Programs & Examples On #Branching and merging

In version control, branches represent parallel lines of development. Merging is the action that integrates changes made in different branches.

How do I copy a version of a single file from one git branch to another?

Following madlep's answer you can also just copy one directory from another branch with the directory blob.

git checkout other-branch app/**

As to the op's question if you've only changed one file in there this will work fine ^_^

How to copy commits from one branch to another?

The cherry-pick command can read the list of commits from the standard input.

The following command cherry-picks commits authored by the user John that exist in the "develop" branch but not in the "release" branch, and does so in the chronological order.

git log develop --not release --format=%H --reverse --author John | git cherry-pick --stdin

Deleting an SVN branch

You can also delete the branch on the remote directly. Having done that, the next update will remove it from your working copy.

svn rm "^/reponame/branches/name_of_branch" -m "cleaning up old branch name_of_branch"

The ^ is short for the URL of the remote, as seen in 'svn info'. The double quotes are necessary on Windows command line, because ^ is a special character.

This command will also work if you have never checked out the branch.

What I can do to resolve "1 commit behind master"?

If your branch is behind by master then do:

git checkout master (you are switching your branch to master)
git pull 
git checkout yourBranch (switch back to your branch)
git merge master

After merging it, check if there is a conflict or not.
If there is NO CONFLICT then:

git push

If there is a conflict then fix your file(s), then:

git add yourFile(s)
git commit -m 'updating my branch'
git push

What is the best (and safest) way to merge a Git branch into master?

I always get merge conflicts when doing just git merge feature-branch. This seems to work for me:

git checkout -b feature-branch

Do a bunch of code changes...

git merge -s ours master 
git checkout master
git merge feature-branch


git checkout -b feature-branch

Do a bunch of code changes...

git checkout master
git merge -X theirs feature-branch

How to resolve git's "not something we can merge" error

I had this issue as well. The branch looked like 'username/master' which seemed to confuse git as it looked like a remote address I defined. For me using this

git merge origin/username/master

worked perfectly fine.

Remove large .pack file created by git

Run the following command, replacing PATH-TO-YOUR-FILE-WITH-SENSITIVE-DATA with the path to the file you want to remove, not just its filename. These arguments will:

  1. Force Git to process, but not check out, the entire history of every branch and tag
  2. Remove the specified file, as well as any empty commits generated as a result
  3. Overwrite your existing tags
git filter-branch --force --index-filter "git rm --cached --ignore-unmatch PATH-TO-YOUR-FILE-WITH-SENSITIVE-DATA" --prune-empty --tag-name-filter cat -- --all

This will forcefully remove all references to the files from the active history of the repo.

Next step, to perform a GC cycle to force all references to the file to be expired and purged from the pack file. Nothing needs to be replaced in these commands.

git update-ref -d refs/original/refs/remotes/origin/master
git for-each-ref --format='delete %(refname)' refs/original | git update-ref --stdin
git reflog expire --expire=now --all
git gc --aggressive --prune=now

Move the most recent commit(s) to a new branch with Git

Yet another way to do this, using just 2 commands. Also keeps your current working tree intact.

git checkout -b newbranch # switch to a new branch
git branch -f master HEAD~3 # make master point to some older commit

Old version - before I learned about git branch -f

git checkout -b newbranch # switch to a new branch
git push . +HEAD~3:master # make master point to some older commit 

Being able to push to . is a nice trick to know.

How do I create a branch?

  • Create a new folder outside of your current project. You can give it any name. (Example: You have a checkout for a project named "Customization". And it has many projects, like "Project1", "Project2"....And you want to create a branch of "Project1". So first open the "Customization", right click and create a new folder and give it a name, "Project1Branch").
  • Right click on "Myproject1"....TortoiseSVN -> Branch/Tag.
  • Choose working copy.
  • Open browser....Just right of parallel on "To URL".
  • Select customization.....right click then Add Folder. and go through the folder which you have created. Here it is "Project1Branch". Now clik the OK button to add.
  • Take checkout of this new banch.
  • Again go to your project which branch you want to create. Right click TorotoiseSVN -> branch/tag. Then select working copy. And you can give the URL as your branch name. like {your IP address/svn/AAAA/Customization/Project1Branch}. And you can set the name in the URL so it will create the folder with this name only. Like {Your IP address/svn/AAAA/Customization/Project1Branch/MyProject1Branch}.
  • Press the OK button. Now you can see the logs in ...your working copy will be stored in your branch.
  • Now you can take a check out...and let you enjoy your work. :)

"Cannot allocate an object of abstract type" error

In C++ a class with at least one pure virtual function is called abstract class. You can not create objects of that class, but may only have pointers or references to it.

If you are deriving from an abstract class, then make sure you override and define all pure virtual functions for your class.

From your snippet Your class AliceUniversity seems to be an abstract class. It needs to override and define all the pure virtual functions of the classes Graduate and UniversityGraduate.

Pure virtual functions are the ones with = 0; at the end of declaration.

Example: virtual void doSomething() = 0;

For a specific answer, you will need to post the definition of the class for which you get the error and the classes from which that class is deriving.

Convert data.frame column format from character to factor

I've doing it with a function. In this case I will only transform character variables to factor:

for (i in 1:ncol(data)){

How to convert a byte to its binary string representation

This code will demonstrate how a java int can be split up into its 4 consecutive bytes. We can then inspect each byte using Java methods compared to low level byte / bit interrogation.

This is the expected output when you run the code below:

[Input] Integer value: 8549658

Integer.toBinaryString: 100000100111010100011010
Integer.toHexString: 82751a
Integer.bitCount: 10

Byte 4th Hex Str: 0
Byte 3rd Hex Str: 820000
Byte 2nd Hex Str: 7500
Byte 1st Hex Str: 1a

(1st + 2nd + 3rd + 4th (int(s)) as Integer.toHexString: 82751a
(1st + 2nd + 3rd + 4th (int(s)) ==  Integer.toHexString): true

Individual bits for each byte in a 4 byte int:
00000000 10000010 01110101 00011010

Here is the code to run:

public class BitsSetCount
    public static void main(String[] args) 
        int send = 8549658;

        System.out.println( "[Input] Integer value: " + send + "\n" );
        BitsSetCount.countBits(  send );

    private static void countBits(int i) 
        System.out.println( "Integer.toBinaryString: " + Integer.toBinaryString(i) );
        System.out.println( "Integer.toHexString: " + Integer.toHexString(i) );
        System.out.println( "Integer.bitCount: "+ Integer.bitCount(i) );

        int d = i & 0xff000000;
        int c = i & 0xff0000;
        int b = i & 0xff00;
        int a = i & 0xff;

        System.out.println( "\nByte 4th Hex Str: " + Integer.toHexString(d) );
        System.out.println( "Byte 3rd Hex Str: " + Integer.toHexString(c) );
        System.out.println( "Byte 2nd Hex Str: " + Integer.toHexString(b) );
        System.out.println( "Byte 1st Hex Str: " + Integer.toHexString(a) );

        int all = a+b+c+d;
        System.out.println( "\n(1st + 2nd + 3rd + 4th (int(s)) as Integer.toHexString: " + Integer.toHexString(all) );

        System.out.println("(1st + 2nd + 3rd + 4th (int(s)) ==  Integer.toHexString): " + 
                Integer.toHexString(all).equals(Integer.toHexString(i) ) );

        System.out.println( "\nIndividual bits for each byte in a 4 byte int:");

         * Because we are sending the MSF bytes to a method
         * which will work on a single byte and print some
         * bits we are generalising the MSF bytes
         * by making them all the same in terms of their position
         * purely for the purpose of printing or analysis
                    getBits( (byte) (d >> 24) ) + " " + 
                    getBits( (byte) (c >> 16) ) + " " + 
                    getBits( (byte) (b >> 8) ) + " " + 
                    getBits( (byte) (a >> 0) ) 


    private static String getBits( byte inByte )
        // Go through each bit with a mask
        StringBuilder builder = new StringBuilder();
        for ( int j = 0; j < 8; j++ )
            // Shift each bit by 1 starting at zero shift
            byte tmp =  (byte) ( inByte >> j );

            // Check byte with mask 00000001 for LSB
            int expect1 = tmp & 0x01; 

        return ( builder.reverse().toString() );


Most pythonic way to delete a file which may not exist

A KISS offering:

def remove_if_exists(filename):
  if os.path.exists(filename):

And then:


Python: Get the first character of the first string in a list?

Indexing in python starting from 0. You wrote [1:] this would not return you a first char in any case - this will return you a rest(except first char) of string.

If you have the following structure:

mylist = ['base', 'sample', 'test']

And want to get fist char for the first one string(item):

>>> b

If all first chars:

[x[0] for x in myList]
>>> ['b', 's', 't']    

If you have a text:

text = 'base sample test'
>>> b

jQuery javascript regex Replace <br> with \n

myString.replace(/<br ?\/?>/g, "\n")

php_network_getaddresses: getaddrinfo failed: Name or service not known

in simple word your site has been blocked to access network. may be you have automated some script and it caused your whole website to be blocked. the better way to resolve this is contact that site and tell your issue. if issue is genuine they may consider unblocking

How do I convert a byte array to Base64 in Java?

Java 8+

Encode or decode byte arrays:

byte[] encoded = Base64.getEncoder().encode("Hello".getBytes());
println(new String(encoded));   // Outputs "SGVsbG8="

byte[] decoded = Base64.getDecoder().decode(encoded);
println(new String(decoded))    // Outputs "Hello"

Or if you just want the strings:

String encoded = Base64.getEncoder().encodeToString("Hello".getBytes());
println(encoded);   // Outputs "SGVsbG8="

String decoded = new String(Base64.getDecoder().decode(encoded.getBytes()));
println(decoded)    // Outputs "Hello"

For more info, see Base64.

Java < 8

Base64 is not bundled with Java versions less than 8. I recommend using Apache Commons Codec.

For direct byte arrays:

Base64 codec = new Base64();
byte[] encoded = codec.encode("Hello".getBytes());
println(new String(encoded));   // Outputs "SGVsbG8="

byte[] decoded = codec.decode(encoded);
println(new String(decoded))    // Outputs "Hello"

Or if you just want the strings:

Base64 codec = new Base64();
String encoded = codec.encodeBase64String("Hello".getBytes());
println(encoded);   // Outputs "SGVsbG8="

String decoded = new String(codec.decodeBase64(encoded));
println(decoded)    // Outputs "Hello"


If you're working in a Spring project already, you may find their org.springframework.util.Base64Utils class more ergonomic:

For direct byte arrays:

byte[] encoded = Base64Utils.encode("Hello".getBytes());
println(new String(encoded))    // Outputs "SGVsbG8="

byte[] decoded = Base64Utils.decode(encoded);
println(new String(decoded))    // Outputs "Hello"

Or if you just want the strings:

String encoded = Base64Utils.encodeToString("Hello".getBytes());
println(encoded);   // Outputs "SGVsbG8="

String decoded = Base64Utils.decodeFromString(encoded);
println(new String(decoded))    // Outputs "Hello"

Android (with Java < 8)

If you are using the Android SDK before Java 8 then your best option is to use the bundled android.util.Base64.

For direct byte arrays:

byte[] encoded = Base64.encode("Hello".getBytes());
println(new String(encoded))    // Outputs "SGVsbG8="

byte [] decoded = Base64.decode(encoded);
println(new String(decoded))    // Outputs "Hello"

Or if you just want the strings:

String encoded = Base64.encodeToString("Hello".getBytes());
println(encoded);   // Outputs "SGVsbG8="

String decoded = new String(Base64.decode(encoded));
println(decoded)    // Outputs "Hello"

The developers of this app have not set up this app properly for Facebook Login?

enter image description here

enter image description here

enter image description here

Make Sure in left panel App review tab selected (Your app is currently live and available to the public.) tab is ON and App status is GREEN

Happy Programming

Seconds CountDown Timer

Hey please add code in your project,it is easy and i think will solve your problem.

    int count = 10;

    private void timer1_Tick(object sender, EventArgs e)
        if (count != 0 && count > 0)
            label1.Text = count / 60 + ":" + ((count % 60) >= 10 ? (count % 60).ToString() : "0" + (count % 60));
            label1.Text = "game over";



    private void Form1_Load(object sender, EventArgs e)
        timer1 = new System.Windows.Forms.Timer();
        timer1.Interval = 1;

        timer1.Tick += new EventHandler(timer1_Tick);


fork() and wait() with two child processes

brilliant example Jonathan Leffler, to make your code work on SLES, I needed to add an additional header to allow the pid_t object :)

#include <sys/types.h>

JSP tricks to make templating easier?

I made quite easy, Django style JSP Template inheritance tag library.

I think it make easy to manage layouts without learning curve.

example code :

base.jsp : layout

<%@page contentType="text/html; charset=UTF-8" %>
<%@ taglib uri="" prefix="layout"%>
<!DOCTYPE html>
<html lang="en">
        <title>JSP Template Inheritance</title>

    <layout:block name="header">

    <layout:block name="contents">
        <h2>Contents will be placed under this h2</h2>

<div class="footer">
    <hr />
    <a href="">jsp template inheritance example</a>

view.jsp : contents

<%@page contentType="text/html; charset=UTF-8" %>
<%@ taglib uri="" prefix="layout"%>
<layout:extends name="base.jsp">
    <layout:put name="header" type="REPLACE">
        <h2>This is an example about layout management with JSP Template Inheritance</h2>
    <layout:put name="contents">
        Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin porta,
        augue ut ornare sagittis, diam libero facilisis augue, quis accumsan enim velit a mauris.

Parse String to Date with Different Format in Java

Use the SimpleDateFormat class:

private Date parseDate(String date, String format) throws ParseException
    SimpleDateFormat formatter = new SimpleDateFormat(format);
    return formatter.parse(date);


Date date = parseDate("19/05/2009", "dd/MM/yyyy");

For efficiency, you would want to store your formatters in a hashmap. The hashmap is a static member of your util class.

private static Map<String, SimpleDateFormat> hashFormatters = new HashMap<String, SimpleDateFormat>();

public static Date parseDate(String date, String format) throws ParseException
    SimpleDateFormat formatter = hashFormatters.get(format);

    if (formatter == null)
        formatter = new SimpleDateFormat(format);
        hashFormatters.put(format, formatter);

    return formatter.parse(date);

Filtering a list based on a list of booleans

filtered_list = [list_a[i] for i in range(len(list_a)) if filter[i]]

Delete directory with files in it?

I do not remember from where I copied this function, but it looks like it is not listed and it is working for me

function rm_rf($path) {
    if (@is_dir($path) && is_writable($path)) {
        $dp = opendir($path);
        while ($ent = readdir($dp)) {
            if ($ent == '.' || $ent == '..') {
            $file = $path . DIRECTORY_SEPARATOR . $ent;
            if (@is_dir($file)) {
            } elseif (is_writable($file)) {
            } else {
                echo $file . "is not writable and cannot be removed. Please fix the permission or select a new path.\n";
        return rmdir($path);
    } else {
        return @unlink($path);

No mapping found for HTTP request with URI [/WEB-INF/pages/apiForm.jsp]

I have encountered this problem in Eclipse Luna EE. My solution was simply restart eclipse and it magically started loading servlet properly.

Format date to MM/dd/yyyy in JavaScript

All other answers don't quite solve the issue. They print the date formatted as mm/dd/yyyy but the question was regarding MM/dd/yyyy. Notice the subtle difference? MM indicates that a leading zero must pad the month if the month is a single digit, thus having it always be a double digit number.

i.e. whereas mm/dd would be 3/31, MM/dd would be 03/31.

I've created a simple function to achieve this. Notice that the same padding is applied not only to the month but also to the day of the month, which in fact makes this MM/DD/yyyy:

function getFormattedDate(date) {_x000D_
  var year = date.getFullYear();_x000D_
  var month = (1 + date.getMonth()).toString();_x000D_
  month = month.length > 1 ? month : '0' + month;_x000D_
  var day = date.getDate().toString();_x000D_
  day = day.length > 1 ? day : '0' + day;_x000D_
  return month + '/' + day + '/' + year;_x000D_

Update for ES2017 using String.padStart(), supported by all major browsers except IE.

function getFormattedDate(date) {_x000D_
    let year = date.getFullYear();_x000D_
    let month = (1 + date.getMonth()).toString().padStart(2, '0');_x000D_
    let day = date.getDate().toString().padStart(2, '0');_x000D_
    return month + '/' + day + '/' + year;_x000D_

How to write Unicode characters to the console?

I found some elegant solution on MSDN

System.Console.Write('\uXXXX') //XXXX is hex Unicode for character

This simple program writes ? right on the screen.

using System;

public class Test
    public static void Main()
        Console.Write('\u2103'); //? character code

VS2010 command prompt gives error: Cannot determine the location of the VS Common Tools folder

I had same problem with Visual Studio 2010 on Windows XP. Just remove all constructions:

> nul 2>&1

from files:

\Microsoft Visual Studio 10.0\VC\bin\vcvars32.bat
\Microsoft Visual Studio 10.0\Common7\Tools\VCVarsQueryRegistry.bat

Left Outer Join using + sign in Oracle 11g

TableA LEFT OUTER JOIN TableB is equivalent to TableB RIGHT OUTER JOIN Table A.

In Oracle, (+) denotes the "optional" table in the JOIN. So in your first query, it's a P LEFT OUTER JOIN S. In your second query, it's S RIGHT OUTER JOIN P. They're functionally equivalent.

In the terminology, RIGHT or LEFT specify which side of the join always has a record, and the other side might be null. So in a P LEFT OUTER JOIN S, P will always have a record because it's on the LEFT, but S could be null.

See this example from for additional explanation.

To clarify, I guess I'm saying that terminology doesn't matter, as it's only there to help visualize. What matters is that you understand the concept of how it works.


I've seen some confusion about what matters in determining RIGHT vs LEFT in implicit join syntax.


WHERE A.column = B.column(+)


WHERE B.column(+) = A.column

All I did is swap sides of the terms in the WHERE clause, but they're still functionally equivalent. (See higher up in my answer for more info about that.) The placement of the (+) determines RIGHT or LEFT. (Specifically, if the (+) is on the right, it's a LEFT JOIN. If (+) is on the left, it's a RIGHT JOIN.)

Types of JOIN

The two styles of JOIN are implicit JOINs and explicit JOINs. They are different styles of writing JOINs, but they are functionally equivalent.

See this SO question.

Implicit JOINs simply list all tables together. The join conditions are specified in a WHERE clause.

Implicit JOIN

WHERE A.column = B.column(+)

Explicit JOINs associate join conditions with a specific table's inclusion instead of in a WHERE clause.

Explicit JOIN

LEFT OUTER JOIN B ON A.column = B.column

These Implicit JOINs can be more difficult to read and comprehend, and they also have a few limitations since the join conditions are mixed in other WHERE conditions. As such, implicit JOINs are generally recommended against in favor of explicit syntax.

How can you customize the numbers in an ordered list?

I will give here the kind of answer i usually don't like to read, but i think that as there are other answers telling you how to achive what you want, it could be nice to rethink if what you are trying to achive is really a good idea.

First, you should think if it is a good idea to show the items in a non-standard way, with a separator charater diferent than the provided.

I don't know the reasons for that, but let's suppose you have good reasons.

The ways propossed here to achive that consist in add content to your markup, mainly trough the CSS :before pseudoclass. This content is really modifing your DOM structure, adding those items to it.

When you use standard "ol" numeration, you will have a rendered content in which the "li" text is selectable, but the number preceding it is not selectable. That is, the standard numbering system seems to be more "decoration" than real content. If you add content for numbers using for example those ":before" methods, this content will be selectable, and dued to this, performing undesired vopy/paste issues, or accesibility issues with screen readers that will read this "new" content in addition to the standard numeration system.

Perhaps another approach could be to style the numbers using images, although this alternative will bring its own problems (numbers not shown when images are disabled, text size for number not changing, ...).

Anyway, the reason for this answer is not just to propose this "images" alternative, but to make people think in the consequences of trying to change the standard numeration system for ordered lists.

Regular expression - starting and ending with a letter, accepting only letters, numbers and _

I'll take a stab at it:



 ^           # match beginning of string
 [a-z]       # match a letter for the first char
 (?:         # start non-capture group
   _?          # match 0 or 1 '_'
   [a-z0-9]+   # match a letter or number, 1 or more times
 )*          # end non-capture group, match whole group 0 or more times
 $           # match end of string
/i           # case insensitive flag

The non-capture group takes care of a) not allowing two _'s (it forces at least one letter or number per group) and b) only allowing the last char to be a letter or number.

Some test strings:

"a": match
"_": fail
"zz": match
"a0": match
"A_": fail
"a0_b": match
"a__b": fail
"a_1_c": match

make: Nothing to be done for `all'

Remove the hello file from your folder and try again.

The all target depends on the hello target. The hello target first tries to find the corresponding file in the filesystem. If it finds it and it is up to date with the dependent files—there is nothing to do.

Using Ansible set_fact to create a dictionary from register results

Thank you Phil for your solution; in case someone ever gets in the same situation as me, here is a (more complex) variant:

# this is just to avoid a call to |default on each iteration
- set_fact:
    postconf_d: {}

- name: 'get postfix default configuration'
  command: 'postconf -d'
  register: command

# the answer of the command give a list of lines such as:
# "key = value" or "key =" when the value is null
- name: 'set postfix default configuration as fact'
    postconf_d: >
        postconf_d |
          dict([ item.partition('=')[::2]|map('trim') ])
  with_items: command.stdout_lines

This will give the following output (stripped for the example):

"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": "hash:/etc/aliases, nis:mail.aliases",
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"

Going even further, parse the lists in the 'value':

- name: 'set postfix default configuration as fact'
    postconf_d: >-
      {% set key, val = item.partition('=')[::2]|map('trim') -%}
      {% if ',' in val -%}
        {% set val = val.split(',')|map('trim')|list -%}
      {% endif -%}
      {{ postfix_default_main_cf | combine({key: val}) }}
  with_items: command.stdout_lines
"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": [
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"

A few things to notice:

  • in this case it's needed to "trim" everything (using the >- in YAML and -%} in Jinja), otherwise you'll get an error like:

    FAILED! => {"failed": true, "msg": "|combine expects dictionaries, got u\"  {u'...
  • obviously the {% if .. is far from bullet-proof

  • in the postfix case, val.split(',')|map('trim')|list could have been simplified to val.split(', '), but I wanted to point out the fact you will need to |list otherwise you'll get an error like:

    "|combine expects dictionaries, got u\"{u'...': <generator object do_map at ...

Hope this can help.

Sort hash by key, return hash in Ruby

You gave the best answer to yourself in the OP: Hash[h.sort] If you crave for more possibilities, here is in-place modification of the original hash to make it sorted:

h.keys.sort.each { |k| h[k] = h.delete k }

Getting value GET OR POST variable using JavaScript?

Here is my answer for this given a string returnURL which is like It's fairly basic as I'm beginning at JavaScript (this is actually part of my first program ever in JS), and making it simpler to understand rather than tricky.


  • No sanity checking of values
  • Just outputting to the console - you'll want to store them in an array or something
  • this is only for GET, and not POST

    var paramindex = returnURL.indexOf('?');
    if (paramindex > 0) {
        var paramstring = returnURL.split('?')[1];
        while (paramindex > 0) {
            paramindex = paramstring.indexOf('=');
            if (paramindex > 0) {
                var parkey = paramstring.substr(0,paramindex);
                paramstring = paramstring.substr(paramindex+1) // +1 to strip out the =
            paramindex = paramstring.indexOf('&');
            if (paramindex > 0) {
                var parvalue = paramstring.substr(0,paramindex);
                paramstring = paramstring.substr(paramindex+1) // +1 to strip out the &
            } else { // we're at the end of the URL
                var parvalue = paramstring

How to show image using ImageView in Android

If you want to display an image file on the phone, you can do this:

private ImageView mImageView;
mImageView = (ImageView) findViewById(;

If you want to display an image from your drawable resources, do this:

private ImageView mImageView;
mImageView = (ImageView) findViewById(;

You'll find the drawable folder(s) in the project res folder. You can put your image files there.

What is the "right" JSON date format?

JSON itself has no date format, it does not care how anyone stores dates. However, since this question is tagged with javascript, I assume you want to know how to store javascript dates in JSON. You can just pass in a date to the JSON.stringify method, and it will use Date.prototype.toJSON by default, which in turns uses Date.prototype.toISOString (MDN on Date.toJSON):

const json = JSON.stringify(new Date());
const parsed = JSON.parse(json); //2015-10-26T07:46:36.611Z
const date = new Date(parsed); // Back to date object

I also found it useful to use the reviver parameter of JSON.parse (MDN on JSON.parse) to automatically convert ISO strings back to javascript dates whenever I read JSON strings.

const isoDatePattern = new RegExp(/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z)/);

const obj = {
 a: 'foo',
 b: new Date(1500000000000) // Fri Jul 14 2017, etc...
const json = JSON.stringify(obj);

// Convert back, use reviver function:
const parsed = JSON.parse(json, (key, value) => {
    if (typeof value === 'string' &&  value.match(isoDatePattern)){
        return new Date(value); // isostring, so cast to js date
    return value; // leave any other value as-is
console.log(parsed.b); // // Fri Jul 14 2017, etc...

C# Listbox Item Double Click Event

void listBox1_MouseDoubleClick(object sender, MouseEventArgs e)
    int index = this.listBox1.IndexFromPoint(e.Location);
    if (index != System.Windows.Forms.ListBox.NoMatches)

This should work...check

Is there a way to have printf() properly print out an array (of floats, say)?

You need to go for a loop:

for (int i = 0; i < sizeof(foo) / sizeof(float); ++i)
   printf("%f", foo[i]);

How can I tell if I'm running in 64-bit JVM or 32-bit JVM (from within a program)?

Under Windows 7 in the "Control Panel" under "Programs | Programs and Features" the 64-bit variants of JRE & JDK are listed with "64-bit" in parentheses (e.g. "Java SE Development Kit 7 Update 65 (64-Bit)"), while for the 32-bit variants the variant is not mentioned in parentheses (e.g. just "Java SE Development Kit 8 Update 60").

Smart cast to 'Type' is impossible, because 'variable' is a mutable property that could have been changed by this time

Do this:

var left: Node? = null

fun show() {
     val left = left
     if (left != null) {
         queue.add(left) // safe cast succeeds

Which seems to be the first option provided by the accepted answer, but that's what you're looking for.

How should I declare default values for instance variables in Python?

You can also declare class variables as None which will prevent propagation. This is useful when you need a well defined class and want to prevent AttributeErrors. For example:

>>> class TestClass(object):
...     t = None
>>> test = TestClass()
>>> test.t
>>> test2 = TestClass()
>>> test.t = 'test'
>>> test.t
>>> test2.t

Also if you need defaults:

>>> class TestClassDefaults(object):
...    t = None
...    def __init__(self, t=None):
...       self.t = t
>>> test = TestClassDefaults()
>>> test.t
>>> test2 = TestClassDefaults([])
>>> test2.t
>>> test.t

Of course still follow the info in the other answers about using mutable vs immutable types as the default in __init__.

ElasticSearch: Unassigned Shards, how to fix?

I was having this issue as well, and I found an easy way to resolve it.

  • Get the index of unassigned shards

    $ curl -XGET
  • Install curator Tools, and use it to delete index

    $ curator --host delete indices --older-than 1 \
           --timestring '%Y.%m.%d' --time-unit days --prefix logstash

    NOTE: In my case, the index is logstash of the day 2016-04-21

  • Then check the shards again, all the unassigned shards go away!

Difference between one-to-many and many-to-one relationship

From this page about Database Terminology

Most relations between tables are one-to-many.


  • One area can be the habitat of many readers.
  • One reader can have many subscriptions.
  • One newspaper can have many subscriptions.

A Many to One relation is the same as one-to-many, but from a different viewpoint.

  • Many readers live in one area.
  • Many subscriptions can be of one and the same reader.
  • Many subscriptions are for one and the same newspaper.

How to create string with multiple spaces in JavaScript

Use &nbsp;

It is the entity used to represent a non-breaking space. It is essentially a standard space, the primary difference being that a browser should not break (or wrap) a line of text at the point that this   occupies.

var a = 'something' + '&nbsp &nbsp &nbsp &nbsp &nbsp' + 'something'

Non-breaking Space

A common character entity used in HTML is the non-breaking space (&nbsp;).

Remember that browsers will always truncate spaces in HTML pages. If you write 10 spaces in your text, the browser will remove 9 of them. To add real spaces to your text, you can use the &nbsp; character entity.


var a = 'something' + '&nbsp &nbsp &nbsp &nbsp &nbsp' + 'something';_x000D_
document.body.innerHTML = a;

Numpy matrix to array

You can try the following variant:


What does the keyword "transient" mean in Java?

Google is your friend - first hit - also you might first have a look at what serialization is.

It marks a member variable not to be serialized when it is persisted to streams of bytes. When an object is transferred through the network, the object needs to be 'serialized'. Serialization converts the object state to serial bytes. Those bytes are sent over the network and the object is recreated from those bytes. Member variables marked by the java transient keyword are not transferred, they are lost intentionally.

Example from there, slightly modified (thanks @pgras):

public class Foo implements Serializable
   private String saveMe;
   private transient String dontSaveMe;
   private transient String password;

Set focus on textbox in WPF

try FocusManager.SetFocusedElement

FocusManager.SetFocusedElement(parentElement, txtCompanyID)

Use grep to report back only line numbers

Bash version

    lineno=$(grep -n "pattern" filename)

Where does VBA Debug.Print log to?

Debug.Print outputs to the "Immediate" window.

Debug.Print outputs to the Immediate window

Also, you can simply type ? and then a statement directly into the immediate window (and then press Enter) and have the output appear right below, like this:

simply type ? and then a statement directly into the immediate window

This can be very handy to quickly output the property of an object...

? set the property of an object... = "thingy"

...or to even execute a function or line of code, while in debugging mode:


How to change proxy settings in Android (especially in Chrome)

Found one solution for WIFI (works for Android 4.3, 4.4):

  1. Connect to WIFI network (e.g. 'Alex')
  2. Settings->WIFI
  3. Long tap on connected network's name (e.g. on 'Alex')
  4. Modify network config-> Show advanced options
  5. Set proxy settings

Excel VBA Check if directory exists error

You can replace WB_parentfolder with something like "C:\". For me WB_parentfolder is grabbing the location of the current workbook. file_des_folder is the new folder i want. This goes through and creates as many folders as you need.

        folder1 = Left(file_des_folder, InStr(Len(WB_parentfolder) + 1, file_loc, "\"))
        Do While folder1 <> file_des_folder
            folder1 = Left(file_des_folder, InStr(Len(folder1) + 1, file_loc, "\"))
            If Dir(file_des_folder, vbDirectory) = "" Then      'create folder if there is not one
                MkDir folder1
            End If

Oracle SQL Developer and PostgreSQL

Oracle SQL Developer 2020-02 support PostgreSQL, but it is just the basics by adding postgreSQL driver under jdbc dir and configure by adding as a 3rd party driver.

The supported functionality:

  • multiple databases which can be selected at connection definition
  • CRUD operations like query tables
  • scheme operations
  • basic modelling support: show tables without pk, fk, connections

Not supported functionalities:

  • no table or field completion
  • no indexes are shown in a tab
  • no constraints are shown in a tab like: fk, pk-s, unique, or others
  • no table or field completions in the editor
  • no functions, packages,triggers, views are shown

The sad thing is Oracle should only change the queries behind this view in case of PostgreSql connections. For example for indexes they need to use this query: select * from pg_catalog.pg_indexes;

Remove all stylings (border, glow) from textarea

try this:

textarea {
        border-style: none;
        border-color: Transparent;
        overflow: auto;
        outline: none;


How do I move a redis database from one server to another?

redis-dump finally worked for me. Its documentation provides an example how to dump a Redis database and insert the data into another one.

Found shared references to a collection org.hibernate.HibernateException

In a one to many and many to one relationship this error will occur. If you attempt to devote same instance from many to one entity to more than one instance from one to many entity.

For example, each person can have many books but each of these books can be owned by only one person if you consider more than one owner for a book this issue is raised.

C++ floating point to integer type conversions

One thing I want to add. Sometimes, there can be precision loss. You may want to add some epsilon value first before converting. Not sure why that works... but it work.

int someint = (somedouble+epsilon);

Laravel Fluent Query Builder Join with subquery

You can use following addon to handle all subquery related function from laravel 5.5+

  Comment::selectRaw('user_id,count(*) total_count')
  //closure for "on" statement
  function ($join) {
      $join->on('', '=', 'comments_by_user.user_id');

Python extending with - using super() Python 3 vs Python 2

In short, they are equivalent. Let's have a history view:

(1) at first, the function looks like this.

    class MySubClass(MySuperClass):
        def __init__(self):

(2) to make code more abstract (and more portable). A common method to get Super-Class is invented like:

    super(<class>, <instance>)

And init function can be:

    class MySubClassBetter(MySuperClass):
        def __init__(self):
            super(MySubClassBetter, self).__init__()

However requiring an explicit passing of both the class and instance break the DRY (Don't Repeat Yourself) rule a bit.

(3) in V3. It is more smart,


is enough in most case. You can refer to

Using "like" wildcard in prepared statement

Code it like this:

PreparedStatement pstmt = con.prepareStatement(
    "SELECT * FROM analysis WHERE notes like ?");
pstmt.setString(1, notes + "%");`

Make sure that you DO NOT include the quotes ' ' like below as they will cause an exception.

pstmt.setString(1,"'%"+ notes + "%'");

SQL Server convert select a column and convert it to a string

You can use the following method:

        select ', ' + CONVERT(varchar(10), ID) FROM @temp
        where ID<50
group by ID for xml path('')
        ), 1, 2, '') as IDs


Declare @temp Table(
ID int
insert into @temp
insert into @temp
insert into @temp
insert into @temp

        select ', ' + CONVERT(varchar(10), ID) FROM @temp
        where ID<50
group by ID for xml path('')
        ), 1, 2, '') as IDs

Result will be:

enter image description here

How to set time to 24 hour format in Calendar

use SimpleDateFormat df = new SimpleDateFormat("HH:mm"); instead


@Ingo is right. is's better use setTime(d1);

first method getHours() and getMinutes() is now deprecated

I test this code

SimpleDateFormat df = new SimpleDateFormat("hh:mm");
  Date d1 = df.parse("23:30");
  Calendar c1 = GregorianCalendar.getInstance();

and output is ok Thu Jan 01 23:30:00 FET 1970

try this

SimpleDateFormat df = new SimpleDateFormat("KK:mm aa");
  Date d1 = df.parse("10:30 PM");
  Calendar c1 = GregorianCalendar.getInstance(Locale.US);
  SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");  
  String str = sdf.format(c1.getTime());

Windows Forms - Enter keypress activates submit button?

If you set your Form's AcceptButton property to one of the Buttons on the Form, you'll get that behaviour by default.

Otherwise, set the KeyPreview property to true on the Form and handle its KeyDown event. You can check for the Enter key and take the necessary action.

Compilation error - missing zlib.h

You are missing zlib.h header file, on Linux install it via:

sudo apt-get install libz-dev

As a matter of fact, the module presents as zlib1g-dev in the apt repo, so this is the up-to-date call (Feb 2019):

sudo apt install zlib1g-dev

On Fedora: sudo dnf install zlib-devel (in older versions: sudo dnf install libz-devel).

This will provide the development support files for a library implementing the deflate compression method found in gzip and PKZIP.

If you've already zlib library, make sure you're compiling your code sources with -lz. See: How to fix undefined references to inflate/deflate functions?.

github changes not staged for commit

I tried everything suggested on whole Stackoverflow. Nothing including -a or -am or anything helped.

If you are the same, do this.

So, the problem is, git thinks some of your subdirectory is sub-project in your root-project. At least, in my case it wasn't like that. It was just regular sub-directory. Not individual project.

Move that regular sub-directory which is not being pushed at some temporary location.

Remove the hidden .git folder from that directory.

cd to the root directory.

git init again.

git add . again.

git commit -m "removed notPushableDirectory temporarily"

git push -f origin master

We will have to force it as the git will see the conflict between remote git and your local structure. Remember, we created this conflict. So, don't worry about forcing it.

Now, it will push that sub-directory as sub-directory and not as sub-module or sub-project inside your root-project.

Round up value to nearest whole number in SQL UPDATE

You could use the ceiling function; this portion of SQL code :

select ceiling(45.01), ceiling(45.49), ceiling(45.99);

will get you "46" each time.

For your update, so, I'd say :

Update product SET price = ceiling(45.01)

BTW : On MySQL, ceil is an alias to ceiling ; not sure about other DB systems, so you might have to use one or the other, depending on the DB you are using...

Quoting the documentation :


Returns the smallest integer value not less than X.

And the given example :

mysql> SELECT CEILING(1.23);
        -> 2
mysql> SELECT CEILING(-1.23);
        -> -1

Can I change a column from NOT NULL to NULL without dropping it?


where {DataType} is the current data type of that column (For example int or varchar(10))

How to call gesture tap on UIView programmatically in swift

STEP : 1

@IBOutlet var viewTap: UIView!

STEP : 2

var tapGesture = UITapGestureRecognizer()

STEP : 3

override func viewDidLoad() {
    // TAP Gesture
    tapGesture = UITapGestureRecognizer(target: self, action: #selector(ViewController.myviewTapped(_:)))
    tapGesture.numberOfTapsRequired = 1
    tapGesture.numberOfTouchesRequired = 1
    viewTap.isUserInteractionEnabled = true

STEP : 4

func myviewTapped(_ sender: UITapGestureRecognizer) {

    if self.viewTap.backgroundColor == UIColor.yellow {
        self.viewTap.backgroundColor =
        self.viewTap.backgroundColor = UIColor.yellow


enter image description here

No provider for Http StaticInjectorError

In ionic 4.6 I use the following technique and it works. I am adding this answer so that if anybody is facing similar issues in newer ionic version app, it may help them.

i) Open app.module.ts and add the following code block to import HttpModule and HttpClientModule

import { HttpModule } from '@angular/http';
import {   HttpClientModule } from '@angular/common/http';

ii) In @NgModule import sections add below lines:


So, in my case @NgModule, looks like this:

  declarations: [AppComponent ],
  entryComponents: [ ],
  imports: [
  providers: [
    { provide: RouteReuseStrategy, useClass: IonicRouteStrategy }
  bootstrap: [AppComponent]

That's it!

Failed to load ApplicationContext for JUnit test of Spring controller

If you are using Maven, add the below config in your pom.xml:


With this config, you will be able to access xml files in WEB-INF folder. From Maven POM Reference: The testResources element block contains testResource elements. Their definitions are similar to resource elements, but are naturally used during test phases.

PHP Date Time Current Time Add Minutes

I think one of the best solutions and easiest is:

strtotime("+30 minutes")

Maybe it's not the most efficient but is one of the more understandable.

How to restrict SSH users to a predefined set of commands after login?

What you are looking for is called Restricted Shell. Bash provides such a mode in which users can only execute commands present in their home directories (and they cannot move to other directories), which might be good enough for you.

I've found this thread to be very illustrative, if a bit dated.

What is time(NULL) in C?

Time : It returns the time elapsed in seconds since the epoch 1 Jan 1970

Filter Excel pivot table using VBA

Field.CurrentPage only works for Filter fields (also called page fields).
If you want to filter a row/column field, you have to cycle through the individual items, like so:

Sub FilterPivotField(Field As PivotField, Value)
    Application.ScreenUpdating = False
    With Field
        If .Orientation = xlPageField Then
            .CurrentPage = Value
        ElseIf .Orientation = xlRowField Or .Orientation = xlColumnField Then
            Dim i As Long
            On Error Resume Next ' Needed to avoid getting errors when manipulating PivotItems that were deleted from the data source.
            ' Set first item to Visible to avoid getting no visible items while working
            .PivotItems(1).Visible = True
            For i = 2 To Field.PivotItems.Count
                If .PivotItems(i).Name = Value Then _
                    .PivotItems(i).Visible = True Else _
                    .PivotItems(i).Visible = False
            Next i
            If .PivotItems(1).Name = Value Then _
                .PivotItems(1).Visible = True Else _
                .PivotItems(1).Visible = False
        End If
    End With
    Application.ScreenUpdating = True
End Sub

Then, you would just call:

FilterPivotField ActiveSheet.PivotTables("PivotTable2").PivotFields("SavedFamilyCode"), "K123223"

Naturally, this gets slower the more there are individual different items in the field. You can also use SourceName instead of Name if that suits your needs better.

Calculate difference between 2 date / times in Oracle SQL

You could use to_timestamp function to convert the dates to timestamps and perform a substract operation.

Something like:

TO_TIMESTAMP ('13.10.1990 00:00:00','DD.MM.YYYY HH24:MI:SS')  - 
TO_TIMESTAMP ('01.01.1990:00:10:00','DD.MM.YYYY:HH24:MI:SS')

Convert stdClass object to array in PHP

Using the ArrayObject from Std or building your own

(new \ArrayObject($existingStdClass))

you can use the build in method on the new class:


or pass the new object to


How to pass parameters to the DbContext.Database.ExecuteSqlCommand method?

Turns out that this works.

var firstName = "John";
var id = 12;
var sql = "Update [User] SET FirstName = {0} WHERE Id = {1}";
ctx.Database.ExecuteSqlCommand(sql, firstName, id);

Get current rowIndex of table in jQuery

Since "$(this).parent().index();" and "$(this).parent('table').index();" don't work for me, I use this code instead:

   var row_index = $(this).closest("tr").index();
   var col_index = $(this).index();

How to enable C++17 compiling in Visual Studio?

There's now a drop down (at least since VS 2017.3.5) where you can specifically select C++17. The available options are (under project > Properties > C/C++ > Language > C++ Language Standard)

  • ISO C++14 Standard. msvc command line option: /std:c++14
  • ISO C++17 Standard. msvc command line option: /std:c++17
  • The latest draft standard. msvc command line option: /std:c++latest

(I bet, once C++20 is out and more fully supported by Visual Studio it will be /std:c++20)

How to change the background color on a Java panel?

setBackground() is the right method to use. Did you repaint after you changed it? If you change it before you make the panel (or its containing frame) visible it should work

Hiding button using jQuery

Try this:

     function ()

For doing everything else you can use something like this one:

     function ()


For hidding any other elements based on their IDs, use this one:

     function ()


Proxy setting for R

Tried all of these and also the solutions using netsh, winhttp etc. Geek On Acid's answer helped me download packages from the server but none of these solutions worked for using the package I wanted to run (twitteR package).

The best solution is to use a software that let's you configure system-wide proxy.

FreeCap (free) and Proxifier (trial) worked perfectly for me at my company.

Please note that you need to remove proxy settings from your browser and any other apps that you have configured to use proxy as these tools provide system-wide proxy for all network traffic from your computer.

How to set a:link height/width with css?

Thanks to RandomUs 1r for this observation:

changing it to display:inline-block; solves that issue. – RandomUs1r May 14 '13 at 21:59

I tried it myself for a top navigation menu bar, as follows:

First style the "li" element as follows:

display: inline-block;
width: 7em;
text-align: center;

Then style the "a"> element as follows:

width: 100%;

Now the navigation links are all equal width with text centered in each link.

Concatenating Column Values into a Comma-Separated List

Please try this with the following code:

SELECT @listStr = COALESCE(@listStr+',' , '') + CarName
SELECT @listStr

How to show math equations in general github's markdown(not github's blog)

If just wanted to show math in the browser for yourself, you could try the Chrome extension GitHub with MathJax. It's quite convenient.

How do I combine the first character of a cell with another cell in Excel?


Assuming A1 holds 1st names; B1 Last names

Convert and format a Date in JSP

You can do that using the SimpleDateFormat class.

SimpleDateFormat formatter=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

String dates=formatter.format(mydate);
//mydate is your date object

how to display progress while loading a url to webview in android?

Check out the sample code. It help you.

 private ProgressBar progressBar;
 WebView urlWebView= new WebView(Context);
    urlWebView.setWebViewClient(new AppWebViewClients(progressBar));

public class AppWebViewClients extends WebViewClient {
     private ProgressBar progressBar;

    public AppWebViewClients(ProgressBar progressBar) {
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        // TODO Auto-generated method stub
        return true;

    public void onPageFinished(WebView view, String url) {
        // TODO Auto-generated method stub
        super.onPageFinished(view, url);


Regular expression to match balanced parentheses

This might help to match balanced parenthesis.


There is no argument given that corresponds to the required formal parameter - .NET Error

I received this same error in the following Linq statement regarding DailyReport. The problem was that DailyReport had no default constructor. Apparently, it instantiates the object before populating the properties.

var sums = reports
    .GroupBy(r => r.CountryRegion)
    .Select(cr => new DailyReport
        CountryRegion = cr.Key,
        ProvinceState = "All",
        RecordDate = cr.First().RecordDate,
        Confirmed = cr.Sum(c => c.Confirmed),
        Recovered = cr.Sum(c => c.Recovered),
        Deaths = cr.Sum(c => c.Deaths)

What is Inversion of Control?

I like this explanation:

It start simple and shows code examples as well.

enter image description here

The consumer, X, needs the consumed class, Y, to accomplish something. That’s all good and natural, but does X really need to know that it uses Y?

Isn’t it enough that X knows that it uses something that has the behavior, the methods, properties etc, of Y without knowing who actually implements the behavior?

By extracting an abstract definition of the behavior used by X in Y, illustrated as I below, and letting the consumer X use an instance of that instead of Y it can continue to do what it does without having to know the specifics about Y.

enter image description here

In the illustration above Y implements I and X uses an instance of I. While it’s quite possible that X still uses Y what’s interesting is that X doesn’t know that. It just knows that it uses something that implements I.

Read article for further info and description of benefits such as:

  • X is not dependent on Y anymore
  • More flexible, implementation can be decided in runtime
  • Isolation of code unit, easier testing


How to convert a Drawable to a Bitmap?

very simple

Bitmap tempBMP = BitmapFactory.decodeResource(getResources(),R.drawable.image);

ng-model for `<input type="file"/>` (with directive DEMO)

If you want something a little more elegant/integrated, you can use a decorator to extend the input directive with support for type=file. The main caveat to keep in mind is that this method will not work in IE9 since IE9 didn't implement the File API. Using JavaScript to upload binary data regardless of type via XHR is simply not possible natively in IE9 or earlier (use of ActiveXObject to access the local filesystem doesn't count as using ActiveX is just asking for security troubles).

This exact method also requires AngularJS 1.4.x or later, but you may be able to adapt this to use $provide.decorator rather than angular.Module.decorator - I wrote this gist to demonstrate how to do it while conforming to John Papa's AngularJS style guide:

(function() {
    'use strict';

    * @ngdoc input
    * @name input[file]
    * @description
    * Adds very basic support for ngModel to `input[type=file]` fields.
    * Requires AngularJS 1.4.x or later. Does not support Internet Explorer 9 - the browser's
    * implementation of `HTMLInputElement` must have a `files` property for file inputs.
    * @param {string} ngModel
    *  Assignable AngularJS expression to data-bind to. The data-bound object will be an instance
    *  of {@link `FileList`}.
    * @param {string=} name Property name of the form under which the control is published.
    * @param {string=} ngChange
    *  AngularJS expression to be executed when input changes due to user interaction with the
    *  input element.
        .decorator('inputDirective', myInputFileDecorator);

    myInputFileDecorator.$inject = ['$delegate', '$browser', '$sniffer', '$filter', '$parse'];
    function myInputFileDecorator($delegate, $browser, $sniffer, $filter, $parse) {
        var inputDirective = $delegate[0],
            preLink =; = function (scope, element, attr, ctrl) {
            if (ctrl[0]) {
                if (angular.lowercase(attr.type) === 'file') {
                        scope, element, attr, ctrl[0], $sniffer, $browser, $filter, $parse);
                } else {
                    preLink.apply(this, arguments);

        return $delegate;

    function fileInputType(scope, element, attr, ctrl, $sniffer, $browser, $filter, $parse) {
        element.on('change', function (ev) {
            if (angular.isDefined(element[0].files)) {
                ctrl.$setViewValue(element[0].files, ev && ev.type);

        ctrl.$isEmpty = function (value) {
            return !value || value.length === 0;

Why wasn't this done in the first place? AngularJS support is intended to reach only as far back as IE9. If you disagree with this decision and think they should have just put this in anyway, then jump the wagon to Angular 2+ because better modern support is literally why Angular 2 exists.

The issue is (as was mentioned before) that without the file api support doing this properly is unfeasible for the core given our baseline being IE9 and polyfilling this stuff is out of the question for core.

Additionally trying to handle this input in a way that is not cross-browser compatible only makes it harder for 3rd party solutions, which now have to fight/disable/workaround the core solution.


I'm going to close this just as we closed #1236. Angular 2 is being build to support modern browsers and with that file support will easily available.

what is the use of xsi:schemaLocation?

The Java XML parser that spring uses will read the schemaLocation values and try to load them from the internet, in order to validate the XML file. Spring, in turn, intercepts those load requests and serves up versions from inside its own JAR files.

If you omit the schemaLocation, then the XML parser won't know where to get the schema in order to validate the config.

How to force NSLocalizedString to use a specific language

Swift Version:

NSUserDefaults.standardUserDefaults().setObject(["fr"], forKey: "AppleLanguages")

Does Typescript support the ?. operator? (And, what's it called?)

Edit Nov. 13, 2019!

As of November 5, 2019 TypeScript 3.7 has shipped and it now supports ?. the optional chaining operator !!!

For Historical Purposes Only:

Edit: I have updated the answer thanks to fracz comment.

TypeScript 2.0 released !. It's not the same as ?.(Safe Navigator in C#)

See this answer for more details:

This will only tell the compiler that the value is not null or undefined. This will not check if the value is null or undefined.

TypeScript Non-null assertion operator

// Compiled with --strictNullChecks
function validateEntity(e?: Entity) {
    // Throw exception if e is null or invalid entity

function processEntity(e?: Entity) {
    let s = e!.name;  // Assert that e is non-null and access name

How can I create directory tree in C++/Linux?

#include <sys/types.h>
#include <sys/stat.h>

int status;
status = mkdir("/tmp/a/b/c", S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);

From here. You may have to do separate mkdirs for /tmp, /tmp/a, /tmp/a/b/ and then /tmp/a/b/c because there isn't an equivalent of the -p flag in the C api. Be sure and ignore the EEXISTS errno while you're doing the upper level ones.

Is there a <meta> tag to turn off caching in all browsers?

It doesn't work in IE5, but that's not a big issue.

However, cacheing headers are unreliable in meta elements; for one, any web proxies between the site and the user will completely ignore them. You should always use a real HTTP header for headers such as Cache-Control and Pragma.

Python Pandas Counting the Occurrences of a Specific value

An elegant way to count the occurrence of '?' or any symbol in any column, is to use built-in function isin of a dataframe object.

Suppose that we have loaded the 'Automobile' dataset into df object. We do not know which columns contain missing value ('?' symbol), so let do:


DataFrame.isin(values) official document says:

it returns boolean DataFrame showing whether each element in the DataFrame is contained in values

Note that isin accepts an iterable as input, thus we need to pass a list containing the target symbol to this function. df.isin(['?']) will return a boolean dataframe as follows.

    symboling   normalized-losses   make    fuel-type   aspiration-ratio ...
0   False       True                False   False       False
1   False       True                False   False       False
2   False       True                False   False       False
3   False       False               False   False       False
4   False       False               False   False       False
5   False       True                False   False       False

To count the number of occurrence of the target symbol in each column, let's take sum over all the rows of the above dataframe by indicating axis=0. The final (truncated) result shows what we expect:

symboling             0
normalized-losses    41
bore                  4
stroke                4
compression-ratio     0
horsepower            2
peak-rpm              2
city-mpg              0
highway-mpg           0
price                 4

Set UILabel line spacing

Of course, Mike's answer doesn't work if you pass the string programmatically. In this case you need to pass a attributed string and change it's style.

NSMutableAttributedString * attrString = [[NSMutableAttributedString alloc] initWithString:@"Your \nregular \nstring"];
NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
[style setLineSpacing:4];
[attrString addAttribute:NSParagraphStyleAttributeName
                   range:NSMakeRange(0, attrString.length)];
_label.attributedText = attrString;

Nexus 5 USB driver

Windows 7 x32 I found that no matter what I did, the driver being used dated back to 2006. It would not update, in fact Windows appears to be preferring the old driver to the new. I eventually found a way to sort it.

The Device Manager contains 'ghost' drivers that need to be deleted (if you have the same problem as I). To see them requires setting a variable in the registry, restarting and then deleting the likely redundant drivers.

Open the Device Manager from the command line use devmgmt.msc There are other ways, but this is easiest to describe. Currently it shows only 'current' drivers.

Open the System Properties box. Via Command line use sysdm.cpl

** Be aware that playing with area of your computer can break it. Back away if you are at all unsure of this. **

  1. Open the Advanced tab, click Environmental Variables.
  2. Under System Variables, click New.
  3. Enter variable name devmgr_show_nonpresent_devices, under value enter 1.
  4. Restart your computer.

Re-open the Device Manager, under view click Show Hidden Devices.

From here delete what you think are the problems then follow the advise you will have read elsewhere. On two seperate computers I have done this and found all I needed to do following this was download and install the standard google drivers as per user3079537's answer above. Good luck.


Best way to define private methods for a class in Objective-C

There's no way of getting around issue #2. That's just the way the C compiler (and hence the Objective-C compiler) work. If you use the XCode editor, the function popup should make it easy to navigate the @interface and @implementation blocks in the file.

Eclipse - debugger doesn't stop at breakpoint

In order to debugger work with remote, the java .class files must be complied along with debugging information. If "-g:none" option was passed to compiler then the class file will not have necessary information and hence debugger will not be able to match breakpoints on source code with that class in remote. Meanwhile, if jars/class files were obfuscated, then they also will not have any debug info. According to your responses, most probably this is not your case, but this info could be useful for others who face the same issue.

What is duck typing?

Wikipedia has a fairly detailed explanation:

duck typing is a style of dynamic typing in which an object's current set of methods and properties determines the valid semantics, rather than its inheritance from a particular class or implementation of a specific interface.

The important note is likely that with duck typing a developer is concerned more with the parts of the object that are consumed rather than what the actual underlying type is.

Dynamic variable names in Bash

For zsh (newers mac os versions), you should use

echo ${(P)aux_var}

Instead of "!"

Count number of occurrences of a pattern in a file (even on same line)

To count all occurrences, use -o. Try this:

echo afoobarfoobar | grep -o foo | wc -l

And man grep of course (:


Some suggest to use just grep -co foo instead of grep -o foo | wc -l.


This shortcut won't work in all cases. Man page says:

-c print a count of matching lines

Difference in these approaches is illustrated below:


$ echo afoobarfoobar | grep -oc foo

As soon as the match is found in the line (a{foo}barfoobar) the searching stops. Only one line was checked and it matched, so the output is 1. Actually -o is ignored here and you could just use grep -c instead.


$ echo afoobarfoobar | grep -o foo

$ echo afoobarfoobar | grep -o foo | wc -l

Two matches are found in the line (a{foo}bar{foo}bar) because we explicitly asked to find every occurrence (-o). Every occurence is printed on a separate line, and wc -l just counts the number of lines in the output.

How to call jQuery function onclick?

Try this:


<input type="submit" value="submit" name="submit" onclick="myfunction()">


<script type="text/javascript">
 function myfunction() 
    var url = $(location).attr('href');
    $('#spn_url').html('<strong>' + url + '</strong>');

Multiple submit buttons in an HTML form

Instead of struggling with multiple submits, JavaScript or anything like that to do some previous/next stuff, an alternative would be to use a carousel to simulate the different pages. Doing this :

  • You don't need multiple buttons, inputs or submits to do the previous/next thing, you have only one input type="submit" in only one form.
  • The values in the whole form are there until the form is submitted.
  • The user can go to any previous page and any next page flawlessly to modify the values.

Example using Bootstrap 5.0.0 :

<div id="carousel" class="carousel slide" data-ride="carousel">
    <form action="index.php" method="post" class="carousel-inner">
        <div class="carousel-item active">
            <input type="text" name="lastname" placeholder="Lastname"/>
        <div class="carousel-item">
            <input type="text" name="firstname" placeholder="Firstname"/>
        <div class="carousel-item">
            <input type="submit" name="submit" value="Submit"/>
    <a class="btn-secondary" href="#carousel" role="button" data-slide="prev">Previous page</a>
    <a class="btn-primary" href="#carousel" role="button" data-slide="next">Next page</a>

AngularJs: How to set radio button checked based on model

One way that I see more powerful and avoid having a isDefault in all the models is by using the ng-attributes ng-model, ng-value and ng-checked.

ng-model: binds the value to your model.

ng-value: the value to pass to the ng-model binding.

ng-checked: value or expression that is evaluated. Useful for radio-button and check-boxes.

Example of use: In the following example, I have my model and a list of languages that my site supports. To display the different languages supported and updating the model with the selecting language we can do it in this way.

<!-- Radio -->
<div ng-repeat="language in languages">


      <input ng-model="site.lang"
             ng-checked="(site.lang == language)"

      <span> {{language}} </span>


<!-- end of Radio -->

Our model site.lang will get a language value whenever the expression under evaluation (site.lang == language) is true. This will allow you to sync it with server easily since your model already has the change.

SQL Server: Null VS Empty String

NULL is a non value, like undefined. '' is a empty string with 0 characters.
The value of a string in database depends of your value in your UI, but generally, it's an empty string '' if you specify the parameter in your query or stored procedure.

Kendo grid date column not formatting

Try formatting the date in the kendo grid as:

columns.Bound(x => x.LastUpdateDate).ClientTemplate("#= kendo.toString(LastUpdateDate, \"MM/dd/yyyy hh:mm tt\") #");

Alternative to google finance api

If you are still looking to use Google Finance for your data you can check this out.

I recently needed to test if SGX data is indeed retrievable via google finance (and of course i met with the same problem as you)

How do I download a file from the internet to my linux server with Bash

I guess you could use curl and wget, but since Oracle requires you to check of some checkmarks this will be painfull to emulate with the tools mentioned. You would have to download the page with the license agreement and from looking at it figure out what request is needed to get to the actual download.

Of course you could simply start a browser, but this might not qualify as 'from the command line'. So you might want to look into lynx, a text based browser.

Spring: how do I inject an HttpServletRequest into a request-scoped bean?

As suggested here you can also inject the HttpServletRequest as a method param, e.g.:

public MyResponseObject myApiMethod(HttpServletRequest request, ...) {

An attempt was made to access a socket in a way forbidden by its access permissions

I had a similar issue with Docker for Windows and Hyper-V having reserved ports for its own use- in my case, it was port 3001 that couldn't be accessed.

  • The port wasn't be used by another process- running netstat -ano | findstr 3001 in an Administrator Powershell prompt showed nothing.
  • However, netsh interface ipv4 show excludedportrange protocol=tcp showed that the port was in one of the exclusion ranges.

I was able to follow the solution described in Docker for Windows issue #3171 (Unable to bind ports: Docker-for-Windows & Hyper-V excluding but not using important port ranges):

  1. Disable Hyper-V:

    dism.exe /Online /Disable-Feature:Microsoft-Hyper-V
  2. After the required restarts, reserve the port you want so Hyper-V doesn't reserve it back:

    netsh int ipv4 add excludedportrange protocol=tcp startport=3001 numberofports=1
  3. Reenable Hyper-V:

    dism.exe /Online /Enable-Feature:Microsoft-Hyper-V /All

After this, I was able to start my docker container.

Best way to get user GPS location in background in Android

To get callback on LocationChange

Define an interface

public interface LocationCallback {
public void locationChanged(Location location);

Callback in your Activity

public static LocationCallback callback;
public void getUserLocation() {

    callback = new LocationCallback() {
        public void locationChanged(Location location) {
            Toast.makeText(getApplicationContext(), location.getLatitude() + "," + location.getLongitude(), Toast.LENGTH_SHORT).show();

    Intent service_intent = new Intent(this, GPSService.class);


Change onLocationChange Method to

    public void onLocationChanged(Location location) {
        Log.e(TAG, "onLocationChanged: " + location);

Testing for empty or nil-value string

The second clause does not need a !variable.nil? check—if evaluation reaches that point, variable.nil is guaranteed to be false (because of short-circuiting).

This should be sufficient:

variable = id if variable.nil? || variable.empty?

If you're working with Ruby on Rails, Object.blank? solves this exact problem:

An object is blank if it’s false, empty, or a whitespace string. For example, "", " ", nil, [], and {} are all blank.

How to detect scroll position of page using jQuery

Store the value of the scroll as changes in HiddenField when around the PostBack retrieves the value and adds the scroll.


jQuery(document).ready(function () {

    $(window).scrollTop($("#<%=hidScroll.ClientID %>").val());

    $(window).scroll(function (event) {
        $("#<%=hidScroll.ClientID %>").val($(window).scrollTop());

var prm = Sys.WebForms.PageRequestManager.getInstance();

prm.add_endRequest(function () {

    $(window).scrollTop($("#<%=hidScroll.ClientID %>").val());

    $(window).scroll(function (event) {
        $("#<%=hidScroll.ClientID %>").val($(window).scrollTop());

//Page Asp.Net
<asp:HiddenField ID="hidScroll" runat="server" Value="0" />

Re-doing a reverted merge in Git

Let's assume you have such history


Where A, B failed commits and W - is revert of M

So before I start fixing found problems I do cherry-pick of W commit to my branch

git cherry-pick -x W

Then I revert W commit on my branch

git revert W 

After I can continue fixing.

The final history could look like:

              /                       /     

When I send a PR it will clearly shows that PR is undo revert and adds some new commits.

Change color inside strings.xml

If you wish to change the font color inside string.xml file, you may try the following code.

   <string name="hello_world"><font fgcolor="#ffff0000">Hello world!</font></string>

Securing a password in a properties file

The poor mans compromise solution is to use a simplistic multi signature approach.

For Example the DBA sets the applications database password to a 50 character random string. TAKqWskc4ncvKaJTyDcgAHq82X7tX6GfK2fc386bmNw3muknjU

He or she give half the password to the application developer who then hard codes it into the java binary.

private String pass1 = "TAKqWskc4ncvKaJTyDcgAHq82"

The other half of the password is passed as a command line argument. the DBA gives pass2 to the system support or admin person who either enters it a application start time or puts it into the automated application start up script.

java -jar /myapplication.jar -pass2 X7tX6GfK2fc386bmNw3muknjU

When the application starts it uses pass1 + pass2 and connects to the database.

This solution has many advantages with out the downfalls mentioned.

You can safely put half the password in a command line arguments as reading it wont help you much unless you are the developer who has the other half of the password.

The DBA can also still change the second half of the password and the developer need not have to re-deploy the application.

The source code can also be semi public as reading it and the password will not give you application access.

You can further improve the situation by adding restrictions on the IP address ranges the database will accept connections from.

Enable remote MySQL connection: ERROR 1045 (28000): Access denied for user

Do you have a firewall ? make sure that port 3306 is open.

On windows , by default mysql root account is created that is permitted to have access from localhost only unless you have selected the option to enable access from remote machines during installation .

creating or update the desired user with '%' as hostname .

example :

CREATE USER 'krish'@'%' IDENTIFIED BY 'password';

getting the last item in a javascript object

var myObj = {a: 1, b: 2, c: 3}, lastProperty;
for (lastProperty in myObj);


Font-awesome, input type 'submit'

You can use button classes btn-link and btn-xs with type submit, which will make a small invisible button with an icon inside of it. Example:

<button class="btn btn-link btn-xs" type="submit" name="action" value="delete">
    <i class="fa fa-times text-danger"></i>

Error message "unreported exception; must be caught or declared to be thrown"

Exceptions bubble up the stack. If a caller calls a method that throws a checked exception, like IOException, it must also either catch the exception, or itself throw it.

In the case of the first block:

    setSize(300, 300);

        addWindowListener(new WindowAdapter()
            public void windowClosing(WindowEvent we)

You would have to include a try catch block:

    try {
    catch (IOException e) {
        // Do something here
    setSize(300, 300);

        addWindowListener(new WindowAdapter()
            public void windowClosing(WindowEvent we)

In the case of the second:

public void actionPerformed(ActionEvent ae)
    if (ae.getSource() == submit)

You cannot throw IOException from this method as its signature is determined by the interface, so you must catch the exception within:

public void actionPerformed(ActionEvent ae)
        try {
        catch (IOException e) {
            // Do something here

Remember, the showFile() method is throwing the exception; that's what the "throws" keyword indicates that the method may throw that exception. If the showFile() method is throwing, then whatever code calls that method must catch, or themselves throw the exception explicitly by including the same throws IOException addition to the method signature, if it's permitted.

If the method is overriding a method signature defined in an interface or superclass that does not also declare that the method may throw that exception, you cannot declare it to throw an exception.

How to throw a C++ exception


#include <stdexcept>

int compare( int a, int b ) {
    if ( a < 0 || b < 0 ) {
        throw std::invalid_argument( "received negative value" );

The Standard Library comes with a nice collection of built-in exception objects you can throw. Keep in mind that you should always throw by value and catch by reference:

try {
    compare( -1, 3 );
catch( const std::invalid_argument& e ) {
    // do stuff with exception... 

You can have multiple catch() statements after each try, so you can handle different exception types separately if you want.

You can also re-throw exceptions:

catch( const std::invalid_argument& e ) {
    // do something

    // let someone higher up the call stack handle it if they want

And to catch exceptions regardless of type:

catch( ... ) { };

React - changing an uncontrolled input

For dynamically setting state properties for form inputs and keeping them controlled you could do something like this:

const inputs = [
    { name: 'email', type: 'email', placeholder: "Enter your email"},
    { name: 'password', type: 'password', placeholder: "Enter your password"},
    { name: 'passwordConfirm', type: 'password', placeholder: "Confirm your password"},

class Form extends Component {
    this.state = {} // Notice no explicit state is set in the constructor

  handleChange = (e) => {
    const { name, value } =;

      [name]: value

  handleSubmit = (e) => {
    // do something

  render() {
     <form onSubmit={(e) => handleSubmit(e)}>
       { inputs.length ? => {
           const { name, placeholder, type } = input;
           const value = this.state[name] || ''; // Does it exist? If so use it, if not use an empty string

           return <input key={name}  type={type} name={name} placeholder={placeholder} value={value} onChange={this.handleChange}/>
       }) :
       <button type="submit" onClick={(e) => e.preventDefault }>Submit</button>

Show values from a MySQL database table inside a HTML table on a webpage

Surely a better solution would by dynamic so that it would work for any query without having to know the column names?

If so, try this (obviously the query should match your database):

// You'll need to put your db connection details in here.
$conn = new mysqli($server_hostname, $server_username, $server_password, $server_database);

// Run the query.
$result = $conn->query("SELECT * FROM table LIMIT 10");

// Get the result in to a more usable format.
$query = array();
while($query[] = mysqli_fetch_assoc($result));

// Output a dynamic table of the results with column headings.
echo '<table border="1">';
echo '<tr>';
foreach($query[0] as $key => $value) {
    echo '<td>';
    echo $key;
    echo '</td>';
echo '</tr>';
foreach($query as $row) {
    echo '<tr>';
    foreach($row as $column) {
        echo '<td>';
        echo $column;
        echo '</td>';
    echo '</tr>';
echo '</table>';

Taken from here:

How to use ternary operator in razor (specifically on HTML attributes)?

in my problem I want the text of anchor <a>text</a> inside my view to be based on some value and that text is retrieved form App string Resources

so, this @() is the solution

<a href='#'>
      @(Model.ID == 0 ? Resource_en.Back : Resource_en.Department_View_DescartChanges)

if the text is not from App string Resources use this

@(Model.ID == 0 ? "Back" :"Descart Changes")

Best way to increase heap size in catalina.bat file

increase heap size of tomcat for window add this file in apache-tomcat-7.0.42\bin

enter image description here

heap size can be changed based on Requirements.

  set JAVA_OPTS=-Dfile.encoding=UTF-8 -Xms128m -Xmx1024m -XX:PermSize=64m -XX:MaxPermSize=256m

How to access JSON Object name/value?

You should do

alert(data[0].name); //Take the property name of the first array

and not


jQuery should be able to sniff the dataType for you even if you don't set it so no need for JSON.parse.

fiddle here

Responsive web design is working on desktop but not on mobile device

You are probably missing the viewport meta tag in the html head:

 <meta name="viewport" content="width=device-width, initial-scale=1">

Without it the device assumes and sets the viewport to full size.

More info here.

How to deselect all selected rows in a DataGridView control?

i have ran into the same problem and found a solution (not totally by myself, but there is the internet for)

Color blue  = ColorTranslator.FromHtml("#CCFFFF");
Color red = ColorTranslator.FromHtml("#FFCCFF");
Color letters = Color.Black;

foreach (DataGridViewRow r in datagridIncome.Rows)
    if (r.Cells[5].Value.ToString().Contains("1")) { 
        r.DefaultCellStyle.BackColor = blue;
        r.DefaultCellStyle.SelectionBackColor = blue;
        r.DefaultCellStyle.SelectionForeColor = letters;
    else { 
        r.DefaultCellStyle.BackColor = red;
        r.DefaultCellStyle.SelectionBackColor = red;
        r.DefaultCellStyle.SelectionForeColor = letters;

This is a small trick, the only way you can see a row is selected, is by the very first column (not column[0], but the one therefore). When you click another row, you will not see the blue selection anymore, only the arrow indicates which row have selected. As you understand, I use rowSelection in my gridview.

Deleting Elements in an Array if Element is a Certain value VBA

I'm pretty new to vba & excel - only been doing this for about 3 months - I thought I'd share my array de-duplication method here as this post seems relevant to it:

This code if part of a bigger application that analyses pipe data- Pipes are listed in a sheet with number in xxxx.1, xxxx.2, yyyy.1, yyyy.2 .... format. so thats why all the string manipulation exists. basically it only collects the pipe number once only, and not the .2 or .1 part.

        With wbPreviousSummary.Sheets(1)
'   here, we will write the edited pipe numbers to a collection - then pass the collection to an array
        Dim PipeDict As New Dictionary

        Dim TempArray As Variant

        TempArray = .Range(.Cells(3, 2), .Cells(3, 2).End(xlDown)).Value

        For ele = LBound(TempArray, 1) To UBound(TempArray, 1)

            If Not PipeDict.Exists(Left(TempArray(ele, 1), Len(TempArray(ele, 1) - 2))) Then

                PipeDict.Add Key:=Left(TempArray(ele, 1), Len(TempArray(ele, 1) - 2)), _
                                                        Item:=Left(TempArray(ele, 1), Len(TempArray(ele, 1) - 2))

            End If

        Next ele

        TempArray = PipeDict.Items

        For ele = LBound(TempArray) To UBound(TempArray)
            MsgBox TempArray(ele)
        Next ele

    End With
    wbPreviousSummary.Close SaveChanges:=False

    Set wbPreviousSummary = Nothing 'done early so we dont have the information loaded in memory

Using a heap of message boxes for debugging atm - im sure you'll change it to suit your own work.

I hope people find this useful, Regards Joe

How to use variables in SQL statement in Python?

The syntax for providing a single value can be confusing for inexperienced Python users.

Given the query

INSERT INTO mytable (fruit) VALUES (%s)

The value passed to cursor.execute must still be a tuple even though it is a singleton, so we must provide a single element tuple, like this: (value,).

cursor.execute("""INSERT INTO mytable (fruit) VALUES (%s)""", ('apple',))

What to return if Spring MVC controller method doesn't return value?

There is nothing wrong with returning a void @ResponseBody and you should for POST requests.

Use HTTP status codes to define errors within exception handler routines instead as others are mentioning success status. A normal method as you have will return a response code of 200 which is what you want, any exception handler can then return an error object and a different code (i.e. 500).

How to make a TextBox accept only alphabetic characters?

you can try following code that alert at the time of key press event

private void tbOwnerName_KeyPress(object sender, KeyPressEventArgs e)

        //===================to accept only charactrs & space/backspace=============================================

        if (e.Handled = !(char.IsLetter(e.KeyChar) || e.KeyChar == (char)Keys.Back || e.KeyChar == (char)Keys.Space))
            e.Handled = true;
            MessageBox.Show("enter characters only");

Angular2 change detection: ngOnChanges not firing for nested object

suppose you have a nested object, like

var obj = {"parent": {"child": {....}}}

If you passed the reference of the complete object, like

[wholeObj] = "obj"

In that case, you can't detect the changes in the child objects, so to overcome this problem you can also pass the reference of the child object through another property, like

[wholeObj] = "obj" [childObj] = "obj.parent.child"

So you can also detect the changes from the child objects too.

ngOnChanges(changes: SimpleChanges) { 
    if (changes.childObj) {// your logic here}

Java simple code: Unexpected end of file from server

In my case it was solved just passing proxy to connection. Thanks to @Andreas Panagiotidis.

Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("<YOUR.HOST>", 80)));
HttpsURLConnection con = (HttpsURLConnection) url.openConnection(proxy);

Display names of all constraints for a table in Oracle SQL

Often enterprise databases have several users and I'm not aways on the right one :


Picked from Oracle documentation

Declaring multiple variables in JavaScript

I believe that before we started using ES6, an approach with a single var declaration was neither good nor bad (in case if you have linters and 'use strict'. It was really a taste preference. But now things changed for me. These are my thoughts in favour of multiline declaration:

  1. Now we have two new kinds of variables, and var became obsolete. It is good practice to use const everywhere until you really need let. So quite often your code will contain variable declarations with assignment in the middle of the code, and because of block scoping you quite often will move variables between blocks in case of small changes. I think that it is more convenient to do that with multiline declarations.

  2. ES6 syntax became more diverse, we got destructors, template strings, arrow functions and optional assignments. When you heavily use all those features with single variable declarations, it hurts readability.

I want to use CASE statement to update some records in sql server 2005

This is also an alternate use of case-when...

UPDATE [dbo].[JobTemplates]
SET [CycleId] = 
    CASE [Id]
        WHEN 1376 THEN 44   --ACE1 FX1
        WHEN 1385 THEN 44   --ACE1 FX2
        WHEN 1574 THEN 43   --ACE1 ELEM1
        WHEN 1576 THEN 43   --ACE1 ELEM2
        WHEN 1581 THEN 41   --ACE1 FS1
        WHEN 1585 THEN 42   --ACE1 HS1
        WHEN 1588 THEN 43   --ACE1 RS1
        WHEN 1589 THEN 44   --ACE1 RM1
        WHEN 1590 THEN 43   --ACE1 ELEM3
        WHEN 1591 THEN 43   --ACE1 ELEM4
        WHEN 1595 THEN 44   --ACE1 SSTn     
        ELSE 0  
    [Id] IN (1376,1385,1574,1576,1581,1585,1588,1589,1590,1591,1595)

I like the use of the temporary tables in cases where duplicate values are not permitted and your update may create them. For example:

    ,CASE [CycleId]
        WHEN  29 THEN 44
        WHEN  30 THEN 43
        WHEN  31 THEN 43
        WHEN 101 THEN 41
        WHEN 102 THEN 43
        WHEN 116 THEN 42
        WHEN 120 THEN 44
        WHEN 127 THEN 44
        WHEN 129 THEN 44
        ELSE    0
     END                AS [CycleId]
    [QueueId] = 3
    [BaseDimensionId], [ElastomerTypeId], [Id];
---- (403 row(s) affected)

UPDATE [dbo].[ProductionQueueProcessAutoclaveNominals]
    [CycleId] = X.[CycleId]
        MIN([Id]) AS [Id],[QueueId],[BaseDimensionId],[ElastomerTypeId],[CycleId] 
    GROUP BY    
) AS X
    [dbo].[ProductionQueueProcessAutoclaveNominals].[Id] = X.[Id];
----(375 row(s) affected)

Difference between Date(dateString) and new Date(dateString)

Any ideas on how to parse "2010-08-17 12:09:36" with new Date()?

Until ES5, there was no string format that browsers were required to support, though there are a number that are widely supported. However browser support is unreliable an inconsistent, e.g. some will allow out of bounds values and others wont, some support certain formats and others don't, etc.

ES5 introduced support for some ISO 8601 formats, however the OP is not compliant with ISO 8601 and not all browsers in use support it anyway.

The only reliable way is to use a small parsing function. The following parses the format in the OP and also validates the values.

/* Parse date string in format yyyy-mm-dd hh:mm:ss_x000D_
** If string contains out of bounds values, an invalid date is returned_x000D_
** _x000D_
** @param {string} s - string to parse, e.g. "2010-08-17 12:09:36"_x000D_
**                     treated as "local" date and time_x000D_
** @returns {Date}   - Date instance created from parsed string_x000D_
function parseDateString(s) {_x000D_
  var b = s.split(/\D/);_x000D_
  var d = new Date(b[0], --b[1], b[2], b[3], b[4], b[5]);_x000D_
  return d && d.getMonth() == b[1] && d.getHours() == b[3] &&_x000D_
         d.getMinutes() == b[4]? d : new Date(NaN);_x000D_
  parseDateString('2010-08-17 12:09:36') + '<br>' +  // Valid values_x000D_
  parseDateString('2010-08-45 12:09:36')             // Out of bounds date_x000D_

Difference between and e.currentTarget

I like visual answers.

enter image description here

When you click #btn, two event handlers get called and they output what you see in the picture.

Demo here:

How do I declare and assign a variable on a single line in SQL

You've nearly got it:

DECLARE @myVariable nvarchar(max) = 'hello world';

See here for the docs

For the quotes, SQL Server uses apostrophes, not quotes:

DECLARE @myVariable nvarchar(max) = 'John said to Emily "Hey there Emily"';

Use double apostrophes if you need them in a string:

DECLARE @myVariable nvarchar(max) = 'John said to Emily ''Hey there Emily''';

How to set the "Content-Type ... charset" in the request header using a HTML link

This is not possible from HTML on. The closest what you can get is the accept-charset attribute of the <form>. Only MSIE browser adheres that, but even then it is doing it wrong (e.g. CP1252 is actually been used when it says that it has sent ISO-8859-1). Other browsers are fully ignoring it and they are using the charset as specified in the Content-Type header of the response. Setting the character encoding right is basically fully the responsiblity of the server side. The client side should just send it back in the same charset as the server has sent the response in.

To the point, you should really configure the character encoding stuff entirely from the server side on. To overcome the inability to edit URIEncoding attribute, someone here on SO wrote a (complex) filter: Detect the URI encoding automatically in Tomcat. You may find it useful as well (note: I haven't tested it).

Update: Noted should be that the meta tag as given in your question is ignored when the content is been transferred over HTTP. Instead, the HTTP response Content-Type header will be used to determine the content type and character encoding. You can determine the HTTP header with for example Firebug, in the Net panel.

alt text

How to get PHP $_GET array?

The usual way to do this in PHP is to put id[] in your URL instead of just id:


Then $_GET['id'] will be an array of those values. It's not especially pretty, but it works out of the box.

text-overflow: ellipsis not working

You may try using ellipsis by adding the following in CSS:

.truncate {
  width: 250px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;

But it seems like this code just applies to one-line trim. More ways to trim text and show ellipsis can be found in this website:

How to search for string in an array

Another option would be use a dictionary instead of an array:

Dim oNames As Object
Set oNames = CreateObject("Scripting.Dictionary")
'You could if need be create this automatically from an existing Array
'The 1 is just a dummy value, we just want the names as keys
oNames.Add "JOHN", 1
oNames.Add "BOB", 1
oNames.Add "JAMES", 1
oNames.Add "PHILIP", 1

As this would then get you a one-liner of


The advantage a dictionary provides is exact matching over partial matching from Filter. Say if you have the original list of names in an Array, but were looking for "JO" or "PHIL" who were actually two new people in addition to the four we started with. In this case, Filter(oNAMES, "JO") will match "JOHN" which may not be desired. With a dictionary, it won't.

How to execute a shell script in PHP?

Residuum did provide a correct answer to how you should get shell exec to find your script, but in regards to security, there are a couple of points.

I would imagine you don't want your shell script to be in your web root, as it would be visible to anyone with web access to your server.

I would recommend moving the shell script to outside of the webroot

      $tempFolder = '/tmp';
      $webRootFolder = '/var/www';
      $scriptName = '';
      $moveCommand = "mv $webRootFolder/$scriptName $tempFolder/$scriptName";
      $output = shell_exec($moveCommand);

In regards to the:

i added www-data ALL=(ALL) NOPASSWD:ALL to /etc/sudoers works

You can modify this to only cover the specific commands in your script which require sudo. Otherwise, if none of the commands in your sh script require sudo to execute, you don't need to do this at all anyway.

Try running the script as the apache user (use the su command to switch to the apache user) and if you are not prompted for sudo or given permission denied, etc, it'll be fine.


sudo su apache (or www-data)
cd /var/www
sh ./myscript

Also... what brought me here was that I wanted to run a multi line shell script using commands that are dynamically generated. I wanted all of my commands to run in the same shell, which won't happen using multiple calls to shell_exec(). The answer to that one is to do it like Jenkins - create your dynamically generated multi line of commands, put it in a variable, save it to a file in a temp folder, execute that file (using shell_exec in() php as Jenkins is Java), then do whatever you want with the output, and delete the temp file

... voila

How to convert a char array back to a string?

String str = "wwwwww3333dfevvv";
char[] c = str.toCharArray();

Now to convert character array into String , there are two ways.


Returns the string [w, w, w, w, w, w, 3, 3, 3, 3, d, f, e, v, v, v].



Returns the string wwwwww3333dfevvv.

In Summary: pay attention to Arrays.toString(c), because you'll get "[w, w, w, w, w, w, 3, 3, 3, 3, d, f, e, v, v, v]" instead of "wwwwww3333dfevvv".

Is it possible to cherry-pick a commit from another git repository?

My situation was that I have a bare repo that the team pushes to, and a clone of that sitting right next to it. This set of lines in a Makefile work correctly for me:

git reset --hard
git remote update --prune
git pull --rebase --all
git cherry-pick -n remotes/origin/$(BRANCH)

By keeping the master of the bare repo up to date, we are able to cherry-pick a proposed change published to the bare repo. We also have a (more complicated) way to cherry-pick multiple braches for consolidated review and testing.

If "knows nothing" means "can't be used as a remote", then this doesn't help, but this SO question came up as I was googling around to come up with this workflow so I thought I'd contribute back.

Using await outside of an async function

you can do top level await since typescript 3.8
From the post:
This is because previously in JavaScript (along with most other languages with a similar feature), await was only allowed within the body of an async function. However, with top-level await, we can use await at the top level of a module.

const response = await fetch("...");
const greeting = await response.text();

// Make sure we're a module
export {};

Note there’s a subtlety: top-level await only works at the top level of a module, and files are only considered modules when TypeScript finds an import or an export. In some basic cases, you might need to write out export {} as some boilerplate to make sure of this.

Top level await may not work in all environments where you might expect at this point. Currently, you can only use top level await when the target compiler option is es2017 or above, and module is esnext or system. Support within several environments and bundlers may be limited or may require enabling experimental support.

How do we download a blob url video

I just came up with a general solution, which should work on most websites. I tried this on Chrome only, but this method should work with any other browser, though, as Dev Tools are pretty much the same in them all.


  1. Open the browser's Dev Tools (usually F12, or Ctrl-Shift-I, or right-click and then Inspect in the popup menu) on the page with the video you are interested in.
  2. Go to Network tab and then reload the page. The tab will get populated with a list of requests (may be up to a hundred of them or even more).
  3. Search through the names of requests and find the request with .m3u8 extension. There may be many of them, but most likely the first you find is the one you are looking for. It may have any name, e.g. playlist.m3u8.
  4. Open the request and under Headers subsection you will see request's full URL in Request URL field. Copy it. enter image description here
  5. Extract the video from m3u8. There are many ways to do it, I'll give you those I tried, but you can google more by "download video from m3u8".
    • Option 1. If you have VLC player installed, feed the URL to VLC using "Open Network Stream..." menu option. I'm not going to go into details on this part here, there are a number of comprehensive guides in many places, for example, here. If the page doesn't work, you can always google another one by "vlc download online video".
    • Option 2. If you are more into command line, use FFMPEG or your own script, as directed in this SuperUser question.

How to add number of days in postgresql datetime

For me I had to put the whole interval in single quotes not just the value of the interval.

select id,  
   created_at + interval '1 day' * claim_window as deadline from projects   

Instead of

select id,  
   created_at + interval '1' day * claim_window as deadline from projects   

Postgres Date/Time Functions

Curl not recognized as an internal or external command, operable program or batch file

Method 1:\

add "C:\Program Files\cURL\bin" path into system variables Path right-click My Computer and click Properties >advanced > Environment Variables enter image description here

Method 2: (if method 1 not work then)

simple open command prompt with "run as administrator"

PermGen elimination in JDK 8

Oracle's JVM implementation for Java 8 got rid of the PermGen model and replaced it with Metaspace.

Unicode character in PHP string

PHP 7.0.0 has introduced the "Unicode codepoint escape" syntax.

It's now possible to write Unicode characters easily by using a double-quoted or a heredoc string, without calling any function.

$unicodeChar = "\u{1000}";

How to delete an app from iTunesConnect / App Store Connect

Apps can’t be deleted if they are part of a Game Center group, in an app bundle, or currently displayed on a store. You’ll want to remove the app from sale or from the group if you want to delete it.

Source: iTunes Connect Developer Guide - Transferring and Deleting Apps

Maven and adding JARs to system scope

System scope was only designed to deal with 'system' files; files sitting in some fixed location. Files in /usr/lib, or ${java.home} (e.g. tools.jar). It wasn't designed to support miscellaneous .jar files in your project.

The authors intentionally refused to make the pathname expansions work right for that to discourage you. As a result, in the short term you can use install:install-file to install into the local repo, and then some day use a repo manager to share.

Fast way to discover the row count of a table in PostgreSQL

How wide is the text column?

With a GROUP BY there's not much you can do to avoid a data scan (at least an index scan).

I'd recommend:

  1. If possible, changing the schema to remove duplication of text data. This way the count will happen on a narrow foreign key field in the 'many' table.

  2. Alternatively, creating a generated column with a HASH of the text, then GROUP BY the hash column. Again, this is to decrease the workload (scan through a narrow column index)


Your original question did not quite match your edit. I'm not sure if you're aware that the COUNT, when used with a GROUP BY, will return the count of items per group and not the count of items in the entire table.

File.separator vs FileSystem.getSeparator() vs System.getProperty("file.separator")?

If your code doesn't cross filesystem boundaries, i.e. you're just working with one filesystem, then use

This will, as explained, get you the default separator for your FS. As Bringer128 explained, System.getProperty("file.separator") can be overriden via command line options and isn't as type safe as

The last one, java.nio.file.FileSystems.getDefault().getSeparator(); was introduced in Java 7, so you might as well ignore it for now if you want your code to be portable across older Java versions.

So, every one of these options is almost the same as others, but not quite. Choose one that suits your needs.

Given a filesystem path, is there a shorter way to extract the filename without its extension?

Firstly, the code in the question does not produce the described output. It extracts the file extension ("txt") and not the file base name ("hello"). To do that the last line should call First(), not Last(), like this...

static string GetFileBaseNameUsingSplit(string path)
    string[] pathArr = path.Split('\\');
    string[] fileArr = pathArr.Last().Split('.');
    string fileBaseName = fileArr.First().ToString();

    return fileBaseName;

Having made that change, one thing to think about as far as improving this code is the amount of garbage it creates:

  • A string[] containing one string for each path segment in path
  • A string[] containing at least one string for each . in the last path segment in path

Therefore, extracting the base file name from the sample path "C:\Program Files\hello.txt" should produce the (temporary) objects "C:", "Program Files", "hello.txt", "hello", "txt", a string[3], and a string[2]. This could be significant if the method is called on a large number of paths. To improve this, we can search path ourselves to locate the start and end points of the base name and use those to create one new string...

static string GetFileBaseNameUsingSubstringUnsafe(string path)
    // Fails on paths with no file extension - DO NOT USE!!
    int startIndex = path.LastIndexOf('\\') + 1;
    int endIndex = path.IndexOf('.', startIndex);
    string fileBaseName = path.Substring(startIndex, endIndex - startIndex);

    return fileBaseName;

This is using the index of the character after the last \ as the start of the base name, and from there looking for the first . to use as the index of the character after the end of the base name. Is this shorter than the original code? Not quite. Is it a "smarter" solution? I think so. At least, it would be if not for the fact that...

As you can see from the comment, the previous method is problematic. Though it works if you assume all paths end with a file name with an extension, it will throw an exception if the path ends with \ (i.e. a directory path) or otherwise contains no extension in the last segment. To fix this, we need to add an extra check to account for when endIndex is -1 (i.e. . is not found)...

static string GetFileBaseNameUsingSubstring(string path)
    int startIndex = path.LastIndexOf('\\') + 1;
    int endIndex = path.IndexOf('.', startIndex);
    int length = (endIndex >= 0 ? endIndex : path.Length) - startIndex;
    string fileBaseName = path.Substring(startIndex, length);

    return fileBaseName;

Now this version is nowhere near shorter than the original, but it is more efficient and (now) correct, too.

As far as .NET methods that implement this functionality, many other answers suggest using Path.GetFileNameWithoutExtension(), which is an obvious, easy solution but does not produce the same results as the code in the question. There is a subtle but important difference between GetFileBaseNameUsingSplit() and Path.GetFileNameWithoutExtension() (GetFileBaseNameUsingPath() below): the former extracts everything before the first . and the latter extracts everything before the last .. This doesn't make a difference for the sample path in the question, but take a look at this table comparing the results of the above four methods when called with various paths...

Description Method Path Result
Single extension GetFileBaseNameUsingSplit() "C:\Program Files\hello.txt" "hello"
Single extension GetFileBaseNameUsingPath() "C:\Program Files\hello.txt" "hello"
Single extension GetFileBaseNameUsingSubstringUnsafe() "C:\Program Files\hello.txt" "hello"
Single extension GetFileBaseNameUsingSubstring() "C:\Program Files\hello.txt" "hello"

Double extension GetFileBaseNameUsingSplit() "C:\Program Files\hello.txt.ext" "hello"
Double extension GetFileBaseNameUsingPath() "C:\Program Files\hello.txt.ext" "hello.txt"
Double extension GetFileBaseNameUsingSubstringUnsafe() "C:\Program Files\hello.txt.ext" "hello"
Double extension GetFileBaseNameUsingSubstring() "C:\Program Files\hello.txt.ext" "hello"

No extension GetFileBaseNameUsingSplit() "C:\Program Files\hello" "hello"
No extension GetFileBaseNameUsingPath() "C:\Program Files\hello" "hello"
No extension GetFileBaseNameUsingSubstringUnsafe() "C:\Program Files\hello" EXCEPTION: Length cannot be less than zero. (Parameter 'length')
No extension GetFileBaseNameUsingSubstring() "C:\Program Files\hello" "hello"

Leading period GetFileBaseNameUsingSplit() "C:\Program Files\.hello.txt" ""
Leading period GetFileBaseNameUsingPath() "C:\Program Files\.hello.txt" ".hello"
Leading period GetFileBaseNameUsingSubstringUnsafe() "C:\Program Files\.hello.txt" ""
Leading period GetFileBaseNameUsingSubstring() "C:\Program Files\.hello.txt" ""

Trailing period GetFileBaseNameUsingSplit() "C:\Program Files\hello.txt." "hello"
Trailing period GetFileBaseNameUsingPath() "C:\Program Files\hello.txt." "hello.txt"
Trailing period GetFileBaseNameUsingSubstringUnsafe() "C:\Program Files\hello.txt." "hello"
Trailing period GetFileBaseNameUsingSubstring() "C:\Program Files\hello.txt." "hello"

Directory path GetFileBaseNameUsingSplit() "C:\Program Files\" ""
Directory path GetFileBaseNameUsingPath() "C:\Program Files\" ""
Directory path GetFileBaseNameUsingSubstringUnsafe() "C:\Program Files\" EXCEPTION: Length cannot be less than zero. (Parameter 'length')
Directory path GetFileBaseNameUsingSubstring() "C:\Program Files\" ""

Current file path GetFileBaseNameUsingSplit() "hello.txt" "hello"
Current file path GetFileBaseNameUsingPath() "hello.txt" "hello"
Current file path GetFileBaseNameUsingSubstringUnsafe() "hello.txt" "hello"
Current file path GetFileBaseNameUsingSubstring() "hello.txt" "hello"

Parent file path GetFileBaseNameUsingSplit() "..\hello.txt" "hello"
Parent file path GetFileBaseNameUsingPath() "..\hello.txt" "hello"
Parent file path GetFileBaseNameUsingSubstringUnsafe() "..\hello.txt" "hello"
Parent file path GetFileBaseNameUsingSubstring() "..\hello.txt" "hello"

Parent directory path GetFileBaseNameUsingSplit() ".." ""
Parent directory path GetFileBaseNameUsingPath() ".." "."
Parent directory path GetFileBaseNameUsingSubstringUnsafe() ".." ""
Parent directory path GetFileBaseNameUsingSubstring() ".." ""

...and you'll see that Path.GetFileNameWithoutExtension() yields different results when passed a path where the file name has a double extension or a leading and/or trailing .. You can try it for yourself with the following code...

using System;
using System.IO;
using System.Linq;
using System.Reflection;

namespace SO6921105
    internal class PathExtractionResult
        public string Description { get; set; }
        public string Method { get; set; }
        public string Path { get; set; }
        public string Result { get; set; }

    public static class Program
        private static string GetFileBaseNameUsingSplit(string path)
            string[] pathArr = path.Split('\\');
            string[] fileArr = pathArr.Last().Split('.');
            string fileBaseName = fileArr.First().ToString();

            return fileBaseName;

        private static string GetFileBaseNameUsingPath(string path)
            return Path.GetFileNameWithoutExtension(path);

        private static string GetFileBaseNameUsingSubstringUnsafe(string path)
            // Fails on paths with no file extension - DO NOT USE!!
            int startIndex = path.LastIndexOf('\\') + 1;
            int endIndex = path.IndexOf('.', startIndex);
            string fileBaseName = path.Substring(startIndex, endIndex - startIndex);

            return fileBaseName;

        private static string GetFileBaseNameUsingSubstring(string path)
            int startIndex = path.LastIndexOf('\\') + 1;
            int endIndex = path.IndexOf('.', startIndex);
            int length = (endIndex >= 0 ? endIndex : path.Length) - startIndex;
            string fileBaseName = path.Substring(startIndex, length);

            return fileBaseName;

        public static void Main()
            MethodInfo[] testMethods = typeof(Program).GetMethods(BindingFlags.NonPublic | BindingFlags.Static)
                .Where(method => method.Name.StartsWith("GetFileBaseName"))
            var inputs = new[] {
                new { Description = "Single extension",      Path = @"C:\Program Files\hello.txt"     },
                new { Description = "Double extension",      Path = @"C:\Program Files\hello.txt.ext" },
                new { Description = "No extension",          Path = @"C:\Program Files\hello"         },
                new { Description = "Leading period",        Path = @"C:\Program Files\.hello.txt"    },
                new { Description = "Trailing period",       Path = @"C:\Program Files\hello.txt."    },
                new { Description = "Directory path",        Path = @"C:\Program Files\"              },
                new { Description = "Current file path",     Path = "hello.txt"                       },
                new { Description = "Parent file path",      Path = @"..\hello.txt"                   },
                new { Description = "Parent directory path", Path = ".."                              }
            PathExtractionResult[] results = inputs
                    input => testMethods.Select(
                        method => {
                            string result;

                                string returnValue = (string) method.Invoke(null, new object[] { input.Path });

                                result = $"\"{returnValue}\"";
                            catch (Exception ex)
                                if (ex is TargetInvocationException)
                                    ex = ex.InnerException;
                                result = $"EXCEPTION: {ex.Message}";

                            return new PathExtractionResult() {
                                Description = input.Description,
                                Method = $"{method.Name}()",
                                Path = $"\"{input.Path}\"",
                                Result = result
            const int ColumnPadding = 2;
            ResultWriter writer = new ResultWriter(Console.Out) {
                DescriptionColumnWidth = results.Max(output => output.Description.Length) + ColumnPadding,
                MethodColumnWidth = results.Max(output => output.Method.Length) + ColumnPadding,
                PathColumnWidth = results.Max(output => output.Path.Length) + ColumnPadding,
                ResultColumnWidth = results.Max(output => output.Result.Length) + ColumnPadding,
                ItemLeftPadding = " ",
                ItemRightPadding = " "
            PathExtractionResult header = new PathExtractionResult() {
                Description = nameof(PathExtractionResult.Description),
                Method = nameof(PathExtractionResult.Method),
                Path = nameof(PathExtractionResult.Path),
                Result = nameof(PathExtractionResult.Result)

            foreach (IGrouping<string, PathExtractionResult> resultGroup in results.GroupBy(result => result.Description))
                foreach (PathExtractionResult result in resultGroup)

    internal class ResultWriter
        private const char DividerChar = '-';
        private const char SeparatorChar = '|';

        private TextWriter Writer { get; }

        public ResultWriter(TextWriter writer)
            Writer = writer ?? throw new ArgumentNullException(nameof(writer));

        public int DescriptionColumnWidth { get; set; }

        public int MethodColumnWidth { get; set; }

        public int PathColumnWidth { get; set; }

        public int ResultColumnWidth { get; set; }

        public string ItemLeftPadding { get; set; }

        public string ItemRightPadding { get; set; }

        public void WriteResult(PathExtractionResult result)

        public void WriteDivider()
                new string(DividerChar, DescriptionColumnWidth),
                new string(DividerChar, MethodColumnWidth),
                new string(DividerChar, PathColumnWidth),
                new string(DividerChar, ResultColumnWidth)

        private void WriteLine(string description, string method, string path, string result)

TL;DR The code in the question does not behave as many seem to expect in some corner cases. If you're going to write your own path manipulation code, be sure to take into consideration...

  • you define a "filename without extension" (is it everything before the first . or everything before the last .?)
  • ...files with multiple extensions
  • ...files with no extension
  • ...files with a leading .
  • ...files with a trailing . (probably not something you'll ever encounter on Windows, but they are possible)
  • ...directories with an "extension" or that otherwise contain a .
  • ...paths that end with a \
  • ...relative paths

Not all file paths follow the usual formula of X:\Directory\File.ext!

PHP PDO returning single row

If you want just a single field, you could use fetchColumn instead of fetch -

Activity restart on rotation Android

you need to use the onSavedInstanceState method to store all the value to its parameter is has that is bundle

    public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
        super.onSaveInstanceState(outState, outPersistentState);

and use

    protected void onRestoreInstanceState(Bundle savedInstanceState) {

to retrive and set the value to view objects it will handles the screen rotations

jQuery if statement to check visibility


if ($('#column-left form:visible').length > 0) { ...

Java ArrayList of Arrays?

Should be

private ArrayList<String[]> action = new ArrayList<String[]>();
action.add(new String[2]);

You can't specify the size of the array within the generic parameter, only add arrays of specific size to the list later. This also means that the compiler can't guarantee that all sub-arrays be of the same size, it must be ensured by you.

A better solution might be to encapsulate this within a class, where you can ensure the uniform size of the arrays as a type invariant.

Converting HTML to Excel?

So long as Excel can open the file, the functionality to change the format of the opened file is built in.

To convert an .html file, open it using Excel (File - Open) and then save it as a .xlsx file from Excel (File - Save as).

To do it using VBA, the code would look like this:

Sub Open_HTML_Save_XLSX()

    Workbooks.Open Filename:="C:\Temp\Example.html"
    ActiveWorkbook.SaveAs Filename:= _
        "C:\Temp\Example.xlsx", FileFormat:= _

End Sub

jquery: get elements by class name and add css to each of them

You can try this

 $('div.easy_editor').css({'border-width':'9px', 'border-style':'solid', 'border-color':'red'});

The $('div.easy_editor') refers to a collection of all divs that have the class easy editor already. There is no need to use each() unless there was some function that you wanted to run on each. The css() method actually applies to all the divs you find.

How to change the color of winform DataGridview header?

If you want to change a color to single column try this:

 dataGridView1.EnableHeadersVisualStyles = false;
 dataGridView1.Columns[0].HeaderCell.Style.BackColor = Color.Magenta;
 dataGridView1.Columns[1].HeaderCell.Style.BackColor = Color.Yellow;

Excel is not updating cells, options > formula > workbook calculation set to automatic

The field is formatted as 'Text', which means that formulas aren't evaluated. Change the formatting to something else, press F2 on the cell and Enter.

Using ORDER BY and GROUP BY together

One way to do this that correctly uses group by:

select l.* 
from table l
inner join (
    m_id, max(timestamp) as latest 
  from table 
  group by m_id
) r
  on l.timestamp = r.latest and l.m_id = r.m_id
order by timestamp desc

How this works:

  • selects the latest timestamp for each distinct m_id in the subquery
  • only selects rows from table that match a row from the subquery (this operation -- where a join is performed, but no columns are selected from the second table, it's just used as a filter -- is known as a "semijoin" in case you were curious)
  • orders the rows

Javascript call() & apply() vs bind()?

Use .bind() when you want that function to later be called with a certain context, useful in events. Use .call() or .apply() when you want to invoke the function immediately, and modify the context.

Call/apply call the function immediately, whereas bind returns a function that, when later executed, will have the correct context set for calling the original function. This way you can maintain context in async callbacks and events.

I do this a lot:

function MyObject(element) {
    this.elm = element;

    element.addEventListener('click', this.onClick.bind(this), false);

MyObject.prototype.onClick = function(e) {
     var t=this;  //do something with [t]...
    //without bind the context of this function wouldn't be a MyObject
    //instance as you would normally expect.

I use it extensively in Node.js for async callbacks that I want to pass a member method for, but still want the context to be the instance that started the async action.

A simple, naive implementation of bind would be like:

Function.prototype.bind = function(ctx) {
    var fn = this;
    return function() {
        fn.apply(ctx, arguments);

There is more to it (like passing other args), but you can read more about it and see the real implementation on the MDN.

Hope this helps.

How to convert a huge list-of-vector to a matrix more efficiently?

You can also use,

output <- as.matrix(

The memory usage is very similar to

output <- matrix(unlist(z), ncol = 10, byrow = TRUE)

Which can be verified, with mem_changed() from library(pryr).

JavaScript OR (||) variable assignment explanation

It means that if x is set, the value for z will be x, otherwise if y is set then its value will be set as the z's value.

it's the same as

  z = x;
  z = y;

It's possible because logical operators in JavaScript doesn't return boolean values but the value of the last element needed to complete the operation (in an OR sentence it would be the first non-false value, in an AND sentence it would be the last one). If the operation fails, then false is returned.

adding a datatable in a dataset

you have to set the tableName you want to your dtimage that is for instance



it will be reflected in dataset because dataset is a container of your datatable dtimage and you have a reference on your dtimage

The declared package does not match the expected package ""

I was using Spring Tool Suite 4. Not able to figure out the issue. The directory structure was according to the package name.

But cleaning the project helped me.

How can I get a resource "Folder" from inside my jar File?

Another solution, you can do it using ResourceLoader like this:


private ResourceLoader resourceLoader;


Resource resource = resourceLoader.getResource("classpath:/path/to/you/dir");
File file = resource.getFile();
Iterator<File> fi = FileUtils.iterateFiles(file, null, true);
while(fi.hasNext()) {

JQuery: detect change in input field

You can use jQuery change() function

  //your codes

There are examples on how to use it on the API Page:

System.Net.WebException: The remote name could not be resolved:

I had a similar issue when trying to access a service (old ASMX service). The call would work when accessing via an IP however when calling with an alias I would get the remote name could not be resolved.

Added the following to the config and it resolved the issue:

    <defaultProxy enabled="true">

handle textview link click in my android app

public static void setTextViewFromHtmlWithLinkClickable(TextView textView, String text) {
    Spanned result;
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
        result = Html.fromHtml(text, Html.FROM_HTML_MODE_LEGACY);
    } else {
        result = Html.fromHtml(text);

Java generics - get class?

Short answer: You can't.

Long answer:

Due to the way generics is implemented in Java, the generic type T is not kept at runtime. Still, you can use a private data member:

public class Foo<T> 
    private Class<T> type;

    public Foo(Class<T> type) { this.type = type; } 

Usage example:

Foo<Integer> test = new Foo<Integer>(Integer.class);

Application Error - The connection to the server was unsuccessful. (file:///android_asset/www/index.html)

Here is the working solution

create a new page main.html


<!doctype html>

change the following in




Now build your application and it works on any slow connection


NOTE: This is a workaround I found in 2013.

What does the percentage sign mean in Python

x % n == 0
which means the x/n and the value of reminder will taken as a result and compare with zero....

example: 4/5==0

4/5 reminder is 4

4==0 (False)

Numpy Resize/Rescale Image

SciPy's imresize() method was another resize method, but it will be removed starting with SciPy v 1.3.0 . SciPy refers to PIL image resize method: Image.resize(size, resample=0)

size – The requested size in pixels, as a 2-tuple: (width, height).
resample – An optional resampling filter. This can be one of PIL.Image.NEAREST (use nearest neighbour), PIL.Image.BILINEAR (linear interpolation), PIL.Image.BICUBIC (cubic spline interpolation), or PIL.Image.LANCZOS (a high-quality downsampling filter). If omitted, or if the image has mode “1” or “P”, it is set PIL.Image.NEAREST.

Link here:

How can I send mail from an iPhone application

Heres a Swift version:

import MessageUI

class YourVC: UIViewController {
    override func viewDidLoad() {
        if MFMailComposeViewController.canSendMail() {
            var emailTitle = "Vea Software Feedback"
            var messageBody = "Vea Software! :) "
            var toRecipents = ["[email protected]"]
            var mc:MFMailComposeViewController = MFMailComposeViewController()
            mc.mailComposeDelegate = self
            mc.setMessageBody(messageBody, isHTML: false)
            self.presentViewController(mc, animated: true, completion: nil)
        } else {
            println("No email account found")

extension YourVC: MFMailComposeViewControllerDelegate {
    func mailComposeController(controller: MFMailComposeViewController!, didFinishWithResult result: MFMailComposeResult, error: NSError!) {
        switch result.value {
        case MFMailComposeResultCancelled.value:
            println("Mail Cancelled")
        case MFMailComposeResultSaved.value:
            println("Mail Saved")
        case MFMailComposeResultSent.value:
            println("Mail Sent")
        case MFMailComposeResultFailed.value:
            println("Mail Failed")
        self.dismissViewControllerAnimated(false, completion: nil)


How to write hello world in assembler under Windows?

These are Win32 and Win64 examples using Windows API calls. They are for MASM rather than NASM, but have a look at them. You can find more details in this article.

This uses MessageBox instead of printing to stdout.

Win32 MASM

;---ASM Hello World Win32 MessageBox

.model flat, stdcall
includelib kernel32.lib
includelib user32.lib

title db 'Win32', 0
msg db 'Hello World', 0


push 0            ; uType = MB_OK
push offset title ; LPCSTR lpCaption
push offset msg   ; LPCSTR lpText
push 0            ; hWnd = HWND_DESKTOP
call MessageBoxA
push eax          ; uExitCode = MessageBox(...)
call ExitProcess

End Main

Win64 MASM

;---ASM Hello World Win64 MessageBox

extrn MessageBoxA: PROC
extrn ExitProcess: PROC

title db 'Win64', 0
msg db 'Hello World!', 0

main proc
  sub rsp, 28h  
  mov rcx, 0       ; hWnd = HWND_DESKTOP
  lea rdx, msg     ; LPCSTR lpText
  lea r8,  title   ; LPCSTR lpCaption
  mov r9d, 0       ; uType = MB_OK
  call MessageBoxA
  add rsp, 28h  
  mov ecx, eax     ; uExitCode = MessageBox(...)
  call ExitProcess
main endp


To assemble and link these using MASM, use this for 32-bit executable:

ml.exe [filename] /link /subsystem:windows 
/defaultlib:kernel32.lib /defaultlib:user32.lib /entry:Main

or this for 64-bit executable:

ml64.exe [filename] /link /subsystem:windows 
/defaultlib:kernel32.lib /defaultlib:user32.lib /entry:main

Why does x64 Windows need to reserve 28h bytes of stack space before a call? That's 32 bytes (0x20) of shadow space aka home space, as required by the calling convention. And another 8 bytes to re-align the stack by 16, because the calling convention requires RSP be 16-byte aligned before a call. (Our main's caller (in the CRT startup code) did that. The 8-byte return address means that RSP is 8 bytes away from a 16-byte boundary on entry to a function.)

Shadow space can be used by a function to dump its register args next to where any stack args (if any) would be. A system call requires 30h (48 bytes) to also reserve space for r10 and r11 in addition to the previously mentioned 4 registers. But DLL calls are just function calls, even if they're wrappers around syscall instructions.

Fun fact: non-Windows, i.e. the x86-64 System V calling convention (e.g. on Linux) doesn't use shadow space at all, and uses up to 6 integer/pointer register args, and up to 8 FP args in XMM registers.

Using MASM's invoke directive (which knows the calling convention), you can use one ifdef to make a version of this which can be built as 32-bit or 64-bit.

ifdef rax
    extrn MessageBoxA: PROC
    extrn ExitProcess: PROC
    .model flat, stdcall
    includelib kernel32.lib
    includelib user32.lib
caption db 'WinAPI', 0
text    db 'Hello World', 0
main proc
    invoke MessageBoxA, 0, offset text, offset caption, 0
    invoke ExitProcess, eax
main endp

The macro variant is the same for both, but you won't learn assembly this way. You'll learn C-style asm instead. invoke is for stdcall or fastcall while cinvoke is for cdecl or variable argument fastcall. The assembler knows which to use.

You can disassemble the output to see how invoke expanded.

Google Play on Android 4.0 emulator

Download Google apps (GoogleLoginService.apk , GoogleServicesFramework.apk , Phonesky.apk)
from here.

Start your emulator:

emulator -avd VM_NAME_HERE -partition-size 500 -no-audio -no-boot-anim

Then use the following commands:

# Remount in rw mode.
# NOTE: more recent system.img files are ext4, not yaffs2
adb shell mount -o remount,rw -t yaffs2 /dev/block/mtdblock0 /system

# Allow writing to app directory on system partition
adb shell chmod 777 /system/app

# Install following apk
adb push GoogleLoginService.apk /system/app/.
adb push GoogleServicesFramework.apk /system/app/.
adb push Phonesky.apk /system/app/. # Vending.apk in older versions
adb shell rm /system/app/SdkSetup*

What is "export default" in JavaScript?

What is “export default” in JavaScript?

In default export the naming of import is completely independent and we can use any name we like.

I will illustrate this line with a simple example.

Let’s say we have three modules and an index.html file:

  • modul.js
  • modul2.js
  • modul3.js
  • index.html

File modul.js

export function hello() {
    console.log("Modul: Saying hello!");

export let variable = 123;

File modul2.js

export function hello2() {
    console.log("Module2: Saying hello for the second time!");

export let variable2 = 456;


export default function hello3() {
    console.log("Module3: Saying hello for the third time!");

File index.html

<script type="module">
import * as mod from './modul.js';
import {hello2, variable2} from './modul2.js';
import blabla from './modul3.js'; // ! Here is the important stuff - we name the variable for the module as we like

console.log("Module: " + mod.variable);

console.log("Module2: " + variable2);


The output is:

modul.js:2:10   -> Modul: Saying hello!
index.html:7:9  -> Module: 123
modul2.js:2:10  -> Module2: Saying hello for the second time!
index.html:10:9 -> Module2: 456
modul3.js:2:10  -> Module3: Saying hello for the third time!

So the longer explanation is:

'export default' is used if you want to export a single thing for a module.

So the thing that is important is "import blabla from './modul3.js'" - we could say instead:

"import pamelanderson from './modul3.js" and then pamelanderson();. This will work just fine when we use 'export default' and basically this is it - it allows us to name it whatever we like when it is default.

P.S.: If you want to test the example - create the files first, and then allow CORS in the browser -> if you are using Firefox type in the URL of the browser: about:config -> Search for "privacy.file_unique_origin" -> change it to "false" -> open index.html -> press F12 to open the console and see the output -> Enjoy and don't forget to return the CORS settings to default.

P.S.2: Sorry for the silly variable naming

More information is in link2medium and link2mdn.

Set drawable size programmatically

Got this working using LayerDrawable:

fun getResizedDrawable(drawable: Drawable, scale: Float) =
    LayerDrawable(arrayOf(drawable)).also { it.setLayerSize(0, (drawable.intrinsicWidth * scale).toInt(), (drawable.intrinsicHeight * scale).toInt()) }

fun getResizedDrawable(drawable: Drawable, scalex: Float, scaleY: Float) =
    LayerDrawable(arrayOf(drawable)).also { it.setLayerSize(0, (drawable.intrinsicWidth * scalex).toInt(), (drawable.intrinsicHeight * scaleY).toInt()) }

fun getResizedDrawableUsingSpecificSize(drawable: Drawable, newWidth: Int, newHeight: Int) =
    LayerDrawable(arrayOf(drawable)).also { it.setLayerSize(0, newWidth, newHeight) }


val drawable = AppCompatResources.getDrawable(this, android.R.drawable.sym_def_app_icon)!!
val resizedDrawable = getResizedDrawable(drawable, 3f)
textView.setCompoundDrawablesWithIntrinsicBounds(resizedDrawable, null, null, null)

XCOPY switch to create specified directory if it doesn't exist?

Answer to use "/I" is working but with little trick - in target you must end with character \ to tell xcopy that target is directory and not file!


xcopy "$(TargetDir)$(TargetName).dll" "$(SolutionDir)_DropFolder" /F /R /Y /I

does not work and return code 2, but this one:

xcopy "$(TargetDir)$(TargetName).dll" "$(SolutionDir)_DropFolder\" /F /R /Y /I

Command line arguments used in my sample:

/F - Displays full source & target file names

/R - This will overwrite read-only files

/Y - Suppresses prompting to overwrite an existing file(s)

/I - Assumes that destination is directory (but must ends with \)

How to convert a boolean array to an int array

I know you asked for non-looping solutions, but the only solutions I can come up with probably loop internally anyway:



[i*1 for i in y]


import numpy

127 Return code from $?

If the IBM mainframe JCL has some extra characters or numbers at the end of the name of unix script being called then it can throw such error.

How do I read / convert an InputStream into a String in Java?

if You need to convert the string to a specific character set w/o external libraries then:

public String convertStreamToString(InputStream is) throws IOException {
  try( ByteArrayOutputStream baos = new ByteArrayOutputStream(); ) {
    is.transferTo( baos );
    return baos.toString( StandardCharsets.UTF_8 );

Importing lodash into angular2 + typescript application

Step 1: Modify package.json file to include lodash in the dependencies.

  "dependencies": {
"@angular/common":  "2.0.0-rc.1",
"@angular/compiler":  "2.0.0-rc.1",
"@angular/core":  "2.0.0-rc.1",
"@angular/http":  "2.0.0-rc.1",
"@angular/platform-browser":  "2.0.0-rc.1",
"@angular/platform-browser-dynamic":  "2.0.0-rc.1",
"@angular/router":  "2.0.0-rc.1",
"@angular/router-deprecated":  "2.0.0-rc.1",
"@angular/upgrade":  "2.0.0-rc.1",
"systemjs": "0.19.27",
"es6-shim": "^0.35.0",
"reflect-metadata": "^0.1.3",
"rxjs": "5.0.0-beta.6",
"zone.js": "^0.6.12",
"angular2-in-memory-web-api": "0.0.7",
"bootstrap": "^3.3.6"  }

Step 2:I am using SystemJs module loader in my angular2 application. So I would be modifying the systemjs.config.js file to map lodash.

(function(global) {

// map tells the System loader where to look for things
var map = {
    'app':                        'app', // 'dist',
    'rxjs':                       'node_modules/rxjs',
    'angular2-in-memory-web-api': 'node_modules/angular2-in-memory-web-api',
    '@angular':                   'node_modules/@angular',
    'lodash':                    'node_modules/lodash'

// packages tells the System loader how to load when no filename and/or no extension
var packages = {
    'app':                        { main: 'main.js',  defaultExtension: 'js' },
    'rxjs':                       { defaultExtension: 'js' },
    'angular2-in-memory-web-api': { defaultExtension: 'js' },
    'lodash':                    {main:'index.js', defaultExtension:'js'}

var packageNames = [

// add package entries for angular packages in the form '@angular/common': { main: 'index.js', defaultExtension: 'js' }
packageNames.forEach(function(pkgName) {
    packages[pkgName] = { main: 'index.js', defaultExtension: 'js' };

var config = {
    map: map,
    packages: packages

// filterSystemConfig - index.html's chance to modify config before we register it.
if (global.filterSystemConfig) { global.filterSystemConfig(config); }


Step 3: Now do npm install

Step 4: To use lodash in your file.

import * as _ from 'lodash';
let firstIndexOfElement=_.findIndex(array,criteria);

Watching variables contents in Eclipse IDE

You can do so by these ways.

Add watchpoint and while debugging you can see variable in debugger window perspective under variable tab. OR Add System.out.println("variable = " + variable); and see in console.

Setting a backgroundImage With React Inline Styles

You can try this with by adding backticks on whole url

style={{backgroundImage:url(${val.image || ''} ) }}

subsampling every nth entry in a numpy array

You can use numpy's slicing, simply start:stop:step.

>>> xs
array([1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4])
>>> xs[1::4]
array([2, 2, 2])

This creates a view of the the original data, so it's constant time. It'll also reflect changes to the original array and keep the whole original array in memory:

>>> a
array([1, 2, 3, 4, 5])
>>> b = a[::2]         # O(1), constant time
>>> b[:] = 0           # modifying the view changes original array
>>> a                  # original array is modified
array([0, 2, 0, 4, 0])

so if either of the above things are a problem, you can make a copy explicitly:

>>> a
array([1, 2, 3, 4, 5])
>>> b = a[::2].copy()  # explicit copy, O(n)
>>> b[:] = 0           # modifying the copy
>>> a                  # original is intact
array([1, 2, 3, 4, 5])

This isn't constant time, but the result isn't tied to the original array. The copy also contiguous in memory, which can make some operations on it faster.

Extending from two classes

Yea, as everyone else wrote, you cannot do multiple inheritance in Java. If you have two classes from which you'd like to use code, you'd typically just subclass one (say class A). For class B, you abstract the important methods of it to an interface BInterface (ugly name, but you get the idea), then say Main extends A implements BInterface. Inside, you can instantiate an object of class B and implement all methods of BInterface by calling the corresponding functions of B.

This changes the "is-a" relationship to a "has-a" relationship as your Main now is an A, but has a B. Depending on your use case, you might even make that change explicit by removing the BInterface from your A class and instead provide a method to access your B object directly.

Does a "Find in project..." feature exist in Eclipse IDE?

yes, but you need to open the global search panel. to do so, press the binoculars icon on the top right corner of the IDE.

you can even filter searches by function identifiers, method scopes an etc...


You technically have two options when speaking of ISO dates.

In general, if you're filtering specifically on Date values alone OR looking to persist date in a neutral fashion. Microsoft recommends using the language neutral format of ymd or y-m-d. Which are both valid ISO formats.

Note that the form '2007-02-12' is considered language-neutral only for the data types DATE, DATETIME2, and DATETIMEOFFSET.

Because of this, your safest bet is to persist/filter based on the always netural ymd format.

The code:

select convert(char(10), getdate(), 126) -- ISO YYYY-MM-DD
select convert(char(8), getdate(), 112) -- ISO YYYYMMDD (safest)

How to prevent SIGPIPEs (or handle them properly)

Another method is to change the socket so it never generates SIGPIPE on write(). This is more convenient in libraries, where you might not want a global signal handler for SIGPIPE.

On most BSD-based (MacOS, FreeBSD...) systems, (assuming you are using C/C++), you can do this with:

int set = 1;
setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, (void *)&set, sizeof(int));

With this in effect, instead of the SIGPIPE signal being generated, EPIPE will be returned.

Is there a "standard" format for command line/shell help text?

yes, you're on the right track.

yes, square brackets are the usual indicator for optional items.

Typically, as you have sketched out, there is a commandline summary at the top, followed by details, ideally with samples for each option. (Your example shows lines in between each option description, but I assume that is an editing issue, and that your real program outputs indented option listings with no blank lines in between. This would be the standard to follow in any case.)

A newer trend, (maybe there is a POSIX specification that addresses this?), is the elimination of the man page system for documentation, and including all information that would be in a manpage as part of the program --help output. This extra will include longer descriptions, concepts explained, usage samples, known limitations and bugs, how to report a bug, and possibly a 'see also' section for related commands.

I hope this helps.

Databinding an enum property to a ComboBox in WPF

I don't know if it is possible in XAML-only but try the following:

Give your ComboBox a name so you can access it in the codebehind: "typesComboBox1"

Now try the following

typesComboBox1.ItemsSource = Enum.GetValues(typeof(ExampleEnum));

reading external sql script in python

A very simple way to read an external script into an sqlite database in python is using executescript():

import sqlite3

conn = sqlite3.connect('csc455_HW3.db')

with open('ZooDatabase.sql', 'r') as sql_file: