Programs & Examples On #Qml

QML (Qt Modeling Language) is a declarative language that allows user interfaces to be described in terms of their visual components and how they interact and relate with one another. It is a highly readable language, JSON-like syntax with support for imperative JavaScript expressions combined with dynamic property bindings. It can be used to build fluid animated user interfaces that can be connected to any backend C++ libraries.

Python list directory, subdirectory, and files

It's just an addition, with this you can get the data into CSV format

import sys,os
    import pandas as pd
    os.system("pip3 install pandas")
root = "/home/kiran/Downloads/MainFolder" # it may have many subfolders and files inside
lst = []
from fnmatch import fnmatch
pattern = "*.csv"      #I want to get only csv files 
pattern = "*.*"        # Note: Use this pattern to get all types of files and folders 
for path, subdirs, files in os.walk(root):
    for name in files:
        if fnmatch(name, pattern):
            lst.append((os.path.join(path, name)))
df = pd.DataFrame({"filePaths":lst})

ValueError when checking if variable is None or numpy.array

To stick to == without consideration of the other type, the following is also possible.
type(a) == type(None)

What's the safest way to iterate through the keys of a Perl hash?

The place where each can cause you problems is that it's a true, non-scoped iterator. By way of example:

while ( my ($key,$val) = each %a_hash ) {
    print "$key => $val\n";
    last if $val; #exits loop when $val is true

# but "each" hasn't reset!!
while ( my ($key,$val) = each %a_hash ) {
    # continues where the last loop left off
    print "$key => $val\n";

If you need to be sure that each gets all the keys and values, you need to make sure you use keys or values first (as that resets the iterator). See the documentation for each.

svn cleanup: sqlite: database disk image is malformed

Throughout my researches, I've found 2 viable solutions.

  1. If you're using any type of connections, ssh, samba, mounting, disconnect/unmount and reconnect/remount. Try again, this often resolved the problem for me. After that you can do svn cleanup or just keep on working normally (depending on when the problem appeared). Rebooting my computer also fixed the problem once... yes it's dumb I know!

  2. Some times all there is to do is to rm -rf your files (or if you're not familiar with the term, just delete your svn folder), and recheckout your svn repository once again. Please note that this does not always solve the problem and you might also have changes you don't want to lose. Which is why I use it as the second option.

Hope this helps you guys!

Returning JSON response from Servlet to Javascript/JSP page

I think that what you want to do is turn the JSON string back into an object when it arrives back in your XMLHttpRequest - correct?

If so, you need to eval the string to turn it into a JavaScript object - note that this can be unsafe as you're trusting that the JSON string isn't malicious and therefore executing it. Preferably you could use jQuery's parseJSON

Should I put input elements inside a label element?

From w3:

The label itself may be positioned before, after or around the associated control.

<label for="lastname">Last Name</label>
<input type="text" id="lastname" />


<input type="text" id="lastname" />
<label for="lastname">Last Name</label>


   <input type="text" name="lastname" />
   Last Name

Note that the third technique cannot be used when a table is being used for layout, with the label in one cell and its associated form field in another cell.

Either one is valid. I like to use either the first or second example, as it gives you more style control.

isolating a sub-string in a string before a symbol in SQL Server 2008

DECLARE @test nvarchar(100)

SET @test = 'Foreign Tax Credit - 1997'

SELECT @test, left(@test, charindex('-', @test) - 2) AS LeftString,
    right(@test, len(@test) - charindex('-', @test) - 1)  AS RightString

Update data on a page without refreshing

Suppose you want to display some live feed content (say livefeed.txt) on you web page without any page refresh then the following simplified example is for you.

In the below html file, the live data gets updated on the div element of id "liveData"


<!DOCTYPE html>
    <title>Live Update</title>
    <meta charset="UTF-8">
    <script type="text/javascript" src="autoUpdate.js"></script>
<div id="liveData">
    <p>Loading Data...</p>

Below autoUpdate.js reads the live data using XMLHttpRequest object and updates the html div element on every 1 second. I have given comments on most part of the code for better understanding.


window.addEventListener('load', function()
    var xhr = null;

    getXmlHttpRequestObject = function()
            // Create a new XMLHttpRequest object 
            xhr = new XMLHttpRequest();
        return xhr;

    updateLiveData = function()
        var now = new Date();
        // Date string is appended as a query with live data 
        // for not to use the cached version 
        var url = 'livefeed.txt?' + now.getTime();
        xhr = getXmlHttpRequestObject();
        xhr.onreadystatechange = evenHandler;
        // asynchronous requests"GET", url, true);
        // Send the request over the network


    function evenHandler()
        // Check response is ready or not
        if(xhr.readyState == 4 && xhr.status == 200)
            dataDiv = document.getElementById('liveData');
            // Set current data text
            dataDiv.innerHTML = xhr.responseText;
            // Update the live data every 1 sec
            setTimeout(updateLiveData(), 1000);

For testing purpose: Just write some thing in the livefeed.txt - You will get updated the same in index.html without any refresh.



Note: You need to run the above code on the web server (ex: http://localhost:1234/index.html) not as a client html file (ex: file:///C:/index.html).

Converting PKCS#12 certificate into PEM using OpenSSL

You just need to supply a password. You can do it within the same command line with the following syntax:

openssl pkcs12 -export -in "path.p12" -out "newfile.pem" -passin pass:[password]

You will then be prompted for a password to encrypt the private key in your output file. Include the "nodes" option in the line above if you want to export the private key unencrypted (plaintext):

openssl pkcs12 -export -in "path.p12" -out "newfile.pem" -passin pass:[password] -nodes

More info:

Converting a PDF to PNG

Try to extract a single page.

$page = 4

gs -sDEVICE=pngalpha -dFirstPage="$page" -dLastPage="$page" -o thumb.png -r144 input.pdf

Add and remove multiple classes in jQuery

easiest way to append class name using javascript. It can be useful when .siblings() are misbehaving.

document.getElementById('myId').className += ' active';

How does the Java 'for each' loop work?

It would look something like this. Very crufty.

for (Iterator<String> i = someList.iterator(); i.hasNext(); )

There is a good writeup on for each in the Sun documentation.

How do I get a TextBox to only accept numeric input in WPF?

I used some of what was already here and put my own twist on it using a behavior so I don't have to propagate this code throughout a ton of Views...

public class AllowableCharactersTextBoxBehavior : Behavior<TextBox>
    public static readonly DependencyProperty RegularExpressionProperty =
         DependencyProperty.Register("RegularExpression", typeof(string), typeof(AllowableCharactersTextBoxBehavior),
         new FrameworkPropertyMetadata(".*"));
    public string RegularExpression
            return (string)base.GetValue(RegularExpressionProperty);
            base.SetValue(RegularExpressionProperty, value);

    public static readonly DependencyProperty MaxLengthProperty =
        DependencyProperty.Register("MaxLength", typeof(int), typeof(AllowableCharactersTextBoxBehavior),
        new FrameworkPropertyMetadata(int.MinValue));
    public int MaxLength
            return (int)base.GetValue(MaxLengthProperty);
            base.SetValue(MaxLengthProperty, value);

    protected override void OnAttached()
        AssociatedObject.PreviewTextInput += OnPreviewTextInput;
        DataObject.AddPastingHandler(AssociatedObject, OnPaste);

    private void OnPaste(object sender, DataObjectPastingEventArgs e)
        if (e.DataObject.GetDataPresent(DataFormats.Text))
            string text = Convert.ToString(e.DataObject.GetData(DataFormats.Text));

            if (!IsValid(text, true))

    void OnPreviewTextInput(object sender, System.Windows.Input.TextCompositionEventArgs e)
        e.Handled = !IsValid(e.Text, false);

    protected override void OnDetaching()
        AssociatedObject.PreviewTextInput -= OnPreviewTextInput;
        DataObject.RemovePastingHandler(AssociatedObject, OnPaste);

    private bool IsValid(string newText, bool paste)
        return !ExceedsMaxLength(newText, paste) && Regex.IsMatch(newText, RegularExpression);

    private bool ExceedsMaxLength(string newText, bool paste)
        if (MaxLength == 0) return false;

        return LengthOfModifiedText(newText, paste) > MaxLength;

    private int LengthOfModifiedText(string newText, bool paste)
        var countOfSelectedChars = this.AssociatedObject.SelectedText.Length;
        var caretIndex = this.AssociatedObject.CaretIndex;
        string text = this.AssociatedObject.Text;

        if (countOfSelectedChars > 0 || paste)
            text = text.Remove(caretIndex, countOfSelectedChars);
            return text.Length + newText.Length;
            var insert = Keyboard.IsKeyToggled(Key.Insert);

            return insert && caretIndex < text.Length ? text.Length : text.Length + newText.Length;

Here is the relevant view code:

<TextBox MaxLength="50" TextWrapping="Wrap" MaxWidth="150" Margin="4"
 Text="{Binding Path=FileNameToPublish}" >
         <v:AllowableCharactersTextBoxBehavior RegularExpression="^[0-9.\-]+$" MaxLength="50" />

Representing EOF in C code?

I have been researching a lot about the EOF signal. In the book on Programming in C by Dennis Ritchie it is first encountered while introducing putchar() and getchar() commands. It basically marks the end of the character string input.

For eg. Let us write a program that seeks two numerical inputs and prints their sum. You'll notice after each numerical input you press Enter to mark the signal that you have completed the iput action. But while working with character strings Enter is read as just another character ['\n': newline character]. To mark the termination of input you enter ^Z(Ctrl + Z on keyboard) in a completely new line and then enter. That signals the next lines of command to get executed.

#include <stdio.h>

int main()
char c;
int i = 0;
c = getchar();

while (c != EOF)
   c = getchar();

printf("NUMBER OF CHARACTERS %d.", i);

return 0;}

The above is the code to count number of characters including '\n'(newline) and '\t'( space) characters. If you don't wanna count the newline characters do this :

#include <stdio.h>

int main()
char c;
int i = 0;
c = getchar();

while (c != EOF)
    if (c != '\n')

    c = getchar();

printf("NUMBER OF CHARACTERS %d.", i);

return 0;}. 

NOW THE MAIN THINK HOOW TO GIVE INPUT. IT'S SIMPLE: Write all the story you want then go in a new line and enter ^Z and then enter again.

How to terminate script execution when debugging in Google Chrome?

Open the source tab in 'Developer Tools', click on a line number in a script that is running, this will create a breakpoint and the debugger will break there.

How to remove margin space around body or clear default css styles

try removing the padding/margins from the body tag.


What generates the "text file busy" message in Unix?

If you are running the .sh from a ssh connection with a tool like MobaXTerm, and if said tool has an autosave utility to edit remote file from local machine, that will lock the file.

Closing and reopening the SSH session solves it.

Why does one use dependency injection?

First, I want to explain an assumption that I make for this answer. It is not always true, but quite often:

Interfaces are adjectives; classes are nouns.

(Actually, there are interfaces that are nouns as well, but I want to generalize here.)

So, e.g. an interface may be something such as IDisposable, IEnumerable or IPrintable. A class is an actual implementation of one or more of these interfaces: List or Map may both be implementations of IEnumerable.

To get the point: Often your classes depend on each other. E.g. you could have a Database class which accesses your database (hah, surprise! ;-)), but you also want this class to do logging about accessing the database. Suppose you have another class Logger, then Database has a dependency to Logger.

So far, so good.

You can model this dependency inside your Database class with the following line:

var logger = new Logger();

and everything is fine. It is fine up to the day when you realize that you need a bunch of loggers: Sometimes you want to log to the console, sometimes to the file system, sometimes using TCP/IP and a remote logging server, and so on ...

And of course you do NOT want to change all your code (meanwhile you have gazillions of it) and replace all lines

var logger = new Logger();


var logger = new TcpLogger();

First, this is no fun. Second, this is error-prone. Third, this is stupid, repetitive work for a trained monkey. So what do you do?

Obviously it's a quite good idea to introduce an interface ICanLog (or similar) that is implemented by all the various loggers. So step 1 in your code is that you do:

ICanLog logger = new Logger();

Now the type inference doesn't change type any more, you always have one single interface to develop against. The next step is that you do not want to have new Logger() over and over again. So you put the reliability to create new instances to a single, central factory class, and you get code such as:

ICanLog logger = LoggerFactory.Create();

The factory itself decides what kind of logger to create. Your code doesn't care any longer, and if you want to change the type of logger being used, you change it once: Inside the factory.

Now, of course, you can generalize this factory, and make it work for any type:

ICanLog logger = TypeFactory.Create<ICanLog>();

Somewhere this TypeFactory needs configuration data which actual class to instantiate when a specific interface type is requested, so you need a mapping. Of course you can do this mapping inside your code, but then a type change means recompiling. But you could also put this mapping inside an XML file, e.g.. This allows you to change the actually used class even after compile time (!), that means dynamically, without recompiling!

To give you a useful example for this: Think of a software that does not log normally, but when your customer calls and asks for help because he has a problem, all you send to him is an updated XML config file, and now he has logging enabled, and your support can use the log files to help your customer.

And now, when you replace names a little bit, you end up with a simple implementation of a Service Locator, which is one of two patterns for Inversion of Control (since you invert control over who decides what exact class to instantiate).

All in all this reduces dependencies in your code, but now all your code has a dependency to the central, single service locator.

Dependency injection is now the next step in this line: Just get rid of this single dependency to the service locator: Instead of various classes asking the service locator for an implementation for a specific interface, you - once again - revert control over who instantiates what.

With dependency injection, your Database class now has a constructor that requires a parameter of type ICanLog:

public Database(ICanLog logger) { ... }

Now your database always has a logger to use, but it does not know any more where this logger comes from.

And this is where a DI framework comes into play: You configure your mappings once again, and then ask your DI framework to instantiate your application for you. As the Application class requires an ICanPersistData implementation, an instance of Database is injected - but for that it must first create an instance of the kind of logger which is configured for ICanLog. And so on ...

So, to cut a long story short: Dependency injection is one of two ways of how to remove dependencies in your code. It is very useful for configuration changes after compile-time, and it is a great thing for unit testing (as it makes it very easy to inject stubs and / or mocks).

In practice, there are things you can not do without a service locator (e.g., if you do not know in advance how many instances you do need of a specific interface: A DI framework always injects only one instance per parameter, but you can call a service locator inside a loop, of course), hence most often each DI framework also provides a service locator.

But basically, that's it.

P.S.: What I described here is a technique called constructor injection, there is also property injection where not constructor parameters, but properties are being used for defining and resolving dependencies. Think of property injection as an optional dependency, and of constructor injection as mandatory dependencies. But discussion on this is beyond the scope of this question.

How to Check byte array empty or not?

In Android Studio version 3.4.1

if(Attachment != null)
   code here ...

Datatables on-the-fly resizing

What is happening is that DataTables is setting the CSS width of the table when it is initialised to a calculated value - that value is in pixels, hence why it won't resize with your dragging. The reason it does this is to stop the table and the columns (the column widths are also set) jumping around in width when you change pagination.

What you can do to stop this behaviour in DataTables is set the autoWidth parameter to false.

$('#example').dataTable( {
  "autoWidth": false
} );

That will stop DataTables adding its calculated widths to the table, leaving your (presumably) width:100% alone and allowing it to resize. Adding a relative width to the columns would also help stop the columns bouncing.

One other option that is built into DataTables is to set the sScrollX option to enable scrolling, as DataTables will set the table to be 100% width of the scrolling container. But you might not want scrolling.

The prefect solution would be if I could get the CSS width of the table (assuming one is applied - i.e. 100%), but without parsing the stylesheets, I don't see a way of doing that (i.e. basically I want $().css('width') to return the value from the stylesheet, not the pixel calculated value).

Right way to write JSON deserializer in Spring or extend it

I've searched a lot and the best way I've found so far is on this article:

Class to serialize

package net.sghill.example;

import net.sghill.example.UserDeserializer
import net.sghill.example.UserSerializer

@JsonDeserialize(using = UserDeserializer.class)
public class User {
    private ObjectId id;
    private String   username;
    private String   password;

    public User(ObjectId id, String username, String password) { = id;
        this.username = username;
        this.password = password;

    public ObjectId getId()       { return id; }
    public String   getUsername() { return username; }
    public String   getPassword() { return password; }

Deserializer class

package net.sghill.example;

import net.sghill.example.User;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.ObjectCodec;


public class UserDeserializer extends JsonDeserializer<User> {

    public User deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
        ObjectCodec oc = jsonParser.getCodec();
        JsonNode node = oc.readTree(jsonParser);
        return new User(null, node.get("username").getTextValue(), node.get("password").getTextValue());

Edit: Alternatively you can look at this article which uses new versions of com.fasterxml.jackson.databind.JsonDeserializer.

How to check syslog in Bash on Linux?

On Fedora 19, it looks like the answer is /var/log/messages. Although check /etc/rsyslog.conf if it has been changed.

Select element based on multiple classes

You can use these solutions :

CSS rules applies to all tags that have following two classes :

.left.ui-class-selector {
    /*style here*/

CSS rules applies to all tags that have <li> with following two classes :

li.left.ui-class-selector {
   /*style here*/

jQuery solution :

$("li.left.ui-class-selector").css("color", "red");

Javascript solution :

document.querySelector("li.left.ui-class-selector").style.color = "red";

Change drive in git bash for windows

TL;DR; for Windows users:

(Quotation marks not needed if path has no blank spaces)

Git Bash: cd "/C/Program Files (x86)/Android" // macOS/Linux syntax

Cmd.exe: cd "C:\Program Files (x86)\Android" // windows syntax

When using git bash on windows, you have to:

  • remove the colon after the drive letter
  • replace your back-slashes with forward-slashes
  • If you have blank spaces in your path: Put quotation marks at beginning and end of the path

Git Bash: cd "/C/Program Files (x86)/Android" // macOS/Linux syntax

Cmd.exe: cd "C:\Program Files (x86)\Android" // windows syntax

sudo in php exec()

I think you can bring specific access to user and command with visudo something like this:

nobody ALL = NOPASSWD: /path/to/osascript myscript.scpt

and with php:

@exec("sudo /path/to/osascript myscript.scpt ");

supposing nobody user is running apache.

Splitting a table cell into two columns in HTML

Like this

Add colspan="2" to the 3rd <th> and then have 4 <td>'s in your second row.

<table border="1">
    <th scope="col">Header</th>
    <th scope="col">Header</th>
    <th scope="col" colspan="2">Header</th>
    <th scope="row">&nbsp;</th>
    <!-- The following two cells will appear under the same header -->
    <td>Col 1</td>
    <td>Col 2</td>

Recreating a Dictionary from an IEnumerable<KeyValuePair<>>

If you're using .NET 3.5 or .NET 4, it's easy to create the dictionary using LINQ:

Dictionary<string, ArrayList> result = target.GetComponents()
                                      .ToDictionary(x => x.Key, x => x.Value);

There's no such thing as an IEnumerable<T1, T2> but a KeyValuePair<TKey, TValue> is fine.

How to fix the error; 'Error: Bootstrap tooltips require Tether ('

And if using webpack, you will need the expose plugin. In your webpack.config.js, add this loader

   test: require.resolve("tether"),
   loader: "expose?$!expose?Tether"

How can I generate an MD5 hash?

No need to make it too complicated.
DigestUtils works fine and makes you comfortable while working with md5 hashes.




Either you can use any other encryption methods such as sha or md.

jquery - is not a function error

When converting an ASP.Net webform prototype to a MVC site I got these errors:

TypeError: $(...).accordion is not a function

TypeError: $(...).dialog is not a function

It worked fine in the webforms. The problem/solution was this line in the _Layout.cshtml


Comment it out to see if the errors go away. Then fix it in the BundlesConfig:

bundles.Add(new ScriptBundle("~/bundles/jquery").Include(

How can I set a UITableView to grouped style

If i understand what you mean, you have to initialize your controller with that style. Something like:

myTVContoller = [[UITableViewController alloc] initWithStyle:UITableViewStyleGrouped];

Can I have two JavaScript onclick events in one element?


<a href="#" id="btn">click</a>

And the javascript

// get a cross-browser function for adding events, place this in [global] or somewhere you can access it
var on = (function(){
    if (window.addEventListener) {
        return function(target, type, listener){
            target.addEventListener(type, listener, false);
    else {
        return function(object, sEvent, fpNotify){
            object.attachEvent("on" + sEvent, fpNotify);

// find the element
var el = document.getElementById("btn");

// add the first listener
on(el, "click", function(){

// add the second listener
on(el, "click", function(){

This will alert both 'foo' and 'bar' when clicked.

get UTC time in PHP

You can use following to get UTC time:


$current_date = date("Y/m/d g:i A");

$ist_date = DateTime::createFromFormat(
                        '"Y/m/d g:i A"',
                        new DateTimeZone('Asia/Calcutta')

$utc_date = clone $ist_date;
$utc_date->setTimeZone(new DateTimeZone('UTC'));

echo 'UTC:  ' . $utc_date->format('Y-m-d g:i A');

Java - get the current class name?

The "$1" is not "useless non-sense". If your class is anonymous, a number is appended.

If you don't want the class itself, but its declaring class, then you can use getEnclosingClass(). For example:

Class<?> enclosingClass = getClass().getEnclosingClass();
if (enclosingClass != null) {
} else {

You can move that in some static utility method.

But note that this is not the current class name. The anonymous class is different class than its enclosing class. The case is similar for inner classes.

How can I refresh or reload the JFrame?

just use frame.setVisible(false); frame.setVisible(true); I've had this problem with JLabels with images, and this solved it

How to navigate to a section of a page

Wrap your div with

<a name="sushi">
  <div id="sushi">

and link to it by

<a href="#sushi">Sushi</a>

How to find length of a string array?

Since car has not been initialized, it has no length, its value is null. However, the compiler won't even allow you to compile that code as is, throwing the following error: variable car might not have been initialized.

You need to initialize it first, and then you can use .length:

String car[] = new String[] { "BMW", "Bentley" };

If you need to initialize an empty array, you can use the following:

String car[] = new String[] { }; // or simply String car[] = { };

If you need to initialize it with a specific size, in order to fill certain positions, you can use the following:

String car[] = new String[3]; // initialize a String[] with length 3
System.out.println(car.length); // 3
car[0] = "BMW";
System.out.println(car.length); // 3

However, I'd recommend that you use a List instead, if you intend to add elements to it:

List<String> cars = new ArrayList<String>();
System.out.println(cars.size()); // 0
System.out.println(cars.size()); // 1

How to convert a file into a dictionary?

Simple Option

Most methods for storing a dictionary use JSON, Pickle, or line reading. Providing you're not editing the dictionary outside of Python, this simple method should suffice for even complex dictionaries. Although Pickle will be better for larger dictionaries.

x = {1:'a', 2:'b', 3:'c'}
f = 'file.txt'
print(x, file=open(f,'w'))    # file.txt >>> {1:'a', 2:'b', 3:'c'}
y = eval(open(f,'r').read())
print(x==y)                   # >>> True

Entity Framework The underlying provider failed on Open

For me when that usually starts happening, I have to remote desktop into the service and at the minimum restart IIS. It usually starts popping up right after I deploy code. On a few rare occasions I have had to restart the SQL services and IIS. I wrote a batch script to take a param (1 or 2) and have it setup to either do a restart of IIS ( i.e. 1), or go full nuclear (i.e. 2).

Predict() - Maybe I'm not understanding it

To avoid error, an important point about the new dataset is the name of independent variable. It must be the same as reported in the model. Another way is to nest the two function without creating a new dataset

model <- lm(Coupon ~ Total, data=df)
predict(model, data.frame(Total=c(79037022, 83100656, 104299800)))

Pay attention on the model. The next two commands are similar, but for predict function, the first work the second don't work.

model <- lm(Coupon ~ Total, data=df) #Ok
model <- lm(df$Coupon ~ df$Total) #Ko

Set a border around a StackPanel.

What about this one :

<DockPanel Margin="8">
    <Border CornerRadius="6" BorderBrush="Gray" Background="LightGray" BorderThickness="2" DockPanel.Dock="Top">
        <StackPanel Orientation="Horizontal">
            <TextBlock FontSize="14" Padding="0 0 8 0" HorizontalAlignment="Center" VerticalAlignment="Center">Search:</TextBlock>
            <TextBox x:Name="txtSearchTerm" HorizontalAlignment="Center" VerticalAlignment="Center" />
            <Image Source="lock.png" Width="32" Height="32" HorizontalAlignment="Center" VerticalAlignment="Center" />            
    <StackPanel Orientation="Horizontal" DockPanel.Dock="Bottom" Height="25" />

Could not connect to React Native development server on Android

From the Docs:

Method 2: Connect via Wi-Fi

You can also connect to the development server over Wi-Fi. You'll
first need to install the app on your device using a USB cable, but
once that has been done you can debug wirelessly by following these
instructions. You'll need your development machine's current IP
address before proceeding.

Open a terminal and type /sbin/ifconfig to find your machine's IP address.

  1. Make sure your laptop and your phone are on the same Wi-Fi network.
  2. Open your React Native app on your device.
  3. You'll see a red screen with an error. This is OK. The following steps will fix that.
  4. Open the in-app Developer menu.
  5. Go to Dev Settings ? Debug server host for device.
  6. Type in your machine's IP address and the port of the local dev server (e.g.
  7. Go back to the Developer menu and select Reload JS.

How to tell git to use the correct identity (name and email) for a given project?

You need to use the local set command below:

local set

git config [email protected]
git config 'Mahmoud Zalt'

local get

git config --get
git config --get

The local config file is in the project directory: .git/config.

global set

git config --global [email protected]
git config --global 'Mahmoud Zalt'

global get

git config --global --get
git config --global --get

The global config file in in your home directory: ~/.gitconfig.

Remember to quote blanks, etc, for example: 'FirstName LastName'

Reading numbers from a text file into an array in C

There are two problems in your code:

  • the return value of scanf must be checked
  • the %d conversion does not take overflows into account (blindly applying *10 + newdigit for each consecutive numeric character)

The first value you got (-104204697) is equals to 5623125698541159 modulo 2^32; it is thus the result of an overflow (if int where 64 bits wide, no overflow would happen). The next values are uninitialized (garbage from the stack) and thus unpredictable.

The code you need could be (similar to the answer of BLUEPIXY above, with the illustration how to check the return value of scanf, the number of items successfully matched):

#include <stdio.h>

int main(int argc, char *argv[]) {
    int i, j;
    short unsigned digitArray[16];
    i = 0;
    while (
        i != sizeof(digitArray) / sizeof(digitArray[0])
     && 1 == scanf("%1hu", digitArray + i)
    ) {
    for (j = 0; j != i; j++) {
        printf("%hu\n", digitArray[j]);
    return 0;

"Can't find Project or Library" for standard VBA functions

In my case, it was that the function was AMBIGUOUS as it was defined in the VBA library (present in my references), and also in the Microsoft Office Object Library (also present). I removed the Microsoft Office Object Library, and voila! No need to use the VBA. prefix.

Difference between DOM parentNode and parentElement

Just like with nextSibling and nextElementSibling, just remember that, properties with "element" in their name always returns Element or null. Properties without can return any other kind of node.

console.log(document.body.parentNode, "is body's parent node");    // returns <html>
console.log(document.body.parentElement, "is body's parent element"); // returns <html>

var html = document.body.parentElement;
console.log(html.parentNode, "is html's parent node"); // returns document
console.log(html.parentElement, "is html's parent element"); // returns null

Check whether a cell contains a substring

The following formula determines if the text "CHECK" appears in cell C10. If it does not, the result is blank. If it does, the result is the work "CHECK".


UITableView with fixed section headers

to make UITableView sections header not sticky or sticky:

  1. change the table view's style - make it grouped for not sticky & make it plain for sticky section headers - do not forget: you can do it from storyboard without writing code. (click on your table view and change it is style from the right Side/ component menu)

  2. if you have extra components such as custom views or etc. please check the table view's margins to create appropriate design. (such as height of header for sections & height of cell at index path, sections)

Bootstrap Responsive Text Size

Simplest way is to use dimensions in % or em. Just change the base font size everything will change.


@media (max-width: @screen-xs) {
    body{font-size: 10px;}

@media (max-width: @screen-sm) {
    body{font-size: 14px;}

    font-size: 1.4rem;

Look at all the ways at

You could use viewport units (vh,vw...) but they dont work on Android < 4.4

Create intermediate folders if one doesn't exist

You have to actually call some method to create the directories. Just creating a file object will not create the corresponding file or directory on the file system.

You can use File#mkdirs() method to create the directory: -


Difference between File#mkdir() and File#mkdirs() is that, the later will create any intermediate directory if it does not exist.

Reactjs - Form input validation

Try powerform-react . It is based upon powerform which is a super portable Javascript form library. Once learnt, it can be used in any framework. It works even with vanilla Javascript.

Checkout this simple form that uses powerform-react

There is also a complex example.

Change the image source on rollover using jQuery

A generic solution that doesn't limit you to "this image" and "that image" only may be to add the 'onmouseover' and 'onmouseout' tags to the HTML code itself.


<img src="img1.jpg" onmouseover="swap('img2.jpg')" onmouseout="swap('img1.jpg')" />


function swap(newImg){
  this.src = newImg;

Depending on your setup, maybe something like this would work better (and requires less HTML modification).


<img src="img1.jpg" id="ref1" />
<img src="img3.jpg" id="ref2" />
<img src="img5.jpg" id="ref3" />

JavaScript / jQuery

// Declare Arrays
  imgList = new Array();
  imgList["ref1"] = new Array();
  imgList["ref2"] = new Array();
  imgList["ref3"] = new Array();

//Set values for each mouse state
  imgList["ref1"]["out"] = "img1.jpg";
  imgList["ref1"]["over"] = "img2.jpg";
  imgList["ref2"]["out"] = "img3.jpg";
  imgList["ref2"]["over"] = "img4.jpg";
  imgList["ref3"]["out"] = "img5.jpg";
  imgList["ref3"]["over"] = "img6.jpg";

//Add the swapping functions
    $(this).attr("src", imgList[ $(this).attr("id") ]["over"]);

    $(this).attr("src", imgList[ $(this).attr("id") ]["out"]);

The application may be doing too much work on its main thread

As I did first preferably use SVG images instead of all other types, If not possible compress all of your PNG and JPG resources using some image processing tools such as Adobe Photoshop or Fotosizer. one of the easiest ways is online image compressing tools like this which helped me to decrease all my image files to almost 50% of their initial size.

Why is division in Ruby returning an integer instead of decimal value?

It’s doing integer division. You can make one of the numbers a Float by adding .0:

9.0 / 5  #=> 1.8
9 / 5.0  #=> 1.8

How to position a Bootstrap popover?

If you take a look at bootstrap source codes, you will notice that position can be modified using margin.

So, first you should change popover template to add own css class to not get in conflict with other popovers:

  html: true,
  placement: 'bottom',
  trigger: 'click',
  template: '<div class="popover popover--topright" role="tooltip"><div class="arrow"></div><h3 class="popover-title"></h3><div class="popover-content"></div></div>'

Then using css you can easily shift popover position:

.popover.popover--topright {
  /* margin-top: 0px; // Use to change vertical position */
  margin-right: 40px; /* Use to change horizontal position */
.popover.popover--topright .arrow {
  left: 88% !important; /* fix arrow position */

This solution would not influence other popovers you have. Same solution can be used on tooltips as well because popover class inherit from tooltip class.

Here's a simple jsFiddle

How to loop over a Class attributes in Java?

While I agree with Jörn's answer if your class conforms to the JavaBeabs spec, here is a good alternative if it doesn't and you use Spring.

Spring has a class named ReflectionUtils that offers some very powerful functionality, including doWithFields(class, callback), a visitor-style method that lets you iterate over a classes fields using a callback object like this:

public void analyze(Object obj){
    ReflectionUtils.doWithFields(obj.getClass(), field -> {

        System.out.println("Field name: " + field.getName());
        System.out.println("Field value: "+ field.get(obj));


But here's a warning: the class is labeled as "for internal use only", which is a pity if you ask me

read string from .resx file in C#

The Simplest Way to get value from resource file. Add Resource file in the project. Now get the string where you want to add like in my case it was text block(SilverLight). No need to add any namespace also.Its working fine in my case

txtStatus.Text = Constants.RefractionUpdateMessage;

Constants is my resource file name in the project.Here how my resource file look like

Thymeleaf: Concatenation - Could not parse as expression

We can concat Like this :

<h5 th:text ="${currentItem.first_name}+ ' ' + ${currentItem.last_name}"></h5>

How to get values and keys from HashMap?

Map is internally made up of Map.Entry objects. Each Entry contains key and value. To get key and value from the entry you use accessor and modifier methods.

If you want to get values with given key, use get() method and to insert value, use put() method.

#Define and initialize map;
Map map = new HashMap();

map.get("Germany") // returns 4

If you want to get the set of keys from map, you can use keySet() method

Set keys = map.keySet();
System.out.println("All keys are: " + keys);
// To get all key: value
for(String key: keys){
    System.out.println(key + ": " + map.get(key));

Generally, To get all keys and values from the map, you have to follow the sequence in the following order:

  • Convert Hashmap to MapSet to get set of entries in Map with entryset() method.:
    Set st = map.entrySet();
  • Get the iterator of this set:
    Iterator it = st.iterator();
  • Get Map.Entry from the iterator:
    Map.Entry entry =;
  • use getKey() and getValue() methods of the Map.Entry to get keys and values.
// Now access it
Set st = (Set) map.entrySet();
Iterator it = st.iterator();
    Map.Entry entry =;
    System.out.print(entry.getKey() + " : " + entry.getValue());

In short, use iterator directly in for

for(Map.Entry entry:map.entrySet()){
    System.out.print(entry.getKey() + " : " + entry.getValue());

Bash foreach loop

"foreach" is not the name for bash. It is simply "for". You can do things in one line only like:

for fn in `cat filenames.txt`; do cat "$fn"; done


HTTP Basic Authentication - what's the expected web browser experience?

You can use Postman a plugin for chrome. It gives the ability to choose the authentication type you need for each of the requests. In that menu you can configure user and password. Postman will automatically translate the config to a authentication header that will be sent with your request.

What key in windows registry disables IE connection parameter "Automatically Detect Settings"?

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Control Panel]
"Connection Settings"=dword:00000000
"Connwiz Admin Lock"=dword:00000000

Get the first item from an iterable that matches a condition

I would write this

next(x for x in xrange(10) if x > 3)

How can you print a variable name in python?

Will something like this work for you?

>>> def namestr(**kwargs):
...     for k,v in kwargs.items():
...       print "%s = %s" % (k, repr(v))
>>> namestr(a=1, b=2)
a = 1
b = 2

And in your example:

>>> choice = {'key': 24; 'data': None}
>>> namestr(choice=choice)
choice = {'data': None, 'key': 24}
>>> printvars(**globals())
__builtins__ = <module '__builtin__' (built-in)>
__name__ = '__main__'
__doc__ = None
namestr = <function namestr at 0xb7d8ec34>
choice = {'data': None, 'key': 24}

Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

I have same issue

above this error

Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

I found one more message in my terminal like: "

"Cartalyst\Stripe\Laravel\StripeServiceProvider::class, not found in your ProviderRepository.php"

then i go config/app.php and find


comment it out then run

composer update

it will work fine **In your case maybe package name is different please check your terminal **

Where does mysql store data?

From here:


  1. Locate the my.ini, which store in the MySQL installation folder.

For Example, C:\Program Files\MySQL\MySQL Server 5.1\my.ini

  1. Open the “my.ini” with our favor text editor.
#Path to installation directory. All paths are usually resolved relative to this.
basedir="C:/Program Files/MySQL/MySQL Server 5.1/"
#Path to the database root
datadir="C:/Documents and Settings/All Users/Application Data/MySQL/MySQL Server 5.1/Data/"

Find the “datadir”, this is the where does MySQL stored the data in Windows.


  1. Locate the my.cnf with the find / -name my.cnf command.
yongmo@myserver:~$ find / -name my.cnf
find: /home/lost+found: Permission denied
find: /lost+found: Permission denied
  1. View the my.cnf file like this: cat /etc/mysql/my.cnf
yongmo@myserver:~$ cat /etc/mysql/my.cnf
# The MySQL database server configuration file.
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
# * Basic Settings
user   = mysql
pid-file = /var/run/mysqld/
socket  = /var/run/mysqld/mysqld.sock
port   = 3306
basedir  = /usr
datadir  = /var/lib/mysql
tmpdir  = /tmp
language = /usr/share/mysql/english
  1. Find the “datadir”, this is where does MySQL stored the data in Linux system.

jquery <a> tag click event

That's because your hidden fields have duplicate IDs, so jQuery only returns the first in the set. Give them classes instead, like .uid and grab them via:

var uids = $(".uid").map(function() {
    return this.value;


EDIT: say your output looks like the following (notice, IDs have changed to classes)

<fieldset><legend>John Smith</legend>
<img src='foo.jpg'/><br>
<a href="#" class="aaf">add as friend</a>
<input name="uid" type="hidden" value='<?php echo $row->uid;?>' class="uid">

You can target the 'uid' relative to the clicked anchor like this:

$("a.aaf").click(function() {

Important: do not have any duplicate IDs. They will cause problems. They are invalid, bad and you should not do it.

Get a substring of a char*

You can just use strstr() from <string.h>

$ man strstr

How to update/upgrade a package using pip?

use this code in teminal :

python -m pip install --upgrade PAKAGE_NAME #instead of PAKAGE_NAME 

for example i want update pip pakage :

 python -m pip install --upgrade pip

more example :

python -m pip install --upgrade selenium
python -m pip install --upgrade requests

HTML5 live streaming

You can use a fantastic library name Videojs. You will find more useful informations here. But with quick start you can do something like this:

<link href="//" rel="stylesheet">
<script src="//"></script>
class="video-js vjs-default-skin vjs-big-play-centered" 
data-setup='{"techOrder": ["flash", "html5", "other supported tech"], "nativeControlsForTouch": true, "controlBar": { "muteToggle": false, "volumeControl": false, "timeDivider": false, "durationDisplay": false, "progressControl": false } }'
<source src="rtmp://{domain_server}/{publisher}" type='rtmp/mp4'/>
var player = videojs('Video');;

angularjs make a simple countdown

You should use $scope.$apply() when you execute an angular expression from outside of the angular framework.

function countController($scope){
    $scope.countDown = 10;    
    var timer = setInterval(function(){
    }, 1000);  

How can the size of an input text box be defined in HTML?

You could set its width:

<input type="text" id="text" name="text_name" style="width: 300px;" />

or even better define a class:

<input type="text" id="text" name="text_name" class="mytext" />

and in a separate CSS file apply the necessary styling:

.mytext {
    width: 300px;

If you want to limit the number of characters that the user can type into this textbox you could use the maxlength attribute:

<input type="text" id="text" name="text_name" class="mytext" maxlength="25" />

How to set a session variable when clicking a <a> link

Is your link to another web page? If so, perhaps you could put the variable in the query string and set the session variable when the page being linked to is loaded.

So the link looks like this:

<a href="home.php?variable=value" name="home">home</a>

And the homge page would parse the query string and set the session variable.

Wait until all promises complete even if some rejected

Promise.all with using modern async/await approach

const promise1 = //...
const promise2 = //...

const data = await Promise.all([promise1, promise2])

const dataFromPromise1 = data[0]
const dataFromPromise2 = data[1]

Angular - POST uploaded file

Look at my code, but be aware. I use async/await, because latest Chrome beta can read any es6 code, which gets by TypeScript with compilation. So, you must replace asyns/await by .then().

Input change handler:

 * @param fileInput
public psdTemplateSelectionHandler (fileInput: any){
    let FileList: FileList =;

    for (let i = 0, length = FileList.length; i < length; i++) {

    this.progressBarVisibility = true;

Submit handler:

public async psdTemplateUploadHandler (): Promise<any> {
    let result: any;

    if (!this.psdTemplates.length) {

    this.isSubmitted = true;

        .subscribe(progress => {
            this.uploadProgress = progress;

    try {
        result = await this.fileUploadService.upload(this.uploadRoute, this.psdTemplates);
    } catch (error) {

    if (!result['images']) {


FileUploadService. That service also stored uploading progress in progress$ property, and in other places, you can subscribe on it and get new value every 500ms.

import { Component } from 'angular2/core';
import { Injectable } from 'angular2/core';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/share';

export class FileUploadService {
 * @param Observable<number>
private progress$: Observable<number>;

 * @type {number}
private progress: number = 0;

private progressObserver: any;

constructor () {
    this.progress$ = new Observable(observer => {
        this.progressObserver = observer

 * @returns {Observable<number>}
public getObserver (): Observable<number> {
    return this.progress$;

 * Upload files through XMLHttpRequest
 * @param url
 * @param files
 * @returns {Promise<T>}
public upload (url: string, files: File[]): Promise<any> {
    return new Promise((resolve, reject) => {
        let formData: FormData = new FormData(),
            xhr: XMLHttpRequest = new XMLHttpRequest();

        for (let i = 0; i < files.length; i++) {
            formData.append("uploads[]", files[i], files[i].name);

        xhr.onreadystatechange = () => {
            if (xhr.readyState === 4) {
                if (xhr.status === 200) {
                } else {


        xhr.upload.onprogress = (event) => {
            this.progress = Math.round(event.loaded / * 100);

        };'POST', url, true);

 * Set interval for frequency with which Observable inside Promise will share data with subscribers.
 * @param interval
private static setUploadUpdateInterval (interval: number): void {
    setInterval(() => {}, interval);

How to import an Oracle database from dmp file and log file?

If you are using impdp command example from @sathyajith-bhat response:

impdp <username>/<password> directory=<directoryname> dumpfile=<filename>.dmp logfile=<filename>.log full=y;

you will need to use mandatory parameter directory and create and grant it as:


or use one of defined:

select * from DBA_DIRECTORIES;

My ORACLE Express 11g R2 has default named DATA_PUMP_DIR (located at {inst_dir}\app\oracle/admin/xe/dpdump/) you sill need to grant it for your user.

Python equivalent for HashMap

You need a dict:

my_dict = {'cheese': 'cake'}

Example code (from the docs):

>>> a = dict(one=1, two=2, three=3)
>>> b = {'one': 1, 'two': 2, 'three': 3}
>>> c = dict(zip(['one', 'two', 'three'], [1, 2, 3]))
>>> d = dict([('two', 2), ('one', 1), ('three', 3)])
>>> e = dict({'three': 3, 'one': 1, 'two': 2})
>>> a == b == c == d == e

You can read more about dictionaries here.

Howto: Clean a mysql InnoDB storage engine?

The InnoDB engine does not store deleted data. As you insert and delete rows, unused space is left allocated within the InnoDB storage files. Over time, the overall space will not decrease, but over time the 'deleted and freed' space will be automatically reused by the DB server.

You can further tune and manage the space used by the engine through an manual re-org of the tables. To do this, dump the data in the affected tables using mysqldump, drop the tables, restart the mysql service, and then recreate the tables from the dump files.

How to add java plugin for Firefox on Linux?

Do you want the JDK or the JRE? Anyways, I had this problem too, a few weeks ago. I followed the instructions here and it worked:

NOTE: Before installing Java make sure you kill Firefox.

root@bt:~# killall -9 /opt/firefox/firefox-bin

You can download java from the official website. (Download tar.gz version)

We first create the directory and place java there:

root@bt:~# mkdir /opt/java

root@bt:~# mv -f jre1.7.0_05/ /opt/java/

Final changes.

root@bt:~# update-alternatives --install /usr/bin/java java /opt/java/jre1.7.0_05/bin/java 1

root@bt:~# update-alternatives --set java /opt/java/jre1.7.0_05/bin/java

root@bt:~# export JAVA_HOME="/opt/java/jre1.7.0_05"

Adding the plugin to Firefox.

For Java 7 (32 bit)

root@bt:~# ln -sf $JAVA_HOME/lib/i386/ /usr/lib/mozilla/plugins/

For Java 8 (64 bit)

root@bt:~# ln -sf $JAVA_HOME/jre/lib/amd64/ /usr/lib/mozilla/plugins/

Testing the plugin.

root@bt:~# firefox

Git: add vs push vs commit

I find this image very meaningful :

enter image description here

(from : Oliver Steele -My Git Workflow (2008) )

How to set a maximum execution time for a mysql query?

pt_kill has an option for such. But it is on-demand, not continually monitoring. It does what @Rafa suggested. However see --sentinel for a hint of how to come close with cron.

How to convert flat raw disk image to vmdk for virtualbox or vmplayer?

To answer TJJ: But is it also possible to do this without copying the whole file? So, just to somehow create an additional vmdk-metafile, that references the raw dd-image.

Yes, it's possible. Here's how to use a flat disk image in VirtualBox:

First you create an image with dd in the usual way:

dd bs=512 count=60000 if=/dev/zero of=usbdrv.img

Then you can create a file for VirtualBox that references this image:

VBoxManage internalcommands createrawvmdk -filename "usbdrv.vmdk" -rawdisk "usbdrv.img"

You can use this image in VirtualBox as is, but depending on the guest OS it might not be visible immediately. For example, I experimented on using this method with a Windows guest OS and I had to do the following to give it a drive letter:

  • Go to the Control Panel.
  • Go to Administrative Tools.
  • Go to Computer Management.
  • Go to Storage\Disk Management in the left side panel.
  • You'll see your disk here. Create a partition on it and format it. Use FAT for small volumes, FAT32 or NTFS for large volumes.

You might want to access your files on Linux. First dismount it from the guest OS to be sure and remove it from the virtual machine. Now we need to create a virtual device that references the partition.

sfdisk -d usbdrv.img


label: dos
label-id: 0xd367a714
device: usbdrv.img
unit: sectors

usbdrv.img1 : start=          63, size=       48132, type=4

Take note of the start position of the partition: 63. In the command below I used loop4 because it was the first available loop device in my case.

sudo losetup -o $((63*512)) loop4 usbdrv.img
mkdir usbdrv
sudo mount /dev/loop4 usbdrv
ls usbdrv -l


total 0
-rwxr-xr-x. 1 root root 0 Apr  5 17:13 'Test file.txt'


to_string is not a member of std, says g++ (mingw)

If we use a template-light-solution (as shown above) like the following:

namespace std {
    template<typename T>
    std::string to_string(const T &n) {
        std::ostringstream s;
        s << n;
        return s.str();

Unfortunately, we will have problems in some cases. For example, for static const members:


class A

    static const std::size_t x = 10;



    std::cout << std::to_string(x);

And linking:

CMakeFiles/untitled2.dir/a.cpp.o:a.cpp:(.rdata$.refptr._ZN1A1xE[.refptr._ZN1A1xE]+0x0): undefined reference to `A::x'
collect2: error: ld returned 1 exit status

Here is one way to solve the problem (add to the type size_t):

namespace std {
    std::string to_string(size_t n) {
        std::ostringstream s;
        s << n;
        return s.str();


python: create list of tuples from lists

Use the builtin function zip():

In Python 3:

z = list(zip(x,y))

In Python 2:

z = zip(x,y)

Cannot refer to a non-final variable inside an inner class defined in a different method

You can only access final variables from the containing class when using an anonymous class. Therefore you need to declare the variables being used final (which is not an option for you since you are changing lastPrice and price), or don't use an anonymous class.

So your options are to create an actual inner class, in which you can pass in the variables and use them in a normal fashion


There is a quick (and in my opinion ugly) hack for your lastPrice and price variable which is to declare it like so

final double lastPrice[1];
final double price[1];

and in your anonymous class you can set the value like this

price[0] = priceObject.getNextPrice(lastPrice[0]);
lastPrice[0] = price[0];

How to pass arguments to addEventListener listener function?

someVar value should be accessible only in some_function() context, not from listener's. If you like to have it within listener, you must do something like:

                             var newVar = someVar;

and use newVar instead.

The other way is to return someVar value from some_function() for using it further in listener (as a new local var):

var someVar = some_function(someVar);

Get model's fields in Django

As per the django documentation 2.2 you can use:

To get all fields: Model._meta.get_fields()

To get an individual field: Model._meta.get_field('field name')

ex. Session._meta.get_field('expire_date')

UITableView, Separator color where to set?

Now you should be able to do it directly in the IB.

Not sure though, if this was available when the question was posted originally.

enter image description here

How to invoke a Linux shell command from Java

Use ProcessBuilder to separate commands and arguments instead of spaces. This should work regardless of shell used:

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

public class Test {

    public static void main(final String[] args) throws IOException, InterruptedException {
        //Build command 
        List<String> commands = new ArrayList<String>();
        //Add arguments

        //Run macro on target
        ProcessBuilder pb = new ProcessBuilder(commands); File("/home/narek"));
        Process process = pb.start();

        //Read output
        StringBuilder out = new StringBuilder();
        BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream()));
        String line = null, previous = null;
        while ((line = br.readLine()) != null)
            if (!line.equals(previous)) {
                previous = line;

        //Check result
        if (process.waitFor() == 0) {

        //Abnormal termination: Log command parameters and output and throw ExecutionException

Programmatically set TextBlock Foreground Color

Foreground needs a Brush, so you can use

textBlock.Foreground = Brushes.Navy;

If you want to use the color from RGB or ARGB then

textBlock.Foreground = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromArgb(100, 255, 125, 35)); 


textBlock.Foreground = new System.Windows.Media.SolidColorBrush(Colors.Navy); 

To get the Color from Hex

textBlock.Foreground = new System.Windows.Media.SolidColorBrush((Color)ColorConverter.ConvertFromString("#FFDFD991")); 

HTML: How to make a submit button with text + image in it?

Please refer to this link. You can have any button you want just use javascript to submit the form

Create a nonclustered non-unique index within the CREATE TABLE statement with SQL Server

It's a separate statement.

It's also not possible to insert into a table and select from it and build an index in the same statement either.

The BOL entry contains the information you need:

Indicate that a clustered or a nonclustered index is created for the PRIMARY KEY or UNIQUE constraint. PRIMARY KEY constraints default to CLUSTERED, and UNIQUE constraints default to NONCLUSTERED.

In a CREATE TABLE statement, CLUSTERED can be specified for only one constraint. If CLUSTERED is specified for a UNIQUE constraint and a PRIMARY KEY constraint is also specified, the PRIMARY KEY defaults to NONCLUSTERED.

You can create an index on a PK field, but not a non-clustered index on a non-pk non-unique-constrained field.

A NCL index is not relevant to the structure of the table, and is not a constraint on the data inside the table. It's a separate entity that supports the table but is not integral to it's functionality or design.

That's why it's a separate statement. The NCL index is irrelevant to the table from a design perspective (query optimization notwithstanding).

Java Error: illegal start of expression


public static int[] locations={1,2,3};

outside of the main method.

How to generate the whole database script in MySQL Workbench?

Surprisingly the Data Export in the MySql Workbench is not just for data, in fact it is ideal for generating SQL scripts for the whole database (including views, stored procedures and functions) with just a few clicks. If you want just the scripts and no data simply select the "Skip table data" option. It can generate separate files or a self contained file. Here are more details about the feature:

What is difference between INNER join and OUTER join

Inner join - An inner join using either of the equivalent queries gives the intersection of the two tables, i.e. the two rows they have in common.
Left outer join - A left outer join will give all rows in A, plus any common rows in B.
Full outer join - A full outer join will give you the union of A and B, i.e. All the rows in A and all the rows in B. If something in A doesn't have a corresponding datum in B, then the B portion is null, and vice versa. check this

Converting json results to a date

You need to extract the number from the string, and pass it into the Date constructor:

var x = [{
    "id": 1,
    "start": "\/Date(1238540400000)\/"
}, {
    "id": 2,
    "start": "\/Date(1238626800000)\/"

var myDate = new Date(x[0].start.match(/\d+/)[0] * 1);

The parts are:

x[0].start                                - get the string from the JSON
x[0].start.match(/\d+/)[0]                - extract the numeric part
x[0].start.match(/\d+/)[0] * 1            - convert it to a numeric type
new Date(x[0].start.match(/\d+/)[0] * 1)) - Create a date object

MYSQL into outfile "access denied" - but my user has "ALL" access.. and the folder is CHMOD 777

As @fijaaron says,

  1. GRANT ALL does not imply GRANT FILE
  2. GRANT FILE only works with *.*

So do

GRANT FILE ON *.* TO user;

How to resolve "could not execute statement; SQL [n/a]; constraint [numbering];"?

In my case, this happens when I try to save an object in hibernate or other orm-mapping with null property which can not be null in database table. This happens when you try to save an object, but the save action doesn't comply with the contraints of the table.

How do you change the launcher logo of an app in Android Studio?

In the manifest file, under the tag, there will be a similar line:


Place the launcher icon you want in drawable folder and write its resource path.

2D character array initialization in C

How to create an array size 5 containing pointers to characters:

char *array_of_pointers[ 5 ];        //array size 5 containing pointers to char
char m = 'm';                        //character value holding the value 'm'
array_of_pointers[0] = &m;           //assign m ptr into the array position 0.
printf("%c", *array_of_pointers[0]); //get the value of the pointer to m

How to create a pointer to an array of characters:

char (*pointer_to_array)[ 5 ];        //A pointer to an array containing 5 chars
char m = 'm';                         //character value holding the value 'm'
*pointer_to_array[0] = m;             //dereference array and put m in position 0
printf("%c", (*pointer_to_array)[0]); //dereference array and get position 0

How to create an 2D array containing pointers to characters:

char *array_of_pointers[5][2];          
//An array size 5 containing arrays size 2 containing pointers to char

char m = 'm';                           
//character value holding the value 'm'

array_of_pointers[4][1] = &m;           
//Get position 4 of array, then get position 1, then put m ptr in there.

printf("%c", *array_of_pointers[4][1]); 
//Get position 4 of array, then get position 1 and dereference it.

How to create a pointer to an 2D array of characters:

char (*pointer_to_array)[5][2];
//A pointer to an array size 5 each containing arrays size 2 which hold chars

char m = 'm';                            
//character value holding the value 'm'

(*pointer_to_array)[4][1] = m;           
//dereference array, Get position 4, get position 1, put m there.

printf("%c", (*pointer_to_array)[4][1]); 
//dereference array, Get position 4, get position 1

To help you out with understanding how humans should read complex C/C++ declarations read this:

How to install a Mac application using Terminal

To disable inputting password:

sudo visudo

Then add a new line like below and save then:

# The user can run installer as root without inputting password
yourusername ALL=(root) NOPASSWD: /usr/sbin/installer

Then you run installer without password:

sudo installer -pkg ...

What is VanillaJS?

The plain and simple answer is yes, VanillaJS === JavaScript, as prescribed by Dr B. Eich.

Conda: Installing / upgrading directly from github

The answers are outdated. You simply have to conda install pip and git. Then you can use pip normally:

  1. Activate your conda environment source activate myenv

  2. conda install git pip

  3. pip install git+git://

Create an Array of Arraylists

This works, array of ArrayList. Give it a try to understand how it works.

import java.util.*;

public class ArrayOfArrayList {
    public static void main(String[] args) {

        // Put the length of the array you need
        ArrayList<String>[] group = new ArrayList[15];
        for (int x = 0; x < group.length; x++) {
            group[x] = new ArrayList<>();

        //Add some thing to first array

        //Add some thing to Secondarray
        group[1].add("In here");

        //Try to output 'em

Credits to Kelvincer for some of codes.

Sort tuples based on second parameter

And if you are using python 3.X, you may apply the sorted function on the mylist. This is just an addition to the answer that @Sven Marnach has given above.

# using *sort method*
mylist.sort(lambda x: x[1]) 

# using *sorted function*
sorted(mylist, key = lambda x: x[1]) 

JavaScript Form Submit - Confirm or Cancel Submission Dialog Box

Simple and easy :

<form onSubmit="return confirm('Do you want to submit?') ">_x000D_
  <input type="submit" />_x000D_

How can I indent multiple lines in Xcode?

? + [ and ? + ] are the equivalents to shift+tab in Xcode.

Maven Could not resolve dependencies, artifacts could not be resolved

As an alternative source to the same problem, this answer cites using Maven 3 versus Maven 2 as the potential cause of this issue. Near as I can tell, this is due to changes in local repository resolution that was changed in Maven 3. Putting this here in case anyone else googles for it and reaches this answer (as I did).

How do I change the figure size with subplots?

Alternatively, create a figure() object using the figsize argument and then use add_subplot to add your subplots. E.g.

import matplotlib.pyplot as plt
import numpy as np

f = plt.figure(figsize=(10,3))
ax = f.add_subplot(121)
ax2 = f.add_subplot(122)
x = np.linspace(0,4,1000)
ax.plot(x, np.sin(x))
ax2.plot(x, np.cos(x), 'r:')

Simple Example

Benefits of this method are that the syntax is closer to calls of subplot() instead of subplots(). E.g. subplots doesn't seem to support using a GridSpec for controlling the spacing of the subplots, but both subplot() and add_subplot() do.

How to make <div> fill <td> height

Really have to do this with JS. Here's a solution. I didn't use your class names, but I called the div within the td class name of "full-height" :-) Used jQuery, obviously. Note this was called from jQuery(document).ready(function(){ setFullHeights();}); Also note if you have images, you are going to have to iterate through them first with something like:

function loadedFullHeights(){
var imgCount = jQuery(".full-height").find("img").length;
    return setFullHeights();
var loaded = 0;
    if(loaded ===imgCount){


And you would want to call the loadedFullHeights() from docReady instead. This is actually what I ended up using just in case. Got to think ahead you know!

function setFullHeights(){
var par;
var height;
var $ = jQuery;
var heights=[];
var i = 0;
    par =$(this).parent();
    height = $(par).height();
    var tPad = Number($(par).css('padding-top').replace('px',''));
    var bPad = Number($(par).css('padding-bottom').replace('px',''));
    height -= tPad+bPad;
for(ii in heights){
    $(".full-height").eq(ii).css('height', heights[ii]+'px');


Unable to compile class for JSP: The type java.util.Map$Entry cannot be resolved. It is indirectly referenced from required .class files

From the JIRA knowledge base:


Workflow actions may be inaccessible

  1. JIRA may throw exceptions on screen
  2. One or both of the following conditions may exist:

The following appears in the atlassian-jira.log:

     2007-12-06 10:55:05,327 http-8080-Processor20 ERROR [500ErrorPage] 
     Exception caught in500 page Unable to compile class for JSP
    org.apache.jasper.JasperException: Unable to compile class for JSP
   at org.apache.jasper.JspCompilationContext.compile(
   at org.apache.jasper.servlet.JspServletWrapper.service(



The Tomcat container caches .java and .class files generated by the JSP parser they are used by the web application. Sometimes these get corrupted or cannot be found. This may occur after a patch or upgrade that contains modifications to JSPs.


1.Delete the contents of the /work folder if using standalone JIRA or /work if using EAR/WAR installation . 2. Verify the user running the JIRA application process has Read/Write permission to the /work directory. 3. Restart the JIRA application container to rebuild the files.

Bash: infinite sleep (infinite blocking)

TL;DR: sleep infinity actually sleeps the maximum time allowed, which is finite.

Wondering why this is not documented anywhere, I bothered to read the sources from GNU coreutils and I found it executes roughly what follows:

  1. Use strtod from C stdlib on the first argument to convert 'infinity' to a double precision value. So, assuming IEEE 754 double precision the 64-bit positive infinity value is stored in the seconds variable.
  2. Invoke xnanosleep(seconds) (found in gnulib), this in turn invokes dtotimespec(seconds) (also in gnulib) to convert from double to struct timespec.
  3. struct timespec is just a pair of numbers: integer part (in seconds) and fractional part (in nanoseconds). Naïvely converting positive infinity to integer would result in undefined behaviour (see § from C standard), so instead it truncates to TYPE_MAXIMUM(time_t).
  4. The actual value of TYPE_MAXIMUM(time_t) is not set in the standard (even sizeof(time_t) isn't); so, for the sake of example let's pick x86-64 from a recent Linux kernel.

This is TIME_T_MAX in the Linux kernel, which is defined (time.h) as:

(time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)

Note that time_t is __kernel_time_t and time_t is long; the LP64 data model is used, so sizeof(long) is 8 (64 bits).

Which results in: TIME_T_MAX = 9223372036854775807.

That is: sleep infinite results in an actual sleep time of 9223372036854775807 seconds (10^11 years). And for 32-bit linux systems (sizeof(long) is 4 (32 bits)): 2147483647 seconds (68 years; see also year 2038 problem).

Edit: apparently the nanoseconds function called is not directly the syscall, but an OS-dependent wrapper (also defined in gnulib).

There's an extra step as a result: for some systems where HAVE_BUG_BIG_NANOSLEEP is true the sleep is truncated to 24 days and then called in a loop. This is the case for some (or all?) Linux distros. Note that this wrapper may be not used if a configure-time test succeeds (source).

In particular, that would be 24 * 24 * 60 * 60 = 2073600 seconds (plus 999999999 nanoseconds); but this is called in a loop in order to respect the specified total sleep time. Therefore the previous conclusions remain valid.

In conclusion, the resulting sleep time is not infinite but high enough for all practical purposes, even if the resulting actual time lapse is not portable; that depends on the OS and architecture.

To answer the original question, this is obviously good enough but if for some reason (a very resource-constrained system) you really want to avoid an useless extra countdown timer, I guess the most correct alternative is to use the cat method described in other answers.

Edit: recent GNU coreutils versions will try to use the pause syscall (if available) instead of looping. The previous argument is no longer valid when targeting these newer versions in Linux (and possibly BSD).


This is an important valid concern:

  • sleep infinity is a GNU coreutils extension not contemplated in POSIX. GNU's implementation also supports a "fancy" syntax for time durations, like sleep 1h 5.2s while POSIX only allows a positive integer (e.g. sleep 0.5 is not allowed).
  • Some compatible implementations: GNU coreutils, FreeBSD (at least from version 8.2?), Busybox (requires to be compiled with options FANCY_SLEEP and FLOAT_DURATION).
  • The strtod behaviour is C and POSIX compatible (i.e. strtod("infinity", 0) is always valid in C99-conformant implementations, see §

How to set 'X-Frame-Options' on iframe?

For this purpose you need to match the location in your apache or any other service you are using

If you are using apache then in httpd.conf file.

  <LocationMatch "/your_relative_path">
      ProxyPass absolute_path_of_your_application/your_relative_path
      ProxyPassReverse absolute_path_of_your_application/your_relative_path

Show hide fragment in android

Hi you do it by using this approach, all fragments will remain in the container once added initially and then we are simply revealing the desired fragment and hiding the others within the container.

// Within an activity
private FragmentA fragmentA;
private FragmentB fragmentB;
private FragmentC fragmentC;

protected void onCreate(Bundle savedInstanceState) {
    if (savedInstanceState == null) {
        fragmentA = FragmentA.newInstance("foo");
        fragmentB = FragmentB.newInstance("bar");
        fragmentC = FragmentC.newInstance("baz");

// Replace the switch method
protected void displayFragmentA() {
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    if (fragmentA.isAdded()) { // if the fragment is already in container;
    } else { // fragment needs to be added to frame container
        ft.add(, fragmentA, "A");
    // Hide fragment B
    if (fragmentB.isAdded()) { ft.hide(fragmentB); }
    // Hide fragment C
    if (fragmentC.isAdded()) { ft.hide(fragmentC); }
    // Commit changes

Please see for more info. I hope I get to help anyone. Even if it this is an old question.

How do I grab an INI value within a shell script?

one of more possible solutions

dbver=$(sed -n 's/.*database_version *= *\([^ ]*.*\)/\1/p' < parameters.ini)
echo $dbver


There's no need for "else" in this case:

IF EXISTS(SELECT *  FROM  table1  WHERE Name='John' ) return 1
return 0

Python: How to keep repeating a program until a specific input is obtained?

There are two ways to do this. First is like this:

while True:             # Loop continuously
    inp = raw_input()   # Get the input
    if inp == "":       # If it is a blank line...
        break           # ...break the loop

The second is like this:

inp = raw_input()       # Get the input
while inp != "":        # Loop until it is a blank line
    inp = raw_input()   # Get the input again

Note that if you are on Python 3.x, you will need to replace raw_input with input.

How to import existing Git repository into another?

I was in a situation where I was looking for -s theirs but of course, this strategy doesn't exist. My history was that I had forked a project on GitHub, and now for some reason, my local master could not be merged with upstream/master although I had made no local changes to this branch. (Really don't know what happened there -- I guess upstream had done some dirty pushes behind the scenes, maybe?)

What I ended up doing was

# as per
git fetch upstream
git checkout master
git merge upstream/master
# Lots of conflicts, ended up just abandonging this approach
git reset --hard   # Ditch failed merge
git checkout upstream/master
# Now in detached state
git branch -d master # !
git checkout -b master   # create new master from upstream/master

So now my master is again in sync with upstream/master (and you could repeat the above for any other branch you also want to sync similarly).

Check if a key exists inside a json object

Try this,



the JS Object thisSession should be like

amt: "10.00",
email: "[email protected]",
merchant_id: "sam",
mobileNo: "9874563210",
orderID: "123456",
passkey: "1234"

you can find the details here

Convert UTF-8 with BOM to UTF-8 with no BOM in Python

Simply use the "utf-8-sig" codec:

fp = open("file.txt")
s =
u = s.decode("utf-8-sig")

That gives you a unicode string without the BOM. You can then use

s = u.encode("utf-8")

to get a normal UTF-8 encoded string back in s. If your files are big, then you should avoid reading them all into memory. The BOM is simply three bytes at the beginning of the file, so you can use this code to strip them out of the file:

import os, sys, codecs

BUFSIZE = 4096
BOMLEN = len(codecs.BOM_UTF8)

path = sys.argv[1]
with open(path, "r+b") as fp:
    chunk =
    if chunk.startswith(codecs.BOM_UTF8):
        i = 0
        chunk = chunk[BOMLEN:]
        while chunk:
            i += len(chunk)
  , os.SEEK_CUR)
            chunk =, os.SEEK_CUR)

It opens the file, reads a chunk, and writes it out to the file 3 bytes earlier than where it read it. The file is rewritten in-place. As easier solution is to write the shorter file to a new file like newtover's answer. That would be simpler, but use twice the disk space for a short period.

As for guessing the encoding, then you can just loop through the encoding from most to least specific:

def decode(s):
    for encoding in "utf-8-sig", "utf-16":
            return s.decode(encoding)
        except UnicodeDecodeError:
    return s.decode("latin-1") # will always work

An UTF-16 encoded file wont decode as UTF-8, so we try with UTF-8 first. If that fails, then we try with UTF-16. Finally, we use Latin-1 — this will always work since all 256 bytes are legal values in Latin-1. You may want to return None instead in this case since it's really a fallback and your code might want to handle this more carefully (if it can).

How can I show current location on a Google Map on Android Marshmallow?

Firstly make sure your API Key is valid and add this into your manifest <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

Here's my maps activity.. there might be some redundant information in it since it's from a larger project I created.

import android.content.Intent;
import android.content.IntentSender;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;


public class MapsActivity extends FragmentActivity implements
        LocationListener {

    //These variable are initalized here as they need to be used in more than one methid
    private double currentLatitude; //lat of user
    private double currentLongitude; //long of user

    private double latitudeVillageApartmets= 53.385952001750184;
    private double longitudeVillageApartments= -6.599087119102478;

    public static final String TAG = MapsActivity.class.getSimpleName();

    private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;

    private GoogleMap mMap; // Might be null if Google Play services APK is not available.

    private GoogleApiClient mGoogleApiClient;
    private LocationRequest mLocationRequest;

    protected void onCreate(Bundle savedInstanceState) {

        mGoogleApiClient = new GoogleApiClient.Builder(this)

        // Create the LocationRequest object
        mLocationRequest = LocationRequest.create()
                .setInterval(10 * 1000)        // 10 seconds, in milliseconds
                .setFastestInterval(1 * 1000); // 1 second, in milliseconds
    /*These methods all have to do with the map and wht happens if the activity is paused etc*/
    //contains lat and lon of another marker
    private void setUpMap() {

            MarkerOptions marker = new MarkerOptions().position(new LatLng(latitudeVillageApartmets, longitudeVillageApartments)).title("1"); //create marker
            mMap.addMarker(marker); // adding marker

    //contains your lat and lon
    private void handleNewLocation(Location location) {
        Log.d(TAG, location.toString());

        currentLatitude = location.getLatitude();
        currentLongitude = location.getLongitude();

        LatLng latLng = new LatLng(currentLatitude, currentLongitude);

        MarkerOptions options = new MarkerOptions()
                .title("You are here");
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom((latLng), 11.0F));

    protected void onResume() {

    protected void onPause() {

        if (mGoogleApiClient.isConnected()) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);

    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            // Try to obtain the map from the SupportMapFragment.
            mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(
            // Check if we were successful in obtaining the map.
            if (mMap != null) {


    public void onConnected(Bundle bundle) {
        Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (location == null) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
        else {

    public void onConnectionSuspended(int i) {

    public void onConnectionFailed(ConnectionResult connectionResult) {
        if (connectionResult.hasResolution()) {
            try {
                // Start an Activity that tries to resolve the error
                connectionResult.startResolutionForResult(this, CONNECTION_FAILURE_RESOLUTION_REQUEST);
                 * Thrown if Google Play services canceled the original
                 * PendingIntent
            } catch (IntentSender.SendIntentException e) {
                // Log the error
        } else {
             * If no resolution is available, display a dialog to the
             * user with the error.
            Log.i(TAG, "Location services connection failed with code " + connectionResult.getErrorCode());

    public void onLocationChanged(Location location) {


There's a lot of methods here that are hard to understand but basically all update the map when it's paused etc. There are also connection timeouts etc. Sorry for just posting this, I tried to fix your code but I couldn't figure out what was wrong.

C Macro definition to determine big endian or little endian machine?

Code supporting arbitrary byte orders, ready to be put into a file called order32.h:

#ifndef ORDER32_H
#define ORDER32_H

#include <limits.h>
#include <stdint.h>

#if CHAR_BIT != 8
#error "unsupported char size"

    O32_LITTLE_ENDIAN = 0x03020100ul,
    O32_BIG_ENDIAN = 0x00010203ul,
    O32_PDP_ENDIAN = 0x01000302ul,      /* DEC PDP-11 (aka ENDIAN_LITTLE_WORD) */
    O32_HONEYWELL_ENDIAN = 0x02030001ul /* Honeywell 316 (aka ENDIAN_BIG_WORD) */

static const union { unsigned char bytes[4]; uint32_t value; } o32_host_order =
    { { 0, 1, 2, 3 } };

#define O32_HOST_ORDER (o32_host_order.value)


You would check for little endian systems via


Eclipse java debugging: source not found

In my case, even after Editing source lookup and Adding project, it didn't worked. I configured the Build path of the project.

enter image description here

After that, I selected JRE System Library and it worked.

enter image description here

Strange problem with Subversion - "File already exists" when trying to recreate a directory that USED to be in my repository

The problem is that the checkout takes place on a laptop and in this case subversion can not cope with the off-line synchronization. The problem is reproducable on an other laptop while on a desktop I have no problem checking out the same repository.

I hope this answer wil help you, it took me quite long to find out.

How to restore SQL Server 2014 backup in SQL Server 2008

Please use SQL Server Data Tools from SQL Server Integration Services (Transfer Database Task) as here:

How to remove outliers in boxplot in R?

See ?boxplot for all the help you need.

 outline: if ‘outline’ is not true, the outliers are not drawn (as
          points whereas S+ uses lines).


And for extending the range of the whiskers and suppressing the outliers inside this range:

   range: this determines how far the plot whiskers extend out from the
          box.  If ‘range’ is positive, the whiskers extend to the most
          extreme data point which is no more than ‘range’ times the
          interquartile range from the box. A value of zero causes the
          whiskers to extend to the data extremes.

# change the value of range to change the whisker length

Storing a Key Value Array into a compact JSON string

For use key/value pair in json use an object and don't use array

Find name/value in array is hard but in object is easy


var exObj = {_x000D_
  "mainData": {_x000D_
    "slide0001.html": "Looking Ahead",_x000D_
    "slide0008.html": "Forecast",_x000D_
    "slide0021.html": "Summary",_x000D_
    // another THOUSANDS KEY VALUE PAIRS_x000D_
    // ..._x000D_
  "otherdata" : { "one": "1", "two": "2", "three": "3" }_x000D_
var mainData = exObj.mainData;_x000D_
// for use:_x000D_
  var v = mainData[n];_x000D_
  console.log('name' + i + ': ' + n + ', value' + i + ': ' + v);_x000D_
// and string length is minimum_x000D_

How do I convert an integer to binary in JavaScript?

You can write your own function that returns an array of bits. Example how to convert number to bits

Divisor| Dividend| bits/remainder

2 | 9 | 1

2 | 4 | 0

2 | 2 | 0

~ | 1 |~

example of above line: 2 * 4 = 8 and remainder is 1 so 9 = 1 0 0 1

function numToBit(num){
    var number = num
    var result = []
    while(number >= 1 ){
        number = number/2
    return result

Read remainders from bottom to top. Digit 1 in the middle to top.

Lock screen orientation (Android)

inside the Android manifest file of your project, find the activity declaration of whose you want to fix the orientation and add the following piece of code ,


for landscape orientation and for portrait add the following code,


How do I execute a Shell built-in command with a C function?

You should execute sh -c echo $PWD; generally sh -c will execute shell commands.

(In fact, system(foo) is defined as execl("sh", "sh", "-c", foo, NULL) and thus works for shell built-ins.)

If you just want the value of PWD, use getenv, though.

find all the name using mysql query which start with the letter 'a'

You can use like 'A%' expression, but if you want this query to run fast for large tables I'd recommend you to put number of first button into separate field with tiny int type.

forward declaration of a struct in C?

Try this

#include <stdio.h>

struct context;

struct funcptrs{
  void (*func0)(struct context *ctx);
  void (*func1)(void);

struct context{
    struct funcptrs fps;

void func1 (void) { printf( "1\n" ); }
void func0 (struct context *ctx) { printf( "0\n" ); }

void getContext(struct context *con){
    con->fps.func0 = func0;  
    con->fps.func1 = func1;  

int main(int argc, char *argv[]){
 struct context c;
   c.fps.func0 = func0;
   c.fps.func1 = func1;
   return 0;

Best way to style a TextBox in CSS

your approach is pretty good...

.myclass {_x000D_
    height: 20px;_x000D_
    position: relative;_x000D_
    border: 2px solid #cdcdcd;_x000D_
    border-color: rgba(0, 0, 0, .14);_x000D_
    background-color: AliceBlue;_x000D_
    font-size: 14px;_x000D_
<input type="text" class="myclass" />

How can I reconcile detached HEAD with master/origin?

Get your detached commit onto its own branch

Simply run git checkout -b mynewbranch.

Then run git log, and you'll see that commit is now HEAD on this new branch.

Python: Passing variables between functions

This is what is actually happening:

global_list = []

def defineAList():
    local_list = ['1','2','3']
    print "For checking purposes: in defineAList, list is", local_list 
    return local_list 

def useTheList(passed_list):
    print "For checking purposes: in useTheList, list is", passed_list

def main():
    # returned list is ignored
    returned_list = defineAList()   

    # passed_list inside useTheList is set to global_list


This is what you want:

def defineAList():
    local_list = ['1','2','3']
    print "For checking purposes: in defineAList, list is", local_list 
    return local_list 

def useTheList(passed_list):
    print "For checking purposes: in useTheList, list is", passed_list

def main():
    # returned list is ignored
    returned_list = defineAList()   

    # passed_list inside useTheList is set to what is returned from defineAList


You can even skip the temporary returned_list and pass the returned value directly to useTheList:

def main():
    # passed_list inside useTheList is set to what is returned from defineAList

Creating an empty file in C#

To avoid accidentally overwriting an existing file use:

using (new FileStream(filename, FileMode.CreateNew)) {}

...and handle the IOException which will occur if the file already exists.

File.Create, which is suggested in other answers, will overwrite the contents of the file if it already exists. In simple cases you could mitigate this using File.Exists(). However something more robust is necessary in scenarios where multiple threads and/or processes are attempting to create files in the same folder simultaneously.

How to best display in Terminal a MySQL SELECT returning too many fields?

Using mysql's ego command

From mysql's help command:

ego          (\G) Send command to mysql server, display result vertically.

So by appending a \G to your select, you can get a very clean vertical output:

mysql> SELECT * FROM sometable \G

Using a pager

You can tell MySQL to use the less pager with its -S option that chops wide lines and gives you an output that you can scroll with the arrow keys:

mysql> pager less -S

Thus, next time you run a command with a wide output, MySQL will let you browse the output with the less pager:

mysql> SELECT * FROM sometable;

If you're done with the pager and want to go back to the regular output on stdout, use this:

mysql> nopager

writing to existing workbook using xlwt

The code example is exactly this:

from xlutils.copy import copy
from xlrd import *
w = copy(open_workbook('book1.xls'))

You'll need to create book1.xls to test, but you get the idea.

Connecting to MySQL from Android with JDBC

An other approach is to use a Virtual JDBC Driver that uses a three-tier architecture: your JDBC code is sent through HTTP to a remote Servlet that filters the JDBC code (configuration & security) before passing it to the MySql JDBC Driver. The result is sent you back through HTTP. There are some free software that use this technique. Just Google "Android JDBC Driver over HTTP".

Javascript change color of text and background to input value

Things seems a little confused in the code in your question, so I am going to give you an example of what I think you are try to do.

First considerations are about mixing HTML, Javascript and CSS:

Why is using onClick() in HTML a bad practice?

Unobtrusive Javascript

Inline Styles vs Classes

I will be removing inline content and splitting these into their appropriate files.

Next, I am going to go with the "click" event and displose of the "change" event, as it is not clear that you want or need both.

Your function changeBackground sets both the backround color and the text color to the same value (your text will not be seen), so I am caching the color value as we don't need to look it up in the DOM twice.


#TheForm {
    margin-left: 396px;
#submitColor {
    margin-left: 48px;
    margin-top: 5px;


<form id="TheForm">
    <input id="color" type="text" />
    <input id="submitColor" value="Submit" type="button" />
<span id="coltext">This text should have the same color as you put in the text box</span>


function changeBackground() {
    var color = document.getElementById("color").value; // cached

    // The working function for changing background color.
    document.bgColor = color;

    // The code I'd like to use for changing the text simultaneously - however it does not work.
    document.getElementById("coltext").style.color = color;

document.getElementById("submitColor").addEventListener("click", changeBackground, false);

On jsfiddle

Source: w3schools

Color Values

CSS colors are defined using a hexadecimal (hex) notation for the combination of Red, Green, and Blue color values (RGB). The lowest value that can be given to one of the light sources is 0 (hex 00). The highest value is 255 (hex FF).

Hex values are written as 3 double digit numbers, starting with a # sign.

Update: as pointed out by @Ian

Hex can be either 3 or 6 characters long

Source: W3C

Numerical color values

The format of an RGB value in hexadecimal notation is a ‘#’ immediately followed by either three or six hexadecimal characters. The three-digit RGB notation (#rgb) is converted into six-digit form (#rrggbb) by replicating digits, not by adding zeros. For example, #fb0 expands to #ffbb00. This ensures that white (#ffffff) can be specified with the short notation (#fff) and removes any dependencies on the color depth of the display.

Here is an alternative function that will check that your input is a valid CSS Hex Color, it will set the text color only or throw an alert if it is not valid.

For regex testing, I will use this pattern


but if you were regex matching and wanted to break the numbers into groups then you would require a different pattern

function changeBackground() {
    var color = document.getElementById("color").value.trim(),
        rxValidHex = /^#(?:[0-9a-f]{3}){1,2}$/i;

    if (rxValidHex.test(color)) {
        document.getElementById("coltext").style.color = color;
    } else {
        alert("Invalid CSS Hex Color");

document.getElementById("submitColor").addEventListener("click", changeBackground, false);

On jsfiddle

Here is a further modification that will allow colours by name along with by hex.

function changeBackground() {
    var names = ["AliceBlue", "AntiqueWhite", "Aqua", "Aquamarine", "Azure", "Beige", "Bisque", "Black", "BlanchedAlmond", "Blue", "BlueViolet", "Brown", "BurlyWood", "CadetBlue", "Chartreuse", "Chocolate", "Coral", "CornflowerBlue", "Cornsilk", "Crimson", "Cyan", "DarkBlue", "DarkCyan", "DarkGoldenRod", "DarkGray", "DarkGrey", "DarkGreen", "DarkKhaki", "DarkMagenta", "DarkOliveGreen", "Darkorange", "DarkOrchid", "DarkRed", "DarkSalmon", "DarkSeaGreen", "DarkSlateBlue", "DarkSlateGray", "DarkSlateGrey", "DarkTurquoise", "DarkViolet", "DeepPink", "DeepSkyBlue", "DimGray", "DimGrey", "DodgerBlue", "FireBrick", "FloralWhite", "ForestGreen", "Fuchsia", "Gainsboro", "GhostWhite", "Gold", "GoldenRod", "Gray", "Grey", "Green", "GreenYellow", "HoneyDew", "HotPink", "IndianRed", "Indigo", "Ivory", "Khaki", "Lavender", "LavenderBlush", "LawnGreen", "LemonChiffon", "LightBlue", "LightCoral", "LightCyan", "LightGoldenRodYellow", "LightGray", "LightGrey", "LightGreen", "LightPink", "LightSalmon", "LightSeaGreen", "LightSkyBlue", "LightSlateGray", "LightSlateGrey", "LightSteelBlue", "LightYellow", "Lime", "LimeGreen", "Linen", "Magenta", "Maroon", "MediumAquaMarine", "MediumBlue", "MediumOrchid", "MediumPurple", "MediumSeaGreen", "MediumSlateBlue", "MediumSpringGreen", "MediumTurquoise", "MediumVioletRed", "MidnightBlue", "MintCream", "MistyRose", "Moccasin", "NavajoWhite", "Navy", "OldLace", "Olive", "OliveDrab", "Orange", "OrangeRed", "Orchid", "PaleGoldenRod", "PaleGreen", "PaleTurquoise", "PaleVioletRed", "PapayaWhip", "PeachPuff", "Peru", "Pink", "Plum", "PowderBlue", "Purple", "Red", "RosyBrown", "RoyalBlue", "SaddleBrown", "Salmon", "SandyBrown", "SeaGreen", "SeaShell", "Sienna", "Silver", "SkyBlue", "SlateBlue", "SlateGray", "SlateGrey", "Snow", "SpringGreen", "SteelBlue", "Tan", "Teal", "Thistle", "Tomato", "Turquoise", "Violet", "Wheat", "White", "WhiteSmoke", "Yellow", "YellowGreen"],
        color = document.getElementById("color").value.trim(),
        rxValidHex = /^#(?:[0-9a-f]{3}){1,2}$/i,
        formattedName = color.charAt(0).toUpperCase() + color.slice(1).toLowerCase();

    if (names.indexOf(formattedName) !== -1 || rxValidHex.test(color)) {
        document.getElementById("coltext").style.color = color;
    } else {
        alert("Invalid CSS Color");

document.getElementById("submitColor").addEventListener("click", changeBackground, false);

On jsfiddle

server error:405 - HTTP verb used to access this page is not allowed

Even if you are using IIS or apache, in my guess you are using static html page as a landing page, and by default the web server doesn't allow POST or GET verb on .html page, facebook calls your page via POST/GET verb

the solution would be to rename the page into .php or .aspx and you should be good to go :)

What is best way to start and stop hadoop ecosystem, with command line? & : Used to start and stop hadoop daemons all at once. Issuing it on the master machine will start/stop the daemons on all the nodes of a cluster. Deprecated as you have already noticed., and, : Same as above but start/stop HDFS and YARN daemons separately on all the nodes from the master machine. It is advisable to use these commands now over & namenode/datanode and resourcemanager : To start individual daemons on an individual machine manually. You need to go to a particular node and issue these commands.

Use case : Suppose you have added a new DN to your cluster and you need to start the DN daemon only on this machine,

bin/ start datanode

Note : You should have ssh enabled if you want to start all the daemons on all the nodes from one machine.

Hope this answers your query.

img src SVG changing the styles with CSS

The main problem in your case is that you are importing the svg from an <img> tag which will hide the SVG structure.

You need to use the <svg> tag in conjunction with the <use> to get the desired effect. To make it work, you need to give an id to the path you want to use in the SVG file <path id='myName'...> to then be able to retrieve them from the <use xlink:href="#myName"/> tag. Try the snipped below.

.icon {_x000D_
  display: inline-block;_x000D_
  width: 2em;_x000D_
  height: 2em;_x000D_
  transition: .5s;_x000D_
  fill: currentColor;_x000D_
  stroke-width: 5;_x000D_
  .icon:hover {_x000D_
    fill: rgba(255,255,255,0);_x000D_
    stroke: black;_x000D_
    stroke-width: 2;_x000D_
.red {_x000D_
  color: red;_x000D_
.blue {_x000D_
  color: blue;_x000D_
<svg width="0" height="0">_x000D_
    <path id="home" d="M100 59.375l-18.75-18.75v-28.125h-12.5v15.625l-18.75-18.75-50 50v3.125h12.5v31.25h31.25v-18.75h12.5v18.75h31.25v-31.25h12.5z"/>_x000D_
  <span class="icon red">_x000D_
          <svg viewbox="0 0 100 100">_x000D_
            <use xlink:href="#home"/>_x000D_
    <span class="icon blue">_x000D_
          <svg viewbox="0 0 100 100">_x000D_
            <use xlink:href="#home"/>_x000D_

Note that you can put any URL before the fragment # if you want to load the SVG from an external source (and not embed it into your HTML). Also, usually you do not specify the fill into the CSS. It's better to consider using fill:"currentColor" within the SVG itself. The corresponding element's CSS color value will then be used in place.

What do $? $0 $1 $2 mean in shell script?

These are positional arguments of the script.


./ Hello World

Will make

$0 = ./
$1 = Hello
$2 = World


If you execute ./, $0 will give output ./ but if you execute it with bash it will give output

pretty-print JSON using JavaScript

If you're looking for a nice library to prettify json on a web page...

Prism.js is pretty good.

I found using JSON.stringify(obj, undefined, 2) to get the indentation, and then using prism to add a theme was a good approach.

If you're loading in JSON via an ajax call, then you can run one of Prism's utility methods to prettify

For example:


Send POST request with JSON data using Volley

I know that this thread is quite old, but I had this problem and I came up with a cool solution which can be very useful to many because it corrects/extended the Volley library on many aspects.

I spotted some not supported-out-of-box Volley features:

  • This JSONObjectRequest is not perfect: you have to expect a JSON at the end (see the Response.Listener<JSONObject>).
  • What about Empty Responses (just with a 200 status)?
  • What do I do if I want directly my POJO from the ResponseListener?

I more or less compiled a lot of solutions in a big generic class in order to have a solution for all the problem I quoted.

  * Created by laurentmeyer on 25/07/15.
 public class GenericRequest<T> extends JsonRequest<T> {

     private final Gson gson = new Gson();
     private final Class<T> clazz;
     private final Map<String, String> headers;
     // Used for request which do not return anything from the server
     private boolean muteRequest = false;

      * Basically, this is the constructor which is called by the others.
      * It allows you to send an object of type A to the server and expect a JSON representing a object of type B.
      * The problem with the #JsonObjectRequest is that you expect a JSON at the end.
      * We can do better than that, we can directly receive our POJO.
      * That's what this class does.
      * @param method:        HTTP Method
      * @param classtype:     Classtype to parse the JSON coming from the server
      * @param url:           url to be called
      * @param requestBody:   The body being sent
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
      * @param headers:       Added headers
     private GenericRequest(int method, Class<T> classtype, String url, String requestBody,
                           Response.Listener<T> listener, Response.ErrorListener errorListener, Map<String, String> headers) {
         super(method, url, requestBody, listener,
         clazz = classtype;
         this.headers = headers;

      * Method to be called if you want to send some objects to your server via body in JSON of the request (with headers and not muted)
      * @param method:        HTTP Method
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param toBeSent:      Object which will be transformed in JSON via Gson and sent to the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
      * @param headers:       Added headers
     public GenericRequest(int method, String url, Class<T> classtype, Object toBeSent,
                           Response.Listener<T> listener, Response.ErrorListener errorListener, Map<String, String> headers) {
         this(method, classtype, url, new Gson().toJson(toBeSent), listener,
                 errorListener, headers);

      * Method to be called if you want to send some objects to your server via body in JSON of the request (without header and not muted)
      * @param method:        HTTP Method
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param toBeSent:      Object which will be transformed in JSON via Gson and sent to the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
     public GenericRequest(int method, String url, Class<T> classtype, Object toBeSent,
                           Response.Listener<T> listener, Response.ErrorListener errorListener) {
         this(method, classtype, url, new Gson().toJson(toBeSent), listener,
                 errorListener, new HashMap<String, String>());

      * Method to be called if you want to send something to the server but not with a JSON, just with a defined String (without header and not muted)
      * @param method:        HTTP Method
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param requestBody:   String to be sent to the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
     public GenericRequest(int method, String url, Class<T> classtype, String requestBody,
                           Response.Listener<T> listener, Response.ErrorListener errorListener) {
         this(method, classtype, url, requestBody, listener,
                 errorListener, new HashMap<String, String>());

      * Method to be called if you want to GET something from the server and receive the POJO directly after the call (no JSON). (Without header)
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
     public GenericRequest(String url, Class<T> classtype, Response.Listener<T> listener, Response.ErrorListener errorListener) {
         this(Request.Method.GET, url, classtype, "", listener, errorListener);

      * Method to be called if you want to GET something from the server and receive the POJO directly after the call (no JSON). (With headers)
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
      * @param headers:       Added headers
     public GenericRequest(String url, Class<T> classtype, Response.Listener<T> listener, Response.ErrorListener errorListener, Map<String, String> headers) {
         this(Request.Method.GET, classtype, url, "", listener, errorListener, headers);

      * Method to be called if you want to send some objects to your server via body in JSON of the request (with headers and muted)
      * @param method:        HTTP Method
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param toBeSent:      Object which will be transformed in JSON via Gson and sent to the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
      * @param headers:       Added headers
      * @param mute:          Muted (put it to true, to make sense)
     public GenericRequest(int method, String url, Class<T> classtype, Object toBeSent,
                           Response.Listener<T> listener, Response.ErrorListener errorListener, Map<String, String> headers, boolean mute) {
         this(method, classtype, url, new Gson().toJson(toBeSent), listener,
                 errorListener, headers);
         this.muteRequest = mute;

      * Method to be called if you want to send some objects to your server via body in JSON of the request (without header and muted)
      * @param method:        HTTP Method
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param toBeSent:      Object which will be transformed in JSON via Gson and sent to the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
      * @param mute:          Muted (put it to true, to make sense)
     public GenericRequest(int method, String url, Class<T> classtype, Object toBeSent,
                           Response.Listener<T> listener, Response.ErrorListener errorListener, boolean mute) {
         this(method, classtype, url, new Gson().toJson(toBeSent), listener,
                 errorListener, new HashMap<String, String>());
         this.muteRequest = mute;


      * Method to be called if you want to send something to the server but not with a JSON, just with a defined String (without header and not muted)
      * @param method:        HTTP Method
      * @param url:           URL to be called
      * @param classtype:     Classtype to parse the JSON returned from the server
      * @param requestBody:   String to be sent to the server
      * @param listener:      Listener of the request
      * @param errorListener: Error handler of the request
      * @param mute:          Muted (put it to true, to make sense)
     public GenericRequest(int method, String url, Class<T> classtype, String requestBody,
                           Response.Listener<T> listener, Response.ErrorListener errorListener, boolean mute) {
         this(method, classtype, url, requestBody, listener,
                 errorListener, new HashMap<String, String>());
         this.muteRequest = mute;


     protected Response<T> parseNetworkResponse(NetworkResponse response) {
         // The magic of the mute request happens here
         if (muteRequest) {
             if (response.statusCode >= 200 && response.statusCode <= 299) {
                 // If the status is correct, we return a success but with a null object, because the server didn't return anything
                 return Response.success(null, HttpHeaderParser.parseCacheHeaders(response));
         } else {
             try {
                 // If it's not muted; we just need to create our POJO from the returned JSON and handle correctly the errors
                 String json = new String(, HttpHeaderParser.parseCharset(response.headers));
                 T parsedObject = gson.fromJson(json, clazz);
                 return Response.success(parsedObject, HttpHeaderParser.parseCacheHeaders(response));
             } catch (UnsupportedEncodingException e) {
                 return Response.error(new ParseError(e));
             } catch (JsonSyntaxException e) {
                 return Response.error(new ParseError(e));
         return null;

     public Map<String, String> getHeaders() throws AuthFailureError {
         return headers != null ? headers : super.getHeaders();

     private void configureRequest() {
         // Set retry policy
         // Add headers, for auth for example
         // ...

It could seem a bit overkill but it's pretty cool to have all these constructors because you have all the cases:

(The main constructor wasn't meant to be used directly although it's, of course, possible).

  1. Request with response parsed to POJO / Headers manually set / POJO to Send
  2. Request with response parsed to POJO / POJO to Send
  3. Request with response parsed to POJO / String to Send
  4. Request with response parsed to POJO (GET)
  5. Request with response parsed to POJO (GET) / Headers manually set
  6. Request with no response (200 - Empty Body) / Headers manually set / POJO to Send
  7. Request with no response (200 - Empty Body) / POJO to Send
  8. Request with no response (200 - Empty Body) / String to Send

Of course, in order that it works, you have to have Google's GSON Lib; just add:

compile ''

to your dependencies (current version is 2.3.1).

Horizontal scroll on overflow of table

I think your overflow should be on the outer container. You can also explicitly set a min width for the columns. Like this:

.search-table-outter { overflow-x: scroll; }
th, td { min-width: 200px; }


How to secure phpMyAdmin

Most likely, somewhere on your webserver will be an Alias directive like this;

Alias /phpmyadmin "c:/wamp/apps/phpmyadmin3.1.3.1/"

In my wampserver / localhost setup, it was in c:/wamp/alias/phpmyadmin.conf.

Just change the alias directive and you should be good to go.

Reduce size of legend area in barplot

The cex parameter will do that for you.

a <- c(3, 2, 2, 2, 1, 2 )
barplot(a, beside = T,
        col = 1:6, space = c(0, 2))
       legend = c("a", "b", "c", "d", "e", "f"), 
       fill = 1:6, ncol = 2,
       cex = 0.75)

The plot

How do I check if a C++ string is an int?

Ok, the way I see it you have 3 options.

1: If you simply wish to check whether the number is an integer, and don't care about converting it, but simply wish to keep it as a string and don't care about potential overflows, checking whether it matches a regex for an integer would be ideal here.

2: You can use boost::lexical_cast and then catch a potential boost::bad_lexical_cast exception to see if the conversion failed. This would work well if you can use boost and if failing the conversion is an exceptional condition.

3: Roll your own function similar to lexical_cast that checks the conversion and returns true/false depending on whether it's successful or not. This would work in case 1 & 2 doesn't fit your requirements.

Viewing all `git diffs` with vimdiff

You can try git difftool, it is designed to do this stuff.

First, you need to config diff tool to vimdiff

git config diff.tool vimdiff

Then, when you want to diff, just use git difftool instead of git diff. It will work as you expect.

Show default value in Spinner in android

I found a solution by extending ArrayAdapter and Overriding the getView method.

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;

 * A SpinnerAdapter which does not show the value of the initial selection initially,
 * but an initialText.
 * To use the spinner with initial selection instead call notifyDataSetChanged().
public class SpinnerAdapterWithInitialText<T> extends ArrayAdapter<T> {

    private Context context;
    private int resource;

    private boolean initialTextWasShown = false;
    private String initialText = "Please select";

     * Constructor
     * @param context The current context.
     * @param resource The resource ID for a layout file containing a TextView to use when
     *                 instantiating views.
     * @param objects The objects to represent in the ListView.
    public SpinnerAdapterWithInitialText(@NonNull Context context, int resource, @NonNull T[] objects) {
        super(context, resource, objects);
        this.context = context;
        this.resource = resource;

     * Returns whether the user has selected a spinner item, or if still the initial text is shown.
     * @param spinner The spinner the SpinnerAdapterWithInitialText is assigned to.
     * @return true if the user has selected a spinner item, false if not.
    public boolean selectionMade(Spinner spinner) {
        return !((TextView)spinner.getSelectedView()).getText().toString().equals(initialText);

     * Returns a TextView with the initialText the first time getView is called.
     * So the Spinner has an initialText which does not represent the selected item.
     * To use the spinner with initial selection instead call notifyDataSetChanged(),
     * after assigning the SpinnerAdapterWithInitialText.
    public View getView(int position, View recycle, ViewGroup container) {
        if(initialTextWasShown) {
            return super.getView(position, recycle, container);
        } else {
            initialTextWasShown = true;
            LayoutInflater inflater = LayoutInflater.from(context);
            final View view = inflater.inflate(resource, container, false);

            ((TextView) view).setText(initialText);

            return view;

What Android does when initialising the Spinner, is calling getView for the selected item before calling getView for all items in T[] objects. The SpinnerAdapterWithInitialText returns a TextView with the initialText, the first time it is called. All the other times it calls super.getView which is the getView method of ArrayAdapter which is called if you are using the Spinner normally.

To find out whether the user has selected a spinner item, or if the spinner still displays the initialText, call selectionMade and hand over the spinner the adapter is assigned to.

Fetch: POST json data

After spending some times, reverse engineering jsFiddle, trying to generate payload - there is an effect.

Please take eye (care) on line return response.json(); where response is not a response - it is promise.

var json = {
    json: JSON.stringify({
        a: 1,
        b: 2
    delay: 3

fetch('/echo/json/', {
    method: 'post',
    headers: {
        'Accept': 'application/json, text/plain, */*',
        'Content-Type': 'application/json'
    body: 'json=' + encodeURIComponent(JSON.stringify(json.json)) + '&delay=' + json.delay
.then(function (response) {
    return response.json();
.then(function (result) {
.catch (function (error) {
    console.log('Request failed', error);

jsFiddle: && Firefox > 39 && Chrome > 42

Remove a prefix from a string

I don't know about "standard way".

def remove_prefix(text, prefix):
    if text.startswith(prefix):
        return text[len(prefix):]
    return text  # or whatever

As noted by @Boris and @Stefan, on Python 3.9+ you can use


with the same behavior.

What is the difference between Python's list methods append and extend?

append(): It is basically used in Python to add one element.

Example 1:

>> a = [1, 2, 3, 4]
>> a.append(5)
>> print(a)
>> a = [1, 2, 3, 4, 5]

Example 2:

>> a = [1, 2, 3, 4]
>> a.append([5, 6])
>> print(a)
>> a = [1, 2, 3, 4, [5, 6]]

extend(): Where extend(), is used to merge two lists or insert multiple elements in one list.

Example 1:

>> a = [1, 2, 3, 4]
>> b = [5, 6, 7, 8]
>> a.extend(b)
>> print(a)
>> a = [1, 2, 3, 4, 5, 6, 7, 8]

Example 2:

>> a = [1, 2, 3, 4]
>> a.extend([5, 6])
>> print(a)
>> a = [1, 2, 3, 4, 5, 6]

how to convert milliseconds to date format in android?

try this code might help, modify it suit your needs

SimpleDateFormat format = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
Date d = format.parse(fileDate);

Unzipping files in Python

from zipfile import ZipFile

The directory where you will extract your files doesn't need to exist before, you name it at this moment is the name of the zip if your project is in the same directory. If not, use the PATH i.e : C://....//

Think to escape the / by an other / in the PATH If you have a permission denied try to launch your ide (i.e: Anaconda) as administrator

YOUR_DESTINATION_DIRECTORY will be created in the same directory than your project

how to remove empty strings from list, then remove duplicate values from a list

Amiram's answer is correct, but Distinct() as implemented is an N2 operation; for each item in the list, the algorithm compares it to all the already processed elements, and returns it if it's unique or ignores it if not. We can do better.

A sorted list can be deduped in linear time; if the current element equals the previous element, ignore it, otherwise return it. Sorting is NlogN, so even having to sort the collection, we get some benefit:

public static IEnumerable<T> SortAndDedupe<T>(this IEnumerable<T> input)
   var toDedupe = input.OrderBy(x=>x);

   T prev;
   foreach(var element in toDedupe)
      if(element == prev) continue;

      yield return element;
      prev = element;      

dtList  = dtList.Where(s => !string.IsNullOrWhitespace(s)).SortAndDedupe().ToList();

This returns the same elements; they're just sorted.

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

Run Multiple Batch Files Parallelly

start "systemLogCollector" /min cmd /k call systemLogCollector.bat
start "uiLogCollector" /min cmd /k call uiLogCollector.bat
start "appLogCollector" /min cmd /k call appLogCollector.bat

running-multiple-batch-files Here three batch files are run on separate command windows in a minimized state. If you don't want them minimized, then remove /min. Also, if you don't need to control them later, then you can get rid of the titles. So, a bare-bone command will be- start cmd /k call systemLogCollector.bat

If you want to terminate them-

taskkill /FI "WindowTitle eq appLogCollector*" /T /F
taskkill /FI "WindowTitle eq uiLogCollector*" /T /F
taskkill /FI "WindowTitle eq systemLogCollector*" /T /F

Exporting functions from a DLL with dllexport

I had exactly the same problem, my solution was to use module definition file (.def) instead of __declspec(dllexport) to define exports( I have no idea why this works, but it does

How to reload a page using Angularjs?

You need $route defined in your module and change the JS to this.

$scope.backLinkClick = function () {

that works fine for me.

How to click or tap on a TextView text

To click on a piece of the text (not the whole TextView), you can use Html or Linkify (both create links that open urls, though, not a callback in the app).


Use a string resource like:

<string name="links">Here is a link:</string>

Then in a textview:

TextView textView = ...
Linkify.addLinks(textView, Linkify.ALL);


Using Html.fromHtml:

<string name="html">Here you can put html &lt;a href=""&gt;Link!&lt;/&gt;</string>

Then in your textview:


Hibernate Auto Increment ID

private int id;

and you leave it null (0) when persisting. (null if you use the Integer / Long wrappers)

In some cases the AUTO strategy is resolved to SEQUENCE rathen than to IDENTITY or TABLE, so you might want to manually set it to IDENTITY or TABLE (depending on the underlying database).

It seems SEQUENCE + specifying the sequence name worked for you.

Call child component method from parent class - Angular

user6779899's answer is neat and more generic However, based on the request by Imad El Hitti, a light weight solution is proposed here. This can be used when a child component is tightly connected to one parent only.


export class Notifier {
    valueChanged: (data: number) => void = (d: number) => { };

export class Parent {
    notifyObj = new Notifier();
    tellChild(newValue: number) {
        this.notifyObj.valueChanged(newValue); // inform child


<my-child-comp [notify]="notifyObj"></my-child-comp>


export class ChildComp implements OnInit{
    @Input() notify = new Notifier(); // create object to satisfy typescript
      this.notify.valueChanged = (d: number) => {
            console.log(`Parent has notified changes to ${d}`);
            // do something with the new value 

Batch File: ( was unexpected at this time

Oh, dear. A few little problems...

As pointed out by others, you need to quote to protect against empty/space-containing entries, and use the !delayed_expansion! facility.

Two other matters of which you should be aware:

First, set/p will assign a user-input value to a variable. That's not news - but the gotcha is that pressing enter in response will leave the variable UNCHANGED - it will not ASSIGN a zero-length string to the variable (hence deleting the variable from the environment.) The safe method is:

 set "var="
 set /p var=

That is, of course, if you don't WANT enter to repeat the existing value.
Another useful form is

 set "var=default"
 set /p var=


 set "var=default"
 set /p "var=[%var%]"

(which prompts with the default value; !var! if in a block statement with delayedexpansion)

Second issue is that on some Windows versions (although W7 appears to "fix" this issue) ANY label - including a :: comment (which is a broken-label) will terminate any 'block' - that is, parenthesised compound statement)

VBoxManage: error: Failed to create the host-only adapter

$sudo /Library/StartupItems/VirtualBox/VirtualBox restart

Worked great for me on Mac. This normally happens when I shut down my computer without running

$vagrant suspend

A valid provisioning profile for this executable was not found... (again)

+1 to banging my head against the wall for a day or two...

Also check this setting:

Build Settings -> Code Signing -> Provisioning Profile

After following the above steps, "Automatic" setting worked for me. ~kjm~

Using Alert in Response.Write Function in ASP.NET

You ca also use Response.Write("alert('Error')");

What is polymorphism, what is it for, and how is it used?

What is polymorphism?

Polymorphism is the ability to:

  • Invoke an operation on an instance of a specialized type by only knowing its generalized type while calling the method of the specialized type and not that of the generalized type: it is dynamic polymorphism.

  • Define several methods having the save name but having differents parameters: it is static polymorphism.

The first if the historical definition and the most important.

What is polymorphism used for?

It allows to create strongly-typed consistency of the class hierarchy and to do some magical things like managing lists of objects of differents types without knowing their types but only one of their parent type, as well as data bindings.

Strong and weak typing


Here are some Shapes like Point, Line, Rectangle and Circle having the operation Draw() taking either nothing or either a parameter to set a timeout to erase it.

public class Shape
 public virtual void Draw()
 public virtual void Draw(int timeout)

public class Point : Shape
 int X, Y;
 public override void Draw()

public class Line : Point
 int Xend, Yend;
 public override Draw()

public class Rectangle : Line
 public override Draw()

var shapes = new List<Shape> { new Point(0,0), new Line(0,0,10,10), new rectangle(50,50,100,100) };

foreach ( var shape in shapes )

Here the Shape class and the Shape.Draw() methods should be marked as abstract.

They are not for to make understand.


Without polymorphism, using abstract-virtual-override, while parsing the shapes, it is only the Spahe.Draw() method that is called as the CLR don't know what method to call. So it call the method of the type we act on, and here the type is Shape because of the list declaration. So the code do nothing at all.

With polymorphism, the CLR is able to infer the real type of the object we act on using what is called a virtual table. So it call the good method, and here calling Shape.Draw() if Shape is Point calls the Point.Draw(). So the code draws the shapes.

More readings

C# - Polymorphism (Level 1)

Polymorphism in Java (Level 2)

Polymorphism (C# Programming Guide)

Virtual method table

How do I perform an insert and return inserted identity with Dapper?

There is a great library to make your life easier Dapper.Contrib.Extensions. After including this you can just write:

public int Add(Transaction transaction)
        using (IDbConnection db = Connection)
                return (int)db.Insert(transaction);

Setting size for icon in CSS

You could override the framework CSS (I guess you're using one) and set the size as you want, like this:

.pnx-msg-icon pnx-icon-msg-warning {
    width: 24px !important;
    height: 24px !important;

The "!important" property will make sure your code has priority to the framework's code. Make sure you are overriding the correct property, I don't know how the framework is working, this is just an example of !important usage.

Angular2 If ngModel is used within a form tag, either the name attribute must be set or the form

For me, the solution was very simple. I changed the <form> tag into a <div> and the error goes away.

How to link html pages in same or different folders?

Within the same folder, just use the file name:

<a href="thefile.html">my link</a>

Within the parent folder's directory:

<a href="../thefile.html">my link</a>

Within a sub-directory:

<a href="subdir/thefile.html">my link</a>

How to set Toolbar text and back arrow color

If you use AndroidX (as of July 2019) you may add these:


NOTE! This was tested to work if your Toolbar is placed directly inside AppBarLayout but not inside CollapsingToolbarLayout

Declare global variables in Visual Studio 2010 and VB.NET

Public Class Form1

   Public Shared SomeValue As Integer = 5

End Class

The answer:

MessageBox.Show("this is the number"&GlobalVariables.SomeValue)

PHP - find entry by object property from an array of objects

$arr = [
    'ID' => 1

echo array_search(1, array_column($arr, 'ID')); // prints 0 (!== false)

Above code echoes the index of the matching element, or false if none.

To get the corresponding element, do something like:

$i = array_search(1, array_column($arr, 'ID'));
$element = ($i !== false ? $arr[$i] : null);

array_column works both on an array of arrays, and on an array of objects.

Automate scp file transfer using a shell script

The command scp can be used like a traditional UNIX cp. SO if you do :

scp -r myDirectory/ mylogin@host:TargetDirectory

will work

How can I delete all of my Git stashes at once?

I wanted to keep a few recent stashes, but delete everything else.

Because all stashes get renumbered when you drop one, this is actually easy to do with while. To delete all stashes older than stash@{19}:

while git stash drop 'stash@{20}'; do true; done

Converting an int to std::string

The following macro is not quite as compact as a single-use ostringstream or boost::lexical_cast.

But if you need conversion-to-string repeatedly in your code, this macro is more elegant in use than directly handling stringstreams or explicit casting every time.

It is also very versatile, as it converts everything supported by operator<<(), even in combination.


#include <sstream>

#define SSTR( x ) dynamic_cast< std::ostringstream & >( \
            ( std::ostringstream() << std::dec << x ) ).str()


The std::dec is a side-effect-free way to make the anonymous ostringstream into a generic ostream so operator<<() function lookup works correctly for all types. (You get into trouble otherwise if the first argument is a pointer type.)

The dynamic_cast returns the type back to ostringstream so you can call str() on it.


#include <string>

int main()
    int i = 42;
    std::string s1 = SSTR( i );

    int x = 23;
    std::string s2 = SSTR( "i: " << i << ", x: " << x );
    return 0;

What is CDATA in HTML?

CDATA is a sequence of characters from the document character set and may include character entities. User agents should interpret attribute values as follows: Replace character entities with characters,

Ignore line feeds,

Replace each carriage return or tab with a single space.

JUnit tests pass in Eclipse but fail in Maven Surefire

I had the same problem (JUnit tests failed in Maven Surefire but passed in Eclipse) and managed to solve it by setting forkMode to always in the maven surefire configuration in pom.xml:


Surefire parameters:

Edit (January 2014):

As Peter Perhác pointed out, the forkMode parameter is deprecated since Surefire 2.14. Beginning from Surefire 2.14 use this instead:


For more information see Fork Options and Parallel Test Execution

Understanding Fragment's setRetainInstance(boolean)

First of all, check out my post on retained Fragments. It might help.

Now to answer your questions:

Does the fragment also retain its view state, or will this be recreated on configuration change - what exactly is "retained"?

Yes, the Fragment's state will be retained across the configuration change. Specifically, "retained" means that the fragment will not be destroyed on configuration changes. That is, the Fragment will be retained even if the configuration change causes the underlying Activity to be destroyed.

Will the fragment be destroyed when the user leaves the activity?

Just like Activitys, Fragments may be destroyed by the system when memory resources are low. Whether you have your fragments retain their instance state across configuration changes will have no effect on whether or not the system will destroy the Fragments once you leave the Activity. If you leave the Activity (i.e. by pressing the home button), the Fragments may or may not be destroyed. If you leave the Activity by pressing the back button (thus, calling finish() and effectively destroying the Activity), all of the Activitys attached Fragments will also be destroyed.

Why doesn't it work with fragments on the back stack?

There are probably multiple reasons why it's not supported, but the most obvious reason to me is that the Activity holds a reference to the FragmentManager, and the FragmentManager manages the backstack. That is, no matter if you choose to retain your Fragments or not, the Activity (and thus the FragmentManager's backstack) will be destroyed on a configuration change. Another reason why it might not work is because things might get tricky if both retained fragments and non-retained fragments were allowed to exist on the same backstack.

Which are the use cases where it makes sense to use this method?

Retained fragments can be quite useful for propagating state information — especially thread management — across activity instances. For example, a fragment can serve as a host for an instance of Thread or AsyncTask, managing its operation. See my blog post on this topic for more information.

In general, I would treat it similarly to using onConfigurationChanged with an Activity... don't use it as a bandaid just because you are too lazy to implement/handle an orientation change correctly. Only use it when you need to.


As far as I can tell, both syntaxes are equivalent. The first is SQL standard, the second is MySQL's extension.

So they should be exactly equivalent performance wise. says:

INSERT inserts new rows into an existing table. The INSERT ... VALUES and INSERT ... SET forms of the statement insert rows based on explicitly specified values. The INSERT ... SELECT form inserts rows selected from another table or tables.

Reloading the page gives wrong GET request with AngularJS HTML5 mode

I believe your issue is with regards to the server. The angular documentation with regards to HTML5 mode (at the link in your question) states:

Server side Using this mode requires URL rewriting on server side, basically you have to rewrite all your links to entry point of your application (e.g. index.html)

I believe you'll need to setup a url rewrite from /about to /.

selecting unique values from a column

Use this query to get values

SELECT * FROM `buy` group by date order by date DESC

How to remove an unpushed outgoing commit in Visual Studio?

Assuming you have pushed most recent changes to the server:

  1. Close Visual Studio and delete your local copy of the project
  2. Open Visual Studio, go to Team Explorer tab, click Manage Connections. (plug)
  3. Click the dropdown arrow next to Manage Connections, Connect to a Project
  4. Select the project, confirm the local path, and click the Connect button.

Once you reopen the project both commits and changes should be zero.

How to update multiple columns in single update statement in DB2

This is an "old school solution", when MERGE command does not work (I think before version 10).

SET (T.VAL1, T.VAL2 ) =  
   AND (T.VAL1 <> S.VAL1 OR T.VAL2 <> S.VAL2));

cartesian product in pandas

Use pd.MultiIndex.from_product as an index in an otherwise empty dataframe, then reset its index, and you're done.

a = [1, 2, 3]
b = ["a", "b", "c"]

index = pd.MultiIndex.from_product([a, b], names = ["a", "b"])

pd.DataFrame(index = index).reset_index()


   a  b
0  1  a
1  1  b
2  1  c
3  2  a
4  2  b
5  2  c
6  3  a
7  3  b
8  3  c

Typescript Date Type?

Typescript recognizes the Date interface out of the box - just like you would with a number, string, or custom type. So Just use:

myDate : Date;

How to concatenate strings in twig

{{ ['foo', 'bar'|capitalize]|join }}

As you can see this works with filters and functions without needing to use set on a seperate line.

What are the specific differences between .msi and setup.exe file?

.msi files are windows installer files without the windows installer runtime, setup.exe can be any executable programm (probably one that installs stuff on your computer)

Link vs compile vs controller

this is a good sample for understand directive phases

var app = angular.module('myapp', [])

app.directive('slngStylePrelink', function() {
    return {
        scope: {
            drctvName: '@'
        controller: function($scope) {
            console.log('controller for ', $scope.drctvName);
        compile: function(element, attr) {
            console.log("compile for ",
            return {
                post: function($scope, element, attr) {
                    console.log('post link for ',
                pre: function($scope, element, attr) {
                    $scope.element = element;
                    console.log('pre link for ',
                        // from angular.js 1.4.1
                    function ngStyleWatchAction(newStyles, oldStyles) {
                        if (oldStyles && (newStyles !== oldStyles)) {
                            forEach(oldStyles, function(val, style) {
                                element.css(style, '');
                        if (newStyles) element.css(newStyles);

                    $scope.$watch(attr.slngStylePrelink, ngStyleWatchAction, true);

                    // Run immediately, because the watcher's first run is async


<body ng-app="myapp">
    <div slng-style-prelink="{height:'500px'}" drctv-name='parent' style="border:1px solid" name="parent">
        <div slng-style-prelink="{height:'50%'}" drctv-name='child' style="border:1px solid red" name='child'>

Convert array to JSON string in swift

Swift 3.0 - 4.0 version

do {

    //Convert to Data
    let jsonData = try dictionaryOrArray, options: JSONSerialization.WritingOptions.prettyPrinted)

    //Convert back to string. Usually only do this for debugging
    if let JSONString = String(data: jsonData, encoding: String.Encoding.utf8) {

    //In production, you usually want to try and cast as the root data structure. Here we are casting as a dictionary. If the root object is an array cast as [Any].
    var json = try JSONSerialization.jsonObject(with: jsonData, options: JSONSerialization.ReadingOptions.mutableContainers) as? [String: Any]

} catch {

The JSONSerialization.WritingOptions.prettyPrinted option gives it to the eventual consumer in an easier to read format if they were to print it out in the debugger.

Reference: Apple Documentation

The JSONSerialization.ReadingOptions.mutableContainers option lets you mutate the returned array's and/or dictionaries.

Reference for all ReadingOptions: Apple Documentation

NOTE: Swift 4 has the ability to encode and decode your objects using a new protocol. Here is Apples Documentation, and a quick tutorial for a starting example.

Difference between 'struct' and 'typedef struct' in C++?

There is no difference in C++, but I believe in C it would allow you to declare instances of the struct Foo without explicitly doing:

struct Foo bar;

How to remove the default arrow icon from a dropdown list (select element)?

The previously mentioned solutions work well with chrome but not on Firefox.

I found a Solution that works well both in Chrome and Firefox(not on IE). Add the following attributes to the CSS for your SELECTelement and adjust the margin-top to suit your needs.

select {
    -webkit-appearance: none;
    -moz-appearance: none;
    text-indent: 1px;
    text-overflow: '';

Hope this helps :)

Apache: "AuthType not set!" 500 Error

Alternatively, this solution works with both Apache2 version < 2.4 as well as >= 2.4. Make sure that the "version" module is enabled:

a2enmod version

And then use this code instead:

<IfVersion < 2.4>
    Allow from all
<IfVersion >= 2.4>
    Require all granted

How do I force Internet Explorer to render in Standards Mode and NOT in Quirks?

I know this question was asked over 2 years ago but no one has mentioned this yet.

The best method is to use a http header

Adding the meta tag to the head doesn't always work because IE might have determined the mode before it's read. The best way to make sure IE always uses standards mode is to use a custom http header.


name: X-UA-Compatible  
value: IE=edge

For example in a .NET application you could put this in the web.config file.

        <add name="X-UA-Compatible" value="IE=edge" />

Android Gradle Apache HttpClient does not exist?

I had this problem and then found these pages: Here you can see that apache library is deprecated, but it's not removed, so it should work. It doesn't.


And here you can see how to include apache library to your project


I resolved problem by adding following to my build.gradle file as recommended in second link.

android {
    useLibrary 'org.apache.http.legacy'

However this only works if you are using gradle 1.3.0-beta2 or greater, so you will have to add this to buildscript dependencies if you are on a lower version:

classpath ''

Hope this helps.