Programs & Examples On #Entry point

For questions concerning the "entry point" of an application or library. The entry point is a special function or location in the code where control is passed from the operating system to the program.

sudo: docker-compose: command not found

The output of dpkg -s ... demonstrates that docker-compose is not installed from a package. Without more information from you there are at least two possibilities:

  1. docker-compose simply isn't installed at all, and you need to install it.

    The solution here is simple: install docker-compose.

  2. docker-compose is installed in your $HOME directory (or other location not on root's $PATH).

    There are several solution in this case. The easiest is probably to replace:

    sudo docker-compose ...


    sudo `which docker-compose` ...

    This will call sudo with the full path to docker-compose.

    You could alternatively install docker-compose into a system-wide directory, such as /usr/local/bin.

How to specify the port an ASP.NET Core application is hosted on?

Follow up answer to help anyone doing this with the VS docker integration. I needed to change to port 8080 to run using the "flexible" environment in google appengine.

You'll need the following in your Dockerfile:


and you'll need to modify the port in docker-compose.yml as well:

      - "8080"

Error: Cannot find module 'webpack'

Nothing suggested above worked for me (including the NODE_PATH variable). I created a sym link of "node_modules" from my local folder to the global AppData(eg below) and it worked like charm.

C:\Users\mmoinuddin\AppData\Roaming\npm>mklink /D node_modules c:\essportreact\day1\node_modules
symbolic link created for node_modules <<===>> c:\essportreact\day1\node_modules
Hash: 2a82a67f90f9aa05ab4a
Version: webpack 1.15.0

How To Inject AuthenticationManager using Java Configuration in a Custom Filter

In addition to what Angular University said above you may want to use @Import to aggregate @Configuration classes to the other class (AuthenticationController in my case) :

public class AuthenticationController {
private AuthenticationManager authenticationManager;
//some logic

Spring doc about Aggregating @Configuration classes with @Import: link

The module ".dll" was loaded but the entry-point was not found

I found the answer: I need to add a new application to the service components in my computer and then add the right DLL's.

Thanks! If anyone has the same problem, I'll be happy to help.

ActiveX component can't create object

I had the same issue with Excel, I was trying to use a 32 COM DLL with an Excel 64 bits version and I got this error. I rebuild the COM dll to a 64 bits version and the error disappears. So be sure that your COM dll has the same architecture (x86 vs x64) than your application.

Best way to Format a Double value to 2 Decimal places

An alternative is to use String.format:

double[] arr = { 23.59004,

for ( double dub : arr ) {
  System.out.println( String.format( "%.2f", dub ) );



You could also use System.out.format (same method signature), or create a java.util.Formatter which works in the same way.

What is the use of the JavaScript 'bind' method?

Bind creates a new function that will force the this inside the function to be the parameter passed to bind().

Here's an example that shows how to use bind to pass a member method around that has the correct this:

var myButton = {
  content: 'OK',
  click() {
    console.log(this.content + ' clicked');

var looseClick =;
looseClick(); // not bound, 'this' is not myButton - it is the globalThis

var boundClick =;
boundClick(); // bound, 'this' is myButton

Which prints out:

OK clicked
undefined clicked
OK clicked

You can also add extra parameters after the 1st (this) parameter and bind will pass in those values to the original function. Any additional parameters you later pass to the bound function will be passed in after the bound parameters:

// Example showing binding some parameters
var sum = function(a, b) {
  return a + b;

var add5 = sum.bind(null, 5);

Which prints out:


Check out JavaScript Function bind for more info and interactive examples.

Update: ECMAScript 2015 adds support for => functions. => functions are more compact and do not change the this pointer from their defining scope, so you may not need to use bind() as often. For example, if you wanted a function on Button from the first example to hook up the click callback to a DOM event, the following are all valid ways of doing that:

var myButton = {
  ... // As above
  hookEvent(element) {
    // Use bind() to ensure 'this' is the 'this' inside click()


var myButton = {
  ... // As above
  hookEvent(element) {
    // Use a new variable for 'this' since 'this' inside the function
    // will not be the 'this' inside hookEvent()
    var me = this;
    element.addEventListener('click', function() { });


var myButton = {
  ... // As above
  hookEvent(element) {
    // => functions do not change 'this', so you can use it directly
    element.addEventListener('click', () =>;

Reminder - \r\n or \n\r?

In any .NET langauge, Environment.NewLine would be preferable.

Get DOS path instead of Windows path

use this link, it will automatically convert any path you give to any format

Does delete on a pointer to a subclass call the base class destructor?

You should delete A yourself in the destructor of B.

Floating point comparison functions for C#

From Bruce Dawson's paper on comparing floats, you can also compare floats as integers. Closeness is determined by least significant bits.

public static bool AlmostEqual2sComplement( float a, float b, int maxDeltaBits ) 
    int aInt = BitConverter.ToInt32( BitConverter.GetBytes( a ), 0 );
    if ( aInt <  0 )
        aInt = Int32.MinValue - aInt;  // Int32.MinValue = 0x80000000

    int bInt = BitConverter.ToInt32( BitConverter.GetBytes( b ), 0 );
    if ( bInt < 0 )
        bInt = Int32.MinValue - bInt;

    int intDiff = Math.Abs( aInt - bInt );
    return intDiff <= ( 1 << maxDeltaBits );

EDIT: BitConverter is relatively slow. If you're willing to use unsafe code, then here is a very fast version:

    public static unsafe int FloatToInt32Bits( float f )
        return *( (int*)&f );

    public static bool AlmostEqual2sComplement( float a, float b, int maxDeltaBits )
        int aInt = FloatToInt32Bits( a );
        if ( aInt < 0 )
            aInt = Int32.MinValue - aInt;

        int bInt = FloatToInt32Bits( b );
        if ( bInt < 0 )
            bInt = Int32.MinValue - bInt;

        int intDiff = Math.Abs( aInt - bInt );
        return intDiff <= ( 1 << maxDeltaBits );

How to add a file to the last commit in git?

If you didn't push the update in remote then the simple solution is remove last local commit using following command: git reset HEAD^. Then add all files and commit again.

How do I trim() a string in angularjs?

If you need only display the trimmed value then I'd suggest against manipulating the original string and using a filter instead.

app.filter('trim', function () {
    return function(value) {
        if(!angular.isString(value)) {
            return value;
        return value.replace(/^\s+|\s+$/g, ''); // you could use .trim, but it's not going to work in IE<9

And then

<span>{{ foo | trim }}</span>

Split string with PowerShell and do something with each token

To complement Justus Thane's helpful answer:

  • As Joey notes in a comment, PowerShell has a powerful, regex-based -split operator.

    • In its unary form (-split '...'), -split behaves like awk's default field splitting, which means that:
      • Leading and trailing whitespace is ignored.
      • Any run of whitespace (e.g., multiple adjacent spaces) is treated as a single separator.
  • In PowerShell v4+ an expression-based - and therefore faster - alternative to the ForEach-Object cmdlet became available: the .ForEach() array (collection) method, as described in this blog post (alongside the .Where() method, a more powerful, expression-based alternative to Where-Object).

Here's a solution based on these features:

PS> (-split '   One      for the money   ').ForEach({ "token: [$_]" })
token: [One]
token: [for]
token: [the]
token: [money]

Note that the leading and trailing whitespace was ignored, and that the multiple spaces between One and for were treated as a single separator.

ReferenceError: event is not defined error in Firefox

It is because you forgot to pass in event into the click function:

$('.menuOption').on('click', function (e) { // <-- the "e" for event

    e.preventDefault(); // now it'll work

    var categories = $(this).attr('rel');

On a side note, e is more commonly used as opposed to the word event since Event is a global variable in most browsers.

How to remove all callbacks from a Handler?

In my experience calling this worked great!


In the docs for removeCallbacksAndMessages it says...

Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.

What does %>% function mean in R?

%...% operators

%>% has no builtin meaning but the user (or a package) is free to define operators of the form %whatever% in any way they like. For example, this function will return a string consisting of its left argument followed by a comma and space and then it's right argument.

"%,%" <- function(x, y) paste0(x, ", ", y)

# test run

"Hello" %,% "World"
## [1] "Hello, World"

The base of R provides %*% (matrix mulitiplication), %/% (integer division), %in% (is lhs a component of the rhs?), %o% (outer product) and %x% (kronecker product). It is not clear whether %% falls in this category or not but it represents modulo.

expm The R package, expm, defines a matrix power operator %^%. For an example see Matrix power in R .

operators The operators R package has defined a large number of such operators such as %!in% (for not %in%). See

igraph This package defines %--% , %->% and %<-% to select edges.

lubridate This package defines %m+% and %m-% to add and subtract months and %--% to define an interval. igraph also defines %--% .


magrittr In the case of %>% the magrittr R package has defined it as discussed in the magrittr vignette. See

magittr has also defined a number of other such operators too. See the Additional Pipe Operators section of the prior link which discusses %T>%, %<>% and %$% and for even more details.

dplyr The dplyr R package used to define a %.% operator which is similar; however, it has been deprecated and dplyr now recommends that users use %>% which dplyr imports from magrittr and makes available to the dplyr user. As David Arenburg has mentioned in the comments this SO question discusses the differences between it and magrittr's %>% : Differences between %.% (dplyr) and %>% (magrittr)

pipeR The R package, pipeR, defines a %>>% operator that is similar to magrittr's %>% and can be used as an alternative to it. See

The pipeR package also has defined a number of other such operators too. See:

postlogic The postlogic package defined %if% and %unless% operators.

wrapr The R package, wrapr, defines a dot pipe %.>% that is an explicit version of %>% in that it does not do implicit insertion of arguments but only substitutes explicit uses of dot on the right hand side. This can be considered as another alternative to %>%. See

Bizarro pipe. This is not really a pipe but rather some clever base syntax to work in a way similar to pipes without actually using pipes. It is discussed in The idea is that instead of writing:

1:8 %>% sum %>% sqrt
## [1] 6

one writes the following. In this case we explicitly use dot rather than eliding the dot argument and end each component of the pipeline with an assignment to the variable whose name is dot (.) . We follow that with a semicolon.

1:8 ->.; sum(.) ->.; sqrt(.)
## [1] 6

Update Added info on expm package and simplified example at top. Added postlogic package.

center a row using Bootstrap 3

Simply use text-center class

 <div class="row">
     <div class="col-md-12">
          <h3 class="text-center">Here Comes your Text</h3>

setImmediate vs. nextTick

Use setImmediate if you want to queue the function behind whatever I/O event callbacks that are already in the event queue. Use process.nextTick to effectively queue the function at the head of the event queue so that it executes immediately after the current function completes.

So in a case where you're trying to break up a long running, CPU-bound job using recursion, you would now want to use setImmediate rather than process.nextTick to queue the next iteration as otherwise any I/O event callbacks wouldn't get the chance to run between iterations.

Adding background image to div using CSS

Specify a height and a width:

    background-image: url('../images/header-shade.jpg');
    height: 10px;
    width: 10px;

Install Android App Bundle on device

For MAC:

brew install bundletool
bundletool build-apks --bundle=./app.aab --output=./app.apks
bundletool install-apks --apks=app.apks

SQL Server Express CREATE DATABASE permission denied in database 'master'

After I performed the following instructions in SSMS, everything works fine:

create login [IIS APPPOOL\MyWebAPP] from windows;

exec sp_addsrvrolemember N'IIS APPPOOL\MyWebAPP', sysadmin

How to change the style of alert box?

I use sweetalert2 library. It's really simple, a lot of customization, modern, animated windows, eye-catching, and also nice design.{
  icon: 'error',
  title: 'Oops...',
  text: 'Something went wrong!',
  footer: '<a href>Why do I have this issue?</a>'

Check this link

Staging Deleted files

Even though it's correct to use git rm [FILE], alternatively, you could do git add -u.

According to the git-add documentation:

-u --update

Update the index just where it already has an entry matching [FILE]. This removes as well as modifies index entries to match the working tree, but adds no new files.

If no [FILE] is given when -u option is used, all tracked files in the entire working tree are updated (old versions of Git used to limit the update to the current directory and its subdirectories).

Upon which the index will be refreshed and files will be properly staged.

Git push error: Unable to unlink old (Permission denied)

I think the problem may be with the ownership to the folder so set it to the current user ownership

sudo chown -R your_login_name /path/to/folder
You can find the solution [here][1]

How can you dynamically create variables via a while loop?

Keyword parameters allow you to pass variables from one function to another. In this way you can use the key of a dictionary as a variable name (which can be populated in your while loop). The dictionary name just needs to be preceded by ** when it is called.

# create a dictionary
>>> kwargs = {}
# add a key of name and assign it a value, later we'll use this key as a variable
>>> kwargs['name'] = 'python'

# an example function to use the variable
>>> def print_name(name):
...   print name

# call the example function
>>> print_name(**kwargs)

Without **, kwargs is just a dictionary:

>>> print_name(kwargs)
{'name': 'python'}

How to select following sibling/xml tag using xpath

For completeness - adding to accepted answer above - in case you are interested in any sibling regardless of the element type you can use variation:


Convert List into Comma-Separated String


Console.WriteLine(String.Join(",", new List<uint> { 1, 2, 3, 4, 5 }));

First Parameter: ","
Second Parameter: new List<uint> { 1, 2, 3, 4, 5 })

String.Join will take a list as a the second parameter and join all of the elements using the string passed as the first parameter into one single string.

What are the best PHP input sanitizing functions?

function sanitize($string,$dbmin,$dbmax){
$string = preg_replace('#[^a-z0-9]#i', '', $string); //useful for strict cleanse, alphanumeric here
$string = mysqli_real_escape_string($con, $string); //get ready for db
if(strlen($string) > $dbmax || strlen($string) < $dbmin){
    echo "reject_this"; exit();
return $string;

For-loop vs while loop in R

The variable in the for loop is an integer sequence, and so eventually you do this:

> y=as.integer(60000)*as.integer(60000)
Warning message:
In as.integer(60000) * as.integer(60000) : NAs produced by integer overflow

whereas in the while loop you are creating a floating point number.

Its also the reason these things are different:

> seq(0,2,1)
[1] 0 1 2
> seq(0,2)
[1] 0 1 2

Don't believe me?

> identical(seq(0,2),seq(0,2,1))


> is.integer(seq(0,2))
[1] TRUE
> is.integer(seq(0,2,1))

How to loop through a directory recursively to delete files with certain extensions

The other answers provided will not include files or directories that start with a . the following worked for me:

  local fl1="$1"/*;
  local fl2="$1"/.[!.]*; 
  local fl3="$1"/..?*;
  for inpath in "$1"/* "$1"/.[!.]* "$1"/..?*; do
    if [ "$inpath" != "$fl1" -a "$inpath" != "$fl2" -a "$inpath" != "$fl3" ]; then 
      stat --printf="%F\0%n\0\n" -- "$inpath";
      if [ -d "$inpath" ]; then
        getAll "$inpath"
      #elif [ -f $inpath ]; then

IOCTL Linux device driver

The ioctl function is useful for implementing a device driver to set the configuration on the device. e.g. a printer that has configuration options to check and set the font family, font size etc. ioctl could be used to get the current font as well as set the font to a new one. A user application uses ioctl to send a code to a printer telling it to return the current font or to set the font to a new one.

int ioctl(int fd, int request, ...)
  1. fd is file descriptor, the one returned by open;
  2. request is request code. e.g GETFONT will get the current font from the printer, SETFONT will set the font on the printer;
  3. the third argument is void *. Depending on the second argument, the third may or may not be present, e.g. if the second argument is SETFONT, the third argument can be the font name such as "Arial";

int request is not just a macro. A user application is required to generate a request code and the device driver module to determine which configuration on device must be played with. The application sends the request code using ioctl and then uses the request code in the device driver module to determine which action to perform.

A request code has 4 main parts

    1. A Magic number - 8 bits
    2. A sequence number - 8 bits
    3. Argument type (typically 14 bits), if any.
    4. Direction of data transfer (2 bits).  

If the request code is SETFONT to set font on a printer, the direction for data transfer will be from user application to device driver module (The user application sends the font name "Arial" to the printer). If the request code is GETFONT, direction is from printer to the user application.

In order to generate a request code, Linux provides some predefined function-like macros.

1._IO(MAGIC, SEQ_NO) both are 8 bits, 0 to 255, e.g. let us say we want to pause printer. This does not require a data transfer. So we would generate the request code as below

#define PRIN_MAGIC 'P'
#define NUM 0

and now use ioctl as

ret_val = ioctl(fd, PAUSE_PRIN);

The corresponding system call in the driver module will receive the code and pause the printer.

  1. __IOW(MAGIC, SEQ_NO, TYPE) MAGIC and SEQ_NO are the same as above, and TYPE gives the type of the next argument, recall the third argument of ioctl is void *. W in __IOW indicates that the data flow is from user application to driver module. As an example, suppose we want to set the printer font to "Arial".
#define PRIN_MAGIC 'S'
#define SEQ_NO 1
#define SETFONT __IOW(PRIN_MAGIC, SEQ_NO, unsigned long)


char *font = "Arial";
ret_val = ioctl(fd, SETFONT, font); 

Now font is a pointer, which means it is an address best represented as unsigned long, hence the third part of _IOW mentions type as such. Also, this address of font is passed to corresponding system call implemented in device driver module as unsigned long and we need to cast it to proper type before using it. Kernel space can access user space and hence this works. other two function-like macros are __IOR(MAGIC, SEQ_NO, TYPE) and __IORW(MAGIC, SEQ_NO, TYPE) where the data flow will be from kernel space to user space and both ways respectively.

Please let me know if this helps!

How can building a heap be O(n) time complexity?

Basically, work is done only on non-leaf nodes while building a heap...and the work done is the amount of swapping down to satisfy heap other words (in worst case) the amount is proportional to the height of the node...all in all the complexity of the problem is proportional to the sum of heights of all the non-leaf nodes..which is (2^h+1 - 1)-h-1=n-h-1= O(n)

Failed to resolve: android

Just add this to your main all project level build.gradle file under allprojects()

 maven {
    url ""

What is the relative performance difference of if/else versus switch statement in Java?

Use switch!

I hate to maintain if-else-blocks! Have a test:

public class SpeedTestSwitch
    private static void do1(int loop)
        int temp = 0;
        for (; loop > 0; --loop)
            int r = (int) (Math.random() * 10);
            switch (r)
                case 0:
                    temp = 9;
                case 1:
                    temp = 8;
                case 2:
                    temp = 7;
                case 3:
                    temp = 6;
                case 4:
                    temp = 5;
                case 5:
                    temp = 4;
                case 6:
                    temp = 3;
                case 7:
                    temp = 2;
                case 8:
                    temp = 1;
                case 9:
                    temp = 0;
        System.out.println("ignore: " + temp);

    private static void do2(int loop)
        int temp = 0;
        for (; loop > 0; --loop)
            int r = (int) (Math.random() * 10);
            if (r == 0)
                temp = 9;
                if (r == 1)
                    temp = 8;
                    if (r == 2)
                        temp = 7;
                        if (r == 3)
                            temp = 6;
                            if (r == 4)
                                temp = 5;
                                if (r == 5)
                                    temp = 4;
                                    if (r == 6)
                                        temp = 3;
                                        if (r == 7)
                                            temp = 2;
                                            if (r == 8)
                                                temp = 1;
                                                if (r == 9)
                                                    temp = 0;
        System.out.println("ignore: " + temp);

    public static void main(String[] args)
        long time;
        int loop = 1 * 100 * 1000 * 1000;
        System.out.println("warming up...");
        do1(loop / 100);
        do2(loop / 100);


        // run 1
        time = System.currentTimeMillis();
        System.out.println(" -> time needed: " + (System.currentTimeMillis() - time));

        // run 2
        time = System.currentTimeMillis();
        System.out.println(" -> time needed: " + (System.currentTimeMillis() - time));

My C# standard code for benchmarking

Printing column separated by comma using Awk command line


awk -F',' '{print $3}' myfile.txt

Here in -F you are saying to awk that use "," as field separator.

Wait some seconds without blocking UI execution

If you do not want to block things and also not want to use multi threading, here is the solution for you:

The UI Thread is not blocked and the timer waits for 2 seconds before doing something.

Here is the code coming from the link above:

        // Create a timer with a two second interval.
    aTimer = new System.Timers.Timer(2000);
    // Hook up the Elapsed event for the timer. 
    aTimer.Elapsed += OnTimedEvent;
    aTimer.Enabled = true;

    Console.WriteLine("Press the Enter key to exit the program... ");
    Console.WriteLine("Terminating the application...");

Adding a column after another column within SQL

It depends on what database you are using. In MySQL, you would use the "ALTER TABLE" syntax. I don't remember exactly how, but it would go something like this if you wanted to add a column called 'newcol' that was a 200 character varchar:

ALTER TABLE example ADD newCol VARCHAR(200) AFTER otherCol;

Static Initialization Blocks

It is a common misconception to think that a static block has only access to static fields. For this I would like to show below piece of code that I quite often use in real-life projects (copied partially from another answer in a slightly different context):

public enum Language { 
  ENGLISH("eng", "en", "en_GB", "en_US"),   
  GERMAN("de", "ge"),   
  CROATIAN("hr", "cro"),   

  static final private Map<String,Language> ALIAS_MAP = new HashMap<String,Language>(); 
  static { 
    for (Language l:Language.values()) { 
      // ignoring the case by normalizing to uppercase
      for (String alias:l.aliases) ALIAS_MAP.put(alias.toUpperCase(),l); 

  static public boolean has(String value) { 
    // ignoring the case by normalizing to uppercase
    return ALIAS_MAP.containsKey(value.toUpper()); 

  static public Language fromString(String value) { 
    if (value == null) throw new NullPointerException("alias null"); 
    Language l = ALIAS_MAP.get(value); 
    if (l == null) throw new IllegalArgumentException("Not an alias: "+value); 
    return l; 

  private List<String> aliases; 
  private Language(String... aliases) { 
    this.aliases = Arrays.asList(aliases); 

Here the initializer is used to maintain an index (ALIAS_MAP), to map a set of aliases back to the original enum type. It is intended as an extension to the built-in valueOf method provided by the Enum itself.

As you can see, the static initializer accesses even the private field aliases. It is important to understand that the static block already has access to the Enum value instances (e.g. ENGLISH). This is because the order of initialization and execution in the case of Enum types, just as if the static private fields have been initialized with instances before the static blocks have been called:

  1. The Enum constants which are implicit static fields. This requires the Enum constructor and instance blocks, and instance initialization to occur first as well.
  2. static block and initialization of static fields in the order of occurrence.

This out-of-order initialization (constructor before static block) is important to note. It also happens when we initialize static fields with the instances similarly to a Singleton (simplifications made):

public class Foo {
  static { System.out.println("Static Block 1"); }
  public static final Foo FOO = new Foo();
  static { System.out.println("Static Block 2"); }
  public Foo() { System.out.println("Constructor"); }
  static public void main(String p[]) {
    System.out.println("In Main");
    new Foo();

What we see is the following output:

Static Block 1
Static Block 2
In Main

Clear is that the static initialization actually can happen before the constructor, and even after:

Simply accessing Foo in the main method, causes the class to be loaded and the static initialization to start. But as part of the Static initialization we again call the constructors for the static fields, after which it resumes static initialization, and completes the constructor called from within the main method. Rather complex situation for which I hope that in normal coding we would not have to deal with.

For more info on this see the book "Effective Java".

React.js, wait for setState to finish before triggering a function?

            originId: input.originId,
            destinationId: input.destinationId,
            radius: input.radius,
        function() { console.log("setState completed", this.state) }

this might be helpful

Pip freeze vs. pip list

The main difference is that the output of pip freeze can be dumped into a requirements.txt file and used later to re-construct the "frozen" environment.

In other words you can run: pip freeze > frozen-requirements.txt on one machine and then later on a different machine or on a clean environment you can do: pip install -r frozen-requirements.txt and you'll get the an identical environment with the exact same dependencies installed as you had in the original environment where you generated the frozen-requirements.txt.

When should I use nil and NULL in Objective-C?

nil is an object pointer to nothing. Although semantically distinct from NULL, they are technically equivalent to one another.

On the framework level, Foundation defines NSNull, which defines a class method, +null, which returns the singleton NSNull object. NSNull is different from nil or NULL, in that it is an actual object, rather than a zero value.

Additionally, in Foundation/NSObjCRuntime.h, Nil is defined as a class pointer to nothing.

Refer this for further info - nil / Nil / NULL / NSNull

Calling C/C++ from Python?

I think cffi for python can be an option.

The goal is to call C code from Python. You should be able to do so without learning a 3rd language: every alternative requires you to learn their own language (Cython, SWIG) or API (ctypes). So we tried to assume that you know Python and C and minimize the extra bits of API that you need to learn.

Sort table rows In Bootstrap

These examples are minified because StackOverflow has a maximum character limit and links to external code are discouraged since links can break.

There are multiple plugins if you look: Bootstrap Sortable, Bootstrap Table or DataTables.

Bootstrap 3 with DataTables Example: Bootstrap Docs & DataTables Docs

$(document).ready(function() {
<link href= rel=stylesheet><link href= rel=stylesheet><div class=container><h1>Bootstrap 3 DataTables</h1><table cellspacing=0 class="table table-bordered table-hover table-striped"id=example width=100%><thead><tr><th>Name<th>Position<th>Office<th>Salary<tbody><tr><td>Tiger Nixon<td>System Architect<td>Edinburgh<td>$320,800<tr><td>Garrett Winters<td>Accountant<td>Tokyo<td>$170,750<tr><td>Ashton Cox<td>Junior Technical Author<td>San Francisco<td>$86,000<tr><td>Cedric Kelly<td>Senior Javascript Developer<td>Edinburgh<td>$433,060<tr><td>Airi Satou<td>Accountant<td>Tokyo<td>$162,700<tr><td>Brielle Williamson<td>Integration Specialist<td>New York<td>$372,000<tr><td>Herrod Chandler<td>Sales Assistant<td>San Francisco<td>$137,500<tr><td>Rhona Davidson<td>Integration Specialist<td>Tokyo<td>$327,900<tr><td>Colleen Hurst<td>Javascript Developer<td>San Francisco<td>$205,500<tr><td>Sonya Frost<td>Software Engineer<td>Edinburgh<td>$103,600<tr><td>Jena Gaines<td>Office Manager<td>London<td>$90,560<tr><td>Quinn Flynn<td>Support Lead<td>Edinburgh<td>$342,000<tr><td>Charde Marshall<td>Regional Director<td>San Francisco<td>$470,600<tr><td>Haley Kennedy<td>Senior Marketing Designer<td>London<td>$313,500<tr><td>Tatyana Fitzpatrick<td>Regional Director<td>London<td>$385,750<tr><td>Michael Silva<td>Marketing Designer<td>London<td>$198,500<tr><td>Paul Byrd<td>Chief Financial Officer (CFO)<td>New York<td>$725,000<tr><td>Gloria Little<td>Systems Administrator<td>New York<td>$237,500<tr><td>Bradley Greer<td>Software Engineer<td>London<td>$132,000<tr><td>Dai Rios<td>Personnel Lead<td>Edinburgh<td>$217,500<tr><td>Jenette Caldwell<td>Development Lead<td>New York<td>$345,000<tr><td>Yuri Berry<td>Chief Marketing Officer (CMO)<td>New York<td>$675,000<tr><td>Caesar Vance<td>Pre-Sales Support<td>New York<td>$106,450<tr><td>Doris Wilder<td>Sales Assistant<td>Sidney<td>$85,600<tr><td>Angelica Ramos<td>Chief Executive Officer (CEO)<td>London<td>$1,200,000<tr><td>Gavin Joyce<td>Developer<td>Edinburgh<td>$92,575<tr><td>Jennifer Chang<td>Regional Director<td>Singapore<td>$357,650<tr><td>Brenden Wagner<td>Software Engineer<td>San Francisco<td>$206,850<tr><td>Fiona Green<td>Chief Operating Officer (COO)<td>San Francisco<td>$850,000<tr><td>Shou Itou<td>Regional Marketing<td>Tokyo<td>$163,000<tr><td>Michelle House<td>Integration Specialist<td>Sidney<td>$95,400<tr><td>Suki Burks<td>Developer<td>London<td>$114,500<tr><td>Prescott Bartlett<td>Technical Author<td>London<td>$145,000<tr><td>Gavin Cortez<td>Team Leader<td>San Francisco<td>$235,500<tr><td>Martena Mccray<td>Post-Sales support<td>Edinburgh<td>$324,050<tr><td>Unity Butler<td>Marketing Designer<td>San Francisco<td>$85,675<tr><td>Howard Hatfield<td>Office Manager<td>San Francisco<td>$164,500<tr><td>Hope Fuentes<td>Secretary<td>San Francisco<td>$109,850<tr><td>Vivian Harrell<td>Financial Controller<td>San Francisco<td>$452,500<tr><td>Timothy Mooney<td>Office Manager<td>London<td>$136,200<tr><td>Jackson Bradshaw<td>Director<td>New York<td>$645,750<tr><td>Olivia Liang<td>Support Engineer<td>Singapore<td>$234,500<tr><td>Bruno Nash<td>Software Engineer<td>London<td>$163,500<tr><td>Sakura Yamamoto<td>Support Engineer<td>Tokyo<td>$139,575<tr><td>Thor Walton<td>Developer<td>New York<td>$98,540<tr><td>Finn Camacho<td>Support Engineer<td>San Francisco<td>$87,500<tr><td>Serge Baldwin<td>Data Coordinator<td>Singapore<td>$138,575<tr><td>Zenaida Frank<td>Software Engineer<td>New York<td>$125,250<tr><td>Zorita Serrano<td>Software Engineer<td>San Francisco<td>$115,000<tr><td>Jennifer Acosta<td>Junior Javascript Developer<td>Edinburgh<td>$75,650<tr><td>Cara Stevens<td>Sales Assistant<td>New York<td>$145,600<tr><td>Hermione Butler<td>Regional Director<td>London<td>$356,250<tr><td>Lael Greer<td>Systems Administrator<td>London<td>$103,500<tr><td>Jonas Alexander<td>Developer<td>San Francisco<td>$86,500<tr><td>Shad Decker<td>Regional Director<td>Edinburgh<td>$183,000<tr><td>Michael Bruce<td>Javascript Developer<td>Singapore<td>$183,000<tr><td>Donna Snider<td>Customer Support<td>New York<td>$112,000</table></div><script src=></script><script src=></script><script src=></script>

Bootstrap 4 with DataTables Example: Bootstrap Docs & DataTables Docs

$(document).ready(function() {
<link href= rel=stylesheet><link href= rel=stylesheet><div class=container><h1>Bootstrap 4 DataTables</h1><table cellspacing=0 class="table table-bordered table-hover table-inverse table-striped"id=example width=100%><thead><tr><th>Name<th>Position<th>Office<th>Age<th>Start date<th>Salary<tfoot><tr><th>Name<th>Position<th>Office<th>Age<th>Start date<th>Salary<tbody><tr><td>Tiger Nixon<td>System Architect<td>Edinburgh<td>61<td>2011/04/25<td>$320,800<tr><td>Garrett Winters<td>Accountant<td>Tokyo<td>63<td>2011/07/25<td>$170,750<tr><td>Ashton Cox<td>Junior Technical Author<td>San Francisco<td>66<td>2009/01/12<td>$86,000<tr><td>Cedric Kelly<td>Senior Javascript Developer<td>Edinburgh<td>22<td>2012/03/29<td>$433,060<tr><td>Airi Satou<td>Accountant<td>Tokyo<td>33<td>2008/11/28<td>$162,700<tr><td>Brielle Williamson<td>Integration Specialist<td>New York<td>61<td>2012/12/02<td>$372,000<tr><td>Herrod Chandler<td>Sales Assistant<td>San Francisco<td>59<td>2012/08/06<td>$137,500<tr><td>Rhona Davidson<td>Integration Specialist<td>Tokyo<td>55<td>2010/10/14<td>$327,900<tr><td>Colleen Hurst<td>Javascript Developer<td>San Francisco<td>39<td>2009/09/15<td>$205,500<tr><td>Sonya Frost<td>Software Engineer<td>Edinburgh<td>23<td>2008/12/13<td>$103,600<tr><td>Jena Gaines<td>Office Manager<td>London<td>30<td>2008/12/19<td>$90,560<tr><td>Quinn Flynn<td>Support Lead<td>Edinburgh<td>22<td>2013/03/03<td>$342,000<tr><td>Charde Marshall<td>Regional Director<td>San Francisco<td>36<td>2008/10/16<td>$470,600<tr><td>Haley Kennedy<td>Senior Marketing Designer<td>London<td>43<td>2012/12/18<td>$313,500<tr><td>Tatyana Fitzpatrick<td>Regional Director<td>London<td>19<td>2010/03/17<td>$385,750<tr><td>Michael Silva<td>Marketing Designer<td>London<td>66<td>2012/11/27<td>$198,500<tr><td>Paul Byrd<td>Chief Financial Officer (CFO)<td>New York<td>64<td>2010/06/09<td>$725,000<tr><td>Gloria Little<td>Systems Administrator<td>New York<td>59<td>2009/04/10<td>$237,500<tr><td>Bradley Greer<td>Software Engineer<td>London<td>41<td>2012/10/13<td>$132,000<tr><td>Dai Rios<td>Personnel Lead<td>Edinburgh<td>35<td>2012/09/26<td>$217,500<tr><td>Jenette Caldwell<td>Development Lead<td>New York<td>30<td>2011/09/03<td>$345,000<tr><td>Yuri Berry<td>Chief Marketing Officer (CMO)<td>New York<td>40<td>2009/06/25<td>$675,000<tr><td>Caesar Vance<td>Pre-Sales Support<td>New York<td>21<td>2011/12/12<td>$106,450<tr><td>Doris Wilder<td>Sales Assistant<td>Sidney<td>23<td>2010/09/20<td>$85,600<tr><td>Angelica Ramos<td>Chief Executive Officer (CEO)<td>London<td>47<td>2009/10/09<td>$1,200,000<tr><td>Gavin Joyce<td>Developer<td>Edinburgh<td>42<td>2010/12/22<td>$92,575<tr><td>Jennifer Chang<td>Regional Director<td>Singapore<td>28<td>2010/11/14<td>$357,650<tr><td>Brenden Wagner<td>Software Engineer<td>San Francisco<td>28<td>2011/06/07<td>$206,850<tr><td>Fiona Green<td>Chief Operating Officer (COO)<td>San Francisco<td>48<td>2010/03/11<td>$850,000<tr><td>Shou Itou<td>Regional Marketing<td>Tokyo<td>20<td>2011/08/14<td>$163,000<tr><td>Michelle House<td>Integration Specialist<td>Sidney<td>37<td>2011/06/02<td>$95,400<tr><td>Suki Burks<td>Developer<td>London<td>53<td>2009/10/22<td>$114,500<tr><td>Prescott Bartlett<td>Technical Author<td>London<td>27<td>2011/05/07<td>$145,000<tr><td>Gavin Cortez<td>Team Leader<td>San Francisco<td>22<td>2008/10/26<td>$235,500<tr><td>Martena Mccray<td>Post-Sales support<td>Edinburgh<td>46<td>2011/03/09<td>$324,050<tr><td>Unity Butler<td>Marketing Designer<td>San Francisco<td>47<td>2009/12/09<td>$85,675<tr><td>Howard Hatfield<td>Office Manager<td>San Francisco<td>51<td>2008/12/16<td>$164,500<tr><td>Hope Fuentes<td>Secretary<td>San Francisco<td>41<td>2010/02/12<td>$109,850<tr><td>Vivian Harrell<td>Financial Controller<td>San Francisco<td>62<td>2009/02/14<td>$452,500<tr><td>Timothy Mooney<td>Office Manager<td>London<td>37<td>2008/12/11<td>$136,200<tr><td>Jackson Bradshaw<td>Director<td>New York<td>65<td>2008/09/26<td>$645,750<tr><td>Olivia Liang<td>Support Engineer<td>Singapore<td>64<td>2011/02/03<td>$234,500<tr><td>Bruno Nash<td>Software Engineer<td>London<td>38<td>2011/05/03<td>$163,500<tr><td>Sakura Yamamoto<td>Support Engineer<td>Tokyo<td>37<td>2009/08/19<td>$139,575<tr><td>Thor Walton<td>Developer<td>New York<td>61<td>2013/08/11<td>$98,540<tr><td>Finn Camacho<td>Support Engineer<td>San Francisco<td>47<td>2009/07/07<td>$87,500<tr><td>Serge Baldwin<td>Data Coordinator<td>Singapore<td>64<td>2012/04/09<td>$138,575<tr><td>Zenaida Frank<td>Software Engineer<td>New York<td>63<td>2010/01/04<td>$125,250<tr><td>Zorita Serrano<td>Software Engineer<td>San Francisco<td>56<td>2012/06/01<td>$115,000<tr><td>Jennifer Acosta<td>Junior Javascript Developer<td>Edinburgh<td>43<td>2013/02/01<td>$75,650<tr><td>Cara Stevens<td>Sales Assistant<td>New York<td>46<td>2011/12/06<td>$145,600<tr><td>Hermione Butler<td>Regional Director<td>London<td>47<td>2011/03/21<td>$356,250<tr><td>Lael Greer<td>Systems Administrator<td>London<td>21<td>2009/02/27<td>$103,500<tr><td>Jonas Alexander<td>Developer<td>San Francisco<td>30<td>2010/07/14<td>$86,500<tr><td>Shad Decker<td>Regional Director<td>Edinburgh<td>51<td>2008/11/13<td>$183,000<tr><td>Michael Bruce<td>Javascript Developer<td>Singapore<td>29<td>2011/06/27<td>$183,000<tr><td>Donna Snider<td>Customer Support<td>New York<td>27<td>2011/01/25<td>$112,000</table></div><script src=></script><script src=></script><script src=></script>

Bootstrap 3 with Bootstrap Table Example: Bootstrap Docs & Bootstrap Table Docs

<link href= rel=stylesheet><link href= rel=stylesheet><table data-sort-name=stargazers_count data-sort-order=desc data-toggle=table data-url=""><thead><tr><th data-field=name data-sortable=true>Name<th data-field=stargazers_count data-sortable=true>Stars<th data-field=forks_count data-sortable=true>Forks<th data-field=description data-sortable=true>Description</thead></table><script src=></script><script src=></script>

Bootstrap 3 with Bootstrap Sortable Example: Bootstrap Docs & Bootstrap Sortable Docs

function randomDate(t,e){return new Date(t.getTime()+Math.random()*(e.getTime()-t.getTime()))}function randomName(){return["Jack","Peter","Frank","Steven"][Math.floor(4*Math.random())]+" "+["White","Jackson","Sinatra","Spielberg"][Math.floor(4*Math.random())]}function newTableRow(){var t=moment(randomDate(new Date(2e3,0,1),new Date)).format("D.M.YYYY"),e=Math.round(Math.random()*Math.random()*100*100)/100,a=Math.round(Math.random()*Math.random()*100*100)/100,r=Math.round(Math.random()*Math.random()*100*100)/100;return"<tr><td>"+randomName()+"</td><td>"+e+"</td><td>"+a+"</td><td>"+r+"</td><td>"+Math.round(100*(e+a+r))/100+"</td><td data-dateformat='D-M-YYYY'>"+t+"</td></tr>"}function customSort(){alert("Custom sort.")}!function(t,e){"use strict";"function"==typeof define&&define.amd?define("tinysort",function(){return e}):t.tinysort=e}(this,function(){"use strict";function t(t,e){for(var a,r=t.length,o=r;o--;)e(t[a=r-o-1],a)}function e(t,e,a){for(var o in 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a=t(this),r=a.closest("table.sortable");"sortTable",r);var s=a.attr("data-sortkey"),i=o?n.lastSort:-1;d[s]=o?d[s]:a.attr("data-defaultsort"),void 0!==d[s]&&o===(s===i)&&(d[s]="asc"===d[s]?"desc":"asc",u(a,r))})})}function i(e){var a=t(e),"sortTable")||a.closest("table.sortable");u(a,r)}function l(e){var"bootstrap-sortable-context");return void 0===a&&(a={bsSort:[],lastSort:void 0},e.find('> thead th[data-defaultsort!="disabled"]').each(function(e){var r=t(this),o=r.attr("data-sortkey");a.bsSort[o]=r.attr("data-defaultsort"),void 0!==a.bsSort[o]&&(a.lastSort=o)}),"bootstrap-sortable-context",a)),a}function c(t,a){e(t,a)}function u(e,a){a.trigger("before-sort");var s=parseFloat(e.attr("data-sortcolumn")),d=l(a),i=d.bsSort;if(e.attr("colspan")){var c=parseFloat("mainsort"))||0,f=parseFloat("sortkey").split("-").pop());if(a.find("> thead tr").length-1>f)return void u(a.find('[data-sortkey="'+(s+c)+"-"+(f+1)+'"]'),a);s+=c}var h=e.attr("data-defaultsign")||r;if(a.find("> thead th").each(function(){t(this).removeClass("up").removeClass("down").addClass("nosort")}),t.browser.mozilla){var p=a.find("> thead div.mozilla");void 0!==p&&(p.find(".sign").remove(),p.parent().html(p.html())),e.wrapInner('<div class="mozilla"></div>'),e.children().eq(0).append('<span class="sign '+h+'"></span>')}else a.find("> thead span.sign").remove(),e.append('<span class="sign '+h+'"></span>');var m=e.attr("data-sortkey"),v="desc"!==e.attr("data-firstsort")?"desc":"asc",b=i[m]||v;d.lastSort!==m&&void 0!==i[m]||(b="asc"===b?"desc":"asc"),i[m]=b,d.lastSort=m,"desc"===i[m]?(e.find("span.sign").addClass("up"),e.addClass("up").removeClass("down nosort")):e.addClass("down").removeClass("up nosort");var g=a.children("tbody").children("tr"),w=[];t(g.filter('[data-disablesort="true"]').get().reverse()).each(function(e,a){var r=t(a);w.push({index:g.index(r),row:r}),r.remove()});var S=g.not('[data-disablesort="true"]');if(0!=S.length){var y="asc"===i[m]&&n;o(S,{emptyEnd:y,selector:"td:nth-child("+(s+1)+")",order:i[m],data:"value"})}t(w.reverse()).each(function(t,e){0===e.index?a.children("tbody").prepend(e.row):a.children("tbody").children("tr").eq(e.index-1).after(e.row)}),a.find("> tbody > tr > td.sorted,> thead th.sorted").removeClass("sorted"),S.find("td:eq("+s+")").addClass("sorted"),e.addClass("sorted"),a.trigger("sorted")}if(t.bootstrapSortable=function(t){null==t?d({}):t.constructor===Boolean?d({applyLast:t}):void 0!==t.sortingHeader?i(t.sortingHeader):d(t)},s.on("click",'table.sortable>thead th[data-defaultsort!="disabled"]',function(t){i(this)}),!t.browser){t.browser={chrome:!1,mozilla:!1,opera:!1,msie:!1,safari:!1};var f=navigator.userAgent;t.each(t.browser,function(e){t.browser[e]=!!new RegExp(e,"i").test(f),t.browser.mozilla&&"mozilla"===e&&(t.browser.mozilla=!!new RegExp("firefox","i").test(f)),"safari"===e&&(t.browser.safari=!1)})}t(t.bootstrapSortable)}),function(){var t=$("table");t.append(newTableRow()),t.append(newTableRow()),$("button.add-row").on("click",function(){var e=$(this);t.append(newTableRow()),"sort")?$.bootstrapSortable(!0):$.bootstrapSortable(!1)}),$("button.change-sort").on("click",function(){$(this).data("custom")?$.bootstrapSortable(!0,void 0,customSort):$.bootstrapSortable(!0,void 0,"default")}),t.on("sorted",function(){alert("Table was sorted.")}),$("#event").on("change",function(){$(this).is(":checked")?t.on("sorted",function(){alert("Table was sorted.")})"sorted")}),$("input[name=sign]:radio").change(function(){$.bootstrapSortable(!0,$(this).val())})}();
table.sortable span.sign { display: block; position: absolute; top: 50%; right: 5px; font-size: 12px; margin-top: -10px; color: #bfbfc1; } table.sortable th:after { display: block; position: absolute; top: 50%; right: 5px; font-size: 12px; margin-top: -10px; color: #bfbfc1; } table.sortable th.arrow:after { content: ''; } table.sortable span.arrow, span.reversed, th.arrow.down:after, th.reversedarrow.down:after, th.arrow.up:after, th.reversedarrow.up:after { border-style: solid; border-width: 5px; font-size: 0; border-color: #ccc transparent transparent transparent; line-height: 0; height: 0; width: 0; margin-top: -2px; } table.sortable span.arrow.up, th.arrow.up:after { border-color: transparent transparent #ccc transparent; margin-top: -7px; } table.sortable span.reversed, th.reversedarrow.down:after { border-color: transparent transparent #ccc transparent; margin-top: -7px; } table.sortable span.reversed.up, th.reversedarrow.up:after { border-color: #ccc transparent transparent transparent; margin-top: -2px; } table.sortable, { content: "a .. z"; } table.sortable, { content: "z .. a"; } table.sortable, th.AZ.nosort:after, th._19.nosort:after, th.month.nosort:after { content: ".."; } table.sortable span.AZ:before, th.AZ.down:after { content: "A .. Z"; } table.sortable span.AZ.up:before, th.AZ.up:after { content: "Z .. A"; } table.sortable span._19:before, th._19.down:after { content: "1 .. 9"; } table.sortable span._19.up:before, th._19.up:after { content: "9 .. 1"; } table.sortable span.month:before, th.month.down:after { content: "jan .. dec"; } table.sortable span.month.up:before, th.month.up:after { content: "dec .. jan"; } table.sortable thead th:not([data-defaultsort=disabled]) { cursor: pointer; position: relative; top: 0; left: 0; } table.sortable thead th:hover:not([data-defaultsort=disabled]) { background: #efefef; } table.sortable thead th div.mozilla { position: relative; }
<link href= rel=stylesheet><link href= rel=stylesheet><div class=container><div class=hero-unit><h1>Bootstrap Sortable</h1></div><table class="sortable table table-bordered table-striped"><thead><tr><th style=width:20%;vertical-align:middle data-defaultsign=nospan class=az data-defaultsort=asc rowspan=2><i class="fa fa-fw fa-map-marker"></i>Name<th style=text-align:center colspan=4 data-mainsort=3>Results<th data-defaultsort=disabled><tr><th style=width:20% colspan=2 data-mainsort=1 data-firstsort=desc>Round 1<th style=width:20%>Round 2<th style=width:20%>Total<t

Error during installing HAXM, VT-X not working

I really hated this awful problem after upgrading Windows 10 Anniversary Update (version 1607). It's just about Driver Signing Changes in Windows 10. If you force install HAXM, you have to disable Driver Signature Enforcement too.

  1. Restart W10 in Safe Mode.
  2. Enter Troubleshoot.
  3. Advanced options>Startup Settings.
  4. Choose "Disable driver signature enforcement"
  5. When Windows 10 loaded, install HAXM latest version.

How do I git rm a file without deleting it from disk?

I tried experimenting with the answers given. My personal finding came out to be:

git rm -r --cached .

And then

git add .

This seemed to make my working directory nice and clean. You can put your fileName in place of the dot.

matching query does not exist Error in Django

I also had this problem. It was caused by the development server not deleting the django session after a debug abort in Aptana, with subsequent database deletion. (Meaning the id of a non-existent database record was still present in the session the next time the development server started)

To resolve this during development, I used


Difference between Static methods and Instance methods

The static modifier when placed in front of a function implies that only one copy of that function exists. If the static modifier is not placed in front of the function then with every object or instance of that class a new copy of that function is made. :) Same is the case with variables.

Angular ng-repeat Error "Duplicates in a repeater are not allowed."

For those who expect JSON and still getting the same error, make sure that you parse your data:

$scope.customers = JSON.parse(data)

Error in Python IOError: [Errno 2] No such file or directory: 'data.csv'

open looks in the current working directory, which in your case is ~, since you are calling your script from the ~ directory.

You can fix the problem by either

  • cding to the directory containing data.csv before executing the script, or

  • by using the full path to data.csv in your script, or

  • by calling os.chdir(...) to change the current working directory from within your script. Note that all subsequent commands that use the current working directory (e.g. open and os.listdir) may be affected by this.

how to convert a string to a bool

Quite simple indeed:

bool b = str == "1";

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

Polymorphism is the ability to treat a class of object as if it is the parent class.

For instance, suppose there is a class called Animal, and a class called Dog that inherits from Animal. Polymorphism is the ability to treat any Dog object as an Animal object like so:

Dog* dog = new Dog;
Animal* animal = dog;

MySQL pivot table query with dynamic columns

The only way in MySQL to do this dynamically is with Prepared statements. Here is a good article about them:

Dynamic pivot tables (transform rows to columns)

Your code would look like this:

SET @sql = NULL;
      'MAX(IF(pa.fieldname = ''',
      ''', pa.fieldvalue, NULL)) AS ',
  ) INTO @sql
FROM product_additional;

                    , p.description, ', @sql, ' 
                   FROM product p
                   LEFT JOIN product_additional AS pa 
                    ON =
                   GROUP BY');

PREPARE stmt FROM @sql;

See Demo

NOTE: GROUP_CONCAT function has a limit of 1024 characters. See parameter group_concat_max_len

Is it possible that one domain name has multiple corresponding IP addresses?

You can do it. That is what big guys do as well.

First query:

» host has address has address has address has address has address has address has address has address has address has address has address

Next query:

» host has address has address has address has address has address has address has address has address has address has address has address

As you see, the list of IPs rotated around, but the relative order between two IPs stayed the same.

Update: I see several comments bragging about how DNS round-robin is not convenient for fail-over, so here is the summary: DNS is not for fail-over. So it is obviously not good for fail-over. It was never designed to be a solution for fail-over.

Tomcat Servlet: Error 404 - The requested resource is not available

You have to user ../../projectName/Filename.jsp in your action attr. or href

../ = contains current folder simple(demo.project.filename.jsp)

Servlet can only be called with 1 slash forward to your project name..

Reset Entity-Framework Migrations

To fix this, You need to:

  1. Delete all *.cs files in the Migrations Folder.

  2. Delete the _MigrationHistory Table in the Database

  3. Run Enable-Migrations -EnableAutomaticMigrations -Force

  4. Run Add-Migration Reset

Then, in the public partial class Reset : DbMigration class, you need to comment all of the existing and current Tables:

public override void Up()
// CreateTable(
// ...
// }

If you miss this bit all will fail and you have to start again!

  1. Now Run Update-Database -verbose

This should be successful if you have done the above correctly, and now you can carry on as normal.

select certain columns of a data table

The question I would ask is, why are you including the extra columns in your DataTable if they aren't required?

Maybe you should modify your SQL select statement so that it is looking at the specific criteria you are looking for as you are populating your DataTable.

You could also use LINQ to query your DataTable as Enumerable and create a List Object that represents only certain columns.

Other than that, hide the DataGridView Columns that you don't require.

Error: vector does not name a type

Also you can add #include<vector> in the header. When two of the above solutions don't work.

How do I define global variables in CoffeeScript?

Ivo nailed it, but I'll mention that there is one dirty trick you can use, though I don't recommend it if you're going for style points: You can embed JavaScript code directly in your CoffeeScript by escaping it with backticks.

However, here's why this is usually a bad idea: The CoffeeScript compiler is unaware of those variables, which means they won't obey normal CoffeeScript scoping rules. So,

`foo = 'bar'`
foo = 'something else'

compiles to

foo = 'bar';
var foo = 'something else';

and now you've got yourself two foos in different scopes. There's no way to modify the global foo from CoffeeScript code without referencing the global object, as Ivy described.

Of course, this is only a problem if you make an assignment to foo in CoffeeScript—if foo became read-only after being given its initial value (i.e. it's a global constant), then the embedded JavaScript solution approach might be kinda sorta acceptable (though still not recommended).

Spring MVC - How to get all request params in a map in Spring controller?

There are two interfaces

  1. org.springframework.web.context.request.WebRequest
  2. org.springframework.web.context.request.NativeWebRequest

Allows for generic request parameter access as well as request/session attribute access, without ties to the native Servlet/Portlet API.


@RequestMapping(value = "/", method = GET)
public List<T> getAll(WebRequest webRequest){
    Map<String, String[]> params = webRequest.getParameterMap();

P.S. There are Docs about arguments which can be used as Controller params.

Why does my Spring Boot App always shutdown immediately after starting?

I think the right answer was at Why does Spring Boot web app close immediately after starting? about the starter-tomcat not being set and if set and running through the IDE, the provided scope should be commented off. Scope doesn't create an issue while running through command. I wonder why.

Anyways just added my additional thoughts.

Whats the CSS to make something go to the next line in the page?

There are two options that I can think of, but without more details, I can't be sure which is the better:

#elementId {
    display: block;

This will force the element to a 'new line' if it's not on the same line as a floated element.

#elementId {
     clear: both;

This will force the element to clear the floats, and move to a 'new line.'

In the case of the element being on the same line as another that has position of fixed or absolute nothing will, so far as I know, force a 'new line,' as those elements are removed from the document's normal flow.

What is an index in SQL?

An index is an on-disk structure associated with a table or view that speeds retrieval of rows from the table or view. An index contains keys built from one or more columns in the table or view. These keys are stored in a structure (B-tree) that enables SQL Server to find the row or rows associated with the key values quickly and efficiently.

Indexes are automatically created when PRIMARY KEY and UNIQUE constraints are defined on table columns. For example, when you create a table with a UNIQUE constraint, Database Engine automatically creates a nonclustered index.

If you configure a PRIMARY KEY, Database Engine automatically creates a clustered index, unless a clustered index already exists. When you try to enforce a PRIMARY KEY constraint on an existing table and a clustered index already exists on that table, SQL Server enforces the primary key using a nonclustered index.

Please refer to this for more information about indexes (clustered and non clustered):

Hope this helps!

What is the purpose of .PHONY in a Makefile?

Let's assume you have install target, which is a very common in makefiles. If you do not use .PHONY, and a file named install exists in the same directory as the Makefile, then make install will do nothing. This is because Make interprets the rule to mean "execute such-and-such recipe to create the file named install". Since the file is already there, and its dependencies didn't change, nothing will be done.

However if you make the install target PHONY, it will tell the make tool that the target is fictional, and that make should not expect it to create the actual file. Hence it will not check whether the install file exists, meaning: a) its behavior will not be altered if the file does exist and b) extra stat() will not be called.

Generally all targets in your Makefile which do not produce an output file with the same name as the target name should be PHONY. This typically includes all, install, clean, distclean, and so on.

how to install apk application from my pc to my mobile android

C:\Program Files (x86)\LG Electronics\LG PC Suite\adb>adb install com.lge.filemanager-15052-v3.1.15052.apk
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
2683 KB/s (3159508 bytes in 1.150s)
pkg: /data/local/tmp/com.lge.filemanager-15052-v3.1.15052.apk

C:\Program Files (x86)\LG Electronics\LG PC Suite\adb>

We can use the adb.exe which is there in PC suit, it worked for me. Thanks Chethan

Count how many files in directory PHP

Try this.

// Directory
$directory = "/dir";

// Returns array of files
$files = scandir($directory);

// Count number of files and store them to variable..
$num_files = count($files)-2;

Not counting the '.' and '..'.

How to check if all list items have the same value and return it, or return an “otherValue” if they don’t?

An alternative to using LINQ:

var set = new HashSet<int>(values);
return (1 == set.Count) ? values.First() : otherValue;

I have found using HashSet<T> is quicker for lists of up to ~ 6,000 integers compared with:

var value1 = items.First();
return values.All(v => v == value1) ? value1: otherValue;

Angular.js: set element height on page load

I came across your post as I was looking for a solution to the same problem for myself. I put together the following solution using a directive based on a number of posts. You can try it here (try resizing the browser window):


<div ng-app="miniapp" ng-controller="AppController" ng-style="style()" resize>
    window.height: {{windowHeight}} <br />
    window.width: {{windowWidth}} <br />


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

function AppController($scope) {
    /* Logic goes here */

app.directive('resize', function ($window) {
    return function (scope, element) {
        var w = angular.element($window);
        scope.getWindowDimensions = function () {
            return { 'h': w.height(), 'w': w.width() };
        scope.$watch(scope.getWindowDimensions, function (newValue, oldValue) {
            scope.windowHeight = newValue.h;
            scope.windowWidth = newValue.w;

   = function () {
                return { 
                    'height': (newValue.h - 100) + 'px',
                    'width': (newValue.w - 100) + 'px' 

        }, true);

        w.bind('resize', function () {

FYI I originally had it working in a controller (, but from subsequent reading found that this is uncool from Angular's perspective, so I have now converted it to use a directive.

Importantly, note the true flag at the end of the 'watch' function, for comparing the getWindowDimensions return object's equality (remove or change to false if not using an object).

Sending JSON to PHP using ajax

I know it's been a while, but just in case someone still needs it:

The JSON object I need to pass:

0:{CommunityId: 509, ListingKey: "20281", Type: 10, Name: "", District: "", Description: "",…}
1:{CommunityId: 510, ListingKey: "20281", Type: 10, Name: "", District: "", Description: "",…}

The Ajax code:

data: JSON.stringify(The-data-shows-above),
type: 'POST',
datatype: 'JSON',
contentType: "application/json; charset=utf-8"

And the PHP side:


It works for me, hope it can help!

How to combine two strings together in PHP?

$result = implode(' ', array($data1, $data2));

is more generic.

How do I update a Tomcat webapp without restarting the entire service?

Have you tried to use Tomcat's Manager application? It allows you to undeploy / deploy war files with out shutting Tomcat down.

If you don't want to use the Manager application, you can also delete the war file from the webapps directory, Tomcat will undeploy the application after a short period of time. You can then copy a war file back into the directory, and Tomcat will deploy the war file.

If you are running Tomcat on Windows, you may need to configure your Context to not lock various files.

If you absolutely can't have any downtime, you may want to look at Tomcat 7's Parallel deployments You may deploy multiple versions of a web application with the same context path at the same time. The rules used to match requests to a context version are as follows:

  • If no session information is present in the request, use the latest version.
  • If session information is present in the request, check the session manager of each version for a matching session and if one is found, use that version.
  • If session information is present in the request but no matching session can be found, use the latest version.

How to disable margin-collapsing?

For your information you could use grid but with side effects :)

.parent {
  display: grid

Can someone explain the dollar sign in Javascript?

Here is a good short video explanation:

According to Ecma International Identifier Names are tokens that are interpreted according to the grammar given in the “Identifiers” section of chapter 5 of the Unicode standard, with some small modifications. An Identifier is an IdentifierName that is not a ReservedWord (see 7.6.1). The Unicode identifier grammar is based on both normative and informative character categories specified by the Unicode Standard. The characters in the specified categories in version 3.0 of the Unicode standard must be treated as in those categories by all conforming ECMAScript implementations.this standard specifies specific character additions:

The dollar sign ($) and the underscore (_) are permitted anywhere in an IdentifierName.

Further reading can be found on:

Ecma International is an industry association founded in 1961 and dedicated to the standardization of Information and Communication Technology (ICT) and Consumer Electronics (CE).

Simple regular expression for a decimal with a precision of 2

Main answer is WRONG because it valids 5. or 5, inputs

this code handle it (but in my example negative numbers are forbidden):


results are bellow:

true => "0" / true => "0.00" / true => "0.0" / true => "0,00" / true => "0,0" / true => "1,2" true => "1.1"/ true => "1" / true => "100" true => "100.00"/ true => "100.0" / true => "1.11" / true => "1,11"/ false => "-5" / false => "-0.00" / true => "101" / false => "0.00.0" / true => "0.000" / true => "000.25" / false => ".25" / true => "100.01" / true => "100.2" / true => "00" / false => "5." / false => "6," / true => "82" / true => "81,3" / true => "7" / true => "7.654"

How to bind multiple values to a single WPF TextBlock?

Use a ValueConverter

[ValueConversion(typeof(string), typeof(String))]
public class MyConverter: IValueConverter
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        return string.Format("{0}:{1}", (string) value, (string) parameter);

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)

        return DependencyProperty.UnsetValue;

and in the markup

<src:MyConverter x:Key="MyConverter"/>

. . .

<TextBlock Text="{Binding Name, Converter={StaticResource MyConverter Parameter=ID}}" />

LINQ query to select top five

Additional information

Sometimes it is necessary to bind a model into a view models and give a type conversion error. In this situation you should use ToList() method.

var list = (from t in ctn.Items
       where t.DeliverySelection == true && t.Delivery.SentForDelivery == null
       orderby t.Delivery.SubmissionDate
       select t).Take(5).ToList();

Floating point exception( core dump

Floating Point Exception happens because of an unexpected infinity or NaN. You can track that using gdb, which allows you to see what is going on inside your C program while it runs. For more details:

In a nutshell, these commands might be useful...

gcc -g myprog.c

gdb a.out

gdb core a.out

ddd a.out

CertPathValidatorException : Trust anchor for certificate path not found - Retrofit Android

Retrofit 2.3.0

    // Load CAs from an InputStream
    CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");

    InputStream inputStream = context.getResources().openRawResource(R.raw.ssl_certificate); //(.crt)
    Certificate certificate = certificateFactory.generateCertificate(inputStream);

    // Create a KeyStore containing our trusted CAs
    String keyStoreType = KeyStore.getDefaultType();
    KeyStore keyStore = KeyStore.getInstance(keyStoreType);
    keyStore.load(null, null);
    keyStore.setCertificateEntry("ca", certificate);

    // Create a TrustManager that trusts the CAs in our KeyStore.
    String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
    TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(tmfAlgorithm);

    TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
    X509TrustManager x509TrustManager = (X509TrustManager) trustManagers[0];

    // Create an SSLSocketFactory that uses our TrustManager
    SSLContext sslContext = SSLContext.getInstance("SSL");
    sslContext.init(null, new TrustManager[]{x509TrustManager}, null);
    sslSocketFactory = sslContext.getSocketFactory();

    //create Okhttp client
    OkHttpClient client = new OkHttpClient.Builder()

    Retrofit retrofit = new Retrofit.Builder()

XmlWriter to Write to a String Instead of to a File

Use StringBuilder:

var sb = new StringBuilder();
    using (XmlWriter xmlWriter = XmlWriter.Create(sb))
return sb.ToString();

What is the difference between YAML and JSON?


The other answers are good. Read those first. But I'll add one other reason to use YAML sometimes: git.

Increasingly, many programming projects use git repositories for distribution and archival. And, while a git repo's history can equally store JSON and YAML files, the "diff" method used for tracking and displaying changes to a file is line-oriented. Since YAML is forced to be line-oriented, any small changes in a YAML file are easier to see by a human.

It is true, of course, that JSON files can be "made pretty" by sorting the strings/keys and adding indentation. But this is not the default and I'm lazy.

Personally, I generally use JSON for system-to-system interaction. I often use YAML for config files, static files, and tracked files. (I also generally avoid adding YAML relational anchors. Life is too short to hunt down loops.)

Also, if speed and space are really a concern, I don't use either. You might want to look at BSON.

How to remove a class from elements in pure JavaScript?

This might help

let allElements = Array.from(document.querySelectorAll('.widget.hover'))
for (let element of allElements) {

Get visible items in RecyclerView

You can use recyclerView.getChildAt() to get each visible child, and setting some tag convertview.setTag(index) on these view in adapter code will help you to relate it with adapter data.

Connect to SQL Server through PDO using SQL Server Driver

Figured this out. Pretty simple:

 new PDO("sqlsrv:server=[sqlservername];Database=[sqlserverdbname]",  "[username]", "[password]");

SVN remains in conflict?

One more solution below,

If the entire folder is removed and SVNis throwing the error "admin file .svn is missing", the following will be used to resolve the conflict to working state.

svn resolve --accept working "file / directory name "

How to assign a heredoc value to a variable in Bash?

Thanks to dimo414's answer, this shows how his great solution works, and shows that you can have quotes and variables in the text easily as well:

example output

$ ./

The text from the example function is:
  Welcome dev: Would you "like" to know how many 'files' there are in /tmp?

  There are "      38" files in /tmp, according to the "wc" command


function text1()
  COUNT=$(\ls /tmp | wc -l)
cat <<EOF

  $1 Would you "like" to know how many 'files' there are in /tmp?

  There are "$COUNT" files in /tmp, according to the "wc" command


function main()
  OUT=$(text1 "Welcome dev:")
  echo "The text from the example function is: $OUT"


Makefile to compile multiple C programs?

SRC = a.cpp b.cpp
BIN = $(patsubst %.cpp,%,$(SRC))

all: $(BIN)

    rm -f $(BIN)

.PHONY: all clean

make all will do:

c++     a.cpp   -o a
c++     b.cpp   -o b

If you set CXX and CXXFLAGS variables make will use them.

How to disable text selection using jQuery?

I found this answer ( Prevent Highlight of Text Table ) most helpful, and perhaps it can be combined with another way of providing IE compatibility.

  -moz-user-select: none;
  -khtml-user-select: none;
  -webkit-user-select: none;
  user-select: none;

Decoding UTF-8 strings in Python

You need to properly decode the source text. Most likely the source text is in UTF-8 format, not ASCII.

Because you do not provide any context or code for your question it is not possible to give a direct answer.

I suggest you study how unicode and character encoding is done in Python:

How do I delete all the duplicate records in a MySQL table without temp tables

As noted in the comments, the query in Saharsh Shah's answer must be run multiple times if items are duplicated more than once.

Here's a solution that doesn't delete any data, and keeps the data in the original table the entire time, allowing for duplicates to be deleted while keeping the table 'live':

alter table tableA add column duplicate tinyint(1) not null default '0';

update tableA set
             and @quiz_num=quiz_num
             and @question_num=question_num
             and @answer_num=answer_num,1,0),
order by member_id, quiz_num, question_num, answer_num;

delete from tableA where duplicate=1;

alter table tableA drop column duplicate;

This basically checks to see if the current row is the same as the last row, and if it is, marks it as duplicate (the order statement ensures that duplicates will show up next to each other). Then you delete the duplicate records. I remove the duplicate column at the end to bring it back to its original state.

It looks like alter table ignore also might go away soon:

In Java, should I escape a single quotation mark (') in String (double quoted)?

It's best practice only to escape the quotes when you need to - if you can get away without escaping it, then do!

The only times you should need to escape are when trying to put " inside a string, or ' in a character:

String quotes = "He said \"Hello, World!\"";
char quote = '\'';

Access to the path is denied

  1. Change the setting from built-in account to custom account and enter the other server's username and password.

  2. Keep the setting as integrated (instead of classic mode).

Check if $_POST exists

The proper way of checking if array key exists is function array_key_exists()

The difference is that when you have $_POST['variable'] = null it means that key exists and was send but value was null

The other option is isset() which which will check if array key exists and if it was set

The last option is to use empty() which will check if array key exists if is set and if value is not considered empty.


$arr = [
  'a' => null,
  'b' => '',
  'c' => 1

array_key_exists('a', $arr); // true
isset($arr['a']); // false
empty($arr['a']); // true

array_key_exists('b', $arr); // true
isset($arr['b']); // true
empty($arr['b']); // true

array_key_exists('c', $arr); // true
isset($arr['c']); // true
empty($arr['c']); // false

Regarding your question

The proper way to check if value was send is to use array_key_exists() with check of request method

if ($_SERVER['REQUEST_METHOD'] == 'POST' && array_key_exists('fromPerson', $_POST)    
   // logic

But there are some cases depends on your logic where isset() and empty() can be good as well.

How to make a Div appear on top of everything else on the screen?

One form to do this is insert the panel that you want to expand inside a DIV setted as relative: let me show you:

<div style="position:relative">
  <div style="position:absolute; z-index: 1000;">
    your code

You use the first div to position the inner content in a specific area inside your page and the second absolute should be referred to the container (because is relative) The z-index in this case is referred also to container and if it higher that the container should be at top. You can put the style in a CSS class and change the size of the absolute div to expand it on hover or another action that you want to control.

I hope that this help

How to install python-dateutil on Windows?

Looks like the uses easy_install (i.e. setuptools). Just install the setuptools package and you will be all set.

To install setuptools in Python 2.6, see the answer to this question.

How to set xampp open localhost:8080 instead of just localhost

Open XAMPP look below the X to close the program there is a Config option click it then click service and port settings then under Apache change your main port to whatever you changed it to in the config file then click save and your good to go.

div background color, to change onhover

Using Javascript

   <div id="mydiv" style="width:200px;background:white" onmouseover="'gray';" onmouseout="'white';">
    Jack and Jill went up the hill 
    To fetch a pail of water. 
    Jack fell down and broke his crown, 
    And Jill came tumbling after. 

How to get the bluetooth devices as a list?

package com.sekurtrack.myapplication;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.Set;

public class MainActivity extends AppCompatActivity {
    ListView listView;
    private BluetoothAdapter BA;
    private ArrayList<String> mDeviceList = new ArrayList<String>();
    private Set<BluetoothDevice> pairedDevices;
    protected void onCreate(Bundle savedInstanceState) {

        BA = BluetoothAdapter.getDefaultAdapter();
        IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        registerReceiver(mReceiver, filter);

       /* BA = BluetoothAdapter.getDefaultAdapter();
        pairedDevices = BA.getBondedDevices();
        ArrayList list = new ArrayList();
        for(BluetoothDevice bt : pairedDevices) list.add(bt.getName());
        Toast.makeText(getApplicationContext(), "Showing Paired Devices",Toast.LENGTH_SHORT).show();
        final ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1, list);


    protected void onDestroy() {

    private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                BluetoothDevice device = intent
                mDeviceList.add(device.getName() + "\n" + device.getAddress());
                Log.i("BT1", device.getName() + "\n" + device.getAddress());
                listView.setAdapter(new ArrayAdapter<String>(context,
                        android.R.layout.simple_list_item_1, mDeviceList));

How to use AND in IF Statement

I think you should append .value in IF statement:

If Cells(i, "A").Value <> "Miami" And Cells(i, "D").Value <> "Florida" Then
    Cells(i, "C").Value = "BA"
End IF

Including external jar-files in a new jar-file build with Ant

With the helpful advice from people who have answered here I started digging into One-Jar. After some dead-ends (and some results that were exactly like my previous results I managed to get it working. For other peoples reference I'm listing the build.xml that worked for me.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project basedir="." default="build" name="<INSERT_PROJECT_NAME_HERE>">
    <property environment="env"/>
    <property name="debuglevel" value="source,lines,vars"/>
    <property name="target" value="1.6"/>
    <property name="source" value="1.6"/>

    <property name="one-jar.dist.dir" value="../onejar"/>
    <import file="${one-jar.dist.dir}/one-jar-ant-task.xml" optional="true" />

    <property name="src.dir"          value="src"/>
    <property name="bin.dir"          value="bin"/>
    <property name="build.dir"        value="build"/>
    <property name="classes.dir"      value="${build.dir}/classes"/>
    <property name=""   value="${build.dir}/jars"/>
    <property name="external.lib.dir" value="../jars"/>
    <property name="final.jar"        value="${bin.dir}/<INSERT_NAME_OF_FINAL_JAR_HERE>"/>

    <property name="main.class"       value="<INSERT_MAIN_CLASS_HERE>"/>

    <path id="project.classpath">
        <fileset dir="${external.lib.dir}">
            <include name="*.jar"/>

    <target name="init">
        <mkdir dir="${bin.dir}"/>
        <mkdir dir="${build.dir}"/>
        <mkdir dir="${classes.dir}"/>
        <mkdir dir="${}"/>
        <copy includeemptydirs="false" todir="${classes.dir}">
            <fileset dir="${src.dir}">
                <exclude name="**/*.launch"/>
                <exclude name="**/*.java"/>

    <target name="clean">
        <delete dir="${build.dir}"/>
        <delete dir="${bin.dir}"/>

    <target name="cleanall" depends="clean"/>

    <target name="build" depends="init">
        <echo message="${}: ${ant.file}"/>
        <javac debug="true" debuglevel="${debuglevel}" destdir="${classes.dir}" source="${source}" target="${target}">
            <src path="${src.dir}"/>
            <classpath refid="project.classpath"/>   

    <target name="build-jar" depends="build">
        <delete file="${final.jar}" />
        <one-jar destfile="${final.jar}" onejarmainclass="${main.class}">
                <fileset dir="${classes.dir}"/>
                <fileset dir="${external.lib.dir}" />

I hope someone else can benefit from this.

How to export data to an excel file using PHPExcel

Try the below complete example for the same

  $objPHPExcel = new PHPExcel();
  $query1 = "SELECT * FROM employee";
  $exec1 = mysql_query($query1) or die ("Error in Query1".mysql_error());
  //Set header with temp array
  $tmparray =array("Sr.Number","Employee Login","Employee Name");
  //take new main array and set header array in it.
  $sheet =array($tmparray);

  while ($res1 = mysql_fetch_array($exec1))
    $tmparray =array();
    $serialnumber = $serialnumber + 1;
    $employeelogin = $res1['employeelogin'];
    $employeename = $res1['employeename'];
   header('Content-type: application/');
   header('Content-Disposition: attachment; filename="name.xlsx"');
  $worksheet = $objPHPExcel->getActiveSheet();
  foreach($sheet as $row => $columns) {
    foreach($columns as $column => $data) {
        $worksheet->setCellValueByColumnAndRow($column, $row + 1, $data);

  //make first row bold
  $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
  $objWriter->save(str_replace('.php', '.xlsx', __FILE__));

python .replace() regex

In order to replace text using regular expression use the re.sub function:

sub(pattern, repl, string[, count, flags])

It will replace non-everlaping instances of pattern by the text passed as string. If you need to analyze the match to extract information about specific group captures, for instance, you can pass a function to the string argument. more info here.


>>> import re
>>> re.sub(r'a', 'b', 'banana')

>>> re.sub(r'/\d+', '/{id}', '/andre/23/abobora/43435')

How to get names of classes inside a jar file?

You can use the

jar tf example.jar

Templated check for the existence of a class member function?

C++ allows SFINAE to be used for this (notice that with C++11 features this is simplier because it supports extended SFINAE on nearly arbitrary expressions - the below was crafted to work with common C++03 compilers):

#define HAS_MEM_FUNC(func, name)                                        \
    template<typename T, typename Sign>                                 \
    struct name {                                                       \
        typedef char yes[1];                                            \
        typedef char no [2];                                            \
        template <typename U, U> struct type_check;                     \
        template <typename _1> static yes &chk(type_check<Sign, &_1::func > *); \
        template <typename   > static no  &chk(...);                    \
        static bool const value = sizeof(chk<T>(0)) == sizeof(yes);     \

the above template and macro tries to instantiate a template, giving it a member function pointer type, and the actual member function pointer. If the types to not fit, SFINAE causes the template to be ignored. Usage like this:

HAS_MEM_FUNC(toString, has_to_string);

template<typename T> void
doSomething() {
   if(has_to_string<T, std::string(T::*)()>::value) {
   } else {

But note that you cannot just call that toString function in that if branch. since the compiler will check for validity in both branches, that would fail for cases the function doesnt exist. One way is to use SFINAE once again (enable_if can be gotten from boost too):

template<bool C, typename T = void>
struct enable_if {
  typedef T type;

template<typename T>
struct enable_if<false, T> { };

HAS_MEM_FUNC(toString, has_to_string);

template<typename T> 
typename enable_if<has_to_string<T, 
                   std::string(T::*)()>::value, std::string>::type
doSomething(T * t) {
   /* something when T has toString ... */
   return t->toString();

template<typename T> 
typename enable_if<!has_to_string<T, 
                   std::string(T::*)()>::value, std::string>::type
doSomething(T * t) {
   /* something when T doesnt have toString ... */
   return "T::toString() does not exist.";

Have fun using it. The advantage of it is that it also works for overloaded member functions, and also for const member functions (remember using std::string(T::*)() const as the member function pointer type then!).

Understanding events and event handlers in C#

To understand event handlers, you need to understand delegates. In C#, you can think of a delegate as a pointer (or a reference) to a method. This is useful because the pointer can be passed around as a value.

The central concept of a delegate is its signature, or shape. That is (1) the return type and (2) the input arguments. For example, if we create a delegate void MyDelegate(object sender, EventArgs e), it can only point to methods which return void, and take an object and EventArgs. Kind of like a square hole and a square peg. So we say these methods have the same signature, or shape, as the delegate.

So knowing how to create a reference to a method, let's think about the purpose of events: we want to cause some code to be executed when something happens elsewhere in the system - or "handle the event". To do this, we create specific methods for the code we want to be executed. The glue between the event and the methods to be executed are the delegates. The event must internally store a "list" of pointers to the methods to call when the event is raised.* Of course, to be able to call a method, we need to know what arguments to pass to it! We use the delegate as the "contract" between the event and all the specific methods that will be called.

So the default EventHandler (and many like it) represents a specific shape of method (again, void/object-EventArgs). When you declare an event, you are saying which shape of method (EventHandler) that event will invoke, by specifying a delegate:

//This delegate can be used to point to methods
//which return void and take a string.
public delegate void MyEventHandler(string foo);

//This event can cause any method which conforms
//to MyEventHandler to be called.
public event MyEventHandler SomethingHappened;

//Here is some code I want to be executed
//when SomethingHappened fires.
void HandleSomethingHappened(string foo)
    //Do some stuff

//I am creating a delegate (pointer) to HandleSomethingHappened
//and adding it to SomethingHappened's list of "Event Handlers".
myObj.SomethingHappened += new MyEventHandler(HandleSomethingHappened);

//To raise the event within a method.

(*This is the key to events in .NET and peels away the "magic" - an event is really, under the covers, just a list of methods of the same "shape". The list is stored where the event lives. When the event is "raised", it's really just "go through this list of methods and call each one, using these values as the parameters". Assigning an event handler is just a prettier, easier way of adding your method to this list of methods to be called).

Binary Search Tree - Java Implementation

According to Collections Framework Overview you have two balanced tree implementations:

What's the difference between HEAD^ and HEAD~ in Git?

The difference between HEAD^ and HEAD~ is well described by the illustration (by Jon Loeliger) found on

This documentation can be a bit obscure to beginners so I've reproduced that illustration below:

G   H   I   J
 \ /     \ /
  D   E   F
   \  |  / \
    \ | /   |
     \|/    |
      B     C
       \   /
        \ /
A =      = A^0
B = A^   = A^1     = A~1
C = A^2
D = A^^  = A^1^1   = A~2
E = B^2  = A^^2
F = B^3  = A^^3
G = A^^^ = A^1^1^1 = A~3
H = D^2  = B^^2    = A^^^2  = A~2^2
I = F^   = B^3^    = A^^3^
J = F^2  = B^3^2   = A^^3^2

Setting action for back button in navigation controller

Swift version of @onegray's answer

protocol RequestsNavigationPopVerification {
    var confirmationTitle: String { get }
    var confirmationMessage: String { get }

extension RequestsNavigationPopVerification where Self: UIViewController {
    var confirmationTitle: String {
        return "Go back?"

    var confirmationMessage: String {
        return "Are you sure?"

final class NavigationController: UINavigationController {

    func navigationBar(navigationBar: UINavigationBar, shouldPopItem item: UINavigationItem) -> Bool {

        guard let requestsPopConfirm = topViewController as? RequestsNavigationPopVerification else {
            return true

        let alertController = UIAlertController(title: requestsPopConfirm.confirmationTitle, message: requestsPopConfirm.confirmationMessage, preferredStyle: .Alert)

        alertController.addAction(UIAlertAction(title: "Cancel", style: .Cancel) { _ in
            dispatch_async(dispatch_get_main_queue(), {
                let dimmed = navigationBar.subviews.flatMap { $0.alpha < 1 ? $0 : nil }
                UIView.animateWithDuration(0.25) {
                    dimmed.forEach { $0.alpha = 1 }

        alertController.addAction(UIAlertAction(title: "Go back", style: .Default) { _ in
            dispatch_async(dispatch_get_main_queue(), {

        presentViewController(alertController, animated: true, completion: nil)

        return false

Now in any controller, just conform to RequestsNavigationPopVerification and this behaviour is adopted by default.

List all liquibase sql types

I've found the liquibase.database.typeconversion.core.AbstractTypeConverter class. It lists all types that can be used:

protected DataType getDataType(String columnTypeString, Boolean autoIncrement, String dataTypeName, String precision, String additionalInformation) {
    // Translate type to database-specific type, if possible
    DataType returnTypeName = null;
    if (dataTypeName.equalsIgnoreCase("BIGINT")) {
        returnTypeName = getBigIntType();
    } else if (dataTypeName.equalsIgnoreCase("NUMBER") || dataTypeName.equalsIgnoreCase("NUMERIC")) {
        returnTypeName = getNumberType();
    } else if (dataTypeName.equalsIgnoreCase("BLOB")) {
        returnTypeName = getBlobType();
    } else if (dataTypeName.equalsIgnoreCase("BOOLEAN")) {
        returnTypeName = getBooleanType();
    } else if (dataTypeName.equalsIgnoreCase("CHAR")) {
        returnTypeName = getCharType();
    } else if (dataTypeName.equalsIgnoreCase("CLOB")) {
        returnTypeName = getClobType();
    } else if (dataTypeName.equalsIgnoreCase("CURRENCY")) {
        returnTypeName = getCurrencyType();
    } else if (dataTypeName.equalsIgnoreCase("DATE") || dataTypeName.equalsIgnoreCase(getDateType().getDataTypeName())) {
        returnTypeName = getDateType();
    } else if (dataTypeName.equalsIgnoreCase("DATETIME") || dataTypeName.equalsIgnoreCase(getDateTimeType().getDataTypeName())) {
        returnTypeName = getDateTimeType();
    } else if (dataTypeName.equalsIgnoreCase("DOUBLE")) {
        returnTypeName = getDoubleType();
    } else if (dataTypeName.equalsIgnoreCase("FLOAT")) {
        returnTypeName = getFloatType();
    } else if (dataTypeName.equalsIgnoreCase("INT")) {
        returnTypeName = getIntType();
    } else if (dataTypeName.equalsIgnoreCase("INTEGER")) {
        returnTypeName = getIntType();
    } else if (dataTypeName.equalsIgnoreCase("LONGBLOB")) {
        returnTypeName = getLongBlobType();
    } else if (dataTypeName.equalsIgnoreCase("LONGVARBINARY")) {
        returnTypeName = getBlobType();
    } else if (dataTypeName.equalsIgnoreCase("LONGVARCHAR")) {
        returnTypeName = getClobType();
    } else if (dataTypeName.equalsIgnoreCase("SMALLINT")) {
        returnTypeName = getSmallIntType();
    } else if (dataTypeName.equalsIgnoreCase("TEXT")) {
        returnTypeName = getClobType();
    } else if (dataTypeName.equalsIgnoreCase("TIME") || dataTypeName.equalsIgnoreCase(getTimeType().getDataTypeName())) {
        returnTypeName = getTimeType();
    } else if (dataTypeName.toUpperCase().contains("TIMESTAMP")) {
        returnTypeName = getDateTimeType();
    } else if (dataTypeName.equalsIgnoreCase("TINYINT")) {
        returnTypeName = getTinyIntType();
    } else if (dataTypeName.equalsIgnoreCase("UUID")) {
        returnTypeName = getUUIDType();
    } else if (dataTypeName.equalsIgnoreCase("VARCHAR")) {
        returnTypeName = getVarcharType();
    } else if (dataTypeName.equalsIgnoreCase("NVARCHAR")) {
        returnTypeName = getNVarcharType();
    } else {
        return new CustomType(columnTypeString,0,2);

How to detect control+click in Javascript from an onclick div attribute?

I'd recommend using JQuery's keyup and keydown methods on the document, as it normalizes the event codes, to make one solution crossbrowser.

For the right click, you can use oncontextmenu, however beware it can be buggy in IE8. See a chart of compatibility here:

<p onclick="selectMe(1)" oncontextmenu="selectMe(2)">Click me</p>

        cntrlIsPressed = true;

    cntrlIsPressed = false;

var cntrlIsPressed = false;

function selectMe(mouseButton)
            case 1:
                alert("Cntrl +  left click");
            case 2:
                alert("Cntrl + right click");


Detecting when a div's height changes using jQuery

Use a resize sensor from the css-element-queries library:

new ResizeSensor(jQuery('#myElement'), function() {
    console.log('myelement has been resized');

It uses a event based approach and doesn't waste your cpu time. Works in all browsers incl. IE7+.

intelliJ IDEA 13 error: please select Android SDK

I had same problem once. every things seems right. I restart, delete and invalidate cache of Android studio, rebuild, clean and nothings changed. It is finally solved by click on Sync Project with Gradle Files button in android studio 3.0

Sync Project with Gradle Files button

Sending a JSON to server and retrieving a JSON in return, without JQuery

Using new api fetch:

const dataToSend = JSON.stringify({"email": "[email protected]", "password": "101010"});
let dataReceived = ""; 
fetch("", {
    credentials: "same-origin",
    mode: "same-origin",
    method: "post",
    headers: { "Content-Type": "application/json" },
    body: dataToSend
    .then(resp => {
        if (resp.status === 200) {
            return resp.json()
        } else {
            console.log("Status: " + resp.status)
            return Promise.reject("server")
    .then(dataJson => {
        dataReceived = JSON.parse(dataJson)
    .catch(err => {
        if (err === "server") return

console.log(`Received: ${dataReceived}`)                
_x000D_ You need to handle when server sends other status rather than 200(ok), you should reject that result because if you were to left it in blank, it will try to parse the json but there isn't, so it will throw an error

How do I get the width and height of a HTML5 canvas?

now starting 2015 all (major?) browsers seem to alow c.width and c.height to get the canvas internal size, but:

the question as the answers are missleading, because the a canvas has in principle 2 different/independent sizes.

The "html" lets say CSS width/height and its own (attribute-) width/height

look at this short example of different sizing, where I put a 200/200 canvas into a 300/100 html-element

With most examples (all I saw) there is no css-size set, so theese get implizit the width and height of the (drawing-) canvas size. But that is not a must, and can produce funy results, if you take the wrong size - ie. css widht/height for inner positioning.

Why is my toFixed() function not working?

Example simple (worked):

var a=Number.parseFloat($("#budget_project").val()); // from input field
var b=Number.parseFloat(html); // from ajax
var c=a-b;
$("#result").html(c.toFixed(2)); // put to id='result' (div or others)

What's the main difference between Java SE and Java EE?

Best description i've encounter so far is available on Oracle website.

Java SE's API provides the core functionality of the Java programming language. It defines everything from the basic types and objects of the Java programming language to high-level classes that are used for networking, security, database access, graphical user interface (GUI) development, and XML parsing.

The Java EE platform is built on top of the Java SE platform. The Java EE platform provides an API and runtime environment for developing and running large-scale, multi-tiered, scalable, reliable, and secure network applications.

If you consider developing application using for example Spring Framework you will use both API's and would have to learn key concept of JavaServer Pages and related technologies like for ex.: JSP, JPA, JDBC, Dependency Injection etc.

jQuery: Adding two attributes via the .attr(); method

Multiple Attribute

var tag = "tag name";
createNode(tag, target, attribute);

createNode: function(tag, target, attribute){
    var tag = jQuery("<" + tag + ">");
    jQuery.each(attribute, function(i,v){
var attribute = [
    {"data-level": "3"},

How to check all versions of python installed on osx and centos

we can directly use this to see all the pythons installed both by current user and the root by the following: whereis python

How does Spring autowire by name when more than one matching bean is found?

You can use the @Qualifier annotation

From here

Fine-tuning annotation-based autowiring with qualifiers

Since autowiring by type may lead to multiple candidates, it is often necessary to have more control over the selection process. One way to accomplish this is with Spring's @Qualifier annotation. This allows for associating qualifier values with specific arguments, narrowing the set of type matches so that a specific bean is chosen for each argument. In the simplest case, this can be a plain descriptive value:

class Main {
    private Country country;
    public void setCountry(Country country) { = country;

This will use the UK add an id to USA bean and use that if you want the USA.

Copy/duplicate database without using mysqldump

Mysqldump isn't bad solution. Simplest way to duplicate database:

mysqldump -uusername -ppass dbname1 | mysql -uusername -ppass dbname2

Also, you can change storage engine by this way:

mysqldump -uusername -ppass dbname1 | sed 's/InnoDB/RocksDB/' | mysql -uusername -ppass dbname2

Remove spacing between table cells and rows

Used font-size:0 in parent TD which has the image.

Easy way to make a confirmation dialog in Angular?

You could use sweetalert:

npm install sweetalert --save

Then, simply import it into your application:

import swal from 'sweetalert';

If you pass two arguments, the first one will be the modal's title, and the second one its text.

swal("Here's the title!", "...and here's the text!");

JUnit assertEquals(double expected, double actual, double epsilon)

Epsilon is your "fuzz factor," since doubles may not be exactly equal. Epsilon lets you describe how close they have to be.

If you were expecting 3.14159 but would take anywhere from 3.14059 to 3.14259 (that is, within 0.001), then you should write something like

double myPi = 22.0d / 7.0d; //Don't use this in real life!
assertEquals(3.14159, myPi, 0.001);

(By the way, 22/7 comes out to 3.1428+, and would fail the assertion. This is a good thing.)

Calling stored procedure from another stored procedure SQL Server

Simply call test2 from test1 like:

EXEC test2 @newId, @prod, @desc;

Make sure to get @id using SCOPE_IDENTITY(), which gets the last identity value inserted into an identity column in the same scope:


How do I fix the Visual Studio compile error, "mismatch between processor architecture"?

You may also get this warning for MS Fakes assemblies which isn't as easy to resolve since the f.csproj is build on command. Luckily the Fakes xml allows you to add it in there.

SSL Error: CERT_UNTRUSTED while using npm command

npm ERR! node -v v0.8.0
npm ERR! npm -v 1.1.32

Update your node.js installation.The following commands should do it (from here):

sudo npm cache clean -f
sudo npm install -g n
sudo n stable

Edit: okay, if you really have a good reason to run an ancient version of the software, npm set ca null will fix the issue. It happened, because built-in npm certificate has expired over the years.

Angular: How to download a file from HttpClient?

I ended up here when searching for ”rxjs download file using post”.

This was my final product. It uses the file name and type given in the server response.

import { ajax, AjaxResponse } from 'rxjs/ajax';
import { map } from 'rxjs/operators';

downloadPost(url: string, data: any) {
    return ajax({
        url: url,
        method: 'POST',
        responseType: 'blob',
        body: data,
        headers: {
            'Content-Type': 'application/json',
            'Accept': 'text/plain, */*',
            'Cache-Control': 'no-cache',

handleDownloadSuccess(response: AjaxResponse) {
    const downloadLink = document.createElement('a');
    downloadLink.href = window.URL.createObjectURL(response.response);

    const disposition = response.xhr.getResponseHeader('Content-Disposition');
    if (disposition) {
        const filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
        const matches = filenameRegex.exec(disposition);
        if (matches != null && matches[1]) {
            const filename = matches[1].replace(/['"]/g, '');
            downloadLink.setAttribute('download', filename);


Trusting all certificates with okHttp

Just in case anyone falls here, the (only) solution that worked for me is creating the OkHttpClient like explained here.

Here is the code:

private static OkHttpClient getUnsafeOkHttpClient() {
  try {
    // Create a trust manager that does not validate certificate chains
    final TrustManager[] trustAllCerts = new TrustManager[] {
        new X509TrustManager() {
          public void checkClientTrusted([] chain, String authType) throws CertificateException {

          public void checkServerTrusted([] chain, String authType) throws CertificateException {

          public[] getAcceptedIssuers() {
            return new[]{};

    // Install the all-trusting trust manager
    final SSLContext sslContext = SSLContext.getInstance("SSL");
    sslContext.init(null, trustAllCerts, new;
    // Create an ssl socket factory with our all-trusting manager
    final SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();

    OkHttpClient.Builder builder = new OkHttpClient.Builder();
    builder.sslSocketFactory(sslSocketFactory, (X509TrustManager)trustAllCerts[0]);
    builder.hostnameVerifier(new HostnameVerifier() {
      public boolean verify(String hostname, SSLSession session) {
        return true;

    OkHttpClient okHttpClient =;
    return okHttpClient;
  } catch (Exception e) {
    throw new RuntimeException(e);

How to access a mobile's camera from a web app?

well, there's a new HTML5 features for accessing the native device camera - "getUserMedia API"

NOTE: HTML5 can handle photo capture from a web page on Android devices (at least on the latest versions, run by the Honeycomb OS; but it can’t handle it on iPhones but iOS 6 ).

Making RGB color in Xcode

You already got the right answer, but if you dislike the UIColor interface like me, you can do this:

#import "UIColor+Helper.h"
// ...
myLabel.textColor = [UIColor colorWithRGBA:0xA06105FF];


#import <UIKit/UIKit.h>

@interface UIColor (Helper)
+ (UIColor *)colorWithRGBA:(NSUInteger)color;


#import "UIColor+Helper.h"

@implementation UIColor (Helper)

+ (UIColor *)colorWithRGBA:(NSUInteger)color
    return [UIColor colorWithRed:((color >> 24) & 0xFF) / 255.0f
                           green:((color >> 16) & 0xFF) / 255.0f
                            blue:((color >> 8) & 0xFF) / 255.0f
                           alpha:((color) & 0xFF) / 255.0f];


One line ftp server in python

apt-get install python3-pip

pip3 install pyftpdlib

python3 -m pyftpdlib -p 21 -w --user=username --password=password

-w = write permission

-p = desired port

--user = give your username

--password = give your password

Can we pass an array as parameter in any function in PHP?

Yes, we can pass arrays to a function.

$arr = array(“a” => “first”, “b” => “second”, “c” => “third”);

function user_defined($item, $key)
    echo $key.”-”.$item.”<br/>”;

array_walk($arr, ‘user_defined’);

We can find more array functions here

Run JavaScript code on window close or page refresh?

You can use window.onbeforeunload.

window.onbeforeunload = confirmExit;
function confirmExit(){
    alert("confirm exit is being called");
    return false;

Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize

The JDK 8 HotSpot JVM is now using native memory for the representation of class metadata and is called Metaspace.

The permanent generation has been removed. The PermSize and MaxPermSize are ignored and a warning is issued if they are present on the command line.

Foreign Key Django Model

You create the relationships the other way around; add foreign keys to the Person type to create a Many-to-One relationship:

class Person(models.Model):
    name = models.CharField(max_length=50)
    birthday = models.DateField()
    anniversary = models.ForeignKey(
        Anniversary, on_delete=models.CASCADE)
    address = models.ForeignKey(
        Address, on_delete=models.CASCADE)

class Address(models.Model):
    line1 = models.CharField(max_length=150)
    line2 = models.CharField(max_length=150)
    postalcode = models.CharField(max_length=10)
    city = models.CharField(max_length=150)
    country = models.CharField(max_length=150)

class Anniversary(models.Model):
    date = models.DateField()

Any one person can only be connected to one address and one anniversary, but addresses and anniversaries can be referenced from multiple Person entries.

Anniversary and Address objects will be given a reverse, backwards relationship too; by default it'll be called person_set but you can configure a different name if you need to. See Following relationships "backward" in the queries documentation.

How to replace innerHTML of a div using jQuery?

Here is your answer:

//This is the setter of the innerHTML property in jQuery
$('#regTitle').html('Hello World');

//This is the getter of the innerHTML property in jQuery
var helloWorld = $('#regTitle').html();

use of entityManager.createNativeQuery(query,foo.class)

JPA was designed to provide an automatic mapping between Objects and a relational database. Since Integer is not a persistant entity, why do you need to use JPA ? A simple JDBC request will work fine.


A few days ago I've had an issue with triggers, and I've figured out that ON UPDATE CASCADE can be useful. Take a look at this example (PostgreSQL):

    name TEXT UNIQUE

    name TEXT UNIQUE

    club_name TEXT REFERENCES club(name) ON UPDATE CASCADE,
    band_name TEXT REFERENCES band(name) ON UPDATE CASCADE,
    concert_date DATE

In my issue, I had to define some additional operations (trigger) for updating the concert's table. Those operations had to modify club_name and band_name. I was unable to do it, because of reference. I couldn't modify concert and then deal with club and band tables. I couldn't also do it the other way. ON UPDATE CASCADE was the key to solve the problem.

Laravel, sync() - how to sync an array and also pass additional pivot fields?

Add following trait to your project and append it to your model class as a trait. This is helpful, because this adds functionality to use multiple pivots. Probably someone can clean this up a little and improve on it ;)

namespace App\Traits;

trait AppTraits
     * Create pivot array from given values
     * @param array $entities
     * @param array $pivots
     * @return array combined $pivots
    public function combinePivot($entities, $pivots = [])
        // Set array
        $pivotArray = [];
        // Loop through all pivot attributes
        foreach ($pivots as $pivot => $value) {
            // Combine them to pivot array
            $pivotArray += [$pivot => $value];
        // Get the total of arrays we need to fill
        $total = count($entities);
        // Make filler array
        $filler = array_fill(0, $total, $pivotArray);
        // Combine and return filler pivot array with data
        return array_combine($entities, $filler);


namespace App;

use Illuminate\Database\Eloquent\Model;

class Example extends Model
    use Traits\AppTraits;
    // ...


// Get id's
$entities = [1, 2, 3];
// Create pivots
$pivots = [
    'price' => 634,
    'name'  => 'Example name',
// Combine the ids and pivots
$combination = $model->combinePivot($entities, $pivots);
// Sync the combination with the related model / pivot

Sending and Receiving SMS and MMS in Android (pre Kit Kat Android 4.4)

I dont understand the frustrations. Why not just make a broadcastreceiver that filters for this intent:


I checked a little further and you might need system level access to get this (rooted phone).

Accessing JSON elements

import json
weather = urllib2.urlopen('url')
wjson =
wjdata = json.loads(wjson)
print wjdata['data']['current_condition'][0]['temp_C']

What you get from the url is a json string. And your can't parse it with index directly. You should convert it to a dict by json.loads and then you can parse it with index.

Instead of using .read() to intermediately save it to memory and then read it to json, allow json to load it directly from the file:

wjdata = json.load(urllib2.urlopen('url'))

Read file As String

public static String readFileToString(String filePath) {
    InputStream in = Test.class.getResourceAsStream(filePath);//filePath="/com/myproject/Sample.xml"
    try {
        return IOUtils.toString(in, StandardCharsets.UTF_8);
    } catch (IOException e) {
        logger.error("Failed to read the xml : ", e);
    return null;

How to check if a character is upper-case in Python?

Use list(str) to break into chars then import string and use string.ascii_uppercase to compare against.

Check the string module:

What's the whole point of "localhost", hosts and ports at all?

I heard a good description (parable) which illustrates ports as different delivery points for a large building, e.g. Post office for letters and small parcels, Goods In for large deliveries / pallets, Doors for people.

Onclick event to remove default value in a text input field

u can use placeholder and when u write a text on the search box placeholder will hidden. Thanks

<input placeholder="Search" type="text" />

How can I convert a date to GMT?

Based on the accepted answer and the second highest scoring answer both are not perfect according to the comment so I mixed both to get something perfect:

var date = new Date(); //Current timestamp_x000D_
date = date.toGMTString(); _x000D_
//Based on the time zone where the date was created_x000D_
/*based on the comment getTimezoneOffset returns an offset based _x000D_
on the date it is called on, and the time zone of the computer the code is_x000D_
 running on. It does not supply the offset passed in when constructing a _x000D_
date from a string. */_x000D_
date = new Date(date); //will convert to present timestamp offset_x000D_
date = new Date(date.getTime() + (date.getTimezoneOffset() * 60 * 1000)); _x000D_

How do I use .toLocaleTimeString() without displaying seconds?

You can always set the options, based on this page you can set, to get rid of the seconds, something like this

var dateWithouthSecond = new Date();
dateWithouthSecond.toLocaleTimeString([], {hour: '2-digit', minute:'2-digit'});

Supported by Firefox, Chrome, IE9+ and Opera. Try it on your web browser console.

How do I grant read access for a user to a database in SQL Server?

This is a two-step process:

  1. you need to create a login to SQL Server for that user, based on its Windows account

    CREATE LOGIN [<domainName>\<loginName>] FROM WINDOWS;
  2. you need to grant this login permission to access a database:

    USE (your database)
    CREATE USER (username) FOR LOGIN (your login name)

Once you have that user in your database, you can give it any rights you want, e.g. you could assign it the db_datareader database role to read all tables.

USE (your database)
EXEC sp_addrolemember 'db_datareader', '(your user name)'

Duplicate and rename Xcode project & associated folders

I'm posting this since I have always been struggling when renaming a project in XCode.

Renaming the project is good and simple but this doesn't rename the source folder. Here is a step by step of what I have done that worked great in Xcode 4 and 5 thanks to the links below.

REF links:
Rename Project.
Rename Source Folder and other files.

1- Backup your project.

If you are using git, commit any changes, make a copy of the entire project folder and backup in time machine before making any changes (this step is not required but I highly recommended).

2- Open your project.

3- Slow double click or hit enter on the Project name (blue top icon) and rename it to whatever you like.

NOTE: After you rename the project and press ‘enter’ it will suggest to automatically change all project-name-related entries and will allow you to de-select some of them if you want. Select all of them and click ok.

4- Rename the Scheme

a) Click the menu right next to the stop button and select Manage Schemes.

b) Single-slow-click or hit enter on the old name scheme and rename it to whatever you like.

c) Click ok.

5 - Build and run to make sure it works.

NOTES: At this point all of the important project files should be renamed except the comments in the classes created when the project was created nor the source folder. Next we will rename the folder in the file system.

6- Close the project.

7- Rename the main and the source folder.

8- Right click the project bundle .xcodeproj file and select “Show Package Contents” from the context menu. Open the .pbxproj file with any text editor.

9- Search and replace any occurrence of the original folder name with the new folder name.

10- Save the file.

11- Open XCode project, test it.

12- Done.

EDIT 10/11/19:

There is a tool to rename projects in Xcode I haven't tried it enough to comment on it.

How to add extra whitespace in PHP?

To render more than one whitespace on most web browsers use &nbsp; instead of normal white spaces.

echo "<p>Hello &nbsp;&nbsp;&nbsp; punt"; // This will render as Hello   Punt (with 4 white spaces)
echo "<p> Hello       punt"; // This will render as Hello punt (with one space)

For showing data in raw format (with exact number of spaces and "enters") use HTML <pre> tag.

echo "<pre>Hello        punt</pre>"; //Will render exactly as written here (8 white spaces)

Or you can use some CSS to style current block, not to break text or strip spaces (I don't know, but this one)

Any way you do the output will be the same but the browser itself strips double white spaces and renders as one.

How to Specify "Vary: Accept-Encoding" header in .htaccess

To gzip up your font files as well!

add "x-font/otf x-font/ttf x-font/eot"

as in:

AddOutputFilterByType DEFLATE text/html text/plain text/xml application/xml x-font/otf x-font/ttf x-font/eot

WARNING: Can't verify CSRF token authenticity rails


I missed the following line in my application.js

//= require jquery_ujs

I replaced it and its working..

======= UPDATED =========

After 5 years, I am back with Same error, now I have brand new Rails 5.1.6, and I found this post again. Just like circle of life.

Now what was the issue is: Rails 5.1 removed support for jquery and jquery_ujs by default, and added

//= require rails-ujs in application.js

It does the following things:

  1. force confirmation dialogs for various actions;
  2. make non-GET requests from hyperlinks;
  3. make forms or hyperlinks submit data asynchronously with Ajax;
  4. have submit buttons become automatically disabled on form submit to prevent double-clicking. (from:

But why is it not including the csrf token for ajax request? If anyone know about this in detail just comment me. I appreciate that.

Anyway I added the following in my custom js file to make it work (Thanks for other answers to help me reach this code):

$( document ).ready(function() {
    headers: {
      'X-CSRF-Token': Rails.csrfToken()

rails 3.1.0 ActionView::Template::Error (application.css isn't precompiled)

I was having the exact same error in my development environment. In the end all I needed to do in order to fix it was to add:

config.assets.manifest = Rails.root.join("public/assets")

to my config/environments/development.rb file and it fixed it. My final config in development related to assets looks like:

config.assets.compress = false  
config.assets.precompile += %w[bootstrap-alerts.js] #Lots of other space separated files
config.assets.compile = false
config.assets.digest = true
config.assets.manifest = Rails.root.join("public/assets")
config.assets.debug = true

case-insensitive matching in xpath?

This does not work in Chrome Developer tools to locate a element, i am looking to locate the 'Submit' button in the screen


However, using 'translate' to replace all caps to small works as below

//input[translate(@value,'ABCDEFGHIJKLMNOPQRSTUVWXYZ','abcdefghijklmnopqrstuvwxyz') = 'submit']

Update: I just found the reason why 'matches' doesnt work. I am using Chrome with xpath 1.0 which wont understand the syntax 'matches'. It should be xpath 2.0

Django: Display Choice Value

For every field that has choices set, the object will have a get_FOO_display() method, where FOO is the name of the field. This method returns the “human-readable” value of the field.

In Views

person = Person.objects.filter(to_be_listed=True)
context['gender'] = person.get_gender_display()

In Template

{{ person.get_gender_display }}

Documentation of get_FOO_display()

Angularjs prevent form submission when input validation fails


<div class="control-group">
    <input class="btn" type="submit" value="Log in" ng-click="login.onSubmit($event)">

In your controller:

$scope.login = {
    onSubmit: function(event) {
        if (dataIsntValid) {
        else {

I want to remove double quotes from a String

If you only want to remove the boundary quotes:

function stripquotes(a) {
    if (a.charAt(0) === '"' && a.charAt(a.length-1) === '"') {
        return a.substr(1, a.length-2);
    return a;

This approach won't touch the string if it doesn't look like "text in quotes".

Error: Cannot find module 'ejs'

I my case, I just added ejs manually in package.json:

   "name": "myApp"
   "dependencies": {
     "express": "^4.12.2",
     "ejs": "^1.0.0"

And run npm install (may be you need run it with sudo) Please note, that ejs looks views directory by default

Grant SELECT on multiple tables oracle

my suggestion is...create role in oracle using

create role <role_name>;

then assign privileges to that role using

grant select on <table_name> to <role_name>;

then assign that group of privileges via that role to any user by using

grant  <role_name> to <user_name>...;

How to identify numpy types in python?

The solution I've come up with is:

isinstance(y, (np.ndarray, np.generic) )

However, it's not 100% clear that all numpy types are guaranteed to be either np.ndarray or np.generic, and this probably isn't version robust.

Docker how to change repository name or rename image?

docker run -it --name NEW_NAME Existing_name

To change the existing image name.

Create normal zip file programmatically

You can now use the ZipArchive class (System.IO.Compression.ZipArchive), available from .NET 4.5

You have to add System.IO.Compression as a reference.

Example: Generating a zip of PDF files

using (var fileStream = new FileStream(@"C:\temp\", FileMode.CreateNew))
    using (var archive = new ZipArchive(fileStream, ZipArchiveMode.Create, true))
        foreach (var creditNumber in creditNumbers)
            var pdfBytes = GeneratePdf(creditNumber);
            var fileName = "credit_" + creditNumber + ".pdf";
            var zipArchiveEntry = archive.CreateEntry(fileName, CompressionLevel.Fastest);
            using (var zipStream = zipArchiveEntry.Open())
                zipStream.Write(pdfBytes, 0, pdfBytes.Length);

DOM element to corresponding vue.js component

Since in Vue 2.0, no solution seems available, a clean solution that I found is to create a vue-id attribute, and also set it on the template. Then on created and beforeDestroy lifecycle these instances are updated on the global object.


created: function() {
    this._id = generateUid();
    globalRepo[this._id] = this;

beforeDestroy: function() {
    delete globalRepo[this._id]

data: function() {
    return {
        vueId: this._id

AES Encrypt and Decrypt

Code provided by SHS didn't work for me, but this one apparently did (I used a Bridging Header: #import <CommonCrypto/CommonCrypto.h>):

extension String {

    func aesEncrypt(key:String, iv:String, options:Int = kCCOptionPKCS7Padding) -> String? {
        if let keyData = String.Encoding.utf8),
            let data = String.Encoding.utf8),
            let cryptData    = NSMutableData(length: Int((data.count)) + kCCBlockSizeAES128) {

            let keyLength              = size_t(kCCKeySizeAES128)
            let operation: CCOperation = UInt32(kCCEncrypt)
            let algoritm:  CCAlgorithm = UInt32(kCCAlgorithmAES128)
            let options:   CCOptions   = UInt32(options)

            var numBytesEncrypted :size_t = 0

            let cryptStatus = CCCrypt(operation,
                                      (keyData as NSData).bytes, keyLength,
                                      (data as NSData).bytes, data.count,
                                      cryptData.mutableBytes, cryptData.length,

            if UInt32(cryptStatus) == UInt32(kCCSuccess) {
                cryptData.length = Int(numBytesEncrypted)
                let base64cryptString = cryptData.base64EncodedString(options: .lineLength64Characters)
                return base64cryptString

            else {
                return nil
        return nil

    func aesDecrypt(key:String, iv:String, options:Int = kCCOptionPKCS7Padding) -> String? {
        if let keyData = String.Encoding.utf8),
            let data = NSData(base64Encoded: self, options: .ignoreUnknownCharacters),
            let cryptData    = NSMutableData(length: Int((data.length)) + kCCBlockSizeAES128) {

            let keyLength              = size_t(kCCKeySizeAES128)
            let operation: CCOperation = UInt32(kCCDecrypt)
            let algoritm:  CCAlgorithm = UInt32(kCCAlgorithmAES128)
            let options:   CCOptions   = UInt32(options)

            var numBytesEncrypted :size_t = 0

            let cryptStatus = CCCrypt(operation,
                                      (keyData as NSData).bytes, keyLength,
                                      data.bytes, data.length,
                                      cryptData.mutableBytes, cryptData.length,

            if UInt32(cryptStatus) == UInt32(kCCSuccess) {
                cryptData.length = Int(numBytesEncrypted)
                let unencryptedMessage = String(data: cryptData as Data, encoding:String.Encoding.utf8)
                return unencryptedMessage
            else {
                return nil
        return nil


From my ViewController:

 let encoded = message.aesEncrypt(key: keyString, iv: iv)
 let unencode = encoded?.aesDecrypt(key: keyString, iv: iv)

Getting last month's date in php

if you want to get just previous month, then you can use as like following

$prevmonth = date('M Y', strtotime('-1 months'));

if you want to get same days of previous month, Then you can use as like following ..

$prevmonth = date('M Y d', strtotime('-1 months'));

if you want to get last date of previous month , Then you can use as like following ...

$prevmonth = date('M Y t', strtotime('-1 months'));

if you want to get first date of previous month , Then you can use as like following ...

$prevmonth = date('M Y 1', strtotime('-1 months'));

Ruby: character to ascii from a string

Ruby String provides the codepoints method after 1.9.1.

str = 'hello world'
=> [104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100] 

str = "????"
=> [20320, 22909, 19990, 30028]

Should I add the Visual Studio .suo and .user files to source control?

These files contain user preference configurations that are in general specific to your machine, so it's better not to put it in SCM. Also, VS will change it almost every time you execute it, so it will always be marked by the SCM as 'changed'. I don't include either, I'm in a project using VS for 2 years and had no problems doing that. The only minor annoyance is that the debug parameters (execution path, deployment target, etc.) are stored in one of those files (don't know which), so if you have a standard for them you won't be able to 'publish' it via SCM for other developers to have the entire development environment 'ready to use'.

How do I extract specific 'n' bits of a 32-bit unsigned integer in C?

Modulus works to get bottom bits (only), although I think value & 0x1ffff expresses "take the bottom 17 bits" more directly than value % 131072, and so is easier to understand as doing that.

The top 17 bits of a 32-bit unsigned value would be value & 0xffff8000 (if you want them still in their positions at the top), or value >> 15 if you want the top 17 bits of the value in the bottom 17 bits of the result.

Using ffmpeg to encode a high quality video

You need to specify the -vb option to increase the video bitrate, otherwise you get the default which produces smaller videos but with more artifacts.

Try something like this:

ffmpeg -r 25 -i %4d.png -vb 20M myvideo.mpg

Git merge two local branches

Here's a clear picture:

Assuming we have branch-A and branch-B

We want to merge branch-B into branch-A

on branch-B -> A: switch to branch-A

on branch-A: git merge branch-B

How do I request and process JSON with python?

Python's standard library has json and urllib2 modules.

import json
import urllib2

data = json.load(urllib2.urlopen('http://someurl/path/to/json'))

How do I concatenate strings in Swift?

Swift 4.2

You can also use an extension:

extension Array where Element == String? {
    func compactConcate(separator: String) -> String {
        return self.compactMap { $0 }.filter { !$0.isEmpty }.joined(separator: separator)


label.text = [m.firstName, m.lastName].compactConcate(separator: " ")


"The Man"

Making macOS Installer Packages which are Developer ID ready

Our example project has two build targets: and We make a component package for each and combine them into a product archive.

A component package contains payload to be installed by the OS X Installer. Although a component package can be installed on its own, it is typically incorporated into a product archive.

Our tools: pkgbuild, productbuild, and pkgutil

After a successful "Build and Archive" open $BUILT_PRODUCTS_DIR in the Terminal.

$ cd ~/Library/Developer/Xcode/DerivedData/.../InstallationBuildProductsLocation
$ pkgbuild --analyze --root ./ HelloWorldAppComponents.plist
$ pkgbuild --analyze --root ./ HelperAppComponents.plist

This give us the component-plist, you find the value description in the "Component Property List" section. pkgbuild -root generates the component packages, if you don't need to change any of the default properties you can omit the --component-plist parameter in the following command.

productbuild --synthesize results in a Distribution Definition.

$ pkgbuild --root ./ \
    --component-plist HelloWorldAppComponents.plist \
$ pkgbuild --root ./ \
    --component-plist HelperAppComponents.plist \
$ productbuild --synthesize \
    --package HelloWorld.pkg --package Helper.pkg \

In the Distribution.xml you can change things like title, background, welcome, readme, license, and so on. You turn your component packages and distribution definition with this command into a product archive:

$ productbuild --distribution ./Distribution.xml \
    --package-path . \

I recommend to take a look at iTunes Installers Distribution.xml to see what is possible. You can extract "Install iTunes.pkg" with:

$ pkgutil --expand "Install iTunes.pkg" "Install iTunes"

Lets put it together

I usually have a folder named Package in my project which includes things like Distribution.xml, component-plists, resources and scripts.

Add a Run Script Build Phase named "Generate Package", which is set to Run script only when installing:

VERSION=$(defaults read "${BUILT_PRODUCTS_DIR}/${FULL_PRODUCT_NAME}/Contents/Info" CFBundleVersion)

PACKAGE_NAME=`echo "$PRODUCT_NAME" | sed "s/ /_/g"`

pkgbuild --root "${INSTALL_ROOT}" \
    --component-plist "./Package/HelloWorldAppComponents.plist" \
    --scripts "./Package/Scripts" \
    --identifier "com.test.pkg.HelloWorld" \
    --version "$VERSION" \
    --install-location "/" \
pkgbuild --root "${BUILT_PRODUCTS_DIR}/" \
    --component-plist "./Package/HelperAppComponents.plist" \
    --identifier "com.test.pkg.Helper" \
    --version "$VERSION" \
    --install-location "/" \
productbuild --distribution "./Package/Distribution.xml"  \
    --package-path "${BUILT_PRODUCTS_DIR}" \
    --resources "./Package/Resources" \

pkgutil --expand "${TMP1_ARCHIVE}" "${TMP2_ARCHIVE}"
# Patches and Workarounds

pkgutil --flatten "${TMP2_ARCHIVE}" "${TMP3_ARCHIVE}"

productsign --sign "Developer ID Installer: John Doe" \

If you don't have to change the package after it's generated with productbuild you could get rid of the pkgutil --expand and pkgutil --flatten steps. Also you could use the --sign paramenter on productbuild instead of running productsign.

Sign an OS X Installer

Packages are signed with the Developer ID Installer certificate which you can download from Developer Certificate Utility.

They signing is done with the --sign "Developer ID Installer: John Doe" parameter of pkgbuild, productbuild or productsign.

Note that if you are going to create a signed product archive using productbuild, there is no reason to sign the component packages.

Developer Certificate Utility

All the way: Copy Package into Xcode Archive

To copy something into the Xcode Archive we can't use the Run Script Build Phase. For this we need to use a Scheme Action.

Edit Scheme and expand Archive. Then click post-actions and add a New Run Script Action:

In Xcode 6:


PACKAGE_NAME=`echo "$PRODUCT_NAME" | sed "s/ /_/g"`

if [ -f "${PKG}" ]; then
    mkdir "${PACKAGES}"
    cp -r "${PKG}" "${PACKAGES}"

In Xcode 5, use this value for PKG instead:


In case your version control doesn't store Xcode Scheme information I suggest to add this as shell script to your project so you can simple restore the action by dragging the script from the workspace into the post-action.


There are two different kinds of scripting: JavaScript in Distribution Definition Files and Shell Scripts.

The best documentation about Shell Scripts I found in WhiteBox - PackageMaker How-to, but read this with caution because it refers to the old package format.

Apple Silicon

In order for the package to run as arm64, the Distribution file has to specify in its hostArchitectures section that it supports arm64 in addition to x86_64:

<options hostArchitectures="arm64,x86_64" />

Additional Reading

Known Issues and Workarounds

Destination Select Pane

The user is presented with the destination select option with only a single choice - "Install for all users of this computer". The option appears visually selected, but the user needs to click on it in order to proceed with the installation, causing some confusion.

Example showing the installer bug

Apples Documentation recommends to use <domains enable_anywhere ... /> but this triggers the new more buggy Destination Select Pane which Apple doesn't use in any of their Packages.

Using the deprecate <options rootVolumeOnly="true" /> give you the old Destination Select Pane. Example showing old Destination Select Pane

You want to install items into the current user’s home folder.

Short answer: DO NOT TRY IT!

Long answer: REALLY; DO NOT TRY IT! Read Installer Problems and Solutions. You know what I did even after reading this? I was stupid enough to try it. Telling myself I'm sure that they fixed the issues in 10.7 or 10.8.

First of all I saw from time to time the above mentioned Destination Select Pane Bug. That should have stopped me, but I ignored it. If you don't want to spend the week after you released your software answering support e-mails that they have to click once the nice blue selection DO NOT use this.

You are now thinking that your users are smart enough to figure the panel out, aren't you? Well here is another thing about home folder installation, THEY DON'T WORK!

I tested it for two weeks on around 10 different machines with different OS versions and what not, and it never failed. So I shipped it. Within an hour of the release I heart back from users who just couldn't install it. The logs hinted to permission issues you are not gonna be able to fix.

So let's repeat it one more time: We do not use the Installer for home folder installations!

RTFD for Welcome, Read-me, License and Conclusion is not accepted by productbuild.

Installer supported since the beginning RTFD files to make pretty Welcome screens with images, but productbuild doesn't accept them.

Workarounds: Use a dummy rtf file and replace it in the package by after productbuild is done.

Note: You can also have Retina images inside the RTFD file. Use multi-image tiff files for this: tiffutil -cat Welcome.tif Welcome_2x.tif -out FinalWelcome.tif. More details.

Starting an application when the installation is done with a BundlePostInstallScriptPath script:



if [ "${COMMAND_LINE_INSTALL}" = "" ]
    /bin/launchctl asuser "${LOGGED_IN_USER_ID}" /usr/bin/open -g PATH_OR_BUNDLE_ID

exit 0

It is important to run the app as logged in user, not as the installer user. This is done with launchctl asuser uid path. Also we only run it when it is not a command line installation, done with installer tool or Apple Remote Desktop.

How to add a ScrollBar to a Stackpanel

For horizontally oriented StackPanel, explicitly putting both the scrollbar visibilities worked for me to get the horizontal scrollbar.

    <ScrollViewer VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Auto" >
        <StackPanel Orientation="Horizontal" />

How to close a GUI when I push a JButton?

See JFrame.setDefaultCloseOperation(DISPOSE_ON_CLOSE)1. You might also use EXIT_ON_CLOSE, but it is better to explicitly clean up any running threads, then when the last GUI element becomes invisible, the EDT & JRE will end.

The 'button' to invoke this operation is already on a frame.

  1. See this answer to How to best position Swing GUIs? for a demo. of the DISPOSE_ON_CLOSE functionality.

    The JRE will end after all 3 frames are closed by clicking the X button.

How to run a Python script in the background even after I logout SSH?

Here is a simple solution inside python using a decorator:

import os, time

def daemon(func):
    def wrapper(*args, **kwargs):
        if os.fork(): return
        func(*args, **kwargs)
    return wrapper

def my_func(count=10):    
  for i in range(0,count):
     print('parent pid: %d' % os.getppid())

#still in parent thread
#after 2 seconds the function my_func lives on is own

You can of course replace the content of your file in place of my_func.

Bootstrap table without stripe / borders

Install bootstrap either with npm or cdn link

<table class="table table-borderless">
  <th scope="col">#</th>
  <th scope="col">First</th>
  <th scope="col">Last</th>
  <th scope="col">Handle</th>
  <th scope="row">1</th>
  <th scope="row">2</th>
  <th scope="row">3</th>
    <td colspan="2">Larry the Bird</td>

get the reference with this link

how to use JSON.stringify and json_decode() properly

When you use JSON stringify then use html_entity_decode first before json_decode.

$tempData = html_entity_decode($tempData);
$cleanData = json_decode($tempData);

What's the idiomatic syntax for prepending to a short python list?

If you can go the functional way, the following is pretty clear

new_list = [x] + your_list

Of course you haven't inserted x into your_list, rather you have created a new list with x preprended to it.

Bat file to run a .exe at the command prompt

As described here, about the Start command, the following would start your application with the parameters you've specified:

start "svcutil" "svcutil.exe" "language:cs" "out:generatedProxy.cs" "config:app.config" "http://localhost:8000/ServiceModelSamples/service"
  • "svcutil", after the start command, is the name given to the CMD window upon running the application specified. This is a required parameter of the start command.

  • "svcutil.exe" is the absolute or relative path to the application you want to run. Using quotation marks allows you to have spaces in the path.

  • After the application to start has been specified, all the following parameters are interpreted as arguments sent to the application.

Enable CORS in fetch api

Browser have cross domain security at client side which verify that server allowed to fetch data from your domain. If Access-Control-Allow-Origin not available in response header, browser disallow to use response in your JavaScript code and throw exception at network level. You need to configure cors at your server side.

You can fetch request using mode: 'cors'. In this situation browser will not throw execption for cross domain, but browser will not give response in your javascript function.

So in both condition you need to configure cors in your server or you need to use custom proxy server.

TypeError: Can't convert 'int' object to str implicitly

def attributeSelection():
balance = 25
print("Your SP balance is currently 25.")
strength = input("How much SP do you want to put into strength?")
balanceAfterStrength = balance - int(strength)
if balanceAfterStrength == 0:
    print("Your SP balance is now 0.")
elif strength < 0:
    print("That is an invalid input. Restarting attribute selection. Keep an eye on your balance this time!")
elif strength > balance:
    print("That is an invalid input. Restarting attribute selection. Keep an eye on your balance this time!")
elif balanceAfterStrength > 0 and balanceAfterStrength < 26:
    print("Ok. You're balance is now at " + str(balanceAfterStrength) + " skill points.")
    print("That is an invalid input. Restarting attribute selection.")

How to set cookie in node js using express framework?

The order in which you use middleware in Express matters: middleware declared earlier will get called first, and if it can handle a request, any middleware declared later will not get called.

If express.static is handling the request, you need to move your middleware up:

// need cookieParser middleware before we can do anything with cookies

// set a cookie
app.use(function (req, res, next) {
  // check if client sent cookie
  var cookie = req.cookies.cookieName;
  if (cookie === undefined) {
    // no: set a new cookie
    var randomNumber=Math.random().toString();
    res.cookie('cookieName',randomNumber, { maxAge: 900000, httpOnly: true });
    console.log('cookie created successfully');
  } else {
    // yes, cookie was already present 
    console.log('cookie exists', cookie);
  next(); // <-- important!

// let static middleware do its job
app.use(express.static(__dirname + '/public'));

Also, middleware needs to either end a request (by sending back a response), or pass the request to the next middleware. In this case, I've done the latter by calling next() when the cookie has been set.


As of now the cookie parser is a seperate npm package, so instead of using


you need to install it separately using npm i cookie-parser and then use it as:

const cookieParser = require('cookie-parser');

Splitting string with pipe character ("|")

String rat_values = "Food 1 | Service 3 | Atmosphere 3 | Value for money 1 ";
    String[] value_split = rat_values.split("\\|");
    for (String string : value_split) {



Float vs Decimal in ActiveRecord

In Rails 3.2.18, :decimal turns into :integer when using SQLServer, but it works fine in SQLite. Switching to :float solved this issue for us.

The lesson learned is "always use homogeneous development and deployment databases!"

How can I hide/show a div when a button is clicked?

Use JQuery. You need to set-up a click event on your button which will toggle the visibility of your wizard div.

$('#btn').click(function() {

Refer to the JQuery website for more information.

This can also be done without JQuery. Using only standard JavaScript:

<script type="text/javascript">
   function toggle_visibility(id) {
       var e = document.getElementById(id);
       if( == 'block')
 = 'none';
 = 'block';

Then add onclick="toggle_visibility('id_of_element_to_toggle');" to the button that is used to show and hide the div.

Center a position:fixed element

What I use is simple. For example I have a nav bar that is position : fixed so I adjust it to leave a small space to the edges like this.

nav {
right: 1%;
width: 98%;
position: fixed;
margin: auto;
padding: 0;

The idea is to take the remainder percentage of the width "in this case 2%" and use the half of it.

How to set custom favicon in Express?

In Express 4

Install the favicon middleware and then do:

var favicon = require('serve-favicon');

app.use(favicon(__dirname + '/public/images/favicon.ico'));

Or better, using the path module:


(note that this solution will work in express 3 apps as well)

In Express 3

According to the API, .favicon accepts a location parameter:


Most of the time, you might want this (as vsync suggested):

app.use(express.favicon(__dirname + '/public/images/favicon.ico'));

Or better yet, use the path module (as Druska suggested):

app.use(express.favicon(path.join(__dirname, 'public','images','favicon.ico'))); 

Why favicon is better than static

According to the package description:

  1. This module caches the icon in memory to improve performance by skipping disk access.
  2. This module provides an ETag based on the contents of the icon, rather than file system properties.
  3. This module will serve with the most compatible Content-Type.

How do I "Add Existing Item" an entire directory structure in Visual Studio?

You can change your project XML to add existing subfolders and structures automatically into your project like "node_modules" from NPM:

This is for older MSBuild / Visual Studio versions

   <Item Include="$([System.IO.Directory]::GetFiles(&quot;$(MSBuildProjectDirectory)\node_modules&quot;,&quot;*&quot;,SearchOption.AllDirectories))"></Item>

For the current MSBuild / Visual Studio versions:

Just put it in the nodes of the xml:


In this case just change $(MSBuildProjectDirectory)\node_modules to your folder name.

MySQL equivalent of DECODE function in Oracle

you can use if() in place of decode() in mySql as follows This query will print all even id row.

mysql> select id, name from employee where id in
-> (select if(id%2=0,id,null) from employee);

What is the difference between an int and an Integer in Java and C#?

"int" is primitive data-type and "Integer" in Wrapper Class in Java. "Integer" can be used as an argument to a method which requires an object, where as "int" can be used as an argument to a method which requires an integer value, that can be used for arithmetic expression.

Append TimeStamp to a File Name

you can use:


Remove non-ASCII characters from CSV

awk '{ sub("[^a-zA-Z0-9\"!@#$%^&*|_\[](){}", ""); print }' MYinputfile.txt > pipe_out_to_CONVERTED_FILE.txt

How to run Spyder in virtual environment?

There is an option to create virtual environments in Anaconda with required Python version.

conda create -n myenv python=3.4

To activate it :

source activate myenv   # (in linux, you can use . as a shortcut for "source")
activate myenv          # (in windows - note that you should be in your c:\anaconda2 directory)

UPDATE. I have tested it with Ubuntu 18.04. Now you have to install spyder additionally for the new environment with this command (after the activation of the environment with the command above):

conda install spyder

(I have also tested the installation with pip, but for Python 3.4 or older versions, it breaks with the library dependencies error that requires manual installation.)

And now to run Spyder with Python 3.4 just type:


Spyder with Python 3.4

EDIT from a reader:

For a normal opening, use "Anaconda Prompt" > activate myenv > spyder (then the "Anaconda Prompt" must stay open, you cannot use it for other commands, and a force-close will shut down Spyder). This is of course faster than the long load of "Anaconda Navigator" > switch environment > launch Spyder (@adelriosantiago's answer).

Hide Spinner in Input Number - Firefox 29

According to this blog post, you need to set -moz-appearance:textfield; on the input.

input[type=number]::-webkit-inner-spin-button {_x000D_
    -webkit-appearance: none;_x000D_
    margin: 0;_x000D_
input[type=number] {_x000D_
<input type="number" step="0.01"/>

How to retrieve form values from HTTPPOST, dictionary or?

The answers are very good but there is another way in the latest release of MVC and .NET that I really like to use, instead of the "old school" FormCollection and Request keys.

Consider a HTML snippet contained within a form tag that either does an AJAX or FORM POST.

<input type="hidden"   name="TrackingID" 
<input type="text"     name="FirstName"  id="firstnametext" />
<input type="checkbox" name="IsLegal"  value="Do you accept terms and conditions?" />

Your controller will actually parse the form data and try to deliver it to you as parameters of the defined type. I included checkbox because it is a tricky one. It returns text "on" if checked and null if not checked. The requirement though is that these defined variables MUST exists (unless nullable(remember though that string is nullable)) otherwise the AJAX or POST back will fail.

public ActionResult PostBack(int TrackingID, string FirstName, string IsLegal){
    MyData.SaveRequest(TrackingID,FirstName, IsLegal == null ? false : true);

You can also post back a model without using any razor helpers. I have come across that this is needed some times.

public Class HomeModel
  public int HouseNumber { get; set; }
  public string StreetAddress { get; set; }

The HTML markup will simply be ...

<input type="text" name="variableName.HouseNumber" id="whateverid" >

and your controller(Razor Engine) will intercept the Form Variable "variableName" (name is as you like but keep it consistent) and try to build it up and cast it to MyModel.

public ActionResult PostBack(HomeModel variableName){
    postBack.HouseNumber; //The value user entered
    postBack.StreetAddress; //the default value of NULL.

When a controller is expecting a Model (in this case HomeModel) you do not have to define ALL the fields as the parser will just leave them at default, usually NULL. The nice thing is you can mix and match various models on the Mark-up and the post back parse will populate as much as possible. You do not need to define a model on the page or use any helpers.

TIP: The name of the parameter in the controller is the name defined in the HTML mark-up "name=" not the name of the Model but the name of the expected variable in the !

Using List<> is bit more complex in its mark-up.

<input type="text" name="variableNameHere[0].HouseNumber" id="id"           value="0">
<input type="text" name="variableNameHere[1].HouseNumber" id="whateverid-x" value="1">
<input type="text" name="variableNameHere[2].HouseNumber"                   value="2">
<input type="text" name="variableNameHere[3].HouseNumber" id="whateverid22" value="3">

Index on List<> MUST always be zero based and sequential. 0,1,2,3.

public ActionResult PostBack(List<HomeModel> variableNameHere){
     int counter = MyHomes.Count()
     foreach(var home in MyHomes)
     { ... }

Using IEnumerable<> for non zero based and non sequential indices post back. We need to add an extra hidden input to help the binder.

<input type="hidden" name="variableNameHere.Index" value="278">
<input type="text" name="variableNameHere[278].HouseNumber" id="id"      value="3">

<input type="hidden" name="variableNameHere.Index" value="99976">
<input type="text" name="variableNameHere[99976].HouseNumber" id="id3"   value="4">

<input type="hidden" name="variableNameHere.Index" value="777">
<input type="text" name="variableNameHere[777].HouseNumber" id="id23"    value="5">

And the code just needs to use IEnumerable and call ToList()

public ActionResult PostBack(IEnumerable<MyModel> variableNameHere){
     int counter = variableNameHere.ToList().Count()
     foreach(var home in variableNameHere)
     { ... }

It is recommended to use a single Model or a ViewModel (Model contianing other models to create a complex 'View' Model) per page. Mixing and matching as proposed could be considered bad practice, but as long as it works and is readable its not BAD. It does however, demonstrate the power and flexiblity of the Razor engine.

So if you need to drop in something arbitrary or override another value from a Razor helper, or just do not feel like making your own helpers, for a single form that uses some unusual combination of data, you can quickly use these methods to accept extra data.

Difference between multitasking, multithreading and multiprocessing?

Multitasking - This is basically multiprogramming in the context of a single-user interactive environment, in which the OS switches between several programs in main memory so as to give the illusion that several are running at once. Common scheduling algorithms used for multitasking are: Round-Robin, Priority Scheduling (multiple queues), Shortest-Process-Next.

MULTIPROCESSING is like the OS handling the different jobs in main memory in such a way that it gives its time to each and every job when other is busy for some task such as I/O operation. So as long as at least one job needs to execute, the cpu never sit idle. and here it is automatically handled by the OS,

Node.js EACCES error when listening on most ports

Non-privileged user (not root) can't open a listening socket on ports below 1024.

Is there a way to continue broken scp (secure copy) command process in Linux?

If you need to resume an scp transfer from local to remote, try with rsync:

rsync --partial --progress --rsh=ssh local_file user@host:remote_file

Short version, as pointed out by @aurelijus-rozenas:

rsync -P -e ssh local_file user@host:remote_file

In general the order of args for rsync is

rsync [options] SRC DEST

showing that a date is greater than current date

For SQL Server

select *
from YourTable
where DateCol between getdate() and dateadd(d, 90, getdate())

What does AngularJS do better than jQuery?


You go around making your webpage, and keep on putting {{data bindings}} whenever you feel you would have dynamic data. Angular will then provide you a $scope handler, which you can populate (statically or through calls to the web server).

This is a good understanding of data-binding. I think you've got that down.

DOM Manipulation

For simple DOM manipulation, which doesnot involve data manipulation (eg: color changes on mousehover, hiding/showing elements on click), jQuery or old-school js is sufficient and cleaner. This assumes that the model in angular's mvc is anything that reflects data on the page, and hence, css properties like color, display/hide, etc changes dont affect the model.

I can see your point here about "simple" DOM manipulation being cleaner, but only rarely and it would have to be really "simple". I think DOM manipulation is one the areas, just like data-binding, where Angular really shines. Understanding this will also help you see how Angular considers its views.

I'll start by comparing the Angular way with a vanilla js approach to DOM manipulation. Traditionally, we think of HTML as not "doing" anything and write it as such. So, inline js, like "onclick", etc are bad practice because they put the "doing" in the context of HTML, which doesn't "do". Angular flips that concept on its head. As you're writing your view, you think of HTML as being able to "do" lots of things. This capability is abstracted away in angular directives, but if they already exist or you have written them, you don't have to consider "how" it is done, you just use the power made available to you in this "augmented" HTML that angular allows you to use. This also means that ALL of your view logic is truly contained in the view, not in your javascript files. Again, the reasoning is that the directives written in your javascript files could be considered to be increasing the capability of HTML, so you let the DOM worry about manipulating itself (so to speak). I'll demonstrate with a simple example.

This is the markup we want to use. I gave it an intuitive name.

<div rotate-on-click="45"></div>

First, I'd just like to comment that if we've given our HTML this functionality via a custom Angular Directive, we're already done. That's a breath of fresh air. More on that in a moment.

Implementation with jQuery

live demo here (click).

function rotate(deg, elem) {
    webkitTransform: 'rotate('+deg+'deg)', 
    mozTransform: 'rotate('+deg+'deg)', 
    msTransform: 'rotate('+deg+'deg)', 
    oTransform: 'rotate('+deg+'deg)', 
    transform: 'rotate('+deg+'deg)'    

function addRotateOnClick($elems) {
  $elems.each(function(i, elem) {
    var deg = 0;
    $(elem).click(function() {
      deg+= parseInt($(this).attr('rotate-on-click'), 10);
      rotate(deg, this);


Implementation with Angular

live demo here (click).

app.directive('rotateOnClick', function() {
  return {
    restrict: 'A',
    link: function(scope, element, attrs) {
      var deg = 0;
      element.bind('click', function() {
        deg+= parseInt(attrs.rotateOnClick, 10);
          webkitTransform: 'rotate('+deg+'deg)', 
          mozTransform: 'rotate('+deg+'deg)', 
          msTransform: 'rotate('+deg+'deg)', 
          oTransform: 'rotate('+deg+'deg)', 
          transform: 'rotate('+deg+'deg)'    

Pretty light, VERY clean and that's just a simple manipulation! In my opinion, the angular approach wins in all regards, especially how the functionality is abstracted away and the dom manipulation is declared in the DOM. The functionality is hooked onto the element via an html attribute, so there is no need to query the DOM via a selector, and we've got two nice closures - one closure for the directive factory where variables are shared across all usages of the directive, and one closure for each usage of the directive in the link function (or compile function).

Two-way data binding and directives for DOM manipulation are only the start of what makes Angular awesome. Angular promotes all code being modular, reusable, and easily testable and also includes a single-page app routing system. It is important to note that jQuery is a library of commonly needed convenience/cross-browser methods, but Angular is a full featured framework for creating single page apps. The angular script actually includes its own "lite" version of jQuery so that some of the most essential methods are available. Therefore, you could argue that using Angular IS using jQuery (lightly), but Angular provides much more "magic" to help you in the process of creating apps.

This is a great post for more related information: How do I “think in AngularJS” if I have a jQuery background?

General differences.

The above points are aimed at the OP's specific concerns. I'll also give an overview of the other important differences. I suggest doing additional reading about each topic as well.

Angular and jQuery can't reasonably be compared.

Angular is a framework, jQuery is a library. Frameworks have their place and libraries have their place. However, there is no question that a good framework has more power in writing an application than a library. That's exactly the point of a framework. You're welcome to write your code in plain JS, or you can add in a library of common functions, or you can add a framework to drastically reduce the code you need to accomplish most things. Therefore, a more appropriate question is:

Why use a framework?

Good frameworks can help architect your code so that it is modular (therefore reusable), DRY, readable, performant and secure. jQuery is not a framework, so it doesn't help in these regards. We've all seen the typical walls of jQuery spaghetti code. This isn't jQuery's fault - it's the fault of developers that don't know how to architect code. However, if the devs did know how to architect code, they would end up writing some kind of minimal "framework" to provide the foundation (achitecture, etc) I discussed a moment ago, or they would add something in. For example, you might add RequireJS to act as part of your framework for writing good code.

Here are some things that modern frameworks are providing:

  • Templating
  • Data-binding
  • routing (single page app)
  • clean, modular, reusable architecture
  • security
  • additional functions/features for convenience

Before I further discuss Angular, I'd like to point out that Angular isn't the only one of its kind. Durandal, for example, is a framework built on top of jQuery, Knockout, and RequireJS. Again, jQuery cannot, by itself, provide what Knockout, RequireJS, and the whole framework built on top them can. It's just not comparable.

If you need to destroy a planet and you have a Death Star, use the Death star.

Angular (revisited).

Building on my previous points about what frameworks provide, I'd like to commend the way that Angular provides them and try to clarify why this is matter of factually superior to jQuery alone.

DOM reference.

In my above example, it is just absolutely unavoidable that jQuery has to hook onto the DOM in order to provide functionality. That means that the view (html) is concerned about functionality (because it is labeled with some kind of identifier - like "image slider") and JavaScript is concerned about providing that functionality. Angular eliminates that concept via abstraction. Properly written code with Angular means that the view is able to declare its own behavior. If I want to display a clock:



Yes, we need to go to JavaScript to make that mean something, but we're doing this in the opposite way of the jQuery approach. Our Angular directive (which is in it's own little world) has "augumented" the html and the html hooks the functionality into itself.

MVW Architecure / Modules / Dependency Injection

Angular gives you a straightforward way to structure your code. View things belong in the view (html), augmented view functionality belongs in directives, other logic (like ajax calls) and functions belong in services, and the connection of services and logic to the view belongs in controllers. There are some other angular components as well that help deal with configuration and modification of services, etc. Any functionality you create is automatically available anywhere you need it via the Injector subsystem which takes care of Dependency Injection throughout the application. When writing an application (module), I break it up into other reusable modules, each with their own reusable components, and then include them in the bigger project. Once you solve a problem with Angular, you've automatically solved it in a way that is useful and structured for reuse in the future and easily included in the next project. A HUGE bonus to all of this is that your code will be much easier to test.

It isn't easy to make things "work" in Angular.

THANK GOODNESS. The aforementioned jQuery spaghetti code resulted from a dev that made something "work" and then moved on. You can write bad Angular code, but it's much more difficult to do so, because Angular will fight you about it. This means that you have to take advantage (at least somewhat) to the clean architecture it provides. In other words, it's harder to write bad code with Angular, but more convenient to write clean code.

Angular is far from perfect. The web development world is always growing and changing and there are new and better ways being put forth to solve problems. Facebook's React and Flux, for example, have some great advantages over Angular, but come with their own drawbacks. Nothing's perfect, but Angular has been and is still awesome for now. Just as jQuery once helped the web world move forward, so has Angular, and so will many to come.

PHP-FPM doesn't write to error log

I gathered insights from a bunch of answers here and I present a comprehensive solution:

So, if you setup nginx with php5-fpm and log a message using error_log() you can see it in /var/log/nginx/error.log by default.

A problem can arise if you want to log a lot of data (say an array) using error_log(print_r($myArr, true));. If an array is large enough, it seems that nginx will truncate your log entry.

To get around this you can configure fpm ( fpm config) to manage logs. Here are the steps to do so.

  1. Open /etc/php5/fpm/pool.d/www.conf:

    $ sudo nano /etc/php5/fpm/pool.d/www.conf

  2. Uncomment the following two lines by removing ; at the beginning of the line: (error_log is defined here:

    ;php_admin_value[error_log] = /var/log/fpm-php.www.log ;php_admin_flag[log_errors] = on

  3. Create /var/log/fpm-php.www.log:

    $ sudo touch /var/log/fpm-php.www.log;

  4. Change ownership of /var/log/fpm-php.www.log so that php5-fpm can edit it:

    $ sudo chown vagrant /var/log/fpm-php.www.log

    Note: vagrant is the user that I need to give ownership to. You can see what user this should be for you by running $ ps aux | grep php.*www and looking at first column.

  5. Restart php5-fpm:

    $ sudo service php5-fpm restart

Now your logs will be in /var/log/fpm-php.www.log.

MD5 is 128 bits but why is it 32 characters?

I wanted summerize some of the answers into one post.

First, don't think of the MD5 hash as a character string but as a hex number. Therefore, each digit is a hex digit (0-15 or 0-F) and represents four bits, not eight.

Taking that further, one byte or eight bits are represented by two hex digits, e.g. b'1111 1111' = 0xFF = 255.

MD5 hashes are 128 bits in length and generally represented by 32 hex digits.

SHA-1 hashes are 160 bits in length and generally represented by 40 hex digits.

For the SHA-2 family, I think the hash length can be one of a pre-determined set. So SHA-512 can be represented by 128 hex digits.

Again, this post is just based on previous answers.