Programs & Examples On #Regex group

Regex groups are created by placing part of a regular expression inside parentheses. Groups allows to apply a quantifier to the entire group or to restrict alternation to part of the regex. Besides grouping part of a regular expression together, parentheses also create a numbered capturing group. It stores the part of the string matched by the part of the regular expression inside the parentheses.

Named regular expression group "(?P<group_name>regexp)": what does "P" stand for?

Python Extension. From the Python Docs:

The solution chosen by the Perl developers was to use (?...) as the extension syntax. ? immediately after a parenthesis was a syntax error because the ? would have nothing to repeat, so this didn’t introduce any compatibility problems. The characters immediately after the ? indicate what extension is being used, so (?=foo) is one thing (a positive lookahead assertion) and (?:foo) is something else (a non-capturing group containing the subexpression foo).

Python supports several of Perl’s extensions and adds an extension syntax to Perl’s extension syntax.If the first character after the question mark is a P, you know that it’s an extension that’s specific to Python

Can I replace groups in Java regex?

You can use matcher.start() and matcher.end() methods to get the group positions. So using this positions you can easily replace any text.

RegEx to extract all matches from string using RegExp.exec

I would definatly recommend using the String.match() function, and creating a relevant RegEx for it. My example is with a list of strings, which is often necessary when scanning user inputs for keywords and phrases.

    // 1) Define keywords
    var keywords = ['apple', 'orange', 'banana'];

    // 2) Create regex, pass "i" for case-insensitive and "g" for global search
    regex = new RegExp("(" + keywords.join('|') + ")", "ig");
    => /(apple|orange|banana)/gi

    // 3) Match it against any string to get all matches 
    "Test string for ORANGE's or apples were mentioned".match(regex);
    => ["ORANGE", "apple"]

Hope this helps!

RegEx for matching UK Postcodes

I had a look into some of the answers above and I'd recommend against using the pattern from @Dan's answer (c. Dec 15 '10), since it incorrectly flags almost 0.4% of valid postcodes as invalid, while the others do not.

Ordnance Survey provide service called Code Point Open which:

contains a list of all the current postcode units in Great Britain

I ran each of the regexs above against the full list of postcodes (Jul 6 '13) from this data using grep:

cat CSV/*.csv |
    # Strip leading quotes
    sed -e 's/^"//g' |
    # Strip trailing quote and everything after it
    sed -e 's/".*//g' |
    # Strip any spaces
    sed -E -e 's/ +//g' |
    # Find any lines that do not match the expression
    grep --invert-match --perl-regexp "$pattern"

There are 1,686,202 postcodes total.

The following are the numbers of valid postcodes that do not match each $pattern:

# => 6016 (0.36%)
'^(GIR ?0AA|[A-PR-UWYZ]([0-9]{1,2}|([A-HK-Y][0-9]([0-9ABEHMNPRV-Y])?)|[0-9][A-HJKPS-UW]) ?[0-9][ABD-HJLNP-UW-Z]{2})$'
# => 0
# => 0

Of course, these results only deal with valid postcodes that are incorrectly flagged as invalid. So:

# => 0

I'm saying nothing about which pattern is the best regarding filtering out invalid postcodes.

How to capture multiple repeated groups?

Sorry, not Swift, just a proof of concept in the closest language at hand.

// JavaScript POC. Output:
// Matches:  ["GOODBYE","CRUEL","WORLD","IM","LEAVING","U","TODAY"]

let matches = [];

function recurse(str, matches) {
    let regex = /^((,?([A-Z]+))+)$/gm
    let m
    while ((m = regex.exec(str)) !== null) {
        return str.replace(m[2], '')
    return "bzzt!"

while ((str = recurse(str, matches)) != "bzzt!") ;
console.log("Matches: ", JSON.stringify(matches))

Note: If you were really going to use this, you would use the position of the match as given by the regex match function, not a string replace.

What is a non-capturing group in regular expressions?

Groups that capture you can use later on in the regex to match OR you can use them in the replacement part of the regex. Making a non-capturing group simply exempts that group from being used for either of these reasons.

Non-capturing groups are great if you are trying to capture many different things and there are some groups you don't want to capture.

Thats pretty much the reason they exist. While you are learning about groups, learn about Atomic Groups, they do a lot! There is also lookaround groups but they are a little more complex and not used so much.

Example of using later on in the regex (backreference):

<([A-Z][A-Z0-9]*)\b[^>]*>.*?</\1> [ Finds an xml tag (without ns support) ]

([A-Z][A-Z0-9]*) is a capturing group (in this case it is the tagname)

Later on in the regex is \1 which means it will only match the same text that was in the first group (the ([A-Z][A-Z0-9]*) group) (in this case it is matching the end tag).

Insert text into textarea with jQuery

    insertAtCaret: function(myValue) {
        var elemSelected = window.getSelection();
        if(elemSelected) {
            var startPos = elemSelected.getRangeAt(0).startOffset;
            var endPos = elemSelected.getRangeAt(0).endOffset;
            this.val(this.val().substring(0, startPos)+myValue+this.val().substring(endPos,this.val().length));
        } else {
            this.val(this.val()+ myValue) ;

JavaScript get child element

Try this one:

function show_sub(cat) {
    var parent = cat,
    sub = parent.getElementsByClassName('sub');
    if (sub[0].style.display == 'inline'){
        sub[0].style.display = 'none';
    else {
        sub[0].style.display = 'inline';

document.getElementById('cat').onclick = function(){

and use this for IE6 & 7

if (typeof document.getElementsByClassName!='function') {
    document.getElementsByClassName = function() {
        var elms = document.getElementsByTagName('*');
        var ei = new Array();
        for (i=0;i<elms.length;i++) {
            if (elms[i].getAttribute('class')) {
               ecl = elms[i].getAttribute('class').split(' ');
                for (j=0;j<ecl.length;j++) {
                    if (ecl[j].toLowerCase() == arguments[0].toLowerCase()) {
            } else if (elms[i].className) {
                ecl = elms[i].className.split(' ');
                for (j=0;j<ecl.length;j++) {
                    if (ecl[j].toLowerCase() == arguments[0].toLowerCase()) {
        return ei;

Why has it failed to load main-class manifest attribute from a JAR file?


java -cp .:mail-1.4.1.jar JavaxMailHTML 

no need to have manifest file.

Extract specific columns from delimited file using Awk

Not using awk but the simplest way I was able to get this done was to just use csvtool. I had other use cases as well to use csvtool and it can handle the quotes or delimiters appropriately if they appear within the column data itself.

csvtool format '%(2)\n' input.csv
csvtool format '%(2),%(3),%(4)\n' input.csv

Replacing 2 with the column number will effectively extract the column data you are looking for.

Metadata file '.dll' could not be found

For me, it was trying to find a DLL in a path that used to contain the Project, but we'd moved it to a new directory. The Solution had the correct path to the Project, but Visual Studio somehow kept looking in the old location.

Solution: Rename each problem Project - just add a character or whatever - then rename it back to its original name.

This must reset some global cache of some kind in Visual Studio, because this clears both this issue up and several like it, while things like Clean do not.

Getting "file not found" in Bridging Header when importing Objective-C frameworks into Swift project

We encountered the same error message, with a completely different cause.


  • App target, all Obj-C code
  • Unit Test target with a single swift test case & a bridging header referring to app code

When we added the second swift test case, after a clean (or on a team mate's machine), we saw this error when building the unit test target.

It was fixed by adding a dummy Obj-C class to the unit test target.

How to check Spark Version

According to the Cloudera documentation - What's New in CDH 5.7.0 it includes Spark 1.6.0.

What is for Python what 'explode' is for PHP?

Choose one you need:

>>> s = "Rajasekar SP  def"
>>> s.split(' ')
['Rajasekar', 'SP', '', 'def']
>>> s.split()
['Rajasekar', 'SP', 'def']
>>> s.partition(' ')
('Rajasekar', ' ', 'SP  def')

str.split and str.partition

Find out whether radio button is checked with JQuery?

You'd have to bind the click event of the checkbox, as the change event doesn't work in IE.

    // if ($(this).is(':checked')) alert('is checked'); 
    alert('check-checky-check was changed');

Now when you programmatically change the state, you have to trigger this event also:

$('#radio_button').attr("checked", "checked");

Multi-Column Join in Hibernate/JPA Annotations

If this doesn't work I'm out of ideas. This way you get the 4 columns in both tables (as Bar owns them and Foo uses them to reference Bar) and the generated IDs in both entities. The set of 4 columns has to be unique in Bar so the many-to-one relation doesn't become a many-to-many.

public class AnEmbeddedObject
    @Column(name = "column_1")
    private Long column1;
    @Column(name = "column_2")
    private Long column2;
    @Column(name = "column_3")
    private Long column3;
    @Column(name = "column_4")
    private Long column4;

public class Foo
    @Column(name = "id")
    @GeneratedValue(generator = "seqGen")
    @SequenceGenerator(name = "seqGen", sequenceName = "FOO_ID_SEQ", allocationSize = 1)
    private Long id;
    @ManyToOne(fetch = FetchType.LAZY)
        @JoinColumn(name = "column_1", referencedColumnName = "column_1"),
        @JoinColumn(name = "column_2", referencedColumnName = "column_2"),
        @JoinColumn(name = "column_3", referencedColumnName = "column_3"),
        @JoinColumn(name = "column_4", referencedColumnName = "column_4")
    private Bar bar;

@Table(uniqueConstraints = @UniqueConstraint(columnNames = {
public class Bar
    @Column(name = "id")
    @GeneratedValue(generator = "seqGen")
    @SequenceGenerator(name = "seqGen", sequenceName = "BAR_ID_SEQ", allocationSize = 1)
    private Long id;
    private AnEmbeddedObject anEmbeddedObject;

What do *args and **kwargs mean?

Another good use for *args and **kwargs: you can define generic "catch all" functions, which is great for decorators where you return such a wrapper instead of the original function.

An example with a trivial caching decorator:

import pickle, functools
def cache(f):
  _cache = {}
  def wrapper(*args, **kwargs):
    key = pickle.dumps((args, kwargs))
    if key not in _cache:
      _cache[key] = f(*args, **kwargs) # call the wrapped function, save in cache
    return _cache[key] # read value from cache
  functools.update_wrapper(wrapper, f) # update wrapper's metadata
  return wrapper

import time
def foo(n):
  return n*2

foo(10) # first call with parameter 10, sleeps
foo(10) # returns immediately

How can I check the size of a collection within a Django template?

A list is considered to be False if it has no elements, so you can do something like this:

{% if mylist %}
    <p>I have a list!</p>
{% else %}
    <p>I don't have a list!</p>
{% endif %}

How might I find the largest number contained in a JavaScript array?

The easiest syntax, with the new spread operator:

var arr = [1, 2, 3];
var max = Math.max(...arr);

Source : Mozilla MDN

forcing web-site to show in landscape mode only

I had to play with the widths of my main containers:

html {
  @media only screen and (orientation: portrait) and (max-width: 555px) {
    transform: rotate(90deg);
    width: calc(155%);
    .content {
      width: calc(155%);

Writing files in Node.js

You can write in a file by the following code example:

var data = [{ 'test': '123', 'test2': 'Lorem Ipsem ' }]; + '/data/topplayers.json', 'wx', function (error, fileDescriptor) {
  if (!error && fileDescriptor) {
    var stringData = JSON.stringify(data);
    fs.writeFile(fileDescriptor, stringData, function (error) {
      if (!error) {
        fs.close(fileDescriptor, function (error) {
          if (!error) {
          } else {
            callback('Error in close file');
      } else {
        callback('Error in writing file.');

Can't install any packages in Node.js using "npm install"

This error might also occur due to proxy settings, once check that your proxy allow the access to npm commands.

It worked for me quite well.

How can I safely create a nested directory?

Check os.makedirs: (It makes sure the complete path exists.)
To handle the fact the directory might exist, catch OSError. (If exist_ok is False (the default), an OSError is raised if the target directory already exists.)

import os
except OSError:

What is the difference between signed and unsigned variables?

unsigned is used when ur value must be positive, no negative value here, if signed for int range -32768 to +32767 if unsigned for int range 0 to 65535

Flutter - Wrap text on overflow, like insert ellipsis or fade

Wrapping whose child elements are in a row or column, please wrap your column or row is new Flexible();

Android Studio Gradle Configuration with name 'default' not found

I recently encountered this error when I refereneced a project that was initiliazed via a git submodule.

I ended up finding out that the root build.gradle file of the submodule (a java project) did not have the java plugin applied at the root level.

It only had

apply plugin: 'idea'

I added the java plugin:

apply plugin: 'idea'
apply plugin: 'java'

Once I applied the java plugin the 'default not found' message disappeared and the build succeeded.

What is the difference between 'git pull' and 'git fetch'?

You can fetch from a remote repository, see the differences and then pull or merge.

This is an example for a remote repository called origin and a branch called master tracking the remote branch origin/master:

git checkout master                                                  
git fetch                                        
git diff origin/master
git rebase origin master

How to open .SQLite files

I would suggest using R and the package RSQLite

#install.packages("RSQLite") #perhaps needed

# connect to the sqlite file
sqlite    <- dbDriver("SQLite")
exampledb <- dbConnect(sqlite,"database.sqlite")


How to fix "Referenced assembly does not have a strong name" error?

Expand the project file that is using the project that does not "have a strong name key" and look for the .snk file (.StrongNameKey).

Browse through to this file in Windows Explorer (just so that you know where it is).

Back in Visual Studio in the project that does not "have a strong name key", do

  • Right click on the project file
  • Select Properties
  • Select "Signing tab" (on the left)
  • Click the check box "Sign the assembly"
  • Then <Browse> to the .snk file you found earlier

That should do the trick. This solved a problem for me for one project using a form inside another project in the same solution.

I hope it helps.

From io.Reader to string in Go

var b bytes.Buffer

// b.String()

How do you test a public/private DSA keypair?

I always compare an MD5 hash of the modulus using these commands:

Certificate: openssl x509 -noout -modulus -in server.crt | openssl md5
Private Key: openssl rsa -noout -modulus -in server.key | openssl md5
CSR: openssl req -noout -modulus -in server.csr | openssl md5

If the hashes match, then those two files go together.

How do you specify a different port number in SQL Management Studio?

On Windows plattform with server execute command:

netstat -a -b

look for sql server processes and find port f.e 49198

Or easier. Connect with dbvisualizer, run netstat -a -b find dbvis.exe process and get port.

Creating folders inside a GitHub repository without using Git

Another thing you can do is just drag a folder from your computer into the GitHub repository page. This folder does have to have at least 1 item in it, though.

How to Call a Function inside a Render in React/Jsx

class App extends React.Component {_x000D_
    console.log("came here")_x000D_
  subComponent() {_x000D_
    return (<div>Hello World</div>);_x000D_
  render() {_x000D_
    return ( _x000D_
      <div className="patient-container">_x000D_
          <button onClick={this.buttonClick.bind(this)}>Click me</button>_x000D_
ReactDOM.render(<App/>, document.getElementById('app'));
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<div id="app"></div>

it depends on your need, u can use either this.renderIcon() or bind this.renderIcon.bind(this)


This is how you call a method outside the render.

    console.log("came here")

render() {
   return (
       <div className="patient-container">
          <button onClick={this.buttonClick.bind(this)}>Click me</button>

The recommended way is to write a separate component and import it.

How to debug a bash script?

set +x = @ECHO OFF, set -x = @ECHO ON.

You can add -xv option to the standard Shebang as follows:

#!/bin/bash -xv  

-x : Display commands and their arguments as they are executed.
-v : Display shell input lines as they are read.

ltrace is another Linux Utility similar to strace. However, ltrace lists all the library calls being called in an executable or a running process. Its name itself comes from library-call tracing. For example:

ltrace ./executable <parameters>  
ltrace -p <PID>  


Tried to Load Angular More Than Once

For anyone that has this issue in the future, for me it was caused by an arrow function instead of a function literal in a run block:

// bad
module('a').run(() => ...)

// good
module('a').run(function() {...})

Spark - SELECT WHERE or filtering?

According to spark documentation "where() is an alias for filter()"

filter(condition) Filters rows using the given condition. where() is an alias for filter().

Parameters: condition – a Column of types.BooleanType or a string of SQL expression.

>>> df.filter(df.age > 3).collect()
[Row(age=5, name=u'Bob')]
>>> df.where(df.age == 2).collect()
[Row(age=2, name=u'Alice')]

>>> df.filter("age > 3").collect()
[Row(age=5, name=u'Bob')]
>>> df.where("age = 2").collect()
[Row(age=2, name=u'Alice')]

What do &lt; and &gt; stand for?

They're used to explicitly define less than and greater than symbols. If one wanted to type out <html> and not have it be a tag in the HTML, one would use them. An alternate way is to wrap the <code> element around code to not run into that.

They can also be used to present mathematical operators.

<!ENTITY lt      CDATA "&#60;"   -- less-than sign, U+003C ISOnum -->
<!ENTITY gt      CDATA "&#62;"   -- greater-than sign, U+003E ISOnum -->

MySQL: How to add one day to datetime field in query

You can use the DATE_ADD() function:


It can also be used in the SELECT statement:

SELECT DATE_ADD('2010-05-11', INTERVAL 1 DAY) AS Tomorrow;
| Tomorrow   |
| 2010-05-12 |
1 row in set (0.00 sec)

Difference between attr_accessor and attr_accessible

attr_accessor is ruby code and is used when you do not have a column in your database, but still want to show a field in your forms. The only way to allow this is to attr_accessor :fieldname and you can use this field in your View, or model, if you wanted, but mostly in your View.

Let's consider the following example

class Address
    attr_reader :street
    attr_writer :street  
    def initialize
        @street = ""

Here we have used attr_reader (readable attribute) and attr_writer (writable attribute) for accessing purpose. But we can achieve the same functionality using attr_accessor. In short, attr_accessor provides access to both getter and setter methods.

So modified code is as below

class Address
    attr_accessor :street  
    def initialize
        @street = ""

attr_accessible allows you to list all the columns you want to allow Mass Assignment. The opposite of this is attr_protected which means this field I do NOT want anyone to be allowed to Mass Assign to. More than likely it is going to be a field in your database that you don't want anyone monkeying around with. Like a status field, or the like.

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

Microsoft has their own Command Line Standard specification:

This document is focused at developers of command line utilities. Collectively, our goal is to present a consistent, composable command line user experience. Achieving that allows a user to learn a core set of concepts (syntax, naming, behaviors, etc) and then be able to translate that knowledge into working with a large set of commands. Those commands should be able to output standardized streams of data in a standardized format to allow easy composition without the burden of parsing streams of output text. This document is written to be independent of any specific implementation of a shell, set of utilities or command creation technologies; however, Appendix J - Using Windows Powershell to implement the Microsoft Command Line Standard shows how using Windows PowerShell will provide implementation of many of these guidelines for free.

How to apply shell command to each line of a command output?

for s in `cmd`; do echo $s; done

If cmd has a large output:

cmd | xargs -L1 echo

Setting the height of a DIV dynamically

inspired by @jason-bunting, same thing for either height or width:

function resizeElementDimension(element, doHeight) {
  dim = (doHeight ? 'Height' : 'Width')
  ref = (doHeight ? 'Top' : 'Left')

  var x = 0;
  var body = window.document.body;
  if(window['inner' + dim])
    x = window['inner' + dim]
  else if (body.parentElement['client' + dim])
    x = body.parentElement['client' + dim]
  else if (body && body['client' + dim])
    x = body['client' + dim][dim.toLowerCase()] = ((x - element['offset' + ref]) + "px");

Finding version of Microsoft C++ compiler from command-line (for makefiles)

Create a .c file containing just the line:




then pre-process with

cl /nologo /EP <filename>.c

It is easy to parse the output.

Remove a HTML tag but keep the innerHtml

// For MSIE:

// Old js, w/o loops, using DocumentFragment:
function replaceWithContents (el) {
  if (el.parentElement) {
    if (el.childNodes.length) {
      var range = document.createRange();
      el.parentNode.replaceChild(range.extractContents(), el);
    } else {

// Modern es:
const replaceWithContents = (el) => {

// or just:

// Today (2018) destructuring assignment works a little slower
// Modern es, using DocumentFragment.
// It may be faster than using
const replaceWithContents = (el) => {
  if (el.parentElement) {
    if (el.childNodes.length) {
      const range = document.createRange();
    } else {

XPath OR operator for different nodes

If you want to select only one of two nodes with union operator, you can use this solution: (//bookstore/book/title | //bookstore/city/zipcode/title)[1]

Python 2.7.10 error "from urllib.request import urlopen" no module named request

You are right the urllib and urllib2 packages have been split into urllib.request , urllib.parse and urllib.error packages in Python 3.x. The latter packages do not exist in Python 2.x

From documentation -

The urllib module has been split into parts and renamed in Python 3 to urllib.request, urllib.parse, and urllib.error.

From urllib2 documentation -

The urllib2 module has been split across several modules in Python 3 named urllib.request and urllib.error.

So I am pretty sure the code you downloaded has been written for Python 3.x , since they are using a library that is only present in Python 3.x .

There is a urllib package in python, but it does not have the request subpackage. Also, lets assume you do lots of work and somehow make request subpackage available in Python 2.x .

There is a very very high probability that you will run into more issues, there is lots of incompatibility between Python 2.x and Python 3.x , in the end you would most probably end up rewriting atleast half the code from github (and most probably reading and understanding the complete code from there).

Even then there may be other bugs arising from the fact that some of the implementation details changed between Python 2.x to Python 3.x (As an example - list comprehension got its own namespace in Python 3.x)

You are better off trying to download and use Python 3 , than trying to make code written for Python 3.x compatible with Python 2.x

Clearing content of text file using C#

Another short version:

System.IO.File.WriteAllBytes(path, new byte[0]);

How to change an Eclipse default project into a Java project

Using project Project facets we can configure characteristics and requirements for projects.

To find Project facets on eclipse:

  • Step 1: Right click on the project and choose properties from the menu.
  • Step 2:Select project facets option. Click on Convert to faceted form... enter image description here

  • Step 3: We can find all available facets you can select and change their settings. enter image description here

How to get the current time in milliseconds from C in Linux?

Use gettimeofday() to get the time in seconds and microseconds. Combining and rounding to milliseconds is left as an exercise.

What is difference between functional and imperative programming languages?

Functional programming is "programming with functions," where a function has some expected mathematical properties, including referential transparency. From these properties, further properties flow, in particular familiar reasoning steps enabled by substitutability that lead to mathematical proofs (i.e. justifying confidence in a result).

It follows that a functional program is merely an expression.

You can easily see the contrast between the two styles by noting the places in an imperative program where an expression is no longer referentially transparent (and therefore is not built with functions and values, and cannot itself be part of a function). The two most obvious places are: mutation (e.g. variables) other side-effects non-local control flow (e.g. exceptions)

On this framework of programs-as-expressions which are composed of functions and values, is built an entire practical paradigm of languages, concepts, "functional patterns", combinators, and various type systems and evaluation algorithms.

By the most extreme definition, almost any language—even C or Java—can be called functional, but usually people reserve the term for languages with specifically relevant abstractions (such as closures, immutable values, and syntactic aids like pattern matching). As far as use of functional programming is concerned it involves use of functins and builds code without any side effects . used to write proofs

Javascript require() function giving ReferenceError: require is not defined

Yes, require is a Node.JS function and doesn't work in client side scripting without certain requirements. If you're getting this error while writing electronJS code, try the following:

In your BrowserWindow declaration, add the following webPreferences field: i.e, instead of plain mainWindow = new BrowserWindow(), write

mainWindow = new BrowserWindow({
        webPreferences: {
            nodeIntegration: true

Read file line by line in PowerShell

I was able to read a 4GB log file in about 50 seconds with the following. You may be able to make it faster by loading it as a C# assembly dynamically using PowerShell.

[System.IO.StreamReader]$sr = [System.IO.File]::Open($file, [System.IO.FileMode]::Open)
while (-not $sr.EndOfStream){
    $line = $sr.ReadLine()

Iterating over ResultSet and adding its value in an ArrayList

Just for the fun, I'm offering an alternative solution using jOOQ and Java 8. Instead of using jOOQ, you could be using any other API that maps JDBC ResultSet to List, such as Spring JDBC or Apache DbUtils, or write your own ResultSetIterator:

jOOQ 3.8 or less

List<Object> list =
   .fetch("SELECT col1, col2, col3, ...")
   .flatMap(r ->

jOOQ 3.9

List<Object> list =
   .fetch("SELECT col1, col2, col3, ...")

(Disclaimer, I work for the company behind jOOQ)

How to include a font .ttf using CSS?

You can use font face like this:

@font-face {
  src: url("yourfont.ttf") format("truetype");

How to convert seconds to time format?

Sorry this is too late but maybe useful

function mediaTimeDeFormater($seconds)
    if (!is_numeric($seconds))
        throw new Exception("Invalid Parameter Type!");

    $ret = "";

    $hours = (string )floor($seconds / 3600);
    $secs = (string )$seconds % 60;
    $mins = (string )floor(($seconds - ($hours * 3600)) / 60);

    if (strlen($hours) == 1)
        $hours = "0" . $hours;
    if (strlen($secs) == 1)
        $secs = "0" . $secs;
    if (strlen($mins) == 1)
        $mins = "0" . $mins;

    if ($hours == 0)
        $ret = "$mins:$secs";
        $ret = "$hours:$mins:$secs";

    return $ret;

echo mediaTimeDeFormater(216.064000);//3:36

How to get current time with jQuery

I use moment for all my time manipulation/display needs (both client side, and node.js if you use it), if you just need a simple format the answers above will do, if you are looking for something a bit more complex, moment is the way to go IMO.

Write Array to Excel Range

Thanks for the pointers guys - the Value vs Value2 argument got me a different set of search results which helped me realise what the answer is. Incidentally, the Value property is a parametrized property, which must be accessed through an accessor in C#. These are called get_Value and set_Value, and take an optional enum value. If anyone's interested, this explains it nicely.

It's possible to make the assignment via the Value2 property however, which is preferable as the interop documentation recommends against the use use of the get_Value and set_Value methods, for reasons beyond my understanding.

The key seems to be the dimension of the array of objects. For the call to work the array must be declared as two-dimensional, even if you're only assigning one-dimensional data.

I declared my data array as an object[NumberofRows,1] and the assignment call worked.

How do I get SUM function in MySQL to return '0' if no values are found?

Can't get exactly what you are asking but if you are using an aggregate SUM function which implies that you are grouping the table.

The query goes for MYSQL like this

Select IFNULL(SUM(COLUMN1),0) as total from mytable group by condition

variable is not declared it may be inaccessible due to its protection level

If I remember correctly, this is the default property for controls.

Can you try by going into Design-View for the admin_reasons that contains the specified Control, then changing the control's Modifiers property to Public or Internal.

What is the difference between . (dot) and $ (dollar sign)?

The $ operator is for avoiding parentheses. Anything appearing after it will take precedence over anything that comes before.

For example, let's say you've got a line that reads:

putStrLn (show (1 + 1))

If you want to get rid of those parentheses, any of the following lines would also do the same thing:

putStrLn (show $ 1 + 1)
putStrLn $ show (1 + 1)
putStrLn $ show $ 1 + 1

The primary purpose of the . operator is not to avoid parentheses, but to chain functions. It lets you tie the output of whatever appears on the right to the input of whatever appears on the left. This usually also results in fewer parentheses, but works differently.

Going back to the same example:

putStrLn (show (1 + 1))
  1. (1 + 1) doesn't have an input, and therefore cannot be used with the . operator.
  2. show can take an Int and return a String.
  3. putStrLn can take a String and return an IO ().

You can chain show to putStrLn like this:

(putStrLn . show) (1 + 1)

If that's too many parentheses for your liking, get rid of them with the $ operator:

putStrLn . show $ 1 + 1

Tablix: Repeat header rows on each page not working - Report Builder 3.0

It depends on the tablix structure you are using. In a table, for example, you do not have column groups, so Reporting Services does not recognize which textboxes are the column headers and setting RepeatColumnHeaders property to True doesn't work.

Instead, you need to:

  1. Open Advanced Mode in the Groupings pane. (Click the arrow to the right of the Column Groups and select Advanced Mode.)
    • Screenshot
  2. In the Row Groups area (not Column Groups), click on a Static group, which highlights the corresponding textbox in the tablix. Click through each Static group until it highlights the leftmost column header. This is generally the first Static group listed.
  3. In the Properties window, set the RepeatOnNewPage property to True.
    • Screenshot
  4. Make sure that the KeepWithGroup property is set to After.

The KeepWithGroup property specifies which group to which the static member needs to stick. If set to After then the static member sticks with the group after it, or below it, acting as a group header. If set to Before, then the static member sticks with the group before, or above it, acting as a group footer. If set to None, Reporting Services decides where to put the static member.

Now when you view the report, the column headers repeat on each page of the tablix.

This video shows how to set it exactly as the answer described.

Code signing is required for product type Unit Test Bundle in SDK iOS 8.0

Hi I face the same problem today. After reading "Spentak"'s answer i tried to make code signing of my target to set to iOSDeveloper, and still did not work. But after i changing "Provisioning Profile" to "Automatic", the project got built and ran without any code signing errors.

python xlrd unsupported format, or corrupt file.

Open in google sheets and then download from sheets as CSV and then reupload to drive. Then you can Open CSV file from python.

How to make an executable JAR file?

If you use maven, add the following to your pom.xml file:

    <!-- Build an executable JAR -->

Then you can run mvn package. The jar file will be located under in the target directory.

The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>)

Check out the solutions at "The Controls collection cannot be modified because the control contains code blocks"

The accepted solution on the other question worked for me -- change instances of <%= to <%#, which converts the code block from Response.Write to an evaluation block, which isn't restricted by the same limitations.

In this case though, like the accepted solution here suggests, you should add the controls to something other than a masterpage ContentPlaceHolder element, namely the asp:Placeholder control suggested.

How to update data in one table from corresponding data in another table in SQL Server 2005

update t2
set t2.deptid = t1.deptid
from test1 t1, test2 t2
where t2.employeeid = t1.employeeid

How to check if a double is null?

I believe Double.NaN might be able to cover this. That is the only 'null' value double contains.

Fast and Lean PDF Viewer for iPhone / iPad / iOS - tips and hints?

I have build such kind of application using approximatively the same approach except :

  • I cache the generated image on the disk and always generate two to three images in advance in a separate thread.
  • I don't overlay with a UIImage but instead draw the image in the layer when zooming is 1. Those tiles will be released automatically when memory warnings are issued.

Whenever the user start zooming, I acquire the CGPDFPage and render it using the appropriate CTM. The code in - (void)drawLayer: (CALayer*)layer inContext: (CGContextRef) context is like :

CGAffineTransform currentCTM = CGContextGetCTM(context);    
if (currentCTM.a == 1.0 && baseImage) {
    //Calculate ideal scale
    CGFloat scaleForWidth = baseImage.size.width/self.bounds.size.width;
    CGFloat scaleForHeight = baseImage.size.height/self.bounds.size.height; 
    CGFloat imageScaleFactor = MAX(scaleForWidth, scaleForHeight);

    CGSize imageSize = CGSizeMake(baseImage.size.width/imageScaleFactor, baseImage.size.height/imageScaleFactor);
    CGRect imageRect = CGRectMake((self.bounds.size.width-imageSize.width)/2, (self.bounds.size.height-imageSize.height)/2, imageSize.width, imageSize.height);
    CGContextDrawImage(context, imageRect, [baseImage CGImage]);
} else {
    @synchronized(issue) { 
        CGPDFPageRef pdfPage = CGPDFDocumentGetPage(issue.pdfDoc, pageIndex+1);
        pdfToPageTransform = CGPDFPageGetDrawingTransform(pdfPage, kCGPDFMediaBox, layer.bounds, 0, true);
        CGContextConcatCTM(context, pdfToPageTransform);    
        CGContextDrawPDFPage(context, pdfPage);

issue is the object containg the CGPDFDocumentRef. I synchronize the part where I access the pdfDoc property because I release it and recreate it when receiving memoryWarnings. It seems that the CGPDFDocumentRef object do some internal caching that I did not find how to get rid of.

Laravel update model with unique validation rule for attribute

I had the same problem. What I've done: add in my view hidden field with id of a model and in validator check the unique, only if I've get some id from view.

            'index'       => implode('|', ['required', $request->input('id') ? '' : 'unique:members']),
            'name'        => 'required',
            'surname'     => 'required',

What is a vertical tab?

A vertical tab was the opposite of a line feed i.e. it went upwards by one line. It had nothing to do with tab positions. If you want to prove this, try it on an RS232 terminal.

Returning JSON from a PHP Script

As said above:

header('Content-Type: application/json');

will make the job. but keep in mind that :

  • Ajax will have no problem to read json even if this header is not used, except if your json contains some HTML tags. In this case you need to set the header as application/json.

  • Make sure your file is not encoded in UTF8-BOM. This format add a character in the top of the file, so your header() call will fail.

HttpURLConnection timeout settings

If the HTTP Connection doesn't timeout, You can implement the timeout checker in the background thread itself (AsyncTask, Service, etc), the following class is an example for Customize AsyncTask which timeout after certain period

public abstract class AsyncTaskWithTimer<Params, Progress, Result> extends
    AsyncTask<Params, Progress, Result> {

private static final int HTTP_REQUEST_TIMEOUT = 30000;

protected Result doInBackground(Params... params) {
    return doInBackgroundImpl(params);

private void createTimeoutListener() {
    Thread timeout = new Thread() {
        public void run() {

            final Handler handler = new Handler();
            handler.postDelayed(new Runnable() {
                public void run() {

                    if (AsyncTaskWithTimer.this != null
                            && AsyncTaskWithTimer.this.getStatus() != Status.FINISHED)
            }, HTTP_REQUEST_TIMEOUT);


abstract protected Result doInBackgroundImpl(Params... params);

A Sample for this

public class AsyncTaskWithTimerSample extends AsyncTaskWithTimer<Void, Void, Void> {

    protected void onCancelled(Void void) {
        Log.d(TAG, "Async Task onCancelled With Result");

    protected void onCancelled() {
        Log.d(TAG, "Async Task onCancelled");

    protected Void doInBackgroundImpl(Void... params) {
        // Do background work
        return null;

Intercept a form submit in JavaScript and prevent normal submission

Another option to handle all requests I used in my practice for cases when onload can't help is to handle javascript submit, html submit, ajax requests. These code should be added in the top of body element to create listener before any form rendered and submitted.

In example I set hidden field to any form on page on its submission even if it happens before page load.

//Handles jquery, dojo, etc. ajax requests
(function (send) {
    var token = $("meta[name='_csrf']").attr("content");
    var header = $("meta[name='_csrf_header']").attr("content");
    XMLHttpRequest.prototype.send = function (data) {
        if (isNotEmptyString(token) && isNotEmptyString(header)) {
            this.setRequestHeader(header, token);
        }, data);

//Handles javascript submit
(function (submit) {
    HTMLFormElement.prototype.submit = function (data) {
        var token = $("meta[name='_csrf']").attr("content");
        var paramName = $("meta[name='_csrf_parameterName']").attr("content");
            type: 'hidden',
            name: paramName,
            value: token
        }).appendTo(this);, data);

//Handles html submit
document.body.addEventListener('submit', function (event) {
    var token = $("meta[name='_csrf']").attr("content");
    var paramName = $("meta[name='_csrf_parameterName']").attr("content");
        type: 'hidden',
        name: paramName,
        value: token
}, false);

How to do 3 table JOIN in UPDATE query?

An alternative General Plan, which I'm only adding as an independent Answer because the blasted "comment on an answer" won't take newlines without posting the entire edit, even though it isn't finished yet.

UPDATE table A
JOIN table B ON {join fields}
JOIN table C ON {join fields}
JOIN {as many tables as you need}
SET A.column = {expression}


UPDATE person P
JOIN address A ON P.home_address_id =
JOIN city C ON A.city_id =
SET P.home_zip = C.zipcode;

Oracle: SQL query that returns rows with only numeric values

You can use the REGEXP_LIKE function as:

FROM myTable 
WHERE REGEXP_LIKE(X, '^[[:digit:]]+$');

Sample run:






What does .class mean in Java?

Just to clarify, this '.class' method is not referring to the bytecode file you see after compiling java code nor a confusion between the concepts of Class vs. Object in OOP theory.

This '.class' method is used in Java for code Reflection. Generally you can gather meta data for your class such as the full qualified class name, list of constants, list of public fields, etc, etc.

Check these links (already mentioned above) to get all the details:

Normally you don't plan on using Reflection right away when you start building your project. It's something that you know you need after trying to manage already working code. Many times you need it to manage multiple instances of your program. Maybe you want to identify each particular 'clone' to determine if something is already defined, or count the number of functions, or just simply log the details of a particular instance of your class.

Java best way for string find and replace?

One possibility, reducing the longer form before expanding all:

string.replaceAll("Milan Vasic", "Milan").replaceAll("Milan", "Milan Vasic")

Another way, treating Vasic as optional:

string.replaceAll("Milan( Vasic)?", "Milan Vasic")

Others have described solutions based on lookahead or alternation.

beyond top level package error in relative import

In my humble opinion, I understand this question in this way:

[CASE 1] When you start an absolute-import like

python -m test_A.test


import test_A.test


from test_A import test

you're actually setting the import-anchor to be test_A, in other word, top-level package is test_A . So, when we have do from ..A import xxx, you are escaping from the anchor, and Python does not allow this.

[CASE 2] When you do

python -m package.test_A.test


from package.test_A import test

your anchor becomes package, so package/test_A/ doing from ..A import xxx does not escape the anchor(still inside package folder), and Python happily accepts this.

In short:

  • Absolute-import changes current anchor (=redefines what is the top-level package);
  • Relative-import does not change the anchor but confines to it.

Furthermore, we can use full-qualified module name(FQMN) to inspect this problem.

Check FQMN in each case:

  • [CASE2] test.__name__ = package.test_A.test
  • [CASE1] test.__name__ = test_A.test

So, for CASE2, an from .. import xxx will result in a new module with, which is acceptable.

While for CASE1, the .. from within from .. import xxx will jump out of the starting node(anchor) of test_A, and this is NOT allowed by Python.

Converting any object to a byte array in java

Use serialize and deserialize methods in SerializationUtils from commons-lang.

How to pip install a package with min and max version range?

You can do:

$ pip install "package>=0.2,<0.3"

And pip will look for the best match, assuming the version is at least 0.2, and less than 0.3.

This also applies to pip requirements files. See the full details on version specifiers in PEP 440.

java.text.ParseException: Unparseable date

I found simple solution to get current date without any parsing error.

Calendar calendar;
calendar = Calendar.getInstance();
String customDate = "" + calendar.get(Calendar.YEAR) + "-" + (calendar.get(Calendar.MONTH) + 1) + "-" + calendar.get(Calendar.DAY_OF_MONTH);

How to write a Python module/package?

Make a file named ""

If you are using Python 2.x

def func():
    print "Hello"

If you are using Python 3.x

def func():

Run the file. Then, you can try the following:

>>> import hello
>>> hello.func()

If you want a little bit hard, you can use the following:

If you are using Python 2.x

def say(text):
    print text

If you are using Python 3.x

def say(text):

See the one on the parenthesis beside the define? That is important. It is the one that you can use within the define.

Text - You can use it when you want the program to say what you want. According to its name, it is text. I hope you know what text means. It means "words" or "sentences".

Run the file. Then, you can try the following if you are using Python 3.x:

>>> import hello
>>> hello.say("hi")
>>> from hello import say
>>> say("test")

For Python 2.x - I guess same thing with Python 3? No idea. Correct me if I made a mistake on Python 2.x (I know Python 2 but I am used with Python 3)

Looking to understand the iOS UIViewController lifecycle

There's a lot of outdated and incomplete information here. For iOS 6 and newer only:

  1. loadView[a]
  2. viewDidLoad[a]
  3. viewWillAppear
  4. viewWillLayoutSubviews is the first time bounds are finalized
  5. viewDidLayoutSubviews
  6. viewDidAppear
  7. * viewWillLayoutSubviews[b]
  8. * viewDidLayoutSubviews[b]


(a) - If you manually nil out your view during didReceiveMemoryWarning, loadView and viewDidLoad will be called again. That is, by default loadView and viewDidLoad only gets called once per view controller instance.

(b) May be called an additional 0 or more times.

java.math.BigInteger cannot be cast to java.lang.Integer

You can try this:

((BigDecimal) volume).intValue();

I use java.math.BigDecimal convert to int (primitive type).

It is worked for me.

How to change dot size in gnuplot

Use the pointtype and pointsize options, e.g.

plot "./points.dat" using 1:2 pt 7 ps 10  

where pt 7 gives you a filled circle and ps 10 is the size.

See: Plotting data.

How to run Unix shell script from Java code?

It is possible, just exec it as any other program. Just make sure your script has the proper #! (she-bang) line as the first line of the script, and make sure there are execute permissions on the file.

For example, if it is a bash script put #!/bin/bash at the top of the script, also chmod +x .

Also as for if it's good practice, no it's not, especially for Java, but if it saves you a lot of time porting a large script over, and you're not getting paid extra to do it ;) save your time, exec the script, and put the porting to Java on your long-term todo list.

cd into directory without having permission

chmod +x openfire worked for me. It adds execution permission to the openfire folder.

Sort & uniq in Linux shell

Beware! While it's true that "sort -u" and "sort|uniq" are equivalent, any additional options to sort can break the equivalence. Here's an example from the coreutils manual:

For example, 'sort -n -u' inspects only the value of the initial numeric string when checking for uniqueness, whereas 'sort -n | uniq' inspects the entire line.

Similarly, if you sort on key fields, the uniqueness test used by sort won't necessarily look at the entire line anymore. After being bitten by that bug in the past, these days I tend to use "sort|uniq" when writing Bash scripts. I'd rather have higher I/O overhead than run the risk that someone else in the shop won't know about that particular pitfall when they modify my code to add additional sort parameters.

How to find out which JavaScript events fired?

Looks like Firebug (Firefox add-on) has the answer:

  • open Firebug
  • right click the element in HTML tab
  • click Log Events
  • enable Console tab
  • click Persist in Console tab (otherwise Console tab will clear after the page is reloaded)
  • select Closed (manually)
  • there will be something like this in Console tab:

    mousemove clientX=1097, clientY=292
    mousedown clientX=1097, clientY=292
    mouseup clientX=1097, clientY=292
    click clientX=1097, clientY=292
    mousemove clientX=1096, clientY=293

Source: Firebug Tip: Log Events

Display an image with Python

Solution for Jupyter notebook PIL image visualization with arbitrary number of images:

def show(*imgs, **kwargs):
    '''Show in Jupyter notebook one or sequence of PIL images in a row. figsize - optional parameter, controlling size of the image.
    if 'figsize' not in kwargs:
        figsize = [9,9]
        figsize = kwargs['figsize']
    fig, ax = plt.subplots(1,len(imgs),figsize=figsize)
    if len(imgs)==1:
    for num,img in enumerate(imgs):

How to print the array?

If you want to print the array like you print a 2D list in Python:

#include <stdio.h>

int main()
  int i, j;
  int my_array[3][3] = {{10, 23, 42}, {1, 654, 0}, {40652, 22, 0}};
  for(i = 0; i < 3; i++)
      if (i == 0) {
      for(j = 0; j < 3; j++)
         printf("%d", my_array[i][j]);
         if (j < 2) {
             printf(", ");
    if (i == 2) {

    if (i < 2) {
        printf(", ");
  return 0;

Output will be:

[[10, 23, 42], [1, 654, 0], [40652, 22, 0]]

De-obfuscate Javascript code to make it readable again

From the first link on google;

function call_func(_0x41dcx2) {
 var _0x41dcx3 = eval('(' + _0x41dcx2 + ')');
 var _0x41dcx4 = document['createElement']('div');
 var _0x41dcx5 = _0x41dcx3['id'];
 var _0x41dcx6 = _0x41dcx3['Student_name'];
 var _0x41dcx7 = _0x41dcx3['student_dob'];
 var _0x41dcx8 = '<b>ID:</b>';
 _0x41dcx8 += '<a href="/learningyii/index.php?r=student/view&amp; id=' + _0x41dcx5 + '">' + _0x41dcx5 + '</a>';
 _0x41dcx8 += '<br/>';
 _0x41dcx8 += '<b>Student Name:</b>';
 _0x41dcx8 += _0x41dcx6;
 _0x41dcx8 += '<br/>';
 _0x41dcx8 += '<b>Student DOB:</b>';
 _0x41dcx8 += _0x41dcx7;
 _0x41dcx8 += '<br/>';
 _0x41dcx4['innerHTML'] = _0x41dcx8;
 _0x41dcx4['setAttribute']('class', 'view');

It won't get you all the way back to source, and that's not really possible, but it'll get you out of a hole.

How do I create an .exe for a Java program?

If you really want an exe Excelsior JET is a professional level product that compiles to native code:

You can also look at JSMooth:

And if your application is compatible with its compatible with AWT/Apache classpath then GCJ compiles to native exe.

How do I translate an ISO 8601 datetime string into a Python datetime object?

Arrow looks promising for this:

>>> import arrow
>>> arrow.get('2014-11-13T14:53:18.694072+00:00').datetime
datetime.datetime(2014, 11, 13, 14, 53, 18, 694072, tzinfo=tzoffset(None, 0))

Arrow is a Python library that provides a sensible, intelligent way of creating, manipulating, formatting and converting dates and times. Arrow is simple, lightweight and heavily inspired by moment.js and requests.

forEach() in React JSX does not output any HTML

You need to pass an array of element to jsx. The problem is that forEach does not return anything (i.e it returns undefined). So it's better to use map because map returns an array:

class QuestionSet extends Component {
    <div className="container">
       {, i) => {     
           // Return the element. Also pass key     
           return (<Answer key={answer} answer={answer} />) 

export default QuestionSet;

CSS text-decoration underline color

You can't change the color of the line (you can't specify different foreground colors for the same element, and the text and its decoration form a single element). However there are some tricks:

a:link, a:visited {text-decoration: none; color: red; border-bottom: 1px solid #006699; }
a:hover, a:active {text-decoration: none; color: red; border-bottom: 1px solid #1177FF; }

Also you can make some cool effects this way:

a:link {text-decoration: none; color: red; border-bottom: 1px dashed #006699; }

Hope it helps.

Swift apply .uppercaseString to only the first letter of a string

From Swift 3 you can easily use textField.autocapitalizationType = UITextAutocapitalizationType.sentences

SQL JOIN vs IN performance?

Funny you mention that, I did a blog post on this very subject.

See Oracle vs MySQL vs SQL Server: Aggregation vs Joins

Short answer: you have to test it and individual databases vary a lot.

image.onload event and browser cache

If the src is already set then the event is firing in the cached case before you even get the event handler bound. So, you should trigger the event based off .complete also.

code sample:

$("img").one("load", function() {
   //do stuff
}).each(function() {
   if(this.complete || /*for IE 10-*/ $(this).height() > 0)

Assert equals between 2 Lists in Junit

I know there are already many options to solve this issue, but I would rather do the following to assert two lists in any oder:

assertTrue(result.containsAll(expected) && expected.containsAll(result))

How to get the caret column (not pixels) position in a textarea, in characters, from the start?

With Firefox, Safari (and other Gecko based browsers) you can easily use textarea.selectionStart, but for IE that doesn't work, so you will have to do something like this:

function getCaret(node) {
  if (node.selectionStart) {
    return node.selectionStart;
  } else if (!document.selection) {
    return 0;

  var c = "\001",
      sel = document.selection.createRange(),
      dul = sel.duplicate(),
      len = 0;

  sel.text = c;
  len = dul.text.indexOf(c);
  sel.text = "";
  return len;

(complete code here)

I also recommend you to check the jQuery FieldSelection Plugin, it allows you to do that and much more...

Edit: I actually re-implemented the above code:

function getCaret(el) { 
  if (el.selectionStart) { 
    return el.selectionStart; 
  } else if (document.selection) { 

    var r = document.selection.createRange(); 
    if (r == null) { 
      return 0; 

    var re = el.createTextRange(), 
        rc = re.duplicate(); 
    rc.setEndPoint('EndToStart', re); 

    return rc.text.length; 
  return 0; 

Check an example here.

Git - Ignore node_modules folder everywhere

just add different .gitignore files to mini project 1 and mini project 2. Each of the .gitignore files should /node_modules and you're good to go.

gradlew: Permission Denied

With this step set permission to gradlew

steps {
    echo 'Compile project'
    sh "chmod +x gradlew"
    sh "./gradlew clean build --no-daemon"

How do I set specific environment variables when debugging in Visual Studio?

You can set it at Property > Configuration Properties > Debugging > Environment enter image description here

OAuth: how to test with local URLs?

I found which automatically converts a fixed url to a embedded localhost domain.

For example lets say your localhost server is running on You can go to to access this server. You can then add this address to Oauth configuration for Facebook or Google.

Spring Boot without the web server

Similar to @nayun oh answer above, but for older versions of Spring, use this code:

SpringApplication application = new SpringApplication(DemoApplication.class);

Google Drive as FTP Server

What about running the google-drive-ftp-adapter application in your local pc and then connect your filezilla client to that application? The google-drive-ftp-adapter application is not an online service, but its an alternative solution to connect to google drive through ftp.

The google-drive-ftp-adapter is an open source application hosted in github and it is a kind of standalone ftp-server java application that connects to your google drive in behalf of you, acting as a bridge (or adapter) between your ftp client and the google drive service. Once you have running the google-drive-ftp adapter, you can connect your preferred FTP client to the google-drive-ftp-adapter ftp server in your localhost (or wherever the app is running, like in a remote machine) to manage your files.

I use it in conjunction with beyond compare to synchronize my local files against the ones I have in the google drive and it serves well for the purpose.

This is the current github link hosting the google-drive-ftp-adapter repository:

Checking from shell script if a directory contains files

Could you compare the output of this?

 ls -A /some/dir | wc -l

jquery how to empty input field

Since you are using jQuery, how about using a trigger-reset:


How do you properly determine the current script directory?

In Python 3.4+ you can use the simpler pathlib module:

from inspect import currentframe, getframeinfo
from pathlib import Path

filename = getframeinfo(currentframe()).filename
parent = Path(filename).resolve().parent

You can also use __file__ to avoid the inspect module altogether:

from pathlib import Path
parent = Path(__file__).resolve().parent

How to get week numbers from dates?

If you want to get the week number with the year, Grant Shannon's solution using strftime works, but you need to make some corrections for the dates around january 1st. For instance, 2016-01-03 (yyyy-mm-dd) is week 53 of year 2015, not 2016. And 2018-12-31 is week 1 of 2019, not of 2018. This codes provides some examples and a solution. In column "yearweek" the years are sometimes wrong, in "yearweek2" they are corrected (rows 2 and 5).


# create a testset
test <- data.frame(matrix(data = c("2015-12-31",
                                   "2019-01-01") , ncol=1, nrow = 6 ))
# add a colname
colnames(test) <- "date_txt"

# this codes provides correct year-week numbers
test <- test %>%
        mutate(date = as.Date(date_txt, format = "%Y-%m-%d")) %>%
        mutate(yearweek = as.integer(strftime(date, format = "%Y%V"))) %>%
        mutate(yearweek2 = ifelse(test = day(date) > 7 & substr(yearweek, 5, 6) == '01',
                                 yes  = yearweek + 100,
                                 no   = ifelse(test = month(date) == 1 & as.integer(substr(yearweek, 5, 6)) > 51,
                                               yes  = yearweek - 100,
                                               no   = yearweek)))
# print the result

    date_txt       date yearweek yearweek2
1 2015-12-31 2015-12-31   201553    201553
2 2016-01-03 2016-01-03   201653    201553
3 2016-01-04 2016-01-04   201601    201601
4 2018-12-30 2018-12-30   201852    201852
5 2018-12-31 2018-12-31   201801    201901
6 2019-01-01 2019-01-01   201901    201901

How to create a blank/empty column with SELECT query in oracle?

I think you should use null

SELECT CustomerName AS Customer, null AS Contact 
FROM Customers;

And Remember that Oracle

treats a character value with a length of zero as null.

What's the difference between TRUNCATE and DELETE in SQL

In short, truncate doesn't log anything (so is much faster but can't be undone) whereas delete is logged (and can be part of a larger transaction, will rollback etc). If you have data that you don't want in a table in dev it is normally better to truncate as you don't run the risk of filling up the transaction log

Getting a count of objects in a queryset in django

To get the number of votes for a specific item, you would use:

vote_count = Item.objects.filter(votes__contest=contestA).count()

If you wanted a break down of the distribution of votes in a particular contest, I would do something like the following:

contest = Contest.objects.get(pk=contest_id)
votes   = contest.votes_set.select_related()

vote_counts = {}

for vote in votes:
  if not vote_counts.has_key(
    vote_counts[] = {
      'item': vote.item,
      'count': 0

  vote_counts[]['count'] += 1

This will create dictionary that maps items to number of votes. Not the only way to do this, but it's pretty light on database hits, so will run pretty quickly.

How can I check if the array of objects have duplicate property values?

//checking duplicate elements in an array
var arr=[1,3,4,6,8,9,1,3,4,7];
var hp=new Map();
var freq=0;
for(var i=1;i<arr.length;i++){
// console.log(arr[i-1]+" "+arr[i]);


Capturing count from an SQL query

int count = 0;    
using (new SqlConnection connection = new SqlConnection("connectionString"))
    sqlCommand cmd = new SqlCommand("SELECT COUNT(*) FROM table_name", connection);
    count = (int32)cmd.ExecuteScalar();

Java 11 package javax.xml.bind does not exist

According to the release-notes, Java 11 removed the Java EE modules:

java.xml.bind (JAXB) - REMOVED
  • Java 8 - OK
  • Java 9 - DEPRECATED
  • Java 10 - DEPRECATED
  • Java 11 - REMOVED

See JEP 320 for more info.

You can fix the issue by using alternate versions of the Java EE technologies. Simply add Maven dependencies that contain the classes you need:


Jakarta EE 8 update (Mar 2020)

Instead of using old JAXB modules you can fix the issue by using Jakarta XML Binding from Jakarta EE 8:


Jakarta EE 9 update (Nov 2020)

Use latest release of Eclipse Implementation of JAXB 3.0.0:


Note: Jakarta EE 9 adopts new API package namespace jakarta.xml.bind.*, so update import statements:

javax.xml.bind -> jakarta.xml.bind

Printing with "\t" (tabs) does not result in aligned columns

The "problem" with the tabs is that they indent the text to fixed tab positions, typically multiples of 4 or 8 characters (depending on the console or editor displaying them). Your first filename is 7 chars, so the next tab stop after its end is at position 8. Your subsequent filenames however are 8 chars long, so the next tab stop is at position 12.

If you want to ensure that columns get nicely indented at the same position, you need to take into account the actual length of previous columns, and either modify the number of following tabs, or pad with the required number of spaces instead. The latter can be achieved using e.g. System.out.printf with an appropriate format specification (e.g. "%1$13s" specifies a minimum width of 13 characters for displaying the first argument as a string).

Display all post meta keys and meta values of the same post ID in wordpress

To get all rows, don't specify the key. Try this:

$meta_values = get_post_meta( get_the_ID() );

var_dump( $meta_values );

Hope it helps!

Editing the git commit message in GitHub

You need to git push -f assuming that nobody has pulled the other commit before. Beware, you're changing history.

python mpl_toolkits installation issue

I can't comment due to the lack of reputation, but if you are on arch linux, you should be able to find the corresponding libraries on the arch repositories directly. For example for mpl_toolkits.basemap:

pacman -S python-basemap

How do you attach and detach from Docker's process?

For anyone who ran into the same problem I did (can't detach without killing the container, even when setting the detach key)......

When starting your containers with docker-compose up -d

instead of using docker attach {container name} to view the tailing log ....

try docker-compose logs -f {service name} ctrl-c kills the log tail without killing your container

{service name} being the service listed in side of your docker-compose.yml file.. (e.g. while container name=elk_logstash_1 -> service name=logstash


How do I create a new column from the output of pandas groupby().sum()?

You want to use transform this will return a Series with the index aligned to the df so you can then add it as a new column:

In [74]:

df = pd.DataFrame({'Date': ['2015-05-08', '2015-05-07', '2015-05-06', '2015-05-05', '2015-05-08', '2015-05-07', '2015-05-06', '2015-05-05'], 'Sym': ['aapl', 'aapl', 'aapl', 'aapl', 'aaww', 'aaww', 'aaww', 'aaww'], 'Data2': [11, 8, 10, 15, 110, 60, 100, 40],'Data3': [5, 8, 6, 1, 50, 100, 60, 120]})
df['Data4'] = df['Data3'].groupby(df['Date']).transform('sum')
   Data2  Data3        Date   Sym  Data4
0     11      5  2015-05-08  aapl     55
1      8      8  2015-05-07  aapl    108
2     10      6  2015-05-06  aapl     66
3     15      1  2015-05-05  aapl    121
4    110     50  2015-05-08  aaww     55
5     60    100  2015-05-07  aaww    108
6    100     60  2015-05-06  aaww     66
7     40    120  2015-05-05  aaww    121

Getting one value from a tuple


Single elements of a tuple a can be accessed -in an indexed array-like fashion-

via a[0], a[1], ... depending on the number of elements in the tuple.


If your tuple is a=(3,"a")

  • a[0] yields 3,
  • a[1] yields "a"

Concrete answer to question

def tup():
  return (3, "hello")

tup() returns a 2-tuple.

In order to "solve"

i = 5 + tup()  # I want to add just the three

you select the 3 by

tup()[0|    #first element

so in total

i = 5 + tup()[0]


Go with namedtuple that allows you to access tuple elements by name (and by index). Details at

>>> import collections
>>> MyTuple=collections.namedtuple("MyTuple", "mynumber, mystring")
>>> m = MyTuple(3, "hello")
>>> m[0]
>>> m.mynumber
>>> m[1]
>>> m.mystring

How to Find the Default Charset/Encoding in Java?

Is this a bug or feature?

Looks like undefined behaviour. I know that, in practice, you can change the default encoding using a command-line property, but I don't think what happens when you do this is defined.

Bug ID: 4153515 on problems setting this property:

This is not a bug. The "file.encoding" property is not required by the J2SE platform specification; it's an internal detail of Sun's implementations and should not be examined or modified by user code. It's also intended to be read-only; it's technically impossible to support the setting of this property to arbitrary values on the command line or at any other time during program execution.

The preferred way to change the default encoding used by the VM and the runtime system is to change the locale of the underlying platform before starting your Java program.

I cringe when I see people setting the encoding on the command line - you don't know what code that is going to affect.

If you do not want to use the default encoding, set the encoding you do want explicitly via the appropriate method/constructor.

How to sort List<Integer>?

You can use the utility method in Collections class public static <T extends Comparable<? super T>> void sort(List<T> list) or

public static <T> void sort(List<T> list,Comparator<? super T> c)

Refer to Comparable and Comparator interfaces for more flexibility on sorting the object.

Error: Specified cast is not valid. (SqlManagerUI)

This would also happen when you are trying to restore a newer version backup in a older SQL database. For example when you try to restore a DB backup that is created in 2012 with 110 compatibility and you are trying to restore it in 2008 R2.

LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression

Just save the string to a temp variable and then use that in your expression:

var strItem = item.Key.ToString();

IQueryable<entity> pages = from p in context.pages
                           where  p.Serial == strItem
                           select p;

The problem arises because ToString() isn't really executed, it is turned into a MethodGroup and then parsed and translated to SQL. Since there is no ToString() equivalent, the expression fails.


Make sure you also check out Alex's answer regarding the SqlFunctions helper class that was added later. In many cases it can eliminate the need for the temporary variable.

Append String in Swift

let firstname = "paresh"
let lastname = "hirpara"
let itsme = "\(firstname) \(lastname)"

Java - Create a new String instance with specified length and filled with specific character. Best solution?

No need to do the loop, and using just standard Java library classes:

protected String getStringWithLengthAndFilledWithCharacter(int length, char charToFill) {
  if (length > 0) {
    char[] array = new char[length];
    Arrays.fill(array, charToFill);
    return new String(array);
  return "";

As you can see, I also added suitable code for the length == 0 case.

return SQL table as JSON in python

Most simple way,

use json.dumps but if its datetime will require to parse datetime into json serializer.

here is mine,

import MySQLdb, re, json
from datetime import date, datetime

def json_serial(obj):
    """JSON serializer for objects not serializable by default json code"""

    if isinstance(obj, (datetime, date)):
        return obj.isoformat()
    raise TypeError ("Type %s not serializable" % type(obj))

conn = MySQLdb.connect(instance)
curr = conn.cursor()
curr.execute("SELECT * FROM `assets`")
data = curr.fetchall()
print json.dumps(data, default=json_serial)

it will return json dump

one more simple method without json dumps, here get header and use zip to map with each finally made it as json but this is not change datetime into json serializer...

data_json = []
header = [i[0] for i in curr.description]
data = curr.fetchall()
for i in data:
    data_json.append(dict(zip(header, i)))
print data_json

Adding a JAR to an Eclipse Java library

You might also consider using a build tool like Maven to manage your dependencies. It is very easy to setup and helps manage those dependencies automatically in eclipse. Definitely worth the effort if you have a large project with a lot of external dependencies.

Display the current time and date in an Android application

To get current Time/Date just use following code snippet:

To use Time:

SimpleDateFormat simpleDateFormatTime = new SimpleDateFormat("HH:mm", Locale.getDefault());
String strTime = simpleDateFormatTime.format(now.getTime());

To use Date:

SimpleDateFormat simpleDateFormatDate = new SimpleDateFormat("E, MMM dd, yyyy", Locale.getDefault());    
String strDate = simpleDateFormatDate.format(now.getTime());

and you are good to go.

Calculating how many days are between two dates in DB2?

I faced the same problem in Derby IBM DB2 embedded database in a java desktop application, and after a day of searching I finally found how it's done :

SELECT days (table1.datecolomn) - days (current date) FROM table1 WHERE days (table1.datecolomn) - days (current date) > 5

for more information check this site

How do you overcome the svn 'out of date' error?

If once solved a similar issue by simply checking out a new working copy and replacing the .svn directory throwing the commit errors with this newly checked out one. The reason in my case was that after a repository corruption and restore from a backup the working copy was pointing towards a revision that didn't exist in the restored repository. Also got "item out of date" errors. Updating the working copy before commit didn't solve this but replacing the .svn as described above did.

Flask-SQLalchemy update a row's information

Retrieve an object using the tutorial shown in the Flask-SQLAlchemy documentation. Once you have the entity that you want to change, change the entity itself. Then, db.session.commit().

For example:

admin = User.query.filter_by(username='admin').first() = '[email protected]'

user = User.query.get(5) = 'New Name'

Flask-SQLAlchemy is based on SQLAlchemy, so be sure to check out the SQLAlchemy Docs as well.

Getting value from a cell from a gridview on RowDataBound event

use RowDataBound function to bind data with a perticular cell, and to get control use (ASP Control Name like DropDownList) GridView.FindControl("Name of Control")

Checkout Jenkins Pipeline Git SCM with credentials?

You can use the following in a pipeline:

git branch: 'master',
    credentialsId: '12345-1234-4696-af25-123455',
    url: 'ssh://[email protected]:company/repo.git'

If you're using the ssh url then your credentials must be username + private key. If you're using the https clone url instead of the ssh one, then your credentials should be username + password.

Button Center CSS

Another nice option is to use :

width: 40%;
margin-left: 30%;
margin-right: 30%

Android: How to set password property in an edit text?

This is deprecated

In xml of EditText iclude this attribute: android:password="true"



How to fire an event on class change using jQuery?

you can use something like this:



$(otherSelector).bind('ClassChanged', data, function(){//stuff });

but otherwise, no, there's no predefined function to fire an event when a class changes.

Read more about triggers here

Can a shell script set environment variables of the calling shell?

You're not going to be able to modify the caller's shell because it's in a different process context. When child processes inherit your shell's variables, they're inheriting copies themselves.

One thing you can do is to write a script that emits the correct commands for tcsh or sh based how it's invoked. If you're script is "setit" then do:

ln -s setit setit-sh


ln -s setit setit-csh

Now either directly or in an alias, you do this from sh

eval `setit-sh`

or this from csh

eval `setit-csh`

setit uses $0 to determine its output style.

This is reminescent of how people use to get the TERM environment variable set.

The advantage here is that setit is just written in whichever shell you like as in:

for nv in \
   if [ x$arg0 = xsetit-sh ]; then
      echo 'export '$nv' ;'
   elif [ x$arg0 = xsetit-csh ]; then
      echo 'setenv '${nv%%=*}' '${nv##*=}' ;'

with the symbolic links given above, and the eval of the backquoted expression, this has the desired result.

To simplify invocation for csh, tcsh, or similar shells:

alias dosetit 'eval `setit-csh`'

or for sh, bash, and the like:

alias dosetit='eval `setit-sh`'

One nice thing about this is that you only have to maintain the list in one place. In theory you could even stick the list in a file and put cat nvpairfilename between "in" and "do".

This is pretty much how login shell terminal settings used to be done: a script would output statments to be executed in the login shell. An alias would generally be used to make invocation simple, as in "tset vt100". As mentioned in another answer, there is also similar functionality in the INN UseNet news server.

Add and remove a class on click using jQuery?

Why not try something like this?

$('#menu li a').on('click', function(){
    $('#menu li a.current').removeClass('current');


Make Bootstrap's Carousel both center AND responsive?

Now (on Boostrap 3 and 4) its simply :

.carousel-inner img {
  margin: auto;

Grouping functions (tapply, by, aggregate) and the *apply family

In the collapse package recently released on CRAN, I have attempted to compress most of the common apply functionality into just 2 functions:

  1. dapply (Data-Apply) applies functions to rows or (default) columns of matrices and data.frames and (default) returns an object of the same type and with the same attributes (unless the result of each computation is atomic and drop = TRUE). The performance is comparable to lapply for data.frame columns, and about 2x faster than apply for matrix rows or columns. Parallelism is available via mclapply (only for MAC).


dapply(X, FUN, ..., MARGIN = 2, parallel = FALSE, mc.cores = 1L, 
       return = c("same", "matrix", "data.frame"), drop = TRUE)


# Apply to columns:
dapply(mtcars, log)
dapply(mtcars, sum)
dapply(mtcars, quantile)
# Apply to rows:
dapply(mtcars, sum, MARGIN = 1)
dapply(mtcars, quantile, MARGIN = 1)
# Return as matrix:
dapply(mtcars, quantile, return = "matrix")
dapply(mtcars, quantile, MARGIN = 1, return = "matrix")
# Same for matrices ...
  1. BY is a S3 generic for split-apply-combine computing with vector, matrix and data.frame method. It is significantly faster than tapply, by and aggregate (an also faster than plyr, on large data dplyr is faster though).


BY(X, g, FUN, ..., use.g.names = TRUE, sort = TRUE,
   expand.wide = FALSE, parallel = FALSE, mc.cores = 1L,
   return = c("same", "matrix", "data.frame", "list"))


# Vectors:
BY(iris$Sepal.Length, iris$Species, sum)
BY(iris$Sepal.Length, iris$Species, quantile)
BY(iris$Sepal.Length, iris$Species, quantile, expand.wide = TRUE) # This returns a matrix 
# Data.frames
BY(iris[-5], iris$Species, sum)
BY(iris[-5], iris$Species, quantile)
BY(iris[-5], iris$Species, quantile, expand.wide = TRUE) # This returns a wider data.frame
BY(iris[-5], iris$Species, quantile, return = "matrix") # This returns a matrix
# Same for matrices ...

Lists of grouping variables can also be supplied to g.

Talking about performance: A main goal of collapse is to foster high-performance programming in R and to move beyond split-apply-combine alltogether. For this purpose the package has a full set of C++ based fast generic functions: fmean, fmedian, fmode, fsum, fprod, fsd, fvar, fmin, fmax, ffirst, flast, fNobs, fNdistinct, fscale, fbetween, fwithin, fHDbetween, fHDwithin, flag, fdiff and fgrowth. They perform grouped computations in a single pass through the data (i.e. no splitting and recombining).


fFUN(x, g = NULL, [w = NULL,] TRA = NULL, [na.rm = TRUE,] use.g.names = TRUE, drop = TRUE)


v <- iris$Sepal.Length
f <- iris$Species

# Vectors
fmean(v)             # mean
fmean(v, f)          # grouped mean
fsd(v, f)            # grouped standard deviation
fsd(v, f, TRA = "/") # grouped scaling
fscale(v, f)         # grouped standardizing (scaling and centering)
fwithin(v, f)        # grouped demeaning

w <- abs(rnorm(nrow(iris)))
fmean(v, w = w)      # Weighted mean
fmean(v, f, w)       # Weighted grouped mean
fsd(v, f, w)         # Weighted grouped standard-deviation
fsd(v, f, w, "/")    # Weighted grouped scaling
fscale(v, f, w)      # Weighted grouped standardizing
fwithin(v, f, w)     # Weighted grouped demeaning

# Same using data.frames...
fmean(iris[-5], f)                # grouped mean
fscale(iris[-5], f)               # grouped standardizing
fwithin(iris[-5], f)              # grouped demeaning

# Same with matrices ...

In the package vignettes I provide benchmarks. Programming with the fast functions is significantly faster than programming with dplyr or data.table, especially on smaller data, but also on large data.

How to see tomcat is running or not

open http://localhost:8080/ in browser, if you get tomcat home page. it means tomcat is running

How to insert special characters into a database?

Are you escaping? Try the mysql_real_escape_string() function and it will handle the special characters.

How to use the read command in Bash?

Another alternative altogether is to use the printf function.

printf -v str 'hello'

Moreover, this construct, combined with the use of single quotes where appropriate, helps to avoid the multi-escape problems of subshells and other forms of interpolative quoting.

How to generate the JPA entity Metamodel?

For eclipselink, only the following dependency is sufficient to generate metamodel. Nothing else is needed.


Sites not accepting wget user agent header

I created a ~/.wgetrc file with the following content (obtained from but with a newer user agent, because otherwise it didn’t work always):

header = Accept-Language: en-us,en;q=0.5
header = Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
header = Connection: keep-alive
user_agent = Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:40.0) Gecko/20100101 Firefox/40.0
referer = /
robots = off

Now I’m able to download from most (all?) file-sharing (streaming video) sites.

How to read a large file line by line?

SplFileObject is useful when it comes to dealing with large files.

function parse_file($filename)
    try {
        $file = new SplFileObject($filename);
    } catch (LogicException $exception) {
        die('SplFileObject : '.$exception->getMessage());
    while ($file->valid()) {
        $line = $file->fgets();
        //do something with $line

    //don't forget to free the file handle.
    $file = null;

How to convert jsonString to JSONObject in Java

Using org.json library:

try {
     JSONObject jsonObject = new JSONObject("{\"phonetype\":\"N95\",\"cat\":\"WP\"}");
}catch (JSONException err){
     Log.d("Error", err.toString());

What's the difference between Instant and LocalDateTime?

One main difference is the Local part of LocalDateTime. If you live in Germany and create a LocalDateTime instance and someone else lives in USA and creates another instance at the very same moment (provided the clocks are properly set) - the value of those objects would actually be different. This does not apply to Instant, which is calculated independently from time zone.

LocalDateTime stores date and time without timezone, but it's initial value is timezone dependent. Instant's is not.

Moreover, LocalDateTime provides methods for manipulating date components like days, hours, months. An Instant does not.

apart from the nanosecond precision advantage of Instant and the time-zone part of LocalDateTime

Both classes have the same precision. LocalDateTime does not store timezone. Read javadocs thoroughly, because you may make a big mistake with such invalid assumptions: Instant and LocalDateTime.

how to setup ssh keys for jenkins to publish via ssh

You will need to create a public/private key as the Jenkins user on your Jenkins server, then copy the public key to the user you want to do the deployment with on your target server.

Step 1, generate public and private key on build server as user jenkins

build1:~ jenkins$ whoami
build1:~ jenkins$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/var/lib/jenkins/.ssh/id_rsa): 
Created directory '/var/lib/jenkins/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /var/lib/jenkins/.ssh/id_rsa.
Your public key has been saved in /var/lib/jenkins/.ssh/
The key fingerprint is:
The key's randomart image is:
build1:~ jenkins$ ls -l .ssh
total 2
-rw-------  1 jenkins  jenkins  1679 Feb 28 11:55 id_rsa
-rw-r--r--  1 jenkins  jenkins   411 Feb 28 11:55 
build1:~ jenkins$ cat .ssh/
ssh-rsa AAAlskdjfalskdfjaslkdjf... [email protected]

Step 2, paste the pub file contents onto the target server.

target:~ bob$ cd .ssh
target:~ bob$ vi authorized_keys (paste in the stuff which was output above.)

Make sure your .ssh dir has permissoins 700 and your authorized_keys file has permissions 644

Step 3, configure Jenkins

  1. In the jenkins web control panel, nagivate to "Manage Jenkins" -> "Configure System" -> "Publish over SSH"
  2. Either enter the path of the file e.g. "var/lib/jenkins/.ssh/id_rsa", or paste in the same content as on the target server.
  3. Enter your passphrase, server and user details, and you are good to go!

How do I execute external program within C code in linux with arguments?

system() executes a shell which is then responsible for parsing the arguments and executing the desired program. To execute the program directly, use fork() and exec() (which is what system() uses to execute the shell as well as what the shell itself uses to execute commands).

#include <unistd.h>

int main() {
     if (fork() == 0) {
           * fork() returns 0 to the child process
           * and the child's PID to the parent.
          execl("/path/to/foo", "foo", "arg1", "arg2", "arg3", 0);
           * We woundn't still be here if execl() was successful,
           * so a non-zero exit value is appropriate.
          return 1;

     return 0;

Razor/CSHTML - Any Benefit over what we have?

One of the benefits is that Razor views can be rendered inside unit tests, this is something that was not easily possible with the previous ASP.Net renderer.

From ScottGu's announcement this is listed as one of the design goals:

Unit Testable: The new view engine implementation will support the ability to unit test views (without requiring a controller or web-server, and can be hosted in any unit test project – no special app-domain required).

How to make responsive table

For make responsive table you can make 100% of each ‘td’ and insert related heading in the ‘td’ on the mobile(less the ’768px’ width).

See More:

Flash CS4 refuses to let go

Do you have several swf-files? If your class is imported in one of the swf's, other swf's will also use the same version of the class. One old import with * in one swf will do it. Recompile everything and see if it works.

C# convert int to string with padding zeros?

You can use:

int x = 1;

Use PHP to convert PNG to JPG with compression?

Be careful of what you want to convert. JPG doesn't support alpha-transparency while PNG does. You will lose that information.

To convert, you may use the following function:

// Quality is a number between 0 (best compression) and 100 (best quality)
function png2jpg($originalFile, $outputFile, $quality) {
    $image = imagecreatefrompng($originalFile);
    imagejpeg($image, $outputFile, $quality);

This function uses the imagecreatefrompng() and the imagejpeg() functions from the GD library.

PHP sessions that have already been started

session_status() === PHP_SESSION_ACTIVE ?: session_start();

Closed Game

Need a row count after SELECT statement: what's the optimal SQL approach?

SELECT my_table.my_col
  FROM my_table
 WHERE = 'bar'

How to make the first option of <select> selected with jQuery

You can select any option from dropdown by using it.

// 'N' can by any number of option.  // e.g.,  N=1 for first option
$("#DropDownId").val($("#DropDownId option:eq(N-1)").val()); 

How can I enable the Windows Server Task Scheduler History recording?

Here is where I found it on a Windows 2008R2 server. Elevated Task Scheduler Click on "Task Scheduler Library" It appears as an option on the right hand "Actions" panel.

enter image description here

How can I split a text into sentences?

i hope this will help you on latin,chinese,arabic text

import re

punctuation = re.compile(r"([^\d+])(\.|!|\?|;|\n|?|!|?|;|…| |!|?|?)+")
lines = []

with open('myData.txt','r',encoding="utf-8") as myFile:
    lines = punctuation.sub(r"\1\2<pad>",
    lines = [line.strip() for line in lines.split("<pad>") if line.strip()]

How to add background image for input type="button"?

If this is a submit button, use <input type="image" src="..." ... />.

If you want to specify the image with CSS, you'll have to use type="submit".

Way to run Excel macros from command line or batch file?

You can check if Excel is already open. There is no need to create another isntance

   If CheckAppOpen("excel.application")  Then
           'MsgBox "App Loaded"
            Set xlApp = GetObject(, "excel.Application")   
            ' MsgBox "App Not Loaded"
            Set  wrdApp = CreateObject(,"excel.Application")   
   End If

Batch script to delete files

Lets say you saved your software onto your desktop.
if you want to remove an entire folder like an uninstaller program you could use this.

cd C:\Users\User\Detsktop\
rd /s /q SOFTWARE

this will delete the entire folder called software and all of its files and subfolders

Make Sure You Delete The Correct Folder Cause This Does Not Have A Yes / No Option

How to get a file or blob from an object URL?

See Getting BLOB data from XHR request which points out that BlobBuilder doesn't work in Chrome so you need to use:

xhr.responseType = 'arraybuffer';

Failed to build gem native extension — Rails install

The suggested answer only works for certain versions of ruby. Some commenters suggest using ruby-dev; that didn't work for me either.

sudo apt-get install ruby-all-dev

worked for me.

How to send email using simple SMTP commands via Gmail?

to send over gmail, you need to use an encrypted connection. this is not possible with telnet alone, but you can use tools like openssl

either connect using the starttls option in openssl to convert the plain connection to encrypted...

openssl s_client -starttls smtp -connect -crlf -ign_eof

or connect to a ssl sockect directly...

openssl s_client -connect -crlf -ign_eof

EHLO localhost

after that, authenticate to the server using the base64 encoded username/password

AUTH PLAIN AG15ZW1haWxAZ21haWwuY29tAG15cGFzc3dvcmQ=

to get this from the commandline:

echo -ne '\[email protected]\00password' | base64

then continue with "mail from:" like in your example

example session:

openssl s_client -connect -crlf -ign_eof
[... lots of openssl output ...]
220 ESMTP m46sm11546481eeh.9
EHLO localhost at your service, []
250-SIZE 35882577
AUTH PLAIN AG5pY2UudHJ5QGdtYWlsLmNvbQBub2l0c25vdG15cGFzc3dvcmQ=
235 2.7.0 Accepted
MAIL FROM: <[email protected]>
250 2.1.0 OK m46sm11546481eeh.9
rcpt to: <[email protected]>
250 2.1.5 OK m46sm11546481eeh.9
354  Go ahead m46sm11546481eeh.9
Subject: it works

250 2.0.0 OK 1339757532 m46sm11546481eeh.9
221 2.0.0 closing connection m46sm11546481eeh.9

If Cell Starts with Text String... Formula

I know this is a really old post, but I found it in searching for a solution to the same problem. I don't want a nested if-statement, and Switch is apparently newer than the version of Excel I'm using. I figured out what was going wrong with my code, so I figured I'd share here in case it helps someone else.

I remembered that VLOOKUP requires the source table to be sorted alphabetically/numerically for it to work. I was initially trying to do this...

=LOOKUP(LOWER(LEFT($T$3, 1)),  {"s","l","m"}, {-1,1,0})

and it started working when I did this...

=LOOKUP(LOWER(LEFT($T$3, 1)),  {"l","m","s"}, {1,0,-1})

I was initially thinking the last value might turn out to be a default, so I wanted the zero at the last place. That doesn't seem to be the behavior anyway, so I just put the possible matches in order, and it worked.

Edit: As a final note, I see that the example in the original post has letters in alphabetical order, but I imagine the real use case might have been different if the error was happening and the letters A, B, and C were just examples.

How to make a class JSON serializable

This class can do the trick, it converts object to standard json .

import json

class Serializer(object):
    def serialize(object):
        return json.dumps(object, default=lambda o: o.__dict__.values()[0])



working in python2.7 and python3.

How to check if IsNumeric

Other answers have suggested using TryParse, which might fit your needs, but the safest way to provide the functionality of the IsNumeric function is to reference the VB library and use the IsNumeric function.

IsNumeric is more flexible than TryParse. For example, IsNumeric returns true for the string "$100", while the TryParse methods all return false.

To use IsNumeric in C#, add a reference to Microsoft.VisualBasic.dll. The function is a static method of the Microsoft.VisualBasic.Information class, so assuming you have using Microsoft.VisualBasic;, you can do this:

if (Information.IsNumeric(txtMyText.Text.Trim())) //...

What resources are shared between threads?

A process has code, data, heap and stack segments. Now, the Instruction Pointer (IP) of a thread OR threads points to the code segment of the process. The data and heap segments are shared by all the threads. Now what about the stack area? What is actually the stack area? Its an area created by the process just for its thread to use... because stacks can be used in a much faster way than heaps etc. The stack area of the process is divided among threads, i.e. if there are 3 threads, then the stack area of the process is divided into 3 parts and each is given to the 3 threads. In other words, when we say that each thread has its own stack, that stack is actually a part of the process stack area allocated to each thread. When a thread finishes its execution, the stack of the thread is reclaimed by the process. In fact, not only the stack of a process is divided among threads, but all the set of registers that a thread uses like SP, PC and state registers are the registers of the process. So when it comes to sharing, the code, data and heap areas are shared, while the stack area is just divided among threads.

How do you uninstall all dependencies listed in package.json (NPM)?

Piggy-backing off of VIKAS KOHLI and jedmao, you can do this

single line version:

npm uninstall `ls -1 node_modules | grep -v ^@ | tr '/\n' ' '` `find node_modules/@* -type d -depth 1 2>/dev/null | cut -d/ -f2-3 | tr '\n' ' '`

multi-lined version:

npm uninstall \
`ls -1 node_modules | grep -v ^@ | tr '/\n' ' '` \
`find node_modules/@* -type d -depth 1 2>/dev/null | cut -d/ -f2-3 | tr '\n' ' '`


To call GET,POST,DELETE,PUT All kind of request, i have created one common function

function CallAPI($method, $api, $data) {
    $url = "http://localhost:82/slimdemo/RESTAPI/" . $api;
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

    switch ($method) {
        case "GET":
            curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data));
            curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "GET");
        case "POST":
            curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data));
            curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "POST");
        case "PUT":
            curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data));
            curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "PUT");
        case "DELETE":
            curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "DELETE"); 
            curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data));
    $response = curl_exec($curl);
    $data = json_decode($response);

    /* Check for 404 (file not found). */
    $httpCode = curl_getinfo($curl, CURLINFO_HTTP_CODE);
    // Check the HTTP Status code
    switch ($httpCode) {
        case 200:
            $error_status = "200: Success";
            return ($data);
        case 404:
            $error_status = "404: API Not found";
        case 500:
            $error_status = "500: servers replied with an error.";
        case 502:
            $error_status = "502: servers may be down or being upgraded. Hopefully they'll be OK soon!";
        case 503:
            $error_status = "503: service unavailable. Hopefully they'll be OK soon!";
            $error_status = "Undocumented error: " . $httpCode . " : " . curl_error($curl);
    echo $error_status;

CALL Delete Method

$data = array('id'=>$_GET['did']);
$result = CallAPI('DELETE', "DeleteCategory", $data);

CALL Post Method

$data = array('title'=>$_POST['txtcategory'],'description'=>$_POST['txtdesc']);
$result = CallAPI('POST', "InsertCategory", $data);

CALL Get Method

$data = array('id'=>$_GET['eid']);
$result = CallAPI('GET', "GetCategoryById", $data);

CALL Put Method

$data = array('id'=>$_REQUEST['eid'],m'title'=>$_REQUEST['txtcategory'],'description'=>$_REQUEST['txtdesc']);
$result = CallAPI('POST', "UpdateCategory", $data);

Correctly ignore all files recursively under a specific folder except for a specific file type

This might look stupid, but check if you haven't already added the folder/files you are trying to ignore to the index before. If you did, it does not matter what you put in your .gitignore file, the folders/files will still be staged.

How do I add the contents of an iterable to a set?

for item in items:

For the record, I think the assertion that "There should be one-- and preferably only one --obvious way to do it." is bogus. It makes an assumption that many technical minded people make, that everyone thinks alike. What is obvious to one person is not so obvious to another.

I would argue that my proposed solution is clearly readable, and does what you ask. I don't believe there are any performance hits involved with it--though I admit I might be missing something. But despite all of that, it might not be obvious and preferable to another developer.

How to convert DateTime to VarChar

select REPLACE(CONVERT(VARCHAR, FORMAT(GETDATE(), N'dd/MM/yyyy hh:mm:ss tt')),'.', '/')

will give 05/05/2020 10:41:05 AM as a result

How do I spool to a CSV formatted file using SQLPLUS?

spool D:\test.txt

    select * from emp
    spool off

Why there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT clause?

Combining various answers :



1) at most one TIMESTAMP column per table could be automatically (or manually[My addition]) initialized or updated to the current date and time. (MySQL Docs).


2) The first NOT NULL TIMESTAMP column without an explicit DEFAULT value like created_date timestamp default '0000-00-00 00:00:00' will be implicitly given a DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP and hence subsequent TIMESTAMP columns cannot be given CURRENT_TIMESTAMP on DEFAULT or ON UPDATE clause

CREATE TABLE `address` (
  `village` int(11) DEFAULT NULL,
    `created_date` timestamp default '0000-00-00 00:00:00', 

    -- Since explicit DEFAULT value that is not CURRENT_TIMESTAMP is assigned for a NOT NULL column, 
    -- implicit DEFAULT CURRENT_TIMESTAMP is avoided.
    -- So it allows us to set ON UPDATE CURRENT_TIMESTAMP on 'updated_date' column.
    -- How does setting DEFAULT to '0000-00-00 00:00:00' instead of CURRENT_TIMESTAMP help? 
    -- It is just a temporary value.
    -- On INSERT of explicit NULL into the column inserts current timestamp.

-- `created_date` timestamp not null default '0000-00-00 00:00:00', // same as above

-- `created_date` timestamp null default '0000-00-00 00:00:00', 
-- inserting 'null' explicitly in INSERT statement inserts null (Ignoring the column inserts the default value)! 
-- Remember we need current timestamp on insert of 'null'. So this won't work. 

-- `created_date` timestamp null , // always inserts null. Equally useless as above. 

-- `created_date` timestamp default 0, // alternative to '0000-00-00 00:00:00'

-- `created_date` timestamp, 
-- first 'not null' timestamp column without 'default' value. 
-- Hence cannot add 'ON UPDATE CURRENT_TIMESTAMP' on 'updated_date' column.

   `updated_date` timestamp null on update current_timestamp,

  PRIMARY KEY (`id`)

INSERT INTO address (village,created_date) VALUES (100,null);

mysql> select * from address;
| id  | village | created_date        | updated_date |
| 132 |     100 | 2017-02-18 04:04:00 | NULL         |
1 row in set (0.00 sec)

UPDATE address SET village=101 WHERE village=100;

mysql> select * from address;
| id  | village | created_date        | updated_date        |
| 132 |     101 | 2017-02-18 04:04:00 | 2017-02-18 04:06:14 |
1 row in set (0.00 sec)

Other option (But updated_date is the first column):

CREATE TABLE `address` (
  `village` int(11) DEFAULT NULL,
  `updated_date` timestamp null on update current_timestamp,
  `created_date` timestamp not null , 
  -- implicit default is '0000-00-00 00:00:00' from 2nd timestamp onwards

  -- `created_date` timestamp not null default '0000-00-00 00:00:00'
  -- `created_date` timestamp
  -- `created_date` timestamp default '0000-00-00 00:00:00'
  PRIMARY KEY (`id`)

How to check object is nil or not in swift?

Swift short expression:

var abc = "string"
abc != nil ? doWork(abc) : ()


abc == nil ? () : abc = "string"

or both:

abc != nil ? doWork(abc) : abc = "string"

What is the easiest way to initialize a std::vector with hardcoded elements?

There are various ways to hardcode a vector, i will share few ways:

  1. Initializing by pushing values one by one
// Create an empty vector 
    vector<int> vect;  

  1. Initializing like arrays
vector<int> vect{ 10, 20, 30 };
  1. Initializing from an array
    int arr[] = { 10, 20, 30 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 

    vector<int> vect(arr, arr + n); 
  1. Initializing from another vector
    vector<int> vect1{ 10, 20, 30 }; 

    vector<int> vect2(vect1.begin(), vect1.end()); 

how to make a specific text on TextView BOLD

Make first char of string spannable while searching for char in list/recycler like

ravi and ajay

previously highlighting like this but i wanted to be like below

ravi and ajay OR ravi and ajay

for this I searched for word length if it is equal to 1 ,I separated main string into words and calculated word start position then I searched word starting with char.

 public static SpannableString colorString(int color, String text, String... wordsToColor) {
    SpannableString coloredString = new SpannableString(text);

    for (String word : wordsToColor) {

        Log.e("tokentoken", "-wrd len-" + word.length());
        if (word.length() !=1) {
            int startColorIndex = text.toLowerCase().indexOf(word.toLowerCase());
            int endColorIndex = startColorIndex + word.length();
            try {
                coloredString.setSpan(new ForegroundColorSpan(color), startColorIndex, endColorIndex,

            } catch (Exception e) {
        } else {
            int start = 0;

            for (String token : text.split("[\u00A0 \n]")) {
                if (token.length() > 0) {
                    start = text.indexOf(token, start);
                   // Log.e("tokentoken", "-token-" + token + "   --start--" + start);
                    char x = token.toLowerCase().charAt(0);
                    char w = word.toLowerCase().charAt(0);
                   // Log.e("tokentoken", "-w-" + w + "   --x--" + x);

                    if (x == w) {
                        // int startColorIndex = text.toLowerCase().indexOf(word.toLowerCase());
                        int endColorIndex = start + word.length();
                        try {
                            coloredString.setSpan(new ForegroundColorSpan(color), start, endColorIndex,

                        } catch (Exception e) {



    return coloredString;

Is there a way to change the spacing between legend items in ggplot2?

To add spacing between entries in a legend, adjust the margins of the theme element legend.text.

To add 30pt of space to the right of each legend label (may be useful for a horizontal legend):

p + theme(legend.text = element_text(
    margin = margin(r = 30, unit = "pt")))

To add 30pt of space to the left of each legend label (may be useful for a vertical legend):

p + theme(legend.text = element_text(
    margin = margin(l = 30, unit = "pt")))

for a ggplot2 object p. The keywords are legend.text and margin.

[Note about edit: When this answer was first posted, there was a bug. The bug has now been fixed]

Javascript pass values using POST

I used a variation of the above but instead of printing html I built a form and submitted it to the 3rd party url:

    var mapForm = document.createElement("form"); = "Map";
    mapForm.method = "POST"; // or "post" if appropriate
    mapForm.action = "";

    var mapInput = document.createElement("input");
    mapInput.type = "text"; = "addrs";
    mapInput.value = data;


    map ="", "Map", "status=0,title=0,height=600,width=800,scrollbars=1");

if (map) {
} else {
    alert('You must allow popups for this map to work.');

Make div fill remaining space along the main axis in flexbox

Basically I was trying to get my code to have a middle section on a 'row' to auto-adjust to the content on both sides (in my case, a dotted line separator). Like @Michael_B suggested, the key is using display:flex on the row container and at least making sure your middle container on the row has a flex-grow value of at least 1 higher than the outer containers (if outer containers don't have any flex-grow properties applied, middle container only needs 1 for flex-grow).

Here's a pic of what I was trying to do and sample code for how I solved it.

enter image description here

.row {
  background: lightgray;
  height: 30px;
  width: 100%;
  display: flex;
.left {
  border-bottom:dotted 2px black;
.right {
<div class="row">
  <div class="left">Left</div>
  <div class="separator"></div>
  <div class="right">Right With Text</div>
<div class="row">
  <div class="left">Left With More Text</div>
  <div class="separator"></div>
  <div class="right">Right</div>
<div class="row">
  <div class="left">Left With Text</div>
  <div class="separator"></div>
  <div class="right">Right With More Text</div>

How to use range-based for() loop with std::map?

If you only want to see the keys/values from your map and like using boost, you can use the boost adaptors with the range based loops:

for (const auto& value : myMap | boost::adaptors::map_values)
    std::cout << value << std::endl;

there is an equivalent boost::adaptors::key_values

Find current directory and file's directory

If you are trying to find the current directory of the file you are currently in:

OS agnostic way:

dirname, filename = os.path.split(os.path.abspath(__file__)) as modal popup?

I agree with both previous answers. Basically, you want to use what is known as a "lightbox" -

It is essentially a div than is created within the DOM of your current window/tab. In addition to the div that contains your dialog, a transparent overlay blocks the user from engaging all underlying elements. This can effectively create a modal dialog (i.e. user MUST make some kind of decision before moving on).

Programmatically get own phone number in iOS

At the risk of getting negative marks, I want to suggest that the highest ranking solution (currently the first response) violates the latest SDK Agreement as of Nov 5, 2009. Our application was just rejected for using it. Here's the response from Apple:

"For security reasons, iPhone OS restricts an application (including its preferences and data) to a unique location in the file system. This restriction is part of the security feature known as the application's "sandbox." The sandbox is a set of fine-grained controls limiting an application's access to files, preferences, network resources, hardware, and so on."

The device's phone number is not available within your application's container. You will need to revise your application to read only within your directory container and resubmit your binary to iTunes Connect in order for your application to be reconsidered for the App Store.

This was a real disappointment since we wanted to spare the user having to enter their own phone number.

Using setDate in PreparedStatement

The docs explicitly says that java.sql.Date will throw:

  • IllegalArgumentException - if the date given is not in the JDBC date escape format (yyyy-[m]m-[d]d)

Also you shouldn't need to convert a date to a String then to a, this seems superfluous (and bug-prone!). Instead you could:

java.sql.Date sqlDate := new java.sql.Date(now.getTime());
prs.setDate(2, sqlDate);
prs.setDate(3, sqlDate);

Replace a string in shell script using a variable

Single quotes are very strong. Once inside, there's nothing you can do to invoke variable substitution, until you leave. Use double quotes instead:

echo $LINE | sed -e "s/12345678/$replace/g"

Android LinearLayout Gradient Background

It is also possible to have the third color (center). And different kinds of shapes.

For example in drawable/gradient.xml:

        android:angle="0" />

This gives you black - gray - black (left to right) which is my favorite dark background atm.

Remember to add gradient.xml as background in your layout xml:


It is also possible to rotate, with:


gives you a vertical line

and with


gives you a horizontal line

Possible angles are:

0, 90, 180, 270.

Also there are few different kind of shapes:


Rounded shape:


and problably a few more.

Hope it helps, cheers!

How to get base URL in Web API controller?

send a GET to a page and the content replied will be the answer.Base url : http://website/api/

PostgreSQL delete with inner join

Just use a subquery with INNER JOIN, LEFT JOIN or smth else:

DELETE FROM m_productprice
WHERE m_product_id IN
  SELECT B.m_product_id
  FROM   m_productprice  B
    INNER JOIN m_product C 
    ON   B.m_product_id = C.m_product_id
  WHERE  C.upc = '7094' 
  AND    B.m_pricelist_version_id = '1000020'

to optimize the query,

Any way to generate ant build.xml file automatically from Eclipse?

Right-click on an Eclipse project then "Export" then "General" then "Ant build files". I don't think it is possible to customise the output format though.

How to make Java work with SQL Server?

Maybe a little late, but using different drivers altogether is overkill for a case of user error:

db.dbConnect("jdbc:sqlserver://localhost:1433/muff", "user", "pw" );

should be either one of these:

db.dbConnect("jdbc:sqlserver://localhost\muff", "user", "pw" );

(using named pipe) or:

db.dbConnect("jdbc:sqlserver://localhost:1433", "user", "pw" );

using port number directly; you can leave out 1433 because it's the default port, leaving:

db.dbConnect("jdbc:sqlserver://localhost", "user", "pw" );

Tomcat manager/html is not available?

You have to check if you have the folder with name manager inside the folder webapps in your tomcat.

Rubens-MacBook-Pro:tomcat rfanjul$ ls -la webapps/
total 16
drwxr-xr-x   8 rfanjul  staff   272 21 May 12:20 .
drwxr-xr-x  14 rfanjul  staff   476 21 May 12:22 ..
-rw-r--r--@  1 rfanjul  staff  6148 21 May 12:20 .DS_Store
drwxr-xr-x  19 rfanjul  staff   646 17 Feb 15:13 ROOT
drwxr-xr-x  51 rfanjul  staff  1734 17 Feb 15:13 docs
drwxr-xr-x   6 rfanjul  staff   204 17 Feb 15:13 examples
drwxr-xr-x   7 rfanjul  staff   238 17 Feb 15:13 host-manager
drwxr-xr-x   8 rfanjul  staff   272 17 Feb 15:13 manager

After that you will be sure that you have this permmint for you user in the file conf/tomcat-users.xml:

<role rolename="admin-gui"/>
<role rolename="manager-gui"/>
<user username="test" password="test" roles="admin-gui,manager-gui"/>

restart tomcat and stat tomcat again.

sh bin/ 
sh bin/

I hope that will works fine for you.

What is the => assignment in C# in a property signature

What you're looking at is an expression-bodied member not a lambda expression.

When the compiler encounters an expression-bodied property member, it essentially converts it to a getter like this:

public int MaxHealth
        return Memory[Address].IsValid ? Memory[Address].Read<int>(Offs.Life.MaxHp) : 0;

(You can verify this for yourself by pumping the code into a tool called TryRoslyn.)

Expression-bodied members - like most C# 6 features - are just syntactic sugar. This means that they don’t provide functionality that couldn't otherwise be achieved through existing features. Instead, these new features allow a more expressive and succinct syntax to be used

As you can see, expression-bodied members have a handful of shortcuts that make property members more compact:

  • There is no need to use a return statement because the compiler can infer that you want to return the result of the expression
  • There is no need to create a statement block because the body is only one expression
  • There is no need to use the get keyword because it is implied by the use of the expression-bodied member syntax.

I have made the final point bold because it is relevant to your actual question, which I will answer now.

The difference between...

// expression-bodied member property
public int MaxHealth => x ? y:z;


// field with field initializer
public int MaxHealth = x ? y:z;

Is the same as the difference between...

public int MaxHealth
        return x ? y:z;


public int MaxHealth = x ? y:z;

Which - if you understand properties - should be obvious.

Just to be clear, though: the first listing is a property with a getter under the hood that will be called each time you access it. The second listing is is a field with a field initializer, whose expression is only evaluated once, when the type is instantiated.

This difference in syntax is actually quite subtle and can lead to a "gotcha" which is described by Bill Wagner in a post entitled "A C# 6 gotcha: Initialization vs. Expression Bodied Members".

While expression-bodied members are lambda expression-like, they are not lambda expressions. The fundamental difference is that a lambda expression results in either a delegate instance or an expression tree. Expression-bodied members are just a directive to the compiler to generate a property behind the scenes. The similarity (more or less) starts and end with the arrow (=>).

I'll also add that expression-bodied members are not limited to property members. They work on all these members:

  • Properties
  • Indexers
  • Methods
  • Operators

Added in C# 7.0

However, they do not work on these members:

  • Nested Types
  • Events
  • Fields

Install Android App Bundle on device

Use (on Linux): cd android ./gradlew assemblyRelease|assemblyDebug

An unsigned APK is generated for each case (for debug or testing)

NOTE: On Windows, replace gradle executable for gradlew.bat

Syntax for async arrow function

My async function

const getAllRedis = async (key) => {
  let obj = [];

  await client.hgetall(key, (err, object) => {
    console.log(object);, (ob)=>{
    return obj;
    // res.send(obj);