Programs & Examples On #Design rationale

How to split a string into an array in Bash?

Since there are so many ways to solve this, let's start by defining what we want to see in our solution.

  1. Bash provides a builtin readarray for this purpose. Let's use it.
  2. Avoid ugly and unnecessary tricks such as changing IFS, looping, using eval, or adding an extra element then removing it.
  3. Find a simple, readable approach that can easily be adapted to similar problems.

The readarray command is easiest to use with newlines as the delimiter. With other delimiters it may add an extra element to the array. The cleanest approach is to first adapt our input into a form that works nicely with readarray before passing it in.

The input in this example does not have a multicharacter delimiter. If we apply a little common sense, it's best understood as comma separated input for which each element may need to be trimmed. My solution is to split the input by comma into multiple lines, trim each element, and pass it all to readarray.

string='  Paris,France  ,   All of Europe  '
readarray -t foo < <(tr ',' '\n' <<< "$string" |sed 's/^ *//' |sed 's/ *$//')
declare -p foo

# declare -a foo='([0]="Paris" [1]="France" [2]="All of Europe")'

How can I get a List from some class properties with Java 8 Stream?

You can use map :

List<String> names =


In order to combine the Lists of friend names, you need to use flatMap :

List<String> friendNames =

Programmatically obtain the phone number of the Android phone

TelephonyManager is not the right solution, because in some cases the number is not stored in the SIM. I suggest that you should use the shared preference to store the user's phone number for the first time the application is open and the number will used whenever you need.

Custom style to jquery ui dialogs

The solution only solves part of the problem, it may let you style the container and contents but doesn't let you change the titlebar. I developed a workaround of sorts but adding an id to the dialog div, then using jQuery .prev to change the style of the div which is the previous sibling of the dialog's div. This works because when jQueryUI creates the dialog, your original div becomes a sibling of the new container, but the title div is a the immediately previous sibling to your original div but neither the container not the title div has an id to simplify selecting the div.


<button id="dialog1" class="btn btn-danger">Warning</button>
<div title="Nothing here, really" id="nonmodal1">
  Nothing here

You can use CSS to style the main section of the dialog but not the title

.custom-ui-widget-header-warning {
  background: #EBCCCC;
  font-size: 1em;

You need some JS to style the title

$(function() {
                     minWidth: 400,
                     minHeight: 'auto',
                     autoOpen: false,
                     dialogClass: 'custom-ui-widget-header-warning',
                     position: {
                       my: 'center',
                       at: 'left'

                   $("#dialog1").click(function() {
                     if ($("#nonmodal1").dialog("isOpen") === true) {
                     } else {


The example only shows simple styling (background) but you can make it as complex as you wish.

You can see it in action here:

How do I grant myself admin access to a local SQL Server instance?

Here's a script that claims to be able to fix this.

Get admin rights to your local SQL Server Express with this simple script

Download link to the script


This command script allows you to easily add yourself to the sysadmin role of a local SQL Server instance. You must be a member of the Windows local Administrators group, or have access to the credentials of a user who is. The script supports SQL Server 2005 and later.

The script is most useful if you are a developer trying to use SQL Server 2008 Express that was installed by someone else. In this situation you usually won't have admin rights to the SQL Server 2008 Express instance, since by default only the person installing SQL Server 2008 is granted administrative privileges.

The user who installed SQL Server 2008 Express can use SQL Server Management Studio to grant the necessary privileges to you. But what if SQL Server Management Studio was not installed? Or worse if the installing user is not available anymore?

This script fixes the problem in just a few clicks!

Note: You will need to provide the BAT file with an 'Instance Name' (Probably going to be 'MSSQLSERVER' - but it might not be): you can get the value by first running the following in the "Microsoft SQL Server Management Console":

 SELECT @@servicename

Then copy the result to use when the BAT file prompts for 'SQL instance name'.

  @echo off 
    rem **************************************************************************** 
    rem    Copyright (c) Microsoft Corporation. All rights reserved. 
    rem    This code is licensed under the Microsoft Public License. 
    rem **************************************************************************** 
    rem CMD script to add a user to the SQL Server sysadmin role 
    rem Input:  %1 specifies the instance name to be modified. Defaults to SQLEXPRESS. 
    rem         %2 specifies the principal identity to be added (in the form "<domain>\<user>"). 
    rem            If omitted, the script will request elevation and add the current user (pre-elevation) to the sysadmin role. 
    rem            If provided explicitly, the script is assumed to be running elevated already. 
    rem Method: 1) restart the SQL service with the '-m' option, which allows a single connection from a box admin 
    rem            (the box admin is temporarily added to the sysadmin role with this start option) 
    rem         2) connect to the SQL instance and add the user to the sysadmin role 
    rem         3) restart the SQL service for normal connections 
    rem Output: Messages indicating success/failure. 
    rem         Note that if elevation is done by this script, a new command process window is created: the output of this 
    rem         window is not directly accessible to the caller. 
    set sqlresult=N/A 
    if .%1 == . (set /P sqlinstance=Enter SQL instance name, or default to SQLEXPRESS: ) else (set sqlinstance=%1) 
    if .%sqlinstance% == . (set sqlinstance=SQLEXPRESS) 
    if /I %sqlinstance% == MSSQLSERVER (set sqlservice=MSSQLSERVER) else (set sqlservice=MSSQL$%sqlinstance%) 
    if .%2 == . (set sqllogin="%USERDOMAIN%\%USERNAME%") else (set sqllogin=%2) 
    rem remove enclosing quotes 
    for %%i in (%sqllogin%) do set sqllogin=%%~i 
    @echo Adding '%sqllogin%' to the 'sysadmin' role on SQL Server instance '%sqlinstance%'. 
    @echo Verify the '%sqlservice%' service exists ... 
    set srvstate=0 
    for /F "usebackq tokens=1,3" %%i in (`sc query %sqlservice%`) do if .%%i == .STATE set srvstate=%%j 
    if .%srvstate% == .0 goto existerror 
    rem elevate if <domain/user> was defaulted 
    if NOT .%2 == . goto continue 
    echo new ActiveXObject("Shell.Application").ShellExecute("cmd.exe", "/D /Q /C pushd \""+WScript.Arguments(0)+"\" & \""+WScript.Arguments(1)+"\" %sqlinstance% \""+WScript.Arguments(2)+"\"", "", "runas"); >"%TEMP%\addsysadmin{7FC2CAE2-2E9E-47a0-ADE5-C43582022EA8}.js" 
    call "%TEMP%\addsysadmin{7FC2CAE2-2E9E-47a0-ADE5-C43582022EA8}.js" "%cd%" %0 "%sqllogin%" 
    del "%TEMP%\addsysadmin{7FC2CAE2-2E9E-47a0-ADE5-C43582022EA8}.js" 
    goto :EOF 
    rem determine if the SQL service is running 
    set srvstarted=0 
    set srvstate=0 
    for /F "usebackq tokens=1,3" %%i in (`sc query %sqlservice%`) do if .%%i == .STATE set srvstate=%%j 
    if .%srvstate% == .0 goto queryerror 
    rem if required, stop the SQL service 
    if .%srvstate% == .1 goto startm 
    set srvstarted=1 
    @echo Stop the '%sqlservice%' service ... 
    net stop %sqlservice% 
    if errorlevel 1 goto stoperror 
    rem start the SQL service with the '-m' option (single admin connection) and wait until its STATE is '4' (STARTED) 
    rem also use trace flags as follows: 
    rem     3659 - log all errors to errorlog 
    rem     4010 - enable shared memory only (lpc:) 
    rem     4022 - do not start autoprocs 
    @echo Start the '%sqlservice%' service in maintenance mode ... 
    sc start %sqlservice% -m -T3659 -T4010 -T4022 >nul 
    if errorlevel 1 goto startmerror 
    set srvstate=0 
    for /F "usebackq tokens=1,3" %%i in (`sc query %sqlservice%`) do if .%%i == .STATE set srvstate=%%j 
    if .%srvstate% == .0 goto queryerror 
    if .%srvstate% == .1 goto startmerror 
    if NOT .%srvstate% == .4 goto checkstate1 
    rem add the specified user to the sysadmin role 
    rem access tempdb to avoid a misleading shutdown error 
    @echo Add '%sqllogin%' to the 'sysadmin' role ... 
    for /F "usebackq tokens=1,3" %%i in (`sqlcmd -S np:\\.\pipe\SQLLocal\%sqlinstance% -E -Q "create table #foo (bar int); declare @rc int; execute @rc = sp_addsrvrolemember '$(sqllogin)', 'sysadmin'; print 'RETURN_CODE : '+CAST(@rc as char)"`) do if .%%i == .RETURN_CODE set sqlresult=%%j 
    rem stop the SQL service 
    @echo Stop the '%sqlservice%' service ... 
    net stop %sqlservice% 
    if errorlevel 1 goto stoperror 
    if .%srvstarted% == .0 goto exit 
    rem start the SQL service for normal connections 
    net start %sqlservice% 
    if errorlevel 1 goto starterror 
    goto exit 
    rem handle unexpected errors 
    sc query %sqlservice% 
    @echo '%sqlservice%' service is invalid 
    goto exit 
    @echo 'sc query %sqlservice%' failed 
    goto exit 
    @echo 'net stop %sqlservice%' failed 
    goto exit 
    @echo 'sc start %sqlservice% -m' failed 
    goto exit 
    @echo 'net start %sqlservice%' failed 
    goto exit 
    if .%sqlresult% == .0 (@echo '%sqllogin%' was successfully added to the 'sysadmin' role.) else (@echo '%sqllogin%' was NOT added to the 'sysadmin' role: SQL return code is %sqlresult%.) 

How to write a multiline Jinja statement

According to the documentation: you may use multi-line statements as long as the code has parens/brackets around it. Example:

{% if ( (foo == 'foo' or bar == 'bar') and 
        (fooo == 'fooo' or baar == 'baar') ) %}
    <li>some text</li>
{% endif %}

Edit: Using line_statement_prefix = '#'* the code would look like this:

# if ( (foo == 'foo' or bar == 'bar') and 
       (fooo == 'fooo' or baar == 'baar') )
    <li>some text</li>
# endif

*Here's an example of how you'd specify the line_statement_prefix in the Environment:

from jinja2 import Environment, PackageLoader, select_autoescape
env = Environment(
    loader=PackageLoader('yourapplication', 'templates'),
    autoescape=select_autoescape(['html', 'xml']),

Or using Flask:

from flask import Flask
app = Flask(__name__, instance_relative_config=True, static_folder='static')
app.jinja_env.filters['zip'] = zip
app.jinja_env.line_statement_prefix = '#'

Numpy: find index of the elements within range

a = np.array([1,2,3,4,5,6,7,8,9])
b = a[(a>2) & (a<8)]

Maximum packet size for a TCP connection

This is an excellent question and I run in to this a lot at work actually. There are a lot of "technically correct" answers such as 65k and 1500. I've done a lot of work writing network interfaces and using 65k is silly, and 1500 can also get you in to big trouble. My work goes on a lot of different hardware / platforms / routers, and to be honest the place I start is 1400 bytes. If you NEED more than 1400 you can start to inch your way up, you can probably go to 1450 and sometimes to 1480'ish? If you need more than that then of course you need to split in to 2 packets, of which there are several obvious ways of doing..

The problem is that you're talking about creating a data packet and writing it out via TCP, but of course there's header data tacked on and so forth, so you have "baggage" that puts you to 1500 or beyond.. and also a lot of hardware has lower limits.

If you "push it" you can get some really weird things going on. Truncated data, obviously, or dropped data I've seen rarely. Corrupted data also rarely but certainly does happen.

How to swap two variables in JavaScript

Till ES5, to swap two numbers, you have to create a temp variable and then swap it. But in ES6, its very easy to swap two numbers using array destructuring. See example.

let x,y;
console.log(x,y);      // return 2,3

console.log(x,y);      // return 3,2

Reading serial data in realtime in Python

A very good solution to this can be found here:

Here's a class that serves as a wrapper to a pyserial object. It allows you to read lines without 100% CPU. It does not contain any timeout logic. If a timeout occurs, returns an empty string and you might want to throw an exception to indicate the timeout.

It is also supposed to be fast according to the author:

The code below gives me 790 kB/sec while replacing the code with pyserial's readline method gives me just 170kB/sec.

class ReadLine:
    def __init__(self, s):
        self.buf = bytearray()
        self.s = s

    def readline(self):
        i = self.buf.find(b"\n")
        if i >= 0:
            r = self.buf[:i+1]
            self.buf = self.buf[i+1:]
            return r
        while True:
            i = max(1, min(2048, self.s.in_waiting))
            data =
            i = data.find(b"\n")
            if i >= 0:
                r = self.buf + data[:i+1]
                self.buf[0:] = data[i+1:]
                return r

ser = serial.Serial('COM7', 9600)
rl = ReadLine(ser)

while True:


Check Whether a User Exists

This is what I ended up doing in a Freeswitch bash startup script:

# Check if user exists
if ! id -u $FS_USER > /dev/null 2>&1; then
    echo "The user does not exist; execute below commands to crate and try again:"
    echo "  root@sh1:~# adduser --home /usr/local/freeswitch/ --shell /bin/false --no-create-home --ingroup daemon --disabled-password --disabled-login $FS_USER"
    echo "  ..."
    echo "  root@sh1:~# chown freeswitch:daemon /usr/local/freeswitch/ -R"
    exit 1

smooth scroll to top

I think the simplest solution is:

window.scrollTo({top: 0, behavior: 'smooth'});

If you wanted instant scrolling then just use:

window.scrollTo({top: 0});

Can be used as a function:

// Scroll To Top

function scrollToTop() {

window.scrollTo({top: 0, behavior: 'smooth'});


Or as an onclick handler:

<button onclick='window.scrollTo({top: 0, behavior: "smooth"});'>Scroll to Top</button>

What is a good pattern for using a Global Mutex in C#?

Sometimes learning by example helps the most. Run this console application in three different console windows. You'll see that the application you ran first acquires the mutex first, while the other two are waiting their turn. Then press enter in the first application, you'll see that application 2 now continues running by acquiring the mutex, however application 3 is waiting its turn. After you press enter in application 2 you'll see that application 3 continues. This illustrates the concept of a mutex protecting a section of code to be executed only by one thread (in this case a process) like writing to a file as an example.

using System;
using System.Threading;

namespace MutexExample
    class Program
        static Mutex m = new Mutex(false, "myMutex");//create a new NAMED mutex, DO NOT OWN IT
        static void Main(string[] args)
            Console.WriteLine("Waiting to acquire Mutex");
            m.WaitOne(); //ask to own the mutex, you'll be queued until it is released
            Console.WriteLine("Mutex acquired.\nPress enter to release Mutex");
            m.ReleaseMutex();//release the mutex so other processes can use it

enter image description here

Function in JavaScript that can be called only once

var quit = false;

function something() {
    if(quit) {
    quit = true;
    ... other code....

What’s the best way to get an HTTP response code from a URL?

Update using the wonderful requests library. Note we are using the HEAD request, which should happen more quickly then a full GET or POST request.

import requests
    r = requests.head("")
    # prints the int of the status code. Find more at :)
except requests.ConnectionError:
    print("failed to connect")

When should I use GC.SuppressFinalize()?

SuppressFinalize should only be called by a class that has a finalizer. It's informing the Garbage Collector (GC) that this object was cleaned up fully.

The recommended IDisposable pattern when you have a finalizer is:

public class MyClass : IDisposable
    private bool disposed = false;

    protected virtual void Dispose(bool disposing)
        if (!disposed)
            if (disposing)
                // called via myClass.Dispose(). 
                // OK to use any private object references
            // Release unmanaged resources.
            // Set large fields to null.                
            disposed = true;

    public void Dispose() // Implement IDisposable

    ~MyClass() // the finalizer

Normally, the CLR keeps tabs on objects with a finalizer when they are created (making them more expensive to create). SuppressFinalize tells the GC that the object was cleaned up properly and doesn't need to go onto the finalizer queue. It looks like a C++ destructor, but doesn't act anything like one.

The SuppressFinalize optimization is not trivial, as your objects can live a long time waiting on the finalizer queue. Don't be tempted to call SuppressFinalize on other objects mind you. That's a serious defect waiting to happen.

Design guidelines inform us that a finalizer isn't necessary if your object implements IDisposable, but if you have a finalizer you should implement IDisposable to allow deterministic cleanup of your class.

Most of the time you should be able to get away with IDisposable to clean up resources. You should only need a finalizer when your object holds onto unmanaged resources and you need to guarantee those resources are cleaned up.

Note: Sometimes coders will add a finalizer to debug builds of their own IDisposable classes in order to test that code has disposed their IDisposable object properly.

public void Dispose() // Implement IDisposable

~MyClass() // the finalizer

How to loop an object in React?

The problem is the way you're using forEach(), as it will always return undefined. You're probably looking for the map() method, which returns a new array:

var tifOptions = Object.keys(tifs).map(function(key) {
    return <option value={key}>{tifs[key]}</option>

If you still want to use forEach(), you'd have to do something like this:

var tifOptions = [];

Object.keys(tifs).forEach(function(key) {
    tifOptions.push(<option value={key}>{tifs[key]}</option>);


If you're writing ES6, you can accomplish the same thing a bit neater using an arrow function:

const tifOptions = Object.keys(tifs).map(key => 
    <option value={key}>{tifs[key]}</option>

Here's a fiddle showing all options mentioned above:

Display filename before matching line

grep 'search this' *.txt

worked for me to search through all .txt files (enter your own search value, of course).

Adding a background image to a <div> element

For the most part, the method is the same as setting the whole body

    background-image: url('path');


<div class="divi"></div>

Showing all session data at once?

For print session data you do not need to use print_r() function every time .

If you use it then it will be non-readable format.Data will be looks very dirty.

But if you use my function all you have to do is to use p()-Funtion and pass data into it. //create new file into application/cms_helper.php and load helper cms into //autoload or on controller

/*Copy Code for p function from here and paste into cms_helper.php in application/helpers folder */

   //@parram $data-array,$d-if true then die by default it is false
   //@author Your name

    function p($data,$d = false){

          echo "<pre>"; 
          echo "</pre>"; 

        if($d == TRUE){

Just remember to load cms_helper into your project or controller using $this->load->helper('cms'); use bellow code into your controller or model it will works just GREAT.

 p($this->session->all_userdata()); // it will apply pre to your sesison data and other array as  well

AngularJS routing without the hash '#'

Lets write answer that looks simple and short

In Router at end add html5Mode(true);

app.config(function($routeProvider,$locationProvider) {

    $routeProvider.when('/home', {


In html head add base tag

    <meta charset="utf-8">    
    <base href="/">

thanks To @plus- for detailing the above answer

include antiforgerytoken in ajax post ASP.NET MVC

I know this is an old question. But I will add my answer anyway, might help someone like me.

If you dont want to process the result from the controller's post action, like calling the LoggOff method of Accounts controller, you could do as the following version of @DarinDimitrov 's answer:

@using (Html.BeginForm("LoggOff", "Accounts", FormMethod.Post, new { id = "__AjaxAntiForgeryForm" }))

<!-- this could be a button -->
<a href="#" id="ajaxSubmit">Submit</a>

<script type="text/javascript">
    $('#ajaxSubmit').click(function () {


        return false;

Malformed String ValueError ast.literal_eval() with String representation of Tuple

From the documentation for ast.literal_eval():

Safely evaluate an expression node or a string containing a Python expression. The string or node provided may only consist of the following Python literal structures: strings, numbers, tuples, lists, dicts, booleans, and None.

Decimal isn't on the list of things allowed by ast.literal_eval().

invalid new-expression of abstract class type

Another possible cause for future Googlers

I had this issue because a method I was trying to implement required a std::unique_ptr<Queue>(myQueue) as a parameter, but the Queue class is abstract. I solved that by using a QueuePtr(myQueue) constructor like so:

using QueuePtr = std::unique_ptr<Queue>;

and used that in the parameter list instead. This fixes it because the initializer tries to create a copy of Queue when you make a std::unique_ptr of its type, which can't happen.

Google MAP API Uncaught TypeError: Cannot read property 'offsetWidth' of null

Actually easiest way to fix this is just move your object before Javascript code it worked to me. I guess in your answer object is loaded after javascript code.

<style type="text/css" >
      #map_canvas {

 <div id="map_canvas"> </div> // Here 

<script type="text/javascript">

var latlng = new google.maps.LatLng(-34.397, 150.644);
var myOptions = {
zoom: 8,
      center: latlng,
      mapTypeId: google.maps.MapTypeId.ROADMAP
var map = new google.maps.Map(document.getElementById("map_canvas"),


<div id="map_canvas"> </div>

What does AND 0xFF do?

it clears the all the bits that are not in the first byte

space between divs - display table-cell

Well, the above does work, here is my solution that requires a little less markup and is more flexible.

.cells {_x000D_
  display: inline-block;_x000D_
  float: left;_x000D_
  padding: 1px;_x000D_
.cells>.content {_x000D_
  background: #EEE;_x000D_
  display: table-cell;_x000D_
  float: left;_x000D_
  padding: 3px;_x000D_
  vertical-align: middle;_x000D_
<div id="div1" class="cells"><div class="content">My Cell 1</div></div>_x000D_
<div id="div2" class="cells"><div class="content">My Cell 2</div></div>

Waiting for HOME ('android.process.acore') to be launched

I faced the same problem. However, it worked after i went to Project->Clean... Don't know why it happened though. Hope this helps

MySQL INNER JOIN select only one row from second table

   SELECT u.* 
        FROM users AS u
        INNER JOIN (
            SELECT p.*,
             @num := if(@id = user_id, @num + 1, 1) as row_number,
             @id := user_id as tmp
            FROM payments AS p,
                 (SELECT @num := 0) x,
                 (SELECT @id := 0) y
            ORDER BY p.user_id ASC, date DESC)
        ON (p.user_id = and (p.row_number=1)
        WHERE u.package = 1

How can I tell gcc not to inline a function?

GCC has a switch called


So use that when invoking gcc. But the side effect is that all other small functions are also non-inlined.

Flask Error: "Method Not Allowed The method is not allowed for the requested URL"

I had a similar problem when I deployed my Flask app in the IIS. Apparently, IIS does not accept route that include an underline ("_"). When I removed the underline, problem was resolved.

Replacing Pandas or Numpy Nan with a None to use with MysqlDB

Another addition: be careful when replacing multiples and converting the type of the column back from object to float. If you want to be certain that your None's won't flip back to np.NaN's apply @andy-hayden's suggestion with using pd.where. Illustration of how replace can still go 'wrong':

In [1]: import pandas as pd

In [2]: import numpy as np

In [3]: df = pd.DataFrame({"a": [1, np.NAN, np.inf]})

In [4]: df
0  1.0
1  NaN
2  inf

In [5]: df.replace({np.NAN: None})
0     1
1  None
2   inf

In [6]: df.replace({np.NAN: None, np.inf: None})
0  1.0
1  NaN
2  NaN

In [7]: df.where((pd.notnull(df)), None).replace({np.inf: None})
0  1.0
1  NaN
2  NaN

Replace Div Content onclick

A Third Answer

Sorry, maybe I have it correct this time...

jsFiddle Demo

var savedBox1, savedBox2, state1=0, state2=0;

jQuery(document).ready(function() {
    jQuery(".rec1").click(function() {
        if (state1==0){
            savedBox1 = jQuery('#rec-box').html();
            state1 = 1;
            state1 = 0;

    jQuery(".rec2").click(function() {
        if (state1==0){
            savedBox2 = jQuery('#rec-box2').html();
            state2 = 1;
            state2 = 0;

Get all child views inside LinearLayout at once

use this

    final int childCount = mainL.getChildCount();
    for (int i = 0; i < childCount; i++) {
          View element = mainL.getChildAt(i);

        // EditText
        if (element instanceof EditText) {
            EditText editText = (EditText)element;
            System.out.println("ELEMENTS EditText getId=>"+editText.getId()+ " getTag=>"+element.getTag()+
            " getText=>"+editText.getText());

        // CheckBox
        if (element instanceof CheckBox) {
            CheckBox checkBox = (CheckBox)element;
            System.out.println("ELEMENTS CheckBox getId=>"+checkBox.getId()+ " getTag=>"+checkBox.getTag()+
            " getText=>"+checkBox.getText()+" isChecked=>"+checkBox.isChecked());

        // DatePicker
        if (element instanceof DatePicker) {
            DatePicker datePicker = (DatePicker)element;
            System.out.println("ELEMENTS DatePicker getId=>"+datePicker.getId()+ " getTag=>"+datePicker.getTag()+
            " getDayOfMonth=>"+datePicker.getDayOfMonth());

        // Spinner
        if (element instanceof Spinner) {
            Spinner spinner = (Spinner)element;
            System.out.println("ELEMENTS Spinner getId=>"+spinner.getId()+ " getTag=>"+spinner.getTag()+
            " getSelectedItemId=>"+spinner.getSelectedItemId()+
            " getSelectedItemPosition=>"+spinner.getSelectedItemPosition()+
            " getTag(key)=>"+spinner.getTag(spinner.getSelectedItemPosition()));


How do I call an Angular.js filter with multiple arguments?

If you need two or more dealings with the filter, is possible to chain them:

{{ value | decimalRound: 2 | currencySimbol: 'U$' }} 
// 11.1111 becomes U$ 11.11

How to add parameters to HttpURLConnection using POST using NameValuePair

I think I found exactly what you need. It may help others.

You can use the method UrlEncodedFormEntity.writeTo(OutputStream).

UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(nvp); 

OutputStream output = null;
try {
  output = http.getOutputStream();    
} finally {
 if (output != null) try { output.close(); } catch (IOException ioe) {}

What is the difference between "#!/usr/bin/env bash" and "#!/usr/bin/bash"?

I find it useful, because when I didn't know about env, before I started to write script I was doing this:

type nodejs > scriptname.js #or any other environment

and then I was modifying that line in the file into shebang.
I was doing this, because I didn't always remember where is nodejs on my computer -- /usr/bin/ or /bin/, so for me env is very useful. Maybe there are details with this, but this is my reason

Getting the .Text value from a TextBox

Did you try using t.Text?

Which Architecture patterns are used on Android?

There are various patterns used in Android framework like:

  • Broadcast receiver uses Observer pattern
  • Remoter service invocation uses Proxy pattern
  • View and view group uses Composite pattern
  • Media framework uses Facade pattern

How do I install the OpenSSL libraries on Ubuntu?

sudo apt-get install libcurl4-openssl-dev

swift How to remove optional String Character

I looked over this again and i'm simplifying my answer. I think most the answers here are missing the point. You usually want to print whether or not your variable has a value and you also want your program not to crash if it doesn't (so don't use !). Here just do this

    print("color: \(color ?? "")")

This will give you blank or the value.

How do I convert a number to a letter in Java?

Personally, I prefer

return "ABCDEFGHIJKLMNOPQRSTUVWXYZ".substring(i, i+1);

which shares the backing char[]. Alternately, I think the next-most-readable approach is

return Character.toString((char) (i + 'A'));

which doesn't depend on remembering ASCII tables. It doesn't do validation, but if you want to, I'd prefer to write

char c = (char) (i + 'A');
return Character.isUpperCase(c) ? Character.toString(c) : null;

just to make it obvious that you're checking that it's an alphabetic character.

How to install a package inside virtualenv?

Avoiding Headaches and Best Practices:

  • Virtual Environments are not part of your git project (they don't need to be versioned) !

  • They can reside on the project folder (locally), but, ignored on your .gitignore.

  • After activating the virtual environment of your project, never "sudo pip install package".
  • After finishing your work, always "deactivate" your environment.
  • Avoid renaming your project folder.

For a better representation, here's a simulation:

creating a folder for your projects/environments

$ mkdir venv

creating environment

$ cd venv/ 

$ virtualenv google_drive
New python executable in google_drive/bin/python
Installing setuptools, pip...done.

activating environment

$ source google_drive/bin/activate

installing packages

(google_drive) $ pip install PyDrive
Downloading/unpacking PyDrive
Downloading PyDrive-1.3.1-py2-none-any.whl
Successfully installed PyDrive PyYAML google-api-python-client oauth2client six uritemplate httplib2 pyasn1 rsa pyasn1-modules
Cleaning up...

package available inside the environment

(google_drive) $ python
Python 2.7.6 (default, Oct 26 2016, 20:30:19) 
[GCC 4.8.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pydrive.auth
>>> gdrive = pydrive.auth.GoogleAuth()

deactivate environment

(google_drive) $ deactivate 


package NOT AVAILABLE outside the environment

$ python
Python 2.7.6 (default, Oct 26 2016, 20:32:10) 
[GCC 4.8.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pydrive.auth
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named pydrive.auth


Why not sudo?

Virtualenv creates a whole new environment for you, defining $PATH and some other variables and settings. When you use sudo pip install package, you are running Virtualenv as root, escaping the whole environment which was created, and then, installing the package on global site-packages, and not inside the project folder where you have a Virtual Environment, although you have activated the environment.

If you rename the folder of your project...'ll have to adjust some variables from some files inside the bin directory of your project.

For example:

bin/pip, line 1 (She Bang)

bin/activate, line 42 (VIRTUAL_ENV)

OpenCV - DLL missing, but it's not?

You just need to add the folder of the needed dll file (or files) to your system "Environment Variables" in "Path". Your problem will 100% be resolved. I had this problem too.

DNS problem, nslookup works, ping doesn't

I had this problem occasionally when using a multi-label name ie test.internal

The solution for me was to stop/start the dnscache on my windows 7 machine. Open a console as administrator and type

net stop dnscache
net start dnscache

then sigh and look for a way to get a Mac as your principal desktop.

How can I copy network files using Robocopy?

You should be able to use Windows "UNC" paths with robocopy. For example:

robocopy \\myServer\myFolder\myFile.txt \\myOtherServer\myOtherFolder

Robocopy has the ability to recover from certain types of network hiccups automatically.

java.lang.IllegalArgumentException: contains a path separator

openFileInput() doesn't accept paths, only a file name if you want to access a path, use File file = new File(path) and corresponding FileInputStream

What is MATLAB good for? Why is it so used by universities? When is it better than Python?

MATLAB, as mentioned by others, is great at matrix manipulation, and was originally built as an extension of the well-known BLAS and LAPACK libraries used for linear algebra. It interfaces well with other languages like Java, and is well favored by engineering and scientific companies for its well developed and documented libraries. From what I know of Python and NumPy, while they share many of the fundamental capabilities of MATLAB, they don't have the full breadth and depth of capabilities with their libraries.

Personally, I use MATLAB because that's what I learned in my internship, that's what I used in grad school, and that's what I used in my first job. I don't have anything against Python (or any other language). It's just what I'm used too.

Also, there is another free version in addition to scilab mentioned by @Jim C from gnu called Octave.

m2e lifecycle-mapping not found

You can use this dummy plugin:

mvn archetype:generate -DgroupId=org.eclipse.m2e -DartifactId=lifecycle-mapping -Dversion=1.0.0 -DarchetypeArtifactId=maven-archetype-mojo

After generating the project install/deploy it.

Docker command can't connect to Docker daemon

I had the same problem. Been struggling for two days to solve it.

It only worked when I did:

  1. According to Docker's Tutorial, you need to add the Docker key if not already added using:

    $ sudo wget -qO- | sudo apt-key add -

  2. Then make sure you grant docker privileges to yourself using:

    $ sudo usermod -aG docker $USER

Hope this helps you too.

Ng-model does not update controller value

For me the problem was solved by stocking my datas into an object (here "datas").

NgApp.controller('MyController', function($scope) {_x000D_
   $scope.my_title = ""; // This don't work in ng-click function called_x000D_
   $scope.datas = {_x000D_
      'my_title' : "",_x000D_
   $scope.doAction = function() {_x000D_
         console.log($scope.my_title); // bad value_x000D_
         console.log($scope.datas.my_title); // Good Value binded by'ng-model'_x000D_

I Hop it will help

How to connect to a secure website using SSL in Java with a pkcs12 file?

URL url = new URL("https://test.domain:443");   
String  keyStore = "server.p12"
String   keyStorePassword = "changeit";    
String  keyPassword = "changeit";    
String   KeyStoreType= "PKCS12";    
String   KeyManagerAlgorithm = "SunX509";    
String   SSLVersion = "SSLv3";    
public HttpURLConnection getHttpsURLConnection(URL url, String  keystore,
    String   keyStorePass,String  keyPassword, String  KeyStoreType
    ,String KeyManagerAlgorithm, String  SSLVersion)
    throws NoSuchAlgorithmException, KeyStoreException,
        CertificateException, FileNotFoundException, IOException,
        UnrecoverableKeyException, KeyManagementException {

    SSLContext sslcontext = SSLContext.getInstance(SSLVersion);
    KeyManagerFactory kmf =  KeyManagerFactory.getInstance(KeyManagerAlgorithm);
    KeyStore ks = KeyStore.getInstance(KeyStoreType);
    ks.load(new FileInputStream(keystore), keyStorePass.toCharArray());
    kmf.init(ks, keyPassword.toCharArray());

     TrustManagerFactory tmf = TrustManagerFactory
    TrustManager[] tm = tmf.getTrustManagers();

    sslcontext.init(kmf.getKeyManagers(), tm, null);
    SSLSocketFactory sslSocketFactory = sslcontext.getSocketFactory();
    HttpsURLConnection httpsURLConnection = ( HttpsURLConnection)uRL.openConnection();

    return httpsURLConnection;

How can I compare strings in C using a `switch` statement?

If you have many cases and do not want to write a ton of strcmp() calls, you could do something like:

switch(my_hash_function(the_string)) {
    case HASH_B1: ...
    /* ...etc... */

You just have to make sure your hash function has no collisions inside the set of possible values for the string.

Can two Java methods have same name with different return types?

No. C++ and Java both disallow overloading on a functions's return type. The reason is that overloading on return-type can be confusing (it can be hard for developers to predict which overload will be called). In fact, there are those who argue that any overloading can be confusing in this respect and recommend against it, but even those who favor overloading seem to agree that this particular form is too confusing.

<div style display="none" > inside a table not working

Semantically what you are trying is invalid html, table element cannot have a div element as a direct child. What you can do is, get your div element inside a td element and than try to hide it

Efficient way to add spaces between characters in a string

s = "BINGO"
print(" ".join(s))

Should do it.

Start a fragment via Intent within a Fragment

You cannot open new fragments. Fragments need to be always hosted by an activity. If the fragment is in the same activity (eg tabs) then the back key navigation is going to be tricky I am assuming that you want to open a new screen with that fragment.

So you would simply create a new activity and put the new fragment in there. That activity would then react to the intent either explicitly via the activity class or implicitly via intent filters.

CASE .. WHEN expression in Oracle SQL

    WHEN STATUS IN('a1','a2','a3') 
     THEN 'Active'
    WHEN STATUS = 'i' 
     THEN 'Inactive'
    WHEN STATUS = 't'
     THEN 'Terminated'  ELSE null

Where are the Properties.Settings.Default stored?

thanks for pointing me in the right direction. I found user.config located at this monstrosity: c:\users\USER\AppData\Local\COMPANY\APPLICATION.exe_Url_LOOKSLIKESOMEKINDOFHASH\VERSION\user.config.

I had to uprev the version on my application and all the settings seemed to have vanished. application created a new folder with the new version and used the default settings. took forever to find where the file was stored, but then it was a simple copy and paste to get the settings to the new version.

Passing arguments to JavaScript function from code-behind

<html xmlns="">
<head runat="server">
    <title>Call java script function on Code behind</title>
    <script  type="text/javascript">
    function abc()
        var a=20;
        var b=30;
        alert("you enter"+a+":"+b);

cs code

protected void Page_Load(object sender, EventArgs e)
    TextBox2.Attributes.Add("onkeypress", "return abc();");

try this

Install a Windows service using a Windows command prompt?

Open Visual studio and select new project by selecting Windows Service template in Windows Desktop tab. Than copy following code into your service_name.cs file.

using System.Diagnostics;
using System.ServiceProcess;
namespace TimerService
    public partial class Timer_Service : ServiceBase
        public Timer_Service()
        static void Main()
            if (System.Diagnostics.Debugger.IsAttached)
                Timer_Service service = new Timer_Service();
                ServiceBase[] ServicesToRun;
                ServicesToRun = new ServiceBase[]
                    new Timer_Service()
        protected override void OnStart(string[] args)
            EventLog.WriteEvent("Timer_Service", new EventInstance(0, 0, EventLogEntryType.Information), new string[] { "Service start successfully." });
        protected override void OnStop()
            EventLog.WriteEvent("Timer_Service", new EventInstance(0, 0, EventLogEntryType.Information), new string[] { "Service stop successfully." });

Right-Click on service_name.cs file and open designer of service. than right-click and select Add Installer. than right-click on serviceProcessInstaller1 and change its property value of Account from User to Local System.

Remove static void main method from Program.cs file. Than save and Build your project.

NOTE: goto bin\Ddebug folder of your project folder. Than open Properties of your service_name.exe file. Than goto Compatibility tab. Than click on Change Settings For All Users.

Select option Run this program as an administrator.

Now, You have to open CommandPromt as Administrator. After open, set directory to where your InstallUtil.exe file is placed. for ex: C:\Windows\Microsoft.NET\Framework64\v4.0.30319. now write the following command:

C:\Windows\Microsoft.NET\Framework64\v4.0.30319>InstallUtil.exe -i C:\TimerService\TimerService\bin\Debug\TimerService.exe

Note: -i is for install he service and -u for Unsinstall.

after -i set the write the path where you want to install your service.

now write the command in CommandPromt as follows:

C:\TimerService\TimerService\bin\Debug>net start service_name

Note: use stop for stop the Service.

Now, open ViewEventLog.exe. Select Windows Logs>Application. There you can check your Service's log by start and stop the service.

ToggleClass animate jQuery?

I attempted to use the toggleClass method to hide an item on my site (using visibility:hidden as opposed to display:none) with a slight animation, but for some reason the animation would not work (possibly due to an older version of jQuery UI).

The class was removed and added correctly, but the duration I added did not seem to make any difference - the item was simply added or removed with no effect.

So to resolve this I used a second class in my toggle method and applied a CSS transition instead:

The CSS:

    opacity: 0;
    -moz-transition: opacity 1s, visibility 1.3s;
    -webkit-transition: opacity 1s, visibility 1.3s;
    -o-transition: opacity 1s, visibility 1.3s;
    transition: opacity 1s, visibility 1.3s;
    opacity: 1;
    -moz-transition: opacity 1s, visibility 1.3s;
    -webkit-transition: opacity 1s, visibility 1.3s;
    -o-transition: opacity 1s, visibility 1.3s;
    transition: opacity 1s, visibility 1.3s;

The JS:

    function showOrHide() {
        $('#element').toggleClass("hidden shown");

Thanks @tomas.satinsky for the awesome (and super simple) answer on this post.

How do I auto-hide placeholder text upon focus using css or jquery?

Sometimes you need SPECIFICITY to make sure your styles are applied with strongest factor id Thanks for @Rob Fletcher for his great answer, in our company we have used

So please consider adding styles prefixed with the id of the app container

    #app input:focus::-webkit-input-placeholder, #app  textarea:focus::-webkit-input-placeholder {_x000D_
        color: #FFFFFF;_x000D_
    #app input:focus:-moz-placeholder, #app textarea:focus:-moz-placeholder {_x000D_
        color: #FFFFFF;_x000D_

No route matches "/users/sign_out" devise rails 3

Other option is to configure the logout to be a GET instead a DELETE, you can do that adding the following line on /config/initializers/devise.rb

config.sign_out_via = :get

But as Steve Klabnik wrote on his blog ( try to use DELETE because of the semantic of this method.

How to declare a global variable in C++

Not sure if this is correct in any sense but this seems to work for me.

inline int someVar;

I don't have linking/multiple definition issues and it "just works"... ;- )

It's quite handy for "quick" tests... Try to avoid global vars tho, because every says so... ;- )

How to get the file name from a full path using JavaScript?

Not more concise than nickf's answer, but this one directly "extracts" the answer instead of replacing unwanted parts with an empty string:

var filename = /([^\\]+)$/.exec(fullPath)[1];

Write a formula in an Excel Cell using VBA

You can try using FormulaLocal property instead of Formula. Then the semicolon should work.

How can I call a WordPress shortcode within a template?

Try this:

Template Name: [contact us]

echo do_shortcode('[CONTACT-US-FORM]'); 

Convert all data frame character columns to factors

DF <- data.frame(x=letters[1:5], y=1:5, stringsAsFactors=FALSE)

#'data.frame':  5 obs. of  2 variables:
# $ x: chr  "a" "b" "c" "d" ...
# $ y: int  1 2 3 4 5

The (annoying) default of is to turn all character columns into factor columns. You can use that here:

DF <-
#'data.frame':  5 obs. of  2 variables:
# $ x: Factor w/ 5 levels "a","b","c","d",..: 1 2 3 4 5
# $ y: int  1 2 3 4 5

How to redirect in a servlet filter?

If you also want to keep hash and get parameter, you can do something like this (fill redirectMap at filter init):

String uri = request.getRequestURI();

String[] uriParts = uri.split("[#?]");
String path = uriParts[0];
String rest = uri.substring(uriParts[0].length());

if(redirectMap.containsKey(path)) {
    response.sendRedirect(redirectMap.get(path) + rest);
} else {
    chain.doFilter(request, response);

Can multiple different HTML elements have the same ID if they're different elements?

Yes they can.

I don't know if all these anwers are outdated, but just open youtube and inspect the html. Try to inspect the suggested videos, you'll see that they all have the same Id and repeating structure as follows:

<span id="video-title" class="style-scope ytd-compact-radio-renderer" title="Mix - LARA TACTICAL">

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

Two possibilities here. Java Version incompatible or import

How to create a secure random AES key in Java?

I would use your suggested code, but with a slight simplification:

KeyGenerator keyGen = KeyGenerator.getInstance("AES");
keyGen.init(256); // for example
SecretKey secretKey = keyGen.generateKey();

Let the provider select how it plans to obtain randomness - don't define something that may not be as good as what the provider has already selected.

This code example assumes (as Maarten points out below) that you've configured your file to include your preferred provider at the top of the list. If you want to manually specify the provider, just call KeyGenerator.getInstance("AES", "providerName");.

For a truly secure key, you need to be using a hardware security module (HSM) to generate and protect the key. HSM manufacturers will typically supply a JCE provider that will do all the key generation for you, using the code above.

Select current date by default in ASP.Net Calendar control

Two ways of doing it.

Late binding

<asp:Calendar ID="planning" runat="server" SelectedDate="<%# DateTime.Now %>"></asp:Calendar>

Code behind way (Page_Load solution)

protected void Page_Load(object sender, EventArgs e)

private void BindCalendar()
    planning.SelectedDate = DateTime.Today;

Altough, I strongly recommend to do it from a BindMyStuff way. Single entry point easier to debug. But since you seems to know your game, you're all set.

What is a typedef enum in Objective-C?

Update for 64-bit Change: According to apple docs about 64-bit changes,

Enumerations Are Also Typed : In the LLVM compiler, enumerated types can define the size of the enumeration. This means that some enumerated types may also have a size that is larger than you expect. The solution, as in all the other cases, is to make no assumptions about a data type’s size. Instead, assign any enumerated values to a variable with the proper data type

So you have to create enum with type as below syntax if you support for 64-bit.

typedef NS_ENUM(NSUInteger, ShapeType) {


typedef enum ShapeType : NSUInteger {
} ShapeType;

Otherwise, it will lead to warning as Implicit conversion loses integer precision: NSUInteger (aka 'unsigned long') to ShapeType

Update for swift-programming:

In swift, there's an syntax change.

enum ControlButtonID: NSUInteger {
        case kCircle , kRectangle, kOblateSpheroid

Installing jdk8 on ubuntu- "unable to locate package" update doesn't fix

If you get a

sudo: add-apt-repository: command not found

then you need to run the following command

sudo apt-get install software-properties-common python-software-properties

Pressed <button> selector

Maybe :active over :focus with :hover will help! Try

button {

button:hover {

button:focus {

button:active {


<button onkeydown="alerted_of_key_pressed()" id="button" title="Test button" href="#button">Demo</button>


function alerted_of_key_pressed() { alert("You pressed a key when hovering over this button.") }
 Sorry about that last one. :) I was just showing you a cool function! 
Wait... did I just emphasize a code block? This is cool!!!

convert string to number node.js

Using parseInt() is a bad idea mainly because it never fails. Also because some results can be unexpected, like in the case of INFINITY.
Below is the function for handling unexpected behaviour.

function cleanInt(x) {
    x = Number(x);
    return x >= 0 ? Math.floor(x) : Math.ceil(x);

See results of below test cases.

console.log("CleanInt: ", cleanInt('xyz'), " ParseInt: ", parseInt('xyz'));
console.log("CleanInt: ", cleanInt('123abc'), " ParseInt: ", parseInt('123abc'));
console.log("CleanInt: ", cleanInt('234'), " ParseInt: ", parseInt('234'));
console.log("CleanInt: ", cleanInt('-679'), " ParseInt: ", parseInt('-679'));
console.log("CleanInt: ", cleanInt('897.0998'), " ParseInt: ", parseInt('897.0998'));
console.log("CleanInt: ", cleanInt('Infinity'), " ParseInt: ", parseInt('Infinity'));


CleanInt:  NaN  ParseInt:  NaN
CleanInt:  NaN  ParseInt:  123
CleanInt:  234  ParseInt:  234
CleanInt:  -679  ParseInt:  -679
CleanInt:  897  ParseInt:  897
CleanInt:  Infinity  ParseInt:  NaN

error: ‘NULL’ was not declared in this scope

NULL isn't a keyword; it's a macro substitution for 0, and comes in stddef.h or cstddef, I believe. You haven't #included an appropriate header file, so g++ sees NULL as a regular variable name, and you haven't declared it.

Postgresql - select something where date = "01/01/11"

I think you want to cast your dt to a date and fix the format of your date literal:

FROM table
WHERE dt::date = '2011-01-01' -- This should be ISO-8601 format, YYYY-MM-DD

Or the standard version:

FROM table
WHERE CAST(dt AS DATE) = '2011-01-01' -- This should be ISO-8601 format, YYYY-MM-DD

The extract function doesn't understand "date" and it returns a number.

How to use bitmask?

Bitmasks are used when you want to encode multiple layers of information in a single number.

So (assuming unix file permissions) if you want to store 3 levels of access restriction (read, write, execute) you could check for each level by checking the corresponding bit.


110 in base 2 translates to 6 in base 10.

So you can easily check if someone is allowed to e.g. read the file by and'ing the permission field with the wanted permission.



user_permissions = 6

if (user_permissions & PERM_READ == TRUE) then
  // this will be reached, as 6 & 4 is true

You need a working understanding of binary representation of numbers and logical operators to understand bit fields.

MySQL ORDER BY rand(), name ASC

Use a subquery:

    SELECT * FROM users ORDER BY rand() LIMIT 20
) T1
ORDER BY name 

The inner query selects 20 users at random and the outer query orders the selected users by name.

Batch Extract path and filename from a variable

All of this works for me:

@Echo Off
Echo Directory = %~dp0
Echo Object Name With Quotations=%0
Echo Object Name Without Quotes=%~0
Echo Bat File Drive = %~d0
Echo Full File Name = %~n0%~x0
Echo File Name Without Extension = %~n0
Echo File Extension = %~x0


Directory = D:\Users\Thejordster135\Desktop\Code\BAT\

Object Name With Quotations="D:\Users\Thejordster135\Desktop\Code\BAT\Path_V2.bat"

Object Name Without Quotes=D:\Users\Thejordster135\Desktop\Code\BAT\Path_V2.bat

Bat File Drive = D:

Full File Name = Path.bat

File Name Without Extension = Path

File Extension = .bat

Could not find tools.jar. Please check that C:\Program Files\Java\jre1.8.0_151 contains a valid JDK installation

The problem is your gradle build is not finding the JAVA_HOME path or JDK folder. So, you could declare the path in like\Program Files\Java\[or yours jdk folder name].

Use this guide for using

Or (and I prefer this solution) include JAVA_HOME path in systmem variables and restart CMD.

enter image description here

Apache: client denied by server configuration

Apache 2.4.3 (or maybe slightly earlier) added a new security feature that often results in this error. You would also see a log message of the form "client denied by server configuration". The feature is requiring an authorized user identity to access a directory. It is turned on by DEFAULT in the httpd.conf that ships with Apache. You can see the enabling of the feature with the directive

Require all denied

This basically says to deny access to all users. To fix this problem, either remove the denied directive (or much better) add the following directive to the directories you want to grant access to:

Require all granted

as in

<Directory "your directory here">
   Order allow,deny
   Allow from all
   # New directive needed in Apache 2.4.3: 
   Require all granted

Ignore invalid self-signed ssl certificate in node.js with https.request?

For meteorJS you can set with npmRequestOptions., {
    npmRequestOptions: {
        rejectUnauthorized: false // TODO remove when deploy
    timeout: 30000, // 30s
    data: xml
}, function(error, result) {
    console.log('error: ' + error);
    console.log('resultXml: ' + result);

Passing a string with spaces as a function argument in bash

Your definition of myFunction is wrong. It should be:

    # same as before


function myFunction
    # same as before

Anyway, it looks fine and works fine for me on Bash 3.2.48.

Jquery to change form action

$('#myform').prop('action', 'page1.php');

How do I make a JAR from a .java file?

Perhaps the most beginner-friendly way to compile a JAR from your Java code is to use an IDE (integrated development environment; essentially just user-friendly software for development) like Netbeans or Eclipse.

  • Install and set-up an IDE. Here is the latest version of Eclipse.
  • Create a project in your IDE and put your Java files inside of the project folder.
  • Select the project in the IDE and export the project as a JAR. Double check that the appropriate java files are selected when exporting.

You can always do this all very easily with the command line. Make sure that you are in the same directory as the files targeted before executing a command such as this:

jar -cf YourJar.jar YourApp.class

...changing "YourApp" and "YourJar" to the proper names of your files, respectively.

Full width layout with twitter bootstrap

In Bootstrap 3, columns are specified using percentages. (In Bootstrap 2, this was only the case if a column/span was within a .row-fluid element, but that's no longer necessary and that class no longer exists.) If you use a .container, then @Michael is absolutely right that you'll be stuck with a fixed-width layout. However, you should be in good shape if you just avoid using a .container element.

  <div class="row">
    <div class="col-lg-4">...</div>
    <div class="col-lg-8">...</div>

The margin for the body is already 0, so you should be able to get up right to the edge. (Columns still have a 15px padding on both sides, so you may have to account for that in your design, but this shouldn't stop you, and you can always customize this when you download Bootstrap.)

Good ways to sort a queryset? - Django

Here's a way that allows for ties for the cut-off score.

author_count = Author.objects.count()
cut_off_score = Author.objects.order_by('-score').values_list('score')[min(30, author_count)]
top_authors = Author.objects.filter(score__gte=cut_off_score).order_by('last_name')

You may get more than 30 authors in top_authors this way and the min(30,author_count) is there incase you have fewer than 30 authors.

ImportError: Couldn't import Django

I think the best way to use django is with virtualenv it's safe and you can install many apps in virtualenv which does not affect any outer space of the system vitualenv uses the default version of python which is same as in your system to install virtualenv

sudo pip install virtualenv

or for python3

sudo pip3 install virtualenv

and then in your dir

mkdir ~/newproject

cd ~/newproject

Now, create a virtual environment within the project directory by typing

virtualenv newenv

To install packages into the isolated environment, you must activate it by typing:

source newenv/bin/activate

now install here with

pip install django

You can verify the installation by typing:

django-admin --version

To leave your virtual environment, you need to issue the deactivate command from anywhere on the system:


How to use Bootstrap modal using the anchor tag for Register?

Just replace it:

<li><a href="" data-toggle="modal" data-target="#modalRegister">Register</a></li>

Instead of:

<li><a href="#" data-toggle="modal" data-target="modalRegister">Register</a></li>

Find Active Tab using jQuery and Twitter Bootstrap

Here is the answer for those of you who need a Boostrap 3 solution.

In bootstrap 3 use '' instead of 'shown' in the next line

// tab
$('#rowTab a:first').tab('show');

$('a[data-toggle="tab"]').on('', function (e) {
//show selected tab / active
 console.log ( $('id') );

How to create a DOM node as an object?

And here is the one liner:

$("<li><div class='bar'>bla</div></li>").find("li").attr("id","1234").end().appendTo("body")

But I'm wondering why you would like to add the "id" attribute at a later stage rather than injecting it directly in the template.

Call method when home button pressed

I also struggled with HOME button for awhile. I wanted to stop/skip a background service (which polls location) when user clicks HOME button.

here is what I implemented as "hack-like" solution;

keep the state of the app on SharedPreferences using boolean value

on each activity

onResume() -> set appactive=true

onPause() -> set appactive=false

and the background service checks the appstate in each loop, skips the action

IF appactive=false

it works well for me, at least not draining the battery anymore, hope this helps....

What is "git remote add ..." and "git push origin master"?

This is an answer to this question (Export Heroku App to a new GitHub repo) which has been marked as duplicate of this one and redirected here.

I wanted to mirror my repo from Heroku to Github personal so that it shows all commits etc also which I made in Heroku. in Github documentation was useful.

UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in position 7: ordinal not in range(128)

You need to encode Unicode explicitly before writing to a file, otherwise Python does it for you with the default ASCII codec.

Pick an encoding and stick with it:

f.write(printinfo.encode('utf8') + '\n')

or use to create a file object that'll encode for you as you write to the file:

import io

f =, 'w', encoding='utf8')

You may want to read:

before continuing.

Convert string to int if string is a number

Cast to long or cast to int, be aware of the following.

These functions are one of the view functions in Excel VBA that are depending on the system regional settings. So if you use a comma in your double like in some countries in Europe, you will experience an error in the US.

E.g., in european excel-version 0,5 will perform well with CDbl(), but in US-version it will result in 5. So I recommend to use the following alternative:

Public Function CastLong(var As Variant)

    ' replace , by .
    var = Replace(var, ",", ".")        

    Dim l As Long
    On Error Resume Next
    l = Round(Val(var))

    ' if error occurs, l will be 0
    CastLong = l

End Function

' similar function for cast-int, you can add minimum and maximum value if you like
' to prevent that value is too high or too low.
Public Function CastInt(var As Variant)

    ' replace , by .
    var = Replace(var, ",", ".")

    Dim i As Integer
    On Error Resume Next
    i = Round(Val(var))

    ' if error occurs, i will be 0
    CastInt = i

End Function

Of course you can also think of cases where people use commas and dots, e.g., three-thousand as 3,000.00. If you require functionality for these kind of cases, then you have to check for another solution.

Generate table relationship diagram from existing schema (SQL Server)

SchemaCrawler for SQL Server can generate database diagrams, with the help of GraphViz. Foreign key relationships are displayed (and can even be inferred, using naming conventions), and tables and columns can be excluded using regular expressions.

How to display the first few characters of a string in Python?

You can 'slice' a string very easily, just like you'd pull items from a list:

a_string = 'This is a string'

To get the first 4 letters:

first_four_letters = a_string[:4]
>>> 'This'

Or the last 5:

last_five_letters = a_string[-5:]
>>> 'string'

So applying that logic to your problem:

the_string = '416d76b8811b0ddae2fdad8f4721ddbe|d4f656ee006e248f2f3a8a93a8aec5868788b927|12a5f648928f8e0b5376d2cc07de8e4cbf9f7ccbadb97d898373f85f0a75c47f '
first_32_chars = the_string[:32]
>>> 416d76b8811b0ddae2fdad8f4721ddbe

A default document is not configured for the requested URL, and directory browsing is not enabled on the server

This can also occur if you do something stupid (like I did) and place the api url in the "Project Url" (e.g. http://localhost:59088/api/Product) on the Project Properties->Web tab instead of specifying it in the "Specific Page" text box. This causes Visual Studio to go ahead and create an APP called ProjectName/api/Product, and this will expect a default page. The only way to undo this is to go to C:\Program Files (x86)\IIS Express and use appcmd.exe to delete it like so

>.\appcmd.exe delete APP "ProjectName/api/Product"

release Selenium chromedriver.exe from memory

Python code:

    # do my automated tasks

OWIN Startup Class Missing

In my case, I had renamed the project and changed it's folder structure. I found that updating the RootNameSpace and AssemblyName in the .csproj file where the error was being thrown resolved the error. If you have modified paths of your project I'd recommend checking this as well.


Centering in CSS Grid

Try using flex:

Plunker demo :

/* Styles go here */

body {
  margin: 0;
  padding: 0;

.container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-rows: 100vh;
  grid-gap: 0px 0px;

.left_bg {
  background-color: #3498db;
  grid-column: 1 / 1;
  grid-row: 1 / 1;
  z-index: 0;
  display: flex;
  justify-content: center;
  align-items: center;


.right_bg {
  background-color: #ecf0f1;
  grid-column: 2 / 2;
  grid_row: 1 / 1;
  z-index: 0;
  display: flex;
  justify-content: center;
  align-items: center;

.text {
  font-family: Raleway;
  font-size: large;
  text-align: center;


    <div class="container">
  <!--everything on the page-->

  <div class="left_bg">
    <!--left background color of the page-->
    <div class="text">
      <!--left side text content-->
      <p>Review my stuff</p>

  <div class="right_bg">
    <!--right background color of the page-->
    <div class="text">
      <!--right side text content-->
      <p>Hire me!</p>

Apache Tomcat Not Showing in Eclipse Server Runtime Environments

  1. Window > Preferences > Server > Runtime Environments (as you said)
  2. Add
  3. Apache > Apache Tomcat 5.5

That has worked for the past 3 versions of Eclipse at least. If there is not such an option on your eclipse, get a fresh installation (for Java EE developers).

Can I run Keras model on gpu?

Yes you can run keras models on GPU. Few things you will have to check first.

  1. your system has GPU (Nvidia. As AMD doesn't work yet)
  2. You have installed the GPU version of tensorflow
  3. You have installed CUDA installation instructions
  4. Verify that tensorflow is running with GPU check if GPU is working

sess = tf.Session(config=tf.ConfigProto(log_device_placement=True))

for TF > v2.0

sess = tf.compat.v1.Session(config=tf.compat.v1.ConfigProto(log_device_placement=True))

(Thanks @nbro and @Ferro for pointing this out in the comments)


from tensorflow.python.client import device_lib

output will be something like this:

  name: "/cpu:0"device_type: "CPU",
  name: "/gpu:0"device_type: "GPU"

Once all this is done your model will run on GPU:

To Check if keras(>=2.1.1) is using GPU:

from keras import backend as K

All the best.

ASP.NET 2.0 - How to use app_offline.htm

Make sure your app_offline.htm file is at least 512 bytes long. A zero-byte app_offline.htm will have no effect.

UPDATE: Newer versions of ASP.NET/IIS may behave better than when I first wrote this.

UPDATE 2: If you are using ASP.NET MVC, add the following to web.config:

<?xml version="1.0"?>
        <modules runAllManagedModulesForAllRequests="true" />

Configure active profile in SpringBoot via Maven

Or rather easily:

mvn spring-boot:run{profile_name}

Go to particular revision

You can get a graphical view of the project history with tools like gitk. Just run:

gitk --all

If you want to checkout a specific branch:

git checkout <branch name>

For a specific commit, use the SHA1 hash instead of the branch name. (See Treeishes in the Git Community Book, which is a good read, to see other options for navigating your tree.)

git log has a whole set of options to display detailed or summary history too.

I don't know of an easy way to move forward in a commit history. Projects with a linear history are probably not all that common. The idea of a "revision" like you'd have with SVN or CVS doesn't map all that well in Git.

'Syntax Error: invalid syntax' for no apparent reason

For problems where it seems to be an error on a line you think is correct, you can often remove/comment the line where the error appears to be and, if the error moves to the next line, there are two possibilities.

Either both lines have a problem or the previous line has a problem which is being carried forward. The most likely case is the second option (even more so if you remove another line and it moves again).

For example, the following Python program

xyzzy = (1 +
plugh = 7

generates the error:

  File "", line 2
    plugh = 7
SyntaxError: invalid syntax

despite the problem clearly being on line 1.

In your particular case, that is the problem. The parentheses in the line before your error line is unmatched, as per the following snippet:

# open parentheses: 1  2             3
#                   v  v             v
#                               ^             ^
# close parentheses:            1             2

Depending on what you're trying to achieve, the solution may be as simple as just adding another closing parenthesis at the end, to close off the sqrt function.

I can't say for certain since I don't recognise the expression off the top of my head. Hardly surprising if (assuming PSAT is the enzyme, and the use of the typeMolecule identifier) it's to do with molecular biology - I seem to recall failing Biology consistently in my youth :-)

Escaping regex string

Please give a try:

\Q and \E as anchors

Put an Or condition to match either a full word or regex.

Ref Link : How to match a whole word that includes special characters in regex

Log all requests from the python-requests module

I'm using a logger_config.yaml file to configure my logging, and to get those logs to show up, all I had to do was to add a disable_existing_loggers: False to the end of it.

My logging setup is rather extensive and confusing, so I don't even know a good way to explain it here, but if someone's also using a YAML file to configure their logging, this might help.

What are the differences between Visual Studio Code and Visual Studio?

For me, Visual Studio on Mac doesn't support Node.js (editing and debugging) whereas Visual Studio Code does this very well.

Get custom product attributes in Woocommerce

Try this to get an array of attribute name => attribute value(s):

global $product;

$formatted_attributes = array();

$attributes = $product->get_attributes();

foreach($attributes as $attr=>$attr_deets){

    $attribute_label = wc_attribute_label($attr);

    if ( isset( $attributes[ $attr ] ) || isset( $attributes[ 'pa_' . $attr ] ) ) {

        $attribute = isset( $attributes[ $attr ] ) ? $attributes[ $attr ] : $attributes[ 'pa_' . $attr ];

        if ( $attribute['is_taxonomy'] ) {

            $formatted_attributes[$attribute_label] = implode( ', ', wc_get_product_terms( $product->id, $attribute['name'], array( 'fields' => 'names' ) ) );

        } else {

            $formatted_attributes[$attribute_label] = $attribute['value'];



return $formatted_attributes;

It's little inefficient but does the trick.

TypeError: 'list' object cannot be interpreted as an integer

In playSound(), instead of

for i in range(myList):


for i in myList:

This will iterate over the contents of myList, which I believe is what you want. range(myList) doesn't make any sense.

jQuery .val change doesn't change input value

$('#link').prop('value', 'new value');

Explanation: Attr will work on jQuery 1.6 but as of jQuery 1.6.1 things have changed. In the majority of cases, prop() does what attr() used to do. Replacing calls to attr() with prop() in your code will generally work. Attr will give you the value of element as it was defined in the html on page load and prop gives the updated values of elements which are modified via jQuery.

Does Hive have a String split function?

There does exist a split function based on regular expressions. It's not listed in the tutorial, but it is listed on the language manual on the wiki:

split(string str, string pat)
   Split str around pat (pat is a regular expression) 

In your case, the delimiter "|" has a special meaning as a regular expression, so it should be referred to as "\\|".

How to hide/show more text within a certain length (like youtube)

Put text inside Your Text Here and copy the script inside your js file. You are ready to go. Working code for see more.. and see less.. options. Works for dynamic as well as static texts

<div class="item">
  Your Text Here

<script type="text/javascript">
 $(function(){ /* to make sure the script runs after page load */

    $('.item').each(function(event){ /* select all divs with the item class */

      var max_length = 150; /* set the max content length before a read more link will be added */

      if($(this).html().length > max_length){ /* check for content length */

        var short_content   = $(this).html().substr(0,max_length); /* split the content in two parts */
        var long_content  = $(this).html().substr(max_length);

        $(this).html(short_content+'<a href="#" class="read_more">Show More</a>'+
               '<span class="more_text" style="display:none;">'+long_content+'</span>'+'<a href="#" class="read_less" style="display:none;">Show Less</a>'); /* Alter the html to allow the read more functionality */

        $(this).find('a.read_more').click(function(event){ /* find the a.read_more element within the new html and bind the following code to it */

          event.preventDefault(); /* prevent the a from changing the url */
          $(this).hide(); /* hide the read more button */
          $('.read_less').show(); /* show read less button */

          $(this).parents('.item').find('.more_text').show(); /* show the .more_text span */



          $(this).hide(); /* hide the read more button */






How to properly create composite primary keys - MYSQL

I would use a composite (multi-column) key.

    t1ID INT,
    t2ID INT,
    PRIMARY KEY (t1ID, t2ID)

This way you can have t1ID and t2ID as foreign keys pointing to their respective tables as well.

How to change port for jenkins window service when 8080 is being used

If you are running on Redhat, do following

  1. Stop Jenkins
    $sudo service jenkins stop

  2. change port number in /etc/sysconfig/jenkins like i did for port 8081

  3. start Jenkins again
    $sudo service jenkins start

make sure your FW has correct burn rules.

pros and cons between os.path.exists vs os.path.isdir

Just like it sounds like: if the path exists, but is a file and not a directory, isdir will return False. Meanwhile, exists will return True in both cases.

What are DDL and DML?

DDL is Data Definition Language: Just think you are defining the DB. So we use CREATE,ALTER TRUNCATE commands.
DML is after defining we are Manipulating the data. So we use SELECT,INSERT, UPDATE, DELETE command.

Remember DDL commands are auto-committed. You don't need to use COMMIT statements.
DML (Data Manipulation Language) commands need to be commited/rolled back.

How to check if an Object is a Collection Type in Java?

Test if the object implements either java.util.Collection or java.util.Map. (Map has to be tested separately because it isn't a sub-interface of Collection.)

Start script missing error when running npm start

I got this error because I wasn't in the right directory in terminal.

App with the scripts was in folder B. Folder B was in folder A. I open folder A in vscode and enter "npm run start" into the built in terminal and got the error. try "cd folder B", opening folder B in the ide, or organizing your stuff better than I did in the first place.

Determine if $.ajax error is a timeout

If your error event handler takes the three arguments (xmlhttprequest, textstatus, and message) when a timeout happens, the status arg will be 'timeout'.

Per the jQuery documentation:

Possible values for the second argument (besides null) are "timeout", "error", "notmodified" and "parsererror".

You can handle your error accordingly then.

I created this fiddle that demonstrates this.

    url: "/ajax_json_echo/",
    type: "GET",
    dataType: "json",
    timeout: 1000,
    success: function(response) { alert(response); },
    error: function(xmlhttprequest, textstatus, message) {
        if(textstatus==="timeout") {
            alert("got timeout");
        } else {

With jsFiddle, you can test ajax calls -- it will wait 2 seconds before responding. I put the timeout setting at 1 second, so it should error out and pass back a textstatus of 'timeout' to the error handler.

Hope this helps!

How can I list the contents of a directory in Python?

glob.glob or os.listdir will do it.

Cannot install Aptana Studio 3.6 on Windows

Had the same error initially. so.. pre-installed git and node.js and later installed Aptana, which installed perfectly. Rajeeva.

MySQL select one column DISTINCT, with corresponding other columns

The DISTINCT keyword doesn't really work the way you're expecting it to. When you use SELECT DISTINCT col1, col2, col3 you are in fact selecting all unique {col1, col2, col3} tuples.

Read and Write CSV files including unicode with Python 2.7

I couldn't respond to Mark above, but I just made one modification which fixed the error which was caused if data in the cells was not unicode, i.e. float or int data. I replaced this line into the UnicodeWriter function: "self.writer.writerow([s.encode("utf-8") if type(s)==types.UnicodeType else s for s in row])" so that it became:

class UnicodeWriter:
    def __init__(self, f, dialect=csv.excel, encoding="utf-8-sig", **kwds):
       self.queue = cStringIO.StringIO()
        self.writer = csv.writer(self.queue, dialect=dialect, **kwds) = f
        self.encoder = codecs.getincrementalencoder(encoding)()
    def writerow(self, row):
        '''writerow(unicode) -> None
        This function takes a Unicode string and encodes it to the output.
        self.writer.writerow([s.encode("utf-8") if type(s)==types.UnicodeType else s for s in row])
        data = self.queue.getvalue()
        data = data.decode("utf-8")
        data = self.encoder.encode(data)

    def writerows(self, rows):
        for row in rows:

You will also need to "import types".

How do I replace all line breaks in a string with <br /> elements?

Not answering the specific question, but I am sure this will help someone...

If you have output from PHP that you want to render on a web page using JavaScript (perhaps the result of an Ajax request), and you just want to retain white space and line breaks, consider just enclosing the text inside a <pre></pre> block:

var text_with_line_breaks = retrieve_some_text_from_php();
var element = document.querySelectorAll('#output');
element.innerHTML = '<pre>' + text_with_line_breaks + '</pre>';

How to allow remote access to my WAMP server for Mobile(Android)

I assume you are using windows. Open the command prompt and type ipconfig and find out your local address (on your pc) it should look something like or where the end digit is the one that changes. It should be next to IPv4 Address.

If your WAMP does not use virtual hosts the next step is to enter that IP address on your phones browser ie If you have a virtual host then you will need root to edit the hosts file.

If you want to test the responsiveness / mobile design of your website you can change your user agent in chrome or other browsers to mimic a mobile.


Edit: Chrome dev tools now has a mobile debug tool where you can change the size of the viewport, spoof user agents, connections (4G, 3G etc).

If you get forbidden access then see this question WAMP error: Forbidden You don't have permission to access /phpmyadmin/ on this server. Basically, change the occurrances of deny,allow to allow,deny in the httpd.conf file. You can access this by the WAMP menu.

To eliminate possible causes of the issue for now set your config file to

<Directory />
    Options FollowSymLinks
    AllowOverride All
    Order allow,deny
    Allow from all
        Require all granted

As thatis working for my windows PC, if you have the directory config block as well change that also to allow all.

Config file that fixed the problem:

Problem was that the /www apache directory config block still had deny set as default and only allowed from localhost.

How to find column names for all tables in all databases in SQL Server

Some minor improvements

->previous answers weren't showing all results

->possible to filter on column name by setting the column name variable

DECLARE @columnname nvarchar(150)
SET @columnname=''

DECLARE @SQL varchar(max)
''''.''''.'' COLLATE SQL_Latin1_General_CP1_CI_AS as name, COLLATE SQL_Latin1_General_CP1_CI_AS as columnname,c.column_id
from ''.sys.columns            c
    inner join ''.sys.objects  o on c.object_id=o.object_id
    INNER JOIN ''.sys.schemas  sh on o.schema_id=sh.schema_id
    where like ''%'+@columnname+'%'' and<>''sys'' 
FROM sys.databases d
SELECT @SQL=RIGHT(@SQL,LEN(@SQL)-5)+'order by 1,3'
--print @SQL

Checking if a character is a special character in Java

Take a look at class java.lang.Character static member methods (isDigit, isLetter, isLowerCase, ...)


String str = "Hello World 123 !!";
int specials = 0, digits = 0, letters = 0, spaces = 0;
for (int i = 0; i < str.length(); ++i) {
   char ch = str.charAt(i);
   if (!Character.isDigit(ch) && !Character.isLetter(ch) && !Character.isSpace(ch)) {
   } else if (Character.isDigit(ch)) {
   } else if (Character.isSpace(ch)) {
   } else {

How can I remove Nan from list Python/NumPy

Another way to do it would include using filter like this:

countries = list(filter(lambda x: str(x) != 'nan', countries))

How can I find which tables reference a given table in Oracle SQL Developer?

SQL Developer 4.1, released in May of 2015, added a Model tab which shows table foreign keys which refer to your table in an Entity Relationship Diagram format.

CSS list-style-image size

You can see how layout engines determine list-image sizes here:

There are three ways to do get around this while maintaining the benefits of CSS:

  1. Resize the image.
  2. Use a background-image and padding instead (easiest method).
  3. Use an SVG without a defined size using viewBox that will then resize to 1em when used as a list-style-image (Kudos to Jeremy).

php static function

Entire difference is, you don't get $this supplied inside the static function. If you try to use $this, you'll get a Fatal error: Using $this when not in object context.

Well, okay, one other difference: an E_STRICT warning is generated by your first example.

MySQL Sum() multiple columns

If any of your markn columns are "AllowNull" then you will need to do a little extra to insure the correct result is returned, this is because 1 NULL value will result in a NULL total.

This is what i would consider to be the correct answer.

SUM(IFNULL(`mark1`, 0) + IFNULL(`mark2`, 0) + IFNULL(`mark3`, 0)) AS `total_marks` 

IFNULL will return the 2nd parameter if the 1st is NULL. COALESCE could be used but i prefer to only use it if it is required. See What is the difference bewteen ifnull and coalesce in mysql?

SUM-ing the entire calculation is tidier than SUM-ing each column individually.

SELECT `student`, SUM(IFNULL(`mark1`, 0) + IFNULL(`mark2`, 0) + IFNULL(`mark3`, 0)) AS `total_marks` 
FROM student_scorecard
GROUP BY `student`

jQuery: what is the best way to restrict "number"-only input for textboxes? (allow decimal points)

Please add in the bottom of the script:

if(this.value.length == 1 && this.value == 0)
 this.value = "";

How to convert rdd object to dataframe in spark

Assuming your RDD[row] is called rdd, you can use:

val sqlContext = new SQLContext(sc) 
import sqlContext.implicits._

Shared-memory objects in multiprocessing

Like Robert Nishihara mentioned, Apache Arrow makes this easy, specifically with the Plasma in-memory object store, which is what Ray is built on.

I made brain-plasma specifically for this reason - fast loading and reloading of big objects in a Flask app. It's a shared-memory object namespace for Apache Arrow-serializable objects, including pickle'd bytestrings generated by pickle.dumps(...).

The key difference with Apache Ray and Plasma is that it keeps track of object IDs for you. Any processes or threads or programs that are running on locally can share the variables' values by calling the name from any Brain object.

$ pip install brain-plasma
$ plasma_store -m 10000000 -s /tmp/plasma

from brain_plasma import Brain
brain = Brain(path='/tmp/plasma/)

brain['a'] = [1]*10000

# >>> [1,1,1,1,...]

Centering FontAwesome icons vertically and horizontally

If you are using twitter Bootstrap add the class text-center to your code.

<div class='login-icon'><i class="icon-lock text-center"></i></div>

What is difference between Errors and Exceptions?

Error and Exception both extend Throwable, but mostly Error is thrown by JVM in a scenario which is fatal and there is no way for the application program to recover from that error. For instance OutOfMemoryError.

Though even application can raise an Error but its just not a good a practice, instead applications should use checked exceptions for recoverable conditions and runtime exceptions for programming errors.

How to specify a min but no max decimal using the range data annotation attribute?

using Range with

[Range(typeof(Decimal), "0", "9999", ErrorMessage = "{0} must be a decimal/number between {1} and {2}.")]

[Range(typeof(Decimal),"0.0", "1000000000000000000"]

Hope it will help

How to convert a std::string to const char* or char*?

char* result = strcpy((char*)malloc(str.length()+1), str.c_str());

How to make a 3-level collapsing menu in Bootstrap?

Bootstrap 2.3.x and later supports the dropdown-submenu..

<ul class="dropdown-menu">
            <li><a href="#">Login</a></li>
            <li class="dropdown-submenu">
                <a tabindex="-1" href="#">More options</a>
                <ul class="dropdown-menu">
                    <li><a tabindex="-1" href="#">Second level</a></li>
                    <li><a href="#">Second level</a></li>
                    <li><a href="#">Second level</a></li>
            <li><a href="#">Logout</a></li>

Working demo on

Swing JLabel text change on the running application

Use setText(str) method of JLabel to dynamically change text displayed. In actionPerform of button write this:

jLabel.setText("new Value");

A simple demo code will be:

    JFrame frame = new JFrame("Demo");
    frame.setLayout(new BorderLayout());

    final JLabel label = new JLabel("flag");
    JButton button = new JButton("Change flag");
    button.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            label.setText("new value");

    frame.add(label, BorderLayout.NORTH);
    frame.add(button, BorderLayout.CENTER);

How does the compilation/linking process work?

On the standard front:

  • a translation unit is the combination of a source files, included headers and source files less any source lines skipped by conditional inclusion preprocessor directive.

  • the standard defines 9 phases in the translation. The first four correspond to preprocessing, the next three are the compilation, the next one is the instantiation of templates (producing instantiation units) and the last one is the linking.

In practice the eighth phase (the instantiation of templates) is often done during the compilation process but some compilers delay it to the linking phase and some spread it in the two.

Dynamic Web Module 3.0 -- 3.1

I had similar troubles in eclipse and the only way to fix it for me was to

  • Remove the web module
  • Apply
  • Change the module version
  • Add the module
  • Configure (Further configuration available link at the bottom of the dialog)
  • Apply

Just make sure you configure the web module before applying it as by default it will look for your web files in /WebContent/ and this is not what Maven project structure should be.


Here is a second way in case nothing else helps

  • Exit eclipse, go to your project in the file system, then to .settings folder.
  • Open the org.eclipse.wst.common.project.facet.core.xml , make backup, and remove the web module entry.
  • You can also modify the web module version there, but again, no guarantees.

Instagram API - How can I retrieve the list of people a user is following on Instagram

You can use the following Instagram API Endpoint to get a list of people a user is following.{user-id}/follows?access_token=ACCESS-TOKEN

Here's the complete documentation for that endpoint. GET /users/user-id/follows

And here's a sample response from executing that endpoint. enter image description here

Since this endpoint required a user-id (and not user-name), depending on how you've written your API client, you might have to make a call to the /users/search endpoint with a username, and then get the user-id from the response and pass it on to the above /users/user-id/follows endpoint to get the list of followers.

IANAL, but considering it's documented in their API, and looking at the terms of use, I don't see how this wouldn't be legal to do.

Laravel Advanced Wheres how to pass variable into function?

You can pass variables using this...

$status =1;
 $info = JOBS::where(function($query) use ($status){        

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

With the above accepted best answer i made experiences with such not nice results and unsightly edges:

border without bezier path

So i will share my UIView Swift extension with you, that uses a UIBezierPath instead as border outline – without unsightly edges (inspired by @Fattie):

border with bezier path

//  UIView+BezierPathBorder.swift

import UIKit

extension UIView {

    fileprivate var bezierPathIdentifier:String { return "bezierPathBorderLayer" }

    fileprivate var bezierPathBorder:CAShapeLayer? {
        return (self.layer.sublayers?.filter({ (layer) -> Bool in
            return == self.bezierPathIdentifier && (layer as? CAShapeLayer) != nil
        }) as? [CAShapeLayer])?.first

    func bezierPathBorder(_ color:UIColor = .white, width:CGFloat = 1) {

        var border = self.bezierPathBorder
        let path = UIBezierPath(roundedRect: self.bounds, cornerRadius:self.layer.cornerRadius)
        let mask = CAShapeLayer()
        mask.path = path.cgPath
        self.layer.mask = mask

        if (border == nil) {
            border = CAShapeLayer()
            border!.name = self.bezierPathIdentifier

        border!.frame = self.bounds
        let pathUsingCorrectInsetIfAny =
            UIBezierPath(roundedRect: border!.bounds, cornerRadius:self.layer.cornerRadius)

        border!.path = pathUsingCorrectInsetIfAny.cgPath
        border!.fillColor = UIColor.clear.cgColor
        border!.strokeColor = color.cgColor
        border!.lineWidth = width * 2

    func removeBezierPathBorder() {
        self.layer.mask = nil



let view = UIView(frame: CGRect(x: 20, y: 20, width: 100, height: 100))
view.layer.cornerRadius = view.frame.width / 2
view.backgroundColor = .red

//add white 2 pixel border outline
view.bezierPathBorder(.white, width: 2)

//remove border outline (optional)

Permanently hide Navigation Bar in an activity

From Google documentation:

You can hide the navigation bar on Android 4.0 and higher using the SYSTEM_UI_FLAG_HIDE_NAVIGATION flag. This snippet hides both the navigation bar and the status bar:

View decorView = getWindow().getDecorView();
// Hide both the navigation bar and the status bar.
// SYSTEM_UI_FLAG_FULLSCREEN is only available on Android 4.1 and higher, but as
// a general rule, you should design your app to hide the status bar whenever you
// hide the navigation bar.
              | View.SYSTEM_UI_FLAG_FULLSCREEN;

Check if a string contains a substring in SQL Server 2005, using a stored procedure

CHARINDEX() searches for a substring within a larger string, and returns the position of the match, or 0 if no match is found

if CHARINDEX('ME',@mainString) > 0
    --do something

Edit or from daniels answer, if you're wanting to find a word (and not subcomponents of words), your CHARINDEX call would look like:

CHARINDEX(' ME ',' ' + REPLACE(REPLACE(@mainString,',',' '),'.',' ') + ' ')

(Add more recursive REPLACE() calls for any other punctuation that may occur)

How to change icon on Google map marker

You have to add the targeted map :

var markers = [
            "title": 'This is title',
            "lat": '-37.801578',
            "lng": '145.060508',
            "map":  map,
            "icon": '',
            "description": 'Vikash Rathee. <strong> This is test Description</strong> <br/><a href="">Pin Code by 


How to catch a specific SqlException error?

For those of you rookies out there who may throw a SQL error when connecting to the DB from another machine(For example, at form load), you will find that when you first setup a datatable in C# which points to a SQL server database that it will setup a connection like this:


You may need to remove this line and replace it with something else like a traditional connection string as mentioned on MSDN, etc.

Regular Expression to select everything before and up to a particular text


This will select all the content before the particular word ".txt" including any context in different lines up to 3 lines

JVM heap parameters

I created this toy example in scala, my_file.scala:

object MyObject {

    def main(args: Array[String]) {
        var ab = ArrayBuffer.empty[Int]

        for (i <- 0 to 100 * 1000 * 1000) {
            ab += i
            if (i % 10000 == 0) {
                println("On : %s".format(i))

I ran it with:

scala -J-Xms500m -J-Xmx7g my_file.scala


scala -J-Xms7g -J-Xmx7g my_file.scala

There are certainly noticeable pauses in -Xms500m version. I am positive that the short pauses are garbage collection runs, and the long ones are heap allocations.

Slidedown and slideup layout with animation

This doesn't work for me, I want to to like jquery slideUp / slideDown function, I tried this code, but it only move the content wich stay at the same place after animation end, the view should have a 0dp height at start of slideDown and the view height (with wrap_content) after the end of the animation.

Creating a Jenkins environment variable using Groovy

My environment was prior tooling such as Jenkins and was running with batch files (I know, I'm old). So those batch files (and their sub-batch files) are using environment variables. This was my piece of groovy script which injects environment variables. The names and parameters used are dummy ones.

// The process/batch which uses environment variables
def buildLabel = "SomeVersionNr"
def script = "startBuild.bat"
def processBuilder = new ProcessBuilder(script, buildLabel)

//Inject our environment variables
Map<String, String> env = processBuilder.environment()
env.put("ProjectRoot", "someLocation")
env.put("SomeVar", "Some")

Process p = processBuilder.start()

Of course if you set Jenkins up from scratch you would probably do it differently and share the variables in another way, or pass parameters around but this might come handy.

Sort Dictionary by keys

let dictionary = [
    "A" : [1, 2],
    "Z" : [3, 4],
    "D" : [5, 6]

let sortedKeys = Array(dictionary.keys).sorted(<) // ["A", "D", "Z"]


The sorted array from the above code contains keys only, while values have to be retrieved from the original dictionary. However, 'Dictionary' is also a 'CollectionType' of (key, value) pairs and we can use the global 'sorted' function to get a sorted array containg both keys and values, like this:

let sortedKeysAndValues = sorted(dictionary) { $0.0 < $1.0 }
println(sortedKeysAndValues) // [(A, [1, 2]), (D, [5, 6]), (Z, [3, 4])]

EDIT2: The monthly changing Swift syntax currently prefers

let sortedKeys = Array(dictionary.keys).sort(<) // ["A", "D", "Z"]

The global sorted is deprecated.

HTTPS connection Python

import requests
r = requests.get("") 
data = r.content  # Content of response

print r.status_code  # Status code of response
print data

How to mark a build unstable in Jenkins when running shell scripts

In my job script, I have the following statements (this job only runs on the Jenkins master):

# This is the condition test I use to set the build status as UNSTABLE
if [ ${PERCENTAGE} -gt 80 -a ${PERCENTAGE} -lt 90 ]; then
  echo WARNING: disc usage percentage above 80%

  # Download the Jenkins CLI JAR:
  curl -o jenkins-cli.jar ${JENKINS_URL}/jnlpJars/jenkins-cli.jar

  # Set build status to unstable
  java -jar jenkins-cli.jar -s ${JENKINS_URL}/ set-build-result unstable


You can see this and a lot more information about setting build statuses on the Jenkins wiki:

How to pass a file path which is in assets folder to File(String path)?

AFAIK, you can't create a File from an assets file because these are stored in the apk, that means there is no path to an assets folder.

But, you can try to create that File using a buffer and the AssetManager (it provides access to an application's raw asset files).

Try to do something like:

AssetManager am = getAssets();
InputStream inputStream ="myfoldername/myfilename");
File file = createFileFromInputStream(inputStream);

private File createFileFromInputStream(InputStream inputStream) {

      File f = new File(my_file_name);
      OutputStream outputStream = new FileOutputStream(f);
      byte buffer[] = new byte[1024];
      int length = 0;

      while(( > 0) {


      return f;
   }catch (IOException e) {
         //Logging exception

   return null;

Let me know about your progress.

Force Java timezone as GMT/UTC

You could change the timezone using TimeZone.setDefault():


Golang append an item to a slice

In your example the slice argument of the Test function receives a copy of the variable a in the caller's scope.

Since a slice variable holds a "slice descriptor" which merely references an underlying array, in your Test function you modify the slice descriptor held in the slice variable several times in a row, but this does not affect the caller and its a variable.

Inside the Test function, the first append reallocates the backing array under the slice variable, copies its original contents over, appends 100 to it, and that's what you're observing. Upon exiting from Test, the slice variable goes out of scope and so does the (new) underlying array that slice references. (Jeff Lee is correct about that it's not what really happens, so the updated version follows; as he correctly states, this answer is correct, if maybe a bit too terse.)

Outside the Test function, a slice of length 7 and capacity 8 is allocated, and its 7 elements filled.
Inside the Test function, the first append sees the that the slice's capacity is still one element larger than its length — in other words, there is room for one more element to add without reallocation. So it "eats up" that remaining element and places 100 to it, after which it adjusts the length in the copy of the slice descriptor to become equal to the slice's capaticy. This does not affect the slice descriptor's in the caller's scope.

And that's what you're observing. Upon exiting from Test, the slice variable goes out of scope and so does the (new) underlying array that slice references.

If you want to make Test behave like append, you have to return the new slice from it — just like append does — and require the callers of Test to use it in the same way they would use append:

func Test(slice []int) []int {
    slice = append(slice, 100)


    return slice

a = Test(a)

Please read this article thoroughly as it basically shows you how to implement append by hand, after explaining how slices are working internally. Then read this.

How to delete object?

You cannot delete an managed object in C# . That's why is called MANAGED language. So you don't have to troble yourself with delete (just like in c++).

It is true that you can set it's instance to null. But that is not going to help you that much because you have no control of your GC (Garbage collector) to delete some objects apart from Collect. And this is not what you want because this will delete all your collection from a generation.

So how is it done then ? So : GC searches periodically objects that are not used anymore and it deletes the object with an internal mechanism that should not concern you.

When you set an instance to null you just notify that your object has no referene anymore ant that could help CG to collect it faster !!!

format a number with commas and decimals in C# ( MVC3)

CultureInfo us = new CultureInfo("en-US");
TotalAmount.ToString("N", us)

Pandas concat: ValueError: Shape of passed values is blah, indices imply blah2

Aus_lacy's post gave me the idea of trying related methods, of which join does work:

In [196]: = 'hl'
In [199]:

high    low loc_h   loc_l   hl
2014-01-01 17:00:00 1.376235    1.375945    1.376235    1.375945    1.376090
2014-01-01 17:01:00 1.376005    1.375775    NaN NaN NaN
2014-01-01 17:02:00 1.375795    1.375445    NaN 1.375445    1.375445
2014-01-01 17:03:00 1.375625    1.375515    NaN NaN NaN

Some insight into why concat works on the example but not this data would be nice though!

Why doesn't Git ignore my specified file?

Please use this command

git rm -rf --cached .
git add .

Sometimes .gitignore files don't work even though they're correct. The reason Git ignores files is that they are not added to the repository. If you added a file that you want to ignore before, it will be tracked by Git, and any skipping matching rules will be skipped. Git does this because the file is already part of the repository.

convert double to int

Convert.ToInt32 is the best way to convert

nil detection in Go

The compiler is pointing the error to you, you're comparing a structure instance and nil. They're not of the same type so it considers it as an invalid comparison and yells at you.

What you want to do here is to compare a pointer to your config instance to nil, which is a valid comparison. To do that you can either use the golang new builtin, or initialize a pointer to it:

config := new(Config) // not nil


config := &Config{
                  host: "", 
                  port: 22,
                 } // not nil


var config *Config // nil

Then you'll be able to check if

if config == nil {
    // then

How to set a CheckBox by default Checked in ASP.Net MVC

You could set your property in the model's constructor

public YourModel()
    As = true;

How do I create a chart with multiple series using different X values for each series?

You need to use the Scatter chart type instead of Line. That will allow you to define separate X values for each series.

How to view the current heap size that an application is using?

Attach with jvisualvm from Sun Java 6 JDK. Startup flags are listed.

How do you remove columns from a data.frame?


# exclude variables v1, v2, v3
myvars <- names(mydata) %in% c("v1", "v2", "v3") 
newdata <- mydata[!myvars]

# exclude 3rd and 5th variable 
newdata <- mydata[c(-3,-5)]

# delete variables v3 and v5
mydata$v3 <- mydata$v5 <- NULL

Thought it was really clever make a list of "not to include"

Convert an integer to an array of digits

I can not add comments to the decision of Vladimir, but you can immediately make an array deployed in the right direction. Here is my solution:

public static int[] splitAnIntegerIntoAnArrayOfNumbers (int a) {
    int temp = a;
    ArrayList<Integer> array = new ArrayList<Integer>();
        array.add(temp % 10);
        temp /= 10;
    } while  (temp > 0);

    int[] arrayOfNumbers = new int[array.size()];
    for(int i = 0, j = array.size()-1; i < array.size(); i++,j--) 
        arrayOfNumbers [j] = array.get(i);
    return arrayOfNumbers;

Important: This solution will not work for negative integers.

Compute a confidence interval from sample data

Start with looking up the z-value for your desired confidence interval from a look-up table. The confidence interval is then mean +/- z*sigma, where sigma is the estimated standard deviation of your sample mean, given by sigma = s / sqrt(n), where s is the standard deviation computed from your sample data and n is your sample size.

Use of #pragma in C

All answers above make nice explanations for #pragma but I wanted to a add small example

I just want to explain a simple OpenMP example that demonstrate some uses of #pragma to doing its work

OpenMp briefly is an implementation for multi-platform shared-memory parallel programming (then we can say it's machine-specific or operating-system-specific)

let's go to the example

#include <stdio.h>
#include <omp.h>// compile with: /openmp

int main() {
   #pragma omp parallel num_threads(4)
      int i = omp_get_thread_num();
      printf_s("Hello from thread %d\n", i);

the output is

Hello from thread 0
Hello from thread 1
Hello from thread 2
Hello from thread 3

Note that the order of output can vary on different machines.

now let me tell you what #pragma did...

it tells the OS to run the some block of code on 4 threads

this is just one of many many applications you can do with the little #pragma

sorry for the outside sample OpenMP

How to left align a fixed width string?

This version uses the str.format method.

Python 2.7 and newer

sys.stdout.write("{:<7}{:<51}{:<25}\n".format(code, name, industry))

Python 2.6 version

sys.stdout.write("{0:<7}{1:<51}{2:<25}\n".format(code, name, industry))


Previously there was a statement in the docs about the % operator being removed from the language in the future. This statement has been removed from the docs.

Combining a class selector and an attribute selector with jQuery

I think you just need to remove the space. i.e.

$(".myclass[reference=12345]").css('border', '#000 solid 1px');

There is a fiddle here

How to convert List to Json in Java

For simplicity and well structured sake, use SpringMVC. It's just so simple.

public @ResponseBody List<String> getCarList() {
    return carService.getAllCars();

Reference and credit:

Is there a C++ gdb GUI for Linux?

KDevelop works pretty well.

How do I convert a Python 3 byte-string variable into a regular string?

You had it nearly right in the last line. You want

str(bytes_string, 'utf-8')

because the type of bytes_string is bytes, the same as the type of b'abc'.

Create an ArrayList of unique values

You could use a Set. It is a collection which doesn't accept duplicates.

Redirecting Output from within Batch file

@echo OFF
[your command] >> [Your log file name].txt

I used the command above in my batch file and it works. In the log file, it shows the results of my command.

Add a "sort" to a =QUERY statement in Google Spreadsheets

Sorting by C and D needs to be put into number form for the corresponding column, ie 3 and 4, respectively. Eg Order By 2 asc")

Flask-SQLalchemy update a row's information

There is a method update on BaseQuery object in SQLAlchemy, which is returned by filter_by.

num_rows_updated = User.query.filter_by(username='admin').update(dict(email='[email protected]')))

The advantage of using update over changing the entity comes when there are many objects to be updated.

If you want to give add_user permission to all the admins,

rows_changed = User.query.filter_by(role='admin').update(dict(permission='add_user'))

Notice that filter_by takes keyword arguments (use only one =) as opposed to filter which takes an expression.

How to debug a Flask app

For Windows users:

Open Powershell and cd into your project directory.

Use these commandos in Powershell, all the other stuff won't work in Powershell.

$env:FLASK_APP = "app"  
$env:FLASK_ENV = "development"

How to change the font and font size of an HTML input tag?

<input type ="text" id="txtComputer">



Does document.body.innerHTML = "" clear the web page?

Whilst agreeing with Douwe Maan and Erik's answers, there are a couple of other things here that you may find useful.

Firstly, within your head tags, you can reference a separate JavaScript file, which is then reusable:

<script language="JavaScript" src="/common/common.js"></script>

where common.js is your reusable function file in a top-level directory called common.

Secondly, you can delay the operation of a script using setTimeout, e.g.:

setTimeout(someFunction, 5000);

The second argument is in milliseconds. I mention this, because you appear to be trying to delay something in your original code snippet.

maven... Failed to clean project: Failed to delete ..\org.ow2.util.asm-asm-tree-3.1.jar

I have same problem and this

mvn clean install -U

command fixed the error.

How to rotate the background image in the container?

Update 2020, May:

Setting position: absolute and then transform: rotate(45deg) will provide a background:

div {_x000D_
  height: 200px;_x000D_
  width: 200px;_x000D_
  outline: 2px dashed slateBlue;_x000D_
  overflow: hidden;_x000D_
div img {_x000D_
  position: absolute;_x000D_
  transform: rotate(45deg);_x000D_
  z-index: -1;_x000D_
  top: 40px;_x000D_
  left: 40px;_x000D_
  <img src="" />_x000D_
  <h1>Hello World!</h1>_x000D_

Original Answer:

In my case, the image size is not so large that I cannot have a rotated copy of it. So, the image has been rotated with photoshop. An alternative to photoshop for rotating images is online tool too for rotating images. Once rotated, I'm working with the rotated-image in the background property.

div.with-background {
    background-image: url(/img/rotated-image.png);
    background-size:     contain;
    background-repeat:   no-repeat;
    background-position: top center;

Good Luck...

Switch statement for greater-than/less-than

Updating the accepted answer (can't comment yet). As of 1/12/16 using the demo jsfiddle in chrome, switch-immediate is the fastest solution.

Results: Time resolution: 1.33

   25ms "if-immediate" 150878146 
   29ms "if-indirect" 150878146
   24ms "switch-immediate" 150878146
   128ms "switch-range" 150878146
   45ms "switch-range2" 150878146
   47ms "switch-indirect-array" 150878146
   43ms "array-linear-switch" 150878146
   72ms "array-binary-switch" 150878146


 1.04 (   25ms) if-immediate
 1.21 (   29ms) if-indirect
 1.00 (   24ms) switch-immediate
 5.33 (  128ms) switch-range
 1.88 (   45ms) switch-range2
 1.96 (   47ms) switch-indirect-array
 1.79 (   43ms) array-linear-switch
 3.00 (   72ms) array-binary-switch

Hide particular div onload and then show div after click

$(document).ready(function() {
    $('#preview').on('click', function() {
        $('#div1').hide(300, function() { // first hide div1
            // then show div2

You missed # before div2

Working Sample