Programs & Examples On #Aggregate initialization

Initializing a member array in constructor initializer

C++98 doesn't provide a direct syntax for anything but zeroing (or for non-POD elements, value-initializing) the array. For that you just write C(): arr() {}.

I thing Roger Pate is wrong about the alleged limitations of C++0x aggregate initialization, but I'm too lazy to look it up or check it out, and it doesn't matter, does it? EDIT: Roger was talking about "C++03", I misread it as "C++0x". Sorry, Roger. ?

A C++98 workaround for your current code is to wrap the array in a struct and initialize it from a static constant of that type. The data has to reside somewhere anyway. Off the cuff it can look like this:

class C 
    C() : arr( arrData ) {}

     struct Arr{ int elem[3]; };
     Arr arr;
     static Arr const arrData;

C::Arr const C::arrData = {{1, 2, 3}};

How do I check that multiple keys are in a dict in a single pass?

Well, you could do this:

>>> if all (k in foo for k in ("foo","bar")):
...     print "They're there!"
They're there!

How to get value of Radio Buttons?

To Get the Value when the radio button is checked

if (rdbtnSN06.IsChecked == true)
string RadiobuttonContent =Convert.ToString(rdbtnSN06.Content.ToString());
string RadiobuttonContent =Convert.ToString(rdbtnSN07.Content.ToString());


Here's one working syntax for SQL Server 2017:

USE [<yourdb-name>]

FROM <table1-name>
SELECT * FROM <table2-name>

Python Timezone conversion

Please note: The first part of this answer is or version 1.x of pendulum. See below for a version 2.x answer.

I hope I'm not too late!

The pendulum library excels at this and other date-time calculations.

>>> import pendulum
>>> some_time_zones = ['Europe/Paris', 'Europe/Moscow', 'America/Toronto', 'UTC', 'Canada/Pacific', 'Asia/Macao']
>>> heres_a_time = '1996-03-25 12:03 -0400'
>>> pendulum_time = pendulum.datetime.strptime(heres_a_time, '%Y-%m-%d %H:%M %z')
>>> for tz in some_time_zones:
...     tz, pendulum_time.astimezone(tz)
('Europe/Paris', <Pendulum [1996-03-25T17:03:00+01:00]>)
('Europe/Moscow', <Pendulum [1996-03-25T19:03:00+03:00]>)
('America/Toronto', <Pendulum [1996-03-25T11:03:00-05:00]>)
('UTC', <Pendulum [1996-03-25T16:03:00+00:00]>)
('Canada/Pacific', <Pendulum [1996-03-25T08:03:00-08:00]>)
('Asia/Macao', <Pendulum [1996-03-26T00:03:00+08:00]>)

Answer lists the names of the time zones that may be used with pendulum. (They're the same as for pytz.)

For version 2:

  • some_time_zones is a list of the names of the time zones that might be used in a program
  • heres_a_time is a sample time, complete with a time zone in the form '-0400'
  • I begin by converting the time to a pendulum time for subsequent processing
  • now I can show what this time is in each of the time zones in show_time_zones


>>> import pendulum
>>> some_time_zones = ['Europe/Paris', 'Europe/Moscow', 'America/Toronto', 'UTC', 'Canada/Pacific', 'Asia/Macao']
>>> heres_a_time = '1996-03-25 12:03 -0400'
>>> pendulum_time = pendulum.from_format('1996-03-25 12:03 -0400', 'YYYY-MM-DD hh:mm ZZ')
>>> for tz in some_time_zones:
...     tz, pendulum_time.in_tz(tz)
('Europe/Paris', DateTime(1996, 3, 25, 17, 3, 0, tzinfo=Timezone('Europe/Paris')))
('Europe/Moscow', DateTime(1996, 3, 25, 19, 3, 0, tzinfo=Timezone('Europe/Moscow')))
('America/Toronto', DateTime(1996, 3, 25, 11, 3, 0, tzinfo=Timezone('America/Toronto')))
('UTC', DateTime(1996, 3, 25, 16, 3, 0, tzinfo=Timezone('UTC')))
('Canada/Pacific', DateTime(1996, 3, 25, 8, 3, 0, tzinfo=Timezone('Canada/Pacific')))
('Asia/Macao', DateTime(1996, 3, 26, 0, 3, 0, tzinfo=Timezone('Asia/Macao')))

mongodb how to get max value from collections

Simple Explanation, if you have mongo query Response something like below - and you want only highest value from Array-> "Date"

  "_id": "57ee5a708e117c754915a2a2",
  "TotalWishs": 3,
  "Events": [
  "wish": [
    "Cosmic Eldorado  Mountain Bikes, 26-inch (Grey/White)",
    "Asics Men's Gel-Nimbus 18 Black, Snow and Fiery Red Running Shoes - 10 UK/India (45 EU) (11 US)",
    "Suunto Digital Black Dial Unisex Watch - SS018734000"
  "Date": [
  "UserDetails": [
      "createdAt": "2016-09-30T12:28:32.773Z",
      "jeenesFriends": [
      "userImage": "user_profile/Male.png",
      "email": "[email protected]",
      "fullName": "Roopak Kapoor"


***Then you have add

Latest_Wish_CreatedDate: { $max: "$Date"},

somthing like below-

                $project : { _id: 1,
                             TotalWishs : 1 ,
                              wish:1 ,
                               Latest_Wish_CreatedDate: { $max: "$Date"},

And Final Query Response will be below

  "_id": "57ee5a708e117c754915a2a2",
  "TotalWishs": 3,
  "Events": [
  "wish": [
    "Cosmic Eldorado  Mountain Bikes, 26-inch (Grey/White)",
    "Asics Men's Gel-Nimbus 18 Black, Snow and Fiery Red Running Shoes - 10 UK/India (45 EU) (11 US)",
    "Suunto Digital Black Dial Unisex Watch - SS018734000"
  "Wish_CreatedDate": [
  "UserDetails": [
      "createdAt": "2016-09-30T12:28:32.773Z",
      "jeenesFriends": [
      "userImage": "user_profile/Male.png",
      "email": "[email protected]",
      "fullName": "Roopak Kapoor"
  "Latest_Wish_CreatedDate": "2017-03-05T00:00:00.000Z"

"Uncaught SyntaxError: Cannot use import statement outside a module" when importing ECMAScript 6

For me, it was caused before I referred a library (specifically typeORM, using the ormconfig.js file, under the entities key) to the src folder, instead of the dist folder...

   "entities": [
      "src/db/entity/**/*.ts", // Pay attention to "src" and "ts" (this is wrong)

instead of

   "entities": [
      "dist/db/entity/**/*.js", // Pay attention to "dist" and "js" (this is the correct way)

how to clear localstorage,sessionStorage and cookies in javascript? and then retrieve?

The standard Web Storage, does not say anything about the restoring any of these. So there won't be any standard way to do it. You have to go through the way the browsers implement these, or find a way to backup these before you delete them.

How to remove lines in a Matplotlib plot

(using the same example as the guy above)

from matplotlib import pyplot
import numpy
a = numpy.arange(int(1e3))
fig = pyplot.Figure()
ax  = fig.add_subplot(1, 1, 1)
lines = ax.plot(a)

for i, line in enumerate(ax.lines):

Where can I find the Tomcat 7 installation folder on Linux AMI in Elastic Beanstalk?

Not sure if this would be helpful. I am using a similar Amazon Linux AMI, which has tomcat7 living under /usr/share/tomcat7.

If tomcat is already running on your machine you can try:

ps -ef | grep tomcat


ps -ef | grep java

to check where it's running from.

get everything between <tag> and </tag> with php

To retrieve or delete the content of a script tag, even with special cases like <script async>.

$str = '
Some js embed
<script async>
  let job, origin = new Date().getTime()
<span id="OUT"></span>
<button onclick="alert()">RESET</button>
timer experiment

$reg = '/<script([\s\S]*)<\/script>/';

preg_match($reg, $str, $matches);
$match = substr($matches[0], (strpos($matches[0], ">")+1));
$match = str_replace("</script>", "", $match);
echo $match;
  let job, origin = new Date().getTime()
echo "\n---------------------\n";
echo preg_replace($reg, "DELETED", $str);
  Some js embed
  <span id="OUT"></span>
  <button onclick="alert()">RESET</button>
  timer experiment

How to get base url in CodeIgniter 2.*

To use base_url() (shorthand), you have to load the URL Helper first


Or you can autoload it by changing application/config/autoload.php

Or just use


Same applies to site_url().

Also I can see you are missing echo (though its not your current problem), use the code below to solve the problem

<link rel="stylesheet" href="<?php echo base_url(); ?>css/default.css" type="text/css" />

How to get an MD5 checksum in PowerShell

This becomes a one-liner if you download File Checksum Integrity Verifier (FCIV) from Microsoft.

I downloaded FCIV from here: Availability and description of the File Checksum Integrity Verifier utility

Run the following command. I had ten files to check.

Get-ChildItem WTAM*.tar | % {.\fciv $_.Name}

How to change the default browser to debug with in Visual Studio 2008?

I have passed this problem in VS2012. When I can't find "Browse with.." on the right-click of the project, I found it on File Menu -> Browse with. If it doesn't appear, first you have to click on menu bar, then try open file menu again. If it still doesn't appear, you can just go to Quick Launch on the top right of menu bar then type it "Browse with".

Remove by _id in MongoDB console

Well, the _id is an object in your example, so you just need to pass an object

'db.test_users.remove({"_id": { "$oid" : "4d513345cc9374271b02ec6c" }})'

This should work

Edit: Added trailing paren to ensure that it compiled.

How do you disable browser Autocomplete on web form field / input tag?

I've been trying endless solutions, and then I found this:

Instead of autocomplete="off" just simply use autocomplete="false"

As simple as that, and it works like a charm in Google Chrome as well!

How to make an array of arrays in Java

there is the class I mentioned in the comment we had with Sean Patrick Floyd : I did it with a peculiar use which needs WeakReference, but you can change it by any object with ease.

Hoping this can help someone someday :)

import java.lang.ref.WeakReference;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Queue;

 * @author leBenj
public class Array2DWeakRefsBuffered<T>
    private final WeakReference<T>[][] _array;
    private final Queue<T> _buffer;

    private final int _width;

    private final int _height;

    private final int _bufferSize;

    @SuppressWarnings( "unchecked" )
    public Array2DWeakRefsBuffered( int w , int h , int bufferSize )
        _width = w;
        _height = h;
        _bufferSize = bufferSize;
        _array = new WeakReference[_width][_height];
        _buffer = new LinkedList<T>();

     * Tests the existence of the encapsulated object
     * /!\ This DOES NOT ensure that the object will be available on next call !
     * @param x
     * @param y
     * @return
     * @throws IndexOutOfBoundsException
     */public boolean exists( int x , int y ) throws IndexOutOfBoundsException
        if( x >= _width || x < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ x = " + x + "]" );
        if( y >= _height || y < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ y = " + y + "]" );
        if( _array[x][y] != null )
            T elem = _array[x][y].get();
            if( elem != null )
            return true;
        return false;

     * Gets the encapsulated object
     * @param x
     * @param y
     * @return
     * @throws IndexOutOfBoundsException
     * @throws NoSuchElementException
    public T get( int x , int y ) throws IndexOutOfBoundsException , NoSuchElementException
        T retour = null;
        if( x >= _width || x < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ x = " + x + "]" );
        if( y >= _height || y < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ y = " + y + "]" );
        if( _array[x][y] != null )
            retour = _array[x][y].get();
            if( retour == null )
            throw new NoSuchElementException( "Dereferenced WeakReference element at [ " + x + " ; " + y + "]" );
            throw new NoSuchElementException( "No WeakReference element at [ " + x + " ; " + y + "]" );
        return retour;

     * Add/replace an object
     * @param o
     * @param x
     * @param y
     * @throws IndexOutOfBoundsException
    public void set( T o , int x , int y ) throws IndexOutOfBoundsException
        if( x >= _width || x < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (set) : [ x = " + x + "]" );
        if( y >= _height || y < 0 )
            throw new IndexOutOfBoundsException( "Index out of bounds (set) : [ y = " + y + "]" );
        _array[x][y] = new WeakReference<T>( o );

        // store local "visible" references : avoids deletion, works in FIFO mode
        _buffer.add( o );
        if(_buffer.size() > _bufferSize)


Example of how to use it :

// a 5x5 array, with at most 10 elements "bufferized" -> the last 10 elements will not be taken by GC process
Array2DWeakRefsBuffered<Image> myArray = new Array2DWeakRefsBuffered<Image>(5,5,10);
Image img = myArray.set(anImage,0,0);
    System.out.println("Image at 3,3 is still in memory");

casting Object array to Integer array error

Ross, you can use Arrays.copyof() or Arrays.copyOfRange() too.

Integer[] integerArray = Arrays.copyOf(a, a.length, Integer[].class);
Integer[] integerArray = Arrays.copyOfRange(a, 0, a.length, Integer[].class);

Here the reason to hitting an ClassCastException is you can't treat an array of Integer as an array of Object. Integer[] is a subtype of Object[] but Object[] is not a Integer[].

And the following also will not give an ClassCastException.

Object[] a = new Integer[1];
Integer b=1;
Integer[] c = (Integer[]) a;

How do I convert an existing callback API to promises?

Perhaps already answered, but this is how I do it typically:

// given you've defined this `Future` fn somewhere:
const Future = fn => {return new Promise((r,t) => fn(r,t))}

// define an eventFn that takes a promise `resolver`
const eventFn = resolve => {
  // do event related closure actions here. When finally done, call `resolve()`
  something.oneventfired = e => {resolve(e)}

// invoke eventFn in an `async` workflowFn using `Future`
// to obtain a `promise` wrapper
const workflowFn = async () => {await Future(eventFn)}

Especially for things like indexedDb event wrappers to simplify usage.

Or you might find this variation of Future to be more general purpose

class PromiseEx extends Promise {
  resolve(v,...a) {
    this.settled = true; this.settledValue = v;
  reject(v,...a) {
    this.settled = false; this.settledValue = v;
  static Future(fn,...args) {
    let r,t,ft = new PromiseEx((r_,t_) => {r=r_;t=t_})
    ft.resolve_ = r; ft.reject_ = t; fn(ft,...args);

Convert float64 column to int64 in Pandas

This seems to be a little buggy in Pandas 0.23.4?

If there are np.nan values then this will throw an error as expected:

df['col'] = df['col'].astype(np.int64)

But doesn't change any values from float to int as I would expect if "ignore" is used:

df['col'] = df['col'].astype(np.int64,errors='ignore') 

It worked if I first converted np.nan:

df['col'] = df['col'].fillna(0).astype(np.int64)
df['col'] = df['col'].astype(np.int64)

Now I can't figure out how to get null values back in place of the zeroes since this will convert everything back to float again:

df['col']  = df['col'].replace(0,np.nan)

Search for all files in project containing the text 'querystring' in Eclipse

press Ctrl + H . Then choose "File Search" tab.

additional search options

search for resources: Ctrl + Shift + R

search for Java types: Ctrl + Shift + T

How to initialize an array in Java?

You cannot initialize an array like that. In addition to what others have suggested, you can do :

data[0] = 10;
data[1] = 20;
data[9] = 91;

posting hidden value

You should never assume register_global_variables is turned on. Even if it is, it's deprecated and you should never use it that way.

Refer directly to the $_POST or $_GET variables. Most likely your form is POSTing, so you'd want your code to look something along the lines of this:

<input type="hidden" name="date" id="hiddenField" value="<?php echo $_POST['date'] ?>" />

If this doesn't work for you right away, print out the $_POST or $_GET variable on the page that would have the hidden form field and determine exactly what you want and refer to it.

echo "<pre>";
echo "</pre>";

Java: Convert String to TimeStamp

This is what I did:

Timestamp timestamp = Timestamp.valueOf(stringValue);

where stringValue can be any format of Date/Time.

Datatables warning(table id = 'example'): cannot reinitialise data table

You are initializing datatables twice, why?

// Take this off
$(document).ready(function() {
    $( '#example' ).dataTable();
} );
$(document).ready( function() {
  $( '#example' ).dataTable( {
   "fnRowCallback": function( nRow, aData, iDisplayIndex, iDisplayIndexFull ) {
     // Bold the grade for all 'A' grade browsers
     if ( aData[4] == "A" )
       $('td:eq(4)', nRow).html( '<b>A</b>' );
 } );
 } );

Javascript, Time and Date: Getting the current minute, hour, day, week, month, year of a given millisecond time

Regarding number of days in month just use static switch command and check if (year % 4 == 0) in which case February will have 29 days.

Minute, hour, day etc:

var someMillisecondValue = 511111222127;
var date = new Date(someMillisecondValue);
var minute = date.getMinutes();
var hour = date.getHours();
var day = date.getDate();
var month = date.getMonth();
var year = date.getFullYear();
alert([minute, hour, day, month, year].join("\n"));

Regular Expression to get all characters before "-"

You could just use another non-regex based method. Someone gave the suggestion of using Substring, but you could also use Split:

string testString = "my-string";
string[] splitString = testString.Split("-");
string resultingString = splitString[0]; //my

See for another good example.

Node.js global proxy setting

replace {userid} and {password} with your id and password in your organization or login to your machine.

npm config set proxy http://{userid}:{password}@proxyip:8080/
npm config set https-proxy http://{userid}:{password}@proxyip:8080/
npm config set http-proxy http://{userid}:{password}@proxyip:8080/

Static extension methods

No, but you could have something like:

bool b;
b = b.YourExtensionMethod();

Difference between float and decimal data type

I found this useful:

Generally, Float values are good for scientific Calculations, but should not be used for Financial/Monetary Values. For Business Oriented Math, always use Decimal.


What are static factory methods?

NOTE! "The static factory method is NOT the same as the Factory Method pattern" (c) Effective Java, Joshua Bloch.

Factory Method: "Define an interface for creating an object, but let the classes which implement the interface decide which class to instantiate. The Factory method lets a class defer instantiation to subclasses" (c) GoF.

"Static factory method is simply a static method that returns an instance of a class." (c) Effective Java, Joshua Bloch. Usually this method is inside a particular class.

The difference:

The key idea of static factory method is to gain control over object creation and delegate it from constructor to static method. The decision of object to be created is like in Abstract Factory made outside the method (in common case, but not always). While the key (!) idea of Factory Method is to delegate decision of what instance of class to create inside Factory Method. E.g. classic Singleton implementation is a special case of static factory method. Example of commonly used static factory methods:

  • valueOf
  • getInstance
  • newInstance

Pandas sort by group aggregate and column

Groupby A:

In [0]: grp = df.groupby('A')

Within each group, sum over B and broadcast the values using transform. Then sort by B:

In [1]: grp[['B']].transform(sum).sort('B')
2 -2.829710
5 -2.829710
1  0.253651
4  0.253651
0  0.551377
3  0.551377

Index the original df by passing the index from above. This will re-order the A values by the aggregate sum of the B values:

In [2]: sort1 = df.ix[grp[['B']].transform(sum).sort('B').index]

In [3]: sort1
     A         B      C
2  baz -0.528172  False
5  baz -2.301539   True
1  bar -0.611756   True
4  bar  0.865408  False
0  foo  1.624345  False
3  foo -1.072969   True

Finally, sort the 'C' values within groups of 'A' using the sort=False option to preserve the A sort order from step 1:

In [4]: f = lambda x: x.sort('C', ascending=False)

In [5]: sort2 = sort1.groupby('A', sort=False).apply(f)

In [6]: sort2
         A         B      C
baz 5  baz -2.301539   True
    2  baz -0.528172  False
bar 1  bar -0.611756   True
    4  bar  0.865408  False
foo 3  foo -1.072969   True
    0  foo  1.624345  False

Clean up the df index by using reset_index with drop=True:

In [7]: sort2.reset_index(0, drop=True)
     A         B      C
5  baz -2.301539   True
2  baz -0.528172  False
1  bar -0.611756   True
4  bar  0.865408  False
3  foo -1.072969   True
0  foo  1.624345  False

How to find the files that are created in the last hour in unix

find ./ -cTime -1 -type f


find ./ -cmin -60 -type f

Print a variable in hexadecimal in Python

You mean you have a string of bytes in my_hex which you want to print out as hex numbers, right? E.g., let's take your example:

>>> my_string = "deadbeef"
>>> my_hex = my_string.decode('hex')  # python 2 only
>>> print my_hex
Þ ­ ¾ ï

This construction only works on Python 2; but you could write the same string as a literal, in either Python 2 or Python 3, like this:

my_hex = "\xde\xad\xbe\xef"

So, to the answer. Here's one way to print the bytes as hex integers:

>>> print " ".join(hex(ord(n)) for n in my_hex)
0xde 0xad 0xbe 0xef

The comprehension breaks the string into bytes, ord() converts each byte to the corresponding integer, and hex() formats each integer in the from 0x##. Then we add spaces in between.

Bonus: If you use this method with unicode strings (or Python 3 strings), the comprehension will give you unicode characters (not bytes), and you'll get the appropriate hex values even if they're larger than two digits.

Addendum: Byte strings

In Python 3 it is more likely you'll want to do this with a byte string; in that case, the comprehension already returns ints, so you have to leave out the ord() part and simply call hex() on them:

>>> my_hex = b'\xde\xad\xbe\xef'
>>> print(" ".join(hex(n) for n in my_hex))
0xde 0xad 0xbe 0xef

Flutter: Setting the height of the AppBar

You can use the toolbarHeight property of Appbar, it does exactly what you want.

Psql could not connect to server: No such file or directory, 5432 error?

In my case it was the lockfile that was not deleted properly during the last system crash that caused the issue. Deleting it with sudo rm /usr/local/var/postgres/ and restarting Postgres solved the problem.

What is the best way to extract the first word from a string in Java?

The second parameter of the split method is optional, and if specified will split the target string only N times.

For example:

String mystring = "the quick brown fox";
String arr[] = mystring.split(" ", 2);

String firstWord = arr[0];   //the
String theRest = arr[1];     //quick brown fox

Alternatively you could use the substring method of String.

Convert this string to datetime

Use DateTime::createFromFormat

$date = date_create_from_format('d/m/Y:H:i:s', $s);

Should I use SVN or Git?

If your team is already familiar with version and source control softwares like cvs or svn, then, for a simple and small project (such as you claim it is), I would recommend you stick to SVN. I am really comfortable with svn, but for the current e-commerce project I am doing on django, I decided to work on git (I am using git in svn-mode, that is, with a centralised repo that I push to and pull from in order to collaborate with at least one other developer). The other developer is comfortable with SVN, and while others' experiences may differ, both of us are having a really bad time embracing git for this small project. (We are both hardcore Linux users, if it matters at all.)

Your mileage may vary, of course.

How to bring back "Browser mode" in IE11?

Easiest way, especially if in MSDN,,wasted hours of my time, stupid MS

  1. Open the Developer Tools pane. To do this, press F12.
  2. Open the Emulation screen. To do this, press Ctrl+8.
  3. On the Document mode list under Mode, click 9.
  4. On the User agent string list under Mode, click Internet Explorer 9.

Command CompileSwift failed with a nonzero exit code in Xcode 10

Here is the solution: - Go to build settings - Search SWIFT_COMPILATION_MODE - If this is "Whole Module" for Release configuration then change it to "Incremental". - Archive now.

When you change the setting to "Incremental" the process succeeds.

How do I configure Apache 2 to run Perl CGI scripts?

There are two ways to handle CGI scripts, SetHandler and AddHandler.

SetHandler cgi-script

applies to all files in a given context, no matter how they are named, even index.html or style.css.

AddHandler cgi-script .pl

is similar, but applies to files ending in .pl, in a given context. You may choose another extension or several, if you like.

Additionally, the CGI module must be loaded and Options +ExecCGI configured. To activate the module, issue

a2enmod cgi

and restart or reload Apache. Finally, the Perl CGI script must be executable. So the execute bits must be set

chmod a+x

and it should start with

#! /usr/bin/perl

as its first line.

When you use SetHandler or AddHandler (and Options +ExecCGI) outside of any directive, it is applied globally to all files. But you may restrict the context to a subset by enclosing these directives inside, e.g. Directory

<Directory /path/to/some/cgi-dir>
    SetHandler cgi-script
    Options +ExecCGI

Now SetHandler applies only to the files inside /path/to/some/cgi-dir instead of all files of the web site. Same is with AddHandler inside a Directory or Location directive, of course. It then applies to the files inside /path/to/some/cgi-dir, ending in .pl.

symbol(s) not found for architecture i386

I had used a CLGeocoder without adding a Core.Location Framework. Basically this error can mean multiple things. I hope this helps someone else.

PHP: Show yes/no confirmation dialog

The best way that I found is here.


<a href="delete.cfm" onclick="return confirm('Are you sure you want to delete?');">Delete</a>


$(document).ready(function() {
    $('a[data-confirm]').click(function(ev) {
        var href = $(this).attr('href');
        if (!$('#dataConfirmModal').length) {
            $('body').append('<div id="dataConfirmModal" class="modal" role="dialog" aria-labelledby="dataConfirmLabel" aria-hidden="true"><div class="modal-header"><button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button><h3 id="dataConfirmLabel">Please Confirm</h3></div><div class="modal-body"></div><div class="modal-footer"><button class="btn" data-dismiss="modal" aria-hidden="true">Cancel</button><a class="btn btn-primary" id="dataConfirmOK">OK</a></div></div>');
        $('#dataConfirmOK').attr('href', href);
        return false;

You should add Jquery and Bootstrap for this to work.

Firebase cloud messaging notification not received by device

I've been working through this entire post and others as well as tutorial videos without being able to solve my problem of not receiving messages, the registration token however worked.

Until then I had only been testing the app on the emulator. After trying it on a physical phone it instantly worked without any prior changes to the project.

How do I calculate power-of in C#?

Following is the code calculating power of decimal value for RaiseToPower for both -ve and +ve values.

public decimal Power(decimal number, decimal raiseToPower)
            decimal result = 0;
            if (raiseToPower < 0)
                raiseToPower *= -1;
                result = 1 / number;
                for (int i = 1; i < raiseToPower; i++)
                    result /= number;
                result = number;
                for (int i = 0; i <= raiseToPower; i++)
                    result *= number;
            return result;

Formatting a float to 2 decimal places

As already mentioned, you will need to use a formatted result; which is all done through the Write(), WriteLine(), Format(), and ToString() methods.

What has not been mentioned is the Fixed-point Format which allows for a specified number of decimal places. It uses an 'F' and the number following the 'F' is the number of decimal places outputted, as shown in the examples.

Console.WriteLine("{0:F2}", 12);    // 12.00 - two decimal places
Console.WriteLine("{0:F0}", 12.3);  // 12 - ommiting fractions

How to hide a button programmatically?

You can use the following code:

playButton = (Button) findViewById(;
playButton.setOnClickListener(new OnClickListener() {
    public void onClick(View v) {
        //when play is clicked show stop button and hide play button

Linux/Unix command to determine if process is running?

You should know the PID of your process.

When you launch it, its PID will be recorded in the $! variable. Save this PID into a file.

Then you will need to check if this PID corresponds to a running process. Here's a complete skeleton script:


if [ -f $FILE ];
   PID=$(cat $FILE)

ps -o pid= -p $PID
if [ $? -eq 0 ]; then
  echo "Process already running."  
  echo "Starting process."
  run_my_app &
  echo $! > $FILE

Based on the answer of peterh. The trick for knowing if a given PID is running is in the ps -o pid= -p $PID instruction.

Convert bytes to bits in python

input_str = "ABC"
[bin(byte) for byte in bytes(input_str, "utf-8")]

Will give:

['0b1000001', '0b1000010', '0b1000011']

Form Google Maps URL that searches for a specific places near specific coordinates

You can use the new URL for Google Maps:,-74.86084,18z equivalent to,-74.86084.

39.774769 is the latitude and -74.86084 is longitude and 18z is 18 zoom level.

Update Fragment from ViewPager

i had 4 Fragments in the ViewPager, but i wanted to update just one Fragment "FavoriteFragment" at the position 0 of the viewPager, every time the user click on this fragment. but none of the codes above helped me reload just the one Fragment i want. so i tried this and it works for me:

in my FavoriteFragment i overrided onResume()

    public void onResume() {
        updateUI(); // code to update the UI in the fragment

in the Activity hosting the viewPager override addOnPageChangeListener() and add this code

mViewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            public void onPageSelected(int position) {

                if(position == 0) { // 0 = the first fragment in the ViewPager, in this case, the fragment i want to refresh its UI
                    FavoritesFragment fragment = (FavoritesFragment) mViewPager.getAdapter().instantiateItem(mViewPager, position); 
                    fragment.onResume(); // here i call the onResume of the fragment, where i have the method updateUI() to update its UI

and it works perfect for me, to refresh/reload just the one fragment i want.

How to create a multi line body in C# System.Net.Mail.MailMessage

I usually like a StringBuilder when I'm working with MailMessage. Adding new lines is easy (via the AppendLine method), and you can simply set the Message's Body equal to StringBuilder.ToString() (... for the instance of StringBuilder).

StringBuilder result = new StringBuilder("my content here...");
result.AppendLine(); // break line

"Could not find Developer Disk Image"

I am facing the same issue on Xcode 7.3 and my device version is iOS 10.

This error is shown when your Xcode is old and the related device you are using is updated to latest version. First of all, install the latest Xcode version.

We can solve this issue by following the below steps:-

  • Open Finder select Applications
  • Right click on Xcode 8, select "Show Package Contents", "Contents", "Developer", "Platforms", "iPhoneOS.Platform", "Device Support"
  • Copy the 10.0 folder (or above for later version).
  • Back in Finder select Applications again
  • Right click on Xcode 7.3, select "Show Package Contents", "Contents", "Developer", "Platforms", "iPhoneOS.Platform", "Device Support"
  • Paste the 10.0 folder

If everything worked properly, your Xcode has a new developer disk image. Close the finder now, and quit your Xcode. Open your Xcode and the error will be gone. Now you can connect your latest device to old Xcode versions.


How do you convert Html to plain text?

If you have data that has HTML tags and you want to display it so that a person can SEE the tags, use HttpServerUtility::HtmlEncode.

If you have data that has HTML tags in it and you want the user to see the tags rendered, then display the text as is. If the text represents an entire web page, use an IFRAME for it.

If you have data that has HTML tags and you want to strip out the tags and just display the unformatted text, use a regular expression.

Is it possible to set the stacking order of pseudo-elements below their parent element?

There are two issues are at play here:

  1. The CSS 2.1 specification states that "The :beforeand :after pseudo-elements elements interact with other boxes, such as run-in boxes, as if they were real elements inserted just inside their associated element." Given the way z-indexes are implemented in most browsers, it's pretty difficult (read, I don't know of a way) to move content lower than the z-index of their parent element in the DOM that works in all browsers.

  2. Number 1 above does not necessarily mean it's impossible, but the second impediment to it is actually worse: Ultimately it's a matter of browser support. Firefox didn't support positioning of generated content at all until FF3.6. Who knows about browsers like IE. So even if you can find a hack to make it work in one browser, it's very likely it will only work in that browser.

The only thing I can think of that's going to work across browsers is to use javascript to insert the element rather than CSS. I know that's not a great solution, but the :before and :after pseudo-selectors just really don't look like they're gonna cut it here.

Failed to auto-configure a DataSource: 'spring.datasource.url' is not specified

Add your dependencies like mongodb,web,jpa. Delete/clear the remainings.


how to change the dist-folder path in angular-cli after 'ng build'

The more current way of this is to update the outDir property in .angular-cli.json.

The ng build command argument --output-path (or -op for short) is still supported also, which can be useful if you want multiple values, you can save them in your package.json as npm scripts.

Beware: The .angular-cli.json property is NOT called output-path like the currently-accepted answer by @cwill747 says. That's the ng build argument only.

It's called outDir as mentioned above, and it's a under the apps property.



(December 2017)

1-year after adding this answer, someone added a new answer with essentially same information, and the Original Poster changed the accepted answer to the 1-year-late answer containing same information in the first line of this one.

how to set the background image fit to browser using html

I encounter same trouble as you, this is my solution.

body {
    background-image: url(image/background.jpg);
    background-size: 100% 100%;

org.apache.poi.POIXMLException: org.apache.poi.openxml4j.exceptions.InvalidFormatException:

Try this:

package my_default;

import java.util.Iterator;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class Test {

    public static void main(String[] args) {
        try {
        // Create Workbook instance holding reference to .xlsx file
        XSSFWorkbook workbook = new XSSFWorkbook();

        // Get first/desired sheet from the workbook
        XSSFSheet sheet = createSheet(workbook, "Sheet 1", false);

        // XSSFSheet sheet = workbook.getSheetAt(1);//Don't use this line
        // because you get Sheet index (1) is out of range (no sheets)

        //Write some information in the cells or do what you want
        XSSFRow row1 = sheet.createRow(0);
        XSSFCell r1c2 = row1.createCell(0);
        XSSFCell r1c3 = row1.createCell(1);

        //Save excel to HDD Drive
        File pathToFile = new File("D:\\test.xlsx");
        if (!pathToFile.exists()) {
        FileOutputStream fos = new FileOutputStream(pathToFile);
    } catch (Exception e) {

private static XSSFSheet createSheet(XSSFWorkbook wb, String prefix, boolean isHidden) {
    XSSFSheet sheet = null;
    int count = 0;

    for (int i = 0; i < wb.getNumberOfSheets(); i++) {
        String sName = wb.getSheetName(i);
        if (sName.startsWith(prefix))

    if (count > 0) {
        sheet = wb.createSheet(prefix + count);
    } else
        sheet = wb.createSheet(prefix);

    if (isHidden)
        wb.setSheetHidden(wb.getNumberOfSheets() - 1, XSSFWorkbook.SHEET_STATE_VERY_HIDDEN);

        return sheet;


How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly?

If you want to filter rows by a certain number of columns with null values, you may use this:

df.iloc[df[(df.isnull().sum(axis=1) >= qty_of_nuls)].index]

So, here is the example:

Your dataframe:

>>> df = pd.DataFrame([range(4), [0, np.NaN, 0, np.NaN], [0, 0, np.NaN, 0], range(4), [np.NaN, 0, np.NaN, np.NaN]])
>>> df
     0    1    2    3
0  0.0  1.0  2.0  3.0
1  0.0  NaN  0.0  NaN
2  0.0  0.0  NaN  0.0
3  0.0  1.0  2.0  3.0
4  NaN  0.0  NaN  NaN

If you want to select the rows that have two or more columns with null value, you run the following:

>>> qty_of_nuls = 2
>>> df.iloc[df[(df.isnull().sum(axis=1) >=qty_of_nuls)].index]
     0    1    2   3
1  0.0  NaN  0.0 NaN
4  NaN  0.0  NaN NaN

How to get controls in WPF to fill available space?

Use the HorizontalAlignment and VerticalAlignment layout properties. They control how an element uses the space it has inside its parent when more room is available than it required by the element.

The width of a StackPanel, for example, will be as wide as the widest element it contains. So, all narrower elements have a bit of excess space. The alignment properties control what the child element does with the extra space.

The default value for both properties is Stretch, so the child element is stretched to fill all available space. Additional options include Left, Center and Right for HorizontalAlignment and Top, Center and Bottom for VerticalAlignment.

Automatically scroll down chat div

const messages = document.getElementById('messages');_x000D_
function appendMessage() {_x000D_
 const message = document.getElementsByClassName('message')[0];_x000D_
  const newMessage = message.cloneNode(true);_x000D_
function getMessages() {_x000D_
 // Prior to getting your messages._x000D_
  shouldScroll = messages.scrollTop + messages.clientHeight === messages.scrollHeight;_x000D_
   * Get your messages, we'll just simulate it by appending a new one syncronously._x000D_
  // After getting your messages._x000D_
  if (!shouldScroll) {_x000D_
function scrollToBottom() {_x000D_
  messages.scrollTop = messages.scrollHeight;_x000D_
setInterval(getMessages, 100);
#messages {_x000D_
  height: 200px;_x000D_
  overflow-y: auto;_x000D_
<div id="messages">_x000D_
  <div class="message">_x000D_
    Hello world_x000D_

Check input value length

<input type='text' minlength=3 /><br />

if browser supports html5,

it will automatical be validate attributes(minlength) in tag

but Safari(iOS) doesn't working

How to specify legend position in matplotlib in graph coordinates

According to the matplotlib legend documentation:

The location can also be a 2-tuple giving the coordinates of the lower-left corner of the legend in axes coordinates (in which case bbox_to_anchor will be ignored).

Thus, one could use:

plt.legend(loc=(x, y))

to set the legend's lower left corner to the specified (x, y) position.

How to make a gui in python

For a start I would recommend wxglade. It is a rather easy to use tool that helps you build wxPython applications. wx is already cross platform and can be packaged with tools like py2exe or py2app.

Sleeping in a batch file

The usage of ping is good, as long as you just want to "wait for a bit". This since you are dependent on other functions underneath, like your network working and the fact that there is nothing answering on ;-) Maybe it is not very likely it fails, but it is not impossible...

If you want to be sure that you are waiting exactly the specified time, you should use the sleep functionality (which also have the advantage that it doesn't use CPU power or wait for a network to become ready).

To find an already made executable for sleep is the most convenient way. Just drop it into your Windows folder or any other part of your standard path and it is always available.

Otherwise, if you have a compiling environment you can easily make one yourself. The Sleep function is available in kernel32.dll, so you just need to use that one. :-) For VB / VBA declare the following in the beginning of your source to declare a sleep function:

private Declare Sub Sleep Lib "kernel32" Alias "Sleep" (byval dwMilliseconds as Long)

For C#:

static extern void Sleep(uint dwMilliseconds);

You'll find here more about this functionality (available since Windows 2000) in Sleep function (MSDN).

In standard C, sleep() is included in the standard library and in Microsoft's Visual Studio C the function is named Sleep(), if memory serves me. ;-) Those two takes the argument in seconds, not in milliseconds as the two previous declarations.

Cannot find the object because it does not exist or you do not have permissions. Error in SQL Server

Are you sure that you are executing the script against the correct database? In SQL Server Management studio you can change the database you are running the query against in a drop-down box on one of the toolbars, or you can start your query with this:

USE SomeDatabase

Sort an ArrayList based on an object field

You can use the Bean Comparator to sort on any property in your custom class.

Share application "link" in Android

Actually the best way to sheared you app between users , google (firebase) proved new technology Firebase Dynamic Link Through several lines you can make it this is documentation and the code is

  Uri dynamicLinkUri = dynamicLink.getUri();
      Task<ShortDynamicLink> shortLinkTask = FirebaseDynamicLinks.getInstance().createDynamicLink()
            .addOnCompleteListener(this, new OnCompleteListener<ShortDynamicLink>() {
                public void onComplete(@NonNull Task<ShortDynamicLink> task) {
                    if (task.isSuccessful()) {
                        // Short link created
                        Uri shortLink = task.getResult().getShortLink();
                        Uri flowchartLink = task.getResult().getPreviewLink();
                        Intent intent = new Intent();
                        intent.putExtra(Intent.EXTRA_TEXT,  shortLink.toString());
                    } else {
                        // Error
                        // ...

Overwriting my local branch with remote branch

git reset --hard

This is to revert all your local changes to the origin head

Recursively counting files in a Linux directory

Since filenames in UNIX may contain newlines (yes, newlines), wc -l might count too many files. I would print a dot for every file and then count the dots:

find DIR_NAME -type f -printf "." | wc -c

AngularJS view not updating on model change

Do not use $scope.$apply() angular already uses it and it can result in this error

$rootScope:inprog Action Already In Progress

if you use twice, use $timeout or interval

Connection to SQL Server Works Sometimes

In my case above all options were already there.

Solved it by increasing Connection Time-out = 30.SQL Server management Studio


While there is probably an agnostic way to describe these, it does seem to be conflicting with various statements from answers to websites.

Let's be very clear and direct here. If you are a .NET developer working with Web API, the facts are (from the Microsoft API documentation),

1. PUT = UPDATE (/api/products/id)
2. MCSD Exams 2014 -  UPDATE = PUT, there are **NO** multiple answers for that question period.

Sure you "can" use "POST" to update, but just follow the conventions laid out for you with your given framework. In my case it is .NET / Web API, so PUT is for UPDATE there is no debate.

I hope this helps any Microsoft developers that read all comments with Amazon and Sun/Java website links.

Using find command in bash script

Welcome to bash. It's an old, dark and mysterious thing, capable of great magic. :-)

The option you're asking about is for the find command though, not for bash. From your command line, you can man find to see the options.

The one you're looking for is -o for "or":

  list="$(find /home/user/Desktop -name '*.bmp' -o -name '*.txt')"

That said ... Don't do this. Storage like this may work for simple filenames, but as soon as you have to deal with special characters, like spaces and newlines, all bets are off. See ParsingLs for details.

$ touch 'one.txt' 'two three.txt' 'foo.bmp'
$ list="$(find . -name \*.txt -o -name \*.bmp -type f)"
$ for file in $list; do if [ ! -f "$file" ]; then echo "MISSING: $file"; fi; done
MISSING: ./two
MISSING: three.txt

Pathname expansion (globbing) provides a much better/safer way to keep track of files. Then you can also use bash arrays:

$ a=( *.txt *.bmp )
$ declare -p a
declare -a a=([0]="one.txt" [1]="two three.txt" [2]="foo.bmp")
$ for file in "${a[@]}"; do ls -l "$file"; done
-rw-r--r--  1 ghoti  staff  0 24 May 16:27 one.txt
-rw-r--r--  1 ghoti  staff  0 24 May 16:27 two three.txt
-rw-r--r--  1 ghoti  staff  0 24 May 16:27 foo.bmp

The Bash FAQ has lots of other excellent tips about programming in bash.

Output a NULL cell value in Excel

I've been frustrated by this problem as well. Find/Replace can be helpful though, because if you don't put anything in the "replace" field it will replace with an -actual- NULL. So the steps would be something along the lines of:

1: Place some unique string in your formula in place of the NULL output (i like to use a password-like string)

2: Run your formula

3: Open Find/Replace, and fill in the unique string as the search value. Leave "replace with" blank

4: Replace All

Obviously, this has limitations. It only works when the context allows you to do a find/replace, so for more dynamic formulas this won't help much. But, I figured I'd put it up here anyway.

Style jQuery autocomplete in a Bootstrap input field

I found the following css in order to style a Bootstrap input for a jquery autocomplete:

.ui-autocomplete {
    position: absolute;
    top: 100%;
    left: 0;
    z-index: 1000;
    float: left;
    display: none;
    min-width: 160px;
    _width: 160px;
    padding: 4px 0;
    margin: 2px 0 0 0;
    list-style: none;
    background-color: #ffffff;
    border-color: #ccc;
    border-color: rgba(0, 0, 0, 0.2);
    border-style: solid;
    border-width: 1px;
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    border-radius: 5px;
    -webkit-box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
    -moz-box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
    -webkit-background-clip: padding-box;
    -moz-background-clip: padding;
    background-clip: padding-box;
    *border-right-width: 2px;
    *border-bottom-width: 2px;
.ui-menu-item > a.ui-corner-all {
    display: block;
    padding: 3px 15px;
    clear: both;
    font-weight: normal;
    line-height: 18px;
    color: #555555;
    white-space: nowrap;
.ui-state-hover, &.ui-state-active {
      color: #ffffff;
      text-decoration: none;
      background-color: #0088cc;
      border-radius: 0px;
      -webkit-border-radius: 0px;
      -moz-border-radius: 0px;
      background-image: none;

Foreach with JSONArray and JSONObject

Seems like you can't iterate through JSONArray with a for each. You can loop through your JSONArray like this:

for (int i=0; i < arr.length(); i++) {


What is the difference between “int” and “uint” / “long” and “ulong”?

It's been a while since I C++'d but these answers are off a bit.

As far as the size goes, 'int' isn't anything. It's a notional value of a standard integer; assumed to be fast for purposes of things like iteration. It doesn't have a preset size.

So, the answers are correct with respect to the differences between int and uint, but are incorrect when they talk about "how large they are" or what their range is. That size is undefined, or more accurately, it will change with the compiler and platform.

It's never polite to discuss the size of your bits in public.

When you compile a program, int does have a size, as you've taken the abstract C/C++ and turned it into concrete machine code.

So, TODAY, practically speaking with most common compilers, they are correct. But do not assume this.

Specifically: if you're writing a 32 bit program, int will be one thing, 64 bit, it can be different, and 16 bit is different. I've gone through all three and briefly looked at 6502 shudder

A brief google search shows this: This is also good info:

use int if you really don't care how large your bits are; it can change.

Use size_t and ssize_t if you want to know how large something is.

If you're reading or writing binary data, don't use int. Use a (usually platform/source dependent) specific keyword. WinSDK has plenty of good, maintainable examples of this. Other platforms do too.

I've spent a LOT of time going through code from people that "SMH" at the idea that this is all just academic/pedantic. These ate the people that write unmaintainable code. Sure, it's easy to use type 'int' and use it without all the extra darn typing. It's a lot of work to figure out what they really meant, and a bit mind-numbing.

It's crappy coding when you mix int.

use int and uint when you just want a fast integer and don't care about the range (other than signed/unsigned).

Performing Breadth First Search recursively

Here is a BFS recursive traversal Python implementation, working for a graph with no cycle.

def bfs_recursive(level):
     @params level: List<Node> containing the node for a specific level.
    next_level = []
    for node in level:
        for child_node in node.adjency_list:
    if len(next_level) != 0:

class Node:
    def __init__(self, value):
        self.value = value
        self.adjency_list = []

Tokenizing Error: java.util.regex.PatternSyntaxException, dangling metacharacter '*'

The first answer covers it.

Im guessing that somewhere down the line you may decide to store your info in a different class/structure. In that case you probably wouldn't want the results going in to an array from the split() method.

You didn't ask for it, but I'm bored, so here is an example, hope it's helpful.

This might be the class you write to represent a single person:

class Person {
            public String firstName;
            public String lastName;
            public int id;
            public int age;

      public Person(String firstName, String lastName, int id, int age) {
         this.firstName = firstName;
         this.lastName = lastName; = id;
         this.age = age;
      // Add 'get' and 'set' method if you want to make the attributes private rather than public.

Then, the version of the parsing code you originally posted would look something like this: (This stores them in a LinkedList, you could use something else like a Hashtable, etc..)

    String ruta="";
    BufferedReader reader = new BufferedReader(new FileReader(ruta));

    LinkedList<Person> list = new LinkedList<Person>();

    String line = null;         
    while ((line=reader.readLine())!=null)
        if (!(line.equals("%")))
            StringTokenizer st = new StringTokenizer(line, "*");
            if (st.countTokens() == 4)          
                list.add(new Person(st.nextToken(), st.nextToken(), Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken)));         
                // whatever you want to do to account for an invalid entry
                  // in your file. (not 4 '*' delimiters on a line). Or you
                  // could write the 'if' clause differently to account for it          

How to find the maximum value in an array?

Iterate over the Array. First initialize the maximum value to the first element of the array and then for each element optimize it if the element under consideration is greater.

Sum function in VBA


won't work because worksheet functions (when actually used on a worksheet) don't understand Range or Cell


Range("A1").Formula="=SUM(" & Range(Cells(2,1),Cells(3,2)).Address(False,False) & ")"

What is the correct way of reading from a TCP socket in C/C++?

This is an article that I always refer to when working with sockets..


It will show you how to reliably use 'select()' and contains some other useful links at the bottom for further info on sockets.

Most simple code to populate JTable from ResultSet

The JTable constructor accepts two arguments 2dimension Object Array for the data, and String Array for the column names.


import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;

public class Test6 extends JFrame {

    public Test6(){     
        Mpanel m = new Mpanel();

    class Mpanel extends JPanel {       

        JTable mTable;
        private Object[][] cells = {{"Vivek",10.00},{"Vishal",20.00}};
        private String[] columnNames = { "Planet", "Radius" };
        JScrollPane mScroll;

        public Mpanel(){

        public void setComponent(){
            mTable = new JTable(cells,columnNames);
            mScroll = new JScrollPane(mTable);


    public static void main(String[] args){     
        new Test6().setVisible(true);

Renaming a branch in GitHub

Here is what worked for me:

  1. Create the new branch first:

    git push github newname :refs/heads/newname
  2. On the GitHub site, go to settings and change the Default branch to newname

  3. Delete the oldname

    git push github --delete oldname

How to change the remote a branch is tracking?

I've found @critikaster's post helpful, except that I had to perform these commands with GIT 2.21:

$ git remote set-url origin https://some_url/some_repo
$ git push --set-upstream origin master

Fast ceiling of an integer division in C / C++

For positive numbers

unsigned int x, y, q;

To round up ...

q = (x + y - 1) / y;

or (avoiding overflow in x+y)

q = 1 + ((x - 1) / y); // if x != 0

In-memory size of a Python structure

One can also make use of the tracemalloc module from the Python standard library. It seems to work well for objects whose class is implemented in C (unlike Pympler, for instance).

How to fix 'Notice: Undefined index:' in PHP form action

short way, you can use Ternary Operators

$filename = !empty($_POST['filename'])?$_POST['filename']:'-';

Specify JDK for Maven to use

As u said "Plus, I don't want to use 1.6 for all maven builds."....So better I will say modify your pom file and specify which jdk version to use.


It will ensure that your particular project uses that version of jdk.

How do I extend a class with c# extension methods?

Extension methods are syntactic sugar for making static methods whose first parameter is an instance of type T look as if they were an instance method on T.

As such the benefit is largely lost where you to make 'static extension methods' since they would serve to confuse the reader of the code even more than an extension method (since they appear to be fully qualified but are not actually defined in that class) for no syntactical gain (being able to chain calls in a fluent style within Linq for example).

Since you would have to bring the extensions into scope with a using anyway I would argue that it is simpler and safer to create:

public static class DateTimeUtils
    public static DateTime Tomorrow { get { ... } }

And then use this in your code via:

WriteLine("{0}", DateTimeUtils.Tomorrow)

Getting scroll bar width using JavaScript

I think this will be simple and fast -

var scrollWidth= window.innerWidth-$(document).width()

Attach event to dynamic elements in javascript

var __ = function(){
    this.context  = [];
    var self = this;
    this.selector = function( _elem, _sel ){
        return _elem.querySelectorAll( _sel );
          this.on = function( _event, _element, _function ){
              this.context = self.selector( document, _element );
              document.addEventListener( _event, function(e){
                  var elem =;
                  while ( elem != null ) {
                      if( "#" == _element || self.isClass( elem, _element ) || self.elemEqal( elem ) ){
                          _function( e, elem );
                      elem = elem.parentElement;
              }, false );

     this.isClass = function( _elem, _class ){
        var names = _elem.className.trim().split(" ");
        for( = 0; < names.length; ){
            names[] = "."+names[];
        return names.indexOf( _class ) != -1 ? true : false;

    this.elemEqal = function( _elem ){
        var flg = false;
        for( = 0; < this.context.length; ){
            if( this.context[] === _elem && !flg ){
                flg = true;
        return flg;


    function _( _sel_string ){
        var new_selc = new __( _sel_string );
        return new_selc;

Now you can register event like,

_( document ).on( "click", "#brnPrepend", function( _event, _element ){
      console.log( _event );
      console.log( _element );
      // Todo


Browser Support

chrome - 4.0, Edge - 9.0, Firefox - 3.5 Safari - 3.2, Opera - 10.0 and above

Matching an optional substring in a regex


Note the escaped parentheses, and the ? (zero or once) quantifiers. Any of the groups you don't want to capture can be (?: non-capture groups).

I agree about the spaces. \s is a better option there. I also changed the quantifier to insure there are digits at the beginning. As far as newlines, that would depend on context: if the file is parsed line by line it won't be a problem. Another option is to anchor the start and end of the line (add a ^ at the front and a $ at the end).

TensorFlow ValueError: Cannot feed value of shape (64, 64, 3) for Tensor u'Placeholder:0', which has shape '(?, 64, 64, 3)'

image has a shape of (64,64,3).

Your input placeholder _x have a shape of (?, 64,64,3).

The problem is that you're feeding the placeholder with a value of a different shape.

You have to feed it with a value of (1, 64, 64, 3) = a batch of 1 image.

Just reshape your image value to a batch with size one.

image = array(img).reshape(1, 64,64,3)

P.S: the fact that the input placeholder accepts a batch of images, means that you can run predicions for a batch of images in parallel. You can try to read more than 1 image (N images) and than build a batch of N image, using a tensor with shape (N, 64,64,3)

Under what conditions is a JSESSIONID created?

For links generated in a JSP with custom tags, I had to use

<%@ page session="false" %>

in the JSP



in the Struts action

How can I get Apache gzip compression to work?

First of all go to apache/bin/conf/httpd.conf and make sure that is enabled.

Then go to the .htaccess file and add this line:

SetOutputFilter DEFLATE

This should output all the content served as gzipped, i have tried it and it works.

MySQL: determine which database is selected?


p.s. I didn't want to take the liberty of modifying @cwallenpoole's answer to reflect the fact that this is a MySQL question and not an Oracle question and doesn't need DUAL.

Sending command line arguments to npm script

From what I see, people use package.json scripts when they would like to run script in simpler way. For example, to use nodemon that installed in local node_modules, we can't call nodemon directly from the cli, but we can call it by using ./node_modules/nodemon/nodemon.js. So, to simplify this long typing, we can put this...


    scripts: {
      'start': 'nodemon app.js'


... then call npm start to use 'nodemon' which has app.js as the first argument.

What I'm trying to say, if you just want to start your server with the node command, I don't think you need to use scripts. Typing npm start or node app.js has the same effort.

But if you do want to use nodemon, and want to pass a dynamic argument, don't use script either. Try to use symlink instead.

For example using migration with sequelize. I create a symlink...

ln -s node_modules/sequelize/bin/sequelize sequelize

... And I can pass any arguement when I call it ...

./sequlize -h /* show help */

./sequelize -m /* upgrade migration */

./sequelize -m -u /* downgrade migration */


At this point, using symlink is the best way I could figure out, but I don't really think it's the best practice.

I also hope for your opinion to my answer.

Setting selected option in laravel form

            @foreach ($categories as $category)
             <option value="{{$category->id}}" 
               @foreach ($posts->postRelateToCategory as $Postcategory)
                 @if ($Postcategory->id == $category->id)
               @endforeach >
              {{ $category->category_name }} </option>               

Streaming via RTSP or RTP in HTML5

There are three streaming protocols / technology in HTML5:

Live streaming, low latency - WebRTC - Websocket

VOD and Live streaming, high latency - HLS

1. WebRTC

In fact WebRTC is SRTP(secure RTP protocol). Thus we can say that video tag supports RTP(SRTP) indirectly via WebRTC.

Therefore to get RTP stream on your Chrome, Firefox or another HTML5 browser, you need a WebRTC server which will deliver the SRTP stream to browser.

2. Websocket

It is TCP based, but with lower latency than HLS. Again you need a Websocket server.

3. HLS

Most popular high-latency streaming protocol for VOD(pre-recorded video).

Google Maps API v3 adding an InfoWindow to each marker

I had a similar problem. If all you want is for some info to be displayed when you hover over a marker, instead of clicking it, then I found that a good alternative to using an info Window was to set a title on the marker. That way whenever you hover the mouse over the marker the title displays like an ALT tag. 'marker.setTitle('Marker '+id);' It removes the need to create a listener for the marker too

How do I write a "tab" in Python?

Assume I have a variable named file that contains a file. Then I could use file.write("hello\talex").

  1. file.write("hello means I'm starting to write to this file.
  2. \t means a tab
  3. alex") is the rest I'm writing

Turning error reporting off php

Does this work?

display_errors = Off

Also, what version of php are you using?

How to download file from database/folder using php


$file = "Bang.png"; //Let say If I put the file name Bang.png

Try this,



function download($name){
$file = $nama_fail;

How to send Request payload to REST API in java?

The following code works for me.

//escape the double quotes in json string
String payload="{\"jsonrpc\":\"2.0\",\"method\":\"changeDetail\",\"params\":[{\"id\":11376}],\"id\":2}";
String requestUrl="";
sendPostRequest(requestUrl, payload);

method implementation:

public static String sendPostRequest(String requestUrl, String payload) {
    try {
        URL url = new URL(requestUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        connection.setRequestProperty("Accept", "application/json");
        connection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
        OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
        BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        StringBuffer jsonString = new StringBuffer();
        String line;
        while ((line = br.readLine()) != null) {
        return jsonString.toString();
    } catch (Exception e) {
            throw new RuntimeException(e.getMessage());


Validation failed for one or more entities. See 'EntityValidationErrors' property for more details

Per @Slauma's answer and @Milton's suggestion I've extended our base class's custom save method with a try/catch that will handle (and hence log in our error logging!) these sorts of exceptions.

// Where `BaseDB` is your Entities object... (it could be `this` in a different design)
public void Save(bool? validateEntities = null)
        //Capture and set the validation state if we decide to
        bool validateOnSaveEnabledStartState = BaseDB.Configuration.ValidateOnSaveEnabled;
        if (validateEntities.HasValue)
            BaseDB.Configuration.ValidateOnSaveEnabled = validateEntities.Value;


        //Revert the validation state when done
        if (validateEntities.HasValue)
            BaseDB.Configuration.ValidateOnSaveEnabled = validateOnSaveEnabledStartState;
    catch (DbEntityValidationException e)
        StringBuilder sb = new StringBuilder();
        foreach (var eve in e.EntityValidationErrors)
            sb.AppendLine(string.Format("Entity of type \"{0}\" in state \"{1}\" has the following validation errors:", 
            foreach (var ve in eve.ValidationErrors)
                sb.AppendLine(string.Format("- Property: \"{0}\", Error: \"{1}\"",
        throw new DbEntityValidationException(sb.ToString(), e);

repository element was not specified in the POM inside distributionManagement element or in -DaltDep loymentRepository=id::layout::url parameter

The issue is fixed by adding repository url under distributionManagement tab in main pom.xml.

Jenkin maven goal : clean deploy -U -Dmaven.test.skip=true


Throwing exceptions in a PHP Try Catch block

Throw needs an object instantiated by \Exception. Just the $e catched can play the trick.

throw $e

How to remove duplicates from a list?

List ? Set ? List (distinct)

Just add all your elements to a Set: it does not allow it's elements to be repeated. If you need a list afterwards, use new ArrayList(theSet) constructor afterwards (where theSet is your resulting set).

Easy way to build Android UI?

This is an old question, that unfortunately even several years on doesn't have a good solution. I've just ported an app from iOS (Obj C) to Android. The biggest problem was not the back end code (for many/most folks, if you can code in Obj C you can code in Java) but porting the native interfaces. What Todd said above, UI layout is still a complete pain. In my experience, the fastest wat to develop a reliable UI that supports multiple formats etc is in good 'ol HTML.

How to pass a querystring or route parameter to AWS Lambda from Amazon API Gateway

In order to pass parameters to your lambda function you need to create a mapping between the API Gateway request and your lambda function. The mapping is done in the Integration Request -> Mapping templates section of the selected API Gateway resource.

Create a mapping of type application/json, then on the right you will edit (click the pencil) the template.

A mapping template is actually a Velocity template where you can use ifs, loops and of course print variables on it. The template has these variables injected where you can access querystring parameters, request headers, etc. individually. With the following code you can re-create the whole querystring:

    "querystring" : "#foreach($key in $input.params().querystring.keySet())#if($foreach.index > 0)&#end$util.urlEncode($key)=$util.urlEncode($input.params().querystring.get($key))#end",
    "body" : $input.json('$')

Note: click on the check symbol to save the template. You can test your changes with the "test" button in your resource. But in order to test querystring parameters in the AWS console you will need to define the parameter names in the Method Request section of your resource.

Note: check the Velocity User Guide for more information about the Velocity templating language.

Then in your lambda template you can do the following to get the querystring parsed:

var query = require('querystring').parse(event.querystring)
// access parameters with query['foo'] or

How do I monitor the computer's CPU, memory, and disk usage in Java?

A lot of this is already available via JMX. With Java 5, JMX is built-in and they include a JMX console viewer with the JDK.

You can use JMX to monitor manually, or invoke JMX commands from Java if you need this information in your own run-time.

Copying files from one directory to another in Java

following code to copy files from one directory to another

File destFile = new File(targetDir.getAbsolutePath() + File.separator
    + file.getName());
try {
  showMessage("Copying " + file.getName());
  in = new BufferedInputStream(new FileInputStream(file));
  out = new BufferedOutputStream(new FileOutputStream(destFile));
  int n;
  while ((n = != -1) {
  showMessage("Copied " + file.getName());
} catch (Exception e) {
  showMessage("Cannot copy file " + file.getAbsolutePath());
} finally {
  if (in != null)
    try {
    } catch (Exception e) {
  if (out != null)
    try {
    } catch (Exception e) {

Change project name on Android Studio

Here is how it all changes in seconds... in your "manifest.xml" find "android:label=" in front of it just type your new name inside "" for example: android:label="My new name"

Its done! your welcome ;)

How to use multiple @RequestMapping annotations in spring?

@RequestMapping has a String[] value parameter, so you should be able to specify multiple values like this:

@RequestMapping(value={"", "/", "welcome"})

How do I convert from BLOB to TEXT in MySQL?

None of these answers worked for me. When converting to UTF8, when the encoder encounters a set of bytes it can't convert to UTF8 it will result in a ? substitution which results in data loss. You need to use UTF16:

    CONVERT(blobfield USING utf16),
    CONVERT(CONVERT(blobfield USING utf16), BINARY),
    CAST(blobfield  AS CHAR(10000) CHARACTER SET utf16),
    CAST(CAST(blobfield  AS CHAR(10000) CHARACTER SET utf16) AS BINARY)

You can inspect the binary values in MySQL Workbench. Right click on the field -> Open Value in Viewer-> Binary. When converted back to BINARY the binary values should be the same as the original.

Alternatively, you can just use base-64 which was made for this purpose:


Templated check for the existence of a class member function?

With C++ 20 you can write the following:

template<typename T>
concept has_toString = requires(const T& t) {

template<typename T>
std::string optionalToString(const T& obj)
    if constexpr (has_toString<T>)
        return obj.toString();
        return "toString not defined";

What is the difference between dynamic programming and greedy approach?

Difference between greedy method and dynamic programming are given below :

  1. Greedy method never reconsiders its choices whereas Dynamic programming may consider the previous state.

  2. Greedy algorithm is less efficient whereas Dynamic programming is more efficient.

  3. Greedy algorithm have a local choice of the sub-problems whereas Dynamic programming would solve the all sub-problems and then select one that would lead to an optimal solution.

  4. Greedy algorithm take decision in one time whereas Dynamic programming take decision at every stage.

How to export settings?

Similar to the answer given by Big Rich you can do the following:

$ code --list-extensions | xargs -L 1 echo code --install-extension

This will list out your extensions with the command to install them so you can just copy and paste the entire output into your other machine:


code --install-extension EditorConfig.EditorConfig
code --install-extension aaron-bond.better-comments
code --install-extension christian-kohler.npm-intellisense
code --install-extension christian-kohler.path-intellisense
code --install-extension CoenraadS.bracket-pair-colorizer

It is taken from the answer given here.

Note: Make sure you have added VS Code to your path beforehand. On mac you can do the following:

  1. Launch Visual Studio Code
  2. Open the Command Palette (? + ? + P) and type 'shell command' to find the Shell Command: Install 'code' command in PATH command.

add onclick function to a submit button

I need to see your submit button html tag for better help. I am not familiar with php and how it handles the postback, but I guess depending on what you want to do, you have three options:

  1. Getting the handling onclick button on the client-side: In this case you only need to call a javascript function.

function foo() {_x000D_
   alert("Submit button clicked!");_x000D_
   return true;_x000D_
<input type="submit" value="submit" onclick="return foo();" />

  1. If you want to handle the click on the server-side, you should first make sure that the form tag method attribute is set to post:

    <form method="post">
  2. You can use onsubmit event from form itself to bind your function to it.

<form name="frm1" method="post" onsubmit="return greeting()">_x000D_
    <input type="text" name="fname">_x000D_
    <input type="submit" value="Submit">_x000D_

MySql sum elements of a column

Try this:

select sum(a), sum(b), sum(c)
from your_table

How to find the port for MS SQL Server 2008?

I solved the problem by enabling the TCP/IP using the SQL Server Configuration Manager under Protocols for SQLEXPRESS2008, i restarted the service and now the "Server is listening on" shows up in the ERRORLOG file

How do I get the result of a command in a variable in windows?

Example to set in the "V" environment variable the most recent file

FOR /F %I IN ('DIR *.* /O:D /B') DO SET V=%I

in a batch file you have to use double prefix in the loop variable:

FOR /F %%I IN ('DIR *.* /O:D /B') DO SET V=%%I

How to set the focus for a particular field in a Bootstrap modal, once it appears

I had the same problem with bootstrap 3, focus when i click the link, but not when trigger the event with javascript. The solution:

$('#myModal').on('', function () {
    }, 100);

Probably it´s something about the animation!

Create an enum with string values

Here's a fairly clean solution that allows inheritance, using TypeScript 2.0. I didn't try this on an earlier version.

Bonus: the value can be any type!

export class Enum<T> {
  public constructor(public readonly value: T) {}
  public toString() {
    return this.value.toString();

export class PrimaryColor extends Enum<string> {
  public static readonly Red = new Enum('#FF0000');
  public static readonly Green = new Enum('#00FF00');
  public static readonly Blue = new Enum('#0000FF');

export class Color extends PrimaryColor {
  public static readonly White = new Enum('#FFFFFF');
  public static readonly Black = new Enum('#000000');

// Usage:

// Output: Enum { value: '#FF0000' }
console.log(Color.Red); // inherited!
// Output: Enum { value: '#FF0000' }
console.log(Color.Red.value); // we have to call .value to get the value.
// Output: #FF0000
console.log(Color.Red.toString()); // toString() works too.
// Output: #FF0000

class Thing {
  color: Color;

let thing: Thing = {
  color: Color.Red,

switch (thing.color) {
  case Color.Red: // ...
  case Color.White: // ...

How can I easily convert DataReader to List<T>?

I've covered this in a pet project.. use what you want.

Note that the ListEx implements the IDataReader interface.

people = new ListExCommand(command)
.Map(p=> new ContactPerson()
  Age = p.GetInt32(p.GetOrdinal("Age")),
  FirstName = p.GetString(p.GetOrdinal("FirstName")),
  IdNumber = p.GetInt64(p.GetOrdinal("IdNumber")),
  Surname = p.GetString(p.GetOrdinal("Surname")),
  Email = "[email protected]"
.Where("FirstName", "Peter");

Or use object mapping like in the following example.

people = new ListExAutoMap(personList)
.Map(p => new ContactPerson()
    Age = p.Age,
    FirstName = p.FirstName,
    IdNumber = p.IdNumber,
    Surname = p.Surname,
    Email = "[email protected]"
.Where(contactPerson => contactPerson.FirstName == "Zack");

Have a look at

How to use Jquery how to change the aria-expanded="false" part of a dom element (Bootstrap)?

Since the question asked for either jQuery or vanilla JS, here's an answer with vanilla JS.

I've added some CSS to the demo below to change the button's font color to red when its aria-expanded is set to true

const button = document.querySelector('button');_x000D_
button.addEventListener('click', () => {_x000D_
  button.ariaExpanded = !JSON.parse(button.ariaExpanded);_x000D_
button[aria-expanded="true"] {_x000D_
  color: red;_x000D_
<button type="button" aria-expanded="false">Click me!</button>

How to put the legend out of the plot

It's worth refreshing this question, as newer versions of Matplotlib have made it much easier to position the legend outside the plot. I produced this example with Matplotlib version 3.1.1.

Users can pass a 2-tuple of coordinates to the loc parameter to position the legend anywhere in the bounding box. The only gotcha is you need to run plt.tight_layout() to get matplotlib to recompute the plot dimensions so the legend is visible:

import matplotlib.pyplot as plt

plt.plot([0, 1], [0, 1], label="Label 1")
plt.plot([0, 1], [0, 2], label='Label 2')

plt.legend(loc=(1.05, 0.5))

This leads to the following plot:

plot with legend outside


Confirm deletion in modal / dialog using Twitter Bootstrap?

Following solution is better than bootbox.js, because

  • It can do everything bootbox.js can do;
  • The use syntax is simpler
  • It allows you to elegantly control the color of your message using "error", "warning" or "info"
  • Bootbox is 986 lines long, mine only 110 lines long


const dialogTemplate = '\_x000D_
    <div class ="modal" id="digimango_messageBox" role="dialog">\_x000D_
        <div class ="modal-dialog">\_x000D_
            <div class ="modal-content">\_x000D_
                <div class ="modal-body">\_x000D_
                    <p class ="text-success" id="digimango_messageBoxMessage">Some text in the modal.</p>\_x000D_
                    <p><textarea id="digimango_messageBoxTextArea" cols="70" rows="5"></textarea></p>\_x000D_
                <div class ="modal-footer">\_x000D_
                    <button type="button" class ="btn btn-primary" id="digimango_messageBoxOkButton">OK</button>\_x000D_
                    <button type="button" class ="btn btn-default" data-dismiss="modal" id="digimango_messageBoxCancelButton">Cancel</button>\_x000D_
// See the comment inside function digimango_onOkClick(event) {_x000D_
var digimango_numOfDialogsOpened = 0;_x000D_
function messageBox(msg, significance, options, actionConfirmedCallback) {_x000D_
    if ($('#digimango_MessageBoxContainer').length == 0) {_x000D_
        var iDiv = document.createElement('div');_x000D_ = 'digimango_MessageBoxContainer';_x000D_
    var okButtonName, cancelButtonName, showTextBox, textBoxDefaultText;_x000D_
    if (options == null) {_x000D_
        okButtonName = 'OK';_x000D_
        cancelButtonName = null;_x000D_
        showTextBox = null;_x000D_
        textBoxDefaultText = null;_x000D_
    } else {_x000D_
        okButtonName = options.okButtonName;_x000D_
        cancelButtonName = options.cancelButtonName;_x000D_
        showTextBox = options.showTextBox;_x000D_
        textBoxDefaultText = options.textBoxDefaultText;_x000D_
    if (showTextBox == true) {_x000D_
        if (textBoxDefaultText == null)_x000D_
    if (okButtonName != null)_x000D_
    if (cancelButtonName == null)_x000D_
    else {_x000D_
    $('#digimango_messageBoxOkButton').on('click', { callback: actionConfirmedCallback }, digimango_onOkClick);_x000D_
    $('#digimango_messageBoxCancelButton').on('click', digimango_onCancelClick);_x000D_
    var content = $("#digimango_messageBoxMessage");_x000D_
    if (significance == 'error')_x000D_
        content.attr('class', 'text-danger');_x000D_
    else if (significance == 'warning')_x000D_
        content.attr('class', 'text-warning');_x000D_
        content.attr('class', 'text-success');_x000D_
    if (digimango_numOfDialogsOpened == 0)_x000D_
function digimango_onOkClick(event) {_x000D_
    // JavaScript's nature is unblocking. So the function call in the following line will not block,_x000D_
    // thus the last line of this function, which is to hide the dialog, is executed before user_x000D_
    // clicks the "OK" button on the second dialog shown in the callback. Therefore we need to count_x000D_
    // how many dialogs is currently showing. If we know there is still a dialog being shown, we do_x000D_
    // not execute the last line in this function._x000D_
    if (typeof ( != 'undefined')_x000D_$('#digimango_messageBoxTextArea').val());_x000D_
    if (digimango_numOfDialogsOpened == 0)_x000D_
function digimango_onCancelClick() {_x000D_
    if (digimango_numOfDialogsOpened == 0)_x000D_

To use digimango.messagebox.js:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">_x000D_
<html xmlns="">_x000D_
    <title>A useful generic message box</title>_x000D_
    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />_x000D_
    <link rel="stylesheet" type="text/css" href="~/Content/bootstrap.min.css" media="screen" />_x000D_
    <script src="~/Scripts/jquery-1.10.2.min.js" type="text/javascript"></script>_x000D_
    <script src="~/Scripts/bootstrap.js" type="text/javascript"></script>_x000D_
    <script src="~/Scripts/bootbox.js" type="text/javascript"></script>_x000D_
    <script src="~/Scripts/digimango.messagebox.js" type="text/javascript"></script>_x000D_
    <script type="text/javascript">_x000D_
        function testAlert() {_x000D_
            messageBox('Something went wrong!', 'error');_x000D_
        function testAlertWithCallback() {_x000D_
            messageBox('Something went wrong!', 'error', null, function () {_x000D_
                messageBox('OK clicked.');_x000D_
        function testConfirm() {_x000D_
            messageBox('Do you want to proceed?', 'warning', { okButtonName: 'Yes', cancelButtonName: 'No' }, function () {_x000D_
                messageBox('Are you sure you want to proceed?', 'warning', { okButtonName: 'Yes', cancelButtonName: 'No' });_x000D_
        function testPrompt() {_x000D_
            messageBox('How do you feel now?', 'normal', { showTextBox: true }, function (userInput) {_x000D_
                messageBox('User entered "' + userInput + '".');_x000D_
        function testPromptWithDefault() {_x000D_
            messageBox('How do you feel now?', 'normal', { showTextBox: true, textBoxDefaultText: 'I am good!' }, function (userInput) {_x000D_
                messageBox('User entered "' + userInput + '".');_x000D_
    <a href="#" onclick="testAlert();">Test alert</a> <br/>_x000D_
    <a href="#" onclick="testAlertWithCallback();">Test alert with callback</a> <br />_x000D_
    <a href="#" onclick="testConfirm();">Test confirm</a> <br/>_x000D_
    <a href="#" onclick="testPrompt();">Test prompt</a><br />_x000D_
    <a href="#" onclick="testPromptWithDefault();">Test prompt with default text</a> <br />_x000D_
_x000D_ enter image description here

Returning an array using C

You can use code like this:

char *MyFunction(some arguments...)
    char *pointer = malloc(size for the new array);
    if (!pointer)
        An error occurred, abort or do something about the error.
    return pointer; // Return address of memory to the caller.

When you do this, the memory should later be freed, by passing the address to free.

There are other options. A routine might return a pointer to an array (or portion of an array) that is part of some existing structure. The caller might pass an array, and the routine merely writes into the array, rather than allocating space for a new array.

CSS 100% height with padding/margin

A solution with flexbox (working on IE11): (or view on jsfiddle)

    html, body {
      height: 100%; /* fix for IE11, not needed for chrome/ff */
      margin: 0; /* CSS-reset for chrome */
  <body style="display: flex;">
    <div style="background-color: black; flex: 1; margin: 25px;"></div>

(The CSS-reset is not necessarily important for the actual problem.)

The important part is flex: 1 (In combination with display: flex at the parent). Funnily enough, the most plausible explanation I know for how the Flex property works comes from a react-native documentation, so I refer to it anyway:

(...) flex: 1, which tells a component to fill all available space, shared evenly amongst other components with the same parent

Is it possible to display my iPhone on my computer monitor?

This is a tool that will help you, i installed it myself

Here is the link

How do I print colored output with Python 3?

This one answer I have got from the earlier python2 answers that is

  1. Install termcolor module.

    pip3 install termcolor

  2. Import the colored library from termcolor.

    from termcolor import colored

  3. Use the provided methods, below is an example.

    print(colored('hello', 'red'), colored('world', 'green'))

Multiple commands in an alias for bash

Does this not work?

alias whatever='gnome-screensaver ; gnome-screensaver-command --lock'

Why does range(start, end) not include end?

It's also useful for splitting ranges; range(a,b) can be split into range(a, x) and range(x, b), whereas with inclusive range you would write either x-1 or x+1. While you rarely need to split ranges, you do tend to split lists quite often, which is one of the reasons slicing a list l[a:b] includes the a-th element but not the b-th. Then range having the same property makes it nicely consistent.

Vector erase iterator

You increment it past the end of the (empty) container in the for loop's loop expression.

I get a "An attempt was made to load a program with an incorrect format" error on a SQL Server replication project

We recently had the issue when trying to run the code from Visual Studio. In that case you need to do
TOOLS > OPTIONS > Projects and Solutions > WEB PROJECTS and check the "Use the 64 bit version of IIS Express for web sites and projects".

TypeScript and React - children type?

From the TypeScript site:

The recommended practice is to write the props type as {children?: any}

That worked for me. The child node can be many different things, so explicit typing can miss cases.

There's a longer discussion on the followup issue here:, but the any approach still works.

Regular expression replace in C#

Add the following 2 lines

var regex = new Regex(Regex.Escape(","));
sb_trim = regex.Replace(sb_trim, " ", 1);

If sb_trim= John,Smith,100000,M the above code will return "John Smith,100000,M"

git pull keeping local changes

Incase their is local uncommitted changes and avoid merge conflict while pulling.

git stash save
git pull
git stash pop

refer -

How to return a string value from a Bash function

#Implement a generic return stack for functions:

push() {
  STACK+=( "${1}" )
pop() {
  export $1="${STACK[${#STACK[@]}-1]}"
  unset 'STACK[${#STACK[@]}-1]';


my_func() {
  push "Hello world!"
  push "Hello world2!"
my_func ; pop MESSAGE2 ; pop MESSAGE1
echo ${MESSAGE1} ${MESSAGE2}

Generating Random Number In Each Row In Oracle Query

If you just use round then the two end numbers (1 and 9) will occur less frequently, to get an even distribution of integers between 1 and 9 then:

SELECT MOD(Round(DBMS_RANDOM.Value(1, 99)), 9) + 1 FROM DUAL

Fitting a histogram with python

Here is another solution using only matplotlib.pyplot and numpy packages. It works only for Gaussian fitting. It is based on maximum likelihood estimation and have already been mentioned in this topic. Here is the corresponding code :

# Python version : 2.7.9
from __future__ import division
import numpy as np
from matplotlib import pyplot as plt

# For the explanation, I simulate the data :
data = np.random.randn(N)
# But in reality, you would read data from file, for example with :
#data = np.loadtxt("data.txt")

# Empirical average and variance are computed
avg = np.mean(data)
var = np.var(data)
# From that, we know the shape of the fitted Gaussian.
pdf_x = np.linspace(np.min(data),np.max(data),100)
pdf_y = 1.0/np.sqrt(2*np.pi*var)*np.exp(-0.5*(pdf_x-avg)**2/var)

# Then we plot :

and here is the output.

How to set a primary key in MongoDB?

The other way is to create Indexes for your collection and make sure that they are unique.

You can find more on the following link

I actually find this pretty simple and easy to implement.

How to dismiss AlertDialog in android

There are two ways of closing an alert dialog.

Option 1:


Option 2:

The DialogInterface#dismiss();

Out of the box, the framework calls DialogInterface#dismiss(); when you define event listeners for the buttons:

  1. AlertDialog#setNegativeButton();
  2. AlertDialog#setPositiveButton();
  3. AlertDialog#setNeutralButton();

for the Alert dialog.

How to reload the current state?

You can use @Rohan answer

But if you want to make each controller reaload after a view change you can use

myApp.config(function($ionicConfigProvider) { $ionicConfigProvider.views.maxCache(0); ... }

What is the standard naming convention for html/css ids and classes?

There is no agreed upon naming convention for HTML and CSS. But you could structure your nomenclature around object design. More specifically what I call Ownership and Relationship.


Keywords that describe the object, could be separated by hyphens.


Keywords that describe the object can also fall into four categories (which should be ordered from left to right): Object, Object-Descriptor, Action, and Action-Descriptor.

car - a noun, and an object
new - an adjective, and an object-descriptor that describes the object in more detail
turned - a verb, and an action that belongs to the object
right - an adjective, and an action-descriptor that describes the action in more detail

Note: verbs (actions) should be in past-tense (turned, did, ran, etc).


Objects can also have relationships like parent and child. The Action and Action-Descriptor belongs to the parent object, they don't belong to the child object. For relationships between objects you could use an underscore.


  • car-new-turned-right (follows the ownership rule)
  • wheel-left-turned-left (follows the ownership rule)
  • car-new-turned-right_wheel-left-turned-left (follows the relationship rule)

Final notes:

  • Because CSS is case-insensitive, it's better to write all names in lower-case (or upper-case); avoid camel-case or pascal-case as they can lead to ambiguous names.
  • Know when to use a class and when to use an id. It's not just about an id being used once on the web page. Most of the time, you want to use a class and not an id. Web components like (buttons, forms, panels, ...etc) should always use a class. Id's can easily lead to naming conflicts, and should be used sparingly for namespacing your markup. The above concepts of ownership and relationship apply to naming both classes and ids, and will help you avoid naming conflicts.
  • If you don't like my CSS naming convention, there are several others as well: Structural naming convention, Presentational naming convention, Semantic naming convention, BEM naming convention, OCSS naming convention, etc.

Difference between HashMap and Map in Java..?

HashMap is an implementation of Map. Map is just an interface for any type of map.

Basic Authentication Using JavaScript

After Spending quite a bit of time looking into this, i came up with the solution for this; In this solution i am not using the Basic authentication but instead went with the oAuth authentication protocol. But to use Basic authentication you should be able to specify this in the "setHeaderRequest" with minimal changes to the rest of the code example. I hope this will be able to help someone else in the future:

var token_ // variable will store the token
var userName = "clientID"; // app clientID
var passWord = "secretKey"; // app clientSecret
var caspioTokenUrl = ""; // Your application token endpoint  
var request = new XMLHttpRequest(); 

function getToken(url, clientID, clientSecret) {
    var key;      "POST", url, true); 
    request.setRequestHeader("Content-type", "application/json");
    request.send("grant_type=client_credentials&client_id="+clientID+"&"+"client_secret="+clientSecret); // specify the credentials to receive the token on request
    request.onreadystatechange = function () {
        if (request.readyState == request.DONE) {
            var response = request.responseText;
            var obj = JSON.parse(response); 
            key = obj.access_token; //store the value of the accesstoken
            token_ = key; // store token in your global variable "token_" or you could simply return the value of the access token from the function
// Get the token
getToken(caspioTokenUrl, userName, passWord);

If you are using the Caspio REST API on some request it may be imperative that you to encode the paramaters for certain request to your endpoint; see the Caspio documentation on this issue;

NOTE: encodedParams is NOT used in this example but was used in my solution.

Now that you have the token stored from the token endpoint you should be able to successfully authenticate for subsequent request from the caspio resource endpoint for your application

function CallWebAPI() {
    var request_ = new XMLHttpRequest();        
    var encodedParams = encodeURIComponent(params);"GET", "", true);
    request_.setRequestHeader("Authorization", "Bearer "+ token_);
    request_.onreadystatechange = function () {
        if (request_.readyState == 4 && request_.status == 200) {
            var response = request_.responseText;
            var obj = JSON.parse(response); 
            // handle data as needed... 


This solution does only considers how to successfully make the authenticated request using the Caspio API in pure javascript. There are still many flaws i am sure...

Perform debounce in React.js

After struggling with the text inputs for a while and not finding a perfect solution on my own, I found this on npm: react-debounce-input.

Here is a simple example:

import React from 'react';
import ReactDOM from 'react-dom';
import {DebounceInput} from 'react-debounce-input';

class App extends React.Component {
state = {
    value: ''

render() {
    return (
        onChange={event => this.setState({value:})} />

        <p>Value: {this.state.value}</p>

const appRoot = document.createElement('div');
ReactDOM.render(<App />, appRoot);

The DebounceInput component accepts all of the props you can assign to a normal input element. Try it out on codepen

I hope it helps someone else too and saves them some time.

How to solve PHP error 'Notice: Array to string conversion in...'

$result = ob_get_clean();

if you want to capture the result in a variable

Getting user input

Use the raw_input() function to get input from users (2.x):

print "Enter a file name:",
filename = raw_input()

or just:

filename = raw_input('Enter a file name: ')

or if in Python 3.x:

filename = input('Enter a file name: ')

Using Transactions or SaveChanges(false) and AcceptAllChanges()?

Because some database can throw an exception at dbContextTransaction.Commit() so better this:

using (var context = new BloggingContext()) 
  using (var dbContextTransaction = context.Database.BeginTransaction()) 
          @"UPDATE Blogs SET Rating = 5" + 
              " WHERE Name LIKE '%Entity Framework%'" 

      var query = context.Posts.Where(p => p.Blog.Rating >= 5); 
      foreach (var post in query) 
          post.Title += "[Cool Blog]"; 



    catch (Exception) 

How to clear memory to prevent "out of memory error" in excel vba?

The best way to help memory to be freed is to nullify large objects:

Sub Whatever()
    Dim someLargeObject as SomeObject

    'expensive computation

    Set someLargeObject = Nothing
End Sub

Also note that global variables remain allocated from one call to another, so if you don't need persistence you should either not use global variables or nullify them when you don't need them any longer.

However this won't help if:

  • you need the object after the procedure (obviously)
  • your object does not fit in memory

Another possibility is to switch to a 64 bit version of Excel which should be able to use more RAM before crashing (32 bits versions are typically limited at around 1.3GB).

Iterating over a numpy array

I see that no good desciption for using numpy.nditer() is here. So, I am gonna go with one. According to NumPy v1.21 dev0 manual, The iterator object nditer, introduced in NumPy 1.6, provides many flexible ways to visit all the elements of one or more arrays in a systematic fashion.

I have to calculate mean_squared_error and I have already calculate y_predicted and I have y_actual from the boston dataset, available with sklearn.

def cal_mse(y_actual, y_predicted):
    """ this function will return mean squared error
           y_actual (ndarray): np array containing target variable
           y_predicted (ndarray): np array containing predictions from DecisionTreeRegressor
           mse (integer)
    sq_error = 0
    for i in np.nditer(np.arange(y_pred.shape[0])):
        sq_error += (y_actual[i] - y_predicted[i])**2
    mse = 1/y_actual.shape[0] * sq_error
    return mse

Hope this helps :). for further explaination visit

Truncate to three decimals in Python

I am trying to generate a random number between 5 to 7 and want to limit it to 3 decimal places.

import random

num = float('%.3f' % random.uniform(5, 7))
print (num)

Passing a Bundle on startActivity()?

You can use the Bundle from the Intent:

Bundle extras = myIntent.getExtras();

Or an entire bundle:


Is this what you're looking for?

Difference between HashMap, LinkedHashMap and TreeMap

All three classes HashMap, TreeMap and LinkedHashMap implements java.util.Map interface, and represents mapping from unique key to values.


  1. A HashMap contains values based on the key.

  2. It contains only unique elements.

  3. It may have one null key and multiple null values.

  4. It maintains no order.

    public class HashMap<K,V> extends AbstractMap<K,V> implements Map<K,V>, Cloneable, Serializable


  1. A LinkedHashMap contains values based on the key.
  2. It contains only unique elements.
  3. It may have one null key and multiple null values.
  4. It is same as HashMap instead maintains insertion order. //See class deceleration below

    public class LinkedHashMap<K,V> extends HashMap<K,V> implements Map<K,V>


  1. A TreeMap contains values based on the key. It implements the NavigableMap interface and extends AbstractMap class.
  2. It contains only unique elements.
  3. It cannot have null key but can have multiple null values.
  4. It is same as HashMap instead maintains ascending order(Sorted using the natural order of its key.).

    public class TreeMap<K,V> extends AbstractMap<K,V> implements NavigableMap<K,V>, Cloneable, Serializable


  1. A Hashtable is an array of list. Each list is known as a bucket. The position of bucket is identified by calling the hashcode() method. A Hashtable contains values based on the key.
  2. It contains only unique elements.
  3. It may have not have any null key or value.
  4. It is synchronized.
  5. It is a legacy class.

    public class Hashtable<K,V> extends Dictionary<K,V> implements Map<K,V>, Cloneable, Serializable


C# - How to get Program Files (x86) on Windows 64 bit

Note, however, that the ProgramFiles(x86) environment variable is only available if your application is running 64-bit.

If your application is running 32-bit, you can just use the ProgramFiles environment variable whose value will actually be "Program Files (x86)".

Default session timeout for Apache Tomcat applications

Open $CATALINA_BASE/conf/web.xml and find this

<!-- ==================== Default Session Configuration ================= -->
<!-- You can set the default session timeout (in minutes) for all newly   -->
<!-- created sessions by modifying the value below.                       -->


all webapps implicitly inherit from this default web descriptor. You can override session-config as well as other settings defined there in your web.xml.

This is actually from my Tomcat 7 (Windows) but I think 5.5 conf is not very different

With MySQL, how can I generate a column containing the record index in a table?

You may want to try the following:

SELECT  l.position, 
        @curRow := @curRow + 1 AS row_number
FROM    league_girl l
JOIN    (SELECT @curRow := 0) r;

The JOIN (SELECT @curRow := 0) part allows the variable initialization without requiring a separate SET command.

Test case:

CREATE TABLE league_girl (position int, username varchar(10), score int);
INSERT INTO league_girl VALUES (1, 'a', 10);
INSERT INTO league_girl VALUES (2, 'b', 25);
INSERT INTO league_girl VALUES (3, 'c', 75);
INSERT INTO league_girl VALUES (4, 'd', 25);
INSERT INTO league_girl VALUES (5, 'e', 55);
INSERT INTO league_girl VALUES (6, 'f', 80);
INSERT INTO league_girl VALUES (7, 'g', 15);

Test query:

SELECT  l.position, 
        @curRow := @curRow + 1 AS row_number
FROM    league_girl l
JOIN    (SELECT @curRow := 0) r
WHERE   l.score > 50;


| position | username | score | row_number |
|        3 | c        |    75 |          1 |
|        5 | e        |    55 |          2 |
|        6 | f        |    80 |          3 |
3 rows in set (0.00 sec)

How to convert Excel values into buckets?

May be not quite what you were looking for but how about using conditional formatting functionality of Excel

EDIT: As an alternate you could create a vba function that acts as a formula that will do the calulation for you. something like

Function getBucket(rng As Range) As String
    Dim strReturn As String

    Select Case rng.Value
        Case 0 to 10
            strReturn = "Small"
        Case 11 To 20
             strReturn = "Medium"
        Case 21 To 30
             strReturn = "Large"
        Case 31 To 40
             strReturn = "Huge"
        Case Else
             strReturn = "OMG!!!"
    End Select
    getBucket = strReturn
End Function

CSS3 background image transition

Considering background-images can't be animated, I created a little SCSS mixin allowing to transition between 2 different background-images using pseudo selectors before and after. They are at different z-index layers. The one that is ahead starts with opacity 0 and becomes visible with hover.

You can use it the same approach for creating animations with linear-gradients too.


@mixin bkg-img-transition( $bkg1, $bkg2, $transTime:0.5s ){  
  position: relative;  
  z-index: 100; 
  &:before, &:after {
    background-size: cover;  
    content: '';    
    display: block;
    height: 100%;
    position: absolute;
    top: 0; left: 0;    
    width: 100%;    
    transition: opacity $transTime;
  &:before {    
    z-index: -101;
    background-image: url("#{$bkg1}");    
  &:after {    
    z-index: -100;
    opacity: 0;
    background-image: url("#{$bkg2}");    
  &:hover {
       opacity: 1; 

Now you can simply use it with

@include bkg-img-transition("","");

You can check it out here:

Should I use Python 32bit or Python 64bit

You do not need to use 64bit since windows will emulate 32bit programs using wow64. But using the native version (64bit) will give you more performance.

How to find integer array size in java

we can find length of array by using array_name.length attribute

int [] i = i.length;

Converting a char to ASCII?

You can use chars as is as single byte integers.

How can I do a line break (line continuation) in Python?

If you want to break your line because of a long literal string, you can break that string into pieces:

long_string = "a very long string"
print("a very long string")

will be replaced by

long_string = (
  "a "
  "very "
  "long "
  "a "
  "very "
  "long "

Output for both print statements:

a very long string

Notice the parenthesis in the affectation.

Notice also that breaking literal strings into pieces allows to use the literal prefix only on parts of the string and mix the delimiters:

s = (

How to collapse blocks of code in Eclipse?

For windows eclipse using java: Windows -> Preferences -> Java -> Editor -> Folding

Unfortunately this will not allow for collapsing code, however if it turns off you can re-enable it to get rid of long comments and imports.

How to add extra whitespace in PHP?

PHP is an easy language with multiple solutions. A Quick Solution would be using Double Quotes " ". Example Below.

$var1 = "Hello";
$var2 = "World";
$var3 = "How";
$var4 = "are";
$var5 = "you";
$var6 = "?";
$var7 = ",";

echo "$var1 $var2$var7 $var3 $var4 $var5$var6";

//Output: Hello World, How are you?

Returning a value from callback function in Node.js

I am facing small trouble in returning a value from callback function in Node.js

This is not a "small trouble", it is actually impossible to "return" a value in the traditional sense from an asynchronous function.

Since you cannot "return the value" you must call the function that will need the value once you have it. @display_name already answered your question, but I just wanted to point out that the return in doCall is not returning the value in the traditional way. You could write doCall as follow:

function doCall(urlToCall, callback) {
    urllib.request(urlToCall, { wd: 'nodejs' }, function (err, data, response) {                              
        var statusCode = response.statusCode;
        finalData = getResponseJson(statusCode, data.toString());
        // call the function that needs the value
        // we are done

Line callback(finalData); is what calls the function that needs the value that you got from the async function. But be aware that the return statement is used to indicate that the function ends here, but it does not mean that the value is returned to the caller (the caller already moved on.)

Manually adding a Userscript to Google Chrome

The best thing to do is to install the Tampermonkey extension.

This will allow you to easily install Greasemonkey scripts, and to easily manage them. Also it makes it easier to install userscripts directly from sites like OpenUserJS, MonkeyGuts, etc.

Finally, it unlocks most all of the GM functionality that you don't get by installing a GM script directly with Chrome. That is, more of what GM on Firefox can do, is available with Tampermonkey.

But, if you really want to install a GM script directly, it's easy a right pain on Chrome these days...

Chrome After about August, 2014:

You can still drag a file to the extensions page and it will work... Until you restart Chrome. Then it will be permanently disabled. See Continuing to "protect" Chrome users from malicious extensions for more information. Again, Tampermonkey is the smart way to go. (Or switch browsers altogether to Opera or Firefox.)

Chrome 21+ :

Chrome is changing the way extensions are installed. Userscripts are pared-down extensions on Chrome but. Starting in Chrome 21, link-click behavior is disabled for userscripts. To install a user script, drag the **.user.js* file into the Extensions page (chrome://extensions in the address input).

Older Chrome versions:

Merely drag your **.user.js* files into any Chrome window. Or click on any Greasemonkey script-link.

You'll get an installation warning:
Initial warning

Click Continue.

You'll get a confirmation dialog:
confirmation dialog

Click Add.


  1. Scripts installed this way have limitations compared to a Greasemonkey (Firefox) script or a Tampermonkey script. See Cross-browser user-scripting, Chrome section.

Controlling the Script and name:

By default, Chrome installs scripts in the Extensions folder1, full of cryptic names and version numbers. And, if you try to manually add a script under this folder tree, it will be wiped the next time Chrome restarts.

To control the directories and filenames to something more meaningful, you can:

  1. Create a directory that's convenient to you, and not where Chrome normally looks for extensions. For example, Create: C:\MyChromeScripts\.

  2. For each script create its own subdirectory. For example, HelloWorld.

  3. In that subdirectory, create or copy the script file. For example, Save this question's code as: HelloWorld.user.js.

  4. You must also create a manifest file in that subdirectory, it must be named: manifest.json.

    For our example, it should contain:

        "manifest_version": 2,
        "content_scripts": [ {
            "exclude_globs":    [  ],
            "include_globs":    [ "*" ],
            "js":               [ "HelloWorld.user.js" ],
            "matches":          [   "*",
            "run_at": "document_end"
        } ],
        "converted_from_user_script": true,
        "description":  "My first sensibly named script!",
        "name":         "Hello World",
        "version":      "1"

    The manifest.json file is automatically generated from the meta-block by Chrome, when an user script is installed. The values of @include and @exclude meta-rules are stored in include_globs and exclude_globs, @match (recommended) is stored in the matches list. "converted_from_user_script": true is required if you want to use any of the supported GM_* methods.

  5. Now, in Chrome's Extension manager (URL = chrome://extensions/), Expand "Developer mode".

  6. Click the Load unpacked extension... button.

  7. For the folder, paste in the folder for your script, In this example it is: C:\MyChromeScripts\HelloWorld.

  8. Your script is now installed, and operational!

  9. If you make any changes to the script source, hit the Reload link for them to take effect:

    Reload link

1 The folder defaults to:

Windows XP:
  Chrome  : %AppData%\..\Local Settings\Application Data\Google\Chrome\User Data\Default\Extensions\
  Chromium: %AppData%\..\Local Settings\Application Data\Chromium\User Data\Default\Extensions\

Windows Vista/7/8:
  Chrome  : %LocalAppData%\Google\Chrome\User Data\Default\Extensions\
  Chromium: %LocalAppData%\Chromium\User Data\Default\Extensions\

  Chrome  : ~/.config/google-chrome/Default/Extensions/
  Chromium: ~/.config/chromium/Default/Extensions/

Mac OS X:
  Chrome  : ~/Library/Application Support/Google/Chrome/Default/Extensions/
  Chromium: ~/Library/Application Support/Chromium/Default/Extensions/

Although you can change it by running Chrome with the --user-data-dir= option.

How can I get the behavior of GNU's readlink -f on a Mac?

Truely platform-indpendent would be also this R-onliner

readlink(){ RScript -e "cat(normalizePath(commandArgs(T)[1]))" "$1";}

To actually mimic readlink -f <path>, $2 instead of $1 would need to be used.

Postgres: clear entire database before re-creating / re-populating from bash script

Although the following line is taken from a windows batch script, the command should be quite similar:

psql -U username -h localhost -d postgres -c "DROP DATABASE \"$DATABASE\";"

This command is used to clear the whole database, by actually dropping it. The $DATABASE (in Windows should be %DATABASE%) in the command is a windows style environment variable that evaluates to the database name. You will need to substitute that by your development_db_name.

Abstract Class:-Real Time Example

I use often abstract classes in conjuction with Template method pattern.
In main abstract class I wrote the skeleton of main algorithm and make abstract methods as hooks where suclasses can make a specific implementation; I used often when writing data parser (or processor) that need to read data from one different place (file, database or some other sources), have similar processing step (maybe small differences) and different output.
This pattern looks like Strategy pattern but it give you less granularity and can degradated to a difficult mantainable code if main code grow too much or too exceptions from main flow are required (this considerations came from my experience).
Just a small example:

abstract class MainProcess {
  public static class Metrics {
    int skipped;
    int processed;
    int stored;
    int error;
  private Metrics metrics;
  protected abstract Iterator<Item> readObjectsFromSource();
  protected abstract boolean storeItem(Item item);
  protected Item processItem(Item item) {
    /* do something on item and return it to store, or null to skip */
    return item;
  public Metrics getMetrics() {
    return metrics;
  /* Main method */
  final public void process() {
    this.metrics = new Metrics();
    Iterator<Item> items = readObjectsFromSource();
    for(Item item : items) {
      item = processItem(item);
      if(null != item) {

      else {

class ProcessFromDatabase extends MainProcess {
  ProcessFromDatabase(String query) {
    this.query = query;
  protected Iterator<Item> readObjectsFromSource() {
    return sessionFactory.getCurrentSession().query(query).list();
  protected boolean storeItem(Item item) {
    return sessionFactory.getCurrentSession().saveOrUpdate(item);

Here another example.

Calling Oracle stored procedure from C#?

It's basically the same mechanism as for a non query command with:

  • command.CommandText = the name of the stored procedure
  • command.CommandType = CommandType.StoredProcedure
  • As many calls to command.Parameters.Add as the number of parameters the sp requires
  • command.ExecuteNonQuery

There are plenty of examples out there, the first one returned by Google is this one

There's also a little trap you might fall into, if your SP is a function, your return value parameter must be first in the parameters collection

How to check if Location Services are enabled?

For kotlin

 private fun isLocationEnabled(mContext: Context): Boolean {
    val lm = mContext.getSystemService(Context.LOCATION_SERVICE) as LocationManager
    return lm.isProviderEnabled(LocationManager.GPS_PROVIDER) || lm.isProviderEnabled(


private fun showLocationIsDisabledAlert() {
    alert("We can't show your position because you generally disabled the location service for your device.") {
        yesButton {
        neutralPressed("Settings") {

call like this

 if (!isLocationEnabled(this.context)) {

Hint: the dialog needs the following imports (android studio should handle this for you)

import org.jetbrains.anko.alert
import org.jetbrains.anko.noButton

And in the manifest you need the following permissions

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

How to set specific Java version to Maven

On windows, I just add multiple batch files for different JDK versions to the Maven bin folder like this:


@echo off
set "JAVA_HOME=path\to\jdk11"
set "path=%JAVA_HOME%;%path%"
mvn %*

then you can use mvn11 to run Maven in the specified JDK.

Making the main scrollbar always visible

body { 
    min-height: 101vh; 

works the best for me

Can't find bundle for base name /Bundle, locale en_US

The problem must be that the resource-bunde > base-name attribute at the faces-config.xml file has a different path to your properties. This happened to me on the firstcup Java EE tutorial, I gave a different package name on then project creation and then Glassfish was unable to find the properties folder which is on "firstcup.web".

I hope it helps.

How to Retrieve value from JTextField in Java Swing?

What I found helpful is this condition that is below.

String tempEmail = "";
JTextField tf1 = new JTextField();

tf1.addKeyListener(new KeyAdapter(){
    public void keyTyped(KeyEvent evt){
         tempEmail = ((JTextField)evt.getSource()).getText() + String.valueOf(evt.getKeyChar());

How to change XAMPP apache server port?

To answer the original question:

To change the XAMPP Apache server port here the procedure :

1. Choose a free port number

The default port used by Apache is 80.

Take a look to all your used ports with Netstat (integrated to XAMPP Control Panel).

Screenshot of xampp control netstat

Then you can see all used ports and here we see that the 80port is already used by System.

screenshot netstat port 80

Choose a free port number (8012, for this exemple).

2. Edit the file "httpd.conf"

This file should be found in C:\xampp\apache\conf on Windows or in bin/apache for Linux.:

Listen 80
ServerName localhost:80

Replace them by:

Listen 8012
ServerName localhost:8012

Save the file.

Access to : http://localhost:8012 for check if it's work.

If not, you must to edit the http-ssl.conf file as explain in step 3 below. ?

3. Edit the file "http-ssl.conf"

This file should be found in C:\xampp\apache\conf\extra on Windows or see this link for Linux.

Locate the following lines:

Listen 443
<VirtualHost _default_:443>
ServerName localhost:443

Replace them by with a other port number (8013 for this example) :

Listen 8013
<VirtualHost _default_:8013>
ServerName localhost:8013

Save the file.

Restart the Apache Server.

Access to : http://localhost:8012 for check if it's work.

4. Configure XAMPP Apache server settings

If your want to access localhost without specify the port number in the URL
http://localhost instead of http://localhost:8012.

  • Open Xampp Control Panel
  • Go to Config ? Service and Port Settings ? Apache
  • Replace the Main Port and SSL Port values ??with those chosen (e.g. 8012 and 8013).
  • Save Service settings
  • Save Configuration of Control Panel
  • Restart the Apache Server xampp apache setting port It should work now.

4.1. Web browser configuration

If this configuration isn't hiding port number in URL it's because your web browser is not configured for. See : Tools ? Options ? General ? Connection Settings... will allow you to choose different ports or change proxy settings.

4.2. For the rare cases of ultimate bad luck

If step 4 and Web browser configuration are not working for you the only way to do this is to change back to 80, or to install a listener on port 80 (like a proxy) that redirects all your traffic to port 8012.

To answer your problem :

If you still have this message in Control Panel Console :

Apache Started [Port 80]

  • Find location of xampp-control.exe file (probably in C:\xampp)
  • Create a file XAMPP.INI in that directory (so XAMPP.ini and xampp-control.exe are in the same directory)

Put following lines in the XAMPP.INI file:

apache = 8012

Now , you will always get:

Apache started [Port 8012]

Please note that, this is for display purpose only. It has no relation with your httpd.conf.

How do I add items to an array in jQuery?

You are making an ajax request which is asynchronous therefore your console log of the list length occurs before the ajax request has completed.

The only way of achieving what you want is changing the ajax call to be synchronous. You can do this by using the .ajax and passing in asynch : false however this is not recommended as it locks the UI up until the call has returned, if it fails to return the user has to crash out of the browser.

What's the pythonic way to use getters and setters?

In [1]: class test(object):
    def __init__(self):
        self.pants = 'pants'
    def p(self):
        return self.pants
    def p(self, value):
        self.pants = value * 2
In [2]: t = test()
In [3]: t.p
Out[3]: 'pants'
In [4]: t.p = 10
In [5]: t.p
Out[5]: 20

Android Studio suddenly cannot resolve symbols

I use shared preferences, but Android Studio complained about Editor symbol. Then, I added

import android.content.SharedPreferences.Editor;

and symbol is cool now.

Printing newlines with print() in R

Using writeLines also allows you to dispense with the "\n" newline character, by using c(). As in:

writeLines(c("File not supplied.","Usage: ./program F=filename",[additional text for third line]))

This is helpful if you plan on writing a multiline message with combined fixed and variable input, such as the [additional text for third line] above.

PreparedStatement setNull(..)

You could also consider using preparedStatement.setObject(index,value,type);

if else condition in blade file (laravel 5.3)

No curly braces required you can directly write

@if($user->status =='waiting')         
      <td><a href="#" class="viewPopLink btn btn-default1" role="button" data-id="{{ $user->travel_id }}" data-toggle="modal" data-target="#myModal">Approve/Reject<a></td>         
      <td>{{ $user->status }}</td>        

Jquery show/hide table rows

Change your black and white IDs to classes instead (duplicate IDs are invalid), add 2 buttons with the proper IDs, and do this:

var rows = $('table.someclass tr');

$('#showBlackButton').click(function() {
    var black = rows.filter('.black').show();
    rows.not( black ).hide();

$('#showWhiteButton').click(function() {
    var white = rows.filter('.white').show();
    rows.not( white ).hide();

$('#showAll').click(function() {;

<button id="showBlackButton">show black</button>
<button id="showWhiteButton">show white</button>
<button id="showAll">show all</button>

<table class="someclass" border="0" cellpadding="0" cellspacing="0" summary="bla bla bla">
    <caption>bla bla bla</caption>
          <tr class="black">
        <tr class="white">
        <tr class="black">

It uses the filter()[docs] method to filter the rows with the black or white class (depending on the button).

Then it uses the not()[docs] method to do the opposite filter, excluding the black or white rows that were previously found.

EDIT: You could also pass a selector to .not() instead of the previously found set. It may perform better that way:

rows.not( `.black` ).hide();

// ...

rows.not( `.white` ).hide();

...or better yet, just keep a cached set of both right from the start:

var rows = $('table.someclass tr');
var black = rows.filter('.black');
var white = rows.filter('.white');

$('#showBlackButton').click(function() {;

$('#showWhiteButton').click(function() {;

Difference between VARCHAR and TEXT in MySQL



  • fixed max size of 65535 characters (you cannot limit the max size)
  • takes 2 + c bytes of disk space, where c is the length of the stored string.
  • cannot be (fully) part of an index. One would need to specify a prefix length.


  • variable max size of M characters
  • M needs to be between 1 and 65535
  • takes 1 + c bytes (for M ≤ 255) or 2 + c (for 256 ≤ M ≤ 65535) bytes of disk space where c is the length of the stored string
  • can be part of an index

More Details

TEXT has a fixed max size of 2¹6-1 = 65535 characters.
VARCHAR has a variable max size M up to M = 2¹6-1.
So you cannot choose the size of TEXT but you can for a VARCHAR.

The other difference is, that you cannot put an index (except for a fulltext index) on a TEXT column.
So if you want to have an index on the column, you have to use VARCHAR. But notice that the length of an index is also limited, so if your VARCHAR column is too long you have to use only the first few characters of the VARCHAR column in your index (See the documentation for CREATE INDEX).

But you also want to use VARCHAR, if you know that the maximum length of the possible input string is only M, e.g. a phone number or a name or something like this. Then you can use VARCHAR(30) instead of TINYTEXT or TEXT and if someone tries to save the text of all three "Lord of the Ring" books in your phone number column you only store the first 30 characters :)

Edit: If the text you want to store in the database is longer than 65535 characters, you have to choose MEDIUMTEXT or LONGTEXT, but be careful: MEDIUMTEXT stores strings up to 16 MB, LONGTEXT up to 4 GB. If you use LONGTEXT and get the data via PHP (at least if you use mysqli without store_result), you maybe get a memory allocation error, because PHP tries to allocate 4 GB of memory to be sure the whole string can be buffered. This maybe also happens in other languages than PHP.

However, you should always check the input (Is it too long? Does it contain strange code?) before storing it in the database.

Notice: For both types, the required disk space depends only on the length of the stored string and not on the maximum length.
E.g. if you use the charset latin1 and store the text "Test" in VARCHAR(30), VARCHAR(100) and TINYTEXT, it always requires 5 bytes (1 byte to store the length of the string and 1 byte for each character). If you store the same text in a VARCHAR(2000) or a TEXT column, it would also require the same space, but, in this case, it would be 6 bytes (2 bytes to store the string length and 1 byte for each character).

For more information have a look at the documentation.

Finally, I want to add a notice, that both, TEXT and VARCHAR are variable length data types, and so they most likely minimize the space you need to store the data. But this comes with a trade-off for performance. If you need better performance, you have to use a fixed length type like CHAR. You can read more about this here.

Android Emulator Error Message: "PANIC: Missing emulator engine program for 'x86' CPUS."

In my case, I needed to install Android Emulator from Sdk manager and it get fixed

enter image description here

openssl s_client -cert: Proving a client certificate was sent to the server

In order to verify a client certificate is being sent to the server, you need to analyze the output from the combination of the -state and -debug flags.

First as a baseline, try running

$ openssl s_client -connect host:443 -state -debug

You'll get a ton of output, but the lines we are interested in look like this:

SSL_connect:SSLv3 read server done A
write to 0x211efb0 [0x21ced50] (12 bytes => 12 (0xC))
0000 - 16 03 01 00 07 0b 00 00-03                        .........
000c - <SPACES/NULS>
SSL_connect:SSLv3 write client certificate A

What's happening here:

  • The -state flag is responsible for displaying the end of the previous section:

    SSL_connect:SSLv3 read server done A  

    This is only important for helping you find your place in the output.

  • Then the -debug flag is showing the raw bytes being sent in the next step:

    write to 0x211efb0 [0x21ced50] (12 bytes => 12 (0xC))
    0000 - 16 03 01 00 07 0b 00 00-03                        .........
    000c - <SPACES/NULS>
  • Finally, the -state flag is once again reporting the result of the step that -debug just echoed:

    SSL_connect:SSLv3 write client certificate A

So in other words: s_client finished reading data sent from the server, and sent 12 bytes to the server as (what I assume is) a "no client certificate" message.

If you repeat the test, but this time include the -cert and -key flags like this:

$ openssl s_client -connect host:443 \
   -cert cert_and_key.pem \
   -key cert_and_key.pem  \
   -state -debug

your output between the "read server done" line and the "write client certificate" line will be much longer, representing the binary form of your client certificate:

SSL_connect:SSLv3 read server done A
write to 0x7bd970 [0x86d890] (1576 bytes => 1576 (0x628))
0000 - 16 03 01 06 23 0b 00 06-1f 00 06 1c 00 06 19 31   ....#..........1
0620 - 95 ca 5e f4 2f 6c 43 11-                          ..^%/lC.
SSL_connect:SSLv3 write client certificate A

The 1576 bytes is an excellent indication on its own that the cert was transmitted, but on top of that, the right-hand column will show parts of the certificate that are human-readable: You should be able to recognize the CN and issuer strings of your cert in there.

How to check whether a Storage item is set?

I've used in my project and works perfectly for me

var returnObjName= JSON.parse(localStorage.getItem('ObjName'));
if(returnObjName && Object.keys(returnObjName).length > 0){
   //Exist data in local storage
  //Non Exist data block

Error while installing json gem 'mkmf.rb can't find header files for ruby'

In case that you are using ruby 2.0 or 2.2 (thanks @patrick-davey) or 2.3 (thanks @juanitofatas).

sudo apt-get install ruby-dev
sudo apt-get install ruby2.0-dev
sudo apt-get install ruby2.2-dev
sudo apt-get install ruby2.3-dev

And you get the pattern here...