Programs & Examples On #Xinc

Xinc is a continuous integration server written in PHP 5

pip is not able to install packages correctly: Permission denied error

Set up a virtualenv:

% curl -kLso /tmp/ 
% sudo python /tmp/

These commands install pip into the global site-packages directory.

% sudo pip install virtualenv

and ditto for virtualenv:

% mkdir -p ~/.virtualenvs

I like my virtualenvs under one tree in my home directory called .virtualenvs

% virtualenv ~/.virtualenvs/lxmltest

Creates a virtualenv.

% . ~/.virtualenvs/lxmltest/bin/activate

Removes the need to specify the full path to pip/python in this virtualenv.

% pip install lxml

Alternatively execute ~/.virtualenvs/lxmltest/bin/pip install lxml if you chose not to follow the previous step. Note, I'm not sure how far along you are, so some of these steps can be safely skipped. Of course, if you mess something up, you can always rm -Rf ~/.virtualenvs/lxmltest and start again from a new virtualenv.

What does elementFormDefault do in XSD?

I have noticed that XMLSpy(at least 2011 version)needs a targetNameSpace defined if elementFormDefault="qualified" is used. Otherwise won't validate. And also won't generate xmls with namespace prefixes

How to make a smaller RatingBar?

                    style = "?android:attr/ratingBarStyleSmall"

// if you want to style 

 <style name="RatingBar" parent="Theme.AppCompat">
        <item name="colorControlNormal">@color/colorPrimary</item>
        <item name="colorControlActivated">@color/colorAccent</item>

// add these line for small rating bar

style = "?android:attr/ratingBarStyleSmall"

C# - Insert a variable number of spaces into a string? (Formatting an output file)

Just for kicks, here's the functions I wrote to do it before I had the .PadRight bit:

    public string insertSpacesAtEnd(string input, int longest)
        string output = input;
        string spaces = "";
        int inputLength = input.Length;
        int numToInsert = longest - inputLength;

        for (int i = 0; i < numToInsert; i++)
            spaces += " ";

        output += spaces;

        return output;

    public int findLongest(List<Results> theList)
        int longest = 0;

        for (int i = 0; i < theList.Count; i++)
            if (longest < theList[i].title.Length)
                longest = theList[i].title.Length;
        return longest;

    for (int i = 0; i < storageList.Count; i++)
        output += insertSpacesAtEnd(storageList[i].title, longest + 5) +   storageList[i].rank.Trim() + "     " + storageList[i].term.Trim() + "         " + storageList[i].name + "\r\n";

Command / failed with exit code 1

Go to target preferences, summary tab, find "Deployment target" and increase it.

Format XML string to print friendly XML string

This one, from kristopherjohnson is heaps better:

  1. It doesn't require an XML document header either.
  2. Has clearer exceptions
  3. Adds extra behaviour options: OmitXmlDeclaration = true, NewLineOnAttributes = true
  4. Less lines of code

    static string PrettyXml(string xml)
        var stringBuilder = new StringBuilder();
        var element = XElement.Parse(xml);
        var settings = new XmlWriterSettings();
        settings.OmitXmlDeclaration = true;
        settings.Indent = true;
        settings.NewLineOnAttributes = true;
        using (var xmlWriter = XmlWriter.Create(stringBuilder, settings))
        return stringBuilder.ToString();

Apply a theme to an activity in Android?

To set it programmatically in

public void onCreate(Bundle savedInstanceState) {


  setTheme(; // (for Custom theme)
  setTheme(; // (for Android Built In Theme)


To set in Application scope in Manifest.xml (all activities):


To set in Activity scope in Manifest.xml (single activity):


To build a custom theme, you will have to declare theme in themes.xml file, and set styles in styles.xml file.

Does a finally block always get executed in Java?

Here's an elaboration of Kevin's answer. It's important to know that the expression to be returned is evaluated before finally, even if it is returned after.

public static void main(String[] args) {

public static int printX() {
    return 0;

public static int test() {
    try {
        return printX();
    finally {
        System.out.println("finally trumps return... sort of");


finally trumps return... sort of

Can Flask have optional URL parameters?

Almost the same as skornos, but with variable declarations for a more explicit answer. It can work with Flask-RESTful extension:

from flask import Flask
from flask_restful import Resource, Api

app = Flask(__name__)
api = Api(app)

class UserAPI(Resource):
    def show(userId, username=None):

api.add_resource(UserAPI, '/<userId>', '/<userId>/<username>', endpoint='user')

if __name__ == '__main__':

The add_resource method allows pass multiples URLs. Each one will be routed to your Resource.

Java: Date from unix timestamp

Date's constructor expects the timeStamp value to be in milliseconds. Multiply your timestamp's value with 1000, then pass it to the constructor.

java - path to trustStore - set property doesn't work?

Looks like you have a typo -- "trustStrore" should be "trustStore", i.e.

System.setProperty("", "cacerts.jks");

should be:

System.setProperty("", "cacerts.jks");

Blurry text after using CSS transform: scale(); in Chrome

Try using zoom: 101%; for complex designs when you can't use a combination of zoom + scale.

How do I programmatically set device orientation in iOS 7?

This works for me on Xcode 6 & 5.

- (BOOL)shouldAutorotate {
    return YES;
- (NSUInteger)supportedInterfaceOrientations {
    return (UIInterfaceOrientationMaskPortrait);

Python read in string from file and split it into values

Something like this - for each line read into string variable a:

>>> a = "123,456"
>>> b = a.split(",")
>>> b
['123', '456']
>>> c = [int(e) for e in b]
>>> c
[123, 456]
>>> x, y = c
>>> x
>>> y

Now you can do what is necessary with x and y as assigned, which are integers.

data.frame Group By column

I would recommend having a look at the plyr package. It might not be as fast as data.table or other packages, but it is quite instructive, especially when starting with R and having to do some data manipulation.

> DF <- data.frame(A = c("1", "1", "2", "3", "3"), B = c(2, 3, 3, 5, 6))
> library(plyr)
> DF.sum <- ddply(DF, c("A"), summarize, B = sum(B))
> DF.sum
  A  B
1 1  5
2 2  3
3 3 11

Convert a byte array to integer in Java and vice versa

byte[] toByteArray(int value) {
     return  ByteBuffer.allocate(4).putInt(value).array();

byte[] toByteArray(int value) {
    return new byte[] { 
        (byte)(value >> 24),
        (byte)(value >> 16),
        (byte)(value >> 8),
        (byte)value };

int fromByteArray(byte[] bytes) {
     return ByteBuffer.wrap(bytes).getInt();
// packing an array of 4 bytes to an int, big endian, minimal parentheses
// operator precedence: <<, &, | 
// when operators of equal precedence (here bitwise OR) appear in the same expression, they are evaluated from left to right
int fromByteArray(byte[] bytes) {
     return bytes[0] << 24 | (bytes[1] & 0xFF) << 16 | (bytes[2] & 0xFF) << 8 | (bytes[3] & 0xFF);

// packing an array of 4 bytes to an int, big endian, clean code
int fromByteArray(byte[] bytes) {
     return ((bytes[0] & 0xFF) << 24) | 
            ((bytes[1] & 0xFF) << 16) | 
            ((bytes[2] & 0xFF) << 8 ) | 
            ((bytes[3] & 0xFF) << 0 );

When packing signed bytes into an int, each byte needs to be masked off because it is sign-extended to 32 bits (rather than zero-extended) due to the arithmetic promotion rule (described in JLS, Conversions and Promotions).

There's an interesting puzzle related to this described in Java Puzzlers ("A Big Delight in Every Byte") by Joshua Bloch and Neal Gafter . When comparing a byte value to an int value, the byte is sign-extended to an int and then this value is compared to the other int

byte[] bytes = (…)
if (bytes[0] == 0xFF) {
   // dead code, bytes[0] is in the range [-128,127] and thus never equal to 255

Note that all numeric types are signed in Java with exception to char being a 16-bit unsigned integer type.

Convert audio files to mp3 using ffmpeg

1) wav to mp3

ffmpeg -i audio.wav -acodec libmp3lame audio.mp3

2) ogg to mp3

ffmpeg -i audio.ogg -acodec libmp3lame audio.mp3

3) ac3 to mp3

ffmpeg -i audio.ac3 -acodec libmp3lame audio.mp3

4) aac to mp3

ffmpeg -i audio.aac -acodec libmp3lame audio.mp3

Manually highlight selected text in Notepad++

"Select your text, right click, then choose Style Token and then using 1st style (2nd style, etc …). At the moment is not possible to save the style tokens but there is an idea pending on Idea torrent you may vote for if your are interested in that."

It should be default, but it might be hidden.

"It might be that something happened to your contextMenu.xml so that you only get the basic standard. Have a look in NPPs config folder (%appdata%\Notepad++\) if the contextMenu.xml is there. If no: that would be the answer; if yes: it might be defect. Anyway you can grab the original standart contextMenu.xml from here and place it into the config folder (or replace the existing xml). Start NPP and you should have quite a long context menu. Tip: have a look at the contextmenu.xml itself - because you're allowed to change it to your own needs."

See this for more information

How do you list all triggers in a MySQL database?

You can use below to find a particular trigger definition.

SHOW TRIGGERS LIKE '%trigger_name%'\G

or the below to show all the triggers in the database. It will work for MySQL 5.0 and above.


How can I disable the default console handler, while using the java logging API?

You must instruct your logger not to send its messages on up to its parent logger:

import java.util.logging.*;
Logger logger = Logger.getLogger(this.getClass().getName());

However, this should be done before adding any more handlers to logger.

Recursion or Iteration?

I'm going to answer your question by designing a Haskell data structure by "induction", which is a sort of "dual" to recursion. And then I will show how this duality leads to nice things.

We introduce a type for a simple tree:

data Tree a = Branch (Tree a) (Tree a)
            | Leaf a
            deriving (Eq)

We can read this definition as saying "A tree is a Branch (which contains two trees) or is a leaf (which contains a data value)". So the leaf is a sort of minimal case. If a tree isn't a leaf, then it must be a compound tree containing two trees. These are the only cases.

Let's make a tree:

example :: Tree Int
example = Branch (Leaf 1) 
                 (Branch (Leaf 2) 
                         (Leaf 3))

Now, let's suppose we want to add 1 to each value in the tree. We can do this by calling:

addOne :: Tree Int -> Tree Int
addOne (Branch a b) = Branch (addOne a) (addOne b)
addOne (Leaf a)     = Leaf (a + 1)

First, notice that this is in fact a recursive definition. It takes the data constructors Branch and Leaf as cases (and since Leaf is minimal and these are the only possible cases), we are sure that the function will terminate.

What would it take to write addOne in an iterative style? What will looping into an arbitrary number of branches look like?

Also, this kind of recursion can often be factored out, in terms of a "functor". We can make Trees into Functors by defining:

instance Functor Tree where fmap f (Leaf a)     = Leaf (f a)
                            fmap f (Branch a b) = Branch (fmap f a) (fmap f b)

and defining:

addOne' = fmap (+1)

We can factor out other recursion schemes, such as the catamorphism (or fold) for an algebraic data type. Using a catamorphism, we can write:

addOne'' = cata go where
           go (Leaf a) = Leaf (a + 1)
           go (Branch a b) = Branch a b

How do I render a shadow?

You have to give elevation prop to View

<View elevation={5} style={styles.container}>
   <Text>Hello World !</Text>

styles can be added like this:

 const styles = StyleSheet.create({

        shadowColor: "#000000",
        shadowOpacity: 0.8,
        shadowRadius: 2,
        shadowOffset: {
          height: 1,
          width: 1

Make javascript alert Yes/No Instead of Ok/Cancel

I shall try the solution with jQuery, for sure it should give a nice result. Of course you have to load jQuery ... What about a pop-up with something like this? Of course this is dependant on the user authorizing pop-ups.

    <script language="javascript">
    var ret;
    function returnfunction()
            <label id="QuestionToAsk" name="QuestionToAsk">Here is talked.</label><br />
            <input type="button" value="Yes" name="yes" onClick="ret=true;returnfunction()" />
            <input type="button" value="No" onClick="ret=false;returnfunction()" />

How do I calculate someone's age in Java?

JDK 8 makes this easy and elegant:

public class AgeCalculator {

    public static int calculateAge(LocalDate birthDate, LocalDate currentDate) {
        if ((birthDate != null) && (currentDate != null)) {
            return Period.between(birthDate, currentDate).getYears();
        } else {
            return 0;

A JUnit test to demonstrate its use:

public class AgeCalculatorTest {

    public void testCalculateAge_Success() {
        // setup
        LocalDate birthDate = LocalDate.of(1961, 5, 17);
        // exercise
        int actual = AgeCalculator.calculateAge(birthDate, LocalDate.of(2016, 7, 12));
        // assert
        Assert.assertEquals(55, actual);

Everyone should be using JDK 8 by now. All earlier versions have passed the end of their support lives.

How to use Monitor (DDMS) tool to debug application

I think things (location) have changed little bit. For: Android Studio Build @AI-141.1903250 - built on May 5, 2015

Franco Rondinis answer should be

To track memory allocation of objects:

  1. Start your app as described in Run Your App in Debug Mode.
  2. Click Android to open the Android DDMS tool window.
  3. Select your device from the dropdown list.
  4. Select your app by its package name from the list of running apps.
  5. On the Android DDMS tool window, select Memory tab.
  6. Click Start Allocation Tracking Interact with your app on the device. Click Stop Allocation Tracking (same icon)

how to start allocation tracking in android studio

Change UITableView height dynamically

for resizing my table I went with this solution in my tableview controller witch is perfectly fine:

[objectManager getObjectsAtPath:self.searchURLString
                            success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
                                NSArray* results = [mappingResult array];
                                self.eventArray = results;
                                NSLog(@"Events number at first: %i", [self.eventArray count]);
                                CGRect newFrame = self.activityFeedTableView.frame;
                                newFrame.size.height = self.cellsHeight + 30.0;
                                self.activityFeedTableView.frame = newFrame;

                                self.cellsHeight = 0.0;

                            failure:^(RKObjectRequestOperation *operation, NSError *error) {
                                UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
                                                                                message:[error localizedDescription]
                                [alert show];
                                NSLog(@"Hit error: %@", error);

The resizing part is in a method but here is just so you can see it. Now the only problem I haveis resizing the scroll view in the other view controller as I have no idea when the tableview has finished resizing. At the moment I'm doing it with performSelector: afterDelay: but this is really not a good way to do it. Any ideas?

Aggregate function in SQL WHERE-Clause

UPDATED query:

select id from t where id < (select max(id) from t);

It'll select all but the last row from the table t.

How to hide Bootstrap modal with javascript?

I was experiencing with that same error and this line of code really helps me.

$("[data-dismiss=modal]").trigger({ type: "click" });

Angular JS update input field after change

I'm guessing that when you enter a value into the totals field that value expression somehow gets overwritten.

However, you can take an alternative approach: Create a field for the total value and when either one or two changes update that field.

<li>Total <input type="text" ng-model="total">{{total}}</li>

And change the javascript:

function TodoCtrl($scope) {
    $scope.$watch('one * two', function (value) {
        $ = value;

Example fiddle here.

How to concatenate and minify multiple CSS and JavaScript files with Grunt.js (0.3.x)

I think may be more automatic, grunt task usemin take care to do all this jobs for you, only need some configuration:

Changing the page title with Jquery


$('title').html("new title");

Composer Warning: openssl extension is missing. How to enable in WAMP

you need to edit the "c:\Program Files\wamp\bin\php\php5.3.13\php.ini" file search for: ;extension=php_openssl.dll

remove the semicolon at the beginning

note: if saving the file doesn't work then you need to edit it as administrator. (on win7) go to start menu, search for notepad, right-click on notepad, click "Run As Administrator"

in the composer installation windows just click back then next (or close it and start again) and it should work

How to exclude a directory from ant fileset, based on directories contents

Here's an alternative, instead of adding an incomplete.flag file to every dir you want to exclude, generate a file that contains a listing of all the directories you want to exclude and then use the excludesfile attribute. Something like this:

<fileset dir="${basedir}" excludesfile="">
  <include name="locale/"/>
  <exclude name="locale/*/incomplete.flag">

Hope it helps.

How to Set Variables in a Laravel Blade Template

There is a very good extention for Blade radic/blade-extensions. After you add it you can use @set(variable_name, variable_value)

@set(var, 33)

Getting key with maximum value in dictionary?

To get the maximum key/value of the dictionary stats:

stats = {'a':1000, 'b':3000, 'c': 100}
  • Based on keys

>>> max(stats.items(), key = lambda x: x[0]) ('c', 100)

  • Based on values

>>> max(stats.items(), key = lambda x: x[1]) ('b', 3000)

Of course, if you want to get only the key or value from the result, you can use tuple indexing. For Example, to get the key corresponding to the maximum value:

>>> max(stats.items(), key = lambda x: x[1])[0] 'b'


The dictionary method items() in Python 3 returns a view object of the dictionary. When this view object is iterated over, by the max function, it yields the dictionary items as tuples of the form (key, value).

>>> list(stats.items()) [('c', 100), ('b', 3000), ('a', 1000)]

When you use the lambda expression lambda x: x[1], in each iteration, x is one of these tuples (key, value). So, by choosing the right index, you select whether you want to compare by keys or by values.

Python 2

For Python 2.2+ releases, the same code will work. However, it is better to use iteritems() dictionary method instead of items() for performance.


Please help me convert this script to a simple image slider

Problems only surface when I am I trying to give the first loaded content an active state

Does this mean that you want to add a class to the first button?

$('.o-links').click(function(e) {   // ... }).first().addClass('O_Nav_Current'); 

instead of using IDs for the slider's items and resetting html contents you can use classes and indexes:


.image-area {     width: 100%;     height: auto;     display: none; }  .image-area:first-of-type {     display: block; } 


var $slides = $('.image-area'),     $btns = $('a.o-links');  $btns.on('click', function (e) {     var i = $btns.removeClass('O_Nav_Current').index(this);     $(this).addClass('O_Nav_Current');      $slides.filter(':visible').fadeOut(1000, function () {         $slides.eq(i).fadeIn(1000);     });      e.preventDefault();  }).first().addClass('O_Nav_Current');

Making Maven run all tests, even when some fail

From the Maven Embedder documentation:

-fae,--fail-at-end Only fail the build afterwards; allow all non-impacted builds to continue

-fn,--fail-never NEVER fail the build, regardless of project result

So if you are testing one module than you are safe using -fae.

Otherwise, if you have multiple modules, and if you want all of them tested (even the ones that depend on the failing tests module), you should run mvn clean install -fn.
-fae will continue with the module that has a failing test (will run all other tests), but all modules that depend on it will be skipped.

Nested rows with bootstrap grid system?

Adding to what @KyleMit said, consider using:

  • col-md-* classes for the larger outer columns
  • col-xs-* classes for the smaller inner columns

This will be useful when you view the page on different screen sizes.

On a small screen, the wrapping of larger outer columns will then happen while maintaining the smaller inner columns, if possible

Javascript: How to loop through ALL DOM elements on a page?

i think this is really quick

document.querySelectorAll('body,body *').forEach(function(e) {

Why is an OPTIONS request sent and can I disable it?

For a developer who understands the reason it exists but needs to access an API that doesn't handle OPTIONS calls without auth, I need a temporary answer so I can develop locally until the API owner adds proper SPA CORS support or I get a proxy API up and running.

I found you can disable CORS in Safari and Chrome on a Mac.

Disable same origin policy in Chrome

Chrome: Quit Chrome, open an terminal and paste this command: open /Applications/Google\ --args --disable-web-security --user-data-dir

Safari: Disabling same-origin policy in Safari

If you want to disable the same-origin policy on Safari (I have 9.1.1), then you only need to enable the developer menu, and select "Disable Cross-Origin Restrictions" from the develop menu.

Are multi-line strings allowed in JSON?

Unfortunately many of the answers here address the question of how to put a newline character in the string data. The question is how to make the code look nicer by splitting the string value across multiple lines of code. (And even the answers that recognize this provide "solutions" that assume one is free to change the data representation, which in many cases one is not.)

And the worse news is, there is no good answer.

In many programming languages, even if they don't explicitly support splitting strings across lines, you can still use string concatenation to get the desired effect; and as long as the compiler isn't awful this is fine.

But json is not a programming language; it's just a data representation. You can't tell it to concatenate strings. Nor does its (fairly small) grammar include any facility for representing a string on multiple lines.

Short of devising a pre-processor of some kind (and I, for one, don't feel like effectively making up my own language to solve this issue), there isn't a general solution to this problem. IF you can change the data format, then you can substitute an array of strings. Otherwise, this is one of the numerous ways that json isn't designed for human-readability.

Iterating over JSON object in C#

You can use the JsonTextReader to read the JSON and iterate over the tokens:

using (var reader = new JsonTextReader(new StringReader(jsonText)))
    while (reader.Read())
        Console.WriteLine("{0} - {1} - {2}", 
                          reader.TokenType, reader.ValueType, reader.Value);

Optional Parameters in Go?

You can encapsulate this quite nicely in a func similar to what is below.

package main

import (

func main() {

func prompt(params ...string) string {
        prompt := ": "
        if len(params) > 0 {
                prompt = params[0]
        reader := bufio.NewReader(os.Stdin)
        text, _ := reader.ReadString('\n')
        return text

In this example, the prompt by default has a colon and a space in front of it . . .


. . . however you can override that by supplying a parameter to the prompt function.

prompt("Input here -> ")

This will result in a prompt like below.

Input here ->

How do I drop a function if it already exists?

      (SELECT * 
      FROM schema.sys.objects
      WHERE name = 'func_name')
    DROP FUNCTION [dbo].[func_name]

How do you POST to a page using the PHP header() function?

There is a good class that does what you want. It can be downloaded at:

CUSTOM_ELEMENTS_SCHEMA added to NgModule.schemas still showing Error

solved this problem in the /app/app.module.ts file

import your component and declare it

import { MyComponent } from './home-about-me/my.component';

  declarations: [

error C4996: 'scanf': This function or variable may be unsafe in c programming

It sounds like it's just a compiler warning.

Usage of scanf_s prevents possible buffer overflow.

Good explanation as to why scanf can be dangerous: Disadvantages of scanf

So as suggested, you can try replacing scanf with scanf_s or disable the compiler warning.

Call to undefined function mysql_connect

I think that you should use mysqli_connect instead of mysql_connect

Running script upon login mac

tl;dr: use OSX's native process launcher and manager, launchd.

To do so, make a launchctl daemon. You'll have full control over all aspects of the script. You can run once or keep alive as a daemon. In most cases, this is the way to go.

  1. Create a .plist file according to the instructions in the Apple Dev docs here or more detail below.
  2. Place in ~/Library/LaunchAgents
  3. Log in (or run manually via launchctl load [filename.plist])

For more on launchd, the wikipedia article is quite good and describes the system and its advantages over other older systems.

Here's the specific plist file to run a script at login.

Updated 2017/09/25 for OSX El Capitan and newer (credit to José Messias Jr):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "">
<plist version="1.0">

Replace the <string> after the Program key with your desired command (note that any script referenced by that command must be executable: chmod a+x /path/to/executable/ to ensure it is for all users).

Save as ~/Library/LaunchAgents/com.user.loginscript.plist

Run launchctl load ~/Library/LaunchAgents/com.user.loginscript.plist and log out/in to test (or to test directly, run launchctl start com.user.loginscript)

Tail /var/log/system.log for error messages.

The key is that this is a User-specific launchd entry, so it will be run on login for the given user. System-specific launch daemons (placed in /Library/LaunchDaemons) are run on boot.

If you want a script to run on login for all users, I believe LoginHook is your only option, and that's probably the reason it exists.

python global name 'self' is not defined

It should be something like:

class Person:
   def setavalue(self, name):         
      self.myname = name      
   def printaname(self):         
      print "Name", self.myname           

def main():
   p = Person()

Default argument values in JavaScript functions

In javascript you can call a function (even if it has parameters) without parameters.

So you can add default values like this:

function func(a, b){
   if (typeof(a)==='undefined') a = 10;
   if (typeof(b)==='undefined') b = 20;

   //your code

and then you can call it like func(); to use default parameters.

Here's a test:

function func(a, b){
   if (typeof(a)==='undefined') a = 10;
   if (typeof(b)==='undefined') b = 20;

   alert("A: "+a+"\nB: "+b);

How to solve Error?

First, you need to obtain the public certificate from the server you're trying to connect to. That can be done in a variety of ways, such as contacting the server admin and asking for it, using OpenSSL to download it, or, since this appears to be an HTTP server, connecting to it with any browser, viewing the page's security info, and saving a copy of the certificate. (Google should be able to tell you exactly what to do for your specific browser.)

Now that you have the certificate saved in a file, you need to add it to your JVM's trust store. At $JAVA_HOME/jre/lib/security/ for JREs or $JAVA_HOME/lib/security for JDKs, there's a file named cacerts, which comes with Java and contains the public certificates of the well-known Certifying Authorities. To import the new cert, run keytool as a user who has permission to write to cacerts:

keytool -import -file <the cert file> -alias <some meaningful name> -keystore <path to cacerts file>

It will most likely ask you for a password. The default password as shipped with Java is changeit. Almost nobody changes it. After you complete these relatively simple steps, you'll be communicating securely and with the assurance that you're talking to the right server and only the right server (as long as they don't lose their private key).

proper way to logout from a session in PHP

Personally, I do the following:

setcookie(session_name(), '', 100);
$_SESSION = array();

That way, it kills the cookie, destroys all data stored internally, and destroys the current instance of the session information (which is ignored by session_destroy).

MySQL fails on: mysql "ERROR 1524 (HY000): Plugin 'auth_socket' is not loaded"

Try it: sudo mysql_secure_installation

Work's in Ubuntu 18.04

Passing 'this' to an onclick event

You can always call funciton differently:; in this way you will be able to use this context inside the function.


<button onclick="" id="bar">Button</button>?

var foo = function()
    this.innerHTML = "Not a button";

Git push error pre-receive hook declined

GitLab by default marks master branch as protected (See part Protecting your code in why). If so in your case, then this can help:

Open your project > Settings > Repository and go to "Protected branches", find "master" branch into the list and click "Unprotect" and try again.


For version 8.11 and above how-to here:

Kill python interpeter in linux from the terminal

pkill with script path

pkill -9 -f path/to/

is a short and selective method that is more likely to only kill the interpreter running a given script.

See also:

How to redirect stdout to both file and console with scripting?

Based on Amith Koujalgi's answer, here's a simple module you can use for logging -

Transcript - direct print output to a file, in addition to terminal.

    import transcript
    print("inside file")
    print("outside file")

import sys

class Transcript(object):

    def __init__(self, filename):
        self.terminal = sys.stdout
        self.logfile = open(filename, "a")

    def write(self, message):

    def flush(self):
        # this flush method is needed for python 3 compatibility.
        # this handles the flush command by doing nothing.
        # you might want to specify some extra behavior here.

def start(filename):
    """Start transcript, appending print output to given filename"""
    sys.stdout = Transcript(filename)

def stop():
    """Stop transcript and return print functionality to normal"""
    sys.stdout = sys.stdout.terminal

How do I return a proper success/error message for JQuery .ajax() using PHP?

Server side:

if (mysql_query($query)) {
    // ...
else {

Client side:

error: function() {
    alert("There was an error. Try again please!");
success: function(){
    alert("Thank you for subscribing!");

Counting in a FOR loop using Windows Batch script

for a = 1 to 100 step 1

Command line in Windows . Please use %%a if running in Batch file.

    for /L %a in (1,1,100) Do echo %a 

Add element to a list In Scala

Since you want to append elements to existing list, you can use var List[Int] and then keep on adding elements to the same list. Note -> You have to make sure that you insert an element into existing list as follows:-

var l: List[int] = List() // creates an empty list

l = 3 :: l // adds 3 to the head of the list

l = 4 :: l // makes int 4 as the head of the list

// Now when you will print l, you will see two elements in the list ( 4, 3)

What does 'x packages are looking for funding' mean when running `npm install`?

When you run npm update in the command prompt, when it is done it will recommend you type a new command called npm fund.

When you run npm fund it will list all the modules and packages you have installed that were created by companies or organizations that need money for their IT projects. You will see a list of webpages where you can send them money. So "funds" means "Angular packages you installed that could use some money from you as an option to help support their businesses".

It's basically a list of the modules you have that need contributions or donations of money to their projects and which list websites where you can enter a credit card to help pay for them.

Returning http status code from Web Api controller

I hate bumping old articles but this is the first result for this in google search and I had a heck of a time with this problem (even with the support of you guys). So here goes nothing...

Hopefully my solution will help those that also was confused.

namespace MyApplication.WebAPI.Controllers
    public class BaseController : ApiController
        public T SendResponse<T>(T response, HttpStatusCode statusCode = HttpStatusCode.OK)
            if (statusCode != HttpStatusCode.OK)
                // leave it up to microsoft to make this way more complicated than it needs to be
                // seriously i used to be able to just set the status and leave it at that but nooo... now 
                // i need to throw an exception 
                var badResponse =
                    new HttpResponseMessage(statusCode)
                        Content =  new StringContent(JsonConvert.SerializeObject(response), Encoding.UTF8, "application/json")

                throw new HttpResponseException(badResponse);
            return response;

and then just inherit from the BaseController

public class DeviceManagementController : BaseController

and then using it

public SearchForDeviceResponse SearchForDevice(string property, string value)
    //todo: limit search property here?
    var response = new SearchForDeviceResponse();

    var results = _deviceManagementBusiness.SearchForDevices(property, value);

    response.Success = true;
    response.Data = results;

    var statusCode = results == null || !results.Any() ? HttpStatusCode.NoContent : HttpStatusCode.OK;

    return SendResponse(response, statusCode);

Adding a guideline to the editor in Visual Studio

For those who use Visual Assist, vertical guidelines can be enabled from Display section in Visual Assist's options:

enter image description here

PHP Array to JSON Array using json_encode();

If the array keys in your PHP array are not consecutive numbers, json_encode() must make the other construct an object since JavaScript arrays are always consecutively numerically indexed.

Use array_values() on the outer structure in PHP to discard the original array keys and replace them with zero-based consecutive numbering:


// Non-consecutive 3number keys are OK for PHP
// but not for a JavaScript array
$array = array(
  2 => array("Afghanistan", 32, 13),
  4 => array("Albania", 32, 12)

// array_values() removes the original keys and replaces
// with plain consecutive numbers
$out = array_values($array);
// [["Afghanistan", 32, 13], ["Albania", 32, 12]]

How to define optional methods in Swift protocol?

Here is a concrete example with the delegation pattern.

Setup your Protocol:

@objc protocol MyProtocol:class
    func requiredMethod()
    optional func optionalMethod()

class MyClass: NSObject
    weak var delegate:MyProtocol?

    func callDelegate()

Set the delegate to a class and implement the Protocol. See that the optional method does not need to be implemented.

class AnotherClass: NSObject, MyProtocol

        let myInstance = MyClass()
        myInstance.delegate = self

    func requiredMethod()

One important thing is that the optional method is optional and needs a "?" when calling. Mention the second question mark.


Parallel foreach with asynchronous lambda

I've created an extension method for this which makes use of SemaphoreSlim and also allows to set maximum degree of parallelism

    /// <summary>
    /// Concurrently Executes async actions for each item of <see cref="IEnumerable<typeparamref name="T"/>
    /// </summary>
    /// <typeparam name="T">Type of IEnumerable</typeparam>
    /// <param name="enumerable">instance of <see cref="IEnumerable<typeparamref name="T"/>"/></param>
    /// <param name="action">an async <see cref="Action" /> to execute</param>
    /// <param name="maxDegreeOfParallelism">Optional, An integer that represents the maximum degree of parallelism,
    /// Must be grater than 0</param>
    /// <returns>A Task representing an async operation</returns>
    /// <exception cref="ArgumentOutOfRangeException">If the maxActionsToRunInParallel is less than 1</exception>
    public static async Task ForEachAsyncConcurrent<T>(
        this IEnumerable<T> enumerable,
        Func<T, Task> action,
        int? maxDegreeOfParallelism = null)
        if (maxDegreeOfParallelism.HasValue)
            using (var semaphoreSlim = new SemaphoreSlim(
                maxDegreeOfParallelism.Value, maxDegreeOfParallelism.Value))
                var tasksWithThrottler = new List<Task>();

                foreach (var item in enumerable)
                    // Increment the number of currently running tasks and wait if they are more than limit.
                    await semaphoreSlim.WaitAsync();

                    tasksWithThrottler.Add(Task.Run(async () =>
                        await action(item).ContinueWith(res =>
                            // action is completed, so decrement the number of currently running tasks

                // Wait for all tasks to complete.
                await Task.WhenAll(tasksWithThrottler.ToArray());
            await Task.WhenAll(enumerable.Select(item => action(item)));

Sample Usage:

await enumerable.ForEachAsyncConcurrent(
    async item =>
        await SomeAsyncMethod(item);

Create a File object in memory from a string in Java

The File class represents the "idea" of a file, not an actual handle to use for I/O. This is why the File class has a .exists() method, to tell you if the file exists or not. (How can you have a File object that doesn't exist?)

By contrast, constructing a new FileInputStream(new File("/my/file")) gives you an actual stream to read bytes from.

How do I concatenate two strings in C?

#include <string.h>
#include <stdio.h>
int main()
   int a,l;
   char str[50],str1[50],str3[100];
   printf("\nEnter a string: ");
   printf("\nEnter the string which you want to concat with string one: ");
   printf("\nThe string is %s\n",str3);

How to convert string to Title Case in Python?

def capitalizeWords(s):
  return re.sub(r'\w+', lambda, s)

re.sub can take a function for the "replacement" (rather than just a string, which is the usage most people seem to be familiar with). This repl function will be called with an re.Match object for each match of the pattern, and the result (which should be a string) will be used as a replacement for that match.

A longer version of the same thing:

WORD_RE = re.compile(r'\w+')

def capitalizeMatch(m):

def capitalizeWords(s):
  return WORD_RE.sub(capitalizeMatch, s)

This pre-compiles the pattern (generally considered good form) and uses a named function instead of a lambda.

How can I get javascript to read from a .json file?

Assuming you mean "file on a local filesystem" when you say .json file.

You'll need to save the json data formatted as jsonp, and use a file:// url to access it.

Your HTML will look like this:

<script src="file://c:\\data\\activity.jsonp"></script>
<script type="text/javascript">
  function updateMe(){
    var x = 0;
    var activity=jsonstr;
    foreach (i in activity) {
        date = document.getElementById( =;
        event = document.getElementById(i.event).innerHTML = activity.event;

And the file c:\data\activity.jsonp contains the following line:

jsonstr = [ {"date":"July 4th", "event":"Independence Day"} ];

How do I watch a file for changes?

Seems that no one has posted fswatch. It is a cross-platform file system watcher. Just install it, run it and follow the prompts.

I've used it with python and golang programs and it just works.

Removing fields from struct or hiding them in JSON Response

I also faced this problem, at first I just wanted to specialize the responses in my http handler. My first approach was creating a package that copies the information of a struct to another struct and then marshal that second struct. I did that package using reflection, so, never liked that approach and also I wasn't dynamically.

So I decided to modify the encoding/json package to do this. The functions Marshal, MarshalIndent and (Encoder) Encode additionally receives a

type F map[string]F

I wanted to simulate a JSON of the fields that are needed to marshal, so it only marshals the fields that are in the map.

package main

import (


type SearchResult struct {
    Date        string      `json:"date"`
    IdCompany   int         `json:"idCompany"`
    Company     string      `json:"company"`
    IdIndustry  interface{} `json:"idIndustry"`
    Industry    string      `json:"industry"`
    IdContinent interface{} `json:"idContinent"`
    Continent   string      `json:"continent"`
    IdCountry   interface{} `json:"idCountry"`
    Country     string      `json:"country"`
    IdState     interface{} `json:"idState"`
    State       string      `json:"state"`
    IdCity      interface{} `json:"idCity"`
    City        string      `json:"city"`
} //SearchResult

type SearchResults struct {
    NumberResults int            `json:"numberResults"`
    Results       []SearchResult `json:"results"`
} //type SearchResults
func main() {
    msg := SearchResults{
        NumberResults: 2,
        Results: []SearchResult{
                Date:        "12-12-12",
                IdCompany:   1,
                Company:     "alfa",
                IdIndustry:  1,
                Industry:    "IT",
                IdContinent: 1,
                Continent:   "america",
                IdCountry:   1,
                Country:     "México",
                IdState:     1,
                State:       "CDMX",
                IdCity:      1,
                City:        "Atz",
                Date:        "12-12-12",
                IdCompany:   2,
                Company:     "beta",
                IdIndustry:  1,
                Industry:    "IT",
                IdContinent: 1,
                Continent:   "america",
                IdCountry:   2,
                Country:     "USA",
                IdState:     2,
                State:       "TX",
                IdCity:      2,
                City:        "XYZ",
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {

        err := jsont.NewEncoder(w).Encode(msg, jsont.F{
            "numberResults": nil,
            "results": jsont.F{
                "date":       nil,
                "idCompany":  nil,
                "idIndustry": nil,
                "country":    nil,
        if err != nil {

    http.ListenAndServe(":3009", nil)

Can I write native iPhone apps using Python?

Technically, as long as the interpreted code ISN'T downloaded (excluding JavaScript), the app may be approved. Rhomobiles "Rhodes" framework does just that, bundling mobile Ruby, a lightweight version of Rails, and your app for distribution via the app-store. Because both the interpreter and the interpreted code are packaged into the final application - Apple doesn't find it objectionable.

Even after the latest apple press release - rhodes apps (mobile ruby) are still viable on the app-store. I'd find it hard to believe that tinyPy or pyObjC wouldn't find a place if there is a willing developer community.

After installing SQL Server 2014 Express can't find local db

I have noticed that after installation of SQL server 2012 express on Windows 10 you must install ENU\x64\SqlLocalDB.MSI from official Microsoft download site. After that, you could run SqlLocalDB.exe.

Pointer to 2D arrays in C

Ok, this is actually four different question. I'll address them one by one:

are both equals for the compiler? (speed, perf...)

Yes. The pointer dereferenciation and decay from type int (*)[100][280] to int (*)[280] is always a noop to your CPU. I wouldn't put it past a bad compiler to generate bogus code anyways, but a good optimizing compiler should compile both examples to the exact same code.

is one of these solutions eating more memory than the other?

As a corollary to my first answer, no.

what is the more frequently used by developers?

Definitely the variant without the extra (*pointer) dereferenciation. For C programmers it is second nature to assume that any pointer may actually be a pointer to the first element of an array.

what is the best way, the 1st or the 2nd?

That depends on what you optimize for:

  • Idiomatic code uses variant 1. The declaration is missing the outer dimension, but all uses are exactly as a C programmer expects them to be.

  • If you want to make it explicit that you are pointing to an array, you can use variant 2. However, many seasoned C programmers will think that there's a third dimension hidden behind the innermost *. Having no array dimension there will feel weird to most programmers.

Simple Vim commands you wish you'd known earlier


You can use other characters than / (slash) to separate patterns for substitution. This way you don’t have to escape the slashes of file paths.

What good technology podcasts are out there?

If you are into web design and website creation then I recommend Boagworld and also The Rissington podcast even if you are not.

JDBC ResultSet: I need a getDateTime, but there is only getDate and getTimeStamp

this worked:

    Date date = null;
    String dateStr = rs.getString("doc_date");
    if (dateStr != null) {
        date = dateFormat.parse(dateStr);

using SimpleDateFormat.

How to replace a whole line with sed?

If you would like to use awk then this would work too

awk -F= '{$2="xxx";print}' OFS="\=" filename

What is a classpath and how do I set it?

For linux users, and to sum up and add to what others have said here, you should know the following:

  1. $CLASSPATH is what Java uses to look through multiple directories to find all the different classes it needs for your script (unless you explicitly tell it otherwise with the -cp override). Using -cp requires that you keep track of all the directories manually and copy-paste that line every time you run the program (not preferable IMO).

  2. The colon (":") character separates the different directories. There is only one $CLASSPATH and it has all the directories in it. So, when you run "export CLASSPATH=...." you want to include the current value "$CLASSPATH" in order to append to it. For example:

    export CLASSPATH=.
    export CLASSPATH=$CLASSPATH:/usr/share/java/mysql-connector-java-5.1.12.jar

    In the first line above, you start CLASSPATH out with just a simple 'dot' which is the path to your current working directory. With that, whenever you run java it will look in the current working directory (the one you're in) for classes. In the second line above, $CLASSPATH grabs the value that you previously entered (.) and appends the path to a mysql dirver. Now, java will look for the driver AND for your classes.

  3. echo $CLASSPATH

    is super handy, and what it returns should read like a colon-separated list of all the directories, and .jar files, you want java looking in for the classes it needs.

  4. Tomcat does not use CLASSPATH. Read what to do about that here:

Get a Windows Forms control by name in C#

Since you're generating them dynamically, keep a map between a string and the menu item, that will allow fast retrieval.

// in class scope
private readonly Dictionary<string, ToolStripMenuItem> _menuItemsByName = new Dictionary<string, ToolStripMenuItem>();

// in your method creating items
ToolStripMenuItem createdItem = ...
_menuItemsByName.Add("<name here>", createdItem);

// to access it
ToolStripMenuItem menuItem = _menuItemsByName["<name here>"];

Get a list of all git commits, including the 'lost' ones

Not particularly easily- if you've lost the pointer to the tip of a branch, it's rather like finding a needle in a haystack. You can find all the commits that don't appear to be referenced any more- git fsck --unreachable will do this for you- but that will include commits that you threw away after a git commit --amend, old commits on branches that you rebased etc etc. So seeing all these commits at once is quite likely far too much information to wade through.

So the flippant answer is, don't lose track of things you're interested in. More seriously, the reflogs will hold references to all the commits you've used for the last 60 days or so by default. More importantly, they will give some context about what those commits are.

How to export a MySQL database to JSON?

The simplest solution I found was combination of mysql and jq commands with JSON_OBJECT query. Actually jq is not required if JSON Lines format is good enough.

Dump from remote server to local file example.

ssh remote_server \
    "mysql \
        --silent \
        --raw \
        --host "" --port 3306 \
        --user "" --password="" \
        table \
        -e \"SELECT JSON_OBJECT('key', value) FROM table\" |
    jq --slurp --ascii-output ." \
> dump.json

books table example

| id | book  | 
| 1  | book1 | 
| 2  | book2 | 
| 3  | book3 | 

Query would looks like:

SELECT JSON_OBJECT('id', id, 'book', book) FROM books;

dump.json output

        "id": "1",
        "book": "book1"
        "id": "2",
        "book": "book2"
        "id": "3",
        "book": "book3"

Maximum and Minimum values for ints

I rely heavily on commands like this.

python -c 'import sys; print(sys.maxsize)'

Max int returned: 9223372036854775807

For more references for 'sys' you should access

How to include CSS file in Symfony 2 and Twig?

The other answers are valid, but the Official Symfony Best Practices guide suggests using the web/ folder to store all assets, instead of different bundles.

Scattering your web assets across tens of different bundles makes it more difficult to manage them. Your designers' lives will be much easier if all the application assets are in one location.

Templates also benefit from centralizing your assets, because the links are much more concise[...]

I'd add to this by suggesting that you only put micro-assets within micro-bundles, such as a few lines of styles only required for a button in a button bundle, for example.

git ignore vim temporary files

This works on a Mac as noted by Alex Moore-Niemi:

set backupdir=$TMPDIR//
set directory=$TMPDIR//

Make sure to use TMPDIR and not TEMPDIR.

Linux Script to check if process is running and act on the result

If you changed awk '{print $1}' to '{ $1=""; print $0}' you will get all processes except for the first as a result. It will start with the field separator (a space generally) but I don't recall killall caring. So:

#! /bin/bash


case "$(pidof oscam1 | wc -w)" in

0)  echo "oscam1 not running, restarting oscam1:     $(date)" >> $logfile
    /usr/local/bin/oscam1 -b -c /usr/local/etc/oscam1 -t /usr/local/tmp.oscam1 &
2)  echo "oscam1 running, all OK:     $(date)" >> $logfile
*)  echo "multiple instances of oscam1 running. Stopping & restarting oscam1:     $(date)" >> $logfile
    kill $(pidof oscam1 | awk '{ $1=""; print $0}')

It is worth noting that the pidof route seems to work fine for commands that have no spaces, but you would probably want to go back to a ps-based string if you were looking for, say, a python script named myscript that showed up under ps like

root 22415 54.0 0.4 89116 79076 pts/1 S 16:40 0:00 /usr/bin/python /usr/bin/myscript

Just an FYI

Printing Exception Message in java

The output looks correct to me:

Invalid JavaScript code: missing } after property list (<Unknown source>) in <Unknown source>; at line number 1

I think Invalid Javascript code: .. is the start of the exception message.

Normally the stacktrace isn't returned with the message:

try {
    throw new RuntimeException("hu?\ntrace-line1\ntrace-line2");
} catch (Exception e) {
    System.out.println(e.getMessage()); // prints "hu?"

So maybe the code you are calling catches an exception and rethrows a ScriptException. In this case maybe e.getCause().getMessage() can help you.

How do I handle the window close event in Tkinter?

from tkinter import*

How to randomize Excel rows

I usually do as you describe:
Add a separate column with a random value (=RAND()) and then perform a sort on that column.

Might be more complex and prettyer ways (using macros etc), but this is fast enough and simple enough for me.

HttpClient 4.0.1 - how to release connection?

This seems to work great :

      if( response.getEntity() != null ) {

And don't forget to consume the entity even if you didn't open its content. For instance, you expect a HTTP_OK status from the response and don't get it, you still have to consume the entity !

String.Replace ignoring case

Lots of suggestions using Regex. How about this extension method without it:

public static string Replace(this string str, string old, string @new, StringComparison comparison)
    @new = @new ?? "";
    if (string.IsNullOrEmpty(str) || string.IsNullOrEmpty(old) || old.Equals(@new, comparison))
        return str;
    int foundAt = 0;
    while ((foundAt = str.IndexOf(old, foundAt, comparison)) != -1)
        str = str.Remove(foundAt, old.Length).Insert(foundAt, @new);
        foundAt += @new.Length;
    return str;

How To Run PHP From Windows Command Line in WAMPServer

Try using batch file

  1. Open notepad
  2. type php -S localhost:8000
  3. save file as .bat extension, server.bat
  4. now click on server.bat file your server is ready on http://localhost:8000


if you got error php not recognize any internal or external command then goto environment variable and edit path to php.exe "C:\wamp\bin\php\php5.4.3"

YAML: Do I need quotes for strings in YAML?

After a brief review of the YAML cookbook cited in the question and some testing, here's my interpretation:

  • In general, you don't need quotes.
  • Use quotes to force a string, e.g. if your key or value is 10 but you want it to return a String and not a Fixnum, write '10' or "10".
  • Use quotes if your value includes special characters, (e.g. :, {, }, [, ], ,, &, *, #, ?, |, -, <, >, =, !, %, @, \).
  • Single quotes let you put almost any character in your string, and won't try to parse escape codes. '\n' would be returned as the string \n.
  • Double quotes parse escape codes. "\n" would be returned as a line feed character.
  • The exclamation mark introduces a method, e.g. !ruby/sym to return a Ruby symbol.

Seems to me that the best approach would be to not use quotes unless you have to, and then to use single quotes unless you specifically want to process escape codes.


"Yes" and "No" should be enclosed in quotes (single or double) or else they will be interpreted as TrueClass and FalseClass values:

    'yes': 'Yes'
    'no': 'No'

join list of lists in python

For one-level flatten, if you care about speed, this is faster than any of the previous answers under all conditions I tried. (That is, if you need the result as a list. If you only need to iterate through it on the fly then the chain example is probably better.) It works by pre-allocating a list of the final size and copying the parts in by slice (which is a lower-level block copy than any of the iterator methods):

def join(a):
    """Joins a sequence of sequences into a single sequence.  (One-level flattening.)
    E.g., join([(1,2,3), [4, 5], [6, (7, 8, 9), 10]]) = [1,2,3,4,5,6,(7,8,9),10]
    This is very efficient, especially when the subsequences are long.
    n = sum([len(b) for b in a])
    l = [None]*n
    i = 0
    for b in a:
        j = i+len(b)
        l[i:j] = b
        i = j
    return l

Sorted times list with comments:

[(0.5391559600830078, 'flatten4b'), # join() above. 
(0.5400412082672119, 'flatten4c'), # Same, with sum(len(b) for b in a) 
(0.5419249534606934, 'flatten4a'), # Similar, using zip() 
(0.7351131439208984, 'flatten1b'), # list(itertools.chain.from_iterable(a)) 
(0.7472689151763916, 'flatten1'), # list(itertools.chain(*a)) 
(1.5468521118164062, 'flatten3'), # [i for j in a for i in j] 
(26.696547985076904, 'flatten2')] # sum(a, [])

LocalDate to java.util.Date and vice versa simplest conversion?

Date to LocalDate

Date date = new Date();
LocalDate localDate = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

LocalDate to Date

LocalDate localDate =;
Date date = Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());

How to compare two dates in Objective-C


NSString *date = @"2009-05-11"
NSString *nowDate = [[[NSDate date]description]substringToIndex: 10];
if([date isEqualToString: nowDate])
// your code

c++ and opencv get and set pixel color to Mat

just use a reference:

Vec3b & color =<Vec3b>(y,x);
color[2] = 13;

Push items into mongo array via mongoose

I ran into this issue as well. My fix was to create a child schema. See below for an example for your models.

---- Person model

const mongoose = require('mongoose');
const SingleFriend = require('./SingleFriend');
const Schema   = mongoose.Schema;

const productSchema = new Schema({
  friends    : [SingleFriend.schema]

module.exports = mongoose.model('Person', personSchema);

***Important: SingleFriend.schema -> make sure to use lowercase for schema

--- Child schema

const mongoose = require('mongoose');
const Schema   = mongoose.Schema;

const SingleFriendSchema = new Schema({
  Name: String

module.exports = mongoose.model('SingleFriend', SingleFriendSchema);

How to find the Number of CPU Cores via .NET/C#?

There are several different pieces of information relating to processors that you could get:

  1. Number of physical processors
  2. Number of cores
  3. Number of logical processors.

These can all be different; in the case of a machine with 2 dual-core hyper-threading-enabled processors, there are 2 physical processors, 4 cores, and 8 logical processors.

The number of logical processors is available through the Environment class, but the other information is only available through WMI (and you may have to install some hotfixes or service packs to get it on some systems):

Make sure to add a reference in your project to System.Management.dll In .NET Core, this is available (for Windows only) as a NuGet package.

Physical Processors:

foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_ComputerSystem").Get())
    Console.WriteLine("Number Of Physical Processors: {0} ", item["NumberOfProcessors"]);


int coreCount = 0;
foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_Processor").Get())
    coreCount += int.Parse(item["NumberOfCores"].ToString());
Console.WriteLine("Number Of Cores: {0}", coreCount);

Logical Processors:

Console.WriteLine("Number Of Logical Processors: {0}", Environment.ProcessorCount);


foreach (var item in new System.Management.ManagementObjectSearcher("Select * from Win32_ComputerSystem").Get())
    Console.WriteLine("Number Of Logical Processors: {0}", item["NumberOfLogicalProcessors"]);

Processors excluded from Windows:

You can also use Windows API calls in setupapi.dll to discover processors that have been excluded from Windows (e.g. through boot settings) and aren't detectable using the above means. The code below gives the total number of logical processors (I haven't been able to figure out how to differentiate physical from logical processors) that exist, including those that have been excluded from Windows:

static void Main(string[] args)
    int deviceCount = 0;
    IntPtr deviceList = IntPtr.Zero;
    // GUID for processor classid
    Guid processorGuid = new Guid("{50127dc3-0f36-415e-a6cc-4cb3be910b65}");

        // get a list of all processor devices
        deviceList = SetupDiGetClassDevs(ref processorGuid, "ACPI", IntPtr.Zero, (int)DIGCF.PRESENT);
        // attempt to process each item in the list
        for (int deviceNumber = 0; ; deviceNumber++)
            SP_DEVINFO_DATA deviceInfo = new SP_DEVINFO_DATA();
            deviceInfo.cbSize = Marshal.SizeOf(deviceInfo);

            // attempt to read the device info from the list, if this fails, we're at the end of the list
            if (!SetupDiEnumDeviceInfo(deviceList, deviceNumber, ref deviceInfo))
                deviceCount = deviceNumber;
        if (deviceList != IntPtr.Zero) { SetupDiDestroyDeviceInfoList(deviceList); }
    Console.WriteLine("Number of cores: {0}", deviceCount);

[DllImport("setupapi.dll", SetLastError = true)]
private static extern IntPtr SetupDiGetClassDevs(ref Guid ClassGuid,
    [MarshalAs(UnmanagedType.LPStr)]String enumerator,
    IntPtr hwndParent,
    Int32 Flags);

[DllImport("setupapi.dll", SetLastError = true)]
private static extern Int32 SetupDiDestroyDeviceInfoList(IntPtr DeviceInfoSet);

[DllImport("setupapi.dll", SetLastError = true)]
private static extern bool SetupDiEnumDeviceInfo(IntPtr DeviceInfoSet,
    Int32 MemberIndex,
    ref SP_DEVINFO_DATA DeviceInterfaceData);

private struct SP_DEVINFO_DATA
    public int cbSize;
    public Guid ClassGuid;
    public uint DevInst;
    public IntPtr Reserved;

private enum DIGCF
    DEFAULT = 0x1,
    PRESENT = 0x2,
    ALLCLASSES = 0x4,
    PROFILE = 0x8,

How to get bean using application context in spring boot

One API method I use when I'm not sure what the bean name is org.springframework.beans.factory.ListableBeanFactory#getBeanNamesForType(java.lang.Class<?>). I simple pass it the class type and it retrieves a list of beans for me. You can be as specific or general as you'd like to retrieve all the beans relate with that type and its subtypes, example

ApplicationContext ctx


SomeController controller = ctx.getBeanNamesForType(SomeController)

function to return a string in java

Your code is fine. There's no problem with returning Strings in this manner.

In Java, a String is a reference to an immutable object. This, coupled with garbage collection, takes care of much of the potential complexity: you can simply pass a String around without worrying that it would disapper on you, or that someone somewhere would modify it.

If you don't mind me making a couple of stylistic suggestions, I'd modify the code like so:

public String time_to_string(long t) // time in milliseconds
    if (t < 0)
        return "-";
        int secs = (int)(t/1000);
        int mins = secs/60;
        secs = secs - (mins * 60);
        return String.format("%d:%02d", mins, secs);

As you can see, I've pushed the variable declarations as far down as I could (this is the preferred style in C++ and Java). I've also eliminated ans and have replaced the mix of string concatenation and String.format() with a single call to String.format().

Better way to Format Currency Input editText?

Another approach, but based on Guilherme answer. This approach is useful when your country locale is not available or if you want to use custom currency symbols. This implementation is only for positive non-decimal.

this code is in Kotlin, first, delegate setMaskingMoney for EditText

fun EditText.setMaskingMoney(currencyText: String) {
    this.addTextChangedListener(object: MyTextWatcher{
        val editTextWeakReference: WeakReference<EditText> = WeakReference<EditText>(this@setMaskingMoney)
        override fun afterTextChanged(editable: Editable?) {
            val editText = editTextWeakReference.get() ?: return
            val s = editable.toString()
            val cleanString = s.replace("[Rp,. ]".toRegex(), "")
            val newval = currencyText + cleanString.monetize()


Then MyTextWatcher interface should be extended from TextWatcher. Since we only need the afterTextChanged method, the other methods need to override in this interface.

interface MyTextWatcher: TextWatcher {
    override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
    override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}

and the monetize methods is:

fun String.monetize(): String = if (this.isEmpty()) "0"
    else DecimalFormat("#,###").format(this.replace("[^\\d]".toRegex(),"").toLong())

Full implementations:

fun EditText.setMaskingMoney(currencyText: String) {
    this.addTextChangedListener(object: MyTextWatcher{
        val editTextWeakReference: WeakReference<EditText> = WeakReference<EditText>(this@setMaskingMoney)
        override fun afterTextChanged(editable: Editable?) {
            val editText = editTextWeakReference.get() ?: return
            val s = editable.toString()
            val cleanString = s.replace("[Rp,. ]".toRegex(), "")
            val newval = currencyText + cleanString.monetize()


interface MyTextWatcher: TextWatcher {
    override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
    override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}

fun String.monetize(): String = if (this.isEmpty()) "0"
    else DecimalFormat("#,###").format(this.replace("[^\\d]".toRegex(),"").toLong())

and somewhere on onCreate method:

yourTextView.setMaskingMoney("Rp. ")

Check if page gets reloaded or refreshed in JavaScript

    var currpage    = window.location.href;
    var lasturl     = sessionStorage.getItem("last_url");

    if(lasturl == null || lasturl.length === 0 || currpage !== lasturl ){
        sessionStorage.setItem("last_url", currpage);
        alert("New page loaded");
        alert("Refreshed Page");  


Is there a "between" function in C#?

There is no built in construct in C#/.NET, but you can easily add your own extension method for this:

public static class ExtensionsForInt32
    public static bool IsBetween (this int val, int low, int high)
           return val > low && val < high;

Which can be used like:

if (5.IsBetween (0, 10)) { /* Do something */ }

Console.WriteLine and generic List

        List<int> a = new List<int>() { 1, 2, 3, 4, 5 };
        a.ForEach(p => Console.WriteLine(p));

edit: ahhh he beat me to it.

How to clear an EditText on click?

Be careful when setting text with an onClick listener on the field you are setting the text. I was doing this and setting the text to an empty string. This was causing the pointer to come up to indicate where my cursor was, which will normally go away after a few seconds. When I did not wait for it to go away before leaving my page causing finish() to be called, it would cause a memory leak and crash my app. Took me a while to figure out what was causing the crash on this one..

Anyway, I would recommend using selectAll() in your on click listener rather than setText() if you can. This way, once the text is selected, the user can start typing and all of the previous text will be cleared.

pic of the suspect pointer:

Make the first character Uppercase in CSS

I suggest to use

#selector {
    text-transform: capitalize;


#selector::first-letter {
    text-transform: uppercase;

By the way, check this w3schools link:

Regex allow digits and a single dot

My try is combined solution.

string = string.replace(',', '.').replace(/[^\d\.]/g, "").replace(/\./, "x").replace(/\./g, "").replace(/x/, ".");
string = Math.round( parseFloat(string) * 100) / 100;

First line solution from here: regex replacing multiple periods in floating number . It replaces comma "," with dot "." ; Replaces first comma with x; Removes all dots and replaces x back to dot.

Second line cleans numbers after dot.

Warning: Permanently added the RSA host key for IP address

While cloning you might be using SSH in the dropdown list. Change it to Https and then clone.

Newline in string attribute

<TextBlock Text="Stuff on line1&#x0a;Stuff on line 2"/>

You can use any hexadecimally encoded value to represent a literal. In this case, I used the line feed (char 10). If you want to do "classic" vbCrLf, then you can use &#x0d;&#x0a;

By the way, note the syntax: It's the ampersand, a pound, the letter x, then the hex value of the character you want, and then finally a semi-colon.

ALSO: For completeness, you can bind to a text that already has the line feeds embedded in it like a constant in your code behind, or a variable constructed at runtime.

Promise.all().then() resolve?

But that doesn't seem like the proper way to do it..

That is indeed the proper way to do it (or at least a proper way to do it). This is a key aspect of promises, they're a pipeline, and the data can be massaged by the various handlers in the pipeline.


const promises = [_x000D_
  new Promise(resolve => setTimeout(resolve, 0, 1)),_x000D_
  new Promise(resolve => setTimeout(resolve, 0, 2))_x000D_
  .then(data => {_x000D_
    console.log("First handler", data);_x000D_
    return => entry * 10);_x000D_
  .then(data => {_x000D_
    console.log("Second handler", data);_x000D_

(catch handler omitted for brevity. In production code, always either propagate the promise, or handle rejection.)

The output we see from that is:

First handler [1,2]
Second handler [10,20]

...because the first handler gets the resolution of the two promises (1 and 2) as an array, and then creates a new array with each of those multiplied by 10 and returns it. The second handler gets what the first handler returned.

If the additional work you're doing is synchronous, you can also put it in the first handler:


const promises = [_x000D_
  new Promise(resolve => setTimeout(resolve, 0, 1)),_x000D_
  new Promise(resolve => setTimeout(resolve, 0, 2))_x000D_
  .then(data => {_x000D_
    console.log("Initial data", data);_x000D_
    data = => entry * 10);_x000D_
    console.log("Updated data", data);_x000D_
    return data;_x000D_

...but if it's asynchronous you won't want to do that as it ends up getting nested, and the nesting can quickly get out of hand.

How to delete projects in Intellij IDEA 14?

Deleting and Recreating a project with same name is tricky. If you try to follow above suggested steps and try to create a project with same name as the one you just deleted, you will run into error like

'C:/xxxxxx/pom.xml' already exists in VFS

Here is what I found would work.

  1. Remove module
  2. File -> Invalidate Cache (at this point the Intelli IDEA wants to restart)
  3. Close project
  4. Delete the folder form system explorer.
  5. Now you can create a project with same name as before.

Peak memory usage of a linux/unix process

Valgrind one-liner:

valgrind --tool=massif --pages-as-heap=yes --massif-out-file=massif.out ./; grep mem_heap_B massif.out | sed -e 's/mem_heap_B=\(.*\)/\1/' | sort -g | tail -n 1

Note use of --pages-as-heap to measure all memory in a process. More info here:

This will slow down your command significantly.

How to push JSON object in to array using javascript

You need to have the 'data' array outside of the loop, otherwise it will get reset in every loop and also you can directly push the json. Find the solution below:-

var my_json;
$.getJSON(""+did+"/feeds.json?api_key="+apikey+"&results=300", function(json1) {
var data = [];
    console.log("\n The details of " + i + "th Object are :  \nCreated_at: " + feed.created_at + "\nEntry_id:" + feed.entry_id + "\nField1:" + feed.field1 + "\nField2:" + feed.field2+"\nField3:" + feed.field3);      
    my_json = feed;
    console.log(my_json); //Object {created_at: "2017-03-14T01:00:32Z", entry_id: 33358, field1: "4", field2: "4", field3: "0"}
     //["2017-03-14T01:00:32Z", 33358, "4", "4", "0"]

How do I get the total number of unique pairs of a set in the database?

What you're looking for is n choose k. Basically:

enter image description here

For every pair of 100 items, you'd have 4,950 combinations - provided order doesn't matter (AB and BA are considered a single combination) and you don't want to repeat (AA is not a valid pair).

Convert MySQL to SQlite

There are different ways to do this. I also had this problem and I searched a lot and then I got a simple way to convert MySQL to SQLite.

Follow these steps:

  1. First You Need to Install SQLite DB Browser (very small and fast to view Tables and Data)

  2. Open your MySQL File in Notepad or it would be great if you open in Notepad++

  3. Remove First extra Lines Contains Information or Queries and Save it.

  4. Open SQLite DB Browser, Create Database, then Tables, and Same Types as it is in MySQL Database.

  5. In Menu Bar of SQLite DB Browser Select File-> then Import data MySQL File which you saved.

It will easily Convert into SQLite After Warning Dialog.

If error then remove more extra lines if your MySQL file have.

You can also Install MySQL to SQLite Converter Software on trial Basis, but the information I am giving for conversion is life time.

ADB Driver and Windows 8.1

this worked for me, in my latest Micromax Yu Yuphoria! just download the installer and install it

What are the new features in C++17?

Language features:

Templates and Generic Code



Syntax cleanup

Cleaner multi-return and flow control

  • Structured bindings

    • Basically, first-class std::tie with auto
    • Example:
      • const auto [it, inserted] = map.insert( {"foo", bar} );
      • Creates variables it and inserted with deduced type from the pair that map::insert returns.
    • Works with tuple/pair-likes & std::arrays and relatively flat structs
    • Actually named structured bindings in standard
  • if (init; condition) and switch (init; condition)

    • if (const auto [it, inserted] = map.insert( {"foo", bar} ); inserted)
    • Extends the if(decl) to cases where decl isn't convertible-to-bool sensibly.
  • Generalizing range-based for loops

    • Appears to be mostly support for sentinels, or end iterators that are not the same type as begin iterators, which helps with null-terminated loops and the like.
  • if constexpr

    • Much requested feature to simplify almost-generic code.


Library additions:

Data types

Invoke stuff

File System TS v1

New algorithms

  • for_each_n

  • reduce

  • transform_reduce

  • exclusive_scan

  • inclusive_scan

  • transform_exclusive_scan

  • transform_inclusive_scan

  • Added for threading purposes, exposed even if you aren't using them threaded


(parts of) Library Fundamentals TS v1 not covered above or below

Container Improvements

Smart pointer changes

Other std datatype improvements:



Deprecated has has an independent list of changes since C++14; it has been partly pillaged.

Naturally TS work continues in parallel, so there are some TS that are not-quite-ripe that will have to wait for the next iteration. The target for the next iteration is C++20 as previously planned, not C++19 as some rumors implied. C++1O has been avoided.

Initial list taken from this reddit post and this reddit post, with links added via googling or from the above page.

Additional entries pillaged from SD-6 feature-test list.

clang's feature list and library feature list are next to be pillaged. This doesn't seem to be reliable, as it is C++1z, not C++17.

these slides had some features missing elsewhere.

While "what was removed" was not asked, here is a short list of a few things ((mostly?) previous deprecated) that are removed in C++17 from C++:


There were rewordings. I am unsure if these have any impact on code, or if they are just cleanups in the standard:

Papers not yet integrated into above:

  • P0505R0 (constexpr chrono)

  • P0418R2 (atomic tweaks)

  • P0512R0 (template argument deduction tweaks)

  • P0490R0 (structured binding tweaks)

  • P0513R0 (changes to std::hash)

  • P0502R0 (parallel exceptions)

  • P0509R1 (updating restrictions on exception handling)

  • P0012R1 (make exception specifications be part of the type system)

  • P0510R0 (restrictions on variants)

  • P0504R0 (tags for optional/variant/any)

  • P0497R0 (shared ptr tweaks)

  • P0508R0 (structured bindings node handles)

  • P0521R0 (shared pointer use count and unique changes?)

Spec changes:

Further reference:

What is "entropy and information gain"?

To begin with, it would be best to understand the measure of information.

How do we measure the information?

When something unlikely happens, we say it's a big news. Also, when we say something predictable, it's not really interesting. So to quantify this interesting-ness, the function should satisfy

  • if the probability of the event is 1 (predictable), then the function gives 0
  • if the probability of the event is close to 0, then the function should give high number
  • if probability 0.5 events happens it give one bit of information.

One natural measure that satisfy the constraints is

I(X) = -log_2(p)

where p is the probability of the event X. And the unit is in bit, the same bit computer uses. 0 or 1.

Example 1

Fair coin flip :

How much information can we get from one coin flip?

Answer : -log(p) = -log(1/2) = 1 (bit)

Example 2

If a meteor strikes the Earth tomorrow, p=2^{-22} then we can get 22 bits of information.

If the Sun rises tomorrow, p ~ 1 then it is 0 bit of information.


So if we take expectation on the interesting-ness of an event Y, then it is the entropy. i.e. entropy is an expected value of the interesting-ness of an event.

H(Y) = E[ I(Y)]

More formally, the entropy is the expected number of bits of an event.


Y = 1 : an event X occurs with probability p

Y = 0 : an event X does not occur with probability 1-p

H(Y) = E[I(Y)] = p I(Y==1) + (1-p) I(Y==0) 
     = - p log p - (1-p) log (1-p)

Log base 2 for all log.

FFMPEG mp4 from http live streaming m3u8 file?

Aergistal's answer works, but I found that converting to mp4 can make some m3u8 videos broken. If you are stuck with this problem, try to convert them to mkv, and convert them to mp4 later.

Catching FULL exception message

I found it!

Simply print out $Error[0] for the last error message.

Service Temporarily Unavailable Magento?

Check if there is a file called maintenance.flag and if so delete it.

Magento 1.x : maintenance.flag file is in : magento root directory

Magento 2.x : maintenance.flag file is in : var folder

When Magento is performing certain tasks it temporarily creates this file. Magento checks for its existence and if it's there will send users to the page you described.

It's supposed to automatically delete this file when done processing whatever task it was doing, but I've experienced occasions where something went wrong and it failed to delete it.

What to do with commit made in a detached head

You can just do git merge <commit-number> or git cherry-pick <commit> <commit> ...

As suggested by Ryan Stewart you may also create a branch from the current HEAD:

git branch brand-name

Or just a tag:

git tag tag-name

How do I pass a datetime value as a URI parameter in mvc?

Use the ticks value. It's quite simple to rebuild into a DateTime structure

 Int64 nTicks = DateTime.Now.Ticks;
 DateTime dtTime = new DateTime(nTicks);

Difference between jar and war in Java

A war file is a special jar file that is used to package a web application to make it easy to deploy it on an application server. The content of the war file must follow a defined structure.

Simplest way to throw an error/exception with a custom message in Swift 2?

In case you don't need to catch the error and you want to immediately stop the application you can use a fatalError: fatalError ("Custom message here")

How to copy a file along with directory structure/path using python?

To create all intermediate-level destination directories you could use os.makedirs() before copying:

import os
import shutil

srcfile = 'a/long/long/path/to/'
dstroot = '/home/myhome/new_folder'

assert not os.path.isabs(srcfile)
dstdir =  os.path.join(dstroot, os.path.dirname(srcfile))

os.makedirs(dstdir) # create all directories, raise an error if it already exists
shutil.copy(srcfile, dstdir)

Split string with string as delimiter

I've found two older scripts that use an indefinite or even a specific string to split. As an approach, these are always helpful.

@echo off
if "%~1" neq "" goto :nohelp
echo Gibt eine Ausgabe bis zur angebenen Zeichenfolge&echo(
echo %~n0 ist mit Eingabeumleitung zu nutzen
echo %~n0 "Zeichenfolge" ^<Quelldatei [^>Zieldatei]&echo(
echo    Zeichenfolge    die zu suchende Zeichenfolge wird mit FIND bestimmt
echo            ohne AusgabeUmleitung Ausgabe im CMD Fenster
exit /b
setlocal disabledelayedexpansion
set "intemp=%temp%%time::=%"
set "string=%~1"
set "stringlength=0"
:Laenge string bestimmen
for /f eol^=^

^ delims^= %%i in (' cmd /u /von /c "echo(!string!"^|find /v "" ') do set /a Stringlength += 1

:Eingabe temporär speichern
>"%intemp%" find /n /v ""

:suchen der Zeichenfolge und Zeile bestimmen und speichen
set "NRout="
for /f "tokens=*delims=" %%a in (' find "%string%"^<"%intemp%" ') do if not defined NRout (set "LineStr=%%a"
  for /f "delims=[]" %%b in ("%%a") do set "NRout=%%b"
if not defined NRout >&2 echo Zeichenfolge nicht gefunden.& set /a xcode=1 &goto :end
if %NRout% gtr 1 call :Line
call :LineStr

del "%intemp%"
exit /b %xcode%

:LineStr Suche nur jeden ersten Buchstaben des Strings in der Treffer-Zeile dann Ausgabe bis dahin
for /f eol^=^

^ delims^= %%a in ('cmd /u /von /c "echo(!String!"^|findstr .') do (
  for /f "delims=[]" %%i in (' cmd /u /von /c "echo(!LineStr!"^|find /n "%%a" ') do (
    setlocal enabledelayedexpansion
    for /f %%n in ('set /a %%i-1') do if !LineStr:^~%%n^,%stringlength%! equ !string! (
      set "Lineout=!LineStr:~0,%%n!!string!"
      exit /b
) )
exit /b 

:Line vorige Zeilen ausgeben
for /f "usebackq tokens=* delims=" %%i in ("%intemp%") do (
  for /f "tokens=1*delims=[]" %%n in ("%%i") do if %%n EQU %NRout%  exit /b
  set "Line=%%i"
  setlocal enabledelayedexpansion 
exit /b

@echo off
:: CUTwithWildcards.cmd
if "%~1" neq "" goto :nohelp
echo Gibt eine Ausgabe ohne die angebene Zeichenfolge.
echo Der Rest wird abgeschnitten.&echo(
echo %~n0 "Zeichenfolge" B n E [/i] &echo(
echo    Zeichenfolge    String zum Durchsuchen
echo    B   Zeichen Wonach am Anfang gesucht wird
echo    n   Auszulassende Zeichenanzahl
echo    E   Zeichen was das Ende der Zeichen Bestimmt
echo    /i  Case intensive
exit /b
setlocal disabledelayedexpansion
set  "Original=%~1"
set     "Begin=%~2"
set /a    Excl=%~3 ||echo Syntaxfehler.>&2 &&exit /b 1
set       "End=%~4"
if not defined end echo Syntaxfehler.>&2 &exit /b 1
set   "CaseInt=%~5"
:: end Setting Input Param
set       "out="
set      "more="
call :read Original
if errorlevel 1 echo Zeichenfolge nicht gefunden.>&2
exit /b
:read VarName B # E [/i]
for /f "delims=[]" %%a in (' cmd /u /von /c "echo  !%~1!"^|find /n %CaseInt% "%Begin%" ') do (
  if defined out exit /b 0
  for /f "delims=[]" %%b in (' cmd /u /von /c "echo !%1!"^|more +%Excl%^|find /n %CaseInt% "%End%"^|find "[%%a]" ') do (
    set "out=1"
    setlocal enabledelayedexpansion
    set "In=  !Original!"
    set "In=!In:~,%%a!"
    echo !In:^~2!
) )
if not defined out exit /b 1 
exit /b

::oneliner for CMDLine
set "Dq=""
for %i in ("*S??E*") do @set "out=1" &for /f "delims=[]" %a in ('cmd/u/c "echo  %i"^|find /n "S"') do @if defined out for /f "delims=[]" %b in ('cmd/u/c "echo %i"^|more +2^|find /n "E"^|find "[%a]"') do @if %a equ %b set "out=" & set in= "%i" &cmd /v/c echo ren "%i" !in:^~0^,%a!!Dq!)

how to get multiple checkbox value using jquery

Also you can use $('input[name="selector[]"]').serialize();. It returns URL encoded string like: "selector%5B%5D=1&selector%5B%5D=3"

How to install .MSI using PowerShell

You can use:

msiexec /i "c:\package.msi"

You can also add some more optional parameters. There are common msi parameters and parameters which are specific for your installer. For common parameters just call msiexec

Cannot get Kerberos service ticket: KrbException: Server not found in Kerberos database (7)

"Server not found in Kerberos database" error can happen if you have registered the SPN to multiple users/computers.

You can check that with:

$ SetSPN -Q ServicePrincipalName
( SetSPN -Q HTTP/my.server.local@MYDOMAIN )

How do I make a comment in a Dockerfile?

As others have mentioned, comments are referenced with a # and are documented here. However, unlike some languages, the # must be at the beginning of the line. If they occur part way through the line, they are interpreted as an argument and may result in unexpected behavior.

# This is a comment

COPY test_dir target_dir # This is not a comment, it is an argument to COPY

RUN echo hello world # This is an argument to RUN but the shell may ignore it

It should also be noted that parser directives have recently been added to the Dockerfile which have the same syntax as a comment. They need to appear at the top of the file, before any other comments or commands. Originally, this directive was added for changing the escape character to support Windows:

# escape=`

FROM microsoft/nanoserver
COPY testfile.txt c:\
RUN dir c:\

The first line, while it appears to be a comment, is a parser directive to change the escape character to a backtick so that the COPY and RUN commands can use the backslash in the path. A parser directive is also used with BuildKit to change the frontend parser with a syntax line. See the experimental syntax for more details on how this is being used in practice.

With a multi-line command, the commented lines are ignored, but you need to comment out every line individually:

$ cat Dockerfile
FROM busybox:latest
RUN echo first command \
# && echo second command disabled \
 && echo third command

$ docker build .
Sending build context to Docker daemon  23.04kB
Step 1/2 : FROM busybox:latest
 ---> 59788edf1f3e
Step 2/2 : RUN echo first command  && echo third command
 ---> Running in b1177e7b563d
first command
third command
Removing intermediate container b1177e7b563d
 ---> 5442cfe321ac
Successfully built 5442cfe321ac

Getting a random value from a JavaScript array

This is similar to, but more general than, @Jacob Relkin's solution:

This is ES2015:

const randomChoice = arr => {
    const randIndex = Math.floor(Math.random() * arr.length);
    return arr[randIndex];

The code works by selecting a random number between 0 and the length of the array, then returning the item at that index.

How do I get the backtrace for all the threads in GDB?

Generally, the backtrace is used to get the stack of the current thread, but if there is a necessity to get the stack trace of all the threads, use the following command.

thread apply all bt

Changing nav-bar color after scrolling?

      $(window).scroll(function() { // check if scroll event happened
        if ($(document).scrollTop() > 50) { // check if user scrolled more than 50 from top of the browser window
          $(".navbar-fixed-top").css("background-color", "#f8f8f8"); // if yes, then change the color of class "navbar-fixed-top" to white (#f8f8f8)
        } else {
          $(".navbar-fixed-top").css("background-color", "transparent"); // if not, change it back to transparent

Settings to Windows Firewall to allow Docker for Windows to share drive

Using Kaspersky Internet Security you can resolve this easily if you change the vEthernet (DockerNAT) network adapter type to Trusted network.

Settings > Protection > Firewall > Networks > vEthernet (DockerNAT) > Select "Trusted Network"

enter image description here enter image description here enter image description here enter image description here

What is trunk, branch and tag in Subversion?

If you're new to Subversion you may want to check out this post on, appropriately titled Ultimate Round-Up for Version Control with SubVersion.

It covers getting started with SubVersion with links to tutorials, reference materials, & book suggestions.

It covers tools (many are compatible windows), and it mentions AnkhSVN as a Visual Studio compatible plugin. The comments also mention VisualSVN as an alternative.

How to use a global array in C#?

Your class shoud look something like this:

class Something {     int[] array; //global array, replace type of course     void function1() {        array = new int[10]; //let say you declare it here that will be 10 integers in size     }     void function2() {        array[0] = 12; //assing value at index 0 to 12.     } } 

That way you array will be accessible in both functions. However, you must be careful with global stuff, as you can quickly overwrite something.

HTML Button Close Window

Use the code below. It works every time.

<button onclick="self.close()">Close</button>

It works every time in Chrome and also works on Firefox.

How can I check if a URL exists via PHP?

Other way to check if a URL is valid or not can be:


  if (isValidURL("")) {
      echo "URL is valid...";
  } else {
      echo "URL is not valid...";

  function isValidURL($url) {
      $file_headers = @get_headers($url);
      if (strpos($file_headers[0], "200 OK") > 0) {
         return true;
      } else {
        return false;

How to check whether a file is empty or not?

>>> import os
>>> os.stat("file").st_size == 0

How to convert String into Hashmap in java

This is one solution. If you want to make it more generic, you can use the StringUtils library.

String value = "{first_name = naresh,last_name = kumar,gender = male}";
value = value.substring(1, value.length()-1);           //remove curly brackets
String[] keyValuePairs = value.split(",");              //split the string to creat key-value pairs
Map<String,String> map = new HashMap<>();               

for(String pair : keyValuePairs)                        //iterate over the pairs
    String[] entry = pair.split("=");                   //split the pairs to get key and value 
    map.put(entry[0].trim(), entry[1].trim());          //add them to the hashmap and trim whitespaces

For example you can switch

 value = value.substring(1, value.length()-1);


 value = StringUtils.substringBetween(value, "{", "}");

if you are using StringUtils which is contained in apache.commons.lang package.

Make a div fill the height of the remaining screen space

Instead of using tables in the markup, you could use CSS tables.


    <div>hello </div>

(Relevant) CSS

div+ div


Some advantages of this method are:

1) Less markup

2) Markup is more semantic than tables, because this is not tabular data.

3) Browser support is very good: IE8+, All modern browsers and mobile devices (caniuse)

Just for completeness, here are the equivalent Html elements to css properties for the The CSS table model

table    { display: table }
tr       { display: table-row }
thead    { display: table-header-group }
tbody    { display: table-row-group }
tfoot    { display: table-footer-group }
col      { display: table-column }
colgroup { display: table-column-group }
td, th   { display: table-cell }
caption  { display: table-caption } 

Converting an object to a string

add on ---

JSON.stringify(obj) is nice, but it will convert to json string object. sometimes we will need the string of it, like when posting it in body for WCF http post and recieving as a string.

in order of this we should reuse the stringify() as following:

let obj = {id:1, name:'cherry'};
let jsonObj = JSON.stringify(doc); //json object string
let strObj = JSON.stringify(jsonObj); //json object string wrapped with string

Chrome & Safari Error::Not allowed to load local resource: file:///D:/CSS/Style.css

I know this post is old but here is what I found. It doesn't work when I link it this way(with / before css/style.csson the href attribute.

<link rel="stylesheet" media="all" href="/CSS/Style.css" type="text/css" />

However, when I removed / I'm able to link properly with the css file It should be like this(without /).

<link rel="stylesheet" media="all" href="CSS/Style.css" type="text/css" />

This was giving me trouble on my project. Hope it will help somebody else.

Is there a 'foreach' function in Python 3?

Look at this article. The iterator object nditer from numpy package, introduced in NumPy 1.6, provides many flexible ways to visit all the elements of one or more arrays in a systematic fashion.


import random
import numpy as np

ptrs = np.int32([[0, 0], [400, 0], [0, 400], [400, 400]])

for ptr in np.nditer(ptrs, op_flags=['readwrite']):
    # apply random shift on 1 for each element of the matrix
    ptr += random.choice([-1, 1])


[[ -1   1]
 [399  -1]
 [  1 399]
 [399 401]]

How do I change the IntelliJ IDEA default JDK?

I am using IntelliJ 2020.3.1 and the File > Other Settings... menu option has disappeared. I went to Settings in the usual way and searched for "jdk". Under Build, Execution, Deployment > Build Tools > Maven > Importing I found the the setting that will solve my specific issue:

JDK for importer.

IntelliJ 2020.3 Settings dialog

chart.js load totally new data

I had huge problems with this

First I tried .clear() then I tried .destroy() and I tried setting my chart reference to null

What finally fixed the issue for me: deleting the <canvas> element and then reappending a new <canvas> to the parent container

There's a million ways to do this:

var resetCanvas = function () {
  $('#results-graph').remove(); // this is my <canvas> element
  $('#graph-container').append('<canvas id="results-graph"><canvas>');
  canvas = document.querySelector('#results-graph'); // why use jQuery?
  ctx = canvas.getContext('2d');
  ctx.canvas.width = $('#graph').width(); // resize to parent width
  ctx.canvas.height = $('#graph').height(); // resize to parent height

  var x = canvas.width/2;
  var y = canvas.height/2;
  ctx.font = '10pt Verdana';
  ctx.textAlign = 'center';
  ctx.fillText('This text is centered on the canvas', x, y);

Bootstrap 4 File Input

Bootstrap 4

More details are here

Today I need to create a browse button with multi-upload files option all above snippets are not good for me.

The official Bootstrap example is also not working when I select multiple files.

I come up with this code may be will help others in the future.

<div class="container mt-5">
  <h1 class="text-center">Bootstrap 4 Upload multiple files</h1>
  <div class="col-sm-4 mr-auto ml-auto border p-4">
  <form method="post" enctype="multipart/form-data" action="upload.php">
    <div class="form-group">
      <label><strong>Upload Files</strong></label>
      <div class="custom-file">
        <input type="file" name="files[]" multiple class="custom-file-input form-control" id="customFile">
        <label class="custom-file-label" for="customFile">Choose file</label>
    <div class="form-group">
      <button type="submit" name="upload" value="upload" id="upload" class="btn btn-block btn-dark"><i class="fa fa-fw fa-upload"></i> Upload</button>

The js code is given below.

$(document).ready(function() {
  $('input[type="file"]').on("change", function() {
    let filenames = [];
    let files = document.getElementById("customFile").files;
    if (files.length > 1) {
      filenames.push("Total Files (" + files.length + ")");
    } else {
      for (let i in files) {
        if (files.hasOwnProperty(i)) {

The working code example is given here with bootstrap 3 and bootstrap 4.3.1.

Find and replace specific text characters across a document with JS

I think you may be overthinking this.

My approach is simple.

Enclose you page with a div tag:

<div id="mydiv">
<!-- you page here -->

In your javascript:

var html=document.getElementById('mydiv').innerHTML;
html = html.replace(/this/g,"that");

Android Spinner: Get the selected item change event

By default, you will get the first item of the spinner array through

value = spinner.getSelectedItem().toString();

whenever you selected the value in the spinner this will give you the selected value

if you want the position of the selected item then do it like that

pos = spinner.getSelectedItemPosition();

the above two answers are for without applying listener

How to call one shell script from another shell script?

Depends on. Briefly... If you want load variables on current console and execute you may use source on your code. Example:

set -x
echo "This is an example of run another INTO this session."
echo "The function internal_function() is defined into my lib."
echo $this_is_an_internal_variable

set +x

If you just want to execute a file and the only thing intersting for you is the result, you can do:

set -x
set +x

I hope helps you. Thanks.

Add "Appendix" before "A" in thesis TOC

You can easily achieve what you want using the appendix package. Here's a sample file that shows you how. The key is the titletoc option when calling the package. It takes whatever value you've defined in \appendixname and the default value is Appendix.


\chapter{Lorem ipsum}
\section{Dolor sit amet}
  \chapter{Consectetur adipiscing elit}
  \chapter{Mauris euismod}

The output looks like

enter image description here

Java collections convert a string to a list of characters

Create an empty list of Character and then make a loop to get every character from the array and put them in the list one by one.

List<Character> characterList = new ArrayList<Character>();
char arrayChar[] = abc.toCharArray();
for (char aChar : arrayChar) 
    characterList.add(aChar); //  autoboxing 

Business logic in MVC

This is an answered question, but I'll give my "one cent":

Business rules belong in the model. The "model" always consists of (logically or physically separated):

  • presentation model - a set of classes that is well suited for use in the view (it's tailored toward specific UI/presentation),
  • domain model - the UI-independent portion of the model, and
  • repository - the storage-aware portion of the "model".

Business rules live in the domain model, are exposed in a presentation-suitable form to the "presentation" model and are sometimes duplicated (or also enforced) in the "data layer".

Python "extend" for a dictionary

As others have mentioned, a.update(b) for some dicts a and b will achieve the result you've asked for in your question. However, I want to point out that many times I have seen the extend method of mapping/set objects desire that in the syntax a.extend(b), a's values should NOT be overwritten by b's values. a.update(b) overwrites a's values, and so isn't a good choice for extend.

Note that some languages call this method defaults or inject, as it can be thought of as a way of injecting b's values (which might be a set of default values) in to a dictionary without overwriting values that might already exist.

Of course, you could simple note that a.extend(b) is nearly the same as b.update(a); a=b. To remove the assignment, you could do it thus:

def extend(a,b):
    """Create a new dictionary with a's properties extended by b,
    without overwriting.

    >>> extend({'a':1,'b':2},{'b':3,'c':4})
    {'a': 1, 'c': 4, 'b': 2}
    return dict(b,**a)

Thanks to Tom Leys for that smart idea using a side-effect-less dict constructor for extend.

Android - Spacing between CheckBox and text

Android 4.2 Jelly Bean (API 17) puts the text paddingLeft from the buttonDrawable (ints right edge). It also works for RTL mode.

Before 4.2 paddingLeft was ignoring the buttonDrawable - it was taken from the left edge of the CompoundButton view.

You can solve it via XML - set paddingLeft to buttonDrawable.width + requiredSpace on older androids. Set it to requiredSpace only on API 17 up. For example use dimension resources and override in values-v17 resource folder.

The change was introduced via android.widget.CompoundButton.getCompoundPaddingLeft();

How to escape a while loop in C#

Use break; to escape the first loop:

if (s.Contains("mp4:production/CATCHUP/"))
   Process p = new Process();
   p.StartInfo.WorkingDirectory = "dump";
   p.StartInfo.FileName = "test.exe"; 
   p.StartInfo.Arguments = s; 

If you want to also escape the second loop, you might need to use a flag and check in the out loop's guard:

        boolean breakFlag = false;
        while (!breakFlag)
            if (!System.IO.File.Exists("Command.bat")) continue;
            using (System.IO.StreamReader sr = System.IO.File.OpenText("Command.bat"))
                string s = "";
                while ((s = sr.ReadLine()) != null)
                    if (s.Contains("mp4:production/CATCHUP/"))


                        Process p = new Process();
                        p.StartInfo.WorkingDirectory = "dump";
                        p.StartInfo.FileName = "test.exe"; 
                        p.StartInfo.Arguments = s; 

                        breakFlag = true;

Or, if you want to just exit the function completely from within the nested loop, put in a return; instead of a break;.

But these aren't really considered best practices. You should find some way to add the necessary Boolean logic into your while guards.

How do you use the ? : (conditional) operator in JavaScript?

It's called the 'ternary' or 'conditional' operator.


The ?: operator can be used as a shortcut for an if...else statement. It is typically used as part of a larger expression where an if...else statement would be awkward. For example:

var now = new Date();
var greeting = "Good" + ((now.getHours() > 17) ? " evening." : " day.");

The example creates a string containing "Good evening." if it is after 6pm. The equivalent code using an if...else statement would look as follows:

var now = new Date();
var greeting = "Good";
if (now.getHours() > 17)
   greeting += " evening.";
   greeting += " day.";

From MSDN JS documentation.

Basically it's a shorthand conditional statement.

Also see:

Scraping html tables into R data frames using the XML package

The rvest along with xml2 is another popular package for parsing html web pages.

theurl <- ""
tables<-html_nodes(file, "table")
table1 <- html_table(tables[4], fill = TRUE)

The syntax is easier to use than the xml package and for most web pages the package provides all of the options ones needs.

An URL to a Windows shared folder

File protocol URIs are like this


that's why you often see file URLs like this (3 slashes) file:///c:\path...

So if the host is server01, you want


This is according to the wikipedia page on file:// protocols and checks out with .NET's Uri.IsWellFormedUriString method.

Java Error: illegal start of expression

Methods can only declare local variables. That is why the compiler reports an error when you try to declare it as public.

In the case of local variables you can not use any kind of accessor (public, protected or private).

You should also know what the static keyword means. In method checkYourself, you use the Integer array locations.

The static keyword distinct the elements that are accessible with object creation. Therefore they are not part of the object itself.

public class Test { //Capitalized name for classes are used in Java
   private final init[] locations; //key final mean that, is must be assigned before object is constructed and can not be changed later. 

   public Test(int[] locations) {
      this.locations = locations;//To access to class member, when method argument has the same name use `this` key word. 

   public boolean checkYourSelf(int value) { //This method is accessed only from a object.
      for(int location : locations) {
         if(location == value) {
            return true; //When you use key word return insied of loop you exit from it. In this case you exit also from whole method.
      return false; //Method should be simple and perform one task. So you can get more flexibility. 
   public static int[] locations = {1,2,3};//This is static array that is not part of object, but can be used in it. 

   public static void main(String[] args) { //This is declaration of public method that is not part of create object. It can be accessed from every place.
      Test test = new Test(Test.locations); //We declare variable test, and create new instance (object) of class Test.  
      String result;
      if(test.checkYourSelf(2)) {//We moved outside the string
        result = "Hurray";        
      } else {
        result = "Try again"
      System.out.println(result); //We have only one place where write is done. Easy to change in future.

Configure hibernate (using JPA) to store Y/N for type Boolean instead of 0/1

I used the concept from the answer posted by @marcg and it works great with JPA 2.1. His code wasn't quite right, so I'm posted my working implementation. This will convert Boolean entity fields to a Y/N character column in the database.

From my entity class:

@Column(name="LOADED", length=1)
private Boolean isLoadedSuccessfully;

My converter class:

 * Converts a Boolean entity attribute to a single-character
 * Y/N string that will be stored in the database, and vice-versa
 * @author jtough
public class BooleanToYNStringConverter 
        implements AttributeConverter<Boolean, String> {

     * This implementation will return "Y" if the parameter is Boolean.TRUE,
     * otherwise it will return "N" when the parameter is Boolean.FALSE. 
     * A null input value will yield a null return value.
     * @param b Boolean
    public String convertToDatabaseColumn(Boolean b) {
        if (b == null) {
            return null;
        if (b.booleanValue()) {
            return "Y";
        return "N";

     * This implementation will return Boolean.TRUE if the string
     * is "Y" or "y", otherwise it will ignore the value and return
     * Boolean.FALSE (it does not actually look for "N") for any
     * other non-null string. A null input value will yield a null
     * return value.
     * @param s String
    public Boolean convertToEntityAttribute(String s) {
        if (s == null) {
            return null;
        if (s.equals("Y") || s.equals("y")) {
            return Boolean.TRUE;
        return Boolean.FALSE;


This variant is also fun if you love emoticons and are just sick and tired of Y/N or T/F in your database. In this case, your database column must be two characters instead of one. Probably not a big deal.

 * Converts a Boolean entity attribute to a happy face or sad face
 * that will be stored in the database, and vice-versa
 * @author jtough
public class BooleanToHappySadConverter 
        implements AttributeConverter<Boolean, String> {

    public static final String HAPPY = ":)";
    public static final String SAD = ":(";

     * This implementation will return ":)" if the parameter is Boolean.TRUE,
     * otherwise it will return ":(" when the parameter is Boolean.FALSE. 
     * A null input value will yield a null return value.
     * @param b Boolean
     * @return String or null
    public String convertToDatabaseColumn(Boolean b) {
        if (b == null) {
            return null;
        if (b) {
            return HAPPY;
        return SAD;

     * This implementation will return Boolean.TRUE if the string
     * is ":)", otherwise it will ignore the value and return
     * Boolean.FALSE (it does not actually look for ":(") for any
     * other non-null string. A null input value will yield a null
     * return value.
     * @param s String
     * @return Boolean or null
    public Boolean convertToEntityAttribute(String s) {
        if (s == null) {
            return null;
        if (HAPPY.equals(s)) {
            return Boolean.TRUE;
        return Boolean.FALSE;


Downloading a picture via urllib and python

Using requests

import requests
import shutil,os

headers = {
    'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36'
currentDir = os.getcwd()
path = os.path.join(currentDir,'Images')#saving images to Images folder

def ImageDl(url):
    attempts = 0
    while attempts < 5:#retry 5 times
            filename = url.split('/')[-1]
            r = requests.get(url,headers=headers,stream=True,timeout=5)
            if r.status_code == 200:
                with open(os.path.join(path,filename),'wb') as f:
                    r.raw.decode_content = True
        except Exception as e:

if __name__ == '__main__':

What's the best way to determine which version of Oracle client I'm running?

You should put a semicolon at the end of select * from v$version;.

Like this you will get all info you need...

If you are looking just for Oracle for example you can do as:

SQL> select * from v$version where banner like 'Oracle%';

Spring Boot Adding Http Request Interceptors

To add interceptor to a spring boot application, do the following

  1. Create an interceptor class

    public class MyCustomInterceptor implements HandlerInterceptor{
        //unimplemented methods comes here. Define the following method so that it     
        //will handle the request before it is passed to the controller.
        public boolean preHandle(HttpServletRequest request,HttpServletResponse  response){
        //your custom logic here.
            return true;
  2. Define a configuration class

    public class MyConfig extends WebMvcConfigurerAdapter{
        public void addInterceptors(InterceptorRegistry registry){
            registry.addInterceptor(new MyCustomInterceptor()).addPathPatterns("/**");
  3. Thats it. Now all your requests will pass through the logic defined under preHandle() method of MyCustomInterceptor.

UICollectionView current visible cell index

It will probably be best to use UICollectionViewDelegate methods: (Swift 3)

// Called before the cell is displayed    
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {

// Called when the cell is displayed
func collectionView(_ collectionView: UICollectionView, didEndDisplaying cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {

Using css transform property in jQuery

Setting a -vendor prefix that isn't supported in older browsers can cause them to throw an exception with .css. Instead detect the supported prefix first:

// Start with a fall back
var newCss = { 'zoom' : ui.value };

// Replace with transform, if supported
if('WebkitTransform' in 
    newCss = { '-webkit-transform': 'scale(' + ui.value + ')'};
// repeat for supported browsers
else if('transform' in 
    newCss = { 'transform': 'scale(' + ui.value + ')'};

// Set the CSS

That works in old browsers. I've done scale here but you could replace it with whatever other transform you wanted.

MySql Query Replace NULL with Empty String in Select

select IFNULL(`prereq`,'') as ColumnName FROM test

this query is selecting "prereq" values and if any one of the values are null it show an empty string as you like So, it shows all values but the NULL ones are showns in blank

Auto increment in phpmyadmin

This is due to the wp_terms, wp_termmeta and wp_term_taxonomy tables, which had all their ID's not set to AUTO_INCREMENT

To do this go to phpmyadmin, click on the concern database, wp_terms table, click on structure Tab, at right side you will see a tab named A_I(AUTO_INCREMENT), check it and save (You are only doing this for the first option, in the case wp_term you are only doing it for term_id).

Do the same for wp_termmeta and wp_term_taxonomy that will fix the issue.

"unadd" a file to svn before commit

svn rm --keep-local folder_name

Note: In svn 1.5.4 svn rm deletes unversioned files even when --keep-local is specified. See for more information.

How to use Global Variables in C#?

First examine if you really need a global variable instead using it blatantly without consideration to your software architecture.

Let's assuming it passes the test. Depending on usage, Globals can be hard to debug with race conditions and many other "bad things", it's best to approach them from an angle where you're prepared to handle such bad things. So,

  1. Wrap all such Global variables into a single static class (for manageability).
  2. Have Properties instead of fields(='variables'). This way you have some mechanisms to address any issues with concurrent writes to Globals in the future.

The basic outline for such a class would be:

public class Globals
    private static bool _expired;
    public static bool Expired 
            // Reads are usually simple
            return _expired;
            // You can add logic here for race conditions,
            // or other measurements
            _expired = value;
    // Perhaps extend this to have Read-Modify-Write static methods
    // for data integrity during concurrency? Situational.

Usage from other classes (within same namespace)

// Read
bool areWeAlive = Globals.Expired;

// Write
// past deadline
Globals.Expired = true;

mongodb group values by multiple fields

Below query will provide exactly the same result as given in the desired response:

        $group: {
            _id: { addresses: "$addr", books: "$book" },
            num: { $sum :1 }
        $group: {
            _id: "$_id.addresses",
            bookCounts: { $push: { bookName: "$_id.books",count: "$num" } }
        $project: {
            _id: 1,
            "totalBookAtAddress": {
                "$sum": "$bookCounts.count"


The response will be looking like below:

/* 1 */
    "_id" : "address4",
    "bookCounts" : [
            "bookName" : "book3",
            "count" : 1
    "totalBookAtAddress" : 1

/* 2 */
    "_id" : "address90",
    "bookCounts" : [
            "bookName" : "book33",
            "count" : 1
    "totalBookAtAddress" : 1

/* 3 */
    "_id" : "address15",
    "bookCounts" : [
            "bookName" : "book1",
            "count" : 1
    "totalBookAtAddress" : 1

/* 4 */
    "_id" : "address3",
    "bookCounts" : [
            "bookName" : "book9",
            "count" : 1
    "totalBookAtAddress" : 1

/* 5 */
    "_id" : "address5",
    "bookCounts" : [
            "bookName" : "book1",
            "count" : 1
    "totalBookAtAddress" : 1

/* 6 */
    "_id" : "address1",
    "bookCounts" : [
            "bookName" : "book1",
            "count" : 3
            "bookName" : "book5",
            "count" : 1
    "totalBookAtAddress" : 4

/* 7 */
    "_id" : "address2",
    "bookCounts" : [
            "bookName" : "book1",
            "count" : 2
            "bookName" : "book5",
            "count" : 1
    "totalBookAtAddress" : 3

/* 8 */
    "_id" : "address77",
    "bookCounts" : [
            "bookName" : "book11",
            "count" : 1
    "totalBookAtAddress" : 1

/* 9 */
    "_id" : "address9",
    "bookCounts" : [
            "bookName" : "book99",
            "count" : 1
    "totalBookAtAddress" : 1

Compiling Java 7 code via Maven

Check the mvn script in your maven installation to see how it's building the command. Perhaps you or someone else has hard-coded a JAVA_HOME in there and forgotten about it.

Oracle Add 1 hour in SQL

select sysdate + 1/24 from dual;

sysdate is a function without arguments which returns DATE type
+ 1/24 adds 1 hour to a date

select to_char(to_date('2014-10-15 03:30:00 pm', 'YYYY-MM-DD HH:MI:SS pm') + 1/24, 'YYYY-MM-DD HH:MI:SS pm') from dual;

Create iOS Home Screen Shortcuts on Chrome for iOS

Can't change the default browser, but try this (found online a while ago). Add a bookmark in Safari called "Open in Chrome" with the following.


Will open the current page in Chrome. Not as convenient, but maybe someone will find it useful.


Works for me.

jquery ajax function not working

you need to prevent the default behavior of your form when submitting

by adding this:

$("#postcontent").on('submit' , function(e) {


  //then the rest of your code

Convert JSON String to JSON Object c#

string result = await resp.Content.ReadAsStringAsync(); List _Resp = JsonConvert.DeserializeObject<List>(result); //List _objList = new List((IEnumerable)_Resp);

            IList usll = _Resp.Select(a => a.lttsdata).ToList();
            // List<ListViewClass> _objList = new List<ListViewClass>((IEnumerable<ListViewClass>)_Resp);
            //IList usll = _objList.OrderBy(a=> a.ReqID).ToList();
            Lv.ItemsSource = usll;

Is it possible to write to the console in colour in .NET?

Yes, it's easy and possible. Define first default colors.

Console.BackgroundColor = ConsoleColor.Black;
Console.ForegroundColor = ConsoleColor.White;

Console.Clear() it's important in order to set new console colors. If you don't make this step you can see combined colors when ask for values with Console.ReadLine().

Then you can change the colors on each print:

Console.BackgroundColor = ConsoleColor.Black;
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("Red text over black.");

When finish your program, remember reset console colors on finish:


Now with netcore we have another problem if you want to "preserve" the User experience because terminal have different colors on each Operative System.

I'm making a library that solves this problem with Text Format: colors, alignment and lot more. Feel free to use and contribute. and also available as NuGet package

Colors for Windows/Linux (Dark):
enter image description here

Colors for MacOS (Light):
enter image description here

How do I list all loaded assemblies?

Here's what I ended up with. It's a listing of all properties and methods, and I listed all parameters for each method. I didn't succeed on getting all of the values.

foreach(System.Reflection.AssemblyName an in System.Reflection.Assembly.GetExecutingAssembly().GetReferencedAssemblies()){                      
            System.Reflection.Assembly asm = System.Reflection.Assembly.Load(an.ToString());
            foreach(Type type in asm.GetTypes()){   
                foreach (System.Reflection.PropertyInfo property in type.GetProperties()){
                    if (property.CanRead){
                        Response.Write("<br>" + an.ToString() + "." + type.ToString() + "." + property.Name);       
                var methods = type.GetMethods();
                foreach (System.Reflection.MethodInfo method in methods){               
                    Response.Write("<br><b>" + an.ToString() + "."  + type.ToString() + "." + method.Name  + "</b>");   
                    foreach (System.Reflection.ParameterInfo param in method.GetParameters())
                        Response.Write("<br><i>Param=" + param.Name.ToString());
                        Response.Write("<br>  Type=" + param.ParameterType.ToString());
                        Response.Write("<br>  Position=" + param.Position.ToString());
                        Response.Write("<br>  Optional=" + param.IsOptional.ToString() + "</i>");

How to catch a specific SqlException error?

With MS SQL 2008, we can list supported error messages in the table sys.messages

SELECT * FROM sys.messages

Angular2 Exception: Can't bind to 'routerLink' since it isn't a known native property


import the RouterModule See also

  imports: [RouterModule],



import { provideRouter, RouterConfig } from '@angular/router';

export const routes: RouterConfig = [

export const APP_ROUTER_PROVIDERS = [provideRouter(routes)];


import { bootstrap } from '@angular/platform-browser-dynamic';
import { APP_ROUTER_PROVIDERS } from './app.routes';

bootstrap(AppComponent, [APP_ROUTER_PROVIDERS]);


Your code is missing

    directives: [ROUTER_DIRECTIVES],

You can't use directives like routerLink or router-outlet without making them known to your component.

While directive names were changed to be case-sensitive in Angular2, elements still use - in the name like <router-outlet> to be compatible with the web-components spec which require a - in the name of custom elements.

register globally

To make ROUTER_DIRECTIVES globally available, add this provider to bootstrap(...):

provide(PLATFORM_DIRECTIVES, {useValue: [ROUTER_DIRECTIVES], multi: true})

then it's no longer necessary to add ROUTER_DIRECTIVES to each component.

Java optional parameters

There are no optional parameters in Java. What you can do is overloading the functions and then passing default values.

void SomeMethod(int age, String name) {

// Overload
void SomeMethod(int age) {
    SomeMethod(age, "John Doe");

Good beginners tutorial to

To start with Socket.IO I suggest you read first the example on the main page:

On the server side, read the "How to use" on the GitHub source page:

And on the client side:

Finally you need to read this great tutorial:

Hint: At the end of this blog post, you will have some links pointing on source code that could be some help.

Check whether a string contains a substring

To find out if a string contains substring you can use the index function:

if (index($str, $substr) != -1) {
    print "$str contains $substr\n";

It will return the position of the first occurrence of $substr in $str, or -1 if the substring is not found.

What is 'Context' on Android?

Instances of the the class android.content.Context provide the connection to the Android system which executes the application. For example, you can check the size of the current device display via the Context.

It also gives access to the resources of the project. It is the interface to global information about the application environment.

The Context class also provides access to Android services, e.g., the alarm manager to trigger time based events.

Activities and services extend the Context class. Therefore they can be directly used to access the Context.

How to set up Spark on Windows?

Steps to install Spark in local mode:

  1. Install Java 7 or later. To test java installation is complete, open command prompt type java and hit enter. If you receive a message 'Java' is not recognized as an internal or external command. You need to configure your environment variables, JAVA_HOME and PATH to point to the path of jdk.

  2. Download and install Scala.

    Set SCALA_HOME in Control Panel\System and Security\System goto "Adv System settings" and add %SCALA_HOME%\bin in PATH variable in environment variables.

  3. Install Python 2.6 or later from Python Download link.

  4. Download SBT. Install it and set SBT_HOME as an environment variable with value as <<SBT PATH>>.

  5. Download winutils.exe from HortonWorks repo or git repo. Since we don't have a local Hadoop installation on Windows we have to download winutils.exe and place it in a bin directory under a created Hadoop home directory. Set HADOOP_HOME = <<Hadoop home directory>> in environment variable.

  6. We will be using a pre-built Spark package, so choose a Spark pre-built package for Hadoop Spark download. Download and extract it.

    Set SPARK_HOME and add %SPARK_HOME%\bin in PATH variable in environment variables.

  7. Run command: spark-shell

  8. Open http://localhost:4040/ in a browser to see the SparkContext web UI.

How can I order a List<string>?

Other answers are correct to suggest Sort, but they seem to have missed the fact that the storage location is typed as IList<string. Sort is not part of the interface.

If you know that ListaServizi will always contain a List<string>, you can either change its declared type, or use a cast. If you're not sure, you can test the type:

if (typeof(List<string>).IsAssignableFrom(ListaServizi.GetType()))
    //... some other solution; there are a few to choose from.

Perhaps more idiomatic:

List<string> typeCheck = ListaServizi as List<string>;
if (typeCheck != null)
    //... some other solution; there are a few to choose from.

If you know that ListaServizi will sometimes hold a different implementation of IList<string>, leave a comment, and I'll add a suggestion or two for sorting it.

How can I center <ul> <li> into div

If you know the width of the ul then you can simply set the margin of the ul to 0 auto;

This will align the ul in the middle of the containing div



<div id="container">


  #container ul{
    margin:0 auto;

MySQL: ignore errors when importing?

Use the --force (-f) flag on your mysql import. Rather than stopping on the offending statement, MySQL will continue and just log the errors to the console.

For example:

mysql -u userName -p -f -D dbName < script.sql

Text in HTML Field to disappear when clicked?

Simple as this: <input type="text" name="email" value="e-mail..." onFocus="this.value=''">

How can I take an UIImage and give it a black border?

For those looking for a plug-and-play solution on UIImage, I wrote CodyMace's answer as an extension.

Usage: let outlined = UIImage(named: "something")?.outline()

extension UIImage {

    func outline() -> UIImage? {

        let size = CGSize(width: self.size.width, height: self.size.height)
        let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
        self.draw(in: rect, blendMode: .normal, alpha: 1.0)
        let context = UIGraphicsGetCurrentContext()
        context?.setStrokeColor(red: 0, green: 0, blue: 0, alpha: 1)
        let newImage = UIGraphicsGetImageFromCurrentImageContext()

        return newImage



Is there a C# case insensitive equals operator?

You can use

if (stringA.equals(StringB, StringComparison.CurrentCultureIgnoreCase))

how to query child objects in mongodb

Assuming your "states" collection is like:

{"name" : "Spain", "cities" : [ { "name" : "Madrid" }, { "name" : null } ] }
{"name" : "France" }

The query to find states with null cities would be:

db.states.find({"" : {"$eq" : null, "$exists" : true}});

It is a common mistake to query for nulls as:

db.states.find({"" : null});

because this query will return all documents lacking the key (in our example it will return Spain and France). So, unless you are sure the key is always present you must check that the key exists as in the first query.

Setting a max character length in CSS

You could always use a truncate method by setting a max-width and overflow ellipsis like this

p {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 200px;

An example:

.wrapper {
  padding: 20px;
  background: #eaeaea;
  max-width: 400px;
  margin: 50px auto;

.demo-1 {
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;

.demo-2 {
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  max-width: 150px;
<div class="wrapper">
  <p class="demo-1">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ut odio temporibus voluptas error distinctio hic quae corrupti vero doloribus optio! Inventore ex quaerat modi blanditiis soluta maiores illum, ab velit.</p>

<div class="wrapper">
  <p class="demo-2">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ut odio temporibus voluptas error distinctio hic quae corrupti vero doloribus optio! Inventore ex quaerat modi blanditiis soluta maiores illum, ab velit.</p>

For a multi-line truncation have a look at a flex solution. An example with truncation on 3 rows.

p {
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;

An example:

p {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 200px;
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Deserunt rem odit quis quaerat. In dolorem praesentium velit ea esse consequuntur cum fugit sequi voluptas ut possimus voluptatibus deserunt nisi eveniet!</p>

Django Rest Framework -- no module named rest_framework

I've faced the same problem, followed these instructions and it worked for me:

  1. python -m pip install --upgrade pip (to upgrade pip)
  2. pip3 install djangorestframework
  3. Added rest_framework as first app:


MySQL: Can't create table (errno: 150)

execute below line:

FOREIGN_KEY_CHECKS option specifies whether or not to check foreign key constraints for InnoDB tables. 

-- Specify to check foreign key constraints (this is the default)


-- Do not check foreign key constraints


When to Use :
Temporarily disabling referential constraints (set FOREIGN_KEY_CHECKS to 0) is useful when you need to re-create the tables and load data in any parent-child order.