Programs & Examples On #Google calendar api

Questions related to interacting programmatically with Google Calendar calendars and events. A language tag should also be included, e.g. [google-apps-script]. Questions about general use of Google Apps should be posted on Web Applications Stack Exchange.

Get refresh token google api

Since March 2016, use prompt=consent to regenerate Google API refresh token.

As mentioned in,

approval_prompt=force has been replaced with prompt=none|consent|select_account

How do I create a link to add an entry to a calendar?

Here's an Add to Calendar service to serve the purpose for adding an event on

  1. Apple Calendar
  2. Google Calendar
  3. Outlook
  4. Outlook Online
  5. Yahoo! Calendar

The "Add to Calendar" button for events on websites and calendars is easy to install, language independent, time zone and DST compatible. It works perfectly in all modern browsers, tablets and mobile devices, and with Apple Calendar, Google Calendar, Outlook, and Yahoo Calendar.

<div title="Add to Calendar" class="addeventatc">
    Add to Calendar
    <span class="start">03/01/2018 08:00 AM</span>
    <span class="end">03/01/2018 10:00 AM</span>
    <span class="timezone">America/Los_Angeles</span>
    <span class="title">Summary of the event</span>
    <span class="description">Description of the event</span>
    <span class="location">Location of the event</span>

enter image description here

Link to add to Google calendar

There is a comprehensive doc for google calendar and other calendar services:

An example of working link:

ERROR in Cannot find module 'node-sass'

I have also been facing this error. None of the above methods work for me. Please follow this as it worked for me.

For Installing node-sass in Ubuntu 16 via npm :-

You can install with npm 5.2.0 Version

If you are using nvm :-

nvm install 8.2.1
nvm use 8.2.1
npm install node-sass

If you are using npm separately then upgrade or downgrade npm version to 5.2.0

npm install node-sass

How to store custom objects in NSUserDefaults

Swift 3

class MyObject: NSObject, NSCoding  {
    let name : String
    let url : String
    let desc : String

    init(tuple : (String,String,String)){ = tuple.0
        self.url = tuple.1
        self.desc = tuple.2
    func getName() -> String {
        return name
    func getURL() -> String{
        return url
    func getDescription() -> String {
        return desc
    func getTuple() -> (String, String, String) {
        return (,self.url,self.desc)

    required init(coder aDecoder: NSCoder) { = aDecoder.decodeObject(forKey: "name") as? String ?? ""
        self.url = aDecoder.decodeObject(forKey: "url") as? String ?? ""
        self.desc = aDecoder.decodeObject(forKey: "desc") as? String ?? ""

    func encode(with aCoder: NSCoder) {
        aCoder.encode(, forKey: "name")
        aCoder.encode(self.url, forKey: "url")
        aCoder.encode(self.desc, forKey: "desc")

to store and retrieve:

func save() {
            let data  = NSKeyedArchiver.archivedData(withRootObject: object)
            UserDefaults.standard.set(data, forKey:"customData" )
        func get() -> MyObject? {
            guard let data = UserDefaults.standard.object(forKey: "customData") as? Data else { return nil }
            return NSKeyedUnarchiver.unarchiveObject(with: data) as? MyObject

How to plot two columns of a pandas data frame using points?

For this (and most plotting) I would not rely on the Pandas wrappers to matplotlib. Instead, just use matplotlib directly:

import matplotlib.pyplot as plt
plt.scatter(df['col_name_1'], df['col_name_2']) # Depending on whether you use IPython or interactive mode, etc.

and remember that you can access a NumPy array of the column's values with df.col_name_1.values for example.

I ran into trouble using this with Pandas default plotting in the case of a column of Timestamp values with millisecond precision. In trying to convert the objects to datetime64 type, I also discovered a nasty issue: < Pandas gives incorrect result when asking if Timestamp column values have attr astype >.

How do I create an average from a Ruby array?

Try this:

arr = [5, 6, 7, 8]
arr.inject{ |sum, el| sum + el }.to_f / arr.size
=> 6.5

Note the .to_f, which you'll want for avoiding any problems from integer division. You can also do:

arr = [5, 6, 7, 8]
arr.inject(0.0) { |sum, el| sum + el } / arr.size
=> 6.5

You can define it as part of Array as another commenter has suggested, but you need to avoid integer division or your results will be wrong. Also, this isn't generally applicable to every possible element type (obviously, an average only makes sense for things that can be averaged). But if you want to go that route, use this:

class Array
  def sum
    inject(0.0) { |result, el| result + el }

  def mean 
    sum / size

If you haven't seen inject before, it's not as magical as it might appear. It iterates over each element and then applies an accumulator value to it. The accumulator is then handed to the next element. In this case, our accumulator is simply an integer that reflects the sum of all the previous elements.

Edit: Commenter Dave Ray proposed a nice improvement.

Edit: Commenter Glenn Jackman's proposal, using arr.inject(:+).to_f, is nice too but perhaps a bit too clever if you don't know what's going on. The :+ is a symbol; when passed to inject, it applies the method named by the symbol (in this case, the addition operation) to each element against the accumulator value.

How to remove focus around buttons on click

Another possible solution is to add a class using a Javascript listener when the user clicks on the button and then remove that class on focus with another listener. This maintains accessibility (visible tabbing) while also preventing Chrome's quirky behaviour of considering a button focused when clicked.




button:focus {
    outline: 1px dotted #000;
button.clicked {
    outline: none;

Full example here:

Parse error: syntax error, unexpected [

Are you using php 5.4 on your local? the render line is using the new way of initializing arrays. Try replacing ["title" => "Welcome "] with array("title" => "Welcome ")

Check if an element contains a class in JavaScript?

I've created a prototype method which uses classList, if possible, else resorts to indexOf:

Element.prototype.hasClass = Element.prototype.hasClass || _x000D_
    var hasClass = 0,_x000D_
        className = this.getAttribute('class');_x000D_
    if( this == null || !classArr || !className ) return false;_x000D_
    if( !(classArr instanceof Array) )_x000D_
      classArr = classArr.split(' ');_x000D_
    for( var i in classArr )_x000D_
      // this.classList.contains(classArr[i]) // for modern browsers_x000D_
      if( className.split(classArr[i]).length > 1 )  _x000D_
    return hasClass == classArr.length;_x000D_
// TESTS (see browser's console when inspecting the output)_x000D_
var elm1 = document.querySelector('p');_x000D_
var elm2 = document.querySelector('b');_x000D_
var elm3 = elm1.firstChild; // textNode_x000D_
var elm4 = document.querySelector('text'); // SVG text_x000D_
console.log( elm1, ' has class "a": ', elm1.hasClass('a') );_x000D_
console.log( elm1, ' has class "b": ', elm1.hasClass('b') );_x000D_
console.log( elm1, ' has class "c": ', elm1.hasClass('c') );_x000D_
console.log( elm1, ' has class "d": ', elm1.hasClass('d') );_x000D_
console.log( elm1, ' has class "a c": ', elm1.hasClass('a c') );_x000D_
console.log( elm1, ' has class "a d": ', elm1.hasClass('a d') );_x000D_
console.log( elm1, ' has class "": ', elm1.hasClass('') );_x000D_
console.log( elm2, ' has class "a": ', elm2.hasClass('a') );_x000D_
// console.log( elm3, ' has class "a": ', elm3.hasClass('a') );_x000D_
console.log( elm4, ' has class "a": ', elm4.hasClass('a') );
<p class='a b c'>This is a <b>test</b> string</p>_x000D_
<svg xmlns="" width="100px" height="50px">_x000D_
    <text x="10" y="20" class='a'>SVG Text Example</text>_x000D_

Test page

Force the origin to start at 0

xlim and ylim don't cut it here. You need to use expand_limits, scale_x_continuous, and scale_y_continuous. Try:

df <- data.frame(x = 1:5, y = 1:5)
p <- ggplot(df, aes(x, y)) + geom_point()
p <- p + expand_limits(x = 0, y = 0)
p # not what you are looking for

enter image description here

p + scale_x_continuous(expand = c(0, 0)) + scale_y_continuous(expand = c(0, 0))

enter image description here

You may need to adjust things a little to make sure points are not getting cut off (see, for example, the point at x = 5 and y = 5.

jQuery - Call ajax every 10 seconds

This worked for me

setInterval(ajax_query, 10000);

function ajax_query(){
   //Call ajax here

How can I apply styles to multiple classes at once?

Don’t Repeat Your CSS,{



How to set corner radius of imageView?

import UIKit

class BorderImage: UIImageView {

    override func awakeFromNib() {
        layer.cornerRadius = self.frame.height / 10.0
        layer.masksToBounds = true

Based on @DCDC's answer

parse html string with jquery

One thing to note - as I had exactly this problem today, depending on your HTML jQuery may or may not parse it that well. jQuery wouldn't parse my HTML into a correct DOM - on smaller XML compliant files it worked fine, but the HTML I had (that would render in a page) wouldn't parse when passed back to an Ajax callback.

In the end I simply searched manually in the string for the tag I wanted, not ideal but did work.

Text that shows an underline on hover

Fairly simple process I am using SCSS obviously but you don't have to as it's just CSS in the end!


<span class="menu">Menu</span>


.menu {
    position: relative;
    text-decoration: none;
    font-weight: 400;
    color: blue;
    transition: all .35s ease;

    &::before {
        content: "";
        position: absolute;
        width: 100%;
        height: 2px;
        bottom: 0;
        left: 0;
        background-color: yellow;
        visibility: hidden;
        -webkit-transform: scaleX(0);
        transform: scaleX(0);
        -webkit-transition: all 0.3s ease-in-out 0s;
        transition: all 0.3s ease-in-out 0s;

    &:hover {
        color: yellow;

        &::before {
            visibility: visible;
            -webkit-transform: scaleX(1);
            transform: scaleX(1);

Set a path variable with spaces in the path in a Windows .cmd file or batch file

The proper way to do this is like so:

@ECHO off
With Spaces\Sub Folder^
:: calls M:\Dir\With Spaces\Sub Folder\Dir\Folder\hello.bat
CALL "%MY_PATH%\hello.bat"

C# find biggest number

Here is the simple logic to find Biggest/Largest Number

Input : 11, 33, 1111, 4, 0 Output : 1111

namespace PurushLogics
    class Purush_BiggestNumber
        static void Main()
            int count = 0;
            Console.WriteLine("Enter Total Number of Integers\n");
            count = int.Parse(Console.ReadLine());

            int[] numbers = new int[count];

            Console.WriteLine("Enter the numbers"); // Input 44, 55, 111, 2 Output = "111"
            for (int temp = 0; temp < count; temp++)
                numbers[temp] = int.Parse(Console.ReadLine());

            int largest = numbers[0];
            for (int big = 1; big < numbers.Length; big++)
                if (largest < numbers[big])
                    largest = numbers[big];

In oracle, how do I change my session to display UTF8?

The character set is part of the locale, which is determined by the value of NLS_LANG. As the documentation makes clear this is an operating system variable:

NLS_LANG is set as an environment variable on UNIX platforms. NLS_LANG is set in the registry on Windows platforms.

Now we can use ALTER SESSION to change the values for a couple of locale elements, NLS_LANGUAGE and NLS_TERRITORY. But not, alas, the character set. The reason for this discrepancy is - I think - that the language and territory simply effect how Oracle interprets the stored data, e.g. whether to display a comma or a period when displaying a large number. Wheareas the character set is concerned with how the client application renders the displayed data. This information is picked up by the client application at startup time, and cannot be changed from within.

How to make a HTTP request using Ruby on Rails?

I prefer httpclient over Net::HTTP.

client =
puts client.get_content('')

HTTParty is a good choice if you're making a class that's a client for a service. It's a convenient mixin that gives you 90% of what you need. See how short the Google and Twitter clients are in the examples.

And to answer your second question: no, I wouldn't put this functionality in a controller--I'd use a model instead if possible to encapsulate the particulars (perhaps using HTTParty) and simply call it from the controller.

Background images: how to fill whole div if image is small and vice versa

This worked perfectly for me

background-repeat: no-repeat;
background-size: 100% 100%;

Refreshing all the pivot tables in my excel workbook with a macro



Or, if your Excel version is old enough,

Dim Sheet as WorkSheet, Pivot as PivotTable
For Each Sheet in ThisWorkbook.WorkSheets
    For Each Pivot in Sheet.PivotTables

Extract filename and extension in Bash

A simple bash one liner. I used this to remove rst extension from all files in pwd

for each in `ls -1 *.rst`
     a=$(echo $each | wc -c)
     echo $each | cut -c -$(( $a-5 )) >> blognames

What it does ?

1) ls -1 *.rst will list all the files on stdout in new line (try).

2) echo $each | wc -c counts the number of characters in each filename .

3) echo $each | cut -c -$(( $a-5 )) selects up to last 4 characters, i.e, .rst.

Tomcat 8 is not able to handle get request with '|' in query parameters?

Adding "relaxedQueryChars" attribute to the server.xml worked for me :

<Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="443" URIEncoding="UTF-8" relaxedQueryChars="[]|{}^&#x5c;&#x60;&quot;&lt;&gt;"/>

How can I return to a parent activity correctly?

Try this solution use NavUtils.navigateUpFromSameTask(this); in the child activity:

HTML display result in text (input) field?

With .value and INPUT tag


    <script type="text/javascript">
      function sum()

         var num1 = document.myform.number1.value;
         var num2 = document.myform.number2.value;
         var sum = parseInt(num1) + parseInt(num2);
         document.getElementById('add').value = sum;

    <FORM NAME="myform">
      <INPUT TYPE="text" NAME="number1" VALUE=""/> + 
      <INPUT TYPE="text" NAME="number2" VALUE=""/>
      <INPUT TYPE="button" NAME="button" Value="=" onClick="sum()"/>
      <INPUT TYPE="text" ID="add" NAME="result" VALUE=""/>


with innerHTML and DIV


    <script type="text/javascript">
      function sum()

         var num1 = document.myform.number1.value;
         var num2 = document.myform.number2.value;
         var sum = parseInt(num1) + parseInt(num2);
         document.getElementById('add').innerHTML = sum;

    <FORM NAME="myform">
      <INPUT TYPE="text" NAME="number1" VALUE=""/> + 
      <INPUT TYPE="text" NAME="number2" VALUE=""/>
      <INPUT TYPE="button" NAME="button" Value="=" onClick="sum()"/>
      <DIV  ID="add"></DIV>


Bootstrap full responsive navbar with logo or brand name text

If you want to achieve this (you can resize the window to see how it will look for mobile version), all you have to do is to have 2 logo images (1 for desktop and one for mobile) and display them depending of the enviroment using visible-xs and hidden-xs classes.

So i used something like this:

<img class="hidden-xs" src="" alt="">
<img class="visible-xs" src="" alt=""> 

And ofcourse, i styled the mobile logo using:

@media (max-width: 767px) { 
    .navbar-brand {
        padding: 0;        

    .navbar-brand img {
        margin-top: 5px;
        margin-left: 5px;

You can see all the code here. In case you need a text on mobile version insted of the logo, it's not a big deal. Just replace the logo with a <h1 class="visible-xs">AppName</h3> and change the style inside the media query like this:

@media (max-width: 767px) { 
    .navbar-brand {
        padding: 0;        

    .navbar-brand h1{
        //here add your style depending of the position you want the text to be placed


You need this conditions to make it work:

.navbar-toggle {
   margin: 23px 0; 

.navbar-nav, .navbar-nav li, .navbar-nav li a {
  height: 80px;
  line-height: 80px;

.navbar-nav li a {
  padding-top: 0;

Why is not Element in Typescript?

I use this:

onClick({ target }: MouseEvent) => {
    const targetDivElement: HTMLDivElement = target as HTMLDivElement;
    const listFullHeight: number = targetDivElement.scrollHeight;
    const listVisibleHeight: number = targetDivElement.offsetHeight;
    const listTopScroll: number = targetDivElement.scrollTop;

How to add image background to btn-default twitter-bootstrap button?

This works with font awesome:

<button class="btn btn-outline-success">
   <i class="fa fa-print" aria-hidden="true"></i>

How to take MySQL database backup using MySQL Workbench?

In workbench 6.0 Connect to any of the database. You will see two tabs.

1.Management 2. Schemas

By default Schemas tab is selected. Select Management tab then select Data Export . You will get list of all databases. select the desired database and and the file name and ther options you wish and start export. You are done with backup.

Explaining the 'find -mtime' command

To find all files modified in the last 24 hours use the one below. The -1 here means changed 1 day or less ago.

find . -mtime -1 -ls

How to configure socket connect timeout

I solved the problem by using Socket.ConnectAsync Method instead of Socket.Connect Method. After invoking the Socket.ConnectAsync(SocketAsyncEventArgs), start a timer (timer_connection), if time is up, check whether socket connection is connected (if(m_clientSocket.Connected)), if not, pop up timeout error.

private void connect(string ipAdd,string port)
            SocketAsyncEventArgs e=new SocketAsyncEventArgs();

            m_clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            IPAddress ip = IPAddress.Parse(serverIp);
            int iPortNo = System.Convert.ToInt16(serverPort);
            IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);

            e.RemoteEndPoint = ipEnd;
            e.UserToken = m_clientSocket;
            e.Completed+=new EventHandler<SocketAsyncEventArgs>(e_Completed);                

            if (timer_connection != null)
                timer_connection = new Timer();
            timer_connection.Interval = 2000;
            timer_connection.Tick+=new EventHandler(timer_connection_Tick);
        catch (SocketException se)
            lb_connectStatus.Text = "Connection Failed";
private void e_Completed(object sender,SocketAsyncEventArgs e)
        lb_connectStatus.Text = "Connection Established";
    private void timer_connection_Tick(object sender, EventArgs e)
        if (!m_clientSocket.Connected)
            MessageBox.Show("Connection Timeout");
            //m_clientSocket = null;


How to push both value and key into PHP array

This is the solution that may useful for u

Class Form {
# Declare the input as property
private $Input = [];

# Then push the array to it
public function addTextField($class,$id){
    $this->Input ['type'][] = 'text';
    $this->Input ['class'][] = $class;
    $this->Input ['id'][] = $id;


$form = new Form();

When you dump it. The result like this

array (size=3)
  'type' => 
    array (size=3)
      0 => string 'text' (length=4)
      1 => string 'text' (length=4)
      2 => string 'text' (length=4)
  'class' => 
    array (size=3)
      0 => string 'myclass1' (length=8)
      1 => string 'myclass2' (length=8)
      2 => string 'myclass3' (length=8)
  'id' => 
    array (size=3)
      0 => string 'myid1' (length=5)
      1 => string 'myid2' (length=5)
      2 => string 'myid3' (length=5)

IIS7: A process serving application pool 'YYYYY' suffered a fatal communication error with the Windows Process Activation Service

I was debugging the problem for the better part of the day and when I was close to burning the building I discovered the Process Monitor tool from Sysinternals.

Set it to monitor w3wp.exe and check last events before it exits after you fire a request in the browser. Hope that helps further readers.

Can I add background color only for padding?

I'd just wrap the header with another div and play with borders.

<div class="header-border"><div class="header-real">




.header-border { border: 2px solid #000000; }
.header-real { border: 10px solid #003399; background: #cccccc; padding: 10px; }

How to install wget in macOS?

Using brew

First install brew:

ruby -e "$(curl -fsSL"

And then install wget with brew:

brew install wget

Using MacPorts

First, download and run MacPorts installer (.pkg)

And then install wget:

sudo port install wget

How do I add space between two variables after a print in Python

You should use python Explicit Conversion Flag PEP-3101

'My name is {0!s:10} {1}'.format('Dunkin', 'Donuts')

'My name is Dunkin Donuts'


'My name is %-10s %s' % ('Dunkin', 'Donuts')

'My name is Dunkin Donuts'

Connecting to SQL Server using windows authentication

Just replace the first line with the below;

SqlConnection con = new SqlConnection("Server=localhost;Database=employeedetails;Trusted_Connection=True");


String escape into XML

Thanks to @sehe for the one-line escape:

var escaped = new System.Xml.Linq.XText(unescaped).ToString();

I add to it the one-line un-escape:

var unescapedAgain = System.Xml.XmlReader.Create(new StringReader("<r>" + escaped + "</r>")).ReadElementString();

Correct way to select from two tables in SQL Server with no common field to join on

A suggestion - when using cross join please take care of the duplicate scenarios. For example in your case:

  • Table 1 may have >1 columns as part of primary keys(say table1_id, id2, id3, table2_id)
  • Table 2 may have >1 columns as part of primary keys(say table2_id, id3, id4)

since there are common keys between these two tables (i.e. foreign keys in one/other) - we will end up with duplicate results. hence using the following form is good:

WITH data_mined_table (col1, col2, col3, etc....) AS
SELECT DISTINCT col1, col2, col3, blabla
FROM table_1 (NOLOCK), table_2(NOLOCK))
SELECT * from data_mined WHERE data_mined_table.col1 = :my_param_value

How to create streams from string in Node.Js?

Another solution is passing the read function to the constructor of Readable (cf doc stream readeable options)

var s = new Readable({read(size) {
    this.push("your string here")

you can after use s.pipe for exemple

How to put two divs side by side

<div style="display: inline">
    <div style="width:80%; display: inline-block; float:left; margin-right: 10px;"></div>
    <div style="width: 19%; display: inline-block; border: 1px solid red"></div>

Pass object to javascript function

The "braces" are making an object literal, i.e. they create an object. It is one argument.


function someFunc(arg) {

someFunc({foo: "This", bar: "works!"});

the object can be created beforehand as well:

var someObject = {
    foo: "This", 
    bar: "works!"


I recommend to read the MDN JavaScript Guide - Working with Objects.

How to link to apps on the app store

Creating a link could become a complex issue when supporting multiple OS and multiple platform. For example the WebObjects isn't supported on iOS 7 (some of them), some links you create would open another country store then the user's etc.

There is an open source library called iLink that could help you.

There advantages of this library is that the links would be found and created at run time (the library would check the app ID and the OS it is running on and would figure out what link should be created). The best point in this is that you don't need to configure almost anything before using it so that is error free and would work always. That's great also if you have few targets on same project so you don't have to remember which app ID or link to use. This library also would prompt the user to upgrade the app if there is a new version on the store (this is built in and you turn this off by a simple flag) directly pointing to the upgrade page for the app if user agrees.

Copy the 2 library files to your project (iLink.h & iLink.m).

On your appDelegate.m:

#import "iLink.h"

+ (void)initialize
    //configure iLink
    [iLink sharedInstance].globalPromptForUpdate = YES; // If you want iLink to prompt user to update when the app is old.

and on the place you want to open the rating page for example just use:

[[iLink sharedInstance] iLinkOpenAppPageInAppStoreWithAppleID: YOUR_PAID_APP_APPLE_ID]; // You should find YOUR_PAID_APP_APPLE_ID from iTunes Connect 

Don't forget to import iLink.h on the same file.

There is a very good doc for the whole library there and an example projects for iPhone and for Mac.

Image encryption/decryption using AES256 symmetric block ciphers

As mentioned by Nacho.L PBKDF2WithHmacSHA1 derivation is used as it is more secured.

import android.util.Base64;


import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;

public class AESEncyption {

    private static final int pswdIterations = 10;
    private static final int keySize = 128;
    private static final String cypherInstance = "AES/CBC/PKCS5Padding";
    private static final String secretKeyInstance = "PBKDF2WithHmacSHA1";
    private static final String plainText = "sampleText";
    private static final String AESSalt = "exampleSalt";
    private static final String initializationVector = "8119745113154120";

    public static String encrypt(String textToEncrypt) throws Exception {

        SecretKeySpec skeySpec = new SecretKeySpec(getRaw(plainText, AESSalt), "AES");
        Cipher cipher = Cipher.getInstance(cypherInstance);
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(initializationVector.getBytes()));
        byte[] encrypted = cipher.doFinal(textToEncrypt.getBytes());
        return Base64.encodeToString(encrypted, Base64.DEFAULT);

    public static String decrypt(String textToDecrypt) throws Exception {

        byte[] encryted_bytes = Base64.decode(textToDecrypt, Base64.DEFAULT);
        SecretKeySpec skeySpec = new SecretKeySpec(getRaw(plainText, AESSalt), "AES");
        Cipher cipher = Cipher.getInstance(cypherInstance);
        cipher.init(Cipher.DECRYPT_MODE, skeySpec, new IvParameterSpec(initializationVector.getBytes()));
        byte[] decrypted = cipher.doFinal(encryted_bytes);
        return new String(decrypted, "UTF-8");

    private static byte[] getRaw(String plainText, String salt) {
        try {
            SecretKeyFactory factory = SecretKeyFactory.getInstance(secretKeyInstance);
            KeySpec spec = new PBEKeySpec(plainText.toCharArray(), salt.getBytes(), pswdIterations, keySize);
            return factory.generateSecret(spec).getEncoded();
        } catch (InvalidKeySpecException e) {
        } catch (NoSuchAlgorithmException e) {
        return new byte[0];


Android: Test Push Notification online (Google Cloud Messaging)

Postman is a good solution and so is php fiddle. However to avoid putting in the GCM URL and the header information every time, you can also use this nifty GCM Notification Test Tool

How can I create an Asynchronous function in Javascript?

Unfortunately, JavaScript doesn't provide an async functionality. It works only in a single one thread. But the most of the modern browsers provide Workers, that are second scripts which gets executed in background and can return a result. So, I reached a solution I think it's useful to asynchronously run a function, which creates a worker for each async call.

The code below contains the function async to call in background.

Function.prototype.async = function(callback) {
    let blob = new Blob([ "self.addEventListener('message', function(e) { self.postMessage({ result: (" + this + ").apply(null, }); }, false);" ], { type: "text/javascript" });
    let worker = new Worker(window.URL.createObjectURL(blob));
    worker.addEventListener("message", function(e) {
    }.bind(callback), false);
    return function() {

This is an example for usage:

(function(x) {
    for (let i = 0; i < 999999999; i++) {}
        return x * 2;
}).async(function(result) {

This executes a function which iterate a for with a huge number to take time as demonstration of asynchronicity, and then gets the double of the passed number. The async method provides a function which calls the wanted function in background, and in that which is provided as parameter of async callbacks the return in its unique parameter. So in the callback function I alert the result.

Rails: Missing host to link to! Please provide :host parameter or set default_url_options[:host]

The above answer did not work for me, at least not as I wanted. I realised config.action_mailer.default_url_options = { host: "localhost", port: 3000 } after installing devise. Hope it will help someone with the same problem.

onchange event on input type=range is not triggering in firefox while dragging

Yet another approach - just set a flag on an element signaling which type of event should be handled:

function setRangeValueChangeHandler(rangeElement, handler) {
    rangeElement.oninput = (event) => {
        // Save flag that we are using onInput in current browser = true;

    rangeElement.onchange = (event) => {
        // Call only if we are not using onInput in current browser
        if (! {

How can I get Git to follow symlinks?

Use hard links instead. This differs from a soft (symbolic) link. All programs, including git will treat the file as a regular file. Note that the contents can be modified by changing either the source or the destination.

On macOS (before 10.13 High Sierra)

If you already have git and Xcode installed, install hardlink. It's a microscopic tool to create hard links.

To create the hard link, simply:

hln source destination

macOS High Sierra update

Does Apple File System support directory hard links?

Directory hard links are not supported by Apple File System. All directory hard links are converted to symbolic links or aliases when you convert from HFS+ to APFS volume formats on macOS.

From APFS FAQ on

Follow for future alternatives.

On Linux and other Unix flavors

The ln command can make hard links:

ln source destination

On Windows (Vista, 7, 8, …)

Use mklink to create a junction on Windows:

mklink /j "source" "destination"

Code for Greatest Common Divisor in Python

#This program will find the hcf of a given list of numbers.

A = [65, 20, 100, 85, 125]     #creates and initializes the list of numbers

def greatest_common_divisor(_A):
  iterator = 1
  factor = 1
  a_length = len(_A)
  smallest = 99999

#get the smallest number
for number in _A: #iterate through array
  if number < smallest: #if current not the smallest number
    smallest = number #set to highest

while iterator <= smallest: #iterate from 1 ... smallest number
for index in range(0, a_length): #loop through array
  if _A[index] % iterator != 0: #if the element is not equally divisible by 0
    break #stop and go to next element
  if index == (a_length - 1): #if we reach the last element of array
    factor = iterator #it means that all of them are divisibe by 0
iterator += 1 #let's increment to check if array divisible by next iterator
#print the factor
print factor

print "The highest common factor of: ",
for element in A:
  print element,
print " is: ",


How to set time zone of a java.util.Date?

You could also set the timezone at the JVM level

Date date1 = new Date();

// or pass in a command line arg: -Duser.timezone="UTC"

Date date2 = new Date();


Thu Sep 05 10:11:12 EDT 2013
Thu Sep 05 14:11:12 UTC 2013

Securely storing passwords for use in python script

I typically have a that is stored separately from my other python scripts and is not under version control. Then whenever required, you can do from secrets import <required_pwd_var>. This way you can rely on the operating systems in-built file security system without re-inventing your own.

Using Base64 encoding/decoding is also another way to obfuscate the password though not completely secure

More here - Hiding a password in a python script (insecure obfuscation only)

Display progress bar while doing some work in C#?

For me the easiest way is definitely to use a BackgroundWorker, which is specifically designed for this kind of task. The ProgressChanged event is perfectly fitted to update a progress bar, without worrying about cross-thread calls

make script execution to unlimited

As @Peter Cullen answer mention, your script will meet browser timeout first. So its good idea to provide some log output, then flush(), but connection have buffer and you'll not see anything unless much output provided. Here are code snippet what helps provide reliable log:

print "log message";
print "<!--"; print str_repeat (' ', 4000); print "-->"; flush();
print "log message";
print "<!--"; print str_repeat (' ', 4000); print "-->"; flush();

Warning: mysqli_real_escape_string() expects exactly 2 parameters, 1 given... what I do wrong?

you are mixing mysql and mysqli

use this mysql_real_escape_string like

$username = mysql_real_escape_string($_POST['username']);

NOTE : mysql_* is deprecated use mysqli_* or PDO

Does Notepad++ show all hidden characters?

Yes, and unfortunately you cannot turn them off, or any other special characters. The options under \View\Show Symbols only turns on or off things like tabs, spaces, EOL, etc. So if you want to read some obscure coding with text in it - you actually need to look elsewhere. I also looked at changing the coding, ASCII is not listed, and that would not make the mess invisible anyway.

Class has been compiled by a more recent version of the Java Environment

Go to Project section, click on properties > then to Java compiler > check compiler compliance level is 1.8 , or there should be no yellow warning at bottom

Android: Remove all the previous activities from the back stack

To clear the activity stack completely you want to create a new task stack using TaskStackBuilder, for example:

Intent loginIntent = LoginActivity.getIntent(context);

This will not only create a new, clean task stack, it will also allow for proper functioning of the "up" button if your LoginActivity has a parent activity.

How do I connect to this localhost from another computer on the same network?

That's definitely possible. We'll take a general case with Apache here.

Let's say you're a big Symfony2 fan and you would like to access your symfony website at http://symfony.local/ from 4 different computers (the main one hosting your website, as well as a Mac, a Windows and a Linux distro connected (wireless or not) to the main computer.

General Sketch:

enter image description here

1 Set up a virtual host:

You first need to set up a virtual host in your apache httpd-vhosts.conf file. On XAMP, you can find this file here: C:\xampp\apache\conf\extra\httpd-vhosts.conf. On MAMP, you can find this file here: Applications/MAMP/conf/apache/extra/httpd-vhosts.conf. This step prepares the Web server on your computer for handling symfony.local requests. You need to provide the name of the Virtual Host as well as the root/main folder of your website. To do this, add the following line at the end of that file. You need to change the DocumentRoot to wherever your main folder is. Here I have taken /Applications/MAMP/htdocs/Symfony/ as the root of my website.

<VirtualHost *:80>
    DocumentRoot "/Applications/MAMP/htdocs/Symfony/"
    ServerName symfony.local

2 Configure your hosts file:

For the client (your browser in that case) to understand what symfony.local really means, you need to edit the hosts file on your computer. Everytime you type an URL in your browser, your computer tries to understand what it means! symfony.local doesn't mean anything for a computer. So it will try to resolve the name symfony.local to an IP address. It will do this by first looking into the hosts file on your computer to see if he can match an IP address to what you typed in the address bar. If it can't, then it will ask DNS servers. The trick here is to append the following to your hosts file.

  • On MAC, this file is in /private/etc/hosts;
  • On LINUX, this file is in /etc/hosts;
  • On WINDOWS, this file is in \Windows\system32\private\etc\hosts;
  • On WINDOWS 7, this file is in \Windows\system32\drivers\etc\hosts;
  • On WINDOWS 10, this file is in \Windows\system32\drivers\etc\hosts;

Hosts file

# Host Database
# localhost is used to configure the loopback interface
#...           symfony.local

From now on, everytime you type symfony.local on this computer, your computer will use the loopback interface to connect to symfony.local. It will understand that you want to work on localhost (

3 Access symfony.local from an other computer:

We finally arrive to your main question which is:

How can I now access my website through an other computer?

Well this is now easy! We just need to tell the other computers how they could find symfony.local! How do we do this?

3a Get the IP address of the computer hosting the website:

We first need to know the IP address on the computer that hosts the website (the one we've been working on since the very beginning). In the terminal, on MAC and LINUX type ifconfig |grep inet, on WINDOWS type ipconfig. Let's assume the IP address of this computer is

3b Edit the hosts file on the computer you are trying to access the website from.:

Again, on MAC, this file is in /private/etc/hosts; on LINUX, in /etc/hosts; and on WINDOWS, in \Windows\system32\private\etc\hosts (if you're using WINDOWS 7, this file is in \Windows\system32\drivers\etc\hosts).. The trick is now to use the IP address of the computer we are trying to access/talk to:

# Host Database
# localhost is used to configure the loopback interface
#...         symfony.local

4 Finally enjoy the results in your browser

You can now go into your browser and type http://symfony.local to beautifully see your website on different computers! Note that you can apply the same strategy if you are a OSX user to test your website on Internet Explorer via Virtual Box (if you don't want to use a Windows computer). This is beautifully explained in Crafting Your Windows / IE Test Environment on OSX.

You can also access your localhost from mobile devices

You might wonder how to access your localhost website from a mobile device. In some cases, you won't be able to modify the hosts file (iPhone, iPad...) on your device (jailbreaking excluded).

Well, the solution then is to install a proxy server on the machine hosting the website and connect to that proxy from your iphone. It's actually very well explained in the following posts and is not that long to set up:

On a Mac, I would recommend: Testing a Mac OS X web site using a local hostname on a mobile device: Using SquidMan as a proxy. It's a 100% free solution. Some people can also use Charles as a proxy server but it's 50$.

On Linux, you can adapt the Mac OS way above by using Squid as a proxy server.

On Windows, you can do that using Fiddler. The solution is described in the following post: Monitoring iPhone traffic with Fiddler

Edit 23/11/2017: Hey I don't want to modify my Hosts file

@Dre. Any possible way to access the website from another computer by not editing the host file manually? let's say I have 100 computers wanted to access the website

This is an interesting question, and as it is related to the OP question, let me help.

You would have to do a change on your network so that every machine knows where your website is hosted. Most everyday routers don't do that so you would have to run your own DNS Server on your network.

Let's pretend you have a router ( This router has a DHCP server and allocates IP addresses to 100 machines on the network.

Now, let's say you have, same as above, on the same network, a machine at which has your website. We will call that machine pompei.

$ echo $HOSTNAME

Same as before, that machine pompei at runs an HTTP Server which serves your website symfony.local.

For every machine to know that symfony.local is hosted on pompei we will now need a custom DNS Server on the network which knows where symfony.local is hosted. Devices on the network will then be able to resolve domain names served by pompei internally.

3 simple steps.

Step 1: DNS Server

Set-up a DNS Server on your network. Let's have it on pompei for convenience and use something like dnsmasq.

Dnsmasq provides Domain Name System (DNS) forwarder, ....

We want pompei to run DNSmasq to handle DNS requests Hey, pompei, where is symfony.local and respond Hey, sure think, it is on but don't take my word for it.

Go ahead install dnsmasq, dnsmasq configuration file is typically in /etc/dnsmasq.conf depending on your environment.

I personally use no-resolv and google servers server= server=

*Note:* ALWAYS restart DNSmasq if modifying /etc/hosts file as no changes will take effect otherwise.

Step 2: Firewall

To work, pompei needs to allow incoming and outgoing 'domain' packets, which are going from and to port 53. Of course! These are DNS packets and if pompei does not allow them, there is no way for your DNS server to be reached at all. Go ahead and open that port 53. On linux, you would classically use iptables for this.

Sharing what I came up with but you will very likely have to dive into your firewall and understand everything well.

# Allow outbound DNS port 53
 iptables -A INPUT -p tcp --dport 53 -j ACCEPT
 iptables -A INPUT -p udp --dport 53 -j ACCEPT

 iptables -A OUTPUT -p tcp --dport 53 -j ACCEPT
 iptables -A OUTPUT -p udp --dport 53 -j ACCEPT

 iptables -A INPUT -p udp --sport 53 -j ACCEPT
 iptables -A INPUT -p tcp --sport 53 -j ACCEPT

 iptables -A OUTPUT -p tcp --sport 53 -j ACCEPT
 iptables -A OUTPUT -p udp --sport 53 -j ACCEPT

Step 3: Router

Tell your router that your dns server is on now. Most of the time, you can just login into your router and change this manually very easily.

That's it, When you are on a machine and ask for symfony.local, it will ask your DNS Server where symfony.local is hosted, and as soon as it has received its answer from the DNS server, will then send the proper HTTP request to pompei on

I let you play with this and enjoy the ride. These 2 steps are the main guidelines, so you will have to debug and spend a few hours if this is the first time you do it. Let's say this is a bit more advanced networking, there are primary DNS Server, secondary DNS Servers, etc.. Good luck!

How to calculate percentage when old value is ZERO

You can add 1 to each example New = 5; old = 0;

(1+new) - (old+1) / (old +1) 5/ 1 * 100 ==> 500%

What does "'') " mean in Flask

To answer to your second question. You can just hit the IP address of the machine that your flask app is running, e.g. in a browser on different machine on the same network and you are there. Though, you will not be able to access it if you are on a different network. Firewalls or VLans can cause you problems with reaching your application. If that computer has a public IP, then you can hit that IP from anywhere on the planet and you will be able to reach the app. Usually this might impose some configuration, since most of the public servers are behind some sort of router or firewall.

How do I display the value of a Django form field in a template?

If you've populated the form with an instance and not with POST data (as the suggested answer requires), you can access the data using {{ form.instance.my_field_name }}.

How to filter empty or NULL names in a QuerySet?

Firstly, the Django docs strongly recommend not using NULL values for string-based fields such as CharField or TextField. Read the documentation for the explanation:

Solution: You can also chain together methods on QuerySets, I think. Try this:


That should give you the set you're looking for.

New lines (\r\n) are not working in email body

OP's problem was related with HTML coding. But if you are using plain text, please use "\n" and not "\r\n".

My personal use case: using mailx mailer, simply replacing "\r\n" into "\n" fixed my issue, related with wrong automatic Content-Type setting.

Wrong header:

User-Agent: Heirloom mailx 12.4 7/29/08
MIME-Version: 1.0
Content-Type: application/octet-stream
Content-Transfer-Encoding: base64

Correct header:

User-Agent: Heirloom mailx 12.4 7/29/08
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

I'm not saying that "application/octet-stream" and "base64" are always wrong/unwanted, but they where in my case.

How to create a sticky navigation bar that becomes fixed to the top after scrolling

Note (2015): Both question and the answer below apply to the old, deprecated version 2.x of Twitter Bootstrap.

This feature of making and element "sticky" is built into the Twitter's Bootstrap and it is called Affix. All you have to do is to add:

<div data-spy="affix" data-offset-top="121">
  ... your navbar ...

around your tag and do not forget to load the Bootstrap's JS files as described in the manual. Data attribute offset-top tells how many pixels the page is scrolled (from the top) to fix you menu component. Usually it is just the space to the top of the page.

Note: You will have to take care of the missing space when the menu will be fixed. Fixing means cutting it off out of your page layer and pasting in different layer that does not scroll. I am doing the following:

<div style="height: 77px;">
  <div data-spy="affix" data-offset-top="121">
    <div style="position: relative; height: 0; width: 100%;">
      <div style="position: absolute; top: 0; left: 0;">
        ... my menu ...

where 77px is the height of my affixed component.

Reading/Writing a MS Word file in PHP

2007 might be a bit complicated as well.

The .docx format is a zip file that contains a few folders with other files in them for formatting and other stuff.

Rename a .docx file to .zip and you'll see what I mean.

So if you can work within zip files in PHP, you should be on the right path.

Override back button to act like home button

Working example..

Make sure don't call super.onBackPressed();

public void onBackPressed() {
   Log.d("CDA", "onBackPressed Called");
   Intent setIntent = new Intent(Intent.ACTION_MAIN);

In this way your Back Button act like Home button . It doesn't finishes your activity but take it to background

Second way is to call moveTaskToBack(true); in onBackPressed and be sure to remove super.onBackPressed

How to use @Nullable and @Nonnull annotations more effectively?

Short answer: I guess these annotations are only useful for your IDE to warn you of potentially null pointer errors.

As said in the "Clean Code" book, you should check your public method's parameters and also avoid checking invariants.

Another good tip is never returning null values, but using Null Object Pattern instead.

RS256 vs HS256: What's the difference?

short answer, specific to OAuth2,

  • HS256 user client secret to generate the token signature and same secret is required to validate the token in back-end. So you should have a copy of that secret in your back-end server to verify the signature.
  • RS256 use public key encryption to sign the token.Signature(hash) will create using private key and it can verify using public key. So, no need of private key or client secret to store in back-end server, but back-end server will fetch the public key from openid configuration url in your tenant (https://[tenant]/.well-known/openid-configuration) to verify the token. KID parameter inside the access_toekn will use to detect the correct key(public) from openid-configuration.

What's the yield keyword in JavaScript?

Simplifying/elaborating on Nick Sotiros' answer (which I think is awesome), I think it's best to describe how one would start coding with yield.

In my opinion, the biggest advantage of using yield is that it will eliminate all the nested callback problems we see in code. It's hard to see how at first, which is why I decided to write this answer (for myself, and hopefully others!)

The way it does it is by introducing the idea of a co-routine, which is a function that can voluntarily stop/pause until it gets what it needs. In javascript, this is denoted by function*. Only function* functions can use yield.

Here's some typical javascript:

loadFromDB('query', function (err, result) {
  // Do something with the result or handle the error

This is clunky because now all of your code (which obviously needs to wait for this loadFromDB call) needs to be inside this ugly looking callback. This is bad for a few reasons...

  • All of your code is indented one level in
  • You have this end }) which you need to keep track of everywhere
  • All this extra function (err, result) jargon
  • Not exactly clear that you're doing this to assign a value to result

On the other hand, with yield, all of this can be done in one line with the help of the nice co-routine framework.

function* main() {
  var result = yield loadFromDB('query')

And so now your main function will yield where necessary when it needs to wait for variables and things to load. But now, in order to run this, you need to call a normal (non-coroutine function). A simple co-routine framework can fix this problem so that all you have to do is run this:


And start is defined (from Nick Sotiro' answer)

function start(routine, data) {
    result =;
    if(!result.done) {
        result.value(function(err, data) {
            if(err) routine.throw(err); // continue next iteration of routine with an exception
            else start(routine, data);  // continue next iteration of routine normally

And now, you can have beautiful code that is much more readable, easy to delete, and no need to fiddle with indents, functions, etc.

An interesting observation is that in this example, yield is actually just a keyword you can put before a function with a callback.

function* main() {
  console.log(yield function(cb) { cb(null, "Hello World") })

Would print "Hello World". So you can actually turn any callback function into using yield by simply creating the same function signature (without the cb) and returning function (cb) {}, like so:

function yieldAsyncFunc(arg1, arg2) {
  return function (cb) {
    realAsyncFunc(arg1, arg2, cb)

Hopefully with this knowledge you can write cleaner, more readable code that is easy to delete!

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

Append vs Extend

enter image description here

With append you can append a single element that will extend the list:

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

If you want to extend more than one element you should use extend, because you can only append one elment or one list of element:

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

So that you get a nested list

Instead with extend, you can extend a single element like this

>>> a = [1,2]
>>> a.extend([3])
>>> a

Or, differently, from append, extend more elements in one time without nesting the list into the original one (that's the reason of the name extend)

>>> a.extend([4,5,6])
>>> a

Adding one element with both methods

enter image description here

Both append and extend can add one element to the end of the list, though append is simpler.

append 1 element

>>> x = [1,2]
>>> x.append(3)
>>> x

extend one element

>>> x = [1,2]
>>> x.extend([3])
>>> x

Adding more elements... with different results

If you use append for more than one element, you have to pass a list of elements as arguments and you will obtain a NESTED list!

>>> x = [1,2]
>>> x.append([3,4])
>>> x

With extend, instead, you pass a list as an argument, but you will obtain a list with the new element that is not nested in the old one.

>>> z = [1,2] 
>>> z.extend([3,4])
>>> z

So, with more elements, you will use extend to get a list with more items. However, appending a list will not add more elements to the list, but one element that is a nested list as you can clearly see in the output of the code.

enter image description here

enter image description here

Moment get current date

Just call moment as a function without any arguments:


For timezone information with moment, look at the moment-timezone package:

Jquery href click - how can I fire up an event?

You are binding the click event to anchors with an href attribute with value sign_new.

Either bind anchors with class sign_new or bind anchors with href value #sign_up. I would prefer the former.

Stopping a JavaScript function when a certain condition is met

The return statement exits a function from anywhere within the function:

function something(x)
    if (x >= 10)
        // this leaves the function if x is at least 10.

    // this message displays only if x is less than 10.
    alert ("x is less than 10!");


Have a look at <openssl/pem.h>. It gives possible BEGIN markers.

Copying the content from the above link for quick reference:

#define PEM_STRING_X509_CRL "X509 CRL"
#define PEM_STRING_PKCS7    "PKCS7"
#define PEM_STRING_CMS      "CMS"

How does GPS in a mobile phone work exactly?

GPS, the Global Positioning System run by the United States Military, is free for civilian use, though the reality is that we're paying for it with tax dollars.

However, GPS on cell phones is a bit more murky. In general, it won't cost you anything to turn on the GPS in your cell phone, but when you get a location it usually involves the cell phone company in order to get it quickly with little signal, as well as get a location when the satellites aren't visible (since the gov't requires a fix even if the satellites aren't visible for emergency 911 purposes). It uses up some cellular bandwidth. This also means that for phones without a regular GPS receiver, you cannot use the GPS at all if you don't have cell phone service.

For this reason most cell phone companies have the GPS in the phone turned off except for emergency calls and for services they sell you (such as directions).

This particular kind of GPS is called assisted GPS (AGPS), and there are several levels of assistance used.


A normal GPS receiver listens to a particular frequency for radio signals. Satellites send time coded messages at this frequency. Each satellite has an atomic clock, and sends the current exact time as well.

The GPS receiver figures out which satellites it can hear, and then starts gathering those messages. The messages include time, current satellite positions, and a few other bits of information. The message stream is slow - this is to save power, and also because all the satellites transmit on the same frequency and they're easier to pick out if they go slow. Because of this, and the amount of information needed to operate well, it can take 30-60 seconds to get a location on a regular GPS.

When it knows the position and time code of at least 3 satellites, a GPS receiver can assume it's on the earth's surface and get a good reading. 4 satellites are needed if you aren't on the ground and you want altitude as well.


As you saw above, it can take a long time to get a position fix with a normal GPS. There are ways to speed this up, but unless you're carrying an atomic clock with you all the time, or leave the GPS on all the time, then there's always going to be a delay of between 5-60 seconds before you get a location.

In order to save cost, most cell phones share the GPS receiver components with the cellular components, and you can't get a fix and talk at the same time. People don't like that (especially when there's an emergency) so the lowest form of GPS does the following:

  1. Get some information from the cell phone company to feed to the GPS receiver - some of this is gross positioning information based on what cellular towers can 'hear' your phone, so by this time they already phone your location to within a city block or so.
  2. Switch from cellular to GPS receiver for 0.1 second (or some small, practically unoticable period of time) and collect the raw GPS data (no processing on the phone).
  3. Switch back to the phone mode, and send the raw data to the phone company
  4. The phone company processes that data (acts as an offline GPS receiver) and send the location back to your phone.

This saves a lot of money on the phone design, but it has a heavy load on cellular bandwidth, and with a lot of requests coming it requires a lot of fast servers. Still, overall it can be cheaper and faster to implement. They are reluctant, however, to release GPS based features on these phones due to this load - so you won't see turn by turn navigation here.

More recent designs include a full GPS chip. They still get data from the phone company - such as current location based on tower positioning, and current satellite locations - this provides sub 1 second fix times. This information is only needed once, and the GPS can keep track of everything after that with very little power. If the cellular network is unavailable, then they can still get a fix after awhile. If the GPS satellites aren't visible to the receiver, then they can still get a rough fix from the cellular towers.

But to completely answer your question - it's as free as the phone company lets it be, and so far they do not charge for it at all. I doubt that's going to change in the future. In the higher end phones with a full GPS receiver you may even be able to load your own software and access it, such as with mologogo on a motorola iDen phone - the J2ME development kit is free, and the phone is only $40 (prepaid phone with $5 credit). Unlimited internet is about $10 a month, so for $40 to start and $10 a month you can get an internet tracking system. (Prices circa August 2008)

It's only going to get cheaper and more full featured from here on out...

Re: Google maps and such

Yes, Google maps and all other cell phone mapping systems require a data connection of some sort at varying times during usage. When you move far enough in one direction, for instance, it'll request new tiles from its server. Your average phone doesn't have enough storage to hold a map of the US, nor the processor power to render it nicely. iPhone would be able to if you wanted to use the storage space up with maps, but given that most iPhones have a full time unlimited data plan most users would rather use that space for other things.

How to get featured image of a product in woocommerce

I got the solution . I tried this .

<?php $image = wp_get_attachment_image_src( get_post_thumbnail_id( $loop->post->ID ), 'single-post-thumbnail' );?>

    <img src="<?php  echo $image[0]; ?>" data-id="<?php echo $loop->post->ID; ?>">

How do I find duplicates across multiple columns?

Given a staging table with 70 columns and only 4 representing duplicates, this code will return the offending columns:

FROM Staging.dbo.Stage S


How to kill a process running on particular port in Linux?

I'm working on a Yocto Linux system that has a limited set of available Linux tools. I wanted to kill the process that was using a particular port (1883).

First, to see what ports we are listening to I used the following command:

root@root:~# netstat -lt
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       
tcp        0      0*               LISTEN      
tcp        0      0 localhost.localdomain:domain*               LISTEN      
tcp        0      0  *               LISTEN      
tcp        0      0  *               LISTEN      
tcp        0      0 :::hostmon              :::*                    LISTEN      
tcp        0      0 localhost:domain        :::*                    LISTEN      
tcp        0      0 :::ssh                  :::*                    LISTEN      
tcp        0      0 :::1883                 :::*                    LISTEN      

Next, I found the name of the process using port 1883 in the following way:

root@root:~# fuser 1883/tcp
root@root:~# ps | grep 290
  290 mosquitt 25508 S    /usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf
12141 root      8444 S    grep 290

As we can see above, it's the program /usr/sbin/mosquitto that's using port 1883.

Lastly, I killed the process:

root@root:~# systemctl stop mosquitto

I used systemctl becuase in this case it was a systemd service.

"Conversion to Dalvik format failed with error 1" on external JAR

I had the exact same error with a project containing protobuf lite (Protocol Buffers by Google) in its classpath. I guess the reason was the protobuf-lite.jar that was in my classpath and project-folder was built in my previous machine. When I downloaded Maven and re-built the protobuf-lite.jar file then added it anew as a user-library to my project everything worked fine.

Naming Classes - How to avoid calling everything a "<WhatEver>Manager"?

You can take a look at, I have analyzed there the most frequently used suffixes of class names of the .NET framework and some other libraries.

The top 20 are:

  • attribute
  • type
  • helper
  • collection
  • converter
  • handler
  • info
  • provider
  • exception
  • service
  • element
  • manager
  • node
  • option
  • factory
  • context
  • item
  • designer
  • base
  • editor

How to change python version in anaconda spyder

  1. Set python3 as a main version in the terminal: ln -sf python3 /usr/bin/python

  2. Install pip3: apt-get install python3-pip

  3. Update spyder: pip install -U spyder


How to make a 3-level collapsing menu in Bootstrap?

Bootstrap 2.3.x and later supports the dropdown-submenu..

<ul class="dropdown-menu">
            <li><a href="#">Login</a></li>
            <li class="dropdown-submenu">
                <a tabindex="-1" href="#">More options</a>
                <ul class="dropdown-menu">
                    <li><a tabindex="-1" href="#">Second level</a></li>
                    <li><a href="#">Second level</a></li>
                    <li><a href="#">Second level</a></li>
            <li><a href="#">Logout</a></li>

Working demo on

Call a global variable inside module

If it is something that you reference but never mutate, then use const:

declare const bootbox;

Revert a jQuery draggable object back to its original container on out event of droppable

$(function() {
        revert : function(event, ui) {
            // on older version of jQuery use "draggable"
            // $(this).data("draggable")
            // on 2.x versions of jQuery use "ui-draggable"
            // $(this).data("ui-draggable")
            $(this).data("uiDraggable").originalPosition = {
                top : 0,
                left : 0
            // return boolean
            return !event;
            // that evaluate like this:
            // return event !== false ? false : true;

Why can't non-default arguments follow default arguments?

Required arguments (the ones without defaults), must be at the start to allow client code to only supply two. If the optional arguments were at the start, it would be confusing:

fun1("who is who", 3, "jack")

What would that do in your first example? In the last, x is "who is who", y is 3 and a = "jack".

Is a view faster than a simple query?

Definitely a view is better than a nested query for SQL Server. Without knowing exactly why it is better (until I read Mark Brittingham's post), I had run some tests and experienced almost shocking performance improvements when using a view versus a nested query. After running each version of the query several hundred times in a row, the view version of the query completed in half the time. I'd say that's proof enough for me.

jQuery Set Selected Option Using Next

Find the row, then

var row = $('#yourTable');

the value you want to select

var theValue = "5";

Dynamically display a CSV file as an HTML table on a web page has tool to convert csv to html table. Here is the link:

I used your sample data, and got the following html table:

<!--Created with XmlGrid Free Online XML Editor (>
  <td> Age</td>
  <td> Sex</td>
  <td>Cantor, Georg</td>
  <td> 163</td>
  <td> M</td>

IIS - 401.3 - Unauthorized

  1. Create a new Site, Right Click on Sites folder then click add Site
  2. Enter the site name.
  3. Select physical path
  4. Select Ip Address
  5. Change Port
  6. Click OK
  7. Go to Application Pools
  8. Select the site pool
  9. Right-click the click Advance Settings
  10. Change the .Net CLR Version to "No Manage Code"
  11. Change the Identity to "ApplicationPoolIdentity"
  12. Go to Site home page then click "Authentication"
  13. Right-click to AnonymousAuthentication then click "Edit"
  14. Select Application Pool Identity
  15. Click ok
  16. boom!

for routes add a web.config

                <rule name="React Routes" stopProcessing="true">
                    <match url=".*" />
                    <conditions logicalGrouping="MatchAll">
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                        <add input="{REQUEST_URI}" pattern="^/(api)" negate="true" />
                    <action type="Rewrite" url="/" />

String representation of an Enum

How I solved this as an extension method:

using System.ComponentModel;
public static string GetDescription(this Enum value)
    var descriptionAttribute = (DescriptionAttribute)value.GetType()
        .Where(a => a is DescriptionAttribute)

    return descriptionAttribute != null ? descriptionAttribute.Description : value.ToString();


public enum OrderType
    None = 0,
    [Description("New Card")]
    NewCard = 1,
    Refill = 2

Usage (where o.OrderType is a property with the same name as the enum):


Which gives me a string of "New Card" or "Reload" instead of the actual enum value NewCard and Refill.

Effective swapping of elements of an array in Java

Solution for object and primitive types:

public static final <T> void swap(final T[] arr, final int i, final int j) {
    T tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final boolean[] arr, final int i, final int j) {
    boolean tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final byte[] arr, final int i, final int j) {
    byte tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final short[] arr, final int i, final int j) {
    short tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final int[] arr, final int i, final int j) {
    int tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final long[] arr, final int i, final int j) {
    long tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final char[] arr, final int i, final int j) {
    char tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final float[] arr, final int i, final int j) {
    float tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
public static final void swap(final double[] arr, final int i, final int j) {
    double tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;

Adding an image to a project in Visual Studio

You need to turn on Show All Files option on solution pane toolbar and include this file manually.

JPA eager fetch does not join

The fetchType attribute controls whether the annotated field is fetched immediately when the primary entity is fetched. It does not necessarily dictate how the fetch statement is constructed, the actual sql implementation depends on the provider you are using toplink/hibernate etc.

If you set fetchType=EAGER This means that the annotated field is populated with its values at the same time as the other fields in the entity. So if you open an entitymanager retrieve your person objects and then close the entitymanager, subsequently doing a person.address will not result in a lazy load exception being thrown.

If you set fetchType=LAZY the field is only populated when it is accessed. If you have closed the entitymanager by then a lazy load exception will be thrown if you do a person.address. To load the field you need to put the entity back into an entitymangers context with em.merge(), then do the field access and then close the entitymanager.

You might want lazy loading when constructing a customer class with a collection for customer orders. If you retrieved every order for a customer when you wanted to get a customer list this may be a expensive database operation when you only looking for customer name and contact details. Best to leave the db access till later.

For the second part of the question - how to get hibernate to generate optimised SQL?

Hibernate should allow you to provide hints as to how to construct the most efficient query but I suspect there is something wrong with your table construction. Is the relationship established in the tables? Hibernate may have decided that a simple query will be quicker than a join especially if indexes etc are missing.

Check if a specific value exists at a specific key in any subarray of a multidimensional array

function checkMultiArrayValue($array) {
        global $test;
        foreach ($array as $key => $item) {

            if(!empty($item) && is_array($item)) {
            }else {
                 $test[$key] = $item;

        return $test;   

 $multiArray = array(    
                0 =>  array(  
                      "country"   => "",  
                      "price"    => 4,  
                      "discount-price" => 0,  

$test = checkMultiArrayValue($multiArray);
echo "<pre>"

Will return array who have index and value

How to set image button backgroundimage for different state?

i think you problem is not the selector file.

you have to add

<imagebutton ..

to your image buttons.

by default the onClick is handled at the listitem level (parent). and the imageButtons dont recieve the onClick.

when you add the above attribute the image button will receive the event and the selector will be used.

check this POST which explains the same for checkbox.

What does body-parser do with express?

Yes we can work without body-parser. When you don't use that you get the raw request, and your body and headers are not in the root object of request parameter . You will have to individually manipulate all the fields.

Or you can use body-parser, as the express team is maintaining it .

What body-parser can do for you: It simplifies the request.
How to use it: Here is example:

Install npm install body-parser --save

This how to use body-parser in express:

const express = require('express'),
      app = express(),
      bodyParser = require('body-parser');

// support parsing of application/json type post data

//support parsing of application/x-www-form-urlencoded post data
app.use(bodyParser.urlencoded({ extended: true }));


And then you can get body and headers in root request object . Example"/posturl",function(req,res,next){

Hadoop "Unable to load native-hadoop library for your platform" warning

The answer depends... I just installed Hadoop 2.6 from tarball on 64-bit CentOS 6.6. The Hadoop install did indeed come with a prebuilt 64-bit native library. For my install, it is here:


And I know it is 64-bit:

[hadoop@VMWHADTEST01 native]$ ldd
./ /lib64/ version `GLIBC_2.14' not found (required by ./ =>  (0x00007fff43510000) => /lib64/ (0x00007f9be553a000) => /lib64/ (0x00007f9be51a5000)
/lib64/ (0x00007f9be5966000)

Unfortunately, I stupidly overlooked the answer right there staring me in the face as I was focuses on, "Is this library 32 pr 64 bit?":

`GLIBC_2.14' not found (required by ./

So, lesson learned. Anyway, the rest at least led me to being able to suppress the warning. So I continued and did everything recommended in the other answers to provide the library path using the HADOOP_OPTS environment variable to no avail. So I looked at the source code. The module that generates the error tells you the hint (util.NativeCodeLoader):

15/06/18 18:59:23 WARN util.NativeCodeLoader: Unable to load native-hadoop    library for your platform... using builtin-java classes where applicable

So, off to here to see what it does:

Ah, there is some debug level logging - let's turn that on a see if we get some additional help. This is done by adding the following line to $HADOOP_CONF_DIR/ file:

Then I ran a command that generates the original warning, like, and got this goodie:

15/06/18 19:05:19 DEBUG util.NativeCodeLoader: Failed to load native-hadoop with error: java.lang.UnsatisfiedLinkError: /opt/hadoop/lib/native/ /lib64/ version `GLIBC_2.14' not found (required by /opt/hadoop/lib/native/

And the answer is revealed in this snippet of the debug message (the same thing that the previous ldd command 'tried' to tell me:

`GLIBC_2.14' not found (required by opt/hadoop/lib/native/

What version of GLIBC do I have? Here's simple trick to find out:

[hadoop@VMWHADTEST01 hadoop]$ ldd --version
ldd (GNU libc) 2.12

So, can't update my OS to 2.14. Only solution is to build the native libraries from sources on my OS or suppress the warning and just ignore it for now. I opted to just suppress the annoying warning for now (but do plan to build from sources in the future) buy using the same logging options we used to get the debug message, except now, just make it ERROR level.

I hope this helps others see that a big benefit of open source software is that you can figure this stuff out if you take some simple logical steps.

Sort a list of lists with a custom compare function

You need to slightly modify your compare function and use functools.cmp_to_key to pass it to sorted. Example code:

import functools

lst = [list(range(i, i+5)) for i in range(5, 1, -1)]

def fitness(item):
    return item[0]+item[1]+item[2]+item[3]+item[4]
def compare(item1, item2):
    return fitness(item1) - fitness(item2)

sorted(lst, key=functools.cmp_to_key(compare))


[[2, 3, 4, 5, 6], [3, 4, 5, 6, 7], [4, 5, 6, 7, 8], [5, 6, 7, 8, 9]]

Works :)

Delete specified file from document directory

FreeGor version converted to Swift 3.0

 func removeOldFileIfExist() {
    let paths = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
    if paths.count > 0 {
        let dirPath = paths[0]
        let fileName = "filename.jpg"
        let filePath = NSString(format:"%@/%@", dirPath, fileName) as String
        if FileManager.default.fileExists(atPath: filePath) {
            do {
                try FileManager.default.removeItem(atPath: filePath)
                print("User photo has been removed")
            } catch {
                print("an error during a removing")

Reading from memory stream to string

string result = System.Text.Encoding.UTF8.GetString(fs.ToArray());

Read/write files within a Linux kernel module

Since version 4.14 of Linux kernel, vfs_read and vfs_write functions are no longer exported for use in modules. Instead, functions exclusively for kernel's file access are provided:

# Read the file from the kernel space.
ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos);

# Write the file from the kernel space.
ssize_t kernel_write(struct file *file, const void *buf, size_t count,
            loff_t *pos);

Also, filp_open no longer accepts user-space string, so it can be used for kernel access directly (without dance with set_fs).

What is the purpose of Node.js module.exports and how do you use it?

let test = function() {
    return "Hello world"
exports.test = test;

IntelliJ inspection gives "Cannot resolve symbol" but still compiles code

If nothing works out, right click on your source directory , mark directory as "Source Directory" and then right click on project directory and maven -> re-import.

this resolved my issue.

C char array initialization

Edit: OP (or an editor) silently changed some of the single quotes in the original question to double quotes at some point after I provided this answer.

Your code will result in compiler errors. Your first code fragment:

char buf[10] ; buf = ''

is doubly illegal. First, in C, there is no such thing as an empty char. You can use double quotes to designate an empty string, as with:

char* buf = ""; 

That will give you a pointer to a NUL string, i.e., a single-character string with only the NUL character in it. But you cannot use single quotes with nothing inside them--that is undefined. If you need to designate the NUL character, you have to specify it:

char buf = '\0';

The backslash is necessary to disambiguate from character '0'.

char buf = 0;

accomplishes the same thing, but the former is a tad less ambiguous to read, I think.

Secondly, you cannot initialize arrays after they have been defined.

char buf[10];

declares and defines the array. The array identifier buf is now an address in memory, and you cannot change where buf points through assignment. So

buf =     // anything on RHS

is illegal. Your second and third code fragments are illegal for this reason.

To initialize an array, you have to do it at the time of definition:

char buf [10] = ' ';

will give you a 10-character array with the first char being the space '\040' and the rest being NUL, i.e., '\0'. When an array is declared and defined with an initializer, the array elements (if any) past the ones with specified initial values are automatically padded with 0. There will not be any "random content".

If you declare and define the array but don't initialize it, as in the following:

char buf [10];

you will have random content in all the elements.

Set div height equal to screen size

Using CSS {height: 100%;} matches the height of the parent. This could be anything, meaning smaller or bigger than the screen. Using {height: 100vh;} matches the height of the viewport.

.container {
    height: 100vh;
    overflow: auto;

According to Mozilla's official documents, 1vh is:

Equal to 1% of the height of the viewport's initial containing block.

sequelize findAll sort order in nodejs

You can accomplish this in a very back-handed way with the following code:

exports.getStaticCompanies = function () {
    var ids = [46128, 2865, 49569, 1488, 45600, 61991, 1418, 61919, 53326, 61680]
    return Company.findAll({
        where: {
            id: ids
        attributes: ['id', 'logo_version', 'logo_content_type', 'name', 'updated_at'],
        order: sequelize.literal('(' + {
            return '"Company"."id" = \'' + id + '\'');
        }).join(', ') + ') DESC')

This is somewhat limited because it's got very bad performance characteristics past a few dozen records, but it's acceptable at the scale you're using.

This will produce a SQL query that looks something like this:

[...] ORDER BY ("Company"."id"='46128', "Company"."id"='2865', "Company"."id"='49569', [...])

How to check a string for a special character?

You will need to define "special characters", but it's likely that for some string s you mean:

import re
if re.match(r'^\w+$', s):
    # s is good-to-go

Detect all changes to a <input type="text"> (immediately) using JQuery

Here's a working example that I'm using to implement an autocomplete variation the populates a jqueryui selector (list), but I don't want it to function exactly like the jqueryui autocomplete which does a drop-down menu.

$("#tagFilter").on("change keyup paste", function() {
     var filterText = $("#tagFilter").val();
    $.getJSON("http://localhost/cgi-bin/tags.php?term=" + filterText,
        function(data) {
            var i;
            for (i = 0; i < data.length; i++) {
                var tag = data[i].value;
                $("#tags").append("<li class=\"tag\">" + tag + "</li>");

How to add and remove item from array in components in Vue 2

There are few mistakes you are doing:

  1. You need to add proper object in the array in addRow method
  2. You can use splice method to remove an element from an array at particular index.
  3. You need to pass the current row as prop to my-item component, where this can be modified.

You can see working code here.

   this.rows.push({description: '', unitprice: '' , code: ''}); // what to push unto the rows array?
   this. itemList.splice(index, 1)

How to do ToString for a possibly null object?

Some (speed) performance tests summarizing the various options, not that it really matters #microoptimization (using a linqpad extension)


void Main()
    object objValue = null;
    string strValue = null;

// Define other methods and classes here
void test(string value) {
    new Perf<string> {
        { "coallesce", n => (value ?? string.Empty).ToString() },
        { "nullcheck", n => value == null ? string.Empty : value.ToString() },
        { "str.Format", n => string.Format("{0}", value) },
        { "str.Concat", n => string.Concat(value) },
        { "string +", n => "" + value },
        { "Convert", n => Convert.ToString(value) },

void test(object value) {
    new Perf<string> {
        { "coallesce", n => (value ?? string.Empty).ToString() },
        { "nullcheck", n => value == null ? string.Empty : value.ToString() },
        { "str.Format", n => string.Format("{0}", value) },
        { "str.Concat", n => string.Concat(value) },
        { "string +", n => "" + value },
        { "Convert", n => Convert.ToString(value) },

Probably important to point out that Convert.ToString(...) will retain a null string.



  • nullcheck 1.00x 1221 ticks elapsed (0.1221 ms) [in 10K reps, 1.221E-05 ms per]
  • coallesce 1.14x 1387 ticks elapsed (0.1387 ms) [in 10K reps, 1.387E-05 ms per]
  • string + 1.16x 1415 ticks elapsed (0.1415 ms) [in 10K reps, 1.415E-05 ms per]
  • str.Concat 1.16x 1420 ticks elapsed (0.142 ms) [in 10K reps, 1.42E-05 ms per]
  • Convert 1.58x 1931 ticks elapsed (0.1931 ms) [in 10K reps, 1.931E-05 ms per]
  • str.Format 5.45x 6655 ticks elapsed (0.6655 ms) [in 10K reps, 6.655E-05 ms per]


  • nullcheck 1.00x 1190 ticks elapsed (0.119 ms) [in 10K reps, 1.19E-05 ms per]
  • Convert 1.01x 1200 ticks elapsed (0.12 ms) [in 10K reps, 1.2E-05 ms per]
  • string + 1.04x 1239 ticks elapsed (0.1239 ms) [in 10K reps, 1.239E-05 ms per]
  • coallesce 1.20x 1423 ticks elapsed (0.1423 ms) [in 10K reps, 1.423E-05 ms per]
  • str.Concat 4.57x 5444 ticks elapsed (0.5444 ms) [in 10K reps, 5.444E-05 ms per]
  • str.Format 5.67x 6750 ticks elapsed (0.675 ms) [in 10K reps, 6.75E-05 ms per]

Return values from the row above to the current row

This formula does not require a column letter reference ("A", "B", etc.). It returns the value of the cell one row above in the same column.


Changing image size in Markdown

One might draw on the alt attribute that can be set in almost all Markdown implementations/renderes together with CSS-selectors based on attribute values. The advantage is that one can easily define a whole set of different picture sizes (and further attributes).




img[alt="minipic"] { 
  max-width:  20px; 
  display: block;

Align items in a stack panel?

For those who stumble upon this question, here's how to achieve this layout with a Grid:

    <TextBlock Text="Server:"/>
    <TextBlock Text="" HorizontalAlignment="Right"/>



IDEA: javac: source release 1.7 requires target release 1.7

Have you looked at your build configuration it should like that if you use maven 3 and JDK 7


How to send email from Terminal?

echo "this is the body" | mail -s "this is the subject" "to@address"

Using %s in C correctly - very basic level

%s is the representation of an array of char

char string[10] // here is a array of chars, they max length is 10;
char character; // just a char 1 letter/from the ascii map

character = 'a'; // assign 'a' to character
printf("character %c  ",a); //we will display 'a' to stout

so string is an array of char we can assign multiple character per space of memory

string[5]=(char) 0;//asigning the last element of the 'word' a mark so the string ends

this assignation can be done at initialization like char word="this is a word" // the word array of chars got this string now and is statically defined

toy can also assign values to the array of chars assigning it with functions like strcpy;

strcpy(string,"hello" );

this do the same as the example and automatically add the (char) 0 at the end

so if you print it with %S printf("my string %s",string);

and how string is a array we can just display part of it

//                         the array    one char
printf("first letter of wrd %s     is    :%c ",string,string[1]  );

What does functools.wraps do?

  1. Prerequisite: You must know how to use decorators and specially with wraps. This comment explains it a bit clear or this link also explains it pretty well.

  2. Whenever we use For eg: @wraps followed by our own wrapper function. As per the details given in this link , it says that

functools.wraps is convenience function for invoking update_wrapper() as a function decorator, when defining a wrapper function.

It is equivalent to partial(update_wrapper, wrapped=wrapped, assigned=assigned, updated=updated).

So @wraps decorator actually gives a call to functools.partial(func[,*args][, **keywords]).

The functools.partial() definition says that

The partial() is used for partial function application which “freezes” some portion of a function’s arguments and/or keywords resulting in a new object with a simplified signature. For example, partial() can be used to create a callable that behaves like the int() function where the base argument defaults to two:

>>> from functools import partial
>>> basetwo = partial(int, base=2)
>>> basetwo.__doc__ = 'Convert base 2 string to an int.'
>>> basetwo('10010')

Which brings me to the conclusion that, @wraps gives a call to partial() and it passes your wrapper function as a parameter to it. The partial() in the end returns the simplified version i.e the object of what's inside the wrapper function and not the wrapper function itself.

remote rejected master -> master (pre-receive hook declined)

I have just run the heroku logs command and checked the git status then retried the git push hreoku master and it worked

What does "#include <iostream>" do?

That is a C++ standard library header file for input output streams. It includes functionality to read and write from streams. You only need to include it if you wish to use streams.

How to undo 'git reset'?

Short answer:

git reset 'HEAD@{1}'

Long answer:

Git keeps a log of all ref updates (e.g., checkout, reset, commit, merge). You can view it by typing:

git reflog

Somewhere in this list is the commit that you lost. Let's say you just typed git reset HEAD~ and want to undo it. My reflog looks like this:

$ git reflog
3f6db14 HEAD@{0}: HEAD~: updating HEAD
d27924e HEAD@{1}: checkout: moving from d27924e0fe16776f0d0f1ee2933a0334a4787b4c

The first line says that HEAD 0 positions ago (in other words, the current position) is 3f6db14; it was obtained by resetting to HEAD~. The second line says that HEAD 1 position ago (in other words, the state before the reset) is d27924e. It was obtained by checking out a particular commit (though that's not important right now). So, to undo the reset, run git reset HEAD@{1} (or git reset d27924e).

If, on the other hand, you've run some other commands since then that update HEAD, the commit you want won't be at the top of the list, and you'll need to search through the reflog.

One final note: It may be easier to look at the reflog for the specific branch you want to un-reset, say master, rather than HEAD:

$ git reflog show master
c24138b master@{0}: merge origin/master: Fast-forward
90a2bf9 master@{1}: merge origin/master: Fast-forward

This should have less noise it in than the general HEAD reflog.

Should I always use a parallel stream when possible?

The Stream API was designed to make it easy to write computations in a way that was abstracted away from how they would be executed, making switching between sequential and parallel easy.

However, just because its easy, doesn't mean its always a good idea, and in fact, it is a bad idea to just drop .parallel() all over the place simply because you can.

First, note that parallelism offers no benefits other than the possibility of faster execution when more cores are available. A parallel execution will always involve more work than a sequential one, because in addition to solving the problem, it also has to perform dispatching and coordinating of sub-tasks. The hope is that you'll be able to get to the answer faster by breaking up the work across multiple processors; whether this actually happens depends on a lot of things, including the size of your data set, how much computation you are doing on each element, the nature of the computation (specifically, does the processing of one element interact with processing of others?), the number of processors available, and the number of other tasks competing for those processors.

Further, note that parallelism also often exposes nondeterminism in the computation that is often hidden by sequential implementations; sometimes this doesn't matter, or can be mitigated by constraining the operations involved (i.e., reduction operators must be stateless and associative.)

In reality, sometimes parallelism will speed up your computation, sometimes it will not, and sometimes it will even slow it down. It is best to develop first using sequential execution and then apply parallelism where

(A) you know that there's actually benefit to increased performance and

(B) that it will actually deliver increased performance.

(A) is a business problem, not a technical one. If you are a performance expert, you'll usually be able to look at the code and determine (B), but the smart path is to measure. (And, don't even bother until you're convinced of (A); if the code is fast enough, better to apply your brain cycles elsewhere.)

The simplest performance model for parallelism is the "NQ" model, where N is the number of elements, and Q is the computation per element. In general, you need the product NQ to exceed some threshold before you start getting a performance benefit. For a low-Q problem like "add up numbers from 1 to N", you will generally see a breakeven between N=1000 and N=10000. With higher-Q problems, you'll see breakevens at lower thresholds.

But the reality is quite complicated. So until you achieve experthood, first identify when sequential processing is actually costing you something, and then measure if parallelism will help.

How to replace text in a column of a Pandas dataframe?

If you only need to replace characters in one specific column, somehow regex=True and in place=True all failed, I think this way will work:

data["column_name"] = data["column_name"].apply(lambda x: x.replace("characters_need_to_replace", "new_characters"))

lambda is more like a function that works like a for loop in this scenario. x here represents every one of the entries in the current column.

The only thing you need to do is to change the "column_name", "characters_need_to_replace" and "new_characters".

Cast Object to Generic Type for returning

I stumble upon this question and it grabbed my interest. The accepted answer is completely correct, but I thought I do provide my findings at JVM byte code level to explain why the OP encounter the ClassCastException.

I have the code which is pretty much the same as OP's code:

public static <T> T convertInstanceOfObject(Object o) {
    try {
       return (T) o;
    } catch (ClassCastException e) {
        return null;

public static void main(String[] args) {
    String k = convertInstanceOfObject(345435.34);

and the corresponding byte code is:

public static <T> T convertInstanceOfObject(java.lang.Object);
       0: aload_0
       1: areturn
       2: astore_1
       3: aconst_null
       4: areturn
    Exception table:
       from    to  target type
           0     1     2   Class java/lang/ClassCastException

  public static void main(java.lang.String[]);
       0: ldc2_w        #3                  // double 345435.34d
       3: invokestatic  #5                  // Method java/lang/Double.valueOf:(D)Ljava/lang/Double;
       6: invokestatic  #6                  // Method convertInstanceOfObject:(Ljava/lang/Object;)Ljava/lang/Object;
       9: checkcast     #7                  // class java/lang/String
      12: astore_1
      13: getstatic     #8                  // Field java/lang/System.out:Ljava/io/PrintStream;
      16: aload_1
      17: invokevirtual #9                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V
      20: return

Notice that checkcast byte code instruction happens in the main method not the convertInstanceOfObject and convertInstanceOfObject method does not have any instruction that can throw ClassCastException. Because the main method does not catch the ClassCastException hence when you execute the main method you will get a ClassCastException and not the expectation of printing null.

Now I modify the code to the accepted answer:

public static <T> T convertInstanceOfObject(Object o, Class<T> clazz) {
        try {
            return clazz.cast(o);
        } catch (ClassCastException e) {
            return null;
    public static void main(String[] args) {
        String k = convertInstanceOfObject(345435.34, String.class);

The corresponding byte code is:

public static <T> T convertInstanceOfObject(java.lang.Object, java.lang.Class<T>);
       0: aload_1
       1: aload_0
       2: invokevirtual #2                  // Method java/lang/Class.cast:(Ljava/lang/Object;)Ljava/lang/Object;
       5: areturn
       6: astore_2
       7: aconst_null
       8: areturn
    Exception table:
       from    to  target type
           0     5     6   Class java/lang/ClassCastException

  public static void main(java.lang.String[]);
       0: ldc2_w        #4                  // double 345435.34d
       3: invokestatic  #6                  // Method java/lang/Double.valueOf:(D)Ljava/lang/Double;
       6: ldc           #7                  // class java/lang/String
       8: invokestatic  #8                  // Method convertInstanceOfObject:(Ljava/lang/Object;Ljava/lang/Class;)Ljava/lang/Object;
      11: checkcast     #7                  // class java/lang/String
      14: astore_1
      15: getstatic     #9                  // Field java/lang/System.out:Ljava/io/PrintStream;
      18: aload_1
      19: invokevirtual #10                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
      22: return

Notice that there is an invokevirtual instruction in the convertInstanceOfObject method that calls Class.cast() method which throws ClassCastException which will be catch by the catch(ClassCastException e) bock and return null; hence, "null" is printed to console without any exception.

Latex Multiple Linebreaks

Do you want more space between paragraphs? Then you can change the parameter \parskip.

For example, try

\setlength{\parskip}{10pt plus 1pt minus 1pt}

This means that the space between paragraphs is usually 10pt, but can grow or shrink by up to 1pt. This means you give LaTeX the ability to change it up to one 1pt in order to achieve a better page layout. You can remove the plus and minus parts to make it always your specified length.

If you are trying to display source code, try the listings package or use verbatim. If you are trying to typeset pseudocode, try the algorithm package.

Does `anaconda` create a separate PYTHONPATH variable for each new environment?

Anaconda does not use the PYTHONPATH. One should however note that if the PYTHONPATH is set it could be used to load a library that is not in the anaconda environment. That is why before activating an environment it might be good to do a


For instance this PYTHONPATH points to an incorrect pandas lib:

export PYTHONPATH=/home/john/share/usr/anaconda/lib/python
source activate anaconda-2.7
>>>> import pandas as pd
/home/john/share/usr/lib/python/pandas-0.12.0-py2.7-linux-x86_64.egg/pandas/ undefined symbol: PyUnicodeUCS2_DecodeUTF8
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/john/share/usr/lib/python/pandas-0.12.0-py2.7-linux-x86_64.egg/pandas/", line 6, in <module>
    from . import hashtable, tslib, lib
ImportError: /home/john/share/usr/lib/python/pandas-0.12.0-py2.7-linux-x86_64.egg/pandas/ undefined symbol: PyUnicodeUCS2_DecodeUTF8

unsetting the PYTHONPATH prevents the wrong pandas lib from being loaded:

source activate anaconda-2.7
>>>> import pandas as pd

How can I keep a container running on Kubernetes?

My few cents on the subject. Assuming that kubectl is working then the closest command that would be equivalent to the docker command that you mentioned in your question, would be something like this.

$ kubectl run ubuntu --image=ubuntu --restart=Never --command sleep infinity

Above command will create a single Pod in default namespace and, it will execute sleep command with infinity argument -this way you will have a process that runs in foreground keeping container alive.

Afterwords, you can interact with Pod by running kubectl exec command.

$ kubectl exec ubuntu -it -- bash

This technique is very useful for creating a Pod resource and ad-hoc debugging.

How to increment a pointer address and pointer's value?

First, the ++ operator takes precedence over the * operator, and the () operators take precedence over everything else.

Second, the ++number operator is the same as the number++ operator if you're not assigning them to anything. The difference is number++ returns number and then increments number, and ++number increments first and then returns it.

Third, by increasing the value of a pointer, you're incrementing it by the sizeof its contents, that is you're incrementing it as if you were iterating in an array.

So, to sum it all up:

ptr++;    // Pointer moves to the next int position (as if it was an array)
++ptr;    // Pointer moves to the next int position (as if it was an array)
++*ptr;   // The value of ptr is incremented
++(*ptr); // The value of ptr is incremented
++*(ptr); // The value of ptr is incremented
*ptr++;   // Pointer moves to the next int position (as if it was an array). But returns the old content
(*ptr)++; // The value of ptr is incremented
*(ptr)++; // Pointer moves to the next int position (as if it was an array). But returns the old content
*++ptr;   // Pointer moves to the next int position, and then get's accessed, with your code, segfault
*(++ptr); // Pointer moves to the next int position, and then get's accessed, with your code, segfault

As there are a lot of cases in here, I might have made some mistake, please correct me if I'm wrong.


So I was wrong, the precedence is a little more complicated than what I wrote, view it here:

Zsh: Conda/Pip installs command not found

For Linux

  1. Open .bashrc
  2. Copy the code for conda initialize and paste it to .zshrc file
  3. Finally run source .zshrc

How to check queue length in Python

Yes we can check the length of queue object created from collections.

from collections import deque
class Queue():
    def __init__(self,batchSize=32):
        #self.batchSie = batchSize
        self._queue = deque(maxlen=batchSize)

    def enqueue(self, items):
        ''' Appending the items to the queue'''

    def dequeue(self):
        '''remoe the items from the top if the queue becomes full '''
        return self._queue.popleft()

Creating an object of class

q = Queue(batchSize=64)

Now retrieving the length of the queue

#check the len of queue
#you can print the content of the queue
#Can check the content of the queue
#Check the length of retrieved item 

check the results in attached screen shot

enter image description here

Hope this helps...

Unable to open a file with fopen()

How are you running the file? Is it from the command line or from an IDE? The directory that your executable is in is not necessarily your working directory.

Try using the full path name in the fopen and see if that fixes it. If so, then the problem is as described.

For example:

file = fopen("c:\\MyDirectory\\TestFile1.txt", "r");
file = fopen("/full/path/to/TestFile1.txt", "r");

Or open up a command window and navigate to the directory where your executable is, then run it manually.

As an aside, you can insert a simple (for Windows or Linux/UNIX/BSD/etc respectively):

system ("cd")

before the fopen to show which directory you're actually in.

Cannot open include file: 'unistd.h': No such file or directory

If you're using ZLib in your project, then you need to find :

#if 1

in zconf.h and replace(uncomment) it with :

#if HAVE_UNISTD_H /* ...the rest of the line

If it isn't ZLib I guess you should find some alternative way to do this. GL.

Saving ssh key fails

You have to create the .ssh folder yourself for saving ssh keys.

By the way, I used this path style: C:/Users/you/.ssh/id_rsa

How to use NULL or empty string in SQL

Select *
From Table
Where (col is null or col = '')


Select *
From Table
Where IsNull(col, '') = ''

A SQL Query to select a string between two known strings

The problem is that the second part of your substring argument is including the first index. You need to subtract the first index from your second index to make this work.

, CHARINDEX('immediately',@text) - CHARINDEX('the dog', @Text) + Len('immediately'))

How to pass multiple parameters in thread in VB

Pass multiple parameter for VB.NET 3.5

 Public Class MyWork

    Public Structure thread_Data            
        Dim TCPIPAddr As String
        Dim TCPIPPort As Integer            
    End Structure

    Dim STthread_Data As thread_Data
    STthread_Data.TCPIPAddr = ""
    STthread_Data.TCPIPPort = 80  

    Dim multiThread As Thread = New Thread(AddressOf testthread)

    Private Function testthread(ByVal STthread_Data As thread_Data) 
        Dim IPaddr as string = STthread_Data.TCPIPAddr
        Dim IPport as integer = STthread_Data.TCPIPPort
        'Your work'        
    End Function

End Class

invalid operands of types int and double to binary 'operator%'

Because % is only defined for integer types. That's the modulus operator.

5.6.2 of the standard:

The operands of * and / shall have arithmetic or enumeration type; the operands of % shall have integral or enumeration type. [...]

As Oli pointed out, you can use fmod(). Don't forget to include math.h.

best OCR (Optical character recognition) example in android

Like you I also faced many problems implementing OCR in Android, but after much Googling I found the solution, and it surely is the best example of OCR.

Let me explain using step-by-step guidance.

First, download the source code from

Import all three projects. After importing you will get an error. To solve the error you have to create a res folder in the tess-two project

enter image description here

First, just create res folder in tess-two by tess-two->RightClick->new Folder->Name it "res"

After doing this in all three project the error should be gone.

Now download the source code from, here you will get best example.

Now you just need to import it into your workspace, but first you have to download android-ndk from this site: i have windows 7 - 32 bit PC so I have download this file

Now extract it suppose I have extract it into E:\Software\android-ndk-r9 so I will set this path on Environment Variable

Right Click on MyComputer->Property->Advance-System-Settings->Advance->Environment Variable-> find PATH on second below Box and set like path like below picture

enter image description here

done it

Now open cmd and go to on D:\Android Workspace\tess-two like below

enter image description here

If you have successfully set up environment variable of NDK then just type ndk-build just like above picture than enter you will not get any kind of error and all file will be compiled successfully:

Now download other source code also from , and extract and import it and give it name OCRTest, like in my PC which is in D:\Android Workspace\OCRTest

enter image description here

Import test-two in this and run OCRTest and run it; you will get the best example of OCR.

How to change current Theme at runtime in Android

I would like to see the method too, where you set once for all your activities. But as far I know you have to set in each activity before showing any views.

For reference check this:

Edit (copied from that forum):

    protected void onCreate(Bundle savedInstanceState) {

        // Call setTheme before creation of any(!) View.

        // ...

If you call setTheme after super.onCreate(savedInstanceState); your activity recreated but if you call setTheme before super.onCreate(savedInstanceState); your theme will set and activity does not recreate anymore

  protected void onCreate(Bundle savedInstanceState) {

    // ...

How to divide flask app into multiple py files?

I would like to recommend flask-empty at GitHub.

It provides an easy way to understand Blueprints, multiple views and extensions.

How to restart a node.js server

If it's just running (not a daemon) then just use Ctrl-C.

If it's daemonized then you could try:

$ ps aux | grep node
you   PID  1.5  0.2  44172  8260 pts/2    S    15:25   0:00 node app.js
$ kill -2 PID

Where PID is replaced by the number in the output of ps.

Inserting values to SQLite table in Android

You'll find debugging errors like this a lot easier if you catch any errors thrown from the execSQL call. eg:

 catch (Exception e) 
       Log.e("ERROR", e.toString());

A non well formed numeric value encountered

This error occurs when you perform calculations with variables that use letters combined with numbers (alphanumeric), for example 24kb, 886ab ...

I had the error in the following function

function get_config_bytes($val) {
    $val = trim($val);
    $last = strtolower($val[strlen($val)-1]);       
    switch($last) {
        case 'g':
            $val *= 1024;
        case 'm':
            $val *= 1024;
        case 'k':
            $val *= 1024;
    return $this->fix_integer_overflow($val);

The application uploads images but it didn't work, it showed the following warning:

enter image description here

Solution: The intval() function extracts the integer value of a variable with alphanumeric data and creates a new variable with the same value but converted to an integer with the intval() function. Here is the code:

function get_config_bytes($val) {
    $val = trim($val);
    $last = strtolower($val[strlen($val)-1]);
    $intval = intval(trim($val));
    switch($last) {
        case 'g':
            $intval *= 1024;
        case 'm':
            $intval *= 1024;
        case 'k':
            $intval *= 1024;
    return $this->fix_integer_overflow($intval);

How to copy a huge table data into another table in SQL Server

If you are copying into a new table, the quickest way is probably what you have in your question, unless your rows are very large.

If your rows are very large, you may want to use the bulk insert functions in SQL Server. I think you can call them from C#.

Or you can first download that data into a text file, then bulk-copy (bcp) it. This has the additional benefit of allowing you to ignore keys, indexes etc.

Also try the Import/Export utility that comes with the SQL Management Studio; not sure whether it will be as fast as a straight bulk-copy, but it should allow you to skip the intermediate step of writing out as a flat file, and just copy directly table-to-table, which might be a bit faster than your SELECT INTO statement.

javac: file not found: Usage: javac <options> <source files>

I had the same issue and it was to do with my file name. If you set the file location using CD in CMD, and then type DIR it will list the files in that directory. Check that the file name appears and check that the spelling and filename ending is correct.

It should be .java but mine was .java.txt. The instructions on the Java tutorials website state that you should select "Save as Type Text Documents" but for me that always adds .txt onto the end of the file name. If I change it to "Save as Type All Documents" it correctly saved the file name.

CMD DIR Example

Export SQL query data to Excel

I don't know if this is what you're looking for, but you can export the results to Excel like this:

In the results pane, click the top-left cell to highlight all the records, and then right-click the top-left cell and click "Save Results As". One of the export options is CSV.

You might give this a shot too:

   'Excel 8.0;Database=c:\Test.xls;','SELECT productid, price FROM dbo.product')

Lastly, you can look into using SSIS (replaced DTS) for data exports. Here is a link to a tutorial:

== Update #1 ==

To save the result as CSV file with column headers, one can follow the steps shown below:

  1. Go to Tools->Options
  2. Query Results->SQL Server->Results to Grid
  3. Check “Include column headers when copying or saving results”
  4. Click OK.
  5. Note that the new settings won’t affect any existing Query tabs — you’ll need to open new ones and/or restart SSMS.

How to Get a Specific Column Value from a DataTable?

I suggest such way based on extension methods:

IEnumerable<Int32> countryIDs =
    .Where(row => row.Field<String>("CountryName") == countryName)
    .Select(row => row.Field<Int32>("CountryID"));

System.Data.DataSetExtensions.dll needs to be referenced.

CodeIgniter - how to catch DB errors?

an example that worked for me:

$query = "some buggy sql statement";

$this->db->db_debug = false;

    $error = $this->db->error();
    // do something in error case
    // do something in success case


Image style height and width not taken in outlook mails

make the image the exact size needed in the email. Windows MSO has a hard time resizing images in different scenarios.

in the case of using a 1px by 1px transparent png or gif as a spacer, defining the dimensions via width, height, or style attributes will work as expected in the majority of clients, but not windows MSO (of course).

example use case - you are using a background image and need to position a with a link inside over some part of the background image. Using a 1px by 1px spacer gif/png will only expand so wide (about 30px). You need size the spacer to the exact dimensions.

Sublime Text 2 - Show file navigation in sidebar

Use Ctrl+0 to change focus to the sidebar.

JQuery Validate input file type

One the elements are added, use the rules method to add the rules

//bug fixed thanks to @Sparky
$('input[name^="fileupload"]').each(function () {
    $(this).rules('add', {
        required: true,
        accept: "image/jpeg, image/pjpeg"

Demo: Fiddle


var filenumber = 1;
$("#AddFile").click(function () { //User clicks button #AddFile
    var $li = $('<li><input type="file" name="FileUpload' + filenumber + '" id="FileUpload' + filenumber + '" required=""/> <a href="#" class="RemoveFileUpload">Remove</a></li>').prependTo("#FileUploader");

    $('#FileUpload' + filenumber).rules('add', {
        required: true,
        accept: "image/jpeg, image/pjpeg"

    return false;

Animate element transform rotate

As far as I know, basic animates can't animate non-numeric CSS properties.

I believe you could get this done using a step function and the appropriate css3 transform for the users browser. CSS3 transform is a bit tricky to cover all your browsers in (IE6 you need to use the Matrix filter, for instance).

EDIT: here's an example that works in webkit browsers (Chrome, Safari):

If you wanted to support IE9 only, you could use transform instead of -webkit-transform, or -moz-transform would support FireFox.

The trick used is to animate a CSS property we don't care about (text-indent) and then use its value in a step function to do the rotation:

step: function(now,fx) {

SQL Server GROUP BY datetime ignore hour minute and a select with a date and sum value

SELECT CAST(Datetimefield AS DATE) as DateField, SUM(intfield) as SumField
FROM MyTable
GROUP BY CAST(Datetimefield AS DATE)

How to get last key in an array?

$array = array(
    'something' => array(1,2,3),
    'somethingelse' => array(1,2,3,4)

$last_value = end($array);
$last_key = key($array); // 'somethingelse'

This works because PHP moves it's array pointer internally for $array

How to set background color of view transparent in React Native

Use rgba value for the backgroundColor.

For example,

backgroundColor: 'rgba(52, 52, 52, 0.8)'

This sets it to a grey color with 80% opacity, which is derived from the opacity decimal, 0.8. This value can be anything from 0.0 to 1.0.

My Routes are Returning a 404, How can I Fix Them?

On my Ubuntu LAMP installation, I solved this problem with the following 2 changes.

  1. Enable mod_rewrite on the apache server: sudo a2enmod rewrite.
  2. Edit /etc/apache2/apache2.conf, changing the "AllowOverride" directive for the /var/www directory (which is my main document root): AllowOverride All

Then restart the Apache server: service apache2 restart

Google Maps API: open url by clicking on marker

the previous answers didn't work out for me well. I had persisting problems by setting the marker. So i changed the code slightly.

   <!DOCTYPE html>
     <meta http-equiv="content-type" content="text/html; charset=ANSI" />
     <title>Google Maps Multiple Markers</title>
     <script src=""
     <div id="map" style="width: 1500px; height: 1000px;"></div>

     <script type="text/javascript">
       var locations = [
         ['Goettingen',  51.54128040000001,  9.915803500000038, ''],
         ['Kassel', 51.31271139999999,  9.479746100000057,0, ''],
         ['Witzenhausen', 51.33996819999999,  9.855564299999969,0, 'www.']


var map = new google.maps.Map(document.getElementById('map'), {
  zoom: 10,
 center: new google.maps.LatLng(51.54376, 9.910419999999931),
 mapTypeId: google.maps.MapTypeId.ROADMAP

var infowindow = new google.maps.InfoWindow();

var marker, i;

for (i = 0; i < locations.length; i++) {
  marker = new google.maps.Marker({
   position: new google.maps.LatLng(locations[i][1], locations[i][2]),
   map: map,
   url: locations[i][4]

 google.maps.event.addListener(marker, 'mouseover', (function(marker, i) {
   return function() {
     infowindow.setContent(locations[i][0]);, marker);
 })(marker, i));

      google.maps.event.addListener(marker, 'click', (function(marker, i) {
   return function() {
     infowindow.setContent(locations[i][0]);, marker);
     window.location.href = this.url;
 })(marker, i));



This way worked out for me! You can create Google Maps routing links from your Datebase to to use it as an interactive routing map.

Django CSRF Cookie Not Set

I have just met once, the solution is to empty the cookies. And may be changed while debugging SECRET_KEY related.

How to exit in Node.js

I was able to get all my node processes to die directly from the Git Bash shell on Windows 10 by typing taskkill -F -IM node.exe - this ends all the node processes on my computer at once. I found I could also use taskkill //F //IM node.exe. Not sure why both - and // work in this context. Hope this helps!

initialize a const array in a class initializer in C++

Where I've a constant array, it's always been done as static. If you can accept that, this code should compile and run.

#include <stdio.h>
#include <stdlib.h>

class a {
        static const int b[2];
        a(void) {
                for(int i = 0; i < 2; i++) {
                        printf("b[%d] = [%d]\n", i, b[i]);

const int a::b[2] = { 4, 2 };

int main(int argc, char **argv)
        a foo;
        return 0;

/usr/bin/ld: cannot find

@Alwin Doss You should provide the -L option before -l. You would have done the other way round probably. Try this :)

Replacing objects in array

Here a transparent approach, instead of an unreadable and undebuggable oneliner:

export class List {
    static replace = (object, list) => {
        let newList = [];
        list.forEach(function (item) {
            if ( === {
            } else {
        return newList;

How do I get my page title to have an icon?

The accepted answer works perfectly fine. I just want to mention a minor problem with the answer devXen has given.

If you set the icon like this:

<link rel="shortcut icon" type="image/x-icon" href="icon.ico">

The icon will work as expected:

enter image description here

However, if you set it like devXen has suggested:

<title> Amir A. Shabani</title>

The title of the page moves upon refresh:

enter image description here

So I would advise using <link> instead.

Is it possible to remove inline styles with jQuery?

.removeAttr("style") to just get rid of the whole style tag...

.attr("style") to test the value and see if an inline style exists...

.attr("style",newValue) to set it to something else

What does a bitwise shift (left or right) do and what is it used for?

Here is an example:


void main()
    int rm, vivek;
    printf("Enter any numbers\t(E.g., 1, 2, 5");
    scanf("%d", &rm); // rm = 5(0101) << 2 (two step add zero's), so the value is 10100
    printf("This left shift value%d=%d", rm, rm<<4);
    printf("This right shift value%d=%d", rm, rm>>2);

Android Studio AVD - Emulator: Process finished with exit code 1

None of the solutions worked for me. I ended up downloading a different emulator image.

First I had arm64-v8a, which was giving this error. I download armeabi-v7a, which worked fine.

Unfortunately I was not able to install HAXM accelerator as organization's softwares were blocking the installation. Hence, had to go with arm.

SQL Server - NOT IN

One issue could be that if either make, model, or [serial number] were null, values would never get returned. Because string concatenations with null values always result in null, and not in () with null will always return nothing. The remedy for this is to use an operator such as IsNull(make, '') + IsNull(Model, ''), etc.

How to Bulk Insert from XLSX file extension?

you can save the xlsx file as a tab-delimited text file and do

        FROM 'C:\SomeDirectory\my table.txt'
                FIELDTERMINATOR = '\t',
                ROWTERMINATOR = '\n'

How to advance to the next form input when the current input has a value?

Needed to emulate the tab functionality a while ago, and now I've released it as a library that uses .

EmulateTab: A jQuery plugin to emulate tabbing between elements on a page.

You can see how it works in the demo.

if (myTextHasBeenFilledWithText) {
  // Tab to the next input after #my-text-input

'gulp' is not recognized as an internal or external command

The best solution, you can manage the multiple node versions using nvm installer. then, install the required node's version using below command

nvm install version

Use below command as a working node with mentioned version alone

nvm use version

now, you can use any version node without uninstalling previous installed node.

How to insert a character in a string at a certain position?

int yourInteger = 123450;
String s = String.format("%6.2f", yourInteger / 100.0);

Can an Android App connect directly to an online mysql database

you can definitely make such application, you need to make http conection to the database, by calling a php script which will in response run specific queries according to your project, and generated the result in the form of xml, or json formate , whihc can be displayed on your android application!. for complete tutorial on how to connect android application to mysql i would recommend to check out this tutorila

What is the difference between up-casting and down-casting with respect to class variable

upcasting means casting the object to a supertype, while downcasting means casting to a subtype.

In java, upcasting is not necessary as it's done automatically. And it's usually referred as implicit casting. You can specify it to make it clear to others.

Thus, writing

Animal a = (Animal)d;


Animal a = d;

leads to exactly the same point and in both cases will be executed the callme() from Dog.

Downcasting is instead necessary because you defined a as object of Animal. Currently you know it's a Dog, but java has no guarantees it's. Actually at runtime it could be different and java will throw a ClassCastException, would that happen. Of course it's not the case of your very sample example. If you wouldn't cast a to Animal, java couldn't even compile the application because Animal doesn't have method callme2().

In your example you cannot reach the code of callme() of Animal from UseAnimlas (because Dog overwrite it) unless the method would be as follow:

class Dog extends Animal 
    public void callme()
        System.out.println("In callme of Dog");

Simulator or Emulator? What is the difference?

Some years ago I came up with a very short adage that, I believe, captures the essence of the difference quite nicely:

A simulator is an emulator on a mission.

By that I mean that you use an emulator when you can't use the real thing, and you use a simulator when you can't use the real thing and you want to find something out about it.

Simple way to measure cell execution time in ipython notebook

Use cell magic and this project on github by Phillip Cloud:

Load it by putting this at the top of your notebook or put it in your config file if you always want to load it by default:

%load_ext autotime

If loaded, every output of subsequent cell execution will include the time in min and sec it took to execute it.

Namenode not getting started

Add hadoop.tmp.dir property in core-site.xml


and format hdfs (hadoop 2.7.1):

$ hdfs namenode -format

The default value in core-default.xml is /tmp/hadoop-${}, which will be deleted after reboot.

High-precision clock in Python

You can also use time.clock() It counts the time used by the process on Unix and time since the first call to it on Windows. It's more precise than time.time().

It's the usually used function to measure performance.

Just call

import time
t_ = time.clock()
#Your code here
print 'Time in function', time.clock() - t_

EDITED: Ups, I miss the question as you want to know exactly the time, not the time spent...

enum - getting value of enum on string conversion

You are printing the enum object. Use the .value attribute if you wanted just to print that:


See the Programmatic access to enumeration members and their attributes section:

If you have an enum member and need its name or value:

>>> member =
>>> member.value

You could add a __str__ method to your enum, if all you wanted was to provide a custom string representation:

class D(Enum):
    def __str__(self):
        return str(self.value)

    x = 1
    y = 2


>>> from enum import Enum
>>> class D(Enum):
...     def __str__(self):
...         return str(self.value)
...     x = 1
...     y = 2
>>> D.x
<D.x: 1>
>>> print(D.x)

Detect network connection type on Android

You can make custom Method to accomplish this task.

  public String getNetworkClass(Context context) {
        TelephonyManager mTelephonyManager = (TelephonyManager)
        int networkType = mTelephonyManager.getNetworkType();
        switch (networkType) {
            case TelephonyManager.NETWORK_TYPE_GPRS:
            case TelephonyManager.NETWORK_TYPE_EDGE:
            case TelephonyManager.NETWORK_TYPE_CDMA:
            case TelephonyManager.NETWORK_TYPE_1xRTT:
            case TelephonyManager.NETWORK_TYPE_IDEN:
                return "2G";
            case TelephonyManager.NETWORK_TYPE_UMTS:
            case TelephonyManager.NETWORK_TYPE_EVDO_0:
            case TelephonyManager.NETWORK_TYPE_EVDO_A:
            case TelephonyManager.NETWORK_TYPE_HSDPA:
            case TelephonyManager.NETWORK_TYPE_HSUPA:
            case TelephonyManager.NETWORK_TYPE_HSPA:
            case TelephonyManager.NETWORK_TYPE_EVDO_B:
            case TelephonyManager.NETWORK_TYPE_EHRPD:
            case TelephonyManager.NETWORK_TYPE_HSPAP:
                return "3G";
            case TelephonyManager.NETWORK_TYPE_LTE:
                return "4G";
                return "Unknown";

RunAs A different user when debugging in Visual Studio

You can open your command prompt as the intended user:

  • Shift + Right Click on Command Prompt icon on task bar.
  • Select (Run as differnt user)

enter image description here

  • You will be prompted with login and password

  • Once CommandP Prompt starts you can double check which user you are running as by the command whoami.

  • Now you can change directory to your project and run

dotnet run

  • In Visual Studio hit Ctrl+Alt+P (Attach to Process - can also be found from Debug menu)

enter image description here

  • Make sure "Show Processes from All users" is checked.
  • Find the running process and attach debugger.

How to sort an array based on the length of each element?

#created a sorting function to sort by length of elements of list
def sort_len(a):
    num = len(a)
    d = {}
    i = 0
    while i<num:
        d[i] = len(a[i])
        i += 1
    b = list(d.values())
    c = []
    for i in b:
        for j in range(num):
            if j in list(d.keys()):
                if d[j] == i:
    return c

regex error - nothing to repeat

Beyond the bug that was discovered and fixed, I'll just note that the error message sre_constants.error: nothing to repeat is a bit confusing. I was trying to use r'?.*' as a pattern, and thought it was complaining for some strange reason about the *, but the problem is actually that ? is a way of saying "repeat zero or one times". So I needed to say r'\?.*'to match a literal ?

python save image from url

It is the simplest way to download and save the image from internet using urlib.request package.

Here, you can simply pass the image URL(from where you want to download and save the image) and directory(where you want to save the download image locally, and give the image name with .jpg or .png) Here I given "local-filename.jpg" replace with this.

Python 3

import urllib.request
imgURL = ""

urllib.request.urlretrieve(imgURL, "D:/abc/image/local-filename.jpg")

You can download multiple images as well if you have all the image URLs from the internet. Just pass those image URLs in for loop, and the code automatically download the images from the internet.

Extracting substrings in Go

WARNING: operating on strings alone will only work with ASCII and will count wrong when input is a non-ASCII UTF-8 encoded character, and will probably even corrupt characters since it cuts multibyte chars mid-sequence.

Here's a UTF-8-aware version:

// NOTE: this isn't multi-Unicode-codepoint aware, like specifying skintone or
//       gender of an emoji:
func substr(input string, start int, length int) string {
    asRunes := []rune(input)
    if start >= len(asRunes) {
        return ""
    if start+length > len(asRunes) {
        length = len(asRunes) - start
    return string(asRunes[start : start+length])

ASP.Net MVC - Read File from HttpPostedFileBase without save

A slight change to Thangamani Palanisamy answer, which allows the Binary reader to be disposed and corrects the input length issue in his comments.

string result = string.Empty;

using (BinaryReader b = new BinaryReader(file.InputStream))
  byte[] binData = b.ReadBytes(file.ContentLength);
  result = System.Text.Encoding.UTF8.GetString(binData);

How to implement a binary search tree in Python?

A simple, recursive method with only 1 function and using an array of values:

class TreeNode(object):

    def __init__(self, value: int, left=None, right=None):
        self.value = value
        self.left = left
        self.right = right

    def __str__(self):
        return str(self.value)

def create_node(values, lower, upper) -> TreeNode:
    if lower > upper:
        return None

    index = (lower + upper) // 2

    value = values[index]
    node = TreeNode(value=value)
    node.left = create_node(values, lower, index - 1)
    node.right = create_node(values, index + 1, upper)

    return node

def print_bst(node: TreeNode):
    if node:
        # Simple pre-order traversal when printing the tree
        print("node: {}".format(node))

if __name__ == '__main__':
    vals = [0, 1, 2, 3, 4, 5, 6]
    bst = create_node(vals, lower=0, upper=len(vals) - 1)

As you can see, we really only need 1 method, which is recursive: create_node. We pass in the full values array in each create_node method call, however, we update the lower and upper index values every time that we make the recursive call.

Then, using the lower and upper index values, we calculate the index value of the current node and capture it in value. This value is the value for the current node, which we use to create a node.

From there, we set the values of left and right by recursively calling the function, until we reach the end state of the recursion call when lower is greater than upper.

Important: we update the value of upper when creating the left side of the tree. Conversely, we update the value of lower when creating the right side of the tree.

Hopefully this helps!

How to format code in Xcode?

Key combination to format all text on open file:

Cmd ? A + Ctrl I

Concatenating bits in VHDL

Here is an example of concatenation operator:

architecture EXAMPLE of CONCATENATION is
   signal Z_BUS : bit_vector (3 downto 0);
   signal A_BIT, B_BIT, C_BIT, D_BIT : bit;
   Z_BUS <= A_BIT & B_BIT & C_BIT & D_BIT;

Must declare the scalar variable

Declare @v1 varchar(max), @v2 varchar(200);

Declare @sql nvarchar(max);

Set @sql = N'SELECT @v1 = value1, @v2 = value2
FROM dbo.TblTest -- always use schema
WHERE ID = 61;';

EXEC sp_executesql @sql,
  N'@v1 varchar(max) output, @v2 varchar(200) output',
  @v1 output, @v2 output;

You should also pass your input, like wherever 61 comes from, as proper parameters (but you won't be able to pass table and column names that way).

Background position, margin-top?

If you mean you want the background image itself to be offset by 50 pixels from the top, like a background margin, then just switch out the top for 50px and you're set.

#thedivstatus {
    background-image: url("imagestatus.gif");
    background-position: right 50px;
    background-repeat: no-repeat;

Centering a background image, using CSS

The only thing that worked for me is..

margin: 0 auto

PHP MySQL Google Chart JSON - Complete Example

Some might encounter this error (I got it while implementing PHP-MySQLi-JSON-Google Chart Example):

You called the draw() method with the wrong type of data rather than a DataTable or DataView.

The solution would be: replace jsapi and just use loader.js with:

google.charts.load('current', {packages: ['corechart']}) and 

-- according to the release notes --> The version of Google Charts that remains available via the jsapi loader is no longer being updated consistently. Please use the new gstatic loader from now on.

Create Git branch with current changes

Since you haven't made any commits yet, you can save all your changes to the stash, create and switch to a new branch, then pop those changes back into your working tree:

git stash  # save local modifications to new stash
git checkout -b topic/newbranch
git stash pop  # apply stash and remove it from the stash list

"No cached version... available for offline mode."

Just happened to me after upgrading to Android Studio 3.1. The Offline Work checkbox was unchecked, so no luck there.

I went to Settings > Build, Execution, Deployment > Compiler and the Command-line Options textfield contained --offline, so I just deleted that and everything worked.

setting screenshot

How to show SVG file on React Native?

you can do this using a simple way

first, you should take installation,

  1. npm install -s react-native-svg
  2. react-native link react-native-svg
  3. npm install -s react-native-svg-transformer

then, you should add the following code in your metro.config.js file

const { getDefaultConfig } = require("metro-config");
module.exports = (async () => {
  const {
    resolver: { sourceExts, assetExts }
  } = await getDefaultConfig();
  return {
    transformer: {
      babelTransformerPath: require.resolve("react-native-svg-transformer")
    resolver: {
      assetExts: assetExts.filter(ext => ext !== "svg"),
      sourceExts: [...sourceExts, "svg"]

after that, you should create a new file in your root directory with the name of declarations.d.js with the following code

declare module "*.svg" {
  import { SvgProps } from "react-native-svg";
  const content: React.FC<SvgProps>;
  export default content;

Finally, This is a import mathod

import USER from "../../assets/icons/user.svg"

and, this is for jsx

<USER width="100%" height="100%"/>

Why Visual Studio 2015 can't run exe file (ucrtbased.dll)?

rdtsc solution did not work for me.

Firstly, I use Visual Studio 2015 Express, for which installer "modify" query does not propose any "Common Tools for Visual C++ 2015" option you could uncheck.

Secondly, even after 2 uninstall/reinstall (many hours waiting for them to complete...), the problem still remains.

I finally fixed the issue by reinstalling the whole Windows SDK from a standalone installer (independently from Visual C++ 2015 install): or

This fixed the issue for me.

DateTime "null" value

I always set the time to DateTime.MinValue. This way I do not get any NullErrorException and I can compare it to a date that I know isn't set.

PHP: convert spaces in string into %20?

The plus sign is the historic encoding for a space character in URL parameters, as documented in the help for the urlencode() function.

That same page contains the answer you need - use rawurlencode() instead to get RFC 3986 compatible encoding.

Import CSV file as a pandas DataFrame

import pandas as pd
dataset = pd.read_csv('/home/nspython/Downloads/movie_metadata1.csv')

How to solve npm error "npm ERR! code ELIFECYCLE"

Try to reinstall the cli package globally. In my case, I was trying to test a Vue.js tutorial when I get the same error message. The other thing I did was run the vue command again but this time using webpack-simple and that is why I am not sure wich one solved the problem but now it is working.

less than 10 add 0 to number

Here is Genaric function for add any number of leading zeros for making any size of numeric string.

function add_zero(your_number, length) {
    var num = '' + your_number;
    while (num.length < length) {
        num = '0' + num;
    return num;