Programs & Examples On #Quicksort

Quicksort is a sorting algorithm invented by C. A. R. Hoare that has an average-case complexity of O(n log n) and worst-case quadratic complexity. It is one of the fastest general-purpose sorting algorithms.

Quicksort with Python

There are many answers to this already, but I think this approach is the most clean implementation:

def quicksort(arr):
    """ Quicksort a list

    :type arr: list
    :param arr: List to sort
    :returns: list -- Sorted list
    if not arr:
        return []

    pivots = [x for x in arr if x == arr[0]]
    lesser = quicksort([x for x in arr if x < arr[0]])
    greater = quicksort([x for x in arr if x > arr[0]])

    return lesser + pivots + greater

You can of course skip storing everything in variables and return them straight away like this:

def quicksort(arr):
    """ Quicksort a list

    :type arr: list
    :param arr: List to sort
    :returns: list -- Sorted list
    if not arr:
        return []

    return quicksort([x for x in arr if x < arr[0]]) \
        + [x for x in arr if x == arr[0]] \
        + quicksort([x for x in arr if x > arr[0]])

Why is quicksort better than mergesort?

In merge-sort, the general algorithm is:

  1. Sort the left sub-array
  2. Sort the right sub-array
  3. Merge the 2 sorted sub-arrays

At the top level, merging the 2 sorted sub-arrays involves dealing with N elements.

One level below that, each iteration of step 3 involves dealing with N/2 elements, but you have to repeat this process twice. So you're still dealing with 2 * N/2 == N elements.

One level below that, you're merging 4 * N/4 == N elements, and so on. Every depth in the recursive stack involves merging the same number of elements, across all calls for that depth.

Consider the quick-sort algorithm instead:

  1. Pick a pivot point
  2. Place the pivot point at the correct place in the array, with all smaller elements to the left, and larger elements to the right
  3. Sort the left-subarray
  4. Sort the right-subarray

At the top level, you're dealing with an array of size N. You then pick one pivot point, put it in its correct position, and can then ignore it completely for the rest of the algorithm.

One level below that, you're dealing with 2 sub-arrays that have a combined size of N-1 (ie, subtract the earlier pivot point). You pick a pivot point for each sub-array, which comes up to 2 additional pivot points.

One level below that, you're dealing with 4 sub-arrays with combined size N-3, for the same reasons as above.

Then N-7... Then N-15... Then N-32...

The depth of your recursive stack remains approximately the same (logN). With merge-sort, you're always dealing with a N-element merge, across each level of the recursive stack. With quick-sort though, the number of elements that you're dealing with diminishes as you go down the stack. For example, if you look at the depth midway through the recursive stack, the number of elements you're dealing with is N - 2^((logN)/2)) == N - sqrt(N).

Disclaimer: On merge-sort, because you divide the array into 2 exactly equal chunks each time, the recursive depth is exactly logN. On quick-sort, because your pivot point is unlikely to be exactly in the middle of the array, the depth of your recursive stack may be slightly greater than logN. I haven't done the math to see how big a role this factor and the factor described above, actually play in the algorithm's complexity.

Quicksort: Choosing the pivot

Heh, I just taught this class.

There are several options.
Simple: Pick the first or last element of the range. (bad on partially sorted input) Better: Pick the item in the middle of the range. (better on partially sorted input)

However, picking any arbitrary element runs the risk of poorly partitioning the array of size n into two arrays of size 1 and n-1. If you do that often enough, your quicksort runs the risk of becoming O(n^2).

One improvement I've seen is pick median(first, last, mid); In the worst case, it can still go to O(n^2), but probabilistically, this is a rare case.

For most data, picking the first or last is sufficient. But, if you find that you're running into worst case scenarios often (partially sorted input), the first option would be to pick the central value( Which is a statistically good pivot for partially sorted data).

If you're still running into problems, then go the median route.

Convert Existing Eclipse Project to Maven Project

Chengdong's answer is correct, you should use Configure>Convert to Maven Project. However, I must add the conversion process has been greatly improved since m2e 0.13.0 : m2e 1.1+ and m2e-wtp 0.16.0+ can now convert the existing eclipse settings into maven plugin configuration .

As for the dependency conversion matter, you can try the JBoss Tools (JBT) 4.0 Maven integration feature, which contains an experimental conversion wizard, plugged into m2e's conversion process :

It does not pretend to be the ultimate solution (nothing can), be it should greatly help bootstrap your Maven conversion process.

Also, FYI, here are some ideas to enhance m2e's conversion process, refactoring to use a Maven layout will most probably be implemented in the future.

JBT 4.0 (requires Eclipse JavaEE Juno) can be installed from or from the Eclipse Marketplace

How to include() all PHP files from a directory?

//Loading all php files into of functions/ folder 

$folder =   "./functions/"; 
$files = glob($folder."*.php"); // return array files

 foreach($files as $phpFile){   

How to make responsive table

Pure css way to make a table fully responsive, no JavaScript is needed. Checke demo here Responsive Tables

  <title>Responsive Table</title>
  /* only for demo purpose. you can remove it */
 .container{border: 1px solid #ccc; background-color: #ff0000; 
  margin: 10px auto;width: 98%; height:auto;padding:5px; text-align: center;}

 /* required */
.tablewrapper{width: 95%; overflow-y: hidden; overflow-x: auto; 
 background-color:green;  height: auto; padding: 5px;}

 /* only for demo purpose just for stlying. you can remove it */
 table { font-family: arial; font-size: 13px; padding: 2px 3px}
 table.responsive{ background-color:#1a99e6; border-collapse: collapse; 
 border-color: #fff}

tr:nth-child(1) td:nth-of-type(1){
 background:#333; color: #fff}
 tr:nth-child(1) td{
 background:#333; color: #fff; font-weight: bold;}
 table tr td:nth-child(2) {
 tr:nth-child(1) td:nth-of-type(2){color: #333}
 tr:nth-child(odd){ background:#ccc;}

<div class="container">
<div class="tablewrapper">
<table  class="responsive" width="98%" cellpadding="4" cellspacing="1" border="1">
 <td>Nick Name</td> 
<td>RN Kushwaha</td>
<td>[email protected]</td>

Angular2 RC6: '<component> is not a known element'

I was facing this issue on Angular 7 and the problem was after creating the module, I did not perform ng build. So I performed -

  • ng build
  • ng serve

and it worked.

Rounding SQL DateTime to midnight

Try using this.

WHERE Orders.OrderStatus = 'Shipped'  

How to clear input buffer in C?

You can do it (also) this way:


What is the difference between supervised learning and unsupervised learning?

Supervised learning

You have input x and a target output t. So you train the algorithm to generalize to the missing parts. It is supervised because the target is given. You are the supervisor telling the algorithm: For the example x, you should output t!

Unsupervised learning

Although segmentation, clustering and compression are usually counted in this direction, I have a hard time to come up with a good definition for it.

Let's take auto-encoders for compression as an example. While you only have the input x given, it is the human engineer how tells the algorithm that the target is also x. So in some sense, this is not different from supervised learning.

And for clustering and segmentation, I'm not too sure if it really fits the definition of machine learning (see other question).

How to create a database from shell command?

You mean while the mysql environment?

create database testdb;

Or directly from command line:

mysql -u root -e "create database testdb"; 

Add Favicon to Website

Simply put a file named favicon.ico in the webroot.

If you want to know more, please start reading:

What's the Android ADB shell "dumpsys" tool and what are its benefits?

According to official Android information about dumpsys:

The dumpsys tool runs on the device and provides information about the status of system services.

To get a list of available services use

adb shell dumpsys -l

Cannot assign requested address - possible causes?

sysctl -w net.ipv4.tcp_timestamps=1
sysctl -w net.ipv4.tcp_tw_recycle=1

How can I convert string date to NSDate?

To add String within Date Format in Swift, I did this

 var dataFormatter:NSDateFormatter = NSDateFormatter()
                dataFormatter.dateFormat = "dd-MMMM 'at' HH:mm a"

cell.timeStamplbl.text = dataFormatter.stringFromDate(object.createdAt)

CSS Resize/Zoom-In effect on Image while keeping Dimensions

You could achieve that simply by wrapping the image by a <div> and adding overflow: hidden to that element:

<div class="img-wrapper">
    <img src="..." />
.img-wrapper {
    display: inline-block; /* change the default display type to inline-block */
    overflow: hidden;      /* hide the overflow */


Also it's worth noting that <img> element (like the other inline elements) sits on its baseline by default. And there would be a 4~5px gap at the bottom of the image.

That vertical gap belongs to the reserved space of descenders like: g j p q y. You could fix the alignment issue by adding vertical-align property to the image with a value other than baseline.

Additionally for a better user experience, you could add transition to the images.

Thus we'll end up with the following:

.img-wrapper img {
    transition: all .2s ease;
    vertical-align: middle;


HTML-Tooltip position relative to mouse pointer

We can achieve the same using "Directive" in Angularjs.

            //Bind mousemove event to the element which will show tooltip
            $("#tooltip").mousemove(function(e) {
                //find X & Y coodrinates
                x = e.clientX,
                y = e.clientY;

                //Set tooltip position according to mouse position
       = (y + 20) + 'px';
       = (x + 20) + 'px';

You can check this post for further details.

Sequelize OR condition object

Use Sequelize.or:

var condition = {
  where: Sequelize.and(
    { name: 'a project' },
      { id: [1,2,3] },
      { id: { lt: 10 } }

Reference (search for Sequelize.or)

Edit: Also, this has been modified and for the latest method see Morio's answer,

How should I tackle --secure-file-priv in MySQL?

I had all sorts of problems with this. I was changing my.cnf and all sorts of crazy things that other versions of this problem tried to show.

What worked for me:

The error I was getting

The MySQL server is running with the --secure-file-priv option so it cannot execute this statement

I was able to fix it by opening /usr/local/mysql/support-files/mysql.server and changing the following line:

$bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" -- $other_args >/dev/null &
  wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?


$bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" --secure-file-priv="" $other_args >/dev/null &
  wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?

ggplot2: sorting a plot

You need to make the x-factor into an ordered factor with the ordering you want, e.g

x <- data.frame("variable"=letters[1:5], "value"=rnorm(5)) ## example data
x <- x[with(x,order(-value)), ] ## Sorting
x$variable <- ordered(x$variable, levels=levels(x$variable)[unclass(x$variable)])

ggplot(x, aes(x=variable,y=value)) + geom_bar() +
   scale_y_continuous("",formatter="percent") + coord_flip()

I don't know any better way to do the ordering operation. What I have there will only work if there are no duplicate levels for x$variable.

Access to build environment variables from a groovy script in a Jenkins build step (Windows)

The Scriptler Groovy script doesn't seem to get all the environment variables of the build. But what you can do is force them in as parameters to the script:

  1. When you add the Scriptler build step into your job, select the option "Define script parameters"

  2. Add a parameter for each environment variable you want to pass in. For example "Name: JOB_NAME", "Value: $JOB_NAME". The value will get expanded from the Jenkins build environment using '$envName' type variables, most fields in the job configuration settings support this sort of expansion from my experience.

  3. In your script, you should have a variable with the same name as the parameter, so you can access the parameters with something like:

    println "JOB_NAME = $JOB_NAME"

I haven't used Sciptler myself apart from some experimentation, but your question posed an interesting problem. I hope this helps!

Creating custom function in React component

You can try this.

// Author: Hannad Rehman Sat Jun 03 2017 12:59:09 GMT+0530 (India Standard Time)

import React from 'react';
import RippleButton from '../../Components/RippleButton/rippleButton.jsx';

class HtmlComponents extends React.Component {


        //do stuff. 
        // foo==bar

    render() {
      return (
             <h1>React Components</h1>
             <RippleButton onClick={this.rippleClickFunction}/>

export default HtmlComponents;

Yhe only concern is you have to bind the context to the function

How to lookup JNDI resources on WebLogic?

java is the root JNDI namespace for resources. What the original snippet of code means is that the container the application was initially deployed in did not apply any additional namespaces to the JNDI context you retrieved (as an example, Tomcat automatically adds all resources to the namespace comp/env, so you would have to do dataSource = (javax.sql.DataSource) context.lookup("java:comp/env/jdbc/myDataSource"); if the resource reference name is jdbc/myDataSource).

To avoid having to change your legacy code I think if you register the datasource with the name myDataSource (remove the jdbc/) you should be fine. Let me know if that works.

How to import a csv file using python with headers intact, where first column is a non-numerical

For Python 3

Remove the rb argument and use either r or don't pass argument (default read mode).

with open( <path-to-file>, 'r' ) as theFile:
    reader = csv.DictReader(theFile)
    for line in reader:
        # line is { 'workers': 'w0', 'constant': 7.334, 'age': -1.406, ... }
        # e.g. print( line[ 'workers' ] ) yields 'w0'

For Python 2

import csv
with open( <path-to-file>, "rb" ) as theFile:
    reader = csv.DictReader( theFile )
    for line in reader:
        # line is { 'workers': 'w0', 'constant': 7.334, 'age': -1.406, ... }
        # e.g. print( line[ 'workers' ] ) yields 'w0'

Python has a powerful built-in CSV handler. In fact, most things are already built in to the standard library.

How do I trim a file extension from a String in Java?

Use a method in class if your project is already dependent on Google core library. The method you need is getNameWithoutExtension.

How to declare and add items to an array in Python?

I believe you are all wrong. you need to do:

array = array[] in order to define it, and then:

array.append ["hello"] to add to it.

How to write a shell script that runs some commands as superuser and some commands not as superuser, without having to babysit it?

If you use this, check man sudo too:


sudo echo "Hi, I'm root"

sudo -u nobody echo "I'm nobody"

sudo -u 1000 touch /test_user

Facebook user url by id

The marked answer seems outdated and it won't work.

Facebook now only gives unique ID related to app which isn't equal to userId and profileUrl and username will come out to be empty.

Doing me?fields=id,name,links is also depreciated after Graph Version 2.4

The only option now is to request for user_links permission from your developer console.

enter image description here

and the pass it in scope when doing facebook login

scope: ['user_link'] }

or by doing an api call

When and why to 'return false' in JavaScript?

return false using only if you have some worng in function (by some test) or you want to stop some function, example use return false in end "onsubmit"

Detecting locked tables (locked by LOCK TABLE)

The following answer was written by Eric Leschinki in 2014/15 at (now deleted):

Mini walkthrough on how to detect locked tables:

This may prevent the database from enforcing atomicity in the affected tables and rows. The locks were designed to make sure things stay consistent and this procedure will prevent that process from taking place as designed.

Create your table, insert some rows

create table penguins(spam int, ham int);
insert into penguins(spam, ham) values (3, 4);

show open tables:

show open tables like "penguins"


your_database penguins    0   0

Penguins isn't locked, lets lock it:


Check if it's locked:

show open tables like "penguins"


your_database, penguins 1, 0

Aha! It is locked! Lets unlock it:

unlock tables

Now it is unlocked:

show open tables like "penguins"


your_database penguins    0   0

show all current locks

show open tables where in_use <> 0

It would be much more helpful if the MySQL developers put this information in a regular table (so I can do a select my_items from my_table where my_clauses), rather than this stripped down 'show table' syntax from system variables.

Python: Total sum of a list of numbers with the for loop

l = [1,2,3,4,5]
sum = 0
for x in l:
    sum = sum + x

And you can change l for any list you want.

Select DISTINCT individual columns in django?

It's quite simple actually if you're using PostgreSQL, just use distinct(columns) (documentation).


Note that this feature has been included in Django since 1.4

How to make child element higher z-index than parent?

Try using this code, it worked for me:

z-index: unset;

Add 2 hours to current time in MySQL?

FROM courses 

See Date and Time Functions for other date/time manipulation.

How do relative file paths work in Eclipse?

Yeah, eclipse sees the top directory as the working/root directory, for the purposes of paths.

...just thought I'd add some extra info. I'm new here! I'd like to help.

SQL Server Group by Count of DateTime Per Hour?

Alternatively, just GROUP BY the hour and day:

SELECT  CAST(Startdate as DATE) as 'StartDate', 
        CAST(DATEPART(Hour, StartDate) as varchar) + ':00' as 'Hour', 
        COUNT(*) as 'Ct'
FROM #Events
GROUP BY CAST(Startdate as DATE), DATEPART(Hour, StartDate)


StartDate   Hour    Ct
2007-01-01  0:00    3
2007-01-02  5:00    2
2007-01-03  4:00    1
2007-01-07  3:00    1

How to check if the URL contains a given string?

Suppose you have this script

  <p id="response"><p>
    var query = document.location.href.substring(document.location.href.indexOf("?") + 1);
    var text_input = query.split("&")[0].split("=")[1];
  </script> </div>

And the url form is

The text written to <p id="response"> will be stack

Remove plot axis values

Remove numbering on x-axis or y-axis:

plot(1:10, xaxt='n')
plot(1:10, yaxt='n')

If you want to remove the labels as well:

plot(1:10, xaxt='n', ann=FALSE)
plot(1:10, yaxt='n', ann=FALSE)

Difference between JOIN and INNER JOIN


INNER JOIN is the default if you don't specify the type when you use the word JOIN.

You can also use LEFT OUTER JOIN or RIGHT OUTER JOIN, in which case the word OUTER is optional, or you can specify CROSS JOIN.


For an inner join, the syntax is:


(in other words, the "INNER" keyword is optional - results are the same with or without it)

Allowed memory size of X bytes exhausted

I had same issue. I found the answer:

ini_set('memory_limit', '-1');

Note: It will take unlimited memory usage of server.

Update: Use this carefully as this might slow down your system if the PHP script starts using an excessive amount of memory, causing a lot of swap space usage. You can use this if you know program will not take much memory and also you don't know how much to set it right now. But you will eventually find it how much memory you require for that program.

You should always memory limit as some value as answered by @sarki dinle.

ini_set('memory_limit', '512M');

Giving unlimited memory is bad practice, rather we should give some max limit that we can bear and then optimise our code or add some RAMs.

Send multipart/form-data files with angular using $http

Here's an updated answer for Angular 4 & 5. TransformRequest and angular.identity were dropped. I've also included the ability to combine files with JSON data in one request.

Angular 5 Solution:

import {HttpClient} from '@angular/common/http';

uploadFileToUrl(files, restObj, uploadUrl): Promise<any> {
  // Note that setting a content-type header
  // for mutlipart forms breaks some built in
  // request parsers like multer in express.
  const options = {} as any; // Set any options you like
  const formData = new FormData();

  // Append files to the virtual form.
  for (const file of files) {
    formData.append(, file)

  // Optional, append other kev:val rest data to the form.
  Object.keys(restObj).forEach(key => {
    formData.append(key, restObj[key]);

  // Send it.
  return, formData, options)
    .catch((e) => {
      // handle me

Angular 4 Solution:

// Note that these imports below are deprecated in Angular 5
import {Http, RequestOptions} from '@angular/http';

uploadFileToUrl(files, restObj, uploadUrl): Promise<any> {
  // Note that setting a content-type header
  // for mutlipart forms breaks some built in
  // request parsers like multer in express.
  const options = new RequestOptions();
  const formData = new FormData();

  // Append files to the virtual form.
  for (const file of files) {
    formData.append(, file)

  // Optional, append other kev:val rest data to the form.
  Object.keys(restObj).forEach(key => {
    formData.append(key, restObj[key]);

  // Send it.
  return, formData, options)
    .catch((e) => {
      // handle me

Extension methods must be defined in a non-generic static class

Try changing

public class LinqHelper


 public static class LinqHelper

How to filter JSON Data in JavaScript or jQuery?

It iterates through the json objects, and searches each value you are concerned about, 'website', and if it equals "yahoo" you can then return that value or do whatever you like there. Right now it just logs that element to the console.

jsonObj.forEach(function (element, index) {
    if(element['website'] === 'yahoo'){
        console.log('found', element)   

Conversion failed when converting the nvarchar value ... to data type int

I use the latest version of SSMS or sql server management studio. I have a SQL script (in query editor) which has about 100 lines of code. This is error I got in the query:

Msg 245, Level 16, State 1, Line 2
Conversion failed when converting the nvarchar value 'abcd' to data type int.

Solution - I had seen this kind of error before when I forgot to enclose a number (in varchar column) in single quotes.

As an aside, the error message is misleading. The actual error on line number 70 in the query editor and not line 2 as the error says!

How to hide keyboard in swift on pressing return key?

Here's the Swift 3.0 update to peacetype's comment:

textField.addTarget(nil, action:Selector(("firstResponderAction:")), for:.editingDidEndOnExit)

Delete from two tables in one query

DELETE a.*, b.* 
FROM messages a 
LEFT JOIN usersmessages b 
ON b.messageid = a.messageid 
WHERE a.messageid = 1

translation: delete from table messages where messageid =1, if table uersmessages has messageid = messageid of table messages, delete that row of uersmessages table.

Creating a UICollectionView programmatically

swift 4 code

//  ViewController.swift
//  coolectionView

import UIKit

class ViewController: UIViewController , UICollectionViewDataSource, UICollectionViewDelegate,UICollectionViewDelegateFlowLayout{
    @IBOutlet weak var collectionView: UICollectionView!

    var items = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48"]

    override func viewDidLoad() {
        // Do any additional setup after loading the view, typically from a nib.

    override func didReceiveMemoryWarning() {
        // Dispose of any resources that can be recreated.

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return self.items.count
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
        if indexPath.row % 3 != 0
        return CGSize(width:collectionView.frame.width/2 - 7.5 , height: 100)
            return CGSize(width:collectionView.frame.width - 10 , height: 100 )

    // make a cell for each cell index path
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        // get a reference to our storyboard cell
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell1234", for: indexPath as IndexPath) as! CollectionViewCell1234

        // Use the outlet in our custom class to get a reference to the UILabel in the cell
        cell.lbl1.text = self.items[indexPath.item]
        cell.backgroundColor = UIColor.cyan // make cell more visible in our example project
        cell.layer.borderColor =
        cell.layer.borderWidth = 1
        cell.layer.cornerRadius = 8

        return cell
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        // handle tap events
        print("You selected cell #\(indexPath.item)!")


Show compose SMS view in Android

Some of what is explained above is meant only for placing an SMS in a 'ready to launch' state. as Senthil Mg said you can use sms manager to send the sms directly but SMSManager has been moved to android.telephony.SmsManager

I know it's not a lot of more info, but it might help someone some day.

Postgresql GROUP_CONCAT equivalent?

Try like this:

select field1, array_to_string(array_agg(field2), ',')
from table1
group by field1;

SQL Server check case-sensitivity?

SQL server determines case sensitivity by COLLATION.

COLLATION can be set at various levels.

  1. Server-level
  2. Database-level
  3. Column-level
  4. Expression-level

Here is the MSDN reference.

One can check the COLLATION at each level as mentioned in Raj More's answer.

Check Server Collation


Check Database Collation

SELECT DATABASEPROPERTYEX('AdventureWorks', 'Collation') SQLCollation;

Check Column Collation

select table_name, column_name, collation_name
where table_name = @table_name

Check Expression Collation

For expression level COLLATION you need to look at the expression. :)

It would be generally at the end of the expression as in below example.

SELECT name FROM customer ORDER BY name COLLATE Latin1_General_CS_AI;

Collation Description

For getting description of each COLLATION value try this.

SELECT * FROM fn_helpcollations()

And you should see something like this.

enter image description here

You can always put a WHERE clause to filter and see description only for your COLLATION.

You can find a list of collations here.

Bootstrap: align input with button

Twitter Bootstrap 4

In Twitter Bootstrap 4, inputs and buttons can be aligned using the input-group-prepend and input-group-append classes (see

Group button on the left side (prepend)

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button class="btn btn-outline-secondary" type="button">Button</button>
  <input type="text" class="form-control">

Group button on the right side (append)

<div class="input-group mb-3">
  <div class="input-group-append">
    <button class="btn btn-outline-secondary" type="button">Button</button>
  <input type="text" class="form-control">

Twitter Bootstrap 3

As shown in the answer by @abimelex, inputs and buttons can be aligned by using the .input-group classes (see

Group button on the left side

<div class="input-group">
  <span class="input-group-btn">
    <button class="btn btn-default" type="button">Go!</button>
  <input type="text" class="form-control">

Group button on the right side

<div class="input-group">
   <input type="text" class="form-control">
   <span class="input-group-btn">
        <button class="btn btn-default" type="button">Go!</button>

This solution has been added to keep my answer up to date, but please stick your up-vote on the answer provided by @abimelex.

Twitter Bootstrap 2

Bootstrap offers an .input-append class, which works as a wrapper element and corrects this for you:

<div class="input-append">
    <input name="search" id="search"/>
    <button class="btn">button</button>

As pointed out by @OleksiyKhilkevich in his answer, there is a second way to align input and button by using the .form-horizontal class:

<div class="form-horizontal">
    <input name="search" id="search"/>
    <button class="btn">button</button>

The Differences

The difference between these two classes is that .input-append will place the button up against the input element (so they look like they are attached), where .form-horizontal will place a space between them.

-- Note --

To allow the input and button elements to be next to each other without spacing, the font-size has been set to 0 in the .input-append class (this removes the white spacing between the inline-block elements). This may have an adverse effect on font-sizes in the input element if you want to override the defaults using em or % measurements.

Splitting applicationContext to multiple files

@eljenso : intrafest-servlet.xml webapplication context xml will be used if the application uses SPRING WEB MVC.

Otherwise the @kosoant configuration is fine.

Simple example if you dont use SPRING WEB MVC, but want to utitlize SPRING IOC :

In web.xml:


Then, your application-context.xml will contain: <import resource="foo-services.xml"/> these import statements to load various application context files and put into main application-context.xml.

Thanks and hope this helps.

Error when testing on iOS simulator: Couldn't register with the bootstrap server

I'm having this problem very often recently. What would prevent this from occurring? Logging out and in fixes the problem but.. it's annoying to do so every so often.


I just found the cause. I had a bug in ApplicationWillTerminate method. So when i click stop button on Xcode window, app couldn't properly terminate and started to hang.

check Activity Monitor to see if your app is on the list. force quit if possible.

Image resizing in React Native

I adjust your answer a bit (shixukai)

image: {
    flex: 1,
    width: 50,
    height: 50,
    resizeMode: 'contain' }

When I set to null, the image wont show at all. I set to certain size like 50

Create a new txt file using VB.NET

You can try writing into the Documents folder. Here is a "debug" function I did for the debugging needs of my project:

Private Sub writeDebug(ByVal x As String)
    Dim path As String = System.Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
    Dim FILE_NAME As String = path & "\mydebug.txt"
    If System.IO.File.Exists(FILE_NAME) = False Then
    End If
    Dim objWriter As New System.IO.StreamWriter(FILE_NAME, True)
End Sub

There are more standard folders you can access through the "SpecialFolder" object.

TimeSpan to DateTime conversion

If you only need to show time value in a datagrid or label similar, best way is convert directly time in datetime datatype.

SELECT CONVERT(datetime,myTimeField) as myTimeField FROM Table1

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

.getCellType() != Cell.CELL_TYPE_BLANK

Basic Authentication Using JavaScript

Today we use Bearer token more often that Basic Authentication but if you want to have Basic Authentication first to get Bearer token then there is a couple ways:

const request = new XMLHttpRequest();'GET', url, false, username,password)
request.onreadystatechange = function() {
        // D some business logics here if you receive return
   if(request.readyState === 4 && request.status === 200) {

Full syntax is here

Second Approach using Ajax:

  type: "GET",
  url: "",
  dataType: 'json',
  async: false,
  username: "username",
  password: "password",
  data: '{ "key":"sample" }',
  success: function (){
    alert('Thanks for your up vote!');

Hopefully, this provides you a hint where to start API calls with JS. In Frameworks like Angular, React, etc there are more powerful ways to make API call with Basic Authentication or Oauth Authentication. Just explore it.

Visual Studio breakpoints not being hit

In my case I had a string of length 70kb. Compiler did not thrown any error. But Debugger failed to hit the break point. After spending 3 hours and scratching my hair I found the cause for not hitting the break point. After removing 70kb data break point worked as normal.

How to check if a map contains a key in Go?

better way here

if _, ok := dict["foo"]; ok {
    //do something here

How do I use floating-point division in bash?

There are scenarios in wich you cannot use bc becouse it might simply not be present, like in some cut down versions of busybox or embedded systems. In any case limiting outer dependencies is always a good thing to do so you can always add zeroes to the number being divided by (numerator), that is the same as multiplying by a power of 10 (you should choose a power of 10 according to the precision you need), that will make the division output an integer number. Once you have that integer treat it as a string and position the decimal point (moving it from right to left) a number of times equal to the power of ten you multiplied the numerator by. This is a simple way of obtaining float results by using only integer numbers.

Saving changes after table edit in SQL Server Management Studio

Rather than unchecking the box (a poor solution), you should STOP editing data that way. If data must be changed, then do it with a script, so that you can easily port it to production and so that it is under source control. This also makes it easier to refresh testing changes after production has been pushed down to dev to enable developers to be working against fresher data.

What, why or when it is better to choose cshtml vs aspx?

As other people have answered, .cshtml (or .vbhtml if that's your flavor) provides a handler-mapping to load the MVC engine. The .aspx extension simply loads the aspnet_isapi.dll that performs the compile and serves up web forms. The difference in the handler mapping is simply a method of allowing the two to co-exist on the same server allowing both MVC applications and WebForms applications to live under a common root.

This allows to be valid and served with MVC rules along with to be valid as a standard web form.

As for the difference in the technologies, the MVC (Razor) templating framework is intended to return .Net pages to a more RESTful "web-based" platform of templated views separating the code logic between the model (business/data objects), the view (what the user sees) and the controllers (the connection between the two). The WebForms model (aspx) was an attempt by Microsoft to use complex javascript embedding to simulate a more stateful application similar to a WinForms application complete with events and a page lifecycle that would be capable of retaining its own state from page to page.

The choice to use one or the other is always going to be a contentious one because there are arguments for and against both systems. I for one like the simplicity in the MVC architecture (though routing is anything but simple) and the ease of the Razor syntax. I feel the WebForms architecture is just too heavy to be an effective web platform. That being said, there are a lot of instances where the WebForms framework provides a very succinct and usable model with a rich event structure that is well defined. It all boils down to the needs of the application and the preferences of those building it.

Android Endless List

Just wanted to contribute a solution that I used for my app.

It is also based on the OnScrollListener interface, but I found it to have a much better scrolling performance on low-end devices, since none of the visible/total count calculations are carried out during the scroll operations.

  1. Let your ListFragment or ListActivity implement OnScrollListener
  2. Add the following methods to that class:

    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        //leave this empty
    public void onScrollStateChanged(AbsListView listView, int scrollState) {
        if (scrollState == SCROLL_STATE_IDLE) {
            if (listView.getLastVisiblePosition() >= listView.getCount() - 1 - threshold) {
                //load more list items:

    where currentPage is the page of your datasource that should be added to your list, and threshold is the number of list items (counted from the end) that should, if visible, trigger the loading process. If you set threshold to 0, for instance, the user has to scroll to the very end of the list in order to load more items.

  3. (optional) As you can see, the "load-more check" is only called when the user stops scrolling. To improve usability, you may inflate and add a loading indicator to the end of the list via listView.addFooterView(yourFooterView). One example for such a footer view:

    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android=""
        android:padding="10dp" >
            android:layout_gravity="center_vertical" />
            android:text="@string/loading_text" />
  4. (optional) Finally, remove that loading indicator by calling listView.removeFooterView(yourFooterView) if there are no more items or pages.

Convert a tensor to numpy array in Tensorflow?

TensorFlow 2.x

Eager Execution is enabled by default, so just call .numpy() on the Tensor object.

import tensorflow as tf

a = tf.constant([[1, 2], [3, 4]])                 
b = tf.add(a, 1)

# array([[1, 2],
#        [3, 4]], dtype=int32)

# array([[2, 3],
#        [4, 5]], dtype=int32)

tf.multiply(a, b).numpy()
# array([[ 2,  6],
#        [12, 20]], dtype=int32)

See NumPy Compatibility for more. It is worth noting (from the docs),

Numpy array may share memory with the Tensor object. Any changes to one may be reflected in the other.

Bold emphasis mine. A copy may or may not be returned, and this is an implementation detail based on whether the data is in CPU or GPU (in the latter case, a copy has to be made from GPU to host memory).

But why am I getting AttributeError: 'Tensor' object has no attribute 'numpy'?.
A lot of folks have commented about this issue, there are a couple of possible reasons:

  • TF 2.0 is not correctly installed (in which case, try re-installing), or
  • TF 2.0 is installed, but eager execution is disabled for some reason. In such cases, call tf.compat.v1.enable_eager_execution() to enable it, or see below.

If Eager Execution is disabled, you can build a graph and then run it through tf.compat.v1.Session:

a = tf.constant([[1, 2], [3, 4]])                 
b = tf.add(a, 1)
out = tf.multiply(a, b)

# array([[ 2,  6],
#        [12, 20]], dtype=int32)

See also TF 2.0 Symbols Map for a mapping of the old API to the new one.

How to concatenate items in a list to a single string?

Use join:

>>> sentence = ['this', 'is', 'a', 'sentence']
>>> '-'.join(sentence)
>>> ' '.join(sentence)
'this is a sentence'

How to print the full NumPy array, without truncation?

A slight modification: (since you are going to print a huge list)

import numpy as np
np.set_printoptions(threshold=np.inf, linewidth=200)

x = np.arange(1000)

This will increase the number of characters per line (default linewidth of 75). Use any value you like for the linewidth which suits your coding environment. This will save you from having to go through huge number of output lines by adding more characters per line.

React Hook "useState" is called in function "app" which is neither a React function component or a custom React Hook function

If you are still looking for answer of this question all above stated solution work fine but still i will provide the running/correct code below (edited)

import React, { useState } from 'react';
import './App.css';
import Person from './Person/Person'

  const App = props => {
    const [personsState, setPersonsState ] = useState({
        {name: 'Ram', age: 20},
        {name: 'Rahul', age: 24},
        {name: 'Ramesh', age: 25}
      otherState: 'Some Other value' 

    const switchNameHandler = () => {
      //console.log('Click is working');
      //Dont Do THIS: this.state.persons[0].name = 'singh';
        {name: 'Ram',age: 20},
        {name: 'Raj', age: 24},
        {name: 'yts', age: 30} 

    return (
      <div className="App">
        <h1>Nice two one three  Hello i am a noob react developer</h1>
        <button onClick={switchNameHandler}>Switch Name</button>
        <Person name={personsState.persons[0].name} age={personsState.persons[0].age} />
        <Person name={personsState.persons[1].name} age={personsState.persons[1].age}> My hobbies are Gaming</Person>
        <Person name={personsState.persons[2].name} age={personsState.persons[2].age} />
    // return React.createElement('div',{className:'App'}, React.createElement('h1', null, 'Hi learning the basics of react'));

export default App;

Python: call a function from string name

You can use a dictionary too.

def install():
    print "In install"

methods = {'install': install}

method_name = 'install' # set by the command line options
if method_name in methods:
    methods[method_name]() # + argument list of course
    raise Exception("Method %s not implemented" % method_name)

Is it possible to declare a public variable in vba and assign a default value?

Just to offer you a different angle -

I find it's not a good idea to maintain public variables between function calls. Any variables you need to use should be stored in Subs and Functions and passed as parameters. Once the code is done running, you shouldn't expect the VBA Project to maintain the values of any variables.

The reason for this is that there is just a huge slew of things that can inadvertently reset the VBA Project while using the workbook. When this happens, any public variables get reset to 0.

If you need a value to be stored outside of your subs and functions, I highly recommend using a hidden worksheet with named ranges for any information that needs to persist.

Encoding conversion in java

UTF-8 and UCS-2/UTF-16 can be distinguished reasonably easily via a byte order mark at the start of the file. If this exists then it's a pretty good bet that the file is in that encoding - but it's not a dead certainty. You may well also find that the file is in one of those encodings, but doesn't have a byte order mark.

I don't know much about ISO-8859-2, but I wouldn't be surprised if almost every file is a valid text file in that encoding. The best you'll be able to do is check it heuristically. Indeed, the Wikipedia page talking about it would suggest that only byte 0x7f is invalid.

There's no idea of reading a file "as it is" and yet getting text out - a file is a sequence of bytes, so you have to apply a character encoding in order to decode those bytes into characters.

Source by stackoverflow

what is the difference between const_iterator and iterator?

Performance wise there is no difference. The only purpose of having const_iterator over iterator is to manage the accessesibility of the container on which the respective iterator runs. You can understand it more clearly with an example:

std::vector<int> integers{ 3, 4, 56, 6, 778 };

If we were to read & write the members of a container we will use iterator:

for( std::vector<int>::iterator it = integers.begin() ; it != integers.end() ; ++it )
       {*it = 4;  std::cout << *it << std::endl; }

If we were to only read the members of the container integers you might wanna use const_iterator which doesn't allow to write or modify members of container.

for( std::vector<int>::const_iterator it = integers.begin() ; it != integers.end() ; ++it )
       { cout << *it << endl; }

NOTE: if you try to modify the content using *it in second case you will get an error because its read-only.

How to use the start command in a batch file?

I think this other Stack Overflow answer would solve your problem: How do I run a bat file in the background from another bat file?

Basically, you use the /B and /C options:

START /B CMD /C CALL "foo.bat" [args [...]] >NUL 2>&1

Installing a local module using npm?

Since asked and answered by the same person, I'll add a npm link as an alternative.

from docs:

This is handy for installing your own stuff, so that you can work on it and test it iteratively without having to continually rebuild.

cd ~/projects/node-bloggy  # go into the dir of your main project
npm link ../node-redis     # link the dir of your dependency

[Edit] As of NPM 2.0, you can declare local dependencies in package.json

"dependencies": {
    "bar": "file:../foo/bar"

fast way to copy formatting in excel

For me, you can't. But if that suits your needs, you could have speed and formatting by copying the whole range at once, instead of looping:

range("B2:B5002").Copy Destination:=Sheets("Output").Cells(startrow, 2)

And, by the way, you can build a custom range string, like Range("B2:B4, B6, B11:B18")

edit: if your source is "sparse", can't you just format the destination at once when the copy is finished ?

Set Icon Image in Java

Your problem is often due to looking in the wrong place for the image, or if your classes and images are in a jar file, then looking for files where files don't exist. I suggest that you use resources to get rid of the second problem.


// the path must be relative to your *class* files
String imagePath = "res/Image.png";
InputStream imgStream = Game.class.getResourceAsStream(imagePath );
BufferedImage myImg =;
// ImageIcon icon = new ImageIcon(myImg);

// use icon here

Python: CSV write by column rather than row

what about Result_* there also are generated in the loop (because i don't think it's possible to add to the csv file)

i will go like this ; generate all the data at one rotate the matrix write in the file:

A = []

A.append(range(1, 5))  # an Example of you first loop

A.append(range(5, 9))  # an Example of you second loop

data_to_write = zip(*A)

# then you can write now row by row

A full list of all the new/popular databases and their uses?

I doubt I'd use it in a mission-critical system, but Derby has always been very interesting to me.

How do multiple clients connect simultaneously to one port, say 80, on a server?

First off, a "port" is just a number. All a "connection to a port" really represents is a packet which has that number specified in its "destination port" header field.

Now, there are two answers to your question, one for stateful protocols and one for stateless protocols.

For a stateless protocol (ie UDP), there is no problem because "connections" don't exist - multiple people can send packets to the same port, and their packets will arrive in whatever sequence. Nobody is ever in the "connected" state.

For a stateful protocol (like TCP), a connection is identified by a 4-tuple consisting of source and destination ports and source and destination IP addresses. So, if two different machines connect to the same port on a third machine, there are two distinct connections because the source IPs differ. If the same machine (or two behind NAT or otherwise sharing the same IP address) connects twice to a single remote end, the connections are differentiated by source port (which is generally a random high-numbered port).

Simply, if I connect to the same web server twice from my client, the two connections will have different source ports from my perspective and destination ports from the web server's. So there is no ambiguity, even though both connections have the same source and destination IP addresses.

Ports are a way to multiplex IP addresses so that different applications can listen on the same IP address/protocol pair. Unless an application defines its own higher-level protocol, there is no way to multiplex a port. If two connections using the same protocol simultaneously have identical source and destination IPs and identical source and destination ports, they must be the same connection.

Latex Remove Spaces Between Items in List

This question was already asked on The highest voted answer also mentioned the enumitem package (here answered by Stefan), but I also like this one, which involves creating your own itemizing environment instead of loading a new package:

{ \begin{itemize}
    \setlength{\parsep}{0pt}     }
{ \end{itemize}                  } 

Which should be used like this:

  \item one 
  \item two 
  \item three 


Nginx serves .php files as downloads, instead of executing them

One more thing to check: if you've set up HTTPS access before setting up PHP -- I used certbot -- you'll need to make the changes in /etc/nginx/sites-available/default twice because there will be two server blocks (one listening on port 80 and one listening on port 443).

(I was setting up this server primarily for email and didn't have any use for PHP when I first installed nginx just as a way to run certbot more easily.)

How can I get the line number which threw exception?

I tried using the solution By @davy-c but had an Exception "System.FormatException: 'Input string was not in a correct format.'", this was due to there still being text past the line number, I modified the code he posted and came up with:

int line = Convert.ToInt32(objErr.ToString().Substring(objErr.ToString().IndexOf("line")).Substring(0, objErr.ToString().Substring(objErr.ToString().IndexOf("line")).ToString().IndexOf("\r\n")).Replace("line ", ""));

This works for me in VS2017 C#.

Converting String to Int using try/except in Python

Here it is:

s = "123"
  i = int(s)
except ValueError as verr:
  pass # do job to handle: s does not contain anything convertible to int
except Exception as ex:
  pass # do job to handle: Exception occurred while converting to int

Using Spring MVC Test to unit test multipart POST request

The method MockMvcRequestBuilders.fileUpload is deprecated use MockMvcRequestBuilders.multipart instead.

This is an example:

import static org.hamcrest.CoreMatchers.containsString;
import static;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.mock.web.MockMultipartFile;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.ResultActions;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.result.MockMvcResultHandlers;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.multipart.MultipartFile;

 * Unit test New Controller.
public class NewControllerTest {

    private MockMvc mockMvc;

    WebApplicationContext wContext;

    private NewController newController;

    public void setup() {
        this.mockMvc = MockMvcBuilders.webAppContextSetup(wContext)

    public void test() throws Exception {
       // Mock Request
        MockMultipartFile jsonFile = new MockMultipartFile("test.json", "", "application/json", "{\"key1\": \"value1\"}".getBytes());

        // Mock Response
        NewControllerResponseDto response = new NewControllerDto();
        Mockito.when(newController.postV1(Mockito.any(Integer.class), Mockito.any(MultipartFile.class))).thenReturn(response);

                .file("file", jsonFile.getBytes())



Having trouble setting working directory

This may help... use the following code and browse the folder you want to set as the working folder


How to find minimum value from vector?

Try this with


How do I remove the horizontal scrollbar in a div?

To remove the horizontal scroll bar, use the following code. It 100% works.

html, body {
    overflow-x: hidden;

In LaTeX, how can one add a header/footer in the document class Letter?

After I removed

\usepackage{fontspec}% font selecting commands 
\usepackage{xunicode}% unicode character macros 
\usepackage{xltxtra} % some fixes/extras 

it seems to have worked "correctly".

It may be worth noting that the headers and footers only appear from page 2 onwards. Although I've tried the fix for this given in the fancyhdr documentation, I can't get it to work either.

FYI: MikTeX 2.7 under Vista

If '<selector>' is an Angular component, then verify that it is part of this module

Check your selector in your filename.component.ts

Using the tag in various html files I would say


Should be



  selector: 'app-my-first-component',
  templateUrl: './my-first-component.component.html',
  styleUrls: ['./my-first-component.component.scss']

Disable form auto submit on button click

another one:

if(this.checkValidity() == false) {


                return false;

SQL Server: Extract Table Meta-Data (description, fields and their data types)

There are 2 simple ways:

  • Option 1

    sp_help 'schema.table_name'

  • Option 2

    SELECT * FROM INFORMATION_SCHEMA.columns c WHERE c.table_name = 'table_name'

How can multiple rows be concatenated into one in Oracle without creating a stored procedure?

From Oracle 11gR2, the LISTAGG clause should do the trick:

SELECT question_id,
       LISTAGG(element_id, ',') WITHIN GROUP (ORDER BY element_id)
GROUP BY question_id;

Beware if the resulting string is too big (more than 4000 chars for a VARCHAR2, for instance): from version 12cR2, we can use ON OVERFLOW TRUNCATE/ERROR to deal with this issue.

Getting error: ISO C++ forbids declaration of with no type

Your declaration is int ttTreeInsert(int value);

However, your definition/implementation is

ttTree::ttTreeInsert(int value)

Notice that the return type int is missing in the implementation. Instead it should be

int ttTree::ttTreeInsert(int value)
    return 1; // or some valid int

Excel VBA Open a Folder

I use this to open a workbook and then copy that workbook's data to the template.

Private Sub CommandButton24_Click()
Set Template = ActiveWorkbook
 With Application.FileDialog(msoFileDialogOpen)
    .InitialFileName = "I:\Group - Finance" ' Yu can select any folder you want
    .Title = "Your Title"
    If Not .Show Then
        MsgBox "No file selected.": Exit Sub
    End If
    Workbooks.OpenText .SelectedItems(1)

'The below is to copy the file into a new sheet in the workbook and paste those values in sheet 1

    Set myfile = ActiveWorkbook
    ActiveWorkbook.Sheets(1).Copy after:=ThisWorkbook.Sheets(1)

End With

Returning value from called function in a shell script

I think returning 0 for succ/1 for fail (glenn jackman) and olibre's clear and explanatory answer says it all; just to mention a kind of "combo" approach for cases where results are not binary and you'd prefer to set a variable rather than "echoing out" a result (for instance if your function is ALSO suppose to echo something, this approach will not work). What then? (below is Bourne Shell)

# Syntax _w (wrapReturn)
# arg1 : method to wrap
# arg2 : variable to set
eval $1
read $2 <<EOF
eval $2=\$$2

as in (yep, the example is somewhat silly, it's just an.. example)

  d=`date '+%d'`
  [ $d -gt 255 ] && echo "Oh no a return value is 0-255!" && BAIL=0 # this will of course never happen, it's just to clarify the nature of returns
  return $d

  if [ $1 -lt 26 ]; then 
      daysLeft=`expr 25 - $1`
     lastDayInMonth=`date -d "`date +%Y%m01` +1 month -1 day" +%d`
     rest=`expr $lastDayInMonth - 25`
     daysLeft=`expr 25 + $rest`
  echo "Mate, it's another $daysLeft days.."

# main
_w getDay DAY # call getDay, save the result in the DAY variable
dayzToSalary $DAY

Hide div if screen is smaller than a certain width

I have the almost the same situation as yours; that if the screen width is less than the my specified width it should hide the div. This is the jquery code I used that worked for me.

$(window).resize(function() {

  if ($(this).width() < 1024) {


  } else {




How to create a numpy array of arbitrary length strings?

You could use the object data type:

>>> import numpy
>>> s = numpy.array(['a', 'b', 'dude'], dtype='object')
>>> s[0] += 'bcdef'
>>> s
array([abcdef, b, dude], dtype=object)

Excel VBA Password via Hex Editor

New version, now you also have the GC= try to replace both DPB and GC with those

DPB="DBD9775A4B774B77B4894C77DFE8FE6D2CCEB951E8045C2AB7CA507D8F3AC7E3A7F59012A2" GC="BAB816BBF4BCF4BCF4"

password will be "test"

IndentationError: unindent does not match any outer indentation level

For SPYDER users: I'm using spyder 3.3.2 with python 3.7.1 and I solved this, setting indentation to use tabs, with the following steps, click on:

  • Tools.
  • Preferences.
  • Editor.
  • Advanced settings.
  • Indentation characters -> Tabs.

Then I reset the "unidented" line using tab key.

For some reason, without this setting, I got the ghost IndentationError sometimes.

How to enter a series of numbers automatically in Excel

Enter the formula =ROW() into any cell and that cell will show the row number as its value.

If you want 1001, 1002 etc just enter =1000+ROW()

Git reset single file in feature branch to be the same as in master

you are almost there; you just need to give the reference to master; since you want to get the file from the master branch:

git checkout master -- filename

Note that the differences will be cached; so if you want to see the differences you obtained; use

git diff --cached

Why doesn't CSS ellipsis work in table cell?

If you don't want to set max-width to td (like in this answer), you can set max-width to div:

function so_hack(){}

function so_hack(){} function so_hack(){}

function so_hack(){}

Note: 100% doesn't work, but 99% does the trick in FF. Other modern browsers doesn't need silly div hacks.

td {
  border: 1px solid black;
    max-width: 99%;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;


Spark dataframe: collect () vs select ()

calling select will result is lazy evaluation: for example:

val df1 ="col1")
val df2 = df1.filter("col1 == 3")

both above statements create lazy path that will be executed when you call action on that df, such as show, collect etc.

val df3 = df2.collect()

use .explain at the end of your transformation to follow its plan here is more detailed info Transformations and Actions

Equivalent of .bat in mac os

May be you can find answer here? Equivalent of double-clickable .sh and .bat on Mac?

Usually you can create bash script for Mac OS, where you put similar commands as in batch file. For your case create bash file and put same command, but change back-slashes with regular ones.

Your file will look something like:

#! /bin/bash
java -cp  ".;./supportlibraries/Framework_Core.jar;./supportlibraries/Framework_DataTable.jar;./supportlibraries/Framework_Reporting.jar;./supportlibraries/Framework_Utilities.jar;./supportlibraries/poi-3.8-20120326.jar;PATH_TO_YOUR_SELENIUM_SERVER_FOLDER/selenium-server-standalone-2.19.0.jar" allocator.testTrack

Change folders in path above to relevant one.

Then make this script executable: open terminal and navigate to folder with your script. Then change read-write-execute rights for this file running command:

chmod 755

Then you can run it like any other regular script: ./

or you can run it passing file to bash:


How do I find the last column with data?

Lots of ways to do this. The most reliable is find.

Dim rLastCell As Range

Set rLastCell = ws.Cells.Find(What:="*", After:=ws.Cells(1, 1), LookIn:=xlFormulas, LookAt:= _
xlPart, SearchOrder:=xlByColumns, SearchDirection:=xlPrevious, MatchCase:=False)

MsgBox ("The last used column is: " & rLastCell.Column)

If you want to find the last column used in a particular row you can use:

Dim lColumn As Long

lColumn = ws.Cells(1, Columns.Count).End(xlToLeft).Column

Using used range (less reliable):

Dim lColumn As Long

lColumn = ws.UsedRange.Columns.Count

Using used range wont work if you have no data in column A. See here for another issue with used range:

See Here regarding resetting used range.

Calling constructors in c++ without new

I assume with the second line you actually mean:

Thing *thing = new Thing("uiae");

which would be the standard way of creating new dynamic objects (necessary for dynamic binding and polymorphism) and storing their address to a pointer. Your code does what JaredPar described, namely creating two objects (one passed a const char*, the other passed a const Thing&), and then calling the destructor (~Thing()) on the first object (the const char* one).

By contrast, this:

Thing thing("uiae");

creates a static object which is destroyed automatically upon exiting the current scope.

How to make an element width: 100% minus padding?

For me, using margin:15px;padding:10px 0 15px 23px;width:100%, the result was this:

enter image description here

The solution for me was to use width:auto instead of width:100%. My new code was:

margin:15px;padding:10px 0 15px 23px;width:auto. Then the element aligned properly:

enter image description here

Check if a string contains a substring in SQL Server 2005, using a stored procedure

CHARINDEX() searches for a substring within a larger string, and returns the position of the match, or 0 if no match is found

if CHARINDEX('ME',@mainString) > 0
    --do something

Edit or from daniels answer, if you're wanting to find a word (and not subcomponents of words), your CHARINDEX call would look like:

CHARINDEX(' ME ',' ' + REPLACE(REPLACE(@mainString,',',' '),'.',' ') + ' ')

(Add more recursive REPLACE() calls for any other punctuation that may occur)

Function in JavaScript that can be called only once

keep it as simple as possible

function sree(){
  window.sree = _=>{};

You can see the result

script result

ERROR 1130 (HY000): Host '' is not allowed to connect to this MySQL server

mysql> CREATE USER 'name'@'%' IDENTIFIED BY 'passWord'; Query OK, 0 rows affected (0.00 sec)

mysql> GRANT ALL PRIVILEGES ON . TO 'name'@'%'; Query OK, 0 rows affected (0.00 sec)

mysql> FLUSH PRIVILEGES; Query OK, 0 rows affected (0.00 sec)


  1. Make sure you have your name and % the right way round
  2. Makes sure you have added your port 3306 to any firewall you may be running (although this will give a different error message)

hope this helps someone...

Int or Number DataType for DataAnnotation validation attribute

Try one of these regular expressions:

// for numbers that need to start with a zero

// for numbers that begin from 1

hope it helps :D

Is there a C# case insensitive equals operator?

I am so used to typing at the end of these comparison methods: , StringComparison.

So I made an extension.

namespace System
{   public static class StringExtension
        public static bool Equals(this string thisString, string compareString,
             StringComparison stringComparison)
            return string.Equals(thisString, compareString, stringComparison);

Just note that you will need to check for null on thisString prior to calling the ext.

Where does Oracle SQL Developer store connections?

SqlDeveloper stores all the connections in a file named


In windows XP you can find the file in location

C:\Documents and Settings\<username>\Application Data\SQL Developer\systemX.X.X.X.X\o.jdeveloper.db.connection.X.X.X.X.X.X.X\connections.xml

In Windows 7 you will find it in location

C:\Users\<username>\AppData\Roaming\SQL Developer\systemX.X.X.X.X\o.jdeveloper.db.connection.X.X.X.X.X.X.X\connections.xml

Android adding simple animations while setvisibility(view.Gone)

You can do two things to add animations, first you can let android animate layout changes for you. That way every time you change something in the layout like changing view visibility or view positions android will automatically create fade/transition animations. To use that set


on the root node in your layout.

Your second option would be to manually add animations. For this I suggest you use the new animation API introduced in Android 3.0 (Honeycomb). I can give you a few examples:

This fades out a View:


This fades it back in:


This moves a View down by its height:


This returns the View to its starting position after it has been moved somewhere else:


You can also use setDuration() to set the duration of the animation. For example this fades out a View over a period of 2 seconds:


And you can combine as many animations as you like, for example this fades out a View and moves it down at the same time over a period of 0.3 seconds:


And you can also assign a listener to the animation and react to all kinds of events. Like when the animation starts, when it ends or repeats etc. By using the abstract class AnimatorListenerAdapter you don't have to implement all callbacks of AnimatorListener at once but only those you need. This makes the code more readable. For example the following code fades out a View moves it down by its height over a period of 0.3 seconds (300 milliseconds) and when the animation is done its visibility is set to View.GONE.

        .setListener(new AnimatorListenerAdapter() {
            public void onAnimationEnd(Animator animation) {


You have to define a table alias for a derived table in SQL Server:

        SELECT * FROM TABLE2) x

"x" is the table alias in this example.

How to add an image to the "drawable" folder in Android Studio?

Tutorial Source Link

Android Studio 3.2

Blazingly fast :P

enter image description here

Just Copy and Paste in this folder

LINQ - Left Join, Group By, and Count

Consider using a subquery:

from p in context.ParentTable 
let cCount =
  from c in context.ChildTable
  where p.ParentId == c.ChildParentId
  select c
select new { ParentId = p.Key, Count = cCount } ;

If the query types are connected by an association, this simplifies to:

from p in context.ParentTable 
let cCount = p.Children.Count()
select new { ParentId = p.Key, Count = cCount } ;

Sort a list alphabetically

You should be able to use OrderBy in LINQ...

var sortedItems = myList.OrderBy(s => s);

How to add a TextView to a LinearLayout dynamically in Android?


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android=""
 android:layout_height="match_parent" >


class file:

TextView textView = new TextView(getApplicationContext());

textView.setText("testDynamic textView");

make arrayList.toArray() return more specific types

 public static <E> E[] arrayListToTypedArray(List<E> list) {

    if (list == null) {
      return null;
    int noItems = list.size();
    if (noItems == 0) {
      return null;

    E[] listAsTypedArray;
    E typeHelper = list.get(0);

    try {
      Object o = Array.newInstance(typeHelper.getClass(), noItems);
      listAsTypedArray = (E[]) o;
      for (int i = 0; i < noItems; i++) {
        Array.set(listAsTypedArray, i, list.get(i));
    } catch (Exception e) {
      return null;

    return listAsTypedArray;

Create a jTDS connection string

SQLServer runs the default instance over port 1433. If you specify the port as port 1433, SQLServer will only look for the default instance. The name of the default instance was created at setup and usually is SQLEXPRESSxxx_xx_ENU.

The instance name also matches the folder name created in Program Files -> Microsoft SQL Server. So if you look there and see one folder named SQLEXPRESSxxx_xx_ENU it is the default instance.

Folders named MSSQL12.myInstanceName (for SQLServer 2012) are named instances in SQL Server and are not accessed via port 1433.

So if your program is accessing a default instance in the database, specify port 1433, and you may not need to specify the instance name.

If your program is accessing a named instance (not the default instance) in the database DO NOT specify the port but you must specify the instance name.

I hope this clarifies some of the confusion emanating from the errors above.

How can I make an "are you sure" prompt in a Windows batchfile?

Here's my go-to method for a yes/no answer.

It's case-insensitive also.

This just checks for the errors given by the input and sets the choice variable to whatever you require so it can be used below in the code.

@echo off
choice /M "[Opt 1]  Do you want to continue [Yes/No]"
if errorlevel 255 (
  echo Error
  ) else if errorlevel 2 (
  set "YourChoice=will not"
  ) else if errorlevel 1 (
  set "YourChoice=will"
  ) else if errorlevel 0 (
  goto :EOF
  echo %YourChoice%

What is the difference between =Empty and IsEmpty() in VBA (Excel)?

I believe IsEmpty is just method that takes return value of Cell and checks if its Empty so: IsEmpty(.Cell(i,1)) does ->

return .Cell(i,1) <> Empty

How to install Python package from GitHub?

You need to use the proper git URL:

pip install git+

Also see the VCS Support section of the pip documentation.

Don’t forget to include the egg=<projectname> part to explicitly name the project; this way pip can track metadata for it without having to have run the script.

How to dynamically create CSS class in JavaScript and apply?

One liner, attach one or many new cascading rule(s) to the document.

This example attach a cursor:pointer to every button, input, select.

document.body.appendChild(Object.assign(document.createElement("style"), {textContent: "select, button, input {cursor:pointer}"

Export to csv in jQuery

By using just jQuery, you cannot avoid a server call.

However, to achieve this result, I'm using Downloadify, which lets me save files without having to make another server call. Doing this reduces server load and makes a good user experience.

To get a proper CSV you just have to take out all the unnecessary tags and put a ',' between the data.

Groovy - How to compare the string?

This line:


Should be:

if( str2 == str ) {

The ${ and } will give you a parse error, as they should only be used inside Groovy Strings for templating

Effective method to hide email from spam bots

The best method hiding email addresses is only good until bot programmer discover this "encoding" and implement a decryption algorithm.

The JavaScript option won't work long, because there are a lot of crawler interpreting JavaScript.

There's no answer, imho.

jquery drop down menu closing by clicking outside

Another multiple dropdown example that works

$('.moderate .button').on('click', (event) => {_x000D_
$(document).click(function(e) {_x000D_
<link href="" rel="stylesheet" />_x000D_
.dropdown {_x000D_
  box-shadow: 0 0 2px #777;_x000D_
  display: none;_x000D_
  left: 0;_x000D_
  position: absolute;_x000D_
  padding: 2px;_x000D_
  z-index: 10;_x000D_
.dropdown a {_x000D_
  font-size: 12px;_x000D_
  padding: 4px;_x000D_
_x000D_ {_x000D_
  display: block;_x000D_
<div class="control moderate">_x000D_
  <button class="button is-small" type="button">_x000D_
  <div class="box dropdown">_x000D_
      <li><a class="nav-item">edit</a></li>_x000D_
      <li><a class="nav-item">delete</a></li>_x000D_
      <li><a class="nav-item">block user</a>   </li>_x000D_
<div class="control moderate">_x000D_
  <button class="button is-small" type="button">_x000D_
  <div class="box dropdown">_x000D_
      <li><a class="nav-item">edit</a></li>_x000D_
      <li><a class="nav-item">delete</a></li>_x000D_
      <li><a class="nav-item">block user</a></li>_x000D_

Web scraping with Python

Use urllib2 in combination with the brilliant BeautifulSoup library:

import urllib2
from BeautifulSoup import BeautifulSoup
# or if you're using BeautifulSoup4:
# from bs4 import BeautifulSoup

soup = BeautifulSoup(urllib2.urlopen('').read())

for row in soup('table', {'class': 'spad'})[0].tbody('tr'):
    tds = row('td')
    print tds[0].string, tds[1].string
    # will print date and sunrise

Create a new cmd.exe window from within another cmd.exe prompt

start cmd.exe 

opens a separate window

start file.cmd 

opens the batch file and executes it in another command prompt

Negation in Python

Combining the input from everyone else (use not, no parens, use os.mkdir) you'd get...

special_path_for_john = "/usr/share/sounds/blues"
if not os.path.exists(special_path_for_john):

Get user info via Google API

There are 3 steps that needs to be run.

  1. Register your app's client id from Google API console
  2. Ask your end user to give consent using this api
  3. Use google's oauth2 api as described at using the token obtained in step 2. (Though still I could not find how to fill "fields" parameter properly).

It is very interesting that this simplest usage is not clearly described anywhere. And i believe there is a danger, you should pay attention to the verified_emailparameter coming in the response. Because if I am not wrong it may yield fake emails to register your application. (This is just my interpretation, has a fair chance that I may be wrong!)

I find facebook's OAuth mechanics much much clearly described.

How to Get XML Node from XDocument


<?xml version="1.0" encoding="utf-8"?>

Select a single node:

XDocument XMLDoc = XDocument.Load("test.xml");
string id = "123"; // id to be selected

XElement Contact = (from xml2 in XMLDoc.Descendants("Node")
                    where xml2.Element("ID").Value == id
                    select xml2).FirstOrDefault();


Delete a single node:

XDocument XMLDoc = XDocument.Load("test.xml");
string id = "123";

var Contact = (from xml2 in XMLDoc.Descendants("Node")
               where xml2.Element("ID").Value == id
               select xml2).FirstOrDefault();


Add new node:

XDocument XMLDoc = XDocument.Load("test.xml");

XElement newNode = new XElement("Node",
    new XElement("ID", "500"),
    new XElement("Name", "Whatever")


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.

Get variable from PHP to JavaScript

You can print the PHP variable into your javascript while your page is created.

<script type="text/javascript">
    var MyJSStringVar = "<?php Print($MyPHPStringVar); ?>";
    var MyJSNumVar = <?php Print($MyPHPNumVar); ?>;

Of course this is for simple variables and not objects.

How to programmatically turn off WiFi on Android device?

You need the following permissions in your manifest file:

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>

Then you can use the following in your activity class:

WifiManager wifiManager = (WifiManager) this.getApplicationContext().getSystemService(Context.WIFI_SERVICE); 

Use the following to check if it's enabled or not

boolean wifiEnabled = wifiManager.isWifiEnabled()

You'll find a nice tutorial on the subject on this site.

Excel VBA Loop on columns

Just use the Cells function and loop thru columns. Cells(Row,Column)

Does Visual Studio Code have box select/multi-line edit?

The shortcuts I use in Visual Studio for multiline (aka box) select are Shift + Alt + up/down/left/right

To create this in Visual Studio Code you can add these keybindings to the keybindings.json file (menu FilePreferencesKeyboard shortcuts).

{ "key": "shift+alt+down", "command": "editor.action.insertCursorBelow",
                                 "when": "editorTextFocus" },
{ "key": "shift+alt+up", "command": "editor.action.insertCursorAbove",
                                 "when": "editorTextFocus" },
{ "key": "shift+alt+right", "command": "cursorRightSelect",
                                     "when": "editorTextFocus" },
{ "key": "shift+alt+left", "command": "cursorLeftSelect",
                                     "when": "editorTextFocus" }

jQuery: Test if checkbox is NOT checked

if (!$("#checkSurfaceEnvironment-1").is(":checked")) {
    // do something if the checkbox is NOT checked

Reactjs setState() with a dynamic key name?

Thanks to @Cory's hint, i used this:

inputChangeHandler : function (event) {
    var stateObject = function() {
      returnObj = {};
      returnObj[] =;
         return returnObj;

    this.setState( stateObject );    

If using ES6 or the Babel transpiler to transform your JSX code, you can accomplish this with computed property names, too:

inputChangeHandler : function (event) {
    this.setState({ []: });
    // alternatively using template strings for strings
    // this.setState({ [`key${}`]: });

Adding a line break in MySQL INSERT INTO text

MySQL can record linebreaks just fine in most cases, but the problem is, you need <br /> tags in the actual string for your browser to show the breaks. Since you mentioned PHP, you can use the nl2br() function to convert a linebreak character ("\n") into HTML <br /> tag.

Just use it like this:

echo nl2br("Hello, World!\n I hate you so much");

Output (in HTML):

Hello, World!<br>I hate you so much

Here's a link to the manual:

filemtime "warning stat failed for"

Shorter version for those who like short code:

// usage: deleteOldFiles("./xml", "xml,xsl", 24 * 3600)

function deleteOldFiles($dir, $patterns = "*", int $timeout = 3600) {

    // $dir is directory, $patterns is file types e.g. "txt,xls", $timeout is max age

    foreach (glob($dir."/*"."{{$patterns}}",GLOB_BRACE) as $f) { 

        if (is_writable($f) && filemtime($f) < (time() - $timeout))



Sanitizing strings to make them URL and filename safe?

Try this:

function normal_chars($string)
    $string = htmlentities($string, ENT_QUOTES, 'UTF-8');
    $string = preg_replace('~&([a-z]{1,2})(acute|cedil|circ|grave|lig|orn|ring|slash|th|tilde|uml);~i', '$1', $string);
    $string = html_entity_decode($string, ENT_QUOTES, 'UTF-8');
    $string = preg_replace(array('~[^0-9a-z]~i', '~[ -]+~'), ' ', $string);

    return trim($string, ' -');


echo normal_chars('Álix----_Ãxel!?!?'); // Alix Axel
echo normal_chars('áéíóúÁÉÍÓÚ'); // aeiouAEIOU
echo normal_chars('üÿÄËÏÖÜŸåÅ'); // uyAEIOUYaA

Based on the selected answer in this thread: URL Friendly Username in PHP?

How can I get the current time in C#?

DateTime.Now is what you're searching for...

curl: (6) Could not resolve host:; Name or service not known

Perhaps you have some very weird and restrictive SELinux rules in place?

If not, try strace -o /tmp/wtf -fF curl -v and try to spot from /tmp/wtf output file what's going on.

JavaScript: Difference between .forEach() and .map()

  • Array.forEach “executes a provided function once per array element.”

  • “creates a new array with the results of calling a provided function on every element in this array.”

So, forEach doesn’t actually return anything. It just calls the function for each array element and then it’s done. So whatever you return within that called function is simply discarded.

On the other hand, map will similarly call the function for each array element but instead of discarding its return value, it will capture it and build a new array of those return values.

This also means that you could use map wherever you are using forEach but you still shouldn’t do that so you don’t collect the return values without any purpose. It’s just more efficient to not collect them if you don’t need them.

Can the :not() pseudo-class have multiple arguments?

If you're using SASS in your project, I've built this mixin to make it work the way we all want it to:

@mixin not($ignorList...) {
    //if only a single value given
    @if (length($ignorList) == 1){
        //it is probably a list variable so set ignore list to the variable
        $ignorList: nth($ignorList,1);
    //set up an empty $notOutput variable
    $notOutput: '';
    //for each item in the list
    @each $not in $ignorList {
        //generate a :not([ignored_item]) segment for each item in the ignore list and put them back to back
        $notOutput: $notOutput + ':not(#{$not})';
    //output the full :not() rule including all ignored items
    &#{$notOutput} {

it can be used in 2 ways:

Option 1: list the ignored items inline

input {
  /*non-ignored styling goes here*/
  @include not('[type="radio"]','[type="checkbox"]'){
    /*ignored styling goes here*/

Option 2: list the ignored items in a variable first


input {
  /*non-ignored styling goes here*/
  @include not($ignoredItems){
    /*ignored styling goes here*/

Outputted CSS for either option

input {
    /*non-ignored styling goes here*/

input:not([type="radio"]):not([type="checkbox"]) {
    /*ignored styling goes here*/

How to use function srand() with time.h?

If you chose to srand, it is a good idea to then call rand() at least once before you use it, because it is a kind of horrible primitive psuedo-random generator. See Stack Overflow question Why does rand() % 7 always return 0?.

//Now use rand()

If available, either random or arc4rand would be better.

How to grant remote access to MySQL for a whole subnet?

Motivated by @Malvineaus answer I tried it myself and noticed that it didn't work for me.

You can specify subnet masks with '192.168.1.%' or '' but the subnet must always be on complete octets. see As result the functionality between one way of specification and the other is the same.

For example '' will not work as it is not on a complete octet boundary.

How to write a link like <a href="#id"> which link to the same page in PHP?

try this

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
        <a href="#name">click me</a>
        <div name="name" id="name">here</div>

Source file not compiled Dev C++

I was facing the same issue as described above.

It can be resolved by creating a new project and creating a new file in that project. Save the file and then try to build and run.

Hope that helps. :)

Dynamically add script tag with src that may include document.write

I tried it by recursively appending each script

Note If your scripts are dependent one after other, then position will need to be in sync.

Major Dependency should be in last in array so that initial scripts can use it

const scripts = ['', '', '']_x000D_
let count = 0_x000D_
 const recursivelyAddScript = (script, cb) => {_x000D_
  const el = document.createElement('script')_x000D_
  el.src = script_x000D_
  if(count < scripts.length) {_x000D_
    count ++_x000D_
    el.onload = recursivelyAddScript(scripts[count])_x000D_
  } else {_x000D_
    console.log('All script loaded')_x000D_

maxFileSize and acceptFileTypes in blueimp file upload plugin do not work. Why?

  • You can also use the file extension to check for the filetype.
  • More simpler way would be to do something as given below inside add :

    add : function (e,data){
       var extension = data.originalFiles[0].name.substr( 
       (data.originalFiles[0].name.lastIndexOf('.') +1) );
                    case 'csv':
                    case 'xls':
                    case 'xlsx':
                        data.url = <Your URL>; 
                        alert("File type not accepted");

Transfer data between databases with PostgreSQL

Just like leonbloy suggested, using two schemas in a database is the way to go. Suppose a source schema (old DB) and a target schema (new DB), you can try something like this (you should consider column names, types, etc.):

INSERT INTO target.Awards SELECT * FROM source.Nominations;

postgresql return 0 if returned value is null

(this answer was added to provide shorter and more generic examples to the question - without including all the case-specific details in the original question).

There are two distinct "problems" here, the first is if a table or subquery has no rows, the second is if there are NULL values in the query.

For all versions I've tested, postgres and mysql will ignore all NULL values when averaging, and it will return NULL if there is nothing to average over. This generally makes sense, as NULL is to be considered "unknown". If you want to override this you can use coalesce (as suggested by Luc M).

$ create table foo (bar int);

$ select avg(bar) from foo;

(1 row)

$ select coalesce(avg(bar), 0) from foo;
(1 row)

$ insert into foo values (3);
$ insert into foo values (9);
$ insert into foo values (NULL);
$ select coalesce(avg(bar), 0) from foo;
(1 row)

of course, "from foo" can be replaced by "from (... any complicated logic here ...) as foo"

Now, should the NULL row in the table be counted as 0? Then coalesce has to be used inside the avg call.

$ select coalesce(avg(coalesce(bar, 0)), 0) from foo;
(1 row)

CASE IN statement with multiple values

The question is specific to SQL Server, but I would like to extend Martin Smith's answer.

SQL:2003 standard allows to define multiple values for simple case expression:

          WHEN '1121231','31242323' THEN 1
          WHEN '234523','2342423' THEN 2
       END AS Test
FROM tblClient c;

It is optional feature: Comma-separated predicates in simple CASE expression“ (F263).


CASE <common operand>
     WHEN <expression>[, <expression> ...] THEN <result>
    [WHEN <expression>[, <expression> ...] THEN <result>
    [ELSE <result>]

As for know I am not aware of any RDBMS that actually supports that syntax.

T-SQL Cast versus Convert

CAST is standard SQL, but CONVERT is only for the dialect T-SQL. We have a small advantage for convert in the case of datetime.

With CAST, you indicate the expression and the target type; with CONVERT, there’s a third argument representing the style for the conversion, which is supported for some conversions, like between character strings and date and time values. For example, CONVERT(DATE, '1/2/2012', 101) converts the literal character string to DATE using style 101 representing the United States standard.

How to add a RequiredFieldValidator to DropDownList control?

If you are using a data source, here's another way to do it without code behind.

Note the following key points:

  • The ListItem of Value="0" is on the source page, not added in code
  • The ListItem in the source will be overwritten if you don't include AppendDataBoundItems="true" in the DropDownList
  • InitialValue="0" tells the validator that this is the value that should fire that validator (as pointed out in other answers)


<asp:DropDownList ID="ddlType" runat="server" DataSourceID="sdsType"
                  DataValueField="ID" DataTextField="Name" AppendDataBoundItems="true">
    <asp:ListItem Value="0" Text="--Please Select--" Selected="True"></asp:ListItem>
<asp:RequiredFieldValidator ID="rfvType" runat="server" ControlToValidate="ddlType" 
                            InitialValue="0" ErrorMessage="Type required"></asp:RequiredFieldValidator>
<asp:SqlDataSource ID="sdsType" runat="server" 
                   ConnectionString='<%$ ConnectionStrings:TESTConnectionString %>'
                   SelectCommand="SELECT ID, Name FROM Type"></asp:SqlDataSource>

Mongoose: Get full list of users

In case we want to list all documents in Mongoose collection after update or delete

We can edit the function to some thing like this:

exports.product_update = function (req, res, next) {
        Product.findByIdAndUpdate(, {$set: req.body}, function (err, product) {
            if (err) return next(err);
            Product.find({}).then(function (products) {
            //res.send('Product udpated.');

This will list all documents on success instead of just showing success message

Complex JSON nesting of objects and arrays

Make sure you follow the language definition for JSON. In your second example, the section:


Is invalid since an object must be composed of zero or more key-value pairs "a" : "b", where "b" may be any valid value. Some parsers may automatically interpret { "" } to be { "" : null }, but this is not a clearly defined case.

Also, you are using a nested array of objects [{}] quite a bit. I would only do this if:

  1. There is no good "identifier" string for each object in the array.
  2. There is some clear reason for having an array over a key-value for that entry.

what is the difference between ajax and jquery and which one is better?

AJAX is a technique to do an XMLHttpRequest (out of band Http request) from a web page to the server and send/retrieve data to be used on the web page. AJAX stands for Asynchronous Javascript And XML. It uses javascript to construct an XMLHttpRequest, typically using different techniques on various browsers.

jQuery (website) is a javascript framework that makes working with the DOM easier by building lots of high level functionality that can be used to search and interact with the DOM. Part of the functionality of jQuery implements a high-level interface to do AJAX requests. jQuery implements this interface abstractly, shielding the developer from the complexity of multi-browser support in making the request.

Two decimal places using printf( )

Use: "%.2f" or variations on that.

See the POSIX spec for an authoritative specification of the printf() format strings. Note that it separates POSIX extras from the core C99 specification. There are some C++ sites which show up in a Google search, but some at least have a dubious reputation, judging from comments seen elsewhere on SO.

Since you're coding in C++, you should probably be avoiding printf() and its relatives.

Eclipse : Maven search dependencies doesn't work

Eclipse artifact searching depends on repository's index file. It seems you did not download the index file.

Go to Window -> Prefrences -> Maven and check "Download repository index updates on start". Restart Eclipse and then look at the progress view. An index file should be downloading.

After downloading completely, artifact searching will be ready to use.

Maven Settings

UPDATE You also need to rebuild your Maven repository index in 'maven repository view'.

In this view , open 'Global Repositories', right-click 'central', check 'Full Index Enable', and then, click 'Rebuild Index' in the same menu.

A 66M index file will be downloaded.

Maven Repositories -> Rebuild Index

How can I check if a string is null or empty in PowerShell?

In addition to [string]::IsNullOrEmpty in order to check for null or empty you can cast a string to a Boolean explicitly or in Boolean expressions:

$string = $null
if (!$string) { "string is null or empty" }

$string = ''
if (!$string) { "string is null or empty" }

$string = 'something'
if ($string) { "string is not null or empty" }


string is null or empty

string is null or empty

string is not null or empty

Generating a list of pages (not posts) without the index file

I have never used jekyll, but it's main page says that it uses Liquid, and according to their docs, I think the following should work:

<ul> {% for page in site.pages %}     {% if page.title != 'index' %}     <li><div class="drvce"><a href="{{ page.url }}">{{ page.title }}</a></div></li>     {% endif %} {% endfor %} </ul> 

LINQ order by null column where order is ascending and nulls should be last

I was trying to find a LINQ solution to this but couldn't work it out from the answers here.

My final answer was:

.OrderByDescending(p => p.LowestPrice.HasValue).ThenBy(p => p.LowestPrice)

VBA module that runs other modules

As long as the macros in question are in the same workbook and you verify the names exist, you can call those macros from any other module by name, not by module.

So if in Module1 you had two macros Macro1 and Macro2 and in Module2 you had Macro3 and Macro 4, then in another macro you could call them all:

Sub MasterMacro()
    Call Macro1
    Call Macro2
    Call Macro3
    Call Macro4
End Sub

How to update-alternatives to Python 3 without breaking apt?

Per Debian policy, python refers to Python 2 and python3 refers to Python 3. Don't try to change this system-wide or you are in for the sort of trouble you already discovered.

Virtual environments allow you to run an isolated Python installation with whatever version of Python and whatever libraries you need without messing with the system Python install.

With recent Python 3, venv is part of the standard library; with older versions, you might need to install python3-venv or a similar package.

$HOME~$ python --version
Python 2.7.11

$HOME~$ python3 -m venv myenv
... stuff happens ...

$HOME~$ . ./myenv/bin/activate

(myenv) $HOME~$ type python   # "type" is preferred over which; see POSIX
python is /home/you/myenv/bin/python

(myenv) $HOME~$ python --version
Python 3.5.1

A common practice is to have a separate environment for each project you work on, anyway; but if you want this to look like it's effectively system-wide for your own login, you could add the activation stanza to your .profile or similar.

TimeStamp on file name using PowerShell

Here's some PowerShell code that should work. You can combine most of this into fewer lines, but I wanted to keep it clear and readable.

[string]$filePath = "C:\";

[string]$directory = [System.IO.Path]::GetDirectoryName($filePath);
[string]$strippedFileName = [System.IO.Path]::GetFileNameWithoutExtension($filePath);
[string]$extension = [System.IO.Path]::GetExtension($filePath);
[string]$newFileName = $strippedFileName + [DateTime]::Now.ToString("yyyyMMdd-HHmmss") + $extension;
[string]$newFilePath = [System.IO.Path]::Combine($directory, $newFileName);

Move-Item -LiteralPath $filePath -Destination $newFilePath;

Random number c++ in some range

Since nobody posted the modern C++ approach yet,

#include <iostream>
#include <random>
int main()
    std::random_device rd; // obtain a random number from hardware
    std::mt19937 gen(rd()); // seed the generator
    std::uniform_int_distribution<> distr(25, 63); // define the range

    for(int n=0; n<40; ++n)
        std::cout << distr(gen) << ' '; // generate numbers

What to put in a python module docstring?

To quote the specifications:

The docstring of a script (a stand-alone program) should be usable as its "usage" message, printed when the script is invoked with incorrect or missing arguments (or perhaps with a "-h" option, for "help"). Such a docstring should document the script's function and command line syntax, environment variables, and files. Usage messages can be fairly elaborate (several screens full) and should be sufficient for a new user to use the command properly, as well as a complete quick reference to all options and arguments for the sophisticated user.

The docstring for a module should generally list the classes, exceptions and functions (and any other objects) that are exported by the module, with a one-line summary of each. (These summaries generally give less detail than the summary line in the object's docstring.) The docstring for a package (i.e., the docstring of the package's module) should also list the modules and subpackages exported by the package.

The docstring for a class should summarize its behavior and list the public methods and instance variables. If the class is intended to be subclassed, and has an additional interface for subclasses, this interface should be listed separately (in the docstring). The class constructor should be documented in the docstring for its __init__ method. Individual methods should be documented by their own docstring.

The docstring of a function or method is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". A multiline-docstring for a function or method should summarize its behavior and document its arguments, return value(s), side effects, exceptions raised, and restrictions on when it can be called (all if applicable). Optional arguments should be indicated. It should be documented whether keyword arguments are part of the interface.

Upload video files via PHP and save them in appropriate folder and have a database entry

PHP file (name is upload.php)    

    // =============  File Upload Code d  ===========================================
    $target_dir = "uploaded/";

    $target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
    $uploadOk = 1;
    $imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);

    // Check if file already exists
    if (file_exists($target_file)) {
        echo "Sorry, file already exists.";
        $uploadOk = 0;

     // Check file size -- Kept for 500Mb
    if ($_FILES["fileToUpload"]["size"] > 500000000) {
        echo "Sorry, your file is too large.";
        $uploadOk = 0;

    // Allow certain file formats
    if($imageFileType != "wmv" && $imageFileType != "mp4" && $imageFileType != "avi" && $imageFileType != "MP4") {
        echo "Sorry, only wmv, mp4 & avi files are allowed.";
        $uploadOk = 0;

    // Check if $uploadOk is set to 0 by an error
    if ($uploadOk == 0) {
        echo "Sorry, your file was not uploaded.";
    // if everything is ok, try to upload file
    } else {
        if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
            echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
        } else {
            echo "Sorry, there was an error uploading your file.";
    // ===============================================  File Upload Code u  ==========================================================

    // =============  Connectivity for DATABASE d ===================================
    $servername = "localhost";
    $username = "root";
    $password = "";
    $dbname = "test";

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);

    $vidname = $_FILES["fileToUpload"]["name"] . "";
    $vidsize = $_FILES["fileToUpload"]["size"] . "";
    $vidtype = $_FILES["fileToUpload"]["type"] . "";

    $sql = "INSERT INTO videos (name, size, type) VALUES ('$vidname','$vidsize','$vidtype')";

    if ($conn->query($sql) === TRUE) {} 
    else {
        echo "Error: " . $sql . "<br>" . $conn->error;

    // =============  Connectivity for DATABASE u ===================================


Activating Anaconda Environment in VsCode

Find a note here:

As noted earlier, the Python extension automatically detects existing conda environments provided that the environment contains a Python interpreter. For example, the following command creates a conda environment with the Python 3.4 interpreter and several libraries, which VS Code then shows in the list of available interpreters:

 conda create -n env-01 python=3.4 scipy=0.15.0 astroid babel 

In contrast, if you fail to specify an interpreter, as with conda create --name env-00, the environment won't appear in the list.

How do you add an SDK to Android Studio?

I had opened a ticket also with Google's support, and received the solution. Instead of choosing the sdk/platform/android-16 folder, if you select the top-level "sdk" folder instead, you'll then be asked to choose which SDK you want to add. This worked!

enter image description here

enter image description here

OnItemCLickListener not working in listview

I've tried all the above and NOTHING worked.

I solved the problem as follows:

First I define a custom Button called ListButton

public class ListButton extends android.widget.Button

private ButtonClickedListener clickListener;

public ListButton(Context context)
    this(context, null);

public ListButton(Context context, AttributeSet attrs)
    this(context, attrs, 0);

public ListButton(Context context, AttributeSet attrs, int defStyle)
    super(context, attrs, defStyle);

public void setClickListener(ButtonClickedListener listener) {
    this.clickListener = listener;

public boolean isInTouchMode() {
    return true;

public boolean onTouchEvent(MotionEvent event) {

    return false;

public boolean dispatchTouchEvent(MotionEvent event) {

    switch (event.getAction()) 
          case MotionEvent.ACTION_DOWN:
          case MotionEvent.ACTION_UP:


          case MotionEvent.ACTION_CANCEL:
          case MotionEvent.ACTION_MOVE:
          default :

    return true;

private void eventClicked() {
    if (this.clickListener!=null) {


The XML looks like:


Then I define my own ButtonClicked Listener interface:

public interface ButtonClickedListener {
    public void ButtonClicked();

Then I use my own listener just as if it was the normal OnClickListener:

final ListButton cancelButton = (ListButton) viewLayout.findViewById(;

    cancelButton.setClickListener(new ButtonClickedListener() {

        public void ButtonClicked() {
            //Do your own stuff here...


What is an opaque response, and what purpose does it serve?

Opaque responses can't be accessed by JavaScript, but you can still cache them with the Cache API and respond with them in the fetch event handler in a service worker. So they're useful for making your app offline, also for resources that you can't control (e.g. resources on a CDN that doesn't set the CORS headers).

The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions

You do not need to use ORDER BY in inner query after WHERE clause because you have already used it in ROW_NUMBER() OVER (ORDER BY VRDATE DESC).

        item.description as item_description, as party_name, 
    FROM StockMain 
    INNER JOIN StockDetail 
        ON StockMain.stid = StockDetail.stid 
    INNER JOIN party 
        ON party.party_id = stockmain.party_id 
    INNER JOIN item 
        ON item.item_id = stockdetail.item_id 
    WHERE stockmain.etype='purchase' 
) AS MyDerivedTable
    MyDerivedTable.RowNum BETWEEN 1 and 5 

How to convert 2D float numpy array to 2D int numpy array?

Some numpy functions for how to control the rounding: rint, floor,trunc, ceil. depending how u wish to round the floats, up, down, or to the nearest int.

>>> x = np.array([[1.0,2.3],[1.3,2.9]])
>>> x
array([[ 1. ,  2.3],
       [ 1.3,  2.9]])
>>> y = np.trunc(x)
>>> y
array([[ 1.,  2.],
       [ 1.,  2.]])
>>> z = np.ceil(x)
>>> z
array([[ 1.,  3.],
       [ 2.,  3.]])
>>> t = np.floor(x)
>>> t
array([[ 1.,  2.],
       [ 1.,  2.]])
>>> a = np.rint(x)
>>> a
array([[ 1.,  2.],
       [ 1.,  3.]])

To make one of this in to int, or one of the other types in numpy, astype (as answered by BrenBern):

array([[1, 2],
       [1, 3]])

>>> y.astype(int)
array([[1, 2],
       [1, 2]])

Read and write a text file in typescript

First you will need to install node definitions for Typescript. You can find the definitions file here:

Once you've got file, just add the reference to your .ts file like this:

/// <reference path="path/to/node.d.ts" />

Then you can code your typescript class that read/writes, using the Node File System module. Your typescript class myClass.ts can look like this:

/// <reference path="path/to/node.d.ts" />

class MyClass {

    // Here we import the File System module of node
    private fs = require('fs');

    constructor() { }

    createFile() {

        this.fs.writeFile('file.txt', 'I am cool!',  function(err) {
            if (err) {
                return console.error(err);
            console.log("File created!");

    showFile() {

        this.fs.readFile('file.txt', function (err, data) {
            if (err) {
                return console.error(err);
            console.log("Asynchronous read: " + data.toString());

// Usage
// var obj = new MyClass();
// obj.createFile();
// obj.showFile();

Once you transpile your .ts file to a javascript (check out here if you don't know how to do it), you can run your javascript file with node and let the magic work:

> node myClass.js

Using global variables in a function

Following on and as an add on, use a file to contain all global variables all declared locally and then import as:


Stocksin = 300
Prices = []


import initval as iv

def getmystocks(): 
    iv.Stocksin = getstockcount()

def getmycharts():
    for ic in range(iv.Stocksin):

How to upload multiple files using PHP, jQuery and AJAX

Finally I have found the solution by using the following code:

$('body').on('click', '#upload', function(e){
        var formData = new FormData($(this).parents('form')[0]);

            url: 'upload.php',
            type: 'POST',
            xhr: function() {
                var myXhr = $.ajaxSettings.xhr();
                return myXhr;
            success: function (data) {
                alert("Data Uploaded: "+data);
            data: formData,
            cache: false,
            contentType: false,
            processData: false
        return false;

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<AnonymousType#1>' to 'System.Collections.Generic.List<string>

If you have source as a string like "abcd" and want to produce a list like this:

{ "a.a" },
{ "b.b" },
{ "c.c" },
{ "d.d" }

then call:

List<string> list = source.Select(c => String.Concat(c, ".", c)).ToList();

Cross domain POST request is not sending cookie Ajax Jquery

There have been a slew of recent changes in this arena, so I thought a fresh answer would be helpful.

To have a cookie sent by the browser to another site during a request the following criteria must be met:

A lot of people find their way to this post trying to do local development against a remote endpoint, which is possible if the above criteria are met.

Strip double quotes from a string in .NET

s = s.Replace("\"",string.Empty);

Razor View Without Layout

Do you have a _ViewStart.cshtml in this directory? I had the same problem you're having when I tried using _ViewStart. Then I renamed it _mydefaultview, moved it to the Views/Shared directory, and switched to specifying no view in cshtml files where I don't want it, and specifying _mydefaultview for the rest. Don't know why this was necessary, but it worked.

How to convert/parse from String to char in java?

You can do the following:

String str = "abcd";
char arr[] = new char[len]; // len is the length of the array
arr = str.toCharArray();

Getting Database connection in pure JPA setup

Hibernate 4 / 5:

Session session = entityManager.unwrap(Session.class);
session.doWork(connection -> doSomeStuffWith(connection));

LF will be replaced by CRLF in git - What is that and is it important?

If you want, you can deactivate this feature in your git core config using

git config core.autocrlf false

But it would be better to just get rid of the warnings using

git config core.autocrlf true

How do I remove a specific element from a JSONArray?

To Remove some element from Listview in android then it will remove your specific element and Bind it to listview.



How to include Authorization header in cURL POST HTTP Request in PHP?

You have most of the code…

CURLOPT_HTTPHEADER for curl_setopt() takes an array with each header as an element. You have one element with multiple headers.

You also need to add the Authorization header to your $header array.

$header = array();
$header[] = 'Content-length: 0';
$header[] = 'Content-type: application/json';
$header[] = 'Authorization: OAuth SomeHugeOAuthaccess_tokenThatIReceivedAsAString';

Launching an application (.EXE) from C#?


Reverse colormap in matplotlib

In matplotlib a color map isn't a list, but it contains the list of its colors as colormap.colors. And the module matplotlib.colors provides a function ListedColormap() to generate a color map from a list. So you can reverse any color map by doing

colormap_r = ListedColormap(colormap.colors[::-1])

Bring element to front using CSS

In my case i had to move the html code of the element i wanted at the front at the end of the html file, because if one element has z-index and the other doesn't have z index it doesn't work.

Taking inputs with BufferedReader in Java

BufferedReader#read reads single character[0 to 65535 (0x00-0xffff)] from the stream, so it is not possible to read single integer from stream.

            String s= inp.readLine();
            int[] m= new int[2];
            String[] s1 = inp.readLine().split(" ");

            // Checking whether I am taking the inputs correctly

You can check also Scanner vs. BufferedReader.

Filtering a list of strings based on contents

# To support matches from the beginning, not any matches:

items = ['a', 'ab', 'abc', 'bac']
prefix = 'ab'

filter(lambda x: x.startswith(prefix), items)

Stretch child div height to fill parent that has dynamic height

You can do it easily with a bit of jQuery

  var parentHeight = $("#parentDiv").parent().height();

How to use jQuery to show/hide divs based on radio button selection?

An interesting solution is to make this declarative: you just give every div that should be shown an attribute automaticallyVisibleIfIdChecked with the id of the checkbox or radio button on which it depends. That is, your form looks like this:

<form name="form1" id="my_form" method="post" action="">
    <div><label><input type="radio" name="group1" id="rdio1" value="opt1">opt1</label></div>  
    <div><label><input type="radio" name="group1" id="rdio2" value="opt2">opt2</label></div>  
<div id="opt1" automaticallyVisibleIfIdChecked="rdio1">lorem ipsum dolor</div>
<div id="opt2" automaticallyVisibleIfIdChecked="rdio2">consectetur adipisicing</div>

and have some page independent JavaScript that nicely uses functional programming:

function executeAutomaticVisibility(name) {
    $("[name="+name+"]:checked").each(function() {
        $("[automaticallyVisibleIfIdChecked=" +"]").show();
    $("[name="+name+"]:not(:checked)").each(function() {
        $("[automaticallyVisibleIfIdChecked=" +"]").hide();

$(document).ready( function() {
    triggers = $("[automaticallyVisibleIfIdChecked]")
        .map(function(){ return $("#" + $(this).attr("automaticallyVisibleIfIdChecked")).get() })
    triggers.each( function() {
        $(this).change( function(){ executeAutomaticVisibility(; } );

Similarily you could automatically enable / disable form fields with an attribute automaticallyEnabledIfChecked.

I think this method is nice since it avoids having to create specific JavaScript for your page - you just insert some attributes that say what should be done.

How do I align a label and a textarea?

You need to put them both in some container element and then apply the alignment on it.

For example:

.formfield * {_x000D_
  vertical-align: middle;_x000D_
<p class="formfield">_x000D_
  <label for="textarea">Label for textarea</label>_x000D_
  <textarea id="textarea" rows="5">Textarea</textarea>_x000D_