Programs & Examples On #Porter duff

In computer graphics, alpha compositing(technique invented by Porter and Duff) is the process of combining an image with a background to create the appearance of partial or full transparency. It is often useful to render image elements in separate passes, and then combine the resulting multiple 2D images into a single, final image in a process called compositing.

How do you append an int to a string in C++?

cout << text << " " << i << endl;

GUI Tool for PostgreSQL

Postgres Enterprise Manager from EnterpriseDB is probably the most advanced you'll find. It includes all the features of pgAdmin, plus monitoring of your hosts and database servers, predictive reporting, alerting and a SQL Profiler.

Ninja edit disclaimer/notice: it seems that this user is affiliated with EnterpriseDB, as the linked Postgres Enterprise Manager website contains a video of one Dave Page.

'npm' is not recognized as internal or external command, operable program or batch file

I had the same problem described by Ashu, but in addition to that, the PATH entry for nodejs was terminated by a backslash:

C:\Program Files\nodejs\

I also had to remove that final backslash in order to have it work.

How to display .svg image using swift

You can use SVGKit for example.

1) Integrate it according to instructions. Drag&dropping the .framework file is fast and easy.

2) Make sure you have an Objective-C to Swift bridge file bridging-header.h with import code in it:

#import <SVGKit/SVGKit.h>
#import <SVGKit/SVGKImage.h>

3) Use the framework like this, assuming that dataFromInternet is NSData, previously downloaded from network:

let anSVGImage: SVGKImage = SVGKImage(data: dataFromInternet)
myIUImageView.image = anSVGImage.UIImage

The framework also allows to init an SVGKImage from other different sources, for example it can download image for you when you provide it with URL. But in my case it was crashing in case of unreachable url, so it turned out to be better to manage networking by myself. More info on it here.

jQuery append() - return appended elements

There's a simpler way to do this:


This turns things around by first creating newHtml with jQuery(html [, ownerDocument ]), and then using appendTo(target) (note the "To" bit) to add that it to the end of #mydiv.

Because you now start with $(newHtml) the end result of appendTo('#myDiv') is that new bit of html, and the .effects(...) call will be on that new bit of html too.


Sure, what do you want to use for the gid? a static value, PHP var, ...

A static value of 1234 could be like:

INSERT INTO courses (name, location, gid)
SELECT name, location, 1234
FROM courses
WHERE cid = $cid

How to read the post request parameters using JavaScript

POST is what browser sends from client(your broswer) to the web server. Post data is send to server via http headers, and it is available only at the server end or in between the path (example: a proxy server) from client (your browser) to web-server. So it cannot be handled from client side scripts like JavaScript. You need to handle it via server side scripts like CGI, PHP, Java etc. If you still need to write in JavaScript you need to have a web-server which understands and executes JavaScript in your server like Node.js

Remove characters after specific character in string, then remove substring?

I second Hightechrider: there is a specialized Url class already built for you.

I must also point out, however, that the PHP's replaceAll uses regular expressions for search pattern, which you can do in .NET as well - look at the RegEx class.

Find by key deep in a nested array

Just use recursive function.
See example below:

const data = [
    title: 'some title',
    channel_id: '123we',
    options: [
        channel_id: 'abc',
        image: '',
        title: 'All-Inclusive',
        options: [
            channel_id: 'dsa2',
            title: 'Some Recommends',
            options: [
                image: '',
                title: 'Sandals',
                id: '1',
                content: {},

function _find(collection, key, value) {
  for (const o of collection) {
    for (const [k, v] of Object.entries(o)) {
      if (k === key && v === value) {
        return o
      if (Array.isArray(v)) {
        const _o = _find(v, key, value)
        if (_o) {
          return _o

console.log(_find(data, 'channel_id', 'dsa2'))

Using Selenium Web Driver to retrieve value of a HTML input


Eventhough if you don't see the "value" attribute in html dom, you will get the field value displayed on the GUI.

What exactly does numpy.exp() do?

It calculates ex for each x in your list where e is Euler's number (approximately 2.718). In other words, np.exp(range(5)) is similar to [math.e**x for x in range(5)].

Missing include "bits/c++config.h" when cross compiling 64 bit program on 32 bit in Ubuntu

Basically It is used in HeapOverflows or other reversing type Problems i.e. If you want to change a 64 bit ELF to 32 bit ELF and it is showing error while converting.

You can simply run the commands

apt-get install gcc-multilib g++-multilib

which will update your libraries Packages upgraded:

The following additional packages will be installed: g++-8-multilib gcc-8-multilib lib32asan5 lib32atomic1 lib32gcc-8-dev lib32gomp1 lib32itm1 lib32mpx2 lib32quadmath0 lib32stdc++-8-dev lib32ubsan1 libc-dev-bin libc6 libc6-dbg libc6-dev libc6-dev-i386 libc6-dev-x32 libc6-i386 libc6-x32 libx32asan5 libx32atomic1 libx32gcc-8-dev libx32gcc1 libx32gomp1 libx32itm1 libx32quadmath0 libx32stdc++-8-dev libx32stdc++6 libx32ubsan1 Suggested packages: lib32stdc++6-8-dbg libx32stdc++6-8-dbg glibc-doc The following NEW packages will be installed: g++-8-multilib g++-multilib gcc-8-multilib gcc-multilib lib32asan5 lib32atomic1 lib32gcc-8-dev lib32gomp1 lib32itm1 lib32mpx2 lib32quadmath0 lib32stdc++-8-dev lib32ubsan1 libc6-dev-i386 libc6-dev-x32 libc6-x32 libx32asan5 libx32atomic1 libx32gcc-8-dev libx32gcc1 libx32gomp1 libx32itm1 libx32quadmath0 libx32stdc++-8-dev libx32stdc++6 libx32ubsan1

similar to this will be shown to your terminal

What exactly is the difference between Web API and REST API in MVC?

I have been there, like so many of us. There are so many confusing words like Web API, REST, RESTful, HTTP, SOAP, WCF, Web Services... and many more around this topic. But I am going to give brief explanation of only those which you have asked.


It is neither an API nor a framework. It is just an architectural concept. You can find more details here.


I have not come across any formal definition of RESTful anywhere. I believe it is just another buzzword for APIs to say if they comply with REST specifications.

EDIT: There is another trending open source initiative OpenAPI Specification (OAS) (formerly known as Swagger) to standardise REST APIs.


It in an open source framework for writing HTTP APIs. These APIs can be RESTful or not. Most HTTP APIs we write are not RESTful. This framework implements HTTP protocol specification and hence you hear terms like URIs, request/response headers, caching, versioning, various content types(formats).

Note: I have not used the term Web Services deliberately because it is a confusing term to use. Some people use this as a generic concept, I preferred to call them HTTP APIs. There is an actual framework named 'Web Services' by Microsoft like Web API. However it implements another protocol called SOAP.

Call parent method from child class c#

To follow up on the comment by suhendri to Rory McCrossan answer. Here is an Action delegate example:

In child add:

public Action UpdateProgress;  // In place of event handler declaration
                               // declare an Action delegate
private LoadData() {
    this.UpdateProgress();    // call to Action delegate - MyMethod in
                              // parent

In parent add:

// The 3 lines in the parent becomes:
ChildClass child = new ChildClass();
child.UpdateProgress = this.MyMethod;  // assigns MyMethod to child delegate

What is FCM token in Firebase?

FirebaseInstanceIdService is now deprecated. you should get the Token in the onNewToken method in the FirebaseMessagingService.

Check out the docs

How to remove text from a string?

Plain old JavaScript will suffice - jQuery is not necessary for such a simple task:

var myString = "data-123";
var myNewString = myString.replace("data-", "");

See: .replace() docs on MDN for additional information and usage.

nvm is not compatible with the npm config "prefix" option:

I have the same error message but other solution. The autogenerated path during curl ( does not match. Check this with:

echo $NVM_DIR

In my case: /var/www//.nvm. Show in your auto generated bash file and change it and replace it: (~/.bash_profile, ~/.zshrc, ~/.profile, or ~/.bashrc)


export NVM_DIR="$HOME/.nvm"

with (e.g.)

export NVM_DIR="$HOME.nvm"

What do hjust and vjust do when making a plot using ggplot?

Probably the most definitive is Figure B.1(d) of the ggplot2 book, the appendices of which are available at

enter image description here

However, it is not quite that simple. hjust and vjust as described there are how it works in geom_text and theme_text (sometimes). One way to think of it is to think of a box around the text, and where the reference point is in relation to that box, in units relative to the size of the box (and thus different for texts of different size). An hjust of 0.5 and a vjust of 0.5 center the box on the reference point. Reducing hjust moves the box right by an amount of the box width times 0.5-hjust. Thus when hjust=0, the left edge of the box is at the reference point. Increasing hjust moves the box left by an amount of the box width times hjust-0.5. When hjust=1, the box is moved half a box width left from centered, which puts the right edge on the reference point. If hjust=2, the right edge of the box is a box width left of the reference point (center is 2-0.5=1.5 box widths left of the reference point. For vertical, less is up and more is down. This is effectively what that Figure B.1(d) says, but it extrapolates beyond [0,1].

But, sometimes this doesn't work. For example

DF <- data.frame(x=c("a","b","cdefghijk","l"),y=1:4)
p <- ggplot(DF, aes(x,y)) + geom_point()

p + opts(axis.text.x=theme_text(vjust=0))
p + opts(axis.text.x=theme_text(vjust=1))
p + opts(axis.text.x=theme_text(vjust=2))

The three latter plots are identical. I don't know why that is. Also, if text is rotated, then it is more complicated. Consider

p + opts(axis.text.x=theme_text(hjust=0, angle=90))
p + opts(axis.text.x=theme_text(hjust=0.5 angle=90))
p + opts(axis.text.x=theme_text(hjust=1, angle=90))
p + opts(axis.text.x=theme_text(hjust=2, angle=90))

The first has the labels left justified (against the bottom), the second has them centered in some box so their centers line up, and the third has them right justified (so their right sides line up next to the axis). The last one, well, I can't explain in a coherent way. It has something to do with the size of the text, the size of the widest text, and I'm not sure what else.

Get column value length, not column max length of value

LENGTH() does return the string length (just verified). I suppose that your data is padded with blanks - try

SELECT typ, LENGTH(TRIM(t1.typ))


As OraNob mentioned, another cause could be that CHAR is used in which case LENGTH() would also return the column width, not the string length. However, the TRIM() approach also works in this case.

Best way to center a <div> on a page vertically and horizontally?

div {_x000D_
    position: absolute;_x000D_
    top: 50%;_x000D_
    left: 50%;_x000D_
    transform: translate(-50%, -50%);_x000D_
    -ms-transform: translate(-50%, -50%); /* IE 9 */_x000D_
    -webkit-transform: translate(-50%, -50%); /* Chrome, Safari, Opera */     _x000D_
    <div>Div to be aligned vertically</div>_x000D_

position: absolute div in body document

An element with position: absolute; is positioned relative to the nearest positioned ancestor (instead of positioned relative to the viewport (body tag), like fixed).

However; if an absolute positioned element has no positioned ancestors, it uses the document body, and moves along with page scrolling.

source: CSS position

How can I compare time in SQL Server?

Adding to the other answers:

you can create a function for trimming the date from a datetime

CREATE FUNCTION dbo.f_trimdate (@dat datetime) RETURNS DATETIME AS BEGIN

So this:

SELECT @dat = '20080201 02:25:46.000'
SELECT dbo.f_trimdate(@dat)

Will return 1900-01-01 02:25:46.000

How to use Bootstrap modal using the anchor tag for Register?

Just replace it:

<li><a href="" data-toggle="modal" data-target="#modalRegister">Register</a></li>

Instead of:

<li><a href="#" data-toggle="modal" data-target="modalRegister">Register</a></li>

How to convert jsonString to JSONObject in Java

Use JsonNode of fasterxml for the Generic Json Parsing. It internally creates a Map of key value for all the inputs.


private void test(@RequestBody JsonNode node)

input String :


get all characters to right of last dash

I can see this post was viewed over 46,000 times. I would bet many of the 46,000 viewers are asking this question simply because they just want the file name... and these answers can be a rabbit hole if you cannot make your substring verbatim using the at sign.

If you simply want to get the file name, then there is a simple answer which should be mentioned here. Even if it's not the precise answer to the question.

result = Path.GetFileName(fileName);


DIV height set as percentage of screen?

This is the solution ,

Add the html also to 100%

html,body {

   height: 100%;
   width: 100%;


How can I get the key value in a JSON object?

Try out this

var str ="{ "name" : "user"}";
var jsonData = JSON.parse(str);     

//Array Object

str ="[{ "name" : "user"},{ "name" : "user2"}]";
jsonData = JSON.parse(str);     

sql searching multiple words in a string

Maybe EXISTS can help.

and exists (select 1 from @DocumentNames where pcd.Name like DocName+'%' or CD.DocumentName like DocName+'%')

Laravel Redirect Back with() Message

You have an error (misspelling):

Sessions::get('msg')// an extra 's' on end

Should be:


I think, now it should work, it does for me.

How to change icon on Google map marker

var marker = new google.maps.Marker({
                position: new google.maps.LatLng(23.016427,72.571156),
                map: map,
                icon: 'images/map_marker_icon.png',
                title: 'Hi..!'

apply local path on icon only

How do I implement onchange of <input type="text"> with jQuery?

You could simply work with the id

$("#your_id").on("change",function() {

How can I change the font-size of a select option?

Tell the option element to be 13pt

select option{
    font-size: 13pt;

and then the first option element to be 7pt

select option:first-child {
    font-size: 7pt;

Running demo:

__init__() missing 1 required positional argument

You need to pass some data into it. An empty dictionary, for example.

if __name__ == '__main__': DHT('a').showData()

However, in your example a parameter is not even needed. You can declare it by just:

def __init__(self):

Maybe you mean to set it from the data?

class DHT:
    def __init__(self, data):['one'] = data['one']['two'] = data['two']['three'] = data['three']
    def showData(self):

if __name__ == '__main__': DHT({'one':2, 'two':4, 'three':5}).showData()

showData will print the data you just entered.

Passing parameters to a Bash function

If you prefer named parameters, it's possible (with a few tricks) to actually pass named parameters to functions (also makes it possible to pass arrays and references).

The method I developed allows you to define named parameters passed to a function like this:

function example { args : string firstName , string lastName , integer age } {
  echo "My name is ${firstName} ${lastName} and I am ${age} years old."

You can also annotate arguments as @required or @readonly, create arguments, create arrays from sequential arguments (using e.g. string[4]) and optionally list the arguments in multiple lines:

function example {
    : @required string firstName
    : string lastName
    : integer age
    : string[] ...favoriteHobbies

  echo "My name is ${firstName} ${lastName} and I am ${age} years old."
  echo "My favorite hobbies include: ${favoriteHobbies[*]}"

In other words, not only you can call your parameters by their names (which makes up for a more readable core), you can actually pass arrays (and references to variables - this feature works only in Bash 4.3 though)! Plus, the mapped variables are all in the local scope, just as $1 (and others).

The code that makes this work is pretty light and works both in Bash 3 and Bash 4 (these are the only versions I've tested it with). If you're interested in more tricks like this that make developing with bash much nicer and easier, you can take a look at my Bash Infinity Framework, the code below is available as one of its functionalities.

shopt -s expand_aliases

function assignTrap {
  local evalString
  local -i paramIndex=${__paramIndex-0}
  local initialCommand="${1-}"

  if [[ "$initialCommand" != ":" ]]
    echo "trap - DEBUG; eval \"${__previousTrap}\"; unset __previousTrap; unset __paramIndex;"

  while [[ "${1-}" == "," || "${1-}" == "${initialCommand}" ]] || [[ "${#@}" -gt 0 && "$paramIndex" -eq 0 ]]
    shift # First colon ":" or next parameter's comma ","
    local -a decorators=()
    while [[ "${1-}" == "@"* ]]
      decorators+=( "$1" )

    local declaration=
    local wrapLeft='"'
    local wrapRight='"'
    local nextType="$1"
    local length=1

    case ${nextType} in
      string | boolean) declaration="local " ;;
      integer) declaration="local -i" ;;
      reference) declaration="local -n" ;;
      arrayDeclaration) declaration="local -a"; wrapLeft= ; wrapRight= ;;
      assocDeclaration) declaration="local -A"; wrapLeft= ; wrapRight= ;;
      "string["*"]") declaration="local -a"; length="${nextType//[a-z\[\]]}" ;;
      "integer["*"]") declaration="local -ai"; length="${nextType//[a-z\[\]]}" ;;

    if [[ "${declaration}" != "" ]]
      local nextName="$1"

      for decorator in "${decorators[@]}"
        case ${decorator} in
          @readonly) declaration+="r" ;;
          @required) evalString+="[[ ! -z \$${paramIndex} ]] || echo \"Parameter '$nextName' ($nextType) is marked as required by '${FUNCNAME[1]}' function.\"; " >&2 ;;
          @global) declaration+="g" ;;

      local paramRange="$paramIndex"

      if [[ -z "$length" ]]
        # trim leading ...
        if [[ "${#@}" -gt 1 ]]
          echo "Unexpected arguments after a rest array ($nextName) in '${FUNCNAME[1]}' function." >&2
      elif [[ "$length" -gt 1 ]]
        paramIndex+=$((length - 1))

      evalString+="${declaration} ${nextName}=${wrapLeft}\$${paramRange}${wrapRight}; "

      # Continue to the next parameter:
  echo "${evalString} local -i __paramIndex=${paramIndex};"

alias args='local __previousTrap=$(trap -p DEBUG); trap "eval \"\$(assignTrap \$BASH_COMMAND)\";" DEBUG;'

Print string to text file

With using pathlib module, indentation isn't needed.

import pathlib
pathlib.Path("output.txt").write_text("Purchase Amount: {}" .format(TotalAmount))

As of python 3.6, f-strings is available.

pathlib.Path("output.txt").write_text(f"Purchase Amount: {TotalAmount}")

Memcache Vs. Memcached

(PartlyStolen from ServerFault)

I think that both are functionally the same, but they simply have different authors, and the one is simply named more appropriately than the other.

Here is a quick backgrounder in naming conventions (for those unfamiliar), which explains the frustration by the question asker: For many *nix applications, the piece that does the backend work is called a "daemon" (think "service" in Windows-land), while the interface or client application is what you use to control or access the daemon. The daemon is most often named the same as the client, with the letter "d" appended to it. For example "imap" would be a client that connects to the "imapd" daemon.

This naming convention is clearly being adhered to by memcache when you read the introduction to the memcache module (notice the distinction between memcache and memcached in this excerpt):

Memcache module provides handy procedural and object oriented interface to memcached, highly effective caching daemon, which was especially designed to decrease database load in dynamic web applications.

The Memcache module also provides a session handler (memcache).

More information about memcached can be found at »

The frustration here is caused by the author of the PHP extension which was badly named memcached, since it shares the same name as the actual daemon called memcached. Notice also that in the introduction to memcached (the php module), it makes mention of libmemcached, which is the shared library (or API) that is used by the module to access the memcached daemon:

memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.

This extension uses libmemcached library to provide API for communicating with memcached servers. It also provides a session handler (memcached).

Information about libmemcached can be found at »

How to enable MySQL Query Log?

I had to drop and recreate the general log at one point. During the recreation, character sets got messed up and I ended up having this error in the logs:

[ERROR] Incorrect definition of table mysql.general_log: expected the type of column 'user_host' at position 1 to have character set 'utf8' but found character set 'latin1'

So if the standard answer of "check to make sure logging is on" doesn't work for you, check to make sure your fields have the right character set.

Correct way of looping through C++ arrays

You can do it as follow:

#include < iostream >

using namespace std;

int main () {

   string texts[] = {"Apple", "Banana", "Orange"};

   for( unsigned int a = 0; a < sizeof(texts) / 32; a++ ) { // 32 is the size of string data type

       cout << "value of a: " << texts[a] << endl;


   return 0;


Customize Bootstrap checkboxes

Since Bootstrap 3 doesn't have a style for checkboxes I found a custom made that goes really well with Bootstrap style.


.checkbox label:after {_x000D_
  content: '';_x000D_
  display: table;_x000D_
  clear: both;_x000D_
.checkbox .cr {_x000D_
  position: relative;_x000D_
  display: inline-block;_x000D_
  border: 1px solid #a9a9a9;_x000D_
  border-radius: .25em;_x000D_
  width: 1.3em;_x000D_
  height: 1.3em;_x000D_
  float: left;_x000D_
  margin-right: .5em;_x000D_
.checkbox .cr .cr-icon {_x000D_
  position: absolute;_x000D_
  font-size: .8em;_x000D_
  line-height: 0;_x000D_
  top: 50%;_x000D_
  left: 15%;_x000D_
.checkbox label input[type="checkbox"] {_x000D_
  display: none;_x000D_
.checkbox label input[type="checkbox"]>.cr-icon {_x000D_
  opacity: 0;_x000D_
.checkbox label input[type="checkbox"]>.cr-icon {_x000D_
  opacity: 1;_x000D_
.checkbox label input[type="checkbox"] {_x000D_
  opacity: .5;_x000D_
<link rel="stylesheet" href="" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">_x000D_
<!-- Default checkbox -->_x000D_
<div class="checkbox">_x000D_
   <input type="checkbox" value="">_x000D_
   <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span>_x000D_
   Option one_x000D_
<!-- Checked checkbox -->_x000D_
<div class="checkbox">_x000D_
   <input type="checkbox" value="" checked>_x000D_
   <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span>_x000D_
   Option two is checked by default_x000D_
<!-- Disabled checkbox -->_x000D_
<div class="checkbox disabled">_x000D_
   <input type="checkbox" value="" disabled>_x000D_
   <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span>_x000D_
   Option three is disabled_x000D_


.checkbox label:after,_x000D_
.radio label:after {_x000D_
  content: '';_x000D_
  display: table;_x000D_
  clear: both;_x000D_
.checkbox .cr,_x000D_
.radio .cr {_x000D_
  position: relative;_x000D_
  display: inline-block;_x000D_
  border: 1px solid #a9a9a9;_x000D_
  border-radius: .25em;_x000D_
  width: 1.3em;_x000D_
  height: 1.3em;_x000D_
  float: left;_x000D_
  margin-right: .5em;_x000D_
.radio .cr {_x000D_
  border-radius: 50%;_x000D_
.checkbox .cr .cr-icon,_x000D_
.radio .cr .cr-icon {_x000D_
  position: absolute;_x000D_
  font-size: .8em;_x000D_
  line-height: 0;_x000D_
  top: 50%;_x000D_
  left: 13%;_x000D_
.radio .cr .cr-icon {_x000D_
  margin-left: 0.04em;_x000D_
.checkbox label input[type="checkbox"],_x000D_
.radio label input[type="radio"] {_x000D_
  display: none;_x000D_
.checkbox label input[type="checkbox"]>.cr-icon,_x000D_
.radio label input[type="radio"]>.cr-icon {_x000D_
  opacity: 0;_x000D_
.checkbox label input[type="checkbox"]>.cr-icon,_x000D_
.radio label input[type="radio"]>.cr-icon {_x000D_
  opacity: 1;_x000D_
.checkbox label input[type="checkbox"],_x000D_
.radio label input[type="radio"] {_x000D_
  opacity: .5;_x000D_
<link rel="stylesheet" href="" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">_x000D_
<link rel="stylesheet" href="" integrity="sha384-+d0P83n9kaQMCwj8F4RJB66tzIwOKmrdb46+porD/OvrJ+37WqIM7UoBtwHO6Nlg" crossorigin="anonymous">_x000D_
<!-- Default radio -->_x000D_
<div class="radio">_x000D_
   <input type="radio" name="o3" value="">_x000D_
   <span class="cr"><i class="cr-icon fa fa-circle"></i></span>_x000D_
   Option one_x000D_
<!-- Checked radio -->_x000D_
<div class="radio">_x000D_
   <input type="radio" name="o3" value="" checked>_x000D_
   <span class="cr"><i class="cr-icon fa fa-circle"></i></span>_x000D_
   Option two is checked by default_x000D_
<!-- Disabled radio -->_x000D_
<div class="radio disabled">_x000D_
   <input type="radio" name="o3" value="" disabled>_x000D_
   <span class="cr"><i class="cr-icon fa fa-circle"></i></span>_x000D_
   Option three is disabled_x000D_

Custom icons

You can choose your own icon between the ones from Bootstrap or Font Awesome by changing [icon name] with your icon.

<span class="cr"><i class="cr-icon [icon name]"></i>

For example:

  • glyphicon glyphicon-remove for Bootstrap, or
  • fa fa-bullseye for Font Awesome

.checkbox label:after,_x000D_
.radio label:after {_x000D_
  content: '';_x000D_
  display: table;_x000D_
  clear: both;_x000D_
.checkbox .cr,_x000D_
.radio .cr {_x000D_
  position: relative;_x000D_
  display: inline-block;_x000D_
  border: 1px solid #a9a9a9;_x000D_
  border-radius: .25em;_x000D_
  width: 1.3em;_x000D_
  height: 1.3em;_x000D_
  float: left;_x000D_
  margin-right: .5em;_x000D_
.radio .cr {_x000D_
  border-radius: 50%;_x000D_
.checkbox .cr .cr-icon,_x000D_
.radio .cr .cr-icon {_x000D_
  position: absolute;_x000D_
  font-size: .8em;_x000D_
  line-height: 0;_x000D_
  top: 50%;_x000D_
  left: 15%;_x000D_
.radio .cr .cr-icon {_x000D_
  margin-left: 0.04em;_x000D_
.checkbox label input[type="checkbox"],_x000D_
.radio label input[type="radio"] {_x000D_
  display: none;_x000D_
.checkbox label input[type="checkbox"]>.cr-icon,_x000D_
.radio label input[type="radio"]>.cr-icon {_x000D_
  opacity: 0;_x000D_
.checkbox label input[type="checkbox"]>.cr-icon,_x000D_
.radio label input[type="radio"]>.cr-icon {_x000D_
  opacity: 1;_x000D_
.checkbox label input[type="checkbox"],_x000D_
.radio label input[type="radio"] {_x000D_
  opacity: .5;_x000D_
<link rel="stylesheet" href="" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">_x000D_
<link rel="stylesheet" href="" integrity="sha384-+d0P83n9kaQMCwj8F4RJB66tzIwOKmrdb46+porD/OvrJ+37WqIM7UoBtwHO6Nlg" crossorigin="anonymous">_x000D_
<div class="checkbox">_x000D_
   <input type="checkbox" value="" checked>_x000D_
   <span class="cr"><i class="cr-icon glyphicon glyphicon-remove"></i></span>_x000D_
   Bootstrap - Custom icon checkbox_x000D_
<div class="radio">_x000D_
   <input type="radio" name="o3" value="" checked>_x000D_
   <span class="cr"><i class="cr-icon fa fa-bullseye"></i></span>_x000D_
   Font Awesome - Custom icon radio checked by default_x000D_
<div class="radio">_x000D_
   <input type="radio" name="o3" value="">_x000D_
   <span class="cr"><i class="cr-icon fa fa-bullseye"></i></span>_x000D_
   Font Awesome - Custom icon radio_x000D_

The view didn't return an HttpResponse object. It returned None instead

I had the same error using an UpdateView

I had this:

if form.is_valid() and form2.is_valid():
    return HttpResponseRedirect(self.get_success_url())

and I solved just doing:

if form.is_valid() and form2.is_valid():
    return HttpResponseRedirect(reverse_lazy('adopcion:solicitud_listar'))

SQL Server: use CASE with LIKE

You can also do like this

select *
from table
where columnName like '%' + case when @varColumn is null then '' else @varColumn end  +  ' %'

Can I call a base class's virtual function if I'm overriding it?

If you want to call a function of base class from its derived class you can simply call inside the overridden function with mentioning base class name(like Foo::printStuff()).

code goes here

#include <iostream>
using namespace std;

class Foo
    int x;

    virtual void printStuff()
         cout<<"Base Foo printStuff called"<<endl;

class Bar : public Foo
    int y;

    void printStuff()
        cout<<"derived Bar printStuff called"<<endl;
        Foo::printStuff();/////also called the base class method

int main()
    Bar *b=new Bar;

Again you can determine at runtime which function to call using the object of that class(derived or base).But this requires your function at base class must be marked as virtual.

code below

#include <iostream>
using namespace std;

class Foo
    int x;

    virtual void printStuff()
         cout<<"Base Foo printStuff called"<<endl;

class Bar : public Foo
    int y;

    void printStuff()
        cout<<"derived Bar printStuff called"<<endl;

int main()

    Foo *foo=new Foo;
    foo->printStuff();/////this call the base function
    foo=new Bar;

PHP, get file name without file extension

Almost all the above solution have the shown getting filename from variable $path

Below snippet will get the current executed file name without extension

echo pathinfo(basename($_SERVER['SCRIPT_NAME']), PATHINFO_FILENAME);


$_SERVER['SCRIPT_NAME'] contains the path of the current script.

How can I execute a python script from an html button?

Using a UI Framework would be a lot cleaner (and involve fewer components). Here is an example using wxPython:

import wx
import os
class MyForm(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, "Launch Scripts")
        panel = wx.Panel(self, wx.ID_ANY)
        sizer = wx.BoxSizer(wx.VERTICAL)
        buttonA = wx.Button(panel, id=wx.ID_ANY, label="App A", name="MYSCRIPT")
        buttonB = wx.Button(panel, id=wx.ID_ANY, label="App B", name="MYOtherSCRIPT")
        buttonC = wx.Button(panel, id=wx.ID_ANY, label="App C", name="SomeDifferentScript")
        buttons = [buttonA, buttonB, buttonC]

        for button in buttons:
            self.buildButtons(button, sizer)


    def buildButtons(self, btn, sizer):
        btn.Bind(wx.EVT_BUTTON, self.onButton)
        sizer.Add(btn, 0, wx.ALL, 5)

    def onButton(self, event):
        This method is fired when its corresponding button is pressed, taking the script from it's name
        button = event.GetEventObject()

        os.system('python {}.py'.format(button.GetName()))

        button_id = event.GetId()
        button_by_id = self.FindWindowById(button_id)
        print "The button you pressed was labeled: " + button_by_id.GetLabel()
        print "The button's name is " + button_by_id.GetName()

# Run the program
if __name__ == "__main__":
    app = wx.App(False)
    frame = MyForm()

I haven't tested this yet, and I'm sure there are cleaner ways of launching a python script form a python script, but the idea I think will still hold. Good luck!

Select all from table with Laravel and Eloquent

If your table is very big, you can also process rows by "small packages" (not all at oce) (laravel doc: Eloquent> Chunking Results )

Post::chunk(200, function($posts)
    foreach ($posts as $post)
        // process post here.

Pandas DataFrame column to list

I'd like to clarify a few things:

  1. As other answers have pointed out, the simplest thing to do is use pandas.Series.tolist(). I'm not sure why the top voted answer leads off with using pandas.Series.values.tolist() since as far as I can tell, it adds syntax/confusion with no added benefit.
  2. tst[lookupValue][['SomeCol']] is a dataframe (as stated in the question), not a series (as stated in a comment to the question). This is because tst[lookupValue] is a dataframe, and slicing it with [['SomeCol']] asks for a list of columns (that list that happens to have a length of 1), resulting in a dataframe being returned. If you remove the extra set of brackets, as in tst[lookupValue]['SomeCol'], then you are asking for just that one column rather than a list of columns, and thus you get a series back.
  3. You need a series to use pandas.Series.tolist(), so you should definitely skip the second set of brackets in this case. FYI, if you ever end up with a one-column dataframe that isn't easily avoidable like this, you can use pandas.DataFrame.squeeze() to convert it to a series.
  4. tst[lookupValue]['SomeCol'] is getting a subset of a particular column via chained slicing. It slices once to get a dataframe with only certain rows left, and then it slices again to get a certain column. You can get away with it here since you are just reading, not writing, but the proper way to do it is tst.loc[lookupValue, 'SomeCol'] (which returns a series).
  5. Using the syntax from #4, you could reasonably do everything in one line: ID = tst.loc[tst['SomeCol'] == 'SomeValue', 'SomeCol'].tolist()

Demo Code:

import pandas as pd
df = pd.DataFrame({'colA':[1,2,1],
filter_value = 1

print "df"
print df
print type(df)

rows_to_keep = df['colA'] == filter_value
print "\ndf['colA'] == filter_value"
print rows_to_keep
print type(rows_to_keep)

result = df[rows_to_keep]['colB']
print "\ndf[rows_to_keep]['colB']"
print result
print type(result)

result = df[rows_to_keep][['colB']]
print "\ndf[rows_to_keep][['colB']]"
print result
print type(result)

result = df[rows_to_keep][['colB']].squeeze()
print "\ndf[rows_to_keep][['colB']].squeeze()"
print result
print type(result)

result = df.loc[rows_to_keep, 'colB']
print "\ndf.loc[rows_to_keep, 'colB']"
print result
print type(result)

result = df.loc[df['colA'] == filter_value, 'colB']
print "\ndf.loc[df['colA'] == filter_value, 'colB']"
print result
print type(result)

ID = df.loc[rows_to_keep, 'colB'].tolist()
print "\ndf.loc[rows_to_keep, 'colB'].tolist()"
print ID
print type(ID)

ID = df.loc[df['colA'] == filter_value, 'colB'].tolist()
print "\ndf.loc[df['colA'] == filter_value, 'colB'].tolist()"
print ID
print type(ID)


   colA  colB
0     1     4
1     2     5
2     1     6
<class 'pandas.core.frame.DataFrame'>

df['colA'] == filter_value
0     True
1    False
2     True
Name: colA, dtype: bool
<class 'pandas.core.series.Series'>

0    4
2    6
Name: colB, dtype: int64
<class 'pandas.core.series.Series'>

0     4
2     6
<class 'pandas.core.frame.DataFrame'>

0    4
2    6
Name: colB, dtype: int64
<class 'pandas.core.series.Series'>

df.loc[rows_to_keep, 'colB']
0    4
2    6
Name: colB, dtype: int64
<class 'pandas.core.series.Series'>

df.loc[df['colA'] == filter_value, 'colB']
0    4
2    6
Name: colB, dtype: int64
<class 'pandas.core.series.Series'>

df.loc[rows_to_keep, 'colB'].tolist()
[4, 6]
<type 'list'>

df.loc[df['colA'] == filter_value, 'colB'].tolist()
[4, 6]
<type 'list'>

5.7.57 SMTP - Client was not authenticated to send anonymous mail during MAIL FROM error

Main two reasons only as mentioned in above comments

  1. NetworkCredentials you set should be correct. Verify with try actually signing into the account.
  2. You need to set UseDefaultCredentials to false first and then set Credentials Or Put smtp.UseDefaultCredentials = false; above the smtp.Credentials assignment.

Find and replace - Add carriage return OR Newline

Make sure "Use: Regular expressions" is selected in the Find and Replace dialog:

Find/Replace Dialog Use Regular expressions

Note that for Visual Studio 2010, this doesn't work in the Visual Studio Productivity Power Tools' "Quick Find" extension (as of the July 2011 update); instead, you'll need to use the full Find and Replace dialog (use Ctrl+Shift+H, or Edit --> Find and Replace --> Replace in Files), and change the scope to "Current Document".

Pass correct "this" context to setTimeout callback?

If you're using underscore, you can use bind.


if (this.options.destroyOnHide) {
     setTimeout(_.bind(this.tip.destroy, this), 1000);

Sass nth-child nesting

I'd be careful about trying to get too clever here. I think it's confusing as it is and using more advanced nth-child parameters will only make it more complicated. As for the background color I'd just set that to a variable.

Here goes what I came up with before I realized trying to be too clever might be a bad thing.

#romtest {
 $bg: #e5e5e5;
 .detailed {
    th {
      &:nth-child(-2n+6) {
        background-color: $bg;
    td {
      &:nth-child(3n), &:nth-child(2), &:nth-child(7) {
        background-color: $bg;
      &.last {
          background-color: $bg;

and here is a quick demo:


Here's another approach to avoid retyping background-color:

#romtest {
  %highlight {
    background-color: #e5e5e5; 
  .detailed {
    th {
      &:nth-child(-2n+6) {
        @extend %highlight;

    td {
      &:nth-child(3n), &:nth-child(2), &:nth-child(7) {
        @extend %highlight;
      &.last {
          @extend %highlight;

Unfortunately MyApp has stopped. How can I solve this?

Use the LogCat and try to find what is causing the app to crash.

To see Logcat if you use Android Studio then Press ALT + 6 or

if you use Eclipse then Window -> Open Perspective -> Other - LogCat

Go to the LogCat, from the drop down menu select error. This will contain all the required information to help you debug. If that doesn't help, post the LogCat as an edit to your question and somebody will help you out.

How to test web service using command line curl

Answering my own question.

curl -X GET --basic --user username:password \

curl -X DELETE --basic --user username:password \

curl -X PUT --basic --user username:password -d 'param1_name=param1_value' \
     -d 'param2_name=param2_value'

POSTing a file and additional parameter

curl -X POST -F 'param_name=@/filepath/filename' \
     -F 'extra_param_name=extra_param_value' --basic --user username:password \

What's the complete range for Chinese characters in Unicode?

Unicode version 11.0.0

In Unicode the Chinese, Japanese and Korean (CJK) scripts share a common background, collectively known as CJK characters.

These ranges often contain non-assigned or reserved code points(such as U+2E9A , U+2EF4 - 2EFF),

Chinese characters

bottom  top     reference (also have a look at wiki page)   block name
4E00    9FEF CJK Unified Ideographs
3400    4DBF CJK Unified Ideographs Extension A
20000   2A6DF    CJK Unified Ideographs Extension B
2A700   2B73F    CJK Unified Ideographs Extension C
2B740   2B81F    CJK Unified Ideographs Extension D
2B820   2CEAF    CJK Unified Ideographs Extension E
2CEB0   2EBEF   CJK Unified Ideographs Extension F
3007    3007    in block CJK Symbols and Punctuation
  • In CJK Unified Ideographs block, I notice many answers use upper bound 9FCC, but U+9FCD(?) is indeed a Chinese char. And all characters in this block are Chinese characters (also used in Japanese or Korean etc.).
  • Most of characters in CJK Unified Ideographs Ext (Except Ext F, only 17% in Ext F are Chinese characters), are traditional Chinese characters, which are rarely used in China.
  • ? is the Chinese character form of zero and still in use today

Therefore the range is


CJK characters but never used in Chinese

They are Common Han used only for compatibility.

It is almost impossible to see them appear in any Chinese books, articles, writings etc.

All characters here have one corresponding glyph-identical Chinese character, such as ?(U+F90A) and ?(U+91D1), they are identical glyphs.

 F900    FAFF  CJK Compatibility Ideographs
2F800   2FA1F CJK Compatibility Ideographs Supplement

CJK related symbols

2E80    2EFF CJK Radicals Supplement
2F00    2FDF Kangxi Radicals 
2FF0    2FFF    Ideographic Description Character
3000    303F    CJK Symbols and Punctuation
3100    312f    Bopomofo
31A0    31BF    Bopomofo Extended
31C0    31EF CJK Strokes
3200    32FF    Enclosed CJK Letters and Months
3300    33FF    CJK Compatibility
FE30    FE4F    CJK Compatibility Forms
FF00    FFEF    Halfwidth and Fullwidth Forms
1F200   1F2FF   Enclosed Ideographic Supplement
  • some blocks such as Hangul Compatibility Jamo are excluded because of no relation to Chinese.
  • Kangxi Radicals is not Chinese characters, they are graphical components of Chinese characters, used specially to express radicals, .e.g. ?(U+2F3B) and ?(U+5F73), ?(U+2EDC) and ? (U+98DE)

Other common punctuation appearing in Chinese

This is a wide range, some punctuation may be never used, some punctuations such as ……”“ are used so much in Chinese.

0000    007F    C0 Controls and Basic Latin 
2000    206F    General Punctuation

There are also many Chinese-related symbols, such as Yijing Hexagram Symbols or Kanbun, but it's off-topic anyway. I write non-chinese-characters in CJK to have a better explanation of what Chinese characters are. And the ranges above already cover almost all the characters which appear in Chinese writing except math and other specialty notation.


CJK Symbols and Punctuation

 ???????<>«»??????????????[]?????????????????????????????????? ? ?

Halfwidth and Fullwidth Forms



  1. (in chinese language, notice the right side bar)
  2. (notice the bottom table)

Set default value of an integer column SQLite

Use the SQLite keyword default


This link is useful:

Find out whether radio button is checked with JQuery?

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

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

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

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

JavaScript override methods

Once should avoid emulating classical OO and use prototypical OO instead. A nice utility library for prototypical OO is traits.

Rather then overwriting methods and setting up inheritance chains (one should always favour object composition over object inheritance) you should be bundling re-usable functions into traits and creating objects with those.

Live Example

var modifyA = {
    modify: function() {
        this.x = 300;
        this.y = 400;

var modifyB = {
    modify: function() {
        this.x = 3000;
        this.y = 4000;

C = function(trait) {
    var o = Object.create(Object.prototype, Trait(trait));

    console.log("sum : " + (o.x + o.y));

    return o;


How can I set the background color of <option> in a <select> element?

I assume you mean the <select> input element?

Support for that is pretty new, but FF 3.6, Chrome and IE 8 render this all right:

<select name="select">
  <option value="1" style="background-color: blue">Test</option>
  <option value="2" style="background-color: green">Test</option>

What is a method group in C#?

You can cast a method group into a delegate.

The delegate signature selects 1 method out of the group.

This example picks the ToString() overload which takes a string parameter:

Func<string,string> fn = 123.ToString;

This example picks the ToString() overload which takes no parameters:

Func<string> fn = 123.ToString;

How to execute mongo commands through shell scripts?

mongo db_name --eval "db.user_info.find().forEach(function(o) {print(o._id);})"

Best way to test for a variable's existence in PHP; isset() is clearly broken

isset checks if the variable is set and, if so, whether its value is not NULL. The latter part is (in my opinion) not within the scope of this function. There is no decent workaround to determine whether a variable is NULL because it is not set or because it is explicitly set to NULL.

Here is one possible solution:

$e1 = error_get_last();
$isNULL = is_null(@$x);
$e2 = error_get_last();
$isNOTSET = $e1 != $e2;
echo sprintf("isNOTSET: %d, isNULL: %d", $isNOTSET, $isNULL);

// Sample output:
// when $x is not set: isNOTSET: 1, isNULL: 1
// when $x = NULL:     isNOTSET: 0, isNULL: 1
// when $x = false:    isNOTSET: 0, isNULL: 0

Other workaround is to probe the output of get_defined_vars():

$vars = get_defined_vars();
$isNOTSET = !array_key_exists("x", $vars);
$isNULL = $isNOTSET ? true : is_null($x);
echo sprintf("isNOTSET: %d, isNULL: %d", $isNOTSET, $isNULL);

// Sample output:
// when $x is not set: isNOTSET: 1, isNULL: 1
// when $x = NULL:     isNOTSET: 0, isNULL: 1
// when $x = false:    isNOTSET: 0, isNULL: 0

HTTP Request in Swift with POST method

@IBAction func btn_LogIn(sender: AnyObject) {

    let request = NSMutableURLRequest(URL: NSURL(string: "")!)
    request.HTTPMethod = "POST"
    let postString = "email: [email protected] & password: testtest"
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)
    let task = NSURLSession.sharedSession().dataTaskWithRequest(request){data, response, error in
        guard error == nil && data != nil else{
        if let httpStatus = response as? NSHTTPURLResponse where httpStatus.statusCode != 200{
            print("statusCode should be 200, but is \(httpStatus.statusCode)")
            print("response = \(response)")
        let responseString = String(data: data!, encoding: NSUTF8StringEncoding)
        print("responseString = \(responseString)")

How to affect other elements when one element is hovered

In this particular example, you can use:

#container:hover #cube {
    background-color: yellow;   

This example only works since cube is a child of container. For more complicated scenarios, you'd need to use different CSS, or use JavaScript.

When to use a linked list over an array/array list?

A simple answer to the question can be given using these points:

  1. Arrays are to be used when a collection of similar type data elements is required. Whereas, linked list is a collection of mixed type data linked elements known as nodes.

  2. In array, one can visit any element in O(1) time. Whereas, in linked list we would need to traverse entire linked list from head to the required node taking O(n) time.

  3. For arrays, a specific size needs to be declared initially. But linked lists are dynamic in size.

Perl: Use s/ (replace) and return new string

print "bla: ", $_, "\n" if ($_ = $myvar) =~ s/a/b/g or 1;

How to get highcharts dates in the x axis?

You write like this-:

xAxis: {
        type: 'datetime',
        dateTimeLabelFormats: {
           day: '%d %b %Y'    //ex- 01 Jan 2016

also check for other datetime format

Principal Component Analysis (PCA) in Python

In addition to all the other answers, here is some code to plot the biplot using sklearn and matplotlib.

import numpy as np
import matplotlib.pyplot as plt
from sklearn import datasets
from sklearn.decomposition import PCA
import pandas as pd
from sklearn.preprocessing import StandardScaler

iris = datasets.load_iris()
X =
y =
#In general a good idea is to scale the data
scaler = StandardScaler()

pca = PCA()
x_new = pca.fit_transform(X)

def myplot(score,coeff,labels=None):
    xs = score[:,0]
    ys = score[:,1]
    n = coeff.shape[0]
    scalex = 1.0/(xs.max() - xs.min())
    scaley = 1.0/(ys.max() - ys.min())
    plt.scatter(xs * scalex,ys * scaley, c = y)
    for i in range(n):
        plt.arrow(0, 0, coeff[i,0], coeff[i,1],color = 'r',alpha = 0.5)
        if labels is None:
            plt.text(coeff[i,0]* 1.15, coeff[i,1] * 1.15, "Var"+str(i+1), color = 'g', ha = 'center', va = 'center')
            plt.text(coeff[i,0]* 1.15, coeff[i,1] * 1.15, labels[i], color = 'g', ha = 'center', va = 'center')

#Call the function. Use only the 2 PCs.
myplot(x_new[:,0:2],np.transpose(pca.components_[0:2, :]))

enter image description here

How can I clear the content of a file?

The easiest way is:

File.WriteAllText(path, string.Empty)

However, I recommend you use FileStream because the first solution can throw UnauthorizedAccessException

using(FileStream fs = File.Open(path,FileMode.OpenOrCreate, FileAccess.ReadWrite))

How do I access previous promise results in a .then() chain?

This days, I also hava meet some questions like you. At last, I find a good solution with the quesition, it's simple and good to read. I hope this can help you.

According to how-to-chain-javascript-promises

ok, let's look at the code:

const firstPromise = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log('first promise is completed');
            resolve({data: '123'});
        }, 2000);

const secondPromise = (someStuff) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log('second promise is completed');
            resolve({newData: `${} some more data`});
        }, 2000);

const thirdPromise = (someStuff) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log('third promise is completed');
            resolve({result: someStuff});
        }, 2000);

    .then(data => {

System.web.mvc missing


C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET Web Stack 5\Packages\ Microsoft.AspNet.Mvc.5.0.0\lib\net45\System.Web.Mvc.dll


C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 4\Assemblies\System.Web.Mvc.dll


C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll


C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 2\Assemblies\System.Web.Mvc.dll

Where can I find System.Web.MVC dll in a system where MVC 3 is installed?

Deserialize JSON with C#

You need to create a structure like this:

public class Friends

    public List<FacebookFriend> data {get; set;}

public class FacebookFriend

    public string id {get; set;}
    public string name {get; set;}

Then you should be able to do:

Friends facebookFriends = new JavaScriptSerializer().Deserialize<Friends>(result);

The names of my classes are just an example. You should use proper names.

Adding a sample test:

string json =
    @"{""data"":[{""id"":""518523721"",""name"":""ftyft""}, {""id"":""527032438"",""name"":""ftyftyf""}, {""id"":""527572047"",""name"":""ftgft""}, {""id"":""531141884"",""name"":""ftftft""}]}";

Friends facebookFriends = new System.Web.Script.Serialization.JavaScriptSerializer().Deserialize<Friends>(json);

foreach(var item in
    Console.WriteLine("id: {0}, name: {1}",,;


id: 518523721, name: ftyft
id: 527032438, name: ftyftyf
id: 527572047, name: ftgft
id: 531141884, name: ftftft

Relay access denied on sending mail, Other domain outside of network

Configuring $mail->SMTPAuth = true; was the solution for me. The reason why is because without authentication the mail server answers with 'Relay access denied'. Since putting this in my code, all mails work fine.

Remove a HTML tag but keep the innerHtml

You can also use .replaceWith(), like this:

$("b").replaceWith(function() { return $(this).contents(); });

Or if you know it's just a string:

$("b").replaceWith(function() { return this.innerHTML; });

This can make a big difference if you're unwrapping a lot of elements since either approach above is significantly faster than the cost of .unwrap().

Adding attribute in jQuery

You can do this with jQuery's .attr function, which will set attributes. Removing them is done via the .removeAttr function.

$("element").attr("id", "newId");
$("element").attr("disabled", true);


Running powershell script within python script, how to make python print the powershell output while it is running

I don't have Python 2.7 installed, but in Python 3.3 calling Popen with stdout set to sys.stdout worked just fine. Not before I had escaped the backslashes in the path, though.

>>> import subprocess
>>> import sys
>>> p = subprocess.Popen(['powershell.exe', 'C:\\Temp\\test.ps1'], stdout=sys.stdout)
>>> Hello World

'if' statement in jinja2 template

Why the loop?

You could simply do this:

{% if 'priority' in data %}
    <p>Priority: {{ data['priority'] }}</p>
{% endif %}

When you were originally doing your string comparison, you should have used == instead.

Use PHP composer to clone git repo

I was encountering the following error: The requested package my-foo/bar could not be found in any version, there may be a typo in the package name.

If you're forking another repo to make your own changes you will end up with a new repository.


The new url will need to go into your repositories section of your composer.json.

Remember if you want refer to your fork as my-foo/bar in your require section, you will have to rename the package in the composer.json file inside of your new repo.

    "name":         "foo/bar",


    "name":         "my-foo/bar",

If you've just forked the easiest way to do this is edit it right inside github.

Android Studio - local path doesn't exist

For those who still can't solve this issue after following all the answers on here. Look in the Gradle console. I had build errors that for some reason were only showing on the Gradle console. Once I fixed them, I could run the app.

Read the package name of an Android APK

aapt list -a "path_to_apk"

I recommend you save it in a .txt, because it can be very long. So:

aapt list -a "path_to_apk" > file.txt

Then see the file.txt in your current directory.

How to change Rails 3 server default port in develoment?

If you're using puma (I'm using this on Rails 6+):

To change default port for all environments:

The "{3000}" part sets the default port if undefined in ENV.


    port ENV.fetch('PORT') { 3000 }
    port ENV.fetch('PORT') { 10524 }

To define it depending on the environment, using Figaro gem for credentials/environment variable:

local_db_username: your_user_name
?local_db_password: your_password
PORT: 10524

You can adapt this to you own environment variable manager.

How to do this using jQuery - document.getElementById("selectlist").value

Chaos is spot on, though for these sorts of questions you should check out the Jquery Documentation online - it really is quite comprehensive. The feature you are after is called 'jquery selectors'

Generally you do $('#ID').val() - the .afterwards can do a number of things on the element that is returned from the selector. You can also select all of the elements on a certain class and do something to each of them. Check out the documentation for some good examples.

How to decode jwt token in javascript without using a library?

If you use Node.JS, You can use the native Buffer module by doing :

const token = 'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWUsImp0aSI6ImU3YjQ0Mjc4LTZlZDYtNDJlZC05MTZmLWFjZDQzNzhkM2U0YSIsImlhdCI6MTU5NTg3NzUxOCwiZXhwIjoxNTk1ODgxMTE4fQ.WXyDlDMMSJAjOFF9oAU9JrRHg2wio-WolWAkAaY3kg4';
const base64Url = token.split('.')[1];
const decoded = Buffer.from(base64Url, 'base64').toString();

And you're good to go :-)

Android scale animation on view

Add this code on values anim

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="">


call on styles.xml

<style name="DialogScale">
    <item name="android:windowEnterAnimation">@anim/scale_in</item>
    <item name="android:windowExitAnimation">@anim/scale_out</item>

In Java code: set Onclick

public void onClick(View v) {
            fab_onclick(, "Scale" ,(Activity) context,getWindow().getDecorView().getRootView());
          //  Dialogs.fab_onclick(, "Scale");


setup on method:

alertDialog.getWindow().getAttributes().windowAnimations = type;

Does the 'mutable' keyword have any purpose other than allowing the variable to be modified by a const function?

The mutable keyword is very useful when creating stubs for class test purposes. You can stub a const function and still be able to increase (mutable) counters or whatever test functionality you have added to your stub. This keeps the interface of the stubbed class intact.

How to Round to the nearest whole number in C#

Use Math.Round:

double roundedValue = Math.Round(value, 0)

How to update and order by using ms sql

You can do a subquery where you first get the IDs of the top 10 ordered by priority and then update the ones that are on that sub query:

UPDATE  messages 
SET status=10 
             FROM Table 
             WHERE status=0 
             ORDER BY priority DESC);

Submitting form and pass data to controller method of type FileStreamResult

When in doubt, follow MVC conventions.

Create a viewModel if you haven't already that contains a property for JobID

public class Model
     public string JobId {get; set;}
     public IEnumerable<MyCurrentModel> myCurrentModel { get; set; }
     //...any other properties you may need

Strongly type your view

@model Fully.Qualified.Path.To.Model

Add a hidden field for JobId to the form

using (@Html.BeginForm("myMethod", "Home", FormMethod.Post))
    @Html.HiddenFor(m => m.JobId)

And accept the model as the parameter in your controller action:

public FileStreamResult myMethod(Model model)
    sting str = model.JobId;

Convert tabs to spaces in Notepad++

Obsolete: This answer is correct only for an older version of Notepad++. Converting between tabs/spaces is now built into Notepad++ and the TextFX plugin is no longer available in the Plugin Manager dialog.

  • First set the "replace by spaces" setting in Preferences -> Language Menu/Tab Settings.
  • Next, open the document you wish to replace tabs with.
  • Highlight all the text (CTRL+A).
  • Then select TextFX -> TextFX Edit -> Leading spaces to tabs or tabs to spaces.

Note: Make sure TextFX Characters plugin is installed (Plugins -> Plugin manager -> Show plugin manager, Installed tab). Otherwise, there will be no TextFX menu.

Centering in CSS Grid

Try using flex:

Plunker demo :

/* Styles go here */

body {
  margin: 0;
  padding: 0;

.container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-rows: 100vh;
  grid-gap: 0px 0px;

.left_bg {
  background-color: #3498db;
  grid-column: 1 / 1;
  grid-row: 1 / 1;
  z-index: 0;
  display: flex;
  justify-content: center;
  align-items: center;


.right_bg {
  background-color: #ecf0f1;
  grid-column: 2 / 2;
  grid_row: 1 / 1;
  z-index: 0;
  display: flex;
  justify-content: center;
  align-items: center;

.text {
  font-family: Raleway;
  font-size: large;
  text-align: center;


    <div class="container">
  <!--everything on the page-->

  <div class="left_bg">
    <!--left background color of the page-->
    <div class="text">
      <!--left side text content-->
      <p>Review my stuff</p>

  <div class="right_bg">
    <!--right background color of the page-->
    <div class="text">
      <!--right side text content-->
      <p>Hire me!</p>

How to change the date format of a DateTimePicker in

Try this code it works:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim CustomeDate As String = ("#" & DOE.Value.Date.ToString("d/MM/yyyy") & "#")


    dadap = New System.Data.OleDb.OleDbDataAdapter("SELECT * FROM QRY_Tran where FORMAT(qry_tran.doe,'d/mm/yyyy') = " & CustomeDate & "", con)

    ds = New System.Data.DataSet
    Dgview.DataSource = ds.Tables(0)

Note : if u use dd for date representation it will return nothing while selecting 1 to 9 so use d for selection

'Date time format
'MMM     Three-letter month.
'ddd     Three-letter day of the week.
'd       Day of the month.
'HH      Two-digit hours on 24-hour scale.
'mm      Two-digit minutes.
'yyyy    Four-digit year.

The documentation contains a full list of the date formats.

Java FileOutputStream Create File if not exists

You can potentially get a FileNotFoundException if the file does not exist.

Java documentation says:

Whether or not a file is available or may be created depends upon the underlying platform

If you're using Java 7 you can use the java.nio package:

The options parameter specifies how the the file is created or opened... it opens the file for writing, creating the file if it doesn't exist...

How to escape "&" in XML?

use &amp; in place of &

change to

<string name="magazine">Newspaper &amp; Magazines</string>

Returning a regex match in VBA (excel)

You need to access the matches in order to get at the SDI number. Here is a function that will do it (assuming there is only 1 SDI number per cell).

For the regex, I used "sdi followed by a space and one or more numbers". You had "sdi followed by a space and zero or more numbers". You can simply change the + to * in my pattern to go back to what you had.

Function ExtractSDI(ByVal text As String) As String

Dim result As String
Dim allMatches As Object
Dim RE As Object
Set RE = CreateObject("vbscript.regexp")

RE.pattern = "(sdi \d+)"
RE.Global = True
RE.IgnoreCase = True
Set allMatches = RE.Execute(text)

If allMatches.count <> 0 Then
    result = allMatches.Item(0).submatches.Item(0)
End If

ExtractSDI = result

End Function

If a cell may have more than one SDI number you want to extract, here is my RegexExtract function. You can pass in a third paramter to seperate each match (like comma-seperate them), and you manually enter the pattern in the actual function call:

Ex) =RegexExtract(A1, "(sdi \d+)", ", ")

Here is:

Function RegexExtract(ByVal text As String, _
                      ByVal extract_what As String, _
                      Optional seperator As String = "") As String

Dim i As Long, j As Long
Dim result As String
Dim allMatches As Object
Dim RE As Object
Set RE = CreateObject("vbscript.regexp")

RE.pattern = extract_what
RE.Global = True
Set allMatches = RE.Execute(text)

For i = 0 To allMatches.count - 1
    For j = 0 To allMatches.Item(i).submatches.count - 1
        result = result & seperator & allMatches.Item(i).submatches.Item(j)

If Len(result) <> 0 Then
    result = Right(result, Len(result) - Len(seperator))
End If

RegexExtract = result

End Function

*Please note that I have taken "RE.IgnoreCase = True" out of my RegexExtract, but you could add it back in, or even add it as an optional 4th parameter if you like.

Dropping a connected user from an Oracle 10g database schema

Have you tried ALTER SYSTEM KILL SESSION? Get the SID and SERIAL# from V$SESSION for each session in the given schema, then do


Rollback to last git commit

git reset --hard will force the working directory back to the last commit and delete new/changed files.

.Net: How do I find the .NET version?

Just type the following in the command line:

dir /b /ad /o-n %systemroot%\Microsoft.NET\Framework\v?.*

Your dotnet version will be shown as the highest number.

Zip lists in Python

Source: My Blog Post (better formatting)


numbers = [1,2,3]
letters = 'abcd'

zip(numbers, letters)
# [(1, 'a'), (2, 'b'), (3, 'c')]


Zero or more iterables [1] (ex. list, string, tuple, dictionary)

Output (list)

1st tuple = (element_1 of numbers, element_1 of letters)

2nd tuple = (e_2 numbers, e_2 letters)

n-th tuple = (e_n numbers, e_n letters)

  1. List of n tuples: n is the length of the shortest argument (input)
    • len(numbers) == 3 < len(letters) == 4 ? short= 3 ? return 3 tuples
  2. Length each tuple = # of args (tuple takes an element from each arg)
    • args = (numbers,letters); len(args) == 2 ? tuple with 2 elements
  3. ith tuple = (element_i arg1, element_i arg2…, element_i argn)

Edge Cases

1) Empty String: len(str)= 0 = no tuples

2) Single String: len(str) == 2 tuples with len(args) == 1 element(s)

# []
# []
# [('h',), ('i',)]

Zip in Action!

1. Build a dictionary [2] out of two lists

keys = ["drink","band","food"]
values = ["La Croix", "Daft Punk", "Sushi"]

my_favorite = dict( zip(keys, values) )

# 'La Croix'

my_faves = dict()
for i in range(len(keys)):
    my_faves[keys[i]] = values[i]
  • zip is an elegant, clear, & concise solution

2. Print columns in a table

"*" [3] is called "unpacking": f(*[arg1,arg2,arg3]) == f(arg1, arg2, arg3)

student_grades = [
[   'Morty'  ,  1   ,  "B"  ],
[   'Rick'   ,  4   ,  "A"  ],
[   'Jerry'  ,  3   ,  "M"  ],
[  'Kramer'  ,  0   ,  "F"  ],

row_1 = student_grades[0]
print row_1
# ['Morty', 1, 'B']

columns = zip(*student_grades)
names = columns[0]
print names
# ('Morty', 'Rick', 'Jerry', 'Kramer')

Extra Credit: Unzipping

zip(*args) is called “unzipping” because it has the inverse effect of zip

numbers = (1,2,3)
letters = ('a','b','c')

zipped = zip(numbers, letters)
print zipped
# [(1, 'a'), (2, 'b'), (3, 'c')]

unzipped = zip(*zipped)
print unzipped
# [(1, 2, 3), ('a', 'b', 'c')]
  • unzipped: tuple_1 = e1 of each zipped tuple. tuple_2 = e2 of each zipped


  1. An object capable of returning its members one at a time (ex. list [1,2,3], string 'I like codin', tuple (1,2,3), dictionary {'a':1, 'b':2})
  2. {key1:value1, key2:value2...}
  3. “Unpacking” (*)

* Code:

# foo - function, returns sum of two arguments
def foo(x,y):
    return x + y
print foo(3,4)
# 7

numbers = [1,2]
print foo(numbers)
# TypeError: foo() takes exactly 2 arguments (1 given)

print foo(*numbers)
# 3

* took numbers (1 arg) and “unpacked” its’ 2 elements into 2 args

JavaScript Array to Set

What levi said about passing it into the constructor is correct, but you could also use an object.

I think what Veverke is trying to say is that you could easily use the delete keyword on an object to achieve the same effect.

I think you're confused by the terminology; properties are components of the object that you can use as named indices (if you want to think of it that way).

Try something like this:

var obj = {
    "bob": "dole",
    "mr.": "peabody",
    "darkwing": "duck"

Then, you could just do this:

delete obj["bob"];

The structure of the object would then be this:

    "mr.": "peabody",
    "darkwing": "duck"

Which has the same effect.

How to add List<> to a List<> in

  1. Use Concat or Union extension methods. You have to make sure that you have this direction using System.Linq; in order to use LINQ extensions methods.

  2. Use the AddRange method.

SQL Server 2008: how do I grant privileges to a username?

If you really want them to have ALL rights:

use YourDatabase
exec sp_addrolemember 'db_owner', 'UserName'

Jenkins could not run git

In case the Jenkins is triggering a build by restricting it to run on a slave or any other server (you may find it in the below setting under 'configure')

enter image description here

then the Path to Git executable should be set as per the 'slave_server_hostname' or any other server where the git commands are executed.

Removing carriage return and new-line from the end of a string in c#

If there's always a single CRLF, then:

myString = myString.Substring(0, myString.Length - 2);

If it may or may not have it, then:

Regex re = new Regex("\r\n$");
re.Replace(myString, "");

Both of these (by design), will remove at most a single CRLF. Cache the regex for performance.

MySQL server has gone away - in exactly 60 seconds

I noticed something perhaps relevant.

I had two scripts running, both doing rather slow queries. One of them locked a table and the other had to wait. The one that was waiting had default_socket_timeout = 300. Eventually it quit with "MySQL server has gone away". However, the mysql process list continued to show both query, the slow one still running and the other locked and waiting.

So I don't think mysqld is the culprit. Something has changed in the php mysql client. Quite possibly the default_socket_timeout which I will now set to -1 to see if that changes anything.

store and retrieve a class object in shared preference

Yes .You can store and retrive the object using Sharedpreference

Using a custom typeface in Android

Working for Xamarin.Android:


public class FontsOverride
    public static void SetDefaultFont(Context context, string staticTypefaceFieldName, string fontAssetName)
        Typeface regular = Typeface.CreateFromAsset(context.Assets, fontAssetName);
        ReplaceFont(staticTypefaceFieldName, regular);

    protected static void ReplaceFont(string staticTypefaceFieldName, Typeface newTypeface)
            Field staticField = ((Java.Lang.Object)(newTypeface)).Class.GetDeclaredField(staticTypefaceFieldName);
            staticField.Accessible = true;
            staticField.Set(null, newTypeface);
        catch (Exception e)

Application Implementation:

namespace SomeAndroidApplication
    public class App : Application
        public App()


        public App(IntPtr handle, JniHandleOwnership transfer)
            : base(handle, transfer)


        public override void OnCreate()

            FontsOverride.SetDefaultFont(this, "MONOSPACE", "fonts/Roboto-Light.ttf");


<style name="Theme.Storehouse" parent="Theme.Sherlock">
    <item name="android:typeface">monospace</item>

Style the first <td> column of a table differently

This should help. Its CSS3 :first-child where you should say that the first tr of the table you would like to style.

Can I have onScrollListener for a ScrollView?

    // --------Start Scroll Bar Slide--------
    final HorizontalScrollView xHorizontalScrollViewHeader = (HorizontalScrollView) findViewById(;
    final HorizontalScrollView xHorizontalScrollViewData = (HorizontalScrollView) findViewById(;
    xHorizontalScrollViewData.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
        public void onScrollChanged() {
            int scrollX; int scrollY;
            xHorizontalScrollViewHeader.scrollTo(scrollX, scrollY);
    // ---------End Scroll Bar Slide---------

Check if textbox has empty value

var inp = $("#txt").val();
if(jQuery.trim(inp).length > 0)
   //do something

Removes white space before checking. If the user entered only spaces then this will still work.

Setting WPF image source in code

There's also a simpler way. If the image is loaded as a resource in the XAML, and the code in question is the code-behind for that XAML content:

Uri iconUri = new Uri("pack://application:,,,/ImageNAme.ico", UriKind.RelativeOrAbsolute);
NotifyIcon.Icon = BitmapFrame.Create(iconUri);

How do you specify a byte literal in Java?

If you're passing literals in code, what's stopping you from simply declaring it ahead of time?

byte b = 0; //Set to desired value.

python date of the previous month

datetime and the datetime.timedelta classes are your friend.

  1. find today.
  2. use that to find the first day of this month.
  3. use timedelta to backup a single day, to the last day of the previous month.
  4. print the YYYYMM string you're looking for.

Like this:

 import datetime
 today =
 first = today.replace(day=1)
 lastMonth = first - datetime.timedelta(days=1)

201202 is printed.

Why does git revert complain about a missing -m option?

By default git revert refuses to revert a merge commit as what that actually means is ambiguous. I presume that your HEAD is in fact a merge commit.

If you want to revert the merge commit, you have to specify which parent of the merge you want to consider to be the main trunk, i.e. what you want to revert to.

Often this will be parent number one, for example if you were on master and did git merge unwanted and then decided to revert the merge of unwanted. The first parent would be your pre-merge master branch and the second parent would be the tip of unwanted.

In this case you could do:

git revert -m 1 HEAD

How do I dynamically set the selected option of a drop-down list using jQuery, JavaScript and HTML?

The defaultSelected attribute is not settable, it's just for informational purposes:


The defaultSelected property returns the default value of the selected attribute.
This property returns true if an option is selected by default, otherwise it returns false.

I think you want:

$('option[value=valueToSelect]', newOption).attr('selected', 'selected');

I.e. set the selected attribute of the option you want to select.

Without trying to fix your code, here's roughly how I would do it:

function buildSelect(options, default) {
    // assume options = { value1 : 'Name 1', value2 : 'Name 2', ... }
    //        default = 'value1'

    var $select = $('<select></select>');
    var $option;

    for (var val in options) {
        $option = $('<option value="' + val + '">' + options[val] + '</option>');
        if (val == default) {
            $option.attr('selected', 'selected');

    return $select;

You seem to have a lot of baggage and dependencies already and I can't tell you how to best integrate the selected option into your code without seeing more of it, but hopefully this helps.

Showing an image from console in Python

In Xterm-compatible terminals, you can show the image directly in the terminal. See my answer to "PPM image to ASCII art in Python"

ImageMagick's "logo:" image in Xterm (show picture in new tab for full size viewing)

Deserialize JSON to Array or List with HTTPClient .ReadAsAsync using .NET 4.0 Task pattern

Instead of handcranking your models try using something like the website. Paste In an example JSON response, the fuller the better and then pull in the resultant generated classes. This, at least, takes away some moving parts, will get you the shape of the JSON in csharp giving the serialiser an easier time and you shouldnt have to add attributes.

Just get it working and then make amendments to your class names, to conform to your naming conventions, and add in attributes later.

EDIT: Ok after a little messing around I have successfully deserialised the result into a List of Job (I used to create the class for me)

public class Job
        public string id { get; set; }
        public string position_title { get; set; }
        public string organization_name { get; set; }
        public string rate_interval_code { get; set; }
        public int minimum { get; set; }
        public int maximum { get; set; }
        public string start_date { get; set; }
        public string end_date { get; set; }
        public List<string> locations { get; set; }
        public string url { get; set; }

And an edit to your code:

        List<Job> model = null;
        var client = new HttpClient();
        var task = client.GetAsync("")
          .ContinueWith((taskwithresponse) =>
              var response = taskwithresponse.Result;
              var jsonString = response.Content.ReadAsStringAsync();
              model = JsonConvert.DeserializeObject<List<Job>>(jsonString.Result);


This means you can get rid of your containing object. Its worth noting that this isn't a Task related issue but rather a deserialisation issue.


There is a way to take a JSON object and generate classes in Visual Studio. Simply copy the JSON of choice and then Edit> Paste Special > Paste JSON as Classes. A whole page is devoted to this here:

Error 1046 No database Selected, how to resolve?

If you are doing this through phpMyAdmin:

  • I'm assuming you already Created a new MySQL Database on Live Site (by live site I mean the company your hosting with (in my case Bluehost)).

  • Go to phpMyAdmin on live site - log in to the database you just created.

  • Now IMPORTANT! Before clicking the "import" option on the top bar, select your database on the left side of the page (grey bar, on the top has PHP Myadmin written, below it two options:information_schema and name of database you just logged into.

  • once you click the database you just created/logged into it will show you that database and then click the import option.

That did the trick for me. Really hope that helps

How do I use an image as a submit button?

Use an image type input:

<input type="image" src="/Button1.jpg" border="0" alt="Submit" />

The full HTML:

<form id='formName' name='formName' onsubmit='redirect();return false;'>_x000D_
  <div class="style7">_x000D_
    <input type='text' id='userInput' name='userInput' value=''>_x000D_
    <input type="image" name="submit" src="" border="0" alt="Submit" style="width: 50px;" />_x000D_

How can I add a line to a file in a shell script?

To answer your original question, here's how you do it with sed:

sed -i '1icolumn1, column2, column3' testfile.csv

The "1i" command tells sed to go to line 1 and insert the text there.

The -i option causes the file to be edited "in place" and can also take an optional argument to create a backup file, for example

sed -i~ '1icolumn1, column2, column3' testfile.csv

would keep the original file in "testfile.csv~".

Capture keyboardinterrupt in Python without try-except

If all you want is to not show the traceback, make your code like this:

## all your app logic here
def main():
   ## whatever your app does.

if __name__ == "__main__":
   except KeyboardInterrupt:
      # do nothing here

(Yes, I know that this doesn't directly answer the question, but it's not really clear why needing a try/except block is objectionable -- maybe this makes it less annoying to the OP)

Regular Expression for matching parentheses

For any special characters you should use '\'. So, for matching parentheses - /\(/

How to completely uninstall python 2.7.13 on Ubuntu 16.04

How I do:

# Remove python2
sudo apt purge -y python2.7-minimal

# You already have Python3 but 
# don't care about the version 
sudo ln -s /usr/bin/python3 /usr/bin/python

# Same for pip
sudo apt install -y python3-pip
sudo ln -s /usr/bin/pip3 /usr/bin/pip

# Confirm the new version of Python: 3
python --version

Check If only numeric values were entered in input. (jQuery)

I used this to check if all the text boxes had numeric values:

if(!$.isNumeric($('input:text').val())) {
        alert("All the text boxes must have numeric values!");
        return false;

or for one:


Available with jQuery 1.7.

Correct way to focus an element in Selenium WebDriver using Java

The focus only works if the window is focused.

Use ((JavascriptExecutor)webDriver).executeScript("window.focus();"); to be sure.

npm install Error: rollbackFailedOptional

I tried following options to fix this issue and it worked.

  1. Uninstall Node.js version 8.
  2. Install Node.js version 6.11.4
  3. Use the registry option along with command to install any package.

For example to install express I used following command.

npm install express --registry


npm install express -g --registry

If you want to install locally in any specific folder then use below command. Below command will install express on path C:\Sample\Example1 .

C:\Sample1\Example1> npm install /Sample/Example1 express --registry

Note: If you are installing locally in a specific location then first go to that directory using command and then run above command. If you are not inside that directory and giving only path in command that will not work.

If you get package.json missing error then run below command before installing package locally

C:\Sample\Example1> npm init

above command will create package.json file. No need to provide any data. just hit enter.

Note: If you are behind a firewall then you may need to set a proxy.

Property 'value' does not exist on type 'EventTarget'

Use currentValue instead, as the type of currentValue is EventTarget & HTMLInputElement.

Android Studio: Where is the Compiler Error Output Window?

If you are in android studio 3.1, Verify if file->Project Structure -> Source compatibility is empty. it should not have 1.8 set.

then press ok, the project will sync and error will disappear.

Difference between database and schema

A database is the main container, it contains the data and log files, and all the schemas within it. You always back up a database, it is a discrete unit on its own.

Schemas are like folders within a database, and are mainly used to group logical objects together, which leads to ease of setting permissions by schema.

EDIT for additional question

drop schema test1

Msg 3729, Level 16, State 1, Line 1
Cannot drop schema 'test1' because it is being referenced by object 'copyme'.

You cannot drop a schema when it is in use. You have to first remove all objects from the schema.

Related reading:

  1. What good are SQL Server schemas?
  2. MSDN: User-Schema Separation

Why doesn't have a close method?

The javadoc of the File class describes the class as:

An abstract representation of file and directory pathnames.

File is only a representation of a pathname, with a few methods concerning the filesystem (like exists()) and directory handling but actual streaming input and output is done elsewhere. Streams can be opened and closed, files cannot.

(My personal opinion is that it's rather unfortunate that Sun then went on to create RandomAccessFile, causing much confusion with its inconsistent naming.)

How do I set a path in Visual Studio?

You have a couple of options:

  • You can add the path to the DLLs to the Executable files settings under Tools > Options > Projects and Solutions > VC++ Directories (but only for building, for executing or debugging here)
  • You can add them in your global PATH environment variable
  • You can start Visual Studio using a batch file as I described here and manipulate the path in that one
  • You can copy the DLLs into the executable file's directory :-)

how to get list of port which are in use on the server

TCPView is a Windows program that will show you detailed listings of all TCP and UDP endpoints on your system, including the local and remote addresses and state of TCP connections. On Windows Server 2008, Vista, NT, 2000 and XP TCPView also reports the name of the process that owns the endpoint. TCPView provides a more informative and conveniently presented subset of the Netstat program that ships with Windows. The TCPView download includes Tcpvcon, a command-line version with the same functionality.

std::string to char*

Assuming you just need a C-style string to pass as input:

std::string str = "string";
const char* chr = str.c_str();

org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class

I got the same error and the cause was the directory:


was corrupted(directory or file not readable or damaged).. solved with

  • renaming the directory WEB-INF\classes as WEB-INF\classes_old
  • Eclipse's Project menu--> Clean (to recreate directories)
  • redeploy --> restart server.

Find and replace in file and overwrite file doesn't work, it empties the file

Warning: this is a dangerous method! It abuses the i/o buffers in linux and with specific options of buffering it manages to work on small files. It is an interesting curiosity. But don't use it for a real situation!

Besides the -i option of sed you can use the tee utility.

From man:

tee - read from standard input and write to standard output and files

So, the solution would be:

sed s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html | tee | tee index.html

-- here the tee is repeated to make sure that the pipeline is buffered. Then all commands in the pipeline are blocked until they get some input to work on. Each command in the pipeline starts when the upstream commands have written 1 buffer of bytes (the size is defined somewhere) to the input of the command. So the last command tee index.html, which opens the file for writing and therefore empties it, runs after the upstream pipeline has finished and the output is in the buffer within the pipeline.

Most likely the following won't work:

sed s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html | tee index.html

-- it will run both commands of the pipeline at the same time without any blocking. (Without blocking the pipeline should pass the bytes line by line instead of buffer by buffer. Same as when you run cat | sed s/bar/GGG/. Without blocking it's more interactive and usually pipelines of just 2 commands run without buffering and blocking. Longer pipelines are buffered.) The tee index.html will open the file for writing and it will be emptied. However, if you turn the buffering always on, the second version will work too.

Allow anonymous authentication for a single folder in web.config?

I added web.config to the specific folder say "Users" (VS 2015, C#) and the added following code

<?xml version="1.0"?>
    <deny users="?"/>

Initially i used location tag but that didn't worked.

Set div height equal to screen size

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

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

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

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

CSS background-image - What is the correct usage?

1) putting quotes is a good habit

2) it can be relative path for example:

background-image: url('images/slides/background.jpg');

will look for images folder in the folder from which css is loaded. So if images are in another folder or out of the CSS folder tree you should use absolute path or relative to the root path (starting with /)

3) you should use complete declaration for background-image to make it behave consistently across standards compliant browsers like:

background:blue url('/images/clouds.jpg') no-repeat scroll left center;

Git status shows files as changed even though contents are the same

I recently moved my local repo from one Windows x64 system to another. The first time I use it half my files appear to be changed. Thanks to Jacek Szybisz for sending me to Configuring Git to handle line endings where I found the following one-liner that removed all the no-change files from Gitkraken's change queue:

git config --global core.autocrlf true

How to write to an existing excel file without overwriting data (using pandas)?

Old question, but I am guessing some people still search for this - so...

I find this method nice because all worksheets are loaded into a dictionary of sheet name and dataframe pairs, created by pandas with the sheetname=None option. It is simple to add, delete or modify worksheets between reading the spreadsheet into the dict format and writing it back from the dict. For me the xlsxwriter works better than openpyxl for this particular task in terms of speed and format.

Note: future versions of pandas (0.21.0+) will change the "sheetname" parameter to "sheet_name".

# read a single or multi-sheet excel file
# (returns dict of sheetname(s), dataframe(s))
ws_dict = pd.read_excel(excel_file_path,

# all worksheets are accessible as dataframes.

# easy to change a worksheet as a dataframe:
mod_df = ws_dict['existing_worksheet']

# do work on mod_df...then reassign
ws_dict['existing_worksheet'] = mod_df

# add a dataframe to the workbook as a new worksheet with
# ws name, df as dict key, value:
ws_dict['new_worksheet'] = some_other_dataframe

# when done, write dictionary back to excel...
# xlsxwriter honors datetime and date formats
# (only included as example)...
with pd.ExcelWriter(excel_file_path,
                    date_format='yyyy-mm-dd') as writer:

    for ws_name, df_sheet in ws_dict.items():
        df_sheet.to_excel(writer, sheet_name=ws_name)

For the example in the 2013 question:

ws_dict = pd.read_excel('Masterfile.xlsx',

ws_dict['Main'] = data_filtered[['Diff1', 'Diff2']]

with pd.ExcelWriter('Masterfile.xlsx',
                    engine='xlsxwriter') as writer:

    for ws_name, df_sheet in ws_dict.items():
        df_sheet.to_excel(writer, sheet_name=ws_name)

Finding length of char array

sizeof returns the size of the type of the variable in bytes. So in your case it's returning the size of your char[7] which is 7 * sizeof(char). Since sizeof(char) = 1, the result is 7.

Expanding this to another example:

int intArr[5];
printf("sizeof(intArr)=%u", sizeof(intArr));

would yield 5 * sizeof(int), so you'd get the result "20" (At least on a regular 32bit platform. On others sizeof(int) might differ)

To return to your problem:

It seems like, that what you want to know is the length of the string which is contained inside your array and not the total array size.

By definition C-Strings have to be terminated with a trailing '\0' (0-Byte). So to get the appropriate length of the string contained within your array, you have to first terminate the string, so that you can tell when it's finished. Otherwise there would be now way to know.

All standard functions build upon this definition, so if you call strlen to retrieve the str ing len gth, it will iterate through the given array until it finds the first 0-byte, which in your case would be the very first element.

Another thing you might need to know that only because you don't fill the remaining elements of your char[7] with a value, they actually do contain random undefined values.

Hope that helped.

FromBody string parameter is giving null

When having [FromBody]attribute, the string sent should not be a raw string, but rather a JSON string as it includes the wrapping quotes:


Based on

Similar answer string value is Empty when using FromBody in web api


Get current language in CultureInfo

Current system language is retrieved using :


"Gets the CultureInfo that represents the culture installed with the operating system."


To set it as default language for thread use :


How to use registerReceiver method?

Broadcast receivers receive events of a certain type. I don't think you can invoke them by class name.

First, your IntentFilter must contain an event.

static final String SOME_ACTION = "com.yourcompany.yourapp.SOME_ACTION";
IntentFilter intentFilter = new IntentFilter(SOME_ACTION);

Second, when you send a broadcast, use this same action:

Intent i = new Intent(SOME_ACTION);

Third, do you really need MyIntentService to be inline? Static? [EDIT] I discovered that MyIntentSerivce MUST be static if it is inline.

Fourth, is your service declared in the AndroidManifest.xml?

MySQL - Replace Character in Columns

maybe I'd go by this.

 SQL = SELECT REPLACE(myColumn, '""', '\'') FROM myTable

I used singlequotes because that's the one that registers string expressions in MySQL, or so I believe.

Hope that helps.

Could not create SSL/TLS secure channel, despite setting ServerCertificateValidationCallback

If you are using a new domain name, and you have done all the above and you are still getting the same error, check to see if you clear the DNS cache on your PC. Clear your DNS for more details.

Windows® 8

To clear your DNS cache if you use Windows 8, perform the following steps:

On your keyboard, press Win+X to open the WinX Menu.

Right-click Command Prompt and select Run as Administrator.

Run the following command:

ipconfig /flushdns

If the command succeeds, the system returns the following message:

Windows IP configuration successfully flushed the DNS Resolver Cache.

Windows® 7

To clear your DNS cache if you use Windows 7, perform the following steps:

Click Start.

Enter cmd in the Start menu search text box.

Right-click Command Prompt and select Run as Administrator.

Run the following command:

ipconfig /flushdns

If the command succeeds, the system returns the following message: Windows IP configuration successfully flushed the DNS Resolver Cache.

How to use wget in php?

lots of methods available in php to read a file like exec, file_get_contents, curl and fopen but it depend on your requirement and file permission

Visit this file_get_contents vs cUrl

Basically file_get_contents for for you

$data = file_get_contents($file_url);

Bundling data files with PyInstaller (--onefile)

Perhaps i missed a step or did something wrong but the methods which are above, didn't bundle data files with PyInstaller into one exe file. Let me share the steps what i have done.

  1. step:Write one of the above methods into your py file with importing sys and os modules. I tried both of them. The last one is:

    def resource_path(relative_path):
    """ Get absolute path to resource, works for dev and for PyInstaller """
        base_path = getattr(sys, '_MEIPASS', os.path.dirname(os.path.abspath(__file__)))
        return os.path.join(base_path, relative_path)
  2. step: Write, pyi-makespec, to the console, to create a file.spec file.

  3. step: Open, file.spec with Notepad++ to add the data files like below:

    a = Analysis(['C:\\Users\\TCK\\Desktop\\Projeler\\'],
    #Add the file like the below example
    a.datas += [('Converter-GUI.ico', 'C:\\Users\\TCK\\Desktop\\Projeler\\Converter-GUI.ico', 'DATA')]
    pyz = PYZ(a.pure, a.zipped_data,
    exe = EXE(pyz,
              #Turn the console option False if you don't want to see the console while executing the program.
              #Add an icon to the program.
    coll = COLLECT(exe,
  4. step: I followed the above steps, then saved the spec file. At last opened the console and write, pyinstaller file.spec (in my case, file=Converter-GUI).

Conclusion: There's still more than one file in the dist folder.

Note: I'm using Python 3.5.

EDIT: Finally it works with Jonathan Reinhart's method.

  1. step: Add the below codes to your python file with importing sys and os.

    def resource_path(relative_path):
    """ Get absolute path to resource, works for dev and for PyInstaller """
        base_path = getattr(sys, '_MEIPASS', os.path.dirname(os.path.abspath(__file__)))
        return os.path.join(base_path, relative_path)
  2. step: Call the above function with adding the path of your file:

    image_path = resource_path("Converter-GUI.ico")
  3. step: Write the above variable that call the function to where your codes need the path. In my case it's:

  4. step: Open the console in the same directory of your python file, write the codes like below:

        pyinstaller --onefile
  5. step: Open the .spec file of the python file and append the a.datas array and add the icon to the exe class, which was given above before the edit in 3'rd step.
  6. step: Save and exit the path file. Go to your folder which include the spec and py file. Open again the console window and type the below command:

        pyinstaller your_file.spec

After the 6. step your one file is ready to use.

How to check if element exists using a lambda expression?

The above answers require you to malloc a new stream object.

public <T>
boolean containsByLambda(Collection<? extends T> c, Predicate<? super T> p) {

    for (final T z : c) {
        if (p.test(z)) {
            return true;
    return false;

public boolean containsTabById(TabPane tabPane, String id) {
    return containsByLambda(tabPane.getTabs(), z -> z.getId().equals(id));
if (containsTabById(tabPane, idToCheck))) {

IE Enable/Disable Proxy Settings via Registry

modifying the proxy value under

[HKEY_USERS\<your SID>\Software\Microsoft\Windows\CurrentVersion\Internet Settings]

doesnt need to restart ie

What is is a Python file like any other. It can take any name, except by convention it is named so that there is not a different procedure with each script.

Most frequently is used to install a Python module but server other purposes:


Perhaps this is most famous usage of is in modules. Although they can be installed using pip, old Python versions did not include pip by default and they needed to be installed separately.

If you wanted to install a module but did not want to install pip, just about the only alternative was to install the module from file. This could be achieved via python install. This would install the Python module to the root dictionary (without pip, easy_install ect).

This method is often used when pip will fail. For example if the correct Python version of the desired package is not available via pipperhaps because it is no longer maintained, , downloading the source and running python install would perform the same thing, except in the case of compiled binaries are required, (but will disregard the Python version -unless an error is returned).

Another use of is to install a package from source. If a module is still under development the wheel files will not be available and the only way to install is to install from the source directly.

Building Python extensions:

When a module has been built it can be converted into module ready for distribution using a distutils setup script. Once built these can be installed using the command above.

A setup script is easy to build and once the file has been properly configured and can be compiled by running python build (see link for all commands).

Once again it is named for ease of use and by convention, but can take any name.


Another famous use of files include compiled extensions. These require a setup script with user defined values. They allow fast (but once compiled are platform dependant) execution. Here is a simple example from the documentation:

from distutils.core import setup
from Cython.Build import cythonize

    name = 'Hello world app',
    ext_modules = cythonize("hello.pyx"),

This can be compiled via python build


Another module requiring a setup script is cx_Freeze. This converts Python script to executables. This allows many commands such as descriptions, names, icons, packages to include, exclude ect and once run will produce a distributable application. An example from the documentation:

import sys
from cx_Freeze import setup, Executable
build_exe_options = {"packages": ["os"], "excludes": ["tkinter"]} 

base = None
if sys.platform == "win32":
    base = "Win32GUI"

setup(  name = "guifoo",
        version = "0.1",
        description = "My GUI application!",
        options = {"build_exe": build_exe_options},
        executables = [Executable("", base=base)])

This can be compiled via python build.

So what is a file?

Quite simply it is a script that builds or configures something in the Python environment.

A package when distributed should contain only one setup script but it is not uncommon to combine several together into a single setup script. Notice this often involves distutils but not always (as I showed in my last example). The thing to remember it just configures Python package/script in some way.

It takes the name so the same command can always be used when building or installing.

What is the best way to delete a component with CLI

This is not supported by Angular CLI and they are in no mood to include it any time soon.

Here is the link to the actual created issue -

And a screenshot of the solution from the officials - enter image description here

How to display all elements in an arraylist?

Set for each loop to get all values

for (String member : members){
    Log.i("Member name: ", member);

Sort objects in ArrayList by date?

This may be an old response but I used some examples from this post to create a comparator that would sort an ArrayList of HashMap<String, String> by one object in the list, that being the timestamp.

I have these objects:

ArrayList<Map<String, String>> alList = new ArrayList<Map<String, String>>();

The map objects are as follows:

Map<String, Object> map = new HashMap<>();
        // of course this is the actual formatted date below in the timestamp
        map.put("timestamp", "MM/dd/yyyy HH:mm:ss"); 
        map.put("item1", "my text goes here");
        map.put("item2", "my text goes here");

That mapping is what I use to load all my objects into the array list, using the alList.add(map) function, within a loop.

Now, I created my own comparator:

import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

 public class DateSorter implements Comparator {
     public int compare(Object firstObjToCompare, Object secondObjToCompare) {
    String firstDateString = ((HashMap<String, String>) firstObjToCompare).get("timestamp");
    String secondDateString = ((HashMap<String, String>) secondObjToCompare).get("timestamp");

    if (secondDateString == null || firstDateString == null) {
        return 0;

    // Convert to Dates
    DateTimeFormatter dtf = DateTimeFormat.forPattern("MM/dd/yyyy HH:mm:ss");
    DateTime firstDate = dtf.parseDateTime(firstDateString);
    DateTime secondDate = dtf.parseDateTime(secondDateString);

    if (firstDate.isAfter(secondDate)) return -1;
    else if (firstDate.isBefore(secondDate)) return 1;
    else return 0;

I can now just call the Comparator at any time on the array and it will sort my array, giving me the Latest timestamp in position 0 (top of the list) and the earliest timestamp at the end of the list. New posts get put to the top basically.

Collections.sort(alList, new DateSorter());

This may help someone out, which is why I posted it. Take into consideration the return statements within the compare() function. There are 3 types of results. Returning 0 if they are equal, returning >0 if the first date is before the second date and returning <0 if the first date is after the second date. If you want your list to be reversed, then just switch those two return statements! Simple =]

Add URL link in CSS Background Image?

Try wrapping the spans in an anchor tag and apply the background image to that.


<div class="header">
    <a href="/">
        <span class="header-title">My gray sea design</span><br />
        <span class="header-title-two">A beautiful design</span>


.header {
    border-bottom:1px solid #eaeaea;

.header a {
    display: block;
    background-image: url("./images/embouchure.jpg");
    background-repeat: no-repeat;
    color: #eaeaea;

jquery: $(window).scrollTop() but no $(window).scrollBottom()

// Back to bottom button
$(window).scroll(function () {
    var scrollBottom = $(this).scrollTop() + $(this).height();
    var scrollTop = $(this).scrollTop();
    var pageHeight = $('html, body').height();//Fixed

    if ($(this).scrollTop() > pageHeight - 700) {
    } else {
        if ($(this).scrollTop() < 100) {
        else {
$('.back-to-bottom').click(function () {
    var pageHeight = $('html, body').height();//Fixed
    $('html, body').animate({ scrollTop: pageHeight }, 1500, 'easeInOutExpo');
    return false;

How to increase icons size on Android Home Screen?

If you want to change settings in the launcher, change icon size, or grid size just hold down on an empty part of your home screen. Tap the three Dots and there you go.


When configuring the phone for first time I saw something about a grid somewhere, but couldn't find it again. Luckily I found the answer on the link above.

How to open a web page automatically in full screen mode

window.onload = function() {
    var el = document.documentElement,
        rfs = el.requestFullScreen
        || el.webkitRequestFullScreen
        || el.mozRequestFullScreen;;

ERROR Source option 1.5 is no longer supported. Use 1.6 or later

Make sure you have following configuration in your pom.xml file.


Inserting created_at data with Laravel

In my case, I wanted to unit test that users weren't able to verify their email addresses after 1 hour had passed, so I didn't want to do any of the other answers since they would also persist when not unit testing, so I ended up just manually updating the row after insert:

// Create new user
$user = factory(User::class)->create();

// Add an email verification token to the 
// email_verification_tokens table
$token = $user->generateNewEmailVerificationToken();

// Get the time 61 minutes ago
$created_at = (new Carbon())->subMinutes(61);

// Do the update
    'UPDATE email_verification_tokens SET created_at = ?',

Note: For anything other than unit testing, I would look at the other answers here.

Facebook Open Graph not clearing cache

The most voted question is quite outdated:

These are the only 2 options that should be used as of November 2014:

For non developers

  1. Use the FB Debugger:
  2. Paste the url you want to recache. (Make sure you use the same url included on your og:url tag)
  3. Click the Fetch Scrape information again Button

For Developers

  1. Make a GET call programmatically to this URL:[YOUR_URL_HERE]&scrape=true (see:
  2. Make sure the og:url tag included on the head on that page matches with the one you are passing.
  3. you can even parse the json response to get the number of shares of that URL.

Additional Info About Updating Images

  • If the og:image URL remains the same but the image has actually changed it won't be updated nor recached by Facebook scrapers even doing the above. (even passing a ?last_update=[TIMESTAMP] at the end of the image url didn't work for me).
  • The only effective workaround for me has been to assign a new name to the image.

Note regarding image or video updates on previously posted posts:

  • When you call the debugger to scrap changes on your og:tags of your page, all previous Facebook shares of that URL will still show the old image/video. There is no way to update all previous posts and it's this way by design for security reasons. Otherwise, someone would be able to pretend that a user shared something that he/she actually didn't.

How to use pagination on HTML tables?

Use tr to <tr class="paginate">


<div id="page-nav"></div>


        jQuery(function($) {
            // Grab whatever we need to paginate
            var pageParts = $(".paginate");
            // How many parts do we have?
            var numPages = 100;
            // How many parts do we want per page?
            var perPage = 10;
            // When the document loads we're on page 1
            // So to start with... hide everything else
            // Apply simplePagination to our placeholder
                items: numPages,
                itemsOnPage: perPage,
                cssStyle: "light-theme",
                // We implement the actual pagination
                //   in this next function. It runs on
                //   the event that a user changes page
                onPageClick: function(pageNum) {
                    // Which page parts do we show?
                    var start = perPage * (pageNum - 1);
                    var end = start + perPage;
                    // First hide all page parts
                    // Then show those just for our page
                        .slice(start, end).show();

PHP Pass variable to next page

Sessions would be the only good way, you could also use GET/POST but that would be potentially insecure.

Disabling right click on images using jquery

For Disable Right Click Option

<script type="text/javascript">
    var message="Function Disabled!";

    function clickIE4(){
        if (event.button==2){
            return false;

    function clickNS4(e){
        if (document.layers||document.getElementById&&!document.all){
            if (e.which==2||e.which==3){
                return false;

    if (document.layers){
    else if (document.all&&!document.getElementById){

    document.oncontextmenu=new Function("alert(message);return false")

Passing Arrays to Function in C++

I just wanna add this, when you access the position of the array like


is the same as

*(arg + n) than means an offset of n starting from de arg address.

so arg[0] will be *arg

jQuery - add additional parameters on submit (NOT ajax)

You could write a jQuery function which allowed you to add hidden fields to a form:

// This must be applied to a form (or an object inside a form).
jQuery.fn.addHidden = function (name, value) {
    return this.each(function () {
        var input = $("<input>").attr("type", "hidden").attr("name", name).val(value);

And then add the hidden field before you submit:

var frm = $("#form").addHidden('SaveAndReturn', 'Save and Return')

How to generate unique id in MySQL?

If you use MySQL with version higher than 5.7.4, you can use the newly added RANDOM_BYTES function:


This will result in a random string such as GgwEvafNLWQ3+ockEST00A==.

Turn off enclosing <p> tags in CKEditor 3.0

Set such config:

    CKEDITOR.config.enterMode = CKEDITOR.ENTER_BR
    CKEDITOR.config.forcePasteAsPlainText = true Need Text Box to Only Accept Numbers

I know it's old.. I'll just leave this code here for the sake of convenience.

Integer only:

Public Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
   With TextBox1
      If IsNumeric(.Text) Then .Text = .Text.Select(Function(x) If(IsNumeric(x), x, "")) : .SelectionStart = .TextLength
   End With
   ' etc..
End Sub

Accepts Double:

Public Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
   With TextBox1
      If IsNumeric(.Text) Then .Text = .Text.Select(Function(x) If(IsNumeric(x) Or x = ".", x, "")) : .SelectionStart = .TextLength
   End With
   ' etc..
End Sub

Accepts basic operations + - * /, parentheses ( ) [ ] { } and Double:

Public Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
   With TextBox1
      If IsNumeric(.Text) Then .Text = .Text.Select(Function(x) If(IsNumeric(x) Or ".+-*/()[]{}".Contains(x), x, "")) : .SelectionStart = .TextLength
   End With
   ' etc..
End Sub

How do I stretch an image to fit the whole background (100% height x 100% width) in Flutter?

This worked for me

class _SplashScreenState extends State<SplashScreen> {
  Widget build(BuildContext context) {
    return Container(
      child: FittedBox(
        child: Image.asset("images/my_image.png"),
        fit: BoxFit.fill,

Check if a time is between two times (time DataType)

Should be AND instead of OR

select *
from MyTable
where CAST(Created as time) >= '23:00:00' 
   AND CAST(Created as time) < '07:00:00'

Tomcat 8 throwing - org.apache.catalina.webresources.Cache.getResource Unable to add the resource

You have more static resources that the cache has room for. You can do one of the following:

  • Increase the size of the cache
  • Decrease the TTL for the cache
  • Disable caching

For more details see the documentation for these configuration options.

Format cell if cell contains date less than today


Returns true for dates up to and including today, false otherwise.

Link to reload current page


<a href="page1.html"> Link </a>

*page1.html -> type the name of the file you are working on (your current HTML file)

Regular expression for matching latitude/longitude coordinates?


Latitude: result = re.match("^[+-]?((90\.?0*$)|(([0-8]?[0-9])\.?[0-9]*$))", '-90.00001')

Longitude: result = re.match("^[+-]?((180\.?0*$)|(((1[0-7][0-9])|([0-9]{0,2}))\.?[0-9]*$))", '-0.0000')

Latitude should fail in the example.

Find out the history of SQL queries

    select v.SQL_TEXT,
      from v$sql v
where to_date(v.FIRST_LOAD_TIME,'YYYY-MM-DD hh24:mi:ss')>ADD_MONTHS(trunc(sysdate,'MM'),-2)

where clause is optional. You can sort the results according to FIRST_LOAD_TIME and find the records up to 2 months ago.

How to place Text and an Image next to each other in HTML?

You want to use css float for this, you can put it directly in your code.

<img src="website_art.png" height= "75" width="235" style="float:left;"/>
<h3 style="float:right;">The Art of Gaming</h3>

But I would really suggest learning the basics of css and splitting all your styling out to a separate style sheet, and use classes. It will help you in the future. A good place to start is w3schools or, perhaps later down the path, Mozzila Dev. Network (MDN).


  <img src="website_art.png" class="myImage"/>
  <h3 class="heading">The Art of Gaming</h3>


.myImage {
  float: left;
  height: 75px;
  width: 235px;
  font-family: Veranda;
.heading {

IllegalStateException: Can not perform this action after onSaveInstanceState with ViewPager

Here is a different solution to this problem.

Using a private member variable you are able to set the returned data as an intent that can then be processed after super.onResume();

Like so:

private Intent mOnActivityResultIntent = null; 

protected void onResume() {
    if(mOnActivityResultIntent != null){
        ... do things ...
        mOnActivityResultIntent = null;

public void onActivityResult(int requestCode, int resultCode, Intent data){
    if(data != null){
        mOnActivityResultIntent = data;

Is there any kind of hash code function in JavaScript?

If you want to use objects as keys you need to overwrite their toString Method, as some already mentioned here. The hash functions that were used are all fine, but they only work for the same objects not for equal objects.

I've written a small library that creates hashes from objects, which you can easily use for this purpose. The objects can even have a different order, the hashes will be the same. Internally you can use different types for your hash (djb2, md5, sha1, sha256, sha512, ripemd160).

Here is a small example from the documentation:

var hash = require('es-hash');

// Save data in an object with an object as a key
Object.prototype.toString = function () {
    return '[object Object #'+hash(this)+']';

var foo = {};

foo[{bar: 'foo'}] = 'foo';

 * Output:
 *  foo
 *  undefined
console.log(foo[{bar: 'foo'}]);

The package can be used either in browser and in Node-Js.


Are dictionaries ordered in Python 3.6+?

Are dictionaries ordered in Python 3.6+?

They are insertion ordered[1]. As of Python 3.6, for the CPython implementation of Python, dictionaries remember the order of items inserted. This is considered an implementation detail in Python 3.6; you need to use OrderedDict if you want insertion ordering that's guaranteed across other implementations of Python (and other ordered behavior[1]).

As of Python 3.7, this is no longer an implementation detail and instead becomes a language feature. From a python-dev message by GvR:

Make it so. "Dict keeps insertion order" is the ruling. Thanks!

This simply means that you can depend on it. Other implementations of Python must also offer an insertion ordered dictionary if they wish to be a conforming implementation of Python 3.7.

How does the Python 3.6 dictionary implementation perform better[2] than the older one while preserving element order?

Essentially, by keeping two arrays.

  • The first array, dk_entries, holds the entries (of type PyDictKeyEntry) for the dictionary in the order that they were inserted. Preserving order is achieved by this being an append only array where new items are always inserted at the end (insertion order).

  • The second, dk_indices, holds the indices for the dk_entries array (that is, values that indicate the position of the corresponding entry in dk_entries). This array acts as the hash table. When a key is hashed it leads to one of the indices stored in dk_indices and the corresponding entry is fetched by indexing dk_entries. Since only indices are kept, the type of this array depends on the overall size of the dictionary (ranging from type int8_t(1 byte) to int32_t/int64_t (4/8 bytes) on 32/64 bit builds)

In the previous implementation, a sparse array of type PyDictKeyEntry and size dk_size had to be allocated; unfortunately, it also resulted in a lot of empty space since that array was not allowed to be more than 2/3 * dk_size full for performance reasons. (and the empty space still had PyDictKeyEntry size!).

This is not the case now since only the required entries are stored (those that have been inserted) and a sparse array of type intX_t (X depending on dict size) 2/3 * dk_sizes full is kept. The empty space changed from type PyDictKeyEntry to intX_t.

So, obviously, creating a sparse array of type PyDictKeyEntry is much more memory demanding than a sparse array for storing ints.

You can see the full conversation on Python-Dev regarding this feature if interested, it is a good read.

In the original proposal made by Raymond Hettinger, a visualization of the data structures used can be seen which captures the gist of the idea.

For example, the dictionary:

d = {'timmy': 'red', 'barry': 'green', 'guido': 'blue'}

is currently stored as [keyhash, key, value]:

entries = [['--', '--', '--'],
           [-8522787127447073495, 'barry', 'green'],
           ['--', '--', '--'],
           ['--', '--', '--'],
           ['--', '--', '--'],
           [-9092791511155847987, 'timmy', 'red'],
           ['--', '--', '--'],
           [-6480567542315338377, 'guido', 'blue']]

Instead, the data should be organized as follows:

indices =  [None, 1, None, None, None, 0, None, 2]
entries =  [[-9092791511155847987, 'timmy', 'red'],
            [-8522787127447073495, 'barry', 'green'],
            [-6480567542315338377, 'guido', 'blue']]

As you can visually now see, in the original proposal, a lot of space is essentially empty to reduce collisions and make look-ups faster. With the new approach, you reduce the memory required by moving the sparseness where it's really required, in the indices.

[1]: I say "insertion ordered" and not "ordered" since, with the existence of OrderedDict, "ordered" suggests further behavior that the dict object doesn't provide. OrderedDicts are reversible, provide order sensitive methods and, mainly, provide an order-sensive equality tests (==, !=). dicts currently don't offer any of those behaviors/methods.

[2]: The new dictionary implementations performs better memory wise by being designed more compactly; that's the main benefit here. Speed wise, the difference isn't so drastic, there's places where the new dict might introduce slight regressions (key-lookups, for example) while in others (iteration and resizing come to mind) a performance boost should be present.

Overall, the performance of the dictionary, especially in real-life situations, improves due to the compactness introduced.

nano error: Error opening terminal: xterm-256color

  1. edit your .bash_profile file

    vim .bash_profile

  2. commnet

    #export TERM=xterm-256color

  3. add this

    export TERMINFO=/usr/share/terminfo

    export TERM=xterm-basic

    to your .bash_profile

  4. finally


    source .bash_profile

How can I show line numbers in Eclipse?

Go to Windows ? Preferences ? General ? Text Editors ? Show numberlines. Click OK, then Apply changes. Then it will show the line count automatically.

Error: "Input is not proper UTF-8, indicate encoding !" using PHP's simplexml_load_string

If you download XML file and open it for example in Notepad++ you'll see that encoding is set to something else than UTF8 - I'v had the same problem with xml made myself, and it was just te encoding in the editor :)

String <?xml version="1.0" encoding="UTF-8"?> don't set up the encoding of the document, it's only info for validator or another resource.

CodeIgniter: How To Do a Select (Distinct Fieldname) MySQL Query

You can also run ->select('DISTINCT `field`', FALSE) and the second parameter tells CI not to escape the first argument.

With the second parameter as false, the output would be SELECT DISTINCT `field` instead of without the second parameter, SELECT `DISTINCT` `field`

Python: instance has no attribute

Your class doesn't have a __init__(), so by the time it's instantiated, the attribute atoms is not present. You'd have to do C.setdata('something') so C.atoms becomes available.

>>> C = Residues()
>>> C.atoms.append('thing')

Traceback (most recent call last):
  File "<pyshell#84>", line 1, in <module>
AttributeError: Residues instance has no attribute 'atoms'

>>> C.setdata('something')
>>> C.atoms.append('thing')   # now it works

Unlike in languages like Java, where you know at compile time what attributes/member variables an object will have, in Python you can dynamically add attributes at runtime. This also implies instances of the same class can have different attributes.

To ensure you'll always have (unless you mess with it down the line, then it's your own fault) an atoms list you could add a constructor:

def __init__(self):
    self.atoms = []

What does DIM stand for in Visual Basic and BASIC?

Variable declaration. Initially, it was short for "dimension", which is not a term that is used in programming (outside of this specific keyword) to any significant degree.

Is it possible to add an array or object to SharedPreferences on Android

To write,

SharedPreferences prefs = PreferenceManager
JSONArray jsonArray = new JSONArray();
Editor editor = prefs.edit();
editor.putString("key", jsonArray.toString());

To Read,

try {
    JSONArray jsonArray2 = new JSONArray(prefs.getString("key", "[]"));
    for (int i = 0; i < jsonArray2.length(); i++) {
         Log.d("your JSON Array", jsonArray2.getInt(i)+"");
} catch (Exception e) {

Other way to do same:

//Retrieve the values
Gson gson = new Gson();
String jsonText = Prefs.getString("key", null);
String[] text = gson.fromJson(jsonText, String[].class);  //EDIT: gso to gson

//Set the values
Gson gson = new Gson();
List<String> textList = new ArrayList<String>(data);
String jsonText = gson.toJson(textList);
prefsEditor.putString("key", jsonText);

Using GSON in Java:

public void saveArrayList(ArrayList<String> list, String key){
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(activity);
    SharedPreferences.Editor editor = prefs.edit();
    Gson gson = new Gson();
    String json = gson.toJson(list);
    editor.putString(key, json);


public ArrayList<String> getArrayList(String key){
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(activity);
    Gson gson = new Gson();
    String json = prefs.getString(key, null);
    Type type = new TypeToken<ArrayList<String>>() {}.getType();
    return gson.fromJson(json, type);

Using GSON in Kotlin

fun saveArrayList(list: java.util.ArrayList<String?>?, key: String?) {
    val prefs: SharedPreferences = PreferenceManager.getDefaultSharedPreferences(activity)
    val editor: Editor = prefs.edit()
    val gson = Gson()
    val json: String = gson.toJson(list)
    editor.putString(key, json)

fun getArrayList(key: String?): java.util.ArrayList<String?>? {
    val prefs: SharedPreferences = PreferenceManager.getDefaultSharedPreferences(activity)
    val gson = Gson()
    val json: String = prefs.getString(key, null)
    val type: Type = object : TypeToken<java.util.ArrayList<String?>?>() {}.getType()
    return gson.fromJson(json, type)

jQuery Ajax File Upload

If you want to upload file using AJAX here is code which you can use for file uploading.

$(document).ready(function() {
    var options = { 
                beforeSubmit:  showRequest,
        success:       showResponse,
        dataType: 'json' 
    $('body').delegate('#image','change', function(){
function showRequest(formData, jqForm, options) { 
    return true; 
function showResponse(response, statusText, xhr, $form)  { 
    if(response.success == false)
        var arr = response.errors;
        $.each(arr, function(index, value)
            if (value.length != 0)
                $("#validation-errors").append('<div class="alert alert-error"><strong>'+ value +'</strong><div>');
    } else {
         $("#output").html("<img src='"+response.file+"' />");

Here is the HTML for Upload the file

<form class="form-horizontal" id="upload" enctype="multipart/form-data" method="post" action="upload/image'" autocomplete="off">
    <input type="file" name="image" id="image" /> 

Swift 2: Call can throw, but it is not marked with 'try' and the error is not handled

When calling a function that is declared with throws in Swift, you must annotate the function call site with try or try!. For example, given a throwing function:

func willOnlyThrowIfTrue(value: Bool) throws {
  if value { throw someError }

this function can be called like:

func foo(value: Bool) throws {
  try willOnlyThrowIfTrue(value)

Here we annotate the call with try, which calls out to the reader that this function may throw an exception, and any following lines of code might not be executed. We also have to annotate this function with throws, because this function could throw an exception (i.e., when willOnlyThrowIfTrue() throws, then foo will automatically rethrow the exception upwards.

If you want to call a function that is declared as possibly throwing, but which you know will not throw in your case because you're giving it correct input, you can use try!.

func bar() {
  try! willOnlyThrowIfTrue(false)

This way, when you guarantee that code won't throw, you don't have to put in extra boilerplate code to disable exception propagation.

try! is enforced at runtime: if you use try! and the function does end up throwing, then your program's execution will be terminated with a runtime error.

Most exception handling code should look like the above: either you simply propagate exceptions upward when they occur, or you set up conditions such that otherwise possible exceptions are ruled out. Any clean up of other resources in your code should occur via object destruction (i.e. deinit()), or sometimes via defered code.

func baz(value: Bool) throws {

  var filePath = NSBundle.mainBundle().pathForResource("theFile", ofType:"txt")
  var data = NSData(contentsOfFile:filePath)

  try willOnlyThrowIfTrue(value)

  // data and filePath automatically cleaned up, even when an exception occurs.

If for whatever reason you have clean up code that needs to run but isn't in a deinit() function, you can use defer.

func qux(value: Bool) throws {
  defer {
    print("this code runs when the function exits, even when it exits by an exception")

  try willOnlyThrowIfTrue(value)

Most code that deals with exceptions simply has them propagate upward to callers, doing cleanup on the way via deinit() or defer. This is because most code doesn't know what to do with errors; it knows what went wrong, but it doesn't have enough information about what some higher level code is trying to do in order to know what to do about the error. It doesn't know if presenting a dialog to the user is appropriate, or if it should retry, or if something else is appropriate.

Higher level code, however, should know exactly what to do in the event of any error. So exceptions allow specific errors to bubble up from where they initially occur to the where they can be handled.

Handling exceptions is done via catch statements.

func quux(value: Bool) {
  do {
    try willOnlyThrowIfTrue(value)
  } catch {
    // handle error

You can have multiple catch statements, each catching a different kind of exception.

  do {
    try someFunctionThatThowsDifferentExceptions()
  } catch MyErrorType.errorA {
    // handle errorA
  } catch MyErrorType.errorB {
    // handle errorB
  } catch {
    // handle other errors

For more details on best practices with exceptions, see It's specifically aimed at C++, but after examining the Swift exception model, I believe the basics apply to Swift as well.

For details on the Swift syntax and error handling model, see the book The Swift Programming Language (Swift 2 Prerelease).

Using Enum values as String literals

You can't. I think you have FOUR options here. All four offer a solution but with a slightly different approach...

Option One: use the built-in name() on an enum. This is perfectly fine if you don't need any special naming format.

    String name =; // Returns the name of this enum constant, exactly as declared in its enum declaration.

Option Two: add overriding properties to your enums if you want more control

public enum Modes {
    mode1 ("Fancy Mode 1"),
    mode2 ("Fancy Mode 2"),
    mode3 ("Fancy Mode 3");

    private final String name;       

    private Modes(String s) {
        name = s;

    public boolean equalsName(String otherName) {
        // (otherName == null) check is not needed because name.equals(null) returns false 
        return name.equals(otherName);

    public String toString() {

Option Three: use static finals instead of enums:

public final class Modes {

    public static final String MODE_1 = "Fancy Mode 1";
    public static final String MODE_2 = "Fancy Mode 2";
    public static final String MODE_3 = "Fancy Mode 3";

    private Modes() { }

Option Four: interfaces have every field public, static and final:

public interface Modes {

    String MODE_1 = "Fancy Mode 1";
    String MODE_2 = "Fancy Mode 2";
    String MODE_3 = "Fancy Mode 3";  

jQuery - Appending a div to body, the body is the object?

Instead use use appendTo. append or appendTo returns a jQuery object so you don't have to wrap it inside $().

var holdyDiv = $('<div />').appendTo('body');
holdyDiv.attr('id', 'holdy');

.appendTo() reference:

Alernatively you can try this also.

$('<div />', { id: 'holdy' }).appendTo('body');
             (Here you can specify any attribute/value pair you want)

How do you display code snippets in MS Word preserving format and syntax highlighting?

Ok, this is weird, but to address the background color issue I paste in the text as normal, select the whole block, click on the highlighter tool to highlight (even if the highlight is set to "No Color"), and then I can style the text block without the background color of the text remaining white. I am using VS 11 and Word 2010, but the problem has been around for a long time (see

The entity type <type> is not part of the model for the current context

I was facing the same issue with EntityFrameworkCore trying to update a range of values.

This approach did not work

  _context.Entry(entity).State = EntityState.Modified;
   await _context.SaveChangesAsync().ConfigureAwait(false);

After adding UpdateRange method and removing attach and entry everything work

  await _context.SaveChangesAsync().ConfigureAwait(false);

A valid provisioning profile for this executable was not found for debug mode

One of the solution can be,Your provisioning profile does not include your iPhone's UDID. For that You need to register UDID first and then regenerate provisioning profile from developer account.

What is Func, how and when is it used

Both C# and Java don't have plain functions only member functions (aka methods). And the methods are not first-class citizens. First-class functions allow us to create beautiful and powerful code, as seen in F# or Clojure languages. (For instance, first-class functions can be passed as parameters and can return functions.) Java and C# ameliorate this somewhat with interfaces/delegates.

Func<int, int, int> randInt = (n1, n2) => new Random().Next(n1, n2); 

So, Func is a built-in delegate which brings some functional programming features and helps reduce code verbosity.

where to place CASE WHEN column IS NULL in this query

Try this:

CASE WHEN table3.col3 IS NULL THEN table2.col3 ELSE table3.col3 END as col4

The as col4 should go at the end of the CASE the statement. Also note that you're missing the END too.

Another probably more simple option would be:

IIf([table3.col3] Is Null,[table2.col3],[table3.col3])

Just to clarify, MS Access does not support COALESCE. If it would that would be the best way to go.

Edit after radical question change:

To turn the query into SQL Server then you can use COALESCE (so it was technically answered before too):

SELECT dbo.AdminID.CountryID, dbo.AdminID.CountryName, dbo.AdminID.RegionID, 
dbo.AdminID.[Region name], dbo.AdminID.DistrictID, dbo.AdminID.DistrictName,
dbo.AdminID.ADMIN3_ID, dbo.AdminID.ADMIN3,
COALESCE(dbo.EU_Admin3.EUID, dbo.EU_Admin2.EUID)
FROM dbo.AdminID

BTW, your CASE statement was missing a , before the field. That's why it didn't work.

Formatting a double to two decimal places

string.Format will not change the original value, but it will return a formatted string. For example:

Console.WriteLine("Earnings this week: {0:0.00}", answer);

Note: Console.WriteLine allows inline string formatting. The above is equivalent to:

Console.WriteLine("Earnings this week: " + string.Format("{0:0.00}", answer));

Hash String via SHA-256 in Java

This will work with "org.bouncycastle.util.encoders.Hex" following package

return new String(Hex.encode(digest));

Its in bouncycastle jar.

PHP: How to check if image file exists?

if (file_exists(''.$filename)) {}

This didn't work for me. The way I did it was using getimagesize.

$src = ''.$filename;

if (@getimagesize($src)) {

Note that the '@' will mean that if the image does not exist (in which case the function would usually throw an error: getimagesize( [function.getimagesize]: failed) it will return false.

Regular expression to match exact number of characters?

What you have is correct, but this is more consice:


How to validate an Email in PHP?


var_dump(filter_var('[email protected]', FILTER_VALIDATE_EMAIL));
$validator = new EmailValidator();
$multipleValidations = new MultipleValidationWithAnd([
    new RFCValidation(),
    new DNSCheckValidation()
$validator->isValid("[email protected]", $multipleValidations); //true

How to list all Git tags?

git tag

should be enough. See git tag man page

You also have:

git tag -l <pattern>

List tags with names that match the given pattern (or all if no pattern is given).
Typing "git tag" without arguments, also lists all tags.

More recently ("How to sort git tags?", for Git 2.0+)

git tag --sort=<type>

Sort in a specific order.

Supported type is:

  • "refname" (lexicographic order),
  • "version:refname" or "v:refname" (tag names are treated as versions).

Prepend "-" to reverse sort order.

That lists both:

  • annotated tags: full objects stored in the Git database. They’re checksummed; contain the tagger name, e-mail, and date; have a tagging message; and can be signed and verified with GNU Privacy Guard (GPG).
  • lightweight tags: simple pointer to an existing commit

Note: the git ready article on tagging disapproves of lightweight tag.

Without arguments, git tag creates a “lightweight” tag that is basically a branch that never moves.
Lightweight tags are still useful though, perhaps for marking a known good (or bad) version, or a bunch of commits you may need to use in the future.
Nevertheless, you probably don’t want to push these kinds of tags.

Normally, you want to at least pass the -a option to create an unsigned tag, or sign the tag with your GPG key via the -s or -u options.

That being said, Charles Bailey points out that a 'git tag -m "..."' actually implies a proper (unsigned annotated) tag (option '-a'), and not a lightweight one. So you are good with your initial command.

This differs from:

git show-ref --tags -d

Which lists tags with their commits (see "Git Tag list, display commit sha1 hashes").
Note the -d in order to dereference the annotated tag object (which have their own commit SHA1) and display the actual tagged commit.

Similarly, git show --name-only <aTag> would list the tag and associated commit.

Foreign key referencing a 2 columns primary key in SQL Server

The key is "the order of the column should be the same"


create Table A (
    A_ID char(3) primary key,
    A_name char(10) primary key,
    A_desc desc char(50)

create Table B (
    B_ID char(3) primary key,
    B_A_ID char(3),
    B_A_Name char(10),
    constraint [Fk_B_01] foreign key (B_A_ID,B_A_Name) references A(A_ID,A_Name)

the column order on table A should be --> A_ID then A_Name; defining the foreign key should follow the same order as well.