Programs & Examples On #Createtextnode

This method is used to create a new text node within the HTML/XML document.

adding text to an existing text element in javascript via DOM

remove .textContent from var t = document.getElementById("p").textContent;

var t = document.getElementById("p");_x000D_
var y = document.createTextNode("This just got added");_x000D_
<p id ="p">This is some text</p>

Uncaught TypeError: Cannot read property 'appendChild' of null

those getting querySelector or getElementById that returns the following error:

Uncaught TypeError: Cannot read property 'appendChild' of null

or any other property, even if you have a class name or id in the HTML

don't use (defer as it is too much browser dependent.)

<script src="script.js" defer></script>  //don't use this

instead, put all your code in 'script.js' inside

    //your script here.

Javascript loading CSV file into an array

The original code works fine for reading and separating the csv file data but you need to change the data type from csv to text.

Javascript Uncaught Reference error Function is not defined

In JSFiddle, when you set the wrapping to "onLoad" or "onDomready", the functions you define are only defined inside that block, and cannot be accessed by outside event handlers.

Easiest fix is to change:

function something(...)


window.something = function(...)

how to add new <li> to <ul> onclick with javascript

You were almost there:

You just need to append the li to ul and voila!

So just add


to the end of your function so the end function will be like this:

function function1() {
  var ul = document.getElementById("list");
  var li = document.createElement("li");
  li.appendChild(document.createTextNode("Element 4"));

Creating SVG elements dynamically with javascript inside HTML

Add this to html:

<svg id="mySVG" xmlns="" xmlns:xlink=""/>

Try this function and adapt for you program:

var svgNS = "";  

function createCircle()
    var myCircle = document.createElementNS(svgNS,"circle"); //to create a circle. for rectangle use "rectangle"


JavaScript Adding an ID attribute to another created Element

Since id is an attribute don't create an id element, just do this:

myPara.setAttribute("id", "id_you_like");

jQuery append() vs appendChild()

No longer

now append is a method in JavaScript

MDN documentation on append method

Quoting MDN

The ParentNode.append method inserts a set of Node objects or DOMString objects after the last child of the ParentNode. DOMString objects are inserted as equivalent Text nodes.

This is not supported by IE and Edge but supported by Chrome(54+), Firefox(49+) and Opera(39+).

The JavaScript's append is similar to jQuery's append.

You can pass multiple arguments.

var elm = document.getElementById('div1');
<div id="div1"></div>

Create table using Javascript

Here is the latest method using the .map function in javascript.

Simple table code..

<table class="table table-hover">
    <thead class="thead-dark">
         <th scope="col">Tour</th>
         <th scope="col">Day</th>
         <th scope="col">Time</th>
         <th scope="col">Highlights</th>
         <th scope="col">Action</th>
  <tbody id="tableBody">

and here is javascript code to append something in the table body.

    const data = "some kind of json data or object of arrays";
                const tableData ={
                    return (
                            <td class="text-center"><a class="btn btn-primary" href="route.html?id=${value.ID}" role="button">Details</a></td>
            const tabelBody = document.querySelector("#tableBody");
                tableBody.innerHTML = tableData;

Creating a div element inside a div element in javascript

Yes, you either need to do this onload or in a <script> tag after the closing </body> tag, when the lc element is already found in the document's DOM tree.

PHP XML how to output nice format


$xml = $argv[1];

$dom = new DOMDocument();

// Initial block (must before load xml string)
$dom->preserveWhiteSpace = false;
$dom->formatOutput = true;
// End initial block

$out = $dom->saveXML();


Dynamic creation of table with DOM

You can create a dynamic table rows as below:

var tbl = document.createElement('table'); = '100%';

for (var i = 0; i < files.length; i++) {

        tr = document.createElement('tr');

        var td1 = document.createElement('td');
        var td2 = document.createElement('td');
        var td3 = document.createElement('td');

        ::::: // As many <td> you want




How do I append a node to an existing XML file in java

The following complete example will read an existing server.xml file from the current directory, append a new Server and re-write the file to server.xml. It does not work without an existing .xml file, so you will need to modify the code to handle that case.

import java.util.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.*;
import org.w3c.dom.*;
import javax.xml.parsers.*;

public class AddXmlNode {
    public static void main(String[] args) throws Exception {

        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
        Document document = documentBuilder.parse("server.xml");
        Element root = document.getDocumentElement();

        Collection<Server> servers = new ArrayList<Server>();
        servers.add(new Server());

        for (Server server : servers) {
            // server elements
            Element newServer = document.createElement("server");

            Element name = document.createElement("name");

            Element port = document.createElement("port");


        DOMSource source = new DOMSource(document);

        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer transformer = transformerFactory.newTransformer();
        StreamResult result = new StreamResult("server.xml");
        transformer.transform(source, result);

    public static class Server {
        public String getName() { return "foo"; }
        public Integer getPort() { return 12345; }

Example server.xml file:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

The main change to your code is not creating a new "root" element. The above example just uses the current root node from the existing server.xml and then just appends a new Server element and re-writes the file.

Error on line 2 at column 1: Extra content at the end of the document

On each loop of the result set, you're appending a new root element to the document, creating an XML document like this:

<?xml version="1.0"?>

An XML document can only have one root element, which is why the error is stating there is "extra content". Create a single root element and add all the mycatch elements to that:

$root = $dom->createElement("root");
// ...
while ($row = @mysql_fetch_assoc($result)){
  $node = $dom->createElement("mycatch");

Add CSS to <head> with JavaScript?

Here's a simple way.

 * Add css to the document
 * @param {string} css
function addCssToDocument(css){
  var style = document.createElement('style')
  style.innerText = css

Get the last item in an array

Not sure if there's a drawback, but this seems quite concise:




Both will return undefined if the array is empty.

Executing <script> elements inserted with .innerHTML

The OP's script doesn't work in IE 7. With help from SO, here's a script that does:

exec_body_scripts: function(body_el) {
  // Finds and executes scripts in a newly added element's body.
  // Needed since innerHTML does not run scripts.
  // Argument body_el is an element in the dom.

  function nodeName(elem, name) {
    return elem.nodeName && elem.nodeName.toUpperCase() ===

  function evalScript(elem) {
    var data = (elem.text || elem.textContent || elem.innerHTML || "" ),
        head = document.getElementsByTagName("head")[0] ||
        script = document.createElement("script");

    script.type = "text/javascript";
    try {
      // doesn't work on ie...
    } catch(e) {
      // IE has funky script nodes
      script.text = data;

    head.insertBefore(script, head.firstChild);

  // main section of function
  var scripts = [],
      children_nodes = body_el.childNodes,

  for (i = 0; children_nodes[i]; i++) {
    child = children_nodes[i];
    if (nodeName(child, "script" ) &&
      (!child.type || child.type.toLowerCase() === "text/javascript")) {

  for (i = 0; scripts[i]; i++) {
    script = scripts[i];
    if (script.parentNode) {script.parentNode.removeChild(script);}

Get the string representation of a DOM node


new XMLSerializer().serializeToString(element);

Creating the checkbox dynamically using JavaScript?

   /* worked for me  */
     <div id="divid"> </div>
     <script type="text/javascript">
         var hold = document.getElementById("divid");
         var checkbox = document.createElement('input');
         checkbox.type = "checkbox"; = "chkbox1"; = "cbid";
         var label = document.createElement('label');
         var tn = document.createTextNode("Not A RoBot");

Can you split a stream into two streams?

I stumbled across this question while looking for a way to filter certain elements out of a stream and log them as errors. So I did not really need to split the stream so much as attach a premature terminating action to a predicate with unobtrusive syntax. This is what I came up with:

public class MyProcess {
    /* Return a Predicate that performs a bail-out action on non-matching items. */
    private static <T> Predicate<T> withAltAction(Predicate<T> pred, Consumer<T> altAction) {
    return x -> {
        if (pred.test(x)) {
            return true;
        return false;

    /* Example usage in non-trivial pipeline */
    public void processItems(Stream<Item> stream) {
                                    i -> logError(i, "Invalid")))
              .filter(withAltAction(i -> i.size() > 10,
                                    i -> logError(i, "Too large")))

How to apply bold text style for an entire row using Apache POI?

Please find below the easy way :

XSSFCellStyle style = workbook.createCellStyle();
style.setBorderTop((short) 6); // double lines border
style.setBorderBottom((short) 1); // single line border
XSSFFont font = workbook.createFont();
font.setFontHeightInPoints((short) 15);

Row row = sheet.createRow(0);   
Cell cell0 = row.createCell(0);
cell0.setCellValue("Nav Value");
for(int j = 0; j<=3; j++)

How to populate HTML dropdown list with values from database

Use OOP concept instead. Create a class with function

class MyClass {


function getData($query) {
    $result = mysqli_query($this->conn, $query);
    while($row=mysqli_fetch_assoc($result)) {
        $resultset[] = $row;
        return $resultset;
} }

and then use the class object to call function in your code


    $obj = new MyClass();
    $row = $obj->getData("select city_name from city"); 
    <?php foreach($row as $row){ ?>
        <option><?php echo $row['city_name'] ?></option>

<?php  } ?>

Full code and description can be found here

How do I see which checkbox is checked?

Try this


<form action="form.php" method="post">
    Do you like stackoverflow?
    <input type="checkbox" name="like" value="Yes" />  
    <input type="submit" name="formSubmit" value="Submit" /> 



        echo "<h1>You like Stackoverflow.<h1>";
        echo "<h1>You don't like Stackoverflow.</h1>";


Or this

    if(isset($_POST['like'])) && 
    $_POST['like'] == 'Yes') 
        echo "You like Stackoverflow.";
        echo "You don't like Stackoverflow.";

How do I delete specific lines in Notepad++?

Notepad++ v6.5

  1. Search menu -> Find... -> Mark tab -> Find what: your search text, check Bookmark Line, then Mark All. This will bookmark all the lines with the search term, you'll see the blue circles in the margin.

  2. Then Search menu -> Bookmark -> Remove Bookmarked Lines. This will delete all the bookmarked lines.

You can also use a regex to search. This method won't result in a blank line like John's and will actually delete the line.

Older Versions

  1. Search menu -> Find... -> Find what: your search text, check Bookmark Line and click Find All.
  2. Then Search -> Bookmark -> Remove Bookmarked Lines

android image button

You can use the button :

1 - make the text empty

2 - set the background for it

+3 - you can use the selector to more useful and nice button

About the imagebutton you can set the image source and the background the same picture and it must be (*.png) when you do it you can make any design for the button

and for more beauty button use the selector //just Google it ;)

null vs empty string in Oracle

In oracle an empty varchar2 and null are treated the same, and your observations show that.

when you write:

select * from table where a = '';

its the same as writing

select * from table where a = null;

and not a is null

which will never equate to true, so never return a row. same on the insert, a NOT NULL means you cant insert a null or an empty string (which is treated as a null)

IndexOf function in T-SQL

One very small nit to pick:

The RFC for email addresses allows the first part to include an "@" sign if it is quoted. Example:


This is quite uncommon, but could happen. Theoretically, you should split on the last "@" symbol, not the first:

SELECT LEN(EmailField) - CHARINDEX('@', REVERSE(EmailField)) + 1

More information:

Better way to right align text in HTML Table

Looking through your exact question to your implied problem:

Step 1: Use the class as you described (or, if you must, use inline styles).

Step 2: Turn on GZIP compression.

Works wonders ;)

This way GZIP removes the redundancy for you (over the wire, anyways) and your source remains standards compliant.

Slide right to left?

or you can use


CKEditor instance already exists

CKeditor 4.2.1

There is a lot of answers here but for me I needed something more (bit dirty too so if anyone can improve please do). For me MODALs where my issue.

I was rendering the CKEditor in a modal, using Foundation. Ideally I would have destoryed the editor upon closing, however I didn't want to mess with Foundation.

I called delete, I tried remove and another method but this was what I finally settled with.

I was using textarea's to populate not DIVs.

My Solution

//hard code the DIV removal (due to duplication of CKeditors on page however they didn't work)


     if (CKEDITOR.instances['myckeditorname']) {
                delete CKEDITOR.instances['myckeditorname'];
                CKEDITOR.replace('myckeditorname', GetCKEditorSettings());
            } else {
                CKEDITOR.replace('myckeditorname', GetCKEditorSettings());

this was my method to return my specific formatting, which you might not want.

    function GetCKEditorSettings()
       return {
                    linkShowAdvancedTab: false,
                    linkShowTargetTab: false,
                    removePlugins: 'elementspath,magicline',
                    extraAllowedContent: 'hr blockquote div',
                    fontSize_sizes: 'small/8px;normal/12px;large/16px;larger/24px;huge/36px;',
                    toolbar: [
                        ['Bold', 'Italic', 'Underline', '-', 'NumberedList', 'BulletedList', '-', 'Link', 'Unlink'],

git replacing LF with CRLF

I think @Basiloungas's answer is close but out of date (at least on Mac).

Open the ~/.gitconfig file and set safecrlf to false

       autocrlf = input
       safecrlf = false

That *will make it ignore the end of line char apparently (worked for me, anyway).

Sorting Directory.GetFiles()

The MSDN Documentation states that there is no guarantee of any order on the return values. You have to use the Sort() method.

How to print a percentage value in python?

You are dividing integers then converting to float. Divide by floats instead.

As a bonus, use the awesome string formatting methods described here:

To specify a percent conversion and precision.

>>> float(1) / float(3)
[Out] 0.33333333333333331

>>> 1.0/3.0
[Out] 0.33333333333333331

>>> '{0:.0%}'.format(1.0/3.0) # use string formatting to specify precision
[Out] '33%'

>>> '{percent:.2%}'.format(percent=1.0/3.0)
[Out] '33.33%'

A great gem!

git status shows fatal: bad object HEAD

I solved this by doing git fetch. My error was because I moved my file from my main storage to my secondary storage on windows 10.

Extract digits from a string in Java

You can use str.replaceAll("[^0-9]", "");

TypeError: unhashable type: 'list' when using built-in set function

Sets require their items to be hashable. Out of types predefined by Python only the immutable ones, such as strings, numbers, and tuples, are hashable. Mutable types, such as lists and dicts, are not hashable because a change of their contents would change the hash and break the lookup code.

Since you're sorting the list anyway, just place the duplicate removal after the list is already sorted. This is easy to implement, doesn't increase algorithmic complexity of the operation, and doesn't require changing sublists to tuples:

def uniq(lst):
    last = object()
    for item in lst:
        if item == last:
        yield item
        last = item

def sort_and_deduplicate(l):
    return list(uniq(sorted(l, reverse=True)))

What is SaaS, PaaS and IaaS? With examples

Adding to that, I have used AWS, heroku and currently using Jelastic and found -

Jelastic offers a Java and PHP cloud hosting platform. Jelastic automatically scales Java and PHP applications and allocates server resources, thus delivering true next-generation Java and PHP cloud computing. or

Personally I found -

  • Jelastic is faster
  • You don’t need to code to any jelastic APIs – just upload your application and select your stack. You can also mix and match software stacks at will.

Try any of them and explore yourself. Its fun :-)

Links in <select> dropdown options

Add an onchange event handler and set the pages location to the value

<select id="foo">
    <option value="">Pick a site</option>
    <option value="">x</option>
    <option value="">y</option>

    document.getElementById("foo").onchange = function() {
        if (this.selectedIndex!==0) {
            window.location.href = this.value;

Simple Java Client/Server Program

Instead of using the IP address from, what if you just get the IP address directly from the machine and plug that in? will give you the address of your router (I'm assuming you're on a home network). I don't think port forwarding will work since your request will come from within the network, not outside.

How to completely uninstall kubernetes

The guide you linked now has a Tear Down section:

Talking to the master with the appropriate credentials, run:

kubectl drain <node name> --delete-local-data --force --ignore-daemonsets
kubectl delete node <node name>

Then, on the node being removed, reset all kubeadm installed state:

kubeadm reset

ASP.NET MVC How to pass JSON object from View to Controller as Parameter

in response to Dan's comment above:

I am using this method to implement the same thing, but for some reason I am getting an exception on the ReadObject method: "Expecting element 'root' from namespace ''.. Encountered 'None' with name '', namespace ''." Any ideas why? – Dan Appleyard Apr 6 '10 at 17:57

I had the same problem (MVC 3 build 3.0.11209.0), and the post below solved it for me. Basically the json serializer is trying to read a stream which is not at the beginning, so repositioning the stream to 0 'fixed' it...

How to set iPhone UIView z index?

Within the view you want to bring to the top... (in swift)


How to format a floating number to fixed width in Python

See Python 3.x format string syntax:

IDLE 3.5.1   
numbers = ['23.23', '.1233', '1', '4.223', '9887.2']

for x in numbers:  
    print('{0: >#016.4f}'. format(float(x)))  


How do I URl encode something in Node.js?

encodeURIComponent(string) will do it:

encodeURIComponent("Robert'); DROP TABLE Students;--")
//>> "Robert')%3B%20DROP%20TABLE%20Students%3B--"

Passing SQL around in a query string might not be a good plan though,

see this one

Using Thymeleaf when the value is null

This can also be handled using the elvis operator ?: which will add a default value when the field is null:

<span th:text="${} ?: 'default value'"></span>

std::wstring VS std::string

string? wstring?

std::string is a basic_string templated on a char, and std::wstring on a wchar_t.

char vs. wchar_t

char is supposed to hold a character, usually an 8-bit character.
wchar_t is supposed to hold a wide character, and then, things get tricky:
On Linux, a wchar_t is 4 bytes, while on Windows, it's 2 bytes.

What about Unicode, then?

The problem is that neither char nor wchar_t is directly tied to unicode.

On Linux?

Let's take a Linux OS: My Ubuntu system is already unicode aware. When I work with a char string, it is natively encoded in UTF-8 (i.e. Unicode string of chars). The following code:

#include <cstring>
#include <iostream>

int main(int argc, char* argv[])
   const char text[] = "olé" ;

   std::cout << "sizeof(char)    : " << sizeof(char) << std::endl ;
   std::cout << "text            : " << text << std::endl ;
   std::cout << "sizeof(text)    : " << sizeof(text) << std::endl ;
   std::cout << "strlen(text)    : " << strlen(text) << std::endl ;

   std::cout << "text(ordinals)  :" ;

   for(size_t i = 0, iMax = strlen(text); i < iMax; ++i)
      std::cout << " " << static_cast<unsigned int>(
                              static_cast<unsigned char>(text[i])

   std::cout << std::endl << std::endl ;

   // - - - 

   const wchar_t wtext[] = L"olé" ;

   std::cout << "sizeof(wchar_t) : " << sizeof(wchar_t) << std::endl ;
   //std::cout << "wtext           : " << wtext << std::endl ; <- error
   std::cout << "wtext           : UNABLE TO CONVERT NATIVELY." << std::endl ;
   std::wcout << L"wtext           : " << wtext << std::endl;

   std::cout << "sizeof(wtext)   : " << sizeof(wtext) << std::endl ;
   std::cout << "wcslen(wtext)   : " << wcslen(wtext) << std::endl ;

   std::cout << "wtext(ordinals) :" ;

   for(size_t i = 0, iMax = wcslen(wtext); i < iMax; ++i)
      std::cout << " " << static_cast<unsigned int>(
                              static_cast<unsigned short>(wtext[i])

   std::cout << std::endl << std::endl ;

   return 0;

outputs the following text:

sizeof(char)    : 1
text            : olé
sizeof(text)    : 5
strlen(text)    : 4
text(ordinals)  : 111 108 195 169

sizeof(wchar_t) : 4
wtext           : ol?
sizeof(wtext)   : 16
wcslen(wtext)   : 3
wtext(ordinals) : 111 108 233

You'll see the "olé" text in char is really constructed by four chars: 110, 108, 195 and 169 (not counting the trailing zero). (I'll let you study the wchar_t code as an exercise)

So, when working with a char on Linux, you should usually end up using Unicode without even knowing it. And as std::string works with char, so std::string is already unicode-ready.

Note that std::string, like the C string API, will consider the "olé" string to have 4 characters, not three. So you should be cautious when truncating/playing with unicode chars because some combination of chars is forbidden in UTF-8.

On Windows?

On Windows, this is a bit different. Win32 had to support a lot of application working with char and on different charsets/codepages produced in all the world, before the advent of Unicode.

So their solution was an interesting one: If an application works with char, then the char strings are encoded/printed/shown on GUI labels using the local charset/codepage on the machine. For example, "olé" would be "olé" in a French-localized Windows, but would be something different on an cyrillic-localized Windows ("ol?" if you use Windows-1251). Thus, "historical apps" will usually still work the same old way.

For Unicode based applications, Windows uses wchar_t, which is 2-bytes wide, and is encoded in UTF-16, which is Unicode encoded on 2-bytes characters (or at the very least, the mostly compatible UCS-2, which is almost the same thing IIRC).

Applications using char are said "multibyte" (because each glyph is composed of one or more chars), while applications using wchar_t are said "widechar" (because each glyph is composed of one or two wchar_t. See MultiByteToWideChar and WideCharToMultiByte Win32 conversion API for more info.

Thus, if you work on Windows, you badly want to use wchar_t (unless you use a framework hiding that, like GTK+ or QT...). The fact is that behind the scenes, Windows works with wchar_t strings, so even historical applications will have their char strings converted in wchar_t when using API like SetWindowText() (low level API function to set the label on a Win32 GUI).

Memory issues?

UTF-32 is 4 bytes per characters, so there is no much to add, if only that a UTF-8 text and UTF-16 text will always use less or the same amount of memory than an UTF-32 text (and usually less).

If there is a memory issue, then you should know than for most western languages, UTF-8 text will use less memory than the same UTF-16 one.

Still, for other languages (chinese, japanese, etc.), the memory used will be either the same, or slightly larger for UTF-8 than for UTF-16.

All in all, UTF-16 will mostly use 2 and occassionally 4 bytes per characters (unless you're dealing with some kind of esoteric language glyphs (Klingon? Elvish?), while UTF-8 will spend from 1 to 4 bytes.

See for more info.


  1. When I should use std::wstring over std::string?

    On Linux? Almost never (§).
    On Windows? Almost always (§).
    On cross-platform code? Depends on your toolkit...

    (§) : unless you use a toolkit/framework saying otherwise

  2. Can std::string hold all the ASCII character set including special characters?

    Notice: A std::string is suitable for holding a 'binary' buffer, where a std::wstring is not!

    On Linux? Yes.
    On Windows? Only special characters available for the current locale of the Windows user.

    Edit (After a comment from Johann Gerell):
    a std::string will be enough to handle all char-based strings (each char being a number from 0 to 255). But:

    1. ASCII is supposed to go from 0 to 127. Higher chars are NOT ASCII.
    2. a char from 0 to 127 will be held correctly
    3. a char from 128 to 255 will have a signification depending on your encoding (unicode, non-unicode, etc.), but it will be able to hold all Unicode glyphs as long as they are encoded in UTF-8.
  3. Is std::wstring supported by almost all popular C++ compilers?

    Mostly, with the exception of GCC based compilers that are ported to Windows.
    It works on my g++ 4.3.2 (under Linux), and I used Unicode API on Win32 since Visual C++ 6.

  4. What is exactly a wide character?

    On C/C++, it's a character type written wchar_t which is larger than the simple char character type. It is supposed to be used to put inside characters whose indices (like Unicode glyphs) are larger than 255 (or 127, depending...).

Append an object to a list in R in amortized constant time, O(1)?

There is also list.append from the rlist (link to the documentation)

LL <- list(a="Tom", b="Dick")

It's very simple and efficient.

Python vs Bash - In which kind of tasks each one outruns the other performance-wise?

Typical mainframe flow...

Input Disk/Tape/User (runtime) --> Job Control Language (JCL) --> Output Disk/Tape/Screen/Printer
                                   |                          ^
                                   v                          |
                                   `--> COBOL Program --------' 

Typical Linux flow...

Input Disk/SSD/User (runtime) --> sh/bash/ksh/zsh/... ----------> Output Disk/SSD/Screen/Printer
                                   |                          ^
                                   v                          |
                                   `--> Python script --------'
                                   |                          ^
                                   v                          |
                                   `--> awk script -----------'
                                   |                          ^
                                   v                          |
                                   `--> sed script -----------'
                                   |                          ^
                                   v                          |
                                   `--> C/C++ program --------'
                                   |                          ^
                                   v                          |
                                   `--- Java program ---------'
                                   |                          ^
                                   v                          |
                                   :                          :

Shells are the glue of Linux

Linux shells like sh/ksh/bash/... provide input/output/flow-control designation facilities much like the old mainframe Job Control Language... but on steroids! They are Turing complete languages in their own right while being optimized to efficiently pass data and control to and from other executing processes written in any language the O/S supports.

Most Linux applications, regardless what language the bulk of the program is written in, depend on shell scripts and Bash has become the most common. Clicking an icon on the desktop usually runs a short Bash script. That script, either directly or indirectly, knows where all the files needed are and sets variables and command line parameters, finally calling the program. That's a shell's simplest use.

Linux as we know it however would hardly be Linux without the thousands of shell scripts that startup the system, respond to events, control execution priorities and compile, configure and run programs. Many of these are quite large and complex.

Shells provide an infrastructure that lets us use pre-built components that are linked together at run time rather than compile time. Those components are free-standing programs in their own right that can be used alone or in other combinations without recompiling. The syntax for calling them is indistinguishable from that of a Bash builtin command, and there are in fact numerous builtin commands for which there is also a stand-alone executable on the system, often having additional options.

There is no language-wide difference between Python and Bash in performance. It entirely depends on how each is coded and which external tools are called.

Any of the well known tools like awk, sed, grep, bc, dc, tr, etc. will leave doing those operations in either language in the dust. Bash then is preferred for anything without a graphical user interface since it is easier and more efficient to call and pass data back from a tool like those with Bash than Python.


It depends on which programs the Bash shell script calls and their suitability for the subtask they are given whether the overall throughput and/or responsiveness will be better or worse than the equivalent Python. To complicate matters Python, like most languages, can also call other executables, though it is more cumbersome and thus not as often used.

User Interface

One area where Python is the clear winner is user interface. That makes it an excellent language for building local or client-server applications as it natively supports GTK graphics and is far more intuitive than Bash.

Bash only understands text. Other tools must be called for a GUI and data passed back from them. A Python script is one option. Faster but less flexible options are the binaries like YAD, Zenity, and GTKDialog.

While shells like Bash work well with GUIs like Yad, GtkDialog (embedded XML-like interface to GTK+ functions), dialog, and xmessage, Python is much more capable and so better for complex GUI windows.


Building with shell scripts is like assembling a computer with off-the-shelf components the way desktop PCs are.

Building with Python, C++ or most any other language is more like building a computer by soldering the chips (libraries) and other electronic parts together the way smartphones are.

The best results are usually obtained by using a combination of languages where each can do what they do best. One developer calls this "polyglot programming".

Set maxlength in Html Textarea

Before HTML5, we have an easy but workable way: Firstly set an maxlength attribute in the textarea element:

<textarea maxlength='250' name=''></textarea>  

Then use JavaScript to limit user input:

$(function() {  
    $("textarea[maxlength]").bind('input propertychange', function() {  
        var maxLength = $(this).attr('maxlength');  
        if ($(this).val().length > maxLength) {  
            $(this).val($(this).val().substring(0, maxLength));  

Make sure the bind both "input" and "propertychange" events to make it work on various browsers such as Firefox/Safari and IE.

Laravel 5 not finding css files

You can use one of the following options:

<link href="{{ asset('css/app.css') }}" rel="stylesheet" type="text/css" >

<link href="{{ URL::asset('css/app.css') }}" rel="stylesheet" type="text/css" >

{!! Html::style( asset('css/app.css')) !!} no protocol

Try instead of db.parse(xml):

Document doc = db.parse(new InputSource(new StringReader(**xml**)));

Getting RAW Soap Data from a Web Reference Client running in

I would prefer to have the framework do the logging for you by hooking in a logging stream which logs as the framework processes that underlying stream. The following isn't as clean as I would like it, since you can't decide between request and response in the ChainStream method. The following is how I handle it. With thanks to Jon Hanna for the overriding a stream idea

public class LoggerSoapExtension : SoapExtension
    private static readonly string LOG_DIRECTORY = ConfigurationManager.AppSettings["LOG_DIRECTORY"];
    private LogStream _logger;

    public override object GetInitializer(LogicalMethodInfo methodInfo, SoapExtensionAttribute attribute)
        return null;
    public override object GetInitializer(Type serviceType)
        return null;
    public override void Initialize(object initializer)
    public override System.IO.Stream ChainStream(System.IO.Stream stream)
        _logger = new LogStream(stream);
        return _logger;
    public override void ProcessMessage(SoapMessage message)
        if (LOG_DIRECTORY != null)
            switch (message.Stage)
                case SoapMessageStage.BeforeSerialize:
                    _logger.Type = "request";
                case SoapMessageStage.AfterSerialize:
                case SoapMessageStage.BeforeDeserialize:
                    _logger.Type = "response";
                case SoapMessageStage.AfterDeserialize:
    internal class LogStream : Stream
        private Stream _source;
        private Stream _log;
        private bool _logSetup;
        private string _type;

        public LogStream(Stream source)
            _source = source;
        internal string Type
            set { _type = value; }
        private Stream Logger
                if (!_logSetup)
                    if (LOG_DIRECTORY != null)
                            DateTime now = DateTime.Now;
                            string folder = LOG_DIRECTORY + now.ToString("yyyyMMdd");
                            string subfolder = folder + "\\" + now.ToString("HH");
                            string client = System.Web.HttpContext.Current != null && System.Web.HttpContext.Current.Request != null && System.Web.HttpContext.Current.Request.UserHostAddress != null ? System.Web.HttpContext.Current.Request.UserHostAddress : string.Empty;
                            string ticks = now.ToString("yyyyMMdd'T'HHmmss.fffffff");
                            if (!Directory.Exists(folder))
                            if (!Directory.Exists(subfolder))
                            _log = new FileStream(new System.Text.StringBuilder(subfolder).Append('\\').Append(client).Append('_').Append(ticks).Append('_').Append(_type).Append(".xml").ToString(), FileMode.Create);
                            _log = null;
                    _logSetup = true;
                return _log;
        public override bool CanRead
                return _source.CanRead;
        public override bool CanSeek
                return _source.CanSeek;

        public override bool CanWrite
                return _source.CanWrite;

        public override long Length
                return _source.Length;

        public override long Position
                return _source.Position;
                _source.Position = value;

        public override void Flush()
            if (Logger != null)

        public override long Seek(long offset, SeekOrigin origin)
            return _source.Seek(offset, origin);

        public override void SetLength(long value)

        public override int Read(byte[] buffer, int offset, int count)
            count = _source.Read(buffer, offset, count);
            if (Logger != null)
                Logger.Write(buffer, offset, count);
            return count;

        public override void Write(byte[] buffer, int offset, int count)
            _source.Write(buffer, offset, count);
            if (Logger != null)
                Logger.Write(buffer, offset, count);
        public override int ReadByte()
            int ret = _source.ReadByte();
            if (ret != -1 && Logger != null)
            return ret;
        public override void Close()
            if (Logger != null)
        public override int ReadTimeout
            get { return _source.ReadTimeout; }
            set { _source.ReadTimeout = value; }
        public override int WriteTimeout
            get { return _source.WriteTimeout; }
            set { _source.WriteTimeout = value; }
public class LoggerSoapExtensionAttribute : SoapExtensionAttribute
    private int priority = 1;
    public override int Priority
            return priority;
            priority = value;
    public override System.Type ExtensionType
            return typeof(LoggerSoapExtension);

Remove duplicates from a list of objects based on property in Java 8

If order does not matter and when it's more performant to run in parallel, Collect to a Map and then get values:, Function.identity(), (p, q) -> p)).values()

How to find the length of an array in shell?

From Bash manual:


The length in characters of the expanded value of parameter is substituted. If parameter is ‘’ or ‘@’, the value substituted is the number of positional parameters. If parameter is an array name subscripted by ‘’ or ‘@’, the value substituted is the number of elements in the array. If parameter is an indexed array name subscripted by a negative number, that number is interpreted as relative to one greater than the maximum index of parameter, so negative indices count back from the end of the array, and an index of -1 references the last element.

Length of strings, arrays, and associative arrays

string="0123456789"                   # create a string of 10 characters
array=(0 1 2 3 4 5 6 7 8 9)           # create an indexed array of 10 elements
declare -A hash
hash=([one]=1 [two]=2 [three]=3)      # create an associative array of 3 elements
echo "string length is: ${#string}"   # length of string
echo "array length is: ${#array[@]}"  # length of array using @ as the index
echo "array length is: ${#array[*]}"  # length of array using * as the index
echo "hash length is: ${#hash[@]}"    # length of array using @ as the index
echo "hash length is: ${#hash[*]}"    # length of array using * as the index


string length is: 10
array length is: 10
array length is: 10
hash length is: 3
hash length is: 3

Dealing with $@, the argument array:

set arg1 arg2 "arg 3"
echo "number of args is: $#"
echo "number of args is: ${#@}"
echo "args_copy length is: ${#args_copy[@]}"


number of args is: 3
number of args is: 3
args_copy length is: 3

How to simulate browsing from various locations?

The only thing that springs to mind for this is to use a proxy server based in Europe. Either have your colleague set one up [if possible] or find a free proxy. A quick Google search came up with as the top result.

hibernate could not get next sequence value

You need to set your @GeneratedId column with strategy GenerationType.IDENTITY instead of GenerationType.AUTO

@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "JUD_ID")
private Long _judId;

Detect Route Change with react-router

react-router v6

In the upcoming v6, this can be done by combining the useLocation and useEffect hooks

import { useLocation } from 'react-router-dom';

const MyComponent = () => {
  const location = useLocation()

  React.useEffect(() => {
    // runs on location, i.e. route, change
    console.log('handle route change here', location)
  }, [location])

For convenient reuse, you can do this in a custom useLocationChange hook

// runs action(location) on location, i.e. route, change
const useLocationChange = (action) => {
  const location = useLocation()
  React.useEffect(() => { action(location) }, [location])

const MyComponent1 = () => {
  useLocationChange((location) => { 
    console.log('handle route change here', location) 

const MyComponent2 = () => {
  useLocationChange((location) => { 
    console.log('and also here', location) 

If you also need to see the previous route on change, you can combine with a usePrevious hook

const usePrevious(value) {
  const ref = React.useRef()
  React.useEffect(() => { ref.current = value })

  return ref.current

const useLocationChange = (action) => {
  const location = useLocation()
  const prevLocation = usePrevious(location)
  React.useEffect(() => { 
    action(location, prevLocation) 
  }, [location])

const MyComponent1 = () => {
  useLocationChange((location, prevLocation) => { 
    console.log('changed from', prevLocation, 'to', location) 

It's important to note that all the above fire on the first client route being mounted, as well as subsequent changes. If that's a problem, use the latter example and check that a prevLocation exists before doing anything.

API Gateway CORS: no 'Access-Control-Allow-Origin' header

I got mine working after I realised that the lambda authoriser was failing and for some unknown reason that was being translated into a CORS error. A simple fix to my authoriser (and some authoriser tests that I should have added in the first place) and it worked. For me the API Gateway action 'Enable CORS' was required. This added all the headers and other settings I needed in my API.

Concatenating strings in Razor

You can give like this....

<a href="@(IsProduction.IsProductionUrl)Index/LogOut">

What is the regex for "Any positive integer, excluding 0"

You might want this (edit: allow number of the form 0123):


however, if it were me, I would instead do

int x = Integer.parseInt(s)
if (x > 0) {...}

MySQL, Check if a column exists in a table with SQL

I threw this stored procedure together with a start from @lain's comments above, kind of nice if you need to call it more than a few times (and not needing php):

delimiter //
-- ------------------------------------------------------------
-- Use the inforamtion_schema to tell if a field exists.
-- Optional param dbName, defaults to current database
-- ------------------------------------------------------------
OUT _exists BOOLEAN,      -- return value
IN tableName CHAR(255),   -- name of table to look for
IN columnName CHAR(255),  -- name of column to look for
IN dbName CHAR(255)       -- optional specific db
-- try to lookup db if none provided
SET @_dbName := IF(dbName IS NULL, database(), dbName);

IF CHAR_LENGTH(@_dbName) = 0
THEN -- no specific or current db to check against
ELSE -- we have a db to work with
  SELECT IF(count(*) > 0, TRUE, FALSE) INTO _exists
  FROM information_schema.COLUMNS c
  c.TABLE_SCHEMA    = @_dbName
  AND c.TABLE_NAME  = tableName
  AND c.COLUMN_NAME = columnName;
END //
delimiter ;

Working with fieldExists

mysql> call fieldExists(@_exists, 'jos_vm_product', 'child_option', NULL) //
Query OK, 0 rows affected (0.01 sec)

mysql> select @_exists //
| @_exists |
|        0 |
1 row in set (0.00 sec)

mysql> call fieldExists(@_exists, 'jos_vm_product', 'child_options', 'etrophies') //
Query OK, 0 rows affected (0.01 sec)

mysql> select @_exists //
| @_exists |
|        1 |

What is the purpose of the : (colon) GNU Bash builtin?

It's similar to pass in Python.

One use would be to stub out a function until it gets written:

future_function () { :; }

Java get String CompareTo as a comparator object

To generalize the good answer of Mike Nakis with String.CASE_INSENSITIVE_ORDER, you can also use :


See Collator

How to detect the OS from a Bash script?

I wrote a personal Bash library and scripting framework that uses GNU shtool to do a rather accurate platform detection.

GNU shtool is a very portable set of scripts that contains, among other useful things, the 'shtool platform' command. Here is the output of:

shtool platform -v -F "%sc (%ac) %st (%at) %sp (%ap)"

on a few different machines:

Mac OS X Leopard: 
    4.4BSD/Mach3.0 (iX86) Apple Darwin 9.6.0 (i386) Apple Mac OS X 10.5.6 (iX86)

Ubuntu Jaunty server:
    LSB (iX86) GNU/Linux 2.9/2.6 (i686) Ubuntu 9.04 (iX86)

Debian Lenny:
    LSB (iX86) GNU/Linux 2.7/2.6 (i686) Debian GNU/Linux 5.0 (iX86)

This produces pretty satisfactory results, as you can see. GNU shtool is a little slow, so I actually store and update the platform identification in a file on the system that my scripts call. It's my framework, so that works for me, but your mileage may vary.

Now, you'll have to find a way to package shtool with your scripts, but it's not a hard exercise. You can always fall back on uname output, also.


I missed the post by Teddy about config.guess (somehow). These are very similar scripts, but not the same. I personally use shtool for other uses as well, and it has been working quite well for me.

How to show grep result with complete path or file name

It is similar to BVB Media's answer.

grep -rnw 'blablabla' `pwd`

It works fine on my ubuntu bash.

How to change the display name for LabelFor in razor in mvc3?

You could decorate your view model property with the [DisplayName] attribute and specify the text to be used:

[DisplayName("foo bar")]
public string SomekingStatus { get; set; }

Or use another overload of the LabelFor helper which allows you to specify the text:

@Html.LabelFor(model => model.SomekingStatus, "foo bar")

And, no, you cannot specify a class name in MVC3 as you tried to do, as the LabelFor helper doesn't support that. However, this would work in MVC4 or 5.

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

On the side note, here is how the various plyr functions correspond to the base *apply functions (from the intro to plyr document from the plyr webpage

Base function   Input   Output   plyr function 
aggregate        d       d       ddply + colwise 
apply            a       a/l     aaply / alply 
by               d       l       dlply 
lapply           l       l       llply  
mapply           a       a/l     maply / mlply 
replicate        r       a/l     raply / rlply 
sapply           l       a       laply 

One of the goals of plyr is to provide consistent naming conventions for each of the functions, encoding the input and output data types in the function name. It also provides consistency in output, in that output from dlply() is easily passable to ldply() to produce useful output, etc.

Conceptually, learning plyr is no more difficult than understanding the base *apply functions.

plyr and reshape functions have replaced almost all of these functions in my every day use. But, also from the Intro to Plyr document:

Related functions tapply and sweep have no corresponding function in plyr, and remain useful. merge is useful for combining summaries with the original data.

How to create an ArrayList from an Array in PowerShell?

Probably the shortest version:


It is also faster because it does not call relatively expensive New-Object.

Display text from .txt file in batch file

Here's a version that doesn't fail if log.txt is missing:

@echo off
  if not exist log.txt goto firstlogin
  echo Date/Time last login:
  type log.txt
  goto end

  echo No last login found.

  echo %date%, %time%. > log.txt

What does the star operator mean, in a function call?

In a function call the single star turns a list into seperate arguments (e.g. zip(*x) is the same as zip(x1,x2,x3) if x=[x1,x2,x3]) and the double star turns a dictionary into seperate keyword arguments (e.g. f(**k) is the same as f(x=my_x, y=my_y) if k = {'x':my_x, 'y':my_y}.

In a function definition it's the other way around: the single star turns an arbitrary number of arguments into a list, and the double start turns an arbitrary number of keyword arguments into a dictionary. E.g. def foo(*x) means "foo takes an arbitrary number of arguments and they will be accessible through the list x (i.e. if the user calls foo(1,2,3), x will be [1,2,3])" and def bar(**k) means "bar takes an arbitrary number of keyword arguments and they will be accessible through the dictionary k (i.e. if the user calls bar(x=42, y=23), k will be {'x': 42, 'y': 23})".

Apache could not be started - ServerRoot must be a valid directory and Unable to find the specified module

Make sure your ServerRoot in httpd.conf points correctly to the Apache path. Otherwise you will see this message for every further module.


  • /etc/apache2/apache2 for Linux
  • "C:\Program Files\Apache24" for Windows

syntaxerror: "unexpected character after line continuation character in python" math

The backslash \ is the line continuation character the error message is talking about, and after it, only newline characters/whitespace are allowed (before the next non-whitespace continues the "interrupted" line.

print "This is a very long string that doesn't fit" + \
      "on a single line"

Outside of a string, a backslash can only appear in this way. For division, you want a slash: /.

If you want to write a verbatim backslash in a string, escape it by doubling it: "\\"

In your code, you're using it twice:

 print("Length between sides: " + str((length*length)*2.6) +
       " \ 1.5 = " +                   # inside a string; treated as literal
       str(((length*length)*2.6)\1.5)+ # outside a string, treated as line cont
                                       # character, but no newline follows -> Fail
       " Units")

What is the most effective way for float and double comparison?

The code you wrote is bugged :

return (diff < EPSILON) && (-diff > EPSILON);

The correct code would be :

return (diff < EPSILON) && (diff > -EPSILON);

(...and yes this is different)

I wonder if fabs wouldn't make you lose lazy evaluation in some case. I would say it depends on the compiler. You might want to try both. If they are equivalent in average, take the implementation with fabs.

If you have some info on which of the two float is more likely to be bigger than then other, you can play on the order of the comparison to take better advantage of the lazy evaluation.

Finally you might get better result by inlining this function. Not likely to improve much though...

Edit: OJ, thanks for correcting your code. I erased my comment accordingly

Validating email addresses using jQuery and regex

you can use this function

 var validateEmail = function (email) {

        var pattern = /^([a-z\d!#$%&'*+\-\/=?^_`{|}~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+(\.[a-z\d!#$%&'*+\-\/=?^_`{|}~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+)*|"((([ \t]*\r\n)?[ \t]+)?([\x01-\x08\x0b\x0c\x0e-\x1f\x7f\x21\x23-\x5b\x5d-\x7e\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]|\\[\x01-\x09\x0b\x0c\x0d-\x7f\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))*(([ \t]*\r\n)?[ \t]+)?")@(([a-z\d\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]|[a-z\d\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF][a-z\d\-._~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]*[a-z\d\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])\.)+([a-z\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]|[a-z\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF][a-z\d\-._~\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]*[a-z\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])\.?$/i;

        if (pattern.test(email)) {
            return true;
        else {
            return false;

What causes "Unable to access jarfile" error?

Just came across the same problem trying to make a bad USB...

I tried to run this command in admin cmd

java -jar c:\fw\ducky\duckencode.jar -I c:\fw\ducky\HelloWorld.txt  -o c:\fw\ducky\inject.bin

But got this error:

Error: unable to access jarfile c:\fw\ducky\duckencode.jar


1st step

Right click the jarfile in question. Click properties. Click the unblock tab in bottom right corner. The file was blocked, because it was downloaded and not created on my PC.

2nd step

In the cmd I changed the directory to where the jar file is located.

cd C:\fw\ducky\

Then I typed dir and saw the file was named duckencode.jar.jar

So in cmd I changed the original command to reference the file with .jar.jar

java -jar c:\fw\ducky\duckencode.jar.jar -I c:\fw\ducky\HelloWorld.txt  -o c:\fw\ducky\inject.bin

That command executed without error messages and the inject.bin I was trying to create was now located in the directory.

Hope this helps.

Linux: is there a read or recv from socket with timeout?

Install a handler for SIGALRM, then use alarm() or ualarm() before a regular blocking recv(). If the alarm goes off, the recv() will return an error with errno set to EINTR.

Ping all addresses in network, windows

Open the Command Prompt and type in the following:

FOR /L %i IN (1,1,254) DO ping -n 1 192.168.10.%i | FIND /i "Reply">>c:\ipaddresses.txt

Change 192.168.10 to match you own network.

By using -n 1 you are asking for only 1 packet to be sent to each computer instead of the usual 4 packets.

The above command will ping all IP Addresses on the network and create a text document in the C:\ drive called ipaddresses.txt. This text document should only contain IP Addresses that replied to the ping request.

Although it will take quite a bit longer to complete, you can also resolve the IP Addresses to HOST names by simply adding -a to the ping command.

FOR /L %i IN (1,1,254) DO ping -a -n 1 192.168.10.%i | FIND /i "Reply">>c:\ipaddresses.txt

This is from Here

Hope this helps

VB.NET Connection string (Web.Config, App.Config)

I don't know if this still is an issue, but i prefere just to use the My.Settings in my code.

Visual Studio generates a simple class with functions for reading settings from the app.config file.

You can simply access it using My.Settings.ConnectionString.

    Using Context As New Data.Context.DataClasses()
        Context.Connection.ConnectionString = My.Settings.ConnectionString
    End Using

How to embed images in email

Generally I handle this by setting up an HTML formatted SMTP message, with IMG tags pointing to a content server. Just make sure you have both text and HTML versions since some email clients cannot support HTML emails.

How can I check that two objects have the same set of property names?

If you want to check if both objects have the same properties name, you can do this:

function hasSameProps( obj1, obj2 ) {
  return Object.keys( obj1 ).every( function( prop ) {
    return obj2.hasOwnProperty( prop );

var obj1 = { prop1: 'hello', prop2: 'world', prop3: [1,2,3,4,5] },
    obj2 = { prop1: 'hello', prop2: 'world', prop3: [1,2,3,4,5] };

console.log(hasSameProps(obj1, obj2));

In this way you are sure to check only iterable and accessible properties of both the objects.

EDIT - 2013.04.26:

The previous function can be rewritten in the following way:

function hasSameProps( obj1, obj2 ) {
    var obj1Props = Object.keys( obj1 ),
        obj2Props = Object.keys( obj2 );

    if ( obj1Props.length == obj2Props.length ) {
        return obj1Props.every( function( prop ) {
          return obj2Props.indexOf( prop ) >= 0;

    return false;

In this way we check that both the objects have the same number of properties (otherwise the objects haven't the same properties, and we must return a logical false) then, if the number matches, we go to check if they have the same properties.


A possible enhancement could be to introduce also a type checking to enforce the match on every property.

How to check if an object is a certain type

In VB.NET, you need to use the GetType method to retrieve the type of an instance of an object, and the GetType() operator to retrieve the type of another known type.

Once you have the two types, you can simply compare them using the Is operator.

So your code should actually be written like this:

Sub FillCategories(ByVal Obj As Object)
    Dim cmd As New SqlCommand("sp_Resources_Categories", Conn)
    cmd.CommandType = CommandType.StoredProcedure
    Obj.DataSource = cmd.ExecuteReader
    If Obj.GetType() Is GetType(System.Web.UI.WebControls.DropDownList) Then

    End If
End Sub

You can also use the TypeOf operator instead of the GetType method. Note that this tests if your object is compatible with the given type, not that it is the same type. That would look like this:

If TypeOf Obj Is System.Web.UI.WebControls.DropDownList Then

End If

Totally trivial, irrelevant nitpick: Traditionally, the names of parameters are camelCased (which means they always start with a lower-case letter) when writing .NET code (either VB.NET or C#). This makes them easy to distinguish at a glance from classes, types, methods, etc.

Unable to set default python version to python3 in ubuntu

A simple safe way would be to use an alias. Place this into ~/.bashrc file: if you have gedit editor use

gedit ~/.bashrc

to go into the bashrc file and then at the top of the bashrc file make the following change.

alias python=python3

After adding the above in the file. run the below command

source ~/.bash_aliases or source ~/.bashrc


$ python --version

Python 2.7.6

$ python3 --version

Python 3.4.3

$ alias python=python3

$ python --version

Python 3.4.3

What are naming conventions for MongoDB?

Even if no convention is specified about this, manual references are consistently named after the referenced collection in the Mongo documentation, for one-to-one relations. The name always follows the structure <document>_id.

For example, in a dogs collection, a document would have manual references to external documents named like this:

  name: 'fido',
  owner_id: '5358e4249611f4a65e3068ab',
  race_id: '5358ee549611f4a65e3068ac',
  colour: 'yellow'

This follows the Mongo convention of naming _id the identifier for every document.

PHP error: Notice: Undefined index:

Assure you have used method="post" in the form you are sending data from.

Null vs. False vs. 0 in PHP

Somebody can explain to me why 'NULL' is not just a string in a comparison instance?

$x = 0;
var_dump($x == 'NULL');  # TRUE   !!!WTF!!!

jackson deserialization json to java-objects

It looks like you are trying to read an object from JSON that actually describes an array. Java objects are mapped to JSON objects with curly braces {} but your JSON actually starts with square brackets [] designating an array.

What you actually have is a List<product> To describe generic types, due to Java's type erasure, you must use a TypeReference. Your deserialization could read: myProduct = objectMapper.readValue(productJson, new TypeReference<List<product>>() {});

A couple of other notes: your classes should always be PascalCased. Your main method can just be public static void main(String[] args) throws Exception which saves you all the useless catch blocks.

Splitting applicationContext to multiple files

There are two types of contexts we are dealing with:

1: root context (parent context. Typically include all jdbc(ORM, Hibernate) initialisation and other spring security related configuration)

2: individual servlet context (child context.Typically Dispatcher Servlet Context and initialise all beans related to spring-mvc (controllers , URL Mapping etc)).

Here is an example of web.xml which includes multiple application context file

<?xml version="1.0" encoding="UTF-8"?>_x000D_
<web-app xmlns=""_x000D_
    <display-name>Spring Web Application example</display-name>_x000D_
    <!-- Configurations for the root application context (parent context) -->_x000D_
            /WEB-INF/spring/jdbc/spring-jdbc.xml <!-- JDBC related context -->_x000D_
            /WEB-INF/spring/security/spring-security-context.xml <!-- Spring Security related context -->_x000D_
    <!-- Configurations for the DispatcherServlet application context (child context) -->_x000D_

How do I install PIL/Pillow for Python 3.6?

You can download the wheel corresponding to your configuration here ("Pillow-4.1.1-cp36-cp36m-win_amd64.whl" in your case) and install it with:

pip install some-package.whl

If you have problem to install the wheel read this answer

Put search icon near textbox using bootstrap

<input type="text" name="whatever" id="funkystyling" />

Here's the CSS for the image on the left:

#funkystyling {
    background: white url(/path/to/icon.png) left no-repeat;
    padding-left: 17px;

And here's the CSS for the image on the right:

#funkystyling {
    background: white url(/path/to/icon.png) right no-repeat;
    padding-right: 17px;

how to use #ifdef with an OR condition?

Like this

#if defined(LINUX) || defined(ANDROID)

How do I get data from a table?

in this code data is a two dimensional array of table data

let oTable = document.getElementById('datatable-id');
let data = [...oTable.rows].map(t => [...t.children].map(u => u.innerText))

What's the most efficient way to check if a record exists in Oracle?

select NVL ((select 'Y' from  dual where exists
   (select  1 from sales where sales_type = 'Accessories')),'N') as rec_exists
from dual

1.Dual table will return 'Y' if record exists in sales_type table 2.Dual table will return null if no record exists in sales_type table and NVL will convert that to 'N'

How to display text in pygame?

Here is my answer:

    def draw_text(text, font_name, size, color, x, y, align="nw"):
        font = pg.font.Font(font_name, size)
        text_surface = font.render(text, True, color)
        text_rect = text_surface.get_rect()
        if align == "nw":
            text_rect.topleft = (x, y)
        if align == "ne":
            text_rect.topright = (x, y)
        if align == "sw":
            text_rect.bottomleft = (x, y)
        if align == "se":
            text_rect.bottomright = (x, y)
        if align == "n":
            text_rect.midtop = (x, y)
        if align == "s":
            text_rect.midbottom = (x, y)
        if align == "e":
            text_rect.midright = (x, y)
        if align == "w":
            text_rect.midleft = (x, y)
        if align == "center":
   = (x, y)
        screen.blit(text_surface, text_rect)

Of course, you'll need to import pygame, a font and a screen, but this is just a def to add on to the rest of the code, and then call "draw_text".

How to change column datatype in SQL database without losing data

ALTER TABLE tablename
ALTER COLUMN columnname columndatatype(size)

Note: if there is a size of columns, just write the size also.

Display number with leading zeros

This is how I do it:


Basically zfill takes the number of leading zeros you want to add, so it's easy to take the biggest number, turn it into a string and get the length, like this:

Python 3.6.5 (default, May 11 2018, 04:00:52) 
[GCC 8.1.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> total = 100
>>> print(str(1).zfill(len(str(total))))
>>> total = 1000
>>> print(str(1).zfill(len(str(total))))
>>> total = 10000
>>> print(str(1).zfill(len(str(total))))

How do I get the day of week given a date?

import numpy as np

def date(df):

df['weekday'] = df['date'].dt.day_name()

conditions = [(df['weekday'] == 'Sunday'),
          (df['weekday'] == 'Monday'),
          (df['weekday'] == 'Tuesday'),
          (df['weekday'] == 'Wednesday'),
          (df['weekday'] == 'Thursday'),
          (df['weekday'] == 'Friday'),
          (df['weekday'] == 'Saturday')]

choices = [0, 1, 2, 3, 4, 5, 6]

df['week'] =, choices)

return df

How to detect scroll direction

Here is a sample showing an easy way to do it. The script is:

$(function() {
  var _t = $("#container").scrollTop();
  $("#container").scroll(function() {
    var _n = $("#container").scrollTop();
    if (_n > _t) {
    } else {
    _t = _n;

The #container is your div id. The #target is just to see it working. Change to what you want when up or when down.


The OP didn't say before, but since he's using a div with overflow: hidden, scrolling doesn't occur, then the script to detect the scroll is the least of it. Well, how to detect something that does not happen?!

So, the OP himself posted the link with what he wants, so why not use that library?

The call is just:

$(function() {
    $(".scrollable").scrollable({ vertical: true, mousewheel: true });

How do I do logging in C# without using 3rd party libraries?

I used to write my own error logging until I discovered ELMAH. I've never been able to get the emailing part down quite as perfectly as ELMAH does.

Set Icon Image in Java

I use this:

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;

public class IconImageUtilities
    public static void setIconImage(Window window)
            InputStream imageInputStream = window.getClass().getResourceAsStream("/Icon.png");
            BufferedImage bufferedImage =;
        } catch (IOException exception)

Just place your image called Icon.png in the resources folder and call the above method with itself as parameter inside a class extending a class from the Window family such as JFrame or JDialog:


Finding moving average from data points in Python

There is a problem with the accepted answer. I think we need to use "valid" instead of "same" here - return numpy.convolve(interval, window, 'same') .

As an Example try out the MA of this data-set = [1,5,7,2,6,7,8,2,2,7,8,3,7,3,7,3,15,6] - the result should be [4.2,5.4,6.0,5.0,5.0,5.2,5.4,4.4,5.4,5.6,5.6,4.6,7.0,6.8], but having "same" gives us an incorrect output of [2.6,3.0,4.2,5.4,6.0,5.0,5.0,5.2,5.4,4.4,5.4,5.6,5.6, 4.6,7.0,6.8,6.2,4.8]

Rusty code to try this out -:

for index in xrange(len(dataset)):
    if index <=len(dataset)-window_size :
        tmp=(dataset[index]+ dataset[index+1]+ dataset[index+2]+ dataset[index+3]+ dataset[index+4])/5.0

result==movingaverage(y, window_size) 

Try this with valid & same and see whether the math makes sense.

See also -:

Multiple definition of ... linker error

Don't define variables in headers. Put declarations in header and definitions in one of the .c files.

In config.h

extern const char *names[];

In some .c file:

const char *names[] =
        "brian", "stefan", "steve"

If you put a definition of a global variable in a header file, then this definition will go to every .c file that includes this header, and you will get multiple definition error because a varible may be declared multiple times but can be defined only once.

Do HTTP POST methods send data as a QueryString?

GET will send the data as a querystring, but POST will not. Rather it will send it in the body of the request.

How to find and turn on USB debugging mode on Nexus 4


To see the option for USB debugging mode in Nexus 4 or Android 4.2 or higher OS, do the following:

  • Open up your device’s “Settings”. This can be done by pressing the Menu button while on your home screen and tapping “System settings”
  • Now scroll to the bottom and tap “About phone” or “About tablet”.
  • At the “About” screen, scroll to the bottom and tap on “Build number” seven times.
    • Make sure you tap seven times. If you see a “Not need, you are already a developer!” message pop up, then you know you have done it correctly.

Done! By tapping on “Build number” seven times, you have unlocked USB debugging mode on Android 4.2 and higher. You can now enable/disable it whenever you desire by going to “Settings” -> “Developer Options” -> “Debugging” ->” USB debugging”.


That was easy. The best part is you only have to do the tap-build-number-seven-times once. After you do it once, USB debugging has been unlocked and you can enable or disable at your leisure. Please restart after done these steps.

Additional information

Setting up a Device for Development native documentation of Google Android developer site

Update: Google Pixel 3

If you need to facilitate a connection between your device and a computer with the Android SDK (software development kit), view this info.

  1. From a Home screen, swipe up to display all apps.
  2. Navigate: Settings > System > Advanced.
  3. Developer options .
    If Developer options isn't available, navigate: SettingsAbout phone then tap Build number 7 times. Tap the Back icon  to Settings then select System > Advanced > Developer options.
  4. Ensure that the Developer options switch (upper-right) is turned on .
  5. Tap USB debugging to turn on or off .
  6. If prompted with 'Allow USB debugging?', tap OK to confirm.

Doc by Verizon: Original source

decompiling DEX into Java sourcecode

It's easy

Get these tools:

  1. dex2jar to translate dex files to jar files

  2. jd-gui to view the java files in the jar

The source code is quite readable as dex2jar makes some optimizations.


And here's the procedure on how to decompile:

Step 1:

Convert classes.dex in test_apk-debug.apk to test_apk-debug_dex2jar.jar -f -o output_jar.jar apk_to_decompile.apk -f -o output_jar.jar dex_to_decompile.dex

Note 1: In the Windows machines all the .sh scripts are replaced by .bat scripts

Note 2: On linux/mac don't forget about sh or bash. The full command should be:

sh -f -o output_jar.jar apk_to_decompile.apk 

Note 3: Also, remember to add execute permission to dex2jar-X.X directory e.g. sudo chmod -R +x dex2jar-2.0

dex2jar documentation

Step 2:

Open the jar in JD-GUI

The decompiled source

regex.test V.S. string.match to know if a string matches a regular expression

This is my benchmark results benchmark results

test 4,267,740 ops/sec ±1.32% (60 runs sampled)

exec 3,649,719 ops/sec ±2.51% (60 runs sampled)

match 3,623,125 ops/sec ±1.85% (62 runs sampled)

indexOf 6,230,325 ops/sec ±0.95% (62 runs sampled)

test method is faster than the match method, but the fastest method is the indexOf

How to turn a String into a JavaScript function call?

Based on Nicolas Gauthier answer:

var strng = 'someobj.someCallback';
var data = 'someData';

var func = window;
var funcSplit = strng.split('.');
for(i = 0;i < funcSplit.length;i++){
   //We maybe can check typeof and break the bucle if typeof != function
   func = func[funcSplit[i]];

Test if number is odd or even

Try this one with #Input field

    //checking even and odd
    echo '<form action="" method="post">';
    echo "<input type='text' name='num'>\n";
    echo "<button type='submit' name='submit'>Check</button>\n";
    echo "</form>";

    $num = 0;
    if ($_SERVER["REQUEST_METHOD"] == "POST") {
      if (empty($_POST["num"])) {
        $numErr = "<span style ='color: red;'>Number is required.</span>";
        echo $numErr;
      } else {
          $num = $_POST["num"];

    $even = ($num % 2 == 0);
    $odd = ($num % 2 != 0);
    if ($num > 0){
            echo "Number is even.";
        } else {
            echo "Number is odd.";
    } else {
        echo "Not a number.";

How to get number of video views with YouTube API?

Here an example that I used in my TubeCount app.

I also use the fields parameter to filter the JSON result, so only the fields that I need are returned.

var fields = "fields=openSearch:totalResults,entry(title,media:group(yt:videoid),media:group(yt:duration),media:group(media:description),media:group(media:thumbnail[@yt:name='default'](@url)),yt:statistics,yt:rating,published,gd:comments(gd:feedLink(@countHint)))";

var channel = "wiibart";

    url: ""+channel+"/uploads?"+fields+"&v=2&alt=json",
    success: function(data){

        var len = data.feed.entry.length;

        for(var k =0; k<len; k++){
            var yt = data.feed.entry[k];
            v.count = Number($statistics != undefined &&$statistics.viewCount != undefined ?$statistics.viewCount : 0);

Serialize JavaScript object into JSON string

Well, the type of an element is not standardly serialized, so you should add it manually. For example

var myobject = new MyClass1("5678999", "text");
var toJSONobject = { objectType: myobject.constructor, objectProperties: myobject };

Good luck!

edit: changed typeof to the correct .constructor. See for more information on the constructor property for Objects.

How to increase the timeout period of web service in

1 - You can set a timeout in your application :

var client = new YourServiceReference.YourServiceClass();
client.Timeout = 60; // or -1 for infinite

It is in milliseconds.

2 - Also you can increase timeout value in httpruntime tag in web/app.config :

          <httpRuntime executionTimeout="<<**seconds**>>" />

For ASP.NET applications, the Timeout property value should always be less than the executionTimeout attribute of the httpRuntime element in Machine.config. The default value of executionTimeout is 90 seconds. This property determines the time ASP.NET continues to process the request before it returns a timed out error. The value of executionTimeout should be the proxy Timeout, plus processing time for the page, plus buffer time for queues. -- Source

How to create a video from images with FFmpeg?

To create frames from video:

ffmpeg\ffmpeg -i %video% test\thumb%04d.jpg -hide_banner

Optional: remove frames you don't want in output video
(more accurate than trimming video with -ss & -t)

Then create video from image/frames eg.:

ffmpeg\ffmpeg -framerate 30 -start_number 56 -i test\thumb%04d.jpg -vf format=yuv420p test/output.mp4

displaying a string on the textview when clicking a button in android

Just check your code in .java class

You had written below line


before initializing the mybtn object I mean

mybtn = (Button)findViewById(;

just switch this two line or put that line "mybtn.setOnClickListener(this)" after initializing your mybtn object and you will get the answer what you want..

T-SQL Format integer to 2-digit string

Here is tiny function that left pad value with a given padding char You can specify how many characters to be padded to left..

   Create    function fsPadLeft(@var varchar(200),@padChar char(1)='0',@len int)
      returns varchar(300)
      return replicate(@PadChar,@len-Len(@var))+@var

To call :

declare @value int; set @value =2
select dbo.fsPadLeft(@value,'0',2)

How to do integer division in javascript (Getting division answer in int not float)?

var answer = Math.floor(x)

I sincerely hope this will help future searchers when googling for this common question.

Oracle - Insert New Row with Auto Incremental ID

For completeness, I'll mention that Oracle 12c does support this feature. Also it's supposedly faster than the triggers approach. For example:

    name       VARCHAR2 (50)

Default passwords of Oracle 11g?

It is possible to connect to the database without specifying a password. Once you've done that you can then reset the passwords. I'm assuming that you've installed the database on your machine; if not you'll first need to connect to the machine the database is running on.

  1. Ensure your user account is a member of the dba group. How you do this depends on what OS you are running.

  2. Enter sqlplus / as sysdba in a Command Prompt/shell/Terminal window as appropriate. This should log you in to the database as SYS.

  3. Once you're logged in, you can then enter

    alter user SYS identified by "newpassword";

    to reset the SYS password, and similarly for SYSTEM.

(Note: I haven't tried any of this on Oracle 12c; I'm assuming they haven't changed things since Oracle 11g.)

Rounded corners for <input type='text' /> using for IE

That won't work in IE<9 though, however, you can make IEs support that using:


PIE makes Internet Explorer 6-8 capable of rendering several of the most useful CSS3 decoration features.

Get value from input (AngularJS)

If your markup is bound to a controller, directive or anything else with a $scope:


Is there a way to return a list of all the image file names from a folder using only Javascript?

Although you can run FTP commands using WebSockets, the simpler solution is listing your files using opendir in server side (PHP), and "spitting" it into the HTML source-code, so it will be available to client side.

The following code will do just that,

Optionally -

  • use <a> tag to present a link.
  • query for more information using server side (PHP),

    for example a file size,

PHP filesize TIP:   also you can easily overcome the 2GB limit of PHP's filesize using: AJAX + HEAD request + .htaccess rule to allow Content-Length access from client-side.

  /* taken from: */

  $path = 'resources';
  $files = [];
  $handle = @opendir('./' . $path . '/');

  while ($file = @readdir($handle)) 
    ("." !== $file && ".." !== $file) && array_push($files, $file);
  sort($files); //uksort($files, "strnatcasecmp");

  $files = json_encode($files);

<!DOCTYPE html>
<html lang="en-US" dir="ltr">
  <meta http-equiv="X-UA-Compatible" content="IE=Edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <div data-container></div>
    /* you will see (for example): 'var files = ["1.bat","1.exe","1.txt"];' if your folder containes those 1.bat 1.exe 1.txt files, it will be sorted too! :) */

    var files = <?php echo $files; ?>;

    files ={
      return '<a data-ext="##EXT##" download="##FILE##" href="">##FILE##</a>'
        .replace(/##FILE##/g,       file)
        .replace(/##EXT##/g,        file.split('.').slice(-1) )

    document.querySelector('[data-container]').innerHTML = files;


DOM result will look like that:

<html lang="en-US" dir="ltr"><head>
  <meta http-equiv="X-UA-Compatible" content="IE=Edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <div data-container="">
    <a data-ext="bat" download="1.bat" href="">1.bat</a>
    <a data-ext="exe" download="1.exe" href="">1.exe</a>
    <a data-ext="txt" download="1.txt" href="">1.txt</a>
    var files = ["1.bat","1.exe","1.txt"];

    files ={
      return '<a data-ext="##EXT##" download="##FILE##" href="">##FILE##</a>'
        .replace(/##FILE##/g,       file)
        .replace(/##EXT##/g,        file.split('.').slice(-1) )

    document.querySelector('[data-container').innerHTML = files;


How to implode array with key and value without foreach in PHP

For create mysql where conditions from array

$sWheres = array('item1'  => 'object1',
                 'item2'  => 'object2',
                 'item3'  => 1,
                 'item4'  => array(4,5),
                 'item5'  => array('object3','object4'));
$sWhere = '';
    $sWhereConditions = array();
    foreach ($sWheres as $key => $value){
                $value = array_filter($value); // For remove blank values from array
                    array_walk($value, function(&$item){ $item = sprintf("'%s'", $item); }); // For make value string type 'string'
                    $sWhereConditions[] = sprintf("%s in (%s)", $key, implode(', ', $value));
                $sWhereConditions[] = sprintf("%s='%s'", $key, $value);
        $sWhere .= "(".implode(' AND ', $sWhereConditions).")";
echo $sWhere;  // (item1='object1' AND item2='object2' AND item3='1' AND item4 in ('4', '5') AND item5 in ('object3', 'object4'))

Limit Decimal Places in Android EditText

All answers here are pretty complex I tried to make it much simpler.Look at my code and decide for yourself -

int temp  = 0;
int check = 0;

editText.addTextChangedListener(new TextWatcher() {

    public void onTextChanged(CharSequence s, int start, int before, int count) {

                editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()-1) });
                editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()+1) });


            editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()+1) });

        else if(check==0)
            editText.setFilters(new InputFilter[] { new InputFilter.LengthFilter(editText.getText().toString().length()+2) });

    public void beforeTextChanged(CharSequence s, int start, int count,
            int after) {
        temp = editText.getText().toString().length();


    public void afterTextChanged(Editable s) {
        // TODO Auto-generated method stub


@HostBinding and @HostListener: what do they do and what are they for?

Theory with less Jargons

@Hostlistnening deals basically with the host element say (a button) listening to an action by a user and performing a certain function say alert("Ahoy!") while @Hostbinding is the other way round. Here we listen to the changes that occurred on that button internally (Say when it was clicked what happened to the class) and we use that change to do something else, say emit a particular color.


Think of the scenario that you would like to make a favorite icon on a component, now you know that you would have to know whether the item has been Favorited with its class changed, we need a way to determine this. That is exactly where @Hostbinding comes in.

And where there is the need to know what action actually was performed by the user that is where @Hostlistening comes in

Adjust width and height of iframe to fit with content in it

Simplicity :

var iframe = $("#myframe");
$(iframe.get(0).contentWindow).on("resize", function(){

Disable submit button on form submit

Specifically if someone is facing problem in Chrome:

What you need to do to fix this is to use the onSubmit tag in the <form> element to set the submit button disabled. This will allow Chrome to disable the button immediately after it is pressed and the form submission will still go ahead...

<form name ="myform" method="POST" action="dosomething.php" onSubmit="document.getElementById('submit').disabled=true;"> 
     <input type="submit" name="submit" value="Submit" id="submit"> 

Text on image mouseover?

For people coming from the future, you can now do this purely in CSS.

.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted black; 
  margin: 5rem;

/* Tooltip text */
.tooltip .tooltiptext {
  visibility: hidden;
  background-color: black;
  color: #fff;
  text-align: center;
  padding: 5px 0;
  border-radius: 6px;

  width: 120px;
  bottom: 100%;
  left: 50%;
  margin-left: -60px;

  position: absolute;
  z-index: 1;

/* Show the tooltip text when you mouse over the tooltip container */
.tooltip:hover .tooltiptext {
  visibility: visible;
<div class="tooltip">Hover over me
  <span class="tooltiptext">Tooltip text</span>

How to check if a string in Python is in ASCII?

I think you are not asking the right question--

A string in python has no property corresponding to 'ascii', utf-8, or any other encoding. The source of your string (whether you read it from a file, input from a keyboard, etc.) may have encoded a unicode string in ascii to produce your string, but that's where you need to go for an answer.

Perhaps the question you can ask is: "Is this string the result of encoding a unicode string in ascii?" -- This you can answer by trying:

except UnicodeDecodeError:
    print "it was not a ascii-encoded unicode string"
    print "It may have been an ascii-encoded unicode string"

What are -moz- and -webkit-?

These are the vendor-prefixed properties offered by the relevant rendering engines (-webkit for Chrome, Safari; -moz for Firefox, -o for Opera, -ms for Internet Explorer). Typically they're used to implement new, or proprietary CSS features, prior to final clarification/definition by the W3.

This allows properties to be set specific to each individual browser/rendering engine in order for inconsistencies between implementations to be safely accounted for. The prefixes will, over time, be removed (at least in theory) as the unprefixed, the final version, of the property is implemented in that browser.

To that end it's usually considered good practice to specify the vendor-prefixed version first and then the non-prefixed version, in order that the non-prefixed property will override the vendor-prefixed property-settings once it's implemented; for example:

.elementClass {
    -moz-border-radius: 2em;
    -ms-border-radius: 2em;
    -o-border-radius: 2em;
    -webkit-border-radius: 2em;
    border-radius: 2em;

Specifically, to address the CSS in your question, the lines you quote:

-webkit-column-count: 3;
-webkit-column-gap: 10px;
-webkit-column-fill: auto;
-moz-column-count: 3;
-moz-column-gap: 10px;
-moz-column-fill: auto;

Specify the column-count, column-gap and column-fill properties for Webkit browsers and Firefox.


How to verify static void method has been called with power mockito

If you are mocking the behavior (with something like doNothing()) there should really be no need to call to verify*(). That said, here's my stab at re-writing your test method:

public class InternalServiceTest { //Note the renaming of the test class.
   public void testProcessOrder() {
        InternalService is = new InternalService();
        Order order = mock(Order.class);

        //Mock Behavior
        doNothing().when(InternalUtils.class); //This is the preferred way
                                               //to mock static void methods.
        InternalUtils.sendEmail(anyString(), anyString(), anyString(), anyString());


        verifyStatic(InternalUtils.class); //Similar to how you mock static methods
                                           //this is how you verify them.
        InternalUtils.sendEmail(anyString(), anyString(), anyString(), anyString());

I grouped into four sections to better highlight what is going on:

1. Variables

I choose to declare any instance variables / method arguments / mock collaborators here. If it is something used in multiple tests, consider making it an instance variable of the test class.

2. Mock Behavior

This is where you define the behavior of all of your mocks. You're setting up return values and expectations here, prior to executing the code under test. Generally speaking, if you set the mock behavior here you wouldn't need to verify the behavior later.

3. Execute

Nothing fancy here; this just kicks off the code being tested. I like to give it its own section to call attention to it.

4. Verify

This is when you call any method starting with verify or assert. After the test is over, you check that the things you wanted to have happen actually did happen. That is the biggest mistake I see with your test method; you attempted to verify the method call before it was ever given a chance to run. Second to that is you never specified which static method you wanted to verify.

Additional Notes

This is mostly personal preference on my part. There is a certain order you need to do things in but within each grouping there is a little wiggle room. This helps me quickly separate out what is happening where.

I also highly recommend going through the examples at the following sites as they are very robust and can help with the majority of the cases you'll need:

How do I convert an object to an array?

//My Function is worked. Hope help full for you :)
      $input = [
            '1' => (object) [1,2,3],
            '2' => (object) [4,5,6,
                (object) [6,7,8,
                [9, 10, 11,
                    (object) [12, 13, 14]]]
            '3' =>[15, 16, (object)[17, 18]]

        echo "<pre>";

      public function toAnArray(&$input) {

        if (is_object($input)) {
            $input = get_object_vars($input);
        foreach ($input as &$item) {
            if (is_object($item) || is_array($item)) {
                if (is_object($item)) {
                    $item = get_object_vars($item);

make an html svg object also a clickable link

Just don't use <object>. Here's a solution that worked for me with <a> and <svg> tags:

<a href="<your-link>" class="mr-5 p-1 border-2 border-transparent text-gray-400 rounded-full hover:text-white focus:outline-none focus:text-white focus:bg-red-700 transition duration-150 ease-in-out" aria-label="Notifications">
    <svg xmlns="" viewBox="0 0 24 24" width="30" 
    height="30"><path class="heroicon-ui" fill="#fff" d="M17 16a3 3 0 1 1-2.83 
    2H9.83a3 3 0 1 1-5.62-.1A3 3 0 0 1 5 12V4H3a1 1 0 1 1 0-2h3a1 1 0 0 1 1 
    1v1h14a1 1 0 0 1 .9 1.45l-4 8a1 1 0 0 1-.9.55H5a1 1 0 0 0 0 2h12zM7 12h9.38l3- 
   6H7v6zm0 8a1 1 0 1 0 0-2 1 1 0 0 0 0 2zm10 0a1 1 0 1 0 0-2 1 1 0 0 0 0 2z"/>

When is JavaScript synchronous?

To someone who really understands how JS works this question might seem off, however most people who use JS do not have such a deep level of insight (and don't necessarily need it) and to them this is a fairly confusing point, I will try to answer from that perspective.

JS is synchronous in the way its code is executed. each line only runs after the line before it has completed and if that line calls a function after that is complete etc...

The main point of confusion arises from the fact that your browser is able to tell JS to execute more code at anytime (similar to how you can execute more JS code on a page from the console). As an example JS has Callback functions who's purpose is to allow JS to BEHAVE asynchronously so further parts of JS can run while waiting for a JS function that has been executed (I.E. a GET call) to return back an answer, JS will continue to run until the browser has an answer at that point the event loop (browser) will execute the JS code that calls the callback function.

Since the event loop (browser) can input more JS to be executed at any point in that sense JS is asynchronous (the primary things that will cause a browser to input JS code are timeouts, callbacks and events)

I hope this is clear enough to be helpful to somebody.

Update Rows in SSIS OLEDB Destination

You can't do a bulk-update in SSIS within a dataflow task with the OOB components.

The general pattern is to identify your inserts, updates and deletes and push the updates and deletes to a staging table(s) and after the Dataflow Task, use a set-based update or delete in an Execute SQL Task. Look at Andy Leonard's Stairway to Integration Services series. Scroll about 3/4 the way down the article to "Set-Based Updates" to see the pattern.

Stage data

Set based updates

enter image description here

You'll get much better performance with a pattern like this versus using the OLE DB Command transformation for anything but trivial amounts of data.

If you are into third party tools, I believe CozyRoc and I know PragmaticWorks have a merge destination component.

Undefined reference to static class member

You need to actually define the static member somewhere (after the class definition). Try this:

class Foo { /* ... */ };

const int Foo::MEMBER;

int main() { /* ... */ }

That should get rid of the undefined reference.

Running multiple commands with xargs

cat a.txt | xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$arg"; ...; done' _

...or, without a Useless Use Of cat:

<a.txt xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$arg"; ...; done' _

To explain some of the finer points:

  • The use of "$arg" instead of % (and the absence of -I in the xargs command line) is for security reasons: Passing data on sh's command-line argument list instead of substituting it into code prevents content that data might contain (such as $(rm -rf ~), to take a particularly malicious example) from being executed as code.

  • Similarly, the use of -d $'\n' is a GNU extension which causes xargs to treat each line of the input file as a separate data item. Either this or -0 (which expects NULs instead of newlines) is necessary to prevent xargs from trying to apply shell-like (but not quite shell-compatible) parsing to the stream it reads. (If you don't have GNU xargs, you can use tr '\n' '\0' <a.txt | xargs -0 ... to get line-oriented reading without -d).

  • The _ is a placeholder for $0, such that other data values added by xargs become $1 and onward, which happens to be the default set of values a for loop iterates over.

How to get request URL in Spring Boot RestController

You may try adding an additional argument of type HttpServletRequest to the getUrlValue() method:

@RequestMapping(value ="/",produces = "application/json")
public String getURLValue(HttpServletRequest request){
    String test = request.getRequestURI();
    return test;

When do we need curly braces around shell variables?

You are also able to do some text manipulation inside the braces:

echo ${STRING} ${STRING%/*/*}


./folder/subfolder/file.txt ./folder


STRING="This is a string"
echo ${STRING// /_}



You are right in "regular variables" are not needed... But it is more helpful for the debugging and to read a script.

How to get the real and total length of char * (char array)?

Given just the pointer, you can't. You'll have to keep hold of the length you passed to new[] or, better, use std::vector to both keep track of the length, and release the memory when you've finished with it.

Note: this answer only addresses C++, not C.

AngularJS custom filter function

You can use it like this:

Like you found, filter accepts predicate function which accepts item by item from the array. So, you just have to create an predicate function based on the given criteria.

In this example, criteriaMatch is a function which returns a predicate function which matches the given criteria.


<div ng-repeat="item in items | filter:criteriaMatch(criteria)">
  {{ item }}


$scope.criteriaMatch = function( criteria ) {
  return function( item ) {
    return ===;

What is the difference/usage of homebrew, macports or other package installation tools?

Homebrew and macports both solve the same problem - that is the installation of common libraries and utilities that are not bundled with osx.

Typically these are development related libraries and the most common use of these tools is for developers working on osx.

They both need the xcode command line tools installed (which you can download separately from, and for some specific packages you will need the entire xcode IDE installed.

xcode can be installed from the mac app store, its a free download but it takes a while since its around 5GB (if I remember correctly).

macports is an osx version of the port utility from BSD (as osx is derived from BSD, this was a natural choice). For anyone familiar with any of the BSD distributions, macports will feel right at home.

One major difference between homebrew and macports; and the reason I prefer homebrew is that it will not overwrite things that should be installed "natively" in osx. This means that if there is a native package available, homebrew will notify you instead of overwriting it and causing problems further down the line. It also installs libraries in the user space (thus, you don't need to use "sudo" to install things). This helps when getting rid of libraries as well since everything is in a path accessible to you.

homebrew also enjoys a more active user community and its packages (called formulas) are updated quite often.

macports does not overwrite native OSX packages - it supplies its own version - This is the main reason I prefer macports over home-brew, you need to be certain of what you are using and Apple's change at different times to the ports and have been know to be years behind updates in some projects

Can you give a reference showing that macports overwrites native OS X packages? As far as I can tell, all macports installation happens in /opt/local

Perhaps I should clarify - I did not say anywhere in my answer that macports overwrites OSX native packages. They both install items separately.

Homebrew will warn you when you should install things "natively" (using the library/tool's preferred installer) for better compatibility. This is what I meant. It will also use as many of the local libraries that are available in OS X. From the wiki:

We really don’t like dupes in Homebrew/homebrew

However, we do like dupes in the tap!

Stuff that comes with OS X or is a library that is provided by RubyGems, CPAN or PyPi should not be duped. There are good reasons for this:

  • Duplicate libraries regularly break builds
  • Subtle bugs emerge with duplicate libraries, and to a lesser extent, duplicate tools
  • We want you to try harder to make your formula work with what OS X comes with

You can optionally overwrite the macosx supplied versions of utilities with homebrew.

How to export collection to CSV in MongoDB?

If you want, you can export all collections to csv without specifying --fields (will export all fields).

From run this bash script


# fill in your details here

# first get all collections in the database
collections=`mongo "$host/$dbname" -u $user -p $pass --eval "rs.slaveOk();db.getCollectionNames();"`;
collections=`mongo $dbname --eval "rs.slaveOk();db.getCollectionNames();"`;

# for each collection
for ((i=0; i<${#collectionArray[@]}; ++i));
    echo 'exporting collection' ${collectionArray[$i]}
    # get comma separated list of keys. do this by peeking into the first document in the collection and get his set of keys
    keys=`mongo "$host/$dbname" -u $user -p $pass --eval "rs.slaveOk();var keys = []; for(var key in db.${collectionArray[$i]}.find().sort({_id: -1}).limit(1)[0]) { keys.push(key); }; keys;" --quiet`;
    # now use mongoexport with the set of keys to export the collection to csv
    mongoexport --host $host -u $user -p $pass -d $dbname -c ${collectionArray[$i]} --fields "$keys" --csv --out $dbname.${collectionArray[$i]}.csv;


How to access a value defined in the file in Spring Boot

For me, none of the above did directly work for me. What I did is the following:

Additionally to @Rodrigo Villalba Zayas answer up there I added
implements InitializingBean to the class
and implemented the method

public void afterPropertiesSet() {
    String path = env.getProperty("userBucket.path");

So that will look like

import org.springframework.core.env.Environment;
public class xyz implements InitializingBean {

    private Environment env;
    private String path;


    public void afterPropertiesSet() {
        path = env.getProperty("userBucket.path");

    public void method() {
        System.out.println("Path: " + path);

See full command of running/stopped container in Docker

docker ps --no-trunc will display the full command along with the other details of the running containers.

Reset select value to default

$('#my_select').get(0).selectedIndex = 1;

But, In my opinion, the better way is using HTML only (with <input type="reset" />):

    <select id="my_select">
        <option value="a">a</option>
        <option value="b" selected="selected">b</option>
        <option value="c">c</option>
    <input type="reset" value="reset" />

Opacity CSS not working in IE8

You need to set Opacity first for standards-compliant browsers, then the various versions of IE. See Example:

but this opacity code not work in ie8

    cursor: pointer;
    opacity: .75; /* Standards Compliant Browsers */
    filter: alpha(opacity=75); /* IE 7 and Earlier */
    /* Next 2 lines IE8 */
    -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=75)";
    filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=75);

Note that I eliminated -moz as Firefox is a Standards Compliant browser and that line is no longer necessary. Also, -khtml is depreciated, so I eliminated that style as well.

Furthermore, IE's filters will not validate to w3c standards, so if you want your page to validate, separate your standards stylesheet from your IE stylesheet by using an if IE statement like below:

<!--[if IE]>
<link rel="stylesheet" type="text/css"  href="" />

If you separate the ie quirks, your site will validate just fine.

android EditText - finished typing event

Simple to trigger finish typing in EditText

worked for me , if you using java convert it

In Kotlin

youredittext.doAfterTextChanged { searchTerm ->
val currentTextLength = searchTerm?.length
        if (currentTextLength == searchTerm?.length) {
            // your code 
           Log.d("aftertextchange", "ON FINISH TRIGGER")
       }, 3000)

Failed to build gem native extension — Rails install

mkmf is part of the ruby1.9.1-dev package. This package contains the header files needed for extension libraries for Ruby 1.9.1. You need to install the ruby1.9.1-dev package by doing:

sudo apt-get install ruby1.9.1-dev

Then you can install Rails as per normal.

Generally it's easier to just do:

sudo apt-get install ruby-dev

The given key was not present in the dictionary. Which key?

string Value = dic.ContainsKey("Name") ? dic["Name"] : "Required Name"

With this code, we will get string data in 'Value'. If key 'Name' exists in the dictionary 'dic' then fetch this value, else returns "Required Name" string.

Parameter in like clause JPQL

Use JpaRepository or CrudRepository as repository interface:

public interface CustomerRepository extends JpaRepository<Customer, Integer> {

    @Query("SELECT t from Customer t where LOWER( LIKE %:name%")
    public List<Customer> findByName(@Param("name") String name);


public class CustomerServiceImpl implements CustomerService {

    private CustomerRepository customerRepository;

    public List<Customer> pattern(String text) throws Exception {
        return customerRepository.findByName(text.toLowerCase());

How to add external JS scripts to VueJS Components

You can use the vue-head package to add scripts, and other tags to the head of your vue component.

Its as simple as:

var myComponent = Vue.extend({
  data: function () {
    return {
  head: {
    title: {
      inner: 'It will be a pleasure'
    // Meta tags
    meta: [
      { name: 'application-name', content: 'Name of my application' },
      { name: 'description', content: 'A description of the page', id: 'desc' }, // id to replace intead of create element
      // ...
      // Twitter
      { name: 'twitter:title', content: 'Content Title' },
      // with shorthand
      { n: 'twitter:description', c: 'Content description less than 200 characters'},
      // ...
      // Google+ /
      { itemprop: 'name', content: 'Content Title' },
      { itemprop: 'description', content: 'Content Title' },
      // ...
      // Facebook / Open Graph
      { property: 'fb:app_id', content: '123456789' },
      { property: 'og:title', content: 'Content Title' },
      // with shorthand
      { p: 'og:image', c: '' },
      // ...
    // link tags
    link: [
      { rel: 'canonical', href: '!/contact/', id: 'canonical' },
      { rel: 'author', href: 'author', undo: false }, // undo property - not to remove the element
      { rel: 'icon', href: require('./path/to/icon-16.png'), sizes: '16x16', type: 'image/png' }, 
      // with shorthand
      { r: 'icon', h: 'path/to/icon-32.png', sz: '32x32', t: 'image/png' },
      // ...
    script: [
      { type: 'text/javascript', src: 'cdn/to/script.js', async: true, body: true}, // Insert in body
      // with shorthand
      { t: 'application/ld+json', i: '{ "@context": "" }' },
      // ...
    style: [
      { type: 'text/css', inner: 'body { background-color: #000; color: #fff}', undo: false },
      // ...

Check out this link for more examples.

merge one local branch into another local branch

  1. git checkout [branchYouWantToReceiveBranch] - checkout branch you want to receive branch
  2. git merge [branchYouWantToMergeIntoBranch]

Call An Asynchronous Javascript Function Synchronously

You can force asynchronous JavaScript in NodeJS to be synchronous with sync-rpc.

It will definitely freeze your UI though, so I'm still a naysayer when it comes to whether what it's possible to take the shortcut you need to take. It's not possible to suspend the One And Only Thread in JavaScript, even if NodeJS lets you block it sometimes. No callbacks, events, anything asynchronous at all will be able to process until your promise resolves. So unless you the reader have an unavoidable situation like the OP (or, in my case, are writing a glorified shell script with no callbacks, events, etc.), DO NOT DO THIS!

But here's how you can do this:


var createClient = require('sync-rpc');
var mySynchronousCall = createClient(require.resolve('./my-asynchronous-call'), 'init data');

var param1 = 'test data'
var data = mySynchronousCall(param1);
console.log(data); // prints: received "test data" after "init data"


function init(initData) {
  return function(param1) {
    // Return a promise here and the resulting rpc client will be synchronous
    return Promise.resolve('received "' + param1 + '" after "' + initData + '"');
module.exports = init;


These are both a consequence of how sync-rpc is implemented, which is by abusing require('child_process').spawnSync:

  1. This will not work in the browser.
  2. The arguments to your function must be serializable. Your arguments will pass in and out of JSON.stringify, so functions and non-enumerable properties like prototype chains will be lost.

Getting a timestamp for today at midnight?

Today at midnight. Easy.

$stamp = mktime(0, 0, 0);

How to use the new Material Design Icon themes: Outlined, Rounded, Two-Tone and Sharp?

Setting up the Two-tone color:

As described above you can use the color css key except for materials Two-tone theme which seems to be glitchy ;-)

A workaround is described in one of several angular material github issue's by using a custom css filter. This custom filter can be generated here.



<link rel="stylesheet" href="|Material+Icons+Outlined|Material+Icons+Round|Material+Icons+Two+Tone|Material+Icons+Sharp">

<i class="material-icons-two-tone red">home</i>


.red {
filter: invert(8%) sepia(94%) saturate(4590%) hue-rotate(358deg) brightness(101%) contrast(112%);


How to make picturebox transparent?

Try using an ImageList

ImageList imgList = new ImageList;

imgList.TransparentColor = Color.White;

Load the image like this:

picturebox.Image = imgList.Images[img_index];

Android Webview gives net::ERR_CACHE_MISS message


if (Build.VERSION.SDK_INT >= 19) {

It should solve the error.

How do I ignore an error on 'git pull' about my local changes would be overwritten by merge?

This worked for me to discard changes on the live remote server and pull from the source control GitHub:

git reset --hard
git pull origin master

How to check if an element is in an array


let elements = [1, 2, 3, 4, 5, 5]

Check elements presence

elements.contains(5) // true

Get elements index

elements.firstIndex(of: 5) // 4
elements.firstIndex(of: 10) // nil

Get element count

let results = elements.filter { element in element == 5 }
results.count // 2

How can I disable selected attribute from select2() dropdown Jquery?

To disable the complete select2 box, that is no deletion of already selected values and no new insertion, use:

$("id-select2").prop("disabled", true);

where id-select2 is the unique id of select2. you can also use any particular class if defined to address the dropdown.

How can I parse a String to BigDecimal?

BigDecimal offers a string constructor. You'll need to strip all commas from the number, via via an regex or String filteredString=inString.replaceAll(",","").

You then simply call BigDecimal myBigD=new BigDecimal(filteredString);

You can also create a NumberFormat and call setParseBigDecimal(true). Then parse( will give you a BigDecimal without worrying about manually formatting.

Fill remaining vertical space - only CSS

you need javascript and some client side calculations:

you will need jquery to effectively achieve what you want. this function is very simple but very effective:

(function () {

    var heights = $("#wrapper").outerHeight(true);
    var outerHeights = $("#first").outerHeight(true);
    jQuery('#second').css('height', (heights - outerHeights) + "px");


first it detects the wrapper height, as it is set to 100% it's different everytime (it depends on what screen you are landing). in the second step it gives the #second div the appropriate height subtracting from the wrapper height the #first div height. the result is the available height left in the wrapper div

Make anchor link go some pixels above where it's linked to

i was facing the similar issue and i resolved by using following code

$(document).on('click', '', function(event) {
        var $anchor = $(this);
        var desiredHeight = $(window).height() - 577;
        $('html, body').stop().animate({
            scrollTop: $($anchor.attr('href')).offset().top - desiredHeight
        }, 1500, 'easeInOutExpo');

Disable/turn off inherited CSS3 transitions

Additionally there is a possibility to set a list of properties that will get transitioned by setting the property transition-property: width, height;, more details here

How can I generate an HTML report for Junit results?

Alternatively for those using Maven build tool, there is a plugin called Surefire Report.

The report looks like this : Sample

CSV file written with Python has blank lines between each row

The simple answer is that csv files should always be opened in binary mode whether for input or output, as otherwise on Windows there are problems with the line ending. Specifically on output the csv module will write \r\n (the standard CSV row terminator) and then (in text mode) the runtime will replace the \n by \r\n (the Windows standard line terminator) giving a result of \r\r\n.

Fiddling with the lineterminator is NOT the solution.

Install Node.js on Ubuntu

npm is automatically installed with Node.js in the latest version of Node.js. What do you see when you type node --version and npm --version in the terminal?

You can upgrade npm using npm itself as well:

[sudo] npm install -g npm

What does "<>" mean in Oracle

It means 'not equal to'. So you're filtering out records where ordid is 605. Overall you're looking for any records which have the same prodid and qty values as those assigned to ordid 605, but which are for a different order.

Easy way to prevent Heroku idling?

One more working solution: wokeDyno Here is a blog post how it works: It's integrated in the app very easy:

/* Example: as used with an Express app */

const express = require("express")
const wakeDyno = require("woke-dyno");

// create an Express app
const app = express();

// start the server, then call wokeDyno(url).start()
app.listen(PORT, () => {
    wakeDyno(DYNO_URL).start(); // DYNO_URL should be the url of your Heroku app

Javascript code for showing yesterday's date and todays date

One liner:

var yesterday = new Date( - 864e5); // 864e5 == 86400000 == 24*60*60*1000

Making the Android emulator run faster

I noticed that the emulator defaults to only Core 0, where most Windows applications will default to "any" core. Also, if you put it on another core (like the last core), it may make the emulator go crazy. If you can, you can try putting your heavy-CPU usage applications on the other CPU cores for a boost in speed.

Hardware-wise, get the fastest CPU you can get that works for single-core applications. More than 2 cores might not experience a huge difference in terms of emulator performance.

Eclipse + the Android emulator together eat up a ton of RAM. I would recommend 3 gigs of RAM at least because I used a system with 2 gigs of RAM, and it slowed down because the system ran out of RAM and started to use the page file.

I feel that the best CPUs for it will probably have a high clock (only use clock as a measure for CPUs in the same series btw), handle non-SIMD operations well, and have a turbo boost mechanism. There aren't many Java-based benchmarks, but overall look for application benchmarks like compression and office. Don't look at gaming or media since those are affected greatly by SIMD. If you find a Java one, even better.

Java Webservice Client (Best way)

I have had good success using Spring WS for the client end of a web service app - see

My project uses a combination of:

  • XMLBeans (generated from a simple Maven job using the xmlbeans-maven-plugin)

  • Spring WS - using marshalSendAndReceive() reduces the code down to one line for sending and receiving

  • some Dozer - mapping the complex XMLBeans to simple beans for the client GUI

Wait for page load in Selenium


driver.manage().timeOuts().implicitlyWait(10, TimeUnit.SECONDS);

Which means any search for the elements on the web page could take time to load. The implicitlyWait is set before throwing an exception. The TimeUnit displays whichever way you want to wait in (seconds, minutes, hours and days).

Error when using scp command "bash: scp: command not found"

Make sure the scp command is available on both sides - both on the client and on the server.

If this is Fedora or Red Hat Enterprise Linux and clones (CentOS), make sure this package is installed:

    yum -y install openssh-clients

If you work with Debian or Ubuntu and clones, install this package:

    apt-get install openssh-client

Again, you need to do this both on the server and the client, otherwise you can encounter "weird" error messages on your client: scp: command not found or similar although you have it locally. This already confused thousands of people, I guess :)

jQuery Ajax File Upload

Simple Upload Form

   //form Submit_x000D_
   $("form").submit(function(evt){  _x000D_
      var formData = new FormData($(this)[0]);_x000D_
       url: 'fileUpload',_x000D_
       type: 'POST',_x000D_
       data: formData,_x000D_
       async: false,_x000D_
       cache: false,_x000D_
       contentType: false,_x000D_
       enctype: 'multipart/form-data',_x000D_
       processData: false,_x000D_
       success: function (response) {_x000D_
   return false;_x000D_
<!--Upload Form-->_x000D_
      <td colspan="2">File Upload</td>_x000D_
      <th>Select File </th>_x000D_
      <td><input id="csv" name="csv" type="file" /></td>_x000D_
      <td colspan="2">_x000D_
        <input type="submit" value="submit"/> _x000D_

How to get item count from DynamoDB?

I'm too late here but like to extend Daniel's answer about using aws cli to include filter expression.


aws dynamodb scan \
    --table-name <tableName> \
    --filter-expression "#v = :num" \
    --expression-attribute-names '{"#v": "fieldName"}' \
    --expression-attribute-values '{":num": {"N": "123"}}' \
    --select "COUNT"

would give

    "Count": 2945,
    "ScannedCount": 7874,
    "ConsumedCapacity": null

That is, ScannedCount is total count and Count is the number of items which are filtered by given expression (fieldName=123).

How do I tell Python to convert integers into words

Convert numbers to words:
Here is an example in which numbers have been converted into words using the dictionary.

string = input("Enter a string: ")
my_dict = {'0': 'zero', '1': 'one', '2': 'two', '3': 'three', '4': 'four', '5': 'five', '6': 'six', '7': 'seven', '8': 'eight', '9': 'nine'}
for item in string:
  if item in my_dict.keys():
    string = string.replace(item, my_dict[item])


What is the difference between encrypting and signing in asymmetric encryption?

In RSA crypto, when you generate a key pair, it's completely arbitrary which one you choose to be the public key, and which is the private key. If you encrypt with one, you can decrypt with the other - it works in both directions.

So, it's fairly simple to see how you can encrypt a message with the receiver's public key, so that the receiver can decrypt it with their private key.

A signature is proof that the signer has the private key that matches some public key. To do this, it would be enough to encrypt the message with that sender's private key, and include the encrypted version alongside the plaintext version. To verify the sender, decrypt the encrypted version, and check that it is the same as the plaintext.

Of course, this means that your message is not secret. Anyone can decrypt it, because the public key is well known. But when they do so, they have proved that the creator of the ciphertext has the corresponding private key.

However, this means doubling the size of your transmission - plaintext and ciphertext together (assuming you want people who aren't interested in verifying the signature, to read the message). So instead, typically a signature is created by creating a hash of the plaintext. It's important that fake hashes can't be created, so cryptographic hash algorithms such as SHA-2 are used.


  • To generate a signature, make a hash from the plaintext, encrypt it with your private key, include it alongside the plaintext.
  • To verify a signature, make a hash from the plaintext, decrypt the signature with the sender's public key, check that both hashes are the same.

SQL Insert Multiple Rows

For MSSQL, there are two ways:(Consider you have a 'users' table,below both examples are using this table for example)

1) In case, you need to insert different values in users table. Then you can write statement like:

(2, 'Michael', 'Blythe'),
(3, 'Linda', 'Mitchell'),
(4, 'Jillian', 'Carson'),
(5, 'Garrett', 'Vargas');

2) Another case, if you need to insert same value for all rows(for example, 10 rows you need to insert here). Then you can use below sample statement:

(2, 'Michael', 'Blythe')
GO 10

Hope this helps.

Bootstrap col-md-offset-* not working

Kindly use offset-md-4 instead of col-md-offset-4 in bootstrap 4. It's little changes adopted in bootstrap 4.

For more info

WaitAll vs WhenAll

What do they do:

  • Internally both do the same thing.

What's the difference:

  • WaitAll is a blocking call
  • WhenAll - not - code will continue executing

Use which when:

  • WaitAll when cannot continue without having the result
  • WhenAll when what just to be notified, not blocked

JsonParseException : Illegal unquoted character ((CTRL-CHAR, code 10)

On Salesforce platform this error is caused by /, the solution is to escape these as //.

Fatal error compiling: invalid target release: 1.8 -> [Help 1]

For eclipse here is how I solved my problem:

  1. Preferences --> Compiler --> Compiler Complainer Level (Change to 1.8) enter image description here

  2. Perferences --> Installed JREs --> select JAVA SE 8 1.8 enter image description here

  3. Rebuild via maven using Run as maven build.

It shouldn't show you the invalid target error anymore.
Note: I didn't have to set or change any other variables in my terminal. Hope this helps.

Case Statement Equivalent in R

As of data.table v1.13.0 you can use the function fcase() (fast-case) to do SQL-like CASE operations (also similar to dplyr::case_when()):


dt <- data.table(name = c('cow','pig','eagle','pigeon','cow','eagle'))
dt[ , category := fcase(name %in% c('cow', 'pig'), 'mammal',
                        name %in% c('eagle', 'pigeon'), 'bird') ]

How to keep console window open

For visual c# console Application use:


for visual c++ win32 console application use:


press ctrl+f5 to run the application.

App not setup: This app is still in development mode

Go to Settings->Basic, on top you will find a Switch button which will say App is in development mode.

enter image description here

Click on in development switch button, it will ask you to make app live, and after providing all necessary things, it will become live.

enter image description here

Append an int to a std::string

I have a feeling that your ClientID is not of a string type (zero-terminated char* or std::string) but some integral type (e.g. int) so you need to convert number to the string first:

std::stringstream ss;
ss << ClientID;

But you can use operator+ as well (instead of append):

query += ss.str();

Java: convert List<String> to a String

Try this:

java.util.Arrays.toString(anArray).replaceAll(", ", ",")

rails bundle clean

If you are using Bundler 1.1 or later you can use bundle clean, just as you imagined you could. This is redundant if you're using bundle install --path (Bundler manages the location you specified with --path, so takes responsibility for removing outdated gems), but if you've used Bundler to install the gems as system gems then bundle clean --force will delete any system gems not required by your Gemfile. Blindingly obvious caveat: don't do this if you have other apps that rely on system gems that aren't in your Gemfile!

Pat Shaughnessy has a good description of bundle clean and other new additions in bundler 1.1.

How to show changed file name only with git log?

This gives almost what you need:

git log --stat --oneline

Commit id + short one line still remains, followed by list of changed files by that commit.

jQuery: using a variable as a selector

You're thinking too complicated. It's actually just $('#'+openaddress).

IntelliJ IDEA "cannot resolve symbol" and "cannot resolve method"

I was facing the same problem when import projects into IntelliJ.

for in my case first, check SDK details and check you have configured JDK correctly or not.

Go to File-> Project Structure-> platform Settings-> SDKs

Check your JDK is correct or not.

enter image description here

Next, I Removed project from IntelliJ and delete all IntelliJ and IDE related files and folder from the project folder (.idea, .settings, .classpath, dependency-reduced-pom). Also, delete the target folder and re-import the project.

The above solution worked in my case.

Are nested try/except blocks in Python a good programming practice?

Your first example is perfectly fine. Even the official Python documentation recommends this style known as EAFP.

Personally, I prefer to avoid nesting when it's not necessary:

def __getattribute__(self, item):
        return object.__getattribute__(item)
    except AttributeError:
        pass  # Fallback to dict
        return self.dict[item]
    except KeyError:
        raise AttributeError("The object doesn't have such attribute") from None

PS. has_key() has been deprecated for a long time in Python 2. Use item in self.dict instead.

Sequence contains more than one element

FYI you can also get this error if EF Migrations tries to run with no Db configured, for example in a Test Project.

Chased this for hours before I figured out that it was erroring on a query, but, not because of the query but because it was when Migrations kicked in to try to create the Db.

jQuery.ajax returns 400 Bad Request

Add this to your ajax call:

contentType: "application/json; charset=utf-8",
dataType: "json"

HTML Submit-button: Different value / button-text?

If you handle "adding tag" via JScript:

<form ...>
<button onclick="...">any text you want</button>

Or above if handle via page reload

Django Rest Framework -- no module named rest_framework

I know there is an accepted answer for this question and many other answers also but I just wanted to add an another case which happened with me was Updating the django and django rest framework to the latest versions to make them work properly without any error.

So all you have to do is just uninstall both django and django rest framework using:

pip uninstall django pip uninstall djangorestframework

and then install it again using:

pip install django pip install djangorestframework

How can I remove leading and trailing quotes in SQL Server?

The following script removes quotation marks only from around the column value if table is called [Messages] and the column is called [Description].

-- If the content is in the form of "anything" (LIKE '"%"')
-- Then take the whole text without the first and last characters 
-- (from the 2nd character and the LEN([Description]) - 2th character)

UPDATE [Messages]
SET [Description] = SUBSTRING([Description], 2, LEN([Description]) - 2)
WHERE [Description] LIKE '"%"'

sort files by date in PHP

You need to put the files into an array in order to sort and find the last modified file.

$files = array();
if ($handle = opendir('.')) {
    while (false !== ($file = readdir($handle))) {
        if ($file != "." && $file != "..") {
           $files[filemtime($file)] = $file;

    // sort
    // find the last modification
    $reallyLastModified = end($files);

    foreach($files as $file) {
        $lastModified = date('F d Y, H:i:s',filemtime($file));
        if(strlen($file)-strpos($file,".swf")== 4){
           if ($file == $reallyLastModified) {
             // do stuff for the real last modified file
           echo "<tr><td><input type=\"checkbox\" name=\"box[]\"></td><td><a href=\"$file\" target=\"_blank\">$file</a></td><td>$lastModified</td></tr>";

Not tested, but that's how to do it.

How to increase the gap between text and underlining in CSS

@last-child's answer is a great answer!

However, adding a border to my H2 produced an underline longer than the text.

If you're dynamically writing your CSS, or if like me you're lucky and know what the text will be, you can do the following:

  1. change the content to something the right length (ie the same

  2. text) set the font color to transparent (or rgba(0,0,0,0) )

to underline <h2>Processing</h2> (for example), change last-child's code to be:

a {
    text-decoration: none;
    position: relative;
a:after {
    content: 'Processing';
    color: transparent;

    width: 100%;
    position: absolute;
    left: 0;
    bottom: 1px;

    border-width: 0 0 1px;
    border-style: solid;

Read response body in JAX-RS client from a post request

I also had the same issue, trying to run a unit test calling code that uses readEntity. Can't use getEntity in production code because that just returns a ByteInputStream and not the content of the body and there is no way I am adding production code that is hit only in unit tests.

My solution was to create a response and then use a Mockito spy to mock out the readEntity method:

Response error = Response.serverError().build();
Response mockResponse = spy(error);

Note that you can't use the when(mockResponse.readEntity(String.class) option because that throws the same IllegalStateException.

Hope this helps!

How to disable editing of elements in combobox for c#?

This is another method I use because changing DropDownSyle to DropDownList makes it look 3D and sometimes its just plain ugly.

You can prevent user input by handling the KeyPress event of the ComboBox like this.

private void ComboBox1_KeyPress(object sender, KeyPressEventArgs e)
      e.Handled = true;

#include errors detected in vscode

The answer is here: How to use C/Cpp extension and add includepath to configurations.

Click the light bulb and then edit the JSON file which is opened. Choose the right block corresponding to your platform (there are Mac, Linux, Win32 – ms-vscode.cpptools version: 3). Update paths in includePath (matters if you compile with VS Code) or browse.paths (matters if you navigate with VS Code) or both.

Thanks to @Francesco Borzì, I will append his answer here:

You have to Left click on the bulb next to the squiggled code line.

If a #include file or one of its dependencies cannot be found, you can also click on the red squiggles under the include statements to view suggestions for how to update your configuration.

enter image description here

MySQL Install: ERROR: Failed to build gem native extension

I had also forgotten to actually install MySQL in the first place. Following this guide helped a lot.

As well as adding these lines to my .profile:

export PATH="/usr/local/mysql/bin:$PATH"
alias mysql=/usr/local/mysql/bin/mysql
alias mysqladmin=/usr/local/mysql/bin/mysqladmin

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

What makes jQuery easy to use is that you don't have to apply attributes to each element. The jQuery object contains an array of elements, and the methods of the jQuery object applies the same attributes to all the elements in the array.

There is also a shorter form for $(document).ready(function(){...}) in $(function(){...}).

So, this is all you need:

  $('div.easy_editor').css('border','9px solid red');

If you want the code to work for any element with that class, you can just specify the class in the selector without the tag name:

  $('.easy_editor').css('border','9px solid red');

Using custom fonts using CSS?

To make sure that your font is cross-browser compatible, make sure that you use this syntax:

@font-face {
    font-family: 'Comfortaa Regular';
    src: url('Comfortaa.eot');
    src: local('Comfortaa Regular'), 
         url('Comfortaa.ttf') format('truetype'),
         url('Comfortaa.svg#font') format('svg'); 

Taken from here.

I didn't find "ZipFile" class in the "System.IO.Compression" namespace

A solution that helped me: Go to Tools > NuGet Package Manager > Manage NuGet Packaged for Solution... > Browse > Search for System.IO.Compression.ZipFile and install it

How to convert a string with Unicode encoding to a string of letters

UnicodeUnescaper from org.apache.commons:commons-text is also acceptable.

new UnicodeUnescaper().translate("\u0048\u0065\u006C\u006C\u006F World") returns "Hello World"

twig: IF with multiple conditions

If I recall correctly Twig doesn't support || and && operators, but requires or and and to be used respectively. I'd also use parentheses to denote the two statements more clearly although this isn't technically a requirement.

{%if ( fields | length > 0 ) or ( trans_fields | length > 0 ) %}


Expressions can be used in {% blocks %} and ${ expressions }.

Operator    Description
==          Does the left expression equal the right expression?
+           Convert both arguments into a number and add them.
-           Convert both arguments into a number and substract them.
*           Convert both arguments into a number and multiply them.
/           Convert both arguments into a number and divide them.
%           Convert both arguments into a number and calculate the rest of the integer division.
~           Convert both arguments into a string and concatenate them.
or          True if the left or the right expression is true.
and         True if the left and the right expression is true.
not         Negate the expression.

For more complex operations, it may be best to wrap individual expressions in parentheses to avoid confusion:

{% if (foo and bar) or (fizz and (foo + bar == 3)) %}

Fragment onCreateView and onActivityCreated called twice

I was scratching my head about this for a while too, and since Dave's explanation is a little hard to understand I'll post my (apparently working) code:

private class TabListener<T extends Fragment> implements ActionBar.TabListener {
    private Fragment mFragment;
    private Activity mActivity;
    private final String mTag;
    private final Class<T> mClass;

    public TabListener(Activity activity, String tag, Class<T> clz) {
        mActivity = activity;
        mTag = tag;
        mClass = clz;

    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        if (mFragment == null) {
            mFragment = Fragment.instantiate(mActivity, mClass.getName());
            ft.replace(, mFragment, mTag);
        } else {
            if (mFragment.isDetached()) {

    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        if (mFragment != null) {

    public void onTabReselected(Tab tab, FragmentTransaction ft) {

As you can see it's pretty much like the Android sample, apart from not detaching in the constructor, and using replace instead of add.

After much headscratching and trial-and-error I found that finding the fragment in the constructor seems to make the double onCreateView problem magically go away (I assume it just ends up being null for onTabSelected when called through the ActionBar.setSelectedNavigationItem() path when saving/restoring state).

center aligning a fixed position div

Normal divs should use margin-left: auto and margin-right: auto, but that doesn't work for fixed divs. The way around this is similar to Andrew's answer, but doesn't use the deprecated <center> thing. Basically, just give the fixed div a wrapper.

#wrapper {_x000D_
    width: 100%;_x000D_
    position: fixed;_x000D_
    background: gray;_x000D_
#fixed_div {_x000D_
    margin-left: auto;_x000D_
    margin-right: auto;_x000D_
    position: relative;_x000D_
    width: 100px;_x000D_
    height: 30px;_x000D_
    text-align: center;_x000D_
    background: lightgreen;_x000D_
<div id="wrapper">_x000D_
    <div id="fixed_div"></div>_x000D_

This will center a fixed div within a div while allowing the div to react with the browser. i.e. The div will be centered if there's enough space, but will collide with the edge of the browser if there isn't; similar to how a regular centered div reacts.

How to rename array keys in PHP?

This is how I rename keys, especially with data that has been uploaded in a spreadsheet:

function changeKeys($array, $new_keys) {
    $newArray = [];

    foreach($array as $row) {
        $oldKeys = array_keys($row);
        $indexedRow = [];

        foreach($new_keys as $index => $newKey)
            $indexedRow[$newKey] = isset($oldKeys[$index]) ? $row[$oldKeys[$index]] : '';

        $newArray[] = $indexedRow;

    return $newArray;

Python unittest - opposite of assertRaises?

If you pass an Exception class to assertRaises(), a context manager is provided. This can improve the readability of your tests:

# raise exception if Application created with bad data
with self.assertRaises(pySourceAidExceptions.PathIsNotAValidOne):
    application = Application("abcdef", "")

This allows you to test error cases in your code.

In this case, you are testing the PathIsNotAValidOne is raised when you pass invalid parameters to the Application constructor.

What is "with (nolock)" in SQL Server?

You can use it when you're only reading data, and you don't really care about whether or not you might be getting back data that is not committed yet.

It can be faster on a read operation, but I cannot really say by how much.

In general, I recommend against using it - reading uncommitted data can be a bit confusing at best.

Caused By: java.lang.NoClassDefFoundError: org/apache/log4j/Logger

During runtime your application is unable to find the jar.

Taken from this answer by Jared:

It is important to keep two different exceptions straight in our head in this case:

  1. java.lang.ClassNotFoundException This an Exception, it indicates that the class was not found on the classpath. This indicates that we were trying to load the class definition, and the class did not exist on the classpath.

  2. java.lang.NoClassDefFoundError This is Error, it indicates that the JVM looked in its internal class definition data structure for the definition of a class and did not find it. This is different than saying that it could not be loaded from the classpath. Usually this indicates that we previously attempted to load a class from the classpath, but it failed for some reason - now we're trying again, but we're not even going to try to load it, because we failed loading it earlier. The earlier failure could be a ClassNotFoundException or an ExceptionInInitializerError (indicating a failure in the static initialization block) or any number of other problems. The point is, a NoClassDefFoundError is not necessarily a classpath problem.

for similarities and differences

How to get exact browser name and version?

Use device detection solution to detect browser name, vendor and version.

First, follow the 4-step guide to incorporate device detector in to your project. When I say incorporate I mean download archive with PHP code and database file, extract them and include 2 files. That's all there is to do to incorporate.

Once that's done you can use the following properties to get browser information:
$_51d['BrowserName'] - Gives you the name of the browser (Safari, Molto, Motorola, MStarBrowser etc).
$_51d['BrowserVendor'] - Gives you the company who created browser.
$_51d['BrowserVersion'] - Version number of the browser

How do we update URL or query strings using javascript/jQuery without reloading the page?

Plain javascript: document.location = '';

This will cause a browser refresh though - consider using hashes if you're in need of having the URL updated to implement some kind of browsing history without reloading the page. You might want to look into jQuery.hashchange if this is the case.