Programs & Examples On #Isolation

Spring @Transactional - isolation, propagation

You can use like this:

@Transactional(propagation = Propagation.REQUIRES_NEW)
public EventMessage<ModificaOperativitaRapporto> activate(EventMessage<ModificaOperativitaRapporto> eventMessage) {
//here some transaction related code

You can use this thing also:

public interface TransactionStatus extends SavepointManager {
    boolean isNewTransaction();
    boolean hasSavepoint();
    void setRollbackOnly();
    boolean isRollbackOnly();
    void flush();
    boolean isCompleted();

How to select the first element with a specific attribute using XPath

/bookstore/book[@location='US'][1] works only with simple structure.

Add a bit more structure and things break.


  <book location="US">A1</book>
  <book location="FIN">A2</book>
  <book location="FIN">B1</book>
  <book location="US">B2</book>

/bookstore/category/book[@location='US'][1] yields

<book location="US">A1</book>
<book location="US">B2</book>

not "the first node that matches a more complicated condition". /bookstore/category/book[@location='US'][2] returns nothing.

With parentheses you can get the result the original question was for:

(/bookstore/category/book[@location='US'])[1] gives

<book location="US">A1</book>

and (/bookstore/category/book[@location='US'])[2] works as expected.

How can I view the Git history in Visual Studio Code?

GitLens has a nice Git history browser. Install GitLens from the extensions marketplace, and then run "Show GitLens Explorer" from the command palette.

Difference between static class and singleton pattern?

The Singleton pattern has several advantages over static classes. First, a singleton can extend classes and implement interfaces, while a static class cannot (it can extend classes, but it does not inherit their instance members). A singleton can be initialized lazily or asynchronously while a static class is generally initialized when it is first loaded, leading to potential class loader issues. However the most important advantage, though, is that singletons can be handled polymorphically without forcing their users to assume that there is only one instance.

Keep only first n characters in a string?

var myString = "Hello, how are you?";

R - test if first occurrence of string1 is followed by string2

> grepl("^[^_]+_1",s)
> grepl("^[^_]+_2",s)
[1] TRUE

basically, look for everything at the beginning except _, and then the _2.

+1 to @Ananda_Mahto for suggesting grepl instead of grep.

.append(), prepend(), .after() and .before()

This image displayed below gives a clear understanding and shows the exact difference between .append(), .prepend(), .after() and .before()

jQuery infographic

You can see from the image that .append() and .prepend() adds the new elements as child elements (brown colored) to the target.

And .after() and .before() adds the new elements as sibling elements (black colored) to the target.

Here is a DEMO for better understanding.

EDIT: the flipped versions of those functions:

jQuery insertion infographic, plus flipped versions of the functions

Using this code:

var $target = $('.target');

$target.append('<div class="child">1. append</div>');
$target.prepend('<div class="child">2. prepend</div>');
$target.before('<div class="sibling">3. before</div>');
$target.after('<div class="sibling">4. after</div>');

$('<div class="child flipped">or appendTo</div>').appendTo($target);
$('<div class="child flipped">or prependTo</div>').prependTo($target);
$('<div class="sibling flipped">or insertBefore</div>').insertBefore($target);
$('<div class="sibling flipped">or insertAfter</div>').insertAfter($target);

on this target:

<div class="target">
    This is the target div to which new elements are associated using jQuery

So although these functions flip the parameter order, each creates the same element nesting:

var $div = $('<div>').append($('<img>'));
var $img = $('<img>').appendTo($('<div>'))

...but they return a different element. This matters for method chaining.

Equivalent to 'app.config' for a library (DLL)

assemblies don't have their own app.config file. They use the app.config file of the application that is using them. So if your assembly is expecting certain things in the config file, then just make sure your application's config file has those entries in there.

If your assembly is being used by multiple applications then each of those applications will need to have those entries in their app.config file.

What I would recommended you do is define properties on the classes in your assembly for those values for example

private string ExternalServicesUrl
    string externalServiceUrl = ConfigurationManager.AppSettings["ExternalServicesUrl"];
    if (String.IsNullOrEmpty(externalServiceUrl))
      throw new MissingConfigFileAppSettings("The Config file is missing the appSettings entry for: ExternalServicesUrl");
    return externalServiceUrl;

Here, the property ExternalServicesUrl get's its value from the application's config file. If any application using this assembly is missing that setting in the config file you'll get an exception o it's clear that something went missing.

MissingConfigFileAppSettings is a custom Exception. You may want to throw a different exception.

Of course a better design would be for the method of those classes to be provided those values as parameters rather than relying on config file setting. That way the applications using these classes can decide from where and how they provide these values.

Count occurrences of a char in a string using Bash

Building on everyone's great answers and comments, this is the shortest and sweetest version:

grep -o "$needle" <<< "$haystack" | wc -l

Can I set text box to readonly when using Html.TextBoxFor?

This work for me...

@Html.TextBoxFor(model => model.RIF, new { value = @Model.RIF, @readonly = "readonly" })

Force an Android activity to always use landscape mode

That's it!! Long waiting for this fix.

I've an old Android issue about double-start an activity that required (programmatically) landscape mode: setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE)

Now Android make Landscape mode on start.

Android: keeping a background service alive (preventing process death)

I had a similar issue. On some devices after a while Android kills my service and even startForeground() does not help. And my customer does not like this issue. My solution is to use AlarmManager class to make sure that the service is running when it's necessary. I use AlarmManager to create a kind of watchdog timer. It checks from time to time if the service should be running and restart it. Also I use SharedPreferences to keep the flag whether the service should be running.

Creating/dismissing my watchdog timer:

void setServiceWatchdogTimer(boolean set, int timeout)
    Intent intent;
    PendingIntent alarmIntent;
    intent = new Intent(); // forms and creates appropriate Intent and pass it to AlarmManager
    intent.setClass(this, WatchDogServiceReceiver.class);
    alarmIntent = PendingIntent.getBroadcast(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager am=(AlarmManager)getSystemService(Context.ALARM_SERVICE);
        am.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + timeout, alarmIntent);

Receiving and processing the intent from the watchdog timer:

/** this class processes the intent and
 *  checks whether the service should be running
public static class WatchDogServiceReceiver extends BroadcastReceiver
    public void onReceive(Context context, Intent intent)

            // check your flag and 
            // restart your service if it's necessary
            setServiceWatchdogTimer(true, 60000*5); // restart the watchdogtimer

Indeed I use WakefulBroadcastReceiver instead of BroadcastReceiver. I gave you the code with BroadcastReceiver just to simplify it.

Convert date to another timezone in JavaScript

Just set your desire country timezone and You can easily show in html it update using SetInteval() function after every one minut. function formatAMPM() manage 12 hour format and AM/PM time display.

        var pakTime = new Date().toLocaleString("en-US", {timeZone: "Asia/Karachi"});
        pakTime = new Date(pakTime);

        var libyaTime = new Date().toLocaleString("en-US", {timeZone: "Africa/Tripoli"});
        libyaTime = new Date(libyaTime);

         document.getElementById("pak").innerHTML = "PAK  "+formatAMPM(pakTime);
         document.getElementById("ly").innerHTML = "LY   " +formatAMPM(libyaTime);

        setInterval(function(today) {
            var pakTime = new Date().toLocaleString("en-US", {timeZone: "Asia/Karachi"});
            pakTime = new Date(pakTime);

            var libyaTime = new Date().toLocaleString("en-US", {timeZone: "Africa/Tripoli"});
            libyaTime = new Date(libyaTime);

           document.getElementById("pak").innerHTML = "PAK  "+formatAMPM(pakTime);
           document.getElementById("ly").innerHTML = "LY  " +formatAMPM(libyaTime);


         function formatAMPM(date) {
            var hours = date.getHours();
            var minutes = date.getMinutes();
            var ampm = hours >= 12 ? 'pm' : 'am';
            hours = hours % 12;
            hours = hours ? hours : 12; // the hour '0' should be '12'
            minutes = minutes < 10 ? '0'+minutes : minutes;
            var strTime = hours + ':' + minutes + ' ' + ampm;
            return strTime;


How to reset selected file with input tag file type in Angular 2?

You can use ViewChild to access the input in your component. First, you need to add #someValue to your input so you can read it in the component:

<input #myInput type="file" placeholder="File Name" name="filename" (change)="onChange($event)">

Then in your component you need to import ViewChild from @angular/core:

import { ViewChild } from '@angular/core';

Then you use ViewChild to access the input from template:

myInputVariable: ElementRef;

Now you can use myInputVariable to reset the selected file because it's a reference to input with #myInput, for example create method reset() that will be called on click event of your button:

reset() {
    this.myInputVariable.nativeElement.value = "";

First console.log will print the file you selected, second console.log will print an empty array because this.myInputVariable.nativeElement.value = ""; deletes selected file(s) from the input. We have to use this.myInputVariable.nativeElement.value = ""; to reset the value of the input because input's FileList attribute is readonly, so it is impossible to just remove item from array. Here's working Plunker.

Difference between Constructor and ngOnInit

Constructor is the first, and it happens sometimes when @input data is null! so we use Constructor for declare services and ngOnInit happens after. Exsample for contrutor:

 constructor(translate: TranslateService, private oauthService: OAuthService) {

Exsample for onInit:

ngOnInit() {
    this.items = [
      { label: 'A', icon: 'fa fa-home', routerLink: ['/'] },
      { label: 'B', icon: 'fa fa-home', routerLink: ['/'] }]

I think that onInit is like InitialComponents() in winForm .

How eliminate the tab space in the column in SQL Server 2008

Try this code

SELECT REPLACE([Column], char(9), '') From [dbo.Table] 

char(9) is the TAB character

How to create <input type=“text”/> dynamically

You could do something like this in a loop based on the number of text fields they enter.


But for better performance I'd create all the html first and inject it into the DOM only once.

var count = 20;
var html = [];
while(count--) {
  html.push("<input type='text' name='name", count, "'>");

Edit this example uses jQuery to append the html, but you could easily modify it to use innerHTML as well.

How to merge remote master to local branch

Switch to your local branch

> git checkout configUpdate

Merge remote master to your branch

> git rebase master configUpdate

In case you have any conflicts, correct them and for each conflicted file do the command

> git add [path_to_file/conflicted_file] (e.g. git add app/assets/javascripts/test.js)

Continue rebase

> git rebase --continue

C# RSA encryption/decryption with transmission

well there are really enough examples for this, but anyway, here you go

using System;
using System.Security.Cryptography;

namespace RsaCryptoExample
  static class Program
    static void Main()
      //lets take a new CSP with a new 2048 bit rsa key pair
      var csp = new RSACryptoServiceProvider(2048);

      //how to get the private key
      var privKey = csp.ExportParameters(true);

      //and the public key ...
      var pubKey = csp.ExportParameters(false);

      //converting the public key into a string representation
      string pubKeyString;
        //we need some buffer
        var sw = new System.IO.StringWriter();
        //we need a serializer
        var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
        //serialize the key into the stream
        xs.Serialize(sw, pubKey);
        //get the string from the stream
        pubKeyString = sw.ToString();

      //converting it back
        //get a stream from the string
        var sr = new System.IO.StringReader(pubKeyString);
        //we need a deserializer
        var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
        //get the object back from the stream
        pubKey = (RSAParameters)xs.Deserialize(sr);

      //conversion for the private key is no black magic either ... omitted

      //we have a public key ... let's get a new csp and load that key
      csp = new RSACryptoServiceProvider();

      //we need some data to encrypt
      var plainTextData = "foobar";

      //for encryption, always handle bytes...
      var bytesPlainTextData = System.Text.Encoding.Unicode.GetBytes(plainTextData);

      //apply pkcs#1.5 padding and encrypt our data 
      var bytesCypherText = csp.Encrypt(bytesPlainTextData, false);

      //we might want a string representation of our cypher text... base64 will do
      var cypherText = Convert.ToBase64String(bytesCypherText);

       * some transmission / storage / retrieval
       * and we want to decrypt our cypherText

      //first, get our bytes back from the base64 string ...
      bytesCypherText = Convert.FromBase64String(cypherText);

      //we want to decrypt, therefore we need a csp and load our private key
      csp = new RSACryptoServiceProvider();

      //decrypt and strip pkcs#1.5 padding
      bytesPlainTextData = csp.Decrypt(bytesCypherText, false);

      //get our original plainText back...
      plainTextData = System.Text.Encoding.Unicode.GetString(bytesPlainTextData);

as a side note: the calls to Encrypt() and Decrypt() have a bool parameter that switches between OAEP and PKCS#1.5 padding ... you might want to choose OAEP if it's available in your situation

Allowing the "Enter" key to press the submit button, as opposed to only using MouseClick

There is a simple trick for this. After you constructed the frame with all it buttons do this:


For each frame, you can set a default button that will automatically listen to the Enter key (and maybe some other event's I'm not aware of). When you hit enter in that frame, the ActionListeners their actionPerformed() method will be invoked.

And the problem with your code as far as I see is that your dialog pops up every time you hit a key, because you didn't put it in the if-body. Try changing it to this:

public void keyPressed(KeyEvent e) {
    if (e.getKeyCode()==KeyEvent.VK_ENTER){

        JOptionPane.showMessageDialog(null , "You've Submitted the name " + nameInput.getText());


UPDATE: I found what is wrong with your code. You are adding the key listener to the Submit button instead of to the TextField. Change your code to this:

SubmitButton listener = new SubmitButton(textBoxToEnterName);

How to set Angular 4 background image?

this one is working for me also for internet explorer:

<div class="col imagebox" [ngStyle]="bkUrl"></div>


@Input() background = '571x450img';  
bkUrl = {};   
ngOnInit() {
    this.bkUrl = this.getBkUrl();
getBkUrl() {
    const styles = {
      'background-image': 'url(src/assets/images/' + this.background + '.jpg)'
    return styles;

How to set up gradle and android studio to do release build?

This is a procedure to configure run release version

1- Change build variants to release version.

enter image description here

2- Open project structure. enter image description here

3- Change default config to $signingConfigs.release enter image description here

Create Hyperlink in Slack

Slack now supports hyperlinks natively in the message composer using the Link button or shortcuts:

  • Mac: cmd+shift+U
  • Windows/Linux: ctrl+shift+U

Base64 encoding and decoding in client-side Javascript

Internet Explorer 10+

// Define the string
var string = 'Hello World!';

// Encode the String
var encodedString = btoa(string);
console.log(encodedString); // Outputs: "SGVsbG8gV29ybGQh"

// Decode the String
var decodedString = atob(encodedString);
console.log(decodedString); // Outputs: "Hello World!"


Re-written and modularized UTF-8 and Base64 Javascript Encoding and Decoding Libraries / Modules for AMD, CommonJS, Nodejs and Browsers. Cross-browser compatible.

with Node.js

Here is how you encode normal text to base64 in Node.js:

//Buffer() requires a number, array or string as the first parameter, and an optional encoding type as the second parameter. 
// Default is utf8, possible encoding types are ascii, utf8, ucs2, base64, binary, and hex
var b = new Buffer('JavaScript');
// If we don't use toString(), JavaScript assumes we want to convert the object to utf8.
// We can make it convert to other formats by passing the encoding type to toString().
var s = b.toString('base64');

And here is how you decode base64 encoded strings:

var b = new Buffer('SmF2YVNjcmlwdA==', 'base64')
var s = b.toString();

with Dojo.js

To encode an array of bytes using dojox.encoding.base64:

var str = dojox.encoding.base64.encode(myByteArray);

To decode a base64-encoded string:

var bytes = dojox.encoding.base64.decode(str)

bower install angular-base64

<script src="bower_components/angular-base64/angular-base64.js"></script>

    .module('myApp', ['base64'])
    .controller('myController', [

    '$base64', '$scope', 
    function($base64, $scope) {
        $scope.encoded = $base64.encode('a string');
        $scope.decoded = $base64.decode('YSBzdHJpbmc=');

But How?

If you would like to learn more about how base64 is encoded in general, and in JavaScript in-particular, I would recommend this article: Computer science in JavaScript: Base64 encoding

When restoring a backup, how do I disconnect all active connections?

I ran across this problem while automating a restore proccess in SQL Server 2008. My (successfull) approach was a mix of two of the answers provided.

First, I run across all the connections of said database, and kill them.

DECLARE @SPID int = (SELECT TOP 1 SPID FROM sys.sysprocess WHERE dbid = db_id('dbName'))
While @spid Is Not Null
        Execute ('Kill ' + @spid)
        Select @spid = top 1 spid from master.dbo.sysprocesses
        where dbid = db_id('dbName')

Then, I set the database to a single_user mode


Then, I run the restore...


Kill the connections again

(same query as above)

And set the database back to multi_user.


This way, I ensure that there are no connections holding up the database before setting to single mode, since the former will freeze if there are.

double free or corruption (!prev) error in c program

I didn't check all the code but my guess is that the error is in the malloc call. You have to replace

 double *ptr = malloc(sizeof(double*) * TIME);


 double *ptr = malloc(sizeof(double) * TIME);

since you want to allocate size for a double (not the size of a pointer to a double).

How can we programmatically detect which iOS version is device running on?

To get more specific version number information with major and minor versions separated:

NSString* versionString = [UIDevice currentDevice].systemVersion;
NSArray* vN = [versionString componentsSeparatedByString:@"."];

The array vN will contain the major and minor versions as strings, but if you want to do comparisons, version numbers should be stored as numbers (ints). You can add this code to store them in the C-array* versionNumbers:

int versionNumbers[vN.count];
for (int i = 0; i < sizeof(versionNumbers)/sizeof(versionNumbers[0]); i++)
    versionNumbers[i] = [[vN objectAtIndex:i] integerValue];

* C-arrays used here for more concise syntax.

How can I get a web site's favicon?

HttpWebRequest w = (HttpWebRequest)HttpWebRequest.Create("");

w.AllowAutoRedirect = true;

HttpWebResponse r = (HttpWebResponse)w.GetResponse();

System.Drawing.Image ico;
using (Stream s = r.GetResponseStream())
    ico = System.Drawing.Image.FromStream(s);


Read input numbers separated by spaces

By default, cin reads from the input discarding any spaces. So, all you have to do is to use a do while loop to read the input more than one time:

do {
   cout<<"Enter a number, or numbers separated by a space, between 1 and 1000."<<endl;
   cin >> num;

   // reset your variables

   // your function stuff (calculations)
while (true); // or some condition

Including JavaScript class definition from another file in Node.js

Instead of myFile.js write your files like myFile.mjs. This extension comes with all the goodies of es6, but I mean I recommend you to you webpack and Babel

Remove sensitive files and their commits from Git history

If you pushed to GitHub, force pushing is not enough, delete the repository or contact support

Even if you force push one second afterwards, it is not enough as explained below.

The only valid courses of action are:

  • is what leaked a changeable credential like a password?

    • yes: modify your passwords immediately, and consider using more OAuth and API keys!

    • no (naked pics):

      • do you care if all issues in the repository get nuked?

        • no: delete the repository

        • yes:

          • contact support
          • if the leak is very critical to you, to the point that you are willing to get some repository downtime to make it less likely to leak, make it private while you wait for GitHub support to reply to you

Force pushing a second later is not enough because:

If you delete the repository instead of just force pushing however, commits do disappear even from the API immediately and give 404, e.g. This works even if you recreate another repository with the same name.

To test this out, I have created a repo: and did:

git init
git remote add origin [email protected]:cirosantilli/test-dangling.git

touch a
git add .
git commit -m 0
git push

touch b
git add .
git commit -m 1
git push

touch c
git rm b
git add .
git commit --amend --no-edit
git push -f

See also: How to remove a dangling commit from GitHub?

git filter-repo is now officially recommended over git filter-branch

This is mentioned in the manpage of git filter-branch in Git 2.5 itself.

With git filter repo, you could either remove certain files with: Remove folder and its contents from git/GitHub's history

pip install git-filter-repo
git filter-repo --path path/to/remove1 --path path/to/remove2 --invert-paths

This automatically removes empty commits.

Or you can replace certain strings with: How to replace a string in a whole Git history?

git filter-repo --replace-text <(echo 'my_password==>xxxxxxxx')

ArrayBuffer to base64 encoded string

My recommendation for this is to NOT use native btoa strategies—as they don't correctly encode all ArrayBuffer's…

rewrite the DOMs atob() and btoa()

Since DOMStrings are 16-bit-encoded strings, in most browsers calling window.btoa on a Unicode string will cause a Character Out Of Range exception if a character exceeds the range of a 8-bit ASCII-encoded character.

While I have never encountered this exact error, I have found that many of the ArrayBuffer's I have tried to encode have encoded incorrectly.

I would either use MDN recommendation or gist.

Differences between dependencyManagement and dependencies in Maven

There's still one thing that is not highlighted enough, in my opinion, and that is unwanted inheritance.

Here's an incremental example:

I declare in my parent pom:


boom! I have it in my Child A, Child B and Child C modules:

  • Implicilty inherited by child poms
  • A single place to manage
  • No need to redeclare anything in child poms
  • I can still redelcare and override to version 18.0 in a Child B if I want to.

But what if I end up not needing guava in Child C, and neither in the future Child D and Child E modules?

They will still inherit it and this is undesired! This is just like Java God Object code smell, where you inherit some useful bits from a class, and a tonn of unwanted stuff as well.

This is where <dependencyManagement> comes into play. When you add this to your parent pom, all of your child modules STOP seeing it. And thus you are forced to go into each individual module that DOES need it and declare it again (Child A and Child B, without the version though).

And, obviously, you don't do it for Child C, and thus your module remains lean.

How to get all checked checkboxes

For a simple two- (or one) liner this code can be:

checkboxes = document.getElementsByName("NameOfCheckboxes");
selectedCboxes = => ch.checked==true);

Here the part converts the object NodeList of all the checkboxes holding that name ("NameOfCheckboxes") into a new array, on which you then use the filter method. You can then also, for example, extract the values of the checkboxes by adding a .map(ch => ch.value) on the end of line 2. The => is javascript's arrow function notation.

How to export html table to excel using javascript

Excel Export Script works on IE7+ , Firefox and Chrome

function fnExcelReport()
             var tab_text="<table border='2px'><tr bgcolor='#87AFC6'>";
             var textRange; var j=0;
          tab = document.getElementById('headerTable'); // id of table

          for(j = 0 ; j < tab.rows.length ; j++) 

          tab_text= tab_text.replace(/<A[^>]*>|<\/A>/g, "");//remove if u want links in your table
          tab_text= tab_text.replace(/<img[^>]*>/gi,""); // remove if u want images in your table
                      tab_text= tab_text.replace(/<input[^>]*>|<\/input>/gi, ""); // reomves input params

               var ua = window.navigator.userAgent;
              var msie = ua.indexOf("MSIE "); 

                 if (msie > 0 || !!navigator.userAgent.match(/Trident.*rv\:11\./))      // If Internet Explorer
                            sa=txtArea1.document.execCommand("SaveAs",true,"Say Thanks to Sumit.xls");
                  else                 //other browser not tested on IE 11
                      sa ='data:application/,' + encodeURIComponent(tab_text));  

                      return (sa);

    Just Create a blank iframe
    enter code here
        <iframe id="txtArea1" style="display:none"></iframe>

    Call this function on

        <button id="btnExport" onclick="fnExcelReport();"> EXPORT 

How to use passive FTP mode in Windows command prompt?

FileZilla Works well. I Use FileZilla FTP Client "Manual Transfer" which supports Passive mode.

Example: Open FileZilla and Select "Transfer" >> "Manual Transfer" then within the Manual Transfer Window, perform the following:

  1. Confirm proper Download / Upload option is selected
  2. For Remote: Enter name of directory where the file to download is located
  3. For Remote: Enter the name of the file to be downloaded
  4. For Local: Browse to desired directory you want to download file to
  5. For Local: Enter a file name to save downloaded file As (use same file name as file to be downloaded unless you want to change it)
  6. Check-Box "Start transfer immediately" and Click "OK"
  7. Download should start momentarily
  8. Note: If you forgot to Check-Box "Start transfer immediately"... No Problem: just Right-Click on the file to be downloaded (within the Process Queue (file transfer queue) at the bottom of the FileZilla window pane and Select "Process Queue"
  9. Download process should begin momentarily
  10. Done

What is the difference between .NET Core and .NET Standard Class Library project types?

The short answer would be:

IAnimal == .NetStandard (General)
ICat == .NetCore (Less general)
IDog == .NetFramework (Specific / oldest and has the most features)

What is the command for cut copy paste a file from one directory to other directory

use the xclip which is command line interface to X selections


apt-get install xclip


echo "test xclip " > /tmp/test.xclip
xclip -i < /tmp/test.xclip
xclip -o > /tmp/test.xclip.out

cat /tmp/test.xclip.out   # "test xclip"


Using getline() with file input in C++

you should do as:

getline(name, sizeofname, '\n');
strtok(name, " ");

This will give you the "joht" in name then to get next token,

temp = strtok(NULL, " ");

temp will get "smith" in it. then you should use string concatination to append the temp at end of name. as:

strcat(name, temp);

(you may also append space first, to obtain a space in between).

Keyboard shortcut to paste clipboard content into command prompt window (Win XP)

There is also a great open source tool called clink, which extends cmd by many features. One of them is being able to use ctrl+v to insert text.

Check if element at position [x] exists in the list

if(list.ElementAtOrDefault(2) != null)
   // logic

ElementAtOrDefault() is part of the System.Linq namespace.

Although you have a List, so you can use list.Count > 2.

How can I convert radians to degrees with Python?

I also like to define my own functions that take and return arguments in degrees rather than radians. I am sure there some capitalization purest who don't like my names, but I just use a capital first letter for my custom functions. The definitions and testing code are below.

#Definitions for trig functions using degrees.
def Cos(a):
    return cos(radians(a))
def Sin(a):
    return sin(radians(a))
def Tan(a):
    return tan(radians(a))
def ArcTan(a):
    return degrees(arctan(a))
def ArcSin(a):
    return degrees(arcsin(a))
def ArcCos(a):
    return degrees(arccos(a))

#Testing Code

Note that I have imported math (or numpy) into the namespace with

from math import *

Also note, that my functions are in the namespace in which they were defined. For instance,


does not exist.

go to link on button click - jquery

$('.button1').click(function() {
   document.location.href='/index.php?id=' + $(this).attr('id');

Are the days of passing const std::string & as a parameter over?

As @JDlugosz points out in the comments, Herb gives other advice in another (later?) talk, see roughly from here:

His advice boils down to only using value parameters for a function f that takes so-called sink arguments, assuming you will move construct from these sink arguments.

This general approach only adds the overhead of a move constructor for both lvalue and rvalue arguments compared to an optimal implementation of f tailored to lvalue and rvalue arguments respectively. To see why this is the case, suppose f takes a value parameter, where T is some copy and move constructible type:

void f(T x) {
  T y{std::move(x)};

Calling f with an lvalue argument will result in a copy constructor being called to construct x, and a move constructor being called to construct y. On the other hand, calling f with an rvalue argument will cause a move constructor to be called to construct x, and another move constructor to be called to construct y.

In general, the optimal implementation of f for lvalue arguments is as follows:

void f(const T& x) {
  T y{x};

In this case, only one copy constructor is called to construct y. The optimal implementation of f for rvalue arguments is, again in general, as follows:

void f(T&& x) {
  T y{std::move(x)};

In this case, only one move constructor is called to construct y.

So a sensible compromise is to take a value parameter and have one extra move constructor call for either lvalue or rvalue arguments with respect to the optimal implementation, which is also the advice given in Herb's talk.

As @JDlugosz pointed out in the comments, passing by value only makes sense for functions that will construct some object from the sink argument. When you have a function f that copies its argument, the pass-by-value approach will have more overhead than a general pass-by-const-reference approach. The pass-by-value approach for a function f that retains a copy of its parameter will have the form:

void f(T x) {
  T y{...};
  y = std::move(x);

In this case, there is a copy construction and a move assignment for an lvalue argument, and a move construction and move assignment for an rvalue argument. The most optimal case for an lvalue argument is:

void f(const T& x) {
  T y{...};
  y = x;

This boils down to an assignment only, which is potentially much cheaper than the copy constructor plus move assignment required for the pass-by-value approach. The reason for this is that the assignment might reuse existing allocated memory in y, and therefore prevent (de)allocations, whereas the copy constructor will usually allocate memory.

For an rvalue argument the most optimal implementation for f that retains a copy has the form:

void f(T&& x) {
  T y{...};
  y = std::move(x);

So, only a move assignment in this case. Passing an rvalue to the version of f that takes a const reference only costs an assignment instead of a move assignment. So relatively speaking, the version of f taking a const reference in this case as the general implementation is preferable.

So in general, for the most optimal implementation, you will need to overload or do some kind of perfect forwarding as shown in the talk. The drawback is a combinatorial explosion in the number of overloads required, depending on the number of parameters for f in case you opt to overload on the value category of the argument. Perfect forwarding has the drawback that f becomes a template function, which prevents making it virtual, and results in significantly more complex code if you want to get it 100% right (see the talk for the gory details).

Remove a git commit which has not been pushed

Simply type in the console :

$ git reset HEAD~

This command discards all local commits ahead of the remote HEAD

Input group - two inputs close to each other

My solution requires no additional css and works with any combination of input-addon, input-btn and form-control. It just uses pre-existing bootstrap classes

<script src=""></script>_x000D_
<script src=""></script>_x000D_
<link href="" type="text/css" rel="stylesheet" />_x000D_
<form style="padding:10px; margin:10px" action="" class=" form-inline">_x000D_
  <div class="form-group">_x000D_
    <div class="input-group">_x000D_
    <div class="form-group">_x000D_
        <div class="input-group">_x000D_
          <input type="text" class="form-control" placeholder="MinVal">_x000D_
      <div class="form-group">_x000D_
        <div class="input-group">_x000D_
          <input type="text" class="form-control" placeholder="MaxVal">_x000D_

This will be inline if there is space and wrap for smaller screens.

Full Example ( input-addon, input-btn and form-control. )


<script src=""></script>_x000D_
<script src=""></script>_x000D_
<link href="" type="text/css" rel="stylesheet" />_x000D_
<form style="padding:10px; margin:10px" action="" class=" form-inline">_x000D_
  <div class="form-group">_x000D_
    <div class="input-group">_x000D_
      <div class="form-group">_x000D_
        <div class="input-group">_x000D_
          <span class="input-group-addon" id="basic-addon1">@</span>_x000D_
          <input type="text" class="form-control" placeholder="Username" aria-describedby="basic-addon1">_x000D_
      <div class="form-group">_x000D_
        <div class="input-group">_x000D_
          <span class="input-group-addon" id="basic-addon1">@</span>_x000D_
          <input type="text" class="form-control" placeholder="Username" aria-describedby="basic-addon1">_x000D_
      <div class="form-group">_x000D_
        <div class="input-group">_x000D_
          <span class="input-group-addon" id="basic-addon1">@</span>_x000D_
          <input type="text" class="form-control" placeholder="Username" aria-describedby="basic-addon1">_x000D_
      <div class="form-group">_x000D_
        <div class="input-group">_x000D_
          <input type="text" class="form-control" placeholder="Username" aria-describedby="basic-addon1">_x000D_
      <div class="form-group">_x000D_
        <div class="input-group">_x000D_
          <input type="text" class="form-control" placeholder="Username" aria-describedby="basic-addon1">_x000D_

submitting a GET form with query string params and hidden params disappear

Isn't that what hidden parameters are for to start with...?

<form action="" method="GET">
  <input type="hidden" name="a" value="1" /> 
  <input type="hidden" name="b" value="2" /> 
  <input type="hidden" name="c" value="3" /> 
  <input type="submit" /> 

I wouldn't count on any browser retaining any existing query string in the action URL.

As the specifications (RFC1866, page 46; HTML 4.x section 17.13.3) state:

If the method is "get" and the action is an HTTP URI, the user agent takes the value of action, appends a `?' to it, then appends the form data set, encoded using the "application/x-www-form-urlencoded" content type.

Maybe one could percent-encode the action-URL to embed the question mark and the parameters, and then cross one's fingers to hope all browsers would leave that URL as it (and validate that the server understands it too). But I'd never rely on that.

By the way: it's not different for non-hidden form fields. For POST the action URL could hold a query string though.

Run script on mac prompt "Permission denied"

To run in the administrator mode in mac

sudo su

How can I clear event subscriptions in C#?

From within the class, you can set the (hidden) variable to null. A null reference is the canonical way of representing an empty invocation list, effectively.

From outside the class, you can't do this - events basically expose "subscribe" and "unsubscribe" and that's it.

It's worth being aware of what field-like events are actually doing - they're creating a variable and an event at the same time. Within the class, you end up referencing the variable. From outside, you reference the event.

See my article on events and delegates for more information.

How to hide a button programmatically?

In Kotlin

myButton.visibility = View.GONE

Print string and variable contents on the same line in R

You can use paste with print

print(paste0("Current working dir: ", wd))

or cat

cat("Current working dir: ", wd)

Using jq to parse and display multiple fields in a json serially

my approach will be (your json example is not well formed.. guess thats only a sample)

jq '.Front[] | [.Name,.Out,.In,.Groups] | join("|")'  front.json  > output.txt

returns something like this

" -443|||"

and grep the output with regular expression.

SQL Server 2008: How to query all databases sizes?

IF OBJECT_ID('tempdb.dbo.#space') IS NOT NULL
    DROP TABLE #space

      database_id INT PRIMARY KEY
    , data_used_size DECIMAL(18,2)
    , log_used_size DECIMAL(18,2)


    SELECT '
    USE [' + + ']
    INSERT INTO #space (database_id, data_used_size, log_used_size)
        , SUM(CASE WHEN [type] = 0 THEN space_used END)
        , SUM(CASE WHEN [type] = 1 THEN space_used END)
    FROM (
        SELECT s.[type], space_used = SUM(FILEPROPERTY(, ''SpaceUsed'') * 8. / 1024)
        FROM sys.database_files s
        GROUP BY s.[type]
    ) t;'
    FROM sys.databases d
    WHERE d.[state] = 0
    FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, '')

EXEC sys.sp_executesql @SQL

    , d.state_desc
    , d.recovery_model_desc
    , t.total_size
    , t.data_size
    , s.data_used_size
    , t.log_size
    , s.log_used_size
        , log_size = CAST(SUM(CASE WHEN [type] = 1 THEN size END) * 8. / 1024 AS DECIMAL(18,2))
        , data_size = CAST(SUM(CASE WHEN [type] = 0 THEN size END) * 8. / 1024 AS DECIMAL(18,2))
        , total_size = CAST(SUM(size) * 8. / 1024 AS DECIMAL(18,2))
    FROM sys.master_files
    GROUP BY database_id
) t
JOIN sys.databases d ON d.database_id = t.database_id
LEFT JOIN #space s ON d.database_id = s.database_id
ORDER BY t.total_size DESC

Python send UDP packet

Your code works as is for me. I'm verifying this by using netcat on Linux.

Using netcat, I can do nc -ul 5005 which will listen for packets at:

  • IP:
  • Port: 5005
  • Protocol: UDP

That being said, here's the output that I see when I run your script, while having netcat running.

[9:34am][wlynch@watermelon ~] nc -ul 5005
Hello, World!

HTTP Error 500.30 - ANCM In-Process Start Failure

For me, everything was just fine but the issue was due to publishing by different VS versions, weird !!! (latest VS 2019 (16.4.2)). When I publish the application with VS 2017 it works fine.

The actual issue is in its dependency json file (e.g. MyWebApp.deps.json) in the publish folder. Hope it helps someone.

enter image description here

Should I use string.isEmpty() or "".equals(string)?

You can use apache commons StringUtils isEmpty() or isNotEmpty().

CGContextDrawImage draws image upside down when passed UIImage.CGImage

It happens because QuartzCore has the coordinate system "bottom-left", while UIKit – "top-left".

In the case you can extend CGContext:

extension CGContext {
  func changeToTopLeftCoordinateSystem() {
    translateBy(x: 0, y: boundingBoxOfClipPath.size.height)
    scaleBy(x: 1, y: -1)

// somewhere in render 
ctx.draw(cgImage!, in: frame)

How to make a vertical SeekBar in Android?

Working example

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;

public class VerticalSeekBar extends SeekBar {

    public VerticalSeekBar(Context context) {

    public VerticalSeekBar(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

    public VerticalSeekBar(Context context, AttributeSet attrs) {
        super(context, attrs);

    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(h, w, oldh, oldw);

   public synchronized void setProgress(int progress)  // it is necessary for calling setProgress on click of a button
    onSizeChanged(getWidth(), getHeight(), 0, 0); 
    protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(heightMeasureSpec, widthMeasureSpec);
        setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());

    protected void onDraw(Canvas c) {
        c.translate(-getHeight(), 0);


    public boolean onTouchEvent(MotionEvent event) {
        if (!isEnabled()) {
            return false;

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_MOVE:
            case MotionEvent.ACTION_UP:
                setProgress(getMax() - (int) (getMax() * event.getY() / getHeight()));
                onSizeChanged(getWidth(), getHeight(), 0, 0);

            case MotionEvent.ACTION_CANCEL:
        return true;

There, paste the code and save it. Now use it in your XML layout:


Make sure to create a package android.widget and create under this package

What does O(log n) mean exactly?

You can think of O(log N) intuitively by saying the time is proportional to the number of digits in N.

If an operation performs constant time work on each digit or bit of an input, the whole operation will take time proportional to the number of digits or bits in the input, not the magnitude of the input; thus, O(log N) rather than O(N).

If an operation makes a series of constant time decisions each of which halves (reduces by a factor of 3, 4, 5..) the size of the input to be considered, the whole will take time proportional to log base 2 (base 3, base 4, base 5...) of the size N of the input, rather than being O(N).

And so on.

I am not able launch JNLP applications using "Java Web Start"?

Same solution worked as suggested by hpereira The issue was due to JRE version was 32 bit and not 64 Bit Check with java -version to see if your Java is 64 bit

C:\>java -version
java version "1.8.0_192"
Java(TM) SE Runtime Environment (build 1.8.0_192-b12)
Java HotSpot(TM) **64-Bit Server** VM (build 25.192-b12, mixed mode)

How can I clear the input text after clicking

I would recommend to use this since I have the same issue which got fixed.


How to get Map data using JDBCTemplate.queryForMap

queryForMap is appropriate if you want to get a single row. You are selecting without a where clause, so you probably want to queryForList. The error is probably indicative of the fact that queryForMap wants one row, but you query is retrieving many rows.

Check out the docs. There is a queryForList that takes just sql; the return type is a


So once you have the results, you can do what you are doing. I would do something like

List results = template.queryForList(sql);

for (Map m : results){

I'll let you fill in the details, but I would not iterate over keys in this case. I like to explicit about what I am expecting.

If you have a User object, and you actually want to load User instances, you can use the queryForList that takes sql and a class type

queryForList(String sql, Class<T> elementType)

(wow Spring has changed a lot since I left Javaland.)

Parsing jQuery AJAX response

     type: "POST",
     url: '/admin/systemgoalssystemgoalupdate?format=html',
     data: formdata,
     success: function (data) {
     dataType: "json"

Making a UITableView scroll when text field is selected

Here is my solution inspired by "Event edit" screen from iOS7 Calendar app.

One of key points of this solution is that keyboard is dismissed when user scrolls table.


1) Add property that will store selected textfield:

@property (strong) UITextField *currentTextField;

and BOOL variable that we will use to check if we need to hide keyboard when user scrolls table.

BOOL hideKeyboardOnScroll;

2) Handle UITextField delegate callbacks:

#pragma mark - UITextFieldDelegate

- (void) textFieldDidBeginEditing: (UITextField *) textField {
    self.currentTextField = textField;

- (void) textFieldDidEndEditing: (UITextField *) textField {
    self.currentTextField = nil;

- (BOOL) textFieldShouldReturn: (UITextField *) textField {
   [textField resignFirstResponder];

    CGPoint newContentOffset = CGPointZero;
    if (tableView.contentSize.height > tableView.frame.size.height) {
        newContentOffset.y = MIN(tableView.contentOffset.y, tableView.contentSize.height - tableView.frame.size.height);
    [tableView setContentOffset: newContentOffset animated: YES];

    return YES;

3) Handle UIScrollViewDelegate method to check that user scroll view.

#pragma mark - UIScrollViewDelegate

- (void) scrollViewDidScroll: (UIScrollView *) scrollView {
    if (hideKeyboardOnScroll == YES) {
        [self.currentTextField resignFirstResponder];

4) Subscribe to keyboard notifications in viewcontroller's [viewWillAppear] method and unsubscribe in [viewWillDisappear] method.

- (void) viewWillAppear: (BOOL) animated {
    [super viewWillAppear: animated];

    [ [NSNotificationCenter defaultCenter] addObserver: self selector: @selector(keyboardWillShow:)
                                                  name: UIKeyboardWillShowNotification object: nil];
    [ [NSNotificationCenter defaultCenter] addObserver: self selector: @selector(keyboardWillHide:)
                                                  name: UIKeyboardWillHideNotification object: nil];

- (void) viewWillDisappear: (BOOL) animated {
    [super viewWillDisappear: animated];

    [ [NSNotificationCenter defaultCenter] removeObserver: self name: UIKeyboardDidShowNotification object: nil];
    [ [NSNotificationCenter defaultCenter] removeObserver: self name: UIKeyboardWillHideNotification object: nil];    

5) Handle keyboard notifications:

- (void) keyboardWillShow: (NSNotification *) notification {
    CGRect keyboardFrame = [ [ [notification userInfo] objectForKey: UIKeyboardFrameBeginUserInfoKey] CGRectValue];

    // Find cell with textfield.
    CGRect textFieldFrame = [tableView convertRect: self.currentTextField.frame fromView: self.currentTextField];
    NSIndexPath *indexPath = [tableView indexPathForRowAtPoint: textFieldFrame.origin];
    UITableViewCell *cell = [tableView cellForRowAtIndexPath: indexPath];

    // Shrink tableView size.
    CGRect tableViewFrame = tableView.frame;
    tableView.frame = CGRectMake(tableView.frame.origin.x, tableView.frame.origin.y, tableView.frame.size.width,
                             self.view.frame.size.height - tableView.frame.origin.y - keyboardFrame.size.height);

    // Check if cell is visible in shrinked table size.
    BOOL cellIsFullyVisible = YES;
    if ( cell.frame.origin.y < tableView.contentOffset.y ||
        (cell.frame.origin.y + cell.frame.size.height) > (tableView.contentOffset.y + tableView.frame.size.height) ) {
        cellIsFullyVisible = NO;

    // If cell is not fully visible when scroll table to show cell;
    if (cellIsFullyVisible == NO) {
        CGPoint contentOffset = CGPointMake(tableView.contentOffset.x, CGRectGetMaxY(cell.frame) - tableView.frame.size.height);
        if (cell.frame.origin.y < tableView.contentOffset.y) {
            contentOffset.y = cell.frame.origin.y;
        contentOffset.y = MAX(0, contentOffset.y);

        // For some reason [setContentOffset] is called without delay then
        // this code may not work for some cells. That why we call it with brief delay.
        dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC));
        dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
            [UIView animateWithDuration: 0.5 animations:^{
                [tableView setContentOffset: contentOffset animated: NO];
            } completion: ^(BOOL finished) {
                hideKeyboardOnScroll = YES;
    } else {
        hideKeyboardOnScroll = YES;

    // Finally restore original table frame.
    tableView.frame = tableViewFrame;

- (void) keyboardWillHide: (NSNotification *) notification {
    [super keyboardWillHide: notification];

    hideKeyboardOnScroll = NO;

Is there a way to make AngularJS load partials in the beginning and not at when needed?

Yes, there are at least 2 solutions for this:

  1. Use the script directive ( to put your partials in the initially loaded HTML
  2. You could also fill in $templateCache ($templateCache) from JavaScript if needed (possibly based on result of $http call)

If you would like to use method (2) to fill in $templateCache you can do it like this:

$templateCache.put('second.html', '<b>Second</b> template');

Of course the templates content could come from a $http call:

$http.get('third.html', {cache:$templateCache});

Here is the plunker those techniques:

Should operator<< be implemented as a friend or as a member function?

operator<< implemented as a friend function:

#include <iostream>
#include <string>
using namespace std;

class Samp
    int ID;
    string strName; 
    friend std::ostream& operator<<(std::ostream &os, const Samp& obj);
 std::ostream& operator<<(std::ostream &os, const Samp& obj)
        os << obj.ID<< “ ” << obj.strName;
        return os;

int main()
   Samp obj, obj1;
    obj.ID = 100;
    obj.strName = "Hello";
    cout << obj <<endl<< obj1;


100 Hello
100 Hello

This can be a friend function only because the object is on the right hand side of operator<< and argument cout is on the left hand side. So this can't be a member function to the class, it can only be a friend function.

What is the most efficient/elegant way to parse a flat table into a tree?

As of Oracle 9i, you can use CONNECT BY.

SELECT LPAD(' ', (LEVEL - 1) * 4) || "Name" AS "Name"
CONNECT BY PRIOR "Id" = "ParentId"

As of SQL Server 2005, you can use a recursive common table expression (CTE).

WITH [NodeList] (
  , [ParentId]
  , [Level]
  , [Order]
) AS (
  SELECT [Node].[Id]
    , [Node].[ParentId]
    , 0 AS [Level]
    , CONVERT([varchar](MAX), [Node].[Order]) AS [Order]
  FROM [Node]
  WHERE [Node].[ParentId] = 0
  SELECT [Node].[Id]
    , [Node].[ParentId]
    , [NodeList].[Level] + 1 AS [Level]
    , [NodeList].[Order] + '|'
      + CONVERT([varchar](MAX), [Node].[Order]) AS [Order]
  FROM [Node]
    INNER JOIN [NodeList] ON [NodeList].[Id] = [Node].[ParentId]
) SELECT REPLICATE(' ', [NodeList].[Level] * 4) + [Node].[Name] AS [Name]
FROM [Node]
  INNER JOIN [NodeList] ON [NodeList].[Id] = [Node].[Id]
ORDER BY [NodeList].[Order]

Both will output the following results.

'Node 1'
'    Node 1.1'
'        Node 1.1.1'
'    Node 1.2'
'Node 2'
'    Node 2.1'

XSLT getting last element

You need to put the last() indexing on the nodelist result, rather than as part of the selection criteria. Try:


Creating an array from a text file in Bash

mapfile and readarray (which are synonymous) are available in Bash version 4 and above. If you have an older version of Bash, you can use a loop to read the file into an array:

while IFS= read -r line; do
done < file

In case the file has an incomplete (missing newline) last line, you could use this alternative:

while IFS= read -r line || [[ "$line" ]]; do
done < file


Is it possible to use "return" in stored procedure?



  RETURN 'This is being returned from a function';
END test_function;

How to Delete a topic in apache kafka

Deletion of a topic has been supported since 0.8.2.x version. You have to enable topic deletion (setting delete.topic.enable to true) on all brokers first.

Note: Ever since 1.0.x, the functionality being stable, delete.topic.enable is by default true.

Follow this step by step process for manual deletion of topics

  1. Stop Kafka server
  2. Delete the topic directory, on each broker (as defined in the logs.dirs and log.dir properties) with rm -rf command
  3. Connect to Zookeeper instance: host:port
  4. From within the Zookeeper instance:
    1. List the topics using: ls /brokers/topics
    2. Remove the topic folder from ZooKeeper using: rmr /brokers/topics/yourtopic
    3. Exit the Zookeeper instance (Ctrl+C)
  5. Restart Kafka server
  6. Confirm if it was deleted or not by using this command --list --zookeeper host:port

REST API Best practice: How to accept list of parameter values as input

A Step Back

First and foremost, REST describes a URI as a universally unique ID. Far too many people get caught up on the structure of URIs and which URIs are more "restful" than others. This argument is as ludicrous as saying naming someone "Bob" is better than naming him "Joe" – both names get the job of "identifying a person" done. A URI is nothing more than a universally unique name.

So in REST's eyes arguing about whether ?id=["101404","7267261"] is more restful than ?id=101404,7267261 or \Product\101404,7267261 is somewhat futile.

Now, having said that, many times how URIs are constructed can usually serve as a good indicator for other issues in a RESTful service. There are a couple of red flags in your URIs and question in general.


  1. Multiple URIs for the same resource and Content-Location

    We may want to accept both styles but does that flexibility actually cause more confusion and head aches (maintainability, documentation, etc.)?

    URIs identify resources. Each resource should have one canonical URI. This does not mean that you can't have two URIs point to the same resource but there are well defined ways to go about doing it. If you do decide to use both the JSON and list based formats (or any other format) you need to decide which of these formats is the main canonical URI. All responses to other URIs that point to the same "resource" should include the Content-Location header.

    Sticking with the name analogy, having multiple URIs is like having nicknames for people. It is perfectly acceptable and often times quite handy, however if I'm using a nickname I still probably want to know their full name – the "official" way to refer to that person. This way when someone mentions someone by their full name, "Nichloas Telsa", I know they are talking about the same person I refer to as "Nick".

  2. "Search" in your URI

    A more complex case is when we want to offer more complex inputs. For example, if we want to allow multiple filters on search...

    A general rule of thumb of mine is, if your URI contains a verb, it may be an indication that something is off. URI's identify a resource, however they should not indicate what we're doing to that resource. That's the job of HTTP or in restful terms, our "uniform interface".

    To beat the name analogy dead, using a verb in a URI is like changing someone's name when you want to interact with them. If I'm interacting with Bob, Bob's name doesn't become "BobHi" when I want to say Hi to him. Similarly, when we want to "search" Products, our URI structure shouldn't change from "/Product/..." to "/Search/...".

Answering Your Initial Question

  1. Regarding ["101404","7267261"] vs 101404,7267261: My suggestion here is to avoid the JSON syntax for simplicity's sake (i.e. don't require your users do URL encoding when you don't really have to). It will make your API a tad more usable. Better yet, as others have recommended, go with the standard application/x-www-form-urlencoded format as it will probably be most familiar to your end users (e.g. ?id[]=101404&id[]=7267261). It may not be "pretty", but Pretty URIs does not necessary mean Usable URIs. However, to reiterate my initial point though, ultimately when speaking about REST, it doesn't matter. Don't dwell too heavily on it.

  2. Your complex search URI example can be solved in very much the same way as your product example. I would recommend going the application/x-www-form-urlencoded format again as it is already a standard that many are familiar with. Also, I would recommend merging the two.

Your URI...


Your URI after being URI encoded...


Can be transformed to...


Aside from avoiding the requirement of URL encoding and making things look a bit more standard, it now homogenizes the API a bit. The user knows that if they want to retrieve a Product or List of Products (both are considered a single "resource" in RESTful terms), they are interested in /Product/... URIs.

WCF gives an unsecured or incorrectly secured fault error

        <binding name="ISG_Binding_Configuration" bypassProxyOnLocal="true" useDefaultWebProxy="false" hostNameComparisonMode="WeakWildcard" sendTimeout="00:30:00" receiveTimeout="00:30:00" maxReceivedMessageSize="2147483647" maxBufferPoolSize="2147483647">_x000D_
          <readerQuotas maxArrayLength="2147483647" maxStringContentLength="2147483647" />_x000D_
          <security mode="None">_x000D_
            <message establishSecurityContext="false" clientCredentialType="UserName"/>_x000D_

Convert string to datetime in

Pass the decode pattern to ParseExact

Dim d as string = "201210120956"
Dim dt = DateTime.ParseExact(d, "yyyyMMddhhmm", Nothing)

ParseExact is available only from Net FrameWork 2.0.
If you are still on 1.1 you could use Parse, but you need to provide the IFormatProvider adequate to your string

How do I convert an existing callback API to promises?

I don't think the window.onload suggestion by @Benjamin will work all the time, as it doesn't detect whether it is called after the load. I have been bitten by that many times. Here is a version which should always work:

function promiseDOMready() {
    return new Promise(function(resolve) {
        if (document.readyState === "complete") return resolve();
        document.addEventListener("DOMContentLoaded", resolve);

How do I validate a date in this format (yyyy-mm-dd) using jquery?

try this Here is working Demo:

$(function() {
    $('#btnSubmit').bind('click', function(){
        var txtVal =  $('#txtDate').val();
            alert('Valid Date');
            alert('Invalid Date');

function isDate(txtDate)
    var currVal = txtDate;
    if(currVal == '')
        return false;

    var rxDatePattern = /^(\d{4})(\/|-)(\d{1,2})(\/|-)(\d{1,2})$/; //Declare Regex
    var dtArray = currVal.match(rxDatePattern); // is format OK?

    if (dtArray == null) 
        return false;

    //Checks for mm/dd/yyyy format.
    dtMonth = dtArray[3];
    dtDay= dtArray[5];
    dtYear = dtArray[1];        

    if (dtMonth < 1 || dtMonth > 12) 
        return false;
    else if (dtDay < 1 || dtDay> 31) 
        return false;
    else if ((dtMonth==4 || dtMonth==6 || dtMonth==9 || dtMonth==11) && dtDay ==31) 
        return false;
    else if (dtMonth == 2) 
        var isleap = (dtYear % 4 == 0 && (dtYear % 100 != 0 || dtYear % 400 == 0));
        if (dtDay> 29 || (dtDay ==29 && !isleap)) 
                return false;
    return true;


changed regex is:

var rxDatePattern = /^(\d{4})(\/|-)(\d{1,2})(\/|-)(\d{1,2})$/; //Declare Regex

What is the ellipsis (...) for in this method signature?

Those are varargs they are used to create a method that receive any number of arguments.

For instance PrintStream.printf method uses it, since you don't know how many would arguments you'll use.

They can only be used as final position of the arguments.

varargs was was added on Java 1.5

How can I stop python.exe from closing immediately after I get an output?

Python files are executables, which means that you can run them directly from command prompt(assuming you have windows). You should be able to just enter in the directory, and then run the program. Also, (assuming you have python 3), you can write:

input("Press enter to close program")

and you can just press enter when you've read your results.

Row Offset in SQL Server

There is OFFSET .. FETCH in SQL Server 2012, but you will need to specify an ORDER BY column.

If you really don't have any explicit column that you could pass as an ORDER BY column (as others have suggested), then you can use this trick:


... or


We're using it in jOOQ when users do not explicitly specify an order. This will then produce pretty random ordering without any additional costs.

Check if a given time lies between two times regardless of date

Simple solution for all gaps:

    public boolean isNowTimeBetween(String startTime, String endTime) {
        LocalTime start = LocalTime.parse(startTime);//"22:00"
        LocalTime end = LocalTime.parse(endTime);//"10:00"
        LocalTime now =;

        if (start.isBefore(end))
            return now.isAfter(start) && now.isBefore(end);

        return now.isBefore(start)
                ? now.isBefore(start) && now.isBefore(end)
                : now.isAfter(start) && now.isAfter(end);

PHP code to convert a MySQL query to CSV

An update to @jrgns (with some slight syntax differences) solution.

$result = mysql_query('SELECT * FROM `some_table`'); 
if (!$result) die('Couldn\'t fetch records'); 
$num_fields = mysql_num_fields($result); 
$headers = array(); 
for ($i = 0; $i < $num_fields; $i++) 
       $headers[] = mysql_field_name($result , $i); 
$fp = fopen('php://output', 'w'); 
if ($fp && $result) 
       header('Content-Type: text/csv');
       header('Content-Disposition: attachment; filename="export.csv"');
       header('Pragma: no-cache');    
       header('Expires: 0');
       fputcsv($fp, $headers); 
       while ($row = mysql_fetch_row($result)) 
          fputcsv($fp, array_values($row)); 

How to define object in array in Mongoose schema correctly with 2d geo index

I had a similar issue with mongoose :

    [ '[object Object]',
     '[object Object]',
     '[object Object]',
     '[object Object]' ] }

In fact, I was using "type" as a property name in my schema :

fields: [
      name: String,
      type: {
        type: String
      registrationEnabled: Boolean,
      checkinEnabled: Boolean

To avoid that behavior, you have to change the parameter to :

fields: [
      name: String,
      type: {
        type: { type: String }
      registrationEnabled: Boolean,
      checkinEnabled: Boolean

Efficient way to insert a number into a sorted array of numbers?

Had your first code been bug free, my best guess is, it would have been how you do this job in JS. I mean;

  1. Make a binary search to find the index of insertion
  2. Use splice to perform your insertion.

This is almost always 2x faster than a top down or bottom up linear search and insert as mentioned in domoarigato's answer which i liked very much and took it as a basis to my benchmark and finally push and sort.

Of course under many cases you are probably doing this job on some objects in real life and here i have generated a benchmark test for these three cases for an array of size 100000 holding some objects. Feel free to play with it.

How to add a .dll reference to a project in Visual Studio

Another method is by using the menu within visual studio. Project -> Add Reference... I recommend copying the needed .dll to your resource folder, or local project folder.

What is an instance variable in Java?

Instance variable is the variable declared inside a class, but outside a method: something like:

class IronMan {

    /** These are all instance variables **/
    public String realName;
    public String[] superPowers;
    public int age;

    /** Getters and setters here **/

Now this IronMan Class can be instantiated in another class to use these variables. Something like:

class Avengers {

    public static void main(String[] a) {
        IronMan ironman = new IronMan();
        ironman.realName = "Tony Stark";
        // or


This is how we use the instance variables. Shameless plug: This example was pulled from this free e-book here here.

Powershell: Get FQDN Hostname


$env:computerName returns NetBIOS name of the host, so that both previous examples return netbioshostname.domainsuffix (not FQDN!) instead of dnshostname.domainsuffix (FQDN)

for example, host has FQDN and NetBIOS name aa-w2k12sv-stor (an easy case, I usually change NetBIOS name)

the hostname utility returns dnshostname, i.e., the first part of FQDN and code


returns the right FQDN

Comment: never use the same NetBIOS and DNS names of AD domains and hosts. If your or 3rd party application writes to the log: "cannot connect to hostname.domainsuffix", what name it tries to resolve? If you see in the log "cannot connect to netbiosname.domainsuffix", no doubt, a lazy programmer added domain suffix to the NetBIOS name and you are sure, this is a bug, and can open a ticket to force them to fix the issue...

What is the default access specifier in Java?

First of all let me say one thing there is no such term as "Access specifier" in java. We should call everything as "Modifiers". As we know that final, static, synchronised, volatile.... are called as modifiers, even Public, private, protected, default, abstract should also be called as modifiers . Default is such a modifiers where physical existence is not there but no modifiers is placed then it should be treated as default modifiers.

To justify this take one example:

public class Simple{  
    public static void main(String args[]){  
     System.out.println("Hello Java");  

Output will be: Hello Java

Now change public to private and see what compiler error you get: It says "Modifier private is not allowed here" What conclusion is someone can be wrong or some tutorial can be wrong but compiler cannot be wrong. So we can say there is no term access specifier in java everything is modifiers.

How to iterate over associative arrays in Bash

declare -a arr
echo "-------------------------------------"
echo "Here another example with arr numeric"
echo "-------------------------------------"
arr=( 10 200 3000 40000 500000 60 700 8000 90000 100000 )

echo -e "\n Elements in arr are:\n ${arr[0]} \n ${arr[1]} \n ${arr[2]} \n ${arr[3]} \n ${arr[4]} \n ${arr[5]} \n ${arr[6]} \n ${arr[7]} \n ${arr[8]} \n ${arr[9]}"

echo -e " \n Total elements in arr are : ${arr[*]} \n"

echo -e " \n Total lenght of arr is : ${#arr[@]} \n"

for (( i=0; i<10; i++ ))
do      echo "The value in position $i for arr is [ ${arr[i]} ]"

for (( j=0; j<10; j++ ))
do      echo "The length in element $j is ${#arr[j]}"

for z in "${!arr[@]}"
do      echo "The key ID is $z"

C# function to return array

public static ArtworkData[] GetDataRecords(int UsersID)
    ArtworkData[] Labels;
    Labels = new ArtworkData[3];

    return Labels;

This should work.

You only use the brackets when creating an array or accessing an array. Also, Array[] is returning an array of array. You need to return the typed array ArtworkData[].

Hibernate Auto Increment ID

Do it as follows :-

@GenericGenerator(name="kaugen" , strategy="increment")
  public Integer getId() {
    return id;

You can use any arbitrary name instead of kaugen. It worked well, I could see below queries on console

Hibernate: select max(proj_id) from javaproj
Hibernate: insert into javaproj (AUTH_email, AUTH_firstName, AUTH_lastName, projname,         proj_id) values (?, ?, ?, ?, ?)

Simple file write function in C++

Your main doesn't know about writeFile() and can't call it.

Move writefile to be before main, or declare a function prototype int writeFile(); before main.

How to exit from the application and show the home screen?

I did it with observer mode.

Observer interface

public interface Observer {
public void update(Subject subject);

Base Subject

public class Subject {
private List<Observer> observers = new ArrayList<Observer>();

public void attach(Observer observer){

public void detach(Observer observer){

protected void notifyObservers(){
    for(Observer observer : observers){

Child Subject implements the exit method

public class ApplicationSubject extends Subject {
public void exit(){

MyApplication which your application should extends it

public class MyApplication extends Application {

private static ApplicationSubject applicationSubject;

public ApplicationSubject getApplicationSubject() {
            if(applicationSubject == null) applicationSubject = new ApplicationSubject();
    return applicationSubject;


Base Activity

public abstract class BaseActivity extends Activity implements Observer {

public MyApplication app;

protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    app = (MyApplication) this.getApplication();

public void finish() {
    // TODO Auto-generated method stub

 * exit the app
public void close() {

public void update(Subject subject) {
    // TODO Auto-generated method stub


let's test it

public class ATestActivity extends BaseActivity {
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    close(); //invoke 'close'

Check key exist in python dict

Use the in keyword.

if 'apples' in d:
    if d['apples'] == 20:
        print('20 apples')
        print('Not 20 apples')

If you want to get the value only if the key exists (and avoid an exception trying to get it if it doesn't), then you can use the get function from a dictionary, passing an optional default value as the second argument (if you don't pass it it returns None instead):

if d.get('apples', 0) == 20:
    print('20 apples.')
    print('Not 20 apples.')

How do I get an empty array of any size in python?

If by "array" you actually mean a Python list, you can use

a = [0] * 10


a = [None] * 10

How to prettyprint a JSON file?

You could try pprintjson.


$ pip3 install pprintjson


Pretty print JSON from a file using the pprintjson CLI.

$ pprintjson "./path/to/file.json"

Pretty print JSON from a stdin using the pprintjson CLI.

$ echo '{ "a": 1, "b": "string", "c": true }' | pprintjson

Pretty print JSON from a string using the pprintjson CLI.

$ pprintjson -c '{ "a": 1, "b": "string", "c": true }'

Pretty print JSON from a string with an indent of 1.

$ pprintjson -c '{ "a": 1, "b": "string", "c": true }' -i 1

Pretty print JSON from a string and save output to a file output.json.

$ pprintjson -c '{ "a": 1, "b": "string", "c": true }' -o ./output.json


enter image description here

Is there a way to only install the mysql client (Linux)?

Maybe try this:

yum -y groupinstall "MYSQL Database Client"

Regular Expression usage with ls

You don't say what shell you are using, but they generally don't support regular expressions that way, although there are common *nix CLI tools (grep, sed, etc) that do.

What shells like bash do support is globbing, which uses some similiar characters (eg, *) but is not the same thing.

Newer versions of bash do have a regular expression operator, =~:

for x in `ls`; do 
    if [[ $x =~ .+\..* ]]; then 
        echo $x; 

JPA Query.getResultList() - use in a generic way

I had the same problem and a simple solution that I found was:

List<Object[]> results = query.getResultList();
for (Object[] result: results) {
    SomeClass something = (SomeClass)result[1];

I know this is defenitly not the most elegant solution nor is it best practice but it works, at least for me.

JPA or JDBC, how are they different?

Main difference between JPA and JDBC is level of abstraction.

JDBC is a low level standard for interaction with databases. JPA is higher level standard for the same purpose. JPA allows you to use an object model in your application which can make your life much easier. JDBC allows you to do more things with the Database directly, but it requires more attention. Some tasks can not be solved efficiently using JPA, but may be solved more efficiently with JDBC.

How to add native library to "java.library.path" with Eclipse launch (instead of overriding it)

The native library file name has to correspond to the Jar file name. This is very very important. Please make sure that jar name and dll name are same. Also,please see the post from Fabian Steeg My download for jawin was containing different names for dll and jar. It was jawin.jar and jawind.dll, note extra 'd' in dll file name. I simply renamed it to jawin.dll and set it as a native library in eclipse as mentioned in post ""

Access host database from a docker container

Use host.docker.internal from Docker 18.03 onwards.

sudo echo "something" >> /etc/privilegedFile doesn't work

echo 'Hello World' | (sudo tee -a /etc/apt/sources.list)

Only allow Numbers in input Tag without Javascript

Of course, you can't fully rely on the client-side (javascript) validation, but that's not a reason to avoid it completely. With or without it, you have to do the server-side validation anyway (since the client can disable javascript). And that's just what you're left with, due to your non-javascript solution constraint.

So, after a submit, if the field value doesn't pass the server-side validation, the client should end up on the very same page, with additional error message specifying the requested value format. You also should provide the value format information beforehands, e.g. as a tool-tip hint (title attribute).

There's most certainly no passive client-side validation mechanism existing in HTML 4 / XHTML.

On the other hand, in HTML 5 you have two options:

  • input of type number:

    <input type="number" min="xxx" max="yyy" title="Format: 3 digits" />

    – only validates the range – if user enters a non-number, an empty value is submitted
    – the field visual is enhanced with increment / decrement controls (browser dependent)

  • the pattern attribute:

    <input type="text" pattern="[0-9]{3}" title="Format: 3 digits" />
    <input type="text" pattern="\d{3}" title="Format: 3 digits" />

    – this gives you a full contorl over the format (anything you can specify by regular expression)
    – no visual difference / enhancement

But here you still rely on browser capabilities, so do a server-side validation in either case.

How to find what code is run by a button or element in Chrome using Developer Tools

This solution needs the jQuery's data method.

  1. Open Chrome's console (although any browser with jQuery loaded will work)
  2. Run $._data($(".example").get(0), "events")
  3. Drill down the output to find the desired event handler.
  4. Right-click on "handler" and select "Show function definition"
  5. The code will be shown in the Sources tab

$._data() is just accessing jQuery's data method. A more readable alternative could be jQuery._data().

Interesting point by this SO answer:

As of jQuery 1.8, the event data is no longer available from the "public API" for data. Read this jQuery blog post. You should now use this instead:

jQuery._data( elem, "events" ); elem should be an HTML Element, not a jQuery object, or selector.

Please note, that this is an internal, 'private' structure, and shouldn't be modified. Use this for debugging purposes only.

In older versions of jQuery, you might have to use the old method which is:

jQuery( elem ).data( "events" );

A version agnostic jQuery would be: (jQuery._data ||, 'events');

Error: Tablespace for table xxx exists. Please DISCARD the tablespace before IMPORT

Thank you #DangerDave this solved my problem on Magento 2, and this is how I did

I am on a vps

root@myvps [~]# cd /var/lib/mysql/mydatabasename/

root@myvps [~]# ls

check for tables with no .frm fie (only .idb) and delete them,

rm customer_grid_flat.ibd

System will regenerate tables after running index:reindex command

Jquery - Uncaught TypeError: Cannot use 'in' operator to search for '324' in

In my case, I forgot to tell the type controller that the response is a JSON object. response.setContentType("application/json");

List all environment variables from the command line

Simply run set from cmd.

Displays, sets, or removes environment variables. Used without parameters, set displays the current environment settings.

Select * from subquery

You can select every column from that sub-query by aliasing it and adding the alias before the *:

SELECT t.*, a+b AS total_sum
   SELECT SUM(column1) AS a, SUM(column2) AS b
   FROM table
) t

Show just the current branch in Git

This is not shorter, but it deals with detached branches as well:

git branch | awk -v FS=' ' '/\*/{print $NF}' | sed 's|[()]||g'

How to move an element down a litte bit in html

.row-2 UL LI A
  margin-top: 10px;  /* or whatever amount you need it to move down */

Add new row to dataframe, at specific row-index, not appended?

for example you want to add rows of variable 2 to variable 1 of a data named "edges" just do it like this

allEdges <- data.frame(c(edges$V1,edges$V2))

How do I check (at runtime) if one class is a subclass of another?

You can use the builtin issubclass. But type checking is usually seen as unneccessary because you can use duck-typing.

CSS fill remaining width

This can be achieved by wrapping the image and search bar in their own container and floating the image to the left with a specific width.

This takes the image out of the "flow" which means that any items rendered in normal flow will not adjust their positioning to take account of this.

To make the "in flow" searchBar appear correctly positioned to the right of the image you give it a left padding equal to the width of the image plus a gutter.

The effect is to make the image a fixed width while the rest of the container block is fluidly filled up by the search bar.

<div class="container">
  <img src="img/logo.png"/>
  <div id="searchBar">
    <input type="text" />

and the css

.container {
  width: 100%;

.container img {
  width: 50px;
  float: left;

.searchBar {
  padding-left: 60px;

How to select an item in a ListView programmatically?

I know this is an old question, but I think this is the definitive answer.

listViewRamos.Items[i].Focused = true;
listViewRamos.Items[i].Selected = true;

If there is a chance the control does not have the focus but you want to force the focus to the control, then you can add the following line.


Why Microsoft didn't just add a SelectItem() method that does all this for you is beyond me.

Best way to initialize (empty) array in PHP

In PHP an array is an array; there is no primitive vs. object consideration, so there is no comparable optimization to be had.

Set focus and cursor to end of text input field / string w. Jquery

You can do this using Input.setSelectionRange, part of the Range API for interacting with text selections and the text cursor:

var searchInput = $('#Search');

// Multiply by 2 to ensure the cursor always ends up at the end;
// Opera sometimes sees a carriage return as 2 characters.
var strLength = searchInput.val().length * 2;

searchInput[0].setSelectionRange(strLength, strLength);

Demo: Fiddle

How do I create and store md5 passwords in mysql

Why don't you use the MySQL built in password hasher:

mysql> SELECT PASSWORD('mypass');
| PASSWORD('mypass')                        |
| *6C8989366EAF75BB670AD8EA7A7FC1176A95CEF4 |

for comparison you could something like this:

select id from PassworTable where Userid='<userid>' and Password=PASSWORD('<password>')

and if it returns a value then the user is correct.

Python datetime strptime() and strftime(): how to preserve the timezone information

Part of the problem here is that the strings usually used to represent timezones are not actually unique. "EST" only means "America/New_York" to people in North America. This is a limitation in the C time API, and the Python solution is… to add full tz features in some future version any day now, if anyone is willing to write the PEP.

You can format and parse a timezone as an offset, but that loses daylight savings/summer time information (e.g., you can't distinguish "America/Phoenix" from "America/Los_Angeles" in the summer). You can format a timezone as a 3-letter abbreviation, but you can't parse it back from that.

If you want something that's fuzzy and ambiguous but usually what you want, you need a third-party library like dateutil.

If you want something that's actually unambiguous, just append the actual tz name to the local datetime string yourself, and split it back off on the other end:

d ="America/New_York"))
dtz_string = d.strftime(fmt) + ' ' + "America/New_York"

d_string, tz_string = dtz_string.rsplit(' ', 1)
d2 = datetime.datetime.strptime(d_string, fmt)
tz2 = pytz.timezone(tz_string)

print dtz_string 
print d2.strftime(fmt) + ' ' + tz_string

Or… halfway between those two, you're already using the pytz library, which can parse (according to some arbitrary but well-defined disambiguation rules) formats like "EST". So, if you really want to, you can leave the %Z in on the formatting side, then pull it off and parse it with pytz.timezone() before passing the rest to strptime.

Android draw a Horizontal line between views

Try this


Long vs Integer, long vs int, what to use and when?

When it comes to using a very long number that may exceed 32 bits to represent, you may use long to make sure that you'll not have strange behavior.

From Java 5 you can use in-boxing and out-boxing features to make the use of int and Integer completely the same. It means that you can do :

int myInt = new Integer(11);
Integer myInt2 = myInt;

The in and out boxing allow you to switch between int and Integer without any additional conversion (same for Long,Double,Short too)

You may use int all the time, but Integer contains some helper methods that can help you to do some complex operations with integers (such as Integer.parseInt(String) )

How to pass arguments to Shell Script through docker run

Use the same

echo $1

Build the image using the existing Dockerfile:

docker build -t test .

Run the image with arguments abc or xyz or something else.

docker run -ti --rm test / abc

docker run -ti --rm test / xyz

How to refresh or show immediately in datagridview after inserting?

I don't know if you resolved your problem, but a simple way to resolve this is rebuilding the DataSource (it is a property) of your datagridview. For example:

grdPatient.DataSource = MethodThatReturnList();

So, in that MethodThatReturnList() you can build a List (List is a class) with all the items you need. In my case, I have a method that return the values for two columns that I have on my datagridview.


What's the difference between a POST and a PUT HTTP REQUEST?

  1. GET: Retrieves data from the server. Should have no other effect.
  2. PUT: Replaces target resource with the request payload. Can be used to update or create a new resources.
  3. PATCH: Similar to PUT, but used to update only certain fields within an existing resource.
  4. POST: Performs resource-specific processing on the payload. Can be used for different actions including creating a new resource, uploading a file or submitting a web form.
  5. DELETE: Removes data from the server.
  6. TRACE: Provides a way to test what server receives. It simply returns what was sent.
  7. OPTIONS: Allows a client to get information about the request methods supported by a service. The relevant response header is Allow with supported methods. Also used in CORS as preflight request to inform server about actual request method and ask about custom headers.
  8. HEAD: Returns only the response headers.
  9. CONNECT: Used by browser when it knows it talks to a proxy and the final URI begins with https://. The intent of CONNECT is to allow end-to-end encrypted TLS session, so the data is unreadable to a proxy.

HttpClient not supporting PostAsJsonAsync method C#

If you're playing around in Blazor and get the error, you need to add the package Microsoft.AspNetCore.Blazor.HttpClient.

How to run multiple .BAT files within a .BAT file

With correct quoting (this can be tricky sometimes):

start "" /D "C:\Program Files\ProgramToLaunch" "cmd.exe" "/c call ""C:\Program Files\ProgramToLaunch\programname.bat"""

1st arg - Title (empty in this case)
2nd arg - /D specifies starting directory, can be ommited if want the current working dir (such as "%~dp0")
3rd arg - command to launch, "cmd.exe"
4th arg - arguments to command, with doubled up quotes for the arguments inside it (this is how you escape quotes within quotes in batch)

Pip - Fatal error in launcher: Unable to create process using '"'

run this python code:

import pip
pip.main(['install','flask']) # replace flask with the name of module you want to install

If you need to install multiple modules from a requirements.txt file,

import pip
fo = open("C:/...../requirements.txt", "r")
inp =
ls =inp.split()     

for i in ls:

Test if remote TCP port is open from a shell script

While an old question, I've just dealt with a variant of it, but none of the solutions here were applicable, so I found another, and am adding it for posterity. Yes, I know the OP said they were aware of this option and it didn't suit them, but for anyone following afterwards it might prove useful.

In my case, I want to test for the availability of a local apt-cacher-ng service from a docker build. That means absolutely nothing can be installed prior to the test. No nc, nmap, expect, telnet or python. perl however is present, along with the core libraries, so I used this:

perl -MIO::Socket::INET -e 'exit(! defined( IO::Socket::INET->new("")))'

Apache shows PHP code instead of executing it

open the file


and change

#LoadModule php5_module libexec/apache2/


LoadModule php5_module libexec/apache2/

So just uncoment the PHP module load in httpd.conf

PHP Curl And Cookies

Solutions which are described above, even with unique CookieFile names, can cause a lot of problems on scale.

We had to serve a lot of authentications with this solution and our server went down because of high file read write actions.

The solution for this was to use Apache Reverse Proxy and omit CURL requests at all.

Details how to use Proxy on Apache can be found here:

CSS blur on background image but not on content


Unfortunately Mozilla has really dropped the ball and taken it's time with the feature. I'm personally hoping it makes it in to the next Firefox ESR as that is what the next major version of Waterfox will use.

MDN (Mozilla Developer Network) article:

Mozilla implementation:

From the MDN documentation page:

/* URL to SVG filter */
backdrop-filter: url(commonfilters.svg#filter);

/* <filter-function> values */
backdrop-filter: blur(2px);
backdrop-filter: brightness(60%);
backdrop-filter: contrast(40%);
backdrop-filter: drop-shadow(4px 4px 10px blue);
backdrop-filter: grayscale(30%);
backdrop-filter: hue-rotate(120deg);
backdrop-filter: invert(70%);
backdrop-filter: opacity(20%);
backdrop-filter: sepia(90%);
backdrop-filter: saturate(80%);

/* Multiple filters */
backdrop-filter: url(filters.svg#filter) blur(4px) saturate(150%);

Declaring a python function with an array parameters and passing an array argument to the function call?

What you have is on the right track.

def dosomething( thelist ):
    for element in thelist:
        print element

dosomething( ['1','2','3'] )
alist = ['red','green','blue']
dosomething( alist )  

Produces the output:


A couple of things to note given your comment above: unlike in C-family languages, you often don't need to bother with tracking the index while iterating over a list, unless the index itself is important. If you really do need the index, though, you can use enumerate(list) to get index,element pairs, rather than doing the x in range(len(thelist)) dance.

Schedule automatic daily upload with FileZilla

FileZilla does not have any command line arguments (nor any other way) that allow an automatic transfer.

Some references:

Though you can use any other client that allows automation.

You have not specified, what protocol you are using. FTP or SFTP? You will definitely be able to use WinSCP, as it supports all protocols that FileZilla does (and more).

Combine WinSCP scripting capabilities with Windows Scheduler:

A typical WinSCP script for upload (with SFTP) looks like:

open sftp://user:[email protected]/ -hostkey="ssh-rsa 2048 xxxxxxxxxxx...="
put c:\mypdfs\*.pdf /home/user/

With FTP, just replace the sftp:// with the ftp:// and remove the -hostkey="..." switch.

Similarly for download: How to schedule an automatic FTP download on Windows?

WinSCP can even generate a script from an imported FileZilla session.

For details, see the guide to FileZilla automation.

(I'm the author of WinSCP)

Another option, if you are using SFTP, is the psftp.exe client from PuTTY suite.

What is a file with extension .a?

.a files are static libraries typically generated by the archive tool. You usually include the header files associated with that static library and then link to the library when you are compiling.

HTTP 404 Page Not Found in Web Api hosted in IIS 7.5

Based on this SO answer, I just had to change path="*." to path="*" for the added ExtensionlessUrlHandler-Integrated-4.0 in configuration>system.WebServer>handlers in my web.config


<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />


<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*" verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />

How to set environment variable or system property in spring tests?

If you want your variables to be valid for all tests, you can have an file in your test resources directory (by default: src/test/resources) which will look something like this:


This will then be loaded and used unless you have definitions via @TestPropertySource or a similar method - the exact order in which properties are loaded can be found in the Spring documentation chapter 24. Externalized Configuration.

How is CountDownLatch used in Java Multithreading?

One good example of when to use something like this is with Java Simple Serial Connector, accessing serial ports. Typically you'll write something to the port, and asyncronously, on another thread, the device will respond on a SerialPortEventListener. Typically, you'll want to pause after writing to the port to wait for the response. Handling the thread locks for this scenario manually is extremely tricky, but using Countdownlatch is easy. Before you go thinking you can do it another way, be careful about race conditions you never thought of!!


CountDownLatch latch;
void writeData() { 
   latch = new CountDownLatch(1);
   try {
      latch.await(4, TimeUnit.SECONDS);
    } catch (InterruptedException e) {
class SerialPortReader implements SerialPortEventListener {
    public void serialEvent(SerialPortEvent event) {
        if(event.isRXCHAR()){//If data is available
            byte buffer[] = serialPort.readBytes(event.getEventValue());

How to ignore PKIX path building failed:

I also came across the same issue. I was trying to build the project with a clean install goal. I simply changed it to clean package -o in the run configuration. Then I re-built the project and it worked for me.

How to get integer values from a string in Python?

def function(string):  
    final = ''  
    for i in string:  
            final += str(int(i))   
        except ValueError:  
            return int(final)  
print(function("4983results should get"))  

How to bind a List<string> to a DataGridView control?

An alternate is to use a new helper function which will take values from List and update in the DataGridView as following:

    private void DisplayStringListInDataGrid(List<string> passedList, ref DataGridView gridToUpdate, string newColumnHeader)
        DataTable gridData = new DataTable();

        foreach (string listItem in passedList)

        BindingSource gridDataBinder = new BindingSource();
        gridDataBinder.DataSource = gridData;
        dgDataBeingProcessed.DataSource = gridDataBinder;

Then we can call this function the following way:

    DisplayStringListInDataGrid(<nameOfListWithStrings>, ref <nameOfDataGridViewToDisplay>, <nameToBeGivenForTheNewColumn>);

How to write a SQL DELETE statement with a SELECT statement in the WHERE clause?

Did something like that once:

CREATE TABLE exclusions(excl VARCHAR(250));
INSERT INTO exclusions(excl)
SELECT * FROM chunks
       WHERE chunks.file_id IN
       FROM LargeFiles lf
       WHERE lf.file_id NOT IN
             SELECT DISTINCT
             FROM LargeFiles lf
                LEFT JOIN exclusions e ON(lf.URL LIKE e.excl)
                WHERE e.excl IS NULL
SET @r = 1;
WHILE @r>0

    DELETE TOP (10000) FROM ToBeDeleted;
    SET @r = @@ROWCOUNT  

Convert double to BigDecimal and set BigDecimal Precision

BigDecimal b = new BigDecimal(c).setScale(2,BigDecimal.ROUND_HALF_UP);

How can I align button in Center or right using IONIC framework?

I Found the esiest soltuion just wrap the button with div and put text-center align-items-center in it like this :

<div text-center align-items-center>
<buttonion-button block class="button-design " text-center>Sign In </button>

Black transparent overlay on image hover with only CSS?

You were close. This will work:

.image { position: relative; border: 1px solid black; width: 200px; height: 200px; }
.image img { max-width: 100%; max-height: 100%; }
.overlay { position: absolute; top: 0; left: 0; right:0; bottom:0; display: none; background-color: rgba(0,0,0,0.5); }
.image:hover .overlay { display: block; }

You needed to put the :hover on image, and make the .overlay cover the whole image by adding right:0; and bottom:0.


Toggle button using two image on different state

AkashG's solution don't work for me. When I set up check.xml to background it's just stratched in vertical direction. To solve this problem you should set up check.xml to "android:button" property:

    android:button="@drawable/check"   //check.xml


<?xml version="1.0" encoding="utf-8"?>
    <selector xmlns:android="">
    <!-- When selected, use grey -->
    <item android:drawable="@drawable/selected_image"
          android:state_checked="true" />
    <!-- When not selected, use white-->
    <item android:drawable="@drawable/unselected_image"

How to replace a set of tokens in a Java String?

The most efficient way would be using a matcher to continually find the expressions and replace them, then append the text to a string builder:

Pattern pattern = Pattern.compile("\\[(.+?)\\]");
Matcher matcher = pattern.matcher(text);
HashMap<String,String> replacements = new HashMap<String,String>();
//populate the replacements map ...
StringBuilder builder = new StringBuilder();
int i = 0;
while (matcher.find()) {
    String replacement = replacements.get(;
    builder.append(text.substring(i, matcher.start()));
    if (replacement == null)
    i = matcher.end();
builder.append(text.substring(i, text.length()));
return builder.toString();

How does the compilation/linking process work?

GCC compiles a C/C++ program into executable in 4 steps.

For example, gcc -o hello hello.c is carried out as follows:

1. Pre-processing

Preprocessing via the GNU C Preprocessor (cpp.exe), which includes the headers (#include) and expands the macros (#define).

cpp hello.c > hello.i

The resultant intermediate file "hello.i" contains the expanded source code.

2. Compilation

The compiler compiles the pre-processed source code into assembly code for a specific processor.

gcc -S hello.i

The -S option specifies to produce assembly code, instead of object code. The resultant assembly file is "hello.s".

3. Assembly

The assembler (as.exe) converts the assembly code into machine code in the object file "hello.o".

as -o hello.o hello.s

4. Linker

Finally, the linker (ld.exe) links the object code with the library code to produce an executable file "hello".

    ld -o hello hello.o ...libraries...

How to find the size of a table in SQL?

SQL Server provides a built-in stored procedure that you can run to easily show the size of a table, including the size of the indexes… which might surprise you.


 sp_spaceused 'Tablename'

see in :

XPath to select Element by attribute value

Try doing this :


SQL query to get the deadlocks in SQL SERVER 2008

In order to capture deadlock graphs without using a trace (you don't need profiler necessarily), you can enable trace flag 1222. This will write deadlock information to the error log. However, the error log is textual, so you won't get nice deadlock graph pictures - you'll have to read the text of the deadlocks to figure it out.

I would set this as a startup trace flag (in which case you'll need to restart the service). However, you can run it only for the current running instance of the service (which won't require a restart, but which won't resume upon the next restart) using the following global trace flag command:

DBCC TRACEON(1222, -1);

A quick search yielded this tutorial:

Also note that if your system experiences a lot of deadlocks, this can really hammer your error log, and can become quite a lot of noise, drowning out other, important errors.

Have you considered third party monitoring tools? SQL Sentry Performance Advisor, for example, has a much nicer deadlock graph, showing you object / index names as well as the order in which the locks were taken. As a bonus, these are captured for you automatically on monitored servers without having to configure trace flags, run your own traces, etc.:

enter image description here

Disclaimer: I work for SQL Sentry.

How does one set up the Visual Studio Code compiler/debugger to GCC?

You need to install C compiler, C/C++ extension, configure launch.json and tasks.json to be able to debug C code.

This article would guide you how to do it:

Remove 'standalone="yes"' from generated XML

If you have <?xml version="1.0" encoding="UTF-8" standalone="yes"?>

but want this: <?xml version="1.0" encoding="UTF-8"?>

Just do:

marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);
marshaller.setProperty("com.sun.xml.internal.bind.xmlHeaders", "<?xml version=\"1.0\" encoding=\"UTF-8\"?>");

Conversion from byte array to base64 and back

The reason the encoded array is longer by about a quarter is that base-64 encoding uses only six bits out of every byte; that is its reason of existence - to encode arbitrary data, possibly with zeros and other non-printable characters, in a way suitable for exchange through ASCII-only channels, such as e-mail.

The way you get your original array back is by using Convert.FromBase64String:

 byte[] temp_backToBytes = Convert.FromBase64String(temp_inBase64);

How to fix IndexError: invalid index to scalar variable

In the for, you have an iteration, then for each element of that loop which probably is a scalar, has no index. When each element is an empty array, single variable, or scalar and not a list or array you cannot use indices.

How do I increase the scrollback buffer in a running screen session?

WARNING: setting this value too high may cause your system to experience a significant hiccup. The higher the value you set, the more virtual memory is allocated to the screen process when initiating the screen session. I set my ~/.screenrc to "defscrollback 123456789" and when I initiated a screen, my entire system froze up for a good 10 minutes before coming back to the point that I was able to kill the screen process (which was consuming 16.6GB of VIRT mem by then).

How to solve error message: "Failed to map the path '/'."

These samples run in server. So either the Windows user must have READ/WRITE permissions or must run the sample in Administrator mode.

Try running the sample in Administrator mode.

Script to get the HTTP status code of a list of urls?

wget --spider -S "http://url/to/be/checked" 2>&1 | grep "HTTP/" | awk '{print $2}'

prints only the status code for you

How to iterate over the file in python

The traceback indicates that probably you have an empty line at the end of the file. You can fix it like this:

f = open('test.txt','r')
g = open('test1.txt','w') 
while True:
    x = f.readline()
    x = x.rstrip()
    if not x: break
    print >> g, int(x, 16)

On the other hand it would be better to use for x in f instead of readline. Do not forget to close your files or better to use with that close them for you:

with open('test.txt','r') as f:
    with open('test1.txt','w') as g: 
        for x in f:
            x = x.rstrip()
            if not x: continue
            print >> g, int(x, 16)

Format a JavaScript string using placeholders and an object of substitutions?

If you want to do something closer to console.log like replacing %s placeholders like in

>console.log("Hello %s how are you %s is everything %s?", "Loreto", "today", "allright")
>Hello Loreto how are you today is everything allright?

I wrote this

function log() {_x000D_
  var args =;_x000D_
  var rep= args.slice(1, args.length);_x000D_
  var i=0;_x000D_
  var output = args[0].replace(/%s/g, function(match,idx) {_x000D_
    var subst=rep.slice(i, ++i);_x000D_
    return( subst );_x000D_
res=log("Hello %s how are you %s is everything %s?", "Loreto", "today", "allright");_x000D_
<span id="console"/>

you will get

>log("Hello %s how are you %s is everything %s?", "Loreto", "today", "allright")
>"Hello Loreto how are you today is everything allright?"


I have added a simple variant as String.prototype useful when dealing with string transformations, here is it:

String.prototype.log = function() {
    var args =;
    var rep= args.slice(0, args.length);
    var i=0;
    var output = this.replace(/%s|%d|%f|%@/g, function(match,idx) {
      var subst=rep.slice(i, ++i);
      return( subst );
    return output;

In that case you will do

"Hello %s how are you %s is everything %s?".log("Loreto", "today", "allright")
"Hello Loreto how are you today is everything allright?"

Try this version here

Change Name of Import in Java, or import two classes with the same name

Java doesn't allow you to do that. You'll need to refer to one of the classes by its fully qualified name and only import the other one.

How to form a correct MySQL connection string?

Here is an example:

MySqlConnection con = new MySqlConnection(

MySqlCommand cmd = new MySqlCommand(
    " INSERT Into Test (lat, long) VALUES ('"+OSGconv.deciLat+"','"+
    OSGconv.deciLon+"')", con);


Simple proof that GUID is not unique

GUIDs are 124 bits because 4 bits hold the version number.

How to change the Content of a <textarea> with JavaScript

Like this:

document.getElementById('myTextarea').value = '';

or like this in jQuery:


Where you have

<textarea id="myTextarea" name="something">This text gets removed</textarea>

For all the downvoters and non-believers:

Convert int to string?

string str = intVar.ToString();

In some conditions, you do not have to use ToString()

string str = "hi " + intVar;

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



The Array.prototype.includes() method determines whether an array includes a certain value among its entries, returning true or false as appropriate.


Object.keys() returns an array of strings that represent all the enumerable properties of the given object.

.hasOwnProperty() and the ES6+ .? -optional-chaining like: if (x?.y) are very good 2020+ options as well.

How to get a list of all files that changed between two Git commits?

  • To list all unstaged tracked changed files:

    git diff --name-only
  • To list all staged tracked changed files:

    git diff --name-only --staged
  • To list all staged and unstaged tracked changed files:

    { git diff --name-only ; git diff --name-only --staged ; } | sort | uniq
  • To list all untracked files (the ones listed by git status, so not including any ignored files):

    git ls-files --other --exclude-standard

If you're using this in a shell script, and you want to programmatically check if these commands returned anything, you'll be interested in git diff's --exit-code option.

How can I see the request headers made by curl when sending a request to the server?

Here is my http client in php to make post queries with cookies included:

function http_login_client($url, $params = "", $cookies_send = "" ){

    // Vars
    $cookies = array();
    $headers = getallheaders();

    // Perform a http post request to $ur1 using $params
    $ch = curl_init($url);
    $options = array(   CURLOPT_POST => 1,
                        CURLINFO_HEADER_OUT => true,
                        CURLOPT_POSTFIELDS => $params,
                        CURLOPT_RETURNTRANSFER => 1,
                        CURLOPT_HEADER => 1,
                        CURLOPT_COOKIE => $cookies_send,
                        CURLOPT_USERAGENT => $headers['User-Agent']

    curl_setopt_array($ch, $options);

    $response = curl_exec($ch);

/// DEBUG info echo $response; var_dump (curl_getinfo($ch)); ///

    // Parse response and read cookies
    preg_match_all('/^Set-Cookie: (.*?)=(.*?);/m', $response, $matches);

    // Build an array with cookies
    foreach( $matches[1] as $index => $cookie )
        $cookies[$cookie] = $matches[2][$index];

    return $cookies;
} // end http_login_client

What is the meaning of the word logits in TensorFlow?

Logits often are the values of Z function of the output layer in Tensorflow.

Convert unsigned int to signed int C

It seems like you are expecting int and unsigned int to be a 16-bit integer. That's apparently not the case. Most likely, it's a 32-bit integer - which is large enough to avoid the wrap-around that you're expecting.

Note that there is no fully C-compliant way to do this because casting between signed/unsigned for values out of range is implementation-defined. But this will still work in most cases:

unsigned int x = 65529;
int y = (short) x;      //  If short is a 16-bit integer.

or alternatively:

unsigned int x = 65529;
int y = (int16_t) x;    //  This is defined in <stdint.h>

Bootstrap Carousel image doesn't align properly

I faced the same problem and solved it this way: It's possible to insert non-image content to Carousel, so we can use it. You should first insert div.inner-item (where you will make center alignment), and then insert image inside this div.

Here is my code (Ruby):

<div id="myCarousel" class="carousel slide">
    <!-- Carousel items -->
    <div class="carousel-inner">
        <div class="active item">
            <%= image_tag "couples/1.jpg" %>
        <% (2..55).each do |t|%>
            <div class="item">
                <div class='inner-item'>
                    <%= image_tag "couples/#{t}.jpg" %>
        <% end -%>
    <!-- Carousel nav -->
    <a class="carousel-control left" href="#myCarousel" data-slide="prev">&lsaquo;</a>
    <a class="carousel-control right" href="#myCarousel" data-slide="next">&rsaquo;</a>

And my css-code(.scss):

.inner-item {
    text-align: center;
    img {
        margin: 0 auto;

Default value for field in Django model

You can set the default like this:

b = models.CharField(max_length=7,default="foobar")

and then you can hide the field with your model's Admin class like this:

class SomeModelAdmin(admin.ModelAdmin):
    exclude = ("b")

Daylight saving time and time zone best practices

For PHP:

The DateTimeZone class in PHP > 5.2 is already based on the Olson DB which others mention, so if you are doing timezone conversions in PHP and not in the DB, you are exempt of working with (the hard-to-understand) Olson files.

However, PHP is not updated as frequently as the Olson DB, so just using PHPs time zone conversions may leave you with outdated DST information and influence the correctness of your data. While this is not expected to happen frequently, it may happen, and will happen if you have a large base of users worldwide.

To cope with the above issue, use the timezonedb pecl package. Its function is to update PHP's timezone data. Install this package as frequently as it is updated. (I'm not sure if the updates to this package follow Olson updates exactly, but it seems to be updated at a frequency which is at least very close to the frequency of Olson updates.)

How to sanity check a date in Java

Key is df.setLenient(false);. This is more than enough for simple cases. If you are looking for a more robust (I doubt) and/or alternate libraries like joda-time then look at the answer by the user "tardate"

final static String DATE_FORMAT = "dd-MM-yyyy";

public static boolean isDateValid(String date) 
        try {
            DateFormat df = new SimpleDateFormat(DATE_FORMAT);
            return true;
        } catch (ParseException e) {
            return false;

How to Lock the data in a cell in excel using vba

You can first choose which cells you don't want to be protected (to be user-editable) by setting the Locked status of them to False:

Worksheets("Sheet1").Range("B2:C3").Locked = False

Then, you can protect the sheet, and all the other cells will be protected. The code to do this, and still allow your VBA code to modify the cells is:

Worksheets("Sheet1").Protect UserInterfaceOnly:=True


Call Worksheets("Sheet1").Protect(UserInterfaceOnly:=True)

Putting GridView data in a DataTable

user this full solution to convert gridview to datatable

 public DataTable gridviewToDataTable(GridView gv)

            DataTable dtCalculate = new DataTable("TableCalculator");

            // Create Column 1: Date
            DataColumn dateColumn = new DataColumn();
            dateColumn.DataType = Type.GetType("System.DateTime");
            dateColumn.ColumnName = "date";

            // Create Column 3: TotalSales
            DataColumn loanBalanceColumn = new DataColumn();
            loanBalanceColumn.DataType = Type.GetType("System.Double");
            loanBalanceColumn.ColumnName = "loanbalance";

            DataColumn offsetBalanceColumn = new DataColumn();
            offsetBalanceColumn.DataType = Type.GetType("System.Double");
            offsetBalanceColumn.ColumnName = "offsetbalance";

            DataColumn netloanColumn = new DataColumn();
            netloanColumn.DataType = Type.GetType("System.Double");
            netloanColumn.ColumnName = "netloan";

            DataColumn interestratecolumn = new DataColumn();
            interestratecolumn.DataType = Type.GetType("System.Double");
            interestratecolumn.ColumnName = "interestrate";

            DataColumn interestrateperdaycolumn = new DataColumn();
            interestrateperdaycolumn.DataType = Type.GetType("System.Double");
            interestrateperdaycolumn.ColumnName = "interestrateperday";

            // Add the columns to the ProductSalesData DataTable

            foreach (GridViewRow row in gv.Rows)
                DataRow dr;
                dr = dtCalculate.NewRow();

                dr["date"] = DateTime.Parse(row.Cells[0].Text);
                dr["loanbalance"] = double.Parse(row.Cells[1].Text);
                dr["offsetbalance"] = double.Parse(row.Cells[2].Text);
                dr["netloan"] = double.Parse(row.Cells[3].Text);
                dr["interestrate"] = double.Parse(row.Cells[4].Text);
                dr["interestrateperday"] = double.Parse(row.Cells[5].Text);


            return dtCalculate;

LINQ query to select top five

This can also be achieved using the Lambda based approach of Linq;

var list = ctn.Items
.Where(t=> t.DeliverySelection == true && t.Delivery.SentForDelivery == null)
.OrderBy(t => t.Delivery.SubmissionDate)

Find what 2 numbers add to something and multiply to something

Come on guys, there is no need to loop, just use simple math to solve this equation system:

a*b = i;

a+b = j;

a = j/b;

a = i-b;

j/b = i-b; so:

b + j/b + i = 0

b^2 + i*b + j = 0

From here, its a quadratic equation, and it's trivial to find b (just implement the quadratic equation formula) and from there get the value for a.


There you go:

function finder($add,$product)

 $inside_root = $add*$add - 4*$product;

 if($inside_root >=0)

     $b = ($add + sqrt($inside_root))/2;
     $a = $add - $b;

     echo "$a+$b = $add and $a*$b=$product\n";

   echo "No real solution\n";

Real live action:

Run task only if host does not belong to a group

Here's another way to do this:

- name: my command
  command: echo stuff
  when: "'groupname' not in group_names"

group_names is a magic variable as documented here: :

group_names is a list (array) of all the groups the current host is in.

How to Free Inode Usage?

It's quite easy for a disk to have a large number of inodes used even if the disk is not very full.

An inode is allocated to a file so, if you have gazillions of files, all 1 byte each, you'll run out of inodes long before you run out of disk.

It's also possible that deleting files will not reduce the inode count if the files have multiple hard links. As I said, inodes belong to the file, not the directory entry. If a file has two directory entries linked to it, deleting one will not free the inode.

Additionally, you can delete a directory entry but, if a running process still has the file open, the inode won't be freed.

My initial advice would be to delete all the files you can, then reboot the box to ensure no processes are left holding the files open.

If you do that and you still have a problem, let us know.

By the way, if you're looking for the directories that contain lots of files, this script may help:

# count_em - count files in all subdirectories under current directory.
echo 'echo $(ls -a "$1" | wc -l) $1' >/tmp/count_em_$$
chmod 700 /tmp/count_em_$$
find . -mount -type d -print0 | xargs -0 -n1 /tmp/count_em_$$ | sort -n
rm -f /tmp/count_em_$$

How do I trim() a string in angularjs?

I insert this code in my tag and it works correctly:

ng-show="!Contract.BuyerName.trim()" >

How do I merge changes to a single file, rather than merging commits?

The following command will (1) compare the file of the correct branch, to master (2) interactively ask you which modifications to apply.

git checkout --patch master

What is the difference between typeof and instanceof and when should one be used vs. the other?


typeof is faster than instanceof in situations where both are applicable.

Depending on your engine, the performance difference in favor of typeof could be around 20%. (Your mileage may vary)

Here is a benchmark testing for Array:

var subject = new Array();
var iterations = 10000000;

var goBenchmark = function(callback, iterations) {
    var start =;
    for (i=0; i < iterations; i++) { var foo = callback(); }
    var end =;
    var seconds = parseFloat((end-start)/1000).toFixed(2);
    console.log(" took: "+ seconds +" seconds.");
    return seconds;

// Testing instanceof
var iot = goBenchmark(function instanceofTest(){
     (subject instanceof Array);
}, iterations);

// Testing typeof
var tot = goBenchmark(function typeofTest(){
     (typeof subject == "object");
}, iterations);

var r = new Array(iot,tot).sort();
console.log("Performance ratio is: "+ parseFloat(r[1]/r[0]).toFixed(3));


instanceofTest took: 9.98 seconds.
typeofTest took: 8.33 seconds.
Performance ratio is: 1.198

Set Locale programmatically

As of 2020 language management become easy! All you have to do is:

  1. Call to Activity.applyOverrideConfiguration
  2. And call to Locale.setDefault

You must call those from the activity constructor since you can call to applyOverrideConfiguration only once, and the system calls it pretty early.

And watch out from app-bundles, Google will split your APK by language resources automatically when using app-bundles. Check out the new API and the workaround here.

I created a helper class to help you with it. In my implementation is the application context. Also, I need to access resources from the app context so I use the Res class for it, this one is optional, but I provide its code as well.


public BaseActivity(){

public void changeLanguage(Local local){
    // you must recreat your activity after you call this
    LanguageUtillity.setDefaultLanguage(local, this);

Source code

public class LanguageUtility {

    private static Configuration configuration;

    public static void setDefaultLanguage(Locale locale, Context context) {

        context.getSharedPreferences("LocaleSettings", Context.MODE_PRIVATE)
                .putString("language", locale.getLanguage())
                .putString("country", locale.getCountry())
                .putString("variant", locale.getVariant())

        configuration = createConfiguration(context);

     * Used to update your app context in case you cache it.
    public static Context createConfigurationContext(Context context) {
        return context.createConfigurationContext(getConfiguration(context));

    public static void init(Activity activity) {
        // you can't access sharedPrefferences from activity constructor 
        // with activity context, so I used the app context.

    private static Configuration getConfiguration(Context context) {
        if (configuration == null) {
            configuration = createConfiguration(context);
        return configuration;

    private static Configuration createConfiguration(Context context) {
        Locale locale = getLocale(context);
        Configuration configuration = new Configuration();
        LanguageUtility.configuration = configuration;
        return configuration;

    private static Locale getLocale(Context context) {
        Locale aDefault = Locale.getDefault();
        SharedPreferences preferences =
                context.getSharedPreferences("LocaleSettings", Context.MODE_PRIVATE);
        String language = preferences.getString("language", aDefault.getLanguage());
        String country = preferences.getString("country", aDefault.getCountry());
        String variant = preferences.getString("variant", aDefault.getVariant());
        return new Locale(language, country, variant);

An optional Res class.

public class Res {

    public static Context appLocalContext = LanguageUtility.createConfigurationContext(;

    public static void updateContext() {
        appLocalContext = LanguageUtility.createConfigurationContext(;

    public static String getString(@StringRes int id, Object... formatArgs) {
        return appLocalContext.getResources().getString(id, formatArgs);

    public static int getColor(@ColorRes int id) {

Oracle JDBC ojdbc6 Jar as a Maven Dependency

Below config worked for me. Refer this link for more details.


Eclipse error: "Editor does not contain a main type"

Did you import the packages for the file reading stuff.


also here

cfiltering(numberOfUsers, numberOfMovies);

Are you trying to create an object or calling a method?

also another thing:


you are assigning a value to a member of an instance as if it was a static variable also remove the Th in

private int user_movie_matrix[][];Th

Hope this helps.

Wpf control size to content?

I had a user control which sat on page in a free form way, not constrained by another container, and the contents within the user control would not auto size but expand to the full size of what the user control was handed.

To get the user control to simply size to its content, for height only, I placed it into a grid with on row set to auto size such as this:

<Grid Margin="0,60,10,200">
        <RowDefinition Height="Auto" />
    <controls1:HelpPanel x:Name="HelpInfoPanel"
                         ItemsSource="{Binding HelpItems}"
                         Background="#FF313131" />

close fxml window by code, javafx

  1. give your close button an fx:id, if you haven't yet: <Button fx:id="closeButton" onAction="#closeButtonAction">
  2. In your controller class:

    @FXML private javafx.scene.control.Button closeButton;
    private void closeButtonAction(){
        // get a handle to the stage
        Stage stage = (Stage) closeButton.getScene().getWindow();
        // do what you have to do

Position Relative vs Absolute?

Absolute CSS Positioning

position: absolute;

Absolute positioning is the easiest to understand. You start with the CSS position property:

position: absolute;

This tells the browser that whatever is going to be positioned should be removed from the normal flow of the document and will be placed in an exact location on the page. It won't affect how the elements before it or after it in the HTML are positioned on the Web page however it will be subject to it's parents' positioning unless you override it.

If you want to position an element 10 pixels from the top of the document window, you would use the top offset to position it there with absolute positioning:

position: absolute;
top: 10px;

This element will then always display 10px from the top of the page regardless of what content passes through, under or over the element (visually).

The four positioning properties are:

  1. top
  2. right
  3. bottom
  4. left

To use them, you need to think of them as offset properties. In other words, an element positioned right: 2px is not moved right 2px. It's right side is offset from the right side of the window (or its position overriding parent) by 2px. The same is true for the other three.

Relative Positioning

position: relative;

Relative positioning uses the same four positioning properties as absolute positioning. But instead of basing the position of the element upon the browser view port, it starts from where the element would be if it were still in the normal flow.

For example, if you have three paragraphs on your Web page, and the third has a position: relative style placed on it, its position will be offset based on its current location-- not from the original sides of the view port.

Paragraph 1.

Paragraph 2.

Paragraph 3.

In the above example, the third paragraph will be positioned 3em from the left side of the container element, but will still be below the first two paragraphs. It would remain in the normal flow of the document, and just be offset slightly. If you changed it to position: absolute;, anything following it would display on top of it, because it would no longer be in the normal flow of the document.


  • the default width of an element that is absolutely positioned is the width of the content within it, unlike an element that is relatively positioned where it's default width is 100% of the space it can fill.

  • You can have elements that overlap with absolutely positioned elements, whereas you cannot do this with relatively positioned elements (natively i.e without the use of negative margins/positioning)

lots pulled from: this resource

performSelector may cause a leak because its selector is unknown


The compiler is warning about this for a reason. It's very rare that this warning should simply be ignored, and it's easy to work around. Here's how:

if (!_controller) { return; }
SEL selector = NSSelectorFromString(@"someMethod");
IMP imp = [_controller methodForSelector:selector];
void (*func)(id, SEL) = (void *)imp;
func(_controller, selector);

Or more tersely (though hard to read & without the guard):

SEL selector = NSSelectorFromString(@"someMethod");
((void (*)(id, SEL))[_controller methodForSelector:selector])(_controller, selector);


What's going on here is you're asking the controller for the C function pointer for the method corresponding to the controller. All NSObjects respond to methodForSelector:, but you can also use class_getMethodImplementation in the Objective-C runtime (useful if you only have a protocol reference, like id<SomeProto>). These function pointers are called IMPs, and are simple typedefed function pointers (id (*IMP)(id, SEL, ...))1. This may be close to the actual method signature of the method, but will not always match exactly.

Once you have the IMP, you need to cast it to a function pointer that includes all of the details that ARC needs (including the two implicit hidden arguments self and _cmd of every Objective-C method call). This is handled in the third line (the (void *) on the right hand side simply tells the compiler that you know what you're doing and not to generate a warning since the pointer types don't match).

Finally, you call the function pointer2.

Complex Example

When the selector takes arguments or returns a value, you'll have to change things a bit:

SEL selector = NSSelectorFromString(@"processRegion:ofView:");
IMP imp = [_controller methodForSelector:selector];
CGRect (*func)(id, SEL, CGRect, UIView *) = (void *)imp;
CGRect result = _controller ?
  func(_controller, selector, someRect, someView) : CGRectZero;

Reasoning for Warning

The reason for this warning is that with ARC, the runtime needs to know what to do with the result of the method you're calling. The result could be anything: void, int, char, NSString *, id, etc. ARC normally gets this information from the header of the object type you're working with.3

There are really only 4 things that ARC would consider for the return value:4

  1. Ignore non-object types (void, int, etc)
  2. Retain object value, then release when it is no longer used (standard assumption)
  3. Release new object values when no longer used (methods in the init/ copy family or attributed with ns_returns_retained)
  4. Do nothing & assume returned object value will be valid in local scope (until inner most release pool is drained, attributed with ns_returns_autoreleased)

The call to methodForSelector: assumes that the return value of the method it's calling is an object, but does not retain/release it. So you could end up creating a leak if your object is supposed to be released as in #3 above (that is, the method you're calling returns a new object).

For selectors you're trying to call that return void or other non-objects, you could enable compiler features to ignore the warning, but it may be dangerous. I've seen Clang go through a few iterations of how it handles return values that aren't assigned to local variables. There's no reason that with ARC enabled that it can't retain and release the object value that's returned from methodForSelector: even though you don't want to use it. From the compiler's perspective, it is an object after all. That means that if the method you're calling, someMethod, is returning a non object (including void), you could end up with a garbage pointer value being retained/released and crash.

Additional Arguments

One consideration is that this is the same warning will occur with performSelector:withObject: and you could run into similar problems with not declaring how that method consumes parameters. ARC allows for declaring consumed parameters, and if the method consumes the parameter, you'll probably eventually send a message to a zombie and crash. There are ways to work around this with bridged casting, but really it'd be better to simply use the IMP and function pointer methodology above. Since consumed parameters are rarely an issue, this isn't likely to come up.

Static Selectors

Interestingly, the compiler will not complain about selectors declared statically:

[_controller performSelector:@selector(someMethod)];

The reason for this is because the compiler actually is able to record all of the information about the selector and the object during compilation. It doesn't need to make any assumptions about anything. (I checked this a year a so ago by looking at the source, but don't have a reference right now.)


In trying to think of a situation where suppression of this warning would be necessary and good code design, I'm coming up blank. Someone please share if they have had an experience where silencing this warning was necessary (and the above doesn't handle things properly).


It's possible to build up an NSMethodInvocation to handle this as well, but doing so requires a lot more typing and is also slower, so there's little reason to do it.


When the performSelector: family of methods was first added to Objective-C, ARC did not exist. While creating ARC, Apple decided that a warning should be generated for these methods as a way of guiding developers toward using other means to explicitly define how memory should be handled when sending arbitrary messages via a named selector. In Objective-C, developers are able to do this by using C style casts on raw function pointers.

With the introduction of Swift, Apple has documented the performSelector: family of methods as "inherently unsafe" and they are not available to Swift.

Over time, we have seen this progression:

  1. Early versions of Objective-C allow performSelector: (manual memory management)
  2. Objective-C with ARC warns for use of performSelector:
  3. Swift does not have access to performSelector: and documents these methods as "inherently unsafe"

The idea of sending messages based on a named selector is not, however, an "inherently unsafe" feature. This idea has been used successfully for a long time in Objective-C as well as many other programming languages.

1 All Objective-C methods have two hidden arguments, self and _cmd that are implicitly added when you call a method.

2 Calling a NULL function is not safe in C. The guard used to check for the presence of the controller ensures that we have an object. We therefore know we'll get an IMP from methodForSelector: (though it may be _objc_msgForward, entry into the message forwarding system). Basically, with the guard in place, we know we have a function to call.

3 Actually, it's possible for it to get the wrong info if declare you objects as id and you're not importing all headers. You could end up with crashes in code that the compiler thinks is fine. This is very rare, but could happen. Usually you'll just get a warning that it doesn't know which of two method signatures to choose from.

4 See the ARC reference on retained return values and unretained return values for more details.

How to initialize all members of an array to the same value?

Cutting through all the chatter, the short answer is that if you turn on optimization at compile time you won't do better than this:

int i,value=5,array[1000]; 
for(i=0;i<1000;i++) array[i]=value; 

Added bonus: the code is actually legible :)

pdftk compression option

In case you want to compress a PDF which contains a lot of selectable text, on Windows you can use NicePDF Compressor - choose "Flate" option. After trying everything (cpdf, pdftk, gs) it finally helped me to compress my 1360 pages PDF from 500 MB down to 10 MB.

Right mime type for SVG images with fonts embedded

There's only one registered mediatype for SVG, and that's the one you listed, image/svg+xml. You can of course serve SVG as XML too, though browsers tend to behave differently in some scenarios if you do, for example I've seen cases where SVG used in CSS backgrounds fail to display unless served with the image/svg+xml mediatype.

How to make an Android Spinner with initial text "Select One"?

None of the previously submitted answers really worked the way I wanted to solve this issue. To me the ideal solution would provide the “Select One” (or whatever initial text) when the spinner is first displayed. When the user taps the spinner, the initial text shouldn’t be a part of the drop down that is displayed.

To further complicate my particular situation, my spinner data is coming form a cursor that is loaded via the LoaderManager callbacks.

After considerable experimentation I came up with the following solution:

public class MyFragment extends Fragment implements

private static final String SPINNER_INIT_VALUE = "Select A Widget";
private Spinner mSpinner;
private int mSpinnerPosition;
private boolean mSpinnerDropDownShowing = false;
private View mSpinnerDropDown;

private MyCursorAdapter mCursorAdapter;


public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){

mCursorAdapter = new MyCursorAdapter(getActivity());

mSpinner = (Spinner) rootView.findViewById(;


//Capture the touch events to toggle the spinner's dropdown visibility
private OnTouchListener mSpinnerTouchListener = new View.OnTouchListener() {
    public boolean onTouch(View view, MotionEvent motionEvent) {
        if(mSpinnerDropDown != null && mSpinnerDropDownShowing == false){
            mSpinnerDropDownShowing = true;
        return false;

//Capture the click event on the spinner drop down items
protected OnClickListener spinnerItemClick = new OnClickListener(){

    public void onClick(View view) {
        String widget = ((TextView) view.findViewById(;

            if(mCursorAdapter != null){
                Cursor cursor = mCursorAdapter.getCursor();


                            //Set the spinner to the correct item
                            mSpinnerPosition = cursor.getPosition() + 1;

        //Hide the drop down. Not the most elegent solution but it is the only way I could hide/dismiss the drop down
        mSpinnerDropDown = view.getRootView();
        mSpinnerDropDownShowing = false;

private class MyCursorAdapter extends CursorAdapter {

    private final int DISPLACEMENT = 1;
    private final int DEFAULT_ITEM_ID = Integer.MAX_VALUE;

    private Activity mActivity;

    public MyCursorAdapter(Activity activity) {
            super(activity, null, false);
            mActivity = activity;

    //When loading the regular views, inject the defualt item
    public View getView(int position, View convertView, ViewGroup parent) {
        if(position == 0){
            if(convertView == null){
                convertView = mActivity.getLayoutInflater().inflate(R.layout.list_item_widget, parent, false);
            return getDefaultItem(convertView);
        return super.getView(position - DISPLACEMENT, convertView, parent);

    //When loading the drop down views, set the onClickListener for each view
    public View getDropDownView(int position, View convertView, ViewGroup parent){
        View view = super.getDropDownView(position, convertView, parent);
        return view;

    //The special default item that is being injected
    private View getDefaultItem(View convertView){
        TextView text = (TextView) convertView.findViewById(;
        return convertView;

    public long getItemId(int position) {
        if (position == 0) {
            return DEFAULT_ITEM_ID;
        return super.getItemId(position - DISPLACEMENT);

    public boolean isEnabled(int position) {
        return position == 0 ? true : super.isEnabled(position - DISPLACEMENT);

    public int getViewTypeCount() {
        return super.getViewTypeCount() + DISPLACEMENT;

    public int getItemViewType(int position) {
        if (position == 0) {
            return super.getViewTypeCount();

        return super.getItemViewType(position - DISPLACEMENT);

    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return mActivity.getLayoutInflater().inflate(R.layout.list_item_widget, parent, false);

    public void bindView(View view, Context context, Cursor cursor){


        TextView text = (TextView) view.findViewById(;
        String WidgetName = cursor.getString(WidgetQuery.WIDGET_NAME);

Cordova app not displaying correctly on iPhone X (Simulator)

I'm developing cordova apps for 2 years and I spent weeks to solve related problems (eg: webview scrolls when keyboard open). Here's a tested and proven solution for both ios and android

P.S.: I'm using iScroll for scrolling content

  1. Never use viewport-fit=cover at index.html's meta tag, leave the app stay out of statusbar. iOS will handle proper area for all iPhone variants.
  2. In XCode uncheck hide status bar and requires full screen and don't forget to select Launch Screen File as CDVLaunchScreen
  3. In config.xml set fullscreen as false
  4. Finally, (thanks to Eddy Verbruggen for great plugins) add his plugin cordova-plugin-webviewcolor to set statusbar and bottom area background color. This plugin will allow you to set any color you want.
  5. Add below to config.xml (first ff after x is opacity)

    <preference name="BackgroundColor" value="0xff088c90" />
  6. Handle your scroll position yourself by adding focus events to input elements

    iscrollObj.scrollToElement(elm, transitionduration ... etc)

For android, do the same but instead of cordova-plugin-webviewcolor, install cordova-plugin-statusbar and cordova-plugin-navigationbar-color

Here's a javascript code using those plugins to work on both ios and android:

function setStatusColor(colorCode) {
    //colorCode is smtg like '#427309';
    if (cordova.platformId == 'android') {
    } else if (cordova.platformId == 'ios') {

How to delete node from XML file using C#

It may be easier to use XPath to locate the nodes that you wish to delete. This stackoverflow thread might give you some ideas.

In your case you will find the four nodes that you want using this expression:

XmlDocument doc = new XmlDocument();
XmlNodeList nodes = doc.SelectNodes("//Setting[@name='File1']");

Could not load file or assembly ... An attempt was made to load a program with an incorrect format (System.BadImageFormatException)

This also can happen just by having multiple supported frameworks defined in the app.config file and, forcing the app to run in a different .NET framework other than the one mentioned first in the app.config file.

And also this fires when you have both of the mentioned frameworks available in your system.

As a workaround, bring up the target framework you are going to use for the debugging up in the app.config

ex: if you trying to run in .NET 4, config file should have something similar to this,

<supportedRuntime version="v4.0"/>
<supportedRuntime version="v2.0.50727"/>