture() it stores a matcher that saves its argument instead for later inspection.

Matchers return dummy values such as zero, empty collections, or null. Mockito tries to return a safe, appropriate dummy value, like 0 for anyInt() or any(Integer.class) or an empty List<String> for anyListOf(String.class). Because of type erasure, though, Mockito lacks type information to return any value but null for any() or argThat(...), which can cause a NullPointerException if trying to "auto-unbox" a null primitive value.

Matchers like eq and gt take parameter values; ideally, these values should be computed before the stubbing/verification starts. Calling a mock in the middle of mocking another call can interfere with stubbing.

Matcher methods can't be used as return values; there is no way to phrase thenReturn(anyInt()) or thenReturn(any(Foo.class)) in Mockito, for instance. Mockito needs to know exactly which instance to return in stubbing calls, and will not choose an arbitrary return value for you.

Implementation details

Matchers are stored (as Hamcrest-style object matchers) in a stack contained in a class called ArgumentMatcherStorage. MockitoCore and Matchers each own a ThreadSafeMockingProgress instance, which statically contains a ThreadLocal holding MockingProgress instances. It's this MockingProgressImpl that holds a concrete ArgumentMatcherStorageImpl. Consequently, mock and matcher state is static but thread-scoped consistently between the Mockito and Matchers classes.

Most matcher calls only add to this stack, with an exception for matchers like and, or, and not. This perfectly corresponds to (and relies on) the evaluation order of Java, which evaluates arguments left-to-right before invoking a method:

when(foo.quux(anyInt(), and(gt(10), lt(20)))).thenReturn(true);
[6]      [5]  [1]       [4] [2]     [3]

This will:

  1. Add anyInt() to the stack.
  2. Add gt(10) to the stack.
  3. Add lt(20) to the stack.
  4. Remove gt(10) and lt(20) and add and(gt(10), lt(20)).
  5. Call foo.quux(0, 0), which (unless otherwise stubbed) returns the default value false. Internally Mockito marks quux(int, int) as the most recent call.
  6. Call when(false), which discards its argument and prepares to stub method quux(int, int) identified in 5. The only two valid states are with stack length 0 (equality) or 2 (matchers), and there are two matchers on the stack (steps 1 and 4), so Mockito stubs the method with an any() matcher for its first argument and and(gt(10), lt(20)) for its second argument and clears the stack.

This demonstrates a few rules:

  • Mockito can't tell the difference between quux(anyInt(), 0) and quux(0, anyInt()). They both look like a call to quux(0, 0) with one int matcher on the stack. Consequently, if you use one matcher, you have to match all arguments.

  • Call order isn't just important, it's what makes this all work. Extracting matchers to variables generally doesn't work, because it usually changes the call order. Extracting matchers to methods, however, works great.

    int between10And20 = and(gt(10), lt(20));
    /* BAD */ when(foo.quux(anyInt(), between10And20)).thenReturn(true);
    // Mockito sees the stack as the opposite: and(gt(10), lt(20)), anyInt().
    public static int anyIntBetween10And20() { return and(gt(10), lt(20)); }
    /* OK */  when(foo.quux(anyInt(), anyIntBetween10And20())).thenReturn(true);
    // The helper method calls the matcher methods in the right order.
  • The stack changes often enough that Mockito can't police it very carefully. It can only check the stack when you interact with Mockito or a mock, and has to accept matchers without knowing whether they're used immediately or abandoned accidentally. In theory, the stack should always be empty outside of a call to when or verify, but Mockito can't check that automatically. You can check manually with Mockito.validateMockitoUsage().

  • In a call to when, Mockito actually calls the method in question, which will throw an exception if you've stubbed the method to throw an exception (or require non-zero or non-null values). doReturn and doAnswer (etc) do not invoke the actual method and are often a useful alternative.

  • If you had called a mock method in the middle of stubbing (e.g. to calculate an answer for an eq matcher), Mockito would check the stack length against that call instead, and likely fail.

  • If you try to do something bad, like stubbing/verifying a final method, Mockito will call the real method and also leave extra matchers on the stack. The final method call may not throw an exception, but you may get an InvalidUseOfMatchersException from the stray matchers when you next interact with a mock.

Common problems

  • InvalidUseOfMatchersException:

    • Check that every single argument has exactly one matcher call, if you use matchers at all, and that you haven't used a matcher outside of a when or verify call. Matchers should never be used as stubbed return values or fields/variables.

    • Check that you're not calling a mock as a part of providing a matcher argument.

    • Check that you're not trying to stub/verify a final method with a matcher. It's a great way to leave a matcher on the stack, and unless your final method throws an exception, this might be the only time you realize the method you're mocking is final.

  • NullPointerException with primitive arguments: (Integer) any() returns null while any(Integer.class) returns 0; this can cause a NullPointerException if you're expecting an int instead of an Integer. In any case, prefer anyInt(), which will return zero and also skip the auto-boxing step.

  • NullPointerException or other exceptions: Calls to when( will actually call, which you might have stubbed to throw an exception when receiving a null argument. Switching to doReturn(baz).when(foo).bar(any()) skips the stubbed behavior.

General troubleshooting

  • Use MockitoJUnitRunner, or explicitly call validateMockitoUsage in your tearDown or @After method (which the runner would do for you automatically). This will help determine whether you've misused matchers.

  • For debugging purposes, add calls to validateMockitoUsage in your code directly. This will throw if you have anything on the stack, which is a good warning of a bad symptom.

How do I run a batch script from within a batch script?

If you wish to open the batch file in another window, use start. This way, you can basically run two scripts at the same time. In other words, you don't have to wait for the script you just called to finish. All examples below work:

start batch.bat
start call batch.bat
start cmd /c batch.bat

If you want to wait for the script to finish, try start /w call batch.bat, but the batch.bat has to end with exit.

Can we install Android OS on any Windows Phone and vice versa, and same with iPhone and vice versa?

Ok, For installing Android on Windows phone, I think you can..(But your window phone has required configuration to run Android) (For other I don't know If I will then surely post here)

Just go through these links,

Run Android on Your Windows Mobile Phone

full tutorial on how to put android on windows mobile touch pro 2

How to install Android on most Windows Mobile phones


For Windows 7 to Android device, this also possible, (You need to do some hack for this)

Just go through these links,

Install Windows Phone 7 Mango on HTC HD2 [How-To Guide]

HTC HD2: How To Install WP7 (Windows Phone 7) & MAGLDR 1.13 To NAND

Install windows phone 7 on android and iphones | Tips and Tricks

How to install Windows Phone 7 on HTC HD2? (Video)

To Install Android on your iOS Devices (This also possible...)

Look at How To Install Android on your iOS Devices

Android 2.2 Froyo running on Iphone

How to convert a UTF-8 string into Unicode?

So the issue is that UTF-8 code unit values have been stored as a sequence of 16-bit code units in a C# string. You simply need to verify that each code unit is within the range of a byte, copy those values into bytes, and then convert the new UTF-8 byte sequence into UTF-16.

public static string DecodeFromUtf8(this string utf8String)
    // copy the string as UTF-8 bytes.
    byte[] utf8Bytes = new byte[utf8String.Length];
    for (int i=0;i<utf8String.Length;++i) {
        //Debug.Assert( 0 <= utf8String[i] && utf8String[i] <= 255, "the char must be in byte's range");
        utf8Bytes[i] = (byte)utf8String[i];

    return Encoding.UTF8.GetString(utf8Bytes,0,utf8Bytes.Length);

DecodeFromUtf8("d\u00C3\u00A9j\u00C3\u00A0"); // déjà

This is easy, however it would be best to find the root cause; the location where someone is copying UTF-8 code units into 16 bit code units. The likely culprit is somebody converting bytes into a C# string using the wrong encoding. E.g. Encoding.Default.GetString(utf8Bytes, 0, utf8Bytes.Length).

Alternatively, if you're sure you know the incorrect encoding which was used to produce the string, and that incorrect encoding transformation was lossless (usually the case if the incorrect encoding is a single byte encoding), then you can simply do the inverse encoding step to get the original UTF-8 data, and then you can do the correct conversion from UTF-8 bytes:

public static string UndoEncodingMistake(string mangledString, Encoding mistake, Encoding correction)
    // the inverse of `mistake.GetString(originalBytes);`
    byte[] originalBytes = mistake.GetBytes(mangledString);
    return correction.GetString(originalBytes);

UndoEncodingMistake("d\u00C3\u00A9j\u00C3\u00A0", Encoding(1252), Encoding.UTF8);

What is the difference between AF_INET and PF_INET in socket programming?

In fact, AF_ and PF_ are the same thing. There are some words on Wikipedia will clear your confusion

The original design concept of the socket interface distinguished between protocol types (families) and the specific address types that each may use. It was envisioned that a protocol family may have several address types. Address types were defined by additional symbolic constants, using the prefix AF_ instead of PF_. The AF_-identifiers are intended for all data structures that specifically deal with the address type and not the protocol family. However, this concept of separation of protocol and address type has not found implementation support and the AF_-constants were simply defined by the corresponding protocol identifier, rendering the distinction between AF_ versus PF_ constants a technical argument of no significant practical consequence. Indeed, much confusion exists in the proper usage of both forms.

How to add time to DateTime in SQL

For me, this code looks more explicit:

CAST(@SomeDate AS datetime) + CAST(@SomeTime AS datetime)

What is the syntax of the enhanced for loop in Java?

An enhanced for loop is just limiting the number of parameters inside the parenthesis.

for (int i = 0; i < myArray.length; i++) {

Can be written as:

for (int myValue : myArray) {

List names of all tables in a SQL Server 2012 schema

SQL Server 2005, 2008, 2012 or 2014:

SELECT * FROM information_schema.tables WHERE TABLE_TYPE='BASE TABLE' AND TABLE_SCHEMA = 'dbo'

For more details: How do I get list of all tables in a database using TSQL?

Check if a Bash array contains a value

My version of the regular expressions technique that's been suggested already:

values=(foo bar)

[[ "${values[@]/#/X-}" =~ "X-${requestedValue}" ]] || echo "Unsupported value"

What's happening here is that you're expanding the entire array of supported values into words and prepending a specific string, "X-" in this case, to each of them, and doing the same to the requested value. If this one is indeed contained in the array, then the resulting string will at most match one of the resulting tokens, or none at all in the contrary. In the latter case the || operator triggers and you know you're dealing with an unsupported value. Prior to all of that the requested value is stripped of all leading and trailing whitespace through standard shell string manipulation.

It's clean and elegant, I believe, though I'm not too sure of how performant it may be if your array of supported values is particularly large.

Getting the absolute path of the executable, using C#?

The one that worked for me and isn't above was Process.GetCurrentProcess().MainModule.FileName.

cast a List to a Collection

There have multiple solusions to convert list to a collection

Solution 1

List<Contact> CONTACTS = new ArrayList<String>();
// fill CONTACTS
Collection<Contact> c = CONTACTS;

Solution 2

private static final Collection<String> c = new ArrayList<String>(
                                                Arrays.asList("a", "b", "c"));

Solution 3

private static final Collection<Contact> = new ArrayList<Contact>(
                       Arrays.asList(new Contact("text1", "name1")
                                     new Contact("text2", "name2")));

Solution 4

List<? extends Contact> col = new ArrayList<Contact>(CONTACTS);

Clicking HTML 5 Video element to play, pause video, breaks play button

I had countless issues doing this but finally came up with a solution that works.

Basically the code below is adding a click handler to the video but ignoring all the clicks on the lower part (0.82 is arbitrary but seems to work on all sizes).


        // get click position 
        var clickY = (e.pageY - $(this).offset().top);
        var height = parseFloat( $(this).height() );

        // avoids interference with controls
        if(y > 0.82*height) return;

        // toggles play / pause
        this.paused ? : this.pause();


Transferring files over SSH

You need to scp something somewhere. You have scp ./styles/, so you're saying secure copy ./styles/, but not where to copy it to.

Generally, if you want to download, it will go:

# download: remote -> local
scp user@remote_host:remote_file local_file 

where local_file might actually be a directory to put the file you're copying in. To upload, it's the opposite:

# upload: local -> remote
scp local_file user@remote_host:remote_file

If you want to copy a whole directory, you will need -r. Think of scp as like cp, except you can specify a file with user@remote_host:file as well as just local files.

Edit: As noted in a comment, if the usernames on the local and remote hosts are the same, then the user can be omitted when specifying a remote file.

how to remove json object key and value.?

I had issues with trying to delete a returned JSON object and found that it was actually a string. If you JSON.parse() before deleting you can be sure your key will get deleted.

let obj;
console.log(this.getBody()); // {"AED":3.6729,"AZN":1.69805,"BRL":4.0851}
obj = this.getBody();
delete obj["BRL"];
console.log(obj) // {"AED":3.6729,"AZN":1.69805,"BRL":4.0851}
obj = JSON.parse(this.getBody());
delete obj["BRL"];
console.log(obj) // {"AED":3.6729,"AZN":1.69805}

How do I use reflection to call a generic method?

Just an addition to the original answer. While this will work:

MethodInfo method = typeof(Sample).GetMethod("GenericMethod");
MethodInfo generic = method.MakeGenericMethod(myType);
generic.Invoke(this, null);

It is also a little dangerous in that you lose compile-time check for GenericMethod. If you later do a refactoring and rename GenericMethod, this code won't notice and will fail at run time. Also, if there is any post-processing of the assembly (for example obfuscating or removing unused methods/classes) this code might break too.

So, if you know the method you are linking to at compile time, and this isn't called millions of times so overhead doesn't matter, I would change this code to be:

Action<> GenMethod = GenericMethod<int>;  //change int by any base type 
                                          //accepted by GenericMethod
MethodInfo method = this.GetType().GetMethod(GenMethod.Method.Name);
MethodInfo generic = method.MakeGenericMethod(myType);
generic.Invoke(this, null);

While not very pretty, you have a compile time reference to GenericMethod here, and if you refactor, delete or do anything with GenericMethod, this code will keep working, or at least break at compile time (if for example you remove GenericMethod).

Other way to do the same would be to create a new wrapper class, and create it through Activator. I don't know if there is a better way.

Multiple file extensions in OpenFileDialog

This is from MSDN sample:

(*.bmp, *.jpg)|*.bmp;*.jpg

So for your case

openFileDialog1.Filter = "JPG (*.jpg,*.jpeg)|*.jpg;*.jpeg|TIFF (*.tif,*.tiff)|*.tif;*.tiff"

momentJS date string add 5 days

  1. add to your html page
  2. var todayDate = moment().format('DD-MM-YYYY');//to get today date 06/03/2018 if you want to add extra day to your current date then
  3. var dueDate = moment().add(15,'days').format('DD-MM-YYYY')// to add 15 days to current date..

point 2 and 3 are using in your jquery code...

Convert Object to JSON string

Convert JavaScript object to json data

  var formData = $("form").serializeArray(); // Create array of object
  var jsonConvertedData = JSON.stringify(formData);  // Convert to json

You can validate json data using

javascript set cookie with expire time

document.cookie = "cookie_name=cookie_value; max-age=31536000; path=/";

Will set the value for a year.

Entity Framework Core: DbContextOptionsBuilder does not contain a definition for 'usesqlserver' and no extension method 'usesqlserver'

Easy way to fix this issue

Error message:
enter image description here

to install "microsoft.entityframeworkcore.sqlserver" with NuGet
enter image description here

Fixed :
enter image description here

PS: make sure you have using EF on the content "using Microsoft.EntityFrameworkCore;" enter image description here

Error: Cannot find module html

Simple way is to use the EJS template engine for serving .html files. Put this line right next to your view engine setup:

app.engine('html', require('ejs').renderFile);

IndentationError expected an indented block

You've mixed tabs and spaces. This can lead to some confusing errors.

I'd suggest using only tabs or only spaces for indentation.

Using only spaces is generally the easier choice. Most editors have an option for automatically converting tabs to spaces. If your editor has this option, turn it on.

As an aside, your code is more verbose than it needs to be. Instead of this:

if str_p == str_q:
    result = True
    result = False
return result

Just do this:

return str_p == str_q

You also appear to have a bug on this line:

str_q = p[b+1:]

I'll leave you to figure out what the error is.

Redirect to a page/URL after alert button is pressed

    function myFunction() {
        var x;
        var r = confirm("Do you want to clear data?");
        if (r == true) {
            x = "Your Data is Cleared";
            window.location.href = "firstpage.php";
        else {
            x = "You pressed Cancel!";
        document.getElementById("demo").innerHTML = x;
<button onclick="myFunction()">Retest</button>

<p id="demo"></p>

This will redirect to new php page.

Django REST Framework: adding additional field to ModelSerializer

This worked for me. If we want to just add an additional field in ModelSerializer, we can do it like below, and also the field can be assigned some val after some calculations of lookup. Or in some cases, if we want to send the parameters in API response.


class Foo(models.Model):
    """Model Foo"""
    name = models.CharField(max_length=30, help_text="Customer Name")


class FooSerializer(serializers.ModelSerializer):
    retrieved_time = serializers.SerializerMethodField()
    def get_retrieved_time(self, object):
        """getter method to add field retrieved_time"""
        return None

  class Meta:
        model = Foo
        fields = ('id', 'name', 'retrieved_time ')

Hope this could help someone.

How to get input text value from inside td

var values = {};
$('td input').each(function(){
  values[$(this).attr('name')] = $(this).val();

Haven't tested, but that should do it...

CSS position:fixed inside a positioned element

Seems, css transforms can be used

"‘transform’ property establishes a new local coordinate system at the element",

but ... this is not cross-browser, seems only Opera works correctly

How can I replace a regex substring match in Javascript?

I think the simplest way to achieve your goal is this:

var str   = 'asd-0.testing';
var regex = /(asd-)(\d)(\.\w+)/;
var anyNumber = 1;
var res = str.replace(regex, `$1${anyNumber}$3`);

in_array multiple values

IMHO Mark Elliot's solution's best one for this problem. If you need to make more complex comparison operations between array elements AND you're on PHP 5.3, you might also think about something like the following:


// First Array To Compare
$a1 = array('foo','bar','c');

// Target Array
$b1 = array('foo','bar');

// Evaluation Function - we pass guard and target array
$test = function($x) use (&$b, $b1) {
        if (!in_array($x,$b1)) {

// Actual Test on array (can be repeated with others, but guard 
// needs to be initialized again, due to by reference assignment above)
array_walk($a1, $test);

This relies on a closure; comparison function can become much more powerful. Good luck!

How to add a second css class with a conditional value in razor MVC 4

You can use String.Format function to add second class based on condition:

<div class="@String.Format("details {0}", Details.Count > 0 ? "show" : "hide")">

How to make a WPF window be on top of all other windows of my app (not system wide)?

The best way is set this two events to all of windows of your app:


in this way:

WiondowOfMyApp_GotKeyboardFocus(object sender, System.Windows.Input.KeyboardFocusChangedEventArgs e)
    windowThatShouldBeTopMost.TopMost = true;

WiondowOfMyApp_LostKeyboardFocus(object sender, System.Windows.Input.KeyboardFocusChangedEventArgs e)
    windowThatShouldBeTopMost.TopMost = false;
  • and surely all of the windows that you wanted to be top, should be accessible from other windows of your app. in my case I have a base window and another some windows that should be top of my base window, so this was not bad to my base window has instance of each another windows.

How do I force files to open in the browser instead of downloading (PDF)?

Oops, there were typing errors in my previous post.

    header("Content-Type: application/force-download");
    header("Content-type: application/pdf");
    header("Content-Disposition: inline; filename=\"".$name."\";");

If you don't want the browser to prompt the user then use "inline" for the third string instead of "attachment". Inline works very well. The PDF display immediately without asking the user to click on Open. I've used "attachment" and this will prompt the user for Open, Save. I've tried to change the browser setting nut it doesn't prevent the prompt.

Inline JavaScript onclick function

This should work

 <a href="#" onclick="function hi(){alert('Hi!')};hi()">click</a>

You may inline any javascript inside the onclick as if you were assigning the method through javascript. I think is just a matter of making code cleaner keeping your js inside a script block

Programmatically check Play Store for app updates

Update 17 October 2019

Update 24 april 2019:

Android announced a feature which will probably fix this problem. Using the in-app Updates API:


As far a I know, there is no official Google API which supports this.

You should consider to get a version number from an API.

Instead of connecting to external APIs or webpages (like Google Play Store). There is a risk that something may change in the API or the webpage, so you should consider to check if the version code of the current app is below the version number you get from your own API.

Just remember if you update your app, you need to change the version in your own API with the app version number.

I would recommend that you make a file in your own website or API, with the version number. (Eventually make a cronjob and make the version update automatic, and send a notification when something goes wrong)

You have to get this value from your Google Play Store page (is changed in the meantime, not working anymore):

<div class="content" itemprop="softwareVersion"> x.x.x  </div>

Check in your app if the version used on the mobile is below the version nummer showed on your own API.

Show indication that she/he needs to update with a notification, ideally.

Things you can do

Version number using your own API


  • No need to load the whole code of the Google Play Store (saves on data/bandwidth)


  • User can be offline, which makes checking useless since the API can't be accessed

Version number on webpage Google Play Store


  • You don't need an API


  • User can be offline, which makes checking useless since the API can't be accessed
    • Using this method may cost your users more bandwidth/mobile data
    • Play store webpage could change which makes your version 'ripper' not work anymore.

Equal sized table cells to fill the entire width of the containing table

You don't even have to set a specific width for the cells, table-layout: fixed suffices to spread the cells evenly.

ul {_x000D_
    width: 100%;_x000D_
    display: table;_x000D_
    table-layout: fixed;_x000D_
    border-collapse: collapse;_x000D_
li {_x000D_
    display: table-cell;_x000D_
    text-align: center;_x000D_
    border: 1px solid hotpink;_x000D_
    vertical-align: middle;_x000D_
    word-wrap: break-word;_x000D_

Note that for table-layout to work the table styled element must have a width set (100% in my example).

jQuery UI Dialog window loaded within AJAX style jQuery UI Tabs

Just an addition to nicktea's answer. This code loads the content of a remote page (without redirecting there), and also cleans up when closing it.

<script type="text/javascript">
    function showDialog() {
            modal: true,
            open: function () {
            close: function(event, ui) {
            height: 400,
            width: 600,
            title: 'Ajax Page'

        return false;

$(...).datepicker is not a function - JQuery - Bootstrap

 <script type="text/javascript">

    var options={
            format: 'mm/dd/yyyy',
            todayHighlight: true,
            autoclose: true,



How to import .py file from another directory?


import importlib.machinery

loader = importlib.machinery.SourceFileLoader('report', '/full/path/report/')
handle = loader.load_module('report')


This method can be used to import whichever way you want in a folder structure (backwards, forwards doesn't really matter, i use absolute paths just to be sure).

There's also the more normal way of importing a python module in Python3,

import importlib
module = importlib.load_module('folder.filename')

Kudos to Sebastian for spplying a similar answer for Python2:

import imp

foo = imp.load_source('', '/path/to/')

How do I sort a Set to a List in Java?

List myList = new ArrayList(collection);

… should do the trick however. Add flavour with Generics where applicable.

What is Ad Hoc Query?

An Ad-hoc query is one created to provide a specific recordset from any or multiple merged tables available on the DB server. These queries usually serve a single-use purpose, and may not be necessary to incorporate into any stored procedure to run again in the future.

Ad-hoc scenario: You receive a request for a specific subset of data with a unique set of variables. If there is no pre-written query that can provide the necessary results, you must write an Ad-hoc query to generate the recordset results.

Beyond a single use Ad-hoc query are stored procedures; i.e. queries which are stored within the DB interface tool. These stored procedures can then be executed in sequence within a module or macro to accomplish a predefined task either on demand, on a schedule, or triggered by another event.

Stored Procedure scenario: Every month you need to generate a report from the same set of tables and with the same variables (these variables may be specific predefined values, computed values such as “end of current month”, or a user’s input values). You would created the procedure as an ad-hoc query the first time. After testing the results to ensure accuracy, you may chose to deploy this query. You would then store the query or series of queries in a module or macro to run again as needed.

Accessing Objects in JSON Array (JavaScript)

Use a loop

for(var i = 0; i < obj.length; ++i){
   //do something with obj[i]
   for(var ind in obj[i]) {
        for(var vals in obj[i][ind]){
            console.log(vals, obj[i][ind][vals]);


javascript create array from for loop

Remove obj and just do this inside your for loop:


Also, the i < yearEnd condition will not include the final year, so change it to i <= yearEnd.

Setting cursor at the end of any text of a textbox

Try like below... it will help you...

Some time in Window Form Focus() doesn't work correctly. So better you can use Select() to focus the textbox.

txtbox.Select(); // to Set Focus
txtbox.Select(txtbox.Text.Length, 0); //to set cursor at the end of textbox

Maven home (M2_HOME) not being picked up by IntelliJ IDEA

In case you don't want to use the M2_HOME and want to direct the IntelliJ to the maven installation you can simply set it by:

  • goto File => Setting => Maven => Maven home directory
  • point to your maven build directory e.g. /usr/local/maven/apache-maven-3.0.4

A better way is to have a symlink e.g. 'latest' for the latest version and point your IntelliJ to use that for consistency, given latest points to the latest version of maven installed on your box.

Regular Expression for alphanumeric and underscores

For me there was an issue in that I want to distinguish between alpha, numeric and alpha numeric, so to ensure an alphanumeric string contains at least one alpha and at least one numeric, I used :


How can I grep for a string that begins with a dash/hyphen?

grep "^-X" file

It will grep and pick all the lines form the file. ^ in the grep"^" indicates a line starting with

Call Python function from MATLAB

You could embed your Python script in a C program and then MEX the C program with MATLAB but that might be a lot of work compared dumping the results to a file.

You can call MATLAB functions in Python using PyMat. Apart from that, SciPy has several MATLAB duplicate functions.

But if you need to run Python scripts from MATLAB, you can try running system commands to run the script and store the results in a file and read it later in MATLAB.

Parenthesis/Brackets Matching using Stack algorithm

import java.util.*;

class StackDemo {

    public static void main(String[] argh) {
        boolean flag = true;
        String str = "(()){}()";
        int l = str.length();
        flag = true;
        Stack<String> st = new Stack<String>();
        for (int i = 0; i < l; i++) {
            String test = str.substring(i, i + 1);
            if (test.equals("(")) {
            } else if (test.equals("{")) {
            } else if (test.equals("[")) {
            } else if (test.equals(")")) {
                if (st.empty()) {
                    flag = false;
                if (st.peek().equals("(")) {
                } else {
                    flag = false;
            } else if (test.equals("}")) {
                if (st.empty()) {
                    flag = false;
                if (st.peek().equals("{")) {
                } else {
                    flag = false;
            } else if (test.equals("]")) {
                if (st.empty()) {
                    flag = false;
                if (st.peek().equals("[")) {
                } else {
                    flag = false;
        if (flag && st.empty())

Ruby: What is the easiest way to remove the first element from an array?

You can use:

arr - [arr[0]]


arr - [arr.shift]

or simply


How can I write output from a unit test?

Console.WriteLine won't work. Only Debug.WriteLine() or Trace.WriteLine() will work, in debug mode.

I do the following: include using System.Diagnostics in the test module. Then, use Debug.WriteLine for my output, right click on the test, choose Debug Selected Tests. The result output will now appear in the Output window below. I use Visual Studio 2017 vs 15.8.1, with the default unit test framework VS provides.

How to force Chrome browser to reload .css file while debugging in Visual Studio?

Current version of Chrome (55.x) does not reload all resources when you reload the page (Command + R) - and that is not useful for debugging the .css file.

Command + R works fine if you want to debug only the .html, .php, .etc files, and is faster because works with local/cached resources (.css, .js). To manually delete browser's cache for each debug iteration is not convenient.

Procedure to force reload .css file on Mac (Keyboard Shortcut / Chrome): Command + Shift + R

How do I collapse a table row in Bootstrap?

You are using collapse on the div inside of your table row (tr). So when you collapse the div, the row is still there. You need to change it to where your id and class are on the tr instead of the div.

Change this:

<tr><td><div class="collapse out" id="collapseme">Should be collapsed</div></td></tr>

to this:

<tr class="collapse out" id="collapseme"><td><div>Should be collapsed</div></td></tr>


EDIT: If you are unable to upgrade to 3.0.0, I found a JQuery workaround in 2.3.2:

Remove your data-toggle and data-target and add this JQuery to your button.

$(".btn").click(function() {
    if($("#collapseme").hasClass("out")) {
    } else {


Get commit list between tags in git

To compare between latest commit of current branch and a tag:

git log --pretty=oneline HEAD...tag

How to check if a network port is open on linux?

In case when you probing TCP ports with intention to listen on it, it’s better to actually call listen. The approach with tring to connect don’t 'see' client ports of established connections, because nobody listen on its. But these ports cannot be used to listen on its.

import socket

def check_port(port, rais=True):
    """ True -- it's possible to listen on this port for TCP/IPv4 or TCP/IPv6
    connections. False -- otherwise.
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.bind(('', port))
        sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
        sock.bind(('::1', port))
    except socket.error as e:
        return False
        if rais:
            raise RuntimeError(
                "The server is already running on port {0}".format(port))
    return True

How do I upload a file with the JS fetch API?

The accepted answer here is a bit dated. As of April 2020, a recommended approach seen on the MDN website suggests using FormData and also does not ask to set the content type.

I'm quoting the code snippet for convenience:

const formData = new FormData();
const fileField = document.querySelector('input[type="file"]');

formData.append('username', 'abc123');
formData.append('avatar', fileField.files[0]);

fetch('', {
  method: 'PUT',
  body: formData
.then((response) => response.json())
.then((result) => {
  console.log('Success:', result);
.catch((error) => {
  console.error('Error:', error);

Adding +1 to a variable inside a function

Move points into test:

def test():
    points = 0
    addpoint = raw_input ("type ""add"" to add a point")

or use global statement, but it is bad practice. But better way it move points to parameters:

def test(points=0):
    addpoint = raw_input ("type ""add"" to add a point")

Synchronous XMLHttpRequest warning and <script>

In my case if i append script tag like this :

var script = document.createElement('script');
script.src = 'url/test.js';

i get that warning but if i append script tag to head first then change src warning gone !

var script = document.createElement('script');
script.src = 'url/test.js';

works fine!!

Random / noise functions for GLSL

Gold Noise

// Gold Noise ©2015 [email protected]
// - based on the Golden Ratio
// - uniform normalized distribution
// - fastest static noise generator function (also runs at low precision)

float PHI = 1.61803398874989484820459;  // F = Golden Ratio   

float gold_noise(in vec2 xy, in float seed){
       return fract(tan(distance(xy*PHI, xy)*seed)*xy.x);

See Gold Noise in your browser right now!

enter image description here

This function has improved random distribution over the current function in @appas' answer as of Sept 9, 2017:

enter image description here

The @appas function is also incomplete, given there is no seed supplied (uv is not a seed - same for every frame), and does not work with low precision chipsets. Gold Noise runs at low precision by default (much faster).

JPQL IN clause: Java-Arrays (or Lists, Sets...)?

I had a problem with this kind of sql, I was giving empty list in IN clause(always check the list if it is not empty). Maybe my practice will help somebody.

How do I render a shadow?

You have to give elevation prop to View

<View elevation={5} style={styles.container}>
   <Text>Hello World !</Text>

styles can be added like this:

 const styles = StyleSheet.create({

        shadowColor: "#000000",
        shadowOpacity: 0.8,
        shadowRadius: 2,
        shadowOffset: {
          height: 1,
          width: 1

How do I get the opposite (negation) of a Boolean in Python?

The not operator (logical negation)

Probably the best way is using the operator not:

>>> value = True
>>> not value

>>> value = False
>>> not value

So instead of your code:

if bool == True:
    return False
    return True

You could use:

return not bool

The logical negation as function

There are also two functions in the operator module operator.not_ and it's alias operator.__not__ in case you need it as function instead of as operator:

>>> import operator
>>> operator.not_(False)
>>> operator.not_(True)

These can be useful if you want to use a function that requires a predicate-function or a callback.

For example map or filter:

>>> lst = [True, False, True, False]
>>> list(map(operator.not_, lst))
[False, True, False, True]

>>> lst = [True, False, True, False]
>>> list(filter(operator.not_, lst))
[False, False]

Of course the same could also be achieved with an equivalent lambda function:

>>> my_not_function = lambda item: not item

>>> list(map(my_not_function, lst))
[False, True, False, True]

Do not use the bitwise invert operator ~ on booleans

One might be tempted to use the bitwise invert operator ~ or the equivalent operator function operator.inv (or one of the other 3 aliases there). But because bool is a subclass of int the result could be unexpected because it doesn't return the "inverse boolean", it returns the "inverse integer":

>>> ~True
>>> ~False

That's because True is equivalent to 1 and False to 0 and bitwise inversion operates on the bitwise representation of the integers 1 and 0.

So these cannot be used to "negate" a bool.

Negation with NumPy arrays (and subclasses)

If you're dealing with NumPy arrays (or subclasses like pandas.Series or pandas.DataFrame) containing booleans you can actually use the bitwise inverse operator (~) to negate all booleans in an array:

>>> import numpy as np
>>> arr = np.array([True, False, True, False])
>>> ~arr
array([False,  True, False,  True])

Or the equivalent NumPy function:

>>> np.bitwise_not(arr)
array([False,  True, False,  True])

You cannot use the not operator or the operator.not function on NumPy arrays because these require that these return a single bool (not an array of booleans), however NumPy also contains a logical not function that works element-wise:

>>> np.logical_not(arr)
array([False,  True, False,  True])

That can also be applied to non-boolean arrays:

>>> arr = np.array([0, 1, 2, 0])
>>> np.logical_not(arr)
array([ True, False, False,  True])

Customizing your own classes

not works by calling bool on the value and negate the result. In the simplest case the truth value will just call __bool__ on the object.

So by implementing __bool__ (or __nonzero__ in Python 2) you can customize the truth value and thus the result of not:

class Test(object):
    def __init__(self, value):
        self._value = value

    def __bool__(self):
        print('__bool__ called on {!r}'.format(self))
        return bool(self._value)

    __nonzero__ = __bool__  # Python 2 compatibility

    def __repr__(self):
        return '{self.__class__.__name__}({self._value!r})'.format(self=self)

I added a print statement so you can verify that it really calls the method:

>>> a = Test(10)
>>> not a
__bool__ called on Test(10)

Likewise you could implement the __invert__ method to implement the behavior when ~ is applied:

class Test(object):
    def __init__(self, value):
        self._value = value

    def __invert__(self):
        print('__invert__ called on {!r}'.format(self))
        return not self._value

    def __repr__(self):
        return '{self.__class__.__name__}({self._value!r})'.format(self=self)

Again with a print call to see that it is actually called:

>>> a = Test(True)
>>> ~a
__invert__ called on Test(True)

>>> a = Test(False)
>>> ~a
__invert__ called on Test(False)

However implementing __invert__ like that could be confusing because it's behavior is different from "normal" Python behavior. If you ever do that clearly document it and make sure that it has a pretty good (and common) use-case.

The type or namespace name does not exist in the namespace 'System.Web.Mvc'

I had the same problem, none of the solutions worked for me, Finally I removed the System.Web.MVC and added again Then everything was back to normal and my problem solved.

Find OpenCV Version Installed on Ubuntu

The other methods here didn't work for me, so here's what does work in Ubuntu 12.04 'precise'.

On Ubuntu and other Debian-derived platforms, dpkg is the typical way to get software package versions. For more recent versions than the one that @Tio refers to, use

 dpkg -l | grep libopencv

If you have the development packages installed, like libopencv-core-dev, you'll probably have .pc files and can use pkg-config:

 pkg-config --modversion opencv

How do I set cell value to Date and apply default Excel date format?

This code sample can be used to change date format. Here I want to change from yyyy-MM-dd to dd-MM-yyyy. Here pos is position of column.

import org.apache.poi.xssf.usermodel.XSSFCellStyle;
import org.apache.poi.xssf.usermodel.XSSFColor;
import org.apache.poi.xssf.usermodel.XSSFFont;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

class Test{ 
public static void main( String[] args )
String input="D:\\somefolder\\somefile.xlsx";
String output="D:\\somefolder\\someoutfile.xlsx"
FileInputStream file = new FileInputStream(new File(input));
XSSFWorkbook workbook = new XSSFWorkbook(file);
XSSFSheet sheet = workbook.getSheetAt(0);
Iterator<Row> iterator = sheet.iterator();
Cell cell = null;
Row row=null;;
int pos=5; // 5th column is date.

    //CellStyle cellStyle = wb.createCellStyle();
    XSSFCellStyle cellStyle = (XSSFCellStyle)cell.getCellStyle();
    CreationHelper createHelper = wb.getCreationHelper();
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    Date d=null;
    try {
        d= sdf.parse(cell.getStringCellValue());
    } catch (ParseException e) {
        // TODO Auto-generated catch block

FileOutputStream outFile =new FileOutputStream(new File(output));

"Repository does not have a release file" error

#For Unable to 'apt update' my Ubuntu 19.04

The repositories for older releases that are not supported (like 11.04, 11.10 and 13.04) get moved to an archive server. There are repositories available at

first break up this file

cp /etc/apt/sources.list /etc/apt/sources.list.bak sudo sed -i -re 's/([a-z]{2}.)?|' /etc/apt/sources.list


sudo apt-get update && sudo apt-get dist-upgrade

Function for 'does matrix contain value X?'

For floating point data, you can use the new ismembertol function, which computes set membership with a specified tolerance. This is similar to the ismemberf function found in the File Exchange except that it is now built-in to MATLAB. Example:

>> pi_estimate = 3.14159;
>> abs(pi_estimate - pi)
ans =
>> tol = 1e-7;
>> ismembertol(pi,pi_estimate,tol)
ans =

How can I add or update a query string parameter?

Here's my slightly different approach to this, written as an excercise

function addOrChangeParameters( url, params )
  let splitParams = {};
  let splitPath = (/(.*)[?](.*)/).exec(url);
  if ( splitPath && splitPath[2] )
    splitPath[2].split("&").forEach( k => { let d = k.split("="); splitParams[d[0]] = d[1]; } );
  let newParams = Object.assign( splitParams, params );
  let finalParams = Object.keys(newParams).map( (a) => a+"="+newParams[a] ).join("&");
  return splitPath ? (splitPath[1] + "?" + finalParams) : (url + "?" + finalParams);


const url = "";

addOrChangeParameters( url, {value1:1, empty:"empty", new:0} )


How to use a TRIM function in SQL Server


I think you're missing a ) on both of the trims. Some SQL versions support just TRIM which does both L and R trims...

Quickest way to convert a base 10 number to any base in .NET?

I was using this to store a Guid as a shorter string (but was limited to use 106 characters). If anyone is interested here is my code for decoding the string back to numeric value (in this case I used 2 ulongs for the Guid value, rather than coding an Int128 (since I'm in 3.5 not 4.0). For clarity CODE is a string const with 106 unique chars. ConvertLongsToBytes is pretty unexciting.

private static Guid B106ToGuid(string pStr)
            ulong tMutl = 1, tL1 = 0, tL2 = 0, targetBase = (ulong)CODE.Length;
            for (int i = 0; i < pStr.Length / 2; i++)
                tL1 += (ulong)CODE.IndexOf(pStr[i]) * tMutl;
                tL2 += (ulong)CODE.IndexOf(pStr[pStr.Length / 2 + i]) * tMutl;
                tMutl *= targetBase;
            return new Guid(ConvertLongsToBytes(tL1, tL2));
        catch (Exception ex)
            throw new Exception("B106ToGuid failed to convert string to Guid", ex);

Make a bucket public in Amazon S3

You can set a bucket policy as detailed in this blog post:

As per @robbyt's suggestion, create a bucket policy with the following JSON:

  "Version": "2008-10-17",
  "Statement": [{
    "Sid": "AllowPublicRead",
    "Effect": "Allow",
    "Principal": { "AWS": "*" },
    "Action": ["s3:GetObject"],
    "Resource": ["arn:aws:s3:::bucket/*" ]

Important: replace bucket in the Resource line with the name of your bucket.

'mvn' is not recognized as an internal or external command, operable program or batch file

This problem arise because there is no any environmental variable corresponding to installed maven in your OS. For fixing this problem, I always use Intellij's bundled Maven and do not install separate version of Maven again, for finding bundled Maven's path go to intellij and hit Ctrl+Alt+S -> Build, Execution, Deployment -> Build tool -> Maven -> Maven home directory you can find the intellij's bundled maven path there as below image demonstrates.

enter image description here

Then go to System environment variables and set these variables:

Variable name: MAVEN_HOME

Variable value: C:/Program Files/JetBrains/IntelliJ IDEA 2019.3.1/plugins/maven/lib/maven3

enter image description here

After defining system variable MAVEN_HOME find variable path and add this line to the list


enter image description here

Work is done, open command prompt and test it by writing mvn -v. 99 percent of the time it work, if you're among 1 percent, you have to restart your computer.

If you want to use mvn command from intellij's internal terminal you have to restart intellij after setting environment variables, then you shouldn't have any problem running maven command from terminal.

Is there an "exists" function for jQuery?

I see most of the answers here are not accurate as they should be, they check element length, it can be OK in many cases, but not 100%, imagine if number pass to the function instead, so I prototype a function which check all conditions and return the answer as it should be:

$.fn.exists = $.fn.exists || function() { 
  return !!(this.length && (this[0] instanceof HTMLDocument || this[0] instanceof HTMLElement)); 

This will check both length and type, Now you can check it this way:

$(1980).exists(); //return false
$([1,2,3]).exists(); //return false
$({name: 'stackoverflow', url: ''}).exists(); //return false
$([{nodeName: 'foo'}]).exists() // returns false
$('div').exists(); //return true
$('.header').exists(); //return true
$(document).exists(); //return true
$('body').exists(); //return true

ASP.NET MVC Page Won't Load and says "The resource cannot be found"

you must check if you implemented the page in the controller for example:

   public ActionResult Register()
            return View();

Extract XML Value in bash script

As Charles Duffey has stated, XML parsers are best parsed with a proper XML parsing tools. For one time job the following should work.

grep -oPm1 "(?<=<title>)[^<]+"


$ echo "$data"
  <title>15:54:57 - George:</title>
  <description>Diane DeConn? You saw Diane DeConn!</description> 
  <title>15:55:17 - Jerry:</title> 
  <description>Something huh?</description>
$ title=$(grep -oPm1 "(?<=<title>)[^<]+" <<< "$data")
$ echo "$title"
15:54:57 - George:

How to access a mobile's camera from a web app?

You'll want to use getUserMedia to access the camera.

This tutorial outlines the basics of accessing a device camera from the browser:

Note: This works on most Android devices, and in iOS in Safari only.

Rename MySQL database

For impatient mysql users (like me), the solution is:

/etc/init.d/mysql stop
mv /var/lib/mysql/old_database /var/lib/mysql/new_database 
/etc/init.d/mysql start

git status (nothing to commit, working directory clean), however with changes commited

git status output tells you three things by default:

  1. which branch you are on
  2. What is the status of your local branch in relation to the remote branch
  3. If you have any uncommitted files

When you did git commit , it committed to your local repository, thus #3 shows nothing to commit, however, #2 should show that you need to push or pull if you have setup the tracking branch.

If you find the output of git status verbose and difficult to comprehend, try using git status -sb this is less verbose and will show you clearly if you need to push or pull. In your case, the output would be something like:

master...origin/master [ahead 1]

git status is pretty useful, in the workflow you described do a git status -sb: after touching the file, after adding the file and after committing the file, see the difference in the output, it will give you more clarity on untracked, tracked and committed files.

Update #1
This answer is applicable if there was a misunderstanding in reading the git status output. However, as it was pointed out, in the OPs case, the upstream was not set correctly. For that, Chris Mae's answer is correct.

How to catch curl errors in PHP

you can generate curl error after its execution

$url = '';

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result = curl_exec($ch);
    echo 'Request Error:' . curl_error($ch);

and here are curl error code

if someone need more information about curl errors


    [2] => 'CURLE_FAILED_INIT',
    [15] => 'CURLE_FTP_CANT_GET_HOST',
    [18] => 'CURLE_PARTIAL_FILE',
    [21] => 'CURLE_QUOTE_ERROR',
    [23] => 'CURLE_WRITE_ERROR',
    [25] => 'CURLE_UPLOAD_FAILED',
    [26] => 'CURLE_READ_ERROR',
    [27] => 'CURLE_OUT_OF_MEMORY',
    [30] => 'CURLE_FTP_PORT_FAILED',
    [33] => 'CURLE_RANGE_ERROR',
    [34] => 'CURLE_HTTP_POST_ERROR',
    [52] => 'CURLE_GOT_NOTHING',
    [55] => 'CURLE_SEND_ERROR',
    [56] => 'CURLE_RECV_ERROR',
    [59] => 'CURLE_SSL_CIPHER',
    [60] => 'CURLE_SSL_CACERT',
    [64] => 'CURLE_USE_SSL_FAILED',
    [67] => 'CURLE_LOGIN_DENIED',
    [68] => 'CURLE_TFTP_NOTFOUND',
    [69] => 'CURLE_TFTP_PERM',
    [71] => 'CURLE_TFTP_ILLEGAL',
    [75] => 'CURLE_CONV_FAILED',
    [76] => 'CURLE_CONV_REQD',
    [79] => 'CURLE_SSH',
    [81] => 'CURLE_AGAIN',
    [82] => 'CURLE_SSL_CRL_BADFILE',
    [84] => 'CURLE_FTP_PRET_FAILED',
    [84] => 'CURLE_FTP_PRET_FAILED',
    [85] => 'CURLE_RTSP_CSEQ_ERROR',
    [87] => 'CURLE_FTP_BAD_FILE_LIST',
    [88] => 'CURLE_CHUNK_FAILED');


Convert JavaScript String to be all lower case?

toLocaleUpperCase() or lower case functions don't behave like they should do.

For example in my system, Safari 4, Chrome 4 Beta, Firefox 3.5.x it converts strings with Turkish characters incorrectly.

The browsers respond to navigator.language as "en-US", "tr", "en-US" respectively.

But there is no way to get user's Accept-Lang setting in the browser as far as I could find.

Only Chrome gives me trouble although I have configured every browser as tr-TR locale preferred.

I think these settings only affect HTTP header, but we can't access to these settings via JS.

In the Mozilla documentation it says "The characters within a string are converted to ... while respecting the current locale.

For most languages, this will return the same as ...".

I think it's valid for Turkish, it doesn't differ it's configured as en or tr.

In Turkish it should convert "DINÇ" to "dinç" and "DINÇ" to "dinç" or vice-versa.

The server encountered an internal error or misconfiguration and was unable to complete your request

You should look for the error in the file error_log in the log directory. Maybe there are differences between your local and server configuration (db user/password etc.etc.)

usually the log file is in




What is the use of GO in SQL Server Management Studio & Transact SQL?

Go means, whatever SQL statements are written before it and after any earlier GO, will go to SQL server for processing.

Select * from employees;
GO    -- GO 1

update employees set empID=21 where empCode=123;
GO    -- GO 2

In the above example, statements before GO 1 will go to sql sever in a batch and then any other statements before GO 2 will go to sql server in another batch. So as we see it has separated batches.

In CSS how do you change font size of h1 and h2

What have you tried? This should work.

h1 { font-size: 20pt; }
h2 { font-size: 16pt; }

Tokenizing Error: java.util.regex.PatternSyntaxException, dangling metacharacter '*'

I had similar problem with regex = "?". It happens for all special characters that have some meaning in a regex. So you need to have "\\" as a prefix to your regex.

String [] separado = line.split("\\*");

python JSON object must be str, bytes or bytearray, not 'dict

json.loads take a string as input and returns a dictionary as output.

json.dumps take a dictionary as input and returns a string as output.

With json.loads({"('Hello',)": 6, "('Hi',)": 5}),

You are calling json.loads with a dictionary as input.

You can fix it as follows (though I'm not quite sure what's the point of that):

d1 = {"('Hello',)": 6, "('Hi',)": 5}
s1 = json.dumps(d1)
d2 = json.loads(s1)

Python code to remove HTML tags from a string

Note that this isn't perfect, since if you had something like, say, <a title=">"> it would break. However, it's about the closest you'd get in non-library Python without a really complex function:

import re

TAG_RE = re.compile(r'<[^>]+>')

def remove_tags(text):
    return TAG_RE.sub('', text)

However, as lvc mentions xml.etree is available in the Python Standard Library, so you could probably just adapt it to serve like your existing lxml version:

def remove_tags(text):
    return ''.join(xml.etree.ElementTree.fromstring(text).itertext())

Find duplicate lines in a file and count how many time each line was duplicated?

In windows using "Windows PowerShell" I used the command mentioned below to achieve this

Get-Content .\file.txt | Group-Object | Select Name, Count

Also we can use the where-object Cmdlet to filter the result

Get-Content .\file.txt | Group-Object | Where-Object { $_.Count -gt 1 } | Select Name, Count

Showing which files have changed between two revisions

Note that git makes it easy to just try out the merge and back away from any problems if you don't like the result. It might be easier than looking for potential problems in advance.

Server.Transfer Vs. Response.Redirect

Response.Redirect() should be used when:

  • we want to redirect the request to some plain HTML pages on our server or to some other web server
  • we don't care about causing additional roundtrips to the server on each request
  • we do not need to preserve Query String and Form Variables from the original request
  • we want our users to be able to see the new redirected URL where he is redirected in his browser (and be able to bookmark it if its necessary)

Server.Transfer() should be used when:

  • we want to transfer current page request to another .aspx page on the same server
  • we want to preserve server resources and avoid the unnecessary roundtrips to the server
  • we want to preserve Query String and Form Variables (optionally)
  • we don't need to show the real URL where we redirected the request in the users Web Browser

What does a circled plus mean?

That's the XOR operator, not the PLUS operator

XOR works bit by bit, without carrying over like PLUS does

1 XOR 1 = 0
1 XOR 0 = 1
0 XOR 0 = 0
0 XOR 1 = 1

PHP & MySQL: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given

$dbc is returning false. Your query has an error in it:

SELECT users.*, profile.* --You do not join with profile anywhere.
                                 FROM users 
                                 INNER JOIN contact_info 
                                 ON contact_info.user_id = users.user_id 
                                 WHERE users.user_id=3");

The fix for this in general has been described by Raveren.

how to remove empty strings from list, then remove duplicate values from a list

Amiram's answer is correct, but Distinct() as implemented is an N2 operation; for each item in the list, the algorithm compares it to all the already processed elements, and returns it if it's unique or ignores it if not. We can do better.

A sorted list can be deduped in linear time; if the current element equals the previous element, ignore it, otherwise return it. Sorting is NlogN, so even having to sort the collection, we get some benefit:

public static IEnumerable<T> SortAndDedupe<T>(this IEnumerable<T> input)
   var toDedupe = input.OrderBy(x=>x);

   T prev;
   foreach(var element in toDedupe)
      if(element == prev) continue;

      yield return element;
      prev = element;      

dtList  = dtList.Where(s => !string.IsNullOrWhitespace(s)).SortAndDedupe().ToList();

This returns the same elements; they're just sorted.

Unable to locate an executable at "/usr/bin/java/bin/java" (-1)

i have experienced the same problem, and after reading this post i have double checked the JAVA_HOME definition in .bash_profile. It is actually:

export JAVA_HOME=$(which java)

that, exactly as Anony-Mousse is explaining, is the executable. Changing it to:


fixes the problem, tho is still interesting to understand why it's valued in that way in the profile file.

How to fix: "HAX is not working and emulator runs in emulation mode"

Re-open your AVD device configuration. by editing device in the AVD manager. proceed to select the AVD Android version. At the right pane a recommendation is displayed follow that recommendation and all will be fixed.

Can I access a form in the controller?

This answer is a little late, but I stumbled upon a solution that makes everything a LOT easier.

You can actually assign the form name directly to your controller if you're using the controllerAs syntax and then reference it from your "this" variable. Here's how I did it in my code:

I configured the controller via ui-router (but you can do it however you want, even in the HTML directly with something like <div ng-controller="someController as myCtrl">) This is what it might look like in a ui-router configuration:

views: {
            "": {
                templateUrl: "someTemplate.html",
                controller: "someController",
                controllerAs: "myCtrl"

and then in the HTML, you just set the form name as the "controllerAs"."name" like so:

<ng-form name="myCtrl.someForm">
    <!-- example form code here -->
    <input name="firstName" ng-model="myCtrl.user.firstName" required>

now inside your controller you can very simply do this:

        function ($scope) {
            var vm = this;
              // do something

How to highlight text using javascript

function stylizeHighlightedString() {

    var text = window.getSelection();

    // For diagnostics
    var start = text.anchorOffset;
    var end = text.focusOffset - text.anchorOffset;

    range = window.getSelection().getRangeAt(0);

    var selectionContents = range.extractContents();
    var span = document.createElement("span");

    span.appendChild(selectionContents); = "yellow"; = "black";


Number of days in particular month of particular year?

You can use Calendar.getActualMaximum method:

Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.YEAR, year);
calendar.set(Calendar.MONTH, month-1);
int numDays = calendar.getActualMaximum(Calendar.DATE);

And month-1 is Because of month takes its original number of month while in method takes argument as below in Calendar.class

public int getActualMaximum(int field) {
   throw new RuntimeException("Stub!");

And the (int field) is like as below.

public static final int JANUARY = 0;
public static final int NOVEMBER = 10;
public static final int DECEMBER = 11;

How to change the Jupyter start-up folder

[1]  cd e:

Test it by:

[2] pwd

Matplotlib tight_layout() doesn't take into account figure suptitle

You can adjust the subplot geometry in the very tight_layout call as follows:

fig.tight_layout(rect=[0, 0.03, 1, 0.95])

As it's stated in the documentation (

tight_layout() only considers ticklabels, axis labels, and titles. Thus, other artists may be clipped and also may overlap.

copying all contents of folder to another folder using batch file?

Here's a solution with robocopy which copies the content of Folder1 into Folder2 going trough all subdirectories and automatically overwriting the files with the same name:

robocopy C:\Folder1 C:\Folder2 /COPYALL /E /IS /IT


/COPYALL copies all file information
/E copies subdirectories including empty directories
/IS includes the same files
/IT includes modified files with the same name

For more parameters see the official documentation:

Note: it can be necessary to run the command as administrator, because of the argument /COPYALL. If you can't: just get rid of it.

get current url in twig template?

{{ path(app.request.attributes.get('_route'),
     app.request.attributes.get('_route_params')) }}

If you want to read it into a view variable:

{% set currentPath = path(app.request.attributes.get('_route'),
                       app.request.attributes.get('_route_params')) %}

The app global view variable contains all sorts of useful shortcuts, such as app.session and, that reference the services you might use in a controller.

Python way to clone a git repository

Github's libgit2 binding, pygit2 provides a one-liner cloning a remote directory:

clone_repository(url, path, 
    bare=False, repository=None, remote=None, checkout_branch=None, callbacks=None)

Split files using tar, gz, zip, or bzip2

You can use the split command with the -b option:

split -b 1024m file.tar.gz

It can be reassembled on a Windows machine using @Joshua's answer.

copy /b file1 + file2 + file3 + file4 filetogether

Edit: As @Charlie stated in the comment below, you might want to set a prefix explicitly because it will use x otherwise, which can be confusing.

split -b 1024m "file.tar.gz" "file.tar.gz.part-"

// Creates files: file.tar.gz.part-aa, file.tar.gz.part-ab, file.tar.gz.part-ac, ...

Edit: Editing the post because question is closed and the most effective solution is very close to the content of this answer:

# create archives
$ tar cz my_large_file_1 my_large_file_2 | split -b 1024MiB - myfiles_split.tgz_
# uncompress
$ cat myfiles_split.tgz_* | tar xz

This solution avoids the need to use an intermediate large file when (de)compressing. Use the tar -C option to use a different directory for the resulting files. btw if the archive consists from only a single file, tar could be avoided and only gzip used:

# create archives
$ gzip -c my_large_file | split -b 1024MiB - myfile_split.gz_
# uncompress
$ cat myfile_split.gz_* | gunzip -c > my_large_file

For windows you can download ported versions of the same commands or use cygwin.

Char array declaration and initialization in C

I think these are two really different cases. In the first case memory is allocated and initialized in compile-time. In the second - in runtime.

Creating a list of dictionaries results in a list of copies of the same dictionary

If you want one line:

list_of_dict = [{} for i in range(list_len)]

Zoom in on a point (using scale and translate)

Here's an alternate way to do it that uses setTransform() instead of scale() and translate(). Everything is stored in the same object. The canvas is assumed to be at 0,0 on the page, otherwise you'll need to subtract its position from the page coords.

this.zoomIn = function (pageX, pageY) {
    var zoomFactor = 1.1;
    this.scale = this.scale * zoomFactor;
    this.lastTranslation = {
        x: pageX - (pageX - this.lastTranslation.x) * zoomFactor,
        y: pageY - (pageY - this.lastTranslation.y) * zoomFactor
    this.canvasContext.setTransform(this.scale, 0, 0, this.scale,
this.zoomOut = function (pageX, pageY) {
    var zoomFactor = 1.1;
    this.scale = this.scale / zoomFactor;
    this.lastTranslation = {
        x: pageX - (pageX - this.lastTranslation.x) / zoomFactor,
        y: pageY - (pageY - this.lastTranslation.y) / zoomFactor
    this.canvasContext.setTransform(this.scale, 0, 0, this.scale,

Accompanying code to handle panning:

this.startPan = function (pageX, pageY) {
    this.startTranslation = {
        x: pageX - this.lastTranslation.x,
        y: pageY - this.lastTranslation.y
this.continuePan = function (pageX, pageY) {
    var newTranslation = {x: pageX - this.startTranslation.x,
                          y: pageY - this.startTranslation.y};
    this.canvasContext.setTransform(this.scale, 0, 0, this.scale,
                                    newTranslation.x, newTranslation.y);
this.endPan = function (pageX, pageY) {
    this.lastTranslation = {
        x: pageX - this.startTranslation.x,
        y: pageY - this.startTranslation.y

To derive the answer yourself, consider that the same page coordinates need to match the same canvas coordinates before and after the zoom. Then you can do some algebra starting from this equation:

(pageCoords - translation) / scale = canvasCoords

How to display HTML <FORM> as inline element?

According to HTML spec both <form> and <p> are block elements and you cannot nest them. Maybe replacing the <p> with <span> would work for you?

EDIT: Sorry. I was to quick in my wording. The <p> element doesn't allow any block content within - as specified by HTML spec for paragraphs.

How to find the statistical mode?

This builds on jprockbelly's answer, by adding a speed up for very short vectors. This is useful when applying mode to a data.frame or datatable with lots of small groups:

Mode <- function(x) {
   if ( length(x) <= 2 ) return(x[1])
   if ( anyNA(x) ) x = x[!]
   ux <- unique(x)
   ux[which.max(tabulate(match(x, ux)))]

Select Multiple Fields from List in Linq

var result = listObject.Select( i => new{ i.category_name, i.category_id } )

This uses anonymous types so you must the var keyword, since the resulting type of the expression is not known in advance.

How to get the jQuery $.ajax error response text?

This is what worked for me

    function showErrorMessage(xhr, status, error) {
        if (xhr.responseText != "") {

            var jsonResponseText = $.parseJSON(xhr.responseText);
            var jsonResponseStatus = '';
            var message = '';
            $.each(jsonResponseText, function(name, val) {
                if (name == "ResponseStatus") {
                    jsonResponseStatus = $.parseJSON(JSON.stringify(val));
                     $.each(jsonResponseStatus, function(name2, val2) {
                         if (name2 == "Message") {
                             message = val2;


Hidden features of Python

Builtin methods or functions don't implement the descriptor protocol which makes it impossible to do stuff like this:

>>> class C(object):
...  id = id
>>> C().id()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: id() takes exactly one argument (0 given)

However you can create a small bind descriptor that makes this possible:

>>> from types import MethodType
>>> class bind(object):
...  def __init__(self, callable):
...   self.callable = callable
...  def __get__(self, obj, type=None):
...   if obj is None:
...    return self
...   return MethodType(self.callable, obj, type)
>>> class C(object):
...  id = bind(id)
>>> C().id()

Conditional Logic on Pandas DataFrame

Just compare the column with that value:

In [9]: df = pandas.DataFrame([1,2,3,4], columns=["data"])

In [10]: df
0     1
1     2
2     3
3     4

In [11]: df["desired"] = df["data"] > 2.5
In [11]: df
   data desired
0     1   False
1     2   False
2     3    True
3     4    True

Why is visible="false" not working for a plain html table?

For a similar post a long time ago there seems to be issues with making table visibility hidden.

You have two options, one is to use the display:none attribute.

Or two wrap the table in a div and make the div hidden.

<div id="wrapper" style="visibility:hidden">

Response::json() - Laravel 5.1

use the helper function in laravel 5.1 instead:

return response()->json(['name' => 'Abigail', 'state' => 'CA']);

This will create an instance of \Illuminate\Routing\ResponseFactory. See the phpDocs for possible parameters below:

* Return a new JSON response from the application.
* @param string|array $data
* @param int $status
* @param array $headers
* @param int $options
* @return \Symfony\Component\HttpFoundation\Response 
* @static 
public static function json($data = array(), $status = 200, $headers = array(), $options = 0){

    return \Illuminate\Routing\ResponseFactory::json($data, $status, $headers, $options);

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

I got same problem... and I did it.

My code before:

<link rel="stylesheet" href="../css/style.default.css" type="text/css" />

And the problem solved after I changed my code into this:

<link rel="stylesheet" href="css/style.default.css" type="text/css" />

So I think "href=../" is not allowed, because I don't have problem when I use "../" in "src=../"

javascript, for loop defines a dynamic variable name

You cannot create different "variable names" but you can create different object properties. There are many ways to do whatever it is you're actually trying to accomplish. In your case I would just do

for (var i = myArray.length - 1; i >= 0; i--) {    console.log(eval(myArray[i])); }; 

More generally you can create object properties dynamically, which is the type of flexibility you're thinking of.

var result = {}; for (var i = myArray.length - 1; i >= 0; i--) {     result[myArray[i]] = eval(myArray[i]);   }; 

I'm being a little handwavey since I don't actually understand language theory, but in pure Javascript (including Node) references (i.e. variable names) are happening at a higher level than at runtime. More like at the call stack; you certainly can't manufacture them in your code like you produce objects or arrays. Browsers do actually let you do this anyway though it's terrible practice, via

window['myVarName'] = 'namingCollisionsAreFun';  

(per comment)

How an 'if (A && B)' statement is evaluated?

Yes, it is called Short-circuit Evaluation.

If the validity of the boolean statement can be assured after part of the statement, the rest is not evaluated.

This is very important when some of the statements have side-effects.

php foreach with multidimensional array

Wouldn't a normal foreach basically yield the same result as a mysql_fetch_assoc in your case?

when using foreach on that array, you would get an array containing those three keys: 'id','firstname' and 'lastname'.

That should be the same as mysql_fetch_assoc would give (in a loop) for each row.

#define in Java

Java doesn't have a general purpose define preprocessor directive.

In the case of constants, it is recommended to declare them as static finals, like in

private static final int PROTEINS = 100;

Such declarations would be inlined by the compilers (if the value is a compile-time constant).

Please note also that public static final constant fields are part of the public interface and their values shouldn't change (as the compiler inlines them). If you do change the value, you would need to recompile all the sources that referenced that constant field.

What is the difference between require() and library()?

Another benefit of require() is that it returns a logical value by default. TRUE if the packages is loaded, FALSE if it isn't.

> test <- library("abc")
Error in library("abc") : there is no package called 'abc'
> test
Error: object 'test' not found
> test <- require("abc")
Loading required package: abc
Warning message:
In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE,  :
  there is no package called 'abc'
> test

So you can use require() in constructions like the one below. Which mainly handy if you want to distribute your code to our R installation were packages might not be installed.

    print("lme4 is loaded correctly")
} else {
    print("trying to install lme4")
        print("lme4 installed and loaded")
    } else {
        stop("could not install lme4")

Convert utf8-characters to iso-88591 and back in PHP

You need to use the iconv package, specifically its iconv function.

In R, how to find the standard error of the mean?

Remembering that the mean can also by obtained using a linear model, regressing the variable against a single intercept, you can use also the lm(x~1) function for this!

Advantages are:

  • You obtain immediately confidence intervals with confint()
  • You can use tests for various hypothesis about the mean, using for example car::linear.hypothesis()
  • You can use more sophisticated estimates of the standard deviation, in case you have some heteroskedasticity, clustered-data, spatial-data etc, see package sandwich
## generate data
x <- rnorm(1000)

## estimate reg
reg <- lm(x~1)
coef(summary(reg))[,"Std. Error"]
#> [1] 0.03237811

## conpare with simple formula
          coef(summary(reg))[,"Std. Error"])
#> [1] TRUE

## extract confidence interval
#>                   2.5 %    97.5 %
#> (Intercept) -0.06457031 0.0625035

Created on 2020-10-06 by the reprex package (v0.3.0)

Keep-alive header clarification

Where is this info kept ("this connection is between computer A and server F")?

A TCP connection is recognized by source IP and port and destination IP and port. Your OS, all intermediate session-aware devices and the server's OS will recognize the connection by this.

HTTP works with request-response: client connects to server, performs a request and gets a response. Without keep-alive, the connection to an HTTP server is closed after each response. With HTTP keep-alive you keep the underlying TCP connection open until certain criteria are met.

This allows for multiple request-response pairs over a single TCP connection, eliminating some of TCP's relatively slow connection startup.

When The IIS (F) sends keep alive header (or user sends keep-alive) , does it mean that (E,C,B) save a connection

No. Routers don't need to remember sessions. In fact, multiple TCP packets belonging to same TCP session need not all go through same routers - that is for TCP to manage. Routers just choose the best IP path and forward packets. Keep-alive is only for client, server and any other intermediate session-aware devices.

which is only for my session ?

Does it mean that no one else can use that connection

That is the intention of TCP connections: it is an end-to-end connection intended for only those two parties.

If so - does it mean that keep alive-header - reduce the number of overlapped connection users ?

Define "overlapped connections". See HTTP persistent connection for some advantages and disadvantages, such as:

  • Lower CPU and memory usage (because fewer connections are open simultaneously).
  • Enables HTTP pipelining of requests and responses.
  • Reduced network congestion (fewer TCP connections).
  • Reduced latency in subsequent requests (no handshaking).

if so , for how long does the connection is saved to me ? (in other words , if I set keep alive- "keep" till when?)

An typical keep-alive response looks like this:

Keep-Alive: timeout=15, max=100

See Hypertext Transfer Protocol (HTTP) Keep-Alive Header for example (a draft for HTTP/2 where the keep-alive header is explained in greater detail than both 2616 and 2086):

  • A host sets the value of the timeout parameter to the time that the host will allows an idle connection to remain open before it is closed. A connection is idle if no data is sent or received by a host.

  • The max parameter indicates the maximum number of requests that a client will make, or that a server will allow to be made on the persistent connection. Once the specified number of requests and responses have been sent, the host that included the parameter could close the connection.

However, the server is free to close the connection after an arbitrary time or number of requests (just as long as it returns the response to the current request). How this is implemented depends on your HTTP server.

Change the mouse cursor on mouse over to anchor-like style

Assuming your div has an id="myDiv", add the following to your CSS. The cursor: pointer specifies that the cursor should be the same hand icon that is use for anchors (hyperlinks):

CSS to Add

    cursor: pointer;

You can simply add the cursor style to your div's HTML like this:

<div style="cursor: pointer">



If you are determined to use jQuery for this, then add the following line to your $(document).ready() or body onload: (replace myClass with whatever class all of your divs share)

$('.myClass').css('cursor', 'pointer');

How can I check the system version of Android?

Build.Version is the place go to for this data. Here is a code snippet for how to format it.

public String getAndroidVersion() {
    String release = Build.VERSION.RELEASE;
    int sdkVersion = Build.VERSION.SDK_INT;
    return "Android SDK: " + sdkVersion + " (" + release +")";

Looks like this "Android SDK: 19 (4.4.4)"

How to automatically select all text on focus in WPF TextBox?

I have tested all of them but only the following worked out:

protected override void OnStartup(StartupEventArgs e) 
    EventManager.RegisterClassHandler(typeof(TextBox), UIElement.PreviewMouseLeftButtonDownEvent,
   new MouseButtonEventHandler(SelectivelyHandleMouseButton), true);
    EventManager.RegisterClassHandler(typeof(TextBox), UIElement.GotKeyboardFocusEvent,
      new RoutedEventHandler(SelectAllText), true);
    EventManager.RegisterClassHandler(typeof(TextBox), UIElement.GotFocusEvent,
      new RoutedEventHandler(GotFocus), true);          

private static void SelectivelyHandleMouseButton(object sender, MouseButtonEventArgs e)
    var textbox = (sender as TextBox);
    if (textbox != null)
        int hc = textbox.GetHashCode();
        if (hc == LastHashCode)
            if (e.OriginalSource.GetType().Name == "TextBoxView")
                e.Handled = true;
                LastHashCode = -1;
    if (textbox != null) textbox.Focus();

private static void SelectAllText(object sender, RoutedEventArgs e)
    var textBox = e.OriginalSource as TextBox;
    if (textBox != null)

private static int LastHashCode;
private static void GotFocus(object sender, RoutedEventArgs e)
    var textBox = e.OriginalSource as TextBox;
    if (textBox != null)
        LastHashCode = textBox.GetHashCode();

Django CSRF check failing with an Ajax POST request

for someone who comes across this and is trying to debug:

1) the django csrf check (assuming you're sending one) is here

2) In my case, settings.CSRF_HEADER_NAME was set to 'HTTP_X_CSRFTOKEN' and my AJAX call was sending a header named 'HTTP_X_CSRF_TOKEN' so stuff wasn't working. I could either change it in the AJAX call, or django setting.

3) If you opt to change it server-side, find your install location of django and throw a breakpoint in the csrf middleware.f you're using virtualenv, it'll be something like: ~/.envs/my-project/lib/python2.7/site-packages/django/middleware/

import ipdb; ipdb.set_trace() # breakpoint!!
if request_csrf_token == "":
    # Fall back to X-CSRFToken, to make things easier for AJAX,
    # and possible for PUT/DELETE.
    request_csrf_token = request.META.get(settings.CSRF_HEADER_NAME, '')

Then, make sure the csrf token is correctly sourced from request.META

4) If you need to change your header, etc - change that variable in your settings file

Fatal error: Call to a member function query() on null

First, you declared $db outside the function. If you want to use it inside the function, you should put this at the begining of your function code:

global $db;

And I guess, when you wrote:

        return (mysqli_result($query, 0) == 1) ? true : false;

what you really wanted was:

if ($result->num_rows==1) { return true; } else { return false; }

swift How to remove optional String Character

Hello i have got the same issue i was getting Optional(3) So, i have tried this below code

cell.lbl_Quantity.text = "(data?.quantity!)" //"Optional(3)"

let quantity = data?.quantity

cell.lbl_Quantity.text = "(quantity!)" //"3"

Output ("echo") a variable to a text file

After some trial and error, I found that

$computername = $env:computername

works to get a computer name, but sending $computername to a file via Add-Content doesn't work.

I also tried $computername.Value.

Instead, if I use

$computername = get-content env:computername

I can send it to a text file using

$computername | Out-File $file

PDF to image using Java

If GPL is fine you may have an additional look at jPodRenderer (SourceForge)

Setting Remote Webdriver to run tests in a remote computer using Java

  • First you need to create HubNode(Server) and start the HubNode(Server) from command Line/prompt using Java: -jar selenium-server-standalone-2.44.0.jar -role hub
  • Then bind the node/Client to this Hub using Hub machines IPAddress or Name with any port number >1024. For Node Machine for example: Java -jar selenium-server-standalone-2.44.0.jar -role webdriver -hub http://HubmachineIPAddress:4444/grid/register -port 5566

One more thing is that whenever we use Internet Explore or Google Chrome we need to set: System.setProperty("",path);

How to use BufferedReader in Java

As far as i understand fr is the object of your FileReadExample class. So it is obvious it will not have any method like fr.readLine() if you dont create one yourself.

secondly, i think a correct constructor of the BufferedReader class will help you do your task.

String str;
BufferedReader buffread = new BufferedReader(new FileReader(new File("file.dat")));
str = buffread.readLine();

this should help you.

checked = "checked" vs checked = true

document.getElementById('myRadio') returns you the DOM element, i'll reference it as elem in this answer.

elem.checked accesses the property named checked of the DOM element. This property is always a boolean.

When writing HTML you use checked="checked" in XHTML; in HTML you can simply use checked. When setting the attribute (this is done via .setAttribute('checked', 'checked')) you need to provide a value since some browsers consider an empty value being non-existent.

However, since you have the DOM element you have no reason to set the attribute since you can simply use the - much more comfortable - boolean property for it. Since non-empty strings are considered true in a boolean context, setting elem.checked to 'checked' or anything else that is not a falsy value (even 'false' or '0') will check the checkbox. There is not reason not to use true and false though so you should stick with the proper values.

Adding a newline character within a cell (CSV)

On Excel for Mac 2011, the newline had to be a \r instead of an \n


"\"first line\rsecond line\""

would show up as a cell with 2 lines

What is the best way to redirect a page using React Router?

You also can Redirect within the Route as follows. This is for handle invalid routes.

<Route path='*' render={() => 
       <Redirect to="/error"/>

Local variable referenced before assignment?

Put a global statement at the top of your function and you should be good:

def onLoadFinished(result):
    global feed

To demonstrate what I mean, look at this little test:

x = 0
def t():
    x += 1

this blows up with your exact same error where as:

x = 0
def t():
    global x
    x += 1

does not.

The reason for this is that, inside t, Python thinks that x is a local variable. Furthermore, unless you explicitly tell it that x is global, it will try to use a local variable named x in x += 1. But, since there is no x defined in the local scope of t, it throws an error.

counting the number of lines in a text file

with for-loop:

std::ifstream myFile;
std::string line;
int lines;;

for(lines = 0; std::getline(myFile,line); lines++);

std::cout << lines << std::endl;

Bootstrap 3 Horizontal Divider (not in a dropdown)

As I found the default Bootstrap <hr/> size unsightly, here's some simple HTML and CSS to balance out the element visually:


<hr class="half-rule"/>


.half-rule { 
    margin-left: 0;
    text-align: left;
    width: 50%;

Leave only two decimal places after the dot

Alternatively, you may also use the composite operator F then indicating how many decimal spots you wish to appear after the decimal.

string.Format("{0:F2}", 123.456789);     //123.46
string.Format("{0:F3}", 123.456789);     //123.457
string.Format("{0:F4}", 123.456789);     //123.4568

It will round up so be aware of that.

I sourced the general documentation. There are a ton of other formatting operators there as well that you may check out.


How to make a Java Generic method static?

the only thing you can do is to change your signature to

public static <E> E[] appendToArray(E[] array, E item)

Important details:

Generic expressions preceding the return value always introduce (declare) a new generic type variable.

Additionally, type variables between types (ArrayUtils) and static methods (appendToArray) never interfere with each other.

So, what does this mean: In my answer <E> would hide the E from ArrayUtils<E> if the method wouldn't be static. AND <E> has nothing to do with the E from ArrayUtils<E>.

To reflect this fact better, a more correct answer would be:

public static <I> I[] appendToArray(I[] array, I item)

Function that creates a timestamp in c#

You can also use


How to install JRE 1.7 on Mac OS X and use it with Eclipse?

The download from which installs in /Library/Internet Plug-Ins is only the JRE, for development you probably want to download the JDK from and install that instead. This will install the JDK at /Library/Java/JavaVirtualMachines/jdk1.7.0_<something>.jdk/Contents/Home which you can then add to Eclipse via Preferences -> Java -> Installed JREs.

Ranges of floating point datatype in C?

A 32 bit floating point number has 23 + 1 bits of mantissa and an 8 bit exponent (-126 to 127 is used though) so the largest number you can represent is:

(1 + 1 / 2 + ... 1 / (2 ^ 23)) * (2 ^ 127) = 
(2 ^ 23 + 2 ^ 23 + .... 1) * (2 ^ (127 - 23)) = 
(2 ^ 24 - 1) * (2 ^ 104) ~= 3.4e38

Exception: Serialization of 'Closure' is not allowed

As already stated: closures, out of the box, cannot be serialized.

However, using the __sleep(), __wakeup() magic methods and reflection u CAN manually make closures serializable. For more details see extending-php-5-3-closures-with-serialization-and-reflection

This makes use of reflection and the php function eval. Do note this opens up the possibility of CODE injection, so please take notice of WHAT you are serializing.

How do I use hexadecimal color strings in Flutter?

Unfortunately, the Color class constructor in Flutter does not accept a simple hexadecimal string (like #bfeb91 in CSS).

Instead, it requires an integer like 0xFFBFEB91.

So here is we convert a hex string to an integer

A simple function

Give this function a hex string and it will return you a Color!

Color _getColorFromHex(String hexColor) {
  hexColor = hexColor.replaceAll("#", "");
  if (hexColor.length == 6) {
    hexColor = "FF" + hexColor;
  if (hexColor.length == 8) {
    return Color(int.parse("0x$hexColor"));

Use it like this

  'Hello World',
  style: TextStyle(backgroundColor: _getColorFromHex('ff00aa')), // or 'bfeb91', or 'ffbfeb91'

As a String extension

Leveraging the power of Dart extensions we can augment String with a function that returns a Color:

extension ColorExtension on String {
  toColor() {
    var hexColor = this.replaceAll("#", "");
    if (hexColor.length == 6) {
      hexColor = "FF" + hexColor;
    if (hexColor.length == 8) {
      return Color(int.parse("0x$hexColor"));

Use it like this

  'Hello World',
  style: TextStyle(backgroundColor: '#bfeb91'.toColor()), // or 'bfeb91', or 'ffbfeb91'

read complete file without using loop in java

If the file is small, you can read the whole data once:

File file = new File("a.txt");
FileInputStream fis = new FileInputStream(file);
byte[] data = new byte[(int) file.length()];;

String str = new String(data, "UTF-8");

What is HTTP "Host" header?

I would always recommend going to the authoritative source when trying to understand the meaning and purpose of HTTP headers.

The "Host" header field in a request provides the host and port
information from the target URI, enabling the origin server to
distinguish among resources while servicing requests for multiple
host names on a single IP address.

Appending the same string to a list of strings in Python

my_list = ['foo', 'fob', 'faz', 'funk']
string = 'bar'
my_new_list = [x + string for x in my_list]
print my_new_list

This will print:

['foobar', 'fobbar', 'fazbar', 'funkbar']