Programs & Examples On #Inexact arithmetic

How to create many labels and textboxes dynamically depending on the value of an integer variable?

Here is a simple example that should let you keep going add somethink that would act as a placeholder to your winform can be TableLayoutPanel

and then just add controls to it

   for ( int i = 0; i < COUNT; i++ ) {

    Label lblTitle = new Label();
    lblTitle.Text = i+"Your Text";
    youlayOut.Controls.Add( lblTitle, 0, i );

    TextBox txtValue = new TextBox();
    youlayOut.Controls.Add( txtValue, 2, i );

How can I run multiple npm scripts in parallel?

... but that will wait for start-watch to finish before running wp-server.

For that to work, you will have to use start on your command. Others have already illustrated but this is how it will work, your code below:

"dev": "npm run start-watch && npm run wp-server"

Should be :

"dev": " start npm run start-watch && start npm run wp-server"

What this will do is, it will open a separate instance for each command and process them concurrently, which shouldn't be an issue as far as your initial issue is concerned. Why do I say so? It's because these instances both open automatically while you run only 1 statement, which is your initial goal.

How do I set an absolute include path in PHP?

There is nothing in include/require that prohibits you from using absolute an path. so your example


should work just fine. Assuming the path and file are corect and have the correct permissions set.
(and thereby allow you to include whatever file you like, in- or outside your document root)

This behaviour is however considered to be a possible security risk. Therefore, the system administrator can set the open_basedir directive.

This directive configures where you can include/require your files from and it might just be your problem.
Some control panels (plesk for example) set this directive to be the same as the document root by default.

as for the '.' syntax:

/home/username/public_html <- absolute path  
public_html <- relative path  
./public_html <- same as the path above  
../username/public_html <- another relative path  

However, I usually use a slightly different option:

require_once(__DIR__ . '/Factories/ViewFactory.php');

With this edition, you specify an absolute path, relative to the file that contains the require_once() statement.

phpMyAdmin - configuration?

Have a look at you will find examples of the configuration directives that you should copy to your (copy the missing ones). Then, have a look at examples/create_tables.sql which will help you create the missing tables.

The complete documentation for this is available at

C++ IDE for Linux?

Sun Studio version 12 is a free download(FREE and paid support available) --

I'm sure you have code completion and debugging support including plugin support in this IDE.

Sun Studio is available for Linux as well as Solaris. forums : Sun Studio Linux forums :

I'll be eager to hear your feedback on this tool.


How to fix the datetime2 out-of-range conversion error using DbContext and SetInitializer?

You have to ensure that Start is greater than or equal to SqlDateTime.MinValue (January 1, 1753) - by default Start equals DateTime.MinValue (January 1, 0001).

How to get URL of current page in PHP

You can use $_SERVER['HTTP_REFERER'] this will give you whole URL for example:

suppose you want to get url of site name then $_SERVER['HTTP_REFERER'] will give you

PHP removing a character in a string

While a regexp would suit here just fine, I'll present you with an alternative method. It might be a tad faster than the equivalent regexp, but life's all about choices (...or something).

$length = strlen($urlString);
for ($i=0; $i<$length; i++) {
  if ($urlString[$i] === '?') {
    $urlString[$i+1] = '';

Weird, I know.

Server.Transfer Vs. Response.Redirect

Response.Redirect simply sends a message (HTTP 302) down to the browser.

Server.Transfer happens without the browser knowing anything, the browser request a page, but the server returns the content of another.

How to search in a List of Java object

As your list is an ArrayList, it can be assumed that it is unsorted. Therefore, there is no way to search for your element that is faster than O(n).

If you can, you should think about changing your list into a Set (with HashSet as implementation) with a specific Comparator for your sample class.

Another possibility would be to use a HashMap. You can add your data as Sample (please start class names with an uppercase letter) and use the string you want to search for as key. Then you could simply use

Sample samp = myMap.get(myKey);

If there can be multiple samples per key, use Map<String, List<Sample>>, otherwise use Map<String, Sample>. If you use multiple keys, you will have to create multiple maps that hold the same dataset. As they all point to the same objects, space shouldn't be that much of a problem.

PostgreSQL next value of the sequences?

I tried this and it works perfectly

public class Shipwreck {
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq")
  @Basic(optional = false)
  @SequenceGenerator(name = "seq", sequenceName = "shipwreck_seq", allocationSize = 1)
  Long id;


CREATE SEQUENCE public.shipwreck_seq
    START 110
    MAXVALUE 9223372036854775807
    CACHE 1;

What is a Subclass

A sub class is a small file of a program that extends from some other class. For example you make a class about cars in general and have basic information that holds true for all cars with your constructors and stuff then you have a class that extends from that on a more specific car or line of cars that would have new variables/methods. I see you already have plenty of examples of code from above by the time I get to post this but I hope this description helps.

Why would a " Connection timed out" exception occur when URL is up?

The error message says it all: your connection timed out. This means your request did not get a response within some (default) timeframe. The reasons that no response was received is likely to be one of:

a) The IP/domain or port is incorrect

b) The IP/domain or port (i.e service) is down

c) The IP/domain is taking longer than your default timeout to respond

d) You have a firewall that is blocking requests or responses on whatever port you are using

e) You have a firewall that is blocking requests to that particular host

f) Your internet access is down

g) Your live-server is down i.e in case of "rest-API call".

Note that firewalls and port or IP blocking may be in place by your ISP

Python __call__ special method practical example

The function call operator.

class Foo:
    def __call__(self, a, b, c):
        # do something

x = Foo()
x(1, 2, 3)

The __call__ method can be used to redefined/re-initialize the same object. It also facilitates the use of instances/objects of a class as functions by passing arguments to the objects.

Constants in Objective-C

If you want to call something like this NSString.newLine; from objective c, and you want it to be static constant, you can create something like this in swift:

public extension NSString {
    @objc public static let newLine = "\n"

And you have nice readable constant definition, and available from within a type of your choice while stile bounded to context of type.

Failed to load resource under Chrome

FYI - I had this issue as well and it turned out that my html listed the .jpg file with a .JPG in caps, but the file itself was lowercase .jpg. That rendered fine locally and using Codekit, but when it was pushed to the web it wouldn't load. Simply changing the file names to have a lowercase .jpg extension to match the html did the trick.

Redirecting 404 error with .htaccess via 301 for SEO etc

I came up with the solution and posted it on my blog

here is the htaccess code also

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . / [L,R=301]

but I posted other solutions on my blog too, it depends what you need really

What is console.log in jQuery?

It has nothing to do with jQuery, it's just a handy js method built into modern browsers.

Think of it as a handy alternative to debugging via window.alert()

HTML5 live streaming

Right now it will only work in some browsers, and as far as I can see you haven't actually linked to a file, so that would explain why it is not playing.

but as you want a live stream (which I have not tested with)

check out Streaming via RTSP or RTP in HTML5


What is the difference between visibility:hidden and display:none?

display:none will hide the element and collapse the space is was taking up, whereas visibility:hidden will hide the element and preserve the elements space. display:none also effects some of the properties available from javascript in older versions of IE and Safari.

How do I run a Python program in the Command Prompt in Windows 7?

So after 30 min of R&D i realized that after setup the PATH at environment variable


" C:\Python/27; "

just restart

now open cmd :

C:> cd Python27 C:\ Python27> python.exe

USE python.exe with extension

alternative option is :

if the software is installed properly directly run Python program, your command line screen will automatically appear without cmd.


Concatenating Column Values into a Comma-Separated List

If you are running on SQL Server 2017 or Azure SQL Database you do something like this :

 SELECT STRING_AGG(CarName,',') as CarNames

Printing pointers in C

It's not a pointer to character char* but a pointer to array of 4 characters: char* [4]. With g++ it doesn't compile:

main.cpp: In function ‘int main(int, char**)’: main.cpp:126: error: cannot convert ‘char (*)[4]’ to ‘char**’ in initialization

Moreover, the linux man pages says:


The void * pointer argument is printed in hexadecimal (as if by %#x or %#lx). It shoud be pointer to void.

You can change your code to:

char* s = "asd";
char** p = &s;

printf("The value of s is: %p\n", s);
printf("The address of s is: %p\n", &s);

printf("The value of p is: %p\n", p);
printf("The address of p is: %p\n", &p);

printf("The address of s[0] is: %p\n", &s[0]);
printf("The address of s[1] is: %p\n", &s[1]);
printf("The address of s[2] is: %p\n", &s[2]);


The value of s is: 0x403f00

The address of s is: 0x7fff2df9d588

The value of p is: 0x7fff2df9d588

The address of p is: 0x7fff2df9d580

The address of s[0] is: 0x403f00

The address of s[1] is: 0x403f01

The address of s[2] is: 0x403f02

How to get Django and ReactJS to work together?

I know this is a couple of years late, but I'm putting it out there for the next person on this journey.

GraphQL has been helpful and way easier compared to DjangoRESTFramework. It is also more flexible in terms of the responses you get. You get what you ask for and don't have to filter through the response to get what you want.

You can use Graphene Django on the server side and React+Apollo/Relay... You can look into it as that is not your question.

How to create PDFs in an Android app?

It's not easy to find a full solution of the problem of a convertion of an arbitrary HTML to PDF with non-english letters in Android. I test it for russian unicode letters.

We use three libraries:

(1) Jsoup (jsoup-1.7.3.jar) for a convertion from HTML to XHTML,

(2) iTextPDF (itextpdf-5.5.0.jar),

(3) XMLWorker (xmlworker-5.5.1.jar).

public boolean createPDF(String rawHTML, String fileName, ContextWrapper context){
    final String APPLICATION_PACKAGE_NAME = context.getBaseContext().getPackageName();
    File path = new File( Environment.getExternalStorageDirectory(), APPLICATION_PACKAGE_NAME );
    if ( !path.exists() ){ path.mkdir(); }
    File file = new File(path, fileName);


    Document document = new Document();
    PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(file));;

    // ?????????????? HTML
    String htmlText = Jsoup.clean( rawHTML, Whitelist.relaxed() );
    InputStream inputStream = new ByteArrayInputStream( htmlText.getBytes() );

    // ???????? ???????? PDF
    XMLWorkerHelper.getInstance().parseXHtml(writer, document,
        inputStream, null, Charset.defaultCharset(), new MyFont());

    return true;

    } catch (FileNotFoundException e) {
        return false;
    } catch (DocumentException e) {
        return false;
    } catch (IOException e) {
        return false;

The difficult problem is to display russian letters in PDF by using iTextPDF XMLWorker library. For this we should create our own implementation of FontProvider interface:

public class MyFont implements FontProvider{
    private static final String FONT_PATH = "/system/fonts/DroidSans.ttf";
    private static final String FONT_ALIAS = "my_font";

    public MyFont(){ FontFactory.register(FONT_PATH, FONT_ALIAS); }

    public Font getFont(String fontname, String encoding, boolean embedded,
        float size, int style, BaseColor color){

        return FontFactory.getFont(FONT_ALIAS, BaseFont.IDENTITY_H, 
            BaseFont.EMBEDDED, size, style, color);

    public boolean isRegistered(String name) { return name.equals( FONT_ALIAS ); }

Here we use the standard Android font Droid Sans, which is located in the system folder:

private static final String FONT_PATH = "/system/fonts/DroidSans.ttf";

Convert dictionary to list collection in C#

foreach (var item in dicNumber)

Saving the PuTTY session logging

To set permanent PuTTY session parameters do:

  1. Create sessions in PuTTY. Name it as "MyskinPROD"

  2. Configure the path for this session to point to "C:\dir\&Y&M&D&T_&H_putty.log".

  3. Create a Windows "Shortcut" to C:...\Putty.exe.

  4. Open "Shortcut" Properties and append "Target" line with parameters as shown below:

    "C:\Program Files (x86)\UTL\putty.exe" -ssh -load MyskinPROD user@ServerIP -pw password

Now, your PuTTY shortcut will bring in the "MyskinPROD" configuration every time you open the shortcut.

Check the screenshots and details on how I did it in my environment:

Using Cookie in Asp.Net Mvc 4

Try using Response.SetCookie(), because Response.Cookies.Add() can cause multiple cookies to be added, whereas SetCookie will update an existing cookie.

Error Running React Native App From Terminal (iOS)

1) Go to Xcode Preferences

2) Locate the location tab

3) Set the Xcode verdion in Given Command Line Tools

Now, it ll successfully work.

Can't push to the heroku

There has to be a .git directory in the root of your project.

If you don't see that directory run git init and then re-associate your remote.

Like so:

heroku git:remote -a herokuAppName
git push heroku master

Match groups in Python

Starting Python 3.8, and the introduction of assignment expressions (PEP 572) (:= operator), we can now capture the condition value, statement) in a variable (let's all it match) in order to both check if it's not None and then re-use it within the body of the condition:

if match :='I love (\w+)', statement):
  print(f'He loves {}')
elif match :="Ich liebe (\w+)", statement):
  print(f'Er liebt {}')
elif match :="Je t'aime (\w+)", statement):
  print(f'Il aime {}')

Base 64 encode and decode example code

'java.util.Base64' class provides functionality to encode and decode the information in Base64 format.

How to get Base64 Encoder?

Encoder encoder = Base64.getEncoder();

How to get Base64 Decoder?

Decoder decoder = Base64.getDecoder();

How to encode the data?

Encoder encoder = Base64.getEncoder();
String originalData = "java";
byte[] encodedBytes = encoder.encode(originalData.getBytes());

How to decode the data?

Decoder decoder = Base64.getDecoder();
byte[] decodedBytes = decoder.decode(encodedBytes);
String decodedStr = new String(decodedBytes);

You can get more details at this link.

Populate XDocument from String

You can use XDocument.Parse(string) instead of Load(string).

Can I redirect the stdout in python into some sort of string buffer?

Here's another take on this. contextlib.redirect_stdout with io.StringIO() as documented is great, but it's still a bit verbose for every day use. Here's how to make it a one-liner by subclassing contextlib.redirect_stdout:

import sys
import io
from contextlib import redirect_stdout

class capture(redirect_stdout):

    def __init__(self):
        self.f = io.StringIO()
        self._new_target = self.f
        self._old_targets = []  # verbatim from parent class

    def __enter__(self):
        self._old_targets.append(getattr(sys, self._stream))  # verbatim from parent class
        setattr(sys, self._stream, self._new_target)  # verbatim from parent class
        return self  # instead of self._new_target in the parent class

    def __repr__(self):
        return self.f.getvalue()  

Since __enter__ returns self, you have the context manager object available after the with block exits. Moreover, thanks to the __repr__ method, the string representation of the context manager object is, in fact, stdout. So now you have,

with capture() as message:
    print('Hello World!')
print(str(message)=='Hello World!\n')  # returns True

Function pointer as a member of a C struct

My guess is that part of your problem is the parameter lists not matching.

int (* length)();


int length(PString * self)

are not the same. It should be int (* length)(PString *);.

...woah, it's Jon!

Edit: and, as mentioned below, your struct pointer is never set to point to anything. The way you're doing it would only work if you were declaring a plain struct, not a pointer.

str = (PString *)malloc(sizeof(PString));

How can I confirm a database is Oracle & what version it is using SQL?

If your instance is down, you are look for version information in alert.log

Or another crude way is to look into Oracle binary, If DB in hosted on Linux, try strings on Oracle binary.

strings -a $ORACLE_HOME/bin/oracle |grep RDBMS | grep RELEASE

SOAP request to WebService with java

When the WSDL is available, it is just two steps you need to follow to invoke that web service.

Step 1: Generate the client side source from a WSDL2Java tool

Step 2: Invoke the operation using:

YourService service = new YourServiceLocator();
Stub stub = service.getYourStub();

If you look further, you will notice that the Stub class is used to invoke the service deployed at the remote location as a web service. When invoking that, your client actually generates the SOAP request and communicates. Similarly the web service sends the response as a SOAP. With the help of a tool like Wireshark, you can view the SOAP messages exchanged.

However since you have requested more explanation on the basics, I recommend you to refer here and write a web service with it's client to learn it further.

Send data from a textbox into Flask?

Unless you want to do something more complicated, feeding data from a HTML form into Flask is pretty easy.

  • Create a view that accepts a POST request (my_form_post).
  • Access the form elements in the dictionary request.form.


<form method="POST">
    <input name="text">
    <input type="submit">
from flask import Flask, request, render_template

app = Flask(__name__)

def my_form():
    return render_template('my-form.html')

@app.route('/', methods=['POST'])
def my_form_post():
    text = request.form['text']
    processed_text = text.upper()
    return processed_text

This is the Flask documentation about accessing request data.

If you need more complicated forms that need validation then you can take a look at WTForms and how to integrate them with Flask.

Note: unless you have any other restrictions, you don't really need JavaScript at all to send your data (although you can use it).

Count number of rows within each group

The simple option to use with aggregate is the length function which will give you the length of the vector in the subset. Sometimes a little more robust is to use function(x) sum( ! ).

Update row with data from another row in the same table

Here's my go:

UPDATE test as t1 
    INNER JOIN test as t2 ON 
        t1.NAME = t2.NAME AND 
        t2.value IS NOT NULL 

EDIT: Removed superfluous != condition.

How to create Gmail filter searching for text only at start of subject line?

The only option I have found to do this is find some exact wording and put that under the "Has the words" option. Its not the best option, but it works.

Hide Twitter Bootstrap nav collapse on click

Update your

  <a href="#about">About</a>


  <a data-toggle="collapse" data-target=".nav-collapse" href="#about">About</a>

This simple change worked for me.


Java 8 stream's .min() and .max(): why does this compile?

Let me explain what is happening here, because it isn't obvious!

First, Stream.max() accepts an instance of Comparator so that items in the stream can be compared against each other to find the minimum or maximum, in some optimal order that you don't need to worry too much about.

So the question is, of course, why is Integer::max accepted? After all it's not a comparator!

The answer is in the way that the new lambda functionality works in Java 8. It relies on a concept which is informally known as "single abstract method" interfaces, or "SAM" interfaces. The idea is that any interface with one abstract method can be automatically implemented by any lambda - or method reference - whose method signature is a match for the one method on the interface. So examining the Comparator interface (simple version):

public Comparator<T> {
    T compare(T o1, T o2);

If a method is looking for a Comparator<Integer>, then it's essentially looking for this signature:

int xxx(Integer o1, Integer o2);

I use "xxx" because the method name is not used for matching purposes.

Therefore, both Integer.min(int a, int b) and Integer.max(int a, int b) are close enough that autoboxing will allow this to appear as a Comparator<Integer> in a method context.

How to create table using select query in SQL Server?

select <column list> into <table name> from <source> where <whereclause>

Disabling Log4J Output in Java

Set level to OFF (instead of DEBUG, INFO, ....)

MVC Razor @foreach

I'm using @foreach when I send an entity that contains a list of entities ( for example to display 2 grids in 1 view )

For example if I'm sending as model the entity Foo that contains Foo1(List<Foo1>) and Foo2(List<Foo2>)

I can refer to the first List with:

@foreach (var item in Model.Foo.Foo1)
    @Html.DisplayFor(modelItem=> item.fooName)

Java Error opening registry key

In case a virus scanner (like McAfee) is running, try:

  1. Disable virus scanner
  2. Uninstall Java (via Control Panel / Programs and Features)
  3. Reinstall Java (from
  4. Re-enable virus scanner

Where is Python's sys.path initialized from?

"Initialized from the environment variable PYTHONPATH, plus an installation-dependent default"


Get current index from foreach loop

IEnumerable list = DataGridDetail.ItemsSource as IEnumerable;
List<string> lstFile = new List<string>();

int i = 0;
foreach (var row in list)
bool IsChecked = (bool)((CheckBox)DataGridDetail.Columns[0].GetCellContent(row)).IsChecked;
if (IsChecked)
--Here i want to get the index or current row from the list                   


if, elif, else statement issues in Bash

Missing space between elif and [ rest your program is correct. you need to correct it an check it out. here is fixed program:


if [ "$seconds" -eq 0 ]; then
elif [ "$seconds" -gt 0 ]; then
   timezone_string=$(printf "%02d:%02d" $((seconds/3600)) $(((seconds / 60) % 60)))
   echo "Unknown parameter"

useful link related to this bash if else statement

Visual Studio 2010 always thinks project is out of date, but nothing has changed

I spent many hours spent tearing out my hair over this. The build output wasn't consistent; different projects would be "not up to date" for different reasons from one build to the next consecutive build. I eventually found that the culprit was DropBox (3.0.4). I junction my source folder from ...\DropBox into my projects folder (not sure if this is the reason), but DropBox somehow "touches" files during a build. Paused syncing and everything is consistently up-to-date.

Angular2 Error: There is no directive with "exportAs" set to "ngForm"

I faced the same issue. I had missed the forms module import tag in the app.module.ts

import { FormsModule } from '@angular/forms';

    imports: [BrowserModule,

React Native Error: ENOSPC: System limit for number of file watchers reached

Please refer this link[1]. Visual Studio code has mentioned a brief explanation for this error message. I also encountered the same error. Adding the below parameter in the relavant file will fix this issue.



Want custom title / image / description in facebook share link from a flash app

I have a Joomla Module that displays stuff... and I want to be able to share that stuff on facebook and not the Page's Title Meta Description... so my workaround is to have a secret .php file on the server that gets executed when it detects the FB's


if($_SERVER['HTTP_USER_AGENT'] != 'facebookexternalhit/1.1 (+') {
    echo 'Direct Access';
} else {
    echo 'FB Accessed';

and pass variables with the URL that formats that particular page with the title and meta desciption of the item I want to share from my joomla module...

a name="fb_share" share_url="MYURL/sharer.php?title=TITLE&desc=DESC"

hope this helps...

Java serialization - local class incompatible

This worked for me:

If you wrote your Serialized class object into a file, then made some changes to file and compiled it, and then you try to read an object, then this will happen.

So, write the necessary objects to file again if a class is modified and recompiled.

PS: This is NOT a solution; was meant to be a workaround.

SQL Switch/Case in 'where' clause

declare @locationType varchar(50);
declare @locationID int;

SELECT column1, column2
FROM viewWhatever
@locationID = 
  CASE @locationType
      WHEN 'location' THEN account_location
      WHEN 'area' THEN xxx_location_area 
      WHEN 'division' THEN xxx_location_division 

How do I force git pull to overwrite everything on every pull?

Really the ideal way to do this is to not use pull at all, but instead fetch and reset:

git fetch origin master
git reset --hard FETCH_HEAD
git clean -df

(Altering master to whatever branch you want to be following.)

pull is designed around merging changes together in some way, whereas reset is designed around simply making your local copy match a specific commit.

You may want to consider slightly different options to clean depending on your system's needs.

Getting current date and time in JavaScript

You need to use getDate() to get the date part. The getDay() function returns the day number (Sunday = 0, Monday = 1...), and the getMonth() returns a 0 based index, so you need to increment it by 1.

 var currentdate = new Date(); 

 var datetime = "Last Sync: " + currentdate.getDate() + "/"+  (parseInt(currentdate.getMonth())    + 1)
   + "/" + currentdate.getFullYear() + " @ "  
   + currentdate.getHours() + ":"  
   + currentdate.getMinutes() + ":" + currentdate.getSeconds(); 

Git: How to rebase to a specific commit?

A simpler solution is git rebase <SHA1 of B> topic. This works irrespective of where your HEAD is.

We can confirm this behaviour from git rebase doc

<upstream> Upstream branch to compare against. May be any valid commit, not just an existing branch name. Defaults to the configured upstream for the current branch.

You might be thinking what will happen if I mention SHA1 of topic too in the above command ?

git rebase <SHA1 of B> <SHA1 of topic>

This will also work but rebase then won't make Topic point to new branch so created and HEAD will be in detached state. So from here you have to manually delete old Topic and create a new branch reference on new branch created by rebase.

Cannot find module cv2 when using OpenCV

I solved my issue using the following command :

pip install opencv-python

Forward X11 failed: Network error: Connection refused

The D-Bus error can be fixed with dbus-launch :

dbus-launch command

How to run a C# console application with the console hidden

You can use the FreeConsole API to detach the console from the process :

static extern bool FreeConsole();

(of course this is applicable only if you have access to the console application's source code)

Disabling radio buttons with jQuery

First, the valid syntax is


second, have you tried:



third, why not assign a class to all the radio buttons, and select them by class?

Error 1053 the service did not respond to the start or control request in a timely fashion

I was getting exactly same issue, All I have done is to to change the Debug mode to Release while compiling the dll. This has solved my probelm, how/why? I dont know I have already asked a question on SO

C# Creating and using Functions

Note: in C# the term "function" is often replaced by the term "method". For the sake of this question there is no difference, so I'll just use the term "function".

The other answers have already given you a quick way to fix your problem (just make Add a static function), but I'd like to explain why.

C# has a fundamentally different design paradigm than C. That paradigm is called object-oriented programming (OOP). Explaining all the differences between OOP and functional programming is beyond the scope of this question, but here's the short version as it applies to you.

Writing your program in C, you would have created a function that adds two numbers, and that function would exist independently and be callable from anywhere. In C# most functions don't exist independently; instead, they exist in the context of an object. In your example code, only an instance (an object) of the class Program knows how to perform Add. Said another way, you have to create an instance of Program, and then ask Program to perform an Add for you.

The solutions that people gave you, using the static keyword, route around that design. Using the static keyword is kind of like saying, "Hey, this function I'm defining doesn't need any context/state, it can just be called." Since your Add function is very simple, this makes sense. As you start diving deeper into OOP, you're going to find that your functions get more complicated and rely on knowing their state/context.

My advice: Pick up an OOP book and get ready to switch your brain from functional programming to OOP programming. You're in for a ride.

AngularJS - Does $destroy remove event listeners?

Event listeners

First off it's important to understand that there are two kinds of "event listeners":

  1. Scope event listeners registered via $on:

    $scope.$on('anEvent', function (event, data) {
  2. Event handlers attached to elements via for example on or bind:

    element.on('click', function (event) {


When $scope.$destroy() is executed it will remove all listeners registered via $on on that $scope.

It will not remove DOM elements or any attached event handlers of the second kind.

This means that calling $scope.$destroy() manually from example within a directive's link function will not remove a handler attached via for example element.on, nor the DOM element itself.


Note that remove is a jqLite method (or a jQuery method if jQuery is loaded before AngularjS) and is not available on a standard DOM Element Object.

When element.remove() is executed that element and all of its children will be removed from the DOM together will all event handlers attached via for example element.on.

It will not destroy the $scope associated with the element.

To make it more confusing there is also a jQuery event called $destroy. Sometimes when working with third-party jQuery libraries that remove elements, or if you remove them manually, you might need to perform clean up when that happens:

element.on('$destroy', function () {

What to do when a directive is "destroyed"

This depends on how the directive is "destroyed".

A normal case is that a directive is destroyed because ng-view changes the current view. When this happens the ng-view directive will destroy the associated $scope, sever all the references to its parent scope and call remove() on the element.

This means that if that view contains a directive with this in its link function when it's destroyed by ng-view:

scope.$on('anEvent', function () {

element.on('click', function () {

Both event listeners will be removed automatically.

However, it's important to note that the code inside these listeners can still cause memory leaks, for example if you have achieved the common JS memory leak pattern circular references.

Even in this normal case of a directive getting destroyed due to a view changing there are things you might need to manually clean up.

For example if you have registered a listener on $rootScope:

var unregisterFn = $rootScope.$on('anEvent', function () {});

scope.$on('$destroy', unregisterFn);

This is needed since $rootScope is never destroyed during the lifetime of the application.

The same goes if you are using another pub/sub implementation that doesn't automatically perform the necessary cleanup when the $scope is destroyed, or if your directive passes callbacks to services.

Another situation would be to cancel $interval/$timeout:

var promise = $interval(function () {}, 1000);

scope.$on('$destroy', function () {

If your directive attaches event handlers to elements for example outside the current view, you need to manually clean those up as well:

var windowClick = function () {

angular.element(window).on('click', windowClick);

scope.$on('$destroy', function () {
  angular.element(window).off('click', windowClick);

These were some examples of what to do when directives are "destroyed" by Angular, for example by ng-view or ng-if.

If you have custom directives that manage the lifecycle of DOM elements etc. it will of course get more complex.

C++: Rounding up to the nearest multiple of a number

Round to nearest multiple that happens to be a power of 2

unsigned int round(unsigned int value, unsigned int multiple){
    return ((value-1u) & ~(multiple-1u)) + multiple;

This can be useful for when allocating along cachelines, where the rounding increment you want is a power of two, but the resulting value only needs to be a multiple of it. On gcc the body of this function generates 8 assembly instructions with no division or branches.

round(  0,  16) ->   0
round(  1,  16) ->  16
round( 16,  16) ->  16
round(257, 128) -> 384 (128 * 3)
round(333,   2) -> 334

Sun JSTL taglib declaration fails with "Can not find the tag library descriptor"

Just check our own JSTL wiki page for the proper download links and crystal clear installation instructions.

Put your mouse above the [jstl] tag which you put on the question yourself until a black box shows up and click therein the info link.

enter image description here

Then scroll a bit down to JSTL versions information until you find download link to JSTL 1.2 (or 1.2.1).

enter image description here

Finally just drop exactly that file in webapp's /WEB-INF/lib.

enter image description here

This way the taglib declaration must not give any errors anymore and the JSTL tags and functions should just work.

Return first N key:value pairs from dict

Dictionary maintains no order , so before picking top N key value pairs lets make it sorted.

import operator
d = {'a': 3, 'b': 2, 'c': 3, 'd': 4}
#itemgetter(0)=sort by keys, itemgetter(1)=sort by values

Now we can do the retrieval of top 'N' elements:, using the method structure like this:

def return_top(elements,dictionary_element):
    '''Takes the dictionary and the 'N' elements needed in return
    for h,i in enumerate(dictionary_element):
        if h<elements:
    return topers

to get the top 2 elements then simply use this structure:

d = {'a': 3, 'b': 2, 'c': 3, 'd': 4}

Warning: date_format() expects parameter 1 to be DateTime

This may help

$formattedweddingdate =date('d-m-Y',strtotime($weddingdate));

Adding one day to a date

Since you already have an answer to what's wrong with your code, I can bring another perspective on how you can play with datetimes generally, and solve your problem specifically.

Oftentimes you find yourself posing a problem in terms of solution. This is just one of the reasons you end up with an imperative code. It's great if it works though; there are just other, arguably more maintainable alternatives. One of them is a declarative code. The point is asking what you need, instead of how to get there.

In your particular case, this can look like the following. First, you need to find out what is it that you're looking for, that is, discover abstractions. In your case, it looks like you need a date. Not just any date, but the one having some standard representation. Say, ISO8601 date. There are at least two implementations: the first one is a date parsed from an ISO8601-formatted string (or a string in any other format actually), and the second is some future date which is a day later. Thus, the whole code could look like that:

(new Future(
    new DateTimeParsedFromISO8601('2009-09-30 20:24:00'),
    new OneDay()

For more examples with datetime juggling check out this one.

How do I remove a single breakpoint with GDB?

You can delete all breakpoints using

del <start_breakpoint_num> - <end_breakpoint_num>

To view the start_breakpoint_num and end_breakpoint_num use:

info break

Regular expression replace in C#

You can do it this with two replace's

//let stw be "John Smith $100,000.00 M"

sb_trim = Regex.Replace(stw, @"\s+\$|\s+(?=\w+$)", ",");
//sb_trim becomes "John Smith,100,000.00,M"

sb_trim = Regex.Replace(sb_trim, @"(?<=\d),(?=\d)|[.]0+(?=,)", "");
//sb_trim becomes "John Smith,100000,M"


Remove a CLASS for all child elements

This should work:

//Find all `li`s with class `active`, children of `ul`s, children of `table-filters`

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

My C drive stopped being shared with Docker after a recent Windows 10 update. I was getting the same problem saying it was blocked by the Windows firewall when attempting to reshare it.

Looking through the above solutions, I found something that worked for me that is simpler than anything else I saw on this page. In Control Panel\All Control Panel Items\Network and Sharing Center, on the vEthernet (DockerNAT) connection, I unchecked the property File and Printer Sharing for Microsoft Networks and saved the setting. Then I checked the property again to reenable it and saved it again.

At this point, I was able to reshare the C drive in Docker settings. I have no idea why this worked but it was not a firewall problem, which already have an entry for DockerSmbMount.

You have not accepted the license agreements of the following SDK components

You can install and accept the license of the SDK & tools via 2 ways:

1. Open the Android SDK Manager GUI via command line

Open the Android SDK manager via the command line using:

# Android SDK Tools 25.2.3 and lower - Open the Android SDK GUI via the command line
cd ~/Library/Android/sdk/tools && ./android

# 'Android SDK Tools' 25.2.3 and higher - `sdkmanager` is located in android_sdk/tools/bin/.
cd ~/Library/Android/sdk/tools/bin && ./sdkmanager

View more details on the new sdkmanager.

Select and install the required tools. (your location may be different)

2. Install and accept android license via command line:

Update the packages via command line, you'll be presented with the terms and conditions which you'll need to accept.

- Install or update to the latest version

This will install the latest platform-tools at the time you run it.

# Android SDK Tools 25.2.3 and lower. Install the latest `platform-tools` for android-25
android update sdk --no-ui --all --filter platform-tools,android-25,extra-android-m2repository

# Android SDK Tools 25.2.3 and higher
sdkmanager --update

- Install a specific version (25.0.1, 24.0.1, 23.0.1)

You can also install a specific version like so:

# Build Tools 23.0.1, 24.0.1, 25.0.1
android update sdk --no-ui --all --filter build-tools-25.0.1,android-25,extra-android-m2repository
android update sdk --no-ui --all --filter build-tools-24.0.1,android-24,extra-android-m2repository
android update sdk --no-ui --all --filter build-tools-23.0.1,android-23,extra-android-m2repository
# Alter the versions as required                      ?               ?

# -u --no-ui  : Updates from command-line (does not display the GUI)
# -a --all    : Includes all packages (such as obsolete and non-dependent ones.)
# -t --filter : A filter that limits the update to the specified types of
#               packages in the form of a comma-separated list of
#               [platform, system-image, tool, platform-tool, doc, sample,
#               source]. This also accepts the identifiers returned by
#               'list sdk --extended'.

# List version and description of other available SDKs and tools
android list sdk --extended
sdkmanager --list

How to find the length of a string in R


you may need to convert to a character vector first;


python NameError: global name '__file__' is not defined

change your codes as follows! it works for me. `


Python concatenate text files

This should do it

For large files:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            for line in infile:

For small files:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:

… and another interesting one that I thought of:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for line in itertools.chain.from_iterable(itertools.imap(open, filnames)):

Sadly, this last method leaves a few open file descriptors, which the GC should take care of anyway. I just thought it was interesting

StringIO in Python3

You can use the StringIO from the six module:

import six
import numpy

x = "1 3\n 4.5 8"

git: fatal: I don't handle protocol '??http'

Mostly it is due to some invisible unicode characters which can come if you hit "Ctrl+V" or "Ctrl+Shift+V" in the terminal. Don't copy and paste the whole command. Instead , type git clone and then copy and paste the url using Right Click + Paste.

What is the difference between a function expression vs declaration in JavaScript?

Though the complete difference is more complicated, the only difference that concerns me is when the machine creates the function object. Which in the case of declarations is before any statement is executed but after a statement body is invoked (be that the global code body or a sub-function's), and in the case of expressions is when the statement it is in gets executed. Other than that for all intents and purposes browsers treat them the same.

To help you understand, take a look at this performance test which busted an assumption I had made of internally declared functions not needing to be re-created by the machine when the outer function is invoked. Kind of a shame too as I liked writing code that way.

How can I unstage my files again after making a local commit?

Lets say you want to unstage changes upto n commits,

Where commit hashes are as follows:

  • h1
  • h2 ...
  • hn
  • hn+1

Then run the following command:
git reset hn

Now the HEAD will be at hn+1. Changes from h1 to hn will be unstaged.

How to use external ".js" files

In your head element add

<script type="text/javascript" src="myscript.js"></script>

Load CSV data into MySQL in Python

The above answer seems good. But another way of doing this is adding the auto commit option along with the db connect. This automatically commits every other operations performed in the db, avoiding the use of mentioning sql.commit() every time.

 mydb = MySQLdb.connect(host='localhost',

SQL Server: Maximum character length of object names

128 characters. This is the max length of the sysname datatype (nvarchar(128)).

How can moment.js be imported with typescript?

1. install moment

npm install moment --save

2. test this code in your typescript file

import moment = require('moment');


Fill an array with random numbers

If the randomness is controlled like this there can always generate any number of data points of a given range. If the random method in java is only used, we cannot guarantee that all the numbers will be unique.

package edu.iu.common;_x000D_
import java.util.ArrayList;_x000D_
import java.util.Random;_x000D_
public class RandomCentroidLocator {_x000D_
public static void main(String [] args){_x000D_
 int min =0;_x000D_
 int max = 10;_x000D_
 int numCentroids = 10;_x000D_
 ArrayList<Integer> values = randomCentroids(min, max, numCentroids); _x000D_
 for(Integer i : values){_x000D_
  System.out.print(i+" ");_x000D_
private static boolean unique(ArrayList<Integer> arr, int num, int numCentroids) {_x000D_
 boolean status = true;_x000D_
 int count=0;_x000D_
 for(Integer i : arr){_x000D_
  status = true;_x000D_
 }else if(count>1){_x000D_
  status =false;_x000D_
 return status;_x000D_
// generate random centroid Ids -> these Ids can be used to retrieve data_x000D_
// from the data Points generated_x000D_
// simply we are picking up random items from the data points_x000D_
// in this case all the random numbers are unique_x000D_
// it provides the necessary number of unique and random centroids_x000D_
private static ArrayList<Integer> randomCentroids(int min, int max, int numCentroids) {_x000D_
 Random random = new Random();_x000D_
 ArrayList<Integer> values = new ArrayList<Integer>();_x000D_
 int num = -1;_x000D_
 int count = 0;_x000D_
 do {_x000D_
  num = random.nextInt(max - min + 1) + min;_x000D_
  int index =values.size()-1;_x000D_
  if(unique(values, num, numCentroids)){    _x000D_
 } while (!( count == numCentroids));_x000D_
 return values;_x000D_

On postback, how can I check which control cause postback in Page_Init event

If you need to check which control caused the postback, then you could just directly compare ["__EVENTTARGET"] to the control you are interested in:

if (specialControl.UniqueID == Page.Request.Params["__EVENTTARGET"])
    /*do special stuff*/

This assumes you're just going to be comparing the result from any GetPostBackControl(...) extension method anyway. It may not handle EVERY situation, but if it works it is simpler. Plus, you won't scour the page looking for a control you didn't care about to begin with.

Method Call Chaining; returning a pointer vs a reference?

It's canonical to use references for this; precedence: ostream::operator<<. Pointers and references here are, for all ordinary purposes, the same speed/size/safety.

Base64 PNG data to HTML5 canvas

By the looks of it you need to actually pass drawImage an image object like so

var canvas = document.getElementById("c");_x000D_
var ctx = canvas.getContext("2d");_x000D_
var image = new Image();_x000D_
image.onload = function() {_x000D_
  ctx.drawImage(image, 0, 0);_x000D_
<canvas id="c"></canvas>

I've tried it in chrome and it works fine.

ValueError: not enough values to unpack (expected 11, got 1)

For the line


What are you splitting on? Looks like a CSV, so try



"one,two,three".split()  # returns one element ["one,two,three"]
"one,two,three".split(',')  # returns three elements ["one", "two", "three"]

As @TigerhawkT3 mentions, it would be better to use the CSV module. Incredibly quick and easy method available here.

How to search if dictionary value contains certain string with Python

import re
for i in range(len(myDict.values())):
    for j in range(len(myDict.values()[i])):'Mary', myDict.values()[i][j])
         if match:
                 print #Mary
                 print myDict.keys()[i] #firstName
                 print myDict.values()[i][j] #Mary-Ann

I got error "The DELETE statement conflicted with the REFERENCE constraint"

The error means that you have data in other tables that references the data you are trying to delete.

You would need to either drop and recreate the constraints or delete the data that the Foreign Key references.

Suppose you have the following tables



Suppose a Foreign Key constraint exists between the StudentTypeId column in StudentTypes and the StudentTypeId column in Students

If you try to delete all the data in StudentTypes an error will occur as the StudentTypeId column in Students reference the data in the StudentTypes table.


DELETE and TRUNCATE essentially do the same thing. The only difference is that TRUNCATE does not save the changes in to the Log file. Also you can't use a WHERE clause with TRUNCATE

AS to why you can run this in SSMS but not via your Application. I really can't see this happening. The FK constraint would still throw an error regardless of where the transaction originated from.

Web.Config Debug/Release

To make the transform work in development (using F5 or CTRL + F5) I drop ctt.exe ( in the packages folder (packages\ConfigTransform\ctt.exe).

Then I register a pre- or post-build event in Visual Studio...

$(SolutionDir)packages\ConfigTransform\ctt.exe source:"$(ProjectDir)connectionStrings.config" transform:"$(ProjectDir)connectionStrings.$(ConfigurationName).config" destination:"$(ProjectDir)connectionStrings.config"
$(SolutionDir)packages\ConfigTransform\ctt.exe source:"$(ProjectDir)web.config" transform:"$(ProjectDir)web.$(ConfigurationName).config" destination:"$(ProjectDir)web.config"

For the transforms I use SlowCheeta VS extension (

How to export data to CSV in PowerShell?

You can always use the

echo "Column1`tColumn2`tColumn3..." >> results.csv

You will need to put "`t" between the columns to separates the variables into their own column. Here is the way I wrote my script:

echo "Host`tState" >> results.csv
$names = Get-Content "hostlist.txt"
foreach ($name in $names) {
    $count = 0
    $count2 = 13490

    if ( Test-Connection -ComputerName $name -Count 1 -ErrorAction SilentlyContinue ) {
        echo "$name`tUp" >> results.csv
    else {
        echo "$name`tDown" >> results.csv

    Write-Progress -Activity "Gathering Information" -status "Pinging Hosts..." -percentComplete ($count / $count2 *100)


This is the easiest way to me. The output I get is :

H1  |Up
H2  |UP
H3  |Down

You can play around with the look, but that's the basic idea. The $count is just a progress bar if you want to spice up the look

What do the terms "CPU bound" and "I/O bound" mean?

See what Microsoft says.

The core of async programming is the Task and Task objects, which model asynchronous operations. They are supported by the async and await keywords. The model is fairly simple in most cases:

  • For I/O-bound code, you await an operation which returns a Task or Task inside of an async method.

  • For CPU-bound code, you await an operation which is started on a background thread with the Task.Run method.

The await keyword is where the magic happens. It yields control to the caller of the method that performed await, and it ultimately allows a UI to be responsive or a service to be elastic.

I/O-Bound Example: Downloading data from a web service

private readonly HttpClient _httpClient = new HttpClient();

downloadButton.Clicked += async (o, e) =>
    // This line will yield control to the UI as the request
    // from the web service is happening.
    // The UI thread is now free to perform other work.
    var stringData = await _httpClient.GetStringAsync(URL);

CPU-bound Example: Performing a Calculation for a Game

private DamageResult CalculateDamageDone()
    // Code omitted:
    // Does an expensive calculation and returns
    // the result of that calculation.

calculateButton.Clicked += async (o, e) =>
    // This line will yield control to the UI while CalculateDamageDone()
    // performs its work.  The UI thread is free to perform other work.
    var damageResult = await Task.Run(() => CalculateDamageDone());

Examples above showed how you can use async and await for I/O-bound and CPU-bound work. It's key that you can identify when a job you need to do is I/O-bound or CPU-bound, because it can greatly affect the performance of your code and could potentially lead to misusing certain constructs.

Here are two questions you should ask before you write any code:

Will your code be "waiting" for something, such as data from a database?

  • If your answer is "yes", then your work is I/O-bound.

Will your code be performing a very expensive computation?

  • If you answered "yes", then your work is CPU-bound.

If the work you have is I/O-bound, use async and await without Task.Run. You should not use the Task Parallel Library. The reason for this is outlined in the Async in Depth article.

If the work you have is CPU-bound and you care about responsiveness, use async and await but spawn the work off on another thread with Task.Run. If the work is appropriate for concurrency and parallelism, you should also consider using the Task Parallel Library.

Couldn't process file resx due to its being in the Internet or Restricted zone or having the mark of the web on the file

I stumbled upon another possible reason of this error. If you use NTFS symbolic links in your project tree, and probably subst'ed drives, you may get this error even if they point to your local drive. If this is the case, try to avoid the situation when .resx files are reached via symlinks.

Extract Data from PDF and Add to Worksheet

Since I do not prefer to rely on external libraries and/or other programs, I have extended your solution so that it works. The actual change here is using the GetFromClipboard function instead of Paste which is mainly used to paste a range of cells. Of course, the downside is that the user must not change focus or intervene during the whole process.

Dim pathPDF As String, textPDF As String
Dim openPDF As Object
Dim objPDF As MsForms.DataObject

pathPDF = "C:\some\path\data.pdf"
Set openPDF = CreateObject("Shell.Application")
openPDF.Open (pathPDF)
Application.Wait Now + TimeValue("00:00:2")
SendKeys "^a"
Application.Wait Now + TimeValue("00:00:2")
SendKeys "^c"
Application.Wait Now + TimeValue("00:00:1")

AppActivate ActiveWorkbook.Windows(1).Caption
textPDF = objPDF.GetText(1)
MsgBox textPDF

If you're interested see my project in github.

Laravel Eloquent: How to get only certain columns from joined tables

In Laravel 4 you can hide certain fields from being returned by adding the following in your model.

protected $hidden = array('password','secret_field');

How to get a specific output iterating a hash in Ruby?

My one line solution:

hash.each { |key, array| puts "#{key}-----", array }

I think it is pretty easy to read.

The SELECT permission was denied on the object 'sysobjects', database 'mssqlsystemresource', schema 'sys'

This was a problem with the user having deny privileges as well; in my haste to grant permissions I basically gave the user everything. And deny was killing it. So as soon as I removed those permissions it worked.

a href link for entire div in HTML/CSS

What I would do is put a span inside the <a> tag, set the span to block, and add size to the span, or just apply the styling to the <a> tag. Definitely handle the positioning in the <a> tag style. Add an onclick event to the a where JavaScript will catch the event, then return false at the end of the JavaScript event to prevent default action of the href and bubbling of the click. This works in cases with or without JavaScript enabled, and any AJAX can be handled in the Javascript listener.

If you're using jQuery, you can use this as your listener and omit the onclick in the a tag.

$('#idofdiv').live("click", function(e) {
    //add stuff here
    e.preventDefault; //or use return false

this allows you to attach listeners to any changed elements as necessary.

How to put a UserControl into Visual Studio toolBox

I found that the user control must have a parameterless constructor or it won't show up in the list. at least that was true in vs2005.

Make index.html default, but allow index.php to be visited if typed in

I agree with @TheAlpha's accepted answer, Apache reads the DirectoryIndex target files from left to right , if the first file exists ,apche serves it and if it doesnt then the next file is served as an index for the directory. So if you have the following Directive :

DirectoryIndex file1.html file2.html

Apache will serve /file.html as index ,You will need to change the order of files if you want to set /file2.html as index

DirectoryIndex file2.html file1.html

You can also set index file using a RewriteRule

RewriteEngine on

RewriteRule ^$ /index.html [L]

RewriteRule above will rewrite your homepage to /index.html the rewriting happens internally so would show you the contents ofindex.html .

Imply bit with constant 1 or 0 in SQL Server

The expression to use inside SELECT could be


UPDATE and REPLACE part of a string

You don't need wildcards in the REPLACE - it just finds the string you enter for the second argument, so the following should work:

SET Value = REPLACE(Value, '123', '')

If the column to replace is type text or ntext you need to cast it to nvarchar

SET Value = REPLACE(CAST(Value as nVarchar(4000)), '123', '')

null terminating a string

'\0' is the way to go. It's a character, which is what's wanted in a string and has the null value.

When we say null terminated string in C/C++, it really means 'zero terminated string'. The NULL macro isn't intended for use in terminating strings.

Link to reload current page

<a href=".">refresh current page</a>

or if you want to pass parameters:

<a href=".?curreny='usd'">refresh current page</a>

Converting A String To Hexadecimal In Java

To go the other way (hex to string), you can use

public String hexToString(String hex) {
    return new String(new BigInteger(hex, 16).toByteArray());

How to call a web service from jQuery


The OP was not looking to use cross-domain requests, but jQuery supports JSONP as of v1.5. See jQuery.ajax(), specificically the crossDomain parameter.

The regular jQuery Ajax requests will not work cross-site, so if you want to query a remote RESTful web service, you'll probably have to make a proxy on your server and query that with a jQuery get request. See this site for an example.

If it's a SOAP web service, you may want to try the jqSOAPClient plugin.

Angular JS: Full example of GET/POST/DELETE/PUT client for a REST/CRUD backend?

Because your update uses PUT method, {entryId: $scope.entryId} is considered as data, to tell angular generate from the PUT data, you need to add params: {entryId: '@entryId'} when you define your update, which means

return $resource('http://localhost\\:3000/realmen/:entryId', {}, {
  query: {method:'GET', params:{entryId:''}, isArray:true},
  post: {method:'POST'},
  update: {method:'PUT', params: {entryId: '@entryId'}},
  remove: {method:'DELETE'}

Fix: Was missing a closing curly brace on the update line.

ie8 var w= - "Message: Invalid argument."

If you want use the name of new window etc posting a form to this window, then the solution, that working in IE, FF, Chrome:

  var ret ="", "_blank"); = "NewFormName";

  var myForm = document.createElement("form");
  myForm.action = "xyz.php"; = "NewFormName";


Python how to exit main function

use sys module

import sys

Typescript sleep

With RxJS:

import { timer } from 'rxjs';

// ...

timer(your_delay_in_ms).subscribe(x => { your_action_code_here })

x is 0.

If you give a second argument period to timer, a new number will be emitted each period milliseconds (x = 0 then x = 1, x = 2, ...).

See the official doc for more details.

How to export JSON from MongoDB using Robomongo

Expanding on Anish's answer, I wanted something I can apply to any query to automatically output all fields vs. having to define them within the print statement. It can probably be simplified but this was something quick & dirty that works great:

var cursor = db.getCollection('foo').find({}, {bar: 1, baz: 1, created_at: 1, updated_at: 1}).sort({created_at: -1, updated_at: -1});

while (cursor.hasNext()) {
    var record =;
    var output = "";
    for (var i in record) {
      output += record[i] + ",";
    output = output.substring(0, output.length - 1);

Set an environment variable in git bash

Creating a .bashrc file in your home directory also works. That way you don't have to copy your .bash_profile every time you install a new version of git bash.

Empty or Null value display in SSRS text boxes

=IIF(ISNOTHING(CStr(Fields!MyFields.Value)) or CStr(Fields!MyFields.Value) = "","-",CStr(Fields!MyFields.Value))

Use this expression you may get the answer.

Here CStr is an default function for handling String datatypes.

Check if instance is of a type

Try the following

if (c is TForm) { 

Angular2 : Can't bind to 'formGroup' since it isn't a known property of 'form'

I had the same problem and I solved the problem in another way, without import ReactiveFormsModule. You may be but this block in


    userForm = new FormGroup({
        name: new FormControl(),
        email: new FormControl(),
        adresse: new FormGroup({
            rue: new FormControl(),
            ville: new FormControl(),
            cp: new FormControl(),

What is the best way to find the users home directory in Java?

Others have answered the question before me but a useful program to print out all available properties is:

for (Map.Entry<?,?> e : System.getProperties().entrySet()) {
    System.out.println(String.format("%s = %s", e.getKey(), e.getValue())); 

How to take last four characters from a varchar?

Right should do:

select RIGHT('abcdeffff',4)

Ruby: kind_of? vs. instance_of? vs. is_a?

What is the difference?

From the documentation:

- (Boolean) instance_of?(class)
Returns true if obj is an instance of the given class.


- (Boolean) is_a?(class)
- (Boolean) kind_of?(class)
Returns true if class is the class of obj, or if class is one of the superclasses of obj or modules included in obj.

If that is unclear, it would be nice to know what exactly is unclear, so that the documentation can be improved.

When should I use which?

Never. Use polymorphism instead.

Why are there so many of them?

I wouldn't call two "many". There are two of them, because they do two different things.

PHP strtotime +1 month adding an extra month

This should be

$endOfCycle=date('Y-m-d', strtotime("+30 days"));


expects to be given a string containing a US English date format and will try to parse that format into a Unix timestamp (the number of seconds since January 1 1970 00:00:00 UTC), relative to the timestamp given in now, or the current time if now is not supplied.



Returns a string formatted according to the given format string using the given integer timestamp or the current time if no timestamp is given.

See the manual pages for:

How can I print the contents of a hash in Perl?

My favorite: Smart::Comments

use Smart::Comments;
# ...

### %hash

That's it.

How do I programmatically click on an element in JavaScript?

Here's a cross browser working function (usable for other than click handlers too):

function eventFire(el, etype){
    if (el.fireEvent) {
      el.fireEvent('on' + etype);
    } else {
      var evObj = document.createEvent('Events');
      evObj.initEvent(etype, true, false);

How to install CocoaPods?

Pod Installation giving error on OS X El Capitan 10.11.2

ERROR: Error installing cocoapods: activesupport requires Ruby version >= 2.2.2.

enter image description here

After getting this error tried this command and install again its work for me.

sudo gem install activesupport -v 4.2.6

Now try same pod installation command

sudo gem install -n /usr/local/bin cocoapods

Hope it'll help to all of us.

How to add a 'or' condition in #ifdef

I am really OCD about maintaining strict column limits, and not a fan of "\" line continuation because you can't put a comment after it, so here is my method.

#ifdef  CONDITION_01             //|       |//
#define             TEMP_MACRO   //|       |//
#endif                           //|       |//
#ifdef  CONDITION_02             //|       |//
#define             TEMP_MACRO   //|       |//
#endif                           //|       |//
#ifdef  CONDITION_03             //|       |//
#define             TEMP_MACRO   //|       |//
#endif                           //|       |//
#ifdef              TEMP_MACRO   //|       |//
//|-  --  --  --  --  --  --  --  --  --  -|//


//|-  --  --  --  --  --  --  --  --  --  -|//
#endif                           //|       |//
#undef              TEMP_MACRO   //|       |//

jQuery - Click event on <tr> elements with in a table and getting <td> element values

jQuery(document).ready(function() {
       alert("Click! "+ jQuery(this).find('td').html());

Injecting $scope into an angular service function()

Got into the same predicament. I ended up with the following. So here I am not injecting the scope object into the factory, but setting the $scope in the controller itself using the concept of promise returned by $http service.

(function () {
    getDataFactory = function ($http)
        return {
            callWebApi: function (reqData)
                var dataTemp = {
                    Page: 1, Take: 10,
                    PropName: 'Id', SortOrder: 'Asc'

                return $http({
                    method: 'GET',
                    url: '/api/PatientCategoryApi/PatCat',
                    params: dataTemp, // Parameters to pass to external service
                    headers: { 'Content-Type': 'application/Json' }
    patientCategoryController = function ($scope, getDataFactory) {
        var promise = getDataFactory.callWebApi('someDataToPass');
            function successCallback(response) {
                // Set this response data to scope to use it in UI
                $ =;
            }, function errorCallback(response) {
                alert('Some problem while fetching data!!');
    patientCategoryController.$inject = ['$scope', 'getDataFactory'];
    getDataFactory.$inject = ['$http'];
    angular.module('demoApp', []);
    angular.module('demoApp').controller('patientCategoryController', patientCategoryController);
    angular.module('demoApp').factory('getDataFactory', getDataFactory);    

Trigger validation of all fields in Angular Form submit

What worked for me was using the $setSubmitted function, which first shows up in the angular docs in version 1.3.20.

In the click event where I wanted to trigger the validation, I did the following:

vm.triggerSubmit = function() {

That was all it took for me. According to the docs it "Sets the form to its submitted state." It's mentioned here.

HTML button to NOT submit form

return false; at the end of the onclick handler will do the job. However, it's be better to simply add type="button" to the <button> - that way it behaves properly even without any JavaScript.

Delete all rows with timestamp older than x days

DELETE FROM on_search WHERE search_date < NOW() - INTERVAL N DAY

Replace N with your day count

What's the difference between all the Selection Segues?

For those who prefer a bit more practical learning, select the segue in dock, open the attribute inspector and switch between different kinds of segues (dropdown "Kind"). This will reveal options specific for each of them: for example you can see that "present modally" allows you to choose a transition type etc.

How to construct a WebSocket URI relative to the page URI?

If your Web server has support for WebSockets (or a WebSocket handler module) then you can use the same host and port and just change the scheme like you are showing. There are many options for running a Web server and Websocket server/module together.

I would suggest that you look at the individual pieces of the window.location global and join them back together instead of doing blind string substitution.

var loc = window.location, new_uri;
if (loc.protocol === "https:") {
    new_uri = "wss:";
} else {
    new_uri = "ws:";
new_uri += "//" +;
new_uri += loc.pathname + "/to/ws";

Note that some web servers (i.e. Jetty based ones) currently use the path (rather than the upgrade header) to determine whether a specific request should be passed on to the WebSocket handler. So you may be limited in whether you can transform the path in the way you want.

Command failed due to signal: Segmentation fault: 11

I also ran into this problem.... obviously, it is a general error or sorts... when the xcode gets confused.... in my case, I had 3 vars that I was assigning values to from an array.... but I did not specify the type of data in each element of the array.... once I did, it resolved the problem....

Deserialize JSON to Array or List with HTTPClient .ReadAsAsync using .NET 4.0 Task pattern

The return type depends on the server, sometimes the response is indeed a JSON array but sent as text/plain

Setting the accept headers in the request should get the correct type:

client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json")); 

which can then be serialized to a JSON list or array. Thanks for the comment from @svick which made me curious that it should work.

The Exception I got without configuring the accept headers was System.Net.Http.UnsupportedMediaTypeException.

Following code is cleaner and should work (untested, but works in my case):

    var client = new HttpClient();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    var response = await client.GetAsync("");
    var model = await response.Content.ReadAsAsync<List<Job>>();

moment.js get current time in milliseconds?

From the docs:

So use either of these:


to parse a preexisting date and convert the representation to a unix timestamp


for the current unix timestamp

Get Android .apk file VersionName or VersionCode WITHOUT installing apk


var ver: String = packageManager.getPackageInfo(packageName, 0).versionName

What is an AssertionError? In which case should I throw it from my own code?

Of course the "You shall not instantiate an item of this class" statement has been violated, but if this is the logic behind that, then we should all throw AssertionErrors everywhere, and that is obviously not what happens.

The code isn't saying the user shouldn't call the zero-args constructor. The assertion is there to say that as far as the programmer is aware, he/she has made it impossible to call the zero-args constructor (in this case by making it private and not calling it from within Example's code). And so if a call occurs, that assertion has been violated, and so AssertionError is appropriate.

How to retrieve GET parameters from JavaScript

I have created a simple JavaScript function to access GET parameters from URL.

Just include this JavaScript source and you can access get parameters. E.g.: in, the language variable can be accessed as $_GET["language"]. Similarly, a list of all parameters will be stored in a variable $_GET_Params as an array. Both the JavaScript and HTML are provided in the following code snippet:

<!DOCTYPE html>
    <!-- This script is required -->
    function $_GET() {
      // Get the Full href of the page e.g.
      var href = window.location.href;

      // Get the protocol e.g. http
      var protocol = window.location.protocol + "//";

      // Get the host name e.g.
      var hostname = window.location.hostname;

      // Get the pathname e.g. /files/script.php
      var pathname = window.location.pathname;

      // Remove protocol part
      var queries = href.replace(protocol, '');

      // Remove host part
      queries = queries.replace(hostname, '');

      // Remove pathname part
      queries = queries.replace(pathname, '');

      // Presently, what is left in the variable queries is : ?v=1.8.7&country=india

      // Perform query functions if present
      if (queries != "" && queries != "?") {

    // Remove question mark '?'
        queries = queries.slice(1);

        // Split all the different queries
        queries = queries.split("&");

        // Get the number of queries
        var length = queries.length;

        // Declare global variables to store keys and elements
        $_GET_Params = new Array();
        $_GET = {};

        // Perform functions per query
        for (var i  = 0; i < length; i++) {

          // Get the present query
          var key = queries[i];

          // Split the query and the value
          key = key.split("=");

          // Assign value to the $_GET variable
          $_GET[key[0]] = [key[1]];

          // Assign value to the $_GET_Params variable
          $_GET_Params[i] = key[0];

    // Execute the function
    <h1>GET Parameters</h1>
    <h2>Try to insert some get parameter and access it through JavaScript</h2>

How do I add a auto_increment primary key in SQL Server database?

You can also perform this action via SQL Server Management Studio.

Right click on your selected table -> Modify

Right click on the field you want to set as PK --> Set Primary Key

Under Column Properties set "Identity Specification" to Yes, then specify the starting value and increment value.

Then in the future if you want to be able to just script this kind of thing out you can right click on the table you just modified and select


so that you can see for yourself the correct syntax to perform this action.

How to split one text file into multiple *.txt files?

Regardless to what is said above, on my ubuntu 16 i had to do :

> split -b 10M -d  system.log system_split.log 

Please note the space between -b and the value

How do I execute a bash script in Terminal?

Yet another way to execute it (this time without setting execute permissions):

bash /path/to/scriptname

How do you check that a number is NaN in JavaScript?


This is not elegant. but after trying isNAN() I arrived at this solution which is another alternative. In this example I also allowed '.' because I am masking for float. You could also reverse this to make sure no numbers are used.


This is a single character evaluation but you could also loop through a string to check for any numbers.

Line break in SSRS expression

If your placeholder is in html enabled mode then "<br />" will work as a newline

MySQL show status - active or total connections?

In order to check the maximum allowed connections, you can run the following query:

SHOW VARIABLES LIKE "max_connections";

To check the number of active connections, you can run the following query:

SHOW VARIABLES LIKE "max_used_connections";

Hope it helps.

Change image onmouseover

here's a native javascript inline code to change image onmouseover & onmouseout:

<a href="#" id="name">
    <img title="Hello" src="/ico/view.png" onmouseover="this.src='/ico/view.hover.png'" onmouseout="this.src='/ico/view.png'" />

ERROR: Error 1005: Can't create table (errno: 121)

Something I noticed was that I had "other_database" and "Other_Database" in my databases. That caused this problem as I actually had same reference in other database which caused this mysterious error!

Extreme wait-time when taking a SQL Server database offline

In SSMS: right-click on SQL server icon, Activity Monitor. Open Processes. Find the processed connected. Right-click on the process, Kill.

How to check if an excel cell is empty using Apache POI?

Cell cell = row.getCell(x, Row.CREATE_NULL_AS_BLANK);

This trick helped me a lot, see if it's useful for you

What .NET collection provides the fastest search

If it's possible to sort your items then there is a much faster way to do this then doing key lookups into a hashtable or b-tree. Though if you're items aren't sortable you can't really put them into a b-tree anyway.

Anyway, if sortable sort both lists then it's just a matter of walking the lookup list in order.

Walk lookup list
   While items in check list <= lookup list item
     if check list item = lookup list item do something
   Move to next lookup list item

Insert image after each list item

I think your problem is that the :after psuedo-element requires the content: property set inside it. You need to tell it to insert something. You could even just have it insert the image directly:

ul li:after {
    content: url('../images/small_triangle.png');

How can I find out if an .EXE has Command-Line Options?

Unless the writer of the executable has specifically provided a way for you to display a list of all the command line switches that it offers, then there is no way of doing this.

As Marcin suggests, the typical switches for displaying all of the options are either /? or /help (some applications might prefer the Unix-style syntax, -? and -help, respectively). But those are just a common convention.

If those don't work, you're out of luck. You'll need to check the documentation for the application, or perhaps try decompiling the executable (if you know what you're looking for).

Angular + Material - How to refresh a data source (mat-table)

I think the MatTableDataSource object is some way linked with the data array that you pass to MatTableDataSource constructor.

For instance:

dataTable: string[];
tableDS: MatTableDataSource<string>;

   // here your pass dataTable to the dataSource
   this.tableDS = new MatTableDataSource(this.dataTable); 

So, when you have to change data; change on the original list dataTable and then reflect the change on the table by call _updateChangeSubscription() method on tableDS.

For instance:


That's work with me through Angular 6.

History or log of commands executed in Git

I found out that in my version of git bash "" in my "home" folder under windows users, there will be a file called ".bash-history" with no file extension in that folder. It's only created after you exit from bash.

Here's my workflow:

  1. before exiting bash type "history >> history.txt" [ENTER]
  2. exit the bash prompt
  3. hold Win+R to open the Run command box
  4. enter shell:profile
  5. open "history.txt" to confirm that my text was added
  6. On a new line press [F5] to enter a timestamp
  7. save and close the history textfile
  8. Delete the ".bash-history" file so the next session will create a new history

If you really want points I guess you could make a batch file to do all this but this is good enough for me. Hope it helps someone.

How to create new folder?

You probably want os.makedirs as it will create intermediate directories as well, if needed.

import os

#dir is not keyword
def makemydir(whatever):
  except OSError:
  # let exception propagate if we just can't
  # cd into the specified directory

Edit line thickness of CSS 'underline' attribute

Here is one way of achieving this :


<h4>This is a heading</h4>

<h4><u>This is another heading</u></h4>

?CSS :

 u {
    text-decoration: none;
    border-bottom: 10px solid black;

Here is an example:

How to terminate the script in JavaScript?

JavaScript equivalent for PHP's die. BTW it just calls exit() (thanks splattne):

function exit( status ) {
    // +   original by: Brett Zamir (
    // +      input by: Paul
    // +   bugfixed by: Hyam Singer (
    // +   improved by: Philip Peterson
    // +   bugfixed by: Brett Zamir (
    // %        note 1: Should be considered expirimental. Please comment on this function.
    // *     example 1: exit();
    // *     returns 1: null

    var i;

    if (typeof status === 'string') {

    window.addEventListener('error', function (e) {e.preventDefault();e.stopPropagation();}, false);

    var handlers = [
        'copy', 'cut', 'paste',
        'beforeunload', 'blur', 'change', 'click', 'contextmenu', 'dblclick', 'focus', 'keydown', 'keypress', 'keyup', 'mousedown', 'mousemove', 'mouseout', 'mouseover', 'mouseup', 'resize', 'scroll',
        'DOMNodeInserted', 'DOMNodeRemoved', 'DOMNodeRemovedFromDocument', 'DOMNodeInsertedIntoDocument', 'DOMAttrModified', 'DOMCharacterDataModified', 'DOMElementNameChanged', 'DOMAttributeNameChanged', 'DOMActivate', 'DOMFocusIn', 'DOMFocusOut', 'online', 'offline', 'textInput',
        'abort', 'close', 'dragdrop', 'load', 'paint', 'reset', 'select', 'submit', 'unload'

    function stopPropagation (e) {
        // e.preventDefault(); // Stop for the form controls, etc., too?
    for (i=0; i < handlers.length; i++) {
        window.addEventListener(handlers[i], function (e) {stopPropagation(e);}, true);

    if (window.stop) {

    throw '';

MySQL - Replace Character in Columns

maybe I'd go by this.

 SQL = SELECT REPLACE(myColumn, '""', '\'') FROM myTable

I used singlequotes because that's the one that registers string expressions in MySQL, or so I believe.

Hope that helps.

Message "Async callback was not invoked within the 5000 ms timeout specified by jest.setTimeout"

// In jest.setup.js

If on Jest <= 23:

// In jest.config.js
module.exports = {
  setupTestFrameworkScriptFile: './jest.setup.js'

If on Jest > 23:

// In jest.config.js
module.exports = {
  setupFilesAfterEnv: ['./jest.setup.js']

How to convert numbers to alphabet?

If you have a number, for example 65, and if you want to get the corresponding ASCII character, you can use the chr function, like this

>>> chr(65)

similarly if you have 97,

>>> chr(97)

EDIT: The above solution works for 8 bit characters or ASCII characters. If you are dealing with unicode characters, you have to specify unicode value of the starting character of the alphabet to ord and the result has to be converted using unichr instead of chr.

>>> print unichr(ord(u'\u0B85'))

>>> print unichr(1 + ord(u'\u0B85'))

NOTE: The unicode characters used here are of the language called "Tamil", my first language. This is the unicode table for the same

In Django, how do I check if a user is in a certain group?

If a user belongs to a certain group or not, can be checked in django templates using:

{% if group in request.user.groups.all %} "some action" {% endif %}

Decrementing for loops

range step should be -1

   for k in range(10,0,-1):
      print k

How to avoid using Select in Excel VBA

To avoid using the .Select method, you can set a variable equal to the property that you want.

? For instance, if you want the value in Cell A1 you could set a variable equal to the value property of that cell.

  • Example valOne = Range("A1").Value

? For instance, if you want the codename of 'Sheet3you could set a variable equal to theCodename` property of that worksheet.

  • Example valTwo = Sheets("Sheet3").Codename

Regex doesn't work in String.matches()

[a-z] matches a single char between a and z. So, if your string was just "d", for example, then it would have matched and been printed out.

You need to change your regex to [a-z]+ to match one or more chars.

Declare and Initialize String Array in VBA

In the specific case of a String array you could initialize the array using the Split Function as it returns a String array rather than a Variant array:

Dim arrWsNames() As String
arrWsNames = Split("Value1,Value2,Value3", ",")

This allows you to avoid using the Variant data type and preserve the desired type for arrWsNames.

Getting the names of all files in a directory with PHP

glob() and FilesystemIterator examples:

 * glob() examples

// get the array of full paths
$result = glob( 'path/*' );

// get the array of file names
$result = array_map( function( $item ) {
    return basename( $item );
}, glob( 'path/*' ) );

 * FilesystemIterator examples

// get the array of file names by using FilesystemIterator and array_map()
$result = array_map( function( $item ) {
    // $item: SplFileInfo object
    return $item->getFilename();
}, iterator_to_array( new FilesystemIterator( 'path' ), false ) );

// get the array of file names by using FilesystemIterator and iterator_apply() filter
$it = new FilesystemIterator( 'path' );
    function( $item, &$result ) {
        // $item: FilesystemIterator object that points to current element
        $result[] = (string) $item;
        // The function must return TRUE in order to continue iterating
        return true;
    array( $it, &$result )

Android how to convert int to String?

You called an incorrect method of String class, try:

int tmpInt = 10;
String tmpStr10 = String.valueOf(tmpInt);

You can also do:

int tmpInt = 10;
String tmpStr10 = Integer.toString(tmpInt);

What is the correct way to declare a boolean variable in Java?

In your example, You don't need to. As a standard programming practice, all variables being referred to inside some code block, say for example try{} catch(){}, and being referred to outside the block as well, you need to declare the variables outside the try block first e.g.

This is helpful when your equals method call throws some exception e.g. NullPointerException;

     boolean isMatch = false;

         isMatch = email1.equals (email2);
      }catch(NullPointerException npe){

How to use font-family lato?

Please put this code in head section

<link href=',700' rel='stylesheet' type='text/css'>

and use font-family: 'Lato', sans-serif; in your css. For example:

h1 {
    font-family: 'Lato', sans-serif;
    font-weight: 400;

Or you can use manually also

Generate .ttf font from fontSquiral

and can try this option

    @font-face {
        font-family: "Lato";
        src: url('698242188-Lato-Bla.eot');
        src: url('698242188-Lato-Bla.eot?#iefix') format('embedded-opentype'),
        url('698242188-Lato-Bla.svg#Lato Black') format('svg'),
        url('698242188-Lato-Bla.woff') format('woff'),
        url('698242188-Lato-Bla.ttf') format('truetype');
        font-weight: normal;
        font-style: normal;

Called like this

body {
  font-family: 'Lato', sans-serif;

How do I find out if first character of a string is a number?

regular expression starts with number->'^[0-9]' 
Pattern pattern = Pattern.compile('^[0-9]');
 Matcher matcher = pattern.matcher(String);



Convert between UIImage and Base64 string

SWIFT 3.0, XCODE 8.0

Replace String with your URL. and testImage is an outlet of ImageView

// Put Your Image URL
let url:NSURL = NSURL(string : "http://.jpg")!
// It Will turn Into Data
let imageData : NSData = NSData.init(contentsOf: url as URL)!
// Data Will Encode into Base64
let str64 = imageData.base64EncodedData(options: .lineLength64Characters)
// Now Base64 will Decode Here
let data: NSData = NSData(base64Encoded: str64 , options: .ignoreUnknownCharacters)!
// turn  Decoded String into Data
let dataImage = UIImage(data: data as Data)
// pass the data image to image View.:)
testImage.image = dataImage

Hope It Helps Thanks.

How to validate an email address in JavaScript

I've mixed @mevius and @Boldewyn Code to Create this ultimate code for email verification using JavaScript.

function ValidateEmail(email){_x000D_
  var re = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;_x000D_
  var input = document.createElement('input');_x000D_
  input.type = 'email';_x000D_
  input.value = email;_x000D_
  return typeof input.checkValidity == 'function' ? input.checkValidity() : re.test(email);_x000D_

I have shared this code on my blog here.

What is a correct MIME type for .docx, .pptx, etc.?

Here are the correct Microsoft Office MIME types for HTTP content streaming:

Extension MIME Type
.doc      application/msword
.dot      application/msword

.docx     application/vnd.openxmlformats-officedocument.wordprocessingml.document
.dotx     application/vnd.openxmlformats-officedocument.wordprocessingml.template
.docm     application/
.dotm     application/

.xls      application/
.xlt      application/
.xla      application/

.xlsx     application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
.xltx     application/vnd.openxmlformats-officedocument.spreadsheetml.template
.xlsm     application/
.xltm     application/
.xlam     application/
.xlsb     application/

.ppt      application/
.pot      application/
.pps      application/
.ppa      application/

.pptx     application/vnd.openxmlformats-officedocument.presentationml.presentation
.potx     application/vnd.openxmlformats-officedocument.presentationml.template
.ppsx     application/vnd.openxmlformats-officedocument.presentationml.slideshow
.ppam     application/
.pptm     application/
.potm     application/
.ppsm     application/

.mdb      application/

For further details check out this TechNet article and this blog post.

C# find highest array value and index

Here is a LINQ solution which is O(n) with decent constant factors:

int[] anArray = { 1, 5, 2, 7, 1 };

int index = 0;
int maxIndex = 0;

var max = anArray.Aggregate(
    (oldMax, element) => {
        if (element <= oldMax)
            return oldMax;
        maxIndex = index;
        return element;

Console.WriteLine("max = {0}, maxIndex = {1}", max, maxIndex);

But you should really write an explicit for lop if you care about performance.

Programmatically find the number of cores on a machine

This functionality is part of the C++11 standard.

#include <thread>

unsigned int nthreads = std::thread::hardware_concurrency();

For older compilers, you can use the Boost.Thread library.

#include <boost/thread.hpp>

unsigned int nthreads = boost::thread::hardware_concurrency();

In either case, hardware_concurrency() returns the number of threads that the hardware is capable of executing concurrently based on the number of CPU cores and hyper-threading units.

Reloading .env variables without restarting server (Laravel 5, shared hosting)

To be clear there are 4 types of caches you can clear depending upon your case.

php artisan cache:clear

You can run the above statement in your console when you wish to clear the application cache. What it does is that this statement clears all caches inside storage\framework\cache.

php artisan route:cache

This clears your route cache. So if you have added a new route or have changed a route controller or action you can use this one to reload the same.

php artisan config:cache 

This will clear the caching of the env file and reload it

php artisan view:clear 

This will clear the compiled view files of your application.

For Shared Hosting

Most of the shared hosting providers don't provide SSH access to the systems. In such a case you will need to create a route and call the following line as below:

Route::get('/clear-cache', function() {
    return "All cache cleared";

What are the nuances of scope prototypal / prototypical inheritance in AngularJS?

Quick answer:
A child scope normally prototypically inherits from its parent scope, but not always. One exception to this rule is a directive with scope: { ... } -- this creates an "isolate" scope that does not prototypically inherit. This construct is often used when creating a "reusable component" directive.

As for the nuances, scope inheritance is normally straightfoward... until you need 2-way data binding (i.e., form elements, ng-model) in the child scope. Ng-repeat, ng-switch, and ng-include can trip you up if you try to bind to a primitive (e.g., number, string, boolean) in the parent scope from inside the child scope. It doesn't work the way most people expect it should work. The child scope gets its own property that hides/shadows the parent property of the same name. Your workarounds are

  1. define objects in the parent for your model, then reference a property of that object in the child: parentObj.someProp
  2. use $parent.parentScopeProperty (not always possible, but easier than 1. where possible)
  3. define a function on the parent scope, and call it from the child (not always possible)

New AngularJS developers often do not realize that ng-repeat, ng-switch, ng-view, ng-include and ng-if all create new child scopes, so the problem often shows up when these directives are involved. (See this example for a quick illustration of the problem.)

This issue with primitives can be easily avoided by following the "best practice" of always have a '.' in your ng-models – watch 3 minutes worth. Misko demonstrates the primitive binding issue with ng-switch.

Having a '.' in your models will ensure that prototypal inheritance is in play. So, use

<input type="text" ng-model="someObj.prop1">

<!--rather than
<input type="text" ng-model="prop1">`

L-o-n-g answer:

JavaScript Prototypal Inheritance

Also placed on the AngularJS wiki:

It is important to first have a solid understanding of prototypal inheritance, especially if you are coming from a server-side background and you are more familiar with class-ical inheritance. So let's review that first.

Suppose parentScope has properties aString, aNumber, anArray, anObject, and aFunction. If childScope prototypically inherits from parentScope, we have:

prototypal inheritance

(Note that to save space, I show the anArray object as a single blue object with its three values, rather than an single blue object with three separate gray literals.)

If we try to access a property defined on the parentScope from the child scope, JavaScript will first look in the child scope, not find the property, then look in the inherited scope, and find the property. (If it didn't find the property in the parentScope, it would continue up the prototype chain... all the way up to the root scope). So, these are all true:

childScope.aString === 'parent string'
childScope.anArray[1] === 20
childScope.anObject.property1 === 'parent prop1'
childScope.aFunction() === 'parent output'

Suppose we then do this:

childScope.aString = 'child string'

The prototype chain is not consulted, and a new aString property is added to the childScope. This new property hides/shadows the parentScope property with the same name. This will become very important when we discuss ng-repeat and ng-include below.

property hiding

Suppose we then do this:

childScope.anArray[1] = '22'
childScope.anObject.property1 = 'child prop1'

The prototype chain is consulted because the objects (anArray and anObject) are not found in the childScope. The objects are found in the parentScope, and the property values are updated on the original objects. No new properties are added to the childScope; no new objects are created. (Note that in JavaScript arrays and functions are also objects.)

follow the prototype chain

Suppose we then do this:

childScope.anArray = [100, 555]
childScope.anObject = { name: 'Mark', country: 'USA' }

The prototype chain is not consulted, and child scope gets two new object properties that hide/shadow the parentScope object properties with the same names.

more property hiding


  • If we read childScope.propertyX, and childScope has propertyX, then the prototype chain is not consulted.
  • If we set childScope.propertyX, the prototype chain is not consulted.

One last scenario:

delete childScope.anArray
childScope.anArray[1] === 22  // true

We deleted the childScope property first, then when we try to access the property again, the prototype chain is consulted.

after removing a child property

Angular Scope Inheritance

The contenders:

  • The following create new scopes, and inherit prototypically: ng-repeat, ng-include, ng-switch, ng-controller, directive with scope: true, directive with transclude: true.
  • The following creates a new scope which does not inherit prototypically: directive with scope: { ... }. This creates an "isolate" scope instead.

Note, by default, directives do not create new scope -- i.e., the default is scope: false.


Suppose we have in our controller:

$scope.myPrimitive = 50;
$scope.myObject    = {aNumber: 11};

And in our HTML:

<script type="text/ng-template" id="/tpl1.html">
<input ng-model="myPrimitive">
<div ng-include src="'/tpl1.html'"></div>

<script type="text/ng-template" id="/tpl2.html">
<input ng-model="myObject.aNumber">
<div ng-include src="'/tpl2.html'"></div>

Each ng-include generates a new child scope, which prototypically inherits from the parent scope.

ng-include child scopes

Typing (say, "77") into the first input textbox causes the child scope to get a new myPrimitive scope property that hides/shadows the parent scope property of the same name. This is probably not what you want/expect.

ng-include with a primitive

Typing (say, "99") into the second input textbox does not result in a new child property. Because tpl2.html binds the model to an object property, prototypal inheritance kicks in when the ngModel looks for object myObject -- it finds it in the parent scope.

ng-include with an object

We can rewrite the first template to use $parent, if we don't want to change our model from a primitive to an object:

<input ng-model="$parent.myPrimitive">

Typing (say, "22") into this input textbox does not result in a new child property. The model is now bound to a property of the parent scope (because $parent is a child scope property that references the parent scope).

ng-include with $parent

For all scopes (prototypal or not), Angular always tracks a parent-child relationship (i.e., a hierarchy), via scope properties $parent, $$childHead and $$childTail. I normally don't show these scope properties in the diagrams.

For scenarios where form elements are not involved, another solution is to define a function on the parent scope to modify the primitive. Then ensure the child always calls this function, which will be available to the child scope due to prototypal inheritance. E.g.,

// in the parent scope
$scope.setMyPrimitive = function(value) {
     $scope.myPrimitive = value;

Here is a sample fiddle that uses this "parent function" approach. (The fiddle was written as part of this answer:

See also and


ng-switch scope inheritance works just like ng-include. So if you need 2-way data binding to a primitive in the parent scope, use $parent, or change the model to be an object and then bind to a property of that object. This will avoid child scope hiding/shadowing of parent scope properties.

See also AngularJS, bind scope of a switch-case?


Ng-repeat works a little differently. Suppose we have in our controller:

$scope.myArrayOfPrimitives = [ 11, 22 ];
$scope.myArrayOfObjects    = [{num: 101}, {num: 202}]

And in our HTML:

<ul><li ng-repeat="num in myArrayOfPrimitives">
       <input ng-model="num">
<ul><li ng-repeat="obj in myArrayOfObjects">
       <input ng-model="obj.num">

For each item/iteration, ng-repeat creates a new scope, which prototypically inherits from the parent scope, but it also assigns the item's value to a new property on the new child scope. (The name of the new property is the loop variable's name.) Here's what the Angular source code for ng-repeat actually is:

childScope = scope.$new();  // child scope prototypically inherits from parent scope
childScope[valueIdent] = value;  // creates a new childScope property

If item is a primitive (as in myArrayOfPrimitives), essentially a copy of the value is assigned to the new child scope property. Changing the child scope property's value (i.e., using ng-model, hence child scope num) does not change the array the parent scope references. So in the first ng-repeat above, each child scope gets a num property that is independent of the myArrayOfPrimitives array:

ng-repeat with primitives

This ng-repeat will not work (like you want/expect it to). Typing into the textboxes changes the values in the gray boxes, which are only visible in the child scopes. What we want is for the inputs to affect the myArrayOfPrimitives array, not a child scope primitive property. To accomplish this, we need to change the model to be an array of objects.

So, if item is an object, a reference to the original object (not a copy) is assigned to the new child scope property. Changing the child scope property's value (i.e., using ng-model, hence obj.num) does change the object the parent scope references. So in the second ng-repeat above, we have:

ng-repeat with objects

(I colored one line gray just so that it is clear where it is going.)

This works as expected. Typing into the textboxes changes the values in the gray boxes, which are visible to both the child and parent scopes.

See also Difficulty with ng-model, ng-repeat, and inputs and


Nesting controllers using ng-controller results in normal prototypal inheritance, just like ng-include and ng-switch, so the same techniques apply. However, "it is considered bad form for two controllers to share information via $scope inheritance" -- A service should be used to share data between controllers instead.

(If you really want to share data via controllers scope inheritance, there is nothing you need to do. The child scope will have access to all of the parent scope properties. See also Controller load order differs when loading or navigating)


  1. default (scope: false) - the directive does not create a new scope, so there is no inheritance here. This is easy, but also dangerous because, e.g., a directive might think it is creating a new property on the scope, when in fact it is clobbering an existing property. This is not a good choice for writing directives that are intended as reusable components.
  2. scope: true - the directive creates a new child scope that prototypically inherits from the parent scope. If more than one directive (on the same DOM element) requests a new scope, only one new child scope is created. Since we have "normal" prototypal inheritance, this is like ng-include and ng-switch, so be wary of 2-way data binding to parent scope primitives, and child scope hiding/shadowing of parent scope properties.
  3. scope: { ... } - the directive creates a new isolate/isolated scope. It does not prototypically inherit. This is usually your best choice when creating reusable components, since the directive cannot accidentally read or modify the parent scope. However, such directives often need access to a few parent scope properties. The object hash is used to set up two-way binding (using '=') or one-way binding (using '@') between the parent scope and the isolate scope. There is also '&' to bind to parent scope expressions. So, these all create local scope properties that are derived from the parent scope. Note that attributes are used to help set up the binding -- you can't just reference parent scope property names in the object hash, you have to use an attribute. E.g., this won't work if you want to bind to parent property parentProp in the isolated scope: <div my-directive> and scope: { localProp: '@parentProp' }. An attribute must be used to specify each parent property that the directive wants to bind to: <div my-directive the-Parent-Prop=parentProp> and scope: { localProp: '@theParentProp' }.
    Isolate scope's __proto__ references Object. Isolate scope's $parent references the parent scope, so although it is isolated and doesn't inherit prototypically from the parent scope, it is still a child scope.
    For the picture below we have
    <my-directive interpolated="{{parentProp1}}" twowayBinding="parentProp2"> and
    scope: { interpolatedProp: '@interpolated', twowayBindingProp: '=twowayBinding' }
    Also, assume the directive does this in its linking function: scope.someIsolateProp = "I'm isolated"
    isolated scope
    For more information on isolate scopes see
  4. transclude: true - the directive creates a new "transcluded" child scope, which prototypically inherits from the parent scope. The transcluded and the isolated scope (if any) are siblings -- the $parent property of each scope references the same parent scope. When a transcluded and an isolate scope both exist, isolate scope property $$nextSibling will reference the transcluded scope. I'm not aware of any nuances with the transcluded scope.
    For the picture below, assume the same directive as above with this addition: transclude: true
    transcluded scope

This fiddle has a showScope() function that can be used to examine an isolate and transcluded scope. See the instructions in the comments in the fiddle.


There are four types of scopes:

  1. normal prototypal scope inheritance -- ng-include, ng-switch, ng-controller, directive with scope: true
  2. normal prototypal scope inheritance with a copy/assignment -- ng-repeat. Each iteration of ng-repeat creates a new child scope, and that new child scope always gets a new property.
  3. isolate scope -- directive with scope: {...}. This one is not prototypal, but '=', '@', and '&' provide a mechanism to access parent scope properties, via attributes.
  4. transcluded scope -- directive with transclude: true. This one is also normal prototypal scope inheritance, but it is also a sibling of any isolate scope.

For all scopes (prototypal or not), Angular always tracks a parent-child relationship (i.e., a hierarchy), via properties $parent and $$childHead and $$childTail.

Diagrams were generated with "*.dot" files, which are on github. Tim Caswell's "Learning JavaScript with Object Graphs" was the inspiration for using GraphViz for the diagrams.

Converting string into datetime

In [34]: import datetime

In [35]: _now =

In [36]: _now
Out[36]: datetime.datetime(2016, 1, 19, 9, 47, 0, 432000)

In [37]: print _now
2016-01-19 09:47:00.432000

In [38]: _parsed = datetime.datetime.strptime(str(_now),"%Y-%m-%d %H:%M:%S.%f")

In [39]: _parsed
Out[39]: datetime.datetime(2016, 1, 19, 9, 47, 0, 432000)

In [40]: assert _now == _parsed

Load a WPF BitmapImage from a System.Drawing.Bitmap

I work at an imaging vendor and wrote an adapter for WPF to our image format which is similar to a System.Drawing.Bitmap.

I wrote this KB to explain it to our customers:

And there is code there that does it. You need to replace AtalaImage with Bitmap and do the equivalent thing that we are doing -- it should be pretty straightforward.

pip connection failure: cannot fetch index base URL

I also got this error while installing pyinstaller in a proxied connection. I just connect direct Internet connection(Using my dongle) and did that again.

 sudo pip install pyinstaller

This worked for me.

Could not install packages due to a "Environment error :[error 13]: permission denied : 'usr/local/bin/f2py'"

This worked for me.

pip3 install --user package-name  # for Python3
pip install --user package-name   # for Python2

The --user flag tells Python to install in the user home directory. By default it will go to system locations. credit

Test method is inconclusive: Test wasn't run. Error?

Have you added any DLL dependency recently? ... like me

I just ran into the same issue and it was very exasperating not to get any clue in the test output window or elsewhere practical.

The cause was extremely stupid: I just added the day before dependency to an additional external DLL in a sub-project, and the main project App indeed built and ran correctly after the change. But my unit tests are in a sister project to the main app, and thus had too the dependency on this changed sub project where the DLL was invoked... yet, the runtime location of the test project is not that of the main App! So changing the build to do copying of the missing DLL into the test runtime directory fixed the problem.

Semi-transparent color layer over background-image?

Why so complicated? Your solution was almost right except it's a way easier to make the pattern transparent and the background color solid. PNG can contain transparencies. So use photoshop to make the pattern transparent by setting the layer to 70% and resaving your image. Then you only need one selector. Works cross browser.


.background {
   background: url('../img/bg/diagonalnoise.png');/* transparent png image*/
   background-color: rgb(248, 247, 216);


<div class="background">

This are the basic. A usage example follows where I switched from background to background-image but both properties works the same.

body { margin: 0; }_x000D_
div {_x000D_
   height: 110px !important;_x000D_
   padding: 1em;_x000D_
   text-transform: uppercase;_x000D_
   font-family: Arial, Helvetica, sans-serif;_x000D_
   font-weight: 600;_x000D_
   color: white;_x000D_
   text-shadow: 0 0 2px #333;_x000D_
.background {_x000D_
   background-image: url('');/* transparent png image */_x000D_
.col-one {_x000D_
  background-color: rgb(255, 255, 0);_x000D_
.col-two {_x000D_
  background-color: rgb(0, 255, 255);_x000D_
.col-three {_x000D_
  background-color: rgb(0, 255, 0);_x000D_
<div class="background col-one">_x000D_
 1. Background_x000D_
</div> _x000D_
<div class="background col-two">_x000D_
 2. Background_x000D_
</div> _x000D_
<div class="background col-three">_x000D_
 3. Background_x000D_


This website seems to be rather slow...

C++ passing an array pointer as a function argument

You're over-complicating it - it just needs to be:

void generateArray(int *a, int si)
    for (int j = 0; j < si; j++)
        a[j] = rand() % 9;

int main()
    const int size=5;
    int a[size];

    generateArray(a, size);

    return 0;

When you pass an array as a parameter to a function it decays to a pointer to the first element of the array. So there is normally never a need to pass a pointer to an array.

open program minimized via command prompt

You could try using the third-party tool called NirCmd. It is a genuine, free command line utility. If or when you have it, use this code in a batch file:

title Open Word
nircmd win hide title "Open Word"
start "C:\Program" "Files" "(x86)\Microsoft" "Office\Office12\WINWORD.exe
nircmd wait 20
nircmd win min foreground

This program, in order, changes its title, hides itself according to its title, starts Word, waits 20 milliseconds as a buffer for Word to settle, minimizes Word by assuming it is now the top window, and then exits itself. This program should work as intended as long as their are no key presses or clicks in that ~50 millisecond time window, which shouldn't be hard.

As for installing nircmd on your computer, use this link, and click "Download NirCmd" at the bottom of the page. Save the .zip folder to a normal directory (like "My Documents"), extract it, and copy "nircmd.exe" to %systemroot%\system32, and there you go. Now you have nircmd included with your command line utilities.

How to make connection to Postgres via Node.js

Connection String

The connection string is a string of the form:


(where the parts in [...] can optionally be included or excluded)

Some examples of valid connection strings include:


If you've just started a database on your local machine, the connection string postgres://localhost will typically work, as that uses the default port number, username, and no password. If the database was started with a specific account, you might find you need to use postgres://pg@localhost or postgres://postgres@localhost

If none of these work, and you have installed docker, another option is to run npx @databases/pg-test start. This will start a postgres server in a docker container and then print out the connection string for you. The pg-test databases are only intended for testing though, so you will loose all your data if your computer restarts.

Connecting in node.js

You can connect to the database and issue queries using @databases/pg:

const createPool = require('@databases/pg');
const {sql} = require('@databases/pg');

// If you're using TypeScript or Babel, you can swap
// the two `require` calls for this import statement:

// import createPool, {sql} from '@databases/pg';

// create a "pool" of connections, you can think of this as a single
// connection, the pool is just used behind the scenes to improve
// performance
const db = createPool('postgres://localhost');

// wrap code in an `async` function so we can use `await`
async function run() {

  // we can run sql by tagging it as "sql" and then passing it to db.query
  await db.query(sql`
      name TEXT NOT NULL,
      height INT NOT NULL,
      birthday DATE NOT NULL

  const beatle = {
    name: 'George',
    height: 70,
    birthday: new Date(1946, 02, 14),

  // If we need to pass values, we can use ${...} and they will
  // be safely & securely escaped for us
  await db.query(sql`
    INSERT INTO beatles (name, height, birthday)
    VALUES (${}, ${beatle.height}, ${beatle.birthday});

    await db.query(sql`SELECT * FROM beatles;`)

run().catch(ex => {
  // It's a good idea to always report errors using
  // `console.error` and set the process.exitCode if
  // you're calling an async function at the top level
  process.exitCode = 1;
}).then(() => {
  // For this little demonstration, we'll dispose of the
  // connection pool when we're done, so that the process
  // exists. If you're building a web server/backend API
  // you probably never need to call this.
  return db.dispose();

You can find a more complete guide to querying Postgres using node.js at

Does uninstalling a package with "pip" also remove the dependent packages?

You can install and use the pip-autoremove utility to remove a package plus unused dependencies.

# install pip-autoremove
pip install pip-autoremove
# remove "somepackage" plus its dependencies:
pip-autoremove somepackage -y

How do I interpret precision and scale of a number in a database?

Precision of a number is the number of digits.

Scale of a number is the number of digits after the decimal point.

What is generally implied when setting precision and scale on field definition is that they represent maximum values.

Example, a decimal field defined with precision=5 and scale=2 would allow the following values:

  • 123.45 (p=5,s=2)
  • 12.34 (p=4,s=2)
  • 12345 (p=5,s=0)
  • 123.4 (p=4,s=1)
  • 0 (p=0,s=0)

The following values are not allowed or would cause a data loss:

  • 12.345 (p=5,s=3) => could be truncated into 12.35 (p=4,s=2)
  • 1234.56 (p=6,s=2) => could be truncated into 1234.6 (p=5,s=1)
  • 123.456 (p=6,s=3) => could be truncated into 123.46 (p=5,s=2)
  • 123450 (p=6,s=0) => out of range

Note that the range is generally defined by the precision: |value| < 10^p ...

Concatenating variables and strings in React

you can simply do this..

 <img src={"" + this.props.url +"/1.jpg"}/>

How to search for an element in a golang slice

There is no library function for that. You have to code by your own.

for _, value := range myconfig {
    if value.Key == "key1" {
        // logic

Working code:

package main

import (

func main() {
    type Config struct {
        Key   string
        Value string

    var respbody = []byte(`[
        {"Key":"Key1", "Value":"Value1"},
        {"Key":"Key2", "Value":"Value2"}

    var myconfig []Config

    err := json.Unmarshal(respbody, &myconfig)
    if err != nil {
        fmt.Println("error:", err)

    fmt.Printf("%+v\n", myconfig)

    for _, v := range myconfig {
        if v.Key == "Key1" {
            fmt.Println("Value: ", v.Value)


How to trigger a build only if changes happen on particular set of files

I wrote this script to skip or execute tests if there are changes:


set -e -o pipefail -u

while [ "$1" != "--" ]; do
    paths+=( "$1" ); shift

if git diff --quiet --exit-code "${BASE_BRANCH:-origin/master}"..HEAD ${paths[@]}; then
    echo "No changes in ${paths[@]}, skipping $@..." 1>&2
    exit 0
echo "Changes found in ${paths[@]}, running $@..." 1>&2

exec "$@"

So you can do something like:

./scripts/ cmd vendor go.mod go.sum fixtures/ tools/ -- go test

Javascript ES6 export const vs export let

In ES6, imports are live read-only views on exported-values. As a result, when you do import a from "somemodule";, you cannot assign to a no matter how you declare a in the module.

However, since imported variables are live views, they do change according to the "raw" exported variable in exports. Consider the following code (borrowed from the reference article below):

//------ lib.js ------
export let counter = 3;
export function incCounter() {

//------ main1.js ------
import { counter, incCounter } from './lib';

// The imported value `counter` is live
console.log(counter); // 3
console.log(counter); // 4

// The imported value can’t be changed
counter++; // TypeError

As you can see, the difference really lies in lib.js, not main1.js.

To summarize:

  • You cannot assign to import-ed variables, no matter how you declare the corresponding variables in the module.
  • The traditional let-vs-const semantics applies to the declared variable in the module.
    • If the variable is declared const, it cannot be reassigned or rebound in anywhere.
    • If the variable is declared let, it can only be reassigned in the module (but not the user). If it is changed, the import-ed variable changes accordingly.


NoClassDefFoundError for code in an Java library on Android

I am guessing that you don't specify javac's target when creating the common library, so javac automatically uses the latest available target, which is likely 1.7 (Java7) or 1.8 (Java8).

It has already been stated that

Android requires compiler compliance level 5.0 or 6.0

dx of Android's build tools < 19.0.0 isn't able to convert Java7 (or higher) bytecode to Dalvik bytecode.

So either use a build tools version >= 19.0.0 or use javac with -target 6, by modifying for example your ant build.xml like this:


How to find if an array contains a string

I'm afraid I don't think there's a shortcut to do this - if only someone would write a linq wrapper for VB6!

You could write a function that does it by looping through the array and checking each entry - I don't think you'll get cleaner than that.

There's an example article that provides some details here:

Converting a string to an integer on Android

You should covert String to float. It is working.

float result = 0;
 if (TextUtils.isEmpty(et.getText().toString()) {

result = Float.parseFloat(et.getText().toString());


How to prevent browser to invoke basic auth popup and handle 401 error using Jquery?

As others have pointed out, the only way to change the browser's behavior is to make sure the response either does not contain a 401 status code or if it does, not include the WWW-Authenticate: Basic header. Since changing the status code is not very semantic and undesirable, a good approach is to remove the WWW-Authenticate header. If you can't or don't want to modify your web server application, you can always serve or proxy it through Apache (if you are not using Apache already).

Here is a configuration for Apache to rewrite the response to remove the WWW-Authenticate header IFF the request contains contains the header X-Requested-With: XMLHttpRequest (which is set by default by major Javascript frameworks such as JQuery/AngularJS, etc...) AND the response contains the header WWW-Authenticate: Basic.

Tested on Apache 2.4 (not sure if it works with 2.2). This relies on the mod_headers module being installed. (On Debian/Ubuntu, sudo a2enmod headers and restart Apache)

    <Location />
            # Make sure that if it is an XHR request,
            # we don't send back basic authentication header.
            # This is to prevent the browser from displaying a basic auth login dialog.
            Header unset WWW-Authenticate "expr=req('X-Requested-With') == 'XMLHttpRequest' && resp('WWW-Authenticate') =~ /^Basic/"