Programs & Examples On #Dhtml

Dynamic HTML, or DHTML, is an umbrella term for a collection of technologies used together to create interactive and animated web sites by using a combination of a static markup language (such as HTML), a client-side scripting language (such as JavaScript), a presentation definition language (such as CSS), and the Document Object Model.

How do I attach events to dynamic HTML elements with jQuery?

Sometimes doing this (the top-voted answer) is not always enough:

$('body').on('click', 'a.myclass', function() {
    // do something

This can be an issue because of the order event handlers are fired. If you find yourself doing this, but it is causing issues because of the order in which it is handled.. You can always wrap that into a function, that when called "refreshes" the listener.

For example:

function RefreshSomeEventListener() {
    // Remove handler from existing elements
    $("#wrapper .specific-selector").off(); 

    // Re-add event handler for all matching elements
    $("#wrapper .specific-selector").on("click", function() {
        // Handle event.

Because it is a function, whenever I set up my listener this way, I typically call it on document ready:

$(document).ready(function() {
    // Other ready commands / code

    // Call our function to setup initial listening

Then, whenever you add some dynamically added element, call that method again:

function SomeMethodThatAddsElement() {
    // Some code / AJAX / whatever.. Adding element dynamically

    // Refresh our listener, so the new element is taken into account

Hopefully this helps!


jQuery document.createElement equivalent?

Here's your example in the "one" line.

this.$OuterDiv = $('<div></div>')
        .attr({ cellSpacing : 0 })

Update: I thought I'd update this post since it still gets quite a bit of traffic. In the comments below there's some discussion about $("<div>") vs $("<div></div>") vs $(document.createElement('div')) as a way of creating new elements, and which is "best".

I put together a small benchmark, and here are roughly the results of repeating the above options 100,000 times:

jQuery 1.4, 1.5, 1.6

               Chrome 11  Firefox 4   IE9
<div>            440ms      640ms    460ms
<div></div>      420ms      650ms    480ms
createElement    100ms      180ms    300ms

jQuery 1.3

                Chrome 11
<div>             770ms
<div></div>      3800ms
createElement     100ms

jQuery 1.2

                Chrome 11
<div>            3500ms
<div></div>      3500ms
createElement     100ms

I think it's no big surprise, but document.createElement is the fastest method. Of course, before you go off and start refactoring your entire codebase, remember that the differences we're talking about here (in all but the archaic versions of jQuery) equate to about an extra 3 milliseconds per thousand elements.

Update 2

Updated for jQuery 1.7.2 and put the benchmark on which is probably a bit more scientific than my primitive benchmarks, plus it can be crowdsourced now!

Redirect parent window from an iframe action

I found that <a href="..." target="_top">link</a> works too

Adding and removing style attribute from div with jquery

Remove style attribute from div using J query:


Add style to div using J query:

$("#TableDiv").attr("style", "display: none;");

Add style using html:

<div class="row" id="TableDiv" style="display: none;">

Hope it will helpful :)

Set content of HTML <span> with Javascript

This is standards compliant and cross-browser safe.


var span = document.getElementById('someID');

while( span.firstChild ) {
    span.removeChild( span.firstChild );
span.appendChild( document.createTextNode("some new content") );

Capture iframe load complete event

Neither of the above answers worked for me, however this did


As @doppleganger pointed out below, load is gone as of jQuery 3.0, so here's an updated version that uses on. Please note this will actually work on jQuery 1.7+, so you can implement it this way even if you're not on jQuery 3.0 yet.

$('iframe').on('load', function() {
    // do stuff 

Print <div id="printarea"></div> only?

You could use a separate CSS style which disables every other content except the one with the id "printarea".

See CSS Design: Going to Print for further explanation and examples.

How do I programmatically click on an element in JavaScript?

Are you trying to actually follow the link or trigger the onclick? You can trigger an onclick with something like this:

var link = document.getElementById(linkId);;

How to resize html canvas element?

Note that if your canvas is statically declared you should use the width and height attributes, not the style, eg. this will work:

<canvas id="c" height="100" width="100" style="border:1px"></canvas>
    document.getElementById('c').width = 200;

But this will not work:

<canvas id="c" style="width: 100px; height: 100px; border:1px"></canvas>
    document.getElementById('c').width = 200;

How do I retrieve an HTML element's actual width and height?

You only need to calculate it for IE7 and older (and only if your content doesn't have fixed size). I suggest using HTML conditional comments to limit hack to old IEs that don't support CSS2. For all other browsers use this:

<style type="text/css">
    html,body {display:table; height:100%;width:100%;margin:0;padding:0;}
    body {display:table-cell; vertical-align:middle;}
    div {display:table; margin:0 auto; background:red;}

This is the perfect solution. It centers <div> of any size, and shrink-wraps it to size of its content.

Getting all selected checkboxes in an array

Use commented if block to prevent add values which has already in array if you use button click or something to run the insertion

$('#myDiv').change(function() {_x000D_
  var values = [];_x000D_
    $('#myDiv :checked').each(function() {_x000D_
      //if(values.indexOf($(this).val()) === -1){_x000D_
      // }_x000D_
<div id="myDiv">_x000D_
  <input type="checkbox" name="type" value="4" />_x000D_
  <input type="checkbox" name="type" value="3" />_x000D_
  <input type="checkbox" name="type" value="1" />_x000D_
  <input type="checkbox" name="type" value="5" />_x000D_
<script src=""></script>

Modifying a query string without reloading the page

Building off of Fabio's answer, I created two functions that will probably be useful for anyone stumbling upon this question. With these two functions, you can call insertParam() with a key and value as an argument. It will either add the URL parameter or, if a query param already exists with the same key, it will change that parameter to the new value:

//function to remove query params from a URL
function removeURLParameter(url, parameter) {
    //better to use if you have a location/link object
    var urlparts= url.split('?');   
    if (urlparts.length>=2) {

        var prefix= encodeURIComponent(parameter)+'=';
        var pars= urlparts[1].split(/[&;]/g);

        //reverse iteration as may be destructive
        for (var i= pars.length; i-- > 0;) {    
            //idiom for string.startsWith
            if (pars[i].lastIndexOf(prefix, 0) !== -1) {  
                pars.splice(i, 1);

        url= urlparts[0] + (pars.length > 0 ? '?' + pars.join('&') : "");
        return url;
    } else {
        return url;

//function to add/update query params
function insertParam(key, value) {
    if (history.pushState) {
        // var newurl = window.location.protocol + "//" + + search.pathname + '?myNewUrlQuery=1';
        var currentUrlWithOutHash = window.location.origin + window.location.pathname +;
        var hash = window.location.hash
        //remove any param for the same key
        var currentUrlWithOutHash = removeURLParameter(currentUrlWithOutHash, key);

        //figure out if we need to add the param with a ? or a &
        var queryStart;
        if(currentUrlWithOutHash.indexOf('?') !== -1){
            queryStart = '&';
        } else {
            queryStart = '?';

        var newurl = currentUrlWithOutHash + queryStart + key + '=' + value + hash

Change :hover CSS properties with JavaScript

This is not actually adding the CSS to the cell, but gives the same effect. While providing the same result as others above, this version is a little more intuitive to me, but I'm a novice, so take it for what it's worth:

$(".hoverCell").bind('mouseover', function() {
    var old_color = $(this).css("background-color");
    $(this)[0].style.backgroundColor = '#ffff00';

    $(".hoverCell").bind('mouseout', function () {
        $(this)[0].style.backgroundColor = old_color;

This requires setting the Class for each of the cells you want to highlight to "hoverCell".

How to load up CSS files using Javascript?

The YUI library might be what you are looking for. It also supports cross domain loading.

If you use jquery, this plugin does the same thing.

jQuery get the id/value of <li> element after click function

If You Have Multiple li elements inside an li element then this will definitely help you, and i have checked it and it works....

$("li").on('click', function() {
          return false;

Child element click event trigger the parent click event

The stopPropagation() method stops the bubbling of an event to parent elements, preventing any parent handlers from being notified of the event.

You can use the method event.isPropagationStopped() to know whether this method was ever called (on that event object).


Here is the simple syntax to use this method:



$("div").click(function(event) {
    alert("This is : " + $(this).prop('id'));

    // Comment the following to see the difference

What is the best JavaScript code to create an img element

oImg.setAttribute('width', '1px');

px is for CSS only. Use either:

oImg.width = '1';

to set a width through HTML, or: = '1px';

to set it through CSS.

Note that old versions of IE don't create a proper image with document.createElement(), and old versions of KHTML don't create a proper DOM Node with new Image(), so if you want to be fully backwards compatible use something like:

// IEWIN boolean previously sniffed through eg. conditional comments

function img_create(src, alt, title) {
    var img = IEWIN ? new Image() : document.createElement('img');
    img.src = src;
    if ( alt != null ) img.alt = alt;
    if ( title != null ) img.title = title;
    return img;

Also be slightly wary of document.body.appendChild if the script may execute as the page is in the middle of loading. You can end up with the image in an unexpected place, or a weird JavaScript error on IE. If you need to be able to add it at load-time (but after the <body> element has started), you could try inserting it at the start of the body using body.insertBefore(body.firstChild).

To do this invisibly but still have the image actually load in all browsers, you could insert an absolutely-positioned-off-the-page <div> as the body's first child and put any tracking/preload images you don't want to be visible in there.

Start index for iterating Python list

You can use slicing:

for item in some_list[2:]:
    # do stuff

This will start at the third element and iterate to the end.

Running python script inside ipython

The %run magic has a parameter file_finder that it uses to get the full path to the file to execute (see here); as you note, it just looks in the current directory, appending ".py" if necessary.

There doesn't seem to be a way to specify which file finder to use from the %run magic, but there's nothing to stop you from defining your own magic command that calls into %run with an appropriate file finder.

As a very nasty hack, you could override the default file_finder with your own:[2] = my_file_finder

To be honest, at the rate the IPython API is changing that's as likely to continue to work as defining your own magic is.

Current date without time

String test = DateTime.Now.ToShortDateString();

Unloading classes in java?

Classloaders can be a tricky problem. You can especially run into problems if you're using multiple classloaders and don't have their interactions clearly and rigorously defined. I think in order to actually be able to unload a class youlre going go have to remove all references to any classes(and their instances) you're trying to unload.

Most people needing to do this type of thing end up using OSGi. OSGi is really powerful and surprisingly lightweight and easy to use,

Copy text from nano editor to shell

Much easier method:
$ cat my_file

Ctrl+Shift+c to copy the required output from the terminal

Ctrl+Shift+v to paste it wherever you like

How to convert NSNumber to NSString

In Swift 3.0

let number:NSNumber = 25
let strValue = String(describing: number as NSNumber)
print("As String => \(strValue)")

We can get the number value in String.

Remove URL parameters without refreshing page

a single line solution :

history.replaceState && history.replaceState(
  null, '', location.pathname +[\?&]my_parameter=[^&]+/, '').replace(/^&/, '?')

credits :

How do I use shell variables in an awk script?

You could pass in the command-line option -v with a variable name (v) and a value (=) of the environment variable ("${v}"):

% awk -vv="${v}" 'BEGIN { print v }'

Or to make it clearer (with far fewer vs):

% environment_variable=123test
% awk -vawk_variable="${environment_variable}" 'BEGIN { print awk_variable }'

How to remove a web site from google analytics

Here's an updated answer, as of Sept. 2013. This took me awhile to figure out.

  1. Go to the Admin tab.

    enter image description here

  2. In the middle column, select the web property that you want to delete from the dropdown.

    enter image description here

  3. In the right-hand column, click on "View Settings." ("Property Settings" in dec. 2015)

    enter image description here

  4. At the bottom of the next page, select "Delete this view."

    enter image description here

It will warn you that you're about to delete all of the data associated with this property. If you're sure, confirm.


How to align an indented line in a span that wraps into multiple lines?

<span> elements are inline elements, as such layout properties such as width or margin don't work. You can fix that by either changing the <span> to a block element (such as <div>), or by using padding instead.

Note that making a span element a block element by adding display: block; is redundant, as a span is by definition a otherwise style-less inline element whereas div is an otherwise style-less block element. So the correct solution is to use a div instead of a block-span.

Make child visible outside an overflow:hidden parent

For others, if clearfix does not solve this for you, add margins to the non-floated sibling that is/are the same as the width(s) of the floated sibling(s).

How can I do an UPDATE statement with JOIN in SQL Server?


INNER JOIN sale ON = sale.udid
SET ud.assid = sale.assid;

Using Eloquent ORM in Laravel to perform search of database using LIKE

You're able to do database finds using LIKE with this syntax:

Model::where('column', 'LIKE', '%value%')->get();

MVC [HttpPost/HttpGet] for Action

You don't need to specify both at the same time, unless you're specifically restricting the other verbs (i.e. you don't want PUT or DELETE, etc).

Contrary to some of the comments, I was also unable to use both Attributes [HttpGet, HttpPost] at the same time, but was able to specify both verbs instead.


    private ActionResult testResult(int id)
        return Json(new {
                            // user input
                            input = id,
                            // just so there's different content in the response
                            when = DateTime.Now,
                            // type of request
                            req = this.Request.HttpMethod,
                            // differentiate calls in response, for matching up
                            call = new StackTrace().GetFrame(1).GetMethod().Name
    public ActionResult Test(int id)
        return testResult(id);
    public ActionResult TestGetOnly(int id)
        return testResult(id);
    public ActionResult TestPostOnly(int id)
        return testResult(id);
    [HttpPost, HttpGet]
    public ActionResult TestBoth(int id)
        return testResult(id);
    [AcceptVerbs(HttpVerbs.Get | HttpVerbs.Post)]
    public ActionResult TestVerbs(int id)
        return testResult(id);


via POSTMAN, formatting by markdowntables

| Method    | URL                   | Response                                                                                  |
|--------   |---------------------- |----------------------------------------------------------------------------------------   |
| GET       | /ctrl/test/5          | { "input": 5, "when": "/Date(1408041216116)/", "req": "GET", "call": "Test" }             |
| POST      | /ctrl/test/5          | { "input": 5, "when": "/Date(1408041227561)/", "req": "POST", "call": "Test" }            |
| PUT       | /ctrl/test/5          | { "input": 5, "when": "/Date(1408041252646)/", "req": "PUT", "call": "Test" }             |
| GET       | /ctrl/testgetonly/5   | { "input": 5, "when": "/Date(1408041335907)/", "req": "GET", "call": "TestGetOnly" }      |
| POST      | /ctrl/testgetonly/5   | 404                                                                                       |
| PUT       | /ctrl/testgetonly/5   | 404                                                                                       |
| GET       | /ctrl/TestPostOnly/5  | 404                                                                                       |
| POST      | /ctrl/TestPostOnly/5  | { "input": 5, "when": "/Date(1408041464096)/", "req": "POST", "call": "TestPostOnly" }    |
| PUT       | /ctrl/TestPostOnly/5  | 404                                                                                       |
| GET       | /ctrl/TestBoth/5      | 404                                                                                       |
| POST      | /ctrl/TestBoth/5      | 404                                                                                       |
| PUT       | /ctrl/TestBoth/5      | 404                                                                                       |
| GET       | /ctrl/TestVerbs/5     | { "input": 5, "when": "/Date(1408041709606)/", "req": "GET", "call": "TestVerbs" }        |
| POST      | /ctrl/TestVerbs/5     | { "input": 5, "when": "/Date(1408041831549)/", "req": "POST", "call": "TestVerbs" }       |
| PUT       | /ctrl/TestVerbs/5     | 404                                                                                       |

Fitting empirical distribution to theoretical ones with Scipy (Python)?

Forgive me if I don't understand your need but what about storing your data in a dictionary where keys would be the numbers between 0 and 47 and values the number of occurrences of their related keys in your original list?
Thus your likelihood p(x) will be the sum of all the values for keys greater than x divided by 30000.

Can you delete data from influxdb?

With influx, you can only delete by time

For example, the following are invalid:

DELETE FROM foo WHERE time < '2014-06-30' and duration > 1000 #Can't delete if where clause has non time entity

This is how I was able to delete the data

DELETE FROM foo WHERE time > '2014-06-30' and time < '2014-06-30 15:16:01'

Update: this worked on influx 8. Supposedly it doesn't work on influx 9

Installing Bower on Ubuntu

Ubuntu 16.04 and later

Bower is a package manager primarily for (but not limited to) front-end web development. In Ubuntu 16.04 and later Bower package manager can be quickly and easily installed from the Ubuntu Software app. Open Ubuntu Software, search for "bower" and click the Install button to install it. In all currently supported versions of Ubuntu open the terminal and type:

sudo snap install bower --classic

enter image description here

How to hide html source & disable right click and text copy?

I have constructed a simple self checking php file, it only allows real loading by humans, and not robots like ( online source code viewer's ) ..

I'm not sure about View Source from Chrome, but it does block access to the html... Not just obfuscation, it uses a bounce back submittance to validate loads.

The short code was still visible in source viewers, so i obfuscated it also...

The page is loaded and bounces back, the bounce gets the real page, not the loader !

   // Create A New File called ( lock.php ) 

Copy this into it....

// PAGE SOURCE GUARD by Elijah Cuff.
if (!hasParam('bounce'))
echo "
<script type='text/javascript'>
eval(unescape('%64%6f%63%75%6d%65%6e%74%2e%77%72%69%74%65%28%63%36%36%32%32%30%36%62%32%63%28%27') + '%47%67%7f%76%73%44%15%15%45%69%74%7e%76%23%7a%6e%7f%6f%75%6c%46%2f%73%74%7f%7f%2d%2f%6a%6f%42%28%7e%62%7a%2d%45%15%15%47%66%71%73%7a%7a%20%7f%78%73%6a%45%2d%6b%66%6f%6f%6a%74%2e%23%73%62%72%6d%46%2d%61%70%7e%75%69%6d%2d%21%79%66%74%7e%6e%4a%2d%32%29%44%44%30%68%71%77%7d%7f%41%1a%15%47%34%6c%73%7d%74%41%12%16%47%7c%60%7d%6a%77%7a%42%16%17%23%7c%69%71%6f%7c%78%31%78%6b%7c%5f%68%76%6a%73%7e%7f%27%69%7e%75%69%7c%6a%72%71%2f%29%23%84%1a%15%23%6b%75%6f%7e%74%6e%75%7c%31%68%62%7f%4e%73%6b%75%6e%73%7f%49%79%4a%6f%27%67%28%79%67%7b%67%2a%2a%35%7f%7e%6d%7a%6a%7f%2f%2f%47%16%17%23%27%85%37%23%33%33%33%2e%41%15%15%45%30%78%6f%7d%6a%7f%7f%41%12%10%44%30%69%7f%72%74%417633171%35%39%35%35%31%30%36' + unescape('%27%29%29%3b'));
// -->
<noscript><i>Javascript required</i></noscript>
function hasParam($param)
    return isset($_POST[$param]);

EVERY PAGE .. Example....

 // use require for more security...

etc.. etc...

Hidden Columns in jqGrid

I just want to expand on queen3's suggestion, applying the following does the trick:

editoptions: { 
              dataInit: function(element) { 
                          $(element).attr("readonly", "readonly"); 

Scenario #1:

  • Field must be visible in the grid
  • Field must be visible in the form
  • Field must be read-only


        {  name:'providerUserId',
                            dataInit: function(element) { 
                                  jq(element).attr("readonly", "readonly"); 

The providerUserId is visible in the grid and visible when editing the form. But you cannot edit the contents.

Scenario #2:

  • Field must not be visible in the grid
  • Field must be visible in the form
  • Field must be read-only


                  dataInit: function(element) {                     
                             jq(element).attr("readonly", "readonly"); 

Notice in both instances I'm using jq to reference jquery, instead of the usual $. In my HTML I have the following script to modify the variable used by jQuery:

<script type="text/javascript">
    var jq = jQuery.noConflict();

<Django object > is not JSON serializable

First I added a to_dict method to my model ;

def to_dict(self):
    return {"name": self.woo, "title":}

Then I have this;

class DjangoJSONEncoder(JSONEncoder):

    def default(self, obj):
        if isinstance(obj, models.Model):
            return obj.to_dict()
        return JSONEncoder.default(self, obj)

dumps = curry(dumps, cls=DjangoJSONEncoder)

and at last use this class to serialize my queryset.

def render_to_response(self, context, **response_kwargs):
    return HttpResponse(dumps(self.get_queryset()))

This works quite well

Spring MVC: How to return image in @ResponseBody?

In spring 4 it's very easy you don't need to make any changes in beans. Only mark your return type to @ResponseBody.


@RequestMapping(value = "/image/{id}")
    public @ResponseBody
    byte[] showImage(@PathVariable Integer id) {
                 byte[] b;
        /* Do your logic and return 
        return b;

Read entire file in Scala?

Just like in Java, using CommonsIO library:

FileUtils.readFileToString(file, StandardCharsets.UTF_8)

Also, many answers here forget Charset. It's better to always provide it explicitly, or it will hit one day.

Even though JRE 8 is installed on my MAC -" No Java Runtime present,requesting to install " gets displayed in terminal

Below is worked for me on macos mojave 10.14.6 version

I installed current jdk(

Then do respectively;

  • vim .bash_profile
  • add "export JAVA_HOME=$(/usr/libexec/java_home)" to bash_profile
  • source .bash_profile

it is done. And you can check the version with java -version command.

Timestamp conversion in Oracle for YYYY-MM-DD HH:MM:SS format

VALUES(TO_DATE('2012-03-28 11:10:00','yyyy/mm/dd hh24:mi:ss'));!4/22115/1

PHP pass variable to include

According to php docs (see $_SERVER) $_SERVER['PHP_SELF'] is the "filename of the currently executing script".

The INCLUDE statement "includes and evaluates the specified" file and "the code it contains inherits the variable scope of the line on which the include occurs" (see INCLUDE).

I believe $_SERVER['PHP_SELF'] will return the filename of the 1st file, even when used by code in the 'second.php'.

I tested this with the following code and it works as expected ($phpSelf is the name of the first file).

// In the first.php file
// get the value of $_SERVER['PHP_SELF'] for the 1st file
$phpSelf = $_SERVER['PHP_SELF'];

// include the second file
// This slurps in the contents of second.php

// execute $phpSelf = $_SERVER['PHP_SELF']; in the secod.php file
// echo the value of $_SERVER['PHP_SELF'] of fist file

echo $phpSelf;  // This echos the name of the First.php file.

Loading local JSON file

       url: "Scripts/testingJSON.json",
           //force to handle it as text
       dataType: "text",
            success: function (dataTest) {

                //data downloaded so we call parseJSON function 
                //and pass downloaded data
                var json = $.parseJSON(dataTest);
                //now json variable contains data in json format
                //let's display a few items
                $.each(json, function (i, jsonObjectList) {
                for (var index = 0; index < jsonObjectList.listValue_.length;index++) {
                      alert(jsonObjectList.listKey_[index][0] + " -- " + jsonObjectList.listValue_[index].description_);


How to vertically align text in input type="text"?

The <textarea> element automatically aligns text at the top of a textbox, if you don't want to use CSS to force it.

What is the technology behind wechat, whatsapp and other messenger apps?

The WhatsApp Architecture Facebook Bought For $19 Billion explains the architecture involved in design of whatsapp.

Here is the general explanation from the link

  • WhatsApp server is almost completely implemented in Erlang.

  • Server systems that do the backend message routing are done in Erlang.

  • Great achievement is that the number of active users is managed with a really small server footprint. Team consensus is that it is largely because of Erlang.

  • Interesting to note Facebook Chat was written in Erlang in 2009, but they went away from it because it was hard to find qualified programmers.

  • WhatsApp server has started from ejabberd

  • Ejabberd is a famous open source Jabber server written in Erlang.

  • Originally chosen because its open, had great reviews by developers, ease of start and the promise of Erlang’s long term suitability for large communication system.

  • The next few years were spent re-writing and modifying quite a few parts of ejabberd, including switching from XMPP to internally developed protocol, restructuring the code base and redesigning some core components, and making lots of important modifications to Erlang VM to optimize server performance.

  • To handle 50 billion messages a day the focus is on making a reliable system that works. Monetization is something to look at later, it’s far far down the road.

  • A primary gauge of system health is message queue length. The message queue length of all the processes on a node is constantly monitored and an alert is sent out if they accumulate backlog beyond a preset threshold. If one or more processes falls behind that is alerted on, which gives a pointer to the next bottleneck to attack.

  • Multimedia messages are sent by uploading the image, audio or video to be sent to an HTTP server and then sending a link to the content along with its Base64 encoded thumbnail (if applicable).

  • Some code is usually pushed every day. Often, it’s multiple times a day, though in general peak traffic times are avoided. Erlang helps being aggressive in getting fixes and features into production. Hot-loading means updates can be pushed without restarts or traffic shifting. Mistakes can usually be undone very quickly, again by hot-loading. Systems tend to be much more loosely-coupled which makes it very easy to roll changes out incrementally.

  • What protocol is used in Whatsapp app? SSL socket to the WhatsApp server pools. All messages are queued on the server until the client reconnects to retrieve the messages. The successful retrieval of a message is sent back to the whatsapp server which forwards this status back to the original sender (which will see that as a "checkmark" icon next to the message). Messages are wiped from the server memory as soon as the client has accepted the message

  • How does the registration process work internally in Whatsapp? WhatsApp used to create a username/password based on the phone IMEI number. This was changed recently. WhatsApp now uses a general request from the app to send a unique 5 digit PIN. WhatsApp will then send a SMS to the indicated phone number (this means the WhatsApp client no longer needs to run on the same phone). Based on the pin number the app then request a unique key from WhatsApp. This key is used as "password" for all future calls. (this "permanent" key is stored on the device). This also means that registering a new device will invalidate the key on the old device.

Java image resize, maintain aspect ratio

All other answers show how to calculate the new image height in function of the new image width or vice-versa and how to resize the image using Java Image API. For those people who are looking for a straightforward solution I recommend any java image processing framework that can do this in a single line.

The exemple below uses Marvin Framework:

// 300 is the new width. The height is calculated to maintain aspect.
scale(image.clone(), image, 300);

Necessary import:

import static marvin.MarvinPluginCollection.*

How can getContentResolver() be called in Android?

The getContentResolver()method is also used when you query a Contact, using a Cursor object. I have used getContentResolver() to query the Android phone Contacts app, looking for contact info from a person's phone number, to include in my app. The different elements in a query (as shown below) represent what kind of contact details you want, and if they should be ordered, etc. Here is another example.

From the Content Provider Basics page from Android docs.

// Queries the user dictionary and returns results
mCursor = getContentResolver().query(
    UserDictionary.Words.CONTENT_URI,   // The content URI of the words table
    mProjection,                        // The columns to return for each row
    mSelectionClause                    // Selection criteria
    mSelectionArgs,                     // Selection criteria
    mSortOrder);                        // The sort order for the returned rows

How to extract a single value from JSON response?

using json.loads will turn your data into a python dictionary.

Dictionaries values are accessed using ['key']

resp_str = {
  "name" : "ns1:timeSeriesResponseType",
  "declaredType" : "org.cuahsi.waterml.TimeSeriesResponseType",
  "scope" : "javax.xml.bind.JAXBElement$GlobalScope",
  "value" : {
    "queryInfo" : {
      "creationTime" : 1349724919000,
      "queryURL" : "",
      "criteria" : {
        "locationParam" : "[ALL:103232434]",
        "variableParam" : "[00060, 00065]"
      "note" : [ {
        "value" : "[ALL:103232434]",
        "title" : "filter:sites"
      }, {
        "value" : "[mode=LATEST, modifiedSince=null]",
        "title" : "filter:timeRange"
      }, {
        "value" : "sdas01",
        "title" : "server"
      } ]
  "nil" : false,
  "globalScope" : true,
  "typeSubstituted" : false

would translate into a python diction

resp_dict = json.loads(resp_str)

resp_dict['name'] # "ns1:timeSeriesResponseType"

resp_dict['value']['queryInfo']['creationTime'] # 1349724919000

How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops

Expanding on patszim's answer for those in a rush.

  1. Open Excel workbook.
  2. Alt+F11 to open VBA/Macros window.
  3. Add reference to regex under Tools then References
    ![Excel VBA Form add references
  4. and selecting Microsoft VBScript Regular Expression 5.5
    ![Excel VBA add regex reference
  5. Insert a new module (code needs to reside in the module otherwise it doesn't work).
    ![Excel VBA insert code module
  6. In the newly inserted module,
    ![Excel VBA insert code into module
  7. add the following code:

    Function RegxFunc(strInput As String, regexPattern As String) As String
        Dim regEx As New RegExp
        With regEx
            .Global = True
            .MultiLine = True
            .IgnoreCase = False
            .pattern = regexPattern
        End With
        If regEx.Test(strInput) Then
            Set matches = regEx.Execute(strInput)
            RegxFunc = matches(0).Value
            RegxFunc = "not matched"
        End If
    End Function
  8. The regex pattern is placed in one of the cells and absolute referencing is used on it. ![Excel regex function in-cell usage Function will be tied to workbook that its created in.
    If there's a need for it to be used in different workbooks, store the function in Personal.XLSB

C++ obtaining milliseconds time on Linux -- clock() doesn't seem to work properly

With C++11 and std::chrono::high_resolution_clock you can do this:

#include <iostream>
#include <chrono>
#include <thread>
typedef std::chrono::high_resolution_clock Clock;

int main()
    std::chrono::milliseconds three_milliseconds{3};

    auto t1 = Clock::now();
    auto t2 = Clock::now();

    std::cout << "Delta t2-t1: " 
              << std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1).count()
              << " milliseconds" << std::endl;


Delta t2-t1: 3 milliseconds

Link to demo:

Getting net::ERR_UNKNOWN_URL_SCHEME while calling telephone number from HTML page in Android

Try this way,hope this will help you to solve your problem.


<LinearLayout xmlns:android=""


public class MyActivity extends Activity {

    private WebView webView;
    protected void onCreate(Bundle savedInstanceState) {

        webView = (WebView) findViewById(;
        webView.loadData("<a href=\"tel:+1800229933\">Call us free!</a>", "text/html", "utf-8");


Please add this permission in AndroidManifest.xml

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

Rename Excel Sheet with VBA Macro

This should do it:

WS.Name = WS.Name & "_v1"

How to get script of SQL Server data?

I had a hell of a time finding this option in SQL Management Studio 2012, but I finally found it. The option is hiding in the Advanced button in the screen below.

I always assumed this contained just assumed advanced options for File generation, since that's what it's next to, but it turns out someone at MS is just really bad at UI design in this case. HTH somebody who comes to this thread like I did.

SQL Management Studio 2012

How can I hide a TD tag using inline JavaScript or CSS?

We can hide the content inside a by using the following inline css:

<div style="visibility:hidden"></div>

for example:

<td><div style="visibility:hidden">Your Content Goes Here:</div></td>

How to download python from command-line?

apt-get install python2.7 will work on debian-like linuxes. The python website describes a whole bunch of other ways to get Python.

How to pass an array within a query string?

This works for me:

In link, to attribute has value:


Route can handle this:


For Multiple arrays:


Route stays same.


enter image description here

How to select the first row of each group?

We can use the rank() window function (where you would choose the rank = 1) rank just adds a number for every row of a group (in this case it would be the hour)

here's an example. ( from )

val dataset = spark.range(9).withColumn("bucket", 'id % 3)

import org.apache.spark.sql.expressions.Window
val byBucket = Window.partitionBy('bucket).orderBy('id)

scala> dataset.withColumn("rank", rank over byBucket).show
| id|bucket|rank|
|  0|     0|   1|
|  3|     0|   2|
|  6|     0|   3|
|  1|     1|   1|
|  4|     1|   2|
|  7|     1|   3|
|  2|     2|   1|
|  5|     2|   2|
|  8|     2|   3|

Formatting code in Notepad++

We can use the following shortcut in the latest version of notepad++ for formatting the code

Alt + Ctrl + Shift + B

Inserting records into a MySQL table using Java

this can also be done like this if you don't want to use prepared statements.

String sql = "INSERT INTO course(course_code,course_desc,course_chair)"+"VALUES('"+course_code+"','"+course_desc+"','"+course_chair+"');"

Why it didnt insert value is because you were not providing values, but you were providing names of variables that you have used.

how to read xml file from url using php

Your code seems right, check if you have fopen wrappers enabled (allow_url_fopen = On on php.ini)

Also, as mentioned by other answers, you should provide a properly encoded URI or encode it using urlencode() function. You should also check if there is any error fetching the XML string and if there is any parsing error, which you can output using libxml_get_errors() as follows:

if (($response_xml_data = file_get_contents($map_url))===false){
    echo "Error fetching XML\n";
} else {
   $data = simplexml_load_string($response_xml_data);
   if (!$data) {
       echo "Error loading XML\n";
       foreach(libxml_get_errors() as $error) {
           echo "\t", $error->message;
   } else {

If the problem is you can't fetch the XML code maybe it's because you need to include some custom headers in your request, check how to use stream_context_create() to create a custom stream context for use when calling file_get_contents() on example 4 at

Batch file to map a drive when the folder name contains spaces

whenever you deal with spaces in filenames, use quotes

net use "m:\Server01\my folder" /USER:mynetwork\Administrator "Mypassword" /persistent:yes

How do I make flex box work in safari?

Maybe this would be useful

-webkit-justify-content: space-around;

How to integrate SAP Crystal Reports in Visual Studio 2017

I had the same problem and I solved by installing Service pack 22 and it fixed it.

convert 12-hour hh:mm AM/PM to 24-hour hh:mm

I had to do something similar but I was generating a Date object so I ended up making a function like this:

function convertTo24Hour(time) {
    var hours = parseInt(time.substr(0, 2));
    if(time.indexOf('am') != -1 && hours == 12) {
        time = time.replace('12', '0');
    if(time.indexOf('pm')  != -1 && hours < 12) {
        time = time.replace(hours, (hours + 12));
    return time.replace(/(am|pm)/, '');

I think this reads a little easier. You feed a string in the format h:mm am/pm.

    var time = convertTo24Hour($("#starttime").val().toLowerCase());
    var date = new Date($("#startday").val() + ' ' + time);



        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 00:00:00 GMT-0700 (PDT)

        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 12:00:00 GMT-0700 (PDT)

        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 01:00:00 GMT-0700 (PDT)

        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 00:12:00 GMT-0700 (PDT)

        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 03:12:00 GMT-0700 (PDT)

        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 21:12:00 GMT-0700 (PDT)

How to make vim paste from (and copy to) system's clipboard?

A quick note for people whose vim installation does not support the * and + registers. It is not necessary to download a new vim installation to paste from the clipboard. Here is an alternative method:

1) Install parcellite (a clipboard manager with a low memory footprint);

2) In your .vimrc file, add the following:

command Clip r !parcellite -c

3) Restart vim.

Now when you type in :Clip as an ex command, the contents of the clipboard will be pasted in at the cursor. You can also map the new command to a function key so as to be able to do this with one keystroke.

Utilizing multi core for tar+gzip/bzip compression/decompression

You can use pigz instead of gzip, which does gzip compression on multiple cores. Instead of using the -z option, you would pipe it through pigz:

tar cf - paths-to-archive | pigz > archive.tar.gz

By default, pigz uses the number of available cores, or eight if it could not query that. You can ask for more with -p n, e.g. -p 32. pigz has the same options as gzip, so you can request better compression with -9. E.g.

tar cf - paths-to-archive | pigz -9 -p 32 > archive.tar.gz

Can't access object property, even though it shows up in a console log

Check whether you had applied any filters in the console. It happens to me in chrome console.

How to put a text beside the image?

Use floats to float the image, the text should wrap beside

php - get numeric index of associative array

echo array_search("car",array_keys($a));

How to use a parameter in ExecStart command line?

Although systemd indeed does not provide way to pass command-line arguments for unit files, there are possibilities to write instances:

For example: /lib/systemd/system/[email protected] looks something like this:

Description=Serial Getty on %I
After=dev-%i.device systemd-user-sessions.service

ExecStart=-/sbin/agetty -s %I 115200,38400,9600

So, you may start it like:

$ systemctl start [email protected]
$ systemctl start [email protected]

For systemd it will different instances:

$ systemctl status [email protected]
[email protected] - Getty on ttyUSB0
      Loaded: loaded (/lib/systemd/system/[email protected]; static)
      Active: active (running) since Mon, 26 Sep 2011 04:20:44 +0200; 2s ago
    Main PID: 5443 (agetty)
      CGroup: name=systemd:/system/[email protected]/ttyUSB0
          + 5443 /sbin/agetty -s ttyUSB0 115200,38400,9600

It also mean great possibility enable and disable it separately.

Off course it lack much power of command line parsing, but in common way it is used as some sort of config files selection. For example you may look at Fedora [email protected]:[email protected]

Postgres: How to convert a json string to text?

Mr. Curious was curious about this as well. In addition to the #>> '{}' operator, in 9.6+ one can get the value of a jsonb string with the ->> operator:

select to_jsonb('Some "text"'::TEXT)->>0;
 Some "text"
(1 row)

If one has a json value, then the solution is to cast into jsonb first:

select to_json('Some "text"'::TEXT)::jsonb->>0;
 Some "text"
(1 row)

Cannot send a content-body with this verb-type

Please set the request Content Type before you read the response stream;

 request.ContentType = "text/xml";

Getting the value of an attribute in XML

This is more of an xpath question, but like this, assuming the context is the parent element:

<xsl:value-of select="name/@attribute1" />

JavaScript alert not working in Android WebView

The following code will work:

private WebView mWebView;
final Activity activity = this;

// private Button b;
public void onCreate(Bundle savedInstanceState) {
    mWebView = (WebView) findViewById(;
    mWebView.setWebChromeClient(new WebChromeClient() {
        public void onProgressChanged(WebView view, int progress) {
            activity.setProgress(progress * 1000);


What is PECS (Producer Extends Consumer Super)?

The principles behind this in computer science is called

  • Covariance: ? extends MyClass,
  • Contravariance: ? super MyClass and
  • Invariance/non-variance: MyClass

The picture below should explain the concept. Picture courtesy: Andrey Tyukin

Covariance vs Contravariance

How can I remove the "No file chosen" tooltip from a file input in Chrome?

All the answers here are totally overcomplicated, or otherwise just totally wrong.


    <input type="file" />
    <button>Select File</button>


input {
    display: none;


$('button').on('click', function(){

I created this fiddle, in the most simplistic way. Clicking the Select File button will bring up the file select menu. You could then stylize the button any way you wanted. Basically, all you need to do is hide the file input, and trigger a synthetic click on it when you click another button. I spot tested this on IE 9, FF, and Chrome, and they all work fine.

version `CXXABI_1.3.8' not found (required by ...)

GCC 4.9 introduces a newer C++ ABI version than your system libstdc++ has, so you need to tell the loader to use this newer version of the library by adding that path to LD_LIBRARY_PATH. Unfortunately, I cannot tell you straight off where the libstdc++ so for your GCC 4.9 installation is located, as this depends on how you configured GCC. So you need something in the style of:

export LD_LIBRARY_PATH=/home/user/lib/gcc-4.9.0/lib:/home/user/lib/boost_1_55_0/stage/lib:$LD_LIBRARY_PATH

Note the actual path may be different (there might be some subdirectory hidden under there, like `x86_64-unknown-linux-gnu/4.9.0´ or similar).

contenteditable change events

const p = document.querySelector('p')_x000D_
const result = document.querySelector('div')_x000D_
const observer = new MutationObserver((mutationRecords) => {_x000D_
  result.textContent = mutationRecords[0].target.data_x000D_
  // result.textContent = p.textContent_x000D_
observer.observe(p, {_x000D_
  characterData: true,_x000D_
  subtree: true,_x000D_
<p contenteditable>abc</p>_x000D_
<div />

Can scripts be inserted with innerHTML?

Here a solution that does not use eval, and works with scripts, linked scripts , as well as with modules.

The function accepts 3 parameters :

  • html : String with the html code to insert
  • dest : reference to the target element
  • append : boolean flag to enable appending at the end of the target element html
function insertHTML(html, dest, append=false){
    // if no append is requested, clear the target element
    if(!append) dest.innerHTML = '';
    // create a temporary container and insert provided HTML code
    let container = document.createElement('div');
    container.innerHTML = html;
    // cache a reference to all the scripts in the container
    let scripts = container.querySelectorAll('script');
    // get all child elements and clone them in the target element
    let nodes = container.childNodes;
    for( let i=0; i< nodes.length; i++) dest.appendChild( nodes[i].cloneNode(true) );
    // force the found scripts to execute...
    for( let i=0; i< scripts.length; i++){
        let script = document.createElement('script');
        script.type = scripts[i].type || 'text/javascript';
        if( scripts[i].hasAttribute('src') ) script.src = scripts[i].src;
        script.innerHTML = scripts[i].innerHTML;
    // done!
    return true;

How to check if a file exists in the Documents directory in Swift?

This works fine for me in swift4:

func existingFile(fileName: String) -> Bool {

    let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
    let url = NSURL(fileURLWithPath: path)
    if let pathComponent = url.appendingPathComponent("\(fileName)") {
        let filePath = pathComponent.path
        let fileManager = FileManager.default
        if fileManager.fileExists(atPath: filePath) 


        return true

        } else {

        return false


    } else {

        return false



You can check with this call:

   if existingFile(fileName: "yourfilename") == true {

            // your code if file exists

           } else {

           // your code if file does not exist


I hope it is useful for someone. @;-]

CSS submit button weird rendering on iPad/iPhone

oops! just found myself: just add this line on any element you need

   -webkit-appearance: none;

Loop through all nested dictionary values?

Here is pythonic way to do it. This function will allow you to loop through key-value pair in all the levels. It does not save the whole thing to the memory but rather walks through the dict as you loop through it

def recursive_items(dictionary):
    for key, value in dictionary.items():
        if type(value) is dict:
            yield (key, value)
            yield from recursive_items(value)
            yield (key, value)

a = {'a': {1: {1: 2, 3: 4}, 2: {5: 6}}}

for key, value in recursive_items(a):
    print(key, value)


a {1: {1: 2, 3: 4}, 2: {5: 6}}
1 {1: 2, 3: 4}
1 2
3 4
2 {5: 6}
5 6

How should I remove all the leading spaces from a string? - swift

Swift 3 version of BadmintonCat's answer

extension String {
    func replace(_ string:String, replacement:String) -> String {
        return self.replacingOccurrences(of: string, with: replacement, options: NSString.CompareOptions.literal, range: nil)

    func removeWhitespace() -> String {
        return self.replace(" ", replacement: "")

Making text bold using attributed string in swift

Swift 3.0

Convert html to string and font change as per your requirement.

do {

     let str = try NSAttributedString(data: ("I'm a normal text and <b>this is my bold part . </b>And I'm again in the normal text".data(using: String.Encoding.unicode, allowLossyConversion: true)!), options: [ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil)

     myLabel.attributedText = str
     myLabel.font =  MONTSERRAT_BOLD(23)
     myLabel.textAlignment = NSTextAlignment.left
} catch {

func MONTSERRAT_BOLD(_ size: CGFloat) -> UIFont
    return UIFont(name: "MONTSERRAT-BOLD", size: size)!

Python: Removing spaces from list objects

List comprehension [num.strip() for num in hello] is the fastest.

>>> import timeit
>>> hello = ['999 ',' 666 ']

>>> t1 = lambda: map(str.strip, hello)
>>> timeit.timeit(t1)

>>> t2 = lambda: list(map(str.strip, hello))
>>> timeit.timeit(t2)

>>> t3 = lambda: [num.strip() for num in hello]
>>> timeit.timeit(t3)

>>> t4 = lambda: [num.replace(' ', '') for num in hello]
>>> timeit.timeit(t4)

HTML span align center not working?

The align attribute is deprecated. Use CSS text-align instead. Also, the span will not center the text unless you use display:block or display:inline-block and set a value for the width, but then it will behave the same as a div (block element).

Can you post an example of your layout? Use

How to interpret "loss" and "accuracy" for a machine learning model

Just to clarify the Training/Validation/Test data sets: The training set is used to perform the initial training of the model, initializing the weights of the neural network.

The validation set is used after the neural network has been trained. It is used for tuning the network's hyperparameters, and comparing how changes to them affect the predictive accuracy of the model. Whereas the training set can be thought of as being used to build the neural network's gate weights, the validation set allows fine tuning of the parameters or architecture of the neural network model. It's useful as it allows repeatable comparison of these different parameters/architectures against the same data and networks weights, to observe how parameter/architecture changes affect the predictive power of the network.

Then the test set is used only to test the predictive accuracy of the trained neural network on previously unseen data, after training and parameter/architecture selection with the training and validation data sets.

How to display the value of the bar on each bar with pyplot.barh()?

For anyone wanting to have their label at the base of their bars just divide v by the value of the label like this:

for i, v in enumerate(labels):

(note: I added 100 so it wasn't absolutely at the bottom)

To get a result like this: enter image description here

How can I turn a List of Lists into a List in Java 8?

The flatMap method on Stream can certainly flatten those lists for you, but it must create Stream objects for element, then a Stream for the result.

You don't need all those Stream objects. Here is the simple, concise code to perform the task.

// listOfLists is a List<List<Object>>.
List<Object> result = new ArrayList<>();

Because a List is Iterable, this code calls the forEach method (Java 8 feature), which is inherited from Iterable.

Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified.

And a List's Iterator returns items in sequential order.

For the Consumer, this code passes in a method reference (Java 8 feature) to the pre-Java 8 method List.addAll to add the inner list elements sequentially.

Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's iterator (optional operation).

What is managed or unmanaged code in programming?

When you think of unmanaged, think machine-specific, machine-level code. Like x86 assembly language. Unmanaged (native) code is compiled and linked to run directly on the processor it was designed for, excluding all the OS stuff for the moment. It's not portable, but it is fast. Very simple, stripped down code.

Managed code is everything from Java to old Interpretive BASIC, or anything that runs under .NET. Managed code typically is compiled to an intermediate level P-Code or byte code set of instructions. These are not machine-specific instructions, although they look similar to assembly language. Managed code insulates the program from the machine it's running on, and creates a secure boundary in which all memory is allocated indirectly, and generally speaking, you don't have direct access to machine resources like ports, memory address space, the stack, etc. The idea is to run in a more secure environment.

To convert from a managed variable, say, to an unmanaged one, you have to get to the actual object itself. It's probably wrapped or boxed in some additional packaging. UNmanaged variables (like an 'int', say) - on a 32 bit machine - takes exactly 4 bytes. There is no overhead or additional packaging. The process of going from managed to unmanaged code - and back again - is called "marshaling". It allows your programs to cross the boundary.

Android: View.setID(int id) programmatically - how to avoid ID conflicts?

Just an addition to the answer of @phantomlimb,

while View.generateViewId() require API Level >= 17,
this tool is compatibe with all API.

according to current API Level,
it decide weather using system API or not.

so you can use ViewIdGenerator.generateViewId() and View.generateViewId() in the same time and don't worry about getting same id

import java.util.concurrent.atomic.AtomicInteger;

import android.annotation.SuppressLint;
import android.os.Build;
import android.view.View;

 * {@link View#generateViewId()}??API Level >= 17,??????????API Level
 * <p>
 * ??????API Level,?????{@link View#generateViewId()},???????{@link View#generateViewId()}
 * ??,???????Id??
 * <p>
 * =============
 * <p>
 * while {@link View#generateViewId()} require API Level >= 17, this tool is compatibe with all API.
 * <p>
 * according to current API Level, it decide weather using system API or not.<br>
 * so you can use {@link ViewIdGenerator#generateViewId()} and {@link View#generateViewId()} in the
 * same time and don't worry about getting same id
 * @author [email protected]
public class ViewIdGenerator {
    private static final AtomicInteger sNextGeneratedId = new AtomicInteger(1);

    public static int generateViewId() {

        if (Build.VERSION.SDK_INT < 17) {
            for (;;) {
                final int result = sNextGeneratedId.get();
                // aapt-generated IDs have the high byte nonzero; clamp to the range under that.
                int newValue = result + 1;
                if (newValue > 0x00FFFFFF)
                    newValue = 1; // Roll over to 1, not 0.
                if (sNextGeneratedId.compareAndSet(result, newValue)) {
                    return result;
        } else {
            return View.generateViewId();


Is there a method that tells my program to quit?

Please note that the solutions based on sys.exit() or any Exception may not work in a multi-threaded environment.

Since exit() ultimately “only” raises an exception, it will only exit the process when called from the main thread, and the exception is not intercepted. (doc)

This answer from Alex Martelli for more details.

AngularJS For Loop with Numbers & Ranges

Suppose $scope.refernceurl is an array then

for(var i=0; i<$scope.refernceurl.length; i++){

Performance differences between ArrayList and LinkedList

In a LinkedList the elements have a reference to the element before and after it. In an ArrayList the data structure is just an array.

  1. A LinkedList needs to iterate over N elements to get the Nth element. An ArrayList only needs to return element N of the backing array.

  2. The backing array needs to either be reallocated for the new size and the array copied over or every element after the deleted element needs to be moved up to fill the empty space. A LinkedList just needs to set the previous reference on the element after the removed to the one before the removed and the next reference on the element before the removed element to the element after the removed element. Longer to explain, but faster to do.

  3. Same reason as deletion here.

Split string into array of characters?

According to this code golfing solution by Gaffi, the following works:

a = Split(StrConv(s, 64), Chr(0))

Styling an input type="file" button

The best way is using the pseudo element :after or :before as an element overt the de input. Then style that pseudo element as you wish. I recomend you to do as a general style for all input files as follows:

input {
  height: 0px;
  outline: none;

input[type="file"]:before {
  content: "Browse";
  background: #fff;
  width: 100%;
  height: 35px;
  display: block;
  text-align: left;
  position: relative;
  margin: 0;
  margin: 0 5px;
  left: -6px;
  border: 1px solid #e0e0e0;
  top: -1px;
  line-height: 35px;
  color: #b6b6b6;
  padding-left: 5px;
  display: block;

Regular expression: zero or more occurrences of optional character /


If your delimiters are slash-based, escape it:


* means "0 or more of the previous repeatable pattern", which can be a single character, a character class or a group.

HttpServletRequest to complete URL

The HttpServletRequest has the following methods:

  • getRequestURL() - returns the part of the full URL before query string separator character ?
  • getQueryString() - returns the part of the full URL after query string separator character ?

So, to get the full URL, just do:

public static String getFullURL(HttpServletRequest request) {
    StringBuilder requestURL = new StringBuilder(request.getRequestURL().toString());
    String queryString = request.getQueryString();

    if (queryString == null) {
        return requestURL.toString();
    } else {
        return requestURL.append('?').append(queryString).toString();

How do you read a CSV file and display the results in a grid in Visual Basic 2010?

Use the TextFieldParser class built into the .Net framework.

Here's some code copied from an MSDN forum post by Paul Clement. It converts the CSV into a new in-memory DataTable and then binds the DataGridView to the DataTable

    Dim TextFileReader As New Microsoft.VisualBasic.FileIO.TextFieldParser("C:\Documents and Settings\...\My Documents\My Database\Text\SemiColonDelimited.txt")

    TextFileReader.TextFieldType = FileIO.FieldType.Delimited

    Dim TextFileTable As DataTable = Nothing

    Dim Column As DataColumn
    Dim Row As DataRow
    Dim UpperBound As Int32
    Dim ColumnCount As Int32
    Dim CurrentRow As String()

    While Not TextFileReader.EndOfData
            CurrentRow = TextFileReader.ReadFields()
            If Not CurrentRow Is Nothing Then
                ''# Check if DataTable has been created
                If TextFileTable Is Nothing Then
                    TextFileTable = New DataTable("TextFileTable")
                    ''# Get number of columns
                    UpperBound = CurrentRow.GetUpperBound(0)
                    ''# Create new DataTable
                    For ColumnCount = 0 To UpperBound
                        Column = New DataColumn()
                        Column.DataType = System.Type.GetType("System.String")
                        Column.ColumnName = "Column" & ColumnCount
                        Column.Caption = "Column" & ColumnCount
                        Column.ReadOnly = True
                        Column.Unique = False
                End If
                Row = TextFileTable.NewRow
                For ColumnCount = 0 To UpperBound
                    Row("Column" & ColumnCount) = CurrentRow(ColumnCount).ToString
            End If
        Catch ex As _
            MsgBox("Line " & ex.Message & _
            "is not valid and will be skipped.")
        End Try
    End While
    frmMain.DataGrid1.DataSource = TextFileTable

No newline after div?

<div style="display: inline">Is this what you meant?</div>

Python vs Bash - In which kind of tasks each one outruns the other performance-wise?

Typical mainframe flow...

Input Disk/Tape/User (runtime) --> Job Control Language (JCL) --> Output Disk/Tape/Screen/Printer
                                   |                          ^
                                   v                          |
                                   `--> COBOL Program --------' 

Typical Linux flow...

Input Disk/SSD/User (runtime) --> sh/bash/ksh/zsh/... ----------> Output Disk/SSD/Screen/Printer
                                   |                          ^
                                   v                          |
                                   `--> Python script --------'
                                   |                          ^
                                   v                          |
                                   `--> awk script -----------'
                                   |                          ^
                                   v                          |
                                   `--> sed script -----------'
                                   |                          ^
                                   v                          |
                                   `--> C/C++ program --------'
                                   |                          ^
                                   v                          |
                                   `--- Java program ---------'
                                   |                          ^
                                   v                          |
                                   :                          :

Shells are the glue of Linux

Linux shells like sh/ksh/bash/... provide input/output/flow-control designation facilities much like the old mainframe Job Control Language... but on steroids! They are Turing complete languages in their own right while being optimized to efficiently pass data and control to and from other executing processes written in any language the O/S supports.

Most Linux applications, regardless what language the bulk of the program is written in, depend on shell scripts and Bash has become the most common. Clicking an icon on the desktop usually runs a short Bash script. That script, either directly or indirectly, knows where all the files needed are and sets variables and command line parameters, finally calling the program. That's a shell's simplest use.

Linux as we know it however would hardly be Linux without the thousands of shell scripts that startup the system, respond to events, control execution priorities and compile, configure and run programs. Many of these are quite large and complex.

Shells provide an infrastructure that lets us use pre-built components that are linked together at run time rather than compile time. Those components are free-standing programs in their own right that can be used alone or in other combinations without recompiling. The syntax for calling them is indistinguishable from that of a Bash builtin command, and there are in fact numerous builtin commands for which there is also a stand-alone executable on the system, often having additional options.

There is no language-wide difference between Python and Bash in performance. It entirely depends on how each is coded and which external tools are called.

Any of the well known tools like awk, sed, grep, bc, dc, tr, etc. will leave doing those operations in either language in the dust. Bash then is preferred for anything without a graphical user interface since it is easier and more efficient to call and pass data back from a tool like those with Bash than Python.


It depends on which programs the Bash shell script calls and their suitability for the subtask they are given whether the overall throughput and/or responsiveness will be better or worse than the equivalent Python. To complicate matters Python, like most languages, can also call other executables, though it is more cumbersome and thus not as often used.

User Interface

One area where Python is the clear winner is user interface. That makes it an excellent language for building local or client-server applications as it natively supports GTK graphics and is far more intuitive than Bash.

Bash only understands text. Other tools must be called for a GUI and data passed back from them. A Python script is one option. Faster but less flexible options are the binaries like YAD, Zenity, and GTKDialog.

While shells like Bash work well with GUIs like Yad, GtkDialog (embedded XML-like interface to GTK+ functions), dialog, and xmessage, Python is much more capable and so better for complex GUI windows.


Building with shell scripts is like assembling a computer with off-the-shelf components the way desktop PCs are.

Building with Python, C++ or most any other language is more like building a computer by soldering the chips (libraries) and other electronic parts together the way smartphones are.

The best results are usually obtained by using a combination of languages where each can do what they do best. One developer calls this "polyglot programming".

How to convert Django Model object to dict with its fields and values?

just vars(obj) , it will state the whole values of the object

>>> obj_attrs = vars(obj)
>>> obj_attrs
 {'_file_data_cache': <FileData: Data>,
  '_state': <django.db.models.base.ModelState at 0x7f5c6733bad0>,
  'aggregator_id': 24,
  'amount': 5.0,
  'biller_id': 23,
  'datetime': datetime.datetime(2018, 1, 31, 18, 43, 58, 933277, tzinfo=<UTC>),
  'file_data_id': 797719,

You can add this also

>>> keys = obj_attrs.keys()
>>> temp = [obj_attrs.pop(key) if key.startswith('_') else None for key in keys]
>>> del temp
>>> obj_attrs
    'aggregator_id': 24,
    'amount': 5.0,
    'biller_id': 23,
    'datetime': datetime.datetime(2018, 1, 31, 18, 43, 58, 933277, tzinfo=<UTC>),
    'file_data_id': 797719,

How to check the gradle version in Android Studio?

File->Project Structure->Project pane->"Android plugin version".

Make sure you don't confuse the Gradle version with the Android plugin version. The former is the build system itself, the latter is the plugin to the build system that knows how to build Android projects

Swift Beta performance: sorting arrays

tl;dr Swift 1.0 is now as fast as C by this benchmark using the default release optimisation level [-O].

Here is an in-place quicksort in Swift Beta:

func quicksort_swift(inout a:CInt[], start:Int, end:Int) {
    if (end - start < 2){
    var p = a[start + (end - start)/2]
    var l = start
    var r = end - 1
    while (l <= r){
        if (a[l] < p){
            l += 1
        if (a[r] > p){
            r -= 1
        var t = a[l]
        a[l] = a[r]
        a[r] = t
        l += 1
        r -= 1
    quicksort_swift(&a, start, r + 1)
    quicksort_swift(&a, r + 1, end)

And the same in C:

void quicksort_c(int *a, int n) {
    if (n < 2)
    int p = a[n / 2];
    int *l = a;
    int *r = a + n - 1;
    while (l <= r) {
        if (*l < p) {
        if (*r > p) {
        int t = *l;
        *l++ = *r;
        *r-- = t;
    quicksort_c(a, r - a + 1);
    quicksort_c(l, a + n - l);

Both work:

var a_swift:CInt[] = [0,5,2,8,1234,-1,2]
var a_c:CInt[] = [0,5,2,8,1234,-1,2]

quicksort_swift(&a_swift, 0, a_swift.count)
quicksort_c(&a_c, CInt(a_c.count))

// [-1, 0, 2, 2, 5, 8, 1234]
// [-1, 0, 2, 2, 5, 8, 1234]

Both are called in the same program as written.

var x_swift = CInt[](count: n, repeatedValue: 0)
var x_c = CInt[](count: n, repeatedValue: 0)
for var i = 0; i < n; ++i {
    x_swift[i] = CInt(random())
    x_c[i] = CInt(random())

let swift_start:UInt64 = mach_absolute_time();
quicksort_swift(&x_swift, 0, x_swift.count)
let swift_stop:UInt64 = mach_absolute_time();

let c_start:UInt64 = mach_absolute_time();
quicksort_c(&x_c, CInt(x_c.count))
let c_stop:UInt64 = mach_absolute_time();

This converts the absolute times to seconds:

static const uint64_t NANOS_PER_USEC = 1000ULL;
static const uint64_t NANOS_PER_MSEC = 1000ULL * NANOS_PER_USEC;
static const uint64_t NANOS_PER_SEC = 1000ULL * NANOS_PER_MSEC;

mach_timebase_info_data_t timebase_info;

uint64_t abs_to_nanos(uint64_t abs) {
    if ( timebase_info.denom == 0 ) {
    return abs * timebase_info.numer  / timebase_info.denom;

double abs_to_seconds(uint64_t abs) {
    return abs_to_nanos(abs) / (double)NANOS_PER_SEC;

Here is a summary of the compiler's optimazation levels:

[-Onone] no optimizations, the default for debug.
[-O]     perform optimizations, the default for release.
[-Ofast] perform optimizations and disable runtime overflow checks and runtime type checks.

Time in seconds with [-Onone] for n=10_000:

Swift:            0.895296452
C:                0.001223848

Here is Swift's builtin sort() for n=10_000:

Swift_builtin:    0.77865783

Here is [-O] for n=10_000:

Swift:            0.045478346
C:                0.000784666
Swift_builtin:    0.032513488

As you can see, Swift's performance improved by a factor of 20.

As per mweathers' answer, setting [-Ofast] makes the real difference, resulting in these times for n=10_000:

Swift:            0.000706745
C:                0.000742374
Swift_builtin:    0.000603576

And for n=1_000_000:

Swift:            0.107111846
C:                0.114957179
Swift_sort:       0.092688548

For comparison, this is with [-Onone] for n=1_000_000:

Swift:            142.659763258
C:                0.162065333
Swift_sort:       114.095478272

So Swift with no optimizations was almost 1000x slower than C in this benchmark, at this stage in its development. On the other hand with both compilers set to [-Ofast] Swift actually performed at least as well if not slightly better than C.

It has been pointed out that [-Ofast] changes the semantics of the language, making it potentially unsafe. This is what Apple states in the Xcode 5.0 release notes:

A new optimization level -Ofast, available in LLVM, enables aggressive optimizations. -Ofast relaxes some conservative restrictions, mostly for floating-point operations, that are safe for most code. It can yield significant high-performance wins from the compiler.

They all but advocate it. Whether that's wise or not I couldn't say, but from what I can tell it seems reasonable enough to use [-Ofast] in a release if you're not doing high-precision floating point arithmetic and you're confident no integer or array overflows are possible in your program. If you do need high performance and overflow checks / precise arithmetic then choose another language for now.


n=10_000 with [-O]:

Swift:            0.019697268
C:                0.000718064
Swift_sort:       0.002094721

Swift in general is a bit faster and it looks like Swift's built-in sort has changed quite significantly.



Swift:   0.678056695
C:       0.000973914


Swift:   0.001158492
C:       0.001192406


Swift:   0.000827764
C:       0.001078914

Shortest way to print current year in a website

Here's the ultimate shortest most responsible version that even works both AD and BC.

[drum rolls...]

<script>document.write(Date().split` `[3])</script>

That's it. 6 Bytes shorter than the accepted answer.

If you need to be ES5 compatible, you can settle for:

<script>document.write(Date().split(' ')[3])</script>

How to avoid the need to specify the WSDL location in a CXF or JAX-WS generated webservice client?

@Martin Devillers solution works fine. For completeness, providing the steps below:

  1. Put your wsdl to resource directory like : src/main/resource
  2. In pom file, add both wsdlDirectory and wsdlLocation(don't miss / at the beginning of wsdlLocation), like below. While wsdlDirectory is used to generate code and wsdlLocation is used at runtime to create dynamic proxy.

  3. Then in your java code(with no-arg constructor):

    MyPort myPort = new MyPortService().getMyPort();
  4. Here is the full code generation part in pom file, with fluent api in generated code.


Unclosed Character Literal error

Java uses double quotes for "String" and single quotes for 'C'haracters.

Alternative to a goto statement in Java

The easiest is:

int label = 0;
loop:while(true) {
    switch(state) {
        case 0:
            // Some code
            state = 5;

        case 2:
            // Some code
            state = 4;
            break loop;

Declaring variables in Excel Cells

You can name cells. This is done by clicking the Name Box (that thing next to the formula bar which says "A1" for example) and typing a name, such as, "myvar". Now you can use that name instead of the cell reference:

= myvar*25

What size should TabBar images be?

30x30 is points, which means 30px @1x, 60px @2x, not somewhere in-between. Also, it's not a great idea to embed the title of the tab into the image—you're going to have pretty poor accessibility and localization results like that.

How do I configure the proxy settings so that Eclipse can download new plugins?

Manual + disable SOCKS didn't work for me (still tried to use SOCKS and my company proxy refused it),
Native + changed eclipse.ini worked for me


These settings require IDE restart (sometimes with -clean -refresh command line options).

Java8, Eclipse Neon3, slow proxy server:


Java logical operator short-circuiting

Logical OR :- returns true if at least one of the operands evaluate to true. Both operands are evaluated before apply the OR operator.

Short Circuit OR :- if left hand side operand returns true, it returns true without evaluating the right hand side operand.

How to upload and parse a CSV file in php

This can be done in a much simpler manner now.

$tmpName = $_FILES['csv']['tmp_name'];
$csvAsArray = array_map('str_getcsv', file($tmpName));

This will return you a parsed array of your CSV data. Then you can just loop through it using a foreach statement.

Forking vs. Branching in GitHub

You cannot always make a branch or pull an existing branch and push back to it, because you are not registered as a collaborator for that specific project.

Forking is nothing more than a clone on the GitHub server side:

  • without the possibility to directly push back
  • with fork queue feature added to manage the merge request

You keep a fork in sync with the original project by:

  • adding the original project as a remote
  • fetching regularly from that original project
  • rebase your current development on top of the branch of interest you got updated from that fetch.

The rebase allows you to make sure your changes are straightforward (no merge conflict to handle), making your pulling request that more easy when you want the maintainer of the original project to include your patches in his project.

The goal is really to allow collaboration even though direct participation is not always possible.

The fact that you clone on the GitHub side means you have now two "central" repository ("central" as "visible from several collaborators).
If you can add them directly as collaborator for one project, you don't need to manage another one with a fork.

fork on GitHub

The merge experience would be about the same, but with an extra level of indirection (push first on the fork, then ask for a pull, with the risk of evolutions on the original repo making your fast-forward merges not fast-forward anymore).
That means the correct workflow is to git pull --rebase upstream (rebase your work on top of new commits from upstream), and then git push --force origin, in order to rewrite the history in such a way your own commits are always on top of the commits from the original (upstream) repo.

See also:

Reflection - get attribute name and value on property

Use typeof(Book).GetProperties() to get an array of PropertyInfo instances. Then use GetCustomAttributes() on each PropertyInfo to see if any of them have the Author Attribute type. If they do, you can get the name of the property from the property info and the attribute values from the attribute.

Something along these lines to scan a type for properties that have a specific attribute type and to return data in a dictionary (note that this can be made more dynamic by passing types into the routine):

public static Dictionary<string, string> GetAuthors()
    Dictionary<string, string> _dict = new Dictionary<string, string>();

    PropertyInfo[] props = typeof(Book).GetProperties();
    foreach (PropertyInfo prop in props)
        object[] attrs = prop.GetCustomAttributes(true);
        foreach (object attr in attrs)
            AuthorAttribute authAttr = attr as AuthorAttribute;
            if (authAttr != null)
                string propName = prop.Name;
                string auth = authAttr.Name;

                _dict.Add(propName, auth);

    return _dict;

Get size of a View in React Native

Here is the code to get the Dimensions of the complete view of the device.

var windowSize = Dimensions.get("window");

Use it like this:


update columns values with column of another table based on condition

This will surely work:

UPDATE table1
SET table1.price=(SELECT table2.price
  FROM table2
  WHERE AND table2.item=table1.item);

What's a decent SFTP command-line client for windows?

WinSCP can be called from batch file:

"C:\Program Files\WinSCP\WinSCP.exe" /console

Example commands:

option batch on 
option confirm off  
option transfer binary 
open sftp://username@hostname:port -hostkey="ssh-rsa " 

IOError: [Errno 22] invalid mode ('r') or filename: 'c:\\Python27\test.txt'

\ is an escape character in Python. \t gets interpreted as a tab. If you need \ character in a string, you have to use \\.

Your code should be:

Why do people use Heroku when AWS is present? What distinguishes Heroku from AWS?

Heroku is like subset of AWS. It is just platform as a service, while AWS can be implemented as anything and at any level.

The implementation depends on what the business requirement. If it fits in either, use accordingly.

invalid new-expression of abstract class type

for others scratching their heads, I came across this error because I had innapropriately const-qualified one of the arguments to a method in a base class, so the derived class member functions were not over-riding it. so make sure you don't have something like

class Base 
      virtual void foo(int a, const int b) = 0;
class D: public Base 
     void foo(int a, int b){};

Generating a WSDL from an XSD file

You cannot - a XSD describes the DATA aspects e.g. of a webservice - the WSDL describes the FUNCTIONS of the web services (method calls). You cannot typically figure out the method calls from your data alone.

These are really two separate, distinctive parts of the equation. For simplicity's sake you would often import your XSD definitions into the WSDL in the <wsdl:types> tag.

(thanks to Cheeso for pointing out my inaccurate usage of terms)

Jquery in React is not defined

I just want to receive ajax request, but the problem is that jQuery is not defined in React.

Then don't use it. Use Fetch and have a look at Fetch polyfill in React not completely working in IE 11 to see example of alternative ways to get it running

Something like this

const that = this; 
  .then(function(response) { return response.json(); }) 
  .then(function(myJson) { 
     that.setState({data: myJson}); // for example

How to execute an external program from within Node.js?

The simplest way is:

const { exec } = require("child_process")

unref is necessary to end your process without waiting for "yourApp"

Here are the exec docs

Android ListView with different layouts for each row

Since you know how many types of layout you would have - it's possible to use those methods.

getViewTypeCount() - this methods returns information how many types of rows do you have in your list

getItemViewType(int position) - returns information which layout type you should use based on position

Then you inflate layout only if it's null and determine type using getItemViewType.

Look at this tutorial for further information.

To achieve some optimizations in structure that you've described in comment I would suggest:

  • Storing views in object called ViewHolder. It would increase speed because you won't have to call findViewById() every time in getView method. See List14 in API demos.
  • Create one generic layout that will conform all combinations of properties and hide some elements if current position doesn't have it.

I hope that will help you. If you could provide some XML stub with your data structure and information how exactly you want to map it into row, I would be able to give you more precise advise. By pixel.

How to declare an array of strings in C++?

Declare an array of strings in C++ like this : char array_of_strings[][]

For example : char array_of_strings[200][8192];

will hold 200 strings, each string having the size 8kb or 8192 bytes.

use strcpy(line[i],tempBuffer); to put data in the array of strings.

Sequence contains more than one element

Use FirstOrDefault insted of SingleOrDefault..

SingleOrDefault returns a SINGLE element or null if no element is found. If 2 elements are found in your Enumerable then it throws the exception you are seeing

FirstOrDefault returns the FIRST element it finds or null if no element is found. so if there are 2 elements that match your predicate the second one is ignored

   public int GetPackage(int id,int emp)
             int getpackages=Convert.ToInt32(EmployerSubscriptionPackage.GetAllData().Where(x
   => x.SubscriptionPackageID ==`enter code here` id && x.EmployerID==emp ).FirstOrDefault().ID);
               return getpackages;

 1. var EmployerId = Convert.ToInt32(Session["EmployerId"]);
               var getpackage = GetPackage(employerSubscription.ID, EmployerId);

How do I determine the current operating system with Node.js

With Node.js v6 (and above) there is a dedicated os module, which provides a number of operating system-related utility methods.

On my Windows 10 machine it reports the following:

var os = require('os');

console.log(os.type()); // "Windows_NT"
console.log(os.release()); // "10.0.14393"
console.log(os.platform()); // "win32"

You can read it's full documentation here:

Is there any way to redraw tmux window when switching smaller monitor to bigger one?

I just ran into this problem and stumbled across a different situation. Although it's probably just a unicorn, I thought I'd lay it out.

I had one session that was smaller, and I noticed that the font sizes were different: the smaller session had the smaller fonts. Apparently, I had changed window font sizes for some reason.

So in OS X, I just did Cmd-+ on the smaller sized session, and it snapped back into place.

Any way to make a WPF textblock selectable?

All the answers here are just using a TextBox or trying to implement text selection manually, which leads to poor performance or non-native behaviour (blinking caret in TextBox, no keyboard support in manual implementations etc.)

After hours of digging around and reading the WPF source code, I instead discovered a way of enabling the native WPF text selection for TextBlock controls (or really any other controls). Most of the functionality around text selection is implemented in System.Windows.Documents.TextEditor system class.

To enable text selection for your control you need to do two things:

  1. Call TextEditor.RegisterCommandHandlers() once to register class event handlers

  2. Create an instance of TextEditor for each instance of your class and pass the underlying instance of your System.Windows.Documents.ITextContainer to it

There's also a requirement that your control's Focusable property is set to True.

This is it! Sounds easy, but unfortunately TextEditor class is marked as internal. So I had to write a reflection wrapper around it:

class TextEditorWrapper
    private static readonly Type TextEditorType = Type.GetType("System.Windows.Documents.TextEditor, PresentationFramework, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35");
    private static readonly PropertyInfo IsReadOnlyProp = TextEditorType.GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);
    private static readonly PropertyInfo TextViewProp = TextEditorType.GetProperty("TextView", BindingFlags.Instance | BindingFlags.NonPublic);
    private static readonly MethodInfo RegisterMethod = TextEditorType.GetMethod("RegisterCommandHandlers", 
        BindingFlags.Static | BindingFlags.NonPublic, null, new[] { typeof(Type), typeof(bool), typeof(bool), typeof(bool) }, null);

    private static readonly Type TextContainerType = Type.GetType("System.Windows.Documents.ITextContainer, PresentationFramework, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35");
    private static readonly PropertyInfo TextContainerTextViewProp = TextContainerType.GetProperty("TextView");

    private static readonly PropertyInfo TextContainerProp = typeof(TextBlock).GetProperty("TextContainer", BindingFlags.Instance | BindingFlags.NonPublic);

    public static void RegisterCommandHandlers(Type controlType, bool acceptsRichContent, bool readOnly, bool registerEventListeners)
        RegisterMethod.Invoke(null, new object[] { controlType, acceptsRichContent, readOnly, registerEventListeners });

    public static TextEditorWrapper CreateFor(TextBlock tb)
        var textContainer = TextContainerProp.GetValue(tb);

        var editor = new TextEditorWrapper(textContainer, tb, false);
        IsReadOnlyProp.SetValue(editor._editor, true);
        TextViewProp.SetValue(editor._editor, TextContainerTextViewProp.GetValue(textContainer));

        return editor;

    private readonly object _editor;

    public TextEditorWrapper(object textContainer, FrameworkElement uiScope, bool isUndoEnabled)
        _editor = Activator.CreateInstance(TextEditorType, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.CreateInstance, 
            null, new[] { textContainer, uiScope, isUndoEnabled }, null);

I also created a SelectableTextBlock derived from TextBlock that takes the steps noted above:

public class SelectableTextBlock : TextBlock
    static SelectableTextBlock()
        FocusableProperty.OverrideMetadata(typeof(SelectableTextBlock), new FrameworkPropertyMetadata(true));
        TextEditorWrapper.RegisterCommandHandlers(typeof(SelectableTextBlock), true, true, true);

        // remove the focus rectangle around the control
        FocusVisualStyleProperty.OverrideMetadata(typeof(SelectableTextBlock), new FrameworkPropertyMetadata((object)null));

    private readonly TextEditorWrapper _editor;

    public SelectableTextBlock()
        _editor = TextEditorWrapper.CreateFor(this);

Another option would be to create an attached property for TextBlock to enable text selection on demand. In this case, to disable the selection again, one needs to detach a TextEditor by using the reflection equivalent of this code:

_editor.TextContainer.TextView = null;
_editor = null;

How do I make a PHP form that submits to self?

The proper way would be to use $_SERVER["PHP_SELF"] (in conjunction with htmlspecialchars to avoid possible exploits). You can also just skip the action= part empty, which is not W3C valid, but currently works in most (all?) browsers - the default is to submit to self if it's empty.

Here is an example form that takes a name and email, and then displays the values you have entered upon submit:

<?php if (!empty($_POST)): ?>
    Welcome, <?php echo htmlspecialchars($_POST["name"]); ?>!<br>
    Your email is <?php echo htmlspecialchars($_POST["email"]); ?>.<br>
<?php else: ?>
    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
        Name: <input type="text" name="name"><br>
        Email: <input type="text" name="email"><br>
        <input type="submit">
<?php endif; ?>

What are the Ruby modes and options?

In Ruby IO module documentation, I suppose.

Mode |  Meaning
"r"  |  Read-only, starts at beginning of file  (default mode).
"r+" |  Read-write, starts at beginning of file.
"w"  |  Write-only, truncates existing file
     |  to zero length or creates a new file for writing.
"w+" |  Read-write, truncates existing file to zero length
     |  or creates a new file for reading and writing.
"a"  |  Write-only, starts at end of file if file exists,
     |  otherwise creates a new file for writing.
"a+" |  Read-write, starts at end of file if file exists,
     |  otherwise creates a new file for reading and
     |  writing.
"b"  |  Binary file mode (may appear with
     |  any of the key letters listed above).
     |  Suppresses EOL <-> CRLF conversion on Windows. And
     |  sets external encoding to ASCII-8BIT unless explicitly
     |  specified.
"t"  |  Text file mode (may appear with
     |  any of the key letters listed above except "b").

Does Index of Array Exist

Test the length

int index = 25;
if(index < array.Length)
    //it exists

scikit-learn random state in splitting dataset

For multiple times of execution of our model, random state make sure that data values will be same for training and testing data sets. It fixes the order of data for train_test_split

Fast way to concatenate strings in nodeJS/JavaScript

The question is already answered, however when I first saw it I thought of NodeJS Buffer. But it is way slower than the +, so it is likely that nothing can be faster than + in string concetanation.

Tested with the following code:

function a(){
    var s = "hello";
    var p = "world";
    s = s + p;
    return s;

function b(){
    var s = new Buffer("hello");
    var p = new Buffer("world");
    s = Buffer.concat([s,p]);
    return s;

var times = 100000;

var t1 = new Date();
for( var i = 0; i < times; i++){

var t2 = new Date();
console.log("Normal took: " + (t2-t1) + " ms.");
for ( var i = 0; i < times; i++){

var t3 = new Date();

console.log("Buffer took: " + (t3-t2) + " ms.");


Normal took: 4 ms.
Buffer took: 458 ms.

System.web.mvc missing

in VS 2017 I cleaned the solution and rebuilt it and that fixed it

boolean in an if statement

In Javascript the idea of boolean is fairly ambiguous. Consider this:

 var bool = 0 
 if(bool){..} //evaluates to false

 if(//uninitialized var) //evaluates to false

So when you're using an if statement, (or any other control statement), one does not have to use a "boolean" type var. Therefore, in my opinion, the "=== true" part of your statement is unnecessary if you know it is a boolean, but absolutely necessary if your value is an ambiguous "truthy" var. More on booleans in javscript can be found here.

org.apache.catalina.core.StandardContext startInternal SEVERE: Error listenerStart

Select "all project" and right click

Maven-> Update project

JQuery: How to get selected radio button value?

$('input[name=myradiobutton]:radio:checked') will get you the selected radio button $('input[name=myradiobutton]:radio:not(:checked)') will get you the unselected radio buttons

Using this you can do this


Update: After reading your Update I think I understand You will want to do something like this

var myRadioValue;

function radioValue(jqRadioButton){
  if (jqRadioButton.length) {
    myRadioValue = jqRadioButton.val();
  else {
    myRadioValue = 0;

$(document).ready(function () {
  $('input[name=myradiobutton]:radio').click(function () {   //Hook the click event for selected elements

  radioValue($('input[name=myradiobutton]:radio:checked')); //check for value on page load

Access VBA | How to replace parts of a string with another string

Since the string "North" might be the beginning of a street name, e.g. "Northern Boulevard", street directions are always between the street number and the street name, and separated from street number and street name.

Public Function strReplace(varValue As Variant) as Variant

Select Case varValue

    Case "Avenue"
        strReplace = "Ave"

    Case " North "
        strReplace = " N "

    Case Else
        strReplace = varValue

End Select

End Function

How to set delay in vbscript

If you're trying to simulate a sleep delay in VBScript but WScript is not available (eg: your script is called from Microsoft's BGInfo tool), then try the following approach.

The example below will delay until 10 seconds from the moment the instruction is processed:

Dim dteWait
dteWait = DateAdd("s", 10, Now())
Do Until (Now() > dteWait)

Print all day-dates between two dates

import datetime

begin =, 8, 15)
end =, 9, 15)

next_day = begin
while True:
    if next_day > end:
    print next_day
    next_day += datetime.timedelta(days=1)

Can I access variables from another file?

Using Node.js you can export the variable via module.

const colorCode = {
    black: "#000",
    white: "#fff"
module.exports = { colorCode };

Then, import the module/variable in second file using require.

const { colorCode } = require('./first.js')

You can use the import and export aproach from ES6 using Webpack/Babel, but in Node.js you need to enable a flag, and uses the .mjs extension.

How to delete/remove nodes on Firebase

To remove a record.

 var db = firebase.database();                   
 var ref = db.ref(); 
 var survey=db.ref(path+'/'+path);    //Eg path is company/employee                
 survey.child(key).remove();          //Eg key is employee id

PHP "php://input" vs $_POST

First, a basic truth about PHP.

PHP was not designed to explicitly give you a pure REST (GET, POST, PUT, PATCH, DELETE) like interface for handling HTTP requests.

However, the $_SERVER, $_COOKIE, $_POST, $_GET, and $_FILES superglobals, and the function filter_input_array() are very useful for the average person's / layman's needs.

The number one hidden advantage of $_POST (and $_GET) is that your input data is url-decoded automatically by PHP. You never even think about having to do it, especially for query string parameters within a standard GET request, or HTTP body data submitted with a POST request.

Other HTTP Request Methods

Those studying the underlying HTTP protocol and its various request methods come to understand that there are many HTTP request methods, including the often referenced PUT, PATCH (not used in Google's Apigee), and DELETE.

In PHP, there are no superglobals or input filter functions for getting HTTP request body data when POST is not used. What are disciples of Roy Fielding to do? ;-)

However, then you learn more ...

That being said, as you advance in your PHP programming knowledge and want to use JavaScript's XmlHttpRequest object (jQuery for some), you come to see the limitation of this scheme.

$_POST limits you to the use of two media types in the HTTP Content-Type header:

  1. application/x-www-form-urlencoded, and
  2. multipart/form-data

Thus, if you want to send data values to PHP on the server, and have it show up in the $_POST superglobal, then you must urlencode it on the client-side and send said data as key/value pairs--an inconvenient step for novices (especially when trying to figure out if different parts of the URL require different forms of urlencoding: normal, raw, etc..).

For all you jQuery users, the $.ajax() method is converting your JSON to URL encoded key/value pairs before transmitting them to the server. You can override this behavior by setting processData: false. Just read the $.ajax() documentation, and don't forget to send the correct media type in the Content-Type header.

php://input, but ...

Even if you use php://input instead of $_POST for your HTTP POST request body data, it will not work with an HTTP Content-Type of multipart/form-data This is the content type that you use on an HTML form when you want to allow file uploads!

<form enctype="multipart/form-data" accept-charset="utf-8" action="post">
    <input type="file" name="resume">

Therefore, in traditional PHP, to deal with a diversity of content types from an HTTP POST request, you will learn to use $_POST or filter_input_array(POST), $_FILES, and php://input. There is no way to just use one, universal input source for HTTP POST requests in PHP.

You cannot get files through $_POST, filter_input_array(POST), or php://input, and you cannot get JSON/XML/YAML in either filter_input_array(POST) or $_POST.

PHP Manual: php://input

php://input is a read-only stream that allows you to read raw data from the request body...php://input is not available with enctype="multipart/form-data".

PHP Frameworks to the rescue?

PHP frameworks like Codeigniter 4 and Laravel use a facade to provide a cleaner interface (IncomingRequest or Request objects) to the above. This is why professional PHP developers use frameworks instead of raw PHP.

Of course, if you like to program, you can devise your own facade object to provide what frameworks do. It is because I have taken time to investigate this issue that I am able to write this answer.

URL encoding? What the heck!!!???

Typically, if you are doing a normal, synchronous (when the entire page redraws) HTTP requests with an HTML form, the user-agent (web browser) will urlencode your form data for you. If you want to do an asynchronous HTTP requests using the XmlHttpRequest object, then you must fashion a urlencoded string and send it, if you want that data to show up in the $_POST superglobal.

How in touch are you with JavaScript? :-)

Converting from a JavaScript array or object to a urlencoded string bothers many developers (even with new APIs like Form Data). They would much rather just be able to send JSON, and it would be more efficient for the client code to do so.

Remember (wink, wink), the average web developer does not learn to use the XmlHttpRequest object directly, global functions, string functions, array functions, and regular expressions like you and I ;-). Urlencoding for them is a nightmare. ;-)

PHP, what gives?

PHP's lack of intuitive XML and JSON handling turns many people off. You would think it would be part of PHP by now (sigh).

So many media types (MIME types in the past)

XML, JSON, and YAML all have media types that can be put into an HTTP Content-Type header.

  • application/xml
  • applicaiton/json
  • application/yaml (although IANA has no official designation listed)

Look how many media-types (formerly, MIME types) are defined by IANA.

Look how many HTTP headers there are.

php://input or bust

Using the php://input stream allows you to circumvent the baby-sitting / hand holding level of abstraction that PHP has forced on the world. :-) With great power comes great responsibility!

Now, before you deal with data values streamed through php://input, you should / must do a few things.

  1. Determine if the correct HTTP method has been indicated (GET, POST, PUT, PATCH, DELETE, ...)
  2. Determine if the HTTP Content-Type header has been transmitted.
  3. Determine if the value for the Content-Type is the desired media type.
  4. Determine if the data sent is well formed XML / JSON / YAML / etc.
  5. If necessary, convert the data to a PHP datatype: array or object.
  6. If any of these basic checks or conversions fails, throw an exception!

What about the character encoding?

AH, HA! Yes, you might want the data stream being sent into your application to be UTF-8 encoded, but how can you know if it is or not?

Two critical problems.

  1. You do not know how much data is coming through php://input.
  2. You do not know for certain the current encoding of the data stream.

Are you going to attempt to handle stream data without knowing how much is there first? That is a terrible idea. You cannot rely exclusively on the HTTP Content-Length header for guidance on the size of streamed input because it can be spoofed.

You are going to need a:

  1. Stream size detection algorithm.
  2. Application defined stream size limits (Apache / Nginx / PHP limits may be too broad).

Are you going to attempt to convert stream data to UTF-8 without knowing the current encoding of the stream? How? The iconv stream filter (iconv stream filter example) seems to want a starting and ending encoding, like this.


Thus, if you are conscientious, you will need:

  1. Stream encoding detection algorithm.
  2. Dynamic / runtime stream filter definition algorithm (because you cannot know the starting encoding a priori).

(Update: 'convert.iconv.UTF-8/UTF-8' will force everything to UTF-8, but you still have to account for characters that the iconv library might not know how to translate. In other words, you have to some how define what action to take when a character cannot be translated: 1) Insert a dummy character, 2) Fail / throw and exception).

You cannot rely exclusively on the HTTP Content-Encoding header, as this might indicate something like compression as in the following. This is not what you want to make a decision off of in regards to iconv.

Content-Encoding: gzip

Therefore, the general steps might be ...

Part I: HTTP Request Related

  1. Determine if the correct HTTP method has been indicated (GET, POST, PUT, PATCH, DELETE, ...)
  2. Determine if the HTTP Content-Type header has been transmitted.
  3. Determine if the value for the Content-Type is the desired media type.

Part II: Stream Data Related

  1. Determine the size of the input stream (optional, but recommended).
  2. Determine the encoding of the input stream.
  3. If necessary, convert the input stream to the desired character encoding (UTF-8).
  4. If necessary, reverse any application level compression or encryption, and then repeat steps 4, 5, and 6.

Part III: Data Type Related

  1. Determine if the data sent is well formed XML / JSON / YMAL / etc.

(Remember, the data can still be a URL encoded string which you must then parse and URL decode).

  1. If necessary, convert the data to a PHP datatype: array or object.

Part IV: Data Value Related

  1. Filter input data.

  2. Validate input data.

Now do you see?

The $_POST superglobal, along with php.ini settings for limits on input, are simpler for the layman. However, dealing with character encoding is much more intuitive and efficient when using streams because there is no need to loop through superglobals (or arrays, generally) to check input values for the proper encoding.

HTML Image not displaying, while the src url works

You can try just putting the image in the source directory. You'd link it by replacing the file path with src="../imagenamehere.fileextension In your case, j3evn.jpg.

How to stop (and restart) the Rails Server?

Now in rails 5 yu can do:

rails restart

This print by rails --tasks

Restart app by touching tmp/restart.txt

I think that is usefully if you run rails as a demon

How to secure RESTful web services?

If choosing between OAuth versions, go with OAuth 2.0.

OAuth bearer tokens should only be used with a secure transport.

OAuth bearer tokens are only as secure or insecure as the transport that encrypts the conversation. HTTPS takes care of protecting against replay attacks, so it isn't necessary for the bearer token to also guard against replay.

While it is true that if someone intercepts your bearer token they can impersonate you when calling the API, there are plenty of ways to mitigate that risk. If you give your tokens a long expiration period and expect your clients to store the tokens locally, you have a greater risk of tokens being intercepted and misused than if you give your tokens a short expiration, require clients to acquire new tokens for every session, and advise clients not to persist tokens.

If you need to secure payloads that pass through multiple participants, then you need something more than HTTPS/SSL, since HTTPS/SSL only encrypts one link of the graph. This is not a fault of OAuth.

Bearer tokens are easy to for clients to obtain, easy for clients to use for API calls and are widely used (with HTTPS) to secure public facing APIs from Google, Facebook, and many other services.

Difference between Python's Generators and Iterators

I am writing specifically for Python newbies in a very simple way, though deep down Python does so many things.

Let’s start with the very basic:

Consider a list,

l = [1,2,3]

Let’s write an equivalent function:

def f():
    return [1,2,3]

o/p of print(l): [1,2,3] & o/p of print(f()) : [1,2,3]

Let’s make list l iterable: In python list is always iterable that means you can apply iterator whenever you want.

Let’s apply iterator on list:

iter_l = iter(l) # iterator applied explicitly

Let’s make a function iterable, i.e. write an equivalent generator function. In python as soon as you introduce the keyword yield; it becomes a generator function and iterator will be applied implicitly.

Note: Every generator is always iterable with implicit iterator applied and here implicit iterator is the crux So the generator function will be:

def f():
  yield 1 
  yield 2
  yield 3

iter_f = f() # which is iter(f) as iterator is already applied implicitly

So if you have observed, as soon as you made function f a generator, it is already iter(f)


l is the list, after applying iterator method "iter" it becomes, iter(l)

f is already iter(f), after applying iterator method "iter" it becomes, iter(iter(f)), which is again iter(f)

It's kinda you are casting int to int(x) which is already int and it will remain int(x).

For example o/p of :



<class 'list_iterator'>

Never forget this is Python and not C or C++

Hence the conclusion from above explanation is:

list l ~= iter(l)

generator function f == iter(f)

Get the current year in JavaScript

You can simply use javascript like this. Otherwise you can use momentJs Plugin which helps in large application.

new Date().getDate()          // Get the day as a number (1-31)
new Date().getDay()           // Get the weekday as a number (0-6)
new Date().getFullYear()      // Get the four digit year (yyyy)
new Date().getHours()         // Get the hour (0-23)
new Date().getMilliseconds()  // Get the milliseconds (0-999)
new Date().getMinutes()       // Get the minutes (0-59)
new Date().getMonth()         // Get the month (0-11)
new Date().getSeconds()       // Get the seconds (0-59)
new Date().getTime()          // Get the time (milliseconds since January 1, 1970)

function generate(type,element)_x000D_
 var value = "";_x000D_
 var date = new Date();_x000D_
 switch (type) {_x000D_
  case "Date":_x000D_
   value = date.getDate();  // Get the day as a number (1-31)_x000D_
  case "Day":_x000D_
   value = date.getDay();  // Get the weekday as a number (0-6)_x000D_
  case "FullYear":_x000D_
   value = date.getFullYear(); // Get the four digit year (yyyy)_x000D_
  case "Hours":_x000D_
   value = date.getHours(); // Get the hour (0-23)_x000D_
  case "Milliseconds":_x000D_
   value = date.getMilliseconds(); // Get the milliseconds (0-999)_x000D_
  case "Minutes":_x000D_
   value = date.getMinutes();     // Get the minutes (0-59)_x000D_
  case "Month":_x000D_
   value = date.getMonth(); // Get the month (0-11)_x000D_
  case "Seconds":_x000D_
   value = date.getSeconds(); // Get the seconds (0-59)_x000D_
  case "Time":_x000D_
   value = date.getTime();  // Get the time (milliseconds since January 1, 1970)_x000D_
  list-style-type: none;_x000D_
  padding: 5px;_x000D_
  width: 150px;_x000D_
  margin-left: 100px;_x000D_
<script src=""></script>_x000D_
  <button type="button" onclick="generate('Date',this)">Get Date</button>_x000D_
  <button type="button" onclick="generate('Day',this)">Get Day</button>_x000D_
  <button type="button" onclick="generate('FullYear',this)">Get Full Year</button>_x000D_
  <button type="button" onclick="generate('Hours',this)">Get Hours</button>_x000D_
  <button type="button" onclick="generate('Milliseconds',this)">Get Milliseconds</button>_x000D_
  <button type="button" onclick="generate('Minutes',this)">Get Minutes</button>_x000D_
  <button type="button" onclick="generate('Month',this)">Get Month</button>_x000D_
  <button type="button" onclick="generate('Seconds',this)">Get Seconds</button>_x000D_
  <button type="button" onclick="generate('Time',this)">Get Time</button>_x000D_

Converting NSString to NSDictionary / JSON

Use the following code to get the response object from the AFHTTPSessionManager failure block; then you can convert the generic type into the required data type:

id responseObject = [NSJSONSerialization JSONObjectWithData:(NSData *)error.userInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] options:0 error:nil];

Bash tool to get nth line from a file

This question being tagged Bash, here's the Bash (=4) way of doing: use mapfile with the -s (skip) and -n (count) option.

If you need to get the 42nd line of a file file:

mapfile -s 41 -n 1 ary < file

At this point, you'll have an array ary the fields of which containing the lines of file (including the trailing newline), where we have skipped the first 41 lines (-s 41), and stopped after reading one line (-n 1). So that's really the 42nd line. To print it out:

printf '%s' "${ary[0]}"

If you need a range of lines, say the range 42–666 (inclusive), and say you don't want to do the math yourself, and print them on stdout:

mapfile -s $((42-1)) -n $((666-42+1)) ary < file
printf '%s' "${ary[@]}"

If you need to process these lines too, it's not really convenient to store the trailing newline. In this case use the -t option (trim):

mapfile -t -s $((42-1)) -n $((666-42+1)) ary < file
# do stuff
printf '%s\n' "${ary[@]}"

You can have a function do that for you:

print_file_range() {
    # $1-$2 is the range of file $3 to be printed to stdout
    local ary
    mapfile -s $(($1-1)) -n $(($2-$1+1)) ary < "$3"
    printf '%s' "${ary[@]}"

No external commands, only Bash builtins!

select dept names who have more than 2 employees whose salary is greater than 1000

1:list name of all employee who earn more than RS.100000 in a year.

2:give the name of employee who earn heads the department where employee with employee I.D

What's a quick way to comment/uncomment lines in Vim?

I mark the first and last lines (ma and mb), and then do :'a,'bs/^# //

Why use the params keyword?

Might sound stupid, But Params doesn't allow multidimensional array. Whereas you can pass a multidimensional array to a function.

Max size of URL parameters in _GET

See What is the maximum length of a URL in different browsers?

The length of the url can't be changed in PHP. The linked question is about the URL size limit, you will find what you want.

Create WordPress Page that redirects to another URL

There are 3 ways of doing this:

  1. By changing your 404.php code.
  2. By using wordpress plugins.
  3. By editing your .htaccess file.

Complete tutorial given at

DataGridView - how to set column width?



AngularJS - pass function to directive

How about passing the controller function with bidirectional binding? Then you can use it in the directive exactly the same way as in a regular template (I stripped irrelevant parts for simplicity):

<div ng-controller="testCtrl">

   <!-- pass the function with no arguments -->
   <test color1="color1" update-fn="updateFn"></test>

   angular.module('dr', [])
   .controller("testCtrl", function($scope) {
      $scope.updateFn = function(msg) {
   .directive('test', function() {
      return {
         scope: {
            updateFn: '=' // '=' bidirectional binding
         template: "<button ng-click='updateFn(1337)'>Click</button>"

I landed at this question, because I tried the method above befire, but somehow it didn't work. Now it works perfectly.

how to call url of any other website in php

use curl php library:

direct example: CURL_EXEC:

// create a new cURL resource
$ch = curl_init();

// set URL and other appropriate options
curl_setopt($ch, CURLOPT_URL, "");
curl_setopt($ch, CURLOPT_HEADER, 0);

// grab URL and pass it to the browser

// close cURL resource, and free up system resources

Custom CSS Scrollbar for Firefox

Year 2020 this works

/* Thin Scrollbar */
  scrollbar-color: rgb(210,210,210) rgb(46,54,69) !important;
  scrollbar-width: thin !important;

How to refresh table contents in div using jquery/ajax

You can load HTML page partial, in your case is everything inside div#mytable.

   $( "#mytable" ).load( "your-current-page.html #mytable" );
}, 2000); //refresh every 2 seconds

more information read this

Update Code (if you don't want it auto-refresh)

<button id="refresh-btn">Refresh Table</button>

$(document).ready(function() {

   function RefreshTable() {
       $( "#mytable" ).load( "your-current-page.html #mytable" );

   $("#refresh-btn").on("click", RefreshTable);

   // $("#refresh-btn").on("click", function() {
   //    $( "#mytable" ).load( "your-current-page.html #mytable" );
   // });


How to get element-wise matrix multiplication (Hadamard product) in numpy?

Try this:

a = np.matrix([[1,2], [3,4]])
b = np.matrix([[5,6], [7,8]])

#This would result a 'numpy.ndarray'
result = np.array(a) * np.array(b)

Here, np.array(a) returns a 2D array of type ndarray and multiplication of two ndarray would result element wise multiplication. So the result would be:

result = [[5, 12], [21, 32]]

If you wanna get a matrix, the do it with this:

result = np.mat(result)

'router-outlet' is not a known element

It works for me, when i add following code in app.module.ts

   imports: [

Composer Update Laravel

You can use :

composer self-update --2

To update to 2.0.8 version (Latest stable version)

How can I set the request header for curl?

Just use the -H parameter several times:

curl -H "Accept-Charset: utf-8" -H "Content-Type: application/x-www-form-urlencoded"

Finding elements not in a list

In the case where item and z are sorted iterators, we can reduce the complexity from O(n^2) to O(n+m) by doing this

def iexclude(sorted_iterator, exclude_sorted_iterator):
    next_val = next(exclude_sorted_iterator)
    for item in sorted_iterator:
            while next_val < item:
                next_val = next(exclude_sorted_iterator)
            if item == next_val:
        except StopIteration:
        yield item

If the two are iterators, we also have the opportunity to reduce the memory footprint not storing z (exclude_sorted_iterator) as a list.

When should you use a class vs a struct in C++?

You can use "struct" in C++ if you are writing a library whose internals are C++ but the API can be called by either C or C++ code. You simply make a single header that contains structs and global API functions that you expose to both C and C++ code as this:

// C access Header to a C++ library
#ifdef __cpp
extern "C" {

// Put your C struct's here
struct foo
// NOTE: the typedef is used because C does not automatically generate
// a typedef with the same name as a struct like C++.
typedef struct foo foo;

// Put your C API functions here
void bar(foo *fun);

#ifdef __cpp

Then you can write a function bar() in a C++ file using C++ code and make it callable from C and the two worlds can share data through the declared struct's. There are other caveats of course when mixing C and C++ but this is a simplified example.

How to safely call an async method in C# without await

I end up with this solution :

public async Task MyAsyncMethod()
    // do some stuff async, don't return any data

public string GetStringData()
    // Run async, no warning, exception are catched
    return "hello world";

private void RunAsync(Task task)
    task.ContinueWith(t =>
        ILog log = ServiceLocator.Current.GetInstance<ILog>();
        log.Error("Unexpected Error", t.Exception);

    }, TaskContinuationOptions.OnlyOnFaulted);

Using jQuery to build table rows from AJAX response(json)

jQuery.html takes string or callback as input, not sure how your example is working... Try something like $('<tr>').append($('<td>' + item.rank + '</td>').append ... And you have some definite problems with tags fromation. It should be $('<tr/>') and $('<td/>')

Getting a list of associative array keys

Simple jQuery way:

This is what I use:

DictionaryObj being the JavaScript dictionary object you want to go through. And value, key of course being the names of them in the dictionary.

$.each(DictionaryObj, function (key, value) {
        .attr("value", key)

Java HTML Parsing

You can also use XWiki HTML Cleaner:

It uses HTMLCleaner and extends it to generate valid XHTML 1.1 content.

Allow click on twitter bootstrap dropdown toggle link?

Since there is not really an answer that works (selected answer disables dropdown), or overrides using javascript, here goes.

This is all html and css fix (uses two <a> tags):

<ul class="nav">
 <li class="dropdown dropdown-li">
    <a class="dropdown-link" href="">Dropdown</a>
    <a class="dropdown-caret dropdown-toggle"><b class="caret"></b></a>
    <ul class="dropdown-menu">
        <li><a href="#">Link 1</a></li>
        <li><a href="#">Link 2</a></li>

Now here's the CSS you need.

.dropdown-li {
    display:inline-block !important;
.dropdown-link {
    display:inline-block !important; 
    padding-right:4px !important;
.dropdown-caret {
    display:inline-block !important; 
    padding-left:4px !important;

Assuming you will want the both <a> tags to highlight on hover of either one, you will also need to override bootstrap, you might play around with the following:

.nav > li:hover {
    background-color: #f67a47; /*hover background color*/
.nav > li:hover > a {
    color: white; /*hover text color*/
.nav > li:hover > ul > a {
    color: black; /*dropdown item text color*/

Going from MM/DD/YYYY to DD-MMM-YYYY in java

Try this,

Date currDate = new Date();
DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
String strCurrDate = dateFormat.format(currDate);

How to check if image exists with given url?

Use the error handler like this:

$('#image_id').error(function() {
  alert('Image does not exist !!');

If the image cannot be loaded (for example, because it is not present at the supplied URL), the alert is displayed:


I think using:


would be enough to check for a 404.

More Readings:

Update 2:

Your code should be like this:

$(this).error(function() {
  alert('Image does not exist !!');

No need for these lines and that won't check if the remote file exists anyway:

var imgcheck = imgsrc.width;    

if (imgcheck==0) {
  alert("You have a zero size image");
} else { 
  //execute the rest of code here 

How to print all session variables currently set?

echo '<pre>';var_dump($_SESSION);echo '</pre>';
// or
echo '<pre>';print_r($_SESSION);echo '</pre>';

NOTE: session_start(); line is must then only you will able to print the value $_SESSION

How to define global variable in Google Apps Script

In GAS global variables are not what they are in other languages. They are not constants nor variables available in all routines.

I thought I could use global variables for consistency amongst functions and efficiency as well. But I was wrong as pointed out by some people here at SO.

Global variable will be evaluated at each execution of a script, so not just once every time you run your application.
Global variables CAN be changed in a script (so they are not constants that cannot be changed by accident), but will be reinitialized when another script will be invoked.
There is also a speed penalty on using global variables. If within a function you use the same global variable two or more times, it will be faster to assign a local variable and use that instead.

If you want to preserve variables between all functions in your application, it might be using a cacheService will be best. I found out that looping through all files and folders on a drive takes a LOT of time. But you can store info about files and folders within cache (or even properties) and speed up at least 100 times.

The only way I use global variables now is for some prefixes and for naming widgets.

Encoding URL query parameters in Java

The built in Java URLEncoder is doing what it's supposed to, and you should use it.

A "+" or "%20" are both valid replacements for a space character in a URL. Either one will work.

A ":" should be encoded, as it's a separator character. i.e. http://foo or ftp://bar. The fact that a particular browser can handle it when it's not encoded doesn't make it correct. You should encode them.

As a matter of good practice, be sure to use the method that takes a character encoding parameter. UTF-8 is generally used there, but you should supply it explicitly.

URLEncoder.encode(yourUrl, "UTF-8");

Does HTTP use UDP?

The answer: Yes

Reason: See the OSI model.


HTTP is an application layer protocol, which could be encapsulated with a protocol that uses UDP, providing arguably faster reliable communication than TCP. The server daemon and client would obviously need to support this new protocol. Quake 2 protocol proves that UDP can be used over TCP to provide a basis for a structured communication system insuring flow control (e.g. chunk ids).

What is the correct "-moz-appearance" value to hide dropdown arrow of a <select> element

While you can't yet get Firefox to remove the dropdown arrow (see MatTheCat's post), you can hide your "stylized" background image from showing in Firefox.

-moz-background-position: -9999px -9999px!important;

This will position it out of frame, leaving you with the default select box arrow – while keeping the stylized version in Webkit.

"E: Unable to locate package python-pip" on Ubuntu 18.04

Try the following commands in terminal, this will work better:

apt-get install curl

curl -o


How do I cancel an HTTP fetch() request?

This works in browser and nodejs Live browser demo

const cpFetch= require('cp-fetch');
const url= '';
const chain = cpFetch(url, {timeout: 10000})
    .then(response => response.json())
    .then(data => console.log(`Done: `, data), err => console.log(`Error: `, err))
setTimeout(()=> chain.cancel(), 1000); // abort the request after 1000ms 

HTML form with two submit buttons and two "target" attributes

Here's a quick example script that displays a form that changes the target type:

<script type="text/javascript">
    function myTarget(form) {
        for (i = 0; i < form.target_type.length; i++) {
            if (form.target_type[i].checked)
                val = form.target_type[i].value;
        } = val;
        return true;
<form action="" onSubmit="return myTarget(this);">
    <input type="radio" name="target_type" value="_self" checked /> Self <br/>
    <input type="radio" name="target_type" value="_blank" /> Blank <br/>
    <input type="submit">

View/edit ID3 data for MP3 files

ID3.NET implemented ID3v1.x and ID3v2.3 and supports read/write operations on the ID3 section in MP3 files. There's also a NuGet package available.

Difference between rake db:migrate db:reset and db:schema:load

Rails 5

db:create - Creates the database for the current RAILS_ENV environment. If RAILS_ENV is not specified it defaults to the development and test databases.

db:create:all - Creates the database for all environments.

db:drop - Drops the database for the current RAILS_ENV environment. If RAILS_ENV is not specified it defaults to the development and test databases.

db:drop:all - Drops the database for all environments.

db:migrate - Runs migrations for the current environment that have not run yet. By default it will run migrations only in the development environment.

db:migrate:redo - Runs db:migrate:down and db:migrate:up or db:migrate:rollback and db:migrate:up depending on the specified migration.

db:migrate:up - Runs the up for the given migration VERSION.

db:migrate:down - Runs the down for the given migration VERSION.

db:migrate:status - Displays the current migration status.

db:migrate:rollback - Rolls back the last migration.

db:version - Prints the current schema version.

db:forward - Pushes the schema to the next version.

db:seed - Runs the db/seeds.rb file.

db:schema:load Recreates the database from the schema.rb file. Deletes existing data.

db:schema:dump Dumps the current environment’s schema to db/schema.rb.

db:structure:load - Recreates the database from the structure.sql file.

db:structure:dump - Dumps the current environment’s schema to db/structure.sql. (You can specify another file with SCHEMA=db/my_structure.sql)

db:setup Runs db:create, db:schema:load and db:seed.

db:reset Runs db:drop and db:setup. db:migrate:reset - Runs db:drop, db:create and db:migrate.

db:test:prepare - Check for pending migrations and load the test schema. (If you run rake without any arguments it will do this by default.)

db:test:clone - Recreate the test database from the current environment’s database schema.

db:test:clone_structure - Similar to db:test:clone, but it will ensure that your test database has the same structure, including charsets and collations, as your current environment’s database.

db:environment:set - Set the current RAILS_ENV environment in the ar_internal_metadata table. (Used as part of the protected environment check.)

db:check_protected_environments - Checks if a destructive action can be performed in the current RAILS_ENV environment. Used internally when running a destructive action such as db:drop or db:schema:load.

How do I capture response of form.submit

I am not sure that you understand what submit() does...

When you do form1.submit(); the form information is sent to the webserver.

The WebServer will do whatever its supposed to do and return a brand new webpage to the client(usually the same page with something changed).

So, there is no way you can "catch" the return of a form.submit() action.

jQuery Call to WebService returns "No Transport" error

I too got this problem and all solutions given above either failed or were not applicable due to client webservice restrictions.

For this, I added an iframe in my page which resided in the client;s server. So when we post our data to the iframe and the iframe then posts it to the webservice. Hence the cross-domain referencing is eliminated.

We added a 2-way origin check to confirm only authorized page posts data to and from the iframe.

Hope it helps

<iframe style="display:none;" id='receiver' name="receiver" src="https://iframe-address-at-client-server">

//send data to iframe
var hiddenFrame = document.getElementById('receiver').contentWindow;
hiddenFrame.postMessage(JSON.stringify(message), 'https://client-server-url');

//The iframe receives the data using the code:
window.onload = function () {
    var eventMethod = window.addEventListener ? "addEventListener" : "attachEvent";
    var eventer = window[eventMethod];
    var messageEvent = eventMethod == "attachEvent" ? "onmessage" : "message";
    eventer(messageEvent, function (e) {
        var origin = e.origin;
        //if origin not in pre-defined list, break and return
        var messageFromParent = JSON.parse(;
        var json =;

        //send json to web service using AJAX   
        //return the response back to source
        e.source.postMessage(JSON.stringify(aJAXResponse), e.origin);
    }, false);

Java: how can I split an ArrayList in multiple small ArrayLists?

Let's suppose you want the considere the class that split the list into multiple chuncks as a library class.

So let's say the class is called 'shared' and in should be final to be sure it won't be extended.

   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.List;

public final class Shared {
List<Integer> input;
int portion;

public Shared(int portion, Integer... input) {

public List<List<Integer>> listToChunks() {
    List<List<Integer>> result = new ArrayList<List<Integer>>();
    int size = this.size();
    int startAt = 0;
    int endAt = this.portion;

    while (endAt <= size) {

        result.add(this.input.subList(startAt, endAt));
        startAt = endAt;
        endAt = (size - endAt < this.portion && size - endAt > 0) ? (this.size()) : (endAt + this.portion);

    return result;

public int size() {
    return this.input.size();

public void setInput(Integer... input) {
    if (input != null && input.length > 0)
        this.input = Arrays.asList(input);
        System.out.println("Error 001 : please enter a valid array of integers.");

public void setPortion(int portion) {
    if (portion > 0)
        this.portion = portion;
        System.out.println("Error 002 : please enter a valid positive number.");

Next, let's try to execute it from another class that hold the public static void main(String... args)

public class exercise {

public static void main(String[] args) {
    Integer[] numbers = {1, 2, 3, 4, 5, 6, 7};
    int portion = 2;
    Shared share = new Shared(portion, numbers);

Now, if you enter an array of integer [1, 2, 3, 4, 5, 6, 7] with a partition of 2. the result will be [[1, 2], [3, 4], [5, 6], [7]]

IOCTL Linux device driver

An ioctl, which means "input-output control" is a kind of device-specific system call. There are only a few system calls in Linux (300-400), which are not enough to express all the unique functions devices may have. So a driver can define an ioctl which allows a userspace application to send it orders. However, ioctls are not very flexible and tend to get a bit cluttered (dozens of "magic numbers" which just work... or not), and can also be insecure, as you pass a buffer into the kernel - bad handling can break things easily.

An alternative is the sysfs interface, where you set up a file under /sys/ and read/write that to get information from and to the driver. An example of how to set this up:

static ssize_t mydrvr_version_show(struct device *dev,
        struct device_attribute *attr, char *buf)
    return sprintf(buf, "%s\n", DRIVER_RELEASE);

static DEVICE_ATTR(version, S_IRUGO, mydrvr_version_show, NULL);

And during driver setup:

device_create_file(dev, &dev_attr_version);

You would then have a file for your device in /sys/, for example, /sys/block/myblk/version for a block driver.

Another method for heavier use is netlink, which is an IPC (inter-process communication) method to talk to your driver over a BSD socket interface. This is used, for example, by the WiFi drivers. You then communicate with it from userspace using the libnl or libnl3 libraries.

How do I prevent DIV tag starting a new line?

Add style="display: inline" to your div.

Perform Button click event when user press Enter key in Textbox

You can try:


    <asp:TextBox ID="TextBox1" runat="server" onKeyDown="submitButton(event)"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />

And javascript:

function submitButton(event) {
        if (event.which == 13) {

Code behind:

protected void Button1_Click(object sender, EventArgs e)
        //load data and fill to gridview
} // fixed the function view for users

Hope this help

Usage of @see in JavaDoc?

Yeah, it is quite vague.

You should use it whenever for readers of the documentation of your method it may be useful to also look at some other method. If the documentation of your methodA says "Works like methodB but ...", then you surely should put a link. An alternative to @see would be the inline {@link ...} tag:

 * ...
 * Works like {@link #methodB}, but ...

When the fact that methodA calls methodB is an implementation detail and there is no real relation from the outside, you don't need a link here.

ListView with Add and Delete Buttons in each Row in android

You will first need to create a custom layout xml which will represent a single item in your list. You will add your two buttons to this layout along with any other items you want to display from your list.

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android=""
android:layout_height="match_parent" > 

    android:textStyle="bold" /> 

    android:text="Delete" /> 

    android:text="Add" />


Next you will need to create a Custom ArrayAdapter Class which you will use to inflate your xml layout, as well as handle your buttons and on click events.

public class MyCustomAdapter extends BaseAdapter implements ListAdapter { 
private ArrayList<String> list = new ArrayList<String>(); 
private Context context; 

public MyCustomAdapter(ArrayList<String> list, Context context) { 
    this.list = list; 
    this.context = context; 

public int getCount() { 
    return list.size(); 

public Object getItem(int pos) { 
    return list.get(pos); 

public long getItemId(int pos) { 
    return list.get(pos).getId();
    //just return 0 if your list items do not have an Id variable.

public View getView(final int position, View convertView, ViewGroup parent) {
    View view = convertView;
    if (view == null) {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
        view = inflater.inflate(R.layout.my_custom_list_layout, null);

    //Handle TextView and display string from your list
    TextView listItemText = (TextView)view.findViewById(; 

    //Handle buttons and add onClickListeners
    Button deleteBtn = (Button)view.findViewById(;
    Button addBtn = (Button)view.findViewById(;

    deleteBtn.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v) { 
            //do something
            list.remove(position); //or some other task
    addBtn.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v) { 
            //do something

    return view; 

Finally, in your activity you can instantiate your custom ArrayAdapter class and set it to your listview.

public class MyActivity extends Activity { 

protected void onCreate(Bundle savedInstanceState) { 

    //generate list
    ArrayList<String> list = new ArrayList<String>();

    //instantiate custom adapter
    MyCustomAdapter adapter = new MyCustomAdapter(list, this);

    //handle listview and assign adapter
    ListView lView = (ListView)findViewById(;

Hope this helps!

Switch role after connecting to database

If someone still needs it (like I do).

The specified role_name must be a role that the current session user is a member of.

We need to make the current session user a member of the role:

create role myrole;
set role myrole;
grant myrole to myuser;
set role myrole;


Role ROLE created.

Error starting at line : 4 in command -
set role myrole
Error report -
ERROR: permission denied to set role "myrole"

Grant succeeded.

Role SET succeeded.

Check if a given time lies between two times regardless of date

This worked for me:

fun timeBetweenInterval(
    openTime: String,
    closeTime: String
): Boolean {
    try {
        val dateFormat = SimpleDateFormat(TIME_FORMAT)
        val afterCalendar = Calendar.getInstance().apply {
            time = dateFormat.parse(openTime)
            add(Calendar.DATE, 1)
        val beforeCalendar = Calendar.getInstance().apply {
            time = dateFormat.parse(closeTime)
            add(Calendar.DATE, 1)

        val current = Calendar.getInstance().apply {
            val localTime = dateFormat.format(timeInMillis)
            time = dateFormat.parse(localTime)
            add(Calendar.DATE, 1)
        return current.time.after(afterCalendar.time) && current.time.before(beforeCalendar.time)
    } catch (e: ParseException) {
        return false

How to read one single line of csv data in Python?

you could get just the first row like:

with open('some.csv', newline='') as f:
  csv_reader = csv.reader(f)
  csv_headings = next(csv_reader)
  first_line = next(csv_reader)

In a Dockerfile, How to update PATH environment variable?

You can use Environment Replacement in your Dockerfile as follows:

ENV PATH="/opt/gtk/bin:${PATH}"

SQL Query - Concatenating Results into One String

DECLARE @CodeNameString varchar(max)
SET @CodeNameString=''

SELECT @CodeNameString=@CodeNameString+CodeName FROM AccountCodes ORDER BY Sort
SELECT @CodeNameString

How to change font-color for disabled input?

This works for making disabled select options act as headers. It doesnt remove the default text shadow of the :disabled option but it does remove the hover effect. In IE you wont get the font color but at least the text-shadow is gone. Here is the html and css:

select option.disabled:disabled{color: #5C3333;background-color: #fff;font-weight: bold;}_x000D_
select option.disabled:hover{color:  #5C3333 !important;background-color: #fff;}_x000D_
select option:hover{color: #fde8c4;background-color: #5C3333;}
     <option class="disabled" disabled>Header1</option>_x000D_
     <option class="disabled" disabled>Header2</option>_x000D_
     <option class="disabled" disabled>Header3</option>_x000D_

What is the difference between Promises and Observables?

Even though this answer is late, i have summarized the differences below,


  1. Observable is just a function that takes an observer and returns a function Observer: an object with next, error.
  2. Observer allows to subscribe/unsubscribe to its data stream, emit next value to the observer, notify the observer about errors and inform the observer about the stream completion
  3. Observer provides a function to handle next value,errors and end of stream(ui events,http responses,data with web sockets).
  4. Works with multiple values over time
  5. It is cancel-able/retry-able and supports operators such as map,filter,reduce etc.
  6. Creating an Observable can be -Observable.create() - returns Observable that can invoke methods on -Observer Observable.from() - converts an array or iterable into -Observable Observable.fromEvent() - converts an event into Observable -Observable.fromPromise() - converts a Promise into Observable -Observable.range() - returns a sequence of integers in the speci?ed range


  1. A promise represents a task that will finish in the future;

  2. Promises become resolved by a value;

  3. Promises get rejected by exceptions;

  4. Not cancellable and it returns a single value

  5. A promise expose a function (then)

    -then returns a new promise;

    -allows for the attachment of that will be executed based on state;

    -handlers are guaranteed to execute in order attached;

How to change the Eclipse default workspace?

My kepler eclipse went into not responding at boot (shortly after installing GAE support) which I traced to a corrupt workspace. I fixed this by closing kepler, renaming the workspace directory (in use) so kepler starts normally without a workspace, then used file >> switch workspace to generate new workspace. Then started populating that with my old projects that I still needed.

How to create Drawable from resource

If you are inheriting from a fragment you can do:

Drawable drawable = getActivity().getDrawable(R.drawable.icon)

Java generics: multiple generic parameters?

You can declare multiple type variables on a type or method. For example, using type parameters on the method:

<P, Q> int f(Set<P>, Set<Q>) {
  return 0;

The difference between Classes, Objects, and Instances

Class : Structure

Object : Physical Manifestation

Instance : each object created from class

Reference : Address of Object

Importing Maven project into Eclipse

Maven have a Eclipse plugin and Eclipse have a Maven plugin we are going to discus those things.when we using maven with those command line stuffs and etc when we are going through eclipse we don't want to that command line codes it have very much helpful, Maven and eclipse giving good integration ,they will work very well together thanks for that plugins

Step 1: Go to the maven project. Here my project is FirstApp.(Example my project is FirstApp)

There you can see one pom.xml file, now what we want is to generate an eclipse project using that pom.xml.

Step 2: Use mvn eclipse:eclipse command

Step 3: Verify the project

after execution of this command notice that two new files have been created

Note:- both these files are created for Eclipse. When you open those files you will notice a "M2_REPO" class variable is generate. You want to add that class path in eclipse, otherwise eclipse will show a error.

Step 4: Importing eclipse project

File -> Import -> General -> Existing Projects in Workspace -> Select root directory -> Done

More details here

Only allow Numbers in input Tag without Javascript

Of course, you can't fully rely on the client-side (javascript) validation, but that's not a reason to avoid it completely. With or without it, you have to do the server-side validation anyway (since the client can disable javascript). And that's just what you're left with, due to your non-javascript solution constraint.

So, after a submit, if the field value doesn't pass the server-side validation, the client should end up on the very same page, with additional error message specifying the requested value format. You also should provide the value format information beforehands, e.g. as a tool-tip hint (title attribute).

There's most certainly no passive client-side validation mechanism existing in HTML 4 / XHTML.

On the other hand, in HTML 5 you have two options:

  • input of type number:

    <input type="number" min="xxx" max="yyy" title="Format: 3 digits" />

    – only validates the range – if user enters a non-number, an empty value is submitted
    – the field visual is enhanced with increment / decrement controls (browser dependent)

  • the pattern attribute:

    <input type="text" pattern="[0-9]{3}" title="Format: 3 digits" />
    <input type="text" pattern="\d{3}" title="Format: 3 digits" />

    – this gives you a full contorl over the format (anything you can specify by regular expression)
    – no visual difference / enhancement

But here you still rely on browser capabilities, so do a server-side validation in either case.

Properly Handling Errors in VBA (Excel)

You've got one truly marvelous answer from ray023, but your comment that it's probably overkill is apt. For a "lighter" version....

Block 1 is, IMHO, bad practice. As already pointed out by osknows, mixing error-handling with normal-path code is Not Good. For one thing, if a new error is thrown while there's an Error condition in effect you will not get an opportunity to handle it (unless you're calling from a routine that also has an error handler, where the execution will "bubble up").

Block 2 looks like an imitation of a Try/Catch block. It should be okay, but it's not The VBA Way. Block 3 is a variation on Block 2.

Block 4 is a bare-bones version of The VBA Way. I would strongly advise using it, or something like it, because it's what any other VBA programmer inherting the code will expect. Let me present a small expansion, though:

Private Sub DoSomething()
On Error GoTo ErrHandler

'Dim as required

'functional code that might throw errors

    'any always-execute (cleanup?) code goes here -- analagous to a Finally block.
    'don't forget to do this -- you don't want to fall into error handling when there's no error
    Exit Sub

    'can Select Case on Err.Number if there are any you want to handle specially

    'display to user
    MsgBox "Something's wrong: " & vbCrLf & Err.Description

    'or use a central DisplayErr routine, written Public in a Module
    DisplayErr Err.Number, Err.Description

    Resume ExitSub
End Sub

Note that second Resume. This is a trick I learned recently: It will never execute in normal processing, since the Resume <label> statement will send the execution elsewhere. It can be a godsend for debugging, though. When you get an error notification, choose Debug (or press Ctl-Break, then choose Debug when you get the "Execution was interrupted" message). The next (highlighted) statement will be either the MsgBox or the following statement. Use "Set Next Statement" (Ctl-F9) to highlight the bare Resume, then press F8. This will show you exactly where the error was thrown.

As to your objection to this format "jumping around", A) it's what VBA programmers expect, as stated previously, & B) your routines should be short enough that it's not far to jump.

I/O error(socket error): [Errno 111] Connection refused

Its seems that server is not running properly so ensure that with terminal by

telnet ip port


telnet localhost 8069

It will return connected to localhost so it indicates that there is no problem with the connection Else it will return Connection refused it indicates that there is problem with the connection

GnuPG: "decryption failed: secret key not available" error from gpg on Windows

workmad3 is apparently out of date, at least for current gpg, as the --allow-secret-key-import is now obsolete and does nothing.

What happened to me was that I failed to export properly. Just doing gpg --export is not adequate, as it only exports the public keys. When exporting keys, you have to do

gpg --export-secret-keys >keyfile

How to get week numbers from dates?

If you want to get the week number with the year, Grant Shannon's solution using strftime works, but you need to make some corrections for the dates around january 1st. For instance, 2016-01-03 (yyyy-mm-dd) is week 53 of year 2015, not 2016. And 2018-12-31 is week 1 of 2019, not of 2018. This codes provides some examples and a solution. In column "yearweek" the years are sometimes wrong, in "yearweek2" they are corrected (rows 2 and 5).


# create a testset
test <- data.frame(matrix(data = c("2015-12-31",
                                   "2019-01-01") , ncol=1, nrow = 6 ))
# add a colname
colnames(test) <- "date_txt"

# this codes provides correct year-week numbers
test <- test %>%
        mutate(date = as.Date(date_txt, format = "%Y-%m-%d")) %>%
        mutate(yearweek = as.integer(strftime(date, format = "%Y%V"))) %>%
        mutate(yearweek2 = ifelse(test = day(date) > 7 & substr(yearweek, 5, 6) == '01',
                                 yes  = yearweek + 100,
                                 no   = ifelse(test = month(date) == 1 & as.integer(substr(yearweek, 5, 6)) > 51,
                                               yes  = yearweek - 100,
                                               no   = yearweek)))
# print the result

    date_txt       date yearweek yearweek2
1 2015-12-31 2015-12-31   201553    201553
2 2016-01-03 2016-01-03   201653    201553
3 2016-01-04 2016-01-04   201601    201601
4 2018-12-30 2018-12-30   201852    201852
5 2018-12-31 2018-12-31   201801    201901
6 2019-01-01 2019-01-01   201901    201901

#1273 - Unknown collation: 'utf8mb4_unicode_ci' cPanel

If you have already exported a .sql file, the best thing to do is to Find and Replace the following if you have them in your file:

  • utf8mb4_0900_ai_ci to utf8_unicode_ci
  • utf8mb4 to utf8
  • utf8_unicode_520_ci to utf8_unicode_ci

It will replace utf8mb4_unicode_ci to utf8_unicode_ci. Now you go to your phpMyAdmin cPanel and set the DB collation to utf8_unicode_ci through Operations > Collation.

If you are exporting to a .sql, it's better to change the format on how you're exporting the file. Check out Evster's anwer (it's in the same page as this)

How to change navigation bar color in iOS 7 or 6?

Based on posted answered, this worked for me:

/* check for iOS 6 or 7 */
if ([[self navigationController].navigationBar respondsToSelector:@selector(setBarTintColor:)]) {
    [[self navigationController].navigationBar setBarTintColor:[UIColor whiteColor]];

} else {
    /* Set background and foreground */
    [[self navigationController].navigationBar setTintColor:[UIColor whiteColor]];
    [self navigationController].navigationBar.titleTextAttributes = [[NSDictionary alloc] initWithObjectsAndKeys:[UIColor blackColor],UITextAttributeTextColor,nil];

VBoxManage: error: Failed to create the host-only adapter

Windows 10 Pro VirtualBox 5.2.12

In my case I had to edit the Host Only Ethernet Adapter in the VirtualBox GUI. Click Global Tools -> Host Network Manager -> Select the ethernet adapter, then click Properties. Mine was set to configure automatically, and the IP address it was trying to use was different than what I was trying to use with drupal-vm and vagrant. I just had to change that to manual and correct the IP address. I hope this helps someone else.

"fatal: Not a git repository (or any of the parent directories)" from git status

Simply, after you clone the repo you need to cd (change your current directory) to the new cloned folder

git clone https://[email protected]/Repo_Name.git

cd Repo_Name