Programs & Examples On #Rgba

RGBA stands for Red-Green-Blue-Alpha and specifies a color using four values which represent the amount of red, green, blue and alpha in the color.

Convert RGBA PNG to RGB with PIL

By using Image.alpha_composite, the solution by Yuji 'Tomita' Tomita become simpler. This code can avoid a tuple index out of range error if png has no alpha channel.

from PIL import Image

png ='RGBA')
background ='RGBA', png.size, (255,255,255))

alpha_composite = Image.alpha_composite(background, png)'foo.jpg', 'JPEG', quality=80)

Overlay a background-image with an rgba background-color

Yes, there is a way to do this. You could use a pseudo-element after to position a block on top of your background image. Something like this:

The css for the :after looks like this:

#the-div:hover:after {
    content: ' ';
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    background-color: rgba(0,0,0,.5);

When you want to apply this to a non-empty element, and just get the overlay on the background, you can do so by applying a positive z-index to the element, and a negative one to the :after. Something like this:

#the-div {
    z-index: 1;
#the-div:hover:after {
    z-index: -1;

And the updated fiddle:

CSS hexadecimal RGBA?

See here

It is not possible, most probably because 0xFFFFFFFF is greater than the maximum value for 32bit integers

Sass - Converting Hex to RGBa for background opacity

If you need to mix colour from variable and alpha transparency, and with solutions that include rgba() function you get an error like

      background-color: rgba(#{$color}, 0.3);
      $color: #002366 is not a color.
   ¦       background-color: rgba(#{$color}, 0.3);
   ¦                         ^^^^^^^^^^^^^^^^^^^^

Something like this might be useful.

$meeting-room-colors: (
  Neumann: '#002366',
  Turing: '#FF0000',
  Lovelace: '#00BFFF',
  Shared: '#00FF00',
  Chilling: '#FF1493',
$color-alpha: EE;

@each $name, $color in $meeting-room-colors {

  .#{$name} {

     background-color: #{$color}#{$color-alpha};



CSS background opacity with rgba not working in IE 8

The best solution I found so far is the one proposed by David J Marland in his blog, to support opacity in old browsers (IE 6+):

    background:rgb(255,0,0); /* Fallback for web browsers that don't support RGBa nor filter */ 
    background: transparent\9; /* backslash 9 hack to prevent IE 8 from falling into the fallback */
    background:rgba(255,0,0,0.3); /* RGBa declaration for browsers that support it */
    filter:progid:DXImageTransform.Microsoft.gradient(startColorstr=#4cFF0000,endColorstr=#4cFF0000); /* needed for IE 6-8 */
    zoom: 1; /* needed for IE 6-8 */

 * CSS3 selector (not supported by IE 6 to IE 8),
 * to avoid IE more recent versions to apply opacity twice
 * (once with rgba and once with filter)
.alpha30:nth-child(n) {
    filter: none;

Getting value from appsettings.json in .net core

I guess the simplest way is by DI. An example of reaching into Controller.

// StartUp.cs
public void ConfigureServices(IServiceCollection services)
    // for get appsettings from anywhere

public class ContactUsController : Controller
    readonly IConfiguration _configuration;

    public ContactUsController(
        IConfiguration configuration)
        _configuration = configuration;

        // sample:
        var apiKey = _configuration.GetValue<string>("SendGrid:CAAO");

What is the Difference Between read() and recv() , and Between send() and write()?

read() and write() are more generic, they work with any file descriptor. However, they won't work on Windows.

You can pass additional options to send() and recv(), so you may have to used them in some cases.

Can I target all <H> tags with a single selector?

Stylus's selector interpolation

for n in 1..6
    font: 32px/42px trajan-pro-1,trajan-pro-2;

Best C/C++ Network Library

Aggregated List of Libraries

How to compute the similarity between two text documents?

Identical to @larsman, but with some preprocessing

import nltk, string
from sklearn.feature_extraction.text import TfidfVectorizer'punkt') # if necessary...

stemmer = nltk.stem.porter.PorterStemmer()
remove_punctuation_map = dict((ord(char), None) for char in string.punctuation)

def stem_tokens(tokens):
    return [stemmer.stem(item) for item in tokens]

'''remove punctuation, lowercase, stem'''
def normalize(text):
    return stem_tokens(nltk.word_tokenize(text.lower().translate(remove_punctuation_map)))

vectorizer = TfidfVectorizer(tokenizer=normalize, stop_words='english')

def cosine_sim(text1, text2):
    tfidf = vectorizer.fit_transform([text1, text2])
    return ((tfidf * tfidf.T).A)[0,1]

print cosine_sim('a little bird', 'a little bird')
print cosine_sim('a little bird', 'a little bird chirps')
print cosine_sim('a little bird', 'a big dog barks')

Select elements by attribute



more info: official docs

Xcode 10, Command CodeSign failed with a nonzero exit code

I will post my solution. This solution worked for me, since none of the previous worked. The issue first occurred right after last update of XCode cli toolset (not sure if this is the confirmation bias).

I tried some of the instructions (ie. Unlock Keychain Trick).

What worked for me in a case of error:

  • Command CodeSign failed with a nonzero exit code (Something.framework)

    • Trash DD Content; rm -rf /Users/dx/Library/Developer/Xcode/DerivedData/*
    • Restart XCode
    • Build Phases => Link Binary With Libraries
      • Something.framework,
    • Set embed value in General => Something.framework => EMBED
      • Do not embed
    • Press Cmd+B (Build Project)
    • Hopefully Built Successful

"make_sock: could not bind to address [::]:443" when restarting apache (installing trac and mod_wsgi)

I seconded Matthieu answer

I commented #Listen 443 in httpd-ssl file and apache can be started

Because the file already has VirtualHost default:443

Android: How to add R.raw to project?

Adding a raw folder to your resource folder (/res/) should do the trick.

Read more here:

Web link to specific whatsapp contact

The following link seems to work fine -

<a href="whatsapp://send?text=Hello World!&phone=+9198********1">Ping me on WhatsApp</a>

It opens the contact in WhatsApp app, along with the message 'Hello World!' prepopulated in the input text box.

(Tested this with google chrome on an android phone.)

Plot inline or a separate window using Matplotlib in Spyder IDE


%matplotlib qt

when you want graphs in a separate window and

%matplotlib inline

when you want an inline plot

Resize an Array while keeping current elements in Java?

Sorry, but at this time is not possible resize arrays, and may be never will be.

So my recommendation, is to think more to find a solution that allow you get from the beginning of the process, the size of the arrays that you will requiere. This often will implicate that your code need a little more time (lines) to run, but you will save a lot of memory resources.

hidden field in php

You absolutely can, I use this approach a lot w/ both JavaScript and PHP.

Field definition:

<input type="hidden" name="foo" value="<?php echo $var;?>" />

Access w/ PHP:

$_GET['foo'] or $_POST['foo']

Also: Don't forget to sanitize your inputs if they are going into a database. Feel free to use my routine:


SQL ORDER BY date problem

It seems that your date column is not of type datetime but varchar. You have to convert it to datetime when sorting:

select date
from tbemp
order by convert(datetime, date, 103) ASC

style 103 = dd/MM/yyyy (msdn)

Why do we need virtual functions in C++?

Here is how I understood not just what virtual functions are, but why they're required:

Let's say you have these two classes:

class Animal
        void eat() { std::cout << "I'm eating generic food."; }

class Cat : public Animal
        void eat() { std::cout << "I'm eating a rat."; }

In your main function:

Animal *animal = new Animal;
Cat *cat = new Cat;

animal->eat(); // Outputs: "I'm eating generic food."
cat->eat();    // Outputs: "I'm eating a rat."

So far so good, right? Animals eat generic food, cats eat rats, all without virtual.

Let's change it a little now so that eat() is called via an intermediate function (a trivial function just for this example):

// This can go at the top of the main.cpp file
void func(Animal *xyz) { xyz->eat(); }

Now our main function is:

Animal *animal = new Animal;
Cat *cat = new Cat;

func(animal); // Outputs: "I'm eating generic food."
func(cat);    // Outputs: "I'm eating generic food."

Uh oh... we passed a Cat into func(), but it won't eat rats. Should you overload func() so it takes a Cat*? If you have to derive more animals from Animal they would all need their own func().

The solution is to make eat() from the Animal class a virtual function:

class Animal
        virtual void eat() { std::cout << "I'm eating generic food."; }

class Cat : public Animal
        void eat() { std::cout << "I'm eating a rat."; }


func(animal); // Outputs: "I'm eating generic food."
func(cat);    // Outputs: "I'm eating a rat."


ngrok command not found

For Linux :

For Mac :

For Windows:

unzip it for linux and mac users move file to /usr/local/bin and execute ngrok http 80 command in the terminal

I don't have any idea about windows

Swift Modal View Controller with transparent background

You can do it like this:

In your main view controller:

func showModal() {
    let modalViewController = ModalViewController()
    modalViewController.modalPresentationStyle = .overCurrentContext
    presentViewController(modalViewController, animated: true, completion: nil)

In your modal view controller:

class ModalViewController: UIViewController {
    override func viewDidLoad() {
        view.backgroundColor = UIColor.clearColor()
        view.opaque = false

If you are working with a storyboard:

Just add a Storyboard Segue with Kind set to Present Modally to your modal view controller and on this view controller set the following values:

  • Background = Clear Color
  • Drawing = Uncheck the Opaque checkbox
  • Presentation = Over Current Context

As Crashalot pointed out in his comment: Make sure the segue only uses Default for both Presentation and Transition. Using Current Context for Presentation makes the modal turn black instead of remaining transparent.

How can I create a correlation matrix in R?

Have a look at qtlcharts. It allows you to create interactive correlation matrices:

iris$Species <- NULL
iplotCorr(iris, reorder=TRUE)

enter image description here

It's more impressive when you correlate more variables, like in the package's vignette: enter image description here

jQuery removeClass wildcard

I had the same issue and came up with the following that uses underscore's _.filter method. Once I discovered that removeClass takes a function and provides you with a list of classnames, it was easy to turn that into an array and filter out the classname to return back to the removeClass method.

// Wildcard removeClass on 'color-*'
$('[class^="color-"]').removeClass (function (index, classes) {
    classesArray = classes.split(' '),
    removeClass = _.filter(classesArray, function(className){ return className.indexOf('color-') === 0; }).toString();

  return removeClass;

Codeigniter $this->input->post() empty while $_POST is working correctly

Upgrading from 2.2.x to 3.0.x -- reason post method fails. If you are upgrading CI 3.x, need to keep the index_page in config file. Also check the .htaccess file for mod_rewrite. CI_3.x

$config['index_page'] = ''; // ci 2.x
$config['index_page'] = 'index.php'; // ci 3.x

My .htaccess

<IfModule mod_rewrite.c>
 RewriteEngine On
 RewriteBase /
 RewriteCond %{REQUEST_FILENAME} !-f
 RewriteCond %{REQUEST_FILENAME} !-d
 RewriteRule . /index.php [L]

<IfModule !mod_rewrite.c>
 ErrorDocument 404 /index.php

Get a json via Http Request in NodeJS

Just setting json option to true, the body will contain the parsed json:

  url: 'http://...',
  json: true
}, function(error, response, body) {

JSON serialization/deserialization in ASP.Net Core

You can use Newtonsoft.Json, it's a dependency of Microsoft.AspNet.Mvc.ModelBinding which is a dependency of Microsoft.AspNet.Mvc. So, you don't need to add a dependency in your project.json.

#using Newtonsoft.Json

Note, using a WebAPI controller you don't need to deal with JSON.

UPDATE ASP.Net Core 3.0

Json.NET has been removed from the ASP.NET Core 3.0 shared framework.

You can use the new JSON serializer layers on top of the high-performance Utf8JsonReader and Utf8JsonWriter. It deserializes objects from JSON and serializes objects to JSON. Memory allocations are kept minimal and includes support for reading and writing JSON with Stream asynchronously.

To get started, use the JsonSerializer class in the System.Text.Json.Serialization namespace. See the documentation for information and samples.

To use Json.NET in an ASP.NET Core 3.0 project:


Read Json.NET support in Migrate from ASP.NET Core 2.2 to 3.0 Preview 2 for more information.

How to get Last record from Sqlite?

Another option is to use SQLites LAST_VALUE() function in the following way.

Given this table:

|        |         |       |
| 1      |  ON     |  100  |
|        |         |       |
| 1      |  OFF    |  102  |
|        |         |       |
| 1      |  ON     |  103  |
|        |         |       |
| 2      |  ON     |  101  |
|        |         |       |
| 2      |  OFF    |  102  |
|        |         |       |
| 2      |  ON     |  103  |
|        |         |       |
| 3      |  OFF    |  102  |
|        |         |       |
| 3      |  ON     |  103  |

You can get the last status of every object with the following query

    DISTINCT OBJECT,             -- Only unique rows
    LAST_VALUE(STATUS) OVER (    -- The last value of the status column
        PARTITION BY OBJECT      -- Taking into account rows with the same value in the object column
        ORDER by time asc        -- "Last" when sorting the rows of every object by the time column in ascending order
    ) as lastStatus

The result would look like:

|        |              |
| 1      |  ON          |
|        |              |
| 2      |  ON          |
|        |              |
| 3      |  ON          |

HTML tag <a> want to add both href and onclick working

To achieve this use following html:

<a href="" onclick="make(event)">Item</a>

    function make(e) {
        // ...  your function code
        // e.preventDefault();   // use this to NOT go to href site

Here is working example.

How do I embed a mp4 movie into my html?

If you have an mp4 video residing at your server, and you want the visitors to stream that over your HTML page.

<video width="480" height="320" controls="controls">
<source src="http://serverIP_or_domain/location_of_video.mp4" type="video/mp4">

How do I configure different environments in Angular.js?

Very late to the thread, but a technique I've used, pre-Angular, is to take advantage of JSON and the flexibility of JS to dynamically reference collection keys, and use inalienable facts of the environment (host server name, current browser language, etc.) as inputs to selectively discriminate/prefer suffixed key names within a JSON data structure.

This provides not merely deploy-environment context (per OP) but any arbitrary context (such as language) to provide i18n or any other variance required simultaneously, and (ideally) within a single configuration manifest, without duplication, and readably obvious.


Overly-simplified but classic example: An API endpoint base URL in a JSON-formatted properties file that varies per environment where (natch) the host server will also vary:

    'svcs': {
        'VER': '2.3',
        'API@localhost': 'http://localhost:9090/',
        '[email protected]': '',
        '[email protected]': ''

A key to the discrimination function is simply the server hostname in the request.

This, naturally, can be combined with an additional key based on the user's language settings:

    'app': {
        'NAME': 'Ferry Reservations',
        'NAME@fr': 'Réservations de ferry',
        'NAME@de': 'Fähren Reservierungen'

The scope of the discrimination/preference can be confined to individual keys (as above) where the "base" key is only overwritten if there's a matching key+suffix for the inputs to the function -- or an entire structure, and that structure itself recursively parsed for matching discrimination/preference suffixes:

    'help': {
        'BLURB': 'This pre-production environment is not supported. Contact Development Team with questions.',
        'PHONE': '808-867-5309',
        'EMAIL': '[email protected]'
    '[email protected]': {
        'BLURB': 'Please contact Customer Service Center',
        'BLURB@fr': 'S\'il vous plaît communiquer avec notre Centre de service à la clientèle',
        'BLURB@de': 'Bitte kontaktieren Sie unseren Kundendienst!!1!',
        'PHONE': '1-800-CUS-TOMR',
        'EMAIL': '[email protected]'

SO, if a visiting user to the production website has German (de) language preference setting, the above configuration would collapse to:

    'help': {
        'BLURB': 'Bitte kontaktieren Sie unseren Kundendienst!!1!',
        'PHONE': '1-800-CUS-TOMR',
        'EMAIL': '[email protected]'

What does such a magical preference/discrimination JSON-rewriting function look like? Not much:

// prefer(object,suffix|[suffixes]) by/par/durch storsoc
// prefer({ a: 'apple', a@env: 'banana', b: 'carrot' },'env') -> { a: 'banana', b: 'carrot' }
function prefer(o,sufs) {
    for (var key in o) {
        if (!o.hasOwnProperty(key)) continue; // skip non-instance props
        if(key.split('@')[1]) { // suffixed!
            // replace root prop with the suffixed prop if among prefs
            if(o[key] && sufs.indexOf(key.split('@')[1]) > -1) o[key.split('@')[0]] = JSON.parse(JSON.stringify(o[key]));

            // and nuke the suffixed prop to tidy up
            delete o[key];

            // continue with root key ...
            key = key.split('@')[0];

        // ... in case it's a collection itself, recurse it!
        if(o[key] && typeof o[key] === 'object') prefer(o[key],sufs);


In our implementations, which include Angular and pre-Angular websites, we simply bootstrap the configuration well ahead of other resource calls by placing the JSON within a self-executing JS closure, including the prefer() function, and fed basic properties of hostname and language-code (and accepts any additional arbitrary suffixes you might need):

(function(prefs){ var props = {
    'svcs': {
        'VER': '2.3',
        'API@localhost': 'http://localhost:9090/',
        '[email protected]': '',
        '[email protected]': ''
    /* yadda yadda moar JSON und bisque */

    function prefer(o,sufs) {
        // body of prefer function, broken for e.g.

    // convert string and comma-separated-string to array .. and process it
    prefs = [].concat( ( prefs.split ? prefs.split(',') : prefs ) || []);
    window.app_props = JSON.parse(JSON.stringify(props));
})([location.hostname, ((window.navigator.userLanguage || window.navigator.language).split('-')[0])  ] );

A pre-Angular site would now have a collapsed (no @ suffixed keys) window.app_props to refer to.

An Angular site, as a bootstrap/init step, simply copies the dead-dropped props object into $rootScope, and (optionally) destroys it from global/window scope

app.constant('props',angular.copy(window.app_props || {})).run( function ($rootScope,props) { $rootScope.props = props; delete window.app_props;} );

to be subsequently injected into controllers:

app.controller('CtrlApp',function($log,props){ ... } );

or referred to from bindings in views:

<span>{{ }} {{ }}</span>

Caveats? The @ character is not valid JS/JSON variable/key naming, but so far accepted. If that's a deal-breaker, substitute for any convention you like, such as "__" (double underscore) as long as you stick to it.

The technique could be applied server-side, ported to Java or C# but your efficiency/compactness may vary.

Alternately, the function/convention could be part of your front-end compile script, so that the full gory all-environment/all-language JSON is never transmitted over the wire.


We've evolved usage of this technique to allow multiple suffixes to a key, to avoid being forced to use collections (you still can, as deeply as you want), and as well to honor the order of the preferred suffixes.

Example (also see working jsFiddle):

var o = { 'a':'apple', 'a@dev':'apple-dev', 'a@fr':'pomme',
          'b':'banana', 'b@fr':'banane', 'b@dev&fr':'banane-dev',
          'c':{ 'o':'c-dot-oh', 'o@fr':'c-point-oh' }, 'c@dev': { 'o':'c-dot-oh-dev', 'o@fr':'c-point-oh-dev' } };

/*1*/ prefer(o,'dev');        // { a:'apple-dev', b:'banana',     c:{o:'c-dot-oh-dev'}   }
/*2*/ prefer(o,'fr');         // { a:'pomme',     b:'banane',     c:{o:'c-point-oh'}     }
/*3*/ prefer(o,'dev,fr');     // { a:'apple-dev', b:'banane-dev', c:{o:'c-point-oh-dev'} }
/*4*/ prefer(o,['fr','dev']); // { a:'pomme',     b:'banane-dev', c:{o:'c-point-oh-dev'} }
/*5*/ prefer(o);              // { a:'apple',     b:'banana',     c:{o:'c-dot-oh'}       }

1/2 (basic usage) prefers '@dev' keys, discards all other suffixed keys

3 prefers '@dev' over '@fr', prefers '@dev&fr' over all others

4 (same as 3 but prefers '@fr' over '@dev')

5 no preferred suffixes, drops ALL suffixed properties

It accomplishes this by scoring each suffixed property and promoting the value of a suffixed property to the non-suffixed property when iterating over the properties and finding a higher-scored suffix.

Some efficiencies in this version, including removing dependence on JSON to deep-copy, and only recursing into objects that survive the scoring round at their depth:

function prefer(obj,suf) {
    function pr(o,s) {
        for (var p in o) {
            if (!o.hasOwnProperty(p) || !p.split('@')[1] || p.split('@@')[1] ) continue; // ignore: proto-prop OR not-suffixed OR temp prop score
            var b = p.split('@')[0]; // base prop name
            if(!!!o['@@'+b]) o['@@'+b] = 0; // +score placeholder
            var ps = p.split('@')[1].split('&'); // array of property suffixes
            var sc = 0; var v = 0; // reset (running)score and value
            while(ps.length) {
                // suffix value: index(of found suffix in prefs)^10
                v = Math.floor(Math.pow(10,s.indexOf(ps.pop())));
                if(!v) { sc = 0; break; } // found suf NOT in prefs, zero score (delete later)
                sc += v;
            if(sc > o['@@'+b]) { o['@@'+b] = sc; o[b] = o[p]; } // hi-score! promote to base prop
            delete o[p];
        for (var p in o) if(p.split('@@')[1]) delete o[p]; // remove scores
        for (var p in o) if(typeof o[p] === 'object') pr(o[p],s); // recurse surviving objs
    if( typeof obj !== 'object' ) return; // validate
    suf = ( (suf || suf === 0 ) && ( suf.length || suf === parseFloat(suf) ) ? suf.toString().split(',') : []); // array|string|number|comma-separated-string -> array-of-strings

Add unique constraint to combination of two columns

In my case, I needed to allow many inactives and only one combination of two keys active, like this:

137          18             0
137          19             0
137          20             1
137          21             0

This seems to work:


Here are my test cases:


insert into USER_UND values (137, 22, 1) --I CAN NOT => Cannot insert duplicate key row in object 'dbo.USER_UND' with unique index 'UQ_USR_UND_UUL_USR_IDF_UUL_ATUAL'. The duplicate key value is (137, 1).
insert into USER_UND values (137, 23, 0) --I CAN
insert into USER_UND values (137, 24, 0) --I CAN


insert into USER_UND values (137, 22, 1) --I CAN
insert into USER_UND values (137, 27, 1) --I CAN NOT => Cannot insert duplicate key row in object 'dbo.USER_UND' with unique index 'UQ_USR_UND_UUL_USR_IDF_UUL_ATUAL'. The duplicate key value is (137, 1).
insert into USER_UND values (137, 28, 0) --I CAN
insert into USER_UND values (137, 29, 0) --I CAN

HTML-Tooltip position relative to mouse pointer

I prefer this technique:

function showTooltip(e) {_x000D_
  var tooltip ="tooltip")_x000D_
      ? e.target_x000D_
      :":scope .tooltip");_x000D_ =_x000D_
      (e.pageX + tooltip.clientWidth + 10 < document.body.clientWidth)_x000D_
          ? (e.pageX + 10 + "px")_x000D_
          : (document.body.clientWidth + 5 - tooltip.clientWidth + "px");_x000D_ =_x000D_
      (e.pageY + tooltip.clientHeight + 10 < document.body.clientHeight)_x000D_
          ? (e.pageY + 10 + "px")_x000D_
          : (document.body.clientHeight + 5 - tooltip.clientHeight + "px");_x000D_
var tooltips = document.querySelectorAll('.couponcode');_x000D_
for(var i = 0; i < tooltips.length; i++) {_x000D_
  tooltips[i].addEventListener('mousemove', showTooltip);_x000D_
.couponcode {_x000D_
    color: red;_x000D_
    cursor: pointer;_x000D_
.couponcode:hover .tooltip {_x000D_
    display: block;_x000D_
.tooltip {_x000D_
    position: absolute;_x000D_
    white-space: nowrap;_x000D_
    display: none;_x000D_
    background: #ffffcc;_x000D_
    border: 1px solid black;_x000D_
    padding: 5px;_x000D_
    z-index: 1000;_x000D_
    color: black;_x000D_
Lorem ipsum dolor sit amet, <span class="couponcode">consectetur_x000D_
adipiscing<span class="tooltip">This is a tooltip</span></span>_x000D_
elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua._x000D_
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi_x000D_
ut aliquip ex ea commodo consequat. Duis aute irure dolor in <span_x000D_
class="couponcode">reprehenderit<span class="tooltip">This is_x000D_
another tooltip</span></span> in voluptate velit esse cillum dolore eu_x000D_
fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident,_x000D_
sunt in culpa qui officia deserunt mollit anim id est <span_x000D_
class="couponcode">laborum<span class="tooltip">This is yet_x000D_
another tooltip</span></span>.

(see also this Fiddle)

Check whether specific radio button is checked

1.You don't need the @ prefix for attribute names any more:

Note: In jQuery 1.3 [@attr] style selectors were removed (they were previously deprecated in jQuery 1.2). Simply remove the ‘@’ symbol from your selectors in order to make them work again.

2.Your selector queries radio buttons by name, but that attribute is not defined in your HTML structure.

What's the function like sum() but for multiplication? product()?

Actually, Guido vetoed the idea:

But, as noted in that issue, you can make one pretty easily:

from functools import reduce # Valid in Python 2.6+, required in Python 3
import operator

reduce(operator.mul, (3, 4, 5), 1)

malloc an array of struct pointers

IMHO, this looks better:

Chess *array = malloc(size * sizeof(Chess)); // array of pointers of size `size`

for ( int i =0; i < SOME_VALUE; ++i )
    array[i] = (Chess) malloc(sizeof(Chess));

Get a list of all git commits, including the 'lost' ones


git fsck --lost-found | grep commit

Then create a branch for each one:

$ git fsck --lost-found | grep commit
Checking object directories: 100% (256/256), done.
dangling commit 2806a32af04d1bbd7803fb899071fcf247a2b9b0
dangling commit 6d0e49efd0c1a4b5bea1235c6286f0b64c4c8de1
dangling commit 91ca9b2482a96b20dc31d2af4818d69606a229d4

$ git branch  branch_2806a3 2806a3
$ git branch  branch_6d0e49 6d0e49
$ git branch  branch_91ca9b 91ca9b

Now many tools will show you a graphical visualization of those lost commits.

Adding hours to JavaScript Date object?

The below code is to add 4 hours to date(example today's date)

var today = new Date();
today.setHours(today.getHours() + 4);

It will not cause error if you try to add 4 to 23 (see the docs):

If a parameter you specify is outside of the expected range, setHours() attempts to update the date information in the Date object accordingly

How do I set the proxy to be used by the JVM

From the Java documentation (not the javadoc API):

Set the JVM flags http.proxyHost and http.proxyPort when starting your JVM on the command line. This is usually done in a shell script (in Unix) or bat file (in Windows). Here's the example with the Unix shell script:

JAVA_FLAGS=-Dhttp.proxyHost= -Dhttp.proxyPort=8800
java ${JAVA_FLAGS} ...

When using containers such as JBoss or WebLogic, my solution is to edit the start-up scripts supplied by the vendor.

Many developers are familiar with the Java API (javadocs), but many times the rest of the documentation is overlooked. It contains a lot of interesting information:

Update : If you do not want to use proxy to resolve some local/intranet hosts, check out the comment from @Tomalak:

Also don't forget the http.nonProxyHosts property!


How do I test a single file using Jest?

Jest will use what you pass as a regular expression pattern. That it will match for.

If you want to run a specific test file, then the best way to do it is to use the precise full path to it. (You can too specify a certain relative path like (src/XFolder/index.spec.ts)).

The easiest way to provide the full path being in the directory and in Linux is:

jest $PWD/index.spec.ts

Note the use of the variable $PWD.

Enter image description here

For Windows! (to be updated)

git still shows files as modified after adding to .gitignore

In my case, the .gitignore file is somehow corrupted. It sometimes shows up OK but sometimes is gibberish. I guess the encoding might be to blame but cannot be sure. To solve the issue, I deleted the file (previously created through echo > .gitgore in VS Code commandline) and created a new one manually in the file system (Explorer), then added my ignore rules. After the new .ignore was in place, everything works fine.

How to find time complexity of an algorithm

Time complexity with examples

1 - Basic Operations (arithmetic, comparisons, accessing array’s elements, assignment) : The running time is always constant O(1)

Example :

read(x)                               // O(1)
a = 10;                               // O(1)
a =         // O(1)

2 - If then else statement: Only taking the maximum running time from two or more possible statements.


age = read(x)                               // (1+1) = 2
if age < 17 then begin                      // 1
      status = "Not allowed!";              // 1
end else begin
      status = "Welcome! Please come in";   // 1
      visitors = visitors + 1;              // 1+1 = 2

So, the complexity of the above pseudo code is T(n) = 2 + 1 + max(1, 1+2) = 6. Thus, its big oh is still constant T(n) = O(1).

3 - Looping (for, while, repeat): Running time for this statement is the number of looping multiplied by the number of operations inside that looping.


total = 0;                                  // 1
for i = 1 to n do begin                     // (1+1)*n = 2n
      total = total + i;                    // (1+1)*n = 2n
writeln(total);                             // 1

So, its complexity is T(n) = 1+4n+1 = 4n + 2. Thus, T(n) = O(n).

4 - Nested Loop (looping inside looping): Since there is at least one looping inside the main looping, running time of this statement used O(n^2) or O(n^3).


for i = 1 to n do begin                     // (1+1)*n  = 2n
   for j = 1 to n do begin                  // (1+1)n*n = 2n^2
       x = x + 1;                           // (1+1)n*n = 2n^2
       print(x);                            // (n*n)    = n^2

Common Running Time

There are some common running times when analyzing an algorithm:

  1. O(1) – Constant Time Constant time means the running time is constant, it’s not affected by the input size.

  2. O(n) – Linear Time When an algorithm accepts n input size, it would perform n operations as well.

  3. O(log n) – Logarithmic Time Algorithm that has running time O(log n) is slight faster than O(n). Commonly, algorithm divides the problem into sub problems with the same size. Example: binary search algorithm, binary conversion algorithm.

  4. O(n log n) – Linearithmic Time This running time is often found in "divide & conquer algorithms" which divide the problem into sub problems recursively and then merge them in n time. Example: Merge Sort algorithm.

  5. O(n2) – Quadratic Time Look Bubble Sort algorithm!

  6. O(n3) – Cubic Time It has the same principle with O(n2).

  7. O(2n) – Exponential Time It is very slow as input get larger, if n = 1000.000, T(n) would be 21000.000. Brute Force algorithm has this running time.

  8. O(n!) – Factorial Time THE SLOWEST !!! Example : Travel Salesman Problem (TSP)

Taken from this article. Very well explained should give a read.

How do I use Notepad++ (or other) with msysgit?

As of Git for Windows v2.15.0 (October 30th 2017) it is now possible to configure nano or Notepad++ as Git's default editor instead of vim.

During the installation you'll see the following screen:

enter image description here

How to disable CSS in Browser for testing purposes

you can block any request (even for a single css file) from inspector with the following:
    Right click > block request URL
without disabling other css files > It's a standard inspector feature, no plugins or tricks needed

Fastest way to check if a value exists in a list

Code to check whether two elements exist in array whose product equals k:

n = len(arr1)
for i in arr1:
    if k%i==0:

Remove a specific character using awk or sed

Using just awk you could do (I also shortened some of your piping):

strings -a | awk '/EngineVersion/ { if(NR==2) { gsub("\"",""); print $2 } }'

I can't verify it for you because I don't know your exact input, but the following works:

echo "Blah EngineVersion=\"123\"" | awk '/EngineVersion/ { gsub("\"",""); print $2 }'

See also this question on removing single quotes.

When to use NSInteger vs. int

Why use int at all?

Apple uses int because for a loop control variable (which is only used to control the loop iterations) int datatype is fine, both in datatype size and in the values it can hold for your loop. No need for platform dependent datatype here. For a loop control variable even a 16-bit int will do most of the time.

Apple uses NSInteger for a function return value or for a function argument because in this case datatype [size] matters, because what you are doing with a function is communicating/passing data with other programs or with other pieces of code; see the answer to When should I be using NSInteger vs int? in your question itself...

they [Apple] use NSInteger (or NSUInteger) when passing a value as an argument to a function or returning a value from a function.

Passing std::string by Value or Reference

Check this answer for C++11. Basically, if you pass an lvalue the rvalue reference

From this article:

void f1(String s) {
    vector<String> v;
void f2(const String &s) {
    vector<String> v;

"For lvalue argument, ‘f1’ has one extra copy to pass the argument because it is by-value, while ‘f2’ has one extra copy to call push_back. So no difference; for rvalue argument, the compiler has to create a temporary ‘String(L“”)’ and pass the temporary to ‘f1’ or ‘f2’ anyway. Because ‘f2’ can take advantage of move ctor when the argument is a temporary (which is an rvalue), the costs to pass the argument are the same now for ‘f1’ and ‘f2’."

Continuing: " This means in C++11 we can get better performance by using pass-by-value approach when:

  1. The parameter type supports move semantics - All standard library components do in C++11
  2. The cost of move constructor is much cheaper than the copy constructor (both the time and stack usage).
  3. Inside the function, the parameter type will be passed to another function or operation which supports both copy and move.
  4. It is common to pass a temporary as the argument - You can organize you code to do this more.


OTOH, for C++98 it is best to pass by reference - less data gets copied around. Passing const or non const depend of whether you need to change the argument or not.

How to check if a string array contains one string in JavaScript?

var stringArray = ["String1", "String2", "String3"];

return (stringArray.indexOf(searchStr) > -1)

How to filter by IP address in Wireshark?

Actually for some reason wireshark uses two different kind of filter syntax one on display filter and other on capture filter. Display filter is only useful to find certain traffic just for display purpose only. its like you are interested in all trafic but for now you just want to see specific.

but if you are interested only in certian traffic and does not care about other at all then you use the capture filter.

The Syntax for display filter is (as mentioned earlier)

ip.addr = x.x.x.x or ip.src = x.x.x.x or ip.dst = x.x.x.x

but above syntax won't work in capture filters, following are the filters

host x.x.x.x

see more example on wireshark wiki page

Convert array of JSON object strings to array of JS objects

If you really have:

var s = ['{"Select":"11", "PhotoCount":"12"}','{"Select":"21", "PhotoCount":"22"}'];

then simply:

var objs = $.map(s, $.parseJSON);

Here's a demo.

Foreign Key to non-primary key

Primary keys always need to be unique, foreign keys need to allow non-unique values if the table is a one-to-many relationship. It is perfectly fine to use a foreign key as the primary key if the table is connected by a one-to-one relationship, not a one-to-many relationship.

A FOREIGN KEY constraint does not have to be linked only to a PRIMARY KEY constraint in another table; it can also be defined to reference the columns of a UNIQUE constraint in another table.

startForeground fail after upgrade to Android 8.1

After some tinkering for a while with different solutions i found out that one must create a notification channel in Android 8.1 and above.

private fun startForeground() {
    val channelId =
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                createNotificationChannel("my_service", "My Background Service")
            } else {
                // If earlier version channel ID is not used

    val notificationBuilder = NotificationCompat.Builder(this, channelId )
    val notification = notificationBuilder.setOngoing(true)
    startForeground(101, notification)

private fun createNotificationChannel(channelId: String, channelName: String): String{
    val chan = NotificationChannel(channelId,
            channelName, NotificationManager.IMPORTANCE_NONE)
    chan.lightColor = Color.BLUE
    chan.lockscreenVisibility = Notification.VISIBILITY_PRIVATE
    val service = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
    return channelId

From my understanding background services are now displayed as normal notifications that the user then can select to not show by deselecting the notification channel.

Update: Also don't forget to add the foreground permission as required Android P:

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

How to determine whether a year is a leap year?

If you don't want to import calendar and apply .isleap method you can try this:

def isleapyear(year):
    if year % 4 == 0 and (year % 100 != 0 or year % 400 == 0):
        return True
    return False

NSURLErrorDomain error codes description

I was unable to find name of an error for given code when developing in Swift. For that reason I paste minus codes for NSURLErrorDomain taken from NSURLError.h

    @enum NSURL-related Error Codes
    @abstract Constants used by NSError to indicate errors in the NSURL domain
    NSURLErrorUnknown =             -1,
    NSURLErrorCancelled =           -999,
    NSURLErrorBadURL =              -1000,
    NSURLErrorTimedOut =            -1001,
    NSURLErrorUnsupportedURL =          -1002,
    NSURLErrorCannotFindHost =          -1003,
    NSURLErrorCannotConnectToHost =         -1004,
    NSURLErrorNetworkConnectionLost =       -1005,
    NSURLErrorDNSLookupFailed =         -1006,
    NSURLErrorHTTPTooManyRedirects =        -1007,
    NSURLErrorResourceUnavailable =         -1008,
    NSURLErrorNotConnectedToInternet =      -1009,
    NSURLErrorRedirectToNonExistentLocation =   -1010,
    NSURLErrorBadServerResponse =       -1011,
    NSURLErrorUserCancelledAuthentication =     -1012,
    NSURLErrorUserAuthenticationRequired =  -1013,
    NSURLErrorZeroByteResource =        -1014,
    NSURLErrorCannotDecodeRawData =             -1015,
    NSURLErrorCannotDecodeContentData =         -1016,
    NSURLErrorCannotParseResponse =             -1017,
    NSURLErrorAppTransportSecurityRequiresSecureConnection NS_ENUM_AVAILABLE(10_11, 9_0) = -1022,
    NSURLErrorFileDoesNotExist =        -1100,
    NSURLErrorFileIsDirectory =         -1101,
    NSURLErrorNoPermissionsToReadFile =     -1102,
    NSURLErrorDataLengthExceedsMaximum NS_ENUM_AVAILABLE(10_5, 2_0) =   -1103,

    // SSL errors
    NSURLErrorSecureConnectionFailed =      -1200,
    NSURLErrorServerCertificateHasBadDate =     -1201,
    NSURLErrorServerCertificateUntrusted =  -1202,
    NSURLErrorServerCertificateHasUnknownRoot = -1203,
    NSURLErrorServerCertificateNotYetValid =    -1204,
    NSURLErrorClientCertificateRejected =   -1205,
    NSURLErrorClientCertificateRequired =   -1206,
    NSURLErrorCannotLoadFromNetwork =       -2000,

    // Download and file I/O errors
    NSURLErrorCannotCreateFile =        -3000,
    NSURLErrorCannotOpenFile =          -3001,
    NSURLErrorCannotCloseFile =         -3002,
    NSURLErrorCannotWriteToFile =       -3003,
    NSURLErrorCannotRemoveFile =        -3004,
    NSURLErrorCannotMoveFile =          -3005,
    NSURLErrorDownloadDecodingFailedMidStream = -3006,
    NSURLErrorDownloadDecodingFailedToComplete =-3007,

    NSURLErrorInternationalRoamingOff NS_ENUM_AVAILABLE(10_7, 3_0) =         -1018,
    NSURLErrorCallIsActive NS_ENUM_AVAILABLE(10_7, 3_0) =                    -1019,
    NSURLErrorDataNotAllowed NS_ENUM_AVAILABLE(10_7, 3_0) =                  -1020,
    NSURLErrorRequestBodyStreamExhausted NS_ENUM_AVAILABLE(10_7, 3_0) =      -1021,

    NSURLErrorBackgroundSessionRequiresSharedContainer NS_ENUM_AVAILABLE(10_10, 8_0) = -995,
    NSURLErrorBackgroundSessionInUseByAnotherProcess NS_ENUM_AVAILABLE(10_10, 8_0) = -996,
    NSURLErrorBackgroundSessionWasDisconnected NS_ENUM_AVAILABLE(10_10, 8_0)= -997,

How to negate specific word in regex?

You could either use a negative look-ahead or look-behind:


Or use just basics:


These all match anything that does not contain bar.

Reorder HTML table rows using drag-and-drop

Apparently the question poorly describes the OP's problem, but this question is the top search result for dragging to reorder table rows, so that is what I will answer. I wasn't interested in bringing in jQuery UI for something so simple, so here is a jQuery only solution:

$(".grab").mousedown(function(e) {
  var tr = $("TR"),
    si = tr.index(),
    sy = e.pageY,
    b = $(document.body),
  if (si == 0) return;
  b.addClass("grabCursor").css("userSelect", "none");

  function move(e) {
    if (!drag && Math.abs(e.pageY - sy) < 10) return;
    drag = true;
    tr.siblings().each(function() {
      var s = $(this),
        i = s.index(),
        y = s.offset().top;
      if (i > 0 && e.pageY >= y && e.pageY < y + s.outerHeight()) {
        if (i < tr.index())
        return false;

  function up(e) {
    if (drag && si != tr.index()) {
      drag = false;
    $(document).unbind("mousemove", move).unbind("mouseup", up);
    b.removeClass("grabCursor").css("userSelect", "none");
.grab {
  cursor: grab;

.grabbed {
  box-shadow: 0 0 13px #000;

.grabCursor * {
  cursor: grabbing !important;
<script src=""></script>
    <th>Table Header</th>
    <td class="grab">&#9776;</td>
    <td>Table Cell 1</td>
    <td class="grab">&#9776;</td>
    <td>Table Cell 2</td>
    <td class="grab">&#9776;</td>
    <td>Table Cell 3</td>

Note si == 0 and i > 0 ignores the first row, which for me contains TH tags. Replace the alert with your "drag finished" logic.

When is assembly faster than C?

This question is a bit pointless, because anyways c is compiled to assembler. But, the assembler produced by optimizing compilers is almost fully optimized, so unless you did twenty doctorates on optimizing specific assembly, you can't beat the compiler.

Portable way to get file size (in bytes) in shell?

You can use find command to get some set of files (here temp files are extracted). Then you can use du command to get the file size of each file in human readable form using -h switch.

find $HOME -type f -name "*~" -exec du -h {} \;


4.0K    /home/turing/Desktop/JavaExmp/
4.0K    /home/turing/Desktop/JavaExmp/
4.0K    /home/turing/Desktop/JavaExmp/
4.0K    /home/turing/Desktop/JavaExmp/
4.0K    /home/turing/Desktop/JavaExmp/
4.0K    /home/turing/Desktop/JavaExmp/

Using the slash character in Git branch name

It is possible to have hierarchical branch names (branch names with slash). For example in my repository I have such branch(es). One caveat is that you can't have both branch 'foo' and branch 'foo/bar' in repository.

Your problem is not with creating branch with slash in name.

$ git branch foo/bar
error: unable to resolve reference refs/heads/labs/feature: Not a directory
fatal: Failed to lock ref for update: Not a directory

The above error message talks about 'labs/feature' branch, not 'foo/bar' (unless it is a mistake in copy'n'paste, i.e you edited parts of session). What is the result of git branch or git rev-parse --symbolic-full-name HEAD?

Array versus linked-list

Eric Lippert recently had a post on one of the reasons arrays should be used conservatively.

Count multiple columns with group by in one query

One solution is to wrap it in a subquery

    SELECT COUNT(column1),column1 FROM table GROUP BY column1
    SELECT COUNT(column2),column2 FROM table GROUP BY column2
    SELECT COUNT(column3),column3 FROM table GROUP BY column3
) s

Safest way to convert float to integer in python?

Combining two of the previous results, we have:


This converts a float to an integer fairly dependably.

XAMPP Apache won't start

After trying all the suggestion given above. Disable this, install that. I opened the xampp-control manager from the start but this this as administrator. After I opened it. MySQL was disable. I disable all of the program and enable apache first and then MySQL. Suddenly start working with no problem.

jQuery Event : Detect changes to the html/text of a div

If you don't want use timer and check innerHTML you can try this event

$('mydiv').bind('DOMSubtreeModified', function(){

More details and browser support datas are Here.

Attention: in newer jQuery versions bind() is deprecated, so you should use on() instead:

$('body').on('DOMSubtreeModified', 'mydiv', function(){


use desc with orderby at the end of the query to get the last values.

How to handle anchor hash linking in AngularJS

On Route change it will scroll to the top of the page.

 $scope.$on('$routeChangeSuccess', function () {
      window.scrollTo(0, 0);

put this code on your controller.

Convert date from 'Thu Jun 09 2011 00:00:00 GMT+0530 (India Standard Time)' to 'YYYY-MM-DD' in javascript

The easiest way for me to convert a date was to stringify it then slice it.

var event = new Date("Fri Apr 05 2019 16:59:00 GMT-0700 (Pacific Daylight Time)");

let date = JSON.stringify(event)
date = date.slice(1,11)

// console.log(date) = '2019-04-05'

Add a border outside of a UIView (instead of inside)

I liked solution of @picciano If you want exploding circle instead of square replace addExternalBorder function with:

func addExternalBorder(borderWidth: CGFloat = 2.0, borderColor: UIColor = UIColor.white) {
        let externalBorder = CALayer()
        externalBorder.frame = CGRect(x: -borderWidth, y: -borderWidth, width: frame.size.width + 2 * borderWidth, height: frame.size.height + 2 * borderWidth)
        externalBorder.borderColor = borderColor.cgColor
        externalBorder.borderWidth = borderWidth
        externalBorder.cornerRadius = (frame.size.width + 2 * borderWidth) / 2 = Constants.ExternalBorderName
        layer.insertSublayer(externalBorder, at: 0)
        layer.masksToBounds = false


What is the maximum length of a table name in Oracle?

In the 10g database I'm dealing with, I know table names are maxed at 30 characters. Couldn't tell you what the column name length is (but I know it's > 30).

Limiting the number of characters per line with CSS

You could do this:
(Note! This is CSS3 and the browser support = good!! )

   p {
    text-overflow: ellipsis; /* will make [...] at the end */
    width: 370px; /* change to your preferences */
    white-space: nowrap; /* paragraph to one line */
    overflow:hidden; /* older browsers */

How to get the current time as datetime

Swift 4

let dateFormatter : DateFormatter = DateFormatter()
//  dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
dateFormatter.dateFormat = "yyyy-MMM-dd HH:mm:ss"
let date = Date()
let dateString = dateFormatter.string(from: date)
let interval = date.timeIntervalSince1970


2018-May-01 10:41:31

How can I clone a JavaScript object except for one key?

I recently did it this very simple way:

const obj = {a: 1, b: 2, ..., z:26};

just using spread operator to separate the unwanted property:

const {b,} = obj;

...and object.assign to take only the 'rest' part:

const newObj = Object.assign({}, {});

How to cherry-pick multiple commits

The simplest way to do this is with the onto option to rebase. Suppose that the branch which current finishes at a is called mybranch and this is the branch that you want to move c-f onto.

# checkout mybranch
git checkout mybranch

# reset it to f (currently includes a)
git reset --hard f

# rebase every commit after b and transplant it onto a
git rebase --onto a b

How to change the Eclipse default workspace?

This is the only answer you got first when you search for default workspace, but any solution is not solved my problem, So I follow this step for a default workspace:

  1. First copy shortcut icon for your eclipse.
  2. Right click and go to properties, add your workspace path with -data attribute,

In Target:

D:\eclipse_path\eclipse.exe -clean -data D:\workspace_path\workspace

enter image description here

For using the same shortcuts and preference into this workspace, Export general --> preference from your working eclipse, it will generate one .epf file.

So, just import .epf file into your new workspace, and you are done.

enter image description here

You have not accepted the license agreements of the following SDK components

You can accept the license agreement by launching Android Studio, then going to:

Help > Check for Updates...

When you are installing updates, it'll ask you to accept the license agreement. Accept the license agreement and install the updates, and you are all set.

Linq style "For Each"

There isn't anything like that in standard Linq, but there is a ForEach operator in MoreLinq.

How to call a Web Service Method?

The current way to do this is by using the "Add Service Reference" command. If you specify "TestUploaderWebService" as the service reference name, that will generate the type TestUploaderWebService.Service1. That class will have a method named GetFileListOnWebServer, which will return an array of strings (you can change that to be a list of strings if you like). You would use it like this:

string[] files = null;
TestUploaderWebService.Service1 proxy = null;
bool success = false;
    proxy = new TestUploaderWebService.Service1();
    files = proxy.GetFileListOnWebServer();
    success = true;
    if (!success)

P.S. Tell your instructor to look at "Microsoft: ASMX Web Services are a “Legacy Technology”", and ask why he's teaching out of date technology.

How do I pass the this context to a function?

Javascripts .call() and .apply() methods allow you to set the context for a function.

var myfunc = function(){

var obj_a = {
    name:  "FOO"

var obj_b = {
    name:  "BAR!!"

Now you can call:;

Which would alert FOO. The other way around, passing obj_b would alert BAR!!. The difference between .call() and .apply() is that .call() takes a comma separated list if you're passing arguments to your function and .apply() needs an array., 1, 2, 3);
myfunc.apply(obj_a, [1, 2, 3]);

Therefore, you can easily write a function hook by using the apply() method. For instance, we want to add a feature to jQuerys .css() method. We can store the original function reference, overwrite the function with custom code and call the stored function.

var _css = $.fn.css;
$.fn.css = function(){
   _css.apply(this, arguments);

Since the magic arguments object is an array like object, we can just pass it to apply(). That way we guarantee, that all parameters are passed through to the original function.

Pass a PHP array to a JavaScript function

You can pass PHP arrays to JavaScript using json_encode PHP function.

    $phpArray = array(
        0 => "Mon", 
        1 => "Tue", 
        2 => "Wed", 
        3 => "Thu",
        4 => "Fri", 
        5 => "Sat",
        6 => "Sun",

<script type="text/javascript">

    var jArray = <?php echo json_encode($phpArray); ?>;

    for(var i=0; i<jArray.length; i++){


How to pass variable number of arguments to a PHP function

You can just call it.

function test(){        



Array ( [0] => blah ) Array ( [0] => blah [1] => blah )

How do I sort a vector of pairs based on the second element of the pair?

For something reusable:

template<template <typename> class P = std::less >
struct compare_pair_second {
    template<class T1, class T2> bool operator()(const std::pair<T1, T2>& left, const std::pair<T1, T2>& right) {
        return P<T2>()(left.second, right.second);

You can use it as

std::sort(foo.begin(), foo.end(), compare_pair_second<>());


std::sort(foo.begin(), foo.end(), compare_pair_second<std::less>());

How to plot a 2D FFT in Matlab?

Assuming that I is your input image and F is its Fourier Transform (i.e. F = fft2(I))

You can use this code:

F = fftshift(F); % Center FFT

F = abs(F); % Get the magnitude
F = log(F+1); % Use log, for perceptual scaling, and +1 since log(0) is undefined
F = mat2gray(F); % Use mat2gray to scale the image between 0 and 1

imshow(F,[]); % Display the result

How do I pull from a Git repository through an HTTP proxy?

I had the same problem, with a slightly different fix: REBUILDING GIT WITH HTTP SUPPORT

The git: protocol did not work through my corporate firewall.

For example, this timed out:

git clone git://

curl works just fine, though, so I know my http_proxy environment variable is correct.

I tried using http, like below, but got an immediate error.

git clone

->>>  fatal: Unable to find remote helper for 'http' <<<-

I tried recompiling git like so:

./configure  --with-curl --with-expat

but still got the fatal error.

Finally, after several frustrating hours, I read the configure file, and saw this:

# Define CURLDIR=/foo/bar if your curl header and library files are in

# /foo/bar/include and /foo/bar/lib directories.

I remembered then, that I had not complied curl from source, and so went looking for the header files. Sure enough, they were not installed. That was the problem. Make did not complain about the missing header files. So I did not realize that the --with-curl option did nothing (it is, in fact the default in my version of git).

I did the following to fix it:

  1. Added the headers needed for make:

    yum install curl-devel
    (expat-devel-1.95.8-8.3.el5_5.3.i386  was already installed).
  2. Removed git from /usr/local (as I want the new install to live there).

    I simply removed git* from /usr/local/share and /usr/local/libexec

  3. Searched for the include dirs containing the curl and expat header files, and then (because I had read through configure) added these to the environment like so:

    export CURLDIR=/usr/include 
    export EXPATDIR=/usr/include
  4. Ran configure with the following options, which, again, were described in the configure file itself, and were also the defaults but what the heck:

    ./configure  --with-curl --with-expat
  5. And now http works with git through my corporate firewall:

    git clone
    Cloning into 'node-websocket-server'...
    * Couldn't find host in the .netrc file, using defaults
    * About to connect() to proxy port 8080
    *   Trying * connected

How to parse a string in JavaScript?

as amber and sinan have noted above, the javascritp '.split' method will work just fine. Just pass it the string separator(-) and the string that you intend to split('123-abc-itchy-knee') and it will do the rest.

    var coolVar = '123-abc-itchy-knee';
    var coolVarParts = coolVar.split('-'); // this is an array containing the items

    var1=coolVarParts[0]; //this will retrieve 123

To access each item from the array just use the respective index(indices start at zero).

How to take complete backup of mysql database using mysqldump command line utility

If you want to take a full backup i.e., all databases, procedures, routines, and events without interrupting any connections:

mysqldump -u [username] -p -A -R -E --triggers --single-transaction > full_backup.sql
  1. -A For all databases (you can also use --all-databases)
  2. -R For all routines (stored procedures & triggers)
  3. -E For all events
  4. --single-transaction Without locking the tables i.e., without interrupting any connection (R/W).

If you want to take a backup of only specified database(s):

mysqldump -u [username] -p [database_name] [other_database_name] -R -e --triggers --single-transaction > database_backup.sql

If you want to take a backup of only a specific table in a database:

mysqldump -u [username] -p [database_name] [table_name] > table_backup.sql

If you want to take a backup of the database structure only just add --no-data to the previous commands:

mysqldump -u [username] –p[password] –-no-data [database_name] > dump_file.sql

mysqldump has many more options, which are all documented in the mysqldump documentation or by running man mysqldump at the command line.

SQL Server find and replace specific word in all rows of specific column

SET number = REPLACE(number, 'KIT', 'CH')
WHERE number like 'KIT%'

or simply this if you are sure that you have no values like this CKIT002

SET number = REPLACE(number, 'KIT', 'CH')

Private pages for a private Github repo

As outlined above, Github pages do not support that functionality. I had the same issue when our team decided to host project documentation (static HTML) internally and privately.

I ended up creating a service It is basically a simple proxy server with Github OAuth authentication, so it merely returns your GitHub repository content with a proper MIME type. By design, only who have access to foo will be able to see foo content at From functional point of view, you can think about it as a simplified GitHub pages with built-in authentication.

Unfortunately, Github OAuth does not allow to request read-only access to private repos, so the server needs the full access (obviously, it does not write anything to your repo). As GitHub API allows to retrieve files under 1 Mb only, the service cannot return larger files. Yet, I found the service is quite suitable for small projects for internal documentation or staging version of a website.

sed: print only matching group

The cut command is designed for this exact situation. It will "cut" on any delimiter and then you can specify which chunks should be output.

For instance: echo "foo bar <foo> bla 1 2 3.4" | cut -d " " -f 6-7

Will result in output of: 2 3.4

-d sets the delimiter

-f selects the range of 'fields' to output, in this case, it's the 6th through 7th chunks of the original string. You can also specify the range as a list, such as 6,7.

Overlapping elements in CSS

I think you could get away with using relative positioning and then set the top/left positioning of the second DIV until you have it in the position desired.

How can I align all elements to the left in JPanel?

The easiest way I've found to place objects on the left is using FlowLayout.

JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEFT));

adding a component normally to this panel will place it on the left

Copy array items into another array

With JavaScript ES6, you can use the ... operator as a spread operator which will essentially convert the array into values. Then, you can do something like this:

const myArray = [1,2,3,4,5];
const moreData = [6,7,8,9,10];

const newArray = [

While the syntax is concise, I do not know how this works internally and what the performance implications are on large arrays.

select count(*) from select

You're missing a FROM and you need to give the subquery an alias.

  SELECT DISTINCT a.my_id, a.last_name, a.first_name, b.temp_val
   FROM dbo.Table_A AS a 
   INNER JOIN dbo.Table_B AS b 
   ON a.a_id = b.a_id
) AS subquery;

Pad left or right with string.format (not padleft or padright) with arbitrary string

You could encapsulate the string in a struct that implements IFormattable

public struct PaddedString : IFormattable
   private string value;
   public PaddedString(string value) { this.value = value; }

   public string ToString(string format, IFormatProvider formatProvider)
      //... use the format to pad value

   public static explicit operator PaddedString(string value)
     return new PaddedString(value);

Then use this like that :

 string.Format("->{0:x20}<-", (PaddedString)"Hello");



Angular: conditional class with *ngClass

This is what worked for me:

[ngClass]="{'active': dashboardComponent.selected_menu == 'profile'}"

Use of alloc init instead of new

There are a bunch of reasons here:

Some selected ones are:

  • new doesn't support custom initializers (like initWithString)
  • alloc-init is more explicit than new

General opinion seems to be that you should use whatever you're comfortable with.

A monad is just a monoid in the category of endofunctors, what's the problem?

That particular phrasing is by James Iry, from his highly entertaining Brief, Incomplete and Mostly Wrong History of Programming Languages, in which he fictionally attributes it to Philip Wadler.

The original quote is from Saunders Mac Lane in Categories for the Working Mathematician, one of the foundational texts of Category Theory. Here it is in context, which is probably the best place to learn exactly what it means.

But, I'll take a stab. The original sentence is this:

All told, a monad in X is just a monoid in the category of endofunctors of X, with product × replaced by composition of endofunctors and unit set by the identity endofunctor.

X here is a category. Endofunctors are functors from a category to itself (which is usually all Functors as far as functional programmers are concerned, since they're mostly dealing with just one category; the category of types - but I digress). But you could imagine another category which is the category of "endofunctors on X". This is a category in which the objects are endofunctors and the morphisms are natural transformations.

And of those endofunctors, some of them might be monads. Which ones are monads? Exactly the ones which are monoidal in a particular sense. Instead of spelling out the exact mapping from monads to monoids (since Mac Lane does that far better than I could hope to), I'll just put their respective definitions side by side and let you compare:

A monoid is...

  • A set, S
  • An operation, • : S × S ? S
  • An element of S, e : 1 ? S

...satisfying these laws:

  • (a • b) • c = a • (b • c), for all a, b and c in S
  • e • a = a • e = a, for all a in S

A monad is...

  • An endofunctor, T : X ? X (in Haskell, a type constructor of kind * -> * with a Functor instance)
  • A natural transformation, µ : T × T ? T, where × means functor composition (µ is known as join in Haskell)
  • A natural transformation, ? : I ? T, where I is the identity endofunctor on X (? is known as return in Haskell)

...satisfying these laws:

  • µ ° Tµ = µ ° µT
  • µ ° T? = µ ° ?T = 1 (the identity natural transformation)

With a bit of squinting you might be able to see that both of these definitions are instances of the same abstract concept.

Difference between Pig and Hive? Why have both?

Read the difference between PIG and HIVE in this link.

All the aspects are given. If you are in the confusion which to choose then you must see that web page.

How to get a web page's source code from Java

Try the following code with an added request property:


public class SocketConnection
    public static String getURLSource(String url) throws IOException
        URL urlObject = new URL(url);
        URLConnection urlConnection = urlObject.openConnection();
        urlConnection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");

        return toString(urlConnection.getInputStream());

    private static String toString(InputStream inputStream) throws IOException
        try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8")))
            String inputLine;
            StringBuilder stringBuilder = new StringBuilder();
            while ((inputLine = bufferedReader.readLine()) != null)

            return stringBuilder.toString();

SQL query for a carriage return in a string and ultimately removing carriage return

this will be slow, but if it is a one time thing, try...

select * from parameters where name like '%'+char(13)+'%' or name like '%'+char(10)+'%'

Note that the ANSI SQL string concatenation operator is "||", so it may need to be:

select * from parameters where name like '%' || char(13) || '%' or name like '%' || char(10) || '%'

Truncate (not round off) decimal numbers in javascript


So, after all it turned out, rounding bugs will always haunt you, no matter how hard you try to compensate them. Hence the problem should be attacked by representing numbers exactly in decimal notation.

Number.prototype.toFixedDown = function(digits) {
    var re = new RegExp("(\\d+\\.\\d{" + digits + "})(\\d)"),
        m = this.toString().match(re);
    return m ? parseFloat(m[1]) : this.valueOf();

[   5.467.toFixedDown(2),
    1.11.toFixedDown(1) + 22];

// [5.46, 985.94, 17.56, 0, 23.1]

Old error-prone solution based on compilation of others':

Number.prototype.toFixedDown = function(digits) {
  var n = this - Math.pow(10, -digits)/2;
  n += n / Math.pow(2, 53); // added 1360765523: 17.56.toFixedDown(2) === "17.56"
  return n.toFixed(digits);

Return a "NULL" object if search result not found

The reason that you can't return NULL here is because you've declared your return type as Attr&. The trailing & makes the return value a "reference", which is basically a guaranteed-not-to-be-null pointer to an existing object. If you want to be able to return null, change Attr& to Attr*.

Git Cherry-Pick and Conflicts

Do, I need to resolve all the conflicts before proceeding to next cherry -pick

Yes, at least with the standard git setup. You cannot cherry-pick while there are conflicts.

Furthermore, in general conflicts get harder to resolve the more you have, so it's generally better to resolve them one by one.

That said, you can cherry-pick multiple commits at once, which would do what you are asking for. See e.g. How to cherry-pick multiple commits . This is useful if for example some commits undo earlier commits. Then you'd want to cherry-pick all in one go, so you don't have to resolve conflicts for changes that are undone by later commits.

Further, is it suggested to do cherry-pick or branch merge in this case?

Generally, if you want to keep a feature branch up to date with main development, you just merge master -> feature branch. The main advantage is that a later merge feature branch -> master will be much less painful.

Cherry-picking is only useful if you must exclude some changes in master from your feature branch. Still, this will be painful so I'd try to avoid it.

MySQL search and replace some text in a field

The Replace string function will do that.

C# static class constructor

We can create static constructor

static class StaticParent 
    //write your initialization code here



and it is always parameter less.

static class StaticParent
    static int i =5;
    static StaticParent(int i)  //Gives error
      //write your initialization code here

and it doesn't have the access modifier

Sending mail from Python using SMTP

Make sure you don't have any firewalls blocking SMTP. The first time I tried to send an email, it was blocked both by Windows Firewall and McAfee - took forever to find them both.

How to get the <td> in HTML tables to fit content, and let a specific <td> fill in the rest

demo -

added border for better view (testing)

more info about white-space

table td{
    white-space: nowrap;  /** added **/
table td:last-child{

    table {_x000D_
      width: 100%;_x000D_
    table td {_x000D_
      white-space: nowrap;_x000D_
    table td:last-child {_x000D_
      width: 100%;_x000D_
<table border="1">_x000D_
      <th>Column A</th>_x000D_
      <th>Column B</th>_x000D_
      <th>Column C</th>_x000D_
      <th class="absorbing-column">Column D</th>_x000D_
      <td>Data A.1 lorem</td>_x000D_
      <td>Data B.1 ip</td>_x000D_
      <td>Data C.1 sum l</td>_x000D_
      <td>Data D.1</td>_x000D_
      <td>Data A.2 ipsum</td>_x000D_
      <td>Data B.2 lorem</td>_x000D_
      <td>Data C.2 some data</td>_x000D_
      <td>Data D.2 a long line of text that is long</td>_x000D_
      <td>Data A.3</td>_x000D_
      <td>Data B.3</td>_x000D_
      <td>Data C.3</td>_x000D_
      <td>Data D.3</td>_x000D_

Why can't I duplicate a slice with `copy()`?

If your slices were of the same size, it would work:

arr := []int{1, 2, 3}
tmp := []int{0, 0, 0}
i := copy(tmp, arr)

Would give:

[1 2 3]
[1 2 3]

From "Go Slices: usage and internals":

The copy function supports copying between slices of different lengths (it will copy only up to the smaller number of elements)

The usual example is:

t := make([]byte, len(s), (cap(s)+1)*2)
copy(t, s)
s = t

Python Remove last char from string and return it

Not only is it the preferred way, it's the only reasonable way. Because strings are immutable, in order to "remove" a char from a string you have to create a new string whenever you want a different string value.

You may be wondering why strings are immutable, given that you have to make a whole new string every time you change a character. After all, C strings are just arrays of characters and are thus mutable, and some languages that support strings more cleanly than C allow mutable strings as well. There are two reasons to have immutable strings: security/safety and performance.

Security is probably the most important reason for strings to be immutable. When strings are immutable, you can't pass a string into some library and then have that string change from under your feet when you don't expect it. You may wonder which library would change string parameters, but if you're shipping code to clients you can't control their versions of the standard library, and malicious clients may change out their standard libraries in order to break your program and find out more about its internals. Immutable objects are also easier to reason about, which is really important when you try to prove that your system is secure against particular threats. This ease of reasoning is especially important for thread safety, since immutable objects are automatically thread-safe.

Performance is surprisingly often better for immutable strings. Whenever you take a slice of a string, the Python runtime only places a view over the original string, so there is no new string allocation. Since strings are immutable, you get copy semantics without actually copying, which is a real performance win.

Eric Lippert explains more about the rationale behind immutable of strings (in C#, not Python) here.

Appending a byte[] to the end of another byte[]

Perhaps the easiest way:

ByteArrayOutputStream output = new ByteArrayOutputStream();


byte[] out = output.toByteArray();

How do you disable browser Autocomplete on web form field / input tag?

Most of the major browsers and password managers (correctly, IMHO) now ignore autocomplete=off.

Why? Many banks and other "high security" websites added autocomplete=off to their login pages "for security purposes" but this actually decreases security since it causes people to change the passwords on these high-security sites to be easy to remember (and thus crack) since autocomplete was broken.

Long ago most password managers started ignoring autocomplete=off, and now the browsers are starting to do the same for username/password inputs only.

Unfortunately, bugs in the autocomplete implementations insert username and/or password info into inappropriate form fields, causing form validation errors, or worse yet, accidentally inserting usernames into fields that were intentionally left blank by the user.

What's a web developer to do?

  • If you can keep all password fields on a page by themselves, that's a great start as it seems that the presence of a password field is the main trigger for user/pass autocomplete to kick in. Otherwise, read the tips below.
  • Safari notices that there are 2 password fields and disables autocomplete in this case, assuming it must be a change password form, not a login form. So just be sure to use 2 password fields (new and confirm new) for any forms where you allow
  • Chrome 34, unfortunately, will try to autofill fields with user/pass whenever it sees a password field. This is quite a bad bug that hopefully, they will change the Safari behavior. However, adding this to the top of your form seems to disable the password autofill:

    <input type="text" style="display:none">
    <input type="password" style="display:none">

I haven't yet investigated IE or Firefox thoroughly but will be happy to update the answer if others have info in the comments.

How to draw interactive Polyline on route google maps v2 android

You should use options.addAll(allPoints); instead of options.add(point);

Best way to remove items from a collection

If RoleAssignments is a List<T> you can use the following code.

workSpace.RoleAssignments.RemoveAll(x =>x.Member.Name == shortName);

How to change the icon of .bat file programmatically?

try with shortcutjs.bat to create a shortcut:

call shortcutjs.bat -linkfile mybat3.lnk -target "%cd%\Ascii2All.bat" -iconlocation "%SystemRoot%\System32\SHELL32.dll,77"

you can use the -iconlocation switch to point to a icon .

Target WSGI script cannot be loaded as Python module

As this question became sort of a pool for collecting solutions for problems that result in the error giving this question its title, I'd like to add this one, too.

In my case, I want to run OpenStack Keystone (Ocata) using Apache and WSGI on Ubuntu 16.04.2. The processes start but as soon as I query keystone I get

mod_wsgi (pid=20103): Target WSGI script '/opt/openstack/bin/keystone-wsgi-public' cannot be loaded as Python module.

I had two vhosts, one had

WSGIDaemonProcess keystone-public ...
WSGIProcessGroup keystone-public ...

while the other had

WSGIDaemonProcess keystone-admin ...
WSGIProcessGroup keystone-admin ...

I solved the problem by renaming them. The vhost entries now read:

WSGIDaemonProcess kst-pub ...
WSGIProcessGroup kst-pub ...


WSGIDaemonProcess kst-adm ...
WSGIProcessGroup kst-adm ...

I didn't investigate any further. Solved as works for me.

List of Stored Procedures/Functions Mysql Command Line

For view procedure in name wise

select name from mysql.proc 

below code used to list all the procedure and below code is give same result as show procedure status

select * from mysql.proc 

How to print the contents of RDD?

There are probably many architectural differences between myRDD.foreach(println) and myRDD.collect().foreach(println) (not only 'collect', but also other actions). One the differences I saw is when doing myRDD.foreach(println), the output will be in a random order. For ex: if my rdd is coming from a text file where each line has a number, the output will have a different order. But when I did myRDD.collect().foreach(println), order remains just like the text file.

Make more than one chart in same IPython Notebook cell

Another way, for variety. Although this is somewhat less flexible than the others. Unfortunately, the graphs appear one above the other, rather than side-by-side, which you did request in your original question. But it is very concise.


If the dataframe has more than the two series, and you only want to plot those two, you'll need to replace df with df[['korisnika','osiguranika']].

How to define servlet filter order of execution using annotations in WAR

  1. Make the servlet filter implement the spring Ordered interface.
  2. Declare the servlet filter bean manually in configuration class.
    import org.springframework.core.Ordered;
    public class MyFilter implements Filter, Ordered {

        public void init(FilterConfig filterConfig) {
            // do something

        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            // do something

        public void destroy() {
            // do something

        public int getOrder() {
            return -100;

    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;

    public class MyAutoConfiguration {

        public MyFilter myFilter() {
            return new MyFilter();

CSS Box Shadow - Top and Bottom Only

essentially the shadow is the box shape just offset behind the actual box. in order to hide portions of the shadow, you need to create additional divs and set their z-index above the shadowed box so that the shadow is not visible.

If you'd like to have extremely specific control over your shadows, build them as images and created container divs with the right amount of padding and margins.. then use the png fix to make sure the shadows render properly in all browsers

How to hide columns in an ASP.NET GridView with auto-generated columns?

Note: This solution only works if your GridView columns are known ahead of time.

It sounds like you're using a GridView with AutoGenerateColumns=true, which is the default. I recommend setting AutoGenerateColumns=false and adding the columns manually:

<asp:GridView runat="server" ID="MyGridView"
    AutoGenerateColumns="false" DataSourceID="MySqlDataSource">
        <asp:BoundField DataField="Column1" />
        <asp:BoundField DataField="Column2" />
        <asp:BoundField DataField="Column3" />

And only include a BoundField for each field that you want to be displayed. This will give you the most flexibility in terms of how the data gets displayed.

Linq to SQL how to do "where [column] in (list of values)"

 var filterTransNos = (from so in db.SalesOrderDetails
                    where  ItemDescription.Contains(ItemDescription)
                            select new { so.TransNo }).AsEnumerable();    

listreceipt = listreceipt.Where(p => filterTransNos.Any(p2 => p2.TransNo == p.TransNo)).ToList();

How to create exe of a console application

The following steps are necessary to create .exe i.e. executable files which are as 1) Open visual studio framework 2) Then, create a new project or application 3) Build or execute your application by pressing F5

How do I execute a command and get the output of the command within C++ using POSIX?

I'd use popen() (++waqas).

But sometimes you need reading and writing...

It seems like nobody does things the hard way any more.

(Assuming a Unix/Linux/Mac environment, or perhaps Windows with a POSIX compatibility layer...)

  READ_FD  = 0,
  WRITE_FD = 1


  int       parentToChild[2];
  int       childToParent[2];
  pid_t     pid;
  string    dataReadFromChild;
  char      buffer[BUFFER_SIZE + 1];
  ssize_t   readResult;
  int       status;

  ASSERT_IS(0, pipe(parentToChild));
  ASSERT_IS(0, pipe(childToParent));

  switch (pid = fork())
    case -1:
      FAIL("Fork failed");

    case 0: /* Child */
      ASSERT_NOT(-1, dup2(parentToChild[READ_FD], STDIN_FILENO));
      ASSERT_NOT(-1, dup2(childToParent[WRITE_FD], STDOUT_FILENO));
      ASSERT_NOT(-1, dup2(childToParent[WRITE_FD], STDERR_FILENO));
      ASSERT_IS(0, close(parentToChild [WRITE_FD]));
      ASSERT_IS(0, close(childToParent [READ_FD]));

      /*     file, arg0, arg1,  arg2 */
      execlp("ls", "ls", "-al", "--color");

      FAIL("This line should never be reached!!!");

    default: /* Parent */
      cout << "Child " << pid << " process running..." << endl;

      ASSERT_IS(0, close(parentToChild [READ_FD]));
      ASSERT_IS(0, close(childToParent [WRITE_FD]));

      while (true)
        switch (readResult = read(childToParent[READ_FD],
                                  buffer, BUFFER_SIZE))
          case 0: /* End-of-File, or non-blocking read. */
            cout << "End of file reached..."         << endl
                 << "Data received was ("
                 << dataReadFromChild.size() << "): " << endl
                 << dataReadFromChild                << endl;

            ASSERT_IS(pid, waitpid(pid, & status, 0));

            cout << endl
                 << "Child exit staus is:  " << WEXITSTATUS(status) << endl
                 << endl;


          case -1:
            if ((errno == EINTR) || (errno == EAGAIN))
              errno = 0;
              FAIL("read() failed");

            dataReadFromChild . append(buffer, readResult);
      } /* while (true) */
  } /* switch (pid = fork())*/

You also might want to play around with select() and non-blocking reads.

fd_set          readfds;
struct timeval  timeout;

timeout.tv_sec  = 0;    /* Seconds */
timeout.tv_usec = 1000; /* Microseconds */

FD_SET(childToParent[READ_FD], &readfds);

switch (select (1 + childToParent[READ_FD], &readfds, (fd_set*)NULL, (fd_set*)NULL, & timeout))
  case 0: /* Timeout expired */

  case -1:
    if ((errno == EINTR) || (errno == EAGAIN))
      errno = 0;
      FAIL("Select() Failed");

  case 1:  /* We have input */
    readResult = read(childToParent[READ_FD], buffer, BUFFER_SIZE);
    // However you want to handle it...

    FAIL("How did we see input on more than one file descriptor?");

Override body style for content in an iframe

This code uses vanilla JavaScript. It creates a new <style> element. It sets the text content of that element to be a string containing the new CSS. And it appends that element directly to the iframe document's head.

Keep in mind, however, that accessing elements of a document loaded from another origin is not permitted (for security reasons) -- contentDocument of the iframe element will evaluate to null when attempted from the browsing context of the page embedding the frame.

var iframe = document.getElementById('the-iframe');
var style = document.createElement('style');
style.textContent =
  'body {' +
  '  background-color: some-color;' +
  '  background-image: some-image;' +

Exception in thread "main" java.lang.Error: Unresolved compilation problems

For this error:

Exception in thread "main" java.lang.Error: Unresolved compilation problems:

There are problems with your import or package name.
You can delete the package name or fix import errors

NameError: global name is not defined

You need to do:

import sqlitedbx

def main():
    db = sqlitedbx.SqliteDBzz()

if __name__ == "__main__":

Global constants file in Swift

What I did in my Swift project
1: Create new Swift File
2: Create a struct and static constant in it.
3: For Using just use YourStructName.baseURL

Note: After Creating initialisation takes little time so it will show in other viewcontrollers after 2-5 seconds.

import Foundation

    struct YourStructName {
    static let MerchantID = "XXX"
    static let MerchantUsername = "XXXXX"
    static let ImageBaseURL = "XXXXXXX"
    static let baseURL = "XXXXXXX"

SqlException: DB2 SQL error: SQLCODE: -302, SQLSTATE: 22001, SQLERRMC: null

As a general point when using a search engine to search for SQL codes make sure you put the sqlcode e.g. -302 in quote marks - like "-302" otherwise the search engine will exclude all search results including the text 302, since the - sign is used to exclude results.

SQL 'LIKE' query using '%' where the search criteria contains '%'

The easiest solution is to dispense with "like" altogether:

Select * 
from table
where charindex(search_criteria, name) > 0

I prefer charindex over like. Historically, it had better performance, but I'm not sure if it makes much of difference now.

Using "Object.create" instead of "new"

I prefer a closure approach.

I still use new. I don't use Object.create. I don't use this.

I still use new as I like the declarative nature of it.

Consider this for simple inheritance.

window.Quad = (function() {

    function Quad() {

        const wheels = 4;
        const drivingWheels = 2;

        let motorSize = 0;

        function setMotorSize(_) {
            motorSize = _;

        function getMotorSize() {
            return motorSize;

        function getWheelCount() {
            return wheels;

        function getDrivingWheelCount() {
            return drivingWheels;
        return Object.freeze({

    return Object.freeze(Quad);

window.Car4wd = (function() {

    function Car4wd() {
        const quad = new Quad();

        const spareWheels = 1;
        const extraDrivingWheels = 2;

        function getSpareWheelCount() {
            return spareWheels;

        function getDrivingWheelCount() {
            return quad.getDrivingWheelCount() + extraDrivingWheels;

        return Object.freeze(Object.assign({}, quad, {

    return Object.freeze(Car4wd);

let myQuad = new Quad();
let myCar = new Car4wd();
console.log(myQuad.getWheelCount()); // 4
console.log(myQuad.getDrivingWheelCount()); // 2
console.log(myCar.getWheelCount()); // 4
console.log(myCar.getDrivingWheelCount()); // 4 - The overridden method is called
console.log(myCar.getSpareWheelCount()); // 1

Feedback encouraged.

"date(): It is not safe to rely on the system's timezone settings..."

There are two options for the resolve this

First, change into the php.ini file and put default timezone

date.timezone = "America/New_York"

Once, you have set the timezone in php.ini restart the server

Secondly, Change the run time assign time zone based on your need


Entity Framework Queryable async

The problem seems to be that you have misunderstood how async/await work with Entity Framework.

About Entity Framework

So, let's look at this code:

public IQueryable<URL> GetAllUrls()
    return context.Urls.AsQueryable();

and example of it usage:

repo.GetAllUrls().Where(u => <condition>).Take(10).ToList()

What happens there?

  1. We are getting IQueryable object (not accessing database yet) using repo.GetAllUrls()
  2. We create a new IQueryable object with specified condition using .Where(u => <condition>
  3. We create a new IQueryable object with specified paging limit using .Take(10)
  4. We retrieve results from database using .ToList(). Our IQueryable object is compiled to sql (like select top 10 * from Urls where <condition>). And database can use indexes, sql server send you only 10 objects from your database (not all billion urls stored in database)

Okay, let's look at first code:

public async Task<IQueryable<URL>> GetAllUrlsAsync()
    var urls = await context.Urls.ToListAsync();
    return urls.AsQueryable();

With the same example of usage we got:

  1. We are loading in memory all billion urls stored in your database using await context.Urls.ToListAsync();.
  2. We got memory overflow. Right way to kill your server

About async/await

Why async/await is preferred to use? Let's look at this code:

var stuff1 = repo.GetStuff1ForUser(userId);
var stuff2 = repo.GetStuff2ForUser(userId);
return View(new Model(stuff1, stuff2));

What happens here?

  1. Starting on line 1 var stuff1 = ...
  2. We send request to sql server that we want to get some stuff1 for userId
  3. We wait (current thread is blocked)
  4. We wait (current thread is blocked)
  5. .....
  6. Sql server send to us response
  7. We move to line 2 var stuff2 = ...
  8. We send request to sql server that we want to get some stuff2 for userId
  9. We wait (current thread is blocked)
  10. And again
  11. .....
  12. Sql server send to us response
  13. We render view

So let's look to an async version of it:

var stuff1Task = repo.GetStuff1ForUserAsync(userId);
var stuff2Task = repo.GetStuff2ForUserAsync(userId);
await Task.WhenAll(stuff1Task, stuff2Task);
return View(new Model(stuff1Task.Result, stuff2Task.Result));

What happens here?

  1. We send request to sql server to get stuff1 (line 1)
  2. We send request to sql server to get stuff2 (line 2)
  3. We wait for responses from sql server, but current thread isn't blocked, he can handle queries from another users
  4. We render view

Right way to do it

So good code here:

using System.Data.Entity;

public IQueryable<URL> GetAllUrls()
   return context.Urls.AsQueryable();

public async Task<List<URL>> GetAllUrlsByUser(int userId) {
   return await GetAllUrls().Where(u => u.User.Id == userId).ToListAsync();

Note, than you must add using System.Data.Entity in order to use method ToListAsync() for IQueryable.

Note, that if you don't need filtering and paging and stuff, you don't need to work with IQueryable. You can just use await context.Urls.ToListAsync() and work with materialized List<Url>.

How to create unique keys for React elements?

Keys helps React identify which items have changed/added/removed and should be given to the elements inside the array to give the elements a stable identity.

With that in mind, there are basically three different strategies as described bellow:

  1. Static Elements (when you don't need to keep html state (focus, cursor position, etc)
  2. Editable and sortable elements
  3. Editable but not sortable elements

As React Documentation explains, we need to give stable identity to the elements and because of that, carefully choose the strategy that best suits your needs:


As we can see also in React Documentation, is not recommended the use of index for keys "if the order of items may change. This can negatively impact performance and may cause issues with component state".

In case of static elements like tables, lists, etc, I recommend using a tool called shortid.

1) Install the package using NPM/YARN:

npm install shortid --save

2) Import in the class file you want to use it:

import shortid from 'shortid';

2) The command to generate a new id is shortid.generate().

3) Example:

  renderDropdownItems = (): React.ReactNode => {
    const { data, isDisabled } = this.props;
    const { selectedValue } = this.state;
    const dropdownItems: Array<React.ReactNode> = [];

    if (data) {
      data.forEach(item => {
          <option value={item.value} key={shortid.generate()}>

    return (

IMPORTANT: As React Virtual DOM relies on the key, with shortid every time the element is re-rendered a new key will be created and the element will loose it's html state like focus or cursor position. Consider this when deciding how the key will be generated as the strategy above can be useful only when you are building elements that won't have their values changed like lists or read only fields.


If the element is sortable and you have a unique ID of the item, combine it with some extra string (in case you need to have the same information twice in a page). This is the most recommended scenario.


  renderDropdownItems = (): React.ReactNode => {
    const elementKey:string = 'ddownitem_'; 
    const { data, isDisabled } = this.props;
    const { selectedValue } = this.state;
    const dropdownItems: Array<React.ReactNode> = [];

    if (data) {
      data.forEach(item => {
          <option value={item.value} key={${elementKey}${}}>

    return (


As a last resort, for editable (but non sortable) fields like input, you can use some the index with some starting text as element key cannot be duplicated.


  renderDropdownItems = (): React.ReactNode => {
    const elementKey:string = 'ddownitem_'; 
    const { data, isDisabled } = this.props;
    const { selectedValue } = this.state;
    const dropdownItems: Array<React.ReactNode> = [];

    if (data) {
      data.forEach((item:any index:number) => {
          <option value={item.value} key={${elementKey}${index}}>

    return (

Hope this helps.

How to print in C

The first argument to printf() is always a string value, known as a format control string. This string may be regular text, such as

printf("Hello, World\n"); // \n indicates a newline character


char greeting[] = "Hello, World\n";

This string may also contain one or more conversion specifiers; these conversion specifiers indicate that additional arguments have been passed to printf(), and they specify how to format those arguments for output. For example, I can change the above to

char greeting[] = "Hello, World";
printf("%s\n", greeting);

The "%s" conversion specifier expects a pointer to a 0-terminated string, and formats it as text.

For signed decimal integer output, use either the "%d" or "%i" conversion specifiers, such as

printf("%d\n", addNumber(a,b));

You can mix regular text with conversion specifiers, like so:

printf("The result of addNumber(%d, %d) is %d\n", a, b, addNumber(a,b));

Note that the conversion specifiers in the control string indicate the number and types of additional parameters. If the number or types of additional arguments passed to printf() don't match the conversion specifiers in the format string then the behavior is undefined. For example:

printf("The result of addNumber(%d, %d) is %d\n", addNumber(a,b));

will result in anything from garbled output to an outright crash.

There are a number of additional flags for conversion specifiers that control field width, precision, padding, justification, and types. Check your handy C reference manual for a complete listing.

Microsoft Visual C++ Compiler for Python 3.4

For the different python versions:

Visual C++ |CPython
14.0       |3.5
10.0       |3.3, 3.4
9.0        |2.6, 2.7, 3.0, 3.1, 3.2

Source: Windows Compilers for py

Also refer: this answer

What Content-Type value should I send for my XML sitemap?

text/xml is for documents that would be meaningful to a human if presented as text without further processing, application/xml is for everything else

Every XML entity is suitable for use with the application/xml media type without modification. But this does not exploit the fact that XML can be treated as plain text in many cases. MIME user agents (and web user agents) that do not have explicit support for application/xml will treat it as application/octet-stream, for example, by offering to save it to a file.

To indicate that an XML entity should be treated as plain text by default, use the text/xml media type. This restricts the encoding used in the XML entity to those that are compatible with the requirements for text media types as described in [RFC-2045] and [RFC-2046], e.g., UTF-8, but not UTF-16 (except for HTTP).

Should a RESTful 'PUT' operation return something

Just as an empty Request body is in keeping with the original purpose of a GET request and empty response body is in keeping with the original purpose of a PUT request.

Removing character in list of strings

A faster way is to join the list, replace 8 and split the new string:

mylist = [("aaaa8"),("bb8"),("ccc8"),("dddddd8")]
mylist = ' '.join(mylist).replace('8','').split()
print mylist

JSONResult to String

You're looking for the JavaScriptSerializer class, which is used internally by JsonResult:

string json = new JavaScriptSerializer().Serialize(jsonResult.Data);


select from_unixtime(column,'%Y-%m-%d') from myTable; 

Performing a Stress Test on Web Application?

There are a lot of good tools mentioned here. I wonder if tools are an answer the question: "How do you stress test a web application?" The tools don't really provide a method to stress a Web app. Here's what I know:

Stress testing shows how a Web app fails while serving responses to an increasing population of users. Stress testing shows how the Web app functions while it fails. Most Web apps today - especially the Social/Mobile Web apps - are integrations of services. For example, when Facebook had its outage in May 2011 you could not log onto's Web app. The app didn't fail entirely, just a big portion of its normal function become unavailable to users.

Performance testing shows a Web app's ability to maintain response times independent of how many users are concurrently using the app. For example, an app that handles 10 transactions per second with 10 concurrent users should handle 20 transactions per second at 20 users. If the app handles less than 20 transactions per second the response times are growing longer and the app is not able to achieve linear scalability.

Also, in the above example the transaction-per-second count should be of only successful operations of a test use case/workflow. Failures typically happen in shorter timespans and will make the TPS measurement overly optimistic. Failures are important to a stress and performance test since they generate load on the app too.

I wrote up the PushToTest methodology in the TestMaker User Guide at TestMaker comes in two flavors: Open Source (GPL) Community version and TestMaker Enterprise (commercial with great professional support.)


How to concatenate variables into SQL strings

You can accomplish this (if I understand what you are trying to do) using dynamic SQL.

The trick is that you need to create a string containing the SQL statement. That's because the tablename has to specified in the actual SQL text, when you execute the statement. The table references and column references can't be supplied as parameters, those have to appear in the SQL text.

So you can use something like this approach:

SET @stmt = 'INSERT INTO @tmpTbl1 SELECT ' + @KeyValue 
    + ' AS fld1 FROM tbl' + @KeyValue

EXEC (@stmt)

First, we create a SQL statement as a string. Given a @KeyValue of 'Foo', that would create a string containing:

'INSERT INTO @tmpTbl1 SELECT Foo AS fld1 FROM tblFoo'

At this point, it's just a string. But we can execute the contents of the string, as a dynamic SQL statement, using EXECUTE (or EXEC for short).

The old-school sp_executesql procedure is an alternative to EXEC, another way to execute dymamic SQL, which also allows you to pass parameters, rather than specifying all values as literals in the text of the statement.


EBarr points out (correctly and importantly) that this approach is susceptible to SQL Injection.

Consider what would happen if @KeyValue contained the string:

'1 AS foo; DROP TABLE students; -- '

The string we would produce as a SQL statement would be:

'INSERT INTO @tmpTbl1 SELECT 1 AS foo; DROP TABLE students; -- AS fld1 ...'

When we EXECUTE that string as a SQL statement:

DROP TABLE students;
-- AS fld1 FROM tbl1 AS foo; DROP ...

And it's not just a DROP TABLE that could be injected. Any SQL could be injected, and it might be much more subtle and even more nefarious. (The first attacks can be attempts to retreive information about tables and columns, followed by attempts to retrieve data (email addresses, account numbers, etc.)

One way to address this vulnerability is to validate the contents of @KeyValue, say it should contain only alphabetic and numeric characters (e.g. check for any characters not in those ranges using LIKE '%[^A-Za-z0-9]%'. If an illegal character is found, then reject the value, and exit without executing any SQL.

Vlookup referring to table data in a different sheet

Copy =VLOOKUP(M3,A$2:Q$47,13,FALSE) to other sheets, then search for ! replace by !$, search for : replace by :$ one time for all sheets

increase font size of hyperlink text html

There is a way simpler way. You put the href in a paragraph just created for that href. For example:

HREF name

Nginx serves .php files as downloads, instead of executing them

The answer above seemed to comment out too much for the solution I reached. This is what my file looked like:


location ~ \.php$ {
# fastcgi_split_path_info ^(.+\.php)(/.+)$;
# # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
# # With php5-cgi alone:
# fastcgi_pass;
# With php5-fpm:
fastcgi_pass unix:/var/run/php5-fpm.sock;
fastcgi_index index.php;
include fastcgi_params;

Hope this helps some folks who are frustrated on a sunday afternoon (c:

Open PDF in new browser full window

To do it from a Base64 encoding you can use the following function:

function base64ToArrayBuffer(data) {
  const bString = window.atob(data);
  const bLength = bString.length;
  const bytes = new Uint8Array(bLength);
  for (let i = 0; i < bLength; i++) {
      bytes[i] = bString.charCodeAt(i);
  return bytes;
function base64toPDF(base64EncodedData, fileName = 'file') {
  const bufferArray = base64ToArrayBuffer(base64EncodedData);
  const blobStore = new Blob([bufferArray], { type: 'application/pdf' });
  if (window.navigator && window.navigator.msSaveOrOpenBlob) {
  const data = window.URL.createObjectURL(blobStore);
  const link = document.createElement('a');
  link.href = data; = `${fileName}.pdf`;;

Mutex example / tutorial?

You are supposed to check the mutex variable before using the area protected by the mutex. So your pthread_mutex_lock() could (depending on implementation) wait until mutex1 is released or return a value indicating that the lock could not be obtained if someone else has already locked it.

Mutex is really just a simplified semaphore. If you read about them and understand them, you understand mutexes. There are several questions regarding mutexes and semaphores in SO. Difference between binary semaphore and mutex, When should we use mutex and when should we use semaphore and so on. The toilet example in the first link is about as good an example as one can think of. All code does is to check if the key is available and if it is, reserves it. Notice that you don't really reserve the toilet itself, but the key.

How do you use math.random to generate random ints?

double  i = 2+Math.random()*100;
int j = (int)i;

How to filter specific apps for ACTION_SEND intent (and set a different text for each app)

To my knowledge, StackOverflow has lots of people asking this question in various ways, but nobody has answered it completely yet.

My spec called for the user to be able to choose email, twitter, facebook, or SMS, with custom text for each one. Here is how I accomplished that:

public void onShareClick(View v) {
    Resources resources = getResources();

    Intent emailIntent = new Intent();
    // Native email client doesn't currently support HTML, but it doesn't hurt to try in case they fix it
    emailIntent.putExtra(Intent.EXTRA_TEXT, Html.fromHtml(resources.getString(R.string.share_email_native)));
    emailIntent.putExtra(Intent.EXTRA_SUBJECT, resources.getString(R.string.share_email_subject));

    PackageManager pm = getPackageManager();
    Intent sendIntent = new Intent(Intent.ACTION_SEND);     

    Intent openInChooser = Intent.createChooser(emailIntent, resources.getString(R.string.share_chooser_text));

    List<ResolveInfo> resInfo = pm.queryIntentActivities(sendIntent, 0);
    List<LabeledIntent> intentList = new ArrayList<LabeledIntent>();        
    for (int i = 0; i < resInfo.size(); i++) {
        // Extract the label, append it, and repackage it in a LabeledIntent
        ResolveInfo ri = resInfo.get(i);
        String packageName = ri.activityInfo.packageName;
        if(packageName.contains("")) {
        } else if(packageName.contains("twitter") || packageName.contains("facebook") || packageName.contains("mms") || packageName.contains("")) {
            Intent intent = new Intent();
            intent.setComponent(new ComponentName(packageName,;
            if(packageName.contains("twitter")) {
                intent.putExtra(Intent.EXTRA_TEXT, resources.getString(R.string.share_twitter));
            } else if(packageName.contains("facebook")) {
                // Warning: Facebook IGNORES our text. They say "These fields are intended for users to express themselves. Pre-filling these fields erodes the authenticity of the user voice."
                // One workaround is to use the Facebook SDK to post, but that doesn't allow the user to choose how they want to share. We can also make a custom landing page, and the link
                // will show the <meta content ="..."> text from that page with our link in Facebook.
                intent.putExtra(Intent.EXTRA_TEXT, resources.getString(R.string.share_facebook));
            } else if(packageName.contains("mms")) {
                intent.putExtra(Intent.EXTRA_TEXT, resources.getString(R.string.share_sms));
            } else if(packageName.contains("")) { // If Gmail shows up twice, try removing this else-if clause and the reference to "" above
                intent.putExtra(Intent.EXTRA_TEXT, Html.fromHtml(resources.getString(R.string.share_email_gmail)));
                intent.putExtra(Intent.EXTRA_SUBJECT, resources.getString(R.string.share_email_subject));               

            intentList.add(new LabeledIntent(intent, packageName, ri.loadLabel(pm), ri.icon));

    // convert intentList to array
    LabeledIntent[] extraIntents = intentList.toArray( new LabeledIntent[ intentList.size() ]);

    openInChooser.putExtra(Intent.EXTRA_INITIAL_INTENTS, extraIntents);

I found bits of how to do this in various places, but I haven't seen all of it in one place anywhere else.

Note that this method also hides all the silly options that I don't want, like sharing over wifi and bluetooth.

Hope this helps someone.

Edit: In a comment, I was asked to explain what this code is doing. Basically, it's creating an ACTION_SEND intent for the native email client ONLY, then tacking other intents onto the chooser. Making the original intent email-specific gets rid of all the extra junk like wifi and bluetooth, then I grab the other intents I want from a generic ACTION_SEND of type plain-text, and tack them on before showing the chooser.

When I grab the additional intents, I set custom text for each one.

Edit2: It's been awhile since I posted this, and things have changed a bit. If you are seeing gmail twice in the list of options, try removing the special handling for "" as suggested in a comment by @h_k below.

Since this one answer is the source of nearly all my stackoverflow reputation points, I have to at least try to keep it up to date.

How to turn off gcc compiler optimization to enable buffer overflow

I won't quote the entire page but the whole manual on optimisation is available here:

From the sounds of it you want at least -O0, the default, and:

-fmudflap -fmudflapth -fmudflapir

For front-ends that support it (C and C++), instrument all risky pointer/array dereferencing operations, some standard library string/heap functions, and some other associated constructs with range/validity tests. Modules so instrumented should be immune to buffer overflows, invalid heap use, and some other classes of C/C++ programming errors. The instrumentation relies on a separate runtime library (libmudflap), which will be linked into a program if -fmudflap is given at link time. Run-time behavior of the instrumented program is controlled by the MUDFLAP_OPTIONS environment variable. See env MUDFLAP_OPTIONS=-help a.out for its options.

Select Multiple Fields from List in Linq

public class Student
    public string Name { set; get; }
    public int ID { set; get; }

class Program
  static void Main(string[] args)
        Student[] students =
        new Student { Name="zoyeb" , ID=1},
        new Student { Name="Siddiq" , ID=2},
        new Student { Name="sam" , ID=3},
        new Student { Name="james" , ID=4},
        new Student { Name="sonia" , ID=5}

        var studentCollection = from s in students select new { s.ID , s.Name};

        foreach (var student in studentCollection)

Codeigniter displays a blank page instead of error messages

Often when codeigniter displays nothing, there is a syntax error. Mostly if the app was running seamlessly previously, just look around your most recent edits. For me the experience this time was the entire app, not just a page. So I did a quick brain scan for the most recent edits I had done and worked backwards, reviewing each file I had worked on this day. Turned out to be some 'where' clauses in two model files: For instance, I had

$this->db->where('Type' => 'Blog'); rather than $this->db->where('Type', 'Blog');

Access-control-allow-origin with multiple domains

There can only be one Access-Control-Allow-Origin response header, and that header can only have one origin value. Therefore, in order to get this to work, you need to have some code that:

  1. Grabs the Origin request header.
  2. Checks if the origin value is one of the whitelisted values.
  3. If it is valid, sets the Access-Control-Allow-Origin header with that value.

I don't think there's any way to do this solely through the web.config.

if (ValidateRequest()) {
    Response.AddHeader("Access-Control-Allow-Origin", Request.UrlReferrer.GetLeftPart(UriPartial.Authority));

    Response.AddHeader("Access-Control-Allow-Credentials", "true");

    Response.AddHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");

Detect key input in Python

use the builtin: (no need for tkinter)

s = input('->>')
print(s) # what you just typed); now use if's 

Calculate age given the birth date in the format YYYYMMDD

Try this:


var $bef = $('#Datepicker').val();
var $today = new Date();
var $before = new Date($bef);
var $befores = $before.getFullYear();
var $todays = $today.getFullYear();
var $bmonth = $before.getMonth();
var $tmonth = $today.getMonth();
var $bday = $before.getDate();
var $tday = $today.getDate();

if ($bmonth>$tmonth)

if ($bmonth==$tmonth)
if ($tday > $bday) {$('#age').val($todays-$befores-1);}
else if ($tday <= $bday) {$('#age').val($todays-$befores);}
else if ($bmonth<$tmonth)
{ $('#age').val($todays-$befores-1);} 

See changes to a specific file using git

you can also try

git show <filename>

For commits, git show will show the log message and textual diff (between your file and the commited version of the file).

You can check git show Documentation for more info.

Failed to build gem native extension (installing Compass)


gem install overcommit

is run also this error have been placed in terminal.

Failed to build gem native extension

please do the same

xcode-select --install

and it will fix that issue too

How to implement a custom AlertDialog View

Custom AlertDialog

This full example includes passing data back to the Activity.

enter image description here

Create a custom layout

A layout with an EditText is used for this simple example, but you can replace it with anything you like.


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""



Use the dialog in code

The key parts are

  • using setView to assign the custom layout to the AlertDialog.Builder
  • sending any data back to the activity when a dialog button is clicked.

This is the full code from the example project shown in the image above:

public class MainActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {

    public void showAlertDialogButtonClicked(View view) {

        // create an alert builder
        AlertDialog.Builder builder = new AlertDialog.Builder(this);

        // set the custom layout
        final View customLayout = getLayoutInflater().inflate(R.layout.custom_layout, null);

        // add a button
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                // send data from the AlertDialog to the Activity
                EditText editText = customLayout.findViewById(;

        // create and show the alert dialog
        AlertDialog dialog = builder.create();;

    // do something with the data coming from the AlertDialog
    private void sendDialogDataToActivity(String data) {
        Toast.makeText(this, data, Toast.LENGTH_SHORT).show();


  • If you find yourself using this in multiple places, then consider making a DialogFragment subclass as is described in the documentation.

See also

Message Queue vs. Web Services?

I think in general, you'd want a web service for a blocking task (this tasks needs to be completed before we execute more code), and a message queue for a non-blocking task (could take quite a while, but we don't need to wait for it).

casting Object array to Integer array error

You can't cast an Object array to an Integer array. You have to loop through all elements of a and cast each one individually.

Object[] a = new Object[1];
Integer b=1;
Integer[] c = new Integer[a.length];
for(int i = 0; i < a.length; i++)
    c[i] = (Integer) a[i];

Edit: I believe the rationale behind this restriction is that when casting, the JVM wants to ensure type-safety at runtime. Since an array of Objects can be anything besides Integers, the JVM would have to do what the above code is doing anyway (look at each element individually). The language designers decided they didn't want the JVM to do that (I'm not sure why, but I'm sure it's a good reason).

However, you can cast a subtype array to a supertype array (e.g. Integer[] to Object[])!

Encrypt and decrypt a string in C#?

Copied in my answer here from a similar question: Simple two-way encryption for C#.

Based on multiple answers and comments.

  • Random initialization vector prepended to crypto text (@jbtule)
  • Use TransformFinalBlock() instead of MemoryStream (@RenniePet)
  • No pre-filled keys to avoid anyone copy & pasting a disaster
  • Proper dispose and using patterns


/// <summary>
/// Simple encryption/decryption using a random initialization vector
/// and prepending it to the crypto text.
/// </summary>
/// <remarks>Based on multiple answers in </remarks>
public class SimpleAes : IDisposable
    /// <summary>
    ///     Initialization vector length in bytes.
    /// </summary>
    private const int IvBytes = 16;

    /// <summary>
    ///     Must be exactly 16, 24 or 32 characters long.
    /// </summary>
    private static readonly byte[] Key = Convert.FromBase64String("FILL ME WITH 16, 24 OR 32 CHARS");

    private readonly UTF8Encoding _encoder;
    private readonly ICryptoTransform _encryptor;
    private readonly RijndaelManaged _rijndael;

    public SimpleAes()
        _rijndael = new RijndaelManaged {Key = Key};
        _encryptor = _rijndael.CreateEncryptor();
        _encoder = new UTF8Encoding();

    public string Decrypt(string encrypted)
        return _encoder.GetString(Decrypt(Convert.FromBase64String(encrypted)));

    public void Dispose()

    public string Encrypt(string unencrypted)
        return Convert.ToBase64String(Encrypt(_encoder.GetBytes(unencrypted)));

    private byte[] Decrypt(byte[] buffer)
        // IV is prepended to cryptotext
        byte[] iv = buffer.Take(IvBytes).ToArray();
        using (ICryptoTransform decryptor = _rijndael.CreateDecryptor(_rijndael.Key, iv))
            return decryptor.TransformFinalBlock(buffer, IvBytes, buffer.Length - IvBytes);

    private byte[] Encrypt(byte[] buffer)
        // Prepend cryptotext with IV
        byte[] inputBuffer = _rijndael.IV.Concat(buffer).ToArray();
        return _encryptor.TransformFinalBlock(inputBuffer, IvBytes, buffer.Length);

Rotating and spacing axis labels in ggplot2

An alternative to coord_flip() is to use the ggstance package. The advantage is that it makes it easier to combine the graphs with other graph types and you can, maybe more importantly, set fixed scale ratios for your coordinate system.


diamonds$cut <- paste("Super Dee-Duper", as.character(diamonds$cut))

ggplot(data=diamonds, aes(carat, cut)) + geom_boxploth()

Created on 2020-03-11 by the reprex package (v0.3.0)

What is the maximum possible length of a query string?

RFC 2616 (Hypertext Transfer Protocol — HTTP/1.1) states there is no limit to the length of a query string (section 3.2.1). RFC 3986 (Uniform Resource Identifier — URI) also states there is no limit, but indicates the hostname is limited to 255 characters because of DNS limitations (section 2.3.3).

While the specifications do not specify any maximum length, practical limits are imposed by web browser and server software. Based on research which is unfortunately no longer available on its original site (it leads to a shady seeming loan site) but which can still be found at Internet Archive Of

  • Microsoft Internet Explorer (Browser)
    Microsoft states that the maximum length of a URL in Internet Explorer is 2,083 characters, with no more than 2,048 characters in the path portion of the URL. Attempts to use URLs longer than this produced a clear error message in Internet Explorer.

  • Microsoft Edge (Browser)
    The limit appears to be around 81578 characters. See URL Length limitation of Microsoft Edge

  • Chrome
    It stops displaying the URL after 64k characters, but can serve more than 100k characters. No further testing was done beyond that.

  • Firefox (Browser)
    After 65,536 characters, the location bar no longer displays the URL in Windows Firefox 1.5.x. However, longer URLs will work. No further testing was done after 100,000 characters.

  • Safari (Browser)
    At least 80,000 characters will work. Testing was not tried beyond that.

  • Opera (Browser)
    At least 190,000 characters will work. Stopped testing after 190,000 characters. Opera 9 for Windows continued to display a fully editable, copyable and pasteable URL in the location bar even at 190,000 characters.

  • Apache (Server)
    Early attempts to measure the maximum URL length in web browsers bumped into a server URL length limit of approximately 4,000 characters, after which Apache produces a "413 Entity Too Large" error. The current up to date Apache build found in Red Hat Enterprise Linux 4 was used. The official Apache documentation only mentions an 8,192-byte limit on an individual field in a request.

  • Microsoft Internet Information Server (Server)
    The default limit is 16,384 characters (yes, Microsoft's web server accepts longer URLs than Microsoft's web browser). This is configurable.

  • Perl HTTP::Daemon (Server)
    Up to 8,000 bytes will work. Those constructing web application servers with Perl's HTTP::Daemon module will encounter a 16,384 byte limit on the combined size of all HTTP request headers. This does not include POST-method form data, file uploads, etc., but it does include the URL. In practice this resulted in a 413 error when a URL was significantly longer than 8,000 characters. This limitation can be easily removed. Look for all occurrences of 16x1024 in and replace them with a larger value. Of course, this does increase your exposure to denial of service attacks.

How to show "Done" button on iPhone number pad

The solution in UIKeyboardTypeNumberPad and missing return key works great but only if there are no other non-number pad text fields on the screen.

I took that code and turned it into an UIViewController that you can simply subclass to make number pads work. You will need to get the icons from the above link.


#import <UIKit/UIKit.h>

@interface NumberPadViewController : UIViewController {
    UIImage *numberPadDoneImageNormal;
    UIImage *numberPadDoneImageHighlighted;
    UIButton *numberPadDoneButton;

@property (nonatomic, retain) UIImage *numberPadDoneImageNormal;
@property (nonatomic, retain) UIImage *numberPadDoneImageHighlighted;
@property (nonatomic, retain) UIButton *numberPadDoneButton;

- (IBAction)numberPadDoneButton:(id)sender;


and NumberPadViewController.m:

#import "NumberPadViewController.h"

@implementation NumberPadViewController

@synthesize numberPadDoneImageNormal;
@synthesize numberPadDoneImageHighlighted;
@synthesize numberPadDoneButton;

- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle {
    if ([super initWithNibName:nibName bundle:nibBundle] == nil)
        return nil;
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.0) {
        self.numberPadDoneImageNormal = [UIImage imageNamed:@"DoneUp3.png"];
        self.numberPadDoneImageHighlighted = [UIImage imageNamed:@"DoneDown3.png"];
    } else {        
        self.numberPadDoneImageNormal = [UIImage imageNamed:@"DoneUp.png"];
        self.numberPadDoneImageHighlighted = [UIImage imageNamed:@"DoneDown.png"];
    return self;

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    // Add listener for keyboard display events
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
        [[NSNotificationCenter defaultCenter] addObserver:self 
    } else {
        [[NSNotificationCenter defaultCenter] addObserver:self 

    // Add listener for all text fields starting to be edited
    [[NSNotificationCenter defaultCenter] addObserver:self 

- (void)viewWillDisappear:(BOOL)animated {
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
        [[NSNotificationCenter defaultCenter] removeObserver:self 
    } else {
        [[NSNotificationCenter defaultCenter] removeObserver:self 
    [[NSNotificationCenter defaultCenter] removeObserver:self 
    [super viewWillDisappear:animated];

- (UIView *)findFirstResponderUnder:(UIView *)root {
    if (root.isFirstResponder)
        return root;    
    for (UIView *subView in root.subviews) {
        UIView *firstResponder = [self findFirstResponderUnder:subView];        
        if (firstResponder != nil)
            return firstResponder;
    return nil;

- (UITextField *)findFirstResponderTextField {
    UIResponder *firstResponder = [self findFirstResponderUnder:[self.view window]];
    if (![firstResponder isKindOfClass:[UITextField class]])
        return nil;
    return (UITextField *)firstResponder;

- (void)updateKeyboardButtonFor:(UITextField *)textField {

    // Remove any previous button
    [self.numberPadDoneButton removeFromSuperview];
    self.numberPadDoneButton = nil;

    // Does the text field use a number pad?
    if (textField.keyboardType != UIKeyboardTypeNumberPad)

    // If there's no keyboard yet, don't do anything
    if ([[[UIApplication sharedApplication] windows] count] < 2)
    UIWindow *keyboardWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];

    // Create new custom button
    self.numberPadDoneButton = [UIButton buttonWithType:UIButtonTypeCustom];
    self.numberPadDoneButton.frame = CGRectMake(0, 163, 106, 53);
    self.numberPadDoneButton.adjustsImageWhenHighlighted = FALSE;
    [self.numberPadDoneButton setImage:self.numberPadDoneImageNormal forState:UIControlStateNormal];
    [self.numberPadDoneButton setImage:self.numberPadDoneImageHighlighted forState:UIControlStateHighlighted];
    [self.numberPadDoneButton addTarget:self action:@selector(numberPadDoneButton:) forControlEvents:UIControlEventTouchUpInside];

    // Locate keyboard view and add button
    NSString *keyboardPrefix = [[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2 ? @"<UIPeripheralHost" : @"<UIKeyboard";
    for (UIView *subView in keyboardWindow.subviews) {
        if ([[subView description] hasPrefix:keyboardPrefix]) {
            [subView addSubview:self.numberPadDoneButton];
            [self.numberPadDoneButton addTarget:self action:@selector(numberPadDoneButton:) forControlEvents:UIControlEventTouchUpInside];

- (void)textFieldDidBeginEditing:(NSNotification *)note {
    [self updateKeyboardButtonFor:[note object]];

- (void)keyboardWillShow:(NSNotification *)note {
    [self updateKeyboardButtonFor:[self findFirstResponderTextField]];

- (void)keyboardDidShow:(NSNotification *)note {
    [self updateKeyboardButtonFor:[self findFirstResponderTextField]];

- (IBAction)numberPadDoneButton:(id)sender {
    UITextField *textField = [self findFirstResponderTextField];
    [textField resignFirstResponder];

- (void)dealloc {
    [numberPadDoneImageNormal release];
    [numberPadDoneImageHighlighted release];
    [numberPadDoneButton release];
    [super dealloc];



Convert a JSON Object to Buffer and Buffer to JSON Object back

You need to stringify the json, not calling toString

var buf = Buffer.from(JSON.stringify(obj));

And for converting string to json obj :

var temp = JSON.parse(buf.toString());

Using If/Else on a data frame

Use ifelse:

frame$twohouses <- ifelse(frame$data>=2, 2, 1)
   data twohouses
1     0         1
2     1         1
3     2         2
4     3         2
5     4         2
16    0         1
17    2         2
18    1         1
19    2         2
20    0         1
21    4         2

The difference between if and ifelse:

  • if is a control flow statement, taking a single logical value as an argument
  • ifelse is a vectorised function, taking vectors as all its arguments.

The help page for if, accessible via ?"if" will also point you to ?ifelse

Angular ng-repeat Error "Duplicates in a repeater are not allowed."

If by chance this error happens when working with SharePoint 2010: Rename your .json file extensions and be sure to update your restService path. No additional "track by $index" was required.

Luckily I was forwarded this link to this rationale:

.json becomes an important file type in SP2010. SP2010 includes certains webservice endpoints. The location of these files is 14hive\isapi folder. The extension of these files are .json. That is the reason it gives such a error.

"cares only that the contents of a json file is json - not its file extension"

Once the file extensions are changed, should be all set.

Notification bar icon turns white in Android 5 Lollipop

Another option is to take advantage of version-specific drawable (mipmap) directories to supply different graphics for Lollipop and above.

In my app, the "v21" directories contain icons with transparent text while the other directories contain non-transparent version (for versions of Android older than Lollipop).

File system

Which should look something like this:

Android Studio

This way, you don't need to check for version numbers in code, e.g.

PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,

Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)

Likewise, you can reference "ic_notification" (or whatever you choose to call it) in your GCM payload if you use the "icon" attribute.

How to run Gulp tasks sequentially one after the other

I was searching for this answer for a while. Now I got it in the official gulp documentation.

If you want to perform a gulp task when the last one is complete, you have to return a stream:

gulp.task('wiredep', ['dev-jade'], function () {_x000D_
    var stream = gulp.src(paths.output + '*.html')_x000D_
    return stream; // execute next task when this is completed_x000D_
// First will execute and complete wiredep task_x000D_
gulp.task('prod-jade', ['wiredep'], function() {_x000D_
    gulp.src(paths.output + '**/*.html')_x000D_

How to pass text in a textbox to JavaScript function?

This is what I have done. (Adapt from all of your answers)

<input name="textbox1" type="text" id="txt1"/>
<input name="buttonExecute" onclick="execute(document.getElementById('txt1').value)" type="button" value="Execute" />

It works. Thanks to all of you. :)

How to AUTO_INCREMENT in db2?

You're looking for is called an IDENTITY column:

create table student (
  ,sname varchar(30)
  ,PRIMARY KEY (sid)

A sequence is another option for doing this, but you need to determine which one is proper for your particular situation. Read this for more information comparing sequences to identity columns.

Convert bytes to a string

I made a function to clean a list

def cleanLists(self, lista):
    lista = [x.strip() for x in lista]
    lista = [x.replace('\n', '') for x in lista]
    lista = [x.replace('\b', '') for x in lista]
    lista = [x.encode('utf8') for x in lista]
    lista = [x.decode('utf8') for x in lista]

    return lista

How to allow only integers in a textbox?

we can use javascript code

function validateAlphaNumericCode(event) {
    keyEntry = (event.which) ? event.which : event.keyCode

    if (((keyEntry >= '65') && (keyEntry <= '90')) || ((keyEntry >= '97') && (keyEntry <= '122')) || (keyEntry == '37') || (keyEntry == '39') || (keyEntry == '46') || (keyEntry == '8') || (keyEntry == '9') || (keyEntry == '95') || ((keyEntry >= '48') && (keyEntry <= '57')))
        return true;
        return false;

validate this code with your textbox.

How do I convert a String to a BigInteger?

According to the documentation:

BigInteger(String val)

Translates the decimal String representation of a BigInteger into a BigInteger.

It means that you can use a String to initialize a BigInteger object, as shown in the following snippet:

sum = sum.add(new BigInteger(newNumber));

Laravel: Get base url

Laravel provides bunch of helper functions and for your requirement you can simply

use url() function of Laravel Helpers

but in case of Laravel 5.2 you will have to use url('/')

here is the list of all other helper functions of Laravel

Creating a directory in /sdcard fails

use mkdirs() instead of mkdir() worked for me :)

File folder = new File(Environment.getExternalStorageDirectory()+"/Saved CGPA");
    Toast.makeText(this, "New Folder Created", Toast.LENGTH_SHORT).show();

File sdCardFile = new File(Environment.getExternalStorageDirectory()+"/Saved CGPA/cgpa.html");

git pull from master into the development branch

This Worked for me. For getting the latest code from master to my branch

git rebase origin/master

Sorting data based on second column of a file

You can use the sort command:

sort -k2 -n yourfile

-n, --numeric-sort compare according to string numerical value

For example:

$ cat ages.txt 
Bob 12
Jane 48
Mark 3
Tashi 54

$ sort -k2 -n ages.txt 
Mark 3
Bob 12
Jane 48
Tashi 54

Create a dropdown component

Hope this will help to someone. Works fine in Angular 6 with reactive forms. Can operate by keyboard too.


<div class="dropdown-wrapper {{className}} {{isFocused ? 'focus':''}}" [ngClass]="{'is-open':isOpen, 'disabled':isReadOnly}" *ngIf="options" (contextmenu)="$event.stopPropagation();">
  <div class="box" (click)="toggle($event)">
      <div class="dropdown-selected" *ngIf="isSelectedValue" l10nTranslate><span>{{options[selected]}}</span></div>
      <div class="dropdown-selected" *ngIf="!isSelectedValue" l10nTranslate><span>{{placeholder}}</span></div>

  <ul class="dropdown-options" *ngIf="options">
    <li *ngIf="placeholder" (click)="$event.stopPropagation()">{{placeholder}}</li>
      <li id="li{{i}}"
        *ngFor="let option of options; let i = index"
        []="selected === i"
        (click)="optionSelect(option, i, $event)"



@import "../../../assets/scss/variables";

.dropdown-wrapper {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    border: 1px solid #DDDDDD;
    border-radius: 3px;
    cursor: pointer;
    position: relative;
        border: 1px solid #a8a8a8;
    .box {
        display: -webkit-box;
        display: -ms-flexbox;
        display: flex;
        width: 100%;

    .dropdown-selected {
        height: 30px;
        position: relative;
        padding: 10px 30px 10px 10px;
        display: -webkit-box;
        display: -ms-flexbox;
        display: flex;
        -webkit-box-align: center;
            -ms-flex-align: center;
                align-items: center;
        width: 100%;
        font-size: 12px;
        color: #666666;
        overflow: hidden;
        background-color: #fff;
        &::before {
            content: "";
            position: absolute;
            top: 50%;
            right: 5px;
            -webkit-transform: translateY(-50%);
                    transform: translateY(-50%);
            width: 22px;
            height: 22px;
            background: url('/assets/i/dropdown-open-selector.svg');
            background-size: 22px 22px;
        span {
            white-space: nowrap;
            overflow: hidden;
            text-overflow: ellipsis;

    .dropdown-options {
        display: none;
        position: absolute;
        padding: 8px 6px 9px 5px;
        max-height: 261px;
        overflow-y: auto;
        z-index: 999;
        li {
            padding: 10px 25px 10px 10px;
            font-size: $regular-font-size;
            color: $content-text-black;
            position: relative;
            line-height: 10px;
            &:last-child {
                border-bottom: none;
            &:hover {
                background-color: #245A88;
                border-radius: 3px;
                color: #fff;
                border-bottom-color: transparent;
                background-color: #245A88;
                border-radius: 3px;
                color: #fff;
            &.active {
                background-color: #245A88;
                border-radius: 3px;
                color: #fff;
                border-bottom-color: transparent;
            &:hover {
                background-color: #7898B3
            &.active {
                font-weight: 600;
    &.is-open {
        .dropdown-selected {
            &::before {
                content: "";
                position: absolute;
                top: 50%;
                right: 5px;
                -webkit-transform: translateY(-50%);
                        transform: translateY(-50%);
                width: 22px;
                height: 22px;
                background: url('/assets/i/dropdown-close-selector.svg');
                background-size: 22px 22px;
        .dropdown-options {
            display: -webkit-box;
            display: -ms-flexbox;
            display: flex;
            -webkit-box-orient: vertical;
            -webkit-box-direction: normal;
                -ms-flex-direction: column;
                    flex-direction: column;
            width: 100%;
            top: 32px;
            border-radius: 3px;
            background-color: #ffffff;
            border: 1px solid #DDDDDD;
            -webkit-box-shadow: 0px 3px 11px 0 rgba(1, 2, 2, 0.14);
                    box-shadow: 0px 3px 11px 0 rgba(1, 2, 2, 0.14);
    &.data-input-fields {
        .box {
            height: 35px;
    &.send-email-table-select {
        min-width: 140px;
        border: none;
    &.persoanal-settings {
        width: 80px;

  pointer-events: none;
  background-color: #F1F1F1;
  opacity: 0.7;


import { Component, OnInit, Input, Output, EventEmitter, HostListener, forwardRef } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';

const noop = () => {

  useExisting: forwardRef(() => DropdownComponent),
  multi: true

  selector: 'app-dropdown',
  templateUrl: './dropdown.component.html',
  styleUrls: ['./dropdown.component.scss'],
export class DropdownComponent implements OnInit, ControlValueAccessor {

  @Input() options: Array<string>;
  @Input() selected: number;
  @Input() className: string;
  @Input() placeholder: string;
  @Input() isReadOnly = false;
  @Output() optSelect = new EventEmitter();
  isOpen = false;

  private onTouchedCallback: () => void = noop;
  private onChangeCallback: (_: any) => void = noop;
  isSelectedValue: boolean;
  key: string;
  isFocused: boolean;

   *Creates an instance of DropdownComponent.
   * @memberof DropdownComponent

  ngOnInit() {
    // Place default value in dropdown
    if (this.selected) {
      this.placeholder = '';
      this.isOpen = false;

  focusHandler() {
    this.selected = 0;
    this.isFocused = true;

  focusOutHandler() {
    this.isFocused = false;

  @HostListener('document:keydown', ['$event'])
  keyPressHandle(event: KeyboardEvent) {

    if (this.isFocused) {
      this.key = event.code;
      switch (this.key) {
        case 'Space':
          this.isOpen = true;
        case 'ArrowDown':
          if (this.options.length - 1 > this.selected) {
            this.selected = this.selected + 1;
        case 'ArrowUp':
          if (this.selected > 0) {
            this.selected = this.selected - 1;
        case 'Enter':
          if (this.selected > 0) {
            this.isSelectedValue = true;
            this.isOpen = false;


  * option selection
  * @param {string} selectedOption - text
  * @param {number} idx - current index of item
  * @param {any} event - object
  optionSelect(selectedOption: string, idx, e: any) {
    this.selected = idx;
    this.isSelectedValue = true;
    // this.placeholder = '';
    this.isOpen = false;

  * toggle the dropdown
  * @param {any} event object
  toggle(e: any) {
    // close all previously opened dropdowns, before open
    const allElems = document.querySelectorAll('.dropdown-wrapper');
    for (let i = 0; i < allElems.length; i++) {
    this.isOpen = !this.isOpen;
    if (this.selected >= 0) {
      document.querySelector('#li' + this.selected).scrollIntoView(true);

  * dropdown click on outside
  @HostListener('document: click', ['$event'])
  onClick() {
    this.isOpen = false;

   * Method implemented from ControlValueAccessor and set default selected value
   * @param {*} obj
   * @memberof DropdownComponent
  writeValue(obj: any): void {
    if (obj && obj !== '') {
      this.isSelectedValue = true;
      this.selected = obj;
    } else {
      this.isSelectedValue = false;

  // From ControlValueAccessor interface
  registerOnChange(fn: any) {
    this.onChangeCallback = fn;

  // From ControlValueAccessor interface
  registerOnTouched(fn: any) {
    this.onTouchedCallback = fn;

  setDisabledState?(isDisabled: boolean): void {




<app-dropdown formControlName="type" [options]="types" [placeholder]="captureData.type" [isReadOnly]="isReadOnly">

Options must bind an array as follows. It can change based on the requirement.

types= [
            "id": "1",
            "value": "Type 1"
             "id": "2",
             "value": "Type 2"
              "id": "3",
              "value": "Type 3"

How to make execution pause, sleep, wait for X seconds in R?

Sys.sleep() will not work if the CPU usage is very high; as in other critical high priority processes are running (in parallel).

This code worked for me. Here I am printing 1 to 1000 at a 2.5 second interval.

for (i in 1:1000)
  while((as.numeric(Sys.time()) - as.numeric(date_time))<2.5){} #dummy while loop

How to configure logging to syslog in Python?

Here's the yaml dictConfig way recommended for 3.2 & later.

In log cfg.yml:

version: 1
disable_existing_loggers: true

        format: "[%(process)d] %(name)s(%(funcName)s:%(lineno)s) - %(levelname)s: %(message)s"

        class: logging.handlers.SysLogHandler
        level: DEBUG
        formatter: default
        address: /dev/log
        facility: local0

        class: logging.handlers.RotatingFileHandler
        level: DEBUG
        formatter: default
        filename: rotating.log
        maxBytes: 10485760 # 10MB
        backupCount: 20
        encoding: utf8

    level: DEBUG
    handlers: [syslog, rotating_file]
    propogate: yes

        level: DEBUG
        handlers: [syslog, rotating_file]
        propogate: yes

Load the config using:

log_config = yaml.safe_load(open('cfg.yml'))

Configured both syslog & a direct file. Note that the /dev/log is OS specific.

Split string in C every white space

You should be malloc'ing strlen(ptr), not strlen(buf). Also, your count2 should be limited to the number of words. When you get to the end of your string, you continue going over the zeros in your buffer and adding zero size strings to your array.

How do I toggle an element's class in pure JavaScript?

This one works in earlier versions of IE also.

function toogleClass(ele, class1) {_x000D_
  var classes = ele.className;_x000D_
  var regex = new RegExp('\\b' + class1 + '\\b');_x000D_
  var hasOne = classes.match(regex);_x000D_
  class1 = class1.replace(/\s+/g, '');_x000D_
  if (hasOne)_x000D_
    ele.className = classes.replace(regex, '');_x000D_
    ele.className = classes + class1;_x000D_
.red {_x000D_
  background-color: red_x000D_
div {_x000D_
  width: 100px;_x000D_
  height: 100px;_x000D_
  margin-bottom: 10px;_x000D_
  border: 1px solid black;_x000D_
<div class="does red redAnother " onclick="toogleClass(this, 'red')"></div>_x000D_
<div class="does collapse navbar-collapse " onclick="toogleClass(this, 'red')"></div>

How to read embedded resource text file

After reading all the solutions posted here. This is how I solved it:

// How to embedded a "Text file" inside of a C# project
//   and read it as a resource from c# code:
// (1) Add Text File to Project.  example: 'myfile.txt'
// (2) Change Text File Properties:
//      Build-action: EmbeddedResource
//      Logical-name: myfile.txt      
//          (note only 1 dot permitted in filename)
// (3) from c# get the string for the entire embedded file as follows:
//     string myfile = GetEmbeddedResourceFile("myfile.txt");

public static string GetEmbeddedResourceFile(string filename) {
    var a = System.Reflection.Assembly.GetExecutingAssembly();
    using (var s = a.GetManifestResourceStream(filename))
    using (var r = new System.IO.StreamReader(s))
        string result = r.ReadToEnd();
        return result;
    return "";      

DateTime.ToString("MM/dd/yyyy HH:mm:ss.fff") resulted in something like "09/14/2013"

You can use InvariantCulture because your user must be in a culture that uses a dot instead of a colon:

DateTime.ToString("MM/dd/yyyy HH:mm:ss.fff", CultureInfo.InvariantCulture);

How to send an email with Python?

Thought I'd put in my two bits here since I have just figured out how this works.

It appears that you don't have the port specified on your SERVER connection settings, this effected me a little bit when I was trying to connect to my SMTP server that isn't using the default port: 25.

According to the smtplib.SMTP docs, your ehlo or helo request/response should automatically be taken care of, so you shouldn't have to worry about this (but might be something to confirm if all else fails).

Another thing to ask yourself is have you allowed SMTP connections on your SMTP server itself? For some sites like GMAIL and ZOHO you have to actually go in and activate the IMAP connections within the email account. Your mail server might not allow SMTP connections that don't come from 'localhost' perhaps? Something to look into.

The final thing is you might want to try and initiate the connection on TLS. Most servers now require this type of authentication.

You'll see I've jammed two TO fields into my email. The msg['TO'] and msg['FROM'] msg dictionary items allows the correct information to show up in the headers of the email itself, which one sees on the receiving end of the email in the To/From fields (you might even be able to add a Reply To field in here. The TO and FROM fields themselves are what the server requires. I know I've heard of some email servers rejecting emails if they don't have the proper email headers in place.

This is the code I've used, in a function, that works for me to email the content of a *.txt file using my local computer and a remote SMTP server (ZOHO as shown):

def emailResults(folder, filename):

    # body of the message
    doc = folder + filename + '.txt'
    with open(doc, 'r') as readText:
        msg = MIMEText(

    # headers
    TO = '[email protected]'
    msg['To'] = TO
    FROM = '[email protected]'
    msg['From'] = FROM
    msg['Subject'] = 'email subject |' + filename

    # SMTP
    send = smtplib.SMTP('', 587)
    send.login('[email protected]', 'password')
    send.sendmail(FROM, TO, msg.as_string())

Axios handling errors

call the request function from anywhere without having to use catch().

First, while handling most errors in one place is a good Idea, it's not that easy with requests. Some errors (e.g. 400 validation errors like: "username taken" or "invalid email") should be passed on.

So we now use a Promise based function:

const baseRequest = async (method: string, url: string, data: ?{}) =>
  new Promise<{ data: any }>((resolve, reject) => {
    const requestConfig: any = {
      timeout: 10000,
      headers: {},

    try {
      const response = await axios(requestConfig);
      // Request Succeeded!
    } catch (error) {
      // Request Failed!

      if (error.response) {
        // Request made and server responded
      } else if (error.request) {
        // The request was made but no response was received
      } else {
        // Something happened in setting up the request that triggered an Error

you can then use the request like

try {
  response = await baseRequest('GET', '')
} catch (error) {
  // either handle errors or don't

What are libtool's .la file for?

It is a textual file that includes a description of the library.

It allows libtool to create platform-independent names.

For example, libfoo goes to:

Under Linux:

/lib/       # Symlink to shared object
/lib/     # Symlink to shared object
/lib/ # Shared object
/lib/libfoo.a        # Static library
/lib/       # 'libtool' library

Under Cygwin:

/lib/libfoo.dll.a    # Import library
/lib/libfoo.a        # Static library
/lib/       # libtool library
/bin/cygfoo_1.dll    # DLL

Under Windows MinGW:

/lib/libfoo.dll.a    # Import library
/lib/libfoo.a        # Static library
/lib/       # 'libtool' library
/bin/foo_1.dll       # DLL

So is the only file that is preserved between platforms by libtool allowing to understand what happens with:

  • Library dependencies
  • Actual file names
  • Library version and revision

Without depending on a specific platform implementation of libraries.

Creating stored procedure with declare and set variables

I assume you want to pass the Order ID in. So:

CREATE PROCEDURE [dbo].[Procedure_Name]
    @OrderID INT
) AS
    Declare @OrderItemID AS INT
    DECLARE @AppointmentID AS INT
    DECLARE @PurchaseOrderID AS INT
    DECLARE @PurchaseOrderItemID AS INT
    DECLARE @SalesOrderID AS INT
    DECLARE @SalesOrderItemID AS INT

    SET @OrderItemID = (SELECT OrderItemID FROM [OrderItem] WHERE OrderID = @OrderID)
    SET @AppointmentID = (SELECT AppoinmentID FROM [Appointment] WHERE OrderID = @OrderID)
    SET @PurchaseOrderID = (SELECT PurchaseOrderID FROM [PurchaseOrder] WHERE OrderID = @OrderID)

Determine if string is in list in JavaScript

EcmaScript 6 and up

If you're using ES6 or higher, the cleanest way is to construct an array of the items and use Array.includes:

['a', 'b', 'c'].includes('b')

This has some inherent benefits over indexOf because it can properly test for the presence of NaN in the list, and can match missing array elements such as the middle one in [1, , 2] to undefined. includes also works on JavaScript typed arrays such as Uint8Array.

If you're concerned about browser support (such as for IE or Edge), you can check Array.includes at CanIUse.Com, and if you want to target a browser or browser version that's missing includes, I recommend for polyfilling.

Without An Array

You could add a new isInList property to strings as follows:

if (!String.prototype.isInList) {
  Object.defineProperty(String.prototype, 'isInList', {
    get: () => function(...args) {
      let value = this.valueOf();
      for (let i = 0, l = args.length; i < l; i += 1) {
        if (arguments[i] === value) return true;
      return false;

Then use it like so:

'fox'.isInList('weasel', 'fox', 'stoat') // true
'fox'.isInList('weasel', 'stoat') // false

You can do the same thing for Number.prototype.

Note that Object.defineProperty cannot be used in IE8 and earlier, or very old versions of other browsers. However, it is a far superior solution to String.prototype.isInList = function() { ... } because using simple assignment like that will create an enumerable property on String.prototype, which is more likely to break code.


If you are using a modern browser, indexOf always works. However, for IE8 and earlier you'll need a polyfill.

If indexOf returns -1, the item is not in the list. Be mindful though, that this method will not properly check for NaN, and while it can match an explicit undefined, it can’t match a missing element to undefined as in the array [1, , 2].

Polyfill for indexOf or includes in IE, or any other browser/version lacking support

If you don't want to use a service like as mentioned above, you can always include in your own source code standards-compliant custom polyfills. For example, Mozilla Developer Network has one for indexOf.

In this situation where I had to make a solution for Internet Explorer 7, I "rolled my own" simpler version of the indexOf() function that is not standards-compliant:

if (!Array.prototype.indexOf) {
   Array.prototype.indexOf = function(item) {
      var i = this.length;
      while (i--) {
         if (this[i] === item) return i;
      return -1;

However, I don't think modifying Array.prototype is the best answer in the long term. Modifying Object and Array prototypes in JavaScript can lead to serious bugs. You need to decide whether doing so is safe in your own environment. Of primary note is that iterating an array (when Array.prototype has added properties) with for ... in will return the new function name as one of the keys:

Array.prototype.blah = function() { console.log('blah'); };
let arr = [1, 2, 3];
for (let x in arr) { console.log(x); }
// Result:
blah // Extra member iterated over!

Your code may work now, but the moment someone in the future adds a third-party JavaScript library or plugin that isn't zealously guarding against inherited keys, everything can break.

The old way to avoid that breakage is, during enumeration, to check each value to see if the object actually has it as a non-inherited property with if (arr.hasOwnProperty(x)) and only then work with that x.

The new ES6 ways to avoid this extra-key problem are:

  1. Use of instead of in, for (let x of arr). However, unless you can guarantee that all of your code and third-party libraries strictly stick to this method, then for the purposes of this question you'll probably just want to use includes as stated above.

  2. Define your new properties on the prototype using Object.defineProperty(), as this will make the property (by default) non-enumerable. This only truly solves the problem if all the JavaScript libraries or modules you use also do this.

Get values from label using jQuery

While this question is rather old, and has been answered, I thought I'd take the time to offer a couple of options that are, as yet, not addressed in other answers.

Given the corrected HTML (camelCasing the id attribute-value) of:

<label year="2010" month="6" id="currentMonth"> June &nbsp;2010</label>

You could use regular expressions to extract the month-name, and year:

// gets the eleent with an id equal to 'currentMonth',
// retrieves its text-content,
// uses String.prototype.trim() to remove leading and trailing white-space:
var labelText = $('#currentMonth').text().trim(),
    // finds the sequence of one, or more, letters (a-z, inclusive)
    // at the start (^) of the string, and retrieves the first match from
    // the array returned by the match() method:
    month = labelText.match(/^[a-z]+/i)[0],
    // finds the sequence of numbers (\d) of length 2-4 ({2,4}) characters,
    // at the end ($) of the string:
    year = labelText.match(/\d{2,4}$/)[0];

var labelText = $('#currentMonth').text().trim(),_x000D_
    month = labelText.match(/^[a-z]+/i)[0],_x000D_
    year = labelText.match(/\d{2,4}$/)[0];_x000D_
console.log(month, year);
<script src=""></script>_x000D_
<label year="2010" month="6" id="currentMonth"> June &nbsp;2010</label>

Rather than regular expressions, though, you could instead use custom data-* attributes (which work in HTML 4.x, despite being invalid under the doctype, but are valid under HTML 5):

var label = $('#currentMonth'),_x000D_
    month ='month'),_x000D_
    year ='year');_x000D_
console.log(month, year);
<script src=""></script>_x000D_
<label data-year="2010" data-month="6" id="currentMonth"> June &nbsp;2010</label>

Note that this will output 6 (for the data-month), rather than 'June' as in the previous example, though if you use an array to tie numbers to month-names, that can be solved easily:

var monthNames = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],_x000D_
    label = $('#currentMonth'),_x000D_
    month = monthNames['month') - 1],_x000D_
    year ='year');_x000D_
console.log(month, year);
<script src=""></script>_x000D_
<label data-year="2010" data-month="6" id="currentMonth"> June &nbsp;2010</label>

Similarly, the above could be easily transcribed to the native DOM (in compliant browsers):

var monthNames = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],_x000D_
    label = document.getElementById('currentMonth'),_x000D_
    month = monthNames[+label.dataset.month - 1],_x000D_
    year = label.dataset.year;_x000D_
console.log(month, year);
<script src=""></script>_x000D_
<label data-year="2010" data-month="6" id="currentMonth"> June &nbsp;2010</label>


Up, Down, Left and Right arrow keys do not trigger KeyDown event

I was having the exact same problem. I considered the answer @Snarfblam provided; however, if you read the documentation on MSDN, the ProcessCMDKey method is meant to override key events for menu items in an application.

I recently stumbled across this article from microsoft, which looks quite promising: According to microsoft, the best thing to do is set e.IsInputKey=true; in the PreviewKeyDown event after detecting the arrow keys. Doing so will fire the KeyDown event.

This worked quite well for me and was less hack-ish than overriding the ProcessCMDKey.

Remove folder and its contents from git/GitHub's history

For Windows user, please note to use " instead of ' Also added -f to force the command if another backup is already there.

git filter-branch -f --tree-filter "rm -rf FOLDERNAME" --prune-empty HEAD
git for-each-ref --format="%(refname)" refs/original/ | xargs -n 1 git update-ref -d
echo FOLDERNAME/ >> .gitignore
git add .gitignore
git commit -m "Removing FOLDERNAME from git history"
git gc
git push origin master --force

How to get a list column names and datatypes of a table in PostgreSQL?

without mentioning schema also you can get the required details Try this query->

select column_name,data_type from information_schema.columns where table_name = 'table_name';

Ignore Typescript Errors "property does not exist on value of type"

You can also use the following trick:

y.x = "some custom property"//gives typescript error

y["x"] = "some custom property"//no errors

Note, that to access x and dont get a typescript error again you need to write it like that y["x"], not y.x. So from this perspective the other options are better.

How to resolve "git did not exit cleanly (exit code 128)" error on TortoiseGit?

In my case, I forgot to add git to the respository name at the end.

How to use putExtra() and getExtra() for string data


startActivity(new Intent(First.this, Secend.class).putExtra("key",edit.getText.tostring));


String myData = getIntent.getStringExtra("key");