Programs & Examples On #Virtualizingstackpanel

Arranges and virtualizes content on a single line that is oriented either horizontally or vertically.

Adding JPanel to JFrame

do it simply

public class Test{
    public Test(){
    }//end Test()

public void design(){
    JFame f = new JFrame();
    f.setSize(int w, int h);
    JPanel p = new JPanel(); 

public static void main(String[] args){
     EventQueue.invokeLater(new Runnable(){
     public void run(){
             new Test();
         }catch(Exception e){



Typescript react - Could not find a declaration file for module ''react-materialize'. 'path/to/module-name.js' implicitly has an any type

If there is no @types/<package> for the module you are using, you may easily circumvent the issue by adding a // @ts-ignore comment above i.e.

// @ts-ignore
import { Navbar, NavItem } from 'react-materialize';

Alternatively you may create the missing @types/<package> following:

declaration files publishing

DefinitelyTyped how can i contribute

PHP substring extraction. Get the string before the first '/' or the whole string

What about this :

substr($mystring.'/', 0, strpos($mystring, '/'))

Simply add a '/' to the end of mystring so you can be sure there is at least one ;)

PostgreSQL DISTINCT ON with different ORDER BY

Documentation says:

DISTINCT ON ( expression [, ...] ) keeps only the first row of each set of rows where the given expressions evaluate to equal. [...] Note that the "first row" of each set is unpredictable unless ORDER BY is used to ensure that the desired row appears first. [...] The DISTINCT ON expression(s) must match the leftmost ORDER BY expression(s).

Official documentation

So you'll have to add the address_id to the order by.

Alternatively, if you're looking for the full row that contains the most recent purchased product for each address_id and that result sorted by purchased_at then you're trying to solve a greatest N per group problem which can be solved by the following approaches:

The general solution that should work in most DBMSs:

SELECT t1.* FROM purchases t1
    SELECT address_id, max(purchased_at) max_purchased_at
    FROM purchases
    WHERE product_id = 1
    GROUP BY address_id
) t2
ON t1.address_id = t2.address_id AND t1.purchased_at = t2.max_purchased_at
ORDER BY t1.purchased_at DESC

A more PostgreSQL-oriented solution based on @hkf's answer:

  SELECT DISTINCT ON (address_id) *
  FROM purchases 
  WHERE product_id = 1
  ORDER BY address_id, purchased_at DESC
) t
ORDER BY purchased_at DESC

Problem clarified, extended and solved here: Selecting rows ordered by some column and distinct on another

How do I set the default font size in Vim?

For the first one remove the spaces. Whitespace matters for the set command.

set guifont=Monaco:h20

For the second one it should be (the h specifies the height)

set guifont=Monospace:h20

My recommendation for setting the font is to do (if your version supports it)

set guifont=*

This will pop up a menu that allows you to select the font. After selecting the font, type

set guifont?

To show what the current guifont is set to. After that copy that line into your vimrc or gvimrc. If there are spaces in the font add a \ to escape the space.

set guifont=Monospace\ 20

Producing a new line in XSLT

I have found a difference between literal newlines in <xsl:text> and literal newlines using &#xA;.

While literal newlines worked fine in my environment (using both Saxon and the default Java XSLT processor) my code failed when it was executed by another group running in a .NET environment.

Changing to entities (&#xA;) got my file generation code running consistently on both Java and .NET.

Also, literal newlines are vulnerable to being reformatted by IDEs and can inadvertently get lost when the file is maintained by someone 'not in the know'.

MS Access: how to compact current database in VBA

When the user exits the FE attempt to rename the backend MDB preferably with todays date in the name in yyyy-mm-dd format. Ensure you close all bound forms, including hidden forms, and reports before doing this. If you get an error message, oops, its busy so don't bother. If it is successful then compact it back.

See my Backup, do you trust the users or sysadmins? tips page for more info.

Making custom right-click context menus for my web-app

You can watch this tutorial: Make sure the context menu is hidden at first and has a position of absolute. This will ensure that there won't be multiple context menu and useless creation of context menu. The link to the page is placed in the description of the YouTube video.

$(document).bind("contextmenu", function(event){
$("#contextmenu").css({"top": event.pageY +  "px", "left": event.pageX +  "px"}).show();
$(document).bind("click", function(){

How to increment a pointer address and pointer's value?

First, the ++ operator takes precedence over the * operator, and the () operators take precedence over everything else.

Second, the ++number operator is the same as the number++ operator if you're not assigning them to anything. The difference is number++ returns number and then increments number, and ++number increments first and then returns it.

Third, by increasing the value of a pointer, you're incrementing it by the sizeof its contents, that is you're incrementing it as if you were iterating in an array.

So, to sum it all up:

ptr++;    // Pointer moves to the next int position (as if it was an array)
++ptr;    // Pointer moves to the next int position (as if it was an array)
++*ptr;   // The value of ptr is incremented
++(*ptr); // The value of ptr is incremented
++*(ptr); // The value of ptr is incremented
*ptr++;   // Pointer moves to the next int position (as if it was an array). But returns the old content
(*ptr)++; // The value of ptr is incremented
*(ptr)++; // Pointer moves to the next int position (as if it was an array). But returns the old content
*++ptr;   // Pointer moves to the next int position, and then get's accessed, with your code, segfault
*(++ptr); // Pointer moves to the next int position, and then get's accessed, with your code, segfault

As there are a lot of cases in here, I might have made some mistake, please correct me if I'm wrong.


So I was wrong, the precedence is a little more complicated than what I wrote, view it here:

What is the difference between HTML tags <div> and <span>?

The real important difference is already mentioned in Chris' answer. However, the implications won't be obvious for everybody.

As an inline element, <span> may only contain other inline elements. The following code is therefore wrong:

<span><p>This is a paragraph</p></span>

The above code isn't valid. To wrap block-level elements, another block-level element must be used (such as <div>). On the other hand, <div> may only be used in places where block-level elements are legal.

Furthermore, these rules are fixed in (X)HTML and they are not altered by the presence of CSS rules! So the following codes are also wrong!

<span style="display: block"><p>Still wrong</p></span>
<span><p style="display: inline">Just as wrong</p></span>

Difference between jar and war in Java

A JAR file extension is .jar and is created with jar command from command prompt (like javac command is executed). Generally, a JAR file contains Java related resources like libraries, classes etc.JAR file is like winzip file except that Jar files are platform independent.

A WAR file is simply a JAR file but contains only Web related Java files like Servlets, JSP, HTML.

To execute a WAR file, a Web server or Web container is required, for example, Tomcat or Weblogic or Websphere. To execute a JAR file, simple JDK is enough.

How to open a file / browse dialog using javascript?

you can't use directly, but you can call this in other element click event.


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


var botton = document.querySelector('button');
var input = document.querySelector('input');
botton.addEventListener('click', function (e) {;

this tell you Using hidden file input elements using the click() method

Python 2.7 getting user input and manipulating as string without quotations

The function input will also evaluate the data it just read as python code, which is not really what you want.

The generic approach would be to treat the user input (from sys.stdin) like any other file. Try

import sys

If you want to keep it short, you can use raw_input which is the same as input but omits the evaluation.

How can I format a number into a string with leading zeros?

Since nobody has yet mentioned this, if you are using C# version 6 or above (i.e. Visual Studio 2015) then you can use string interpolation to simplify your code. So instead of using string.Format(...), you can just do this:

Key = $"{i:D2}";

Error: Argument is not a function, got undefined

Could it be as simple as enclosing your asset in " " and whatever needs quotes on the inside with ' '?

<link rel="stylesheet" media="screen" href=""stylesheets/main.css")">


<link rel="stylesheet" media="screen" href="'stylesheets/main.css')">

That could be causing some problems with parsing

Can I use a binary literal in C or C++?

You can also use inline assembly like this:

int i;

__asm {
    mov eax, 00000000000000000000000000000000b
    mov i,   eax

std::cout << i;

Okay, it might be somewhat overkill, but it works.

Convert MySql DateTime stamp into JavaScript's Date format

I think I may have found a simpler way, that nobody mentioned.

A MySQL DATETIME column can be converted to a unix timestamp through:

SELECT unix_timestamp(my_datetime_column) as stamp ...

We can make a new JavaScript Date object by using the constructor that requires milliseconds since the epoch. The unix_timestamp function returns seconds since the epoch, so we need to multiply by 1000:

SELECT unix_timestamp(my_datetime_column) * 1000 as stamp ...

The resulting value can be used directly to instantiate a correct Javascript Date object:

var myDate = new Date(<?=$row['stamp']?>);

Hope this helps.

int to hex string

Try C# string interpolation introduced in C# 6:

var id = 100;
var hexid = $"0x{id:X}";

hexid value:


Class is not abstract and does not override abstract method

If you're trying to take advantage of polymorphic behavior, you need to ensure that the methods visible to outside classes (that need polymorphism) have the same signature. That means they need to have the same name, number and order of parameters, as well as the parameter types.

In your case, you might do better to have a generic draw() method, and rely on the subclasses (Rectangle, Ellipse) to implement the draw() method as what you had been thinking of as "drawEllipse" and "drawRectangle".

Upgrading Node.js to latest version

my 2c:

I tried both with n and with nvm on Linux Ubuntu 12.04 LTS, in order to update node from v0.8.25 to v0.10.22.

The first one was successfully completed, but the command 'which node' resulted in the old v0.8.25.
The second one was successfully completed and the same command resulted in v.0.10.22.

How to change font-color for disabled input?

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

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

How do I add a Fragment to an Activity with a programmatically created content view

This may help you

Defining a Fragment

create xml file for fragment view fragment_abc.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
android:layout_width="match_parent" android:layout_height="match_parent"
android:orientation="vertical" >

    android:text="TextView" />

    android:text="Button" />


create fragment


public class FooFragment extends Fragment {
// The onCreateView method is called when Fragment should create its View object hierarchy,
// either dynamically or via XML layout inflation. 

public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle 
savedInstanceState) {
    // Defines the xml file for the fragment
    return inflater.inflate(R.layout.fragment_abc, parent, false);

// This event is triggered soon after onCreateView().
// Any view setup should occur here.  E.g., view lookups and attaching view listeners.
public void onViewCreated(View view, Bundle savedInstanceState) {
    // Setup any handles to view objects here
    // EditText etFoo = (EditText) view.findViewById(;

Add frameLayout in your activity


now in activity, add following method

protected void setFragment() {
    // Begin the transaction
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    // Replace the contents of the container with the new fragment
    ft.replace(, new ABCFragment());
    // or ft.add(, new ABCFragment());
    // Complete the changes added above

reference :

How to create a HTML Table from a PHP array?

Here is my answer.

function array2Html($array, $table = true)
    $out = '';
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            if (!isset($tableHeader)) {
                $tableHeader =
                    '<th>' .
                    implode('</th><th>', array_keys($value)) .
            $out .= '<tr>';
            $out .= array2Html($value, false);
            $out .= '</tr>';
        } else {
            $out .= "<td>$value</td>";

    if ($table) {
        return '<table>' . $tableHeader . $out . '</table>';
    } else {
        return $out;

However, your table headers have to be a part of the array, which is pretty common when it comes from a database. e.g.

$shop = array(
        'title' => 'rose',
        'price' => 1.25,
        'number' => 15,
        'title' => 'daisy',
        'price' => 0.75,
        'number' => 25,
        'title' => 'orchid',
        'price' => 1.15,
        'number' => 7,

print arrayToHtml($shop);

Hope it helps ;)

Select distinct using linq

myList.GroupBy(i => => group.First())

Pass arguments into C program from command line

Take a look at the getopt library; it's pretty much the gold standard for this sort of thing.

Authentication issue when debugging in VS2013 - iis express

F4 doesn't always bring me to this panel. Besides, it is often said that a picture is worth a thousand words.

enter image description here

Purpose of ESI & EDI registers?

SI = Source Index
DI = Destination Index

As others have indicated, they have special uses with the string instructions. For real mode programming, the ES segment register must be used with DI and DS with SI as in

movsb  es:di, ds:si

SI and DI can also be used as general purpose index registers. For example, the C source code

srcp [srcidx++] = argv [j];

compiles into

8B550C         mov    edx,[ebp+0C]
8B0C9A         mov    ecx,[edx+4*ebx]
894CBDAC       mov    [ebp+4*edi-54],ecx
47             inc    edi

where ebp+12 contains argv, ebx is j, and edi has srcidx. Notice the third instruction uses edi mulitplied by 4 and adds ebp offset by 0x54 (the location of srcp); brackets around the address indicate indirection.

Though I can't remember where I saw it, but this confirms most of it, and this (slide 17) others:

AX = accumulator
DX = double word accumulator
CX = counter
BX = base register

They look like general purpose registers, but there are a number of instructions which (unexpectedly?) use one of them—but which one?—implicitly.

XML parsing of a variable string in JavaScript

Apparently jQuery now provides jQuery.parseXML as of version 1.5

jQuery.parseXML( data ) Returns: XMLDocument

Converting unix timestamp string to readable date

You can convert the current time like this


To convert a date in string to different formats.

import datetime,time

def createDateObject(str_date,strFormat="%Y-%m-%d"):    
    timeStamp = time.mktime(time.strptime(str_date,strFormat))
    return datetime.datetime.fromtimestamp(timeStamp)

def FormatDate(objectDate,strFormat="%Y-%m-%d"):
    return objectDate.strftime(strFormat)

print FormatDate(o,'%d-%m-%Y')

Output 03-03-2013

In OS X Lion, LANG is not set to UTF-8, how to fix it?

I recently had the same issue on OS X Sierra with bash shell, and thanks to answers above I only had to edit the file


and append those lines

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8

What does numpy.random.seed(0) do?

All the random numbers generated after setting particular seed value are same across all the platforms/systems.

Popup Message boxes

Use the following library: import javax.swing.JOptionPane;

Input at the top of the code-line. You must only add this, because the other things is done correctly!

Using Jquery Ajax to retrieve data from Mysql

This answer was for @
Neha Gandhi but I modified it for  people who use pdo and mysqli sing mysql functions are not supported. Here is the new answer 

<!--Save this as index.php-->
      <script src="//"></script>
        <script src="//"></script>
     <script type="text/javascript">
     $(document).ready(function() {
        $("#display").click(function() {                
          $.ajax({    //create an ajax request to display.php
            type: "GET",
            url: "display.php",             
            dataType: "html",   //expect html to be returned                
            success: function(response){                    
    <h3 align="center">Manage Student Details</h3>
    <table border="1" align="center">
           <td> <input type="button" id="display" value="Display All Data" /> </td>
    <div id="responsecontainer" align="center">

// save this as display.php

    // show errors 
ini_set('display_errors', 1);
    //errors ends here 
// call the page for connecting to the db
$get_member =" SELECT 
empid, lastName, firstName, email, usercode, companyid, userid, jobTitle, cell, employeetype, address ,initials   FROM employees";
$user_coder1 = $con->prepare($get_member);
$user_coder1 ->execute();

echo "<table border='1' >
<td align=center> <b>Roll No</b></td>
<td align=center><b>Name</b></td>
<td align=center><b>Address</b></td>
<td align=center><b>Stream</b></td></td>
<td align=center><b>Status</b></td>";

while($row =$user_coder1->fetch(PDO::FETCH_ASSOC)){
$firstName = $row['firstName'];
$empid = $row['empid'];
$lastName =    $row['lastName'];
$cell =    $row['cell'];

    echo "<tr>";
    echo "<td align=center>$firstName</td>";
    echo "<td align=center>$empid</td>";
    echo "<td align=center>$lastName </td>";
    echo "<td align=center>$cell</td>";
    echo "<td align=center>$cell</td>";
    echo "</tr>";
echo "</table>";

// save this as dbconnector.php
function connected_Db(){

    $dsn  = 'mysql:host=localhost;dbname=mydb;charset=utf8';
    $opt  = array(
    #echo "Yes we are connected";
    return new PDO($dsn,'username','password', $opt);
$con = connected_Db();
//echo "me  is connected ";
else {
//echo "Connection faid ";

Qt Creator color scheme

Here is a theme that I copied all the important parts of the Visual Studio 2013 dark theme.

**Update 08/Sep/15 - Qt Creator 3.5.1/Qt 5.5.1 might have fixed the rest of Qt not being dark properly and hard to read.

How to convert a factor to integer\numeric without loss of information?

It is possible only in the case when the factor labels match the original values. I will explain it with an example.

Assume the data is vector x:

x <- c(20, 10, 30, 20, 10, 40, 10, 40)

Now I will create a factor with four labels:

f <- factor(x, levels = c(10, 20, 30, 40), labels = c("A", "B", "C", "D"))

1) x is with type double, f is with type integer. This is the first unavoidable loss of information. Factors are always stored as integers.

> typeof(x)
[1] "double"
> typeof(f)
[1] "integer"

2) It is not possible to revert back to the original values (10, 20, 30, 40) having only f available. We can see that f holds only integer values 1, 2, 3, 4 and two attributes - the list of labels ("A", "B", "C", "D") and the class attribute "factor". Nothing more.

> str(f)
 Factor w/ 4 levels "A","B","C","D": 2 1 3 2 1 4 1 4
> attributes(f)
[1] "A" "B" "C" "D"

[1] "factor"

To revert back to the original values we have to know the values of levels used in creating the factor. In this case c(10, 20, 30, 40). If we know the original levels (in correct order), we can revert back to the original values.

> orig_levels <- c(10, 20, 30, 40)
> x1 <- orig_levels[f]
> all.equal(x, x1)
[1] TRUE

And this will work only in case when labels have been defined for all possible values in the original data.

So if you will need the original values, you have to keep them. Otherwise there is a high chance it will not be possible to get back to them only from a factor.

Access blocked by CORS policy: Response to preflight request doesn't pass access control check

You can just create the required CORS configuration as a bean. As per the code below this will allow all requests coming from any origin. This is good for development but insecure. Spring Docs

WebMvcConfigurer corsConfigurer() {
    return new WebMvcConfigurer() {
        void addCorsMappings(CorsRegistry registry) {

Upload files with FTP using PowerShell

There are some other ways too. I have used the following script:

$File = "D:\Dev\";
$ftp = "ftp://username:[email protected]/pub/incoming/";

Write-Host -Object "ftp url: $ftp";

$webclient = New-Object -TypeName System.Net.WebClient;
$uri = New-Object -TypeName System.Uri -ArgumentList $ftp;

Write-Host -Object "Uploading $File...";

$webclient.UploadFile($uri, $File);

And you could run a script against the windows FTP command line utility using the following command

ftp -s:script.txt 

(Check out this article)

The following question on SO also answers this: How to script FTP upload and download?

How do I publish a UDP Port on Docker?

Use the -p flag and add /udp suffix to the port number.

-p 53160:53160/udp

Full command

sudo docker run -p 53160:53160 \
    -p 53160:53160/udp -p 58846:58846 \ 
    -p 8112:8112 -t -i aostanin/deluge /

If you're running boot2docker on Mac, be sure to forward the same ports on boot2docker to your local machine.

You can also document that your container needs to receive UDP using EXPOSE in The Dockerfile (EXPOSE does not publish the port):

EXPOSE 8285/udp

Here is a link with more Docker Networking info covered in the container docs: (Courtesy of Old Pro in the comments)

Equivalent of jQuery .hide() to set visibility: hidden

An even simpler way to do this is to use jQuery's toggleClass() method


.newClass{visibility: hidden}


<a href="#" class=trigger>Trigger Element </a>
<div class="hidden_element">Some Content</div>



Python Binomial Coefficient

This question is old but as it comes up high on search results I will point out that scipy has two functions for computing the binomial coefficients:

  1. scipy.special.binom()
  2. scipy.special.comb()

    import scipy.special
    # the two give the same results 
    scipy.special.binom(10, 5)
    # 252.0
    scipy.special.comb(10, 5)
    # 252.0
    scipy.special.binom(300, 150)
    # 9.375970277281882e+88
    scipy.special.comb(300, 150)
    # 9.375970277281882e+88
    # ...but with `exact == True`
    scipy.special.comb(10, 5, exact=True)
    # 252
    scipy.special.comb(300, 150, exact=True)
    # 393759702772827452793193754439064084879232655700081358920472352712975170021839591675861424

Note that scipy.special.comb(exact=True) uses Python integers, and therefore it can handle arbitrarily large results!

Speed-wise, the three versions give somewhat different results:

num = 300

%timeit [[scipy.special.binom(n, k) for k in range(n + 1)] for n in range(num)]
# 52.9 ms ± 107 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)

%timeit [[scipy.special.comb(n, k) for k in range(n + 1)] for n in range(num)]
# 183 ms ± 814 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)each)

%timeit [[scipy.special.comb(n, k, exact=True) for k in range(n + 1)] for n in range(num)]
# 180 ms ± 649 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)

(and for n = 300, the binomial coefficients are too large to be represented correctly using float64 numbers, as shown above).

Why does Eclipse complain about @Override on interface methods?

I understood your problem, change your jdk from your jdk to greaterthan 1.5

Getting the client IP address: REMOTE_ADDR, HTTP_X_FORWARDED_FOR, what else could be useful?

If you're behind a proxy, you should use X-Forwarded-For:

It is an IETF draft standard with wide support:

The X-Forwarded-For field is supported by most proxy servers, including Squid, Apache mod_proxy, Pound, HAProxy, Varnish cache, IronPort Web Security Appliance, AVANU WebMux, ArrayNetworks, Radware's AppDirector and Alteon ADC, ADC-VX, and ADC-VA, F5 Big-IP, Blue Coat ProxySG, Cisco Cache Engine, McAfee Web Gateway, Phion Airlock, Finjan's Vital Security, NetApp NetCache, jetNEXUS, Crescendo Networks' Maestro, Web Adjuster and Websense Web Security Gateway.

If not, here are a couple other common headers I've seen:

Set default value of javascript object attributes

Simplest of all Solutions:

dict = {'first': 1,
        'second': 2,
        'third': 3}


dict['last'] || 'Excluded'

will return 'Excluded', which is the default value.

Parse Error: Adjacent JSX elements must be wrapped in an enclosing tag

Import view and wrap in View. Wrapping in a div did not work for me.

import { View } from 'react-native';
    render() {
      return (

android View not attached to window manager

I am using a custom static class which makes- shows and hides a dialog. this class is being used by other activities too not only one activiy. Now the problem you described also appeared to me and i have stayed overnight to find a solution..

Finally i present you the solution!

if you want to show or dismiss a dialog and you dont know which activity initiated the dialog in order to touch it then the following code is for you..

 static class CustomDialog{

     public static void initDialog(){
         //init code

      public static void showDialog(){
         //init code for show dialog

     /****This is your Dismiss dialog code :D*******/
     public static void dismissProgressDialog(Context context) {                
            //Can't touch other View of other Activiy..
            if ( (progressdialog != null) && progressdialog.isShowing()) {

                //is it the same context from the caller ?
                Log.w("ProgressDIalog dismiss", "the dialog is from"+progressdialog.getContext());

                Class caller_context= context.getClass();
                Activity call_Act = (Activity)context;
                Class progress_context= progressdialog.getContext().getClass();

                Boolean is_act= ( (progressdialog.getContext()) instanceof  Activity )?true:false;
                Boolean is_ctw= ( (progressdialog.getContext()) instanceof  ContextThemeWrapper )?true:false;

                if (is_ctw) {
                    ContextThemeWrapper cthw=(ContextThemeWrapper) progressdialog.getContext();
                    Boolean is_same_acivity_with_Caller= ((Activity)(cthw).getBaseContext() ==  call_Act )?true:false;

                    if (is_same_acivity_with_Caller){
                        progressdialog = null;
                    else {
                        Log.e("ProgressDIalog dismiss", "the dialog is NOT from the same context! Can't touch.."+((Activity)(cthw).getBaseContext()).getClass());
                        progressdialog = null;



Rounded Corners Image in Flutter

Try this instead, worked for me:

  width: 100.0,
  height: 150.0,
  decoration: BoxDecoration(
    image: DecorationImage(
        fit: BoxFit.cover, image: NetworkImage('Path to your image')),
    borderRadius: BorderRadius.all(Radius.circular(8.0)),
    color: Colors.redAccent,

Using variables inside strings

This functionality is not built-in to C# 5 or below.
Update: C# 6 now supports string interpolation, see newer answers.

The recommended way to do this would be with String.Format:

string name = "Scott";
string output = String.Format("Hello {0}", name);

However, I wrote a small open-source library called SmartFormat that extends String.Format so that it can use named placeholders (via reflection). So, you could do:

string name = "Scott";
string output = Smart.Format("Hello {name}", new{name}); // Results in "Hello Scott".

Hope you like it!

Is there any way to change input type="date" format?

After having read lots of discussions, I have prepared a simple solution but I don't want to use lots of Jquery and CSS, just some javascript.

HTML Code:

<input type="date" id="dt" onchange="mydate1();" hidden/>
<input type="text" id="ndt"  onclick="mydate();" hidden />
<input type="button" Value="Date" onclick="mydate();" />

CSS Code:

#dt {
  text-indent: -500px;
  height: 25px;
  width: 200px;

Javascript Code :

function mydate() {
  document.getElementById("dt").hidden = false;
  document.getElementById("ndt").hidden = true;

function mydate1() {
  d = new Date(document.getElementById("dt").value);
  dt = d.getDate();
  mn = d.getMonth();
  yy = d.getFullYear();
  document.getElementById("ndt").value = dt + "/" + mn + "/" + yy
  document.getElementById("ndt").hidden = false;
  document.getElementById("dt").hidden = true;


enter image description here

How to test enum types?

For enums, I test them only when they actually have methods in them. If it's a pure value-only enum like your example, I'd say don't bother.

But since you're keen on testing it, going with your second option is much better than the first. The problem with the first is that if you use an IDE, any renaming on the enums would also rename the ones in your test class.

Logarithmic returns in pandas dataframe

Single line, and only calculating logs once. First convert to log-space, then take the 1-period diff.


In earlier versions of numpy:


Extracting text from HTML file using Python

I am achieving it something like this.

>>> import requests
>>> url = ""
>>> res = requests.get(url)
>>> text = res.text

addID in jQuery?

Like this :

var id = $('').attr('id');
$('').attr('id', id + ' id_adding');
  1. get actual ID
  2. put actuel ID and add the new one

Swift: Display HTML data in a label or textView

Here is a Swift 3 version:

private func getHtmlLabel(text: String) -> UILabel {
    let label = UILabel()
    label.numberOfLines = 0
    label.lineBreakMode = .byWordWrapping
    label.attributedString = stringFromHtml(string: text)
    return label

private func stringFromHtml(string: String) -> NSAttributedString? {
    do {
        let data = String.Encoding.utf8, allowLossyConversion: true)
        if let d = data {
            let str = try NSAttributedString(data: d,
                                             options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType],
                                             documentAttributes: nil)
            return str
    } catch {
    return nil

I found issues with some of the other answers here and it took me a bit to get this right. I set the line break mode and number of lines so that the label sized appropriately when the HTML spanned multiple lines.

How can I access the MySQL command line with XAMPP for Windows?

To access the mysql command in Windows without manually changing directories, do this:

  • Go to Control Panel > System > Advanced system settings.
  • System Properties will appear.
  • Click on the 'Advanced' tab.
  • Click 'Environment Variables'.
  • Under System Variables, locate 'Path' and click Edit.
  • Append the path to your MySQL installation to the end of the exisiting 'Variable value'. Example:


    or, if you prefer

  • Finally, open a new command prompt to make this change take effect.

Note that MySQL's documentation on Setting Environment Variables has little to say about handling this in Windows.

Running Java gives "Error: could not open `C:\Program Files\Java\jre6\lib\amd64\jvm.cfg'"

I had the same problem in Eclipse and I fixed it by changing the JRE from 64 bit to 32 bit:

Window > Preferences > Java > Installed JREs > Add... > Next > Directory > select "C:\Program Files (x86)\Java\jre1.8.0_65" instead of "C:\Program Files\Java\jre1.8.0_60"

REST API error code 500 handling

The real question is why does it generate a 500 error. If it is related to any input parameters, then I would argue that it should be handled internally and returned as a 400 series error. Generally a 400, 404 or 406 would be appropriate to reflect bad input since the general convention is that a RESTful resource is uniquely identified by the URL and a URL that cannot generate a valid response is a bad request (400) or similar.

If the error is caused by anything other than the inputs explicitly or implicitly supplied by the request, then I would say a 500 error is likely appropriate. So a failed database connection or other unpredictable error is accurately represented by a 500 series error.

Javascript: Call a function after specific time period

You can use JavaScript Timing Events to call function after certain interval of time:

This shows the alert box after 3 seconds:


You can use two method of time event in javascript.i.e.

  1. setInterval(): executes a function, over and over again, at specified time intervals
  2. setTimeout() : executes a function, once, after waiting a specified number of milliseconds

POST request with JSON body

// Example API call
$data = array(array (
    "REGION" => "MUMBAI",
    "LOCATION" => "NA",
    "STORE" => "AMAZON"));
// json encode data
$authToken = "xxxxxxxxxx";
$data_string = json_encode($data); 
// set up the curl resource
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "");   
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Content-Length: ' . strlen($data_string) ,
    'API-TOKEN-KEY:'.$authToken ));   // API-TOKEN-KEY is keyword so change according to ur key word. like authorization 
// execute the request
$output = curl_exec($ch);
//echo $output;
// Check for errors
if($output === FALSE){
echo($output) . PHP_EOL;
// close curl resource to free up system resources

What's the shebang/hashbang (#!) in Facebook and new Twitter URLs for?

I would be very careful if you are considering adopting this hashbang convention.

Once you hashbang, you can’t go back. This is probably the stickiest issue. Ben’s post put forward the point that when pushState is more widely adopted then we can leave hashbangs behind and return to traditional URLs. Well, fact is, you can’t. Earlier I stated that URLs are forever, they get indexed and archived and generally kept around. To add to that, cool URLs don’t change. We don’t want to disconnect ourselves from all the valuable links to our content. If you’ve implemented hashbang URLs at any point then want to change them without breaking links the only way you can do it is by running some JavaScript on the root document of your domain. Forever. It’s in no way temporary, you are stuck with it.

You really want to use pushState instead of hashbangs, because making your URLs ugly and possibly broken -- forever -- is a colossal and permanent downside to hashbangs.

How to make an embedded video not autoplay

I had the same problem and came across this post. Nothing worked. After randomly playing around, I found that <embed ........ play="false"> stopped it from playing automatically. I now have the problem that I can't get a controller to appear, so can't start the movie! :S

How to dynamic new Anonymous Class?

Anonymous types are just regular types that are implicitly declared. They have little to do with dynamic.

Now, if you were to use an ExpandoObject and reference it through a dynamic variable, you could add or remove fields on the fly.


Sure you can: just cast it to IDictionary<string, object>. Then you can use the indexer.

You use the same casting technique to iterate over the fields:

dynamic employee = new ExpandoObject();
employee.Name = "John Smith";
employee.Age = 33;

foreach (var property in (IDictionary<string, object>)employee)
    Console.WriteLine(property.Key + ": " + property.Value);
// This code example produces the following output:
// Name: John Smith
// Age: 33

The above code and more can be found by clicking on that link.

Prevent text selection after double click

To prevent text selection ONLY after a double click:

You could use MouseEvent#detail property. For mousedown or mouseup events, it is 1 plus the current click count.

document.addEventListener('mousedown', function (event) {
  if (event.detail > 1) {
    // of course, you still do not know what you prevent here...
    // You could also check event.ctrlKey/event.shiftKey/event.altKey
    // to not prevent something useful.
}, false);


How to measure time in milliseconds using ANSI C?

Implementing a portable solution

As it was already mentioned here that there is no proper ANSI solution with sufficient precision for the time measurement problem, I want to write about the ways how to get a portable and, if possible, a high-resolution time measurement solution.

Monotonic clock vs. time stamps

Generally speaking there are two ways of time measurement:

  • monotonic clock;
  • current (date)time stamp.

The first one uses a monotonic clock counter (sometimes it is called a tick counter) which counts ticks with a predefined frequency, so if you have a ticks value and the frequency is known, you can easily convert ticks to elapsed time. It is actually not guaranteed that a monotonic clock reflects the current system time in any way, it may also count ticks since a system startup. But it guarantees that a clock is always run up in an increasing fashion regardless of the system state. Usually the frequency is bound to a hardware high-resolution source, that's why it provides a high accuracy (depends on hardware, but most of the modern hardware has no problems with high-resolution clock sources).

The second way provides a (date)time value based on the current system clock value. It may also have a high resolution, but it has one major drawback: this kind of time value can be affected by different system time adjustments, i.e. time zone change, daylight saving time (DST) change, NTP server update, system hibernation and so on. In some circumstances you can get a negative elapsed time value which can lead to an undefined behavior. Actually this kind of time source is less reliable than the first one.

So the first rule in time interval measuring is to use a monotonic clock if possible. It usually has a high precision, and it is reliable by design.

Fallback strategy

When implementing a portable solution it is worth to consider a fallback strategy: use a monotonic clock if available and fallback to time stamps approach if there is no monotonic clock in the system.


There is a great article called Acquiring high-resolution time stamps on MSDN about time measurement on Windows which describes all the details you may need to know about software and hardware support. To acquire a high precision time stamp on Windows you should:

  • query a timer frequency (ticks per second) with QueryPerformanceFrequency:

    LARGE_INTEGER tcounter;
    LARGE_INTEGER freq;    
    if (QueryPerformanceFrequency (&tcounter) != 0)
        freq = tcounter.QuadPart;

    The timer frequency is fixed on the system boot so you need to get it only once.

  • query the current ticks value with QueryPerformanceCounter:

    LARGE_INTEGER tcounter;
    LARGE_INTEGER tick_value;
    if (QueryPerformanceCounter (&tcounter) != 0)
        tick_value = tcounter.QuadPart;
  • scale the ticks to elapsed time, i.e. to microseconds:

    LARGE_INTEGER usecs = (tick_value - prev_tick_value) / (freq / 1000000);

According to Microsoft you should not have any problems with this approach on Windows XP and later versions in most cases. But you can also use two fallback solutions on Windows:

  • GetTickCount provides the number of milliseconds that have elapsed since the system was started. It wraps every 49.7 days, so be careful in measuring longer intervals.
  • GetTickCount64 is a 64-bit version of GetTickCount, but it is available starting from Windows Vista and above.

OS X (macOS)

OS X (macOS) has its own Mach absolute time units which represent a monotonic clock. The best way to start is the Apple's article Technical Q&A QA1398: Mach Absolute Time Units which describes (with the code examples) how to use Mach-specific API to get monotonic ticks. There is also a local question about it called clock_gettime alternative in Mac OS X which at the end may leave you a bit confused what to do with the possible value overflow because the counter frequency is used in the form of numerator and denominator. So, a short example how to get elapsed time:

  • get the clock frequency numerator and denominator:

    #include <mach/mach_time.h>
    #include <stdint.h>
    static uint64_t freq_num   = 0;
    static uint64_t freq_denom = 0;
    void init_clock_frequency ()
        mach_timebase_info_data_t tb;
        if (mach_timebase_info (&tb) == KERN_SUCCESS && tb.denom != 0) {
            freq_num   = (uint64_t) tb.numer;
            freq_denom = (uint64_t) tb.denom;

    You need to do that only once.

  • query the current tick value with mach_absolute_time:

    uint64_t tick_value = mach_absolute_time ();
  • scale the ticks to elapsed time, i.e. to microseconds, using previously queried numerator and denominator:

    uint64_t value_diff = tick_value - prev_tick_value;
    /* To prevent overflow */
    value_diff /= 1000;
    value_diff *= freq_num;
    value_diff /= freq_denom;

    The main idea to prevent an overflow is to scale down the ticks to desired accuracy before using the numerator and denominator. As the initial timer resolution is in nanoseconds, we divide it by 1000 to get microseconds. You can find the same approach used in Chromium's time_mac.c. If you really need a nanosecond accuracy consider reading the How can I use mach_absolute_time without overflowing?.

Linux and UNIX

The clock_gettime call is your best way on any POSIX-friendly system. It can query time from different clock sources, and the one we need is CLOCK_MONOTONIC. Not all systems which have clock_gettime support CLOCK_MONOTONIC, so the first thing you need to do is to check its availability:

  • if _POSIX_MONOTONIC_CLOCK is defined to a value >= 0 it means that CLOCK_MONOTONIC is avaiable;
  • if _POSIX_MONOTONIC_CLOCK is defined to 0 it means that you should additionally check if it works at runtime, I suggest to use sysconf:

    #include <unistd.h>
    if (sysconf (_SC_MONOTONIC_CLOCK) > 0) {
        /* A monotonic clock presents */
  • otherwise a monotonic clock is not supported and you should use a fallback strategy (see below).

Usage of clock_gettime is pretty straight forward:

  • get the time value:

    #include <time.h>
    #include <sys/time.h>
    #include <stdint.h>
    uint64_t get_posix_clock_time ()
        struct timespec ts;
        if (clock_gettime (CLOCK_MONOTONIC, &ts) == 0)
            return (uint64_t) (ts.tv_sec * 1000000 + ts.tv_nsec / 1000);
            return 0;

    I've scaled down the time to microseconds here.

  • calculate the difference with the previous time value received the same way:

    uint64_t prev_time_value, time_value;
    uint64_t time_diff;
    /* Initial time */
    prev_time_value = get_posix_clock_time ();
    /* Do some work here */
    /* Final time */
    time_value = get_posix_clock_time ();
    /* Time difference */
    time_diff = time_value - prev_time_value;

The best fallback strategy is to use the gettimeofday call: it is not a monotonic, but it provides quite a good resolution. The idea is the same as with clock_gettime, but to get a time value you should:

#include <time.h>
#include <sys/time.h>
#include <stdint.h>

uint64_t get_gtod_clock_time ()
    struct timeval tv;

    if (gettimeofday (&tv, NULL) == 0)
        return (uint64_t) (tv.tv_sec * 1000000 + tv.tv_usec);
        return 0;

Again, the time value is scaled down to microseconds.


IRIX has the clock_gettime call, but it lacks CLOCK_MONOTONIC. Instead it has its own monotonic clock source defined as CLOCK_SGI_CYCLE which you should use instead of CLOCK_MONOTONIC with clock_gettime.

Solaris and HP-UX

Solaris has its own high-resolution timer interface gethrtime which returns the current timer value in nanoseconds. Though the newer versions of Solaris may have clock_gettime, you can stick to gethrtime if you need to support old Solaris versions.

Usage is simple:

#include <sys/time.h>

void time_measure_example ()
    hrtime_t prev_time_value, time_value;
    hrtime_t time_diff;

    /* Initial time */
    prev_time_value = gethrtime ();

    /* Do some work here */

    /* Final time */
    time_value = gethrtime ();

    /* Time difference */
    time_diff = time_value - prev_time_value;

HP-UX lacks clock_gettime, but it supports gethrtime which you should use in the same way as on Solaris.


BeOS also has its own high-resolution timer interface system_time which returns the number of microseconds have elapsed since the computer was booted.

Example usage:

#include <kernel/OS.h>

void time_measure_example ()
    bigtime_t prev_time_value, time_value;
    bigtime_t time_diff;

    /* Initial time */
    prev_time_value = system_time ();

    /* Do some work here */

    /* Final time */
    time_value = system_time ();

    /* Time difference */
    time_diff = time_value - prev_time_value;


OS/2 has its own API to retrieve high-precision time stamps:

  • query a timer frequency (ticks per unit) with DosTmrQueryFreq (for GCC compiler):

    #define INCL_DOSERRORS
    #include <os2.h>
    #include <stdint.h>
    ULONG freq;
    DosTmrQueryFreq (&freq);
  • query the current ticks value with DosTmrQueryTime:

    QWORD    tcounter;
    unit64_t time_low;
    unit64_t time_high;
    unit64_t timestamp;
    if (DosTmrQueryTime (&tcounter) == NO_ERROR) {
        time_low  = (unit64_t) tcounter.ulLo;
        time_high = (unit64_t) tcounter.ulHi;
        timestamp = (time_high << 32) | time_low;
  • scale the ticks to elapsed time, i.e. to microseconds:

    uint64_t usecs = (prev_timestamp - timestamp) / (freq / 1000000);

Example implementation

You can take a look at the plibsys library which implements all the described above strategies (see ptimeprofiler*.c for details).

One line if/else condition in linux shell scripting

To summarize the other answers, for general use:

Multi-line if...then statement

if [ foo ]; then
    a; b
elif [ bar ]; then
    c; d
    e; f

Single-line version

if [ foo ]; then a && b; elif [ bar ]; c && d; else e && f; fi

Using the OR operator

( foo && a && b ) || ( bar && c && d ) || e && f;


Remember that the AND and OR operators evaluate whether or not the result code of the previous operation was equal to true/success (0). So if a custom function returns something else (or nothing at all), you may run into problems with the AND/OR shorthand. In such cases, you may want to replace something like ( a && b ) with ( [ a == 'EXPECTEDRESULT' ] && b ), etc.

Also note that ( and [ are technically commands, so whitespace is required around them.

Instead of a group of && statements like then a && b; else, you could also run statements in a subshell like then $( a; b ); else, though this is less efficient. The same is true for doing something like result1=$( foo; a; b ); result2=$( bar; c; d ); [ "$result1" -o "$result2" ] instead of ( foo && a && b ) || ( bar && c && d ). Though at that point you'd be getting more into less-compact, multi-line stuff anyway.

How to select the last record of a table in SQL?

The last is just the first when you reverse your ordering.

How to add an existing folder with files to SVN?

In Windows 7 I did this:

  1. Have you installed SVN and Tortoise SVN? If not, Google them and do so now.
  2. Go to your SVN folder where you may have other repos (short for repository) (or if you're creating one from scratch, choose a location C drive, D drive, etc or network path).
  3. Create a new folder to store your new repository. Call it the same name as your project title
  4. Right click the folder and choose Tortoise SVN -> Create Repository here
  5. Say yes to Create Folder Structure
  6. Click OK. You should see a new icon looking like a "wave" next to your new folder/repo
  7. Right Click the new repo and choose SVN Repo Browser
  8. Right click 'trunk'
  9. Choose ADD Folder... and point to your folder structure of your project in development.
  10. Click OK and SVN will ADD your folder structure in. Be patient! It looks like SVN has crashed/frozen. Don't worry. It's doing its work.


Converting Go struct to JSON

You can define your own custom MarshalJSON and UnmarshalJSON methods and intentionally control what should be included, ex:

package main

import (

type User struct {
    name string

func (u *User) MarshalJSON() ([]byte, error) {
    return json.Marshal(&struct {
        Name     string `json:"name"`
        Name:     "customized" +,

func main() {
    user := &User{name: "Frank"}
    b, err := json.Marshal(user)
    if err != nil {

how to set image from url for imageView


Create a class that extends AsyncTask

public class ImageLoadTask extends AsyncTask<Void, Void, Bitmap> {

    private String url;
    private ImageView imageView;

    public ImageLoadTask(String url, ImageView imageView) {
        this.url = url;
        this.imageView = imageView;

    protected Bitmap doInBackground(Void... params) {
        try {
            URL urlConnection = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) urlConnection
            InputStream input = connection.getInputStream();
            Bitmap myBitmap = BitmapFactory.decodeStream(input);
            return myBitmap;
        } catch (Exception e) {
        return null;

    protected void onPostExecute(Bitmap result) {


And call this like new ImageLoadTask(url, imageView).execute();

Direct method:

Use this method and pass your url as string. It returns a bitmap. Set the bitmap to your ImageView.

public static Bitmap getBitmapFromURL(String src) {
    try {
        URL url = new URL(src);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        InputStream input = connection.getInputStream();
        Bitmap myBitmap = BitmapFactory.decodeStream(input);
        return myBitmap;
    } catch (IOException e) {
        return null;

And then this to ImageView like so:


And dont forget about this permission in maifest.

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


Try to call this method from another thread or AsyncTask because we are performing networking operations. no protocol

Try instead of db.parse(xml):

Document doc = db.parse(new InputSource(new StringReader(**xml**)));

iOS 7's blurred overlay effect using CSS?

Check out this demo page.
This demo uses html2canvas for rendering document as an image.

  1. When the "Show popup" link is clicked, the 'makePopup' function is called.
  2. 'makePopup' runs html2canvas for rendering document as an image.
  3. The image is converted to data-url string and it is painted as the popup's background-image.
  4. Popup's bg is blurred by -webkit-filter:blur
  5. Append the popup into document.
  6. While you're dragging the popup, it changes its own background-position.

Difference of keywords 'typename' and 'class' in templates?

While there is no technical difference, I have seen the two used to denote slightly different things.

For a template that should accept any type as T, including built-ins (such as an array )

template<typename T>
class Foo { ... }

For a template that will only work where T is a real class.

template<class T>
class Foo { ... }

But keep in mind that this is purely a style thing some people use. Not mandated by the standard or enforced by compilers

How to write a Python module/package?

Since nobody did cover this question of the OP yet:

What I wanted to do:

Make a python module install-able with "pip install ..."

Here is an absolute minimal example, showing the basic steps of preparing and uploading your package to PyPI using setuptools and twine.

This is by no means a substitute for reading at least the tutorial, there is much more to it than covered in this very basic example.

Creating the package itself is already covered by other answers here, so let us assume we have that step covered and our project structure like this:

+-- hellostackoverflow/

In order to use setuptools for packaging, we need to add a file, this goes into the root folder of our project:

+-- hellostackoverflow/

At the minimum, we specify the metadata for our package, our would look like this:

from setuptools import setup

    description='a pip-installable package example',
    author='Benjamin Gerfelder',
    author_email='[email protected]',

Since we have set license='MIT', we include a copy in our project as LICENCE.txt, alongside a readme file in reStructuredText as README.rst:

+-- LICENCE.txt
+-- README.rst
+-- hellostackoverflow/

At this point, we are ready to go to start packaging using setuptools, if we do not have it already installed, we can install it with pip:

pip install setuptools

In order to do that and create a source distribution, at our project root folder we call our from the command line, specifying we want sdist:

python sdist

This will create our distribution package and egg-info, and result in a folder structure like this, with our package in dist:

+-- dist/
+-- hellostackoverflow.egg-info/
+-- LICENCE.txt
+-- README.rst
+-- hellostackoverflow/

At this point, we have a package we can install using pip, so from our project root (assuming you have all the naming like in this example):

pip install ./dist/hellostackoverflow-0.0.1.tar.gz

If all goes well, we can now open a Python interpreter, I would say somewhere outside our project directory to avoid any confusion, and try to use our shiny new package:

Python 3.5.2 (default, Sep 14 2017, 22:51:06) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from hellostackoverflow import hellostackoverflow
>>> hellostackoverflow.greeting()
'Hello Stack Overflow!'

Now that we have confirmed the package installs and works, we can upload it to PyPI.

Since we do not want to pollute the live repository with our experiments, we create an account for the testing repository, and install twine for the upload process:

pip install twine

Now we're almost there, with our account created we simply tell twine to upload our package, it will ask for our credentials and upload our package to the specified repository:

twine upload --repository-url dist/*

We can now log into our account on the PyPI test repository and marvel at our freshly uploaded package for a while, and then grab it using pip:

pip install --index-url hellostackoverflow

As we can see, the basic process is not very complicated. As I said earlier, there is a lot more to it than covered here, so go ahead and read the tutorial for more in-depth explanation.

Execute Python script via crontab

Put your script in a file starting with


Then give execute permission to that script using

chmod a+x

and use the full path of your file in your crontab.

See documentation of execve(2) which is handling the shebang.

How can I insert data into Database Laravel?

The error MethodNotAllowedHttpException means the route exists, but the HTTP method (GET) is wrong. You have to change it to POST:

Route::post('test/register', array('uses'=>'TestController@create'));

Also, you need to hash your passwords:

public function create()
    $user = new User;

    $user->username = Input::get('username');
    $user->email = Input::get('email');
    $user->password = Hash::make(Input::get('password'));

    return Redirect::back();

And I removed the line:

$user= Input::all();

Because in the next command you replace its contents with

$user = new User;

To debug your Input, you can, in the first line of your controller:

dd( Input::all() );

It will display all fields in the input.

How to add image background to btn-default twitter-bootstrap button?

Have you tried using a icon font like

Bootstrap comes with their own library, but it doesn't have as many icons as Font Awesome.

Angular.js programmatically setting a form field to dirty

If you have access to the NgModelController (you can only get access to it from a directive) then you can call

ngModel.$setViewValue("your new view value");
// or to keep the view value the same and just change it to dirty

Unable to locate tools.jar

I was also facing the same error. This was removed after setting Java_Home path to C:\Program Files\Java\jdk1.8.0_121. Please ensure bin is not included in the path and no slash is there after jdk1.8.0_121 after you have defined %JAVA_HOME%\bin in the system path variable.

Public class is inaccessible due to its protection level

Also if you want to do something like ClassB.Run("thing");, make sure the Method Run(); is static or you could call it like this: thing.Run("thing");.

Using Server.MapPath() inside a static field in ASP.NET MVC

I think you can try this for calling in from a class


*----------------Sorry I oversight, for static function already answered the question by adrift*



I got exception while using System.Web.Hosting.HostingEnvironment.MapPath("~/SignatureImages/");

Ex details : System.ArgumentException: The relative virtual path 'SignatureImages' is not allowed here. at System.Web.VirtualPath.FailIfRelativePath()

Solution (tested in static webmethod)

System.Web.HttpContext.Current.Server.MapPath("~/SignatureImages/"); Worked

Windows could not start the Apache2 on Local Computer - problem

Follow this step it will works fine. Go to Control panel-->Programs and features-->click Turn Windows features on and off--> see IIS is Checked Or Not If checked please unckeck IIS and restart the computer.After that Open services see Web Deployement Agent Service status if its started please stop.And also see WampAppache and WampSqlID if its not started please start manually. it will works for me.

How can I check if a command exists in a shell script?

The question doesn't specify a shell, so for those using fish (friendly interactive shell):

if command -v foo > /dev/null
  echo exists
  echo does not exist

For basic POSIX compatibility, we use the -v flag which is an alias for --search or -s.

Random strings in Python

Sometimes, I've wanted random strings that are semi-pronounceable, semi-memorable.

import random

def randomWord(length=5):
    consonants = "bcdfghjklmnpqrstvwxyz"
    vowels = "aeiou"

    return "".join(random.choice((consonants, vowels)[i%2]) for i in range(length))


>>> randomWord()
>>> randomWord()
>>> randomWord(10)

To avoid 4-letter words, don't set length to 4.


Java: set timeout on a certain block of code?

There is a hacky way to do it.

Set some boolean field to indicate whether the work was completed. Then before the block of code, set a timer to run a piece of code after your timeout. The timer will check if the block of code had finished executing, and if not, throw an exception. Otherwise it will do nothing.

The end of the block of code should, of course, set the field to true to indicate the work was done.

How to get the URL without any parameters in JavaScript?

You can concat origin and pathname, if theres present a port such as, that will be included as well.

location.origin + location.pathname

How to print environment variables to the console in PowerShell?

The following is works best in my opinion:

Get-Item Env:PATH
  1. It's shorter and therefore a little bit easier to remember than Get-ChildItem. There's no hierarchy with environment variables.
  2. The command is symmetrical to one of the ways that's used for setting environment variables with Powershell. (EX: Set-Item -Path env:SomeVariable -Value "Some Value")
  3. If you get in the habit of doing it this way you'll remember how to list all Environment variables; simply omit the entry portion. (EX: Get-Item Env:)

I found the syntax odd at first, but things started making more sense after I understood the notion of Providers. Essentially PowerShell let's you navigate disparate components of the system in a way that's analogous to a file system.

What's the point of the trailing colon in Env:? Try listing all of the "drives" available through Providers like this:

PS> Get-PSDrive

I only see a few results... (Alias, C, Cert, D, Env, Function, HKCU, HKLM, Variable, WSMan). It becomes obvious that Env is simply another "drive" and the colon is a familiar syntax to anyone who's worked in Windows.

You can navigate the drives and pick out specific values:

Get-ChildItem C:\Windows
Get-Item C:
Get-Item Env:
Get-Item HKLM:

Refreshing page on click of a button

There are several ways to reload the current page using a button or other trigger. The examples below use a button click to reload the page but you can use a text hyperlink or any trigger you like.

<input type="button" value="Reload Page" onClick="window.location.reload()">

<input type="button" value="Reload Page" onClick="history.go(0)">

<input type="button" value="Reload Page" onClick="window.location.href=window.location.href">

How to set the color of "placeholder" text?

::-webkit-input-placeholder { /* WebKit browsers */
    color:    #999;
:-moz-placeholder { /* Mozilla Firefox 4 to 18 */
    color:    #999;
::-moz-placeholder { /* Mozilla Firefox 19+ */
    color:    #999;
:-ms-input-placeholder { /* Internet Explorer 10+ */
    color:    #999;

How can I combine flexbox and vertical scroll in a full-height app?

Flexbox spec editor here.

This is an encouraged use of flexbox, but there are a few things you should tweak for best behavior.

  • Don't use prefixes. Unprefixed flexbox is well-supported across most browsers. Always start with unprefixed, and only add prefixes if necessary to support it.

  • Since your header and footer aren't meant to flex, they should both have flex: none; set on them. Right now you have a similar behavior due to some overlapping effects, but you shouldn't rely on that unless you want to accidentally confuse yourself later. (Default is flex:0 1 auto, so they start at their auto height and can shrink but not grow, but they're also overflow:visible by default, which triggers their default min-height:auto to prevent them from shrinking at all. If you ever set an overflow on them, the behavior of min-height:auto changes (switching to zero rather than min-content) and they'll suddenly get squished by the extra-tall <article> element.)

  • You can simplify the <article> flex too - just set flex: 1; and you'll be good to go. Try to stick with the common values in unless you have a good reason to do something more complicated - they're easier to read and cover most of the behaviors you'll want to invoke.

SQL Query - SUM(CASE WHEN x THEN 1 ELSE 0) for multiple columns

I think you should make a subquery to do grouping. In this case inner subquery returns few rows and you don't need a CASE statement. So I think this is going to be faster:

select Detail.ReceiptDate AS 'DATE',


select SentDate AS 'ReceiptDate', 
       count('TotalMailed') AS TotalMailed, 
       0 as TotalReturnMail, 
       0 as TraceReturnedMail
from MailDataExtract
where sentdate is not null

select MDE.ReturnMailDate AS 'ReceiptDate', 
       0 AS TotalMailed, 
       count(TotalReturnMail) as TotalReturnMail, 
       0 as TraceReturnedMail
from MailDataExtract MDE
where MDE.ReturnMailDate is not null
GROUP BY  MDE.ReturnMailDate


select MDE.ReturnMailDate AS 'ReceiptDate', 
       0 AS TotalMailed, 
       0 as TotalReturnMail, 
       count(TraceReturnedMail) as TraceReturnedMail

from MailDataExtract MDE
    inner join DTSharedData.dbo.ScanData SD 
        ON SD.ScanDataID = MDE.ReturnScanDataID
   where MDE.ReturnMailDate is not null AND SD.ReturnMailTypeID = 1
GROUP BY MDE.ReturnMailDate

) as Detail
GROUP BY Detail.ReceiptDate

Date query with ISODate in mongodb doesn't seem to work

Try this:

{ "dt" : { "$gte" : ISODate("2013-10-01") } }

Why does Path.Combine not properly concatenate filenames that start with Path.DirectorySeparatorChar?

If you want to combine both paths without losing any path you can use this:

?Path.Combine(@"C:\test", @"\test".Substring(0, 1) == @"\" ? @"\test".Substring(1, @"\test".Length - 1) : @"\test");

Or with variables:

string Path1 = @"C:\Test";
string Path2 = @"\test";
string FullPath = Path.Combine(Path1, Path2.IsRooted() ? Path2.Substring(1, Path2.Length - 1) : Path2);

Both cases return "C:\test\test".

First, I evaluate if Path2 starts with / and if it is true, return Path2 without the first character. Otherwise, return the full Path2.


Even after following all the suggestions, if it shows error then check your buildType in Gradle.

Make sure signingConfig signingConfigs.config

is in release scope, not in debug.

Are HTTP cookies port specific?

The current cookie specification is RFC 6265, which replaces RFC 2109 and RFC 2965 (both RFCs are now marked as "Historic") and formalizes the syntax for real-world usages of cookies. It clearly states:

  1. Introduction


For historical reasons, cookies contain a number of security and privacy infelicities. For example, a server can indicate that a given cookie is intended for "secure" connections, but the Secure attribute does not provide integrity in the presence of an active network attacker. Similarly, cookies for a given host are shared across all the ports on that host, even though the usual "same-origin policy" used by web browsers isolates content retrieved via different ports.

And also:

8.5. Weak Confidentiality

Cookies do not provide isolation by port. If a cookie is readable by a service running on one port, the cookie is also readable by a service running on another port of the same server. If a cookie is writable by a service on one port, the cookie is also writable by a service running on another port of the same server. For this reason, servers SHOULD NOT both run mutually distrusting services on different ports of the same host and use cookies to store security sensitive information.

How can I require at least one checkbox be checked before a form can be submitted?

Here's an example using jquery and your html.

     <script src=""></script>

<script type="text/javascript">
$(document).ready(function () {
    $('#checkBtn').click(function() {
      checked = $("input[type=checkbox]:checked").length;

      if(!checked) {
        alert("You must check at least one checkbox.");
        return false;



<p>Box Set 1</p>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 1" required><label>Box 1</label></li>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 2" required><label>Box 2</label></li>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 3" required><label>Box 3</label></li>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 4" required><label>Box 4</label></li>
<p>Box Set 2</p>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 5" required><label>Box 5</label></li>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 6" required><label>Box 6</label></li>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 7" required><label>Box 7</label></li>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 8" required><label>Box 8</label></li>
<p>Box Set 3</p>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 9" required><label>Box 9</label></li>
<p>Box Set 4</p>
   <li><input name="BoxSelect[]" type="checkbox" value="Box 10" required><label>Box 10</label></li>

<input type="button" value="Test Required" id="checkBtn">


Returning http status code from Web Api controller

If you need to return an IHttpActionResult and want to return the error code plus a message, use:

return ResponseMessage(Request.CreateErrorResponse(HttpStatusCode.NotModified, "Error message here"));

Disable/turn off inherited CSS3 transitions

You could also disinherit all transitions inside a containing element:


.noTrans *{
-moz-transition: none;
-webkit-transition: none;
-o-transition: color 0 ease-in;
transition: none;


<a href="#">Content</a>
<a href="#">Content</a>
<div class="noTrans">
<a href="#">Content</a>
<a href="#">Content</a>

How to access parent scope from within a custom directive *with own scope* in AngularJS?

Here's a trick I used once: create a "dummy" directive to hold the parent scope and place it somewhere outside the desired directive. Something like:

module.directive('myDirectiveContainer', function () {
    return {
        controller: function ($scope) {
            this.scope = $scope;

module.directive('myDirective', function () {
    return {
        require: '^myDirectiveContainer',
        link: function (scope, element, attrs, containerController) {
            // use containerController.scope here...

and then

<div my-directive-container="">
    <div my-directive="">

Maybe not the most graceful solution, but it got the job done.

Initialize static variables in C++ class?

If your goal is to initialize the static variable in your header file (instead of a *.cpp file, which you may want if you are sticking to a "header only" idiom), then you can work around the initialization problem by using a template. Templated static variables can be initialized in a header, without causing multiple symbols to be defined.

See here for an example:

Static member initialization in a class template

How to prevent rm from reporting that a file was not found?

\rm -f file will never report not found.

Differences between Microsoft .NET 4.0 full Framework and Client Profile

You should deploy "Client Profile" instead of "Full Framework" inside a corporation mostly in one case only: you want explicitly deny some .NET features are running on the client computers. The only real case is denying of ASP.NET on the client machines of the corporation, for example, because of security reasons or the existing corporate policy.

Saving of less than 8 MB on client computer can not be a serious reason of "Client Profile" deployment in a corporation. The risk of the necessity of the deployment of the "Full Framework" later in the corporation is higher than costs of 8 MB per client.

How to check if a list is empty in Python?

I like Zarembisty's answer. Although, if you want to be more explicit, you can always do:

if len(my_list) == 0:
    print "my_list is empty"

excel vba getting the row,cell value from selection.address

Dim f as Range

Set f=ActiveSheet.Cells.Find(...)

If Not f Is Nothing then
    msgbox "Row=" & f.Row & vbcrlf & "Column=" & f.Column
    msgbox "value not found!"
End If

How to increment variable under DOS?

I built my answer thanks to previous contributors.

Not having time for a custom counter.exe, I downloaded sed for FREEDOS.

And then the batch code could be, emulating "wc -l" with the utility sed, something like this according to your loop (I just use it to increment through executions starting from "1" to n+1):

Just remember to manually create a file "test.txt" with written on the first row


sed -n '$=' test.txt > counter.txt
set /P Var=< counter.txt
echo 0 >> test.txt

Reading data from a website using C#

The WebClient class should be more than capable of handling the functionality you describe, for example:

System.Net.WebClient wc = new System.Net.WebClient();
byte[] raw = wc.DownloadData("");

string webData = System.Text.Encoding.UTF8.GetString(raw);

or (further to suggestion from Fredrick in comments)

System.Net.WebClient wc = new System.Net.WebClient();
string webData = wc.DownloadString("");

When you say it took 30 seconds, can you expand on that a little more? There are many reasons as to why that could have happened. Slow servers, internet connections, dodgy implementation etc etc.

You could go a level lower and implement something like this:

HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create("");

using (StreamWriter streamWriter = new StreamWriter(webRequest.GetRequestStream(), Encoding.UTF8))

string responseData = string.Empty;
HttpWebResponse httpResponse = (HttpWebResponse)webRequest.GetResponse();
using (StreamReader responseReader = new StreamReader(httpResponse.GetResponseStream()))
    responseData = responseReader.ReadToEnd();

However, at the end of the day the WebClient class wraps up this functionality for you. So I would suggest that you use WebClient and investigate the causes of the 30 second delay.

Laravel Blade html image

as of now, you can use

<img src="{{ asset('images/foo.png') }}" alt="tag">

In php, is 0 treated as empty?

From a linguistic point of view empty has a meaning of without value. Like the others said you'll have to use isset() in order to check if a variable has been defined, which is what you do.

How to detect DataGridView CheckBox event change?

I found @Killercam's solution to work but was a bit dodgy if the user double clicked too fast. Not sure if other's found that the case either. I found a another solution here.

It uses the datagrid's CellValueChanged and CellMouseUp. Changhong explains that

"The reason for that is OnCellvalueChanged event won’t fire until the DataGridView thinks you have completed editing. This makes senses for a TextBox Column, as OnCellvalueChanged wouldn’t [bother] to fire for each key strike, but it doesn’t [make sense] for a CheckBox."

Here it is in action from his example:

private void myDataGrid_OnCellValueChanged(object sender, DataGridViewCellEventArgs e)
    if (e.ColumnIndex == myCheckBoxColumn.Index && e.RowIndex != -1)
        // Handle checkbox state change here

And the code to tell the checkbox it is done editing when it is clicked, instead of waiting till the user leaves the field:

private void myDataGrid_OnCellMouseUp(object sender,DataGridViewCellMouseEventArgs e)
    // End of edition on each click on column of checkbox
    if (e.ColumnIndex == myCheckBoxColumn.Index && e.RowIndex != -1)

Edit: A DoubleClick event is treated separate from a MouseUp event. If a DoubleClick event is detected, the application will ignore the first MouseUp event entirely. This logic needs to be added to the CellDoubleClick event in addition to the MouseUp event:

private void myDataGrid_OnCellDoubleClick(object sender,DataGridViewCellEventArgs e)
    // End of edition on each click on column of checkbox
    if (e.ColumnIndex == myCheckBoxColumn.Index && e.RowIndex != -1)

How do I use Spring Boot to serve static content located in Dropbox folder?

@Mark Schäfer

Never too late, but add a slash (/) after static:


So http://<host>/index.html is now reachable.

How to get the first word in the string

If you want to feel especially sly, you can write it as this:

(firstWord, rest) = yourLine.split(maxsplit=1)

This is supposed to bring the best from both worlds:

I kind of fell in love with this solution and it's general unpacking capability, so I had to share it.

awk partly string match (if column/word partly matches)

awk '$3 ~ /snow/ { print }' dummy_file 

How do you Programmatically Download a Webpage in Java

You'd most likely need to extract code from a secure web page (https protocol). In the following example, the html file is being saved into c:\temp\filename.html Enjoy!



 * <b>Get the Html source from the secure url </b>
public class HttpsClientUtil {
    public static void main(String[] args) throws Exception {
        String httpsURL = "";
        String FILENAME = "c:\\temp\\filename.html";
        BufferedWriter bw = new BufferedWriter(new FileWriter(FILENAME));
        URL myurl = new URL(httpsURL);
        HttpsURLConnection con = (HttpsURLConnection) myurl.openConnection();
        con.setRequestProperty ( "User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0" );
        InputStream ins = con.getInputStream();
        InputStreamReader isr = new InputStreamReader(ins, "Windows-1252");
        BufferedReader in = new BufferedReader(isr);
        String inputLine;

        // Write each line into the file
        while ((inputLine = in.readLine()) != null) {

Why do I get "Cannot redirect after HTTP headers have been sent" when I call Response.Redirect()?

Just check if you have set the buffering option to false (by default its true). For response.redirect to work,

  1. Buffering should be true,
  2. you should not have sent more data using response.write which exceeds the default buffer size (in which case it will flush itself causing the headers to be sent) therefore disallowing you to redirect.

How can I create persistent cookies in ASP.NET?

Here's how you can do that.

Writing the persistent cookie.

//create a cookie
HttpCookie myCookie = new HttpCookie("myCookie");

//Add key-values in the cookie

//set cookie expiry date-time. Made it to last for next 12 hours.
myCookie.Expires = DateTime.Now.AddHours(12);

//Most important, write the cookie to client.

Reading the persistent cookie.

//Assuming user comes back after several hours. several < 12.
//Read the cookie from Request.
HttpCookie myCookie = Request.Cookies["myCookie"];
if (myCookie == null)
    //No cookie found or cookie expired.
    //Handle the situation here, Redirect the user or simply return;

//ok - cookie is found.
//Gracefully check if the cookie has the key-value as expected.
if (!string.IsNullOrEmpty(myCookie.Values["userid"]))
    string userId = myCookie.Values["userid"].ToString();
    //Yes userId is found. Mission accomplished.

How to conclude your merge of a file?

Note and update:

Since Git1.7.4 (January 2011), you have git merge --abort, synonymous to "git reset --merge" when a merge is in progress.

But if you want to complete the merge, while somehow nothing remains to be added, then a crude rm -rf .git/MERGE* can be enough for Git to forget about the current merge.

Compile error: "g++: error trying to exec 'cc1plus': execvp: No such file or directory"

I don't know why but i just renamed my source file COLARR.C to colarr.c and the error vanished! probably you need this

sudo apt-get install g++

React-Native: Application has not been registered error

This can also be due to Root component name starts with lowercase.

Recorrect it or rather create the project once again with a PascalCase name.

e.g. ignite new HelloWord

How to retrieve data from a SQL Server database in C#?

To retrieve data from database:

private SqlConnection Conn;
 private void CreateConnection()
    string ConnStr =
    Conn = new SqlConnection(ConnStr);
 public DataTable getData()
    string SqlString = "SELECT * FROM TableName WHERE SomeID = @SomeID;";
    SqlDataAdapter sda = new SqlDataAdapter(SqlString, Conn);
    DataTable dt = new DataTable();
    catch (SqlException se)
        DBErLog.DbServLog(se, se.ToString());
    return dt;

How do I style (css) radio buttons and labels?

The first part of your question can be solved with just HTML & CSS; you'll need to use Javascript for the second part.

Getting the Label Near the Radio Button

I'm not sure what you mean by "next to": on the same line and near, or on separate lines? If you want all of the radio buttons on the same line, just use margins to push them apart. If you want each of them on their own line, you have two options (unless you want to venture into float: territory):

  • Use <br />s to split the options apart and some CSS to vertically align them:
<style type='text/css'>
    .input input
        width: 20px;
<div class="input radio">
        <legend>What color is the sky?</legend>
        <input type="hidden" name="data[Submit][question]" value="" id="SubmitQuestion" />

        <input type="radio" name="data[Submit][question]" id="SubmitQuestion1" value="1"  />
        <label for="SubmitQuestion1">A strange radient green.</label>
        <br />
        <input type="radio" name="data[Submit][question]" id="SubmitQuestion2" value="2"  />
        <label for="SubmitQuestion2">A dark gloomy orange</label>
        <br />
        <input type="radio" name="data[Submit][question]" id="SubmitQuestion3" value="3"  />
        <label for="SubmitQuestion3">A perfect glittering blue</label>

Applying a Style to the Currently Selected Label + Radio Button

Styling the <label> is why you'll need to resort to Javascript. A library like jQuery is perfect for this:

<style type='text/css'>
    .input label.focused
        background-color: #EEEEEE;
        font-style: italic;
<script type='text/javascript' src='jquery.js'></script>
<script type='text/javascript'>
    $(document).ready(function() {
        $('.input :radio').focus(updateSelectedStyle);
        $('.input :radio').blur(updateSelectedStyle);
        $('.input :radio').change(updateSelectedStyle);

    function updateSelectedStyle() {
        $('.input :radio').removeClass('focused').next().removeClass('focused');
        $('.input :radio:checked').addClass('focused').next().addClass('focused');

The focus and blur hooks are needed to make this work in IE.

How to convert latitude or longitude to meters?

For approximating short distances between two coordinates I used formulas from

m_per_deg_lat = 111132.954 - 559.822 * cos( 2 * latMid ) + 1.175 * cos( 4 * latMid);
m_per_deg_lon = 111132.954 * cos ( latMid );


In the code below I've left the raw numbers to show their relation to the formula from wikipedia.

double latMid, m_per_deg_lat, m_per_deg_lon, deltaLat, deltaLon,dist_m;

latMid = (Lat1+Lat2 )/2.0;  // or just use Lat1 for slightly less accurate estimate

m_per_deg_lat = 111132.954 - 559.822 * cos( 2.0 * latMid ) + 1.175 * cos( 4.0 * latMid);
m_per_deg_lon = (3.14159265359/180 ) * 6367449 * cos ( latMid );

deltaLat = fabs(Lat1 - Lat2);
deltaLon = fabs(Lon1 - Lon2);

dist_m = sqrt (  pow( deltaLat * m_per_deg_lat,2) + pow( deltaLon * m_per_deg_lon , 2) );

The wikipedia entry states that the distance calcs are within 0.6m for 100km longitudinally and 1cm for 100km latitudinally but I have not verified this as anywhere near that accuracy is fine for my use.

How can I safely create a nested directory?

On Python = 3.5, use pathlib.Path.mkdir:

from pathlib import Path
Path("/my/directory").mkdir(parents=True, exist_ok=True)

For older versions of Python, I see two answers with good qualities, each with a small flaw, so I will give my take on it:

Try os.path.exists, and consider os.makedirs for the creation.

import os
if not os.path.exists(directory):

As noted in comments and elsewhere, there's a race condition – if the directory is created between the os.path.exists and the os.makedirs calls, the os.makedirs will fail with an OSError. Unfortunately, blanket-catching OSError and continuing is not foolproof, as it will ignore a failure to create the directory due to other factors, such as insufficient permissions, full disk, etc.

One option would be to trap the OSError and examine the embedded error code (see Is there a cross-platform way of getting information from Python’s OSError):

import os, errno

except OSError as e:
    if e.errno != errno.EEXIST:

Alternatively, there could be a second os.path.exists, but suppose another created the directory after the first check, then removed it before the second one – we could still be fooled.

Depending on the application, the danger of concurrent operations may be more or less than the danger posed by other factors such as file permissions. The developer would have to know more about the particular application being developed and its expected environment before choosing an implementation.

Modern versions of Python improve this code quite a bit, both by exposing FileExistsError (in 3.3+)...

except FileExistsError:
    # directory already exists

...and by allowing a keyword argument to os.makedirs called exist_ok (in 3.2+).

os.makedirs("path/to/directory", exist_ok=True)  # succeeds even if directory exists.

Modular multiplicative inverse function in Python

Python 3.8+

y = pow(x, -1, p)

Python 3.7 and earlier

Maybe someone will find this useful (from wikibooks):

def egcd(a, b):
    if a == 0:
        return (b, 0, 1)
        g, y, x = egcd(b % a, a)
        return (g, x - (b // a) * y, y)

def modinv(a, m):
    g, x, y = egcd(a, m)
    if g != 1:
        raise Exception('modular inverse does not exist')
        return x % m

Add new item in existing array in

A new Append<TSource> method has been added to IEnumerable<TSource> since .NET Framework 4.7.1 and .NET Core 1.0.

Here is how to use it:

var numbers = new [] { "one", "two", "three" };
numbers = numbers.Append("four").ToArray();
Console.WriteLine(string.Join(", ", numbers)); // one, two, three, four

Note that if you want to add the element at the beginning of the array, you can use the new Prepend<TSource> method instead.

How to import a single table in to mysql database using command line

It works correctly...

C:\>mysql>bin>mysql -u USERNAME DB_NAME < tableNameFile.sql

please note .sql file specified your current database..

SQL Server : SUM() of multiple rows including where clauses

sounds like you want something like:

select PropertyID, SUM(Amount)
from MyTable
Where EndDate is null
Group by PropertyID

Update span tag value with JQuery

Tag ids must be unique. You are updating the span with ID 'ItemCostSpan' of which there are two. Give the span a class and get it using find.

    $("legend").each(function() {
        var SoftwareItem = $(this).text();
        itemCost = GetItemCost(SoftwareItem);
        $("input:checked").each(function() {               
            var Component = $(this).next("label").text();
            itemCost += GetItemCost(Component);
        $(this).find(".ItemCostSpan").text("Item Cost = $ " + itemCost);

Is a DIV inside a TD a bad idea?

It breaks semantics, that's all. It works fine, but there may be screen readers or something down the road that won't enjoy processing your HTML if you "break semantics".

Removing elements by class name?

In pure vanilla Javascript, without jQuery or ES6, you could do:

const elements = document.getElementsByClassName("my-class");

while (elements.length > 0) elements[0].remove();

How to edit the legend entry of a chart in Excel?

The data series names are defined by the column headers. Add the names to the column headers that you would like to use as titles for each of your data series, select all of the data (including the headers), then re-generate your graph. The names in the headers should then appear as the names in the legend for each series.

Column headers become data series titles in graph legend

Microsoft Advertising SDK doesn't deliverer ads

I only use MicrosoftAdvertising.Mobile and Microsoft.Advertising.Mobile.UI and I am served ads. The SDK should only add the DLLs not reference itself.

Note: You need to explicitly set width and height Make sure the phone dialer, and web browser capabilities are enabled

Followup note: Make sure that after you've removed the SDK DLL, that the xmlns references are not still pointing to it. The best route to take here is

  1. Remove the XAML for the ad
  2. Remove the xmlns declaration (usually at the top of the page, but sometimes will be declared in the ad itself)
  3. Remove the bad DLL (the one ending in .SDK )
  4. Do a Clean and then Build (clean out anything remaining from the DLL)
  5. Add the xmlns reference (actual reference is below)
  6. Add the ad to the page (example below)

Here is the xmlns reference:


Then the ad itself:

<AdNamespace:AdControl x:Name="myAd" Height="80" Width="480"                    AdUnitId="yourAdUnitIdHere" ApplicationId="yourIdHere"/> 

Binding Combobox Using Dictionary as the Datasource

        var colors = new Dictionary < string, string > ();
        colors["10"] = "Red";

Binding to Combobox

        comboBox1.DataSource = new BindingSource(colors, null);
        comboBox1.DisplayMember = "Value";
        comboBox1.ValueMember = "Key"; 

Full Source...Dictionary as a Combobox Datasource


Detecting input change in jQuery?

If you've got HTML5:

  • oninput (fires only when a change actually happens, but does so immediately)

Otherwise you need to check for all these events which might indicate a change to the input element's value:

  • onchange
  • onkeyup (not keydown or keypress as the input's value won't have the new keystroke in it yet)
  • onpaste (when supported)

and maybe:

  • onmouseup (I'm not sure about this one)

How do I add records to a DataGridView in VB.Net?

I think you should build a dataset/datatable in code and bind the grid to that.

How to efficiently remove duplicates from an array without using Set

 package javaa;

public class UniqueElementinAnArray 

 public static void main(String[] args) 
    int[] a = {10,10,10,10,10,100};
    int[] output = new int[a.length];
    int count = 0;
    int num = 0;

    //Iterate over an array
    for(int i=0; i<a.length; i++)
        boolean flag = check(output,num);


    //print the all the elements from an array except zero's (0)
    for (int i : output) 
        if(i!=0 )
            System.out.print(i+"  ");


 * If a next number from an array is already exists in unique array then return true else false
 * @param arr   Unique number array. Initially this array is an empty.
 * @param num   Number to be search in unique array. Whether it is duplicate or unique.
 * @return  true: If a number is already exists in an array else false 
public static boolean check(int[] arr, int num)
    boolean flag = false;
    for(int i=0;i<arr.length; i++)
            flag = true;
    return flag;


Setting Different Bar color in matplotlib Python

Update pandas 0.17.0

@7stud's answer for the newest pandas version would require to just call


instead of


The plotting functions have become members of the Series, DataFrame objects and in fact calling pd.Series.plot with a color argument gives an error

JavaScript: get code to run every minute

You could use setInterval for this.

<script type="text/javascript">
function myFunction () {

var interval = setInterval(function () { myFunction(); }, 60000);

Disable the timer by setting clearInterval(interval).

See this Fiddle:

JS regex: replace all digits in string

The /g modifier is used to perform a global match (find all matches rather than stopping after the first)

You can use \d for digit, as it is shorter than [0-9].


var s = "04.07.2012"; 
echo(s.replace(/\d/g, "X"));



How to replace local branch with remote branch entirely in Git?

If you want to update branch that is not currently checked out you can do:

git fetch -f origin rbranch:lbranch

What does "async: false" do in jQuery.ajax()?


Synchronous XMLHttpRequest outside of workers is in the process of being removed from the web platform as it has detrimental effects to the end user's experience. (This is a long process that takes many years.) Developers must not pass false for the async argument when the JavaScript global environment is a document environment. User agents are strongly encouraged to warn about such usage in developer tools and may experiment with throwing an InvalidAccessError exception when it occurs. The future direction is to only allow XMLHttpRequests in worker threads. The message is intended to be a warning to that effect.

Detect Close windows event by jQuery

You can use:

$(window).unload(function() {
    //do something

Unload() is deprecated in jQuery version 1.8, so if you use jQuery > 1.8 you can use even beforeunload instead.

The beforeunload event fires whenever the user leaves your page for any reason.

$(window).on("beforeunload", function() { 
    return confirm("Do you really want to close?"); 

Source Browser window close event

How can I get Apache gzip compression to work?

Your .htaccess should run just fine; it depends on four different Apache modules (one per each <IfModule> directive). I guess one of the following:

  • your Apache server doesn't have either mod_filter, mod_deflate, mod_headers and/or mod_setenvif modules installed and running. If you can access the server config, please check /etc/apache2/httpd.conf (and the related Apache config files); otherwise, you can see which modules are loaded via phpinfo(), under the apache2handler section (see attached image); (EDIT) OR, you can open a terminal window and issue the command sudo apachectl -M that will list the loaded modules;

  • if you get an http 500 internal server error, your server may not be allowed to use .htaccess files;

  • you are trying to load a PHP file that sends its own headers (overwriting Apache'sheaders), thus "confusing" the browser.

In any case, you should double-check your server config and error logs to see what's going wrong. Just to be sure, try to use the fastest way suggested here in Apache docs:

AddOutputFilterByType DEFLATE text/html text/plain text/xml

and then try to load a large textfile (preferably, clean your cache first).

(EDIT) If the needed modules are there (in the Apache modules dir) but aren't loaded, just edit /etc/apache2/httpd.conf and add a LoadModule directive for each one of them.

If the needed modules aren't there (neither loaded, nor in the Apache modules directory), I fear that the only option is reinstalling Apache (a complete version).

phpinfo() apache2handler section

How to launch an application from a browser?

We use a sonicwall vpn. It launches a java applet that launches mstc with all the credentials setup. You really can't do this without a java applet or activex plugin.

Microsoft uses this technique itself on their small business server for getting inside the network. I wouldn't say it is a terrible idea, as long as platform independence isn't important.

How to escape comma and double quote at same time for CSV file?

There are several libraries. Here are two examples:

❐ Apache Commons Lang

Apache Commons Lang includes a special class to escape or unescape strings (CSV, EcmaScript, HTML, Java, Json, XML): org.apache.commons.lang3.StringEscapeUtils.

  • Escape to CSV

    String escaped = StringEscapeUtils
        .escapeCsv("I said \"Hey, I am 5'10\".\""); // I said "Hey, I am 5'10"."
    System.out.println(escaped); // "I said ""Hey, I am 5'10""."""
  • Unescape from CSV

    String unescaped = StringEscapeUtils
        .unescapeCsv("\"I said \"\"Hey, I am 5'10\"\".\"\"\""); // "I said ""Hey, I am 5'10""."""
    System.out.println(unescaped); // I said "Hey, I am 5'10"."

* You can download it from here.

❐ OpenCSV

If you use OpenCSV, you will not need to worry about escape or unescape, only for write or read the content.

  • Writing file:

    FileOutputStream fos = new FileOutputStream("awesomefile.csv"); 
    OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
    CSVWriter writer = new CSVWriter(osw);
    String[] row = {
        "I said \"Hey, I am 5'10\".\""
  • Reading file:

    FileInputStream fis = new FileInputStream("awesomefile.csv"); 
    InputStreamReader isr = new InputStreamReader(fis, "UTF-8");
    CSVReader reader = new CSVReader(isr);
    for (String[] row; (row = reader.readNext()) != null;) {

* You can download it from here.

Meaning of "487 Request Terminated"

It's the response code a SIP User Agent Server (UAS) will send to the client after the client sends a CANCEL request for the original unanswered INVITE request (yet to receive a final response).

Here is a nice CANCEL SIP Call Flow illustration.

How to make correct date format when writing data to Excel

Try using


And putting that as a double in the cell. There could be issues with Excel on Mac Systems (it uses a different datetime-->double conversion), but it should work well for most cases.

Hope this helps.

Invariant Violation: Objects are not valid as a React child

I had the same problem because I didn't put the props in the curly braces.

export default function Hero(children, hero ) {
    return (
        <header className={hero}>

So if your code is similar to the above one then you will get this error. To resolve this just put curly braces around the props.

export default function Hero({ children, hero }) {
    return (
        <header className={hero}>

Angular2 set value for formGroup

As pointed out in comments, this feature wasn't supported at the time this question was asked. This issue has been resolved in angular 2 rc5

Testing the type of a DOM element in JavaScript

I usually get it from the toString() return value. It works in differently accessed DOM elements:

var a = document.querySelector('a');

var img = document.createElement('img');

document.body.innerHTML += '<div id="newthing"></div>';
var div = document.getElementById('newthing');;    // "[object HTMLAnchorElement]";  // "[object HTMLImageElement]";  // "[object HTMLDivElement]"

Then the relevant piece:' ')[1].slice(0, -1);

It works in Chrome, FF, Opera, Edge, IE9+ (in older IE it return "[object Object]").

Regular expression to match a dot

This expression,


might also work OK for those specific types of input strings.



import re

expression = r'(?<=^|\s)[^.\s]+\.[^.\s]+(?=@)'
string = '''
blah blah blah [email protected] blah blah
blah blah blah test.this blah blah
blah blah blah [email protected] blah blah

matches = re.findall(expression, string)




If you wish to simplify/modify/explore the expression, it's been explained on the top right panel of If you'd like, you can also watch in this link, how it would match against some sample inputs.

Eclipse: Error ".. overlaps the location of another project.." when trying to create new project

Go to the actual FILE menu and create a new general project.

If the project type isn't recognized, preventing one of these import methods from working, then try this. Once you add the generic project, you can then add support for whatever language you require.

<embed> vs. <object>

Some other options:

<object type="application/pdf" data="filename.pdf" width="100%" height="100%">

<object type="application/pdf" data="#request.localhost#_includes/filename.pdf" 
        width="100%" height="100%">
  <param name="src" value="#request.localhost#_includes/filename.pdf">

how do I initialize a float to its max/min value?

You can either use -FLT_MAX (or -DBL_MAX) for the maximum magnitude negative number and FLT_MAX (or DBL_MAX) for positive. This gives you the range of possible float (or double) values.

You probably don't want to use FLT_MIN; it corresponds to the smallest magnitude positive number that can be represented with a float, not the most negative value representable with a float.

FLT_MIN and FLT_MAX correspond to std::numeric_limits<float>::min() and std::numeric_limits<float>::max().

How to connect to a remote Windows machine to execute commands using python?

pypsrp - Python PowerShell Remoting Protocol Client library

At a basic level, you can use this library to;

Execute a cmd command
Run another executable
Execute PowerShell scripts
Copy a file from the localhost to the remote Windows host
Fetch a file from the remote Windows host to the localhost
Create a Runspace Pool that contains one or multiple PowerShell pipelines and execute them asynchronously
Support for a reference host base implementation of PSRP for interactive scripts


Split a List into smaller lists of N size

While plenty of the answers above do the job, they all fail horribly on a never ending sequence (or a really long sequence). The following is a completely on-line implementation which guarantees best time and memory complexity possible. We only iterate the source enumerable exactly once and use yield return for lazy evaluation. The consumer could throw away the list on each iteration making the memory footprint equal to that of the list w/ batchSize number of elements.

public static IEnumerable<List<T>> BatchBy<T>(this IEnumerable<T> enumerable, int batchSize)
    using (var enumerator = enumerable.GetEnumerator())
        List<T> list = null;
        while (enumerator.MoveNext())
            if (list == null)
                list = new List<T> {enumerator.Current};
            else if (list.Count < batchSize)
                yield return list;
                list = new List<T> {enumerator.Current};

        if (list?.Count > 0)
            yield return list;

EDIT: Just now realizing the OP asks about breaking a List<T> into smaller List<T>, so my comments regarding infinite enumerables aren't applicable to the OP, but may help others who end up here. These comments were in response to other posted solutions that do use IEnumerable<T> as an input to their function, yet enumerate the source enumerable multiple times.

Proper way to declare custom exceptions in modern Python?

Maybe I missed the question, but why not:

class MyException(Exception):

Edit: to override something (or pass extra args), do this:

class ValidationError(Exception):
    def __init__(self, message, errors):

        # Call the base class constructor with the parameters it needs
        super(ValidationError, self).__init__(message)

        # Now for your custom code...
        self.errors = errors

That way you could pass dict of error messages to the second param, and get to it later with e.errors

Python 3 Update: In Python 3+, you can use this slightly more compact use of super():

class ValidationError(Exception):
    def __init__(self, message, errors):

        # Call the base class constructor with the parameters it needs

        # Now for your custom code...
        self.errors = errors

Understanding ibeacon distancing

I'm very thoroughly investigating the matter of accuracy/rssi/proximity with iBeacons and I really really think that all the resources in the Internet (blogs, posts in StackOverflow) get it wrong.

davidgyoung (accepted answer, > 100 upvotes) says:

Note that the term "accuracy" here is iOS speak for distance in meters.

Actually, most people say this but I have no idea why! Documentation makes it very very clear that CLBeacon.proximity:

Indicates the one sigma horizontal accuracy in meters. Use this property to differentiate between beacons with the same proximity value. Do not use it to identify a precise location for the beacon. Accuracy values may fluctuate due to RF interference.

Let me repeat: one sigma accuracy in meters. All 10 top pages in google on the subject has term "one sigma" only in quotation from docs, but none of them analyses the term, which is core to understand this.

Very important is to explain what is actually one sigma accuracy. Following URLs to start with:,

In physical world, when you make some measurement, you always get different results (because of noise, distortion, etc) and very often results form Gaussian distribution. There are two main parameters describing Gaussian curve:

  1. mean (which is easy to understand, it's value for which peak of the curve occurs).
  2. standard deviation, which says how wide or narrow the curve is. The narrower curve, the better accuracy, because all results are close to each other. If curve is wide and not steep, then it means that measurements of the same phenomenon differ very much from each other, so measurement has a bad quality.

one sigma is another way to describe how narrow/wide is gaussian curve.
It simply says that if mean of measurement is X, and one sigma is s, then 68% of all measurements will be between X - s and X + s.

Example. We measure distance and get a gaussian distribution as a result. The mean is 10m. If s is 4m, then it means that 68% of measurements were between 6m and 14m.

When we measure distance with beacons, we get RSSI and 1-meter calibration value, which allow us to measure distance in meters. But every measurement gives different values, which form gaussian curve. And one sigma (and accuracy) is accuracy of the measurement, not distance!

It may be misleading, because when we move beacon further away, one sigma actually increases because signal is worse. But with different beacon power-levels we can get totally different accuracy values without actually changing distance. The higher power, the less error.

There is a blog post which thoroughly analyses the matter:

Author has a hypothesis that accuracy is actually distance. He claims that beacons from are faulty beacuse when he increased power to the max value, accuracy value was very small for 1, 5 and even 15 meters. Before increasing power, accuracy was quite close to the distance values. I personally think that it's correct, because the higher power level, the less impact of interference. And it's strange why Estimote beacons don't behave this way.

I'm not saying I'm 100% right, but apart from being iOS developer I have degree in wireless electronics and I think that we shouldn't ignore "one sigma" term from docs and I would like to start discussion about it.

It may be possible that Apple's algorithm for accuracy just collects recent measurements and analyses the gaussian distribution of them. And that's how it sets accuracy. I wouldn't exclude possibility that they use info form accelerometer to detect whether user is moving (and how fast) in order to reset the previous distribution distance values because they have certainly changed.

How to get images in Bootstrap's card to be the same height/width?

I solved this problem using Bootstrap 4 Emdeds Utilities

In this case you just need to add you image to a div.embbed-responsive like this:

<div class="card">
  <div class="embed-responsive embed-responsive-16by9">
     <img alt="Card image cap" class="card-img-top embed-responsive-item" src="img/butterPecan.jpg" />
  <div class="card-block">
    <h4 class="card-title">Butter Pecan</h4>
    <p class="card-text">Roasted pecans, butter and vanilla come together to make this wonderful ice cream</p>

All images will fit the ratio specified by modifier classes:

  • .embed-responsive-21by9
  • .embed-responsive-16by9
  • .embed-responsive-4by3
  • .embed-responsive-1by1

Aditionally this css enables zoom instead of image stretching

.embed-responsive .card-img-top {
    object-fit: cover;

Illegal string offset Warning PHP

It works to me:

Testing Code of mine:

$var2['data'] = array ('a'=>'21','b'=>'32','c'=>'55','d'=>'66','e'=>'77');
foreach($var2 as $result)
    $test = $result['c'];

Output: 55

Check it guys. Thanks

Java "user.dir" property - what exactly does it mean?

System.getProperty("user.dir") fetches the directory or path of the workspace for the current project

Why is “while ( !feof (file) )” always wrong?

I'd like to provide an abstract, high-level perspective.

Concurrency and simultaneity

I/O operations interact with the environment. The environment is not part of your program, and not under your control. The environment truly exists "concurrently" with your program. As with all things concurrent, questions about the "current state" don't make sense: There is no concept of "simultaneity" across concurrent events. Many properties of state simply don't exist concurrently.

Let me make this more precise: Suppose you want to ask, "do you have more data". You could ask this of a concurrent container, or of your I/O system. But the answer is generally unactionable, and thus meaningless. So what if the container says "yes" – by the time you try reading, it may no longer have data. Similarly, if the answer is "no", by the time you try reading, data may have arrived. The conclusion is that there simply is no property like "I have data", since you cannot act meaningfully in response to any possible answer. (The situation is slightly better with buffered input, where you might conceivably get a "yes, I have data" that constitutes some kind of guarantee, but you would still have to be able to deal with the opposite case. And with output the situation is certainly just as bad as I described: you never know if that disk or that network buffer is full.)

So we conclude that it is impossible, and in fact unreasonable, to ask an I/O system whether it will be able to perform an I/O operation. The only possible way we can interact with it (just as with a concurrent container) is to attempt the operation and check whether it succeeded or failed. At that moment where you interact with the environment, then and only then can you know whether the interaction was actually possible, and at that point you must commit to performing the interaction. (This is a "synchronisation point", if you will.)


Now we get to EOF. EOF is the response you get from an attempted I/O operation. It means that you were trying to read or write something, but when doing so you failed to read or write any data, and instead the end of the input or output was encountered. This is true for essentially all the I/O APIs, whether it be the C standard library, C++ iostreams, or other libraries. As long as the I/O operations succeed, you simply cannot know whether further, future operations will succeed. You must always first try the operation and then respond to success or failure.


In each of the examples, note carefully that we first attempt the I/O operation and then consume the result if it is valid. Note further that we always must use the result of the I/O operation, though the result takes different shapes and forms in each example.

  • C stdio, read from a file:

      for (;;) {
          size_t n = fread(buf, 1, bufsize, infile);
          consume(buf, n);
          if (n == 0) { break; }

The result we must use is n, the number of elements that were read (which may be as little as zero).

  • C stdio, scanf:

      for (int a, b, c; scanf("%d %d %d", &a, &b, &c) == 3; ) {
          consume(a, b, c);

The result we must use is the return value of scanf, the number of elements converted.

  • C++, iostreams formatted extraction:

      for (int n; std::cin >> n; ) {

The result we must use is std::cin itself, which can be evaluated in a boolean context and tells us whether the stream is still in the good() state.

  • C++, iostreams getline:

      for (std::string line; std::getline(std::cin, line); ) {

The result we must use is again std::cin, just as before.

  • POSIX, write(2) to flush a buffer:

      char const * p = buf;
      ssize_t n = bufsize;
      for (ssize_t k = bufsize; (k = write(fd, p, n)) > 0; p += k, n -= k) {}
      if (n != 0) { /* error, failed to write complete buffer */ }

The result we use here is k, the number of bytes written. The point here is that we can only know how many bytes were written after the write operation.

  • POSIX getline()

      char *buffer = NULL;
      size_t bufsiz = 0;
      ssize_t nbytes;
      while ((nbytes = getline(&buffer, &bufsiz, fp)) != -1)
          /* Use nbytes of data in buffer */

    The result we must use is nbytes, the number of bytes up to and including the newline (or EOF if the file did not end with a newline).

    Note that the function explicitly returns -1 (and not EOF!) when an error occurs or it reaches EOF.

You may notice that we very rarely spell out the actual word "EOF". We usually detect the error condition in some other way that is more immediately interesting to us (e.g. failure to perform as much I/O as we had desired). In every example there is some API feature that could tell us explicitly that the EOF state has been encountered, but this is in fact not a terribly useful piece of information. It is much more of a detail than we often care about. What matters is whether the I/O succeeded, more-so than how it failed.

  • A final example that actually queries the EOF state: Suppose you have a string and want to test that it represents an integer in its entirety, with no extra bits at the end except whitespace. Using C++ iostreams, it goes like this:

      std::string input = "   123   ";   // example
      std::istringstream iss(input);
      int value;
      if (iss >> value >> std::ws && iss.get() == EOF) {
      } else {
          // error, "input" is not parsable as an integer

We use two results here. The first is iss, the stream object itself, to check that the formatted extraction to value succeeded. But then, after also consuming whitespace, we perform another I/O/ operation, iss.get(), and expect it to fail as EOF, which is the case if the entire string has already been consumed by the formatted extraction.

In the C standard library you can achieve something similar with the strto*l functions by checking that the end pointer has reached the end of the input string.

The answer

while(!feof) is wrong because it tests for something that is irrelevant and fails to test for something that you need to know. The result is that you are erroneously executing code that assumes that it is accessing data that was read successfully, when in fact this never happened.

Make one div visible and another invisible

You can use the display property of style. Intialy set the result section style as

style = "display:none"

Then the div will not be visible and there won't be any white space.

Once the search results are being populated change the display property using the java script like

document.getElementById("someObj").style.display = "block"

Using java script you can make the div invisible

document.getElementById("someObj").style.display = "none"

Can regular JavaScript be mixed with jQuery?

You can, but be aware of the return types with jQuery functions. jQuery won't always use the exact same JavaScript object type, although generally they will return subclasses of what you would expect to be returned from a similar JavaScript function.

Check if table exists in SQL Server

For queries like this it is always best to use an INFORMATION_SCHEMA view. These views are (mostly) standard across many different databases and rarely change from version to version.

To check if a table exists use:

                 WHERE TABLE_SCHEMA = 'TheSchema' 
                 AND  TABLE_NAME = 'TheTable'))
    --Do Stuff

"SSL certificate verify failed" using pip to install packages

If you're using python3, you can try this too:

python3 -m pip install --upgrade Scrapy --trusted-host --trusted-host

HTML character codes for this ? or this ?

&#9650; is the Unicode black up-pointing triangle (?) while &#9660; is the black down-pointing triangle (?).

You can just plug the characters (copied from the web) into this site for a lookup.

'dict' object has no attribute 'has_key'

I think it is considered "more pythonic" to just use in when determining if a key already exists, as in

if start not in graph:
    return None

jquery smooth scroll to an anchor?


$('a[href*=#]').each(function () {
    $(this).attr('href', $(this).attr('href').replace('#', '#_'));
    $(this).on( "click", function() {

        var hashname = $(this).attr('href').replace('#_', '');

        if($(this).attr('href') == "#_") {
            $('html, body').animate({ scrollTop: 0 }, 300);
        else {
            var target = $('a[name="' + hashname + '"], #' + hashname),
                targetOffset = target.offset().top;
            if(targetOffset >= 1) {
                $('html, body').animate({ scrollTop: targetOffset-60 }, 300);

Intellisense and code suggestion not working in Visual Studio 2012 Ultimate RC

It got frustrating for me as well but I figured out my own answer. Restarting did help but I found why I ran into trouble: I'd copied and pasted an ASP Panel with controls I'd need to re-use. I only had those in the first Div tag working. All others needed to be set up, so I said "Aha ... let me comment out the remaining Div Tags that aren't set up ..." and sure enough, intellisense came right back on.

So not only will it fail to work if the cursor is below a code error but it can fail to work if you're a copy / paste type like me.

Why this line xmlns:android="" must be the first in the layout xml file?

I think it makes clear with the namespace, as we can create our own attributes and if the user specified attribute is the same as the Android one it avoid the conflict of the namespace.

Printing leading 0's in C

You will save yourself a heap of trouble (long term) if you store a ZIP Code as a character string, which it is, rather than a number, which it is not.

How do you turn a Mongoose document into a plain object?

the fast way if the property is not in the model :

document.set( key,value, { strict: false });

Access camera from a browser

As of 2017, WebKit announces support for WebRTC on Safari

Now you can access them with video and standard javascript WebRTC


var video = document.createElement('video');
video.setAttribute('playsinline', '');
video.setAttribute('autoplay', '');
video.setAttribute('muted', ''); = '200px'; = '200px';

/* Setting up the constraint */
var facingMode = "user"; // Can be 'user' or 'environment' to access back or front camera (NEAT!)
var constraints = {
  audio: false,
  video: {
   facingMode: facingMode

/* Stream it to video element */
navigator.mediaDevices.getUserMedia(constraints).then(function success(stream) {
  video.srcObject = stream;

Have a play with it.

If statement with String comparison fails

You can use



if("/quit".compareTo(s) == 0) 

The latter makes a lexicographic comparison, and will return 0 if the two strings are the same.

jQuery click event on radio button doesn't get fired

It fires. Check demo

$("#inline_content input[name='type']").click(function(){
    alert('You clicked radio!');
    if($('input:radio[name=type]:checked').val() == "walk_in"){
        //$('#select-table > .roomNumber').attr('enabled',false);

How do I alias commands in git?

I created the alias dog for showing the log graph:

git config --global "log --all --decorate --oneline --graph"

And use it as follows:

git dog

Compiling an application for use in highly radioactive environments

Firstly, design your application around failure. Ensure that as part of normal flow operation, it expects to reset (depending on your application and the type of failure either soft or hard). This is hard to get perfect: critical operations that require some degree of transactionality may need to be checked and tweaked at an assembly level so that an interruption at a key point cannot result in inconsistent external commands. Fail fast as soon as any unrecoverable memory corruption or control flow deviation is detected. Log failures if possible.

Secondly, where possible, correct corruption and continue. This means checksumming and fixing constant tables (and program code if you can) often; perhaps before each major operation or on a timed interrupt, and storing variables in structures that autocorrect (again before each major op or on a timed interrupt take a majority vote from 3 and correct if is a single deviation). Log corrections if possible.

Thirdly, test failure. Set up a repeatable test environment that flips bits in memory psuedo-randomly. This will allow you to replicate corruption situations and help design your application around them.

What's the difference between ng-model and ng-bind

tosh's answer gets to the heart of the question nicely. Here's some additional information....

Filters & Formatters

ng-bind and ng-model both have the concept of transforming data before outputting it for the user. To that end, ng-bind uses filters, while ng-model uses formatters.

filter (ng-bind)

With ng-bind, you can use a filter to transform your data. For example,

<div ng-bind="mystring | uppercase"></div>,

or more simply:

<div>{{mystring | uppercase}}</div>

Note that uppercase is a built-in angular filter, although you can also build your own filter.

formatter (ng-model)

To create an ng-model formatter, you create a directive that does require: 'ngModel', which allows that directive to gain access to ngModel's controller. For example:

app.directive('myModelFormatter', function() {
  return {
    require: 'ngModel',
    link: function(scope, element, attrs, controller) {
     controller.$formatters.push(function(value) {
        return value.toUpperCase();

Then in your partial:

<input ngModel="mystring" my-model-formatter />

This is essentially the ng-model equivalent of what the uppercase filter is doing in the ng-bind example above.


Now, what if you plan to allow the user to change the value of mystring? ng-bind only has one way binding, from model-->view. However, ng-model can bind from view-->model which means that you may allow the user to change the model's data, and using a parser you can format the user's data in a streamlined manner. Here's what that looks like:

app.directive('myModelFormatter', function() {
  return {
    require: 'ngModel',
    link: function(scope, element, attrs, controller) {
     controller.$parsers.push(function(value) {
        return value.toLowerCase();

Play with a live plunker of the ng-model formatter/parser examples

What Else?

ng-model also has built-in validation. Simply modify your $parsers or $formatters function to call ngModel's controller.$setValidity(validationErrorKey, isValid) function.

Angular 1.3 has a new $validators array which you can use for validation instead of $parsers or $formatters.

Angular 1.3 also has getter/setter support for ngModel

Traverse all the Nodes of a JSON Object Tree with JavaScript

We use object-scan for many data processing tasks. It's powerful once you wrap your head around it. Here is how you could do basic traversal

// const objectScan = require('object-scan');

const obj = { foo: 'bar', arr: [1, 2, 3], subo: { foo2: 'bar2' } };

objectScan(['**'], {
  reverse: false,
  filterFn: ({ key, value }) => {
    console.log(key, value);
// => [ 'foo' ] bar
// => [ 'arr', 0 ] 1
// => [ 'arr', 1 ] 2
// => [ 'arr', 2 ] 3
// => [ 'arr' ] [ 1, 2, 3 ]
// => [ 'subo', 'foo2' ] bar2
// => [ 'subo' ] { foo2: 'bar2' }
.as-console-wrapper {max-height: 100% !important; top: 0}
<script src="[email protected]"></script>

Disclaimer: I'm the author of object-scan

jQuery return ajax result into outside variable

Using 'async': false to prevent asynchronous code is a bad practice,

Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience.

On the surface setting async to false fixes a lot of issues because, as the other answers show, you get your data into a variable. However, while waiting for the post data to return (which in some cases could take a few seconds because of database calls, slow connections, etc.) the rest of your Javascript functionality (like triggered events, Javascript handled buttons, JQuery transitions (like accordion, or autocomplete (JQuery UI)) will not be able to occur while the response is pending (which is really bad if the response never comes back as your site is now essentially frozen).

Try this instead,

var return_first;
function callback(response) {
  return_first = response;
  //use return_first variable here

  'type': "POST",
  'global': false,
  'dataType': 'html',
  'url': "ajax.php?first",
  'data': { 'request': "", 'target': arrange_url, 'method': method_target },
  'success': function(data){

What is the difference between %g and %f in C?

As Unwind points out f and g provide different default outputs.

Roughly speaking if you care more about the details of what comes after the decimal point I would do with f and if you want to scale for large numbers go with g. From some dusty memories f is very nice with small values if your printing tables of numbers as everything stays lined up but something like g is needed if you stand a change of your numbers getting large and your layout matters. e is more useful when your numbers tend to be very small or very large but never near ten.

An alternative is to specify the output format so that you get the same number of characters representing your number every time.

Sorry for the woolly answer but it is a subjective out put thing that only gets hard answers if the number of characters generated is important or the precision of the represented value.

Copy files to network computers on windows command line

Why for? What do you want to iterate? Try this.

call :cpy pc-name-1
call :cpy pc-name-2

net use \\%1\{destfolder} {password} /user:{username}
copy {file} \\%1\{destfolder}
goto :EOF

How to make JavaScript execute after page load?

Using the YUI library (I love it):

    //your code

Portable and beautiful! However, if you don't use YUI for other stuff (see its doc) I would say that it's not worth to use it.

N.B. : to use this code you need to import 2 scripts

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

Create SQLite Database and table

The next link will bring you to a great tutorial, that helped me a lot!

How to SQLITE in C#

I nearly used everything in that article to create the SQLite database for my own C# Application.

Don't forget to download the SQLite.dll, and add it as a reference to your project. This can be done using NuGet and by adding the dll manually.

After you added the reference, refer to the dll from your code using the following line on top of your class:

using System.Data.SQLite;

You can find the dll's here:

SQLite DLL's

You can find the NuGet way here:


Up next is the create script. Creating a database file:


SQLiteConnection m_dbConnection = new SQLiteConnection("Data Source=MyDatabase.sqlite;Version=3;");

string sql = "create table highscores (name varchar(20), score int)";

SQLiteCommand command = new SQLiteCommand(sql, m_dbConnection);

sql = "insert into highscores (name, score) values ('Me', 9001)";

command = new SQLiteCommand(sql, m_dbConnection);


After you created a create script in C#, I think you might want to add rollback transactions, it is safer and it will keep your database from failing, because the data will be committed at the end in one big piece as an atomic operation to the database and not in little pieces, where it could fail at 5th of 10 queries for example.

Example on how to use transactions:

 using (TransactionScope tran = new TransactionScope())
     //Insert create script here.

     //Indicates that creating the SQLiteDatabase went succesfully, so the database can be committed.

Java, How to implement a Shift Cipher (Caesar Cipher)

Hello...I have created a java client server application in swing for caesar cipher...I have created a new formula that can decrypt the text properly... sorry only for lower case..!

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;

public class ceasarserver extends JFrame implements ActionListener {
    static String cs = "abcdefghijklmnopqrstuvwxyz";
    static JLabel l1, l2, l3, l5, l6;
    JTextField t1;
    JButton close, b1;
    static String en;
    int num = 0;
    JProgressBar progress;

    ceasarserver() {
        JPanel p = new JPanel(new GridLayout(10, 1));
        l1 = new JLabel("");
        l2 = new JLabel("");
        l3 = new JLabel("");
        l5 = new JLabel("");
        l6 = new JLabel("Enter the Key...");
        t1 = new JTextField(30);
        progress = new JProgressBar(0, 20);
        close = new JButton("Close");
        close.setPreferredSize(new Dimension(300, 25));
        b1 = new JButton("Decrypt");

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == close)
        else if (e.getSource() == b1) {
            int key = Integer.parseInt(t1.getText());
            String d = "";
            int i = 0, j, k;
            while (i < en.length()) {
                j = cs.indexOf(en.charAt(i));
                k = (j + (26 - key)) % 26;
                d = d + cs.charAt(k);
            while (num < 21) {
                try {
                } catch (InterruptedException ex) {
                Rectangle progressRect = progress.getBounds();
                progressRect.x = 0;
                progressRect.y = 0;
            l5.setText("Decrypted text: " + d);

    public static void main(String args[]) throws IOException {
        new ceasarserver();
        String strm = new String();
        ServerSocket ss = new ServerSocket(4321);
        l1.setText("Secure data transfer Server Started....");
        Socket s = ss.accept();
        l2.setText("Client Connected !");
        while (true) {
            Scanner br1 = new Scanner(s.getInputStream());
            en = br1.nextLine();
            l3.setText("Client:" + en);

The client class:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;

public class ceasarclient extends JFrame {
    String cs = "abcdefghijklmnopqrstuvwxyz";
    static JLabel l1, l2, l3, l4, l5;
    JButton b1, b2, b3;
    JTextField t1, t2;
    JProgressBar progress;
    int num = 0;
    String en = "";

    ceasarclient(final Socket s) {
        JPanel p = new JPanel(new GridLayout(10, 1));
        setSize(500, 500);
        t1 = new JTextField(30);
        b1 = new JButton("Send");
        b2 = new JButton("Close");
        l1 = new JLabel("Welcome to Secure Data transfer!");
        l2 = new JLabel("Enter the word here...");
        l3 = new JLabel("");
        l4 = new JLabel("Enter the Key:");
        b3 = new JButton("Encrypt");
        t2 = new JTextField(30);
        progress = new JProgressBar(0, 20);
        b1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                try {
                    PrintWriter pw = new PrintWriter(s.getOutputStream(), true);
                } catch (Exception ex) {
                l3.setText("Encrypted Text Sent.");
        b3.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String strw = t1.getText();
                int key = Integer.parseInt(t2.getText());
                int i = 0, j, k;
                while (i < strw.length()) {
                    j = cs.indexOf(strw.charAt(i));
                    k = (j + key) % 26;
                    en = en + cs.charAt(k);
                while (num < 21) {
                    try {
                    } catch (InterruptedException exe) {
                    Rectangle progressRect = progress.getBounds();
                    progressRect.x = 0;
                    progressRect.y = 0;
        b2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

    public static void main(String args[]) throws IOException {
        final Socket s = new Socket(InetAddress.getLocalHost(), 4321);
        new ceasarclient(s);

Get all attributes of an element using jQuery

Here is an overview of the many ways that can be done, for my own reference as well as yours :) The functions return a hash of attribute names and their values.

Vanilla JS:

function getAttributes ( node ) {
    var i,
        attributeNodes = node.attributes,
        length = attributeNodes.length,
        attrs = {};

    for ( i = 0; i < length; i++ ) attrs[attributeNodes[i].name] = attributeNodes[i].value;
    return attrs;

Vanilla JS with Array.reduce

Works for browsers supporting ES 5.1 (2011). Requires IE9+, does not work in IE8.

function getAttributes ( node ) {
    var attributeNodeArray = node.attributes );

    return attributeNodeArray.reduce( function ( attrs, attribute ) {
        attrs[] = attribute.value;
        return attrs;
    }, {} );


This function expects a jQuery object, not a DOM element.

function getAttributes ( $node ) {
    var attrs = {};
    $.each( $node[0].attributes, function ( index, attribute ) {
        attrs[] = attribute.value;
    } );

    return attrs;


Also works for lodash.

function getAttributes ( node ) {
    return _.reduce( node.attributes, function ( attrs, attribute ) {
        attrs[] = attribute.value;
        return attrs;
    }, {} );


Is even more concise than the Underscore version, but only works for lodash, not for Underscore. Requires IE9+, is buggy in IE8. Kudos to @AlJey for that one.

function getAttributes ( node ) {
    return _.transform( node.attributes, function ( attrs, attribute ) {
        attrs[] = attribute.value;
    }, {} );

Test page

At JS Bin, there is a live test page covering all these functions. The test includes boolean attributes (hidden) and enumerated attributes (contenteditable="").

Check that a input to UITextField is numeric only

#pragma mark - UItextfield Delegate

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if ([string isEqualToString:@"("]||[string isEqualToString:@")"]) {
        return TRUE;

    NSLog(@"Range ==%d  ,%d",range.length,range.location);
    //NSRange *CURRANGE = [NSString  rangeOfString:string];

    if (range.location == 0 && range.length == 0) {
        if ([string isEqualToString:@"+"]) {
            return TRUE;
    return [self isNumeric:string];

    BOOL isValid = NO;
    NSCharacterSet *alphaNumbersSet = [NSCharacterSet decimalDigitCharacterSet];
    NSCharacterSet *stringSet = [NSCharacterSet characterSetWithCharactersInString:inputString];
    isValid = [alphaNumbersSet isSupersetOfSet:stringSet];
    return isValid;

What causes a Python segmentation fault?

Looks like you are out of stack memory. You may want to increase it as Davide stated. To do it in python code, you would need to run your "main()" using threading:

def main():
    pass # write your code here

sys.setrecursionlimit(2097152)    # adjust numbers
threading.stack_size(134217728)   # for your needs

main_thread = threading.Thread(target=main)

Source: c1729's post on codeforces. Runing it with PyPy is a bit trickier.

Type definition in object literal in TypeScript

// Use ..

const Per = {
  name: 'HAMZA',
  age: 20,
  coords: {
    tele: '09',
    lan: '190'
  setAge(age: Number): void {
    this.age = age;
  getAge(): Number {
    return age;
const { age, name }: { age: Number; name: String } = Per;
const {
  coords: { tele, lan }
}: { coords: { tele: String; lan: String } } = Per;


stop service in android

To stop the service we must use the method stopService():

  Intent myService = new Intent(MainActivity.this, BackgroundSoundService.class);

then the method onDestroy() in the service is called:

    public void onDestroy() {

        Log.i(TAG, "onCreate() , service stopped...");

Here is a complete example including how to stop the service.

How to disable Home and other system buttons in Android?

If you target android 5.0 and above. You could use:


Convert to absolute value in Objective-C

You can use this function to get the absolute value:

+(NSNumber *)absoluteValue:(NSNumber *)input {
  return [NSNumber numberWithDouble:fabs([input doubleValue])];

self referential struct definition?

In C, you cannot reference the typedef that you're creating withing the structure itself. You have to use the structure name, as in the following test program:

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

typedef struct Cell {
  int cellSeq;
  struct Cell* next; /* 'tCell *next' will not work here */
} tCell;

int main(void) {
    int i;
    tCell *curr;
    tCell *first;
    tCell *last;

    /* Construct linked list, 100 down to 80. */

    first = malloc (sizeof (tCell));
    last = first;
    first->cellSeq = 100;
    first->next = NULL;
    for (i = 0; i < 20; i++) {
        curr = malloc (sizeof (tCell));
        curr->cellSeq = last->cellSeq - 1;
        curr->next = NULL;
        last->next = curr;
        last = curr;

    /* Walk the list, printing sequence numbers. */

    curr = first;
    while (curr != NULL) {
        printf ("Sequence = %d\n", curr->cellSeq);
        curr = curr->next;

    return 0;

Although it's probably a lot more complicated than this in the standard, you can think of it as the compiler knowing about struct Cell on the first line of the typedef but not knowing about tCell until the last line :-) That's how I remember that rule.

From io.Reader to string in Go

The most efficient way would be to always use []byte instead of string.

In case you need to print data received from the io.ReadCloser, the fmt package can handle []byte, but it isn't efficient because the fmt implementation will internally convert []byte to string. In order to avoid this conversion, you can implement the fmt.Formatter interface for a type like type ByteSlice []byte.

How to make an introduction page with Doxygen

Following syntax may help for adding a main page and related subpages for doxygen:

/*! \mainpage Drawing Shapes
 * This project helps user to draw shapes.
 * Currently two types of shapes can be drawn:
 * - \subpage drawingRectanglePage "How to draw rectangle?"
 * - \subpage drawingCirclePage "How to draw circle?"

/*! \page drawingRectanglePage How to draw rectangle?
 * Lorem ipsum dolor sit amet

/*! \page drawingCirclePage How to draw circle?
 * This page is about how to draw a circle.
 * Following sections describe circle:
 * - \ref groupCircleDefinition "Definition of Circle"
 * - \ref groupCircleClass "Circle Class"

Creating groups as following also help for designing pages:

/** \defgroup groupCircleDefinition Circle Definition
 * A circle is a simple shape in Euclidean geometry.
 * It is the set of all points in a plane that are at a given distance from a given point, the centre;
 * equivalently it is the curve traced out by a point that moves so that its distance from a given point is constant.
 * The distance between any of the points and the centre is called the radius.

An example can be found here

mysql delete under safe mode

You can trick MySQL into thinking you are actually specifying a primary key column. This allows you to "override" safe mode.

Assuming you have a table with an auto-incrementing numeric primary key, you could do the following:


Parenthesis/Brackets Matching using Stack algorithm

Algorithm to use for checking well balanced parenthesis -

  1. Declare a map matchingParenMap and initialize it with closing and opening bracket of each type as the key-value pair respectively.
  2. Declare a set openingParenSet and initialize it with the values of matchingParenMap.
  3. Declare a stack parenStack which will store the opening brackets '{', '(', and '['.
  4. Now traverse the string expression input.

    1. If the current character is an opening bracket ( '{', '(', '[' ) then push it to the parenStack.

    2. If the current character is a closing bracket ( '}', ')', ']' ) then pop from parenStack and if the popped character is equal to the matching starting bracket in matchingParenMap then continue looping else return false.

  5. After complete traversal if no opening brackets are left in parenStack it means it is a well balanced expression.

I have explained the code snippet of the algorithm used on my blog. Check link -

How can I split a text into sentences?

Here is a middle of the road approach that doesn't rely on any external libraries. I use list comprehension to exclude overlaps between abbreviations and terminators as well as to exclude overlaps between variations on terminations, for example: '.' vs. '."'

abbreviations = {'dr.': 'doctor', 'mr.': 'mister', 'bro.': 'brother', 'bro': 'brother', 'mrs.': 'mistress', 'ms.': 'miss', 'jr.': 'junior', 'sr.': 'senior',
                 'i.e.': 'for example', 'e.g.': 'for example', 'vs.': 'versus'}
terminators = ['.', '!', '?']
wrappers = ['"', "'", ')', ']', '}']

def find_sentences(paragraph):
   end = True
   sentences = []
   while end > -1:
       end = find_sentence_end(paragraph)
       if end > -1:
           paragraph = paragraph[:end]
   return sentences

def find_sentence_end(paragraph):
    [possible_endings, contraction_locations] = [[], []]
    contractions = abbreviations.keys()
    sentence_terminators = terminators + [terminator + wrapper for wrapper in wrappers for terminator in terminators]
    for sentence_terminator in sentence_terminators:
        t_indices = list(find_all(paragraph, sentence_terminator))
        possible_endings.extend(([] if not len(t_indices) else [[i, len(sentence_terminator)] for i in t_indices]))
    for contraction in contractions:
        c_indices = list(find_all(paragraph, contraction))
        contraction_locations.extend(([] if not len(c_indices) else [i + len(contraction) for i in c_indices]))
    possible_endings = [pe for pe in possible_endings if pe[0] + pe[1] not in contraction_locations]
    if len(paragraph) in [pe[0] + pe[1] for pe in possible_endings]:
        max_end_start = max([pe[0] for pe in possible_endings])
        possible_endings = [pe for pe in possible_endings if pe[0] != max_end_start]
    possible_endings = [pe[0] + pe[1] for pe in possible_endings if sum(pe) > len(paragraph) or (sum(pe) < len(paragraph) and paragraph[sum(pe)] == ' ')]
    end = (-1 if not len(possible_endings) else max(possible_endings))
    return end

def find_all(a_str, sub):
    start = 0
    while True:
        start = a_str.find(sub, start)
        if start == -1:
        yield start
        start += len(sub)

I used Karl's find_all function from this entry: Find all occurrences of a substring in Python

add new row in gridview after binding C#,

If you are using dataset to bind in a Grid, you can add the row after you fill in the sql data adapter:


Get combobox value in Java swing

If the string is empty, comboBox.getSelectedItem().toString() will give a NullPointerException. So better to typecast by (String).