Programs & Examples On #Chop

Android Material and appcompat Manifest merger failed

If you do not intend to migrate to AndroidX follow the below steps

  1. In terminal type gradlew app:dependencies
  2. After dependencies are shown in the window press Ctrl+f and type androidX
  3. You will find all the dependencies which are using androidx lib internally you may have to downgrade that or use alternative for that to ensure it is no longer using androidX libs internally.

JS map return object

Use .map without return in simple way. Also start using let and const instead of var because let and const is more recommended

const rockets = [_x000D_
    { country:'Russia', launches:32 },_x000D_
    { country:'US', launches:23 },_x000D_
    { country:'China', launches:16 },_x000D_
    { country:'Europe(ESA)', launches:7 },_x000D_
    { country:'India', launches:4 },_x000D_
    { country:'Japan', launches:3 }_x000D_
const launchOptimistic = => (_x000D_
    launches: elem.launches+10_x000D_
  } _x000D_

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema

I had the same issue and I resolved this by making some changes in my web.config.js file. FYI I am using the latest version of webpack and webpack-cli. This trick just saved my day. I have attached the example of mine web.config.js file before and after version.


module.exports = {
    resolve: {
        extensions: ['.js', '.jsx']
    entry: './index.js',
    output: {
         filename: 'bundle.js'
    module: {
        loaders : [
           { test: /\.js?/, loader: 'bable-loader', exclude: /node_modules/ }

After: I Just replaced loaders to rules in module object as you can see in my code snippet.

module.exports = {
    resolve: {
        extensions: ['.js', '.jsx']
    entry: './index.js',
    output: {
        filename: 'bundle.js'
    module: {
        rules : [
            { test: /\.js?/, loader: 'bable-loader', exclude: /node_modules/ }

Hopefully, This will help someone to get rid out of this issue.

Consider marking event handler as 'passive' to make the page more responsive

For those stuck with legacy issues, find the line throwing the error and add {passive: true} - eg:

this.element.addEventListener(t, e, !1)


this.element.addEventListener(t, e, { passive: true} )

Python pandas: how to specify data types when reading an Excel file?

The read_excel() function has a converters argument, where you can apply functions to input in certain columns. You can use this to keep them as strings. Documentation:

Dict of functions for converting values in certain columns. Keys can either be integers or column labels, values are functions that take one input argument, the Excel cell content, and return the transformed content.

Example code:

pandas.read_excel(my_file, converters = {my_str_column: str})

How to add users to Docker container?

To avoid the interactive questions by adduser, you can call it with these parameters:

RUN adduser --disabled-password --gecos '' newuser

The --gecos parameter is used to set the additional information. In this case it is just empty.

On systems with busybox (like Alpine), use

RUN adduser -D -g '' newuser

See busybox adduser

Solve Cross Origin Resource Sharing with Flask

I used decorator given by Armin Ronacher with little modifications (due to different headers that are requested by the client).And that worked for me. (where I use angular as the requester requesting application/json type).

The code is slightly modified at below places,

from flask import jsonify

@app.route('/my_service', methods=['POST', 'GET','OPTIONS'])
def my_service():
    return jsonify(foo='cross domain ftw')

jsonify will send a application/json type, else it will be text/html. headers are added as the client in my case request for those headers

 const httpOptions = {
      headers: new HttpHeaders({
        'Content-Type': 'application/json',
    return<any>(url, item,httpOptions)

set initial viewcontroller in appdelegate - swift

Just in case you want to do it in the view controller and not in the app delegate: Just fetch the reference to the AppDelegate in your view controller and reset it's window object with the right view controller as it's rootviewController.

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
appDelegate.window = UIWindow(frame: UIScreen.mainScreen().bounds)
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let yourVC = mainStoryboard.instantiateViewControllerWithIdentifier("YOUR_VC_IDENTIFIER") as! YourViewController
appDelegate.window?.rootViewController = yourVC

How do I hide the status bar in a Swift iOS app?

A solution that works for me; if you want to hide the status bar on a specific view controller while loading:

import UIKit

class ViewController: UIViewController {

private var hideStatusBar: Bool = false

override var prefersStatusBarHidden: Bool {
    return hideStatusBar

override var preferredStatusBarUpdateAnimation: UIStatusBarAnimation {
    return UIStatusBarAnimation.slide

override func viewDidLoad() {

    view.backgroundcolor = .white
    hideStatusBar = true

    UIView.animate(withDuration: 0.3) {

Attention: if you set the key "View controller-based status bar appearance" to "NO" in your info.plist the code above doesn't work. You should set the key to "YES" or remove it from info.plist

"Could not find a part of the path" error message

Is the drive E a mapped drive? Then, it can be created by another account other than the user account. This may be the cause of the error.

ImportError: numpy.core.multiarray failed to import

Tilde folders

In the event pip uninstall numpy and reinstallation of Numpy does not work. Review your site-packages folder for sub-folders beginning with a tilde ~

These folders relate to pip installations that got mangled and the installation was aborted part way through. The tilde folders were only ever meant to be tmp folders but ended up becoming permanent. In my case there was a file called ~mpy which was a mangled legacy Numpy folder. This led to compatibility issues and ImportErrors.

These mangled folders can safely be deleted, for further details see this answer

Get current time in hours and minutes

I have another solution for your question .

In the first when use date the output is like this :

Thu 28 Jan 2021 22:29:40 IST

Then if you want only to show current time in hours and minutes you can use this command :

date | cut -d " " -f5 | cut -d ":" -f1-2 

Then the output :


Controlling fps with requestAnimationFrame?

Skipping requestAnimationFrame cause not smooth(desired) animation at custom fps.

// Input/output DOM elements_x000D_
var $results = $("#results");_x000D_
var $fps = $("#fps");_x000D_
var $period = $("#period");_x000D_
// Array of FPS samples for graphing_x000D_
// Animation state/parameters_x000D_
var fpsInterval, lastDrawTime, frameCount_timed, frameCount, lastSampleTime, _x000D_
  currentFps=0, currentFps_timed=0;_x000D_
var intervalID, requestID;_x000D_
// Setup canvas being animated_x000D_
var canvas = document.getElementById("c");_x000D_
var canvas_timed = document.getElementById("c2");_x000D_
canvas_timed.width = canvas.width = 300;_x000D_
canvas_timed.height = canvas.height = 300;_x000D_
var ctx = canvas.getContext("2d");_x000D_
var ctx2 = canvas_timed.getContext("2d");_x000D_
// Setup input event handlers_x000D_
$fps.on('click change keyup', function() {_x000D_
    if (this.value > 0) {_x000D_
        fpsInterval = 1000 / +this.value;_x000D_
$period.on('click change keyup', function() {_x000D_
    if (this.value > 0) {_x000D_
        if (intervalID) {_x000D_
        intervalID = setInterval(sampleFps, +this.value);_x000D_
function startAnimating(fps, sampleFreq) {_x000D_
    ctx.fillStyle = ctx2.fillStyle = "#000";_x000D_
    ctx.fillRect(0, 0, canvas.width, canvas.height);_x000D_
    ctx2.fillRect(0, 0, canvas.width, canvas.height);_x000D_
    ctx2.font = ctx.font = "32px sans";_x000D_
    fpsInterval = 1000 / fps;_x000D_
    lastDrawTime =;_x000D_
    lastSampleTime = lastDrawTime;_x000D_
    frameCount = 0;_x000D_
    frameCount_timed = 0;_x000D_
    intervalID = setInterval(sampleFps, sampleFreq);_x000D_
function sampleFps() {_x000D_
    // sample FPS_x000D_
    var now =;_x000D_
    if (frameCount > 0) {_x000D_
        currentFps =_x000D_
            (frameCount / (now - lastSampleTime) * 1000).toFixed(2);_x000D_
        currentFps_timed =_x000D_
            (frameCount_timed / (now - lastSampleTime) * 1000).toFixed(2);_x000D_
        $results.text(currentFps + " | " + currentFps_timed);_x000D_
        frameCount = 0;_x000D_
        frameCount_timed = 0;_x000D_
    lastSampleTime = now;_x000D_
function drawNextFrame(now, canvas, ctx, fpsCount) {_x000D_
    // Just draw an oscillating seconds-hand_x000D_
    var length = Math.min(canvas.width, canvas.height) / 2.1;_x000D_
    var step = 15000;_x000D_
    var theta = (now % step) / step * 2 * Math.PI;_x000D_
    var xCenter = canvas.width / 2;_x000D_
    var yCenter = canvas.height / 2;_x000D_
    var x = xCenter + length * Math.cos(theta);_x000D_
    var y = yCenter + length * Math.sin(theta);_x000D_
    ctx.moveTo(xCenter, yCenter);_x000D_
    ctx.lineTo(x, y);_x000D_
   ctx.fillStyle = ctx.strokeStyle = 'white';_x000D_
    var theta2 = theta + 3.14/6;_x000D_
    ctx.moveTo(xCenter, yCenter);_x000D_
    ctx.lineTo(x, y);_x000D_
    ctx.arc(xCenter, yCenter, length*2, theta, theta2);_x000D_
    ctx.fillStyle = "rgba(0,0,0,.1)"_x000D_
    ctx.fillStyle = "#000";_x000D_
    ctx.fillStyle = "#080";_x000D_
// redraw second canvas each fpsInterval (1000/fps)_x000D_
function animate_timed() {_x000D_
    drawNextFrame(, canvas_timed, ctx2, currentFps_timed);_x000D_
    setTimeout(animate_timed, fpsInterval);_x000D_
function animate(now) {_x000D_
    // request another frame_x000D_
    // calc elapsed time since last loop_x000D_
    var elapsed = now - lastDrawTime;_x000D_
    // if enough time has elapsed, draw the next frame_x000D_
    if (elapsed > fpsInterval) {_x000D_
        // Get ready for next frame by setting lastDrawTime=now, but..._x000D_
        // Also, adjust for fpsInterval not being multiple of 16.67_x000D_
        lastDrawTime = now - (elapsed % fpsInterval);_x000D_
      drawNextFrame(now, canvas, ctx, currentFps);_x000D_
startAnimating(+$fps.val(), +$period.val());
  padding:0px 25px;_x000D_
<script src=""></script>_x000D_
<h3>requestAnimationFrame skipping <span id="tvs">vs.</span> setTimeout() redraw</h3>_x000D_
    <input id="fps" type="number" value="33"/> FPS:_x000D_
    <span id="results"></span>_x000D_
    <input id="period" type="number" value="1000"/> Sample period (fps, ms)_x000D_
<canvas id="c"></canvas><canvas id="c2"></canvas>

Original code by @tavnab.

Detect if the app was launched/opened from a push notification

if somebody wants the answer in swift 3

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {
    switch application.applicationState {
    case .active:
        //app is currently active, can update badges count here
    case .inactive:
        //app is transitioning from background to foreground (user taps notification), do what you need when user taps here
    case .background:
        //app is in background, if content-available key of your notification is set to 1, poll to your backend to retrieve data and update your interface here

Linq filter List<string> where it contains a string value from another List<string>

its even easier:

fileList.Where(item => filterList.Contains(item))

in case you want to filter not for an exact match but for a "contains" you can use this expression:

var t = fileList.Where(file => filterList.Any(folder => file.ToUpperInvariant().Contains(folder.ToUpperInvariant())));

Launch iOS simulator from Xcode and getting a black screen, followed by Xcode hanging and unable to stop tasks

What happened with me was the Type of class was not UIViewController for the script attached to my view controller. It was for a UITabController..... I had mistakenly quickly created the wrong type of class.... So make sure the class if the correct type.. Hope this helps someone. I was in a rush and made this mistake.

Error HRESULT E_FAIL has been returned from a call to a COM component VS2012 when debugging

Maybe this page helps:

Scenario Two: The Microsoft Visual Studio 2010 IDE crashes while creating OR debugging a web application project. This above error occurs because of corrupted Cache of Visual Studio 2010. In order to resolve the issue just delete the project Cache from the below location:

C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE\ProjectTemplatesCache

C:\Program Files(x86)\Microsoft Visual Studio 10.0\Common7\IDE\ProjectTemplatesCache

Then run devenv.exe /setup to re-build the cache.

Directory.GetFiles of certain extension

If you would like to do your filtering in LINQ, you can do it like this:

var ext = new List<string> { "jpg", "gif", "png" };
var myFiles = Directory
    .EnumerateFiles(dir, "*.*", SearchOption.AllDirectories)
    .Where(s => ext.Contains(Path.GetExtension(s).TrimStart(".").ToLowerInvariant()));

Now ext contains a list of allowed extensions; you can add or remove items from it as necessary for flexible filtering.

NSInternalInconsistencyException', reason: 'Could not load NIB in bundle: 'NSBundle

enter image description here

In Identity inspector change class name with the corresponding identifier and also In Attributes inspector modify Indentifier then it should work as expected.

Right pad a string with variable number of spaces

The easiest way to right pad a string with spaces (without them being trimmed) is to simply cast the string as CHAR(length). MSSQL will sometimes trim whitespace from VARCHAR (because it is a VARiable-length data type). Since CHAR is a fixed length datatype, SQL Server will never trim the trailing spaces, and will automatically pad strings that are shorter than its length with spaces. Try the following code snippet for example.


This returns the value 'Test '.

Twitter Bootstrap: div in container with 100% height

you need to add padding-top to "fill" element, plus add box-sizing:border-box - sample here bootply

iPad Safari scrolling causes HTML elements to disappear and reappear with a delay

In my case (an iOS Phonegap app), applying translate3d to relative child elements did not resolve the issue. My scrollable element didn't have a set height as it was absolutely positioned and I was defining the top and bottom positions. What fixed it for me was adding a min-height (of 100px).

Xcode error - Thread 1: signal SIGABRT

You are trying to load a XIB named DetailViewController, but no such XIB exists or it's not member of your current target.

CSS transition when class removed

The @jfriend00's answer helps me to understand the technique to animate only remove class (not add).

A "base" class should have transition property (like transition: 2s linear all;). This enables animations when any other class is added or removed on this element. But to disable animation when other class is added (and only animate class removing) we need to add transition: none; to the second class.



.issue {
  background-color: lightblue;
  transition: 2s linear all;

.recently-updated {
  background-color: yellow;
  transition: none;


<div class="issue" onclick="addClass()">click me</div>

JS (only needed to add class):

var timeout = null;

function addClass() {
  if (timeout) {
    timeout = null;
  timeout = setTimeout(function () {
  }, 1000);

plunker of this example.

With this code only removing of recently-updated class will be animated.

Get device token for push notification

And the Swift version of the Wasif's answer:

Swift 2.x

var token = deviceToken.description.stringByTrimmingCharactersInSet(NSCharacterSet(charactersInString: "<>"))
token = token.stringByReplacingOccurrencesOfString(" ", withString: "")
print("Token is \(token)")

Update for Swift 3

let deviceTokenString = { String(format: "%02.2hhx", $0) }.joined()

iOS application: how to clear notifications?

It might also make sense to add a call to clearNotifications in applicationDidBecomeActive so that in case the application is in the background and comes back it will also clear the notifications.

- (void)applicationDidBecomeActive:(UIApplication *)application
    [self clearNotifications];

Limiting the number of characters in a string, and chopping off the rest

The solution may be java.lang.String.format("%" + maxlength + "s", string).trim(), like this:

int maxlength = 20;
String longString = "Any string you want which length is greather than 'maxlength'";
String shortString = "Anything short";
String resultForLong = java.lang.String.format("%" + maxlength + "s", longString).trim();
String resultForShort = java.lang.String.format("%" + maxlength + "s", shortString).trim();


Any string you want w

Anything short

Applications are expected to have a root view controller at the end of application launch

Try to connect IBOutlet of tab bar controller to root view in the Interface Builder instead of

self.window.rootViewController = self.tabBarController;

But actually I haven't seen such error before.

How to edit HTML input value colour?

Please try this:

<input class="col-xs-12 col-sm-8 col-sm-offset-2 col-md-8 col-md-offset-2" type="text" name="name" value="" placeholder="Your Name" style="background-color:blue;"/>

You basically put all the CSS inside the style part of the input tag and it works.

how to read a text file using scanner in Java?

This should help you..:

import static java.lang.System.*;
* Write a description of class InRead here.
* @author (your name) 
* @version (a version number or a date)
public class InRead
public InRead(String Recipe)
public void find(String Name){
    String newRecipe= Name+".txt";
        FileReader fr= new FileReader(newRecipe);
        BufferedReader br= new BufferedReader(fr);

        String str;

    while ((str=br.readLine()) != null){
            out.println(str + "\n");

    }catch (IOException e){
        out.println("File Not Found!");


Get all files and directories in specific path fast

In .NET 4.0 there's the Directory.EnumerateFiles method which returns an IEnumerable<string> and is not loading all the files in memory. It's only once you start iterating over the returned collection that files will be returned and exceptions could be handled.

curl_init() function not working

(Trying to get Curl working via PHP and Apache on Windows...)

I kept getting an error saying: Call to undefined function 'curl_init()'

I made sure I had enabled curl with this line in my php.ini file: extension=php_curl.dll

I made sure the extension_dir variable was being set properly, like this: extension_dir = "ext"

I was doing everything everyone else said on the forums and curl was not showing up in my call to phpinfo(), and I kept getting that same error from above.

Finally I found out that Apache by default looks for php.ini in the C:\Windows folder. I had been changing php.ini in my PHP installation folder. Once I copied my php.ini into C:\Windows, everything worked.

Took me forever to figure that out, so thought I'd post in case it helps someone else.

Simple and fast method to compare images for similarity

Can the screenshot or icon be transformed (scaled, rotated, skewed ...)? There are quite a few methods on top of my head that could possibly help you:

  • Simple euclidean distance as mentioned by @carlosdc (doesn't work with transformed images and you need a threshold).
  • (Normalized) Cross Correlation - a simple metrics which you can use for comparison of image areas. It's more robust than the simple euclidean distance but doesn't work on transformed images and you will again need a threshold.
  • Histogram comparison - if you use normalized histograms, this method works well and is not affected by affine transforms. The problem is determining the correct threshold. It is also very sensitive to color changes (brightness, contrast etc.). You can combine it with the previous two.
  • Detectors of salient points/areas - such as MSER (Maximally Stable Extremal Regions), SURF or SIFT. These are very robust algorithms and they might be too complicated for your simple task. Good thing is that you do not have to have an exact area with only one icon, these detectors are powerful enough to find the right match. A nice evaluation of these methods is in this paper: Local invariant feature detectors: a survey.

Most of these are already implemented in OpenCV - see for example the cvMatchTemplate method (uses histogram matching): The salient point/area detectors are also available - see OpenCV Feature Detection.

How to write the code for the back button?

<a href="javascript:history.back(1)">Back</a>

this one (by Eiko) is perfect, use css to make a button of <a>... eg you can use this css class in <a> as `

<a class=".back_button" href="javascript:history.back(1)">Back</a>`

.back_button {
border:1px solid #000000;

What is the easiest way to remove the first character from a string?

Using regex:

str = 'string'
n = 1  #to remove first n characters

str[/.{#{str.size-n}}\z/] #=> "tring"

Viewing full output of PS command

simple and perfect:

ps -efww

won't truncate line

Escape quotes in JavaScript

Escape whitespace as well. It sounds to me like Firefox is assuming three arguments instead of one. &nbsp; is the non-breaking space character. Even if it's not the whole problem, it may still be a good idea.

How can I get my webapp's base URL in ASP.NET MVC?

This works fine for me (also with a load balancer):

    var urlHelper = new UrlHelper(Html.ViewContext.RequestContext);
    var baseurl = urlHelper.Content(“~”);

    var base_url = "@baseurl";

Especially if you are using non-standard port numbers, using Request.Url.Authority appears like a good lead at first, but fails in a LB environment.

How to call a Web Service Method?

James' answer is correct, of course, but I should remind you that the whole ASMX thing is, if not obsolete, at least not the current method. I strongly suggest that you look into WCF, if only to avoid learning things you will need to forget.

JavaScript chop/slice/trim off last character in string

You can use slice! You just have to make sure you know how to use it. Positive #s are relative to the beginning, negative numbers are relative to the end.


CSS Printing: Avoiding cut-in-half DIVs between pages?

page-break-inside: avoid; does not seem to always work. It seems to take into account the height and positioning of container elements.

For example, inline-block elements that are taller than the page will get clipped.

I was able to restore working page-break-inside: avoid; functionality by identifying a container element with display: inline-block and adding:

@media print {
    .container { display: block; } /* this is key */

    div, p, ..etc { page-break-inside: avoid; }

Hope this helps folks who complain that "page-break-inside does not work".

Fastest way to determine if an integer's square root is an integer

If speed is a concern, why not partition off the most commonly used set of inputs and their values to a lookup table and then do whatever optimized magic algorithm you have come up with for the exceptional cases?

Can you call Directory.GetFiles() with multiple filters?

I can't use .Where method because I'm programming in .NET Framework 2.0 (Linq is only supported in .NET Framework 3.5+).

Code below is not case sensitive (so .CaB or .cab will be listed too).

string[] ext = new string[2] { "*.CAB", "*.MSU" };

foreach (string found in ext)
    string[] extracted = Directory.GetFiles("C:\\test", found, System.IO.SearchOption.AllDirectories);

    foreach (string file in extracted)

How to Truncate a string in PHP to the word closest to a certain number of characters?

I have a function that does almost what you want, if you'll do a few edits, it will fit exactly:

function stripByWords($string,$length,$delimiter = '<br>') {
    $words_array = explode(" ",$string);
    $strlen = 0;
    $return = '';
    foreach($words_array as $word) {
        $strlen += mb_strlen($word,'utf8');
        $return .= $word." ";
        if($strlen >= $length) {
            $strlen = 0;
            $return .= $delimiter;
    return $return;

Calculate rolling / moving average in C++

One way can be to circularly store the values in the buffer array. and calculate average this way.

int j = (int) (counter % size);
buffer[j] = mostrecentvalue;
avg = (avg * size - buffer[j - 1 == -1 ? size - 1 : j - 1] + buffer[j]) / size;


// buffer[j - 1 == -1 ? size - 1 : j - 1] is the oldest value stored

The whole thing runs in a loop where most recent value is dynamic.

Show/Hide Div on Scroll

  <div class="a">

$(window).scroll(function() {
  if ($(this).scrollTop() > 0) {
  } else {


Is gcc's __attribute__((packed)) / #pragma pack unsafe?

(The following is a very artificial example cooked up to illustrate.) One major use of packed structs is where you have a stream of data (say 256 bytes) to which you wish to supply meaning. If I take a smaller example, suppose I have a program running on my Arduino which sends via serial a packet of 16 bytes which have the following meaning:

0: message type (1 byte)
1: target address, MSB
2: target address, LSB
3: data (chars)
F: checksum (1 byte)

Then I can declare something like

typedef struct {
  uint8_t msgType;
  uint16_t targetAddr; // may have to bswap
  uint8_t data[12];
  uint8_t checksum;
} __attribute__((packed)) myStruct;

and then I can refer to the targetAddr bytes via aStruct.targetAddr rather than fiddling with pointer arithmetic.

Now with alignment stuff happening, taking a void* pointer in memory to the received data and casting it to a myStruct* will not work unless the compiler treats the struct as packed (that is, it stores data in the order specified and uses exactly 16 bytes for this example). There are performance penalties for unaligned reads, so using packed structs for data your program is actively working with is not necessarily a good idea. But when your program is supplied with a list of bytes, packed structs make it easier to write programs which access the contents.

Otherwise you end up using C++ and writing a class with accessor methods and stuff that does pointer arithmetic behind the scenes. In short, packed structs are for dealing efficiently with packed data, and packed data may be what your program is given to work with. For the most part, you code should read values out of the structure, work with them, and write them back when done. All else should be done outside the packed structure. Part of the problem is the low level stuff that C tries to hide from the programmer, and the hoop jumping that is needed if such things really do matter to the programmer. (You almost need a different 'data layout' construct in the language so that you can say 'this thing is 48 bytes long, foo refers to the data 13 bytes in, and should be interpreted thus'; and a separate structured data construct, where you say 'I want a structure containing two ints, called alice and bob, and a float called carol, and I don't care how you implement it' -- in C both these use cases are shoehorned into the struct construct.)

Calculate percentage Javascript


const result = Math.round((data.expense / data.income) * 100)

Use of symbols '@', '&', '=' and '>' in custom directive's scope binding: AngularJS

< one-way binding

= two-way binding

& function binding

@ pass only strings

Doctrine 2: Update query with query builder

Let's say there is an administrator dashboard where users are listed with their id printed as a data attribute so it can be retrieved at some point via JavaScript.

An update could be executed this way …

class UserRepository extends \Doctrine\ORM\EntityRepository
    public function updateUserStatus($userId, $newStatus)
        return $this->createQueryBuilder('u')
            ->set('u.isActive', '?1')
            ->setParameter(1, $qb->expr()->literal($newStatus))
            ->where(' = ?2')
            ->setParameter(2, $qb->expr()->literal($userId))

AJAX action handling:

# Post datas may be:
# handled with a specific custom formType — OR — retrieved from request object
$userId = (int)$request->request->get('userId');
$newStatus = (int)$request->request->get('newStatus');
$em = $this->getDoctrine()->getManager();
$r = $em->getRepository('NAMESPACE\User')
        ->updateUserStatus($userId, $newStatus);
if ( !empty($r) ){
    # Row updated

Working example using Doctrine 2.5 (on top of Symfony3).

IIS_IUSRS and IUSR permissions in IIS8

IUSR is part of IIS_IUSER i guess you can remove the permissions for IUSR without worrying. Further Reading

However, a problem arose over time as more and more Windows system services started to run as NETWORKSERVICE. This is because services running as NETWORKSERVICE can tamper with other services that run under the same identity. Because IIS worker processes run third-party code by default (Classic ASP, ASP.NET, PHP code), it was time to isolate IIS worker processes from other Windows system services and run IIS worker processes under unique identities. The Windows operating system provides a feature called "Virtual Accounts" that allows IIS to create unique identities for each of its Application Pools. DefaultAppPool is the by default pool that is assigned to all Application Pool you create.

To make it more secure you can change the IIS DefaultAppPool Identity to ApplicationPoolIdentity.

Regarding permission, Create and Delete summarizes all the rights that can be given. So whatever you have assigned to the IIS_USERS group is that they will require. Nothing more, nothing less.

hope this helps.

How to convert java.lang.Object to ArrayList?

An interesting note: it appears that attempting to cast from an object to a list on the JavaFX Application thread always results in a ClassCastException.

I had the same issue as you, and no answer helped. After playing around for a while, the only thing I could narrow it down to was the thread. Running the code to cast on any other thread other than the UI thread succeeds as expected, and as the other answers in this section suggest.

Thus, be careful that your source isn't running on the JavaFX application thread.

Reset Windows Activation/Remove license key

On Windows XP -

  1. Reboot into "Safe mode with Command Prompt"
  2. Type "explorer" in the command prompt that comes up and push [Enter]
  3. Click on Start>Run, and type the following :

    rundll32.exe syssetup,SetupOobeBnk

Reboot, and login as normal.

This will reset the 30 day timer for activation back to 30 days so you can enter in the key normally.

SQL Server command line backup statement

You can use sqlcmd to run a backup, or any other T-SQL script. You can find the detailed instructions and examples on various useful sqlcmd switches in this article: Working with the SQL Server command line (sqlcmd)

Error # 1045 - Cannot Log in to MySQL server -> phpmyadmin

You need to do two additional things after following the link that you have mentioned in your post:

One have to map the changed login cridentials in phpmyadmin's

and second, you need to restart your web and mysql servers..

php version is not the issue need to go to phpmyadmin installation directory and find file and in that file put your current mysql password at line

$cfg['Servers'][$i]['user'] = 'root'; //mysql username here
$cfg['Servers'][$i]['password'] = 'password'; //mysql password here

Unique constraint violation during insert: why? (Oracle)

Your error looks like you are duplicating an already existing Primary Key in your DB. You should modify your sql code to implement its own primary key by using something like the IDENTITY keyword.

    [DBId] bigint NOT NULL IDENTITY,



Laravel - Session store not set on request

A problem can be that you try to access you session inside of your controller's __constructor() function.

From Laravel 5.3+ this is not possible anymore because it is not intended to work anyway, as stated in the upgrade guide.

In previous versions of Laravel, you could access session variables or the authenticated user in your controller's constructor. This was never intended to be an explicit feature of the framework. In Laravel 5.3, you can't access the session or authenticated user in your controller's constructor because the middleware has not run yet.

For more background information also read Taylor his response.


If you still want to use this, you can dynamically create a middleware and run it in the constructor, as described in the upgrade guide:

As an alternative, you may define a Closure based middleware directly in your controller's constructor. Before using this feature, make sure that your application is running Laravel 5.3.4 or above:


namespace App\Http\Controllers;

use App\User;
use Illuminate\Support\Facades\Auth;
use App\Http\Controllers\Controller;

class ProjectController extends Controller
     * All of the current user's projects.
    protected $projects;

     * Create a new controller instance.
     * @return void
    public function __construct()
        $this->middleware(function ($request, $next) {
            $this->projects = Auth::user()->projects;

            return $next($request);

How do I make a redirect in PHP?

Many of these answers are correct, but they assume you have an absolute URL, which may not be the case. If you want to use a relative URL and generate the rest, then you can do something like this...

$url = 'http://' . $_SERVER['HTTP_HOST'];            // Get the server
$url .= rtrim(dirname($_SERVER['PHP_SELF']), '/\\'); // Get the current directory
$url .= '/your-relative/path-goes/here/';            // <-- Your relative path
header('Location: ' . $url, true, 302);              // Use either 301 or 302

Currency formatting in Python

See the locale module.

This does currency (and date) formatting.

>>> import locale
>>> locale.setlocale( locale.LC_ALL, '' )
'English_United States.1252'
>>> locale.currency( 188518982.18 )
>>> locale.currency( 188518982.18, grouping=True )

td widths, not working?

try to use

word-wrap: break-word;

hope this help

Private properties in JavaScript ES6 classes

For future reference of other on lookers, I'm hearing now that the recommendation is to use WeakMaps to hold private data.

Here is a more clear, working example:

function storePrivateProperties(a, b, c, d) {
  let privateData = new WeakMap;
  // unique object as key, weak map can only accept object as key, when key is no longer referened, garbage collector claims the key-value 
  let keyA = {}, keyB = {}, keyC = {}, keyD = {};

  privateData.set(keyA, a);
  privateData.set(keyB, b);
  privateData.set(keyC, c);
  privateData.set(keyD, d);

  return {
    logPrivateKey(key) {
      switch(key) {
      case "a":
      case "b":
      case "c":
      case "d":
        console.log(`There is no value for ${key}`)

How to reduce the image size without losing quality in PHP

I'd go for jpeg. Read this post regarding image size reduction and after deciding on the technique, use ImageMagick

Hope this helps

Check if checkbox is NOT checked on click - jQuery

$(document).ready(function() {
        $("#check1").click(function() {
            var checked = $(this).is(':checked');
            if (checked) {
            } else {

Using getline() in C++

I know I'm late but I hope this is useful. Logic is for taking one line at a time if the user wants to enter many lines

int main() 
int t;                    // no of lines user wants to enter
string str;
cin.ignore();            // for clearing newline in cin
    getline(cin,str);    // accepting one line, getline is teminated when newline is found 
return 0; 

input :


Government collage Berhampore

Serampore textile collage

Berhampore Serampore

output :

Government collage Berhampore

Serampore textile collage

Berhampore Serampore

Force “landscape” orientation mode


Will force it to change to and stay in landscape mode. Tested on Nexus 5.

How to add images to on GitHub?

I usually host the image on the site, this can link to any hosted image. Just toss this in the readme. Works for .rst files, not sure about .md

.. image:: https://url/path/to/image
   :height: 100px
   :width: 200 px
   :scale: 50 %

How to make <input type="file"/> accept only these types?

for powerpoint and pdf files:

<input type="file" placeholder="Do you have a .ppt?" name="pptfile" id="pptfile" accept="application/pdf,application/,application/vnd.openxmlformats-officedocument.presentationml.slideshow,application/vnd.openxmlformats-officedocument.presentationml.presentation"/>

How to check if NSString begins with a certain character

As a more general answer, try using the hasPrefix method. For example, the code below checks to see if a string begins with 10, which is the error code used to identify a certain problem.

NSString* myString = @"10:Username taken";

if([myString hasPrefix:@"10"]) {
      //display more elegant error message

A field initializer cannot reference the nonstatic field, method, or property

you can use like this

private dynamic defaultReminder => reminder.TimeSpanText[TimeSpan.FromMinutes(15)]; 

Error in Swift class: Property not initialized at super.init call

You are just initing in the wrong order.

     class Shape2 {
        var numberOfSides = 0
        var name: String
        init(name:String) {
   = name
        func simpleDescription() -> String {
            return "A shape with \(numberOfSides) sides."

    class Square2: Shape2 {
        var sideLength: Double

        init(sideLength:Double, name:String) {

            self.sideLength = sideLength
            super.init(name:name) // It should be behind "self.sideLength = sideLength"
            numberOfSides = 4
        func area () -> Double {
            return sideLength * sideLength

Counting number of characters in a file through shell script


wc -m $1 | awk '{print $1}'

wc -m counts the number of characters; the awk command prints the number of characters only, omitting the filename.

wc -c would give you the number of bytes (which can be different to the number of characters, as depending on the encoding you may have a character encoded on several bytes).

'ls' is not recognized as an internal or external command, operable program or batch file

I'm fairly certain that the ls command is for Linux, not Windows (I'm assuming you're using Windows as you referred to cmd, which is the command line for the Windows OS).

You should use dir instead, which is the Windows equivalent of ls.

Edit (since this post seems to be getting so many views :) ):

You can't use ls on cmd as it's not shipped with Windows, but you can use it on other terminal programs (such as GitBash). Note, ls might work on some FTP servers if the servers are linux based and the FTP is being used from cmd.

dir on Windows is similar to ls. To find out the various options available, just do dir/?.

If you really want to use ls, you could install 3rd party tools to allow you to run unix commands on Windows. Such a program is Microsoft Windows Subsystem for Linux (link to docs).

How to get $(this) selected option in jQuery?

Best guess:

var cur_value = $('#select-id').children('option:selected').text();

I like children better in this case because you know you're only going one branch down the DOM tree...

Failed to find Build Tools revision 23.0.1

As the error says Failed to find build Tools revision 23.0.1 This means that in your project you have used buildToolsVersion "23.0.3" So,You need to download the exact same version this makes the error disappear

**Step 1:**
GO to Tools and click SDK Manager
**Step 2:**
you can see SDK Platforms ,SDK Tools and SDK update Sites
Click SDK Tools and click show package details
**Step 4:**
Select the version that you have mentioned in your Project 

These Steps has solved my issue.

Calculate difference between two dates (number of days)?

You can try this


Linking dll in Visual Studio

I find it useful to understand the underlying tools. These are cl.exe (compiler) and link.exe (linker). You need to tell the compiler the signatures of the functions you want to call in the dynamic library (by including the library's header) and you need to tell the linker what the library is called and how to call it (by including the "implib" or import library).

This is roughly the same process gcc uses for linking to dynamic libraries on *nix, only the library object file differs.

Knowing the underlying tools means you can more quickly find the appropriate settings in the IDE and allows you to check that the commandlines generated are correct.


Say A.exe depends B.dll. You need to include B's header in A.cpp (#include "B.h") then compile and link with B.lib:

cl A.cpp /c /EHsc
link A.obj B.lib

The first line generates A.obj, the second generates A.exe. The /c flag tells cl not to link and /EHsc specifies what kind of C++ exception handling the binary should use (there's no default, so you have to specify something).

If you don't specify /c cl will call link for you. You can use the /link flag to specify additional arguments to link and do it all at once if you like:

cl A.cpp /EHsc /link B.lib

If B.lib is not on the INCLUDE path you can give a relative or absolute path to it or add its parent directory to your include path with the /I flag.

If you're calling from cygwin (as I do) replace the forward slashes with dashes.

If you write #pragma comment(lib, "B.lib") in A.cpp you're just telling the compiler to leave a comment in A.obj telling the linker to link to B.lib. It's equivalent to specifying B.lib on the link commandline.

How to run script as another user without password?

Call visudo and add this:

user1 ALL=(user2) NOPASSWD: /home/user2/bin/

The command paths must be absolute! Then call sudo -u user2 /home/user2/bin/ from a user1 shell. Done.

Procedure expects parameter which was not supplied

I came across this error today when null values were passed to my stored procedure's parameters. I was able easily fix by altering the stored procedure by adding default value = null.

Case statement in MySQL

Yes, something like this:

        WHEN action_type = 'Income' THEN action_amount
        ELSE NULL
    END AS income_amt,
        WHEN action_type = 'Expense' THEN action_amount
        ELSE NULL
    END AS expense_amt

FROM tbl_transaction;

As other answers have pointed out, MySQL also has the IF() function to do this using less verbose syntax. I generally try to avoid this because it is a MySQL-specific extension to SQL that isn't generally supported elsewhere. CASE is standard SQL and is much more portable across different database engines, and I prefer to write portable queries as much as possible, only using engine-specific extensions when the portable alternative is considerably slower or less convenient.

jQuery Scroll to Div

Could just use JQuery position function to get coordinates of your div, then use javascript scroll:

var position = $("div").position();

Stop all active ajax requests in jQuery

I have updated the code to make it works for me

$.xhrPool = [];
$.xhrPool.abortAll = function() {
    $(this).each(function(idx, jqXHR) {
    $(this).each(function(idx, jqXHR) {
        var index = $.inArray(jqXHR, $.xhrPool);
        if (index > -1) {
            $.xhrPool.splice(index, 1);

    beforeSend: function(jqXHR) {
    complete: function(jqXHR) {
        var index = $.inArray(jqXHR, $.xhrPool);
        if (index > -1) {
            $.xhrPool.splice(index, 1);

Maven and adding JARs to system scope

System scope was only designed to deal with 'system' files; files sitting in some fixed location. Files in /usr/lib, or ${java.home} (e.g. tools.jar). It wasn't designed to support miscellaneous .jar files in your project.

The authors intentionally refused to make the pathname expansions work right for that to discourage you. As a result, in the short term you can use install:install-file to install into the local repo, and then some day use a repo manager to share.

How to "pretty" format JSON output in Ruby on Rails

Pretty print variant:

my_object = { :array => [1, 2, 3, { :sample => "hash"}, 44455, 677778, 9900 ], :foo => "bar", rrr: {"pid": 63, "state": false}}
puts my_object.as_json.pretty_inspect.gsub('=>', ': ')


{"array": [1, 2, 3, {"sample": "hash"}, 44455, 677778, 9900],
 "foo": "bar",
 "rrr": {"pid": 63, "state": false}}

How to scroll the page when a modal dialog is longer than the screen?

Here is my demo of modal window that auto-resize to its content and starts scrolling when it does not fit the window.

Modal window demo (see comments in the HTML source code)

All done only with HTML and CSS - no JS required to display and resize the modal window (but you still need it to display the window of course - in new version you don't need JS at all).

Update (more demos):

The point is to have outer and inner DIVs where the outer one defines the fixed position and the inner creates the scrolling. (In the demo there are actually more DIVs to make them look like an actual modal window.)

        #modal {
            position: fixed;
            transform: translate(0,0);
            width: auto; left: 0; right: 0;
            height: auto; top: 0; bottom: 0;
            z-index: 990; /* display above everything else */
            padding: 20px; /* create padding for inner window - page under modal window will be still visible */

        #modal .outer {
            box-sizing: border-box; -moz-box-sizing: border-box; -webkit-box-sizing: border-box; -o-box-sizing: border-box;
            width: 100%;
            height: 100%;
            position: relative;
            z-index: 999;

        #modal .inner {
            box-sizing: border-box; -moz-box-sizing: border-box; -webkit-box-sizing: border-box; -o-box-sizing: border-box;
            width: 100%;
            height: auto;       /* allow to fit content (if smaller)... */
            max-height: 100%;   /* ... but make sure it does not overflow browser window */

            /* allow vertical scrolling if required */
            overflow-x: hidden;
            overflow-y: auto;

            /* definition of modal window layout */
            background: #ffffff;
            border: 2px solid #222222;
            border-radius: 16px; /* some nice (modern) round corners */
            padding: 16px;       /* make sure inner elements does not overflow round corners */

How to get http headers in flask?

If any one's trying to fetch all headers that were passed then just simply use:


it gives you all the headers in a dict from which you can actually do whatever ops you want to. In my use case I had to forward all headers to another API since the python API was a proxy

Jersey stopped working with InjectionManagerFactory not found

Here is the reason. Starting from Jersey 2.26, Jersey removed HK2 as a hard dependency. It created an SPI as a facade for the dependency injection provider, in the form of the InjectionManager and InjectionManagerFactory. So for Jersey to run, we need to have an implementation of the InjectionManagerFactory. There are two implementations of this, which are for HK2 and CDI. The HK2 dependency is the jersey-hk2 others are talking about.


The CDI dependency is


This (jersey-cdi2-se) should only be used for SE environments and not EE environments.

Jersey made this change to allow others to provide their own dependency injection framework. They don't have any plans to implement any other InjectionManagers, though others have made attempts at implementing one for Guice.

How to make a machine trust a self-signed Java application

Just Go To *Startmenu >>Java >>Configure Java >> Security >> Edit site list >> copy and paste your Link with problem >> OK Problem fixed :)*

MongoDB running but can't connect using shell

I had same problem. In my case MongoDB server wasn't running.

Try to open this in your web browser:


If you can't, this means that you have to start MongoDB server.

Run mongod in another terminal tab. Then in your main tab run mongo which is is the shell that connects to your MongoDB server.

How to POST a FORM from HTML to ASPX page

The Request.Form.Keys collection will be empty if none of your html inputs have NAMEs. It's easy to forget to put them there after you've been doing .NET for a while. Just name them and you'll be good to go.

Masking password input from the console : Java

If you're dealing with a Java character array (such as password characters that you read from the console), you can convert it to a JRuby string with the following Ruby code:

# GIST: "pw_from_console.rb" under ""

jconsole = Java::java.lang.System.console()
password = jconsole.readPassword()
ruby_string = ''
password.to_a.each {|c| ruby_string << c.chr}

# .. do something with 'password' variable ..    
puts "password_chars: #{password_chars.inspect}"
puts "password_string: #{password_string}"

See also "" and ""

How to save a git commit message from windows cmd?

With the atom editor, you just need to install the git-plus package.

How can I count the occurrences of a list item?

Why not using Pandas?

import pandas as pd

l = ['a', 'b', 'c', 'd', 'a', 'd', 'a']

# converting the list to a Series and counting the values
my_count = pd.Series(l).value_counts()


a    3
d    2
b    1
c    1
dtype: int64

If you are looking for a count of a particular element, say a, try:




Create a Path from String in Java7

You can just use the Paths class:

Path path = Paths.get(textPath);

... assuming you want to use the default file system, of course.

C# windows application Event: CLR20r3 on application start

.NET has two CLRs 2.0 and 4.0. CLR 2.0 works till .NET framework 3.5. CLR 4.0 works from .NET 4.0 onwards. Its possible that your solution is using a different CLR than your reference assemblies. In your local development environment, you might have both the CLRs and hence you did not faced any problem. However when you moved to deployment environments, they might have a single CLR only and you got this error.

Forward request headers from nginx proxy server

The problem is that '_' underscores are not valid in header attribute. If removing the underscore is not an option you can add to the server block:

underscores_in_headers on;

This is basically a copy and paste from @kishorer747 comment on @Fleshgrinder answer, and solution is from:

I added it here as in my case the application behind nginx was working perfectly fine, but as soon ngix was between my flask app and the client, my flask app would not see the headers any longer. It was kind of time consuming to debug.

RegEx to extract all matches from string using RegExp.exec


returns all matches as an array.

If, for some mysterious reason, you need the additional information comes with exec, as an alternative to previous answers, you could do it with a recursive function instead of a loop as follows (which also looks cooler :).

function findMatches(regex, str, matches = []) {
   const res = regex.exec(str)
   res && matches.push(res) && findMatches(regex, str, matches)
   return matches

// Usage
const matches = findMatches(/regex/g, str)

as stated in the comments before, it's important to have g at the end of regex definition to move the pointer forward in each execution.

How to list all `env` properties within jenkins pipeline job?

According to Jenkins documentation for declarative pipeline:

sh 'printenv'

For Jenkins scripted pipeline:

echo sh(script: 'env|sort', returnStdout: true)

The above also sorts your env vars for convenience.

Converting Hexadecimal String to Decimal Integer

Since there is no brute-force approach which (done with it manualy). To know what exactly happened.

Given a hexadecimal number


The equivalent decimal value is:

K? * 16? + K??1 * 16??1 + K??2 * 16??2 + .... + K2 * 162 + K1 * 161 + K0 * 160

For example, the hex number AB8C is:

10 * 163 + 11 * 162 + 8 * 161 + 12 * 160 = 43916


 //convert hex to decimal number
private static int hexToDecimal(String hex) {
    int decimalValue = 0;
    for (int i = 0; i < hex.length(); i++) {
        char hexChar = hex.charAt(i);
        decimalValue = decimalValue * 16 + hexCharToDecimal(hexChar);
    return decimalValue;
private static int hexCharToDecimal(char character) {
    if (character >= 'A' && character <= 'F')
        return 10 + character - 'A';
    else //character is '0', '1',....,'9'
        return character - '0';

TypeError: '<=' not supported between instances of 'str' and 'int'

input() by default takes the input in form of strings.

if (0<= vote <=24):

vote takes a string input (suppose 4,5,etc) and becomes uncomparable.

The correct way is: vote = int(input("Enter your message")will convert the input to integer (4 to 4 or 5 to 5 depending on the input)

How to access nested elements of json object using getJSONArray method

I suggest you to use Gson library. It allows to parse JSON string into object data model. Please, see my example:

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


public class GsonProgram {

    public static void main(String... args) {
        String response = "{\"result\":{\"map\":{\"entry\":[{\"key\":{\"@xsi.type\":\"xs:string\",\"$\":\"ContentA\"},\"value\":\"fsdf\"},{\"key\":{\"@xsi.type\":\"xs:string\",\"$\":\"ContentB\"},\"value\":\"dfdf\"}]}}}";

        Gson gson = new GsonBuilder().serializeNulls().create();
        Response res = gson.fromJson(response, Response.class);

        System.out.println("Entries: " + res.getResult().getMap().getEntry());

class Response {

    private Result result;

    public Result getResult() {
        return result;

    public void setResult(Result result) {
        this.result = result;

    public String toString() {
        return result.toString();

class Result {

    private MapNode map;

    public MapNode getMap() {
        return map;

    public void setMap(MapNode map) { = map;

    public String toString() {
        return map.toString();

class MapNode {

    List<Entry> entry = new ArrayList<Entry>();

    public List<Entry> getEntry() {
        return entry;

    public void setEntry(List<Entry> entry) {
        this.entry = entry;

    public String toString() {
        return Arrays.toString(entry.toArray());

class Entry {

    private Key key;
    private String value;

    public String getValue() {
        return value;

    public void setValue(String value) {
        this.value = value;

    public Key getKey() {
        return key;

    public void setKey(Key key) {
        this.key = key;

    public String toString() {
        return "[key=" + key + ", value=" + value + "]";

class Key {

    private String value;

    private String type;

    public String getValue() {
        return value;

    public void setValue(String value) {
        this.value = value;

    public String getType() {
        return type;

    public void setType(String type) {
        this.type = type;

    public String toString() {
        return "[value=" + value + ", type=" + type + "]";

Program output:

Entries: [[key=[value=ContentA, type=xs:string], value=fsdf], [key=[value=ContentB, type=xs:string], value=dfdf]]

If you not familiar with this library, then you can find a lot of informations in "Gson User Guide".

Comparing boxed Long values 127 and 128

Comparing non-primitives (aka Objects) in Java with == compares their reference instead of their values. Long is a class and thus Long values are Objects.

The problem is that the Java Developers wanted people to use Long like they used long to provide compatibility, which led to the concept of autoboxing, which is essentially the feature, that long-values will be changed to Long-Objects and vice versa as needed. The behaviour of autoboxing is not exactly predictable all the time though, as it is not completely specified.

So to be safe and to have predictable results always use .equals() to compare objects and do not rely on autoboxing in this case:

Long num1 = 127, num2 = 127;
if(num1.equals(num2)) { iWillBeExecutedAlways(); }

Using multiple parameters in URL in express

For what you want I would've used

    app.get('/fruit/:fruitName&:fruitColor', function(request, response) {
       const name = request.params.fruitName 
       const color = request.params.fruitColor 

or better yet

    app.get('/fruit/:fruit', function(request, response) {
       const fruit = request.params.fruit

where fruit is a object. So in the client app you just call{"name":"My fruit name", "color":"The color of the fruit"}

and as a response you should see:

    //  client side response
    // { name: My fruit name, color:The color of the fruit}

How to produce a range with step n in bash? (generate a sequence of numbers with increments)

I'd do

for i in `seq 0 2 10`; do echo $i; done

(though of course seq 0 2 10 will produce the same output on its own).

Note that seq allows floating-point numbers (e.g., seq .5 .25 3.5) but bash's brace expansion only allows integers.

What are sessions? How do they work?

HTTP is stateless connection protocol, that is, the server cannot differentiate between different connections of different users.

Hence comes cookie, once a client connects first time to a server, the server generates a new session id, which later will be sent to the client as cookie value. And from now on, this session id will identify that client connection, because within each HTTP request it will see the appropriate session id inside cookies.

Now for each session id, the server keeps some data structure, which enables him to store data specific to user, this data structure you can abstractly call session.

How to convert a String to CharSequence?

Attempting to provide some (possible) context for OP's question by posting my own trouble. I'm working in Scala, but the error messages I'm getting all reference Java types, and the error message reads a lot like the compiler complaining that CharSequence is not a String. I confirmed in the source code that String implements the CharSequence interface, but the error message draws attention to the difference between String and CharSequence while hiding the real source of the trouble:

scala> cols
res8: Iterable[String] = List(Item, a, b)

scala> val header = String.join(",", cols)
<console>:13: error: overloaded method value join with alternatives:
  (x$1: CharSequence,x$2: java.lang.Iterable[_ <: CharSequence])String <and>
  (x$1: CharSequence,x$2: CharSequence*)String
 cannot be applied to (String, Iterable[String])
       val header = String.join(",", cols)

I was able to fix this problem with the realization that the problem wasn't String / CharSequence, but rather a mismatch between java.lang.Iterable and Scala's built-in Iterable.

scala> val header = String.join(",", coll: _*)
header: String = Item,a,b

My particular problem can also be solved via the answers at Scala: join an iterable of strings

In summary, OP and others who come across similar problems should parse the error messages very closely and see what other type conversions might be involved.

Preferred way of getting the selected item of a JComboBox

The first method is right.

The second method kills kittens if you attempt to do anything with x after the fact other than Object methods.

How to create a batch file to run cmd as administrator

You can use a shortcut that links to the batch file. Just go into properties for the shortcut and select advanced, then "run as administrator".

Then just make the batch file hidden, and run the shortcut.

This way, you can even set your own icon for the shortcut.

Detecting installed programs via registry

User-specific settings should be written to HKCU\Software, machine-specific settings to HKLM\Software. Under these keys, structure [software vendor name]\[application name] (e.g. HKLM\Software\Microsoft\Internet Explorer) may be the most common, but that's just a convention, not a law of nature.

Many (most?) applications also add their uninstall entries to HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall\[app name], but again, not all applications do this.

These are the most important keys; however, contents of the registry do not have to represent the installed software exactly - maybe the application was installed once, but then was manually deleted, or maybe the uninstaller didn't remove all traces of it. If you want to be sure, check the filesystem to see if the application still exists where its registry entries say it is.


If you're a member of the group Administrators, you can check the HKEY_USERS hive - each user's HKCU actually resides there (you'll need to know the user SID, or go through all of them).

Note: As @Brian Ensink says, "installed" is a bit of a vague concept - are we trying to find what the user could run? Some software doesn't even write to the Registry at all: search for "portable apps" to see apps that have been specifically modified to run directly from media (CD/USB) and not to leave any traces on the computer. We may also have to scan the disks, and network disks, and anything the user downloads, and world-accessible Windows shares in the Internet (yes, such things exist legitimately - \\\tools comes to mind). In this direction, there's no real limit of what the user can run, unless prevented by system policies.

android download pdf from url then open it with a pdf reader

This is the best method to download and view PDF file.You can just call it from anywhere as like

PDFTools.showPDFUrl(context, url);

here below put the code. It will works fine

public class PDFTools {
private static final String TAG = "PDFTools";
private static final String GOOGLE_DRIVE_PDF_READER_PREFIX = "";
private static final String PDF_MIME_TYPE = "application/pdf";
private static final String HTML_MIME_TYPE = "text/html";

public static void showPDFUrl(final Context context, final String pdfUrl ) {
    if ( isPDFSupported( context ) ) {
        downloadAndOpenPDF(context, pdfUrl);
    } else {
        askToOpenPDFThroughGoogleDrive( context, pdfUrl );

public static void downloadAndOpenPDF(final Context context, final String pdfUrl) {
    // Get filename
    //final String filename = pdfUrl.substring( pdfUrl.lastIndexOf( "/" ) + 1 );
    String filename = "";
    try {
        filename = new GetFileInfo().execute(pdfUrl).get();
    } catch (InterruptedException e) {
    } catch (ExecutionException e) {
    // The place where the downloaded PDF file will be put
    final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), filename );
    Log.e(TAG,"File Path:"+tempFile);
    if ( tempFile.exists() ) {
        // If we have downloaded the file before, just go ahead and show it.
        openPDF( context, Uri.fromFile( tempFile ) );

    // Show progress dialog while downloading
    final ProgressDialog progress = context, context.getString( R.string.pdf_show_local_progress_title ), context.getString( R.string.pdf_show_local_progress_content ), true );

    // Create the download request
    DownloadManager.Request r = new DownloadManager.Request( Uri.parse( pdfUrl ) );
    r.setDestinationInExternalFilesDir( context, Environment.DIRECTORY_DOWNLOADS, filename );
    final DownloadManager dm = (DownloadManager) context.getSystemService( Context.DOWNLOAD_SERVICE );
    BroadcastReceiver onComplete = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            if ( !progress.isShowing() ) {
            context.unregisterReceiver( this );

            long downloadId = intent.getLongExtra( DownloadManager.EXTRA_DOWNLOAD_ID, -1 );
            Cursor c = dm.query( new DownloadManager.Query().setFilterById( downloadId ) );

            if ( c.moveToFirst() ) {
                int status = c.getInt( c.getColumnIndex( DownloadManager.COLUMN_STATUS ) );
                if ( status == DownloadManager.STATUS_SUCCESSFUL ) {
                    openPDF( context, Uri.fromFile( tempFile ) );
    context.registerReceiver( onComplete, new IntentFilter( DownloadManager.ACTION_DOWNLOAD_COMPLETE ) );

    // Enqueue the request
    dm.enqueue( r );

public static void askToOpenPDFThroughGoogleDrive( final Context context, final String pdfUrl ) {
    new AlertDialog.Builder( context )
            .setTitle( R.string.pdf_show_online_dialog_title )
            .setMessage( R.string.pdf_show_online_dialog_question )
            .setNegativeButton( R.string.pdf_show_online_dialog_button_no, null )
            .setPositiveButton( R.string.pdf_show_online_dialog_button_yes, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    openPDFThroughGoogleDrive(context, pdfUrl);

public static void openPDFThroughGoogleDrive(final Context context, final String pdfUrl) {
    Intent i = new Intent( Intent.ACTION_VIEW );
    i.setDataAndType(Uri.parse(GOOGLE_DRIVE_PDF_READER_PREFIX + pdfUrl ), HTML_MIME_TYPE );
    context.startActivity( i );

public static final void openPDF(Context context, Uri localUri ) {
    Intent i = new Intent( Intent.ACTION_VIEW );
    i.setDataAndType( localUri, PDF_MIME_TYPE );
    context.startActivity( i );

public static boolean isPDFSupported( Context context ) {
    Intent i = new Intent( Intent.ACTION_VIEW );
    final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), "test.pdf" );
    i.setDataAndType( Uri.fromFile( tempFile ), PDF_MIME_TYPE );
    return context.getPackageManager().queryIntentActivities( i, PackageManager.MATCH_DEFAULT_ONLY ).size() > 0;

// get File name from url
static class GetFileInfo extends AsyncTask<String, Integer, String>
    protected String doInBackground(String... urls)
        URL url;
        String filename = null;
        try {
            url = new URL(urls[0]);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                String depo = conn.getHeaderField("Content-Disposition");

                String depoSplit[] = depo.split("filename=");
                filename = depoSplit[1].replace("filename=", "").replace("\"", "").trim();
                filename = "download.pdf";
        } catch (MalformedURLException e1) {
        } catch (IOException e) {
        return filename;

    protected void onPreExecute() {
    protected void onPostExecute(String result) {
        // use result as file name


try it. it will works, enjoy

How change List<T> data to IQueryable<T> data

var list = new List<string>();
var queryable = list.AsQueryable();

Add a reference to: System.Linq

How to check SQL Server version

Here is what i have done to find the version Here is what i have done to find the version: just write SELECT @@version and it will give you the version.

vba listbox multicolumn add

Simplified example (with counter):

With Me.lstbox
    .ColumnCount = 2
    .ColumnWidths = "60;60"
    .List(i, 0) = Company_ID
    .List(i, 1) = Company_name 
    i = i + 1

end with

Make sure to start the counter with 0, not 1 to fill up a listbox.

HTML - Change\Update page contents without refreshing\reloading the page

You've got the right idea, so here's how to go ahead: the onclick handlers run on the client side, in the browser, so you cannot call a PHP function directly. Instead, you need to add a JavaScript function that (as you mentioned) uses AJAX to call a PHP script and retrieve the data. Using jQuery, you can do something like this:

<script type="text/javascript">
function recp(id) {
  $('#myStyle').load('data.php?id=' + id);

<a href="#" onClick="recp('1')" > One   </a>
<a href="#" onClick="recp('2')" > Two   </a>
<a href="#" onClick="recp('3')" > Three </a>

<div id='myStyle'>

Then you put your PHP code into a separate file: (I've called it data.php in the above example)

  require ('myConnect.php');     
  $id = $_GET['id'];
  $results = mysql_query("SELECT para FROM content WHERE  para_ID='$id'");   
  if( mysql_num_rows($results) > 0 )
   $row = mysql_fetch_array( $results );
   echo $row['para'];

How can I add a .npmrc file?

There are a few different points here:

  1. Where is the .npmrc file created.
  2. How can you download private packages

Running npm config ls -l will show you all the implicit settings for npm, including what it thinks is the right place to put the .npmrc. But if you have never logged in (using npm login) it will be empty. Simply log in to create it.

Another thing is #2. You can actually do that by putting a .npmrc file in the NPM package's root. It will then be used by NPM when authenticating. It also supports variable interpolation from your shell so you could do stuff like this:

; Get the auth token to use for fetching private packages from our private scope
; see
; and also


Sum rows in data.frame or matrix

I came here hoping to find a way to get the sum across all columns in a data table and run into issues implementing the above solutions. A way to add a column with the sum across all columns uses the cbind function:

cbind(data, total = rowSums(data))

This method adds a total column to the data and avoids the alignment issue yielded when trying to sum across ALL columns using the above solutions (see the post below for a discussion of this issue).

Adding a new column to matrix error

How to print float to n decimal places including trailing 0s?

The cleanest way in modern Python >=3.6, is to use an f-string with string formatting:

>>> var = 1.6
>>> f"{var:.15f}"

Docker is in volume in use, but there aren't any Docker containers

I am pretty sure that those volumes are actually mounted on your system. Look in /proc/mounts and you will see them there. You will likely need to sudo umount <path> or sudo umount -f -n <path>. You should be able to get the mounted path either in /proc/mounts or through docker volume inspect

How to determine whether an object has a given property in JavaScript

Since question was regarding clunkiness of property checking, and one regular usecase for that being validation of function argument options objects, thought I'd mention a library-free short way of testing existence of multiple properties. Disclaimer: It does require ECMAScript 5 (but IMO anyone still using IE8 deserves a broken web).

function f(opts) {
  if(!["req1","req2"].every(opts.hasOwnProperty, opts)) {
      throw new Error("IllegalArgumentException");
f({req1: 123});  // error
f({req1: 123, req2: 456});  // ok

Programmatically generate video or animated GIF in Python?

from PIL import Image
import glob  #use it if you want to read all of the certain file type in the directory
for i in range(596,691): 
    print("scanned the image identified with",i)  

starting and ending value+1 of the index that identifies different file names

imgs = glob.glob("*.png") #do this if you want to read all files ending with .png

my files were: snap596.png, snap597.png ...... snap690.png

frames = []
for i in imgs:
    new_frame =

Save into a GIF file that loops forever

frames[0].save('fire3_PIL.gif', format='GIF',
    duration=300, loop=0)

I found flickering issue with imageio and this method fixed it.

Example: Communication between Activity and Service using Messaging

I have seen all answers. I want tell most robust way now a day. That will make you communicate between Activity - Service - Dialog - Fragments (Everything).


This lib which i am using in my projects has great features related to messaging.

EventBus in 3 steps

  1. Define events:

    public static class MessageEvent { /* Additional fields if needed */ }

  2. Prepare subscribers:

Declare and annotate your subscribing method, optionally specify a thread mode:

@Subscribe(threadMode = ThreadMode.MAIN) 
public void onMessageEvent(MessageEvent event) {/* Do something */};

Register and unregister your subscriber. For example on Android, activities and fragments should usually register according to their life cycle:

public void onStart() {

public void onStop() {
  1. Post events:

    EventBus.getDefault().post(new MessageEvent());

Just add this dependency in your app level gradle

compile 'org.greenrobot:eventbus:3.1.1'

Search for a particular string in Oracle clob column

Use dbms_lob.instr and dbms_lob.substr, just like regular InStr and SubstStr functions.
Look at simple example:

SQL> create table t_clob(
  2    id number,
  3    cl clob
  4  );

Tabela zosta¦a utworzona.

SQL> insert into t_clob values ( 1, ' xxxx abcd xyz qwerty 354657 [] ' );

1 wiersz zosta¦ utworzony.

SQL> declare
  2    i number;
  3  begin
  4    for i in 1..400 loop
  5        update t_clob set cl = cl || ' xxxx abcd xyz qwerty 354657 [] ';
  6    end loop;
  7    update t_clob set cl = cl || ' CALCULATION=[N]NEW.PRODUCT_NO=[T9856] OLD.PRODUCT_NO=[T9852].... -- with other text ';
  8    for i in 1..400 loop
  9        update t_clob set cl = cl || ' xxxx abcd xyz qwerty 354657 [] ';
 10    end loop;
 11  end;
 12  /

Procedura PL/SQL zosta¦a zako?czona pomytlnie.

SQL> commit;

Zatwierdzanie zosta¦o uko?czone.
SQL> select length( cl ) from t_clob;


SQL> select dbms_lob.instr( cl, 'NEW.PRODUCT_NO=[' ) from t_clob;


SQL> select dbms_lob.substr( cl, 5,dbms_lob.instr( cl, 'NEW.PRODUCT_NO=[' ) + length( 'NEW.PRODUCT_NO=[') ) new_product
  2  from t_clob;


How do you create a Swift Date object?

Here's how I did it in Swift 4.2:

extension Date {

    /// Create a date from specified parameters
    /// - Parameters:
    ///   - year: The desired year
    ///   - month: The desired month
    ///   - day: The desired day
    /// - Returns: A `Date` object
    static func from(year: Int, month: Int, day: Int) -> Date? {
        let calendar = Calendar(identifier: .gregorian)
        var dateComponents = DateComponents()
        dateComponents.year = year
        dateComponents.month = month = day
        return dateComponents) ?? nil


let marsOpportunityLaunchDate = Date.from(year: 2003, month: 07, day: 07)

How to install XNA game studio on Visual Studio 2012?

Yes, it's possible with a bit of tweak. Unfortunately, you still have to have VS 2010 installed.

  1. First, install XNA Game Studio 4.0. The easiest way is to install the Windows Phone SDK 7.1 which contains everything required.

  2. Copy the XNA Game Extension from VS 10 to VS 11 by opening a command prompt 'as administrator' and executing the following (may vary if not x64 computer with defaults paths) :

    xcopy /e "C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\Extensions\Microsoft\XNA Game Studio 4.0" "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\Extensions\Microsoft\XNA Game Studio 4.0"

  3. Run notepad as administrator then open extension.vsixmanifest in the destination directory just created.

  4. Upgrade the Supported product version to match the new version (or duplicate the whole VisualStudio element and change the Version attribute, as @brainslugs83 said in comments):

      <VisualStudio Version="11.0">
  5. Don't forget to clear/delete your cache in %localappdata%\Microsoft\VisualStudio\12.0\Extensions.

  6. You may have to run the command to tells Visual Studio that new extensions are available. If you see an 'access denied' message, try launching the console as an administrator.

    "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\devenv.exe" /setup

This has been tested for Windows Games, but not WP7 or Xbox games.

[Edit] According Jowsty, this works also for XBox 360 Games.

[Edit for Visual Studio 2013 & Windows 8.1] See here for documentation on installing Windows Phone SDK 7.1 on Windows 8.1. Use VS version number 12.0 in place of 11.0 for all of these steps, and they will still work correctly.

How to determine SSL cert expiration date from a PEM encoded certificate?

If (for some reason) you want to use a GUI application in Linux, use gcr-viewer (in most distributions it is installed by the package gcr (otherwise in package gcr-viewer))

gcr-viewer file.pem
# or
gcr-viewer file.crt

Is there any way to return HTML in a PHP function? (without building the return value as a string)

Create a template file and use a template engine to read/update the file. It will increase your code's maintainability in the future as well as separate display from logic.

An example using Smarty:

Template File

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "">


function TestBlockHTML(){
  $smarty = new Smarty();
  $smarty->assign('title', 'My Title');
  $smarty->assign('string', $replStr);
  return $smarty->render('template.tpl');

Best TCP port number range for internal applications

Short answer: use an unassigned user port

Over achiever's answer - Select and deploy a resource discovery solution. Have the server select a private port dynamically. Have the clients use resource discovery.

The risk that that a server will fail because the port it wants to listen on is not available is real; at least it's happened to me. Another service or a client might get there first.

You can almost totally reduce the risk from a client by avoiding the private ports, which are dynamically handed out to clients.

The risk that from another service is minimal if you use a user port. An unassigned port's risk is only that another service happens to be configured (or dyamically) uses that port. But at least that's probably under your control.

The huge doc with all the port assignments, including User Ports, is here: look for the token Unassigned.

What are these attributes: `aria-labelledby` and `aria-hidden`

Aria is used to improve the user experience of visually impaired users. Visually impaired users navigate though application using screen reader software like JAWS, NVDA,.. While navigating through the application, screen reader software announces content to users. Aria can be used to add content in the code which helps screen reader users understand role, state, label and purpose of the control

Aria does not change anything visually. (Aria is scared of designers too).


aria-hidden attribute is used to hide content for visually impaired users who navigate through application using screen readers (JAWS, NVDA,...).

aria-hidden attribute is used with values true, false.

How To Use:

<i class = "fa fa-books" aria-hidden = "true"></i>

using aria-hidden = "true" on the <i> hides content to screen reader users with no visual change in the application.


aria-label attribute is used to communicate the label to screen reader users. Usually search input field does not have visual label (thanks to designers). aria-label can be used to communicate the label of control to screen reader users

How To Use:

<input type = "edit" aria-label = "search" placeholder = "search">

There is no visual change in application. But screen readers can understand the purpose of control


Both aria-label and aria-labelledby is used to communicate the label. But aria-labelledby can be used to reference any label already present in the page whereas aria-label is used to communicate the label which i not displayed visually

Approach 1:

<span id = "sd"> Search </span>

<input type = "text" aria-labelledby = "sd">

aria-labelledby can also be used to combine two labels for screen reader users

Approach 2:

<span id = "de"> Billing Address </span>

<span id = "sd"> First Name </span>

<input type = "text" aria-labelledby = "de sd">

fatal: 'origin' does not appear to be a git repository

I faced the same problem when I renamed my repository on GitHub. I tried to push at which point I got the error

fatal: 'origin' does not appear to be a git repository
fatal: The remote end hung up unexpectedly

I had to change the URL using

git remote set-url origin ssh://[email protected]/username/newRepoName.git

After this all commands started working fine. You can check the change by using

git remote -v

In my case after successfull change it showed correct renamed repo in URL

[aniket@alok Android]$ git remote -v
origin  ssh://[email protected]/aniket91/TicTacToe.git (fetch)
origin  ssh://[email protected]/aniket91/TicTacToe.git (push)

Hide separator line on one UITableViewCell

In Swift 3, Swift 4 and Swift 5, you can write an extension to UITableViewCell like this:

extension UITableViewCell {
  func separator(hide: Bool) {
    separatorInset.left = hide ? bounds.size.width : 0

Then you can use this as below (when cell is your cell instance):

cell.separator(hide: false) // Shows separator 
cell.separator(hide: true) // Hides separator

It is really better assigning the width of table view cell as left inset instead of assigning it some random number. Because in some screen dimensions, maybe not now but in future your separators can still be visible because that random number may not be enough. Also, in iPad in landscape mode you can't guarantee that your separators will always be invisible.

Embedding a media player in a website using HTML

You can use plenty of things.

  • If you're a standards junkie, you can use the HTML5 <audio> tag:

Here is the official W3C specification for the audio tag.


<audio controls>
 <source src=""
 <!-- The next two lines are only executed if the browser doesn't support MP4 files -->
 <source src=""
         type='audio/ogg; codecs=vorbis'>
 <!-- The next line will only be executed if the browser doesn't support the <audio> tag-->
 <p>Your user agent does not support the HTML5 Audio element.</p>

jsFiddle here.

Note: I'm not sure which are the best ones, as I have never used one (yet).

UPDATE: As mentioned in another answer's comment, you are using XHTML 1.0 Transitional. You might be able to get <audio> to work with some hack.

UPDATE 2: I just remembered another way to do play audio. This will work in XHTML!!! This is fully standards-compliant.

You use this JavaScript:

var aud = document.createElement("iframe");
aud.setAttribute('src', ""); // replace with actual file path
aud.setAttribute('width', '1px');
aud.setAttribute('height', '1px');
aud.setAttribute('scrolling', 'no'); = "0px";

This is my answer to another question.

UPDATE 3: To customise the controls, you can use something like this.

Draw in Canvas by finger, Android

I think it's important to add a thing, if you use the layout inflation that constructor in the drawview is not correct, add these constructors in the class:

public DrawingView(Context c, AttributeSet attrs) {
    super(c, attrs);

public DrawingView(Context c, AttributeSet attrs, int defStyle) {
    super(c, attrs, defStyle);

or the android system fails to inflate the layout file. I hope this could to help.

Sql Server 'Saving changes is not permitted' error ? Prevent saving changes that require table re-creation

To change the Prevent saving changes that require the table re-creation option, follow these steps:

Open SQL Server Management Studio (SSMS). On the Tools menu, click Options.

In the navigation pane of the Options window, click Designers.

Select or clear the Prevent saving changes that require the table re-creation check box, and then click OK.

Note: If you disable this option, you are not warned when you save the table that the changes that you made have changed the metadata structure of the table. In this case, data loss may occur when you save the table.

enter image description here

Can Linux apps be run in Android?

In general, no. Android apps generally run in a sandboxed Java-like virtual machine, so have to be written in Java or some language that compiles to virtual-machine bytecode that use the Android API.

However, the virtual machine does run on top of the underlying Linux OS, and there are ways to call native code. See

So, while it is technically possible to run native Linux programs, as there is a Linux kernel running beneath everything, most users would not be able to install such applications or use them. (If you have root access or are building your own firmware, then you can do whatever you want.)

How to append text to a text file in C++?

I got my code for the answer from a book called "C++ Programming In Easy Steps". The could below should work.

#include <fstream>
#include <string>
#include <iostream>

using namespace std;

int main()
    ofstream writer("filename.file-extension" , ios::app);

    if (!writer)
        cout << "Error Opening File" << endl;
        return -1;

    string info = "insert text here";

    writer << info << endl;
    return 0;   

I hope this helps you.

:: (double colon) operator in Java 8

At runtime they behave a exactly the same.The bytecode may/not be same (For above Incase,it generates the same bytecode(complie above and check javaap -c;))

At runtime they behave a exactly the same.method(math::max);,it generates the same math (complie above and check javap -c;))

Get clicked item and its position in RecyclerView

Based on the link: Why doesn't RecyclerView have onItemClickListener()? and How RecyclerView is different from Listview?, and also @Duncan's general idea, I give my solution here:

  • Define one interface RecyclerViewClickListener for a passing message from the adapter to Activity/Fragment:

      public interface RecyclerViewClickListener {
          public void recyclerViewListClicked(View v, int position);
  • In Activity/Fragment implement the interface, and also pass listener to adapter:

      public void recyclerViewListClicked(View v, int position){... ...}
      //set up adapter and pass clicked listener this
      myAdapter = new MyRecyclerViewAdapter(context, this);
  • In Adapter and ViewHolder:

      public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ItemViewHolder> {
         ... ... 
         private Context context;
         private static RecyclerViewClickListener itemListener;
         public MyRecyclerViewAdapter(Context context, RecyclerViewClickListener itemListener) {
             this.context = context;
             this.itemListener = itemListener;
             ... ...
         //ViewHolder class implement OnClickListener, 
         //set clicklistener to itemView and, 
         //send message back to Activity/Fragment 
         public static class ItemViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
             ... ...
             public ItemViewHolder(View convertView) {
                 ... ...
             public void onClick(View v) {
                 itemListener.recyclerViewListClicked(v, this.getPosition());     

After testing, it works fine.


Since API 22, RecyclerView.ViewHolder.getPosition() is deprecated, so instead with getLayoutPosition().

How can I get the assembly file version

When I want to access the application file version (what is set in Assembly Information -> File version), say to set a label's text to it on form load to display the version, I have just used

versionlabel.Text = "Version " + Application.ProductVersion;

This approach requires a reference to System.Windows.Forms.

Catch multiple exceptions in one line (except block)

If you frequently use a large number of exceptions, you can pre-define a tuple, so you don't have to re-type them many times.

#This example code is a technique I use in a library that connects with websites to gather data

ConnectErrs  = (URLError, SSLError, SocketTimeoutError, BadStatusLine, ConnectionResetError)

def connect(url, data):
    #do connection and return some data

def some_function(var_a, var_b, ...):
    try: o = connect(url, data)
    except ConnectErrs as e:
        #do the recovery stuff
    blah #do normal stuff you would do if no exception occurred


  1. If you, also, need to catch other exceptions than those in the pre-defined tuple, you will need to define another except block.

  2. If you just cannot tolerate a global variable, define it in main() and pass it around where needed...

intelliJ IDEA 13 error: please select Android SDK

I encountered this error after installing Intellij IDEA Ultimate 14.1 and opening an existing Android project I had created using Android Studio. It turns out I just had to add the Android SDK to my list of SDKs and fix the project/module SDK settings. This is how I did it:

Go to File -> Project Structure. Click on the Project tab under Project Settings. Under Project SDK click on New -> Android SDK.

Adding new Android SDK

Now select the existing directory for your Android SDK. In my case it was in this folder:

C:\Users\<windows username>\AppData\Local\Android\android-sdk

Click Ok. A menu pops up asking you to set the Java SDK + Build target. You can either change these or leave it as its defaults and hit Ok. You should now see "Android API XX Platform" in the Project SDK dropdown. Click apply on the bottom. Then go to the Modules tab under Project Settings and click on the folders in the modules listing.

Module List

For each folder go to the dependencies tab and change the Module SDK to the new Android SDK and click apply. Then click Ok to close the Project Structure dialog.

After doing the above, my project was fixed.

List all files and directories in a directory + subdirectories

A littlebit simple and slowly but working!! if you do not give a filepath basicly use the "fixPath" this is just example.... you can search the correct fileType what you want, i did a mistake when i chosen the list name because the "temporaryFileList is the searched file list so carry on that.... and the "errorList" is speaks for itself

 static public void Search(string path, string fileType, List<string> temporaryFileList, List<string> errorList)

        List<string> temporaryDirectories = new List<string>();

        //string fix = @"C:\Users\" + Environment.UserName + @"\";
        string fix = @"C:\";
        string folders = "";
        //Alap útvonal megadása 
        if (path.Length != 0)
        { folders = path; }
        else { path = fix; }

        int j = 0;
        int equals = 0;
        bool end = true;


            equals = j;
            int k = 0;


                int foldersNumber = 
                int fileNumber = Directory.GetFiles(folders).Count();

                if ((foldersNumber != 0 || fileNumber != 0) && equals == j)

                    for (int i = k; k < 


                    if (temporaryDirectories.Count == j)
                        end = false;
                    foreach (string files in Directory.GetFiles(folders))
                        if (files != string.Empty)
                            if (fileType.Length == 0)

                                if (files.Contains(fileType))




                for (int i = j; i < temporaryDirectories.Count;)
                    folders = temporaryDirectories[i];

            catch (Exception ex)

                for (int i = j; i < temporaryDirectories.Count;)
                    folders = temporaryDirectories[i];
        } while (end);

Adding Access-Control-Allow-Origin header response in Laravel 5.3 Passport

The simple answer is to set the Access-Control-Allow-Origin header to localhost or *. Here's how I usually do it:

Create a simple middleware called Cors:

php artisan make:middleware Cors

Add the following code to app/Http/Middleware/Cors.php:

public function handle($request, Closure $next)
    return $next($request)
        ->header('Access-Control-Allow-Origin', '*')
        ->header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');

You can replace the * with localhost or keep it as it is.

Next step is to load the middleware. Add the following line to the $routeMiddleware array in app/Http/Kernel.php.

'cors' => \App\Http\Middleware\Cors::class, 

And the final step is to use the middleware on the routes to which you want to set the access origin headers. Assuming you are talking about the new api routes in laravel 5.3, the place to do it is app/Providers/RouteServiceProvider.php, inside the mapApiRoutes() function (you can remove or comment the previous code of the function):

        'middleware' => ['api', 'cors'],
        'namespace' => $this->namespace,
        'prefix' => 'api',
    ], function ($router) {
         //Add you routes here, for example:

How to achieve function overloading in C?

Leushenko's answer is really cool - solely: the foo example does not compile with GCC, which fails at foo(7), stumbling over the FIRST macro and the actual function call ((_1, __VA_ARGS__), remaining with a surplus comma. Additionally, we are in trouble if we want to provide additional overloads, such as foo(double).

So I decided to elaborate the answer a little further, including to allow a void overload (foo(void) – which caused quite some trouble...).

Idea now is: Define more than one generic in different macros and let select the correct one according to the number of arguments!

Number of arguments is quite easy, based on this answer:

#define foo(...) SELECT(__VA_ARGS__)(__VA_ARGS__)

#define CONCAT(X, Y) CONCAT_(X, Y)
#define CONCAT_(X, Y) X ## Y

That's nice, we resolve to either SELECT_1 or SELECT_2 (or more arguments, if you want/need them), so we simply need appropriate defines:

#define SELECT_0() foo_void
#define SELECT_1(_1) _Generic ((_1),    \
        int: foo_int,                   \
        char: foo_char,                 \
        double: foo_double              \
#define SELECT_2(_1, _2) _Generic((_1), \
        double: _Generic((_2),          \
                int: foo_double_int     \
        )                               \

OK, I added the void overload already – however, this one actually is not covered by the C standard, which does not allow empty variadic arguments, i. e. we then rely on compiler extensions!

At very first, an empty macro call (foo()) still produces a token, but an empty one. So the counting macro actually returns 1 instead of 0 even on empty macro call. We can "easily" eliminate this problem, if we place the comma after __VA_ARGS__ conditionally, depending on the list being empty or not:

#define NARG(...) ARG4_(__VA_ARGS__ COMMA(__VA_ARGS__) 4, 3, 2, 1, 0)

That looked easy, but the COMMA macro is quite a heavy one; fortunately, the topic is already covered in a blog of Jens Gustedt (thanks, Jens). Basic trick is that function macros are not expanded if not followed by parentheses, for further explanations, have a look at Jens' blog... We just have to modify the macros a little to our needs (I'm going to use shorter names and less arguments for brevity).

#define ARGN(...) ARGN_(__VA_ARGS__)
#define ARGN_(_0, _1, _2, _3, N, ...) N
#define HAS_COMMA(...) ARGN(__VA_ARGS__, 1, 1, 1, 0)

#define SET_COMMA(...) ,

#define COMMA(...) SELECT_COMMA             \
(                                           \
        HAS_COMMA(__VA_ARGS__),             \
        HAS_COMMA(__VA_ARGS__ ()),          \
        HAS_COMMA(SET_COMMA __VA_ARGS__),   \
        HAS_COMMA(SET_COMMA __VA_ARGS__ ()) \

#define SELECT_COMMA(_0, _1, _2, _3) SELECT_COMMA_(_0, _1, _2, _3)
#define SELECT_COMMA_(_0, _1, _2, _3) COMMA_ ## _0 ## _1 ## _2 ## _3

#define COMMA_0000 ,
#define COMMA_0001
#define COMMA_0010 ,
// ... (all others with comma)
#define COMMA_1111 ,

And now we are fine...

The complete code in one block:

 * demo.c
 *  Created on: 2017-09-14
 *      Author: sboehler

#include <stdio.h>

void foo_void(void)
void foo_int(int c)
    printf("int: %d\n", c);
void foo_char(char c)
    printf("char: %c\n", c);
void foo_double(double c)
    printf("double: %.2f\n", c);
void foo_double_int(double c, int d)
    printf("double: %.2f, int: %d\n", c, d);

#define foo(...) SELECT(__VA_ARGS__)(__VA_ARGS__)

#define CONCAT(X, Y) CONCAT_(X, Y)
#define CONCAT_(X, Y) X ## Y

#define SELECT_0() foo_void
#define SELECT_1(_1) _Generic ((_1), \
        int: foo_int,                \
        char: foo_char,              \
        double: foo_double           \
#define SELECT_2(_1, _2) _Generic((_1), \
        double: _Generic((_2),          \
                int: foo_double_int     \
        )                               \

#define ARGN(...) ARGN_(__VA_ARGS__)
#define ARGN_(_0, _1, _2, N, ...) N

#define NARG(...) ARGN(__VA_ARGS__ COMMA(__VA_ARGS__) 3, 2, 1, 0)
#define HAS_COMMA(...) ARGN(__VA_ARGS__, 1, 1, 0)

#define SET_COMMA(...) ,

#define COMMA(...) SELECT_COMMA             \
(                                           \
        HAS_COMMA(__VA_ARGS__),             \
        HAS_COMMA(__VA_ARGS__ ()),          \
        HAS_COMMA(SET_COMMA __VA_ARGS__),   \
        HAS_COMMA(SET_COMMA __VA_ARGS__ ()) \

#define SELECT_COMMA(_0, _1, _2, _3) SELECT_COMMA_(_0, _1, _2, _3)
#define SELECT_COMMA_(_0, _1, _2, _3) COMMA_ ## _0 ## _1 ## _2 ## _3

#define COMMA_0000 ,
#define COMMA_0001
#define COMMA_0010 ,
#define COMMA_0011 ,
#define COMMA_0100 ,
#define COMMA_0101 ,
#define COMMA_0110 ,
#define COMMA_0111 ,
#define COMMA_1000 ,
#define COMMA_1001 ,
#define COMMA_1010 ,
#define COMMA_1011 ,
#define COMMA_1100 ,
#define COMMA_1101 ,
#define COMMA_1110 ,
#define COMMA_1111 ,

int main(int argc, char** argv)
    foo(12.10, 7);

    return 0;

Adding system header search path to Xcode

We have two options.

  1. Look at Preferences->Locations->"Custom Paths" in Xcode's preference. A path added here will be a variable which you can add to "Header Search Paths" in project build settings as "$cppheaders", if you saved the custom path with that name.

  2. Set HEADER_SEARCH_PATHS parameter in build settings on project info. I added "${SRCROOT}" here without recursion. This setting works well for most projects.

About 2nd option:

Xcode uses Clang which has GCC compatible command set. GCC has an option -Idir which adds system header searching paths. And this option is accessible via HEADER_SEARCH_PATHS in Xcode project build setting.

However, path string added to this setting should not contain any whitespace characters because the option will be passed to shell command as is.

But, some OS X users (like me) may put their projects on path including whitespace which should be escaped. You can escape it like /Users/my/work/a\ project\ with\ space if you input it manually. You also can escape them with quotes to use environment variable like "${SRCROOT}".

Or just use . to indicate current directory. I saw this trick on Webkit's source code, but I am not sure that current directory will be set to project directory when building it.

The ${SRCROOT} is predefined value by Xcode. This means source directory. You can find more values in Reference document.

PS. Actually you don't have to use braces {}. I get same result with $SRCROOT. If you know the difference, please let me know.

Multiple github accounts on the same computer?

Unlike other answers, where you need to follow few steps to use two different github account from same machine, for me it worked in two steps.

You just need to :

1) generate SSH public and private key pair for each of your account under ~/.ssh location with different names and

2) add the generated public keys to the respective account under Settings >> SSH and GPG keys >> New SSH Key.

To generate the SSH public and private key pairs use following command:

cd ~/.ssh
ssh-keygen -t rsa -C "[email protected]" -f "id_rsa_WORK"
ssh-keygen -t rsa -C "[email protected]" -f "id_rsa_PERSONAL"

As a result of above commands, id_rsa_WORK and files will be created for your work account (ex - and id_rsa_PERSONAL and will be created for your personal account (ex -

Once created, copy the content from each public (*.pub) file and do Step 2 for the each account.

PS : Its not necessary to make an host entry for each git account under ~/.ssh/config file as mentioned in other answers, if hostname of your two accounts are different.

C# DateTime to "YYYYMMDDHHMMSS" format

It is not a big deal. you can simply put like this


Excuse here for I used $ which is for string Interpolation .

"Faceted Project Problem (Java Version Mismatch)" error message

In Spring STS, Right click the project & select "Open Project", This provision do the necessary action on the background & bring the project back to work space.

Thanks & Regards Vengat Maran

How to Pass data from child to parent component Angular

In order to send data from child component create property decorated with output() in child component and in the parent listen to the created event. Emit this event with new values in the payload when ever it needed.

@Output() public eventName:EventEmitter = new EventEmitter();

to emit this event:


git - pulling from specific branch

if you want to pull from a specific branch all you have to do is

git pull 'remote_name' 'branch_name'

NOTE: Make sure you commit your code first.

Number of days in particular month of particular year?

if (month == 4 || month == 6 || month == 9 || month == 11)

daysInMonth = 30;


if (month == 2) 

daysInMonth = (leapYear) ? 29 : 28;


daysInMonth = 31;

Tensorflow: Using Adam optimizer

run init after AdamOptimizer,and without define init before or run init


How can I reset eclipse to default settings?

All the setting are stored in .metadata file in your workspace delete this and you are good to go

Eclipse jump to closing brace

On the Macintosh, place the cursor after either the opening or closing curly brace } and use the keys: Shift + Command + P.

Capitalize first letter. MySQL

You can use a combination of UCASE(), MID() and CONCAT():

SELECT CONCAT(UCASE(MID(name,1,1)),MID(name,2)) AS name FROM names;

After updating Entity Framework model, Visual Studio does not see changes

First Build your Project and if it was successful, right click on the "" file and choose run custom tool. It will fix it.

Again Build your project and point to "" run custom tool. it will update DbSet lists.

Explain the different tiers of 2 tier & 3 tier architecture?

Tiers are nothing but the separation of concerns and in general the presentation layer (the forms or pages that is visible to the user) is separated from the data tier (the class or file interact with the database). This separation is done in order to improve the maintainability, scalability, re-usability, flexibility and performance as well.

A good explanations with demo code of 3-tier and 4-tier architecture can be read at

How do I access ViewBag from JS

if you are using razor engine template then do the following

in your view write :

<script> var myJsVariable = '@ViewBag.MyVariable' </script>

UPDATE: A more appropriate approach is to define a set of configuration on the master layout for example, base url, facebook API Key, Amazon S3 base URL, etc ...```

   var AppConfig = @Html.Raw(Json.Encode(new {
    baseUrl: Url.Content("~"),
    fbApi: "get it from db",
    awsUrl: "get it from db"

And you can use it in your JavaScript code as follow:

  myProduct.fullUrl = AppConfig.awsUrl + myProduct.path;

Finding the max/min value in an array of primitives using Java

    int[] arr = {1, 2, 3};

    List<Integer> list =;
    int max_ = Collections.max(list);
    int i;
    if (max_ > 0) {
        for (i = 1; i < Collections.max(list); i++) {
            if (!list.contains(i)) {
    } else {

What integer hash function are good that accepts an integer hash key?

I have been using splitmix64 (pointed in Thomas Mueller's answer) ever since I found this thread. However, I recently stumbled upon Pelle Evensen's rrxmrrxmsx_0, which yielded tremendously better statistical distribution than the original MurmurHash3 finalizer and its successors (splitmix64 and other mixes). Here is the code snippet in C:

#include <stdint.h>

static inline uint64_t ror64(uint64_t v, int r) {
    return (v >> r) | (v << (64 - r));

uint64_t rrxmrrxmsx_0(uint64_t v) {
    v ^= ror64(v, 25) ^ ror64(v, 50);
    v *= 0xA24BAED4963EE407UL;
    v ^= ror64(v, 24) ^ ror64(v, 49);
    v *= 0x9FB21C651E98DF25UL;
    return v ^ v >> 28;

Pelle also provides an in-depth analysis of the 64-bit mixer used in the final step of MurmurHash3 and the more recent variants.

Remove an item from a dictionary when its key is unknown

I'd build a list of keys that need removing, then remove them. It's simple, efficient and avoids any problem about simultaneously iterating over and mutating the dict.

keys_to_remove = [key for key, value in some_dict.iteritems()
                  if value == value_to_remove]
for key in keys_to_remove:
    del some_dict[key]

How to create exe of a console application

an EXE file is created as long as you build the project. you can usually find this on the debug folder of you project.

C:\Users\username\Documents\Visual Studio 2012\Projects\ProjectName\bin\Debug

Get integer value of the current year in Java

Using Java 8's time API (assuming you are happy to get the year in your system's default time zone), you could use the Year::now method:

int year =;

How do you Programmatically Download a Webpage in Java

Get help from this class it get code and filter some information.

public class MainActivity extends AppCompatActivity {

    EditText url;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate( savedInstanceState );
        setContentView( R.layout.activity_main );

        url = ((EditText)findViewById(;
        DownloadCode obj = new DownloadCode();

        try {
            String des=" ";

            String tag1= "<div class=\"description\">";
            String l = obj.execute( "" ).get();

            url.setText( l );
            url.setText( " " );

            String[] t1 = l.split(tag1);
            String[] t2 = t1[0].split( "</div>" );
            url.setText( t2[0] );

        catch (Exception e)
            Toast.makeText( this,e.toString(),Toast.LENGTH_SHORT ).show();

                                        // input, extrafunctionrunparallel, output
    class DownloadCode extends AsyncTask<String,Void,String>
        protected String doInBackground(String... WebAddress) // string of webAddress separate by ','
            String htmlcontent = " ";
            try {
                URL url = new URL( WebAddress[0] );
                HttpURLConnection c = (HttpURLConnection) url.openConnection();
                InputStream input = c.getInputStream();
                int data;
                InputStreamReader reader = new InputStreamReader( input );

                data =;

                while (data != -1)
                    char content = (char) data;
                    data =;
            catch (Exception e)
                Log.i("Status : ",e.toString());
            return htmlcontent;

`React/RCTBridgeModule.h` file not found

For viewers who got this error after upgrading React Native to 0.40+, you may need to run react-native upgrade on the command line.

JavaScript: Parsing a string Boolean value?

stringjs has a toBoolean() method:

S('true').toBoolean() //true
S('false').toBoolean() //false
S('hello').toBoolean() //false
S(true).toBoolean() //true
S('on').toBoolean() //true
S('yes').toBoolean() //true
S('TRUE').toBoolean() //true
S('TrUe').toBoolean() //true
S('YES').toBoolean() //true
S('ON').toBoolean() //true
S('').toBoolean() //false
S(undefined).toBoolean() //false
S('undefined').toBoolean() //false
S(null).toBoolean() //false
S(false).toBoolean() //false
S({}).toBoolean() //false
S(1).toBoolean() //true
S(-1).toBoolean() //false
S(0).toBoolean() //false

Binding a Button's visibility to a bool value in ViewModel

Generally there are two ways to do it, a converter class or a property in the Viewmodel that essentially converts the value for you.

I tend to use the property approach if it is a one off conversion. If you want to reuse it, use the converter. Below, find an example of the converter:

<ValueConversion(GetType(Boolean), GetType(Visibility))> _
Public Class BoolToVisibilityConverter
    Implements IValueConverter

    Public Function Convert(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.Convert

        If value IsNot Nothing Then
            If value = True Then 
                Return Visibility.Visible
                Return Visibility.Collapsed
            End If
            Return Visibility.Collapsed
        End If
    End Function

    Public Function ConvertBack(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.ConvertBack
        Throw New NotImplementedException
    End Function
End Class

A ViewModel property method would just check the boolean property value, and return a visibility based on that. Be sure to implement INotifyPropertyChanged and call it on both the Boolean and Visibility properties to updated properly.

AngularJS Error: Cross origin requests are only supported for protocol schemes: http, data, chrome-extension, https

  1. Install the http-server, running command npm install http-server -g
  2. Open the terminal in the path where is located the index.html
  3. Run command http-server . -o
  4. Enjoy it!

automating telnet session using bash scripts


expect -c " 
        set timeout 3
        spawn telnet "$adress"
        expect \"Login:\" 
        send \"$user\n\"
        expect \"Password:\"
        send \"$pass\n\"
        expect \"commands.\"
        send \"ping -c $ping_count\n\"
        set timeout 9
        expect \"transmitted\"
        send \"exit\"

count_ping=$(echo "$VAR" | grep packets | cut -c 1)
avg_ms=$(echo "$VAR" | grep round-trip | cut -d '/' -f 4 | cut -d '.' -f 1)

echo "1_____ping___$count_ping|||____$avg_ms"
echo "$VAR"

expected assignment or function call: no-unused-expressions ReactJS

import React from 'react';

class Counter extends React.Component{
    state = {
        count: 0,

    formatCount() {
        const {count} = this.state;
        // use a return statement here, it is a importent,
        return count === 0 ? 'Zero' : count;
    render() {
              <button type="button" className="btn btn-primary">Increment</button>

export default Counter;

Looking for a short & simple example of getters/setters in C#

My explanation would be following. (It's not so short, but it's quite simple.)

Imagine a class with a variable:

class Something
    int weight;
    // and other methods, of course, not shown here

Well, there is a small problem with this class: no one can see the weight. We could make weight public, but then everyone would be able to change the weight at any moment (which is perhaps not what we want). So, well, we can do a function:

class Something
    int weight;
    public int GetWeight() { return weight; }
    // and other methods

This is already better, but now everyone instead of plain something.Weight has to type something.GetWeight(), which is, well, ugly.

With properties, we can do the same, but the code stays clean:

class Something
    public int weight { get; private set; }
    // and other methods

int w = something.weight // works!
something.weight = x; // doesn't even compile

Nice, so with the properties we have finer control over the variable access.

Another problem: okay, we want the outer code to be able to set weight, but we'd like to control its value, and not allow the weights lower than 100. Moreover, there are is some other inner variable density, which depends on weight, so we'd want to recalculate the density as soon as the weight changes.

This is traditionally achieved in the following way:

class Something
    int weight;
    public int SetWeight(int w)
        if (w < 100)
            throw new ArgumentException("weight too small");
        weight = w;
    // and other methods

something.SetWeight(anotherSomething.GetWeight() + 1);

But again, we don't want expose to our clients that setting the weight is a complicated operation, it's semantically nothing but assigning a new weight. So the code with a setter looks the same way, but nicer:

class Something
    private int _w;
    public int Weight
        get { return _w; }
            if (value < 100)
                throw new ArgumentException("weight too small");
            _w = value;
    // and other methods

something.Weight = otherSomething.Weight + 1; // much cleaner, right?

So, no doubt, properties are "just" a syntactic sugar. But it makes the client's code be better. Interestingly, the need for property-like things arises very often, you can check how often you find the functions like GetXXX() and SetXXX() in the other languages.

How to force page refreshes or reloads in jQuery?

Or better

window.location.assign("relative or absolute address");

that tends to work best across all browsers and mobile

how to get last insert id after insert query in codeigniter active record

A transaction isn't needed here, this should suffice:

function add_post($post_data) {
    return $this->db->insert_id();

Using a PagedList with a ViewModel ASP.Net MVC

I modified the code as follow:


using System.Collections.Generic;
using ContosoUniversity.Models;

namespace ContosoUniversity.ViewModels
    public class InstructorIndexData
     public PagedList.IPagedList<Instructor> Instructors { get; set; }
     public PagedList.IPagedList<Course> Courses { get; set; }
     public PagedList.IPagedList<Enrollment> Enrollments { get; set; }


public ActionResult Index(int? id, int? courseID,int? InstructorPage,int? CoursePage,int? EnrollmentPage)
 int instructPageNumber = (InstructorPage?? 1);
 int CoursePageNumber = (CoursePage?? 1);
 int EnrollmentPageNumber = (EnrollmentPage?? 1);
 var viewModel = new InstructorIndexData();
 viewModel.Instructors = db.Instructors
    .Include(i => i.OfficeAssignment)
    .Include(i => i.Courses.Select(c => c.Department))
    .OrderBy(i => i.LastName).ToPagedList(instructPageNumber,5);

 if (id != null)
    ViewBag.InstructorID = id.Value;
    viewModel.Courses = viewModel.Instructors.Where(
        i => i.ID == id.Value).Single().Courses.ToPagedList(CoursePageNumber,5);

 if (courseID != null)
    ViewBag.CourseID = courseID.Value;
    viewModel.Enrollments = viewModel.Courses.Where(
        x => x.CourseID == courseID).Single().Enrollments.ToPagedList(EnrollmentPageNumber,5);

 return View(viewModel);


   Page @(Model.Instructors.PageCount < Model.Instructors.PageNumber ? 0 : Model.Instructors.PageNumber) of @Model.Instructors.PageCount

   @Html.PagedListPager(Model.Instructors, page => Url.Action("Index", new {InstructorPage=page}))


I hope this would help you!!

jwt check if token expired

You should use jwt.verify it will check if the token is expired. jwt.decode should not be used if the source is not trusted as it doesn't check if the token is valid.

How do I change data-type of pandas data frame to string with a defined format?

If you could reload this, you might be able to use dtypes argument.

pd.read_csv(..., dtype={'COL_NAME':'str'})

substring index range

Like you I didn't find it came naturally. I normally still have to remind myself that

  • the length of the returned string is

    lastIndex - firstIndex

  • that you can use the length of the string as the lastIndex even though there is no character there and trying to reference it would throw an Exception


"University".substring(6, 10)

returns the 4-character string "sity" even though there is no character at position 10.

Avoiding "resource is out of sync with the filesystem"

A little hint. The message often appears during rename operation. The quick workaround for me is pressing Ctrl-Y (redo shortcut) after message confirmation. It works only if the renaming affects a single file.

Simple way to get element by id within a div tag?

var x = document.getElementById("parent").querySelector("#child");
// don't forget a #


var x = document.querySelector("#parent").querySelector("#child");


var x = document.querySelector("#parent #child");


var x = document.querySelector("#parent");
var y = x.querySelector("#child");


var x = document.querySelector("#div1").querySelector("#edit2");

How to use su command over adb shell?

On my Linux I see an error with

adb shell "su -c '[your command goes here]'"

su: invalid uid/gid '-c'

The solution is on Linux

adb shell su 0 '[your command goes here]'

Using filesystem in node.js with async / await

Native support for async await fs functions since Node 11

Since Node.JS 11.0.0 (stable), and version 10.0.0 (experimental), you have access to file system methods that are already promisify'd and you can use them with try catch exception handling rather than checking if the callback's returned value contains an error.

The API is very clean and elegant! Simply use .promises member of fs object:

import fs from 'fs';
const fsPromises = fs.promises;

async function listDir() {
  try {
    return fsPromises.readdir('path/to/dir');
  } catch (err) {
    console.error('Error occured while reading directory!', err);


maxReceivedMessageSize and maxBufferSize in app.config

The currently accepted answer is incorrect. It is NOT required to set maxBufferSize and maxReceivedMessageSize on the client and the server binding. It depends!

If your request is too large (i.e., method parameters of the service operation are memory intensive) set the properties on the server-side, if the response is too large (i.e., the method return value of the service operation is memory intensive) set the values on the client-side.

For the difference between maxBufferSize and maxReceivedMessageSize see MaxBufferSize property?.

Why do I get a SyntaxError for a Unicode escape in my file path?

C:\\Users\\expoperialed\\Desktop\\Python This syntax worked for me.

Create whole path automatically when writing to a new file

Use FileUtils to handle all these headaches.

Edit: For example, use below code to write to a file, this method will 'checking and creating the parent directory if it does not exist'.

openOutputStream(File file [, boolean append]) 

How do you add UI inside cells in a google spreadsheet using app script?

Status 2018:

There seems to be no way to place buttons (drawings, images) within cells in a way that would allow them to be linked to Apps Script functions.

This being said, there are some things that you can indeed do:

You can...

You can place images within cells using IMAGE(URL), but they cannot be linked to Apps Script functions.

You can place images within cells and link them to URLs using:
=HYPERLINK(""; IMAGE(""; 1))

You can create drawings as described in the answer of @Eduardo and they can be linked to Apps Script functions, but they will be stand-alone items that float freely "above" the spreadsheet and cannot be positioned in cells. They cannot be copied from cell to cell and they do not have a row or col position that the script function could read.

A simple jQuery form validation script

you can use jquery validator for that but you need to add jquery.validate.js and jquery.form.js file for that. after including validator file define your validation something like this.

<script type="text/javascript">
    rules :{
        "data[User][name]" : {
            required : true
    messages :{
        "data[User][name]" : {
            required : 'Enter username'

You can see required : true same there is many more property like for email you can define email : true for number number : true

Conditionally change img src based on model data

Another way ..

<img ng-src="{{!video.playing ? 'img/icons/play-rounded-button-outline.svg' : 'img/icons/pause-thin-rounded-button.svg'}}" />

How to check if a key exists in Json Object and get its value


if (containerObject.has("video")) {
    //get value of video

Counting array elements in Python



if you want to be oopy; "len(myArray)" is a lot easier to type! :)

Connecting to Postgresql in a docker container from outside

For some reason 5432 port seems protected. I changed my port config from 5432:5432to 5416:5432 and the following command worked to connect to your postgres database from outside its docker container:

psql -h localhost -p 5416 -U <my-user> -d <my-database>

How do you set the max number of characters for an EditText in Android?

In XML you can add this line to the EditText View where 140 is the maximum number of characters:


Passing an array/list into a Python function

You can pass lists just like other types:

l = [1,2,3]

def stuff(a):
   for x in a:
      print a


This prints the list l. Keep in mind lists are passed as references not as a deep copy.

Loop through all the rows of a temp table and call a stored procedure for each row

Try returning the dataset from your stored procedure to your datatable in C# or VB.Net. Then the large amount of data in your datatable can be copied to your destination table using a Bulk Copy. I have used BulkCopy for loading large datatables with thousands of rows, into Sql tables with great success in terms of performance.

You may want to experiment with BulkCopy in your C# or VB.Net code.

Create a mocked list by mockito

When dealing with mocking lists and iterating them, I always use something like:

private List<Object> parts = new ArrayList<>();

How to generate UL Li list from string array using jquery?

It's possible without jQuery too! :)

let countries = ['United States', 'Canada', 'Argentina', 'Armenia', 'Aruba'];_x000D_
// The <ul> that we will add <li> elements to:_x000D_
let myList = document.querySelector('ul.mylist');_x000D_
// Loop over the Array of country names:_x000D_
countries.forEach(function(value, index, array) {_x000D_
  // Create an <li> element:_x000D_
  let li = document.createElement('li');_x000D_
  // Give it the desired classes & attributes:_x000D_
  li.setAttribute('role', 'menuitem');_x000D_
  // Now create an <a> element:_x000D_
  let a = document.createElement('a');_x000D_
  // Give it the desired classes & attributes:_x000D_
  a.tabIndex = -1;_x000D_
  a.innerText = value; //  <--- the country name from our Array_x000D_
  a.href = "#"_x000D_
  // Now add the <a> to the <li>, and add the <li> to the <ul>_x000D_
<ul class="mylist"></ul>

How do I implement a callback in PHP?

For those who don't care about breaking compatibility with PHP < 5.4, I'd suggest using type hinting to make a cleaner implementation.

function call_with_hello_and_append_world( callable $callback )
     // No need to check $closure because of the type hint
     return $callback( "hello" )."world";

function append_space( $string )
     return $string." ";

$output1 = call_with_hello_and_append_world( function( $string ) { return $string." "; } );
var_dump( $output1 ); // string(11) "hello world"

$output2 = call_with_hello_and_append_world( "append_space" );
var_dump( $output2 ); // string(11) "hello world"

$old_lambda = create_function( '$string', 'return $string." ";' );
$output3 = call_with_hello_and_append_world( $old_lambda );
var_dump( $output3 ); // string(11) "hello world"

asp:TextBox ReadOnly=true or Enabled=false?

Readonly will allow the user to copy text from it. Disabled will not.

How to view AndroidManifest.xml from APK file?

There is an online tool that lets you upload an APK It decompiles it and finally lets you to download a zip with all sources, manifest XML file and so on decompiled, all of that without having to install any program on your computer:

Also if you wish just to check on some params you can, by their UI

Start script missing error when running npm start

Try with these steps :

npm rm -g create-react-app

npm install -g create-react-app

npx create-react-app my-app

Definitely this works!!

Java: Reading integers from a file into an array

You must have an empty line in your file.

You may want to wrap your parseInt calls in a "try" block:

try {
  tall[i++] = Integer.parseInt(s);
catch (NumberFormatException ex) {

Or simply check for empty strings before parsing:

if (s.length() == 0) 

Note that by initializing your index variable i inside the loop, it is always 0. You should move the declaration before the while loop. (Or make it part of a for loop.)

How to convert integer to char in C?

 void main ()
    int temp,integer,count=0,i,cnd=0;
    char ascii[10]={0};
    printf("enter a number");

     /*CONVERTING 2's complement value to normal value*/    

    printf("\n count =%d ascii=%s ",count,ascii);


Source file 'Properties\AssemblyInfo.cs' could not be found

This solved my problem. You should select Properties, Right-Click, Source Control and Get Specific Version.

How to tell if node.js is installed or not

Please try this command node --version or node -v, either of which should return something like v4.4.5.

How to get the absolute coordinates of a view

Just in addition to the above answers, for the question where and when you should call getLocationOnScreen?

For any information that is related to the view, will be available only after the view has been laid out(created) on the screen. So to get the location put your code inside which is called after view has been laid out, like this: Runnable() {
            public void run() {

               // This code will run when view created and rendered on screen

               // So as the answer to this question, you can put the code here
               int[] location = new int[2];
               int x = location[0];
               int y = location[1];

JavaScript - get the first day of the week from current date

setDate() has issues with month boundaries that are noted in comments above. A clean workaround is to find the date difference using epoch timestamps rather than the (surprisingly counterintuitive) methods on the Date object. I.e.

function getPreviousMonday(fromDate) {
    var dayMillisecs = 24 * 60 * 60 * 1000;

    // Get Date object truncated to date.
    var d = new Date(new Date(fromDate || Date()).toISOString().slice(0, 10));

    // If today is Sunday (day 0) subtract an extra 7 days.
    var dayDiff = d.getDay() === 0 ? 7 : 0;

    // Get date diff in millisecs to avoid setDate() bugs with month boundaries.
    var mondayMillisecs = d.getTime() - (d.getDay() + dayDiff) * dayMillisecs;

    // Return date as YYYY-MM-DD string.
    return new Date(mondayMillisecs).toISOString().slice(0, 10);

How to find MySQL process list and to kill those processes?

select GROUP_CONCAT(stat SEPARATOR ' ') from (select concat('KILL ',id,';') as stat from information_schema.processlist) as stats;

Then copy and paste the result back into the terminal. Something like:

KILL 2871; KILL 2879; KILL 2874; KILL 2872; KILL 2866;

What does yield mean in PHP?

An interesting aspect, which worth to be discussed here, is yielding by reference. Every time we need to change a parameter such that it is reflected outside of the function, we have to pass this parameter by reference. To apply this to generators, we simply prepend an ampersand & to the name of the generator and to the variable used in the iteration:

 * Yields by reference.
 * @param int $from
function &counter($from) {
    while ($from > 0) {
        yield $from;

foreach (counter(100) as &$value) {
    echo $value . '...';

// Output: 99...98...97...96...95...

The above example shows how changing the iterated values within the foreach loop changes the $from variable within the generator. This is because $from is yielded by reference due to the ampersand before the generator name. Because of that, the $value variable within the foreach loop is a reference to the $from variable within the generator function.

Java - Best way to print 2D array?

You can print in simple way.

Use below to print 2D array

int[][] array = new int[rows][columns];

Use below to print 1D array

int[] array = new int[size];

Remove pandas rows with duplicate indices

If anyone like me likes chainable data manipulation using the pandas dot notation (like piping), then the following may be useful:

df3 = df3.query('~index.duplicated()')

This enables chaining statements like this:


What are the differences between the different saving methods in Hibernate?

Be aware that if you call an update on an detached object, there will always be an update done in the database whether you changed the object or not. If it is not what you want you should use Session.lock() with LockMode.None.

You should call update only if the object was changed outside the scope of your current session (when in detached mode).

Java Look and Feel (L&F)

You can also use JTattoo (, it has a couple of cool themes that can be used.

Just download the jar and import it into your classpath, or add it as a maven dependency:


Here is a list of some of the cool themes they have available:

  • com.jtattoo.plaf.acryl.AcrylLookAndFeel
  • com.jtattoo.plaf.aluminium.AluminiumLookAndFeel
  • com.jtattoo.plaf.bernstein.BernsteinLookAndFeel
  • com.jtattoo.plaf.graphite.GraphiteLookAndFeel
  • com.jtattoo.plaf.hifi.HiFiLookAndFeel
  • com.jtattoo.plaf.luna.LunaLookAndFeel
  • com.jtattoo.plaf.mcwin.McWinLookAndFeel
  • com.jtattoo.plaf.noire.NoireLookAndFeel
  • com.jtattoo.plaf.texture.TextureLookAndFeel
  • com.jtattoo.plaf.custom.flx.FLXLookAndFeel


Install / upgrade gradle on Mac OS X

Another alternative is to use sdkman. An advantage of sdkman over brew is that many versions of gradle are supported. (brew only supports the latest version and 2.14.) To install sdkman execute:

curl -s "" | bash

Then follow the instructions. Go here for more installation information. Once sdkman is installed use the command:

sdk install gradle

Or to install a specific version:

sdk install gradle 2.2

Or use to use a specific installed version:

sdk use gradle 2.2

To see which versions are installed and available:

sdk list gradle

For more information go here.

How to screenshot website in JavaScript client-side / how Google did it? (no need to access HDD)

"Using HTML5/Canvas/JavaScript to take screenshots" answers your problem.

You can use JavaScript/Canvas to do the job but it is still experimental.

regex for zip-code

  • ^ = Start of the string.
  • \d{5} = Match 5 digits (for condition 1, 2, 3)
  • (?:…) = Grouping
  • [-\s] = Match a space (for condition 3) or a hyphen (for condition 2)
  • \d{4} = Match 4 digits (for condition 2, 3)
  • …? = The pattern before it is optional (for condition 1)
  • $ = End of the string.

How to preserve insertion order in HashMap?

HashMap is unordered per the second line of the documentation:

This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.

Perhaps you can do as aix suggests and use a LinkedHashMap, or another ordered collection. This link can help you find the most appropriate collection to use.

Swift 3: Display Image from URL

let url = URL(string: "")
let data = try? Data(contentsOf: url)

if let imageData = data {
    let image = UIImage(data: imageData)

Error in Python script "Expected 2D array, got 1D array instead:"?

I faced the same issue except that the data type of the instance I wanted to predict was a panda.Series object.

Well I just needed to predict one input instance. I took it from a slice of my data.

df = pd.DataFrame(list(BiogasPlant.objects.all()))
test = df.iloc[-1:]       # sliced it here

In this case, you'll need to convert it into a 1-D array and then reshape it.

 test2d = test.values.reshape(1,-1)

From the docs, values will convert Series into a numpy array.

Ignore parent padding

If you have a parent container with vertical padding and you want something (e.g. an image) inside that container to ignore its vertical padding you can set a negative, but equal, margin for both 'top' and 'bottom':

margin-top: -100px;
margin-bottom: -100px;

The actual value doesn't appear to matter much. Haven't tried this for horizontal paddings.

Does Python have “private” variables in classes?

As correctly mentioned by many of the comments above, let's not forget the main goal of Access Modifiers: To help users of code understand what is supposed to change and what is supposed not to. When you see a private field you don't mess around with it. So it's mostly syntactic sugar which is easily achieved in Python by the _ and __.

Regular expression that doesn't contain certain string

I the following code I had to replace add a GET-parameter to all references to JS-files EXCEPT one.

<link rel="stylesheet" type="text/css" href="/login/css/ABC.css" />
<script type="text/javascript" language="javascript" src="/localization/DEF.js"></script>
<script type="text/javascript" language="javascript" src="/login/jslib/GHI.js"></script>
<script type="text/javascript" language="javascript" src="/login/jslib/md5.js"></script>
sendRequest('/application/srvc/EXCEPTION.js', handleChallengeResponse, null);
sendRequest('/application/srvc/EXCEPTION.js",handleChallengeResponse, null);

This is the Matcher used:


What that does is look for all occurences of ".js" and if they are preceeded by the "EXCEPTION" string, discard that result from the result array. That's called negative lookbehind. Since I spent a day on finding out how to do this I thought I should share.

Ignore files that have already been committed to a Git repository

another problem I had was I placed an inline comment.

tmp/*   # ignore my tmp folder (this doesn't work)

this works

# ignore my tmp folder

PHP array printing using a loop

I also find that using <pre></pre> tags around your var_dump or print_r results in a much more readable dump.

Get last 30 day records from today date in SQL Server

I dont know why all these complicated answers are on here but this is what I would do

where pdate >= CURRENT_TIMESTAMP -30


How do we determine the number of days for a given month in python

Alternative solution:

>>> from datetime import date
>>> (date(2012, 3, 1) - date(2012, 2, 1)).days

Plotting with C#

NPlot is a pretty good simple open source 2D plotting API. Unfortunately, the web site is down. I don't know if this is just temporary or not. I haven't heard of any bad news. It may come back up.

Here is an article describing it:

The previous article uses VB.NET, but obviously this will work with C#.

Again, not sure why nplot's site is not currently working but it is a somewhat popular plotting API that I've used in the past. I post it for your information and in case of the likely event nplot will be back up soon. :)


Thanks to a Hosam Aly, it looks like the SourceForge project can still be accessed here:

How to show SVG file on React Native?

import React from 'react'
import SvgUri from 'react-native-svg-uri';

export default function Splash() {
  return (
    <View style={styles.container}>
      {/* provided the svg file is stored locally */}
      {/* if the svg is online */}
        source={{ uri: '' }}

      <Text style={styles.logoText}>

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center'
  logoText: {
    fontSize: 50

Remove an item from an IEnumerable<T> collection

You can't. IEnumerable<T> can only be iterated.

In your second example, you can remove from original collection by iterating over a copy of it

foreach(var u in users.ToArray()) // ToArray creates a copy
   if(u.userId != 1233)

jQuery DataTables: control table width

Well, I'm not familiar with that plugin, but could you reset the style after adding the datatable? Something like


after the .dataTable call?

The endpoint reference (EPR) for the Operation not found is

It seems don't find wsdl file..
I've solved adding wsdlLocation parameter at javax.jws.WebService annotation

How to check if an element exists in the xml using xpath?



How to install node.js as windows service?

I'm not addressing the question directly, but providing an alternative that might also meet your requirement in a more node.js fashion way.

Functionally the requirements are:

  1. Have the logic (app) running in the background
  2. Be able to start/stop the logic
  3. Automatically start the logic when system boots up

These requirements can be satisfied by using a process manager (PM) and making the process manager start on system startup. Two good PMs that are Windows-friendly are:

To make the PM start automatically, the most simple way is to create a scheduled task with a "At Startup" trigger:

enter image description here

Detect if page has finished loading

there are two ways to do this in jquery depending what you are looking for..

using jquery you can do

  • //this will wait for the text assets to be loaded before calling this (the dom.. css.. js)

  • //this will wait for all the images and text assets to finish loading before executing


Get a random item from a JavaScript array

Use underscore (or loDash :)):

var randomArray = [
   '#cc0000','#00cc00', '#0000cc'

// use _.sample
var randomElement = _.sample(randomArray);

// manually use _.random
var randomElement = randomArray[_.random(randomArray.length-1)];

Or to shuffle an entire array:

// use underscore's shuffle function
var firstRandomElement = _.shuffle(randomArray)[0];

Which command in VBA can count the number of characters in a string variable?

Do you mean counting the number of characters in a string? That's very simple

Dim strWord As String
Dim lngNumberOfCharacters as Long

strWord = "habit"
lngNumberOfCharacters = Len(strWord)
Debug.Print lngNumberOfCharacters

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

Up to and including txt you would need to change your regex like so:


How to sort a HashSet?

You can use guava library for the same

Set<String> sortedSet = FluentIterable.from(myHashSet).toSortedSet(new Comparator<String>() {
    public int compare(String s1, String s2) {
        // descending order of relevance
        //required code

Which is fastest? SELECT SQL_CALC_FOUND_ROWS FROM `table`, or SELECT COUNT(*)

MySQL has started deprecating SQL_CALC_FOUND_ROWS functionality with version 8.0.17 onwards.

So, it is always preferred to consider executing your query with LIMIT, and then a second query with COUNT(*) and without LIMIT to determine whether there are additional rows.

From docs:

The SQL_CALC_FOUND_ROWS query modifier and accompanying FOUND_ROWS() function are deprecated as of MySQL 8.0.17 and will be removed in a future MySQL version.

COUNT(*) is subject to certain optimizations. SQL_CALC_FOUND_ROWS causes some optimizations to be disabled.

Use these queries instead:

SELECT * FROM tbl_name WHERE id > 100 LIMIT 10;

Also, SQL_CALC_FOUND_ROWS has been observed to having more issues generally, as explained in the MySQL WL# 12615 :

SQL_CALC_FOUND_ROWS has a number of problems. First of all, it's slow. Frequently, it would be cheaper to run the query with LIMIT and then a separate SELECT COUNT() for the same query, since COUNT() can make use of optimizations that can't be done when searching for the entire result set (e.g. filesort can be skipped for COUNT(*), whereas with CALC_FOUND_ROWS, we must disable some filesort optimizations to guarantee the right result)

More importantly, it has very unclear semantics in a number of situations. In particular, when a query has multiple query blocks (e.g. with UNION), there's simply no way to calculate the number of “would-have-been” rows at the same time as producing a valid query. As the iterator executor is progressing towards these kinds of queries, it is genuinely difficult to try to retain the same semantics. Furthermore, if there are multiple LIMITs in the query (e.g. for derived tables), it's not necessarily clear to which of them SQL_CALC_FOUND_ROWS should refer to. Thus, such nontrivial queries will necessarily get different semantics in the iterator executor compared to what they had before.

Finally, most of the use cases where SQL_CALC_FOUND_ROWS would seem useful should simply be solved by other mechanisms than LIMIT/OFFSET. E.g., a phone book should be paginated by letter (both in terms of UX and in terms of index use), not by record number. Discussions are increasingly infinite-scroll ordered by date (again allowing index use), not by paginated by post number. And so on.

What is the use of the square brackets [] in sql statements?

The brackets are required if you use keywords or special chars in the column names or identifiers. You could name a column [First Name] (with a space)--but then you'd need to use brackets every time you referred to that column.

The newer tools add them everywhere just in case or for consistency.

CSS selector for a checked radio button's label

try the + symbol: It is Adjacent sibling combinator. It combines two sequences of simple selectors having the same parent and the second one must come IMMEDIATELY after the first.

As such:

input[type="radio"]:checked+label{ font-weight: bold; } 
 //a label that immediately follows an input of type radio that is checked 

works very nicely for the following markup:

<input id="rad1" type="radio" name="rad"/><label for="rad1">Radio 1</label>
<input id="rad2" type="radio" name="rad"/><label for="rad2">Radio 2</label>

... and it will work for any structure, with or without divs etc as long as the label follows the radio input.


input[type="radio"]:checked+label { font-weight: bold; }
<input id="rad1" type="radio" name="rad"/><label for="rad1">Radio 1</label>_x000D_
<input id="rad2" type="radio" name="rad"/><label for="rad2">Radio 2</label>

How do I check if a Key is pressed on C++

There is no portable function that allows to check if a key is hit and continue if not. This is always system dependent.

Solution for linux and other posix compliant systems:

Here, for Morgan Mattews's code provide kbhit() functionality in a way compatible with any POSIX compliant system. He uses the trick of desactivating buffering at termios level.

Solution for windows:

For windows, Microsoft offers _kbhit()