Programs & Examples On #Startswith

How do I check if a C++ std::string starts with a certain string, and convert a substring to an int?

std::string text = "--foo=98";
std::string start = "--foo=";

if (text.find(start) == 0)
    int n = stoi(text.substr(start.length()));
    std::cout << n << std::endl;

Regex to check with starts with http://, https:// or ftp://

I think the regex / string parsing solutions are great, but for this particular context, it seems like it would make sense just to use java's url parser:

Taken from that page:


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

        URL aURL = new URL(""
                           + "/index.html?name=networking#DOWNLOADING");

        System.out.println("protocol = " + aURL.getProtocol());
        System.out.println("authority = " + aURL.getAuthority());
        System.out.println("host = " + aURL.getHost());
        System.out.println("port = " + aURL.getPort());
        System.out.println("path = " + aURL.getPath());
        System.out.println("query = " + aURL.getQuery());
        System.out.println("filename = " + aURL.getFile());
        System.out.println("ref = " + aURL.getRef());

yields the following:

protocol = http
authority =
host =
port = 80
path = /docs/books/tutorial/index.html
query = name=networking
filename = /docs/books/tutorial/index.html?name=networking

How do I find if a string starts with another string in Ruby?

The method mentioned by steenslag is terse, and given the scope of the question it should be considered the correct answer. However it is also worth knowing that this can be achieved with a regular expression, which if you aren't already familiar with in Ruby, is an important skill to learn.

Have a play with Rubular:

But in this case, the following ruby statement will return true if the string on the left starts with 'abc'. The \A in the regex literal on the right means 'the beginning of the string'. Have a play with rubular - it will become clear how things work.

'abcdefg' =~  /\Aabc/ 

How to check if a string "StartsWith" another string?

I just wanted to add my opinion about this.

I think we can just use like this:

var haystack = 'hello world';
var needle = 'he';

if (haystack.indexOf(needle) == 0) {
  // Code if string starts with this substring

If strings starts with in PowerShell

$Group is an object, but you will actually need to check if $Group.samaccountname.StartsWith("string").

Change $Group.StartsWith("S_G_") to $Group.samaccountname.StartsWith("S_G_").

Code not running in IE 11, works fine in Chrome

I also recently faced the prob. I solved using ^ which is similar to startwith in jquery. Say,

var str = array[a].id;
if (str.startsWith('REP')) {..........}

we can use


Here, str is id of element.

How can query string parameters be forwarded through a proxy_pass with nginx?

To redirect Without Query String add below lines in Server block under listen port line:

if ($uri ~ .*.containingString$) {
           return 301 https://$host/$uri/;

With Query String:

if ($uri ~ .*.containingString$) {
           return 301 https://$host/$uri/?$query_string;

How can I do a case insensitive string comparison?

Others answer are totally valid here, but somehow it takes some time to type StringComparison.OrdinalIgnoreCase and also using String.Compare.

I've coded simple String extension method, where you could specify if comparison is case sensitive or case senseless with boolean, attaching whole code snippet here:

using System;

/// <summary>
/// String helpers.
/// </summary>
public static class StringExtensions
    /// <summary>
    /// Compares two strings, set ignoreCase to true to ignore case comparison ('A' == 'a')
    /// </summary>
    public static bool CompareTo(this string strA, string strB, bool ignoreCase)
        return String.Compare(strA, strB, ignoreCase) == 0;

After that whole comparison shortens by 10 characters approximately - compare:

Before using String extension:

String.Compare(testFilename, testToStart,true) != 0

After using String extension:

testFilename.CompareTo(testToStart, true)

How to configure PHP to send e-mail?

configure your php.ini like this


[mail function]
; XAMPP: Comment out this if you want to work with an SMTP Server like Mercury

; SMTP =

; smtp_port = 465

; For Win32 only.
;sendmail_from = postmaster@localhost

How to open .dll files to see what is written inside?

Follow below steps..

  1. Go to Start Menu.
  2. Type Visual Studio Tool.
  3. Go to the folder above.
  4. Click on "Developer Command Prompt for VS 2013" in the case of VS 2013 or just "Visual Studio Command Prompt " in case of VS 2010.
  5. After command prompt loaded to screen type ILDASM.EXE press ENTER.
  6. ILDASM window will open.Drag the .dll file to window from your folder.Or click on File->New.Then Add required .dll file.
  7. After above steps Mainfest and .dll file will appear. Double click on these files to see what it contains.

How do I convert a list of ascii values to a string in python?

Same basic solution as others, but I personally prefer to use map instead of the list comprehension:

>>> L = [104, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100]
>>> ''.join(map(chr,L))
'hello, world'

Add a custom attribute to a Laravel / Eloquent model on load?

in my case, creating an empty column and setting its accessor worked fine. my accessor filling user's age from dob column. toArray() function worked too.

public function getAgeAttribute()
  return Carbon::createFromFormat('Y-m-d', $this->attributes['dateofbirth'])->age;

catching stdout in realtime from subprocess

I know this is an old topic, but there is a solution now. Call the rsync with option --outbuf=L. Example:

cmd=['rsync', '-arzv','--backup','--outbuf=L','source/','dest']
p = subprocess.Popen(cmd,
for line in iter(p.stdout.readline, b''):
    print '>>> {}'.format(line.rstrip())

c#: getter/setter

In C# 6:

It is now possible to declare the auto-properties just as a field:

public string FirstName { get; set; } = "Ropert";

Read-Only Auto-Properties

public string FirstName { get;} = "Ropert";

Can we locate a user via user's phone number in Android?

Quick answer: No, at least not with native SMS service.

Long answer: Sure, but the receiver's phone should have the correct setup first. An app that detects incoming sms, and if a keyword matches, reports its current location to your server, which then pushes that info to the sender.

How to display special characters in PHP

Try This


<!DOCTYPE html>

$str = "This is some <b>bold</b> text.";
echo htmlspecialchars($str);

<p>Converting &lt; and &gt; into entities are often used to prevent browsers from using it as an HTML element. <br />This can be especially useful to prevent code from running when users have access to display input on your homepage.</p>



This is some <b>bold</b> text.

Converting < and > into entities are often used to prevent browsers from using it as an HTML element. This can be especially useful to prevent code from running when users have access to display input on your homepage.

Handling exceptions from Java ExecutorService tasks

This is because of AbstractExecutorService :: submit is wrapping your runnable into RunnableFuture (nothing but FutureTask) like below

public Future<?> submit(Runnable task) {
    if (task == null) throw new NullPointerException();
    RunnableFuture<Void> ftask = newTaskFor(task, null); /////////HERE////////
    return ftask;

Then execute will pass it to Worker and will call the below.

final void runWorker(Worker w) {
    Thread wt = Thread.currentThread();
    Runnable task = w.firstTask;
    w.firstTask = null;
    w.unlock(); // allow interrupts
    boolean completedAbruptly = true;
    try {
        while (task != null || (task = getTask()) != null) {
            // If pool is stopping, ensure thread is interrupted;
            // if not, ensure thread is not interrupted.  This
            // requires a recheck in second case to deal with
            // shutdownNow race while clearing interrupt
            if ((runStateAtLeast(ctl.get(), STOP) ||
                 (Thread.interrupted() &&
                  runStateAtLeast(ctl.get(), STOP))) &&
            try {
                beforeExecute(wt, task);
                Throwable thrown = null;
                try {
          ;           /////////HERE////////
                } catch (RuntimeException x) {
                    thrown = x; throw x;
                } catch (Error x) {
                    thrown = x; throw x;
                } catch (Throwable x) {
                    thrown = x; throw new Error(x);
                } finally {
                    afterExecute(task, thrown);
            } finally {
                task = null;
        completedAbruptly = false;
    } finally {
        processWorkerExit(w, completedAbruptly);

Finally; in the above code call will call Here is the exception handler code, because of this you are NOT getting the expected exception.

class FutureTask<V> implements RunnableFuture<V>

public void run() {
    if (state != NEW ||
        !UNSAFE.compareAndSwapObject(this, runnerOffset,
                                     null, Thread.currentThread()))
    try {
        Callable<V> c = callable;
        if (c != null && state == NEW) {
            V result;
            boolean ran;
            try {
                result =;
                ran = true;
            } catch (Throwable ex) {   /////////HERE////////
                result = null;
                ran = false;
            if (ran)
    } finally {
        // runner must be non-null until state is settled to
        // prevent concurrent calls to run()
        runner = null;
        // state must be re-read after nulling runner to prevent
        // leaked interrupts
        int s = state;
        if (s >= INTERRUPTING)

Convert String to Double - VB

Dim text As String = "123.45"
Dim value As Double
If Double.TryParse(text, value) Then
    ' text is convertible to Double, and value contains the Double value now
    ' Cannot convert text to Double
End If

Tkinter: How to use threads to preventing main event loop from "freezing"

The problem is that t.join() blocks the click event, the main thread does not get back to the event loop to process repaints. See Why ttk Progressbar appears after process in Tkinter or TTK progress bar blocked when sending email

Chrome:The website uses HSTS. Network errors...this page will probably work later

One very quick way around this is, when you're viewing the "Your connection is not private" screen:

type badidea

type thisisunsafe (credit to The Java Guy for finding the new passphrase)

That will allow the security exception when Chrome is otherwise not allowing the exception to be set via clickthrough, e.g. for this HSTS case.

This is only recommended for local connections and local-network virtual machines, obviously, but it has the advantage of working for VMs being used for development (e.g. on port-forwarded local connections) and not just direct localhost connections.

Note: the Chrome developers have changed this passphrase in the past, and may do so again. If badidea ceases to work, please leave a note here if you learn the new passphrase. I'll try to do the same.

Edit: as of 30 Jan 2018 this passphrase appears to no longer work.

If I can hunt down a new one I'll post it here. In the meantime I'm going to take the time to set up a self-signed certificate using the method outlined in this stackoverflow post:

How to create a self-signed certificate with openssl?

Edit: as of 1 Mar 2018 and Chrome Version 64.0.3282.186 this passphrase works again for HSTS-related blocks on .dev sites.

Edit: as of 9 Mar 2018 and Chrome Version 65.0.3325.146 the badidea passphrase no longer works.

Edit 2: the trouble with self-signed certificates seems to be that, with security standards tightening across the board these days, they cause their own errors to be thrown (nginx, for example, refuses to load an SSL/TLS cert that includes a self-signed cert in the chain of authority, by default).

The solution I'm going with now is to swap out the top-level domain on all my .app and .dev development sites with .test or .localhost. Chrome and Safari will no longer accept insecure connections to standard top-level domains (including .app).

The current list of standard top-level domains can be found in this Wikipedia article, including special-use domains:

Wikipedia: List of Internet Top Level Domains: Special Use Domains

These top-level domains seem to be exempt from the new https-only restrictions:

  • .local
  • .localhost
  • .test
  • (any custom/non-standard top-level domain)

See the answer and link from codinghands to the original question for more information:

answer from codinghands

Difference between javacore, thread dump and heap dump in Websphere

JVM head dump is a snapshot of a JVM heap memory in a given time. So its simply a heap representation of JVM. That is the state of the objects.

JVM thread dump is a snapshot of a JVM threads at a given time. So thats what were threads doing at any given time. This is the state of threads. This helps understanding such as locked threads, hanged threads and running threads.

Head dump has more information of java class level information than a thread dump. For example Head dump is good to analyse JVM heap memory issues and OutOfMemoryError errors. JVM head dump is generated automatically when there is something like OutOfMemoryError has taken place. Heap dump can be created manually by killing the process using kill -3 . Generating a heap dump is a intensive computing task, which will probably hang your jvm. so itsn't a methond to use offetenly. Heap can be analysed using tools such as eclipse memory analyser.

Core dump is a os level memory usage of objects. It has more informaiton than a head dump. core dump is not created when we kill a process purposely.

TokenMismatchException in VerifyCsrfToken.php Line 67

If you check some of the default forms from Laravel 5.4 you fill find how this is done:

<form class="form-horizontal" role="form" method="POST" action="{{ route('') }}">
  {{ csrf_field() }}

  <div class="form-group{{ $errors->has('email') ? ' has-error' : '' }}">
    <label for="email" class="col-md-4 control-label">E-Mail Address</label>

    <div class="col-md-6">
      <input id="email" type="email" class="form-control" name="email" value="{{ old('email') }}" required> @if ($errors->has('email'))
      <span class="help-block">
                                        <strong>{{ $errors->first('email') }}</strong>
                                    </span> @endif

  <div class="form-group">
    <div class="col-md-6 col-md-offset-4">
      <button type="submit" class="btn btn-primary">
                                    Send Password Reset Link

{{ csrf_field() }}

is the most appropriate way to add a custom hidden field that Laravel will understand.

csrf_filed() uses csrf_token() inside as you can see:

if (! function_exists('csrf_field')) {
     * Generate a CSRF token form field.
     * @return \Illuminate\Support\HtmlString
    function csrf_field()
        return new HtmlString('<input type="hidden" name="_token" value="'.csrf_token().'">');

And csrf_field() method uses session for the job.

function csrf_token()
    $session = app('session');

    if (isset($session)) {
        return $session->token();

    throw new RuntimeException('Application session store not set.');

Changing default startup directory for command prompt in Windows 7


cmd.exe /k cd c:/

in a text file and save as cmd.bat Clicking this file does the trick. You can pin it to the start menu as well.

To start in a partitioned drive (e.g. D), use

cmd.exe /k d:

JavaScript URL Decode function

var uri = "my test.asp?name=ståle&car=saab";_x000D_

What is the difference between call and apply?

From the MDN docs on Function.prototype.apply() :

The apply() method calls a function with a given this value and arguments provided as an array (or an array-like object).


fun.apply(thisArg, [argsArray])

From the MDN docs on :

The call() method calls a function with a given this value and arguments provided individually.

Syntax[, arg1[, arg2[, ...]]])

From Function.apply and in JavaScript :

The apply() method is identical to call(), except apply() requires an array as the second parameter. The array represents the arguments for the target method.

Code example :

var doSomething = function() {_x000D_
    var arr = [];_x000D_
    for(i in arguments) {_x000D_
        if(typeof this[arguments[i]] !== 'undefined') {_x000D_
    return arr;_x000D_
var output = function(position, obj) {_x000D_
    document.body.innerHTML += '<h3>output ' + position + '</h3>' + JSON.stringify(obj) + '\n<br>\n<br><hr>';_x000D_
output(1, doSomething(_x000D_
output(2, doSomething.apply({one : 'Steven', two : 'Jane'}, [_x000D_
output(3,{one : 'Steven', two : 'Jane'},_x000D_

See also this Fiddle.

The project type is not supported by this installation

For Visual Studio 2010 (prolly also for other versions):

If you are opening an ASP.NET MVC project make sure that the correct MVC version is installed on your PC. If you try to open an ASP.NET MVC 3 project, first close all your visual studio instances and install MVC3:

For other ASP.NET MVC versions download them from or via Web Platform Installer 4.0.

Getting path of captured image in Android using camera intent

Try this method to get path of original image captured by camera.

public String getOriginalImagePath() {
        String[] projection = { MediaStore.Images.Media.DATA };
        Cursor cursor = getActivity().managedQuery(
                projection, null, null, null);
        int column_index_data = cursor

        return cursor.getString(column_index_data);

This method will return path of the last image captured by camera. So this path would be of original image not of thumbnail bitmap.

Hiding a button in Javascript

If the space on that page is not disabled then put your button inside a div.

<div id="a1">
<button>Click here</button>

Using Jquery:

<script language="javascript">

Using JS:

<script language="javascript">
document.getElementById("a1").style.visibility = "hidden";
document.getElementById("a1").style.display = "none";

System.Net.WebException: The operation has timed out

I remember I had the same problem a while back using WCF due the quantity of the data I was passing. I remember I changed timeouts everywhere but the problem persisted. What I finally did was open the connection as stream request, I needed to change the client and the server side, but it work that way. Since it was a stream connection, the server kept reading until the stream ended.

Expected initializer before function name

Try adding a semi colon to the end of your structure:

 struct sotrudnik {
    string name;
    string speciality;
    string razread;
    int zarplata;
} //Semi colon here

Will using 'var' affect performance?

I don't think you properly understood what you read. If it gets compiled to the correct type, then there is no difference. When I do this:

var i = 42;

The compiler knows it's an int, and generate code as if I had written

int i = 42;

As the post you linked to says, it gets compiled to the same type. It's not a runtime check or anything else requiring extra code. The compiler just figures out what the type must be, and uses that.

How do you force a CIFS connection to unmount

Try umount -f /mnt/share. Works OK with NFS, never tried with cifs.

Also, take a look at autofs, it will mount the share only when accessed, and will unmount it afterworlds.

There is a good tutorial at

Cannot resolve symbol AppCompatActivity - Support v7 libraries aren't recognized?

After invalidating Cache, changing from




worked for me.

Android - How to decode and decompile any APK file?

You can try this website Just upload the .apk file and rest of it will be done by this site.

checking for typeof error in JS

Or use this for different types of errors

function isError(val) {
  return (!!val && typeof val === 'object')
    && (( === '[object Error]')
      || (typeof val.message === 'string' && typeof === 'string'))

How to fix "unable to open stdio.h in Turbo C" error?

Since you did not mention which version of Turbo C this method below will cover both v2 and v3.

  • Click on 'Options', 'Directories', enter the proper location for the Include and Lib directories.

How do I get the current absolute URL in Ruby on Rails?

You can add this current_url method in the ApplicationController to return the current URL and allow merging in other parameters

# + current_url( :page => 3 )
# =
def current_url(overwrite={})
    url_for :only_path => false, :params => params.merge(overwrite)

Example Usage:

current_url --> http://...
current_url(:page=>4) --> http://...&page=4

Java 8 stream map to list of keys sorted by values

You have to sort with a custom comparator based on the value of the entry. Then select all the keys before collecting

           .sorted((e1, e2) -> e1.getValue().compareTo(e2.getValue())) // custom Comparator
           .map(e -> e.getKey())

Using variables inside strings

In C# 6 you can use string interpolation:

string name = "John";
string result = $"Hello {name}";

The syntax highlighting for this in Visual Studio makes it highly readable and all of the tokens are checked.

What’s the best way to reload / refresh an iframe?

Add empty space also reload the iFrame automatically.

document.getElementById('id').src += '';

Gradle - Move a folder from ABC to XYZ

Your task declaration is incorrectly combining the Copy task type and project.copy method, resulting in a task that has nothing to copy and thus never runs. Besides, Copy isn't the right choice for renaming a directory. There is no Gradle API for renaming, but a bit of Groovy code (leveraging Java's File API) will do. Assuming Project1 is the project directory:

task renABCToXYZ {     doLast {         file("ABC").renameTo(file("XYZ"))     } } 

Looking at the bigger picture, it's probably better to add the renaming logic (i.e. the doLast task action) to the task that produces ABC.

Putting a password to a user in PhpMyAdmin in Wamp

Looks like phpmyadmin's username and password are stored elsewhere ( probably in a custom-defined config file ) in WAMP or there is some additional hashing or ... involved in the process.

So to change currently used default 'config'-file-based password you can browse "<host>/phpmyadmin/user_password.php" using your browser. You'll be prompted to enter your mysql credentials and then you can use the displayed form to change the stored password for the user you logged into previously.

Fade Effect on Link Hover?

I know in the question you state "I assume JavaScript is used to create this effect" but CSS can be used too, an example is below.


.fancy-link {
   color: #333333;
   text-decoration: none;
   transition: color 0.3s linear;
   -webkit-transition: color 0.3s linear;
   -moz-transition: color 0.3s linear;

.fancy-link:hover {
   color: #F44336;


<a class="fancy-link" href="#">My Link</a>

And here is a JSFIDDLE for the above code!

Marcel in one of the answers points out you can "transition multiple CSS properties" you can also use "all" to effect the element with all your :hover styles like below.


.fancy-link {
   color: #333333;
   text-decoration: none;
   transition: all 0.3s linear;
   -webkit-transition: all 0.3s linear;
   -moz-transition: all 0.3s linear;

.fancy-link:hover {
   color: #F44336;
   padding-left: 10px;


<a class="fancy-link" href="#">My Link</a>

And here is a JSFIDDLE for the "all" example!

How to pass all arguments passed to my bash script to a function of mine?

It's worth mentioning that you can specify argument ranges with this syntax.

function example() {
    echo "line1 ${@:1:1}"; #First argument
    echo "line2 ${@:2:1}"; #Second argument
    echo "line3 ${@:3}"; #Third argument onwards

I hadn't seen it mentioned.

SQL Query with Join, Count and Where

SELECT COUNT(*), table1.category_id, table2.category_name 
FROM table1 
INNER JOIN table2 ON table1.category_id=table2.category_id 
WHERE table1.colour <> 'red'
GROUP BY table1.category_id, table2.category_name 

Init function in javascript and how it works

The way I usually explain this to people is to show how it's similar to other JavaScript patterns.

First, you should know that there are two ways to declare a function (actually, there's at least five, but these are the two main culprits):

function foo() {/*code*/}


var foo = function() {/*code*/};

Even if this construction looks strange, you probably use it all the time when attaching events:


You should notice that the second form is not much different from a regular variable declaration:

var bar = 5;
var baz = 'some string';
var foo = function() {/*code*/};

But in JavaScript, you always have the choice between using a value directly or through a variable. If bar is 5, then the next two statements are equivalent:

var myVal = bar * 100; // use 'bar'
var myVal = 5 * 100;   // don't use 'bar'

Well, if you can use 5 on its own, why can't you use function() {\*code*\} on its own too? In fact, you can. And that's called an anonymous function. So these two examples are equivalent as well:

var foo = function() {/*code*/}; // use 'foo'

(function(){/*code*/})();        // don't use 'foo' 

The only difference you should see is in the extra brackets. That's simply because if you start a line with the keyword function, the parser will think you are declaring a function using the very first pattern at the top of this answer and throw a syntax error exception. So wrap your entire anonymous function inside a pair of braces and the problem goes away.

In other words, the following three statements are valid:

5;                        // pointless and stupid
'some string';            // pointless and stupid
(function(){/*code*/})(); // wonderfully powerful

[EDIT in 2020]

The previous version of my answer recommended Douglas Crockford's form of parens-wrapping for these "immediately invoked anonymous functions". User @RayLoveless recommended in 2012 to use the version shown now. Back then, before ES6 and arrow functions, there was no obvious idiomatic difference; you simply had to prevent the statement starting with the function keyword. In fact, there were lots of ways to do that. But using parens, these two statements were syntactically and idiomatically equivalent:

( function() { /* code */}() );
( function() { /* code */} )();

But user @zentechinc's comment below reminds me that arrow functions change all this. So now only one of these statements is correct.

( () => { /* code */ }() ); // Syntax error
( () => { /* code */ } )();

Why on earth does this matter? Actually, it's pretty easy to demonstrate. Remember an arrow function can come in two basic forms:

() => { return 5; };       // With a function body
() => { console.log(5); };

() => 5;                   // Or with a single expression
() => console.log(5);

Without parens wrapping this second type of arrow function, you end up with an idiomatic mess:

() => 5();              // How do you invoke a 5?
() => console.log(5)(); // console.log does not return a function!

Hash function for a string

Java's String implements hashCode like this:

public int hashCode()

Returns a hash code for this string. The hash code for a String object is computed as

     s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]

using int arithmetic, where s[i] is the ith character of the string, n is the length of the string, and ^ indicates exponentiation. (The hash value of the empty string is zero.) 

So something like this:

int HashTable::hash (string word) {
    int result = 0;
    for(size_t i = 0; i < word.length(); ++i) {
        result += word[i] * pow(31, i);
    return result;

Find Item in ObservableCollection without using a loop

ObservableCollection is a list so if you don't know the element position you have to look at each element until you find the expected one.

Possible optimization If your elements are sorted use a binary search to improve performances otherwise use a Dictionary as index.

Get a list of all the files in a directory (recursive)

The following works for me in Gradle / Groovy for build.gradle for an Android project, without having to import (NOTE: Does not recurse subdirectories, but when I found this solution I no longer cared about recursion, so you may not either):

FileCollection proGuardFileCollection = files { file('./proguard').listFiles() }
proGuardFileCollection.each {
    println "Proguard file located and processed: " + it

Turning multi-line string into single comma-separated

You can also print like this:

Just awk: using printf

bash-3.2$ cat sample.log
something1:    +12.0   (some unnecessary trailing data (this must go))
something2:    +15.5   (some more unnecessary trailing data)
something4:    +9.0   (some other unnecessary data)
something1:    +13.5  (blah blah blah)

bash-3.2$ awk ' { if($2 != "") { if(NR==1) { printf $2 } else { printf "," $2 } } }' sample.log

React this.setState is not a function

You no need to assign this to a local variable if you use arrow function. Arrow functions takes binding automatically and you can stay away with scope related issues.

Below code explains how to use arrow function in different scenarios

componentDidMount = () => {

    VK.init(() => {"API initialisation successful");
        VK.api('users.get',{fields: 'photo_50'},(data) => {
                that.setState({ //this available here and you can do setState
                    FirstName: data.response[0].first_name
    }, () => {"API initialisation failed");

    }, '5.34');

node.js http 'get' request with query string parameters

Check out the request module.

It's more full featured than node's built-in http client.

var request = require('request');

var propertiesObject = { field1:'test1', field2:'test2' };

request({url:url, qs:propertiesObject}, function(err, response, body) {
  if(err) { console.log(err); return; }
  console.log("Get response: " + response.statusCode);

What is %timeit in python?

Line magics are prefixed with the % character and work much like OS command-line calls: they get as an argument the rest of the line, where arguments are passed without parentheses or quotes. Cell magics are prefixed with a double %%, and they are functions that get as an argument not only the rest of the line, but also the lines below it in a separate argument.

How to center a View inside of an Android Layout?

I use android:layout_centerInParent="true" and it worked

Python JSON serialize a Decimal object

From the JSON Standard Document, as linked in

JSON is agnostic about the semantics of numbers. In any programming language, there can be a variety of number types of various capacities and complements, fixed or floating, binary or decimal. That can make interchange between different programming languages difficult. JSON instead offers only the representation of numbers that humans use: a sequence of digits. All programming languages know how to make sense of digit sequences even if they disagree on internal representations. That is enough to allow interchange.

So it's actually accurate to represent Decimals as numbers (rather than strings) in JSON. Bellow lies a possible solution to the problem.

Define a custom JSON encoder:

import json

class CustomJsonEncoder(json.JSONEncoder):

    def default(self, obj):
        if isinstance(obj, Decimal):
            return float(obj)
        return super(CustomJsonEncoder, self).default(obj)

Then use it when serializing your data:

json.dumps(data, cls=CustomJsonEncoder)

As noted from comments on the other answers, older versions of python might mess up the representation when converting to float, but that's not the case anymore.

To get the decimal back in Python:


This solution is hinted in Python 3.0 documentation on decimals:

To create a Decimal from a float, first convert it to a string.

Get time in milliseconds using C#

I use the following class. I found it on the Internet once, postulated to be the best NOW().

/// <summary>Class to get current timestamp with enough precision</summary>
static class CurrentMillis
    private static readonly DateTime Jan1St1970 = new DateTime (1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
    /// <summary>Get extra long current timestamp</summary>
    public static long Millis { get { return (long)((DateTime.UtcNow - Jan1St1970).TotalMilliseconds); } }

Source unknown.

JavaScript is in array

As mentioned before, if your browser supports indexOf(), great! If not, you need to pollyfil it or rely on an utility belt like lodash/underscore.

Just wanted to add this newer ES2016 addition (to keep this question updated):


if (blockedTile.includes("118")) {
    // found element

JQuery create a form and add elements to it programmatically

var form = $("<form/>", 
                 { action:'/myaction' }
         { type:'text', 
           style:'width:65%' }

          { type:'submit', 
            style:'width:30%' }


Align image to left of text on same line - Twitter Bootstrap3

I would use Bootstrap's grid to achieve the desired result. The class="img-responsive" works nicely. Something like:

    <div class="container-fluid">
        <div class="row">
            <div class="col-md-3"><img src="./pictures/placeholder.jpg" class="img-responsive" alt="Some picture" width="410" height="307"></div>
            <div class="col-md-9"><h1>Heading</h1><p>Your Information.</p></div>

Getting raw SQL query string from PDO prepared statements

Mike's answer is working good until you are using the "re-use" bind value.
For example:

SELECT * FROM `an_modules` AS `m` LEFT JOIN `an_module_sites` AS `ms` ON m.module_id = ms.module_id WHERE 1 AND `module_enable` = :module_enable AND `site_id` = :site_id AND (`module_system_name` LIKE :search OR `module_version` LIKE :search)

The Mike's answer can only replace first :search but not the second.
So, I rewrite his answer to work with multiple parameters that can re-used properly.

public function interpolateQuery($query, $params) {
    $keys = array();
    $values = $params;
    $values_limit = [];

    $words_repeated = array_count_values(str_word_count($query, 1, ':_'));

    # build a regular expression for each parameter
    foreach ($params as $key => $value) {
        if (is_string($key)) {
            $keys[] = '/:'.$key.'/';
            $values_limit[$key] = (isset($words_repeated[':'.$key]) ? intval($words_repeated[':'.$key]) : 1);
        } else {
            $keys[] = '/[?]/';
            $values_limit = [];

        if (is_string($value))
            $values[$key] = "'" . $value . "'";

        if (is_array($value))
            $values[$key] = "'" . implode("','", $value) . "'";

        if (is_null($value))
            $values[$key] = 'NULL';

    if (is_array($values)) {
        foreach ($values as $key => $val) {
            if (isset($values_limit[$key])) {
                $query = preg_replace(['/:'.$key.'/'], [$val], $query, $values_limit[$key], $count);
            } else {
                $query = preg_replace(['/:'.$key.'/'], [$val], $query, 1, $count);
        unset($key, $val);
    } else {
        $query = preg_replace($keys, $values, $query, 1, $count);
    unset($keys, $values, $values_limit, $words_repeated);

    return $query;

How to convert a Collection to List?

@Kunigami: I think you may be mistaken about Guava's newArrayList method. It does not check whether the Iterable is a List type and simply return the given List as-is. It always creates a new list:

@GwtCompatible(serializable = true)
public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
  checkNotNull(elements); // for GWT
  // Let ArrayList's sizing logic work, if possible
  return (elements instanceof Collection)
      ? new ArrayList<E>(Collections2.cast(elements))
      : newArrayList(elements.iterator());

UTC Date/Time String to Timezone

Assuming the UTC is not included in the string then:

$datestring = '2011-01-01 15:00:00';  //Pulled in from somewhere
$date = date('Y-m-d H:i:s T',strtotime($datestring . ' UTC'));
echo $date;  //Should get '2011-01-01 10:00:00 EST' or something like that

Or you could use the DateTime object.

How can I execute PHP code from the command line?

On the command line:

php -i | grep sourceguardian

If it's there, then you'll get some text. If not, you won't get a thing.

How to backup Sql Database Programmatically in C#

            SqlConnection con = new SqlConnection();
            SqlCommand sqlcmd = new SqlCommand();
            SqlDataAdapter da = new SqlDataAdapter();
            DataTable dt = new DataTable();

            con.ConnectionString = ConfigurationManager.ConnectionStrings["MyConString"].ConnectionString;
            string backupDIR = "~/BackupDB";
            string path = Server.MapPath(backupDIR);

                var databaseName = "MyFirstDatabase";
                string saveFileName = "HiteshBackup";
                sqlcmd = new SqlCommand("backup database" +databaseName.BKSDatabaseName + "to disk='" + path + "\\" + saveFileName + ".Bak'", con);

                ViewBag.Success = "Backup database successfully";
                return View("Create");
            catch (Exception ex)
                ViewBag.Error = "Error Occured During DB backup process !<br>" + ex.ToString();
                return View("Create");

The program can’t start because MSVCR71.dll is missing from your computer. Try reinstalling the program to fix this program

MY SOLUTION!!!!!!! I fixed this problem when I was trying to install business objects. When the installer failed to register .dll's I inputted the MSVCR71.dll into both system32 and sysWOW64 then clicked retry. Installation finished. I did try adding this in before and after install but, install still failed.

Only on Firefox "Loading failed for the <script> with source"

I had the same problem (different web app though) with the error message and it turned out to be the MIME-Type for .js files was text/x-js instead of application/javascript due to a duplicate entry in mime.types on the server that was responsible for serving the js files. It seems that this is happening if the header X-Content-Type-Options: nosniff is set, which makes Firefox (and Chrome) block the content of the js files.

Calculate Age in MySQL (InnoDb)

select *,year(curdate())-year(dob) - (right(curdate(),5) < right(dob,5)) as age from your_table

in this way you consider even month and day of birth in order to have a more accurate age calculation.

Pass a data.frame column name to a function

If you are trying to build this function within an R package or simply want to reduce complexity, you can do the following:

test_func <- function(df, column) {
  if (column %in% colnames(df)) {
    return(max(df[, column, with=FALSE])) 
  } else {
    stop(cat(column, "not in data.frame columns."))

The argument with=FALSE "disables the ability to refer to columns as if they are variables, thereby restoring the “data.frame mode” (per CRAN documentation). The if statement is a quick way to catch if the column name provided is within the data.frame. Could also use tryCatch error handling here.

Unable to find the requested .Net Framework Data Provider. It may not be installed. - when following mvc3 tutorial

Add these lines to your web.config file:

               <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory,MySql.Data,  Version=, Culture=neutral, PublicKeyToken=C5687FC88969C44D"/>

Change your provider from MySQL to SQL Server or whatever database provider you are connecting to.

Getting a count of objects in a queryset in django

Another way of doing this would be using Aggregation. You should be able to achieve a similar result using a single query. Such as this:


I did not test this specific query, but this should output a count of the items for each value in contests as a dictionary.

Basic text editor in command prompt?

I want to add that it is very strange to introduce Core and Nano servers without native console full-featured editor. Like others I`ll recommend to use vim or nano. But my suggestion is to install it via OneGet (require WMF5)! They both are presented in Chocolatey repository so installation is simple and fast:

PS C:> Find-Package -Name vim | Format-Table -AutoSize
Name Version Status    ProviderName Source     Summary
---- ------- ------    ------------ ------     -------
vim  7.4.638 Available Chocolatey   chocolatey Vim is an advanced text editor...

PS C:> Install-Package vim

Python multiprocessing PicklingError: Can't pickle <type 'function'>

This solution requires only the installation of dill and no other libraries as pathos

def apply_packed_function_for_map((dumped_function, item, args, kwargs),):
    Unpack dumped function as target function and call it with arguments.

    :param (dumped_function, item, args, kwargs):
        a tuple of dumped function and its arguments
        result of target function
    target_function = dill.loads(dumped_function)
    res = target_function(item, *args, **kwargs)
    return res

def pack_function_for_map(target_function, items, *args, **kwargs):
    Pack function and arguments to object that can be sent from one
    multiprocessing.Process to another. The main problem is:
        «*» or «apply*»
        cannot use class methods or closures.
    It solves this problem with «dill».
    It works with target function as argument, dumps it («with dill»)
    and returns dumped function with arguments of target function.
    For more performance we dump only target function itself
    and don't dump its arguments.
    How to use (pseudo-code):

        ~>>> import multiprocessing
        ~>>> images = [...]
        ~>>> pool = multiprocessing.Pool(100500)
        ~>>> features =
        ~...     *pack_function_for_map(
        ~...         super(Extractor, self).extract_features,
        ~...         images,
        ~...         type='png'
        ~...         **options,
        ~...     )
        ~... )

    :param target_function:
        function, that you want to execute like  target_function(item, *args, **kwargs).
    :param items:
        list of items for map
    :param args:
        positional arguments for target_function(item, *args, **kwargs)
    :param kwargs:
        named arguments for target_function(item, *args, **kwargs)
    :return: tuple(function_wrapper, dumped_items)
        It returs a tuple with
            * function wrapper, that unpack and call target function;
            * list of packed target function and its' arguments.
    dumped_function = dill.dumps(target_function)
    dumped_items = [(dumped_function, item, args, kwargs) for item in items]
    return apply_packed_function_for_map, dumped_items

It also works for numpy arrays.

How can I make an entire HTML form "readonly"?

Not all form elements can be set to readonly, for example:

  • checkboxes
  • radio boxes
  • file upload
  • ...more..

Then the reasonable solution would be to set all form elements' disabled attributes to true, since the OP did not state that the specific "locked" form should be sent to the server (which the disabled attribute does not allow).

Another solution, which is presented in the demo below, is to place a layer on top of the form element which will prevent any interaction with all the elements inside the form element, since that layer is set with a greater z-index value:


var form = document.forms[0], // form element to be "readonly"_x000D_
    btn1 = document.querySelectorAll('button')[0],_x000D_
    btn2 = document.querySelectorAll('button')[1]_x000D_
btn1.addEventListener('click', lockForm)_x000D_
btn2.addEventListener('click', lockFormByCSS)_x000D_
function lockForm(){_x000D_
  [] form.elements ).forEach(function(item){_x000D_
      item.disabled = !item.disabled;_x000D_
function lockFormByCSS(){_x000D_
form{ position:relative; } _x000D_
button.on{ color:red; }
<button type='button'>Lock / Unlock Form</button>_x000D_
<button type='button'>Lock / Unlock Form (with CSS)</button>_x000D_
    <legend>Some Form</legend>_x000D_
    <input placeholder='text input'>_x000D_
    <input type='file'>_x000D_
    <textarea placeholder='textarea'></textarea>_x000D_
    <label><input type='checkbox'>Checkbox</label>_x000D_
    <label><input type='radio' name='r'>option 1</label>_x000D_
    <label><input type='radio' name='r' checked>option 2</label>_x000D_
    <label><input type='radio' name='r'>option 3</label>_x000D_
      <option>options 1</option>_x000D_
      <option>options 2</option>_x000D_
      <option selected>options 3</option>_x000D_

Making HTTP Requests using Chrome Developer tools

    type : "home", id : "0"_x000D_
<script src=""></script>

VBA copy rows that meet criteria to another sheet

You need to specify workseet. Change line

If Worksheet.Cells(i, 1).Value = "X" Then


If Worksheets("Sheet2").Cells(i, 1).Value = "X" Then


Try to use following code (but it's not the best approach. As @SiddharthRout suggested, consider about using Autofilter):

Sub LastRowInOneColumn()
   Dim LastRow As Long
   Dim i As Long, j As Long

   'Find the last used row in a Column: column A in this example
   With Worksheets("Sheet2")
      LastRow = .Cells(.Rows.Count, "A").End(xlUp).Row
   End With

   MsgBox (LastRow)
   'first row number where you need to paste values in Sheet1'
   With Worksheets("Sheet1")
      j = .Cells(.Rows.Count, "A").End(xlUp).Row + 1
   End With 

   For i = 1 To LastRow
       With Worksheets("Sheet2")
           If .Cells(i, 1).Value = "X" Then
               .Rows(i).Copy Destination:=Worksheets("Sheet1").Range("A" & j)
               j = j + 1
           End If
       End With
   Next i
End Sub

Correct file permissions for WordPress

I can't tell you whether or not this is correct, but I am using a Bitnami image over Google Compute App Engine. I has having problems with plugins and migration, and after further messing things up by chmod'ing permissions, I found these three lines which solved all my problems. Not sure if it's the proper way but worked for me.

sudo chown -R bitnami:daemon /opt/bitnami/apps/wordpress/htdocs/
sudo find /opt/bitnami/apps/wordpress/htdocs/ -type f -exec chmod 664 {} \;
sudo find /opt/bitnami/apps/wordpress/htdocs/ -type d -exec chmod 775 {} \;

How do you launch the JavaScript debugger in Google Chrome?

Windows and Linux:

Ctrl + Shift + I keys to open Developer Tools

Ctrl + Shift + J to open Developer Tools and bring focus to the Console.

Ctrl + Shift + C to toggle Inspect Element mode.


? + ? + I keys to open Developer Tools

? + ? + J to open Developer Tools and bring focus to the Console.

? + ? + C to toggle Inspect Element mode.


Other shortcuts

Warning: Null value is eliminated by an aggregate or other SET operation in Aqua Data Studio

One way to solve this problem is by turning the warnings off.


TimePicker Dialog from clicking EditText

For me the dialogue appears more than one if I click the dpFlightDate edit text more than one time same for the timmer dialog . how can I avoid this dialog to appear only once and if the user click's 2nd time the dialog must not appear again ie if dialog is on the screen ?

          // perform click event on edit text
            dpFlightDate.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    // calender class's instance and get current date , month and year from calender
                    final Calendar c = Calendar.getInstance();
                    int mYear = c.get(Calendar.YEAR); // current year
                    int mMonth = c.get(Calendar.MONTH); // current month
                    int mDay = c.get(Calendar.DAY_OF_MONTH); // current day
                    // date picker dialog
                    datePickerDialog = new DatePickerDialog(frmFlightDetails.this,
                            new DatePickerDialog.OnDateSetListener() {
                                public void onDateSet(DatePicker view, int year,
                                                      int monthOfYear, int dayOfMonth) {
                                    // set day of month , month and year value in the edit text
                                    dpFlightDate.setText(dayOfMonth + "/"
                                            + (monthOfYear + 1) + "/" + year);

                            }, mYear, mMonth, mDay);
            tpFlightTime.setOnClickListener(new View.OnClickListener() {
                public void onClick(View view) {
                    // Use the current time as the default values for the picker
                    final Calendar c = Calendar.getInstance();
                    int hour = c.get(Calendar.HOUR_OF_DAY);
                    int minute = c.get(Calendar.MINUTE);
                    // Create a new instance of TimePickerDialog
                    timePickerDialog = new TimePickerDialog(frmFlightDetails.this, new TimePickerDialog.OnTimeSetListener() {
                        public void onTimeSet(TimePicker timePicker, int selectedHour, int selectedMinute) {
                            tpFlightTime.setText( selectedHour + ":" + selectedMinute);
                    }, hour, minute, true);//Yes 24 hour time
                    timePickerDialog.setTitle("Select Time");

Can I stretch text using CSS?

I'll answer for horizontal stretching of text, since the vertical is the easy part - just use "transform: scaleY()"

.stretched-text {
  letter-spacing: 2px;
  display: inline-block;
  font-size: 32px;
  transform: scaleY(0.5);
  transform-origin: 0 0;
  margin-bottom: -50%;
span {
  font-size: 16px;
  vertical-align: top;
<span class="stretched-text">this is some stretched text</span>
<span>and this is some random<br />triple line <br />not stretched text</span>

letter-spacing just adds space between letters, stretches nothing, but it's kinda relative

inline-block because inline elements are too restrictive and the code below wouldn't work otherwise

Now the combination that makes the difference

font-size to get to the size we want - that way the text will really be of the length it's supposed to be and the text before and after it will appear next to it (scaleX is just for show, the browser still sees the element at its original size when positioning other elements).

scaleY to reduce the height of the text, so that it's the same as the text beside it.

transform-origin to make the text scale from the top of the line.

margin-bottom set to a negative value, so that the next line will not be far below - preferably percentage, so that we won't change the line-height property. vertical-align set to top, to prevent the text before or after from floating to other heights (since the stretched text has a real size of 32px)

-- The simple span element has a font-size, only as a reference.

The question asked for a way to prevent the boldness of the text caused by the stretch and I still haven't given one, BUT the font-weight property has more values than just normal and bold.

I know, you just can't see that, but if you search for the appropriate fonts, you can use the more values.

Setting up and using environment variables in IntelliJ Idea

It is possible to reference an intellij 'Path Variable' in an intellij 'Run Configuration'.

In 'Path Variables' create a variable for example ANALYTICS_VERSION.

In a 'Run Configuration' under 'Environment Variables' add for example the following:


To answer the original question you would need to add an APP_HOME environment variable to your run configuration which references the path variable:


PHP Regex to check date is in YYYY-MM-DD format

You can make it this way:

if (preg_match("/\d{4}\-\d{2}-\d{2}/", $date)) {
    echo 'true';
} else {
    echo 'false';

but you'd better use this one:

$date = DateTime::createFromFormat('Y-m-d', $date);
if ($date) {
    echo $date -> format('Y-m-d');

in this case you'll get an object which is muck easier to use than just strings.

Is it possible only to declare a variable without assigning any value in Python?

I usually initialize the variable to something that denotes the type like

var = ""


var = 0

If it is going to be an object then don't initialize it until you instantiate it:

var = Var()

Log all queries in mysql

OS / mysql version:

$ uname -a
Darwin Raphaels-MacBook-Pro.local 15.6.0 Darwin Kernel Version 15.6.0: Thu Jun 21 20:07:40 PDT 2018; root:xnu-3248.73.11~1/RELEASE_X86_64 x86_64

$ mysql --version
/usr/local/mysql/bin/mysql  Ver 14.14 Distrib 5.6.23, for osx10.8 (x86_64) using  EditLine wrapper

Adding logging (example, I don't think /var/log/... is the best path on Mac OS but that worked:

sudo vi ./usr/local/mysql-5.6.23-osx10.8-x86_64/my.cnf

general_log = on

Restarted Mysql


$ sudo tail -f /var/log/mysql/mysqld_general.log
181210  9:41:04    21 Connect   root@localhost on employees
           21 Query /* mysql-connector-java-5.1.47 ( Revision: fe1903b1ecb4a96a917f7ed3190d80c049b1de29 ) */SELECT  @@session.auto_increment_increment AS auto_increment_increment, @@character_set_client AS character_set_client, @@character_set_connection AS character_set_connection, @@character_set_results AS character_set_results, @@character_set_server AS character_set_server, @@collation_server AS collation_server, @@collation_connection AS collation_connection, @@init_connect AS init_connect, @@interactive_timeout AS interactive_timeout, @@license AS license, @@lower_case_table_names AS lower_case_table_names, @@max_allowed_packet AS max_allowed_packet, @@net_buffer_length AS net_buffer_length, @@net_write_timeout AS net_write_timeout, @@query_cache_size AS query_cache_size, @@query_cache_type AS query_cache_type, @@sql_mode AS sql_mode, @@system_time_zone AS system_time_zone, @@time_zone AS time_zone, @@tx_isolation AS transaction_isolation, @@wait_timeout AS wait_timeout
           21 Query SET NAMES latin1
           21 Query SET character_set_results = NULL
           21 Query SET autocommit=1
           21 Query SELECT USER()
           21 Query SELECT USER()
181210  9:41:10    21 Query show tables
181210  9:41:25    21 Query select count(*) from current_dept_emp

How to delete an element from a Slice in Golang

Maybe you can try this method:

// DelEleInSlice delete an element from slice by index
//  - arr: the reference of slice
//  - index: the index of element will be deleted
func DelEleInSlice(arr interface{}, index int) {
    vField := reflect.ValueOf(arr)
    value := vField.Elem()
    if value.Kind() == reflect.Slice || value.Kind() == reflect.Array {
        result := reflect.AppendSlice(value.Slice(0, index), value.Slice(index+1, value.Len()))


arrInt := []int{0, 1, 2, 3, 4, 5}
arrStr := []string{"0", "1", "2", "3", "4", "5"}
DelEleInSlice(&arrInt, 3)
DelEleInSlice(&arrStr, 4)


0, 1, 2, 4, 5
"0", "1", "2", "3", "5"

Convert byte to string in Java

System.out.println(new String(new byte[]{ (byte)0x63 }, "US-ASCII"));

Note especially that converting bytes to Strings always involves an encoding. If you do not specify it, you'll be using the platform default encoding, which means the code can break when running in different environments.

Dots in URL causes 404 with ASP.NET mvc and IIS

Also, (related) check the order of your handler mappings. We had a .ashx with a .svc (e.g. /foo.asmx/bar.svc/path) in the path after it. The .svc mapping was first so 404 for the .svc path which matched before the .asmx. Havn't thought too much but maybe url encodeing the path would take care of this.

How can I start PostgreSQL server on Mac OS X?

docker run --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d postgres

Convert NSDate to String in iOS Swift

I always use this code while converting Date to String . (Swift 3)

extension Date
    func toString( dateFormat format  : String ) -> String
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = format
        return dateFormatter.string(from: self)


and call like this . .

let today = Date()
today.toString(dateFormat: "dd-MM")

How to make an anchor tag refer to nothing?

What do you mean by nothing?

<a href='about:blank'>blank page</a>


<a href='whatever' onclick='return false;'>won't navigate</a>

How to create SPF record for multiple IPs?

Try this:

v=spf1 ~all

"UnboundLocalError: local variable referenced before assignment" after an if statement

I was facing same issue in my exercise. Although not related, yet might give some reference. I didn't get any error once I placed addition_result = 0 inside function. Hope it helps! Apologize if this answer is not in context.

user_input = input("Enter multiple values separated by comma > ")

def add_numbers(num_list):
    addition_result = 0
    for i in num_list:
        addition_result = addition_result + i


How to insert a row in an HTML table body in JavaScript

You can use the following example:

<table id="purches">
            <th>Transaction Date</th>
            <th>Transaction Amount</th>

    <!--  <tr th:each="person: ${list}"    >
            <td><li th:each="person: ${list}" th:text="|${person.description}|"></li></td>
            <td><li th:each="person: ${list}" th:text="|${person.price}|"></li></td>
            <td><li th:each="person: ${list}" th:text="|${person.available}|"></li></td>
            <td><li th:each="person: ${list}" th:text="|${person.from}|"></li></td>

    <tbody id="feedback">

JavaScript file:

    type: "POST",
    contentType: "application/json",
    url: "/search",
    data: JSON.stringify(search),
    dataType: 'json',
    cache: false,
    timeout: 600000,
    success: function (data) {
        //  var json = "<h4>Ajax Response</h4><pre>"  + JSON.stringify(data, null, 4) + "</pre>";
        // $('#feedback').html(json);
        console.log("SUCCESS: ", data);
        //$("#btn-search").prop("disabled", false);

        for (var i = 0; i < data.length; i++) {
            //$("#feedback").append('<tr><td>' + data[i].accountNumber + '</td><td>' + data[i].category + '</td><td>' + data[i].ssn + '</td></tr>');
            $('#feedback').append('<tr><td>' + data[i].accountNumber + '</td><td>' + data[i].category + '</td><td>' + data[i].ssn + '</td><td>' + data[i].ssn + '</td><td>' + data[i].ssn + '</td></tr>');

    error: function (e) {
        var json = "<h4>Ajax Response</h4><pre>" + e.responseText + "</pre>";

        console.log("ERROR: ", e);
        $("#btn-search").prop("disabled", false);

Element-wise addition of 2 lists?

This will work for 2 or more lists; iterating through the list of lists, but using numpy addition to deal with elements of each list

import numpy as np
list1=[1, 2, 3]
list2=[4, 5, 6]

lists = [list1, list2]
list_sum = np.zeros(len(list1))
for i in lists:
   list_sum += i
list_sum = list_sum.tolist()    

[5.0, 7.0, 9.0]

.htaccess deny from all

This syntax has changed with the newer Apache HTTPd server, please see upgrade to apache 2.4 doc for full details.

2.2 configuration syntax was

Order deny,allow
Deny from all

2.4 configuration now is

Require all denied

Thus, this 2.2 syntax

order deny,allow
deny from all
allow from

Would ne now written

Require local

How do I convert dmesg timestamp to custom date format?

you will need to reference the "btime" in /proc/stat, which is the Unix epoch time when the system was latest booted. Then you could base on that system boot time and then add on the elapsed seconds given in dmesg to calculate timestamp for each events.

How to display the function, procedure, triggers source code in postgresql?

Here are few examples from PostgreSQL-9.5

Display list:

  1. Functions: \df+
  2. Triggers : \dy+

Display Definition:

postgres=# \sf
function name is required

postgres=# \sf pg_reload_conf()
CREATE OR REPLACE FUNCTION pg_catalog.pg_reload_conf()
 RETURNS boolean
 LANGUAGE internal
AS $function$pg_reload_conf$function$

postgres=# \sf pg_encoding_to_char
CREATE OR REPLACE FUNCTION pg_catalog.pg_encoding_to_char(integer)
 LANGUAGE internal
AS $function$PG_encoding_to_char$function$

Install mysql-python (Windows)

try running the following command:

pip install mysqlclient

How to deal with bad_alloc in C++?

You can catch it like any other exception:

try {
catch (const std::bad_alloc&) {
  return -1;

Quite what you can usefully do from this point is up to you, but it's definitely feasible technically.

In general you cannot, and should not try, to respond to this error. bad_alloc indicates that a resource cannot be allocated because not enough memory is available. In most scenarios your program cannot hope to cope with that, and terminating soon is the only meaningful behaviour.

Worse, modern operating systems often over-allocate: on such systems, malloc and new can return a valid pointer even if there is not enough free memory left – std::bad_alloc will never be thrown, or is at least not a reliable sign of memory exhaustion. Instead, attempts to access the allocated memory will then result in a segmentation fault, which is not catchable (you can handle the segmentation fault signal, but you cannot resume the program afterwards).

The only thing you could do when catching std::bad_alloc is to perhaps log the error, and try to ensure a safe program termination by freeing outstanding resources (but this is done automatically in the normal course of stack unwinding after the error gets thrown if the program uses RAII appropriately).

In certain cases, the program may attempt to free some memory and try again, or use secondary memory (= disk) instead of RAM but these opportunities only exist in very specific scenarios with strict conditions:

  1. The application must ensure that it runs on a system that does not overcommit memory, i.e. it signals failure upon allocation rather than later.
  2. The application must be able to free memory immediately, without any further accidental allocations in the meantime.

It’s exceedingly rare that applications have control over point 1 — userspace applications never do, it’s a system-wide setting that requires root permissions to change.1

OK, so let’s assume you’ve fixed point 1. What you can now do is for instance use a LRU cache for some of your data (probably some particularly large business objects that can be regenerated or reloaded on demand). Next, you need to put the actual logic that may fail into a function that supports retry — in other words, if it gets aborted, you can just relaunch it:

lru_cache<widget> widget_cache;

double perform_operation(int widget_id) {
    std::optional<widget> maybe_widget = widget_cache.find_by_id(widget_id);
    if (not maybe_widget) {
        maybe_widget =, load_widget_from_disk(widget_id));
    return maybe_widget->frobnicate();


for (int num_attempts = 0; num_attempts < MAX_NUM_ATTEMPTS; ++num_attempts) {
    try {
        return perform_operation(widget_id);
    } catch (std::bad_alloc const&) {
        if (widget_cache.empty()) throw; // memory error elsewhere.

// Handle too many failed attempts here.

But even here, using std::set_new_handler instead of handling std::bad_alloc provides the same benefit and would be much simpler.

1 If you’re creating an application that does control point 1, and you’re reading this answer, please shoot me an email, I’m genuinely curious about your circumstances.

What is the C++ Standard specified behavior of new in c++?

The usual notion is that if new operator cannot allocate dynamic memory of the requested size, then it should throw an exception of type std::bad_alloc.
However, something more happens even before a bad_alloc exception is thrown:

C++03 Section says

An allocation function that fails to allocate storage can invoke the currently installed new_handler(, if any. [Note: A program-supplied allocation function can obtain the address of the currently installed new_handler using the set_new_handler function (] If an allocation function declared with an empty exception-specification (15.4), throw(), fails to allocate storage, it shall return a null pointer. Any other allocation function that fails to allocate storage shall only indicate failure by throw-ing an exception of class std::bad_alloc ( or a class derived from std::bad_alloc.

Consider the following code sample:

#include <iostream>
#include <cstdlib>

// function to call if operator new can't allocate enough memory or error arises
void outOfMemHandler()
    std::cerr << "Unable to satisfy request for memory\n";


int main()
    //set the new_handler

    //Request huge memory size, that will cause ::operator new to fail
    int *pBigDataArray = new int[100000000L];

    return 0;

In the above example, operator new (most likely) will be unable to allocate space for 100,000,000 integers, and the function outOfMemHandler() will be called, and the program will abort after issuing an error message.

As seen here the default behavior of new operator when unable to fulfill a memory request, is to call the new-handler function repeatedly until it can find enough memory or there is no more new handlers. In the above example, unless we call std::abort(), outOfMemHandler() would be called repeatedly. Therefore, the handler should either ensure that the next allocation succeeds, or register another handler, or register no handler, or not return (i.e. terminate the program). If there is no new handler and the allocation fails, the operator will throw an exception.

What is the new_handler and set_new_handler?

new_handler is a typedef for a pointer to a function that takes and returns nothing, and set_new_handler is a function that takes and returns a new_handler.

Something like:

typedef void (*new_handler)();
new_handler set_new_handler(new_handler p) throw();

set_new_handler's parameter is a pointer to the function operator new should call if it can't allocate the requested memory. Its return value is a pointer to the previously registered handler function, or null if there was no previous handler.

How to handle out of memory conditions in C++?

Given the behavior of newa well designed user program should handle out of memory conditions by providing a proper new_handlerwhich does one of the following:

Make more memory available: This may allow the next memory allocation attempt inside operator new's loop to succeed. One way to implement this is to allocate a large block of memory at program start-up, then release it for use in the program the first time the new-handler is invoked.

Install a different new-handler: If the current new-handler can't make any more memory available, and of there is another new-handler that can, then the current new-handler can install the other new-handler in its place (by calling set_new_handler). The next time operator new calls the new-handler function, it will get the one most recently installed.

(A variation on this theme is for a new-handler to modify its own behavior, so the next time it's invoked, it does something different. One way to achieve this is to have the new-handler modify static, namespace-specific, or global data that affects the new-handler's behavior.)

Uninstall the new-handler: This is done by passing a null pointer to set_new_handler. With no new-handler installed, operator new will throw an exception ((convertible to) std::bad_alloc) when memory allocation is unsuccessful.

Throw an exception convertible to std::bad_alloc. Such exceptions are not be caught by operator new, but will propagate to the site originating the request for memory.

Not return: By calling abort or exit.

C# Linq Group By on multiple columns

var consolidatedChildren =
    from c in children
    group c by new
    } into gcs
    select new ConsolidatedChild()
        School = gcs.Key.School,
        Friend = gcs.Key.Friend,
        FavoriteColor = gcs.Key.FavoriteColor,
        Children = gcs.ToList(),

var consolidatedChildren =
        .GroupBy(c => new
        .Select(gcs => new ConsolidatedChild()
            School = gcs.Key.School,
            Friend = gcs.Key.Friend,
            FavoriteColor = gcs.Key.FavoriteColor,
            Children = gcs.ToList(),

When is JavaScript synchronous?

To someone who really understands how JS works this question might seem off, however most people who use JS do not have such a deep level of insight (and don't necessarily need it) and to them this is a fairly confusing point, I will try to answer from that perspective.

JS is synchronous in the way its code is executed. each line only runs after the line before it has completed and if that line calls a function after that is complete etc...

The main point of confusion arises from the fact that your browser is able to tell JS to execute more code at anytime (similar to how you can execute more JS code on a page from the console). As an example JS has Callback functions who's purpose is to allow JS to BEHAVE asynchronously so further parts of JS can run while waiting for a JS function that has been executed (I.E. a GET call) to return back an answer, JS will continue to run until the browser has an answer at that point the event loop (browser) will execute the JS code that calls the callback function.

Since the event loop (browser) can input more JS to be executed at any point in that sense JS is asynchronous (the primary things that will cause a browser to input JS code are timeouts, callbacks and events)

I hope this is clear enough to be helpful to somebody.

Remove object from a list of objects in python

You could try this to dynamically remove an object from an array without looping through it? Where e and t are just random objects.

>>> e = {'b':1, 'w': 2}
>>> t = {'b':1, 'w': 3}
>>> p = [e,t]
>>> p
[{'b': 1, 'w': 2}, {'b': 1, 'w': 3}]
>>> p.pop(p.index({'b':1, 'w': 3}))
{'b': 1, 'w': 3}
>>> p
[{'b': 1, 'w': 2}]

python how to "negate" value : if true return false, if false return true

Use the not boolean operator:

nyval = not myval

not returns a boolean value (True or False):

>>> not 1
>>> not 0

If you must have an integer, cast it back:

nyval = int(not myval)

However, the python bool type is a subclass of int, so this may not be needed:

>>> int(not 0)
>>> int(not 1)
>>> not 0 == 1
>>> not 1 == 0

Email & Phone Validation in Swift

File-New-File.Make a Swift class named AppExtension.Add the following.

        extension UIViewController{
            func validateEmailAndGetBoolValue(candidate: String) -> Bool {
                let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,6}"
                return NSPredicate(format: "SELF MATCHES %@", emailRegex).evaluateWithObject(candidate)

        var emailValidator:Bool?
        self.emailValidator =  self.validateEmailAndGetBoolValue(resetEmail!)
                        print("emailValidator : "+String(self.emailValidator?.boolValue))

        Use a loop to alternate desired results.

        extension String
        //Validate Email
            var isEmail: Bool {
                do {
                    let regex = try NSRegularExpression(pattern: "^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$", options: .CaseInsensitive)
                    return regex.firstMatchInString(self, options: NSMatchingOptions(rawValue: 0), range: NSMakeRange(0, self.characters.count)) != nil
                } catch {
                    return false


                        self.view.makeToast(message: "Sending OTP")
                            self.view.makeToast(message: "Please enter a valid email")

First char to upper case

Or you can do

s = Character.toUpperCase(s.charAt(0)) + s.substring(1); 

How do I do top 1 in Oracle?

With Oracle 12c (June 2013), you are able to use it like the following.


How do I change db schema to dbo

Move table from dbo schema to MySchema:


Move table from MySchema to dbo schema:


mysql query result into php array

What about this:

while ($row = mysql_fetch_array($result)) 
    $new_array[$row['id']]['id'] = $row['id'];
    $new_array[$row['id']]['link'] = $row['link'];

To retrieve link and id:

foreach($new_array as $array)
   echo $array['id'].'<br />';
   echo $array['link'].'<br />';

What does the colon (:) operator do?

In your specific case,

String cardString = "";
for (PlayingCard c : this.list)  // <--
    cardString = cardString + c + "\n";

this.list is a collection (list, set, or array), and that code assigns c to each element of the collection.

So, if this.list were a collection {"2S", "3H", "4S"} then the cardString on the end would be this string:


Could not find module FindOpenCV.cmake ( Error in configuration process)

Another possibility is to denote where you can find OpenCV_DIR in the CMakeLists.txt file. For example, the following cmake scripts work for me:

cmake_minimum_required(VERSION 2.8)


set(OpenCV_CUDA OFF)
set(OpenCV_DIR "${CMAKE_SOURCE_DIR}/../install")

find_package(OpenCV REQUIRED)



file(GLOB my_source_files ./src/*)

add_executable( performance_test ${my_source_files})

target_link_libraries(performance_test ${OpenCV_LIBS})

Just to remind that you should set OpenCV_STATIC and OpenCV_CUDA as well before you invoke OpenCVConfig.cmake. In my case the built library is static library that does not use CUDA.

How can I tell where mongoDB is storing data? (its not in the default /data/db!)

When you start it up it shows you. But I don't know if it is something you can do or not on your host. If you have access to the command line and can restart the service, you will get something like:

    2016-11-15T12:57:09.182-0500 I CONTROL  [initandlisten]
 MongoDB starting : pid=16448 port=27017 dbpath=C:\data\db\ 

Excel - match data from one range to another and get the value from the cell to the right of the matched data

Put this formula in cell d31 and copy down to d39


Here's what is going on. VLOOKUP:

  • Takes a value (here the contents of b31),
  • Looks for it in the first column of a range (f3:f12 in the range f3:g12), and
  • Returns the value for the corresponding row in a column in that range (in this case, the 2nd column or g3:g12 of the range f3:g12).

As you know, the last argument of VLOOKUP sets the match type, with FALSE or 0 indicating an exact match.

Finally, IFERROR handles the #N/A when VLOOKUP does not find a match.

Easy interview question got harder: given numbers 1..100, find the missing number(s) given exactly k are missing

We can solve Q2 by summing both the numbers themselves, and the squares of the numbers.

We can then reduce the problem to

k1 + k2 = x
k1^2 + k2^2 = y

Where x and y are how far the sums are below the expected values.

Substituting gives us:

(x-k2)^2 + k2^2 = y

Which we can then solve to determine our missing numbers.

python: order a list of numbers without built-in sort, min, max function

data = [3, 1, 5, 2, 4]
n = len(data)
    for i in range(n):
        for j in range(1,n):
            if data[j-1] > data[j]:
                (data[j-1], data[j]) = (data[j], data[j-1])

Fastest way to reset every value of std::vector<int> to 0

If it's just a vector of integers, I'd first try:

memset(&my_vector[0], 0, my_vector.size() * sizeof my_vector[0]);

It's not very C++, so I'm sure someone will provide the proper way of doing this. :)

Android: Proper Way to use onBackPressed() with Toast

I would implement a dialog asking the user if they wanted to exit and then call super.onBackPressed() if they did.

public void onBackPressed() {
    new AlertDialog.Builder(this)
        .setTitle("Really Exit?")
        .setMessage("Are you sure you want to exit?")
        .setNegativeButton(, null)
        .setPositiveButton(android.R.string.yes, new OnClickListener() {

            public void onClick(DialogInterface arg0, int arg1) {

In the above example, you'll need to replace WelcomeActivity with the name of your activity.

Renaming files using node.js

For linux/unix OS, you can use the shell syntax

const shell = require('child_process').execSync ; 

const currentPath= `/path/to/name.png`;
const newPath= `/path/to/another_name.png`;

shell(`mv ${currentPath} ${newPath}`);

That's it!

How do I remove all HTML tags from a string without knowing which tags are in it?

You can parse the string using Html Agility pack and get the InnerText.

    HtmlDocument htmlDoc = new HtmlDocument();
    htmlDoc.LoadHtml(@"<b> Hulk Hogan's Celebrity Championship Wrestling &nbsp;&nbsp;&nbsp;<font color=\"#228b22\">[Proj # 206010]</font></b>&nbsp;&nbsp;&nbsp; (Reality Series, &nbsp;)");
    string result = htmlDoc.DocumentNode.InnerText;

link_to image tag. how to add class to a tag

Just adding that you can pass the link_to method a block:

<%= link_to href: '' do %>
    <%= image_tag 'happyface.png', width: 136, height: 67, alt: 'a face that is unnervingly happy'%>
<% end %>

results in:

<a href="/?href=http%3A%2F%2F">
    <img alt="a face that is unnervingly happy" height="67" src="/assets/happyface.png" width="136">

This has been a life saver when the designer has given me complex links with fancy css3 roll-over effects.

how to insert value into DataGridView Cell?

This is perfect code but it cannot add a new row:

dataGridView1.Rows[rowIndex].Cells[columnIndex].Value = value;

But this code can insert a new row:

var index = this.dataGridView1.Rows.Add();
this.dataGridView1.Rows[index].Cells[1].Value = "1";
this.dataGridView1.Rows[index].Cells[2].Value = "Baqar";

SQL Server 2012 can't start because of a login failure

I don't know how good of a solution this is it, but after following some of the other answer to this question without success, i resolved setting the connection user of the service MSSQLSERVER to "Local Service".

N.B: i'm using SQL Server 2017.

How do I convert a Python program to a runnable .exe Windows program?

For this you have two choices:

  • A downgrade to python 2.6. This is generally undesirable because it is backtracking and may nullify a small portion of your scripts
  • Your second option is to use some form of exe converter. I recommend pyinstaller as it seems to have the best results.

How to set the timezone in Django?

To get a set of all valid timezone names (ids) from the tz database, you could use pytz module in Python:

>>> import pytz # $ pip install pytz
>>> pytz.all_timezones_set

What's the proper way to compare a String to an enum value?

This is my solution in java 8:

 public static Boolean isValidCity(String cityCode) {

How can I enable "URL Rewrite" Module in IIS 8.5 in Server 2012?

Thought I'd give a full answer combining some of the possible intricacies required for completeness.

  1. Check if you have 32-bit or 64-bit IIS installed:
    • Go to IIS Manager ? Application Pools, choose the appropriate app pool then Advanced Settings.
    • Check the setting "Enable 32-bit Applications". If that's true, that means the worker process is forced to run in 32-bit. If the setting is false, then the app pool is running in 64-bit mode.
    • You can also open up Task Manager and check w3wp.exe. If it's showing as w3wp*32.exe then it's 32-bit.
  2. Download the appropriate version here:
  3. Install it.
  4. Close and reopen IIS Manager to ensure the URL Rewrite module appears.

How to concatenate characters in java?

You need to tell the compiler you want to do String concatenation by starting the sequence with a string, even an empty one. Like so:

System.out.println("" + char1 + char2 + char3...);

How to download HTTP directory with all files and sub-directories as they appear on the online files/folders list?

I was able to get this to work thanks to this post utilizing VisualWGet. It worked great for me. The important part seems to be to check the -recursive flag (see image).

Also found that the -no-parent flag is important, othewise it will try to download everything.

enter image description here enter image description here

Convert Select Columns in Pandas Dataframe to Numpy Array

The best way for converting to Numpy Array is using '.to_numpy(self, dtype=None, copy=False)'. It is new in version 0.24.0.Refrence

You can also use '.array'.Refrence

Pandas .as_matrix deprecated since version 0.23.0.

jQuery UI Dialog OnBeforeUnload

For ASP.NET MVC if you want to make an exception for leaving the page via submitting a particular form:

Set a form id:

@using (Html.BeginForm("Create", "MgtJob", FormMethod.Post, new { id = "createjob" }))
  // Your code

<script type="text/javascript">

  // Without submit form
   $(window).bind('beforeunload', function () {
        if ($('input').val() !== '') {
            return "It looks like you have input you haven't submitted."

    // this will call before submit; and it will unbind beforeunload
    $(function () {
        $("#createjob").submit(function (event) {


How to append data to div using JavaScript?

IE9+ (Vista+) solution, without creating new text nodes:

var div = document.getElementById("divID");
div.textContent += data + " ";

However, this didn't quite do the trick for me since I needed a new line after each message, so my DIV turned into a styled UL with this code:

var li = document.createElement("li");
var text = document.createTextNode(data);

From :

Differences from innerHTML

innerHTML returns the HTML as its name indicates. Quite often, in order to retrieve or write text within an element, people use innerHTML. textContent should be used instead. Because the text is not parsed as HTML, it's likely to have better performance. Moreover, this avoids an XSS attack vector.

error_log per Virtual Host?

php_value error_log "/var/log/httpd/vhost_php_error_log"

It works for me, but I have to change the permission of the log file.

or Apache will write the log to the its error_log.

HTML5 Pre-resize images before uploading

I tackled this problem a few years ago and uploaded my solution to github as

robertc's answer uses the solution proposed in the Mozilla Hacks blog post, however I found this gave really poor image quality when resizing to a scale that was not 2:1 (or a multiple thereof). I started experimenting with different image resizing algorithms, although most ended up being quite slow or else were not great in quality either.

Finally I came up with a solution which I believe executes quickly and has pretty good performance too - as the Mozilla solution of copying from 1 canvas to another works quickly and without loss of image quality at a 2:1 ratio, given a target of x pixels wide and y pixels tall, I use this canvas resizing method until the image is between x and 2 x, and y and 2 y. At this point I then turn to algorithmic image resizing for the final "step" of resizing down to the target size. After trying several different algorithms I settled on bilinear interpolation taken from a blog which is not online anymore but accessible via the Internet Archive, which gives good results, here's the applicable code:

ImageUploader.prototype.scaleImage = function(img, completionCallback) {
    var canvas = document.createElement('canvas');
    canvas.width = img.width;
    canvas.height = img.height;
    canvas.getContext('2d').drawImage(img, 0, 0, canvas.width, canvas.height);

    while (canvas.width >= (2 * this.config.maxWidth)) {
        canvas = this.getHalfScaleCanvas(canvas);

    if (canvas.width > this.config.maxWidth) {
        canvas = this.scaleCanvasWithAlgorithm(canvas);

    var imageData = canvas.toDataURL('image/jpeg', this.config.quality);
    this.performUpload(imageData, completionCallback);

ImageUploader.prototype.scaleCanvasWithAlgorithm = function(canvas) {
    var scaledCanvas = document.createElement('canvas');

    var scale = this.config.maxWidth / canvas.width;

    scaledCanvas.width = canvas.width * scale;
    scaledCanvas.height = canvas.height * scale;

    var srcImgData = canvas.getContext('2d').getImageData(0, 0, canvas.width, canvas.height);
    var destImgData = scaledCanvas.getContext('2d').createImageData(scaledCanvas.width, scaledCanvas.height);

    this.applyBilinearInterpolation(srcImgData, destImgData, scale);

    scaledCanvas.getContext('2d').putImageData(destImgData, 0, 0);

    return scaledCanvas;

ImageUploader.prototype.getHalfScaleCanvas = function(canvas) {
    var halfCanvas = document.createElement('canvas');
    halfCanvas.width = canvas.width / 2;
    halfCanvas.height = canvas.height / 2;

    halfCanvas.getContext('2d').drawImage(canvas, 0, 0, halfCanvas.width, halfCanvas.height);

    return halfCanvas;

ImageUploader.prototype.applyBilinearInterpolation = function(srcCanvasData, destCanvasData, scale) {
    function inner(f00, f10, f01, f11, x, y) {
        var un_x = 1.0 - x;
        var un_y = 1.0 - y;
        return (f00 * un_x * un_y + f10 * x * un_y + f01 * un_x * y + f11 * x * y);
    var i, j;
    var iyv, iy0, iy1, ixv, ix0, ix1;
    var idxD, idxS00, idxS10, idxS01, idxS11;
    var dx, dy;
    var r, g, b, a;
    for (i = 0; i < destCanvasData.height; ++i) {
        iyv = i / scale;
        iy0 = Math.floor(iyv);
        // Math.ceil can go over bounds
        iy1 = (Math.ceil(iyv) > (srcCanvasData.height - 1) ? (srcCanvasData.height - 1) : Math.ceil(iyv));
        for (j = 0; j < destCanvasData.width; ++j) {
            ixv = j / scale;
            ix0 = Math.floor(ixv);
            // Math.ceil can go over bounds
            ix1 = (Math.ceil(ixv) > (srcCanvasData.width - 1) ? (srcCanvasData.width - 1) : Math.ceil(ixv));
            idxD = (j + destCanvasData.width * i) * 4;
            // matrix to vector indices
            idxS00 = (ix0 + srcCanvasData.width * iy0) * 4;
            idxS10 = (ix1 + srcCanvasData.width * iy0) * 4;
            idxS01 = (ix0 + srcCanvasData.width * iy1) * 4;
            idxS11 = (ix1 + srcCanvasData.width * iy1) * 4;
            // overall coordinates to unit square
            dx = ixv - ix0;
            dy = iyv - iy0;
            // I let the r, g, b, a on purpose for debugging
            r = inner([idxS00],[idxS10],[idxS01],[idxS11], dx, dy);
  [idxD] = r;

            g = inner([idxS00 + 1],[idxS10 + 1],[idxS01 + 1],[idxS11 + 1], dx, dy);
  [idxD + 1] = g;

            b = inner([idxS00 + 2],[idxS10 + 2],[idxS01 + 2],[idxS11 + 2], dx, dy);
  [idxD + 2] = b;

            a = inner([idxS00 + 3],[idxS10 + 3],[idxS01 + 3],[idxS11 + 3], dx, dy);
  [idxD + 3] = a;

This scales an image down to a width of config.maxWidth, maintaining the original aspect ratio. At the time of development this worked on iPad/iPhone Safari in addition to major desktop browsers (IE9+, Firefox, Chrome) so I expect it will still be compatible given the broader uptake of HTML5 today. Note that the canvas.toDataURL() call takes a mime type and image quality which will allow you to control the quality and output file format (potentially different to input if you wish).

The only point this doesn't cover is maintaining the orientation information, without knowledge of this metadata the image is resized and saved as-is, losing any metadata within the image for orientation meaning that images taken on a tablet device "upside down" were rendered as such, although they would have been flipped in the device's camera viewfinder. If this is a concern, this blog post has a good guide and code examples on how to accomplish this, which I'm sure could be integrated to the above code.

How to convert from []byte to int in Go Programming

var bs []byte
value, _ := strconv.ParseInt(string(bs), 10, 64)

Python develop vs install

From the documentation. The develop will not install the package but it will create a .egg-link in the deployment directory back to the project source code directory.

So it's like installing but instead of copying to the site-packages it adds a symbolic link (the .egg-link acts as a multiplatform symbolic link).

That way you can edit the source code and see the changes directly without having to reinstall every time that you make a little change. This is useful when you are the developer of that project hence the name develop. If you are just installing someone else's package you should use install

How do I add python3 kernel to jupyter (IPython)

for recent versions of jupyter/ipython: use jupyter kernelspec

Full doc:

list current kernels

$ jupyter kernelspec list
Available kernels:
  python2    .../Jupyter/kernels/python2
  python3    .../Jupyter/kernels/python3

In my case, the python3 kernel setup was broken because the py3.5 linked was no longer there, replaced by a py3.6

add/remove kernels


$ jupyter kernelspec uninstall python3

Add a new one: Using the Python you wish to add and pointing to the python which runs your jupiter:

$ /path/to/kernel/env/bin/python -m ipykernel install --prefix=/path/to/jupyter/env --name 'python-my-env'

See more examples in

List again:

$ jupyter kernelspec list
Available kernels:
  python3    /usr/local/lib/python3.6/site-packages/ipykernel/resources
  python2    /Users/stefano/Library/Jupyter/kernels/python2



Kernels available are listed under the kernels folder in Jupyter DATA DIRECTORY (see for details).

For instance on macosx that would be /Users/YOURUSERNAME/Library/Jupyter/kernels/

the kernel is simply described by a kernel.json file, eg. for /Users/me/Library/Jupyter/kernels/python3/kernel.json

 "argv": [
 "language": "python",
 "display_name": "Python 3"

Rather then manipulating that by hand, you can use the kernelspec command (as above). It was previously available through ipython now through jupyter ( -

$ jupyter kernelspec help
Manage Jupyter kernel specifications.


Subcommands are launched as `jupyter kernelspec cmd [args]`. For information on
using subcommand 'cmd', do: `jupyter kernelspec cmd -h`.

    List installed kernel specifications.
    Install a kernel specification directory.
    Alias for remove
    Remove one or more Jupyter kernelspecs by name.
    [DEPRECATED] Install the IPython kernel spec directory for this Python.

To see all available configurables, use `--help-all`

Kernels for other languages

By the way, not strictly related to this question but there's a lot of other kernels available...

Is there an ignore command for git like there is for svn?

There is no special git ignore command.

Edit a .gitignore file located in the appropriate place within the working copy. You should then add this .gitignore and commit it. Everyone who clones that repo will than have those files ignored.

Note that only file names starting with / will be relative to the directory .gitignore resides in. Everything else will match files in whatever subdirectory.

You can also edit .git/info/exclude to ignore specific files just in that one working copy. The .git/info/exclude file will not be committed, and will thus only apply locally in this one working copy.

You can also set up a global file with patterns to ignore with git config --global core.excludesfile. This will locally apply to all git working copies on the same user's account.

Run git help gitignore and read the text for the details.

How to get coordinates of an svg element?

The way to determine the coordinates depends on what element you're working with. For circles for example, the cx and cy attributes determine the center position. In addition, you may have a translation applied through the transform attribute which changes the reference point of any coordinates.

Most of the ways used in general to get screen coordinates won't work for SVGs. In addition, you may not want absolute coordinates if the line you want to draw is in the same container as the elements it connects.


In your particular code, it's quite difficult to get the position of the node because its determined by a translation of the parent element. So you need to get the transform attribute of the parent node and extract the translation from that.


Working jsfiddle here.

Named tuple and default values for optional keyword arguments

I'm not sure if there's an easy way with just the built-in namedtuple. There's a nice module called recordtype that has this functionality:

>>> from recordtype import recordtype
>>> Node = recordtype('Node', [('val', None), ('left', None), ('right', None)])
>>> Node(3)
Node(val=3, left=None, right=None)
>>> Node(3, 'L')
Node(val=3, left=L, right=None)

Not an enclosing class error Android Studio

replace code in onClick() method with this:

Intent myIntent = new Intent(this, Katra_home.class);

Download a div in a HTML page as pdf using javascript

Content inside a <div class='html-content'>....</div> can be downloaded as pdf with styles using jspdf & html2canvas.

You need to refer both js libraries,

<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>

Then call below function,

//Create PDf from HTML...
function CreatePDFfromHTML() {
    var HTML_Width = $(".html-content").width();
    var HTML_Height = $(".html-content").height();
    var top_left_margin = 15;
    var PDF_Width = HTML_Width + (top_left_margin * 2);
    var PDF_Height = (PDF_Width * 1.5) + (top_left_margin * 2);
    var canvas_image_width = HTML_Width;
    var canvas_image_height = HTML_Height;

    var totalPDFPages = Math.ceil(HTML_Height / PDF_Height) - 1;

    html2canvas($(".html-content")[0]).then(function (canvas) {
        var imgData = canvas.toDataURL("image/jpeg", 1.0);
        var pdf = new jsPDF('p', 'pt', [PDF_Width, PDF_Height]);
        pdf.addImage(imgData, 'JPG', top_left_margin, top_left_margin, canvas_image_width, canvas_image_height);
        for (var i = 1; i <= totalPDFPages; i++) { 
            pdf.addPage(PDF_Width, PDF_Height);
            pdf.addImage(imgData, 'JPG', top_left_margin, -(PDF_Height*i)+(top_left_margin*4),canvas_image_width,canvas_image_height);

Ref: pdf genration from html canvas and jspdf.

May be this will help someone.

Code not running in IE 11, works fine in Chrome

I also recently faced the prob. I solved using ^ which is similar to startwith in jquery. Say,

var str = array[a].id;
if (str.startsWith('REP')) {..........}

we can use


Here, str is id of element.

Maven Unable to locate the Javac Compiler in:

I tried all of the above suggestions, which did not work for me, but I found how to fix the error in my case.

The following steps made the project compile succesfully:

In project explorer, right-click on project, select “properties” In the tree on the right, go to Java build path. Select the tab “libraries”. Click “Add library”. Select JRE system library. Click next. Select radio button Alternate JRE. Click “installed JRE’s”. Select the JRE with the right version. Click Appy and close. In the next screen, click finish. In the properties window, click Apply and close. In the project explorer, right-click your pom.xml and select run as > maven build In the goal textbox, write “install”. Click Run.

This made the project build succesfully in my case.

What does `m_` variable prefix mean?

As stated in the other answers, m_ prefix is used to indicate that a variable is a class member. This is different from Hungarian notation because it doesn't indicate the type of the variable but its context.

I use m_ in C++ but not in some other languages where 'this' or 'self' is compulsory. I don't like to see 'this->' used with C++ because it clutters the code.

Another answer says m_dsc is "bad practice" and 'description;' is "good practice" but this is a red herring because the problem there is the abbreviation.

Another answer says typing this pops up IntelliSense but any good IDE will have a hotkey to pop up IntelliSense for the current class members.

align textbox and text/labels in html?

Using a table would be one (and easy) option.

Other options are all about setting fixed width on the and making it text-aligned to the right:

label {
   width: 200px;
   display: inline-block;
   text-align: right;

or, as was pointed out, make them all float instead of inline.

How to format a Java string with leading zero?

 StringUtils.leftPad(yourString, 8, '0');

This is from commons-lang. See javadoc

Regex empty string or email

If you are using it within rails - activerecord validation you can set allow_blank: true


validates :email, allow_blank: true, format: { with: EMAIL_REGEX }

FragmentActivity to Fragment

first of all;

a Fragment must be inside a FragmentActivity, that's the first rule,

a FragmentActivity is quite similar to a standart Activity that you already know, besides having some Fragment oriented methods

second thing about Fragments, is that there is one important method you MUST call, wich is onCreateView, where you inflate your layout, think of it as the setContentLayout

here is an example:

    @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {     mView       = inflater.inflate(R.layout.fragment_layout, container, false);       return mView; } 

and continu your work based on that mView, so to find a View by id, call mView.findViewById(..);

for the FragmentActivity part:

the xml part "must" have a FrameLayout in order to inflate a fragment in it

        <FrameLayout             android:id="@+id/content_frame"             android:layout_width="match_parent"             android:layout_height="match_parent"  >         </FrameLayout> 

as for the inflation part

getSupportFragmentManager().beginTransaction().replace(, new YOUR_FRAGMENT, "TAG").commit();

begin with these, as there is tons of other stuf you must know about fragments and fragment activities, start of by reading something about it (like life cycle) at the android developer site

Is there a "do ... until" in Python?

There's no prepackaged "do-while", but the general Python way to implement peculiar looping constructs is through generators and other iterators, e.g.:

import itertools

def dowhile(predicate):
  it = itertools.repeat(None)
  for _ in it:
    if not predicate(): break

so, for example:

i=7; j=3
for _ in dowhile(lambda: i<j):
  print i, j
  i+=1; j-=1

executes one leg, as desired, even though the predicate's already false at the start.

It's normally better to encapsulate more of the looping logic into your generator (or other iterator) -- for example, if you often have cases where one variable increases, one decreases, and you need a do/while loop comparing them, you could code:

def incandec(i, j, delta=1):
  while True:
    yield i, j
    if j <= i: break
    i+=delta; j-=delta

which you can use like:

for i, j in incandec(i=7, j=3):
  print i, j

It's up to you how much loop-related logic you want to put inside your generator (or other iterator) and how much you want to have outside of it (just like for any other use of a function, class, or other mechanism you can use to refactor code out of your main stream of execution), but, generally speaking, I like to see the generator used in a for loop that has little (ideally none) "loop control logic" (code related to updating state variables for the next loop leg and/or making tests about whether you should be looping again or not).

How can I select an element with multiple classes in jQuery?

The problem you're having, is that you are using a Group Selector, whereas you should be using a Multiples selector! To be more specific, you're using $('.a, .b') whereas you should be using $('.a.b').

For more information, see the overview of the different ways to combine selectors herebelow!

Group Selector : ","

Select all <h1> elements AND all <p> elements AND all <a> elements :

$('h1, p, a')

Multiples selector : "" (no character)

Select all <input> elements of type text, with classes code and red :


Descendant Selector : " " (space)

Select all <i> elements inside <p> elements:

$('p i')

Child Selector : ">"

Select all <ul> elements that are immediate children of a <li> element:

$('li > ul')

Adjacent Sibling Selector : "+"

Select all <a> elements that are placed immediately after <h2> elements:

$('h2 + a')

General Sibling Selector : "~"

Select all <span> elements that are siblings of <div> elements:

$('div ~ span')

Javascript: Call a function after specific time period

setTimeout(func, 5000);

-- it will call the function named func() after the time specified. here, 5000 milli seconds , i.e) after 5 seconds

Check if date is a valid one

I just found a really messed up case.

moment('Decimal128', 'YYYY-MM-DD').isValid() // true

What is a "thread" (really)?

A thread is an execution context, which is all the information a CPU needs to execute a stream of instructions.

Suppose you're reading a book, and you want to take a break right now, but you want to be able to come back and resume reading from the exact point where you stopped. One way to achieve that is by jotting down the page number, line number, and word number. So your execution context for reading a book is these 3 numbers.

If you have a roommate, and she's using the same technique, she can take the book while you're not using it, and resume reading from where she stopped. Then you can take it back, and resume it from where you were.

Threads work in the same way. A CPU is giving you the illusion that it's doing multiple computations at the same time. It does that by spending a bit of time on each computation. It can do that because it has an execution context for each computation. Just like you can share a book with your friend, many tasks can share a CPU.

On a more technical level, an execution context (therefore a thread) consists of the values of the CPU's registers.

Last: threads are different from processes. A thread is a context of execution, while a process is a bunch of resources associated with a computation. A process can have one or many threads.

Clarification: the resources associated with a process include memory pages (all the threads in a process have the same view of the memory), file descriptors (e.g., open sockets), and security credentials (e.g., the ID of the user who started the process).

How can I check if a view is visible or not in Android?

Or you could simply use


Python - A keyboard command to stop infinite loop?

Ctrl+C is what you need. If it didn't work, hit it harder. :-) Of course, you can also just close the shell window.

Edit: You didn't mention the circumstances. As a last resort, you could write a batch file that contains taskkill /im python.exe, and put it on your desktop, Start menu, etc. and run it when you need to kill a runaway script. Of course, it will kill all Python processes, so be careful.

How to convert an OrderedDict into a regular dict in python3

Here is what seems simplest and works in python 3.7

from collections import OrderedDict

d = OrderedDict([('method', 'constant'), ('data', '1.225')])
d2 = dict(d)  # Now a normal dict

Now to check this:

>>> type(d2)
<class 'dict'>
>>> isinstance(d2, OrderedDict)
>>> isinstance(d2, dict)

NOTE: This also works, and gives same result -

>>> {**d}
{'method': 'constant', 'data': '1.225'}
>>> {**d} == d2

As well as this -

>>> dict(d)
{'method': 'constant', 'data': '1.225'}
>>> dict(d) == {**d}


How to import local packages without gopath

You can use replace

go mod init



go 1.14

replace => /path/to/bar

require v1.0.0


package main
import ""

func main() {



go 1.14



import "fmt"

func MyFunc() {

Importing a local package is just like importing an external pacakge

except inside the go.mod file you replace that external package name with a local folder.

The path to the folder can be full or relative /path/to/bar or ../bar

CSS to prevent child element from inheriting parent styles

Can't you style the forms themselves? Then, style the divs accordingly.

    /* styles */

You can always overrule inherited styles by making it important:

    /* styles */ !important

When to use IList and when to use List

Microsoft guidelines as checked by FxCop discourage use of List<T> in public APIs - prefer IList<T>.

Incidentally, I now almost always declare one-dimensional arrays as IList<T>, which means I can consistently use the IList<T>.Count property rather than Array.Length. For example:

public interface IMyApi
    IList<int> GetReadOnlyValues();

public class MyApiImplementation : IMyApi
    public IList<int> GetReadOnlyValues()
        List<int> myList = new List<int>();
        ... populate list
        return myList.AsReadOnly();
public class MyMockApiImplementationForUnitTests : IMyApi
    public IList<int> GetReadOnlyValues()
        IList<int> testValues = new int[] { 1, 2, 3 };
        return testValues;

How to convert a string to lower case in Bash?

Converting case is done for alphabets only. So, this should work neatly.

I am focusing on converting alphabets between a-z from upper case to lower case. Any other characters should just be printed in stdout as it is...

Converts the all text in path/to/file/filename within a-z range to A-Z

For converting lower case to upper case

cat path/to/file/filename | tr 'a-z' 'A-Z'

For converting from upper case to lower case

cat path/to/file/filename | tr 'A-Z' 'a-z'

For example,


my name is xyz

gets converted to:


Example 2:

echo "my name is 123 karthik" | tr 'a-z' 'A-Z'
# Output:

Example 3:

echo "my name is 123 &&^&& #@$#@%%& kAR2~thik" | tr 'a-z' 'A-Z'
# Output:
# MY NAME IS 123 &&^&& #@0@%%& KAR2~THIK

Ignoring NaNs with str.contains


How to add images to on GitHub?

In case you need to upload some pictures for documentation, a nice approach is to use git-lfs. Asuming that you have installed the git-lfs follow these steps:

  1. Intialize git lfs for your each image type:

    git lfs *.png
    git lfs *.svg
    git lfs *.gif
    git lfs *.jpg
    git lfs *.jpeg
  2. Create a folder that will be used as image location eg. doc. On GNU/Linux and Unix based systems this can be done via:

    cd project_folder
    mkdir doc
    git add doc
  3. Copy paste any images into doc folder. Afterwards add them via git add command.

  4. Commit and push.

  5. The images are publicly available in the following url:^github_username^/^repo^/^branch^/^image_location in the repo^

Where: * ^github_username^ is the username in github (you can find it in the profile page) * ^repo_name^ is the repository name * ^branch^ is the repository branch where the image is uploaded * ^image_location in the repo^ is the location including the folder that the image is stored.

Also you can upload the image first then visit the location in your projects github page and navigate through until you find the image then press the download button and then copy-paste the url from the browser's address bar.

Look this from my project as reference.

Then you can use the url to include them using the markdown syntax mentioned above:

![some alternate text that describes the image](^github generated url from git lfs^)

Eg: Let us suppose we use this photo Then you can use the markdown syntax:

![In what order to compile the files](

How to count duplicate value in an array in javascript

Count the Letters provided in string

function countTheElements(){
    var str = "ssdefrcgfrdesxfdrgs";
    var arr = [];
    var count = 0;
    for(var i=0;i<str.length;i++){
    for(var i=0;i<arr.length;i++){     
        if(arr[i] == arr[i-1]){
            count = 1;        
            if(arr[i] != arr[i+1]){
                console.log(arr[i] +": "+(count));

Circle line-segment collision detection algorithm?

In this post circle line collision will be checked by checking distance between circle center and point on line segment (Ipoint) that represent intersection point between normal N (Image 2) from circle center to line segment.

( 1. Finding vectors E and D

On image 1 one circle and one line are shown, vector A point to line start point, vector B point to line end point, vector C point to circle center. Now we must find vector E (from line start point to circle center) and vector D (from line start point to line end point) this calculation is shown on image 1.

( 2. Finding vector X

At image 2 we can see that vector E is projected on Vector D by "dot product" of vector E and unit vector D, result of dot product is scalar Xp that represent the distance between line start point and point of intersection (Ipoint) of vector N and vector D. Next vector X is found by multiplying unit vector D and scalar Xp.

Now we need to find vector Z (vector to Ipoint), its easy its simple vector addition of vector A (start point on line) and vector X. Next we need to deal with special cases we must check is Ipoint on line segment, if its not we must find out is it left of it or right of it, we will use vector closest to determine which point is closest to circle.

( 3. Finding closest point

When projection Xp is negative Ipoint is left of line segment, vector closest is equal to vector of line start point, when projection Xp is greater then magnitude of vector D then Ipoint is right of line segment then closest vector is equal to vector of line end point in any other case closest vector is equal to vector Z.

Now when we have closest vector , we need to find vector from circle center to Ipoint (dist vector), its simple we just need to subtract closest vector from center vector. Next just check if vector dist magnitude is less then circle radius if it is then they collide, if its not there is no collision.

( 4. Checking for collision

For end, we can return some values for resolving collision , easiest way is to return overlap of collision (subtract radius from vector dist magnitude) and return axis of collision, its vector D. Also intersection point is vector Z if needed.

Could not load file or assembly 'Newtonsoft.Json' or one of its dependencies. Manifest definition does not match the assembly reference

I had the same issue. I created a web api project and then upgraded it from .net 4.5.1 to .net 4.6.1. Closing the IDE, stopping IIS, and deleting contents of the C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\ dir fixed the issue.


Insert/Update Many to Many Entity Framework . How do I do it?

I wanted to add my experience on that. Indeed EF, when you add an object to the context, it changes the state of all the children and related entities to Added. Although there is a small exception in the rule here: if the children/related entities are being tracked by the same context, EF does understand that these entities exist and doesn't add them. The problem happens when for example, you load the children/related entities from some other context or a web ui etc and then yes, EF doesn't know anything about these entities and goes and adds all of them. To avoid that, just get the keys of the entities and find them (e.g. context.Students.FirstOrDefault(s => s.Name == "Alice")) in the same context in which you want to do the addition.

What's the best CRLF (carriage return, line feed) handling strategy with Git?

Two alternative strategies to get consistent about line-endings in mixed environments (Microsoft + Linux + Mac):

A. Global per All Repositories Setup

1) Convert all to one format

find . -type f -not -path "./.git/*" -exec dos2unix {} \;
git commit -a -m 'dos2unix conversion'

2) Set core.autocrlf to input on Linux/UNIX or true on MS Windows (repository or global)

git config --global core.autocrlf input

3) [ Optional ] set core.safecrlf to true (to stop) or warn (to sing:) to add extra guard comparing if the reversed newline transformation would result in the same file

git config --global core.safecrlf true

B. Or per Repository Setup

1) Convert all to one format

find . -type f -not -path "./.git/*" -exec dos2unix {} \;
git commit -a -m 'dos2unix conversion'

2) add .gitattributes file to your repository

echo "* text=auto" > .gitattributes
git add .gitattributes
git commit -m 'adding .gitattributes for unified line-ending'

Don't worry about your binary files - Git should be smart enough about them.

More about safecrlf/autocrlf variables

Initialize value of 'var' in C# to null

var variables still have a type - and the compiler error message says this type must be established during the declaration.

The specific request (assigning an initial null value) can be done, but I don't recommend it. It doesn't provide an advantage here (as the type must still be specified) and it could be viewed as making the code less readable:

var x = (String)null;

Which is still "type inferred" and equivalent to:

String x = null;

The compiler will not accept var x = null because it doesn't associate the null with any type - not even Object. Using the above approach, var x = (Object)null would "work" although it is of questionable usefulness.

Generally, when I can't use var's type inference correctly then

  1. I am at a place where it's best to declare the variable explicitly; or
  2. I should rewrite the code such that a valid value (with an established type) is assigned during the declaration.

The second approach can be done by moving code into methods or functions.

How do you format a Date/Time in TypeScript?

Here is another option for Angular (using own formatting function) - this one is for format:

YYYY-mm-dd hh:nn:ss

-you can adjust to your formats, just re-order the lines and change separators

dateAsYYYYMMDDHHNNSS(date): string {
  return date.getFullYear()
            + '-' + this.leftpad(date.getMonth() + 1, 2)
            + '-' + this.leftpad(date.getDate(), 2)
            + ' ' + this.leftpad(date.getHours(), 2)
            + ':' + this.leftpad(date.getMinutes(), 2)
            + ':' + this.leftpad(date.getSeconds(), 2);

leftpad(val, resultLength = 2, leftpadChar = '0'): string {
  return (String(leftpadChar).repeat(resultLength)
        + String(val)).slice(String(val).length);

For current time stamp use like this:

const curTime = this.dateAsYYYYMMDDHHNNSS(new Date());

Will output e.g: 2018-12-31 23:00:01

How do I convert a byte array to Base64 in Java?


byte[] data = Base64.encode(base64str);

Encoding converts to Base64

You would need to reference commons codec from your project in order for that code to work.

For java8:

import java.util.Base64

How do I mock a class without an interface?

Most mocking frameworks (Moq and RhinoMocks included) generate proxy classes as a substitute for your mocked class, and override the virtual methods with behavior that you define. Because of this, you can only mock interfaces, or virtual methods on concrete or abstract classes. Additionally, if you're mocking a concrete class, you almost always need to provide a parameterless constructor so that the mocking framework knows how to instantiate the class.

Why the aversion to creating interfaces in your code?

All inclusive Charset to avoid "java.nio.charset.MalformedInputException: Input length = 1"?

try this.. i had the same issue, below implementation worked for me

Reader reader = Files.newBufferedReader(Paths.get(<yourfilewithpath>), StandardCharsets.ISO_8859_1);

then use Reader where ever you want.


CsvToBean<anyPojo> csvToBean = null;
    try {
        Reader reader = Files.newBufferedReader(Paths.get(csvFilePath), 
        csvToBean = new CsvToBeanBuilder(reader)

    } catch (IOException e) {

Aborting a stash pop in Git

If DavidG is correct that it didn't pop the stash because of the merge conflict, then you merely need to clean up your working directory. Quickly git commit everything you care about. (You can reset or squash the commit later if you're not done.) Then with everything you care about safe, git reset everything else that git stash pop dumped into your working directory.

Indentation shortcuts in Visual Studio

Tab to tab right, shift-tab to tab left.

How to install psycopg2 with "pip" on Python?

On OSX with macports:

sudo port install postgresql96
export PATH=/opt/local/lib/postgresql96/bin:$PATH

White space showing up on right side of page when background image should extend full length of page

I had the same issue, so tried a few things. One of which seemed to work for me - removing the width and adding a float to the body tag.

May not work for all instances, but in the scenario I recently had, hiding overflow on content elements was a no go...

jQuery Validate Required Select

An easier solution has been outlined here: Validate select box

Make the value be empty and add the required attribute

<select id="select" class="required">
<option value="">Choose an option</option> 
<option value="option1">Option1</option>
<option value="option2">Option2</option>
<option value="option3">Option3</option>

TypeError: 'tuple' object does not support item assignment when swapping values

Evaluating "1,2,3" results in (1, 2, 3), a tuple. As you've discovered, tuples are immutable. Convert to a list before processing.

receiving error: 'Error: SSL Error: SELF_SIGNED_CERT_IN_CHAIN' while using npm

For now I just switched registry URL from https to http. Like this:

npm config set registry=""

Is there a “not in” operator in JavaScript for checking object properties?

As already said by Jordão, just negate it:

if (!(id in tutorTimes)) { ... }

Note: The above test if tutorTimes has a property with the name specified in id, anywhere in the prototype chain. For example "valueOf" in tutorTimes returns true because it is defined in Object.prototype.

If you want to test if a property doesn't exist in the current object, use hasOwnProperty:

if (!tutorTimes.hasOwnProperty(id)) { ... }

Or if you might have a key that is hasOwnPropery you can use this:

if (!,id)) { ... }

Lollipop : draw behind statusBar with its color set to transparent

The solution from Cody Toombs almost did the trick for me. I'm not sure if this is Xamarin related or not, but I now have an acceptable solution:


This is my setup:

I have an Android project where I have referenced the Android.Support v4 and v7 packages. I have two styles defined:


<?xml version="1.0" encoding="UTF-8" ?>
    <style name="MyStyle" parent="@style/Theme.AppCompat.Light.NoActionBar">
        <item name="android:windowTranslucentStatus">true</item>


<?xml version="1.0" encoding="UTF-8" ?>
    <style name="MyStyle" parent="@style/Theme.AppCompat.Light.NoActionBar">
        <item name="android:statusBarColor">@android:color/transparent</item>

AndroidManifest targets "MyStyle":


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="" android:versionCode="1" android:versionName="1.0" package="com.agn.test.test">
    <uses-sdk android:minSdkVersion="10" />
    <application android:allowBackup="true" android:icon="@mipmap/icon" android:label="@string/app_name" android:theme="@style/MyStyle">

And finally the code in the Main Activity:

[Activity (Label = "Test", MainLauncher = true, Icon = "@mipmap/icon")]
public class MainActivity : Activity
    protected override void OnCreate (Bundle savedInstanceState)
        base.OnCreate (savedInstanceState);

        SetContentView (Resource.Layout.Main);
        //Resource.Layout.Main is just a regular layout, no additional flags. Make sure there is something in there like an imageView, so that you can see the overlay.

        var uiOptions = (int)Window.DecorView.SystemUiVisibility;
        uiOptions ^= (int)SystemUiFlags.LayoutStable;
        uiOptions ^= (int)SystemUiFlags.LayoutFullscreen;
        Window.DecorView.SystemUiVisibility = (StatusBarVisibility)uiOptions;

        Window.AddFlags (WindowManagerFlags.DrawsSystemBarBackgrounds);

Notice that I set DrawsSystemBarBackgrounds flag, this makes all the difference

Window.AddFlags (WindowManagerFlags.DrawsSystemBarBackgrounds); 

I spent a lot of time getting it right, too much time in fact. Hopefully this answer helps anyone trying to achieve the same thing.

Checking that a List is not empty in Hamcrest

Well there's always

assertThat(list.isEmpty(), is(false));

... but I'm guessing that's not quite what you meant :)


assertThat((Collection)list, is(not(empty())));

empty() is a static in the Matchers class. Note the need to cast the list to Collection, thanks to Hamcrest 1.2's wonky generics.

The following imports can be used with hamcrest 1.3

import static org.hamcrest.Matchers.empty;
import static;
import static org.hamcrest.core.IsNot.*;

Find the most frequent number in a NumPy array

If you're willing to use SciPy:

>>> from scipy.stats import mode
>>> mode([1,2,3,1,2,1,1,1,3,2,2,1])
(array([ 1.]), array([ 6.]))
>>> most_frequent = mode([1,2,3,1,2,1,1,1,3,2,2,1])[0][0]
>>> most_frequent

How do I iterate through lines in an external file with shell?

cat names.txt|while read line; do
    echo "$line";

Undefined reference to pow( ) in C, despite including math.h

You need to link with the math library:

gcc -o sphere sphere.c -lm

The error you are seeing: error: ld returned 1 exit status is from the linker ld (part of gcc that combines the object files) because it is unable to find where the function pow is defined.

Including math.h brings in the declaration of the various functions and not their definition. The def is present in the math library libm.a. You need to link your program with this library so that the calls to functions like pow() are resolved.

How to make ng-repeat filter out duplicate results

I decided to extend @thethakuri's answer to allow any depth for the unique member. Here's the code. This is for those who don't want to include the entire AngularUI module just for this functionality. If you're already using AngularUI, ignore this answer:

app.filter('unique', function() {
    return function(collection, primaryKey) { //no need for secondary key
      var output = [], 
          keys = [];
          var splitKeys = primaryKey.split('.'); //split by period

      angular.forEach(collection, function(item) {
            var key = {};
            angular.copy(item, key);
            for(var i=0; i<splitKeys.length; i++){
                key = key[splitKeys[i]];    //the beauty of loosely typed js :)

            if(keys.indexOf(key) === -1) {

      return output;


<div ng-repeat="item in items | unique : 'subitem.subitem.subitem.value'"></div>

Fatal error: Cannot use object of type stdClass as array in

Sorry.Though it is a bit late but hope it would help others as well . Always use the stdClass object.e.g

 $getvidids = $ci->db->query("SELECT * FROM videogroupids WHERE videogroupid='$videogroup'   AND used='0' LIMIT 10");

foreach($getvidids->result() as $key=>$myids)

  $vidid[$key] = $myids->videoid;  // better methodology to retrieve and store multiple records in arrays in loop

SQL Server using wildcard within IN

This might me the most simple solution use like any

select *
from jobdetails
where job_no like any ('0711%', '0712%')

In Teradata this works fine.

Pandas conditional creation of a series/dataframe column

List comprehension is another way to create another column conditionally. If you are working with object dtypes in columns, like in your example, list comprehensions typically outperform most other methods.

Example list comprehension:

df['color'] = ['red' if x == 'Z' else 'green' for x in df['Set']]

%timeit tests:

import pandas as pd
import numpy as np

df = pd.DataFrame({'Type':list('ABBC'), 'Set':list('ZZXY')})
%timeit df['color'] = ['red' if x == 'Z' else 'green' for x in df['Set']]
%timeit df['color'] = np.where(df['Set']=='Z', 'green', 'red')
%timeit df['color'] = lambda x: 'red' if x == 'Z' else 'green')

1000 loops, best of 3: 239 µs per loop
1000 loops, best of 3: 523 µs per loop
1000 loops, best of 3: 263 µs per loop

Case insensitive searching in Oracle

maybe you can try using

SELECT user_name
FROM user_master
WHERE upper(user_name) LIKE '%ME%'

How to increase MySQL connections(max_connections)?

If you need to increase MySQL Connections without MySQL restart do like below

mysql> show variables like 'max_connections';
| Variable_name   | Value |
| max_connections | 100   |
1 row in set (0.00 sec)

mysql> SET GLOBAL max_connections = 150;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'max_connections';
| Variable_name   | Value |
| max_connections | 150   |
1 row in set (0.00 sec)

These settings will change at MySQL Restart.

For permanent changes add below line in my.cnf and restart MySQL

max_connections = 150

How do I programmatically "restart" an Android app?

Jake Wharton recently published his ProcessPhoenix library, which does this in a reliable way. You basically only have to call:


The library will automatically finish the calling activity, kill the application process and restart the default application activity afterwards.

filters on ng-model in an input

I had a similar problem and used


in my handler I call a method of the objectInScope to modify itself correctly (coarse input). In the controller I have initiated somewhere that

$scope.objectInScope = myObject; 

I know this doesn't use any fancy filters or watchers... but it's simple and works great. The only down-side to this is that the objectInScope is sent in the call to the handler...

In UML class diagrams, what are Boundary Classes, Control Classes, and Entity Classes?

These are class stereotypes used in analysis.

  • boundary classes are ones at the boundary of the system - the classes that you or other systems interact with

  • entity classes classes are your typical business entities like "person" and "bank account"

  • control classes implement some business logic or other

How to compile C++ under Ubuntu Linux?

even you can compile your c++ code by gcc Sounds funny ?? Yes it is. try it

$  gcc avishay.cpp -lstdc++


How to persist a property of type List<String> in JPA?

I had the same problem so I invested the possible solution given but at the end I decided to implement my ';' separated list of String.

so I have

// a ; separated list of arguments
String arguments;

public List<String> getArguments() {
    return Arrays.asList(arguments.split(";"));

This way the list is easily readable/editable in the database table;

How to check for file existence

# file? will only return true for files


# Will also return true for directories - watch out!

create unique id with javascript

put in your namespace an instance similar to the following one

var myns = {/*.....*/};
myns.uid = new function () {
    var u = 0;
    this.toString = function () {
        return 'myID_' + u++;
console.dir([myns.uid, myns.uid, myns.uid]);

How do you get current active/default Environment profile programmatically in Spring?

Here is a more complete example.

Autowire Environment

First you will want to autowire the environment bean.

private Environment environment;

Check if Profiles exist in Active Profiles

Then you can use getActiveProfiles() to find out if the profile exists in the list of active profiles. Here is an example that takes the String[] from getActiveProfiles(), gets a stream from that array, then uses matchers to check for multiple profiles(Case-Insensitive) which returns a boolean if they exist.

//Check if Active profiles contains "local" or "test"
   env -> (env.equalsIgnoreCase("test") 
   || env.equalsIgnoreCase("local")) )) 
//Check if Active profiles contains "prod"
else if(
   env -> (env.equalsIgnoreCase("prod")) )) 

You can also achieve similar functionality using the annotation @Profile("local") Profiles allow for selective configuration based on a passed-in or environment parameter. Here is more information on this technique: Spring Profiles

How do I make a redirect in PHP?

Output JavaScript from PHP using echo, which will do the job.

echo '<script type="text/javascript">
           window.location = ""

You can't really do it in PHP unless you buffer the page output and then later check for redirect condition. That might be too much of a hassle. Remember that headers are the first thing that is sent from the page. Most of the redirect is usually required later in the page. For that you have to buffer all the output of the page and check for redirect condition later. At that point you can either redirect page user header() or simply echo the buffered output.

For more about buffering (advantages)

What is output buffering?

Illegal pattern character 'T' when parsing a date string to java.util.Date

There are two answers above up-to-now and they are both long (and tl;dr too short IMHO), so I write summary from my experience starting to use new java.time library (applicable as noted in other answers to Java version 8+). ISO 8601 sets standard way to write dates: YYYY-MM-DD so the format of date-time is only as below (could be 0, 3, 6 or 9 digits for milliseconds) and no formatting string necessary:

import java.time.Instant;
public static void main(String[] args) {
    String date="2010-10-02T12:23:23Z";
    try {
        Instant myDate = Instant.parse(date);
    } catch (ParseException e) {
        // TODO Auto-generated catch block

I did not need it, but as getting year is in code from the question, then:
it is trickier, cannot be done from Instant directly, can be done via Calendar in way of questions Get integer value of the current year in Java and Converting java.time to Calendar but IMHO as format is fixed substring is more simple to use:


DB2 Date format

This isn't straightforward, but


returns the current date in yyyy-mm-dd format. You would have to substring and concatenate the result to get yyyymmdd.


Python dictionary : TypeError: unhashable type: 'list'

You can also use defaultdict to address this situation. It goes something like this:

from collections import defaultdict

#initialises the dictionary with values as list
aTargetDictionary = defaultdict(list)

for aKey in aSourceDictionary:

How to insert multiple rows from a single query using eloquent/fluent

using Eloquent

$data = array(
    array('user_id'=>'Coder 1', 'subject_id'=> 4096),
    array('user_id'=>'Coder 2', 'subject_id'=> 2048),


Convert UTC/GMT time to local time

I'd just like to add a general note of caution.

If all you are doing is getting the current time from the computer's internal clock to put a date/time on the display or a report, then all is well. But if you are saving the date/time information for later reference or are computing date/times, beware!

Let's say you determine that a cruise ship arrived in Honolulu on 20 Dec 2007 at 15:00 UTC. And you want to know what local time that was.
1. There are probably at least three 'locals' involved. Local may mean Honolulu, or it may mean where your computer is located, or it may mean the location where your customer is located.
2. If you use the built-in functions to do the conversion, it will probably be wrong. This is because daylight savings time is (probably) currently in effect on your computer, but was NOT in effect in December. But Windows does not know this... all it has is one flag to determine if daylight savings time is currently in effect. And if it is currently in effect, then it will happily add an hour even to a date in December.
3. Daylight savings time is implemented differently (or not at all) in various political subdivisions. Don't think that just because your country changes on a specific date, that other countries will too.