Programs & Examples On #Sshfs

SSHFS (Secure Shell File System) is a file system client to mount and interact with directories and files located on a remote server or workstation. The client interacts with the remote file system via the SSH File Transfer Protocol (SFTP), a network protocol providing file access, file transfer, and file management functionality over any reliable data stream that was designed as an extension of the Secure Shell protocol (SSH) version 2.0.

Unmount the directory which is mounted by sshfs in Mac

At least in 10.11 (El Capitan), the man page for umount indicates:

Due to the complex and interwoven nature of Mac OS X, umount may fail often. It is recommended that diskutil(1) (as in, "diskutil unmount /mnt") be used instead.

This approach (e.g., "diskutil umount path/to/mount/point") allows me to unmount sshfs-mounted content, and does not require sudo. (And I believe that it should work back through at least 10.8.)

GIT_DISCOVERY_ACROSS_FILESYSTEM problem when working with terminal and MacFusion

Try a different protocol. git:// may have problems from your firewall, for example; try a git clone with https: instead.

How do I trim a file extension from a String in Java?

public static String removeExtension(String file) {
    if(file != null && file.length() > 0) {
        while(file.contains(".")) {
            file = file.substring(0, file.lastIndexOf('.'));
    return file;

Why SpringMVC Request method 'GET' not supported?

method = POST will work if you 'post' a form to the url /test.

if you type a url in address bar of a browser and hit enter, it's always a GET request, so you had to specify POST request.

Google for HTTP GET and HTTP POST (there are several others like PUT DELETE). They all have their own meaning.

"No resource identifier found for attribute 'showAsAction' in package 'android'"

Add compat library compilation to the build.gradle file:

compile ''

BATCH file asks for file or folder

Actually xcopy does not ask you if the original file exists, but if you want to put it in a new folder named Shapes.atc, or in the folder Support (which is what you want.

To prevent xcopy from asking this, just tell him the destination folder, so there's no ambiguity:

xcopy /s/y "J:\Old path\Shapes.atc" "C:\Documents and Settings\his name\Support"

If you want to change the filename in destination just use copy (which is more adapted than xcopy when copying files):

copy /y "J:\Old path\Shapes.atc" "C:\Documents and Settings\his name\Support\Shapes-new.atc

Eclipse Generate Javadoc Wizard: what is "Javadoc Command"?

Had this problem and solved typing this : C:\Program Files (x86)\Java\jdk1.7.0_51\bin\javadoc.exe

Installing packages in Sublime Text 2

With Package Control in Sublime Text 2, you really need to become cozy with a couple of different things to make it all work:

  1. Always look up a package in the wbond community. There you'll be able to see how many people have installed that package (the more popular, the better) as well as the documentation on the package (if any).
  2. Menu Items under Prefs > Package Control. Here you can install, remove or see a list of all installed packages.
  3. Prefs > Package Settings. Here you'll find the settings that can be tinkered with as well as shortcut keys that are available. Make sure to make any changes in the User Settings, rather than the Default Settings. Otherwise, your settings will be overwritten when that package is updated.
  4. CTRL+SHIFT+P. This will bring up a menu where you can look up a lot of the functions your installed packages can do. Just start typing and it will start filtering.

Private vs Protected - Visibility Good-Practice Concern

Well it is all about encapsulation if the paybill classes handles billing of payment then in product class why would it needs the whole process of billing process i.e payment method how to pay where to pay .. so only letting what are used for other classes and objects nothing more than that public for those where other classes would use too, protected for those limit only for extending classes. As you are madara uchiha the private is like "limboo" you can see it (you class only single class).

How do I open multiple instances of Visual Studio Code?

You can open multiple windows (from the menu or by running the code executable again).

However, unfortunately there seems to be no way to actually have separate instances at the moment. For example, if you have two shells open with different environments in each (different paths, etc.), launching code for both will result in the second window sharing the same paths as the first, and ignoring the environment it was launched from.

Extension gd is missing from your system - laravel composer Update

Open your php.ini and uncomment this line:


Uncaught Typeerror: cannot read property 'innerHTML' of null

var idPost=document.getElementById("status").innerHTML;

The 'status' element does not exist in your webpage.

So document.getElementById("status") return null. While you can not use innerHTML property of NULL.

You should add a condition like this:

if(document.getElementById("status") != null){
    var idPost=document.getElementById("status").innerHTML;

Hope this answer can help you. :)

Trusting all certificates with okHttp

Update OkHttp 3.0, the getAcceptedIssuers() function must return an empty array instead of null.

What are the differences between LinearLayout, RelativeLayout, and AbsoluteLayout?

LinearLayout - In LinearLayout, views are organized either in vertical or horizontal orientation.

RelativeLayout - RelativeLayout is way more complex than LinearLayout, hence provides much more functionalities. Views are placed, as the name suggests, relative to each other.

FrameLayout - It behaves as a single object and its child views are overlapped over each other. FrameLayout takes the size of as per the biggest child element.

Coordinator Layout - This is the most powerful ViewGroup introduced in Android support library. It behaves as FrameLayout and has a lot of functionalities to coordinate amongst its child views, for example, floating button and snackbar, Toolbar with scrollable view.

Select row and element in awk

To expand on Dennis's answer, use awk's -v option to pass the i and j values:

# print the j'th field of the i'th line
awk -v i=5 -v j=3 'FNR == i {print $j}'

What's the difference between SCSS and Sass?

The Sass .sass file is visually different from .scss file, e.g.

Example.sass - sass is the older syntax

$color: red

  border: 1px solid $color

  background: $color

Example.scss - sassy css is the new syntax as of Sass 3

$color: red;

@mixin my-border($color) {
  border: 1px solid $color;

body {
  background: $color;
  @include my-border(green);

Any valid CSS document can be converted to Sassy CSS (SCSS) simply by changing the extension from .css to .scss.

Rewrite URL after redirecting 404 error htaccess

Try this in your .htaccess:


ErrorDocument 404
ErrorDocument 500
# or map them to one error document:
# ErrorDocument 404 /pages/errors/error_redirect.php
# ErrorDocument 500 /pages/errors/error_redirect.php

RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_URI} ^/404/$
RewriteRule ^(.*)$ /pages/errors/404.php [L]

RewriteCond %{REQUEST_URI} ^/500/$
RewriteRule ^(.*)$ /pages/errors/500.php [L]

# or map them to one error document:
#RewriteCond %{REQUEST_URI} ^/404/$ [OR]
#RewriteCond %{REQUEST_URI} ^/500/$
#RewriteRule ^(.*)$ /pages/errors/error_redirect.php [L]

The ErrorDocument redirects all 404s to a specific URL, all 500s to another url (replace with your domain).

The Rewrite rules map that URL to your actual 404.php script. The RewriteCond regular expressions can be made more generic if you want, but I think you have to explicitly define all ErrorDocument codes you want to override.

Local Redirect:

Change .htaccess ErrorDocument to a file that exists (must exist, or you'll get an error):

ErrorDocument 404 /pages/errors/404_redirect.php


   header('Location: /404/');

Redirect based on error number

Looks like you'll need to specify an ErrorDocument line in .htaccess for every error you want to redirect (see: Apache ErrorDocument and Apache Custom Error). The .htaccess example above has multiple examples in it. You can use the following as the generic redirect script to replace 404_redirect.php above.


   $error_url = $_SERVER["REDIRECT_STATUS"] . '/';
   $error_path = $error_url . '.php';

   if ( ! file_exists($error_path)) {
      // this is the default error if a specific error page is not found
      $error_url = '404/';

   header('Location: ' . $error_url);

How to manually include external aar package using new Gradle Android Build System

you can do something like this:

  1. Put your local libraries (with extension: .jar, .aar, ...) into 'libs' Folder (or another if you want).

  2. In build.gradle (app level), add this line into dependences

    implementation fileTree(include: ['*.jar', '*.aar'], dir: 'libs')

How to check the gradle version in Android Studio?

File->Project Structure->Project pane->"Android plugin version".

Make sure you don't confuse the Gradle version with the Android plugin version. The former is the build system itself, the latter is the plugin to the build system that knows how to build Android projects

How do I change a tab background color when using TabLayout?

As I found best and suitable option for me and it will work with animation too.

You can use indicator it self as a background.

You can set app:tabIndicatorGravity="stretch" attribute to use as background.



            android:text="Chef" />

            android:text="User" />


Hope it will helps you.

What's the easiest way to call a function every 5 seconds in jQuery?

You don't need jquery for this, in plain javascript, the following will work!

var intervalId = window.setInterval(function(){
  /// call your function here
}, 5000);

To stop the loop you can use


C# : Passing a Generic Object

You're missing at least a couple of things:

  • Unless you're using reflection, the type arguments need to be known at compile-time, so you can't use


    ... although in this case you don't need to anyway

  • PrintGeneric doesn't know anything about T at the moment, so the compiler can't find a member called T


  • Put a property in the ITest interface, and change PrintGeneric to constrain T:

    public void PrintGeneric<T>(T test) where T : ITest
        Console.WriteLine("Generic : " + test.PropertyFromInterface);
  • Put a property in the ITest interface and remove the generics entirely:

    public void PrintGeneric(ITest test)
        Console.WriteLine("Property : " + test.PropertyFromInterface);
  • Use dynamic typing instead of generics if you're using C# 4

Is there a way to detect if a browser window is not currently active?

This is an adaptation of the answer from Andy E.

This will do a task e.g. refresh the page every 30 seconds, but only if the page is visible and focused.

If visibility can't be detected, then only focus will be used.

If the user focuses the page, then it will update immediately

The page won't update again until 30 seconds after any ajax call

var windowFocused = true;
var timeOut2 = null;

  $.ajaxSetup ({
    cache: false
  $("#content").ajaxComplete(function(event,request, settings){
       set_refresh_page(); // ajax call has just been made, so page doesn't need updating again for 30 seconds
  // check visibility and focus of window, so as not to keep updating unnecessarily
  (function() {
      var hidden, change, vis = {
              hidden: "visibilitychange",
              mozHidden: "mozvisibilitychange",
              webkitHidden: "webkitvisibilitychange",
              msHidden: "msvisibilitychange",
              oHidden: "ovisibilitychange" /* not currently supported */
      for (hidden in vis) {
          if (vis.hasOwnProperty(hidden) && hidden in document) {
              change = vis[hidden];
      if (change){     // this will check the tab visibility instead of window focus
          document.addEventListener(change, onchange,false);

      if(navigator.appName == "Microsoft Internet Explorer")
         window.onfocus = document.onfocusin = document.onfocusout = onchangeFocus
         window.onfocus = window.onblur = onchangeFocus;

      function onchangeFocus(evt){
        evt = evt || window.event;
        if (evt.type == "focus" || evt.type == "focusin"){
        else if (evt.type == "blur" || evt.type == "focusout"){
        if (evt.type == "focus"){
          update_page();  // only update using window.onfocus, because document.onfocusin can trigger on every click


      function onchange () {
        document.body.className = this[hidden] ? "hidden" : "visible";

      function update_page(){


function get_date_time_string(){
  var d = new Date();
  var dT = [];
  return dT.join('_');

function do_refresh_page(){

// do tasks here

// e.g. some ajax call to update part of the page.

// (date time parameter will probably force the server not to cache)

//      $.ajax({
//        type: "POST",
//        url: "someUrl.php",
//        data: "t=" + get_date_time_string()+"&task=update",
//        success: function(html){
//          $('#content').html(html);
//        }
//      });


function set_refresh_page(interval){
  interval = typeof interval !== 'undefined' ? interval : 30000; // default time = 30 seconds
  if(timeOut2 != null) clearTimeout(timeOut2);
  timeOut2 = setTimeout(function(){
  }, interval);

Controlling number of decimal digits in print output in R

If you are producing the entire output yourself, you can use sprintf(), e.g.

> sprintf("%.10f",0.25)
[1] "0.2500000000"

specifies that you want to format a floating point number with ten decimal points (in %.10f the f is for float and the .10 specifies ten decimal points).

I don't know of any way of forcing R's higher level functions to print an exact number of digits.

Displaying 100 digits does not make sense if you are printing R's usual numbers, since the best accuracy you can get using 64-bit doubles is around 16 decimal digits (look at .Machine$double.eps on your system). The remaining digits will just be junk.

Java: Convert String to TimeStamp

Follow these steps for a correct result:

try {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss.SSS");
    Date parsedDate = dateFormat.parse(yourString);
    Timestamp timestamp = new java.sql.Timestamp(parsedDate.getTime());
} catch(Exception e) { //this generic but you can control another types of exception
    // look the origin of excption 

Please note that .parse(String) might throw a ParseException.

Get selected option text with JavaScript

I just copy all "select list", you can see demo from following image.gif link.

see demo now

I love "select/option" css style and javascript tricks...

try it now....

/***javascript code***/
  document.querySelector("#mySelect").addEventListener("click", () => {
    var x = document.querySelector("#mySelect").selectedIndex;
    let optionText = document.getElementsByTagName("option")[x].innerText;
    document.querySelector(".nav-search-label").innerText = optionText;
  .nav-left {
    display: -webkit-box;
    display: -moz-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    position: static;
    float: none;
  .nav-search-scope {
    display: -webkit-box;
    display: -moz-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    position: relative;
    float: none;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
  .nav-search-facade {
    position: relative;
    float: left;
    cursor: default;
    overflow: hidden;
    top: 3px;
  .nav-search-label {
    display: block;
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
    color: #555;
    font-size: 12px;
    line-height: 33px;
    margin-right: 21px;
    margin-left: 5px;
    min-width: 19px;
  .nav-icon {
    position: absolute;
    top: 14px;
    right: 8px;
    border-style: solid;
    _border-style: dashed;
    border-width: 4px;
    border-color: transparent;
    border-top: 4px solid #666;
    border-bottom-width: 0;
    width: 0;
    height: 0;
    font-size: 0;
    line-height: 0;
  .nav-search-dropdown {
    position: absolute;
    display: block;
    top: -1px;
    left: 0;
    height: 35px;
    width: auto;
    font-family: inherit;
    outline: 0;
    margin: 0;
    padding: 0;
    cursor: pointer;
    opacity: 0;
    filter: alpha(opacity=0);
    visibility: visible;
    border: 0;
    line-height: 35px;
<!--html code-->
<div class="nav-left">
  <div id="nav-search-dropdown-card">
    <div class="nav-search-scope nav-sprite">
      <div class="nav-search-facade">
        <span class="nav-search-label" style="width: auto">All</span>
        <i class="nav-icon"></i>

        class="nav-search-dropdown searchSelect"
        style="display: block; top: 3px"
        title="Search in"
        <option>All Departments</option>
        <option>Arts &amp; Crafts</option>
        <option>Beauty &amp; Personal Care</option>
        <option>Digital Music</option>
        <option>Kindle Store</option>
        <option>Prime Video</option>
        <option>Women's Fashion</option>
        <option>Men's Fashion</option>
        <option>Girls' Fashion</option>
        <option>Boys' Fashion</option>
        <option>Health &amp; Household</option>
        <option>Home &amp; Kitchen</option>
        <option>Industrial &amp; Scientific</option>
        <option>Movies &amp; TV</option>
        <option>Music, CDs &amp; Vinyl</option>
        <option>Pet Supplies</option>
        <option>Sports &amp; Outdoors</option>
        <option>Tools &amp; Home Improvement</option>
        <option>Toys &amp; Games</option>
        <option>Video Games</option>

DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled

Try setting the definer for the function!

So instead of

CREATE FUNCTION get_pet_owner

you will write something akin to

CREATE DEFINER=procadmin@% FUNCTION get_pet_owner

which ought to work if the user prodacmin has rights to create functions/procedures.

In my case the function worked when generated through MySQL Workbench but did not work when run directly as an SQL script. Making the changes above fixed the problem.

Using python's mock patch.object to change the return value of a method called within another method

There are two ways you can do this; with patch and with patch.object

Patch assumes that you are not directly importing the object but that it is being used by the object you are testing as in the following
def some_fn():
    return 'some_fn'

class Foo(object):
    def method_1(self):
        return some_fn()
import foo
class Bar(object):
    def method_2(self):
        tmp = foo.Foo()
        return tmp.method_1()
import bar
from mock import patch

def test_bar(mock_some_fn):
    mock_some_fn.return_value = 'test-val-1'
    tmp = bar.Bar()
    assert tmp.method_2() == 'test-val-1'
    mock_some_fn.return_value = 'test-val-2'
    assert tmp.method_2() == 'test-val-2'

If you are directly importing the module to be tested, you can use patch.object as follows:
import foo
from mock import patch

@patch.object(foo, 'some_fn')
def test_foo(test_some_fn):
    test_some_fn.return_value = 'test-val-1'
    tmp = foo.Foo()
    assert tmp.method_1() == 'test-val-1'
    test_some_fn.return_value = 'test-val-2'
    assert tmp.method_1() == 'test-val-2'

In both cases some_fn will be 'un-mocked' after the test function is complete.

Edit: In order to mock multiple functions, just add more decorators to the function and add arguments to take in the extra parameters

@patch.object(foo, 'some_fn')
@patch.object(foo, 'other_fn')
def test_foo(test_other_fn, test_some_fn):

Note that the closer the decorator is to the function definition, the earlier it is in the parameter list.

Python Set Comprehension

You can generate pairs like this:

{(x, x + 2) for x in r if x + 2 in r}

Then all that is left to do is to get a condition to make them prime, which you have already done in the first example.

A different way of doing it: (Although slower for large sets of primes)

{(x, y) for x in r for y in r if x + 2 == y}

The client and server cannot communicate, because they do not possess a common algorithm - ASP.NET C# IIS TLS 1.0 / 1.1 / 1.2 - Win32Exception

My app is running in .net 4.7.2. Simplest solution was to add this to the config:

    <httpRuntime targetFramework="4.7.2"/>

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

The Saxon documentation, though a little unclear, seems to suggest that the JAXP XPath API will return false when evaluating an XPath expression if no matching nodes are found.

This IBM article mentions a return value of null when no nodes are matched.

You might need to play around with the return types a bit based on this API, but the basic idea is that you just run a normal XPath and check whether the result is a node / false / null / etc.

XPathFactory xpathFactory = XPathFactory.newInstance(NamespaceConstant.OBJECT_MODEL_SAXON);
XPath xpath = xpathFactory.newXPath();
XPathExpression expr = xpath.compile("/Consumers/Consumer/DataSources/Credit/CreditReport/AttachedXml");
Object result = expr.evaluate(doc, XPathConstants.NODE);

if ( result == null ) {
    // do something

Ways to implement data versioning in MongoDB

I have used the below package for a meteor/MongoDB project, and it works well, the main advantage is that it stores history/revisions within an array in the same document, hence no need for an additional publications or middleware to access change-history. It can support a limited number of previous versions (ex. last ten versions), it also supports change-concatenation (so all changes happened within a specific period will be covered by one revision).


Another sound option is to use Meteor Vermongo (here)

How to force keyboard with numbers in mobile website in Android

Some browsers igoners sending leading zero to the server when the input type is "number". So I use a mixing of jquery and html to load a numeric keypad and also make sure that the value is sent as a text not as a number:

<script src=""></script>_x000D_
<input type="text" class="numberonly">

How create table only using <div> tag and Css

A bit OFF-TOPIC, but may help someone for a cleaner HTML... CSS

    border:1px solid grey;
.common_table DIV{
    border:1px solid grey;
.common_table DIV DIV{


<DIV class="common_table">
   <DIV><DIV>this is a cell</DIV></DIV>
   <DIV><DIV>this is a cell</DIV></DIV>

Works on Chrome and Firefox

Laravel Eloquent - distinct() and count() not working properly together

Anyone else come across this post, and not finding the other suggestions to work?

Depending on the specific query, a different approach may be needed. In my case, I needed either count the results of a GROUP BY, e.g.




After some puzzling around, I realised there was no built-in Laravel function for either of these. So the simplest solution was to use use DB::raw with the count method.

$count = $builder->count(DB::raw('DISTINCT b'));

Remember, don't use groupBy before calling count. You can apply groupBy later, if you need it for getting rows.

Sass - Converting Hex to RGBa for background opacity

If you need to mix colour from variable and alpha transparency, and with solutions that include rgba() function you get an error like

      background-color: rgba(#{$color}, 0.3);
      $color: #002366 is not a color.
   ¦       background-color: rgba(#{$color}, 0.3);
   ¦                         ^^^^^^^^^^^^^^^^^^^^

Something like this might be useful.

$meeting-room-colors: (
  Neumann: '#002366',
  Turing: '#FF0000',
  Lovelace: '#00BFFF',
  Shared: '#00FF00',
  Chilling: '#FF1493',
$color-alpha: EE;

@each $name, $color in $meeting-room-colors {

  .#{$name} {

     background-color: #{$color}#{$color-alpha};



Run react-native application on iOS device directly from command line?

The following worked for me (tested on react native 0.38 and 0.40):

npm install -g ios-deploy
# Run on a connected device, e.g. Max's iPhone:
react-native run-ios --device "Max's iPhone"

If you try to run run-ios, you will see that the script recommends to do npm install -g ios-deploy when it reach install step after building.

While the documentation on the various commands that react-native offers is a little sketchy, it is worth going to react-native/local-cli. There, you can see all the commands available and the code that they run - you can thus work out what switches are available for undocumented commands.

addEventListener for keydown on Canvas

Edit - This answer is a solution, but a much simpler and proper approach would be setting the tabindex attribute on the canvas element (as suggested by hobberwickey).

You can't focus a canvas element. A simple work around this, would be to make your "own" focus.

var lastDownTarget, canvas;
window.onload = function() {
    canvas = document.getElementById('canvas');

    document.addEventListener('mousedown', function(event) {
        lastDownTarget =;
    }, false);

    document.addEventListener('keydown', function(event) {
        if(lastDownTarget == canvas) {
    }, false);


Change window location Jquery

Assuming you want to change the url to another within the same domain, you can use this:

history.pushState('data', '', '');

Remove all subviews?

In order to remove all subviews Syntax :

- (void)makeObjectsPerformSelector:(SEL)aSelector;

Usage :

[self.View.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];

This method is present in NSArray.h file and uses NSArray(NSExtendedArray) interface

How to use Python's pip to download and keep the zipped files for a package?

pip install --download is deprecated. Starting from version 8.0.0 you should use pip download command:

 pip download <package-name>

Set Background cell color in PHPExcel


It's in the documentation, located here:

REST API Token-based Authentication

Let me seperate up everything and solve approach each problem in isolation:


For authentication, baseauth has the advantage that it is a mature solution on the protocol level. This means a lot of "might crop up later" problems are already solved for you. For example, with BaseAuth, user agents know the password is a password so they don't cache it.

Auth server load

If you dispense a token to the user instead of caching the authentication on your server, you are still doing the same thing: Caching authentication information. The only difference is that you are turning the responsibility for the caching to the user. This seems like unnecessary labor for the user with no gains, so I recommend to handle this transparently on your server as you suggested.

Transmission Security

If can use an SSL connection, that's all there is to it, the connection is secure*. To prevent accidental multiple execution, you can filter multiple urls or ask users to include a random component ("nonce") in the URL.

url = username:[email protected]/api/call/nonce

If that is not possible, and the transmitted information is not secret, I recommend securing the request with a hash, as you suggested in the token approach. Since the hash provides the security, you could instruct your users to provide the hash as the baseauth password. For improved robustness, I recommend using a random string instead of the timestamp as a "nonce" to prevent replay attacks (two legit requests could be made during the same second). Instead of providing seperate "shared secret" and "api key" fields, you can simply use the api key as shared secret, and then use a salt that doesn't change to prevent rainbow table attacks. The username field seems like a good place to put the nonce too, since it is part of the auth. So now you have a clean call like this:

nonce = generate_secure_password(length: 16);
one_time_key = nonce + '-' + sha1(nonce+salt+shared_key);
url = username:[email protected]/api/call

It is true that this is a bit laborious. This is because you aren't using a protocol level solution (like SSL). So it might be a good idea to provide some kind of SDK to users so at least they don't have to go through it themselves. If you need to do it this way, I find the security level appropriate (just-right-kill).

Secure secret storage

It depends who you are trying to thwart. If you are preventing people with access to the user's phone from using your REST service in the user's name, then it would be a good idea to find some kind of keyring API on the target OS and have the SDK (or the implementor) store the key there. If that's not possible, you can at least make it a bit harder to get the secret by encrypting it, and storing the encrypted data and the encryption key in seperate places.

If you are trying to keep other software vendors from getting your API key to prevent the development of alternate clients, only the encrypt-and-store-seperately approach almost works. This is whitebox crypto, and to date, no one has come up with a truly secure solution to problems of this class. The least you can do is still issue a single key for each user so you can ban abused keys.

(*) EDIT: SSL connections should no longer be considered secure without taking additional steps to verify them.

Command to list all files in a folder as well as sub-folders in windows

If you want to list folders and files like graphical directory tree, you should use tree command.

tree /f

There are various options for display format or ordering.

Check example output.

enter image description here

Answering late. Hope it help someone.

How do you change the formatting options in Visual Studio Code?

Same thing happened to me just now. I set prettier as the Default Formatter in Settings and it started working again. My Default Formatter was null.

To set VSCODE Default Formatter

File -> Preferences -> Settings (for Windows) Code -> Preferences -> Settings (for Mac)

Search for "Default Formatter". In the dropdown, prettier will show as esbenp.prettier-vscode.

VSCODE Editor Option

How can I find whitespace in a String?

You can use charAt() function to find out spaces in string.

 public class Test {
  public static void main(String args[]) {
   String fav="Hi Testing  12 3";
   int counter=0;
   for( int i=0; i<fav.length(); i++ ) {
    if(fav.charAt(i) == ' ' ) {
    System.out.println("Number of spaces "+ counter);
    //This will print Number of spaces 4

Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel

In Windows server 2012. Go to ISS -> Modules -> Remove the ServiceModel3-0.

What does cv::normalize(_src, dst, 0, 255, NORM_MINMAX, CV_8UC1);

When the normType is NORM_MINMAX, cv::normalize normalizes _src in such a way that the min value of dst is alpha and max value of dst is beta. cv::normalize does its magic using only scales and shifts (i.e. adding constants and multiplying by constants).

CV_8UC1 says how many channels dst has.

The documentation here is pretty clear:

What is the JUnit XML format specification that Hudson supports?

Good answers here on using python: (there are many ways to do it) Python unittests in Jenkins?

IMHO the best way is write python unittest tests and install pytest (something like 'yum install pytest') to get py.test installed. Then run tests like this: 'py.test --junitxml results.xml'. You can run any unittest python script and get jUnit xml results.

In jenkins build configuration Post-build actions Add a "Publish JUnit test result report" action with result.xml and any more test result files you produce.

how to set "camera position" for 3d plots using python/matplotlib?

By "camera position," it sounds like you want to adjust the elevation and the azimuth angle that you use to view the 3D plot. You can set this with ax.view_init. I've used the below script to first create the plot, then I determined a good elevation, or elev, from which to view my plot. I then adjusted the azimuth angle, or azim, to vary the full 360deg around my plot, saving the figure at each instance (and noting which azimuth angle as I saved the plot). For a more complicated camera pan, you can adjust both the elevation and angle to achieve the desired effect.

    from mpl_toolkits.mplot3d import Axes3D
    ax = Axes3D(fig)
    ax.scatter(xx,yy,zz, marker='o', s=20, c="goldenrod", alpha=0.6)
    for ii in xrange(0,360,1):
        ax.view_init(elev=10., azim=ii)
        savefig("movie%d.png" % ii)

Convert a Unicode string to an escaped ASCII string

Here is my current implementation:

public static class UnicodeStringExtensions
    public static string EncodeNonAsciiCharacters(this string value) {
        var bytes = Encoding.Unicode.GetBytes(value);
        var sb = StringBuilderCache.Acquire(value.Length);
        bool encodedsomething = false;
        for (int i = 0; i < bytes.Length; i += 2) {
            var c = BitConverter.ToUInt16(bytes, i);
            if ((c >= 0x20 && c <= 0x7f) || c == 0x0A || c == 0x0D) {
                sb.Append((char) c);
            } else {
                encodedsomething = true;
        if (!encodedsomething) {
            return value;
        return StringBuilderCache.GetStringAndRelease(sb);

    public static string DecodeEncodedNonAsciiCharacters(this string value)
      => Regex.Replace(value,/*language=regexp*/@"(?:\\u[a-fA-F0-9]{4})+", Decode);

    static readonly string[] Splitsequence = new [] { "\\u" };
    private static string Decode(Match m) {
        var bytes = m.Value.Split(Splitsequence, StringSplitOptions.RemoveEmptyEntries)
                .Select(s => ushort.Parse(s, NumberStyles.HexNumber)).SelectMany(BitConverter.GetBytes).ToArray();
        return Encoding.Unicode.GetString(bytes);

This passes a test:

public void TestBigUnicode() {
    var s = "\U00020000";
    var encoded = s.EncodeNonAsciiCharacters();
    var decoded = encoded.DecodeEncodedNonAsciiCharacters();
    Assert.Equals(s, decoded);

with the encoded value: "\ud840\udc00"

This implementation makes use of a StringBuilderCache (reference source link)

JQuery ajax call default timeout value

There doesn't seem to be a standardized default value. I have the feeling the default is 0, and the timeout event left totally dependent on browser and network settings.

For IE, there is a timeout property for XMLHTTPRequests here. It defaults to null, and it says the network stack is likely to be the first to time out (which will not generate an ontimeout event by the way).

Get SSID when WIFI is connected

For me it only worked when I set the permission on the phone itself (settings -> app permissions -> location always on).

How do I convert from int to Long in Java?

 //Suppose you have int and you wan to convert it to Long
 int i=78;
 //convert to Long
 Long l=Long.valueOf(i)

How to avoid mysql 'Deadlock found when trying to get lock; try restarting transaction'

In case someone is still struggling with this issue:

I faced similar issue where 2 requests were hitting the server at the same time. There was no situation like below:



So, I was puzzled why deadlock is happening.

Then I found that there was parent child relation ship between 2 tables because of foreign key. When I was inserting a record in child table, the transaction was acquiring a lock on parent table's row. Immediately after that I was trying to update the parent row which was triggering elevation of lock to EXCLUSIVE one. As 2nd concurrent transaction was already holding a SHARED lock, it was causing deadlock.

Refer to:

Replace or delete certain characters from filenames of all files in a folder

The PowerShell answers are good, but the Rename-Item command doesn't work in the same target directory unless ALL of your files have the unwanted character in them (fails if it finds duplicates).

If you're like me and had a mix of good names and bad names, try this script instead (will replace spaces with an underscore):

Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace(" ", "_") }

Unit Testing: DateTime.Now

You can change the class you are testing to use a Func<DateTime> which will be passed through it's constructor parameters, so when you create instance of the class in real code, you can pass () => DateTime.UtcNow to the Func<DateTime> parameter, and on the test, you can pass the time you wish to test.

For example:

    public void MyTestMethod()
        var instance = new MyClass(() => DateTime.MinValue);
        Assert.AreEqual(instance.MyMethod(), DateTime.MinValue);

    public void RealWorldInitialization()
        new MyClass(() => DateTime.UtcNow);

    class MyClass
        private readonly Func<DateTime> _utcTimeNow;

        public MyClass(Func<DateTime> UtcTimeNow)
            _utcTimeNow = UtcTimeNow;

        public DateTime MyMethod()
            return _utcTimeNow();

how to drop database in sqlite?

The concept of creating or dropping a database is not meaningful for an embedded database engine like SQLite. It only has meaning with a client-sever database system, such as used by MySQL or Postgres.

To create a new database, just do sqlite_open() or from the command line sqlite3 databasefilename.

To drop a database, delete the file.

Reference: sqlite - Unsupported SQL

What are libtool's .la file for?

I found very good explanation about .la files here

Summary (The way I understood): Because libtool deals with static and dynamic libraries internally (through --diable-shared or --disable-static) it creates a wrapper on the library files it builds. They are treated as binary library files with in libtool supported environment.

How do I write data to csv file in columns and rows from a list in python?

>>> import csv
>>> with open('test.csv', 'wb') as f:
...     wtr = csv.writer(f, delimiter= ' ')
...     wtr.writerows( [[1, 2], [2, 3], [4, 5]])
>>> with open('test.csv', 'r') as f:
...     for line in f:
...         print line,
1 2 <<=== Exactly what you said that you wanted.
2 3
4 5

To get it so that it can be loaded sensibly by Excel, you need to use a comma (the csv default) as the delimiter, unless you are in a locale (e.g. Europe) where you need a semicolon.

How do I keep a label centered in WinForms?

You will achive it with setting property Anchor: None.

How can I exclude $(this) from a jQuery selector?

You can also use the jQuery .siblings() method:


<div class="content">
  <a href="#">A</a>
  <a href="#">B</a>
  <a href="#">C</a>


$(".content").on('click', 'a', function(e) {

Working demo:

nodejs - How to read and output jpg image?

Two things to keep in mind Content-Type and the Encoding

1) What if the file is css

if (/.(css)$/.test(path)) {
  res.writeHead(200, {'Content-Type': 'text/css'}); 
  res.write(data, 'utf8');

2) What if the file is jpg/png

if (/.(jpg)$/.test(path)) {
  res.writeHead(200, {'Content-Type': 'image/jpg'});

Above one is just a sample code to explain the answer and not the exact code pattern.

How to limit google autocomplete results to City and Country only

I found a solution for myself

var acService = new google.maps.places.AutocompleteService();
var autocompleteItems = [];

    types: ['(regions)']
}, function(predictions) {
    predictions.forEach(function(prediction) {
        if (prediction.types.some(function(x) {
                return x === "country" || x === "administrative_area1" || x === "locality";
            })) {
            if (prediction.terms.length < 3) {

this solution only show city and country..

Implementing a Custom Error page on an ASP.Net website

Is it a spelling error in your closing tag ie:

</CustomErrors> instead of </CustomError>?

How to vertically center <div> inside the parent element with CSS?

divs can't be vertically aligned that way, you can however use margins or position:relative to modify its location.

Creating a REST API using PHP

In your example, it’s fine as it is: it’s simple and works. The only things I’d suggest are:

  1. validating the data POSTed
  2. make sure your API is sending the Content-Type header to tell the client to expect a JSON response:

    header('Content-Type: application/json');
    echo json_encode($response);

Other than that, an API is something that takes an input and provides an output. It’s possible to “over-engineer” things, in that you make things more complicated that need be.

If you wanted to go down the route of controllers and models, then read up on the MVC pattern and work out how your domain objects fit into it. Looking at the above example, I can see maybe a MathController with an add() action/method.

There are a few starting point projects for RESTful APIs on GitHub that are worth a look.

jQuery toggle CSS?

You can do by maintaining the state as below:

    if($(this).attr('data-click-state') == 1) {
        $(this).attr('data-click-state', 0);
        $(this).css('background-color', 'red')
    else {
      $(this).attr('data-click-state', 1);
      $(this).css('background-color', 'orange')

Take a reference from hear codepen example

Select option padding not working in chrome

This simple hack will indent the text. Works well.

select {
  text-indent: 5px;

How do I raise an exception in Rails so it behaves like other Rails exceptions?

You can do it like this:

class UsersController < ApplicationController
  ## Exception Handling
  class NotActivated < StandardError

  rescue_from NotActivated, :with => :not_activated

  def not_activated(exception)
    flash[:notice] = "This user is not activated."
    Event.new_event "Exception: #{exception.message}", current_user, request.remote_ip
    redirect_to "/"

  def show
      // Do something that fails..
      raise NotActivated unless @user.is_activated?

What you're doing here is creating a class "NotActivated" that will serve as Exception. Using raise, you can throw "NotActivated" as an Exception. rescue_from is the way of catching an Exception with a specified method (not_activated in this case). Quite a long example, but it should show you how it works.

Best wishes,

How can I change the Bootstrap default font family using font from Google?

Another way is to download source code then change following vaiables in variables.less

@font-family-sans-serif:  "Helvetica Neue", Helvetica, Arial, sans-serif;
@font-family-serif:       Georgia, "Times New Roman", Times, serif;
//** Default monospace fonts for `<code>`, `<kbd>`, and `<pre>`.
@font-family-monospace:   Menlo, Monaco, Consolas, "Courier New", monospace;
@font-family-base:        @font-family-sans-serif;

And then compile it to .css file

How can I rebuild indexes and update stats in MySQL innoDB?

You can also use the provided CLI tool mysqlcheck to run the optimizations. It's got a ton of switches but at its most basic you just pass in the database, username, and password.

Adding this to cron or the Windows Scheduler can make this an automated process. (MariaDB but basically the same thing.)

Gridview get Checkbox.Checked value

    foreach (GridViewRow row in GridView1.Rows)
        CheckBox chkbox = (CheckBox)row.FindControl("CheckBox1");
        if (chkbox.Checked == true)
            // Your Code


this statement

DBMS_OUTPUT.PUT_LINE('a.firstName' || 'a.lastName');

means to print the string as it is.. remove the quotes to get the values to be printed.So the correct syntax is

DBMS_OUTPUT.PUT_LINE(a.firstName || a.lastName);

Git pull a certain branch from GitHub

This helped me to get remote branch before merging it into other:

git fetch repo xyz:xyz
git checkout xyz

Read Post Data submitted to ASP.Net Form

NameValueCollection nvclc = Request.Form;
string   uName= nvclc ["txtUserName"];
string   pswod= nvclc ["txtPassword"];
//try login
CheckLogin(uName, pswod);

React JS Error: is not defined react/jsx-no-undef

in map.jsx or map.js file, if you exporting as default like:

export default MapComponent;

then you can import it like

import MapComponent from './map'

but if you do not export it as default like this one here

export const MapComponent = () => { ...whatever }

you need to import in inside curly braces like

import { MapComponent } from './map'

Here we get into your problem: --- sometimes in our project (most of the time that I work with react) we need to import our styles in our javascript files to use it. in such cases we can use that syntax because in such cases, we have a blunder like webpack that that takes care of it, then later on, when we want to bundle our app, webpack is going to extract our CSS files and put it in a separate (for example) app.css file. in those situations, we can use such syntax to import our CSS files into our javascript modules.

like below:

import './css/app.css'

if you are using sass all you need to do is just use sass loader with webpack!

How to get all keys with their values in redis

You can use MGET to get the values of multiple keys in a single go.


redis> SET key1 "Hello"
redis> SET key2 "World"
redis> MGET key1 key2 nonexisting
1) "Hello"
2) "World"
3) (nil)

For listing out all keys & values you'll probably have to use bash or something similar, but MGET can help in listing all the values when you know which keys to look for beforehand.

Using the star sign in grep

Use grep -P - which enables support for Perl style regular expressions.

grep -P "abc.*def" myfile

RegEx to extract all matches from string using RegExp.exec

Iterables are nicer:

const matches = (text, pattern) => ({
  [Symbol.iterator]: function * () {
    const clone = new RegExp(pattern.source, pattern.flags);
    let match = null;
    do {
      match = clone.exec(text);
      if (match) {
        yield match;
    } while (match);

Usage in a loop:

for (const match of matches('abcdefabcdef', /ab/g)) {

Or if you want an array:

[ ...matches('abcdefabcdef', /ab/g) ]

adb is not recognized as internal or external command on windows

If you get your adb from Android Studio (which most will nowadays since Android is deprecated on Eclipse), your adb program will most likely be located here:


Where %USERPROFILE% represents something like C:\Users\yourName.

If you go into your computer's environmental variables and add %USERPROFILE%\AppData\Local\Android\sdk\platform-tools to the PATH (just copy-paste that line, even with the % --- it will work fine, at least on Windows, you don't need to hardcode your username) then it should work now. Open a new command prompt and type adb to check.

Split bash string by newline characters

Another way:

readarray -t y <<<"$x"

Or, if you don't have bash 4, the bash 3.2 equivalent:

IFS=$'\n' read -rd '' -a y <<<"$x"

You can also do it the way you were initially trying to use:

y=(${x//$'\n'/ })

This, however, will not function correctly if your string already contains spaces, such as 'line 1\nline 2'. To make it work, you need to restrict the word separator before parsing it:

IFS=$'\n' y=(${x//$'\n'/ })

...and then, since you are changing the separator, you don't need to convert the \n to space anymore, so you can simplify it to:

IFS=$'\n' y=($x)

This approach will function unless $x contains a matching globbing pattern (such as "*") - in which case it will be replaced by the matched file name(s). The read/readarray methods require newer bash versions, but work in all cases.

Passing environment-dependent variables in webpack

You can directly use the EnvironmentPlugin available in webpack to have access to any environment variable during the transpilation.

You just have to declare the plugin in your webpack.config.js file:

var webpack = require('webpack');

module.exports = {
    /* ... */
    plugins = [
        new webpack.EnvironmentPlugin(['NODE_ENV'])

Note that you must declare explicitly the name of the environment variables you want to use.

Select Last Row in the Table


How to drop column with constraint?

I got the same:

ALTER TABLE DROP COLUMN failed because one or more objects access this column message.

My column had an index which needed to be deleted first. Using sys.indexes did the trick:


SELECT @sql = 'DROP INDEX ' + idx.NAME + ' ON tblName'
FROM sys.indexes idx
INNER JOIN sys.tables tbl ON idx.object_id = tbl.object_id
INNER JOIN sys.index_columns idxCol ON idx.index_id = idxCol.index_id
INNER JOIN sys.columns col ON idxCol.column_id = col.column_id
WHERE idx.type <> 0
    AND tbl.NAME = 'tblName'
    AND col.NAME = 'colName'

EXEC sp_executeSql @sql


SelectSingleNode returning null for known good xml node path using XPath

Just to build upon solving the namespace issues, in my case I've been running into documents with multiple namespaces and needed to handle namespaces properly. I wrote the function below to get a namespace manager to deal with any namespace in the document:

private XmlNamespaceManager GetNameSpaceManager(XmlDocument xDoc)
        XmlNamespaceManager nsm = new XmlNamespaceManager(xDoc.NameTable);
        XPathNavigator RootNode = xDoc.CreateNavigator();
        IDictionary<string, string> NameSpaces = RootNode.GetNamespacesInScope(XmlNamespaceScope.All);

        foreach (KeyValuePair<string, string> kvp in NameSpaces)
            nsm.AddNamespace(kvp.Key, kvp.Value);

        return nsm;

How can I clear the NuGet package cache using the command line?

First, download the NuGet command line tool from here.

Next, open a command prompt and cd to the directory to which nuget.exe was downloaded.

You can list the local caches with this command:

nuget locals all -list

You can clear all caches with this command:

nuget locals all -clear


Add & delete view from Layout

For changing visibility:


For removing:


Call multiple functions onClick ReactJS

Maybe you can use arrow function (ES6+) or the simple old function declaration.

Normal function declaration type (Not ES6+):

<link href="#" onClick={function(event){ func1(event); func2();}}>Trigger here</link>

Anonymous function or arrow function type (ES6+)

<link href="#" onClick={(event) => { func1(event); func2();}}>Trigger here</link>

The second one is the shortest road that I know. Hope it helps you!

How to easily resize/optimize an image size with iOS?

If anyone still looking for better option

-(UIImage *)scaleImage:(UIImage *)image toSize:(CGSize)targetSize {

    UIImage *sourceImage = image;
    UIImage *newImage = nil;

    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;

    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;

    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;

    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {

        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor < heightFactor)
            scaleFactor = widthFactor;
            scaleFactor = heightFactor;

        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the image

        if (widthFactor < heightFactor) {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        } else if (widthFactor > heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;

    // this is actually the interesting part:


    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();

    if(newImage == nil) NSLog(@"could not scale image");

    return newImage ;


Different names of JSON property during serialization and deserialization

I would bind two different getters/setters pair to one variable:

class Coordinates{
    int red;

    public byte getRed() {
      return red;

    public void setRed(byte red) { = red;

    public byte getR() {
      return red;

    public void setR(byte red) { = red;

ASP.Net Download file to client browser

Try changing it to.

 Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
 Response.AddHeader("Content-Length", file.Length.ToString());
 Response.ContentType = "text/plain";

MySql Error: 1364 Field 'display_name' doesn't have default value

Also, I had this issue using Laravel, but fixed by changing my database schema to allow "null" inputs on a table where I plan to collect the information from separate forms:

public function up()

    Schema::create('trip_table', function (Blueprint $table) {


The ->nullable(); Added to the end. This is using Laravel. Hope this helps someone, thanks!

Is it possible to write data to file using only JavaScript?

Use the code by the user @useless-code above ( to generate the file. If you want to download the file automatically, pass the textFile that was just generated to this function:

var downloadFile = function downloadURL(url) {
    var hiddenIFrameID = 'hiddenDownloader',
    iframe = document.getElementById(hiddenIFrameID);
    if (iframe === null) {
        iframe = document.createElement('iframe'); = hiddenIFrameID; = 'none';
    iframe.src = url;

Can I perform a DNS lookup (hostname to IP address) using client-side Javascript?

I know this question was asked a very long time ago, but I figured I'd offer a more recent answer.

DNS over HTTPS (DoH)

You can send DNS queries over HTTPS to DNS resolvers that support it. The standard for DOH is described in RFC 8484.

This is a similar thing to what all the other answers suggest, only that DoH is actually the DNS protocol over HTTPS. It's also a "proposed" Internet standard and it's becoming quite popular. For example, some major browsers either support it or have plans to support it (Chrome, Edge, Firefox), and Microsoft is in the process of building it into their operating system.

One of the purposes of DoH is:

allowing web applications to access DNS information via existing browser APIs in a safe way consistent with Cross Origin Resource Sharing (CORS)

There's an open source tool made especially for doing DNS lookups from web applications called dohjs. It does DNS over HTTPS (DoH) wireformat queries as described in RFC 8484. It supports both GET and POST methods.

Full disclosure: I am a contributor to dohjs.

Another JavaScript library with similar features is found here - I haven't used this one personally, but I think it would work client side as well.


If you don't want to bother with DNS wireformat, both Google and Cloudflare offer JSON APIs for DNS over HTTPS.

Example Javascript code to lookup with Google's JSON DOH API:

var response = await fetch('');
var json = await response.json();

Examples from the RFC for DOH GET and POST with wireformat

Here are the examples the RFC gives for both GET and POST (see

GET example:

The first example request uses GET to request "".

:method = GET
:scheme = https
:authority =
:path = /dns-query?dns=AAABAAABAAAAAAAAA3d3dwdleGFtcGxlA2NvbQAAAQAB
accept = application/dns-message

POST example:

The same DNS query for "", using the POST method would be:

:method = POST
:scheme = https
:authority =
:path = /dns-query
accept = application/dns-message
content-type = application/dns-message
content-length = 33

<33 bytes represented by the following hex encoding> 00 00 01 00 00 01 00 00 00 00 00 00 03 77 77 77 07 65 78 61 6d 70 6c 65 03 63 6f 6d 00 00 01 00 01

Other places to send DOH queries

You can find a list of some public DNS resolvers that support DNS over HTTPS in a couple places:

Of the above resources, I'd say that the list on Curl's wiki and the DNSCrypt list are are probably the most complete and the most frequently updated. Curl's page also includes a list of open source tools for DoH (servers, proxies, client libs, etc).

Initialize 2D array

How about something like this:

for (int row = 0; row < 3; row ++)
    for (int col = 0; col < 3; col++)
        table[row][col] = (char) ('1' + row * 3 + col);

The following complete Java program:

class Test {
    public static void main(String[] args) {
        char[][] table = new char[3][3];
        for (int row = 0; row < 3; row ++)
            for (int col = 0; col < 3; col++)
                table[row][col] = (char) ('1' + row * 3 + col);

        for (int row = 0; row < 3; row ++)
            for (int col = 0; col < 3; col++)
                System.out.println (table[row][col]);



This works because the digits in Unicode are consecutive starting at \u0030 (which is what you get from '0').

The expression '1' + row * 3 + col (where you vary row and col between 0 and 2 inclusive) simply gives you a character from 1 to 9.

Obviously, this won't give you the character 10 (since that's two characters) if you go further but it works just fine for the 3x3 case. You would have to change the method of generating the array contents at that point such as with something like:

String[][] table = new String[5][5];
for (int row = 0; row < 5; row ++)
    for (int col = 0; col < 5; col++)
        table[row][col] = String.format("%d", row * 5 + col + 1);

what does "dead beef" mean?

It was used as a pattern to store in memory as a series of hex bytes (0xde, 0xad, 0xbe, 0xef). You could see if memory was corrupted because of hardware failure, buffer overruns, etc.

Reset CSS display property to default value

A browser's default styles are defined in its user agent stylesheet, the sources of which you can find here. Unfortunately, the Cascading and Inheritance level 3 spec does not appear to propose a way to reset a style property to its browser default. However there are plans to reintroduce a keyword for this in Cascading and Inheritance level 4 — the working group simply hasn't settled on a name for this keyword yet (the link currently says revert, but it is not final). Information about browser support for revert can be found on

While the level 3 spec does introduce an initial keyword, setting a property to its initial value resets it to its default value as defined by CSS, not as defined by the browser. The initial value of display is inline; this is specified here. The initial keyword refers to that value, not the browser default. The spec itself makes this note under the all property:

For example, if an author specifies all: initial on an element it will block all inheritance and reset all properties, as if no rules appeared in the author, user, or user-agent levels of the cascade.

This can be useful for the root element of a "widget" included in a page, which does not wish to inherit the styles of the outer page. Note, however, that any "default" style applied to that element (such as, e.g. display: block from the UA style sheet on block elements such as <div>) will also be blown away.

So I guess the only way right now using pure CSS is to look up the browser default value and set it manually to that: { display: inline-block; } { display: block; }

(An alternative to the above would be { display: inline-block; }, but that involves modifying the original selector rather than an override.)

Oracle comparing timestamp with date

to_date format worked for me. Please consider the date formats: MON-, MM, ., -.

t.start_date >= to_date('14.11.2016 04:01:39', 'DD.MM.YYYY HH24:MI:SS')
t.start_date <=to_date('14.11.2016 04:10:07', 'DD.MM.YYYY HH24:MI:SS')

"Could not find a valid gem in any repository" (rubygame and others)

I have tried most of the solutions suggested here but I had no luck. I found a solution that worked for me, which was manually updating the gemfile to 2.6.7. The guide on how to do is in installing-using-update-packages

Download rubygems-update-2.6.7.gem to your C:\

Now, using your Command Prompt:

C:\>gem install --local C:\rubygems-update-2.6.7.gem
C:\>update_rubygems --no-ri --no-rdoc 

After this, gem --version should report the new update version (2.6.7).

You can now safely uninstall rubygems-update gem:

C:\>gem uninstall rubygems-update -x
Removing update_rubygems
Successfully uninstalled rubygems-update-2.6.7

The reason why this did not work before was because server used certificates SHA-1, now this was updated to SHA-2.

How to add reference to a method parameter in javadoc?

I guess you could write your own doclet or taglet to support this behaviour.

Taglet Overview

Doclet Overview

How do you reverse a string in place in C or C++?

The standard algorithm is to use pointers to the start / end, and walk them inward until they meet or cross in the middle. Swap as you go.

Reverse ASCII string, i.e. a 0-terminated array where every character fits in 1 char. (Or other non-multibyte character sets).

void strrev(char *head)
  if (!head) return;
  char *tail = head;
  while(*tail) ++tail;    // find the 0 terminator, like head+strlen
  --tail;               // tail points to the last real char
                        // head still points to the first
  for( ; head < tail; ++head, --tail) {
      // walk pointers inwards until they meet or cross in the middle
      char h = *head, t = *tail;
      *head = t;           // swapping as we go
      *tail = h;

// test program that reverses its args
#include <stdio.h>

int main(int argc, char **argv)
  do {
    printf("%s ",  argv[argc-1]);
    printf("%s\n", argv[argc-1]);
  } while(--argc);

  return 0;

The same algorithm works for integer arrays with known length, just use tail = start + length - 1 instead of the end-finding loop.

(Editor's note: this answer originally used XOR-swap for this simple version, too. Fixed for the benefit of future readers of this popular question. XOR-swap is highly not recommended; hard to read and making your code compile less efficiently. You can see on the Godbolt compiler explorer how much more complicated the asm loop body is when xor-swap is compiled for x86-64 with gcc -O3.)

Ok, fine, let's fix the UTF-8 chars...

(This is XOR-swap thing. Take care to note that you must avoid swapping with self, because if *p and *q are the same location you'll zero it with a^a==0. XOR-swap depends on having two distinct locations, using them each as temporary storage.)

Editor's note: you can replace SWP with a safe inline function using a tmp variable.

#include <bits/types.h>
#include <stdio.h>

#define SWP(x,y) (x^=y, y^=x, x^=y)

void strrev(char *p)
  char *q = p;
  while(q && *q) ++q; /* find eos */
  for(--q; p < q; ++p, --q) SWP(*p, *q);

void strrev_utf8(char *p)
  char *q = p;
  strrev(p); /* call base case */

  /* Ok, now fix bass-ackwards UTF chars. */
  while(q && *q) ++q; /* find eos */
  while(p < --q)
    switch( (*q & 0xF0) >> 4 ) {
    case 0xF: /* U+010000-U+10FFFF: four bytes. */
      SWP(*(q-0), *(q-3));
      SWP(*(q-1), *(q-2));
      q -= 3;
    case 0xE: /* U+000800-U+00FFFF: three bytes. */
      SWP(*(q-0), *(q-2));
      q -= 2;
    case 0xC: /* fall-through */
    case 0xD: /* U+000080-U+0007FF: two bytes. */
      SWP(*(q-0), *(q-1));

int main(int argc, char **argv)
  do {
    printf("%s ",  argv[argc-1]);
    printf("%s\n", argv[argc-1]);
  } while(--argc);

  return 0;
  • Why, yes, if the input is borked, this will cheerfully swap outside the place.
  • Useful link when vandalising in the UNICODE:
  • Also, UTF-8 over 0x10000 is untested (as I don't seem to have any font for it, nor the patience to use a hexeditor)


$ ./strrev Räksmörgås ¦¦¦?????

¦¦¦????? ?????¦¦¦

Räksmörgås sågrömskäR

./strrev verrts/.

Python, add items from txt file into a list

names=[line.strip() for line in open('names.txt')]

Trigger standard HTML5 validation (form) without using submit button?

Try HTMLFormElement.reportValidity() where this function will invoke the input validations.

How to print to stderr in Python?

EDIT In hind-sight, I think the potential confusion with changing sys.stderr and not seeing the behaviour updated makes this answer not as good as just using a simple function as others have pointed out.

Using partial only saves you 1 line of code. The potential confusion is not worth saving 1 line of code.


To make it even easier, here's a version that uses 'partial', which is a big help in wrapping functions.

from __future__ import print_function
import sys
from functools import partial

error = partial(print, file=sys.stderr)

You then use it like so

error('An error occured!')

You can check that it's printing to stderr and not stdout by doing the following (over-riding code from

# over-ride stderr to prove that this function works.
class NullDevice():
    def write(self, s):
sys.stderr = NullDevice()

# we must import print error AFTER we've removed the null device because
# it has been assigned and will not be re-evaluated.
# assume error function is in
from print_error import error

# no message should be printed
error("You won't see this error!")

The downside to this is partial assigns the value of sys.stderr to the wrapped function at the time of creation. Which means, if you redirect stderr later it won't affect this function. If you plan to redirect stderr, then use the **kwargs method mentioned by aaguirre on this page.

How to resolve cURL Error (7): couldn't connect to host?


is very explicit ... it means Failed to connect() to host or proxy.

The following code would work on any system:

$ch = curl_init("");    // initialize curl handle
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$data = curl_exec($ch);

If you can not see google page then .. your URL is wrong or you have some firewall or restriction issue.

How can I use Bash syntax in Makefile targets?

There is a way to do this without explicitly setting your SHELL variable to point to bash. This can be useful if you have many makefiles since SHELL isn't inherited by subsequent makefiles or taken from the environment. You also need to be sure that anyone who compiles your code configures their system this way.

If you run sudo dpkg-reconfigure dash and answer 'no' to the prompt, your system will not use dash as the default shell. It will then point to bash (at least in Ubuntu). Note that using dash as your system shell is a bit more efficient though.

What does it mean "No Launcher activity found!"

You missed in specifying the intent filter elements in your manifest file.Manifest file is:

<application android:label="@string/app_name" android:icon="@drawable/icon">
    <activity android:name="Your Activity Name"
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />

Add and check this correctly. Hope this will help..

Reset all the items in a form

You can create the form again and dispose the old one.

public partial class Form1 : Form
    public Form1()

    private void btnReset_Click(object sender, EventArgs e)
        Form1 NewForm = new Form1();           

PHP, get file name without file extension

No need for all that. Check out pathinfo(), it gives you all the components of your path.

Example from the manual:

$path_parts = pathinfo('/www/htdocs/index.html');

echo $path_parts['dirname'], "\n";
echo $path_parts['basename'], "\n";
echo $path_parts['extension'], "\n";
echo $path_parts['filename'], "\n"; // filename is only since PHP 5.2.0

Output of the code:


And alternatively you can get only certain parts like:

echo pathinfo('/www/htdocs/index.html', PATHINFO_EXTENSION); // outputs html

Autocompletion in Vim

I'm a bit late to the party but autocomplpop might be helpful.

What is the difference between char s[] and char *s?

Just to add: you also get different values for their sizes.

printf("sizeof s[] = %zu\n", sizeof(s));  //6
printf("sizeof *s  = %zu\n", sizeof(s));  //4 or 8

As mentioned above, for an array '\0' will be allocated as the final element.

How to drop columns using Rails migration

In a rails4 app it is possible to use the change method also for removing columns. The third param is the data_type and in the optional forth you can give options. It is a bit hidden in the section 'Available transformations' on the documentation .

class RemoveFieldFromTableName < ActiveRecord::Migration
  def change
    remove_column :table_name, :field_name, :data_type, {}

Alter user defined type in SQL Server

We are using the following procedure, it allows us to re-create a type from scratch, which is "a start". It renames the existing type, creates the type, recompiles stored procs and then drops the old type. This takes care of scenarios where simply dropping the old type-definition fails due to references to that type.

Usage Example:

exec RECREATE_TYPE @schema='dbo', @typ_nme='typ_foo', @sql='AS TABLE([bar] varchar(10) NOT NULL)'


    @schema     VARCHAR(100),       -- the schema name for the existing type
    @typ_nme    VARCHAR(128),       -- the type-name (without schema name)
    @sql        VARCHAR(MAX)        -- the SQL to create a type WITHOUT the "CREATE TYPE schema.typename" part
    @scid       BIGINT,
    @typ_id     BIGINT,
    @temp_nme   VARCHAR(1000),
    @msg        VARCHAR(200)
    -- find the existing type by schema and name
    SELECT @scid = [SCHEMA_ID] FROM sys.schemas WHERE UPPER(name) = UPPER(@schema);
    IF (@scid IS NULL) BEGIN
        SET @msg = 'Schema ''' + @schema + ''' not found.';
        RAISERROR (@msg, 1, 0);
    SELECT @typ_id = system_type_id FROM sys.types WHERE UPPER(name) = UPPER(@typ_nme);
    SET @temp_nme = @typ_nme + '_rcrt'; -- temporary name for the existing type

    -- if the type-to-be-recreated actually exists, then rename it (give it a temporary name)
    -- if it doesn't exist, then that's OK, too.
    IF (@typ_id IS NOT NULL) BEGIN
        exec sp_rename @objname=@typ_nme, @newname= @temp_nme, @objtype='USERDATATYPE'

    -- now create the new type
    SET @sql = 'CREATE TYPE ' + @schema + '.' + @typ_nme + ' ' + @sql;
    exec sp_sqlexec @sql;

    -- if we are RE-creating a type (as opposed to just creating a brand-spanking-new type)...
    IF (@typ_id IS NOT NULL) BEGIN
        exec recompile_prog;    -- then recompile all stored procs (that may have used the type)
        exec sp_droptype @typename=@temp_nme;   -- and drop the temporary type which is now no longer referenced


CREATE PROCEDURE [dbo].[recompile_prog]
    DECLARE @v TABLE (RecID INT IDENTITY(1,1), spname sysname)
    -- retrieve the list of stored procedures
        '[' + s.[name] + '].[' + + ']'     
        (SELECT, sp.schema_id, sp.is_ms_shipped FROM sys.procedures sp UNION SELECT, so.SCHEMA_ID, so.is_ms_shipped FROM sys.objects so WHERE so.type_desc LIKE '%FUNCTION%') items
        INNER JOIN sys.schemas s ON s.schema_id = items.schema_id    
        WHERE is_ms_shipped = 0;

    -- counter variables
    DECLARE @cnt INT, @Tot INT;
    SELECT @cnt = 1;
    SELECT @Tot = COUNT(*) FROM @v;
    DECLARE @spname sysname
    -- start the loop
    WHILE @Cnt <= @Tot BEGIN    
        SELECT @spname = spname        
        FROM @v        
        WHERE RecID = @Cnt;
        --PRINT 'refreshing...' + @spname    
        BEGIN TRY        -- refresh the stored procedure        
            EXEC sp_refreshsqlmodule @spname    
        END TRY    
        BEGIN CATCH        
            PRINT 'Validation failed for : ' + @spname + ', Error:' + ERROR_MESSAGE();
        END CATCH    
        SET @Cnt = @cnt + 1;


What is (x & 1) and (x >>= 1)?

These are Bitwise Operators (reference).

x & 1 produces a value that is either 1 or 0, depending on the least significant bit of x: if the last bit is 1, the result of x & 1 is 1; otherwise, it is 0. This is a bitwise AND operation.

x >>= 1 means "set x to itself shifted by one bit to the right". The expression evaluates to the new value of x after the shift.

Note: The value of the most significant bit after the shift is zero for values of unsigned type. For values of signed type the most significant bit is copied from the sign bit of the value prior to shifting as part of sign extension, so the loop will never finish if x is a signed type, and the initial value is negative.

SQL: parse the first, middle and last name from a fullname field

As everyone else says, you can't from a simple programmatic way.

Consider these examples:

  • President "George Herbert Walker Bush" (First Middle Middle Last)

  • Presidential assassin "John Wilkes Booth" (First Middle Last)

  • Guitarist "Eddie Van Halen" (First Last Last)

  • And his mom probably calls him Edward Lodewijk Van Halen (First Middle Last Last)

  • Famed castaway "Mary Ann Summers" (First First Last)

  • New Mexico GOP chairman "Fernando C de Baca" (First Last Last Last)

How do I copy SQL Azure database to my local development server?

In SQL Server 2016 Management Studio, the process for getting an azure database to your local machine has been streamlined.

Right click on the database you want to import, click Tasks > Export data-tier application, and export your database to a local .dacpac file.

In your local target SQL server instance, you can right click Databases > Import data-tier application, and once it's local, you can do things like backup and restore the database.

jQuery selectors on custom data attributes using HTML5

jsFiddle Demo

jQuery provides several selectors (full list) in order to make the queries you are looking for work. To address your question "In other cases is it possible to use other selectors like "contains, less than, greater than, etc..."." you can also use contains, starts with, and ends with to look at these html5 data attributes. See the full list above in order to see all of your options.

The basic querying has been covered above, and using John Hartsock's answer is going to be the best bet to either get every data-company element, or to get every one except Microsoft (or any other version of :not).

In order to expand this to the other points you are looking for, we can use several meta selectors. First, if you are going to do multiple queries, it is nice to cache the parent selection.

var group = $('ul[data-group="Companies"]');

Next, we can look for companies in this set who start with G

var google = $('[data-company^="G"]',group);//google

Or perhaps companies which contain the word soft

var microsoft = $('[data-company*="soft"]',group);//microsoft

It is also possible to get elements whose data attribute's ending matches

var facebook = $('[data-company$="book"]',group);//facebook

//stored selector_x000D_
var group = $('ul[data-group="Companies"]');_x000D_
//data-company starts with G_x000D_
var google = $('[data-company^="G"]',group).css('color','green');_x000D_
//data-company contains soft_x000D_
var microsoft = $('[data-company*="soft"]',group).css('color','blue');_x000D_
//data-company ends with book_x000D_
var facebook = $('[data-company$="book"]',group).css('color','pink');
<script src=""></script>_x000D_
<ul data-group="Companies">_x000D_
  <li data-company="Microsoft">Microsoft</li>_x000D_
  <li data-company="Google">Google</li>_x000D_
  <li data-company ="Facebook">Facebook</li>_x000D_

no pg_hba.conf entry for host

Add the following in line in pg_hba.conf

hostnossl all all trust

And then restart the Service.

SonarQube Exclude a directory

You can do the same with build.gradle

sonarqube {
properties {
    property "sonar.exclusions", "**/src/java/test/**/*.java"

And if you want to exclude more files/directories then:

sonarqube {
properties {
    property "sonar.exclusions", "**/src/java/test/**/*.java, **/src/java/main/**/*.java"

Calling a Fragment method from a parent Activity

I don't know about Java, but in C# (Xamarin.Android) there is no need to look up the fragment everytime you need to call the method, see below:

public class BrandActivity : Activity
    MyFragment myFragment;

    protected override void OnCreate(Bundle bundle)
        // ...
        myFragment = new MyFragment();      
        // ...

    void someMethod()

public class MyFragment : Android.Support.V4.App.Fragment
    public override void OnCreate(Bundle bundle)
        // ...

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle bundle)
        // ...

    public void MyPublicMethod()
        // ...

I think in Java you can do the same.

Get the filename of a fileupload in a document through JavaScript

Try the value property, like this:

var fu1 = document.getElementById("FileUpload1");
alert("You selected " + fu1.value);

NOTE: It looks like FileUpload1 is an ASP.Net server-side FileUpload control.
If so, you should get its ID using the ClientID property, like this:

var fu1 = document.getElementById("<%= FileUpload1.ClientID %>");

hash function for string

First, you generally do not want to use a cryptographic hash for a hash table. An algorithm that's very fast by cryptographic standards is still excruciatingly slow by hash table standards.

Second, you want to ensure that every bit of the input can/will affect the result. One easy way to do that is to rotate the current result by some number of bits, then XOR the current hash code with the current byte. Repeat until you reach the end of the string. Note that you generally do not want the rotation to be an even multiple of the byte size either.

For example, assuming the common case of 8 bit bytes, you might rotate by 5 bits:

int hash(char const *input) { 
    int result = 0x55555555;

    while (*input) { 
        result ^= *input++;
        result = rol(result, 5);

Edit: Also note that 10000 slots is rarely a good choice for a hash table size. You usually want one of two things: you either want a prime number as the size (required to ensure correctness with some types of hash resolution) or else a power of 2 (so reducing the value to the correct range can be done with a simple bit-mask).

Why is Dictionary preferred over Hashtable in C#?

Another important difference is that Hashtable is thread safe. Hashtable has built-in multiple reader/single writer (MR/SW) thread safety which means Hashtable allows ONE writer together with multiple readers without locking.

In the case of Dictionary there is no thread safety; if you need thread safety you must implement your own synchronization.

To elaborate further:

Hashtable provides some thread-safety through the Synchronized property, which returns a thread-safe wrapper around the collection. The wrapper works by locking the entire collection on every add or remove operation. Therefore, each thread that is attempting to access the collection must wait for its turn to take the one lock. This is not scalable and can cause significant performance degradation for large collections. Also, the design is not completely protected from race conditions.

The .NET Framework 2.0 collection classes like List<T>, Dictionary<TKey, TValue>, etc. do not provide any thread synchronization; user code must provide all synchronization when items are added or removed on multiple threads concurrently

If you need type safety as well thread safety, use concurrent collections classes in the .NET Framework. Further reading here.

An additional difference is that when we add the multiple entries in Dictionary, the order in which the entries are added is maintained. When we retrieve the items from Dictionary we will get the records in the same order we have inserted them. Whereas Hashtable doesn't preserve the insertion order.

How to update Ruby to 1.9.x on Mac?

As previously mentioned, the bundler version may be too high for your version of rails.

I ran into the same problem using Rails 3.0.1 which requires Bundler v1.0.0 - v1.0.22

Check your bundler version using: gem list bundler

If your bundler version is not within the appropriate range, I found this solution to work: rvm @global do gem uninstall bundler

Note: rvm is required for this solution... another case for why you should be using rvm in the first place.

Pandas: how to change all the values of a column?

You can do a column transformation by using apply

Define a clean function to remove the dollar and commas and convert your data to float.

def clean(x):
    x = x.replace("$", "").replace(",", "").replace(" ", "")
    return float(x)

Next, call it on your column like this.

data['Revenue'] = data['Revenue'].apply(clean)

Can we use join for two different database tables?

You could use Synonyms part in the database.

enter image description here

Then in view wizard from Synonyms tab find your saved synonyms and add to view and set inner join simply. enter image description here

HRESULT: 0x800A03EC on Worksheet.range

I've come across it several different times and every time it was always some error with either duplicating a tab name or in this current case it just occurred because I simply had a typo in the get_Range where I tried to get a Cell by number and number instead of the letter and number.
Drove me crazy because the error pointed me to a few lines down but I had commented out all of the creation of the other sheets above the "error line" and the ones in the line and below were created with no issue.
Happened to scan up a few lines above and saw that I put 6 + lastword, C + lastrow in my get_Range statement and of course you can't have a cell starting with a number it's always letter than number.

Can I delete data from the iOS DeviceSupport directory?

Yes, you can delete data from iOS device support by the symbols of the operating system, one for each version for each architecture. It's used for debugging. If you don't need to support those devices any more, you can delete the directory without ill effect

Equivalent of *Nix 'which' command in PowerShell?

The very first alias I made once I started customizing my profile in PowerShell was 'which'.

New-Alias which get-command

To add this to your profile, type this:

"`nNew-Alias which get-command" | add-content $profile

The `n at the start of the last line is to ensure it will start as a new line.

CodeIgniter Disallowed Key Characters

Took a while to figure this one out. Seems most of us missed the obvious error…the last “-” is not escaped.

Adding the . and | as I’ve seen other suggest may work for you, but the regex was supposed to be:

if ( ! preg_match("/^[a-z0-9:_\/\-\.|]+$/i", $str))  

What are the First and Second Level caches in (N)Hibernate?

First Level Cache

Session object holds the first level cache data. It is enabled by default. The first level cache data will not be available to entire application. An application can use many session object.

Second Level Cache

SessionFactory object holds the second level cache data. The data stored in the second level cache will be available to entire application. But we need to enable it explicitly.

Counting DISTINCT over multiple columns

This code uses distinct on 2 parameters and provides count of number of rows specific to those distinct values row count. It worked for me in MySQL like a charm.

select DISTINCT DocumentId as i,  DocumentSessionId as s , count(*) 
from DocumentOutputItems   
group by i ,s;

XSLT equivalent for JSON

I recently found a tool that I love for styling JSON: Very easy tool to use--in my opinion, it is much easier to work with than XSLT--no need for XPATH queries.

Various ways to remove local Git changes

Reason for adding an answer at this moment:

So far I was adding the conclusion and ‘answers’ to my initial question itself, making the question very lengthy, hence moving to separate answer.

I have also added more frequently used git commands that helps me on git, to help someone else too.

Basically to clean all local commits $ git reset --hard and $ git clean -d -f

First step before you do any commits is to configure your username and email that appears along with your commit.

#Sets the name you want attached to your commit transactions

$ git config --global "[name]"

#Sets the email you want atached to your commit transactions

$ git config --global "[email address]"

#List the global config

$ git config --list

#List the remote URL

$ git remote show origin

#check status

git status

#List all local and remote branches

git branch -a

#create a new local branch and start working on this branch

git checkout -b "branchname" 

or, it can be done as a two step process

create branch: git branch branchname work on this branch: git checkout branchname

#commit local changes [two step process:- Add the file to the index, that means adding to the staging area. Then commit the files that are present in this staging area]

git add <path to file>

git commit -m "commit message"

#checkout some other local branch

git checkout "local branch name"

#remove all changes in local branch [Suppose you made some changes in local branch like adding new file or modifying existing file, or making a local commit, but no longer need that] git clean -d -f and git reset --hard [clean all local changes made to the local branch except if local commit]

git stash -u also removes all changes

Note: It's clear that we can use either (1) combination of git clean –d –f and git reset --hard OR (2) git stash -u to achieve the desired result.

Note 1: Stashing, as the word means 'Store (something) safely and secretly in a specified place.' This can always be retreived using git stash pop. So choosing between the above two options is developer's call.

Note 2: git reset --hard will delete working directory changes. Be sure to stash any local changes you want to keep before running this command.

# Switch to the master branch and make sure you are up to date.

git checkout master

git fetch [this may be necessary (depending on your git config) to receive updates on origin/master ]

git pull

# Merge the feature branch into the master branch.

git merge feature_branch

# Reset the master branch to origin's state.

git reset origin/master

#Accidentally deleted a file from local , how to retrieve it back? Do a git status to get the complete filepath of the deleted resource

git checkout branchname <file path name>

that's it!

#Merge master branch with someotherbranch

git checkout master
git merge someotherbranchname

#rename local branch

git branch -m old-branch-name new-branch-name

#delete local branch

git branch -D branch-name

#delete remote branch

git push origin --delete branchname


git push origin :branch-name

#revert a commit already pushed to a remote repository

git revert hgytyz4567

#branch from a previous commit using GIT

git branch branchname <sha1-of-commit>

#Change commit message of the most recent commit that's already been pushed to remote

git commit --amend -m "new commit message"
git push --force origin <branch-name>

# Discarding all local commits on this branch [Removing local commits]

In order to discard all local commits on this branch, to make the local branch identical to the "upstream" of this branch, simply run

git reset --hard @{u}

Reference: or do git reset --hard origin/master [if local branch is master]

# Revert a commit already pushed to a remote repository?

$ git revert ab12cd15

#Delete a previous commit from local branch and remote branch

Use-Case: You just commited a change to your local branch and immediately pushed to the remote branch, Suddenly realized , Oh no! I dont need this change. Now do what?

git reset --hard HEAD~1 [for deleting that commit from local branch. 1 denotes the ONE commit you made]

git push origin HEAD --force [both the commands must be executed. For deleting from remote branch]. Currently checked out branch will be referred as the branch where you are making this operation.

#Delete some of recent commits from local and remote repo and preserve to the commit that you want. ( a kind of reverting commits from local and remote)

Let's assume you have 3 commits that you've pushed to remote branch named 'develop'

commitid-1 done at 9am
commitid-2 done at 10am
commitid-3 done at 11am. // latest commit. HEAD is current here.

To revert to old commit ( to change the state of branch)

git log --oneline --decorate --graph // to see all your commitids

git clean -d -f // clean any local changes

git reset --hard commitid-1 // locally reverting to this commitid

git push -u origin +develop // push this state to remote. + to do force push

# Remove local git merge: Case: I am on master branch and merged master branch with a newly working branch phase2

$ git status

On branch master

$ git merge phase2 $ git status

On branch master

Your branch is ahead of 'origin/master' by 8 commits.

Q: How to get rid of this local git merge? Tried git reset --hard and git clean -d -f Both didn't work. The only thing that worked are any of the below ones:

$ git reset --hard origin/master


$ git reset --hard HEAD~8


$ git reset --hard 9a88396f51e2a068bb7 [sha commit code - this is the one that was present before all your merge commits happened]

#create gitignore file

touch .gitignore // create the file in mac or unix users

sample .gitignore contents:


Reference link to GIT cheat sheet:

Stored Procedure parameter default value - is this a constant or a variable

It has to be a constant - the value has to be computable at the time that the procedure is created, and that one computation has to provide the value that will always be used.

Look at the definition of sys.all_parameters:

default_value sql_variant If has_default_value is 1, the value of this column is the value of the default for the parameter; otherwise, NULL.

That is, whatever the default for a parameter is, it has to fit in that column.

As Alex K pointed out in the comments, you can just do:

CREATE PROCEDURE [dbo].[problemParam] 
    @StartDate INT = NULL,
    @EndDate INT = NULL
   SET @StartDate = COALESCE(@StartDate,CONVERT(INT,(CONVERT(CHAR(8),GETDATE()-130,112))))

provided that NULL isn't intended to be a valid value for @StartDate.

As to the blog post you linked to in the comments - that's talking about a very specific context - that, the result of evaluating GETDATE() within the context of a single query is often considered to be constant. I don't know of many people (unlike the blog author) who would consider a separate expression inside a UDF to be part of the same query as the query that calls the UDF.

De-obfuscate Javascript code to make it readable again

From the first link on google;

function call_func(_0x41dcx2) {
 var _0x41dcx3 = eval('(' + _0x41dcx2 + ')');
 var _0x41dcx4 = document['createElement']('div');
 var _0x41dcx5 = _0x41dcx3['id'];
 var _0x41dcx6 = _0x41dcx3['Student_name'];
 var _0x41dcx7 = _0x41dcx3['student_dob'];
 var _0x41dcx8 = '<b>ID:</b>';
 _0x41dcx8 += '<a href="/learningyii/index.php?r=student/view&amp; id=' + _0x41dcx5 + '">' + _0x41dcx5 + '</a>';
 _0x41dcx8 += '<br/>';
 _0x41dcx8 += '<b>Student Name:</b>';
 _0x41dcx8 += _0x41dcx6;
 _0x41dcx8 += '<br/>';
 _0x41dcx8 += '<b>Student DOB:</b>';
 _0x41dcx8 += _0x41dcx7;
 _0x41dcx8 += '<br/>';
 _0x41dcx4['innerHTML'] = _0x41dcx8;
 _0x41dcx4['setAttribute']('class', 'view');

It won't get you all the way back to source, and that's not really possible, but it'll get you out of a hole.

How do you delete all text above a certain line

Providing you know these vim commands:

1G -> go to first line in file
G -> go to last line in file

then, the following make more sense, are more unitary and easier to remember IMHO:

d1G -> delete starting from the line you are on, to the first line of file
dG -> delete starting from the line you are on, to the last line of file


Mobile Redirect using htaccess

I modified Tim Stone's solution even further. This allows the cookie to be in 2 states, 1 for mobile and 0 for full. When the mobile cookie is set to 0 even a mobile browser will go to the full site.

Here is the code:

<IfModule mod_rewrite.c>
    RewriteBase /
    RewriteEngine On

    # Check if mobile=1 is set and set cookie 'mobile' equal to 1
    RewriteCond %{QUERY_STRING} (^|&)mobile=1(&|$)
    RewriteRule ^ - [CO=mobile:1:%{HTTP_HOST}]

    # Check if mobile=0 is set and set cookie 'mobile' equal to 0
    RewriteCond %{QUERY_STRING} (^|&)mobile=0(&|$)
    RewriteRule ^ - [CO=mobile:0:%{HTTP_HOST}]

    # cookie can't be set and read in the same request so check
    RewriteCond %{QUERY_STRING} (^|&)mobile=0(&|$)
    RewriteRule ^ - [S=1]

    # Check if this looks like a mobile device
    RewriteCond %{HTTP:x-wap-profile} !^$ [OR]
    RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC,OR]
    RewriteCond %{HTTP:Profile}       !^$

    # Check if we're not already on the mobile site
    RewriteCond %{HTTP_HOST}          !^m\.
    # Check to make sure we haven't set the cookie before
    RewriteCond %{HTTP:Cookie}        !\mobile=0(;|$)
    # Now redirect to the mobile site
    RewriteRule ^{REQUEST_URI} [R,L]

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

Delete all items from a c++ std::vector

I think you should use std::vector::clear:



Doesn't clear destruct the elements held by the vector?

Yes it does. It calls the destructor of every element in the vector before returning the memory. That depends on what "elements" you are storing in the vector. In the following example, I am storing the objects them selves inside the vector:

class myclass


std::vector<myclass> myvector;
myvector.clear(); // calling clear will do the following:
// 1) invoke the deconstrutor for every myclass
// 2) size == 0 (the vector contained the actual objects).

If you want to share objects between different containers for example, you could store pointers to them. In this case, when clear is called, only pointers memory is released, the actual objects are not touched:

std::vector<myclass*> myvector;
myvector.clear(); // calling clear will do:
// 1) ---------------
// 2) size == 0 (the vector contained "pointers" not the actual objects).

For the question in the comment, I think getVector() is defined like this:

std::vector<myclass> getVector();

Maybe you want to return a reference:

// vector.getVector().clear() clears m_vector in this case
std::vector<myclass>& getVector(); 

How to get Bitmap from an Uri?

It seems that MediaStore.Images.Media.getBitmap was deprecated in API 29. The recommended way is to use ImageDecoder.createSource which was added in API 28.

Here's how getting the bitmap would be done:

val bitmap = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
    ImageDecoder.decodeBitmap(ImageDecoder.createSource(requireContext().contentResolver, imageUri))
} else {
    MediaStore.Images.Media.getBitmap(requireContext().contentResolver, imageUri)

How to trigger event when a variable's value is changed?

Seems to me like you want to create a property.

public int MyProperty
    get { return _myProperty; }
        _myProperty = value;
        if (_myProperty == 1)
            // DO SOMETHING HERE

private int _myProperty;

This allows you to run some code any time the property value changes. You could raise an event here, if you wanted.

How do you add swap to an EC2 instance?

You can add a 1 GB swap to your instance with these commands:

sudo dd if=/dev/zero of=/swapfile bs=1M count=1024
sudo mkswap /swapfile
sudo swapon /swapfile

To enable it by default after reboot, add this line to /etc/fstab:

/swapfile swap swap defaults 0 0

MongoDB relationships: embed or reference?

Actually, I'm quite curious why nobody spoke about the UML specifications. A rule of thumb is that if you have an aggregation, then you should use references. But if it is a composition, then the coupling is stronger, and you should use embedded documents.

And you will quickly understand why it is logical. If an object can exist independently of the parent, then you will want to access it even if the parent doesn't exist. As you just can't embed it in a non-existing parent, you have to make it live in it's own data structure. And if a parent exist, just link them together by adding a ref of the object in the parent.

Don't really know what is the difference between the two relationships ? Here is a link explaining them: Aggregation vs Composition in UML

Difference between View and ViewGroup in Android

in ViewGroup you can add some other Views as child. ViewGroup is the base class for layouts and view containers.

String to HtmlDocument

Using Html Agility Pack as suggested by SLaks, this becomes very easy:

string html = webClient.DownloadString(url);
var doc = new HtmlDocument();

HtmlNode specificNode = doc.GetElementById("nodeId");
HtmlNodeCollection nodesMatchingXPath = doc.DocumentNode.SelectNodes("x/path/nodes");

Adding machineKey to web.config on web-farm sites

If you are using IIS 7.5 or later you can generate the machine key from IIS and save it directly to your web.config, within the web farm you then just copy the new web.config to each server.

  1. Open IIS manager.
  2. If you need to generate and save the MachineKey for all your applications select the server name in the left pane, in that case you will be modifying the root web.config file (which is placed in the .NET framework folder). If your intention is to create MachineKey for a specific web site/application then select the web site / application from the left pane. In that case you will be modifying the web.config file of your application.
  3. Double-click the Machine Key icon in ASP.NET settings in the middle pane:
  4. MachineKey section will be read from your configuration file and be shown in the UI. If you did not configure a specific MachineKey and it is generated automatically you will see the following options:
  5. Now you can click Generate Keys on the right pane to generate random MachineKeys. When you click Apply, all settings will be saved in the web.config file.

Full Details can be seen @ Easiest way to generate MachineKey – Tips and tricks: ASP.NET, IIS and .NET development…

Find the number of employees in each department - SQL Oracle

Try the query below:

select count(*),d.dname from emp e , dept d where d.deptno = e.deptno
group by d.dname

Magento addFieldToFilter: Two fields, match as OR, not AND

To create simple OR condition for collection, use format below:

    $orders = Mage::getModel('sales/order')->getResourceCollection();

This will produce SQL like this:

WHERE (((`status` = 'processing') OR (`status` = 'pending')))

SSRS - Checking whether the data is null

Or in your SQL query wrap that field with IsNull or Coalesce (SQL Server).

Either way works, I like to put that logic in the query so the report has to do less.

onclick="javascript:history.go(-1)" not working in Chrome

Try this dude,

<button onclick="goBack()">Go Back 2 Pages</button>
  function goBack() {

How do I wait until Task is finished in C#?

I'm an async novice, so I can't tell you definitively what is happening here. I suspect that there's a mismatch in the method execution expectations, even though you are using tasks internally in the methods. I think you'd get the results you are expecting if you changed Print to return a Task<string>:

private static string Send(int id)
    Task<HttpResponseMessage> responseTask = client.GetAsync("aaaaa");
    Task<string> result;
    responseTask.ContinueWith(x => result = Print(x));
    responseTask.Wait(); // There's likely a better way to wait for both tasks without doing it in this awkward, consecutive way.
    return result.Result;

private static Task<string> Print(Task<HttpResponseMessage> httpTask)
    Task<string> task = httpTask.Result.Content.ReadAsStringAsync();
    string result = string.Empty;
    task.ContinueWith(t =>
        Console.WriteLine("Result: " + t.Result);
        result = t.Result;
    return task;

Use "ENTER" key on softkeyboard instead of clicking button

We can also use Kotlin lambda

editText.setOnKeyListener { _, keyCode, keyEvent ->
        if (keyEvent.action == KeyEvent.ACTION_DOWN && keyCode == KeyEvent.KEYCODE_ENTER) {
            Log.d("Android view component", "Enter button was pressed")
            return@setOnKeyListener true
        return@setOnKeyListener false

How do you use global variables or constant values in Ruby?

One thing you need to realize is in Ruby everything is an object. Given that, if you don't define your methods within Module or Class, Ruby will put it within the Object class. So, your code will be local to the Object scope.

A typical approach on Object Oriented Programming is encapsulate all logic within a class:

class Point
  attr_accessor :x, :y

  # If we don't specify coordinates, we start at 0.
  def initialize(x = 0, y = 0)
    # Notice that `@` indicates instance variables.
    @x = x
    @y = y

  # Here we override the `+' operator.
  def +(point) + point.x, self.y + point.y)

  # Here we draw the point.
  def draw(offset = nil)
    if offset.nil?
      new_point = self
      new_point = self + offset 

  def draw_absolute
    puts "x: #{self.x}, y: #{self.y}"

first_point =, 200)
second_point =, 4)


Hope this clarifies a bit.

How to set the width of a RaisedButton in Flutter?

we use Row or Column, Expanded, Container and the element to use example RaisedButton

 body: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                  padding: const EdgeInsets.symmetric(vertical: 10.0),
                  children: <Widget>[
                      flex: 2, // we define the width of the button
                      child: Container(
                        // height: 50, we define the height of the button
                        child: Padding(
                          padding: const EdgeInsets.symmetric(horizontal: 10.0),
                          child: RaisedButton(
                            materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                            textColor: Colors.white,
                            onPressed: () {
                              // Method to execute
                            child: Text('Copy'),
                      flex: 2, // we define the width of the button
                      child: Container(
                        // height: 50, we define the height of the button
                        child: Padding(
                          padding: const EdgeInsets.symmetric(horizontal: 10.0),
                          child: RaisedButton(
                            materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                            textColor: Colors.white,
                            onPressed: () {
                              // Method to execute
                            child: Text('Paste'),

Convert string to datetime

This will convert the string in date to datetime, if using Rails:


Doc Reference:

youtube: link to display HD video by default

Nick Vogt at H3XED posted this syntax:

Take this link and replace the expression "VIDEOID" with the (shortened/shared) ID of the video.

Exapmple for ID: i3jNECZ3ybk looks like this: ... /v/i3jNECZ3ybk?version=3&vq=hd1080

What you get as a result is the standalone 1080p video but not in the Tube environment.

How to check the maximum number of allowed connections to an Oracle database?

There are a few different limits that might come in to play in determining the number of connections an Oracle database supports. The simplest approach would be to use the SESSIONS parameter and V$SESSION, i.e.

The number of sessions the database was configured to allow

SELECT name, value 
  FROM v$parameter
 WHERE name = 'sessions'

The number of sessions currently active

  FROM v$session

As I said, though, there are other potential limits both at the database level and at the operating system level and depending on whether shared server has been configured. If shared server is ignored, you may well hit the limit of the PROCESSES parameter before you hit the limit of the SESSIONS parameter. And you may hit operating system limits because each session requires a certain amount of RAM.

Javascript set img src

Pure JavaScript to Create img tag and add attributes manually ,

var image = document.createElement("img");
var imageParent = document.getElementById("body"); = "id";
image.className = "class";
image.src = searchPic.src;            // image.src = "IMAGE URL/PATH"

Set src in pic1

document["#pic1"].src = searchPic.src;

or with getElementById

document.getElementById("pic1").src= searchPic.src;

j-Query to archive this,

$("#pic1").attr("src", searchPic.src);

Check if PHP-page is accessed from an iOS device

51Degrees' PHP solution is able to do this. you can get the free Open Source API here You can use the HardwareFamily Property to determine if it is an iPad/iPod/iPhone etc.

Due to the nature of Apple's User-Agents the initial result will return a generic device, however if you are interested in the specific device you can use a JavaScript client side override to determine to specific model.

To do this you can implement something similar to the following logic once you have determined it is an Apple Device, in this case for an iPhone.

// iPhone model checks.
function getiPhoneModel() {
// iPhone 6 Plus
if ((window.screen.height / window.screen.width == 736 / 414) && 
(window.devicePixelRatio == 3)) {
return "iPhone 6 Plus";
// iPhone 6
else if ((window.screen.height / window.screen.width == 667 / 375) && 
(window.devicePixelRatio == 2)) {
return "iPhone 6";
// iPhone 5/5C/5S or 6 in zoom mode
else if ((window.screen.height / window.screen.width == 1.775) && 
(window.devicePixelRatio == 2)) {
return "iPhone 5, 5C, 5S or 6 (display zoom)";
// iPhone 4/4S
else if ((window.screen.height / window.screen.width == 1.5) && 
(window.devicePixelRatio == 2)) {
return "iPhone 4 or 4S";
// iPhone 1/3G/3GS
else if ((window.screen.height / window.screen.width == 1.5) && 
(window.devicePixelRatio == 1)) {
return "iPhone 1, 3G or 3GS";
} else {
return "Not an iPhone";

Or for an iPad

function getiPadVersion() {
var pixelRatio = getPixelRatio();
var return_string = "Not an iPad";
if (pixelRatio == 1 ) {
return_string = "iPad 1, iPad 2, iPad Mini 1";
if (pixelRatio == 2) {
return_string = "iPad 3, iPad 4, iPad Air 1, iPad Air 2, iPad Mini 2, iPad 
Mini 3";
return return_string;

For more information on research 51Degrees have done into Apple devices you can read their blog post here

Disclosure: I work for 51Degrees.

simple custom event

Events are pretty easy in C#, but the MSDN docs in my opinion make them pretty confusing. Normally, most documentation you see discusses making a class inherit from the EventArgs base class and there's a reason for that. However, it's not the simplest way to make events, and for someone wanting something quick and easy, and in a time crunch, using the Action type is your ticket.

Creating Events & Subscribing To Them

1. Create your event on your class right after your class declaration.

public event Action<string,string,string,string>MyEvent;

2. Create your event handler class method in your class.

private void MyEventHandler(string s1,string s2,string s3,string s4)
  Console.WriteLine("{0} {1} {2} {3}",s1,s2,s3,s4);

3. Now when your class is invoked, tell it to connect the event to your new event handler. The reason the += operator is used is because you are appending your particular event handler to the event. You can actually do this with multiple separate event handlers, and when an event is raised, each event handler will operate in the sequence in which you added them.

class Example
  public Example() // I'm a C# style class constructor
    MyEvent += new Action<string,string,string,string>(MyEventHandler);

4. Now, when you're ready, trigger (aka raise) the event somewhere in your class code like so:


The end result when you run this is that the console will emit "wow this is cool". And if you changed "cool" with a date or a sequence, and ran this event trigger multiple times, you'd see the result come out in a FIFO sequence like events should normally operate.

In this example, I passed 4 strings. But you could change those to any kind of acceptable type, or used more or less types, or even remove the <...> out and pass nothing to your event handler.

And, again, if you had multiple custom event handlers, and subscribed them all to your event with the += operator, then your event trigger would have called them all in sequence.

Identifying Event Callers

But what if you want to identify the caller to this event in your event handler? This is useful if you want an event handler that reacts with conditions based on who's raised/triggered the event. There are a few ways to do this. Below are examples that are shown in order by how fast they operate:

Option 1. (Fastest) If you already know it, then pass the name as a literal string to the event handler when you trigger it.

Option 2. (Somewhat Fast) Add this into your class and call it from the calling method, and then pass that string to the event handler when you trigger it:

private static string GetCaller([System.Runtime.CompilerServices.CallerMemberName] string s = null) => s;

Option 3. (Least Fast But Still Fast) In your event handler when you trigger it, get the calling method name string with this:

string callingMethod = new System.Diagnostics.StackTrace().GetFrame(1).GetMethod().ReflectedType.Name.Split('<', '>')[1];

Unsubscribing From Events

You may have a scenario where your custom event has multiple event handlers, but you want to remove one special one out of the list of event handlers. To do so, use the -= operator like so:

MyEvent -= MyEventHandler;

A word of minor caution with this, however. If you do this and that event no longer has any event handlers, and you trigger that event again, it will throw an exception. (Exceptions, of course, you can trap with try/catch blocks.)

Clearing All Events

Okay, let's say you're through with events and you don't want to process any more. Just set it to null like so:

MyEvent = null;

The same caution for Unsubscribing events is here, as well. If your custom event handler no longer has any events, and you trigger it again, your program will throw an exception.

Selenium Finding elements by class name in python

You can try to get the list of all elements with class = "content" by using find_elements_by_class_name:

a = driver.find_elements_by_class_name("content")

Then you can click on the link that you are looking for.

Replace all 0 values to NA

Because someone asked for the Data.Table version of this, and because the given data.frame solution does not work with data.table, I am providing the solution below.

Basically, use the := operator --> DT[x == 0, x := NA]


status =

head(status, 10)
    origin destination  N
 1:      1           1 50
 2:      2           1 16
 3:      3           1 12
 4:      4           1 11
 5:      5           1  2
 6:      6           1 12
 7:      7           1  0
 8:      8           1  0
 9:      1           2 19
10:      2           2 40

status[N == 0, N := NA]

head(status, 10)
    origin destination  N
 1:      1           1 50
 2:      2           1 16
 3:      3           1 12
 4:      4           1 11
 5:      5           1  2
 6:      6           1 12
 7:      7           1 NA
 8:      8           1 NA
 9:      1           2 19
10:      2           2 40

How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version

I got the same issue with Spring Source Tool (STS) IDE for a Grails project. I checked the installed Java version and the project Java version were 1.7.*. Later I found that in GGTS.ini file the Java version was set to 1.6:


-Dosgi.requiredJavaVersion=1.6 changed to
Add below two lines before -vmargs

Problem solved. Happy coding.

header location not working in my php code

I had same application on my localhost and on a shared server. On my localhost the redirects worked fine while on this shared server didn't. I checked the phpinfo and I saw what caused this:

enter image description here

While on my localhost I had this:

enter image description here

So I asked the system admin to increase that value and after he did that, everything worked fine.

ReactJS and images in public folder

You Could also use this.. it works assuming 'yourimage.jpg' is in your public folder.

<img src={'./yourimage.jpg'}/>

Google Maps API v3 adding an InfoWindow to each marker

The only way I could finally get this to work was by creating an array in JavaScript. The array elements reference the various info-windows (one info-window is created for each marker on the map). Each array element contains the unique text for its appropriate map marker. I defined the JavaScript event for each info-window based on the array element. And when the event fires, I use the "this" keyword to reference the array element to reference the appropriate value to display.

var map = new google.maps.Map(document.getElementById('map-div'), mapOptions);
zipcircle = [];
for (var zip in zipmap) {
    var circleoptions = {
        strokeOpacity: 0.8,
        strokeWeight: 1,
        fillOpacity: 0.35,
        map: map,
        center: zipmap[zip].center,
        radius: 100
    zipcircle[zipmap[zip].zipkey] = new google.maps.Circle(circleoptions);
    zipcircle[zipmap[zip].zipkey].infowindowtext = zipmap[zip].popuptext;
    zipcircle[zipmap[zip].zipkey].infowindow = new google.maps.InfoWindow();
    google.maps.event.addListener(zipcircle[zipmap[zip].zipkey], 'click', function() {
        this.infowindow.setContent(this.infowindowtext);, this);

Unit test naming best practices


For test method names, I personally find using verbose and self-documented names very useful (alongside Javadoc comments that further explain what the test is doing).

iPhone 5 CSS media query

/* iPad */
@media screen and (min-device-width: 768px) {
    /* ipad-portrait */
    @media screen and (max-width: 896px) { 
            display: none !important;
    /* ipad-landscape */
    @media screen and (min-width: 897px) { 

/* iPhone */
@media screen and (max-device-width: 480px) {
    /* iphone-portrait */
    @media screen and (max-width: 400px) { 

    /* iphone-landscape */
    @media screen and (min-width: 401px) { 


git replacing LF with CRLF

In a GNU/Linux shell prompt, dos2unix & unix2dos commands allow you to easely convert/format your files coming from MS Windows

Remove characters after specific character in string, then remove substring?

To remove everything before a specific char, use below.

string1 = string1.Substring(string1.IndexOf('$') + 1);

What this does is, takes everything before the $ char and removes it. Now if you want to remove the items after a character, just change the +1 to a -1 and you are set!

But for a URL, I would use the built in .NET class to take of that.

Difference between xcopy and robocopy

The differences I could see is that Robocopy has a lot more options, but I didn't find any of them particularly helpful unless I'm doing something special.

I did some benchmarking of several copy routines and found XCOPY and ROBOCOPY to be the fastest, but to my surprise, XCOPY consistently edged out Robocopy.

It's ironic that robocopy retries a copy that fails, but it also failed a lot in my benchmark tests, where xcopy never did.

I did full file (byte by byte) file compares after my benchmark tests.

Here are the switches I used with robocopy in my tests:

 **"/E /R:1 /W:1 /NP /NFL /NDL"**.  

If anyone knows a faster combination (other than removing /E, which I need), I'd love to hear.

Another interesting/disappointing thing with robocopy is that if a copy does fail, by default it retries 1,000,000 times with a 30 second delay between each try. If you are running a long batch file unattended, you may be very disappointed when you come back after a few hours to find it's still trying to copy a particular file.

The /R and /W switches let you change this behavior.

  • With /R you can tell it how many times to retry,
  • /W let's you specify the wait time before retries.

If there's a way to attach files here, I can share my results.

  • My tests were all done on the same computer and
  • copied files from one external drive to another external,
  • both on USB 3.0 ports.

I also included FastCopy and Windows Copy in my tests and each test was run 10 times. Note, the differences were pretty significant. The 95% confidence intervals had no overlap.

Best way to store date/time in mongodb

One datestamp is already in the _id object, representing insert time

So if the insert time is what you need, it's already there:

Login to mongodb shell

ubuntu@ip-10-0-1-223:~$ mongo
MongoDB shell version: 2.4.9
connecting to:

Create your database by inserting items

> db.penguins.insert({"penguin": "skipper"})
> db.penguins.insert({"penguin": "kowalski"})

Lets make that database the one we are on now

> use penguins
switched to db penguins

Get the rows back:

> db.penguins.find()
{ "_id" : ObjectId("5498da1bf83a61f58ef6c6d5"), "penguin" : "skipper" }
{ "_id" : ObjectId("5498da28f83a61f58ef6c6d6"), "penguin" : "kowalski" }

Get each row in yyyy-MM-dd HH:mm:ss format:

> db.penguins.find().forEach(function (doc){ d = doc._id.getTimestamp(); print(d.getFullYear()+"-"+(d.getMonth()+1)+"-"+d.getDate() + " " + d.getHours() + ":" + d.getMinutes() + ":" + d.getSeconds()) })
2014-12-23 3:4:41
2014-12-23 3:4:53

If that last one-liner confuses you I have a walkthrough on how that works here:

Including one C source file in another?

The extension of the file does not matter to most C compilers, so it will work.

However, depending on your makefile or project settings the included c file might generate a separate object file. When linking that might lead to double defined symbols.

How to filter rows in pandas by regex

Use contains instead:

In [10]: df.b.str.contains('^f')
0    False
1     True
2     True
3    False
Name: b, dtype: bool

Is there anyway to exclude artifacts inherited from a parent POM?

Don't use a parent pom

This might sound extreme, but the same way "inheritance hell" is a reason some people turn their backs on Object Oriented Programming (or prefer composition over inheritance), remove the problematic <parent> block and copy and paste whatever <dependencies> you need (if your team gives you this liberty).

The assumption that splitting of poms into a parent and child for "reuse" and "avoidance of redunancy" should be ignored and you should serve your immediate needs first (the cure is worst than the disease). Besides, redundancy has its advantages - namely independence of external changes (i.e stability).

This is easier than it sounds if you generate the effective pom (eclipse provides it but you can generate it from the command line with mvn help:effective).


I want to use logback as my slf4j binding, but my parent pom includes the log4j dependency. I don't want to go and have to push the other children's dependence on log4j down into their own pom.xml files so that mine is unobstructed.

ImportError: No module named dateutil.parser

i have same issues on my MacOS and it's work for me to try

pip3 install python-dateutil

on Ubuntu

sudo apt-get install python-dateutil

Check here

How do you sign a Certificate Signing Request with your Certification Authority?

1. Using the x509 module
openssl x509 ...

2 Using the ca module
openssl ca ...

You are missing the prelude to those commands.

This is a two-step process. First you set up your CA, and then you sign an end entity certificate (a.k.a server or user). Both of the two commands elide the two steps into one. And both assume you have a an OpenSSL configuration file already setup for both CAs and Server (end entity) certificates.

First, create a basic configuration file:

$ touch openssl-ca.cnf

Then, add the following to it:

HOME            = .
RANDFILE        = $ENV::HOME/.rnd

[ ca ]
default_ca    = CA_default      # The default ca section

[ CA_default ]

default_days     = 1000         # How long to certify for
default_crl_days = 30           # How long before next CRL
default_md       = sha256       # Use public key default MD
preserve         = no           # Keep passed DN ordering

x509_extensions = ca_extensions # The extensions to add to the cert

email_in_dn     = no            # Don't concat the email in the DN
copy_extensions = copy          # Required to copy SANs from CSR to cert

[ req ]
default_bits       = 4096
default_keyfile    = cakey.pem
distinguished_name = ca_distinguished_name
x509_extensions    = ca_extensions
string_mask        = utf8only

[ ca_distinguished_name ]
countryName         = Country Name (2 letter code)
countryName_default = US

stateOrProvinceName         = State or Province Name (full name)
stateOrProvinceName_default = Maryland

localityName                = Locality Name (eg, city)
localityName_default        = Baltimore

organizationName            = Organization Name (eg, company)
organizationName_default    = Test CA, Limited

organizationalUnitName         = Organizational Unit (eg, division)
organizationalUnitName_default = Server Research Department

commonName         = Common Name (e.g. server FQDN or YOUR name)
commonName_default = Test CA

emailAddress         = Email Address
emailAddress_default = [email protected]

[ ca_extensions ]

subjectKeyIdentifier   = hash
authorityKeyIdentifier = keyid:always, issuer
basicConstraints       = critical, CA:true
keyUsage               = keyCertSign, cRLSign

The fields above are taken from a more complex openssl.cnf (you can find it in /usr/lib/openssl.cnf), but I think they are the essentials for creating the CA certificate and private key.

Tweak the fields above to suit your taste. The defaults save you the time from entering the same information while experimenting with configuration file and command options.

I omitted the CRL-relevant stuff, but your CA operations should have them. See openssl.cnf and the related crl_ext section.

Then, execute the following. The -nodes omits the password or passphrase so you can examine the certificate. It's a really bad idea to omit the password or passphrase.

$ openssl req -x509 -config openssl-ca.cnf -newkey rsa:4096 -sha256 -nodes -out cacert.pem -outform PEM

After the command executes, cacert.pem will be your certificate for CA operations, and cakey.pem will be the private key. Recall the private key does not have a password or passphrase.

You can dump the certificate with the following.

$ openssl x509 -in cacert.pem -text -noout
        Version: 3 (0x2)
        Serial Number: 11485830970703032316 (0x9f65de69ceef2ffc)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, ST=MD, L=Baltimore, CN=Test CA/[email protected]
            Not Before: Jan 24 14:24:11 2014 GMT
            Not After : Feb 23 14:24:11 2014 GMT
        Subject: C=US, ST=MD, L=Baltimore, CN=Test CA/[email protected]
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (4096 bit)
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier:
            X509v3 Authority Key Identifier:

            X509v3 Basic Constraints: critical
            X509v3 Key Usage:
                Certificate Sign, CRL Sign
    Signature Algorithm: sha256WithRSAEncryption

And test its purpose with the following (don't worry about the Any Purpose: Yes; see "critical,CA:FALSE" but "Any Purpose CA : Yes").

$ openssl x509 -purpose -in cacert.pem -inform PEM
Certificate purposes:
SSL client : No
SSL client CA : Yes
SSL server : No
SSL server CA : Yes
Netscape SSL server : No
Netscape SSL server CA : Yes
S/MIME signing : No
S/MIME signing CA : Yes
S/MIME encryption : No
S/MIME encryption CA : Yes
CRL signing : Yes
CRL signing CA : Yes
Any Purpose : Yes
Any Purpose CA : Yes
OCSP helper : Yes
OCSP helper CA : Yes
Time Stamp signing : No
Time Stamp signing CA : Yes

For part two, I'm going to create another configuration file that's easily digestible. First, touch the openssl-server.cnf (you can make one of these for user certificates also).

$ touch openssl-server.cnf

Then open it, and add the following.

HOME            = .
RANDFILE        = $ENV::HOME/.rnd

[ req ]
default_bits       = 2048
default_keyfile    = serverkey.pem
distinguished_name = server_distinguished_name
req_extensions     = server_req_extensions
string_mask        = utf8only

[ server_distinguished_name ]
countryName         = Country Name (2 letter code)
countryName_default = US

stateOrProvinceName         = State or Province Name (full name)
stateOrProvinceName_default = MD

localityName         = Locality Name (eg, city)
localityName_default = Baltimore

organizationName            = Organization Name (eg, company)
organizationName_default    = Test Server, Limited

commonName           = Common Name (e.g. server FQDN or YOUR name)
commonName_default   = Test Server

emailAddress         = Email Address
emailAddress_default = [email protected]

[ server_req_extensions ]

subjectKeyIdentifier = hash
basicConstraints     = CA:FALSE
keyUsage             = digitalSignature, keyEncipherment
subjectAltName       = @alternate_names
nsComment            = "OpenSSL Generated Certificate"

[ alternate_names ]

DNS.1  =
DNS.2  =
DNS.3  =
DNS.4  =

If you are developing and need to use your workstation as a server, then you may need to do the following for Chrome. Otherwise Chrome may complain a Common Name is invalid (ERR_CERT_COMMON_NAME_INVALID). I'm not sure what the relationship is between an IP address in the SAN and a CN in this instance.

# IPv4 localhost
IP.1     =

# IPv6 localhost
IP.2     = ::1

Then, create the server certificate request. Be sure to omit -x509*. Adding -x509 will create a certificate, and not a request.

$ openssl req -config openssl-server.cnf -newkey rsa:2048 -sha256 -nodes -out servercert.csr -outform PEM

After this command executes, you will have a request in servercert.csr and a private key in serverkey.pem.

And you can inspect it again.

$ openssl req -text -noout -verify -in servercert.csr
    verify OK
    Certificate Request:
        Version: 0 (0x0)
        Subject: C=US, ST=MD, L=Baltimore, CN=Test Server/[email protected]
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Exponent: 65537 (0x10001)
        Requested Extensions:
            X509v3 Subject Key Identifier:
            X509v3 Basic Constraints:
            X509v3 Key Usage:
                Digital Signature, Key Encipherment
            X509v3 Subject Alternative Name:
            Netscape Comment:
                OpenSSL Generated Certificate
    Signature Algorithm: sha256WithRSAEncryption

Next, you have to sign it with your CA.

You are almost ready to sign the server's certificate by your CA. The CA's openssl-ca.cnf needs two more sections before issuing the command.

First, open openssl-ca.cnf and add the following two sections.

[ signing_policy ]
countryName            = optional
stateOrProvinceName    = optional
localityName           = optional
organizationName       = optional
organizationalUnitName = optional
commonName             = supplied
emailAddress           = optional

[ signing_req ]
subjectKeyIdentifier   = hash
authorityKeyIdentifier = keyid,issuer
basicConstraints       = CA:FALSE
keyUsage               = digitalSignature, keyEncipherment

Second, add the following to the [ CA_default ] section of openssl-ca.cnf. I left them out earlier, because they can complicate things (they were unused at the time). Now you'll see how they are used, so hopefully they will make sense.

base_dir      = .
certificate   = $base_dir/cacert.pem   # The CA certifcate
private_key   = $base_dir/cakey.pem    # The CA private key
new_certs_dir = $base_dir              # Location for new certs after signing
database      = $base_dir/index.txt    # Database index file
serial        = $base_dir/serial.txt   # The current serial number

unique_subject = no  # Set to 'no' to allow creation of
                     # several certificates with same subject.

Third, touch index.txt and serial.txt:

$ touch index.txt
$ echo '01' > serial.txt

Then, perform the following:

$ openssl ca -config openssl-ca.cnf -policy signing_policy -extensions signing_req -out servercert.pem -infiles servercert.csr

You should see similar to the following:

Using configuration from openssl-ca.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName           :PRINTABLE:'US'
stateOrProvinceName   :ASN.1 12:'MD'
localityName          :ASN.1 12:'Baltimore'
commonName            :ASN.1 12:'Test CA'
emailAddress          :IA5STRING:'[email protected]'
Certificate is to be certified until Oct 20 16:12:39 2016 GMT (1000 days)
Sign the certificate? [y/n]:Y

1 out of 1 certificate requests certified, commit? [y/n]Y
Write out database with 1 new entries
Data Base Updated

After the command executes, you will have a freshly minted server certificate in servercert.pem. The private key was created earlier and is available in serverkey.pem.

Finally, you can inspect your freshly minted certificate with the following:

$ openssl x509 -in servercert.pem -text -noout
        Version: 3 (0x2)
        Serial Number: 9 (0x9)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, ST=MD, L=Baltimore, CN=Test CA/[email protected]
            Not Before: Jan 24 19:07:36 2014 GMT
            Not After : Oct 20 19:07:36 2016 GMT
        Subject: C=US, ST=MD, L=Baltimore, CN=Test Server
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier:
            X509v3 Authority Key Identifier:

            X509v3 Basic Constraints:
            X509v3 Key Usage:
                Digital Signature, Key Encipherment
            X509v3 Subject Alternative Name:
            Netscape Comment:
                OpenSSL Generated Certificate
    Signature Algorithm: sha256WithRSAEncryption

Earlier, you added the following to CA_default: copy_extensions = copy. This copies extension provided by the person making the request.

If you omit copy_extensions = copy, then your server certificate will lack the Subject Alternate Names (SANs) like and

If you use copy_extensions = copy, but don't look over the request, then the requester might be able to trick you into signing something like a subordinate root (rather than a server or user certificate). Which means he/she will be able to mint certificates that chain back to your trusted root. Be sure to verify the request with openssl req -verify before signing.

If you omit unique_subject or set it to yes, then you will only be allowed to create one certificate under the subject's distinguished name.

unique_subject = yes            # Set to 'no' to allow creation of
                                # several ctificates with same subject.

Trying to create a second certificate while experimenting will result in the following when signing your server's certificate with the CA's private key:

Sign the certificate? [y/n]:Y
failed to update database
TXT_DB error number 2

So unique_subject = no is perfect for testing.

If you want to ensure the Organizational Name is consistent between self-signed CAs, Subordinate CA and End-Entity certificates, then add the following to your CA configuration files:

[ policy_match ]
organizationName = match

If you want to allow the Organizational Name to change, then use:

[ policy_match ]
organizationName = supplied

There are other rules concerning the handling of DNS names in X.509/PKIX certificates. Refer to these documents for the rules:

RFC 6797 and RFC 7469 are listed, because they are more restrictive than the other RFCs and CA/B documents. RFC's 6797 and 7469 do not allow an IP address, either.

conflicting types for 'outchar'

In C, the order that you define things often matters. Either move the definition of outchar to the top, or provide a prototype at the top, like this:

#include <stdio.h> #include <stdlib.h>  void outchar(char ch);  int main() {     outchar('A');     outchar('B');     outchar('C');     return 0; }  void outchar(char ch) {     printf("%c", ch); } 

Also, you should be specifying the return type of every function. I added that for you.

Change Activity's theme programmatically

I have used this code to implement dark worked fine for me...You can use it in a switch on....listener...

//setting up Night Mode...
//Store current mode in a sharedprefernce to retrieve on restarting app
            editor.putBoolean("NightMode", true);
//restart all the activities to apply changed mode...
                    .addNextIntent(new Intent(getActivity(), MainActivity.class))

Check if all elements in a list are identical

Use itertools.groupby (see the itertools recipes):

from itertools import groupby
def all_equal(iterable):
    g = groupby(iterable)
    return next(g, True) and not next(g, False)

or without groupby:

def all_equal(iterator):
    iterator = iter(iterator)
        first = next(iterator)
    except StopIteration:
        return True
    return all(first == rest for rest in iterator)

There are a number of alternative one-liners you might consider:

  1. Converting the input to a set and checking that it only has one or zero (in case the input is empty) items

    def all_equal2(iterator):
        return len(set(iterator)) <= 1
  2. Comparing against the input list without the first item

    def all_equal3(lst):
        return lst[:-1] == lst[1:]
  3. Counting how many times the first item appears in the list

    def all_equal_ivo(lst):
        return not lst or lst.count(lst[0]) == len(lst)
  4. Comparing against a list of the first element repeated

    def all_equal_6502(lst):
        return not lst or [lst[0]]*len(lst) == lst

But they have some downsides, namely:

  1. all_equal and all_equal2 can use any iterators, but the others must take a sequence input, typically concrete containers like a list or tuple.
  2. all_equal and all_equal3 stop as soon as a difference is found (what is called "short circuit"), whereas all the alternatives require iterating over the entire list, even if you can tell that the answer is False just by looking at the first two elements.
  3. In all_equal2 the content must be hashable. A list of lists will raise a TypeError for example.
  4. all_equal2 (in the worst case) and all_equal_6502 create a copy of the list, meaning you need to use double the memory.

On Python 3.9, using perfplot, we get these timings (lower Runtime [s] is better):

for a list with a difference in the first two elements, groupby is fastestfor a list with no differences, count(l[0]) is fastest

"Comparison method violates its general contract!"

Your comparator is not transitive.

Let A be the parent of B, and B be the parent of C. Since A > B and B > C, then it must be the case that A > C. However, if your comparator is invoked on A and C, it would return zero, meaning A == C. This violates the contract and hence throws the exception.

It's rather nice of the library to detect this and let you know, rather than behave erratically.

One way to satisfy the transitivity requirement in compareParents() is to traverse the getParent() chain instead of only looking at the immediate ancestor.

ASP.NET MVC: What is the correct way to redirect to pages/actions in MVC?

1) To redirect to the login page / from the login page, don't use the Redirect() methods. Use FormsAuthentication.RedirectToLoginPage() and FormsAuthentication.RedirectFromLoginPage() !

2) You should just use RedirectToAction("action", "controller") in regular scenarios.. You want to redirect in side the Initialize method? Why? I don't see why would you ever want to do this, and in most cases you should review your approach imo.. If you want to do this for authentication this is DEFINITELY the wrong way (with very little chances foe an exception) Use the [Authorize] attribute on your controller or method instead :)

UPD: if you have some security checks in the Initialise method, and the user doesn't have access to this method, you can do a couple of things: a)

Response.StatusCode = 403;

This will send the user back to the login page. If you want to send him to a custom location, you can do something like this (cautios: pseudocode)

Response.Redirect(Url.Action("action", "controller"));

No need to specify the full url. This should be enough. If you completely insist on the full url:

Response.Redirect(new Uri(Request.Url, Url.Action("action", "controller")).ToString());

How do I do a multi-line string in node.js?

As an aside to what folks have been posting here, I've heard that concatenation can be much faster than join in modern javascript vms. Meaning:

var a = 
[ "hey man, this is on a line",
  "and this is on another",
  "and this is on a third"

Will be slower than:

var a = "hey man, this is on a line\n" + 
        "and this is on another\n" +
        "and this is on a third";    

In certain cases.

As another aside, I find this one of the more appealing features in Coffeescript. Yes, yes, I know, haters gonna hate.

html = '''
         cup of coffeescript

Its especially nice for html snippets. I'm not saying its a reason to use it, but I do wish it would land in ecma land :-(.


how to implement Pagination in reactJs

Give you a pagination component, which is maybe a little difficult to understand for newbie to react:

SQL Server GROUP BY datetime ignore hour minute and a select with a date and sum value

I came researching the options that I would have to do this, however, I believe the method I use is the simplest:

       DATEADD(dd, DATEDIFF(dd, 0, date_field),0) as dtgroup 
GROUP BY DATEADD(dd, DATEDIFF(dd, 0, date_field),0) 
ORDER BY dtgroup ASC;

How to log SQL statements in Spring Boot?

Log in to standard output

Add to

### to enable
### to make the printing SQL beautify

This the simplest way to print the SQL queries though it doesn't log the parameters of prepared statements. And its is not recommended since its not such as optimized logging framework.

Using Logging Framework

Add to

### logs the SQL queries
### logs the prepared statement parameters
### to make the printing SQL beautify

By specifying above properties, logs entries will be sent to the configured log appender such as log-back or log4j.

TypeError: window.initMap is not a function

I had a similar error. The answers here helped me figure out what to do.


 <!--The div element for the map -->
 <div id="map"></div>

<!--The link to external javascript file that has initMap() function-->
 <script src="main.js">

<!--Google api, this calls initMap() function-->
 <script async defer src="">

main.js // This gives error

// The initMap function has not been executed
const initMap = () => {
const mapDisplayElement = document.getElementById('map');
  // The address is Uluru
const address = {lat: -25.344, lng: 131.036};
  // The zoom property specifies the zoom level for the map. Zoom: 0 is the lowest zoom,and displays the entire earth.
const map = new google.maps.Map(mapDisplayElement, { zoom: 4, center: address });
const marker = new google.maps.Marker({ position: address, map });

The answers here helped me figure out a solution. I used an immediately invoked the function (IIFE ) to work around it.

The error is as at the time of calling the google maps api the initMap() function has not executed.

main.js // This works

const mapDisplayElement = document.getElementById('map');
// The address is Uluru
// Run the initMap() function imidiately, 
(initMap = () => {
  const address = {lat: -25.344, lng: 131.036};
  // The zoom property specifies the zoom level for the map. Zoom: 0 is the lowest zoom,and displays the entire earth.
  const map = new google.maps.Map(mapDisplayElement, { zoom: 4, center: address });
  const marker = new google.maps.Marker({ position: address, map });

Is there a simple way to remove multiple spaces in a string?

You can also use the string splitting technique in a Pandas DataFrame without needing to use .apply(..), which is useful if you need to perform the operation quickly on a large number of strings. Here it is on one line:

df['message'] = (df['message'].str.split()).str.join(' ')

UndefinedMetricWarning: F-score is ill-defined and being set to 0.0 in labels with no predicted samples

As I have noticed this error occurs under two circumstances,

  1. If you have used train_test_split() to split your data, you have to make sure that you reset the index of the data (specially when taken using a pandas series object): y_train, y_test indices should be resetted. The problem is when you try to use one of the scores from sklearn.metrics such as; precision_score, this will try to match the shuffled indices of the y_test that you got from train_test_split().

so use, either np.array(y_test) for y_true in scores or y_test.reset_index(drop=True)

  1. Then again you can still have this error if your predicted 'True Positives' is 0, which is used for precision, recall and f1_scores. You can visualize this using a confusion_matrix. If the classification is multilabel and you set param: average='weighted'/micro/macro you will get an answer as long as the diagonal line in the matrix is not 0

Hope this helps.

Unstaged changes left after git reset --hard

Another possibility that I encountered was that one of the packages in the repository ended up with a detached HEAD. If none of the answer here helps and you encounter a git status message like this you might have the same problem:

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   path/to/package (new commits)

Going into the path/to/package folder a git status should yield the following result:

HEAD detached at 7515f05

And the following command should then fix the issue, where master should be replaced by your local branch:

git checkout master

And you'll get a message that your local branch will be some amounts of commits behind the remote branch. git pull and you should be out of the woods!

How often should you use git-gc?

Note that the downside of garbage-collecting your repository is that, well, the garbage gets collected. As we all know as computer users, files we consider garbage right now might turn out to be very valuable three days in the future. The fact that git keeps most of its debris around has saved my bacon several times – by browsing all the dangling commits, I have recovered much work that I had accidentally canned.

So don’t be too much of a neat freak in your private clones. There’s little need for it.

OTOH, the value of data recoverability is questionable for repos used mainly as remotes, eg. the place all the devs push to and/or pulled from. There, it might be sensible to kick off a GC run and a repacking frequently.

Difference between adjustResize and adjustPan in android?

As doc says also keep in mind the correct value combination:

The setting must be one of the values listed in the following table, or a combination of one "state..." value plus one "adjust..." value. Setting multiple values in either group — multiple "state..." values, for example — has undefined results. Individual values are separated by a vertical bar (|). For example:

<activity android:windowSoftInputMode="stateVisible|adjustResize" . . . >

AND/OR in Python?

if input == 'a':
    for char in 'abc':
        if char in some_list:

Creating a chart in Excel that ignores #N/A or blank cells

Best way is use Empty

Dim i as Integer
For i = 1 to 1000
    If CPT_DB.Cells(i, 1) > 100 Then
       CPT_DB.Cells(i, 2) = CPT_DB.Cells(i, 1)
       CPT_DB.Cells(i, 2) = Empty //**********************
    End If
Next i

How to write "not in ()" sql query using join

I would opt for NOT EXISTS in this case.

SELECT D1.ShortCode
FROM Domain1 D1
    (SELECT 'X'
     FROM Domain2 D2
     WHERE D2.ShortCode = D1.ShortCode