Programs & Examples On #Parallel builds

Parallel building harnesses the advantages of multi-core processors to speed up compilation and building, by compiling several files in parallel.

How to remove all white space from the beginning or end of a string?

String.Trim() returns a string which equals the input string with all white-spaces trimmed from start and end:

"   A String   ".Trim() -> "A String"

String.TrimStart() returns a string with white-spaces trimmed from the start:

"   A String   ".TrimStart() -> "A String   "

String.TrimEnd() returns a string with white-spaces trimmed from the end:

"   A String   ".TrimEnd() -> "   A String"

None of the methods modify the original string object.

(In some implementations at least, if there are no white-spaces to be trimmed, you get back the same string object you started with:

csharp> string a = "a"; csharp> string trimmed = a.Trim(); csharp> (object) a == (object) trimmed; returns true

I don't know whether this is guaranteed by the language.)

PHP: How to remove specific element from an array?

A better approach would maybe be to keep your values as keys in an associative array, and then call array_keys() on it when you want to actual array. That way you don't need to use array_search to find your element.

Writing binary number system in C code

Standard C doesn't define binary constants. There's a GNU (I believe) extension though (among popular compilers, clang adapts it as well): the 0b prefix:

int foo = 0b1010;

If you want to stick with standard C, then there's an option: you can combine a macro and a function to create an almost readable "binary constant" feature:

#define B(x) S_to_binary_(#x)

static inline unsigned long long S_to_binary_(const char *s)
        unsigned long long i = 0;
        while (*s) {
                i <<= 1;
                i += *s++ - '0';
        return i;

And then you can use it like this:

int foo = B(1010);

If you turn on heavy compiler optimizations, the compiler will most likely eliminate the function call completely (constant folding) or will at least inline it, so this won't even be a performance issue.


The following code:

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>

#define B(x) S_to_binary_(#x)

static inline unsigned long long S_to_binary_(const char *s)
    unsigned long long i = 0;
    while (*s) {
        i <<= 1;
        i += *s++ - '0';
    return i;

int main()
    int foo = B(001100101);

    printf("%d\n", foo);

    return 0;

has been compiled using clang -o baz.S baz.c -Wall -O3 -S, and it produced the following assembly:

    .section    __TEXT,__text,regular,pure_instructions
    .globl  _main
    .align  4, 0x90
_main:                                  ## @main
## BB#0:
    pushq   %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register %rbp
    leaq    L_.str1(%rip), %rdi
    movl    $101, %esi               ## <= This line!
    xorb    %al, %al
    callq   _printf
    xorl    %eax, %eax
    popq    %rbp

    .section    __TEXT,__cstring,cstring_literals
L_.str1:                                ## @.str1
    .asciz   "%d\n"


So clang completely eliminated the call to the function, and replaced its return value with 101. Neat, huh?

How to do if-else in Thymeleaf?

Thymeleaf has an equivalent to <c:choose> and <c:when>: the th:switch and th:case attributes introduced in Thymeleaf 2.0.

They work as you'd expect, using * for the default case:

<div th:switch="${user.role}"> 
  <p th:case="'admin'">User is an administrator</p>
  <p th:case="#{roles.manager}">User is a manager</p>
  <p th:case="*">User is some other thing</p> 

See this for a quick explanation of syntax (or the Thymeleaf tutorials).

Disclaimer: As required by StackOverflow rules, I'm the author of Thymeleaf.

Resolving a Git conflict with binary files

To resolve by keeping the version in your current branch (ignore the version from the branch you are merging in), just add and commit the file:

git commit -a

To resolve by overwriting the version in your current branch with the version from the branch you are merging in, you need to retrieve that version into your working directory first, and then add/commit it:

git checkout otherbranch theconflictedfile
git commit -a

Explained in more detail

Could not load file or assembly 'System.Web.WebPages.Razor, Version=

Update using NuGet Package Manager Console in your Visual Studio

Update-Package -reinstall Microsoft.AspNet.Mvc

ASP.NET Web Site or ASP.NET Web Application?

Unless you have a specific need for a dynamically compiled project, don't use a web site project.

Why? Because web site project will drive you up the wall when trying to change or understand your project. The static typing find features (e.g. find usages, refactor) in Visual Studio will all take forever on any reasonably sized project. For further information, see the Stack Overflow question Slow “Find All References” in Visual Studio.

I really can't see why they dropped web applications in Visual Studio 2005 for the pain-inducing, sanity-draining, productivity carbuncle web site project type.

Is this how you define a function in jQuery?

That is how you define an anonymous function that gets called when the document is ready.

Forcing anti-aliasing using css: Is this a myth?

Not a pure CSS but natively supported method without any font replacement hacks: Simply convert your font to SVG and place it higher(before WOFF or TTF) in @font-face order. Voila! Fonts are smooth now, because they're no longer treated as a font but an SVG shape which will be nicely smoothened.

Note: I noticed that SVG can weight more than WOFF or TTF.

Concatenate multiple files but include filename as section headers

find . -type f -print0 | xargs -0 -I % sh -c 'echo %; cat %'

This will print the full filename (including path), then the contents of the file. It is also very flexible, as you can use -name "expr" for the find command, and run as many commands as you like on the files.

Adding Lombok plugin to IntelliJ project

There is a lot of really helpful info posted here, but there is one thing that all the posts seem to have wrong. I could not find any 'Settings' option under 'Files', and I hunted around for 10 minutes looking through all the menus until I found the settings under 'IntelliJ IDE' -> 'Preferences'.

I don't know if I am using a differing OS version or IntelliJ version from other posters, or if it is because I am a stupid Windows user that doesn't know that settings == preferences on a mac (Did I miss the memo?), but I hope this helps you if you aren't finding the paths that other posts are suggesting.

finding multiples of a number in Python

If you're trying to find the first count multiples of m, something like this would work:

def multiples(m, count):
    for i in range(count):

Alternatively, you could do this with range:

def multiples(m, count):
    for i in range(0,count*m,m):

Note that both of these start the multiples at 0 - if you wanted to instead start at m, you'd need to offset it by that much:


Failed to auto-configure a DataSource: 'spring.datasource.url' is not specified

your dependency based on data is trying to find their respective entities which one has not been created, comments the dependencies based on data and runs the app again.

<!-- <dependency> -->
        <!-- <groupId>org.springframework.boot</groupId> -->
        <!-- <artifactId>spring-boot-starter-data-jpa</artifactId> -->
        <!-- </dependency> -->

How to change legend title in ggplot

Since in your code you used ggplot(data, fill= cond) to create the histogram you need to add the legend title by also using "fill" in the label section i.e. +labs(fill="Title name"). If you were using a different type of plot where the code was ggplot(data, colour= cond), then you could use +labs(colour= "Title Name"). In summary, the lab argument has to match the aes argument.

I have used + guides(fill=guide_legend("my awesome title")) to change the legend title on geom_bar plots but it did not seem to work for geom_point.

Can curl make a connection to any TCP ports, not just HTTP/HTTPS?

Since you're using PHP, you will probably need to use the CURLOPT_PORT option, like so:

curl_setopt($ch, CURLOPT_PORT, 11740);

Bear in mind, you may face problems with SELinux:

Unable to make php curl request with port number

Check if a variable is of function type

The solution as some previous answers has shown is to use typeof. the following is a code snippet In NodeJs,

    function startx() {
      console.log("startx function called.");

 var fct= {};
 fct["/startx"] = startx;

if (typeof fct[/startx] === 'function') { //check if function then execute it

In Laravel, the best way to pass different types of flash messages in the session

You can make a multiple messages and with different types. Follow these steps below:

  1. Create a file: "app/Components/FlashMessages.php"
namespace App\Components;

trait FlashMessages
  protected static function message($level = 'info', $message = null)
      if (session()->has('messages')) {
          $messages = session()->pull('messages');

      $messages[] = $message = ['level' => $level, 'message' => $message];

      session()->flash('messages', $messages);

      return $message;

  protected static function messages()
      return self::hasMessages() ? session()->pull('messages') : [];

  protected static function hasMessages()
      return session()->has('messages');

  protected static function success($message)
      return self::message('success', $message);

  protected static function info($message)
      return self::message('info', $message);

  protected static function warning($message)
      return self::message('warning', $message);

  protected static function danger($message)
      return self::message('danger', $message);
  1. On your base controller "app/Http/Controllers/Controller.php".
namespace App\Http\Controllers;

use Illuminate\Foundation\Bus\DispatchesJobs;
use Illuminate\Routing\Controller as BaseController;
use Illuminate\Foundation\Validation\ValidatesRequests;
use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
use Illuminate\Foundation\Auth\Access\AuthorizesResources;

use App\Components\FlashMessages;

class Controller extends BaseController
    use AuthorizesRequests, AuthorizesResources, DispatchesJobs, ValidatesRequests;

    use FlashMessages;

This will make the FlashMessages trait available to all controllers that extending this class.

  1. Create a blade template for our messages: "views/partials/messages.blade.php"
@if (count($messages))
<div class="row">
  <div class="col-md-12">
  @foreach ($messages as $message)
      <div class="alert alert-{{ $message['level'] }}">{!! $message['message'] !!}</div>
  1. On "boot()" method of "app/Providers/AppServiceProvider.php":
namespace App\Providers;

use Illuminate\Support\ServiceProvider; 

use App\Components\FlashMessages;

class AppServiceProvider extends ServiceProvider
  use FlashMessages;

    public function boot()
        view()->composer('partials.messages', function ($view) {

          $messages = self::messages();

          return $view->with('messages', $messages);


This will make the $messages variable available to "views/partials/message.blade.php" template whenever it is called.

  1. On your template, include our messages template - "views/partials/messages.blade.php"
<div class="row">
  <p>Page title goes here</p>

@include ('partials.messages')

<div class="row">
  <div class="col-md-12">
      Page content goes here

You only need to include the messages template wherever you want to display the messages on your page.

  1. On your controller, you can simply do this to push flash messages:
use App\Components\FlashMessages;

class ProductsController {

  use FlashMessages;

  public function store(Request $request)
      self::message('info', 'Just a plain message.');
      self::message('success', 'Item has been added.');
      self::message('warning', 'Service is currently under maintenance.');
      self::message('danger', 'An unknown error occured.');


      self::info('Just a plain message.');
      self::success('Item has been added.');
      self::warning('Service is currently under maintenance.');
      self::danger('An unknown error occured.');


Hope it'l help you.

What is 'Context' on Android?

Instances of the the class android.content.Context provide the connection to the Android system which executes the application. For example, you can check the size of the current device display via the Context.

It also gives access to the resources of the project. It is the interface to global information about the application environment.

The Context class also provides access to Android services, e.g., the alarm manager to trigger time based events.

Activities and services extend the Context class. Therefore they can be directly used to access the Context.

Set custom attribute using JavaScript

Please use dataset

var article = document.querySelector('#electriccars'),
    data = article.dataset;

// data.columns -> "3"
// data.indexnumber -> "12314"
// data.parent -> "cars"

so in your case for setting data:

getElementById('item1').dataset.icon = "base2.gif";

White space at top of page

If nothing of the above helps, check if there is margin-top set on some of the (some levels below) nested DOM element(s).

It will be not recognizable when you inspect body element itself in the debugger. It will only be visible when you unfold several elements nested down in body element in Chrome Dev Tools elements debugger and check if there is one of them with margin-top set.

The below is the upper part of a site screen shot and the corresponding Chrome Dev Tools view when you inspect body tag.

No sign of top margin here and you have resetted all the browser-scpecific CSS properties as per answers above but that unwanted white space is still here.

The unwanted white space above the body element The corresponding debugger view

The following is a view when you inspect the right nested element. It is clearly seen the orange'ish top-margin is set on it. This is the one that causes the white space on top of body element.

Clearly visible top-margin enter image description here

On that found element replace margin-top with padding-top if you need space above it and yet not to leak it above the body tag.

Hope that helps :)

Datatable vs Dataset

It really depends on the sort of data you're bringing back. Since a DataSet is (in effect) just a collection of DataTable objects, you can return multiple distinct sets of data into a single, and therefore more manageable, object.

Performance-wise, you're more likely to get inefficiency from unoptimized queries than from the "wrong" choice of .NET construct. At least, that's been my experience.

Using NSPredicate to filter an NSArray based on NSDictionary keys

It should work - as long as the data variable is actually an array containing a dictionary with the key SPORT

NSArray *data = [NSArray arrayWithObject:[NSMutableDictionary dictionaryWithObject:@"foo" forKey:@"BAR"]];    
NSArray *filtered = [data filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(BAR == %@)", @"foo"]];

Filtered in this case contains the dictionary.

(the %@ does not have to be quoted, this is done when NSPredicate creates the object.)

Hexadecimal value 0x00 is a invalid character

As kind of a late answer:

I've had this problem with SSRS ReportService2005.asmx when uploading a report.

    Public Shared Sub CreateReport(ByVal strFileNameAndPath As String, ByVal strReportName As String, ByVal strReportingPath As String, Optional ByVal bOverwrite As Boolean = True)
        Dim rs As SSRS_2005_Administration_WithFOA = New SSRS_2005_Administration_WithFOA
        rs.Credentials = ReportingServiceInterface.GetMyCredentials(strCredentialsURL)
        rs.Timeout = ReportingServiceInterface.iTimeout
        rs.Url = ReportingServiceInterface.strReportingServiceURL
        rs.UnsafeAuthenticatedConnectionSharing = True

        Dim btBuffer As Byte() = Nothing

        Dim rsWarnings As Warning() = Nothing
            Dim fstrStream As System.IO.FileStream = System.IO.File.OpenRead(strFileNameAndPath)
            btBuffer = New Byte(fstrStream.Length - 1) {}
            fstrStream.Read(btBuffer, 0, CInt(fstrStream.Length))
        Catch ex As System.IO.IOException
            Throw New Exception(ex.Message)
        End Try

            rsWarnings = rs.CreateReport(strReportName, strReportingPath, bOverwrite, btBuffer, Nothing)

            If Not (rsWarnings Is Nothing) Then
                Dim warning As Warning
                For Each warning In rsWarnings
                Next warning
                Log("Report: {0} created successfully with no warnings", strReportName)
            End If

        Catch ex As System.Web.Services.Protocols.SoapException
        Catch ex As Exception
            Log("Error at creating report. Invalid server name/timeout?" + vbCrLf + vbCrLf + "Error Description: " + vbCrLf + ex.Message)
        End Try
    End Sub ' End Function CreateThisReport

The problem occurs when you allocate a byte array that is at least 1 byte larger than the RDL (XML) file.

Specifically, I used a C# to converter, that converted

  btBuffer = new byte[fstrStream.Length];


  btBuffer = New Byte(fstrStream.Length) {}

But because in C# the number denotes the NUMBER OF ELEMENTS in the array, and in VB.NET, that number denotes the UPPER BOUND of the array, I had an excess byte, causing this error.

So the problem's solution is simply:

  btBuffer = New Byte(fstrStream.Length - 1) {}

Easiest way to convert a Blob into a byte array

the mySql blob class has the following function :


use it like this:

//(assuming you have a ResultSet named RS)
Blob blob = rs.getBlob("SomeDatabaseField");

int blobLength = (int) blob.length();  
byte[] blobAsBytes = blob.getBytes(1, blobLength);

//release the blob and free up memory. (since JDBC 4.0);

Parsing Json rest api response in C#

Create a C# class that maps to your Json and use Newsoft JsonConvert to Deserialise it.

For example:

public Class MyResponse
    public Meta Meta { get; set; }
    public Response Response { get; set; }

JavaScript: Collision detection

bcm's answer, which has 0 votes at this time, is actually a great, under-appreciated answer. It uses good old Pythagoras to detect when objects are closer than their combined bounding circles. Simple collision detection often uses rectangular collision detection, which is fine if your sprites tend to be, well, rectangular. If they are circular (or otherwise less than rectangular), such as a ball, an asteroid, or any other shape where the extreme corners are usually transparent, you may find this efficient routine to be the most accurate.

But for clarity, here is a more fully realized version of the code:

function doCollide(x1, y1, w1, x2, y2, w2) {
    var xd = x1 - x2;
    var yd = y1 - y2;
    var wt = w2 + w1;
    return (xd * xd + yd * yd <= wt * wt);

Where the parameters to pass in are the x,y and width values of two different sprite objects.

How can I get the current page name in WordPress?

You can get the current page, post, or custom post type with the global variable $post:

echo $post->post_title

Note: In a function or class you'll need to specify global $post; prior to trying to use $post.

If you have loops on your page, make sure you end each loop with wp_reset_postdata(); to set $post back to the default item being displayed (the page).

Note, the 'post_title' variable is also available for any custom loop / query... including menu items and media attachments... everything in WordPress is a 'post'.

Cannot uninstall angular-cli

For those using Windows, I had this issue because :

  • after running npm uninstall -g @ angular/cli, the folder AppData\Roaming\npm were still containing a ng file
  • this file prevented a complete uninstall of the CLI

I tried then to remove the ng file manually, but for some reasons it was not possible (I did not have the right), even as admin.

The only hack I found was using a 'linux based' command (I used Git bash) as admin and removing this file from command line: cd AppData/Roaming/npm rm ng.cmd

For information: this was with the version 6 of the CLI. There is not problem anymore to remove manually this specific file after the update.

Can we have multiple <tbody> in same <table>?

According to this example it can be done: w3-struct-tables.

get all characters to right of last dash

I created a string extension for this, hope it helps.

public static string GetStringAfterChar(this string value, char substring)
        if (!string.IsNullOrWhiteSpace(value))
            var index = value.LastIndexOf(substring);
            return index > 0 ? value.Substring(index + 1) : value;

        return string.Empty;

Creating a dynamic choice field

you can filter the waypoints by passing the user to the form init

class waypointForm(forms.Form):
    def __init__(self, user, *args, **kwargs):
        super(waypointForm, self).__init__(*args, **kwargs)
        self.fields['waypoints'] = forms.ChoiceField(
            choices=[(, str(o)) for o in Waypoint.objects.filter(user=user)]

from your view while initiating the form pass the user

form = waypointForm(user)

in case of model form

class waypointForm(forms.ModelForm):
    def __init__(self, user, *args, **kwargs):
        super(waypointForm, self).__init__(*args, **kwargs)
        self.fields['waypoints'] = forms.ModelChoiceField(

    class Meta:
        model = Waypoint

Get value of multiselect box using jQuery or pure JS

You could do like this too.

<form action="ResultsDulith.php" id="intermediate" name="inputMachine[]" multiple="multiple" method="post">
    <select id="selectDuration" name="selectDuration[]" multiple="multiple"> 
        <option value="1 WEEK" >Last 1 Week</option>
        <option value="2 WEEK" >Last 2 Week </option>
        <option value="3 WEEK" >Last 3 Week</option>
         <option value="4 WEEK" >Last 4 Week</option>
          <option value="5 WEEK" >Last 5 Week</option>
           <option value="6 WEEK" >Last 6 Week</option>
     <input type="submit"/> 

Then take the multiple selection from following PHP code below. It print the selected multiple values accordingly.



Understanding checked vs unchecked exceptions in Java

I just want to add some reasoning for not using checked exceptions at all. This is not a full answer, but I feel it does answer part of your question, and complements many other answers.

Whenever checked exceptions are involved, there's a throws CheckedException somewhere in a method signature (CheckedException could be any checked exception). A signature does NOT throw an Exception, throwing Exceptions is an aspect of implementation. Interfaces, method signatures, parent classes, all these things should NOT depend on their implementations. The usage of checked Exceptions here (actually the fact that you have to declare the throws in the method signature) is binding your higher-level interfaces with your implementations of these interfaces.

Let me show you an example.

Let's have a nice and clean interface like this

public interface IFoo {
    public void foo();

Now we can write many implementations of method foo(), like these

public class Foo implements IFoo {
    public void foo() {
        System.out.println("I don't throw and exception");

Class Foo is perfectly fine. Now let's make a first attempt at class Bar

public class Bar implements IFoo {
    public void foo() {
        //I'm using InterruptedExcepton because you probably heard about it somewhere. It's a checked exception. Any checked exception will work the same.
        throw new InterruptedException();

This class Bar won't compile. As InterruptedException is a checked exception, you must either capture it (with a try-catch inside method foo()) or declare that you're throwing it (adding throws InterruptedException to the method signature). As I don't want to capture this exception here (I want it to propagate upwards so I can properly deal with it somewhere else), let's alter the signature.

public class Bar implements IFoo {
    public void foo() throws InterruptedException {
        throw new InterruptedException();

This class Bar won't compile either! Bar's method foo() does NOT override IFoo's method foo() since their signatures are different. I could remove the @Override annotation, but I want to program against interface IFoo like IFoo foo; and later on decide on which implementation I want to use, like foo = new Bar();. If Bar's method foo() doesn't override IFoo's method foo, when I do; it won't call Bar's implementation of foo().

To make Bar's public void foo() throws InterruptedException override IFoo's public void foo() I MUST add throws InterruptedException to IFoo's method signature. This, however, will cause problems with my Foo class, since it's foo() method's signature differs from IFoo's method signature. Furthermore, if I added throws InterruptedException to Foo's method foo() I would get another error stating that Foo's method foo() declares that it throws an InterruptedException yet it never throws an InterruptedException.

As you can see (if I did a decent job at explaining this stuff), the fact that I'm throwing a checked exception like InterruptedException is forcing me to tie my interface IFoo to one of it's implementations, which in turn causes havoc on IFoo's other implementations!

This is one big reason why checked exceptions are BAD. In caps.

One solution is to capture the checked exception, wrap it in an unchecked exception and throw the unchecked exception.

jQuery’s .bind() vs. .on()

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

jQuery API documentation for .bind()

php execute a background process

A working solution for both Windows and Linux. Find more on My github page.

function run_process($cmd,$outputFile = '/dev/null', $append = false){
                if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {//'This is a server using Windows!';
                        $cmd = 'wmic process call create "'.$cmd.'" | find "ProcessId"';
                        $handle = popen("start /B ". $cmd, "r");
                        $read = fread($handle, 200); //Read the output 
                        $pid=substr($pid,0,strpos($pid,';') );
                        $pid = (int)$pid;
                        pclose($handle); //Close
                    $pid = (int)shell_exec(sprintf('%s %s %s 2>&1 & echo $!', $cmd, ($append) ? '>>' : '>', $outputFile));
                    return $pid;
            function is_process_running($pid){
                if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {//'This is a server using Windows!';
                        //tasklist /FI "PID eq 6480"
                    $result = shell_exec('tasklist /FI "PID eq '.$pid.'"' );
                    if (count(preg_split("/\n/", $result)) > 0 && !preg_match('/No tasks/', $result)) {
                        return true;
                    $result = shell_exec(sprintf('ps %d 2>&1', $pid));
                    if (count(preg_split("/\n/", $result)) > 2 && !preg_match('/ERROR: Process ID out of range/', $result)) {
                        return true;
                return false;
            function stop_process($pid){
                    if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {//'This is a server using Windows!';
                            $result = shell_exec('taskkill /PID '.$pid );
                        if (count(preg_split("/\n/", $result)) > 0 && !preg_match('/No tasks/', $result)) {
                            return true;
                            $result = shell_exec(sprintf('kill %d 2>&1', $pid));
                        if (!preg_match('/No such process/', $result)) {
                            return true;

Removing Data From ElasticSearch

You can delete the index by Kibana Console:

Console Icon

To get all index:

GET /_cat/indices?v

To delete a specific index:


What and where are the stack and heap?

Others have directly answered your question, but when trying to understand the stack and the heap, I think it is helpful to consider the memory layout of a traditional UNIX process (without threads and mmap()-based allocators). The Memory Management Glossary web page has a diagram of this memory layout.

The stack and heap are traditionally located at opposite ends of the process's virtual address space. The stack grows automatically when accessed, up to a size set by the kernel (which can be adjusted with setrlimit(RLIMIT_STACK, ...)). The heap grows when the memory allocator invokes the brk() or sbrk() system call, mapping more pages of physical memory into the process's virtual address space.

In systems without virtual memory, such as some embedded systems, the same basic layout often applies, except the stack and heap are fixed in size. However, in other embedded systems (such as those based on Microchip PIC microcontrollers), the program stack is a separate block of memory that is not addressable by data movement instructions, and can only be modified or read indirectly through program flow instructions (call, return, etc.). Other architectures, such as Intel Itanium processors, have multiple stacks. In this sense, the stack is an element of the CPU architecture.

How to get streaming url from online streaming radio station

Edited ZygD's answer for python 3.x.:

import re
import urllib.request
import string
url1 = input("Please enter a URL from Tunein Radio: ");
request = urllib.request.Request(url1);
response = urllib.request.urlopen(request);
raw_file ='utf-8');
API_key = re.findall(r"StreamUrl\":\"(.*?),\"",raw_file);
#print API_key;
#print "The API key is: " + API_key[0];
request2 = urllib.request.Request(str(API_key[0]));
response2 = urllib.request.urlopen(request2);
key_content ='utf-8');
raw_stream_url = re.findall(r"Url\": \"(.*?)\"",key_content);
bandwidth = re.findall(r"Bandwidth\":(.*?),", key_content);
reliability = re.findall(r"lity\":(.*?),", key_content);
isPlaylist = re.findall(r"HasPlaylist\":(.*?),",key_content);
codec = re.findall(r"MediaType\": \"(.*?)\",", key_content);
tipe = re.findall(r"Type\": \"(.*?)\"", key_content);
total = 0
for element in raw_stream_url:
    total = total + 1
i = 0
print ("I found " + str(total) + " streams.");
for element in raw_stream_url:
    print ("Stream #" + str(i + 1));
    print ("Stream stats:");
    print ("Bandwidth: " + str(bandwidth[i]) + " kilobytes per second.");
    print ("Reliability: " + str(reliability[i]) + "%");
    print ("HasPlaylist: " + str(isPlaylist[i]));
    print ("Stream codec: " + str(codec[i]));
    print ("This audio stream is " + tipe[i].lower());
    print ("Pure streaming URL: " + str(raw_stream_url[i]));
i = i + 1
input("Press enter to close")

How to wait until an element is present in Selenium?

Let me recommend you using Selenide library. It allows writing much more concise and readable tests. It can wait for presence of elements with much shorter syntax:


Here is a sample project for testing Google search:

Convert file path to a file URI?

At least in .NET 4.5+ you can also do:

var uri = new System.Uri("C:\\foo", UriKind.Absolute);

How to change value of a request parameter in laravel

Use add

$request->request->add(['img' => $img]);

Compilation fails with "relocation R_X86_64_32 against `.rodata.str1.8' can not be used when making a shared object"

In my case this error occurred because a make command was expecting to fetch shared libraries (*.so files) from a remote directory indicated by a LDFLAGS environment variable. In a mistake, only static libraries were available there (*.la or *.a files).

Hence, my problem did not reside with the program I was compiling but with the remote libraries it was trying to fetch. So, I did not need to add any flag (say, -fPIC) to the compilation interrupted by the relocation error. Rather, I recompiled the remote library so that the shared objects were available.

Basically, it's been a file-not-found error in disguise.

In my case I had to remove a misplaced --disable-shared switch in the configure invocation for the requisite program, since shared and static libraries were both built as default.

I noticed that most programs build both types of libraries at the same time, so mine is probably a corner case. In general, it may be the case that you rather have to enable shared libraries, depending on defaults.

To inspect your particular situation with compile switches and defaults, I would read out the summary that shows up with ./configure --help | less, typically in the section Optional Features. I often found that this reading is more reliable than installation guides that are not updated while dependency programs evolve.

How do I convert strings in a Pandas data frame to a 'date' data type?

Use astype

In [31]: df
   a        time
0  1  2013-01-01
1  2  2013-01-02
2  3  2013-01-03

In [32]: df['time'] = df['time'].astype('datetime64[ns]')

In [33]: df
   a                time
0  1 2013-01-01 00:00:00
1  2 2013-01-02 00:00:00
2  3 2013-01-03 00:00:00

How to stash my previous commit?

If you've not pushed either commit to your remote repository, you could use interactive rebasing to 'reorder' your commits and stash the (new) most recent commit's changes only.

Assuming you have the tip of your current branch (commit 111 in your example) checked out, execute the following:

git rebase -i HEAD~2

This will open your default editor, listing most recent 2 commits and provide you with some instructions. Be very cautious as to what you do here, as you are going to effectively 'rewrite' the history of your repository, and can potentially lose work if you aren't careful (make a backup of the whole repository first if necessary). I've estimated commit hashes/titles below for example

pick 222 commit to be stashed
pick 111 commit to be pushed to remote

# Rebase 111..222 onto 333
# Commands:
#  p, pick = use commit
#  r, reword = use commit, but edit the commit message
#  e, edit = use commit, but stop for amending
#  s, squash = use commit, but meld into previous commit
#  f, fixup = like "squash", but discard this commit's log message
#  x, exec = run command (the rest of the line) using shell
# These lines can be re-ordered; they are executed from top to bottom.
# If you remove a line here THAT COMMIT WILL BE LOST.
# However, if you remove everything, the rebase will be aborted.
# Note that empty commits are commented out

Reorder the two commits (they are listed oldest => newest) like this:

pick 111 commit to be pushed to remote
pick 222 commit to be stashed

Save and exit, at which point git will do some processing to rewrite the two commits you have changed. Assuming no issues, you should have reversed the order of your two changesets. This can be confirmed with git log --oneline -5 which will output newest-first.

At this point, you can simply do a soft-reset on the most recent commit, and stash your working changes:

git reset --soft HEAD~1
git stash

It's important to mention that this option is only really viable if you have not previously pushed any of these changes to your remote, otherwise it can cause issues for everyone using the repository.

Flutter - Wrap text on overflow, like insert ellipsis or fade


  child: Container(
      child: Text('OVER FLOW TEST TEXTTTT',
          overflow: TextOverflow.fade)),

This will show OVER FLOW. If there is an overflow, it will be handled.

What are Bearer Tokens and token_type in OAuth 2?

Anyone can define "token_type" as an OAuth 2.0 extension, but currently "bearer" token type is the most common one.

Basically that's what Facebook is using. Their implementation is a bit behind from the latest spec though.

If you want to be more secure than Facebook (or as secure as OAuth 1.0 which has "signature"), you can use "mac" token type.

However, it will be hard way since the mac spec is still changing rapidly.

Call a "local" function within module.exports from another function in module.exports?

You can also save a reference to module's global scope outside the (module.)exports.somemodule definition:

var _this = this;

exports.somefunction = function() {

exports.someotherfunction = function() {

How to stop app that node.js express 'npm start'

You have to press combination ctrl + z My os is Ubuntu

SQL not a single-group group function

Maybe you find this simpler

select * from (
    select ssn, sum(time) from downloads
    group by ssn
    order by sum(time) desc
) where rownum <= 10 --top 10 downloaders


Assign a login to a user created without login (SQL Server)

You have an orphaned user and this can't be remapped with ALTER USER (yet) becauses there is no login to map to. So, you need run CREATE LOGIN first.

If the database level user is

  • a Windows Login, the mapping will be fixed automatcially via the AD SID
  • a SQL Login, use "sid" from sys.database_principals for the SID option for the login


Edit, after comments and updates

The sid from sys.database_principals is for a Windows login.

So trying to create and re-map to a SQL Login will fail

Run this to get the Windows login

SELECT SUSER_SNAME(0x0105000000000009030000001139F53436663A4CA5B9D5D067A02390)


Be consistent and it doesn't matter which one. Also if for some reason you must interop with another program or tool using a certain DEBUG identifier it's easy to do

#define MYDEBUG
#endif //and vice-versa

Regex pattern to match at least 1 number and 1 character in a string

This RE will do:


Explanation of RE:

  • Match either of the following:
    1. At least one number, then one letter or
    2. At least one letter, then one number plus
  • Any remaining numbers and letters

  • (?:...) creates an unreferenced group
  • /i is the ignore-case flag, so that a-z == a-zA-Z.

Setting up redirect in web.config file

In case that you need to add the http redirect in many sites, you could use it as a c# console program:

   class Program
    static int Main(string[] args)
        if (args.Length < 3)
            Console.WriteLine("Please enter an argument: for example insert-redirect ./web.config");
            return 1;

        if (args.Length == 3)
            if (args[0].ToLower() == "-insert-redirect")
                var path = args[1];
                var value = args[2];

                if (InsertRedirect(path, value))
                    Console.WriteLine("Redirect added.");
                return 0;

        Console.WriteLine("Wrong parameters.");
        return 1;


    static bool InsertRedirect(string path, string value)
            XmlDocument doc = new XmlDocument();


            // This should find the appSettings node (should be only one):
            XmlNode nodeAppSettings = doc.SelectSingleNode("//system.webServer");

            var existNode = nodeAppSettings.SelectSingleNode("httpRedirect");
            if (existNode != null)
                return false;

            // Create new <add> node
            XmlNode nodeNewKey = doc.CreateElement("httpRedirect");

            XmlAttribute attributeEnable = doc.CreateAttribute("enabled");
            XmlAttribute attributeDestination = doc.CreateAttribute("destination");
            //XmlAttribute attributeResponseStatus = doc.CreateAttribute("httpResponseStatus");

            // Assign values to both - the key and the value attributes:

            attributeEnable.Value = "true";
            attributeDestination.Value = value;
            //attributeResponseStatus.Value = "Permanent";

            // Add both attributes to the newly created node:

            // Add the node under the 

            return true;
        catch (Exception e)
            Console.WriteLine($"Exception adding redirect: {e.Message}");
            return false;

Convert UTC Epoch to local date

Are you just asking to convert a UTC string to a "local" string? You could do:

var utc_string = '2011-09-05 20:05:15';
var local_string = (function(dtstr) {
    var t0 = new Date(dtstr);
    var t1 = Date.parse(t0.toUTCString().replace('GMT', ''));
    var t2 = (2 * t0) - t1;
    return new Date(t2).toString();

How can I concatenate two arrays in Java?

This one works only with int but the idea is generic

public static int[] junta(int[] v, int[] w) {

int[] junta = new int[v.length + w.length];

for (int i = 0; i < v.length; i++) {            
    junta[i] = v[i];

for (int j = v.length; j < junta.length; j++) {
    junta[j] = w[j - v.length];

How to bind to a PasswordBox in MVVM

You can use this XAML:

        <i:EventTrigger EventName="PasswordChanged">
            <i:InvokeCommandAction Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=PasswordBox}}" CommandParameter="{Binding ElementName=PasswordBox}"/>

And this command execute method:

private void ExecutePasswordChangedCommand(PasswordBox obj)
   if (obj != null)
     Password = obj.Password;

This requires adding the System.Windows.Interactivity assembly to your project and referencing it via xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity".

How do Python's any and all functions work?

>>> any([False, False, False])
>>> any([False, True, False])
>>> all([False, True, True])
>>> all([True, True, True])


Syntactic sugar, makes it more obvious to the casual reader that the join isn't an inner one.

How can a Java program get its own process ID?

Try Sigar . very extensive APIs. Apache 2 license.

private Sigar sigar;

public synchronized Sigar getSigar() {
    if (sigar == null) {
        sigar = new Sigar();
    return sigar;

public synchronized void forceRelease() {
    if (sigar != null) {
        sigar = null;

public long getPid() {
    return getSigar().getPid();

Checking out Git tag leads to "detached HEAD state"

Yes, it is normal. This is because you checkout a single commit, that doesnt have a head. Especially it is (sooner or later) not a head of any branch.

But there is usually no problem with that state. You may create a new branch from the tag, if this makes you feel safer :)

How to create an exit message

The abort function does this. For example:

abort("Message goes here")

Note: the abort message will be written to STDERR as opposed to puts which will write to STDOUT.

JavaScript: How to join / combine two arrays to concatenate into one array?

var a = ['a','b','c'];
var b = ['d','e','f'];
var c = a.concat(b); //c is now an an array with: ['a','b','c','d','e','f']
console.log( c[3] ); //c[3] will be 'd'

Warning: comparison with string literals results in unspecified behaviour

  1. clang has advantages in error reporting & recovery.

    $ clang errors.c
    errors.c:36:21: warning: result of comparison against a string literal is unspecified (use strcmp instead)
            if (args[i] == "&") //WARNING HERE
                        ^~ ~~~
                strcmp( ,     ) == 0
    errors.c:38:26: warning: result of comparison against a string literal is unspecified (use strcmp instead)
            else if (args[i] == "<") //WARNING HERE
                             ^~ ~~~
                     strcmp( ,     ) == 0
    errors.c:44:26: warning: result of comparison against a string literal is unspecified (use strcmp instead)
            else if (args[i] == ">") //WARNING HERE
                             ^~ ~~~
                     strcmp( ,     ) == 0

    It suggests to replace x == y by strcmp(x,y) == 0.

  2. gengetopt writes command-line option parser for you.

Get text of the selected option with jQuery

You could actually put the value = to the text and then do

        val = $j("#select_2 option:selected").html();

Or what I did on a similar case was

<select name="options[2]" id="select_2" onChange="JavascriptMethod()">
  with you're options here

With this second option you should have a undefined. Give me feedback if it worked :)


XPath: select text node

Having the following XML:


How do I select either the first or the second text node via XPath?



This selects all text-node children of the top element (named "node") of the XML document.


This selects the first text-node child of the top element (named "node") of the XML document.


This selects the second text-node child of the top element (named "node") of the XML document.


This selects the someInteger-th text-node child of the top element (named "node") of the XML document. It is equivalent to the following XPath expression:

/node/text()[position() = someInteger]

Error: could not find function "%>%"

You need to load a package (like magrittr or dplyr) that defines the function first, then it should work.

install.packages("magrittr") # package installations are only needed the first time you use it
install.packages("dplyr")    # alternative installation of the %>%
library(magrittr) # needs to be run every time you start R and want to use %>%
library(dplyr)    # alternatively, this also loads %>%

The pipe operator %>% was introduced to "decrease development time and to improve readability and maintainability of code."

But everybody has to decide for himself if it really fits his workflow and makes things easier. For more information on magrittr, click here.

Not using the pipe %>%, this code would return the same as your code:

words <- colnames(as.matrix(dtm))
words <- words[nchar(words) < 20]

EDIT: (I am extending my answer due to a very useful comment that was made by @Molx)

Despite being from magrittr, the pipe operator is more commonly used with the package dplyr (which requires and loads magrittr), so whenever you see someone using %>% make sure you shouldn't load dplyr instead.

SQL GROUP BY CASE statement with aggregate function

I think the answer is pretty simple (unless I'm missing something?)

    WHEN col1 > col2 THEN SUM(col3*col4)
    ELSE 0
END AS some_product
FROM some_table
    WHEN col1 > col2 THEN SUM(col3*col4)
    ELSE 0

You can put the CASE STATEMENT in the GROUP BY verbatim (minus the alias column name)

How to open a txt file and read numbers in Java

Good news in Java 8 we can do it in one line:

List<Integer> ints = Files.lines(Paths.get(fileName))

Swift Error: Editor placeholder in source file

Sometimes, XCode does not forget the line which had an "Editor Placeholder" even if you have replaced it with a value. Cut the portion of the code where XCode is complaining and paste the code back to the same place to make the error message go away. This worked for me.

Add Facebook Share button to static HTML page

 <div class="fb_share">
     <a name="fb_share" type="box_count" share_url="<?php the_permalink() ?>"
     <script src="" type="text/javascript"></script> </div> <?php }  }


How to reset radiobuttons in jQuery so that none is checked

Your problem is that the attribute selector doesn't start with a @.

Try this:

$('input[name="correctAnswer"]').attr('checked', false);

Border for an Image view in Android?

you must create a background.xml in res/drawable this code

<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="">
<solid android:color="#FFFFFF" />
<corners android:radius="6dp" />
    android:color="@android:color/white" />
    android:top="6dp" />

How to keep :active css style after click a button


:active denotes the interaction state (so for a button will be applied during press), :focus may be a better choice here. However, the styling will be lost once another element gains focus.

The final potential alternative using CSS would be to use :target, assuming the items being clicked are setting routes (e.g. anchors) within the page- however this can be interrupted if you are using routing (e.g. Angular), however this doesnt seem the case here.

.active:active {_x000D_
  color: red;_x000D_
.focus:focus {_x000D_
  color: red;_x000D_
:target {_x000D_
  color: red;_x000D_
<button class='active'>Active</button>_x000D_
<button class='focus'>Focus</button>_x000D_
<a href='#target1' id='target1' class='target'>Target 1</a>_x000D_
<a href='#target2' id='target2' class='target'>Target 2</a>_x000D_
<a href='#target3' id='target3' class='target'>Target 3</a>

Javascript / jQuery

As such, there is no way in CSS to absolutely toggle a styled state- if none of the above work for you, you will either need to combine with a change in your HTML (e.g. based on a checkbox) or programatically apply/remove a class using e.g. jQuery

$('button').on('click', function(){_x000D_
<script src=""></script>_x000D_

HTML Upload MAX_FILE_SIZE does not appear to work

There IS A POINT in introducing MAX_FILE_SIZE client side hidden form field.

php.ini can limit uploaded file size. So, while your script honors the limit imposed by php.ini, different HTML forms can further limit an uploaded file size. So, when uploading video, form may limit* maximum size to 10MB, and while uploading photos, forms may put a limit of just 1mb. And at the same time, the maximum limit can be set in php.ini to suppose 10mb to allow all this.

Although this is not a fool proof way of telling the server what to do, yet it can be helpful.

  • HTML does'nt limit anything. It just forwards the server all form variable including MAX_FILE_SIZE and its value.

Hope it helped someone.

Authentication failed to bitbucket

  • Inside company but will held true anywhere.
    • Logout from Bitbucket ( in case you are using)
    • Login with your credential
    • Go back to console
    • Fire the same command
    • It will ask for password - Provide it.
    • You are good to go.

What is the use of static synchronized method in java?

At run time every loaded class has an instance of a Class object. That is the object that is used as the shared lock object by static synchronized methods. (Any synchronized method or block has to lock on some shared object.)

You can also synchronize on this object manually if wanted (whether in a static method or not). These three methods behave the same, allowing only one thread at a time into the inner block:

class Foo {
    static synchronized void methodA() {
        // ...

    static void methodB() {
        synchronized (Foo.class) {
            // ...

    static void methodC() {
        Object lock = Foo.class;
        synchronized (lock) {
            // ...

The intended purpose of static synchronized methods is when you want to allow only one thread at a time to use some mutable state stored in static variables of a class.

Nowadays, Java has more powerful concurrency features, in java.util.concurrent and its subpackages, but the core Java 1.0 constructs such as synchronized methods are still valid and usable.

How to delete last item in list?

If you do a lot with timing, I can recommend this little (20 line) context manager:

You code could look like this then:

#!/usr/bin/env python
# coding: utf-8

from timer import Timer

if __name__ == '__main__':
    a, record = None, []
    while not a == '':
        with Timer() as t: # everything in the block will be timed
            a = input('Type: ')
    # drop the last item (makes a copy of the list):
    record = record[:-1] 
    # or just delete it:
    # del record[-1]

Just for reference, here's the content of the Timer context manager in full:

from timeit import default_timer

class Timer(object):
    """ A timer as a context manager. """

    def __init__(self):
        self.timer = default_timer
        # measures wall clock time, not CPU time!
        # On Unix systems, it corresponds to time.time
        # On Windows systems, it corresponds to time.clock

    def __enter__(self):
        self.start = self.timer() # measure start time
        return self

    def __exit__(self, exc_type, exc_value, exc_traceback):
        self.end = self.timer() # measure end time
        self.elapsed_s = self.end - self.start # elapsed time, in seconds
        self.elapsed_ms = self.elapsed_s * 1000  # elapsed time, in milliseconds

Multi-threading in VBA

As you probably learned VBA does not natively support multithreading but. There are 3 methods to achieve multithreading:

  1. COM/dlls - e.g. C# and the Parallel class to run in separate threads
  2. Using VBscript worker threads - run your VBA code in separate VBscript threads
  3. Using VBA worker threads executed e.g. via VBscript - copy the Excel workbook and run your macro in parallel.

I compared all thread approaches here:

Considering approach #3 I also made a VBA Multithreading Tool that allows you to easily add multithreading to VBA:

See the examples below:

Multithreading a For Loop

Sub RunForVBA(workbookName As String, seqFrom As Long, seqTo As Long)
    For i = seqFrom To seqTo
        x = seqFrom / seqTo
    Next i
End Sub

Sub RunForVBAMultiThread()
    Dim parallelClass As Parallel 

    Set parallelClass = New Parallel 

    parallelClass.SetThreads 4 

    Call parallelClass.ParallelFor("RunForVBA", 1, 1000) 
End Sub

Run an Excel macro asynchronously

Sub RunAsyncVBA(workbookName As String, seqFrom As Long, seqTo As Long)
    For i = seqFrom To seqTo
        x = seqFrom / seqTo
    Next i
End Sub

Sub RunForVBAAndWait()
    Dim parallelClass As Parallel

    Set parallelClass  = New Parallel

    Call parallelClass.ParallelAsyncInvoke("RunAsyncVBA", ActiveWorkbook.Name, 1, 1000) 
    'Do other operations here

End Sub

Change some value inside the List<T>

I know this is an old post but, I've always used an updater extension method:

      public static void Update<TSource>(this IEnumerable<TSource> outer, Action<TSource> updator)
            foreach (var item in outer)

list.Where(w => w.Name == "height").ToList().Update(u => u.height = 30);

What is the difference between GitHub and gist?

GitHub Gists

To gist or not to gist. That is the $64 question ...

GitHub Gists are Single ( or, multiple ) Simple Markdown Files with repo-like qualities that can be forked or cloned ( if public ).

Otherwise, not if private.

Kinda like a fancy scratch pad that can be shared.

Similar to this comment scratch pad that I am typing on now, but a bit more elaborate.

Whereas, an official, full GitHub repo is a full blown repository of source code src, supporting documents ( markdown or html, or both ) docs or root, images png, ico, svg, and a config.sys file for running Yaml variables hosted on a Jekyll server.

Does a simple Gist file support Yaml front matter?

Me thinks not.

From the official GitHub Gist documentation ...

The gist editor is powered by CodeMirror.

However, you can copy a public Gist ( or, a private Gist if the owner has granted you access via a link to the private Gist ) ...

And, you can then embed that public Gist into an "official" repo using Visual Studio Code, as follows:

"You can embed a gist in any text field that supports Javascript, such as a blog post."

"To get the embed code, click the clipboard icon next to the Embed URL button of a gist."

Now, that's a cool feature.

Makes me want to search ( discover ) other peoples' gists, or OPG and incorporate their "public" work into my full-blown working repos.

"You can discover the PUBLIC gists others have created by going to the gist home page and clicking on the link ...

All Gists{:title='Click to Review the Discover Feature at GitHub Gists'}{:target='_blank'}."

Caveat. No support for Liquid tags at GitHub Gist.

I suppose if I do find something beneficial, I can always ping-back, or cite that source if I do use the work in my full-blown working repos.

Where is the implicit license posted for all gists made public by their authors?


P.S. This is a good comment. I think I will turn this into a gist and make it publically searchable over at GitHub Gists.

Note. When embedding the <script></script> html tag within the body of a Markdown (.md) file, you may get a warning "MD033" from your linter.

This should not, however, affect the rendering of the data ( src ) called from within the script tag.

To change the default warning flag to accommodate the called contents of a script tag from within Visual Studio Code, add an entry to the Markdownlint Configuration Object within the User Settings Json file, as follows:

// Begin Markdownlint Configuration Object
"markdownlint.config": {
  "MD013": false,
  "MD033": {"allowed_elements": ["script"]}
}// End Markdownlint Configuration Object

Note. Solution derived from GitHub Commit by David Anson

How do I get the computer name in .NET

I set the .InnerHtml of a <p> bracket for my web project to the user's computer name doing the following:


    <div class="col-md-4">
       <h2>Your Computer Name Is</h2>
       <p id="pcname" runat="server"></p>
           <a class="btn btn-default" href="#">Learn more &raquo;</a>


using System;
using System.Web.UI;

namespace GetPCName {
   public partial class _Default : Page {
    protected void Page_Load(object sender, EventArgs e) {            
        pcname.InnerHtml = Environment.MachineName;

How to kill all processes matching a name?

I think this command killall is exactly what you need. The command is described as "kill processes by name".It's easy to use.For example

killall chrome

This command will kill all process of Chrome.Here is a link about killall command

Hope this command could help you.

How to do a regular expression replace in MySQL?

My brute force method to get this to work was just:

  1. Dump the table - mysqldump -u user -p database table > dump.sql
  2. Find and replace a couple patterns - find /path/to/dump.sql -type f -exec sed -i 's/old_string/new_string/g' {} \;, There are obviously other perl regeular expressions you could perform on the file as well.
  3. Import the table - mysqlimport -u user -p database table < dump.sql

If you want to make sure the string isn't elsewhere in your dataset, run a few regular expressions to make sure they all occur in a similar environment. It's also not that tough to create a backup before you run a replace, in case you accidentally destroy something that loses depth of information.

Gradle: How to Display Test Results in the Console in Real Time?

If you are using jupiter and none of the answers work, consider verifying it is setup correctly:

test {
    outputs.upToDateWhen { false }

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.7.0'
    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.7.0'

And then try the accepted answers

Split Div Into 2 Columns Using CSS

Best way to divide a div vertically --

#parent {
    margin: 0;
    width: 100%;
.left {
    float: left;
    width: 60%;
.right {
    overflow: hidden;
    width: 40%;

How do I print out the value of this boolean? (Java)

There are several problems.

One is of style; always capitalize class names. This is a universally observed Java convention. Failing to do so confuses other programmers.

Secondly, the line

System.out.println(boolean isLeapYear);

is a syntax error. Delete it.


You never call the function from your main routine. That is why you never see any reply to the input.

Count the number of items in my array list

Outside of your loop create an int:

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

Then in the loop, increment it:

itemId = p.getItemId();

Error Code: 1062. Duplicate entry '1' for key 'PRIMARY'

The main reason why the error has been generated is because there is already an existing value of 1 for the column ID in which you define it as PRIMARY KEY (values are unique) in the table you are inserting.

Why not set the column ID as AUTO_INCREMENT?

  `viale` VARCHAR(45) NULL ,

and when you are inserting record, you can now skip the column ID

INSERT INTO `PROGETTO`.`UFFICIO-INFORMAZIONI` (`viale`, `num_civico`, ...) 
VALUES ('Viale Cogel ', '120', ...)

SimpleXML - I/O warning : failed to load external entity

this also works:

$url = "http://www.some-url";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$xmlresponse = curl_exec($ch);

then I just run a forloop to grab the stuff from the nodes.

like this:`

for($i = 0; $i < 20; $i++) {
$title = $xml->channel->item[$i]->title;
$link = $xml->channel->item[$i]->link;
$desc = $xml->channel->item[$i]->description;
$html .="<div><h3>$title</h3>$link<br />$desc</div><hr>";
echo $html;

***note that your node names will differ, obviously..and your HTML might be structured differently...also your loop might be set to higher or lower amount of results.

Django - Did you forget to register or load this tag?

The app that contains the custom tags must be in INSTALLED_APPS. So Are you sure that your directory is in INSTALLED_APPS ?

From the documentation:

The app that contains the custom tags must be in INSTALLED_APPS in order for the {% load %} tag to work. This is a security feature: It allows you to host Python code for many template libraries on a single host machine without enabling access to all of them for every Django installation.

Return generated pdf using spring MVC

You were on the right track with response.getOutputStream(), but you're not using its output anywhere in your code. Essentially what you need to do is to stream the PDF file's bytes directly to the output stream and flush the response. In Spring you can do it like this:

@RequestMapping(value="/getpdf", method=RequestMethod.POST)
public ResponseEntity<byte[]> getPDF(@RequestBody String json) {
    // convert JSON to Employee 
    Employee emp = convertSomehow(json);

    // generate the file

    // retrieve contents of "C:/tmp/report.pdf" that were written in showHelp
    byte[] contents = (...);

    HttpHeaders headers = new HttpHeaders();
    // Here you have to set the actual filename of your pdf
    String filename = "output.pdf";
    headers.setContentDispositionFormData(filename, filename);
    headers.setCacheControl("must-revalidate, post-check=0, pre-check=0");
    ResponseEntity<byte[]> response = new ResponseEntity<>(contents, headers, HttpStatus.OK);
    return response;


  • use meaningful names for your methods: naming a method that writes a PDF document showHelp is not a good idea
  • reading a file into a byte[]: example here
  • I'd suggest adding a random string to the temporary PDF file name inside showHelp() to avoid overwriting the file if two users send a request at the same time

create a white rgba / CSS3

For completely transparent color, use:


A little more visible:


How to run or debug php on Visual Studio Code (VSCode)

XDebug changed some configuration settings.

Old settings:

xdebug.remote_enable = 1
xdebug.remote_autostart = 1
xdebug.remote_port = 9000

New settings:


So you should paste the latter in php.ini file. More info: XDebug Changed Configuration Settings

The imported project "C:\Microsoft.CSharp.targets" was not found

This is a global solution, not dependent on particular package or bin.

In my case, I removed Packages folder from my root directory.

Maybe it happens because of your packages are there but compiler is not finding it's reference. so remove older packages first and add new packages.

Steps to Add new packages

  • First remove, packages folder (it will be near by or one step up to your current project folder).
  • Then restart the project or solution.
  • Now, Rebuild solution file.
  • Project will get new references from nuGet package manager. And your issue will be resolved.

This is not proper solution, but I posted it here because I face same issue.

In my case, I wasn't even able to open my solution in visual studio and didn't get any help with other SO answers.

'tuple' object does not support item assignment

PIL pixels are tuples, and tuples are immutable. You need to construct a new tuple. So, instead of the for loop, do:

pixels = [(pixel[0] + 20, pixel[1], pixel[2]) for pixel in pixels]

Also, if the pixel is already too red, adding 20 will overflow the value. You probably want something like min(pixel[0] + 20, 255) or int(255 * (pixel[0] / 255.) ** 0.9) instead of pixel[0] + 20.

And, to be able to handle images in lots of different formats, do image = image.convert("RGB") after opening the image. The convert method will ensure that the pixels are always (r, g, b) tuples.

Chrome's remote debugging (USB debugging) not working for Samsung Galaxy S3 running android 4.3

For me, the menu item Inspect Devices wasn't available (not shown at all). But, simply browsing to chrome://inspect/#devices showed me my device and I was able to use the port forward etc. I have no idea why the menu item is not displayed.

Phone: Android Galaxy S4

OS: Mac OS X

Left/Right float button inside div

Change display:inline to display:inline-block

.test {
  overflow: auto;
  white-space: nowrap;
  margin:0px auto;
  border:1px red solid;

How are POST and GET variables handled in Python?

Python is only a language, to get GET and POST data, you need a web framework or toolkit written in Python. Django is one, as Charlie points out, the cgi and urllib standard modules are others. Also available are Turbogears, Pylons, CherryPy,, mod_python, fastcgi, etc, etc.

In Django, your view functions receive a request argument which has request.GET and request.POST. Other frameworks will do it differently.

iOS UIImagePickerController result image orientation after upload

A UIImage has a property imageOrientation, which instructs the UIImageView and other UIImage consumers to rotate the raw image data. There's a good chance that this flag is being saved to the exif data in the uploaded jpeg image, but the program you use to view it is not honoring that flag.

To rotate the UIImage to display properly when uploaded, you can use a category like this:


@interface UIImage (fixOrientation)

- (UIImage *)fixOrientation;



@implementation UIImage (fixOrientation)

- (UIImage *)fixOrientation {

    // No-op if the orientation is already correct
    if (self.imageOrientation == UIImageOrientationUp) return self;

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    CGAffineTransform transform = CGAffineTransformIdentity;

    switch (self.imageOrientation) {
        case UIImageOrientationDown:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height);
            transform = CGAffineTransformRotate(transform, M_PI);

        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.width, 0);
            transform = CGAffineTransformRotate(transform, M_PI_2);

        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, 0, self.size.height);
            transform = CGAffineTransformRotate(transform, -M_PI_2);
        case UIImageOrientationUp:
        case UIImageOrientationUpMirrored:

    switch (self.imageOrientation) {
        case UIImageOrientationUpMirrored:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.width, 0);
            transform = CGAffineTransformScale(transform, -1, 1);

        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.height, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
        case UIImageOrientationUp:
        case UIImageOrientationDown:
        case UIImageOrientationLeft:
        case UIImageOrientationRight:

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    CGContextRef ctx = CGBitmapContextCreate(NULL, self.size.width, self.size.height,
                                             CGImageGetBitsPerComponent(self.CGImage), 0,
    CGContextConcatCTM(ctx, transform);
    switch (self.imageOrientation) {
        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            // Grr...
            CGContextDrawImage(ctx, CGRectMake(0,0,self.size.height,self.size.width), self.CGImage);

            CGContextDrawImage(ctx, CGRectMake(0,0,self.size.width,self.size.height), self.CGImage);

    // And now we just create a new UIImage from the drawing context
    CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
    UIImage *img = [UIImage imageWithCGImage:cgimg];
    return img;


How do you get AngularJS to bind to the title attribute of an A tag?

Look at the fiddle here for a quick answer

data-ng-attr-title="{{d.age > 5 ? 'My age is greater than threshold': ''}}"

Displays Title over elements conditionally using Angular JS

What does this symbol mean in JavaScript?

See the documentation on MDN about expressions and operators and statements.

Basic keywords and general expressions

this keyword:

var x = function() vs. function x() — Function declaration syntax

(function(){})() — IIFE (Immediately Invoked Function Expression)

someFunction()() — Functions which return other functions

=> — Equal sign, greater than: arrow function expression syntax

|> — Pipe, greater than: Pipeline operator

function*, yield, yield* — Star after function or yield: generator functions

[], Array() — Square brackets: array notation

If the square brackets appear on the left side of an assignment ([a] = ...), or inside a function's parameters, it's a destructuring assignment.

{key: value} — Curly brackets: object literal syntax (not to be confused with blocks)

If the curly brackets appear on the left side of an assignment ({ a } = ...) or inside a function's parameters, it's a destructuring assignment.

`${}` — Backticks, dollar sign with curly brackets: template literals

// — Slashes: regular expression literals

$ — Dollar sign in regex replace patterns: $$, $&, $`, $', $n

() — Parentheses: grouping operator

Property-related expressions

obj.prop, obj[prop], obj["prop"] — Square brackets or dot: property accessors

?., ?.[], ?.() — Question mark, dot: optional chaining operator

:: — Double colon: bind operator

new operator

...iter — Three dots: spread syntax; rest parameters

Increment and decrement

++, -- — Double plus or minus: pre- / post-increment / -decrement operators

Unary and binary (arithmetic, logical, bitwise) operators

delete operator

void operator

+, - — Plus and minus: addition or concatenation, and subtraction operators; unary sign operators

|, &, ^, ~ — Single pipe, ampersand, circumflex, tilde: bitwise OR, AND, XOR, & NOT operators

% — Percent sign: remainder operator

&&, ||, ! — Double ampersand, double pipe, exclamation point: logical operators

?? — Double question mark: nullish-coalescing operator

** — Double star: power operator (exponentiation)

Equality operators

==, === — Equal signs: equality operators

!=, !== — Exclamation point and equal signs: inequality operators

Bit shift operators

<<, >>, >>> — Two or three angle brackets: bit shift operators

Conditional operator

?:… — Question mark and colon: conditional (ternary) operator

Assignment operators

= — Equal sign: assignment operator

%= — Percent equals: remainder assignment

+= — Plus equals: addition assignment operator

&&=, ||=, ??= — Double ampersand, pipe, or question mark, followed by equal sign: logical assignments


Comma operator

, — Comma operator

Control flow

{} — Curly brackets: blocks (not to be confused with object literal syntax)


var, let, const — Declaring variables


label: — Colon: labels

# — Hash (number sign): Private methods or private fields

regular expression for Indian mobile numbers

var PHONE_REGEXP = /^[789]\d{9}$/;

this works for ng-pattern in angularjs or in javascript or any js framework

pandas get column average/mean

You can simply go for: df.describe() that will provide you with all the relevant details you need, but to find the min, max or average value of a particular column (say 'weights' in your case), use:

    df['weights'].mean(): For average value
    df['weights'].max(): For maximum value
    df['weights'].min(): For minimum value

Editing legend (text) labels in ggplot

The tutorial @Henrik mentioned is an excellent resource for learning how to create plots with the ggplot2 package.

An example with your data:

# transforming the data from wide to long
dfm <- melt(df, id = "TY")

# creating a scatterplot
ggplot(data = dfm, aes(x = TY, y = value, color = variable)) + 
  geom_point(size=5) +
  labs(title = "Temperatures\n", x = "TY [°C]", y = "Txxx", color = "Legend Title\n") +
  scale_color_manual(labels = c("T999", "T888"), values = c("blue", "red")) +
  theme_bw() +
  theme(axis.text.x = element_text(size = 14), axis.title.x = element_text(size = 16),
        axis.text.y = element_text(size = 14), axis.title.y = element_text(size = 16),
        plot.title = element_text(size = 20, face = "bold", color = "darkgreen"))

this results in:

enter image description here

As mentioned by @user2739472 in the comments: If you only want to change the legend text labels and not the colours from ggplot's default palette, you can use scale_color_hue(labels = c("T999", "T888")) instead of scale_color_manual().

How to reload page the page with pagination in Angular 2?

This should technically be achievable using window.location.reload():


<button (click)="refresh()">Refresh</button>


refresh(): void {


Here is a basic StackBlitz example showing the refresh in action. Notice the URL on "/hello" path is retained when window.location.reload() is executed.

How do I perform a Perl substitution on a string while keeping the original?

The statement:

(my $newstring = $oldstring) =~ s/foo/bar/g;

Which is equivalent to:

my $newstring = $oldstring;
$newstring =~ s/foo/bar/g;

Alternatively, as of Perl 5.13.2 you can use /r to do a non destructive substitution:

use 5.013;
my $newstring = $oldstring =~ s/foo/bar/gr;

Deserializing JSON Object Array with

Using the accepted answer you have to access each record by using Customers[i].customer, and you need an extra CustomerJson class, which is a little annoying. If you don't want to do that, you can use the following:

public class CustomerList
    public List<Customer> customer { get; set; }

Note that I'm using a List<>, not an Array. Now create the following class:

class MyListConverter : JsonConverter
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        var token = JToken.Load(reader);
        var list = Activator.CreateInstance(objectType) as System.Collections.IList;
        var itemType = objectType.GenericTypeArguments[0];
        foreach (var child in token.Values())
            var childToken = child.Children().First();
            var newObject = Activator.CreateInstance(itemType);
            serializer.Populate(childToken.CreateReader(), newObject);
        return list;

    public override bool CanConvert(Type objectType)
        return objectType.IsGenericType && (objectType.GetGenericTypeDefinition() == typeof(List<>));
    public override bool CanWrite => false;
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) => throw new NotImplementedException();

Concatenate text files with Windows command line, dropping leading lines

The help for copy explains that wildcards can be used to concatenate multiple files into one.

For example, to copy all .txt files in the current folder that start with "abc" into a single file named xyz.txt:

copy abc*.txt xyz.txt

Convert a hexadecimal string to an integer efficiently in C?


I was actually hoping to see a C wizard post something really cool, sort of like what I did but less verbose, while still doing it "manually".

Well, I'm no C guru, but here's what I came up with:

unsigned int parseHex(const char * str)
    unsigned int val = 0;
    char c;

    while(c = *str++)
        val <<= 4;

        if (c >= '0' && c <= '9')
            val += c & 0x0F;

        c &= 0xDF;
        if (c >= 'A' && c <= 'F')
            val += (c & 0x07) + 9;

        errno = EINVAL;
        return 0;

    return val;

I originally had more bitmasking going on instead of comparisons, but I seriously doubt bitmasking is any faster than comparison on modern hardware.

A select query selecting a select statement

Not sure if Access supports it, but in most engines (including SQL Server) this is called a correlated subquery and works fine:

SELECT  TypesAndBread.Type, TypesAndBread.TBName,
        SELECT  Count(Sandwiches.[SandwichID]) As SandwichCount
        FROM    Sandwiches
        WHERE   (Type = 'Sandwich Type' AND Sandwiches.Type = TypesAndBread.TBName)
                OR (Type = 'Bread' AND Sandwiches.Bread = TypesAndBread.TBName)
        ) As SandwichCount
FROM    TypesAndBread

This can be made more efficient by indexing Type and Bread and distributing the subqueries over the UNION:

SELECT  [Sandwiches Types].[Sandwich Type] As TBName, "Sandwich Type" As Type,
        SELECT  COUNT(*) As SandwichCount
        FROM    Sandwiches
        WHERE   Sandwiches.Type = [Sandwiches Types].[Sandwich Type]
FROM    [Sandwiches Types]
SELECT  [Breads].[Bread] As TBName, "Bread" As Type,
        SELECT  COUNT(*) As SandwichCount
        FROM    Sandwiches
        WHERE   Sandwiches.Bread = [Breads].[Bread]
FROM    [Breads]

Where does VBA Debug.Print log to?

Where do you want to see the output?

Messages being output via Debug.Print will be displayed in the immediate window which you can open by pressing Ctrl+G.

You can also Activate the so called Immediate Window by clicking View -> Immediate Window on the VBE toolbar

enter image description here

sql query distinct with Row_Number

Try this:

               SELECT DISTINCT id FROM table WHERE fid = 64
  FROM cte
 WHERE fid = 64

IOError: [Errno 13] Permission denied

I had a similar problem. I was attempting to have a file written every time a user visits a website.

The problem ended up being twofold.

1: the permissions were not set correctly

2: I attempted to use
f = open(r"newfile.txt","w+") (Wrong)

After changing the file to 777 (all users can read/write)
chmod 777 /var/www/path/to/file
and changing the path to an absolute path, my problem was solved
f = open(r"/var/www/path/to/file/newfile.txt","w+") (Right)

Dead simple example of using Multiprocessing Queue, Pool and Locking

This might be not 100% related to the question, but on my search for an example of using multiprocessing with a queue this shows up first on google.

This is a basic example class that you can instantiate and put items in a queue and can wait until queue is finished. That's all I needed.

from multiprocessing import JoinableQueue
from multiprocessing.context import Process

class Renderer:
    queue = None

    def __init__(self, nb_workers=2):
        self.queue = JoinableQueue()
        self.processes = [Process(target=self.upload) for i in range(nb_workers)]
        for p in self.processes:

    def render(self, item):

    def upload(self):
        while True:
            item = self.queue.get()
            if item is None:

            # process your item here


    def terminate(self):
        """ wait until queue is empty and terminate processes """
        for p in self.processes:

r = Renderer()

How to process POST data in Node.js?

For those using raw binary POST upload without encoding overhead you can use:


var xhr = new XMLHttpRequest();"POST", "/api/upload", true);
var blob = new Uint8Array([65,72,79,74]); // or e.g. recorder.getBlob()


var express = require('express');
var router = express.Router();
var fs = require('fs');

router.use (function(req, res, next) {
  var data='';
  req.on('data', function(chunk) {
    data += chunk;

  req.on('end', function() {
    req.body = data;
});'/api/upload', function(req, res, next) {
  fs.writeFile("binaryFile.png", req.body, 'binary', function(err) {
    res.send("Binary POST successful!");

How to do an array of hashmaps?

What gives? It works. Just ignore it:


No, you cannot parameterize it. I'd however rather use a List<Map<K, V>> instead.

List<Map<String, String>> listOfMaps = new ArrayList<Map<String, String>>();

To learn more about collections and maps, have a look at this tutorial.

Is Unit Testing worth the effort?

Unit testing helps a lot in projects that are larger than any one developer can hold in their head. They allow you to run the unit test suite before checkin and discover if you broke something. This cuts down a lot on instances of having to sit and twiddle your thumbs while waiting for someone else to fix a bug they checked in, or going to the hassle of reverting their change so you can get some work done. It's also immensely valuable in refactoring, so you can be sure that the refactored code passes all the tests that the original code did.

UPDATE multiple tables in MySQL using LEFT JOIN

UPDATE `Table A` a
SET a.`text`=(
        SELECT group_concat(b.`B-num`,' from ',b.`date` SEPARATOR ' / ') 
        FROM `Table B` b WHERE (a.`A-num`=b.`A-num`)

Generating random numbers in Objective-C

Generate random number between 0 to 99:

int x = arc4random()%100;

Generate random number between 500 and 1000:

int x = (arc4random()%501) + 500;

Python error when trying to access list by index - "List indices must be integers, not str"

players is a list which needs to be indexed by integers. You seem to be using it like a dictionary. Maybe you could use unpacking -- Something like:

name, score = player

(if the player list is always a constant length).

There's not much more advice we can give you without knowing what query is and how it works.

It's worth pointing out that the entire code you posted doesn't make a whole lot of sense. There's an IndentationError on the second line. Also, your function is looping over some iterable, but unconditionally returning during the first iteration which isn't usually what you actually want to do.

Python error message io.UnsupportedOperation: not readable

This will let you read, write and create the file if it don't exist:

f = open('filename.txt','a+')
f = open('filename.txt','r+')

Often used commands:

f.readline() #Read next line #Jump to beginning #Read all file
f.write('test text') #Write 'test text' to file
f.close() #Close file

Volatile Vs Atomic

Volatile and Atomic are two different concepts. Volatile ensures, that a certain, expected (memory) state is true across different threads, while Atomics ensure that operation on variables are performed atomically.

Take the following example of two threads in Java:

Thread A:

value = 1;
done = true;

Thread B:

if (done)

Starting with value = 0 and done = false the rule of threading tells us, that it is undefined whether or not Thread B will print value. Furthermore value is undefined at that point as well! To explain this you need to know a bit about Java memory management (which can be complex), in short: Threads may create local copies of variables, and the JVM can reorder code to optimize it, therefore there is no guarantee that the above code is run in exactly that order. Setting done to true and then setting value to 1 could be a possible outcome of the JIT optimizations.

volatile only ensures, that at the moment of access of such a variable, the new value will be immediately visible to all other threads and the order of execution ensures, that the code is at the state you would expect it to be. So in case of the code above, defining done as volatile will ensure that whenever Thread B checks the variable, it is either false, or true, and if it is true, then value has been set to 1 as well.

As a side-effect of volatile, the value of such a variable is set thread-wide atomically (at a very minor cost of execution speed). This is however only important on 32-bit systems that i.E. use long (64-bit) variables (or similar), in most other cases setting/reading a variable is atomic anyways. But there is an important difference between an atomic access and an atomic operation. Volatile only ensures that the access is atomically, while Atomics ensure that the operation is atomically.

Take the following example:

i = i + 1;

No matter how you define i, a different Thread reading the value just when the above line is executed might get i, or i + 1, because the operation is not atomically. If the other thread sets i to a different value, in worst case i could be set back to whatever it was before by thread A, because it was just in the middle of calculating i + 1 based on the old value, and then set i again to that old value + 1. Explanation:

Assume i = 0
Thread A reads i, calculates i+1, which is 1
Thread B sets i to 1000 and returns
Thread A now sets i to the result of the operation, which is i = 1

Atomics like AtomicInteger ensure, that such operations happen atomically. So the above issue cannot happen, i would either be 1000 or 1001 once both threads are finished.

rails + MySQL on OSX: Library not loaded: libmysqlclient.18.dylib

After a lot of googling and trying all above...the only thing that solved my problem was this command:

$install_name_tool -id /usr/local/lib/libmysqlclient.18.dylib /usr/local/lib/libmysqlclient.18.dylib

I am using a macbook pro, OSX 10 El Capitan. Darwin xxxx-MacBook-Pro.local 15.6.0 Darwin Kernel Version 15.6.0: Thu Jun 23 18:25:34 PDT 2016; XXX:xnu-3248.60.10~1/RELEASE_X86_64 x86_64 Perl:v5.18.2 Mysql:5.6.19

RegEx for matching "A-Z, a-z, 0-9, _" and "."


From beginning until the end of the string, match one or more of these characters.


Note that ^ and $ match the beginning and the end of a line. When multiline is enabled, this can mean that one line matches, but not the complete string.

Use \A for the beginning of the string, and \z for the end.

See for example:

How can I reconcile detached HEAD with master/origin?

First, let’s clarify what HEAD is and what it means when it is detached.

HEAD is the symbolic name for the currently checked out commit. When HEAD is not detached (the “normal”1 situation: you have a branch checked out), HEAD actually points to a branch’s “ref” and the branch points to the commit. HEAD is thus “attached” to a branch. When you make a new commit, the branch that HEAD points to is updated to point to the new commit. HEAD follows automatically since it just points to the branch.

  • git symbolic-ref HEAD yields refs/heads/master
    The branch named “master” is checked out.
  • git rev-parse refs/heads/master yield 17a02998078923f2d62811326d130de991d1a95a
    That commit is the current tip or “head” of the master branch.
  • git rev-parse HEAD also yields 17a02998078923f2d62811326d130de991d1a95a
    This is what it means to be a “symbolic ref”. It points to an object through some other reference.
    (Symbolic refs were originally implemented as symbolic links, but later changed to plain files with extra interpretation so that they could be used on platforms that do not have symlinks.)

We have HEAD ? refs/heads/master ? 17a02998078923f2d62811326d130de991d1a95a

When HEAD is detached, it points directly to a commit—instead of indirectly pointing to one through a branch. You can think of a detached HEAD as being on an unnamed branch.

  • git symbolic-ref HEAD fails with fatal: ref HEAD is not a symbolic ref
  • git rev-parse HEAD yields 17a02998078923f2d62811326d130de991d1a95a
    Since it is not a symbolic ref, it must point directly to the commit itself.

We have HEAD ? 17a02998078923f2d62811326d130de991d1a95a

The important thing to remember with a detached HEAD is that if the commit it points to is otherwise unreferenced (no other ref can reach it), then it will become “dangling” when you checkout some other commit. Eventually, such dangling commits will be pruned through the garbage collection process (by default, they are kept for at least 2 weeks and may be kept longer by being referenced by HEAD’s reflog).

1 It is perfectly fine to do “normal” work with a detached HEAD, you just have to keep track of what you are doing to avoid having to fish dropped history out of the reflog.

The intermediate steps of an interactive rebase are done with a detached HEAD (partially to avoid polluting the active branch’s reflog). If you finish the full rebase operation, it will update your original branch with the cumulative result of the rebase operation and reattach HEAD to the original branch. My guess is that you never fully completed the rebase process; this will leave you with a detached HEAD pointing to the commit that was most recently processed by the rebase operation.

To recover from your situation, you should create a branch that points to the commit currently pointed to by your detached HEAD:

git branch temp
git checkout temp

(these two commands can be abbreviated as git checkout -b temp)

This will reattach your HEAD to the new temp branch.

Next, you should compare the current commit (and its history) with the normal branch on which you expected to be working:

git log --graph --decorate --pretty=oneline --abbrev-commit master origin/master temp
git diff master temp
git diff origin/master temp

(You will probably want to experiment with the log options: add -p, leave off --pretty=… to see the whole log message, etc.)

If your new temp branch looks good, you may want to update (e.g.) master to point to it:

git branch -f master temp
git checkout master

(these two commands can be abbreviated as git checkout -B master temp)

You can then delete the temporary branch:

git branch -d temp

Finally, you will probably want to push the reestablished history:

git push origin master

You may need to add --force to the end of this command to push if the remote branch can not be “fast-forwarded” to the new commit (i.e. you dropped, or rewrote some existing commit, or otherwise rewrote some bit of history).

If you were in the middle of a rebase operation you should probably clean it up. You can check whether a rebase was in process by looking for the directory .git/rebase-merge/. You can manually clean up the in-progress rebase by just deleting that directory (e.g. if you no longer remember the purpose and context of the active rebase operation). Usually you would use git rebase --abort, but that does some extra resetting that you probably want to avoid (it moves HEAD back to the original branch and resets it back to the original commit, which will undo some of the work we did above).

Android studio Gradle icon error, Manifest Merger

I tried all the solution mentioned above

in Manifest.xml :

  • add this code in top of your xml file within manifest tag:


  • Then added :

    tools:replace="android:icon,android:theme,android:label,android:name" to the application tag

but none of it worked. I needed to delete a xml file which was situated in


I was testing the application in

Samsung Galaxy 8 with OS version 8.0.0

is it really a solution?

Using sed, how do you print the first 'N' characters of a line?

colrm x

For example, if you need the first 100 characters:

cat file |colrm 101 

It's been around for years and is in most linux's and bsd's (freebsd for sure), usually by default. I can't remember ever having to type apt-get install colrm.

Reading in double values with scanf in c

Use this line of code when scanning the second value: scanf(" %lf", &b); also replace all %ld with %lf.

It's a problem related with input stream buffer. You can also use fflush(stdin); after the first scanning to clear the input buffer and then the second scanf will work as expected. An alternate way is place a getch(); or getchar(); function after the first scanf line.

jQuery xml error ' No 'Access-Control-Allow-Origin' header is present on the requested resource.'

You won't be able to make an ajax call to from a file deployed at due to the same-origin policy.

As the source (aka origin) page and the target URL are at different domains ( and, your code is actually attempting to make a Cross-domain (CORS) request, not an ordinary GET.

In a few words, the same-origin policy says that browsers should only allow ajax calls to services at the same domain of the HTML page.


A page at can only directly request services that are at, like If the service is hosted at another domain (say, the browser won't make the call directly (as you'd expect). Instead, it will try to make a CORS request.

To put it shortly, to perform a (CORS) request* across different domains, your browser:

  • Will include an Origin header in the original request (with the page's domain as value) and perform it as usual; and then
  • Only if the server response to that request contains the adequate headers (Access-Control-Allow-Origin is one of them) allowing the CORS request, the browse will complete the call (almost** exactly the way it would if the HTML page was at the same domain).
    • If the expected headers don't come, the browser simply gives up (like it did to you).

* The above depicts the steps in a simple request, such as a regular GET with no fancy headers. If the request is not simple (like a POST with application/json as content type), the browser will hold it a moment, and, before fulfilling it, will first send an OPTIONS request to the target URL. Like above, it only will continue if the response to this OPTIONS request contains the CORS headers. This OPTIONS call is known as preflight request.
** I'm saying almost because there are other differences between regular calls and CORS calls. An important one is that some headers, even if present in the response, will not be picked up by the browser if they aren't included in the Access-Control-Expose-Headers header.

How to fix it?

Was it just a typo? Sometimes the JavaScript code has just a typo in the target domain. Have you checked? If the page is at it will only make regular calls to! Other URLs, such as or even or are considered different domains by the browser! Yes, if the port is different, then it is a different domain!

Add the headers. The simplest way to enable CORS is by adding the necessary headers (as Access-Control-Allow-Origin) to the server's responses. (Each server/language has a way to do that - check some solutions here.)

Last resort: If you don't have server-side access to the service, you can also mirror it (through tools such as reverse proxies), and include all the necessary headers there.

How can I get the intersection, union, and subset of arrays in Ruby?

Utilizing the fact that you can do set operations on arrays by doing &(intersection), -(difference), and |(union).

Obviously I didn't implement the MultiSet to spec, but this should get you started:

class MultiSet
  attr_accessor :set
  def initialize(set)
    @set = set
  # intersection
  def &(other)
    @set & other.set
  # difference
  def -(other)
    @set - other.set
  # union
  def |(other)
    @set | other.set

x =[1,1,2,2,3,4,5,6])
y =[1,3,5,6])

p x - y # [2,2,4]
p x & y # [1,3,5,6]
p x | y # [1,2,3,4,5,6]

JDK was not found on the computer for NetBeans 6.5

I use the following steps to solve the problem:

First, Make sure

“Run this program in compatibality mode for: Windows XP (Service Pack 3)” and “Run this program as an administrator” are ENABLED.

Run in Command Prompt

C:\Users\{yourusernamehere}\Documents\Downloads\netbeans-6.5-ml-windows.exe –-javahome "C:\Program Files (x86)\Java\jdk1.6.0_18"

What's the UIScrollView contentInset property for?

Great question.

Consider the following example (scroller is a UIScrollView):

float offset = 1000;
[super viewDidLoad];
for (int i=0;i<500; i++) {
    UILabel *label = [[[UILabel alloc] initWithFrame:CGRectMake(i * 100, 50, 95, 100)] autorelease];
    [label setText:[NSString stringWithFormat:@"label %d",i]];
    [self.scroller addSubview:label];
    [self.scroller setContentSize:CGSizeMake(self.view.frame.size.width * 2 + offset, 0)];
    [self.scroller setContentInset:UIEdgeInsetsMake(0, -offset, 0, 0)];

The insets are the ONLY way to force your scroller to have a "window" on the content where you want it. I'm still messing with this sample code, but the idea is there: use the insets to get a "window" on your UIScrollView.

"Connect failed: Access denied for user 'root'@'localhost' (using password: YES)" from php function

From what you've said so far, it sounds like a problem where the MySQL driver in PHP5.3 has trouble connecting to the older MySQL version 4.1. Have a look on

There's a similar question here with some useful answers, Cannot connect to MySQL 4.1+ using old authentication

SELECT `User`, `Host`, Length(`Password`) FROM mysql.user

This will return 16 for accounts with old passwords and 41 for accounts with new passwords (and 0 for accounts with no password at all, you might want to take care of those as well). Either use the user managements tools of the MySQL front end (if there are any) or

SET PASSWORD FOR 'User'@'Host'=PASSWORD('yourpassword');
FLUSH Privileges

Using String Format to show decimal up to 2 places or simple integer

An inelegant way would be:

var my = DoFormat(123.0);

With DoFormat being something like:

public static string DoFormat( double myNumber )
    var s = string.Format("{0:0.00}", myNumber);

    if ( s.EndsWith("00") )
        return ((int)myNumber).ToString();
        return s;

Not elegant but working for me in similar situations in some projects.

How to fill color in a cell in VBA?

Non VBA Solution:

Use Conditional Formatting rule with formula: =ISNA(A1) (to highlight cells with all errors - not only #N/A, use =ISERROR(A1))

enter image description here

VBA Solution:

Your code loops through 50 mln cells. To reduce number of cells, I use .SpecialCells(xlCellTypeFormulas, 16) and .SpecialCells(xlCellTypeConstants, 16)to return only cells with errors (note, I'm using If cell.Text = "#N/A" Then)

Sub ColorCells()
    Dim Data As Range, Data2 As Range, cell As Range
    Dim currentsheet As Worksheet

    Set currentsheet = ActiveWorkbook.Sheets("Comparison")

    With currentsheet.Range("A2:AW" & Rows.Count)
        .Interior.Color = xlNone
        On Error Resume Next
        'select only cells with errors
        Set Data = .SpecialCells(xlCellTypeFormulas, 16)
        Set Data2 = .SpecialCells(xlCellTypeConstants, 16)
        On Error GoTo 0
    End With

    If Not Data2 Is Nothing Then
        If Not Data Is Nothing Then
            Set Data = Union(Data, Data2)
            Set Data = Data2
        End If
    End If

    If Not Data Is Nothing Then
        For Each cell In Data
            If cell.Text = "#N/A" Then
               cell.Interior.ColorIndex = 4
            End If
    End If
End Sub

Note, to highlight cells witn any error (not only "#N/A"), replace following code

If Not Data Is Nothing Then
   For Each cell In Data
       If cell.Text = "#N/A" Then
          cell.Interior.ColorIndex = 3
       End If
End If


If Not Data Is Nothing Then Data.Interior.ColorIndex = 3

UPD: (how to add CF rule through VBA)

Sub test()
    With ActiveWorkbook.Sheets("Comparison").Range("A2:AW" & Rows.Count).FormatConditions
        .Add Type:=xlExpression, Formula1:="=ISNA(A1)"
        .Item(1).Interior.ColorIndex = 3
    End With
End Sub

Remove an item from an IEnumerable<T> collection

Not removing but creating a new List without that element with LINQ:

// remove
users = users.Where(u => u.userId != 123).ToList();

// new list
var modified = users.Where(u => u.userId == 123).ToList();

How do I mock an open used in a with statement (using the Mock framework in Python)?

Sourced from a github snippet to patch read and write functionality in python.

The source link is over here

import configparser
import pytest

simpleconfig = """[section]\nkey = value\n\n"""

def test_monkeypatch_open_read(mockopen):
    filename = 'somefile.txt'
    mockopen.write(filename, simpleconfig)
    parser = configparser.ConfigParser()
    assert parser.sections() == ['section']
def test_monkeypatch_open_write(mockopen):
    parser = configparser.ConfigParser()
    parser.set('section', 'key', 'value')
    filename = 'somefile.txt'
    parser.write(open(filename, 'wb'))
    assert == simpleconfig

How to avoid variable substitution in Oracle SQL Developer with 'trinidad & tobago'

Call this before the query:

set define off;

Alternatively, hacky:

update t set country = 'Trinidad and Tobago' where country = 'trinidad &' || ' tobago';

From Tuning SQL*Plus:

SET DEFINE OFF disables the parsing of commands to replace substitution variables with their values.

Check if a value is in an array (C#)

Something like this?

string[] printer = {"jupiter", "neptune", "pangea", "mercury", "sonic"};

// redefine PrinterSetup this way:
public void PrinterSetup(string[] printer)
    foreach (p in printer.Where(c => c == "jupiter"))

Bootstrap: add margin/padding space between columns

A solution for someone like me when cells got background color


<div class="row">
        <div class="col-6 cssBox">
            a<br />ba<br />ba<br />b
        <div class="col-6 cssBox">
            a<br />b


.cssBox {
  background-color: red;
  margin: 0 10px;
  flex-basis: calc(50% - 20px);

How can I run code on a background thread on Android?

Remember Running Background, Running continuously are two different tasks.

For long-term background processes, Threads aren't optimal with Android. However, here's the code and do it at your own risk...

Remember Service or Thread will run in the background but our task needs to make trigger (call again and again) to get updates, i.e. once the task is completed we need to recall the function for next update.

Timer (periodic trigger), Alarm (Timebase trigger), Broadcast (Event base Trigger), recursion will awake our functions.

public static boolean isRecursionEnable = true;

void runInBackground() {
    if (!isRecursionEnable)
        // Handle not to start multiple parallel threads

    // isRecursionEnable = false; when u want to stop
    // on exception on thread make it true again  
    new Thread(new Runnable() {
        public void run() {
            // DO your work here
            // get the data
            if (activity_is_not_in_background) {
                runOnUiThread(new Runnable() {
                    public void run() {
                        // update UI
            } else {

Using Service: If you launch a Service it will start, It will execute the task, and it will terminate itself. after the task execution. terminated might also be caused by exception, or user killed it manually from settings. START_STICKY (Sticky Service) is the option given by android that service will restart itself if service terminated.

Remember the question difference between multiprocessing and multithreading? Service is a background process (Just like activity without UI), The same way how you launch thread in the activity to avoid load on the main thread (Activity thread), the same way you need to launch threads(or async tasks) on service to avoid load on service.

In a single statement, if you want a run a background continues task, you need to launch a StickyService and run the thread in the service on event base

select2 changing items dynamically

I fix the lack of example's library here:

<link href="" rel="stylesheet"/>
<script src="">

How can I remove leading and trailing quotes in SQL Server?

You can use TRIM('"' FROM '"this "is" a test"') which returns: this "is" a test

multiple classes on single element html

Short Answer



It is a good practice since an element can be a part of different groups, and you may want specific elements to be a part of more than one group. The element can hold an infinite number of classes in HTML5, while in HTML4 you are limited by a specific length.

The following example will show you the use of multiple classes.

The first class makes the text color red.

The second class makes the background-color blue.

See how the DOM Element with multiple classes will behave, it will wear both CSS statements at the same time.

Result: multiple CSS statements in different classes will stack up.

You can read more about CSS Specificity.


.class1 {

.class2 {


<div class="class1">text 1</div>
<div class="class2">text 2</div>
<div class="class1 class2">text 3</div>

Live demo

What is an 'undeclared identifier' error and how do I fix it?

Check if you are importing the same packages in your .m and in your .h Example given: I had this very problem with the init method and it was caused by missing the "#import " on the .m file

Add list to set?

You can't add a list to a set because lists are mutable, meaning that you can change the contents of the list after adding it to the set.

You can however add tuples to the set, because you cannot change the contents of a tuple:

>>> a.add(('f', 'g'))
>>> print a
set(['a', 'c', 'b', 'e', 'd', ('f', 'g')])

Edit: some explanation: The documentation defines a set as an unordered collection of distinct hashable objects. The objects have to be hashable so that finding, adding and removing elements can be done faster than looking at each individual element every time you perform these operations. The specific algorithms used are explained in the Wikipedia article. Pythons hashing algorithms are explained on and pythons __hash__ function in the python reference.

Some facts:

  • Set elements as well as dictionary keys have to be hashable
  • Some unhashable datatypes:
    • list: use tuple instead
    • set: use frozenset instead
    • dict: has no official counterpart, but there are some recipes
  • Object instances are hashable by default with each instance having a unique hash. You can override this behavior as explained in the python reference.

How to get the browser to navigate to URL in JavaScript

Try these:

  1. window.location.href = '';
  2. window.location.assign("");
  3. window.location = '';

For more see this link: other ways to reload the page with JavaScript

Multiple ping script in Python

import subprocess
import os
servers.txt contains ip address in following format
    with open('servers.txt', 'r') as f:
        for ip in f:
            result=subprocess.Popen(["ping", "-c", "1", "-n", "-W", "2",    ip],stdout=f, stderr=f).wait()
            if result:
                print(ip, "inactive")
                print(ip, "active")

jQuery - Follow the cursor with a DIV

You don't need jQuery for this. Here's a simple working example:

<!DOCTYPE html>
        <style type="text/css">
                position: fixed;
                width: 1px;
                height: 1px;
                border-radius: 100%;
                box-shadow: 0 0 10px 10px black;
                top: 49%;
                left: 48.85%;
        <script type="text/javascript">
            window.onload = function(){
                var bsDiv = document.getElementById("box-shadow-div");
                var x, y;
    // On mousemove use event.clientX and event.clientY to set the location of the div to the location of the cursor:
                window.addEventListener('mousemove', function(event){
                    x = event.clientX;
                    y = event.clientY;                    
                    if ( typeof x !== 'undefined' ){
               = x + "px";
               = y + "px";
                }, false);
        <div id="box-shadow-div"></div>

I chose position: fixed; so scrolling wouldn't be an issue.

How to stretch children to fill cross-axis?

  • The children of a row-flexbox container automatically fill the container's vertical space.

  • Specify flex: 1; for a child if you want it to fill the remaining horizontal space:

.wrapper {_x000D_
  display: flex;_x000D_
  flex-direction: row;_x000D_
  align-items: stretch;_x000D_
  width: 100%;_x000D_
  height: 5em;_x000D_
  background: #ccc;_x000D_
.wrapper > .left_x000D_
  background: #fcc;_x000D_
.wrapper > .right_x000D_
  background: #ccf;_x000D_
  flex: 1; _x000D_
<div class="wrapper">_x000D_
  <div class="left">Left</div>_x000D_
  <div class="right">Right</div>_x000D_

  • Specify flex: 1; for both children if you want them to fill equal amounts of the horizontal space:

.wrapper {_x000D_
  display: flex;_x000D_
  flex-direction: row;_x000D_
  align-items: stretch;_x000D_
  width: 100%;_x000D_
  height: 5em;_x000D_
  background: #ccc;_x000D_
.wrapper > div _x000D_
  flex: 1; _x000D_
.wrapper > .left_x000D_
  background: #fcc;_x000D_
.wrapper > .right_x000D_
  background: #ccf;_x000D_
<div class="wrapper">_x000D_
  <div class="left">Left</div>_x000D_
  <div class="right">Right</div>_x000D_

403 Forbidden error when making an ajax Post request in Django framework

Make sure you aren't caching the page/view that your form is showing up on. It could be caching your CSRF_TOKEN. Happened to me!

"CSV file does not exist" for a filename with embedded quotes

What worked for me:

import csv
import pandas as pd
import os

base =os.path.normpath(r"path")

with open(base, 'r') as csvfile:
    readCSV = csv.reader(csvfile, delimiter='|')
    for row in readCSV:
    df = pd.DataFrame(data[1:],columns=data[0][0:15])

This reads in the file , delimit by |, and appends to list which is converted to a pandas df (taking 15 columns)

Set space between divs

Float them both the same way and add the margin of 40px. If you have 2 elements floating opposite ways you will have much less control and the containing element will determine how far apart they are.

    float: left;
    margin-right: 40px;
   float: left;

Codeigniter: does $this->db->last_query(); execute a query?

For me save_queries option was turned off so,

$this->db->save_queries = TRUE; //Turn ON save_queries for temporary use.
$str = $this->db->last_query();
echo $str;

Ref: Can't get result from $this->db->last_query(); codeigniter

Detect if value is number in MySQL

Returns numeric rows

I found the solution with following query and works for me:

SELECT * FROM myTable WHERE col1 > 0;

This query return rows having only greater than zero number column that col1

Returns non numeric rows

if you want to check column not numeric try this one with the trick (!col1 > 0):

SELECT * FROM myTable WHERE !col1 > 0;

Detect home button press in android

This is an old question but it might help someone.

protected void onUserLeaveHint()
    Log.d("onUserLeaveHint","Home button pressed");

According to the documentation, the onUserLeaveHint() method is called when the user clicks the home button OR when something interrupts your application (like an incoming phone call).

This works for me.. :)

How to create composite primary key in SQL Server 2008

  [User_Id] INT NOT NULL,
  [Group_Id] INT NOT NULL


Cannot make file No such file or directory

File.isFile() is false if the file / directory does not exist, so you can't use it to test whether you're trying to create a directory. But that's not the first issue here.

The issue is that the intermediate directories don't exist. You want to call f.mkdirs() first.

Using File.listFiles with FileNameExtensionFilter

With java lambdas (available since java 8) you can simply convert javax.swing.filechooser.FileFilter to in one line.

javax.swing.filechooser.FileFilter swingFilter = new FileNameExtensionFilter("jpeg files", "jpeg"); ioFilter = file -> swingFilter.accept(file);
new File("myDirectory").listFiles(ioFilter);

Npm install cannot find module 'semver'

Just check your preinstall scripts if you have one. Sometimes to restrict the versions of node and npm one needs to run a project.

If that's the case you need to install semver manually via npm install -g semver

How do you find the row count for all your tables in Postgres

Not sure if an answer in bash is acceptable to you, but FWIW...

PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
            SELECT   table_name
            FROM     information_schema.tables
            WHERE    table_type='BASE TABLE'
            AND      table_schema='public'

    PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
                SELECT   '$TABLENAME',
                FROM     $TABLENAME
    eval "$PGCOMMAND"

IOException: The process cannot access the file 'file path' because it is being used by another process

I had the following scenario that was causing the same error:

  • Upload files to the server
  • Then get rid of the old files after they have been uploaded

Most files were small in size, however, a few were large, and so attempting to delete those resulted in the cannot access file error.

It was not easy to find, however, the solution was as simple as Waiting "for the task to complete execution":

using (var wc = new WebClient())
   var tskResult = wc.UploadFileTaskAsync(_address, _fileName);

How do I use a file grep comparison inside a bash if/else statement?

From grep --help, but also see man grep:

Exit status is 0 if any line was selected, 1 otherwise; if any error occurs and -q was not given, the exit status is 2.

if grep --quiet MYSQL_ROLE=master /etc/aws/hosts.conf; then
  echo exists
  echo not found

You may want to use a more specific regex, such as ^MYSQL_ROLE=master$, to avoid that string in comments, names that merely start with "master", etc.

This works because the if takes a command and runs it, and uses the return value of that command to decide how to proceed, with zero meaning true and non-zero meaning false—the same as how other return codes are interpreted by the shell, and the opposite of a language like C.

Should I use typescript? or I can just use ES6?

I've been using Typescript in my current angular project for about a year and a half and while there are a few issues with definitions every now and then the DefinitelyTyped project does an amazing job at keeping up with the latest versions of most popular libraries.

Having said that there is a definite learning curve when transitioning from vanilla JavaScript to TS and you should take into account the ability of you and your team to make that transition. Also if you are going to be using angular 1.x most of the examples you will find online will require you to translate them from JS to TS and overall there are not a lot of resources on using TS and angular 1.x together right now.

If you plan on using angular 2 there are a lot of examples using TS and I think the team will continue to provide most of the documentation in TS, but you certainly don't have to use TS to use angular 2.

ES6 does have some nice features and I personally plan on getting more familiar with it but I would not consider it a production-ready language at this point. Mainly due to a lack of support by current browsers. Of course, you can write your code in ES6 and use a transpiler to get it to ES5, which seems to be the popular thing to do right now.

Overall I think the answer would come down to what you and your team are comfortable learning. I personally think both TS and ES6 will have good support and long futures, I prefer TS though because you tend to get language features quicker and right now the tooling support (in my opinion) is a little better.

How can I get the session object if I have the entity-manager?

'entityManager.unwrap(Session.class)' is used to get session from EntityManager.

public class EmployeeRepository {

  private EntityManager entityManager;

  public Session getSession() {
    Session session = entityManager.unwrap(Session.class);
    return session;



Demo Application link.

What is the difference between ports 465 and 587?

587 vs. 465

These port assignments are specified by the Internet Assigned Numbers Authority (IANA):

  • Port 587: [SMTP] Message submission (SMTP-MSA), a service that accepts submission of email from email clients (MUAs). Described in RFC 6409.
  • Port 465: URL Rendezvous Directory for SSM (entirely unrelated to email)

Historically, port 465 was initially planned for the SMTPS encryption and authentication “wrapper” over SMTP, but it was quickly deprecated (within months, and over 15 years ago) in favor of STARTTLS over SMTP (RFC 3207). Despite that fact, there are probably many servers that support the deprecated protocol wrapper, primarily to support older clients that implemented SMTPS. Unless you need to support such older clients, SMTPS and its use on port 465 should remain nothing more than an historical footnote.

The hopelessly confusing and imprecise term, SSL, has often been used to indicate the SMTPS wrapper and TLS to indicate the STARTTLS protocol extension.

For completeness: Port 25

  • Port 25: Simple Mail Transfer (SMTP-MTA), a service that accepts submission of email from other servers (MTAs or MSAs). Described in RFC 5321.


addID in jQuery?

ID is an attribute, you can set it with the attr function:

$(element).attr('id', 'newID');

I'm not sure what you mean about adding IDs since an element can only have one identifier and this identifier must be unique.

How to set MouseOver event/trigger for border in XAML?

Yes, this is confusing...

According to this blog post, it looks like this is an omission from WPF.

To make it work you need to use a style:

    <Border Name="ClearButtonBorder" Grid.Column="1" CornerRadius="0,3,3,0">
                <Setter Property="Border.Background" Value="Blue"/>
                    <Trigger Property="Border.IsMouseOver" Value="True">
                        <Setter Property="Border.Background" Value="Green" />
        <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="X" />

I guess this problem isn't that common as most people tend to factor out this sort of thing into a style, so it can be used on multiple controls.

Inserting Image Into BLOB Oracle 10g

You cannot access a local directory from pl/sql. If you use bfile, you will setup a directory (create directory) on the server where Oracle is running where you will need to put your images.

If you want to insert a handful of images from your local machine, you'll need a client side app to do this. You can write your own, but I typically use Toad for this. In schema browser, click onto the table. Click the data tab, and hit + sign to add a row. Double click the BLOB column, and a wizard opens. The far left icon will load an image into the blob:

enter image description here

SQL Developer has a similar feature. See the "Load" link below:

enter image description here

If you need to pull images over the wire, you can do it using pl/sql, but its not straight forward. First, you'll need to setup ACL list access (for security reasons) to allow a user to pull over the wire. See this article for more on ACL setup.

Assuming ACL is complete, you'd pull the image like this:

    l_url varchar2(4000) := '';
    l_http_request   UTL_HTTP.req;
    l_http_response  UTL_HTTP.resp;
    l_raw RAW(2000);
    l_blob BLOB;
   -- Important: setup ACL access list first!

    DBMS_LOB.createtemporary(l_blob, FALSE);

    l_http_request  := UTL_HTTP.begin_request(l_url);
    l_http_response := UTL_HTTP.get_response(l_http_request);

  -- Copy the response into the BLOB.
      UTL_HTTP.read_raw(l_http_response, l_raw, 2000);
      DBMS_LOB.writeappend (l_blob, UTL_RAW.length(l_raw), l_raw);
    WHEN UTL_HTTP.end_of_body THEN

  insert into my_pics (pic_id, pic) values (102, l_blob);


Hope that helps.

Ruby: How to post a file via HTTP as multipart/form-data?

Well the solution with NetHttp has a drawback that is when posting big files it loads the whole file into memory first.

After playing a bit with it I came up with the following solution:

class Multipart

  def initialize( file_names )
    @file_names = file_names

  def post( to_url )
    boundary = '----RubyMultipartClient' + rand(1000000).to_s + 'ZZZZZ'

    parts = []
    streams = []
    @file_names.each do |param_name, filepath|
      pos = filepath.rindex('/')
      filename = filepath[pos + 1, filepath.length - pos]
      parts << ( "--" + boundary + "\r\n" +
      "Content-Disposition: form-data; name=\"" + param_name.to_s + "\"; filename=\"" + filename + "\"\r\n" +
      "Content-Type: video/x-msvideo\r\n\r\n")
      stream =, "rb")
      streams << stream
      parts << (stream, File.size(filepath))
    parts << ( "\r\n--" + boundary + "--\r\n" )

    post_stream = parts )

    url = URI.parse( to_url )
    req =
    req.content_length = post_stream.size
    req.content_type = 'multipart/form-data; boundary=' + boundary
    req.body_stream = post_stream
    res =, url.port).start {|http| http.request(req) }

    streams.each do |stream|



class StreamPart
  def initialize( stream, size )
    @stream, @size = stream, size

  def size

  def read ( offset, how_much ) ( how_much )

class StringPart
  def initialize ( str )
    @str = str

  def size

  def read ( offset, how_much )
    @str[offset, how_much]

class MultipartStream
  def initialize( parts )
    @parts = parts
    @part_no = 0;
    @part_offset = 0;

  def size
    total = 0
    @parts.each do |part|
      total += part.size

  def read ( how_much )

    if @part_no >= @parts.size
      return nil;

    how_much_current_part = @parts[@part_no].size - @part_offset

    how_much_current_part = if how_much_current_part > how_much

    how_much_next_part = how_much - how_much_current_part

    current_part = @parts[@part_no].read(@part_offset, how_much_current_part )

    if how_much_next_part > 0
      @part_no += 1
      @part_offset = 0
      next_part = read ( how_much_next_part  )
      current_part + if next_part
      @part_offset += how_much_current_part

Search for highest key/index in an array

This should work fine

$arr = array( 1 => "A", 10 => "B", 5 => "C" );

Adding an img element to a div with javascript




and use the below to set the source

elem.src = 'images/hydrangeas.jpg';

Temporarily switch working copy to a specific Git commit

If you are at a certain branch mybranch, just go ahead and git checkout commit_hash. Then you can return to your branch by git checkout mybranch. I had the same game bisecting a bug today :) Also, you should know about git bisect.

How to get first character of a string in SQL?

SUBSTRING ( MyColumn, 1 , 1 ) for the first character and SUBSTRING ( MyColumn, 1 , 2 ) for the first two.

A method to reverse effect of java String.split()?

For the sake of completeness, I'd like to add that you cannot reverse String#split in general, as it accepts a regular expression.

"hello__world".split("_+"); Yields ["hello", "world"].
"hello_world".split("_+"); Yields ["hello", "world"].

These yield identical results from a different starting point. splitting is not a one-to-one operation, and is thus non-reversible.

This all being said, if you assume your parameter to be a fixed string, not regex, then you can certainly do this using one of the many posted answers.

Change drawable color programmatically


"your image name".setColorFilter("your context".getResources().getColor("color name"));



Most efficient T-SQL way to pad a varchar on the left to a certain length?

Here is how I would normally pad a varchar

WHILE Len(@String) < 8
    SELECT @String = '0' + @String

How can I change UIButton title color?

If you are using Swift, this will do the same:

buttonName.setTitleColor(UIColor.blackColor(), forState: .Normal)

Hope that helps!

Why does git status show branch is up-to-date when changes exist upstream?

What the status is telling you is that you're behind the ref called origin/master which is a local ref in your local repo. In this case that ref happens to track a branch in some remote, called origin, but the status is not telling you anything about the branch on the remote. It's telling you about the ref, which is just a commit ID stored on your local filesystem (in this case, it's typically in a file called .git/refs/remotes/origin/master in your local repo).

git pull does two operations; first it does a git fetch to get up to date with the commits in the remote repo (which updates the origin/master ref in your local repo), then it does a git merge to merge those commits into the current branch.

Until you do the fetch step (either on its own or via git pull) your local repo has no way to know that there are additional commits upstream, and git status only looks at your local origin/master ref.

When git status says up-to-date, it means "up-to-date with the branch that the current branch tracks", which in this case means "up-to-date with the local ref called origin/master". That only equates to "up-to-date with the upstream status that was retrieved last time we did a fetch" which is not the same as "up-to-date with the latest live status of the upstream".

Why does it work this way? Well the fetch step is a potentially slow and expensive network operation. The design of Git (and other distributed version control systems) is to avoid network operations when unnecessary, and is a completely different model to the typical client-server system many people are used to (although as pointed out in the comments below, Git's concept of a "remote tracking branch" that causes confusion here is not shared by all DVCSs). It's entirely possible to use Git offline, with no connection to a centralized server, and the output of git status reflects this.

Creating and switching branches (and checking their status) in Git is supposed to be lightweight, not something that performs a slow network operation to a centralized system. The assumption when designing Git, and the git status output, was that users understand this (too many Git features only make sense if you already know how Git works). With the adoption of Git by lots and lots of users who are not familiar with DVCS this assumption is not always valid.

What's the difference between an Angular component and module

enter image description here

Simplest Explanation:

Module is like a big container containing one or many small containers called Component, Service, Pipe

A Component contains :

  • HTML template or HTML code

  • Code(TypeScript)

  • Service: It is a reusable code that is shared by the Components so that rewriting of code is not required

  • Pipe: It takes in data as input and transforms it to the desired output


What is an example of the simplest possible example?

i realize this post is several years old now, but sometimes certified newbies such as myself need a working example that is totally stripped down to the absolute most simplest form.

every simple example i could find involved http.createServer(). but what if you want to include a bit of magic in an existing webpage? here is the absolute easiest and smallest example i could come up with.

this just returns a string passed from the console UPPERCASED.


var http = require('http');

var app = http.createServer(function(req, res) {

var io = require('').listen(app);

io.on('connection', function(socket) {
    io.emit('Server 2 Client Message', 'Welcome!' );

    socket.on('Client 2 Server Message', function(message)      {
        io.emit('Server 2 Client Message', message.toUpperCase() );     //upcase it



<!doctype html>
        <script type='text/javascript' src='http://localhost:3000/'></script>
        <script type='text/javascript'>
                var socket = io.connect(':3000');
                 // optionally use io('http://localhost:3000');
                 // but make *SURE* it matches the jScript src
                socket.on ('Server 2 Client Message',
                     function(messageFromServer)       {
                        console.log ('server said: ' + messageFromServer);

        <h5>Worlds smallest example to uppercase strings</h5>
        <a href='#' onClick="javascript:socket.emit('Client 2 Server Message', 'return UPPERCASED in the console');">return UPPERCASED in the console</a>
                <br />
                socket.emit('Client 2 Server Message', 'try cut/paste this command in your console!');

to run:

npm init;  // accept defaults
npm  install  http  --save ;
node app.js  &

use something like this port test to ensure your port is open.

now browse to http://localhost/index.html and use your browser console to send messages back to the server.

at best guess, when using http.createServer, it changes the following two lines for you:

<script type='text/javascript' src='/'></script>
var socket = io();

i hope this very simple example spares my fellow newbies some struggling. and please notice that i stayed away from using "reserved word" looking user-defined variable names for my socket definitions.

What is the Maximum Size that an Array can hold?


Assuming you mean System.Array, ie. any normally defined array (int[], etc). This is the maximum number of values the array can hold. The size of each value is only limited by the amount of memory or virtual memory available to hold them.

This limit is enforced because System.Array uses an Int32 as it's indexer, hence only valid values for an Int32 can be used. On top of this, only positive values (ie, >= 0) may be used. This means the absolute maximum upper bound on the size of an array is the absolute maximum upper bound on values for an Int32, which is available in Int32.MaxValue and is equivalent to 2^31, or roughly 2 billion.

On a completely different note, if you're worrying about this, it's likely you're using alot of data, either correctly or incorrectly. In this case, I'd look into using a List<T> instead of an array, so that you are only using as much memory as needed. Infact, I'd recommend using a List<T> or another of the generic collection types all the time. This means that only as much memory as you are actually using will be allocated, but you can use it like you would a normal array.

The other collection of note is Dictionary<int, T> which you can use like a normal array too, but will only be populated sparsely. For instance, in the following code, only one element will be created, instead of the 1000 that an array would create:

Dictionary<int, string> foo = new Dictionary<int, string>();
foo[1000] = "Hello world!";

Using Dictionary also lets you control the type of the indexer, and allows you to use negative values. For the absolute maximal sized sparse array you could use a Dictionary<ulong, T>, which will provide more potential elements than you could possible think about.

Download a file with Android, and showing the progress in a ProgressDialog


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

Using HttpURLConnection


import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

public class DownloadFileUseHttpURLConnection extends Activity {

ProgressBar pb;
Dialog dialog;
int downloadedSize = 0;
int totalSize = 0;
TextView cur_val;
String dwnload_file_path =  
public void onCreate(Bundle savedInstanceState) {

    Button b = (Button) findViewById(;
    b.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {

                new Thread(new Runnable() {
                    public void run() {

void downloadFile(){

    try {
        URL url = new URL(dwnload_file_path);
        HttpURLConnection urlConnection = (HttpURLConnection)   



        //set the path where we want to save the file           
        File SDCardRoot = Environment.getExternalStorageDirectory(); 
        //create a new file, to save the downloaded file 
        File file = new File(SDCardRoot,"downloaded_file.png");

        FileOutputStream fileOutput = new FileOutputStream(file);

        //Stream used for reading the data from the internet
        InputStream inputStream = urlConnection.getInputStream();

        //this is the total size of the file which we are downloading
        totalSize = urlConnection.getContentLength();

        runOnUiThread(new Runnable() {
            public void run() {

        //create a buffer...
        byte[] buffer = new byte[1024];
        int bufferLength = 0;

        while ( (bufferLength = > 0 ) {
            fileOutput.write(buffer, 0, bufferLength);
            downloadedSize += bufferLength;
            // update the progressbar //
            runOnUiThread(new Runnable() {
                public void run() {
                    float per = ((float)downloadedSize/totalSize) *     
                    cur_val.setText("Downloaded " + downloadedSize +  

                    "KB / " + totalSize + "KB (" + (int)per + "%)" );
        //close the output stream when complete //
        runOnUiThread(new Runnable() {
            public void run() {
                // pb.dismiss(); // if you want close it..

    } catch (final MalformedURLException e) {
        showError("Error : MalformedURLException " + e);        
    } catch (final IOException e) {
        showError("Error : IOException " + e);          
    catch (final Exception e) {
        showError("Error : Please check your internet connection " +  

void showError(final String err){
    runOnUiThread(new Runnable() {
        public void run() {
            Toast.makeText(DownloadFileDemo1.this, err,  

void showProgress(String file_path){
    dialog = new Dialog(DownloadFileDemo1.this);
    dialog.setTitle("Download Progress");

    TextView text = (TextView) dialog.findViewById(;
    text.setText("Downloading file from ... " + file_path);
    cur_val = (TextView) dialog.findViewById(;
    cur_val.setText("Starting download...");;

     pb = (ProgressBar)dialog.findViewById(;

android.view.InflateException: Binary XML file line #12: Error inflating class <unknown>

I had the same error on Kitkat which was because i had android:tint on one of the imageViews. It would work fine on Lollipop but crash on Kikkat with Error Inflating class .

Fixed it by using app:tint on the AppCompatImageView which i was dealing with.

How to correctly use Html.ActionLink with ASP.NET MVC 4 Areas

Just to add up my bit:
Remember, you're gonna need to have at least 2 areas in your MVC application to get the routeValues: { area="" } working; otherwise the area value will be used as a query-string parameter and you link will look like this: /?area=

If you don't have at least 2 areas, you can fix this behavior by:
1. editing the default route in RouteConfig.cs like this:

    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { area = "", controller = "Home", action = "Index", id = UrlParameter.Optional }

2. Adding a dummy area to your MVC project.

How to disable the resize grabber of <textarea>?

Just use resize: none

textarea {
   resize: none;

You can also decide to resize your textareas only horizontal or vertical, this way:

textarea { resize: vertical; }

textarea { resize: horizontal; }

Finally, resize: both enables the resize grabber.

Shell - Write variable contents to a file

When you say "copy the contents of a variable", does that variable contain a file name, or does it contain a name of a file?

I'm assuming by your question that $var contains the contents you want to copy into the file:

$ echo "$var" > "$destdir"

This will echo the value of $var into a file called $destdir. Note the quotes. Very important to have "$var" enclosed in quotes. Also for "$destdir" if there's a space in the name. To append it:

$ echo "$var" >> "$destdir"

Get div height with plain JavaScript

The other answers weren't working for me. Here's what I found at w3schools, assuming the div has a height and/or width set.

All you need is height and width to exclude padding.

    var height = document.getElementById('myDiv').style.height;
    var width = document.getElementById('myDiv').style.width;

You downvoters: This answer has helped at least 5 people, judging by the upvotes I've received. If you don't like it, tell me why so I can fix it. That's my biggest pet peeve with downvotes; you rarely tell me why you downvote it.

Foreign key constraints: When to use ON UPDATE and ON DELETE

Addition to @MarkR answer - one thing to note would be that many PHP frameworks with ORMs would not recognize or use advanced DB setup (foreign keys, cascading delete, unique constraints), and this may result in unexpected behaviour.

For example if you delete a record using ORM, and your DELETE CASCADE will delete records in related tables, ORM's attempt to delete these related records (often automatic) will result in error.

Bootstrap - Removing padding or margin when screen size is smaller

I have had this problem occur on sites that used similar formatting and code and I have racked my brain over what was the missing detail that made some of my sites work, and some not.

For Bootstrap 3: The answer for me was not in rewriting css for .container-fluid, .row or resetting margins, the consistent pattern that I realized was the length of longer words were throwing off the design and creating margins.

The solution steps:

  1. Test your page by temporarily deleting sections that contain containers and test your site on small browsers. This will identify your problem container.

  2. You may have a div formatting problem. If you do, fix it. If all is well then:

  3. Identify if you have used long words that are not wrapping. If you cannot change the word (like for tag lines or slogans, etc.)

Solution 1: Format the font to smaller size in your media query for smaller screen (I usually find @media (max-width: 767px) to be sufficient).


Solution 2:

@media (max-width: 767px){

h1, h2, h3 {word-wrap: break-word;}

Can an AJAX response set a cookie?

Also check that your server isn't setting secure cookies on a non http request. Just found out that my ajax request was getting a php session with "secure" set. Because I was not on https it was not sending back the session cookie and my session was getting reset on each ajax request.

angular2: how to copy object into another object

As suggested before, the clean way of deep copying objects having nested objects inside is by using lodash's cloneDeep method.

For Angular, you can do it like this:

Install lodash with yarn add lodash or npm install lodash.

In your component, import cloneDeep and use it:

import * as cloneDeep from 'lodash/cloneDeep';
clonedObject = cloneDeep(originalObject);

It's only 18kb added to your build, well worth for the benefits.

I've also written an article here, if you need more insight on why using lodash's cloneDeep.

Disabling the button after once click

jQuery .one() should not be used with the click event but with the submit event as described below.

 $('input[type=submit]').one('submit', function() {

Virtualbox shared folder permissions

For the truly lazy (no typing, only totally easy copy and paste):

sudo usermod -aG vboxsf $USER

Log out and back in to make the change active.

I know it's a "me too" solution, but I am truly lazy and didn't find any other solution to appeal my innate apathy... :)

what is the use of fflush(stdin) in c programming

it clears stdin buffer before reading. From the man page:

For output streams, fflush() forces a write of all user-space buffered data for the given output or update stream via the stream's underlying write function. For input streams, fflush() discards any buffered data that has been fetched from the underlying file, but has not been consumed by the application.

Note: This is Linux-specific, using fflush() on input streams is undefined by the standard, however, most implementations behave the same as in Linux.