Programs & Examples On #Editmode

How to get `DOM Element` in Angular 2?

Use ViewChild with #localvariable as shown here,

<textarea  #someVar  id="tasknote"
                  placeholder="{{ notePlaceholder }}"
                  style="background-color: pink"
                  (blur)="updateNote() ; noteEditMode = false " (click)="noteEditMode = false"> {{ todo.note }} 


In component,


import {ElementRef} from '@angular/core';
@ViewChild('someVar') el:ElementRef;



import {ElementRef} from '@angular/core';
@ViewChild('someVar') el:ElementRef;

constructor(private rd: Renderer) {}
ngAfterViewInit() {

Updated on 22/03(March)/2017


Please note from Angular v4.0.0-rc.3 (2017-03-10) few things have been changed. Since Angular team will deprecate invokeElementMethod, above code no longer can be used.


since 4.0 rc.1:

rename RendererV2 to Renderer2
rename RendererTypeV2 to RendererType2
rename RendererFactoryV2 to RendererFactory2

import {ElementRef,Renderer2} from '@angular/core';
@ViewChild('someVar') el:ElementRef;

constructor(private rd: Renderer2) {}

ngAfterViewInit() {
      this.el.nativeElement.focus();      //<<<=====same as oldest way

console.log(this.rd) will give you following methods and you can see now invokeElementMethod is not there. Attaching img as yet it is not documented.

NOTE: You can use following methods of Rendere2 with/without ViewChild variable to do so many things.

enter image description here

Angular2 - Focusing a textbox on component load

Directive for autoFocus first field

import {_x000D_
} from "@angular/core";_x000D_
  selector: "[appFocusFirstEmptyInput]"_x000D_
export class FocusFirstEmptyInputDirective implements AfterViewInit {_x000D_
  constructor(private el: ElementRef) {}_x000D_
  ngAfterViewInit(): void {_x000D_
    const invalidControl = this.el.nativeElement.querySelector(".ng-untouched");_x000D_
    if (invalidControl) {_x000D_

How to Create simple drag and Drop in angularjs

I'm a bit late to the party, but I have my own directive that looks like it'll fit your case (You can adapt it yourself). It's a modification of the ng-repeat directive that's specifically built for list re-ordering via DnD. I built it as I don't like JQuery UI (preference for less libraries than anything else) also I wanted mine to work on touch screens too ;).

Code is here:

Blog post is here:

Display DateTime value in dd/mm/yyyy format in Asp.NET MVC

Since the question was "display" :

@Html.ValueFor(model => model.RegistrationDate, "{0:dd/MM/yyyy}")

What is the best way to conditionally apply attributes in AngularJS?

I am using the following to conditionally set the class attr when ng-class can't be used (for example when styling SVG):

ng-attr-class="{{someBoolean && 'class-when-true' || 'class-when-false' }}"

The same approach should work for other attribute types.

(I think you need to be on latest unstable Angular to use ng-attr-, I'm currently on 1.1.4)

Format datetime in mvc 4

Client validation issues can occur because of MVC bug (even in MVC 5) in jquery.validate.unobtrusive.min.js which does not accept date/datetime format in any way. Unfortunately you have to solve it manually.

My finally working solution:

$(function () {
    $ = function (value, element) {
        return this.optional(element) || moment(value, "DD.MM.YYYY", true).isValid();

You have to include before:


You can install moment.js using:

Install-Package Moment.js

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details

While you are in debug mode within the catch {...} block open up the "QuickWatch" window (ctrl+alt+q) and paste in there:




If you are not in a try/catch or don't have access to the exception object.

This will allow you to drill down into the ValidationErrors tree. It's the easiest way I've found to get instant insight into these errors.

What does the question mark and the colon (?: ternary operator) mean in objective-c?

Fun fact, in objective-c if you want to check null / nil For example:

-(NSString*) getSomeStringSafeCheck
    NSString *string = [self getSomeString];
    if(string != nil){
        return String;
    return @"";

The quick way to do it is:

-(NSString*) getSomeStringSafeCheck
    return [self getSomeString] != nil ? [self getSomeString] : @"";

Then you can update it to a simplest way:

-(NSString*) getSomeStringSafeCheck
    return [self getSomeString]?: @"";

Because in Objective-C:

  1. if an object is nil, it will return false as boolean;
  2. Ternary Operator's second parameter can be empty, as it will return the result on the left of '?'

So let say you write:

[self getSomeString] != nil?: @"";

the second parameter is returning a boolean value, thus a exception is thrown.

HTML: Is it possible to have a FORM tag in each TABLE ROW in a XHTML valid way?

It's worth mentioning that this is possible in HTML5, using the "form" attribute for input elements:

        <td><form id="form1"><input type="hidden" name="id" value="1" /></form></td>
        <td><input form="form1" type="text" name="name" value="Name" /></td>
        <td><input form="form1" type="text" name="description" value="Description" /></td>
        <td><input form="form1" type="submit" value="Save" /></td>
        <td><form id="form2"><input type="hidden" name="id" value="1" /></form></td>
        <td><input form="form2" type="text" name="name" value="Name" /></td>
        <td><input form="form2" type="text" name="description" value="Description" /></td>
        <td><input form="form2" type="submit" value="Save" /></td>

While clean in its lack of JS and use of original elements, unfortunately this isn't working in IE10.

Using sed to mass rename files

If all you're really doing is removing the second character, regardless of what it is, you can do this:


but your command is building a mv command and piping it to the shell for execution.

This is no more readable than your version:

find -type f | sed -n 'h;s/.//4;x;s/^/mv /;G;s/\n/ /g;p' | sh

The fourth character is removed because find is prepending each filename with "./".

Spring Data JPA findOne() change to Optional how to use this?

Optional api provides methods for getting the values. You can check isPresent() for the presence of the value and then make a call to get() or you can make a call to get() chained with orElse() and provide a default value.

The last thing you can try doing is using @Query() over a custom method.

How to uninstall a windows service and delete its files without rebooting

As noted by StingyJack and mcbala, and in reference to comments made by Mike L, my experience is that on a Windows 2000 machine, when uninstalling / reinstalling .Net services, "installutil /u" does require a reboot, even when the service was previously stopped. "sc /delete", on the other hand, does not require a reboot - it deletes the service right away (as long as it is stopped).

I have often wondered, actually, whether there is a good reason "installutil /u" requires a reboot... Is "sc /delete" actually doing something wrong / leaving something hanging?

Re-assign host access permission to MySQL user

I haven't had to do this, so take this with a grain of salt and a big helping of "test, test, test".

What happens if (in a safe controlled test environment) you directly modify the Host column in the mysql.user and probably mysql.db tables? (E.g., with an update statement.) I don't think MySQL uses the user's host as part of the password encoding (the PASSWORD function doesn't suggest it does), but you'll have to try it to be sure. You may need to issue a FLUSH PRIVILEGES command (or stop and restart the server).

For some storage engines (MyISAM, for instance), you may also need to check/modify the .frm file any views that user has created. The .frm file stores the definer, including the definer's host. (I have had to do this, when moving databases between hosts where there had been a misconfiguration causing the wrong host to be recorded...)

Best equivalent VisualStudio IDE for Mac to program .NET/C#

MonoDevelop from:

There is no equivalent to Visual Studio. However, for writing C# on Mac or Linux, you can't get better than MonoDevelop.

The Mac build is pre beta. From the MonoDevelop site on Mac:

The Mac OS X port of MonoDevelop is under active development and has not seen a stable release yet. Recent work described by Michael Hutchinson has focussed on improving the usability and stability of Monodevelop on the Mac. This work will be released in MonoDevelop 2.2. Right now it's not finished, and is very much an alpha.

Array to Collection: Optimized code



 List<String> stooges = Arrays.asList("Larry", "Moe", "Curly");

See Arrays.asList class documentation.

What is recursion and when should I use it?

A recursive function is one which calls itself. The most common reason I've found to use it is traversing a tree structure. For example, if I have a TreeView with checkboxes (think installation of a new program, "choose features to install" page), I might want a "check all" button which would be something like this (pseudocode):

function cmdCheckAllClick {

function checkRecursively(Node n) {
    n.Checked = True;
    foreach ( n.Children as child ) {

So you can see that the checkRecursively first checks the node which it is passed, then calls itself for each of that node's children.

You do need to be a bit careful with recursion. If you get into an infinite recursive loop, you will get a Stack Overflow exception :)

I can't think of a reason why people shouldn't use it, when appropriate. It is useful in some circumstances, and not in others.

I think that because it's an interesting technique, some coders perhaps end up using it more often than they should, without real justification. This has given recursion a bad name in some circles.

How to get an element by its href in jquery?

If you want to get any element that has part of a URL in their href attribute you could use:

$( 'a[href*=""]' );

This will select all elements with a href that contains, for example:

As stated by @BalusC in the comments below, it will also match elements that have at any position in the href, like

Sass calculate percent minus px

There is a calc function in both SCSS [compile-time] and CSS [run-time]. You're likely invoking the former instead of the latter.

For obvious reasons mixing units won't work compile-time, but will at run-time.

You can force the latter by using unquote, a SCSS function.

.selector { height: unquote("-webkit-calc(100% - 40px)"); }

The localhost page isn’t working localhost is currently unable to handle this request. HTTP ERROR 500

It maybe solve your problem, check your files access level

$ sudo chmod -R 777 /"your files location"

Adding close button in div to close the box

jQuery("#your_div_id").remove(); will completely remove the corresponding elements from the HTML DOM. So if you want to show the div on another event without a refresh, it will not be possible to retrieve the removed elements back unless you use AJAX.

jQuery("#your_div_id").toggle("slow"); will also could make unexpected results. As an Example when you select some element on your div which generates another div with a close button(which uses the same close functionality just as your previous div) it could make undesired behaviour.

So without using AJAX, a good solution for the close button would be as follows


<div id="your_div_id">
<span class="close_div" onclick="close_div(1)">&#10006</span>


function close_div(id) {
    if(id === 1) {

Now you can show the div, when another event occures as you wish... :-)

Emulator error: This AVD's configuration is missing a kernel file

Update the following commands in command prompt in windows:

i) android update sdk --no-ui --all // It update your SDK packages and it takes 3 minutes. ii) android update sdk --no-ui --filter platform-tools,tools //It updates the platform tools and its packages. iii) android update sdk --no-ui --all --filter extra-android-m2repository // Those who are working with maven project update this to support with latest support design library which will include extra maven android maven Repository.

1)In the command prompt it asks you for Y/N .click on the Y then it proceeds with the installation. 2) It updates all Kernel-qemu files and qt5.dll commands. so that the Emulator works fine without any issues.

Rails: Address already in use - bind(2) (Errno::EADDRINUSE)

If the above solutions don't work on ubuntu/linux then you can try this

sudo fuser -k -n tcp port

Run it several times to kill processes on your port of choosing. port could be 3000 for example. You would have killed all the processes if you see no output after running the command

How to make a <ul> display in a horizontal row

As others have mentioned, you can set the li to display:inline;, or float the li left or right. Additionally, you can also use display:flex; on the ul. In the snippet below I also added justify-content:space-around to give it more spacing.

For more information on flexbox, checkout this complete guide.

#div_top_hypers {_x000D_
    display:inline;      _x000D_
#ul_top_hypers {_x000D_
    display: flex;_x000D_
<div id="div_top_hypers">_x000D_
    <ul id="ul_top_hypers">_x000D_
        <li>&#8227; <a href="" class="a_top_hypers"> Inbox</a></li>_x000D_
        <li>&#8227; <a href="" class="a_top_hypers"> Compose</a></li>_x000D_
        <li>&#8227; <a href="" class="a_top_hypers"> Reports</a></li>_x000D_
        <li>&#8227; <a href="" class="a_top_hypers"> Preferences</a></li>_x000D_
        <li>&#8227; <a href="" class="a_top_hypers"> logout</a></li>_x000D_

How can I use jQuery in Greasemonkey?

There's absolutely nothing wrong with including the entirety of jQuery within your Greasemonkey script. Just take the source, and place it at the top of your user script. No need to make a script tag, since you're already executing JavaScript!

The user only downloads the script once anyways, so size of script is not a big concern. In addition, if you ever want your Greasemonkey script to work in non-GM environments (such as Opera's GM-esque user scripts, or Greasekit on Safari), it'll help not to use GM-unique constructs such as @require.

How to configure ChromeDriver to initiate Chrome browser in Headless mode through Selenium?

So after correcting my code to:

options = webdriver.ChromeOptions()
chrome_driver_path = "C:\Python27\Scripts\chromedriver.exe"

The .exe file still came up when running the script. Although this did get rid of some extra output telling me "Failed to launch GPU process".

What ended up working is running my Python script using a .bat file

So basically,

  1. Save python script if a folder
  2. Open text editor, and dump the following code (edit to your script of course)

    c:\python27\python.exe c:\SampleFolder\ %*

  3. Save the .txt file and change the extension to .bat

  4. Double click this to run the file

So this just opened the script in Command Prompt and ChromeDriver seems to be operating within this window without popping out to the front of my screen and thus solving the problem.

How to extract img src, title and alt from html using php?

Here's A PHP Function I hobbled together from all of the above info for a similar purpose, namely adjusting image tag width and length properties on the fly ... a bit clunky, perhaps, but seems to work dependably:

function ReSizeImagesInHTML($HTMLContent,$MaximumWidth,$MaximumHeight) {

// find image tags
preg_match_all('/<img[^>]+>/i',$HTMLContent, $rawimagearray,PREG_SET_ORDER); 

// put image tags in a simpler array
$imagearray = array();
for ($i = 0; $i < count($rawimagearray); $i++) {
    array_push($imagearray, $rawimagearray[$i][0]);

// put image attributes in another array
$imageinfo = array();
foreach($imagearray as $img_tag) {

    preg_match_all('/(src|width|height)=("[^"]*")/i',$img_tag, $imageinfo[$img_tag]);

// combine everything into one array
$AllImageInfo = array();
foreach($imagearray as $img_tag) {

    $ImageSource = str_replace('"', '', $imageinfo[$img_tag][2][0]);
    $OrignialWidth = str_replace('"', '', $imageinfo[$img_tag][2][1]);
    $OrignialHeight = str_replace('"', '', $imageinfo[$img_tag][2][2]);

    $NewWidth = $OrignialWidth; 
    $NewHeight = $OrignialHeight;
    $AdjustDimensions = "F";

    if($OrignialWidth > $MaximumWidth) { 
        $diff = $OrignialWidth-$MaximumHeight; 
        $percnt_reduced = (($diff/$OrignialWidth)*100); 
        $NewHeight = floor($OrignialHeight-(($percnt_reduced*$OrignialHeight)/100)); 
        $NewWidth = floor($OrignialWidth-$diff); 
        $AdjustDimensions = "T";

    if($OrignialHeight > $MaximumHeight) { 
        $diff = $OrignialHeight-$MaximumWidth; 
        $percnt_reduced = (($diff/$OrignialHeight)*100); 
        $NewWidth = floor($OrignialWidth-(($percnt_reduced*$OrignialWidth)/100)); 
        $NewHeight= floor($OrignialHeight-$diff); 
        $AdjustDimensions = "T";

    $thisImageInfo = array('OriginalImageTag' => $img_tag , 'ImageSource' => $ImageSource , 'OrignialWidth' => $OrignialWidth , 'OrignialHeight' => $OrignialHeight , 'NewWidth' => $NewWidth , 'NewHeight' => $NewHeight, 'AdjustDimensions' => $AdjustDimensions);
    array_push($AllImageInfo, $thisImageInfo);

// build array of before and after tags
$ImageBeforeAndAfter = array();
for ($i = 0; $i < count($AllImageInfo); $i++) {

    if($AllImageInfo[$i]['AdjustDimensions'] == "T") {
        $NewImageTag = str_ireplace('width="' . $AllImageInfo[$i]['OrignialWidth'] . '"', 'width="' . $AllImageInfo[$i]['NewWidth'] . '"', $AllImageInfo[$i]['OriginalImageTag']);
        $NewImageTag = str_ireplace('height="' . $AllImageInfo[$i]['OrignialHeight'] . '"', 'height="' . $AllImageInfo[$i]['NewHeight'] . '"', $NewImageTag);

        $thisImageBeforeAndAfter = array('OriginalImageTag' => $AllImageInfo[$i]['OriginalImageTag'] , 'NewImageTag' => $NewImageTag);
        array_push($ImageBeforeAndAfter, $thisImageBeforeAndAfter);

// execute search and replace
for ($i = 0; $i < count($ImageBeforeAndAfter); $i++) {
    $HTMLContent = str_ireplace($ImageBeforeAndAfter[$i]['OriginalImageTag'],$ImageBeforeAndAfter[$i]['NewImageTag'], $HTMLContent);

return $HTMLContent;


How to create a thread?

The following ways work.

// The old way of using ParameterizedThreadStart. This requires a
// method which takes ONE object as the parameter so you need to
// encapsulate the parameters inside one object.
Thread t = new Thread(new ParameterizedThreadStart(StartupA));
t.Start(new MyThreadParams(path, port));

// You can also use an anonymous delegate to do this.
Thread t2 = new Thread(delegate()
    StartupB(port, path);

// Or lambda expressions if you are using C# 3.0
Thread t3 = new Thread(() => StartupB(port, path));

The Startup methods have following signature for these examples.

public void StartupA(object parameters);

public void StartupB(int port, string path);

Java Replace Character At Specific Position Of String?

If you need to re-use a string, then use StringBuffer:

String str = "hi";
StringBuffer sb = new StringBuffer(str);
while (...) {
    sb.setCharAt(1, 'k');


Note that StringBuffer is thread-safe, while using StringBuilder is faster, but not thread-safe.

Boolean operators ( &&, -a, ||, -o ) in Bash

-a and -o are the older and/or operators for the test command. && and || are and/or operators for the shell. So (assuming an old shell) in your first case,

[ "$1" = 'yes' ] && [ -r $2.txt ]

The shell is evaluating the and condition. In your second case,

[ "$1" = 'yes' -a $2 -lt 3 ]

The test command (or builtin test) is evaluating the and condition.

Of course in all modern or semi-modern shells, the test command is built in to the shell, so there really isn't any or much difference. In modern shells, the if statement can be written:

[[ $1 == yes && -r $2.txt ]]

Which is more similar to modern programming languages and thus is more readable.

git ignore vim temporary files

This is something that should only be done on a per-user basis, not per-repository. If Joe uses emacs, he will want to have emacs backup files ignored, but Betty (who uses vi) will want vi backup files ignored (in many cases, they are similar, but there are about 24,893 common editors in existence and it is pretty ridiculous to try to ignore all of the various backup extensions.)

In other words, do not put anything in .gitignore or in core.excludes in $GIT_DIR/config. Put the info in $HOME/.gitconfig instead (as nunopolonia suggests with --global.) Note that "global" means per-user, not per-system.

If you want configuration across the system for all users (which you don't), you'll need a different mechanism. (Possibly with templates setup prior to initialization of the repository.)

SQL - Select first 10 rows only?

In standard SQL you can use:


This is supported in DB2, PostgreSQL and Oracle 12.1 (and later)

Port 443 in use by "Unable to open process" with PID 4

I had this same problem with port 443, process id 4 and everything. For me it was not the VPN using the port, it was IIS. To fix this I opened up IIS and right clicked on my instance and stopped it. Then IIS Express(Or apache if you're using that) was able to use port 443. Hope this helps someone else.

Write a number with two decimal places SQL Server

Multiply the value you want to insert (ex. 2.99) by 100

Then insert the division by 100 of the result adding .01 to the end:


JSON to pandas DataFrame

The problem is that you have several columns in the data frame that contain dicts with smaller dicts inside them. Useful Json is often heavily nested. I have been writing small functions that pull the info I want out into a new column. That way I have it in the format that I want to use.

for row in range(len(data)):
    #First I load the dict (one at a time)
    n = data.loc[row,'dict_column']
    #Now I make a new column that pulls out the data that I want.
    data.loc[row,'new_column'] = n.get('key')

Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_u64 on Intel CPUs

I can't give an authoritative answer, but provide an overview of a likely cause. This reference shows pretty clearly that for the instructions in the body of your loop there is a 3:1 ratio between latency and throughput. It also shows the effects of multiple dispatch. Since there are (give-or-take) three integer units in modern x86 processors, it's generally possible to dispatch three instructions per cycle.

So between peak pipeline and multiple dispatch performance and failure of these mechanisms, we have a factor of six in performance. It's pretty well known that the complexity of the x86 instruction set makes it quite easy for quirky breakage to occur. The document above has a great example:

The Pentium 4 performance for 64-bit right shifts is really poor. 64-bit left shift as well as all 32-bit shifts have acceptable performance. It appears that the data path from the upper 32 bits to the lower 32 bit of the ALU is not well designed.

I personally ran into a strange case where a hot loop ran considerably slower on a specific core of a four-core chip (AMD if I recall). We actually got better performance on a map-reduce calculation by turning that core off.

Here my guess is contention for integer units: that the popcnt, loop counter, and address calculations can all just barely run at full speed with the 32-bit wide counter, but the 64-bit counter causes contention and pipeline stalls. Since there are only about 12 cycles total, potentially 4 cycles with multiple dispatch, per loop body execution, a single stall could reasonably affect run time by a factor of 2.

The change induced by using a static variable, which I'm guessing just causes a minor reordering of instructions, is another clue that the 32-bit code is at some tipping point for contention.

I know this is not a rigorous analysis, but it is a plausible explanation.

How to make spring inject value into a static field

I've had a similar requirement: I needed to inject a Spring-managed repository bean into my Person entity class ("entity" as in "something with an identity", for example an JPA entity). A Person instance has friends, and for this Person instance to return its friends, it shall delegate to its repository and query for friends there.

public class Person {
    private static PersonRepository personRepository;

    private long id;

    public static void setPersonRepository(PersonRepository personRepository){
        this.personRepository = personRepository;

    public Set<Person> getFriends(){
        return personRepository.getFriends(id);



public class PersonRepository {

    public Person get Person(long id) {
        // do database-related stuff

    public Set<Person> getFriends(long id) {
        // do database-related stuff


So how did I inject that PersonRepository singleton into the static field of the Person class?

I created a @Configuration, which gets picked up at Spring ApplicationContext construction time. This @Configuration gets injected with all those beans that I need to inject as static fields into other classes. Then with a @PostConstruct annotation, I catch a hook to do all static field injection logic.

public class StaticFieldInjectionConfiguration {

    private PersonRepository personRepository;

    private void init() {

Single-threaded apartment - cannot instantiate ActiveX control

The problem you're running into is that most background thread / worker APIs will create the thread in a Multithreaded Apartment state. The error message indicates that the control requires the thread be a Single Threaded Apartment.

You can work around this by creating a thread yourself and specifying the STA apartment state on the thread.

var t = new Thread(MyThreadStartMethod);

Turn off display errors using file "php.ini"

It is not enough in case of PHP fpm. It was one more configuration file which can enable display_error. You should find www.conf. In my case it is in directory /etc/php/7.1/fpm/pool.d/

You should find php_flag[display_errors] = on and disable it, php_flag[display_errors] = off. This should solve the issue.

How do I REALLY reset the Visual Studio window layout?

I tried most of the suggestions, and none of them worked. I didn't get a chance to try /resetuserdata. Finally I reinstalled the plugin and uninstalled it again, and the windows went away.

How to fix error "ERROR: Command errored out with exit status 1: python." when trying to install django-heroku using pip

You need to add the package containing the executable pg_config.

A prior answer should have details you need: pg_config executable not found

Right pad a string with variable number of spaces

This is based on Jim's answer,

    @field_text + SPACE(@pad_length - LEN(@field_text)) AS RightPad
   ,SPACE(@pad_length - LEN(@field_text)) + @field_text AS LeftPad


  • More Straight Forward
  • Slightly Cleaner (IMO)
  • Faster (Maybe?)
  • Easily Modified to either double pad for displaying in non-fixed width fonts or split padding left and right to center


  • Doesn't handle LEN(@field_text) > @pad_length

Converting unix timestamp string to readable date

>>> from datetime import datetime
>>> datetime.fromtimestamp(1172969203.1)
datetime.datetime(2007, 3, 4, 0, 46, 43, 100000)

Taken from

scikit-learn random state in splitting dataset

We used the random_state parameter for reproducibility of the initial shuffling of training datasets after each epoch.

How to link HTML5 form action to Controller ActionResult method in ASP.NET MVC 4

Here I'm basically wrapping a button in a link. The advantage is that you can post to different action methods in the same form.

<a href="Controller/ActionMethod">
    <input type="button" value="Click Me" />

Adding parameters:

<a href="Controller/ActionMethod?userName=ted">
    <input type="button" value="Click Me" />

Adding parameters from a non-enumerated Model:

<a href="Controller/[email protected]">
    <input type="button" value="Click Me" />

You can do the same for an enumerated Model too. You would just have to reference a single entity first. Happy Coding!

how to open a jar file in Eclipse

use java decompiler. you can open the jar files.

Thanks, Manirathinam.

How to get first character of a string in SQL?

I prefer:

SUBSTRING (my_column, 1, 1)

because it is Standard SQL-92 syntax and therefore more portable.

Strictly speaking, the standard version would be

SUBSTRING (my_column FROM 1 FOR 1)

The point is, transforming from one to the other, hence to any similar vendor variation, is trivial.

p.s. It was only recently pointed out to me that functions in standard SQL are deliberately contrary, by having parameters lists that are not the conventional commalists, in order to make them easily identifiable as being from the standard!

How to get AM/PM from a datetime in PHP

$currentDateTime = $row['date'];
echo $newDateTime = date('l jS \of F Y h:i:s A', strtotime($currentDateTime));

What is the best way to parse html in C#?

Html Agility Pack

This is an agile HTML parser that builds a read/write DOM and supports plain XPATH or XSLT (you actually don't HAVE to understand XPATH nor XSLT to use it, don't worry...). It is a .NET code library that allows you to parse "out of the web" HTML files. The parser is very tolerant with "real world" malformed HTML. The object model is very similar to what proposes System.Xml, but for HTML documents (or streams).

Linear Layout and weight in Android

Plus you need to add this android:layout_width="0dp" for children views [Button views] of LinerLayout

Waiting till the async task finish its work

I think the easiest way is to create an interface to get the data from onpostexecute and run the Ui from interface :

Create an Interface :

public interface AsyncResponse {
    void processFinish(String output);

Then in asynctask

protected void onPostExecute(String data) {

Then in yout main activity

public void processFinish(String data) {
     // do things


Cannot insert explicit value for identity column in table 'table' when IDENTITY_INSERT is set to OFF

The problem raised from using non-typed DBContext or DBSet if you using Interface and implement method of savechanges in a generic way

If this is your case I propose to strongly typed DBContex for example


then .Savechanges will work

C# Break out of foreach loop after X number of items

int processed = 0;
foreach(ListViewItem lvi in listView.Items)
   //do stuff
   if (++processed == 50) break;

or use LINQ

foreach( ListViewItem lvi in listView.Items.Cast<ListViewItem>().Take(50))
    //do stuff

or just use a regular for loop (as suggested by @sgriffinusa and @Eric J.)

for(int i = 0; i < 50 && i < listView.Items.Count; i++)
    ListViewItem lvi = listView.Items[i];

Export DataBase with MySQL Workbench with INSERT statements

I had some problems to find this option in newer versions, so for Mysql Workbench 6.3, go to schemas and enter in your connection:

enter image description here

Go to Tools -> Data Export

enter image description here

Click on Advanced Options

enter image description here

Scroll down and uncheck extended-inserts

enter image description here

Then export the data you want and you will see the result file as this:

enter image description here

load scripts asynchronously

I loaded the scripts asynchronously (html 5 has that feature) when all the scripts where done loading I redirected the page to index2.html where index2.html uses the same libraries. Because browsers have a cache once the page redirects to index2.html, index2.html loads in less than a second because it has all it needs to load the page. In my index.html page I also load the images that I plan on using so that the browser place those images on the cache. so my index.html looks like:

<!DOCTYPE html>
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
    <title>Project Management</title>

    <!-- the purpose of this page is to load all the scripts on the browsers cache so that pages can load fast from now on -->

    <script type="text/javascript">

        function stylesheet(url) {
            var s = document.createElement('link');
            s.type = 'text/css';
            s.async = true;
            s.src = url;
            var x = document.getElementsByTagName('head')[0];

        function script(url) {
            var s = document.createElement('script');
            s.type = 'text/javascript';
            s.async = true;
            s.src = url;
            var x = document.getElementsByTagName('head')[0];

        //load scritps to the catche of browser
        (function () {            



    <script type="text/javascript">
       // once the page is loaded go to index2.html
        window.onload = function () {
            document.location = "index2.html";


<div id="cover" style="position:fixed; left:0px; top:0px; width:100%; height:100%; background-color:Black; z-index:100;">Loading</div>

<img src="images/home/background.png" />
<img src="images/home/3.png"/>
<img src="images/home/6.jpg"/>
<img src="images/home/4.png"/>
<img src="images/home/5.png"/>
<img src="images/home/8.jpg"/>
<img src="images/home/9.jpg"/>
<img src="images/logo.png"/>
<img src="images/logo.png"/>
<img src="images/theme/contentBorder.png"/>


another nice thing about this is that I may place a loader in the page and when the page is done loading the loader will go away and in a matte of milliseconds the new page will be running.

Is there a way to automatically generate getters and setters in Eclipse?

Right click -> Source -> Generate setters and getters

But to make it even more convenient, I always map this to ALT+SHIFT+G from Windows -> Preferences -> General -> Keys

Creating a new dictionary in Python

>>> dict(a=2,b=4)
{'a': 2, 'b': 4}

Will add the value in the python dictionary.

PHP not displaying errors even though display_errors = On

Although this is old post... i had similar situation that gave me headache. Finally, i figured that i was including sub pages in index.php with "@include ..." "@" hides all errors even if display_errors is ON

Count words in a string method?



This will work.

appending array to FormData and send via AJAX

I've fixed the typescript version. For javascript, just remove type definitions.

  _getFormDataKey(key0: any, key1: any): string {
    return !key0 ? key1 : `${key0}[${key1}]`;
  _convertModelToFormData(model: any, key: string, frmData?: FormData): FormData {
    let formData = frmData || new FormData();

    if (!model) return formData;

    if (model instanceof Date) {
      formData.append(key, model.toISOString());
    } else if (model instanceof Array) {
      model.forEach((element: any, i: number) => {
        this._convertModelToFormData(element, this._getFormDataKey(key, i), formData);
    } else if (typeof model === 'object' && !(model instanceof File)) {
      for (let propertyName in model) {
        if (!model.hasOwnProperty(propertyName) || !model[propertyName]) continue;
        this._convertModelToFormData(model[propertyName], this._getFormDataKey(key, propertyName), formData);
    } else {
      formData.append(key, model);

    return formData;

retrieve links from web page using python and BeautifulSoup

just for getting the links, without B.soup and regex:

import urllib2
tag="<a href=\""
for item in data:
    if "<a href" in item:
            ind = item.index(tag)
        except: pass
            print item[:end]

for more complex operations, of course BSoup is still preferred.

Execution failed app:processDebugResources Android Studio

aapt is 32 bit so will not execute on a 64 bit box until 32 bit architecture is enabled

dpkg --print-foreign-architectures  #  if prints nothing then below is fix

sudo dpkg --add-architecture i386  #  add a 32 bit architecture to box

sudo apt-get install -y lib32gcc1 libc6-i386 lib32z1 lib32stdc++6

sudo apt-get install -y lib32ncurses5 lib32gomp1 lib32z1-dev

it work for me.

How do I write the 'cd' command in a makefile?

Starting from GNU make 3.82 (July 2010), you can use the .ONESHELL special target to run all recipe lines in a single instantiation of the shell (bold emphasis mine):

  • New special target: .ONESHELL instructs make to invoke a single instance of the shell and provide it with the entire recipe, regardless of how many lines it contains.
.ONESHELL: # Only applies to all target
    cd ~/some_dir
    pwd # Prints ~/some_dir if cd succeeded

    cd ~/some_dir
    pwd # Oops, prints ~

How to continue a Docker container which has exited

docker start `docker ps -a | awk '{print $1}'`

This will start up all the containers that are in the 'Exited' state

Modifying a file inside a jar

Check out TrueZip.

It does exactly what you want (to edit files inline inside a jar file), through a virtual file system API. It also supports nested archives (jar inside a jar) as well.

Is it possible to specify a different ssh port when using rsync?

Your command line should look like this:

rsync -rvz -e 'ssh -p 2222' --progress ./dir user@host:/path

this works fine - I use it all the time without needing any new firewall rules - just note the SSH command itself is enclosed in quotes.

Why are Python lambdas useful?

I use it quite often, mainly as a null object or to partially bind parameters to a function.

Here are examples:

to implement null object pattern:

    DATA_PACKET: self.handle_data_packets
    NET_PACKET: self.handle_hardware_packets
}.get(packet_type, lambda x : None)(payload)

for parameter binding:

let say that I have the following API

def dump_hex(file, var)
    # some code

class X(object):
    def packet_received(data):
        # some kind of preprocessing

Then, when I wan't to quickly dump the recieved data to a file I do that:

dump_file = file('hex_dump.txt','w')
X.callback = lambda (x): dump_hex(dump_file, x)

In Python, how do you convert seconds since epoch to a `datetime` object?

From the docs, the recommended way of getting a timezone aware datetime object from seconds since epoch is:

Python 3:

from datetime import datetime, timezone
datetime.fromtimestamp(timestamp, timezone.utc)

Python 2, using pytz:

from datetime import datetime
import pytz
datetime.fromtimestamp(timestamp, pytz.utc)

Best way to check if MySQL results returned in PHP?

Whenever we do queries to get some data, it is returned as an object. Then most of us convert it to array for looping through the rows easily. In php "empty()" function is used to check if an array is empty i.e. if it has no data in it. So we can check if returned array representation of query isn't empty by doing like this

           //DO STUFF

how to change text box value with jQuery?

Use like this on dropdown change

Python Requests requests.exceptions.SSLError: [Errno 8] _ssl.c:504: EOF occurred in violation of protocol

I have had this error when connecting to a RabbitMQ MQTT server via TLS. I'm pretty sure the server is broken but anyway it worked with OpenSSL 1.0.1, but not OpenSSL 1.0.2.

You can check your version in Python using this:

import ssl

I'm not sure how to downgrade OpenSSL within Python (it seems to be statically linked on Windows at least), other than using an older version of Python.

Error when creating a new text file with python?

instead of using try-except blocks, you could use, if else

this will not execute if the file is non-existent, open(name,'r+')

if os.path.exists('location\filename.txt'):
    print "File exists"

   open("location\filename.txt", 'w')

'w' creates a file if its non-exis

Hibernate Annotations - Which is better, field or property access?

We created entity beans and used getter annotations. The problem we ran into is this: some entities have complex rules for some properties regarding when they can be updated. The solution was to have some business logic in each setter that determines whether or not the actual value changed and, if so, whether the change should be allowed. Of course, Hibernate can always set the properties, so we ended up with two groups of setters. Pretty ugly.

Reading previous posts, I also see that referencing the properties from inside the entity could lead to issues with collections not loading.

Bottom line, I would lean toward annotating the fields in the future.

403 - Forbidden: Access is denied. You do not have permission to view this directory or page using the credentials that you supplied

In my case, the issue was new sites had an implicit deny of all IP addresses unless an explicit allow was created. To fix: Under the site in Features View: Under the IIS Section > IP Address and Domain Restrictions > Edit Feature Settings > Set 'Access for unspecified clients:' to 'Allow'

ConcurrentModificationException for ArrayList

there should has a concurrent implemention of List interface supporting such operation.

try java.util.concurrent.CopyOnWriteArrayList.class

Calculate age given the birth date in the format YYYYMMDD

see this example you get full year month day information from here

function getAge(dateString) {
    var today = new Date();
    var birthDate = new Date(dateString);
    var age = today.getFullYear() - birthDate.getFullYear();
    var m = today.getMonth() - birthDate.getMonth();
    var da = today.getDate() - birthDate.getDate();
    if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
        m +=12;
        da +=30;
    return age+" years "+ Math.abs(m) + "months"+ Math.abs(da) + " days";
alert('age: ' + getAge("1987/08/31"));    

How can I make a weak protocol reference in 'pure' Swift (without @objc)

protocol must be subClass of AnyObject, class

example given below

    protocol NameOfProtocol: class {
   // member of protocol
   class ClassName: UIViewController {
      weak var delegate: NameOfProtocol? 

PLS-00428: an INTO clause is expected in this SELECT statement

In PLSQL block, columns of select statements must be assigned to variables, which is not the case in SQL statements.

The second BEGIN's SQL statement doesn't have INTO clause and that caused the error.

   DSC           VARCHAR (512);
    WHERE PART_NUM = 'S0146404';

             || ','
             || RTRIM (PLANID.DESC_TEXT)
             || ','
             || CASE
                   WHEN PLANID.HIGH = 'TEST123'
                         WHEN TO_DATE (PROD.START_DATE) + 30 > SYSDATE
             || ','
             || 'GB'
             || ','
        INTO DSC
                ON PROD.PART_NUM = PLANID.VAL
                ON PROD.PROD_ID = PROD.ROW_ID
                ON VIS.PROD_ID = VISPROD.ROW_ID
       WHERE     PLANID.TYPE = 'Test Plan'
             AND PLANID.ACTIVE_FLG = 'Y'
             AND PROD.STATUS_CD = 'Active'


ORDER BY date and time BEFORE GROUP BY name in mysql

As I am not allowed to comment on user1908688's answer, here a hint for MariaDB users:

     SELECT *
     ORDER BY date ASC, time ASC
     LIMIT 18446744073709551615
     ) AS sub

add image to uitableview cell

Try this code:--

UIImageView *imv = [[UIImageView alloc]initWithFrame:CGRectMake(3,2, 20, 25)];
imv.image=[UIImage imageNamed:@"arrow2.png"];
[cell addSubview:imv];
[imv release];

Android Studio was unable to find a valid Jvm (Related to MAC OS)

I ran this bad boy:

launchctl setenv STUDIO_JDK /Library/Java/JavaVirtualMachines/jdk1.7.0_71.jdk/

Difference between `constexpr` and `const`

const applies for variables, and prevents them from being modified in your code.

constexpr tells the compiler that this expression results in a compile time constant value, so it can be used in places like array lengths, assigning to const variables, etc. The link given by Oli has a lot of excellent examples.

Basically they are 2 different concepts altogether, and can (and should) be used together.

How should I use Outlook to send code snippets?

Years later I have a response.

  1. Use an online code highlighter like to highlight your code so you can paste marked up code from your IDE into Word. Depending on your IDE you may be able to skip this step.

  2. In Word 2010, go to insert->object->openDocument Text. Steps 2-3 are documented at How do you display code snippets in MS Word preserving format and syntax highlighting?.

  3. Paste your highlighted code into the object.

  4. Copy the whole object.

  5. Right-click-> paste special the object into Outlook.

This gives you a highlighted, contained box of code for use in emails in Outlook 2010.

How many socket connections possible?

10,000? 70,000? is that all :)

FreeBSD is probably the server you want, Here's a little blog post about tuning it to handle 100,000 connections, its has had some interesting features like zero-copy sockets for some time now, along with kqueue to act as a completion port mechanism.

Solaris can handle 100,000 connections back in the last century!. They say linux would be better

The best description I've come across is this presentation/paper on writing a scalable webserver. He's not afraid to say it like it is :)

Same for software: the cretins on the application layer forced great innovations on the OS layer. Because Lotus Notes keeps one TCP connection per client open, IBM contributed major optimizations for the ”one process, 100.000 open connections” case to Linux

And the O(1) scheduler was originally created to score well on some irrelevant Java benchmark. The bottom line is that this bloat bene?ts all of us.

How to upload a file and JSON data in Postman?

The Missing Visual Guide

You must first find the nearly-invisible pale-grey-on-white dropdown for File which is the magic key that unlocks the Choose Files button.

After you choose POST, then choose Body->form-data, then find the File dropdown, and then choose 'File', only then will the 'Choose Files' button magically appear:

Postman POST file setup - (Text,File) dropdown highlighted

What are named pipes?

According to Wikipedia:

[...] A traditional pipe is "unnamed" because it exists anonymously and persists only for as long as the process is running. A named pipe is system-persistent and exists beyond the life of the process and must be "unlinked" or deleted once it is no longer being used. Processes generally attach to the named pipe (usually appearing as a file) to perform IPC (inter-process communication).

To show error message without alert box in Java Script

Try this code

 <script type="text/javascript">
 function validate() {
document.getElementById('errfn').innerHTML="this is invalid name";
 <form name="myform">
  <input type=text id=fname name=fname onblur="validate()"> </input><div id="errfn">   </div>

<br> <br>
<input type=text id=lname name=lname onblur="validate()"> </input>

<input type=button value=check> 


How to solve Object reference not set to an instance of an object.?

I think you just need;

List<string> list = new List<string>();

There is a difference between

List<string> list; 


List<string> list = new List<string>();

When you didn't use new keyword in this case, your list didn't initialized. And when you try to add it hai, obviously you get an error.

How to make tesseract to recognize only numbers, when they are mixed with letters?

For tesseract 3, the command is simpler tesseract imagename outputbase digits according to the FAQ. But it doesn't work for me very well.

I turn to try different psm options and find -psm 6 works best for my case.

man tesseract for details.

Fluid or fixed grid system, in responsive design, based on Twitter Bootstrap

Source -


  • Fixed-width layouts are much easier to use and easier to customize in terms of design.
  • Widths are the same for every browser, so there is less hassle with images, forms, video and other content that are fixed-width.
  • There is no need for min-width or max-width, which isn’t supported by every browser anyway.
  • Even if a website is designed to be compatible with the smallest screen resolution, 800×600, the content will still be wide enough at a larger resolution to be easily legible.


  • A fixed-width layout may create excessive white space for users with larger screen resolutions, thus upsetting “divine proportion,” the “Rule of Thirds,” overall balance and other design principles.
  • Smaller screen resolutions may require a horizontal scroll bar, depending the fixed layout’s width.
  • Seamless textures, patterns and image continuation are needed to accommodate those with larger resolutions.
  • Fixed-width layouts generally have a lower overall score when it comes to usability.

MySQL: Can't create table (errno: 150)

Please make sure both your primary key column and referenced column have the same data types and attributes (unsigned, binary, unsigned zerofill etc).

Trim Cells using VBA in Excel

The infinite loop is a result of an On Error Resume Next statement somewhere higher up in your code. Get rid of it now. If your code only runs with On Error Resume Next in effect, it needs instant and complete overhaul.

And while you are at it, place an Option Explicit on top of yor module. It forces you to declare all variables, a safeguard against annoying bugs that are the result of mis-typed variable names. (You can modify the VBA editor preferences to have that option set automatically the next time, which is highly recommended.)

The immediate problem with your code is that a cell is an object, and objects cannot be trimmed. You want to trim the text of the cell, so you must do so:

cell.Text = Trim(cell.Text)

How to update nested state properties in React

Something like this might suffice,

const isObject = (thing) => {
    if(thing && 
        typeof thing === 'object' &&
        typeof thing !== null
        && !(Array.isArray(thing))
        return true;
    return false;

  Call with an array containing the path to the property you want to access
  And the current component/redux state.

  For example if we want to update `hello` within the following obj
  const obj = {

  we would do :
  //clone the object
  const cloned = clone(['someNestedObj','hello'],obj)
  //Set the new value
  cloned.someNestedObj.hello = 5;

const clone = (arr, state) => {
    let clonedObj = {...state}
    const originalObj = clonedObj;
    arr.forEach(property => {
        if(!(property in clonedObj)){
            throw new Error('State missing property')

            clonedObj[property] = {...originalObj[property]};
            clonedObj = clonedObj[property];
    return originalObj;

const nestedObj = {

const clonedObj = clone(['someProperty'], nestedObj);
console.log(clonedObj === nestedObj) //returns false
console.log(clonedObj.someProperty === nestedObj.someProperty) //returns true
console.log(clonedObj.someNestedObj === nestedObj.someNestedObj) //returns true

const clonedObj2 = clone(['someProperty','someNestedObj','someOtherProperty'], nestedObj);
console.log(clonedObj2 === nestedObj) // returns false
console.log(clonedObj2.someNestedObj === nestedObj.someNestedObj) //returns false
//returns true (doesn't attempt to clone because its primitive type)
console.log(clonedObj2.someNestedObj.someOtherProperty === nestedObj.someNestedObj.someOtherProperty) 

How to parse data in JSON format?

For URL or file, use json.load(). For string with .json content, use json.loads().

#! /usr/bin/python

import json
# from pprint import pprint

json_file = 'my_cube.json'
cube = '1'

with open(json_file) as json_data:
    data = json.load(json_data)

# pprint(data)

print "Dimension: ", data['cubes'][cube]['dim']
print "Measures:  ", data['cubes'][cube]['meas']

How to use store and use session variables across pages?

Reasoning from the comments to this question, it appears a lack of an adjusted session.save_path causes this misbehavior of PHP’s session handler. Just specify a directory (outside your document root directory) that exists and is both readable and writeable by PHP to fix this.

Element implicitly has an 'any' type because expression of type 'string' can't be used to index

// bad
const _getKeyValue = (key: string) => (obj: object) => obj[key];

// better
const _getKeyValue_ = (key: string) => (obj: Record<string, any>) => obj[key];

// best
const getKeyValue = <T extends object, U extends keyof T>(key: U) => (obj: T) =>

Bad - the reason for the error is the object type is just an empty object by default. Therefore it isn't possible to use a string type to index {}.

Better - the reason the error disappears is because now we are telling the compiler the obj argument will be a collection of string/value (string/any) pairs. However, we are using the any type, so we can do better.

Best - T extends empty object. U extends the keys of T. Therefore U will always exist on T, therefore it can be used as a look up value.

Here is a full example:

I have switched the order of the generics (U extends keyof T now comes before T extends object) to highlight that order of generics is not important and you should select an order that makes the most sense for your function.

const getKeyValue = <U extends keyof T, T extends object>(key: U) => (obj: T) =>

interface User {
  name: string;
  age: number;

const user: User = {
  name: "John Smith",
  age: 20

const getUserName = getKeyValue<keyof User, User>("name")(user);

// => 'John Smith'

Alternative Syntax

const getKeyValue = <T, K extends keyof T>(obj: T, key: K): T[K] => obj[key];

How does Trello access the user's clipboard?

I actually built a Chrome extension that does exactly this, and for all web pages. The source code is on GitHub.

I find three bugs with Trello's approach, which I know because I've faced them myself :)

The copy doesn't work in these scenarios:

  1. If you already have Ctrl pressed and then hover a link and hit C, the copy doesn't work.
  2. If your cursor is in some other text field in the page, the copy doesn't work.
  3. If your cursor is in the address bar, the copy doesn't work.

I solved #1 by always having a hidden span, rather than creating one when user hits Ctrl/Cmd.

I solved #2 by temporarily clearing the zero-length selection, saving the caret position, doing the copy and restoring the caret position.

I haven't found a fix for #3 yet :) (For information, check the open issue in my GitHub project).

How can I create numbered map markers in Google Maps V3?

This has now been added to the Mapping documentation and requires no third party code.

You can combine these two samples:

To get code like this:

var labelIndex = 0;

function initialize() {
  var bangalore = { lat: 12.97, lng: 77.59 };
  var map = new google.maps.Map(document.getElementById('map-canvas'), {
    zoom: 12,
    center: bangalore

  // This event listener calls addMarker() when the map is clicked.
  google.maps.event.addListener(map, 'click', function(event) {
    addMarker(event.latLng, map);

  // Add a marker at the center of the map.
  addMarker(bangalore, map);

// Adds a marker to the map.
function addMarker(location, map) {
  // Add the marker at the clicked location, and add the next-available label
  // from the array of alphabetical characters.
  var marker = new google.maps.Marker({
    position: location,
    label: labels[labelIndex],
    map: map,
    icon: 'image.png'

google.maps.event.addDomListener(window, 'load', initialize);

Note that if you have more than 35 markers, this method will not work as the label only shows the first character (using A-Z and 0-9 makes 35). Please vote for this Google Maps Issue to request that this restriction be lifted.

Why is HttpClient BaseAddress not working?

It turns out that, out of the four possible permutations of including or excluding trailing or leading forward slashes on the BaseAddress and the relative URI passed to the GetAsync method -- or whichever other method of HttpClient -- only one permutation works. You must place a slash at the end of the BaseAddress, and you must not place a slash at the beginning of your relative URI, as in the following example.

using (var handler = new HttpClientHandler())
using (var client = new HttpClient(handler))
    client.BaseAddress = new Uri("");
    var response = await client.GetAsync("resource/7");

Even though I answered my own question, I figured I'd contribute the solution here since, again, this unfriendly behavior is undocumented. My colleague and I spent most of the day trying to fix a problem that was ultimately caused by this oddity of HttpClient.

How to print last two columns using awk

awk '{print $NF-1, $NF}'  inputfile

Note: this works only if at least two columns exist. On records with one column you will get a spurious "-1 column1"

How do I capture all of my compiler's output to a file?

It is typically not what you want to do. You want to run your compilation in an editor that has support for reading the output of the compiler and going to the file/line char that has the problems. It works in all editors worth considering. Here is the emacs setup:

How can I find the first occurrence of a sub-string in a python string?

def find_pos(chaine,x):

    for i in range(len(chaine)):
        if chaine[i] ==x :
            return 'yes',i 
    return 'no'

How to switch between frames in Selenium WebDriver using Java

There is also possibility to use WebDriverWait with ExpectedConditions (to make sure that Frame will be available).

  1. With string as parameter

    (new WebDriverWait(driver, 5)).until(ExpectedConditions.frameToBeAvailableAndSwitchToIt("frame-name"));
  2. With locator as a parameter

    (new WebDriverWait(driver, 5)).until(ExpectedConditions.frameToBeAvailableAndSwitchToIt("frame-id")));

More info can be found here

Change bootstrap navbar background color and font color

No need for the specificity .navbar-default in your CSS. Background color requires background-color:#cc333333 (or just background:#cc3333). Finally, probably best to consolidate all your customizations into a single class, as below:

.navbar-custom {
    color: #FFFFFF;
    background-color: #CC3333;


<div id="menu" class="navbar navbar-default navbar-custom">


String replacement in java, similar to a velocity template

Use StringSubstitutor from Apache Commons Text.

It will do it for you (and its open source...)

 Map<String, String> valuesMap = new HashMap<String, String>();
 valuesMap.put("animal", "quick brown fox");
 valuesMap.put("target", "lazy dog");
 String templateString = "The ${animal} jumped over the ${target}.";
 StringSubstitutor sub = new StringSubstitutor(valuesMap);
 String resolvedString = sub.replace(templateString);

Get exit code for command in bash/ksh

It should be $cmd instead of $($cmd). Works fine with that on my box.

Edit: Your script works only for one-word commands, like ls. It will not work for "ls cpp". For this to work, replace cmd="$1"; $cmd with "$@". And, do not run your script as command="some cmd"; safeRun command, run it as safeRun some cmd.

Also, when you have to debug your bash scripts, execute with '-x' flag. [bash -x].

How to overlay density plots in R?

ggplot2 is another graphics package that handles things like the range issue Gavin mentions in a pretty slick way. It also handles auto generating appropriate legends and just generally has a more polished feel in my opinion out of the box with less manual manipulation.


#Sample data
dat <- data.frame(dens = c(rnorm(100), rnorm(100, 10, 5))
                   , lines = rep(c("a", "b"), each = 100))
ggplot(dat, aes(x = dens, fill = lines)) + geom_density(alpha = 0.5)

enter image description here

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

Below code is perfectly workd for me:

        var inputValue = $(this).attr("value");_x000D_
        var targetBox = $("." + inputValue);_x000D_
        color: #fff;_x000D_
        padding: 20px;_x000D_
        display: none;_x000D_
        margin-top: 20px;_x000D_
    .red{ background: #ff0000; }_x000D_
    .green{ background: #228B22; }_x000D_
    .blue{ background: #0000ff; }_x000D_
    label{ margin-right: 15px; }
<script src=""></script>_x000D_
        <label><input type="radio" name="colorRadio" value="red"> red</label>_x000D_
        <label><input type="radio" name="colorRadio" value="green"> green</label>_x000D_
        <label><input type="radio" name="colorRadio" value="blue"> blue</label>_x000D_
    <div class="red box">You have selected <strong>red radio button</strong> so i am here</div>_x000D_
    <div class="green box">You have selected <strong>green radio button</strong> so i am here</div>_x000D_
    <div class="blue box">You have selected <strong>blue radio button</strong> so i am here</div>

Conversion failed when converting date and/or time from character string in SQL SERVER 2008

Seems like last_accessed_on, is a date time, and you are converting '23-07-2014 09:37:00' to a varchar. This would not work, and give you conversion errors. Try

last_accessed_on= convert(datetime,'23-07-2014 09:37:00', 103)  

I think you can avoid the cast though, and update with '23-07-2014 09:37:00'. It should work given that the format is correct.

Your query is not going to work because in last_accessed_on (which is DateTime2 type), you are trying to pass a Varchar value.

You query would be

UPDATE  student_queues SET  Deleted=0 ,  last_accessed_by='raja', last_accessed_on=convert(datetime,'23-07-2014 09:37:00', 103)  
 WHERE std_id IN ('2144-384-11564') AND reject_details='REJECT'

how to calculate binary search complexity

The time complexity of the binary search algorithm belongs to the O(log n) class. This is called big O notation. The way you should interpret this is that the asymptotic growth of the time the function takes to execute given an input set of size n will not exceed log n.

This is just formal mathematical lingo in order to be able to prove statements, etc. It has a very straightforward explanation. When n grows very large, the log n function will out-grow the time it takes to execute the function. The size of the "input set", n, is just the length of the list.

Simply put, the reason binary search is in O(log n) is that it halves the input set in each iteration. It's easier to think about it in the reverse situation. On x iterations, how long list can the binary search algorithm at max examine? The answer is 2^x. From this we can see that the reverse is that on average the binary search algorithm needs log2 n iterations for a list of length n.

If why it is O(log n) and not O(log2 n), it's because simply put again - Using the big O notation constants don't count.

SQL grouping by all the columns

He is trying find and display the duplicate rows in a table.

SELECT *, COUNT(*) AS NoOfOccurrences

Do we have a simple way to accomplish this?

How to detect when a youtube video finishes playing?

What you may want to do is include a script on all pages that does the following ... 1. find the youtube-iframe : searching for it by width and height by title or by finding in its source. You can do that by ... - looping through the window.frames by a for-in loop and then filter out by the properties

  1. inject jscript in the iframe of the current page adding the onYoutubePlayerReady must-include-function

  2. Add the event listeners etc..

Hope this helps

MySQL Select Date Equal to Today

SELECT, DATE_FORMAT(users.signup_date, '%Y-%m-%d') 
FROM users 
WHERE DATE(signup_date) = CURDATE()

Convert to binary and keep leading zeros in Python

>>> '{:08b}'.format(1)

See: Format Specification Mini-Language

Note for Python 2.6 or older, you cannot omit the positional argument identifier before :, so use

>>> '{0:08b}'.format(1)

How can I overwrite file contents with new content in PHP?

MY PREFERRED METHOD is using fopen,fwrite and fclose [it will cost less CPU]

fwrite($f,'new content');

Warning for those using file_put_contents

It'll affect a lot in performance, for example [on the same class/situation] file_get_contents too: if you have a BIG FILE, it'll read the whole content in one shot and that operation could take a long waiting time

One command to create a directory and file inside it linux command

devnull's answer provides a function:

mkfile() { mkdir -p -- "$1" && touch -- "$1"/"$2" }

This function did not work for me as is (I'm running bash 4.3.48 on WSL Ubuntu), but did work once I removed the double dashes. So, this worked for me:

echo 'mkfile() { mkdir -p "$1" && touch "$1"/"$2" }' >> ~/.bash_profile
source ~/.bash_profile
mkfile sample/dir test.file

jQuery find file extension (from string)

How about something like this.

Test the live example:

It assumes that the string will always end with the extension:

function openFile(file) {
    var extension = file.substr( (file.lastIndexOf('.') +1) );
    switch(extension) {
        case 'jpg':
        case 'png':
        case 'gif':
            alert('was jpg png gif');  // There's was a typo in the example where
        break;                         // the alert ended with pdf instead of gif.
        case 'zip':
        case 'rar':
            alert('was zip rar');
        case 'pdf':
            alert('was pdf');
            alert('who knows');


EDIT: I mistakenly deleted part of the string in openFile("somestring.png");. Corrected. Had it in the Live Example, though.

Detect click outside React component

I used this module (I have no association with the author)

npm install react-onclickout --save

const ClickOutHandler = require('react-onclickout');_x000D_
class ExampleComponent extends React.Component {_x000D_
  onClickOut(e) {_x000D_
    if (hasClass(, 'ignore-me')) return;_x000D_
    alert('user clicked outside of the component!');_x000D_
  render() {_x000D_
    return (_x000D_
      <ClickOutHandler onClickOut={this.onClickOut}>_x000D_
        <div>Click outside of me!</div>_x000D_

It did the job nicely.

What is the purpose for using OPTION(MAXDOP 1) in SQL Server?

Adding my two cents, based on a performance issue I observed.

If simple queries are getting parellelized unnecessarily, it can bring more problems than solving one. However, before adding MAXDOP into the query as "knee-jerk" fix, there are some server settings to check.

In Jeremiah Peschka - Five SQL Server Settings to Change, MAXDOP and "COST THRESHOLD FOR PARALLELISM" (CTFP) are mentioned as important settings to check.

Note: Paul White mentioned max server memory aslo as a setting to check, in a response to Performance problem after migration from SQL Server 2005 to 2012. A good kb article to read is Using large amounts of memory can result in an inefficient plan in SQL Server

Jonathan Kehayias - Tuning ‘cost threshold for parallelism’ from the Plan Cache helps to find out good value for CTFP.

Why is cost threshold for parallelism ignored?

Aaron Bertrand - Six reasons you should be nervous about parallelism has a discussion about some scenario where MAXDOP is the solution.

Parallelism-Inhibiting Components are mentioned in Paul White - Forcing a Parallel Query Execution Plan

Get file name from a file location in Java

new File(absolutePath).getName();

Nginx 403 forbidden for all files

One permission requirement that is often overlooked is a user needs x permissions in every parent directory of a file to access that file. Check the permissions on /, /home, /home/demo, etc. for www-data x access. My guess is that /home is probably 770 and www-data can't chdir through it to get to any subdir. If it is, try chmod o+x /home (or whatever dir is denying the request).

EDIT: To easily display all the permissions on a path, you can use namei -om /path/to/check

LINQ query to find if items in a list are contained in another list

List<string> test1 = new List<string> { "", "" };
List<string> test2 = new List<string> { "[email protected]", "[email protected]", "[email protected]" };

var result = (from t2 in test2
              where test1.Any(t => t2.Contains(t)) == false
              select t2);

If query form is what you want to use, this is legible and more or less as "performant" as this could be.

What i mean is that what you are trying to do is an O(N*M) algorithm, that is, you have to traverse N items and compare them against M values. What you want is to traverse the first list only once, and compare against the other list just as many times as needed (worst case is when the email is valid since it has to compare against every black listed domain).

from t2 in test we loop the email list once.

test1.Any(t => t2.Contains(t)) == false we compare with the blacklist and when we found one match return (hence not comparing against the whole list if is not needed)

select t2 keep the ones that are clean.

So this is what I would use.

Is it possible to indent JavaScript code in Notepad++?

JSTool is the best for stability.


  1. Select menu Plugins>Plugin Manager>Show Plugin Manager
  2. Check to JSTool checkbox > Install > Restart Notepad++
  3. Open js file > Plugins > JSTool > JSFormat


Check if list contains element that contains a string and get that element

You could use Linq's FirstOrDefault extension method:

string element = myList.FirstOrDefault(s => s.Contains(myString));

This will return the fist element that contains the substring myString, or null if no such element is found.

If all you need is the index, use the List<T> class's FindIndex method:

int index = myList.FindIndex(s => s.Contains(myString));

This will return the the index of fist element that contains the substring myString, or -1 if no such element is found.

Binding ItemsSource of a ComboBoxColumn in WPF DataGrid

RookieRick is right, using DataGridTemplateColumn instead of DataGridComboBoxColumn gives a much simpler XAML.

Moreover, putting the CompanyItem list directly accessible from the GridItem allows you to get rid of the RelativeSource.

IMHO, this give you a very clean solution.


<DataGrid AutoGenerateColumns="False" ItemsSource="{Binding GridItems}" >
        <DataTemplate x:Key="CompanyDisplayTemplate" DataType="vm:GridItem">
            <TextBlock Text="{Binding Company}" />
        <DataTemplate x:Key="CompanyEditingTemplate" DataType="vm:GridItem">
            <ComboBox SelectedItem="{Binding Company}" ItemsSource="{Binding CompanyList}" />
        <DataGridTextColumn Binding="{Binding Name}" />
        <DataGridTemplateColumn CellTemplate="{StaticResource CompanyDisplayTemplate}"
                                CellEditingTemplate="{StaticResource CompanyEditingTemplate}" />

View model:

public class GridItem
    public string Name { get; set; }
    public CompanyItem Company { get; set; }
    public IEnumerable<CompanyItem> CompanyList { get; set; }

public class CompanyItem
    public int ID { get; set; }
    public string Name { get; set; }

    public override string ToString() { return Name; }

public class ViewModel
    readonly ObservableCollection<CompanyItem> companies;

    public ViewModel()
        companies = new ObservableCollection<CompanyItem>{
            new CompanyItem { ID = 1, Name = "Company 1" },
            new CompanyItem { ID = 2, Name = "Company 2" }

        GridItems = new ObservableCollection<GridItem> {
            new GridItem { Name = "Jim", Company = companies[0], CompanyList = companies}

    public ObservableCollection<GridItem> GridItems { get; set; }

fast way to copy formatting in excel

Just use the NumberFormat property after the Value property: In this example the Ranges are defined using variables called ColLetter and SheetRow and this comes from a for-next loop using the integer i, but they might be ordinary defined ranges of course.

TransferSheet.Range(ColLetter & SheetRow).Value = Range(ColLetter & i).Value TransferSheet.Range(ColLetter & SheetRow).NumberFormat = Range(ColLetter & i).NumberFormat

copy db file with adb pull results in 'permission denied' error

Did you try adb remount after giving adb root?

React Native Change Default iOS Simulator Device

Specify a simulator using the --simulator flag.

These are the available devices for iOS 14.0 onwards:

npx react-native run-ios --simulator="iPhone 8"
npx react-native run-ios --simulator="iPhone 8 Plus"
npx react-native run-ios --simulator="iPhone 11"
npx react-native run-ios --simulator="iPhone 11 Pro"
npx react-native run-ios --simulator="iPhone 11 Pro Max"
npx react-native run-ios --simulator="iPhone SE (2nd generation)"
npx react-native run-ios --simulator="iPhone 12 mini"
npx react-native run-ios --simulator="iPhone 12"
npx react-native run-ios --simulator="iPhone 12 Pro"
npx react-native run-ios --simulator="iPhone 12 Pro Max"
npx react-native run-ios --simulator="iPod touch (7th generation)"
npx react-native run-ios --simulator="iPad Pro (9.7-inch)"
npx react-native run-ios --simulator="iPad Pro (11-inch) (2nd generation)"
npx react-native run-ios --simulator="iPad Pro (12.9-inch) (4th generation)"
npx react-native run-ios --simulator="iPad (8th generation)"
npx react-native run-ios --simulator="iPad Air (4th generation)"

List all available iOS devices:

xcrun simctl list devices

There is currently no way to set a default.

React Native Docs: Running On Simulator

Do you get charged for a 'stopped' instance on EC2?

When you stop an instance, it is 'deleted'. As such there's nothing to be charged for. If you have an Elastic IP or EBS, then you'll be charged for those - but nothing related to the instance itself.

Using Keras & Tensorflow with AMD GPU

Theano does have support for OpenCL but it is still in its early stages. Theano itself is not interested in OpenCL and relies on community support.

Most of the operations are already implemented and it is mostly a matter of tuning and optimizing the given operations.

To use the OpenCL backend you have to build libgpuarray yourself.

From personal experience I can tell you that you will get CPU performance if you are lucky. The memory allocation seems to be very naively implemented (therefore computation will be slow) and will crash when it runs out of memory. But I encourage you to try and maybe even optimize the code or help reporting bugs.

sql query with multiple where statements

Can we see the structure of your table? If I am understanding this, then the assumption made by the query is that a record can be only meta_key - 'lat' or meta_key = 'long' not both because each row only has one meta_key column and can only contain 1 corresponding value, not 2. That would explain why you don't get results when you connect the with an AND; it's impossible.

How to find memory leak in a C++ code/project?

Make certain that all the heap memory is successfully freed. There is no need if you never allocate memory on the heap. If you do, count the number of times you malloc memory, and count up the number of time you free memory.

How do I set response headers in Flask?

This work for me

from flask import Flask
from flask import Response

app = Flask(__name__)

def home():
    return Response(headers={'Access-Control-Allow-Origin':'*'})

if __name__ == "__main__":

Does Java have an exponential operator?

In case if anyone wants to create there own exponential function using recursion, below is for your reference.

public static double power(double value, double p) {
        if (p <= 0)
            return 1;

        return value * power(value, p - 1);

500 internal server error at GetResponse()

From that error, I would say that your code is fine, at least the part that calls the webservice. The error seems to be in the actual web service.

To get the error from the web server, add a try catch and catch a WebException. A WebException has a property called Response which is a HttpResponse. you can then log anything that is returned, and upload you code. Check back later in the logs and see what is actually being returned.

Change event on select with knockout binding, how can I know if it is a real change?

If you use an observable instead of a primitive value, the select will not raise change events on initial binding. You can continue to bind to the change event, rather than subscribing directly to the observable.

Prevent double curly brace notation from displaying momentarily before angular.js compiles/interpolates document

To improve the effectiveness of class='ng-cloak' approach when scripts are loaded last, make sure the following css is loaded in the head of the document:

.ng-cloak { display:none; }

Passing multiple variables to another page in url


Warning The superglobals $_GET and $_REQUEST are already decoded. Using urldecode() on an element in $_GET or $_REQUEST could have unexpected and dangerous results.


be careful.

javascript: pause setTimeout();

I don't think you'll find anything better than clearTimeout. Anyway, you can always schedule another timeout later, instead 'resuming' it.

Getting list of tables, and fields in each, in a database

I found an easy way to fetch the details of Tables and columns of a particular DB using SQL developer.


Seeing the console's output in Visual Studio 2010?

Here are a couple of things to check:

  1. For console.Write/WriteLine, your app must be a console application. (right-click the project in Solution Explorer, choose Properties, and look at the "Output Type" combo in the Application Tab -- should be "Console Application" (note, if you really need a windows application or a class library, don't change this to Console App just to get the Console.WriteLine).

  2. You could use System.Diagnostics.Debug.WriteLine to write to the output window (to show the output window in VS, got to View | Output) Note that these writes will only occur in a build where the DEBUG conditional is defined (by default, debug builds define this, and release builds do not)

  3. You could use System.Diagnostics.Trace.Writeline if you want to be able to write to configurable "listeners" in non-debug builds. (by default, this writes to the Output Window in Visual Studio, just like Debug.Writeline)

dropping infinite values from dataframes in pandas?

The simplest way would be to first replace infs to NaN:

df.replace([np.inf, -np.inf], np.nan)

and then use the dropna:

df.replace([np.inf, -np.inf], np.nan).dropna(subset=["col1", "col2"], how="all")

For example:

In [11]: df = pd.DataFrame([1, 2, np.inf, -np.inf])

In [12]: df.replace([np.inf, -np.inf], np.nan)
0   1
1   2
2 NaN
3 NaN

The same method would work for a Series.

This declaration has no storage class or type specifier in C++

Calling m.check(side), meaning you are running actual code, but you can't run code outside main() - you can only define variables. In C++, code can only appear inside function bodies or in variable initializes.

Including a css file in a blade template?

include the css file into your blade template in laravel

  1. move css file into public->css folder in your laravel project.
  2. use <link rel="stylesheet" href="{{ asset('css/filename') }}">

so css is applied in a blade.php file.

"Use of undeclared type" in Swift, even though type is internal, and exists in same module

In my case, this was caused by a subclass name being used in the very next line as a variable name with a different type:

var binGlow: pipGlow = pipGlow(style: "Bin")
var pipGlow: PipGlowSprite = PipGlowSprite()

Notice that in line 1, pipGlow is the name of the subclass (of SKShapeNode), but in line two, I was using pipGlow as a variable name. This was not only bad coding style, but apparently an outright no-no as well! Once I change the second line to:

var binGlow: pipGlow = pipGlow(style: "Bin")
var pipGlowSprite: PipGlowSprite = PipGlowSprite()

I no longer received the error. I hope this helps someone!

How to set a timeout on a http.request() in Node?

At this moment there is a method to do this directly on the request object:

request.setTimeout(timeout, function() {

This is a shortcut method that binds to the socket event and then creates the timeout.

Reference: Node.js v0.8.8 Manual & Documentation

Why are only final variables accessible in anonymous class?

You can create a class level variable to get returned value. I mean

class A {
    int k = 0;
    private void f(Button b, int a){
        b.addClickHandler(new ClickHandler() {
        public void onClick(ClickEvent event) {
            k = a * 5;

now you can get value of K and use it where you want.

Answer of your why is :

A local inner class instance is tied to Main class and can access the final local variables of its containing method. When the instance uses a final local of its containing method, the variable retains the value it held at the time of the instance's creation, even if the variable has gone out of scope (this is effectively Java's crude, limited version of closures).

Because a local inner class is neither the member of a class or package, it is not declared with an access level. (Be clear, however, that its own members have access levels like in a normal class.)

Bring element to front using CSS

Note: z-index only works on positioned elements (position:absolute, position:relative, or position:fixed). Use one of those.

How to get complete current url for Cakephp

In CakePHP 3 $this->here will be deprecated. The actual way is using this method:


Inheriting constructors

You have to explicitly define the constructor in B and explicitly call the constructor for the parent.

B(int x) : A(x) { }


B() : A(5) { }

What does "exited with code 9009" mean during this build?

I think in my case there were russian symbols in path (all projects were in user folder). When I put solution in another folder (directly on disk), everything became ok.

Append values to a set in Python

This question is the first one that shows up on Google when one looks up "Python how to add elements to set", so it's worth noting explicitly that, if you want to add a whole string to a set, it should be added with .add(), not .update().

Say you have a string foo_str whose contents are 'this is a sentence', and you have some set bar_set equal to set().

If you do bar_set.update(foo_str), the contents of your set will be {'t', 'a', ' ', 'e', 's', 'n', 'h', 'c', 'i'}.

If you do bar_set.add(foo_str), the contents of your set will be {'this is a sentence'}.

Insert auto increment primary key to existing table

Well, you have multiple ways to do this: -if you don't have any data on your table, just drop it and create it again.

Dropping the existing field and creating it again like this


Or just modify it


Try-catch speeding up my code?

I'd have put this in as a comment as I'm really not certain that this is likely to be the case, but as I recall it doesn't a try/except statement involve a modification to the way the garbage disposal mechanism of the compiler works, in that it clears up object memory allocations in a recursive way off the stack. There may not be an object to be cleared up in this case or the for loop may constitute a closure that the garbage collection mechanism recognises sufficient to enforce a different collection method. Probably not, but I thought it worth a mention as I hadn't seen it discussed anywhere else.

Excel to JSON javascript code?

The answers are working fine with xls format but, in my case, it didn't work for xlsx format. Thus I added some code here. it works both xls and xlsx format.

I took the sample from the official sample link.

Hope it may help !

function fileReader(oEvent) {
        var oFile =[0];
        var sFilename =;

        var reader = new FileReader();
        var result = {};

        reader.onload = function (e) {
            var data =;
            data = new Uint8Array(data);
            var workbook =, {type: 'array'});
            var result = {};
            workbook.SheetNames.forEach(function (sheetName) {
                var roa = XLSX.utils.sheet_to_json(workbook.Sheets[sheetName], {header: 1});
                if (roa.length) result[sheetName] = roa;
            // see the result, caution: it works after reader event is done.

// Add your id of "File Input" 
$('#fileUpload').change(function(ev) {
        // Do something 

Windows path in Python

Yes, \ in Python string literals denotes the start of an escape sequence. In your path you have a valid two-character escape sequence \a, which is collapsed into one character that is ASCII Bell:

>>> '\a'
>>> len('\a')
>>> 'C:\meshes\as'
>>> print('C:\meshes\as')

Other common escape sequences include \t (tab), \n (line feed), \r (carriage return):

>>> list('C:\test')
['C', ':', '\t', 'e', 's', 't']
>>> list('C:\nest')
['C', ':', '\n', 'e', 's', 't']
>>> list('C:\rest')
['C', ':', '\r', 'e', 's', 't']

As you can see, in all these examples the backslash and the next character in the literal were grouped together to form a single character in the final string. The full list of Python's escape sequences is here.

There are a variety of ways to deal with that:

  1. Python will not process escape sequences in string literals prefixed with r or R:

    >>> r'C:\meshes\as'
    >>> print(r'C:\meshes\as')
  2. Python on Windows should handle forward slashes, too.

  3. You could use os.path.join ...

    >>> import os
    >>> os.path.join('C:', os.sep, 'meshes', 'as')
  4. ... or the newer pathlib module

    >>> from pathlib import Path
    >>> Path('C:', '/', 'meshes', 'as')

PyCharm import external library

Answer for PyCharm 2016.1 on OSX: (This is an update to the answer by @GeorgeWilliams993's answer above, but I don't have the rep yet to make comments.)

Go to Pycharm menu --> Preferences --> Project: (projectname) --> Project Interpreter

At the top is a popup for "Project Interpreter," and to the right of it is a button with ellipses (...) - click on this button for a different popup and choose "More" (or, as it turns out, click on the main popup and choose "Show All").

This shows a list of interpreters, with one selected. At the bottom of the screen are a set of tools... pick the rightmost one:

Show path for the selected interpreter button

Now you should see all the paths pycharm is searching to find imports, and you can use the "+" button at the bottom to add a new path.

I think the most significant difference from @GeorgeWilliams993's answer is that the gear button has been replaced by a set of ellipses. That threw me off.

mysql is not recognised as an internal or external command,operable program or batch

In my case, it turned out to be a simple case of spacing.

Turns out, i had a space inserted after the last ; and before ""C:\Program Files\MySQL\MySQL Server 5.7" For this very simple reason, no matter what i did, MySql was still not being recognized.

Once i eliminated the spaces before and after path, it worked perfectly.

In retrospect, seems like a very obvious answer, but nobody's mentioned it anywhere.

Also, i'm new to this whole windows thing, so please excuse me if it sounds very simple.

How to show image using ImageView in Android

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

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

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

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

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

Tomcat request timeout

For anyone who doesn't like none of the solutions posted above like me then you can simply implement a timer yourself and stop the request execution by throwing a runtime exception. Something like below:

                     timer.schedule(new TimerTask() {
                       public void run() {
                     }, /* specify time of the requst */ 1000);
                 catch(Exception e)
                   throw new RuntimeException("the request is taking longer than usual");


or preferably use the java guava timeLimiter here

npm not working after clearing cache

This worked for me:

npm cache clean --force 

How to insert text with single quotation sql server 2005

This worked for me:

  VALUES ('text','''''', 1)

Basically, you take the single quote you want to insert and replace it with two. So if you want to insert a string of text ('text') and add single quotes around it, it would be ('''text'''). Hope this helps.

Sum the digits of a number

Here is a solution without any loop or recursion but works for non-negative integers only (Python3):

def sum_digits(n):
    if n > 0:
        s = (n-1) // 9    
        return n-9*s
    return 0

The CodeDom provider type "Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider" could not be located

Just add the next nuget package to your project - Microsoft.CodeDom.Providers.DotNetCompilerPlatform.

Had the same problem.

browser.msie error after update to jQuery 1.9.1

Instead of having the whole migration script added, you could simply add the following (extracted from the migration script)

$.uaMatch = function( ua ) {
    ua = ua.toLowerCase();

    var match = /(chrome)[ \/]([\w.]+)/.exec( ua ) ||
        /(webkit)[ \/]([\w.]+)/.exec( ua ) ||
        /(opera)(?:.*version|)[ \/]([\w.]+)/.exec( ua ) ||
        /(msie) ([\w.]+)/.exec( ua ) ||
        ua.indexOf("compatible") < 0 && /(mozilla)(?:.*? rv:([\w.]+)|)/.exec( ua ) ||

    return {
        browser: match[ 1 ] || "",
        version: match[ 2 ] || "0"

and then use it like so


How do I disable form fields using CSS?

You can't use CSS to disable Textbox. solution would be HTML Attribute.


Copy a git repo without history

Isn't this exactly what squashing a rebase does? Just squash everything except the last commit and then (force) push it.

Copying files to a container with Docker Compose


      - /dir/on/host:/var/www/html

if /dir/on/host doesn't exist, it is created on the host and the empty content is mounted in the container at /var/www/html. Whatever content you had before in /var/www/html inside the container is inaccessible, until you unmount the volume; the new mount is hiding the old content.

how to use math.pi in java

Here is usage of Math.PI to find circumference of circle and Area First we take Radius as a string in Message Box and convert it into integer

public class circle {

    public static void main(String[] args) {
        // TODO code application logic here

        String rad;

        float radius,area,circum;

       rad = JOptionPane.showInputDialog("Enter the Radius of circle:");

        radius = Integer.parseInt(rad);
        area = (float) (Math.PI*radius*radius);
        circum = (float) (2*Math.PI*radius);

        JOptionPane.showMessageDialog(null, "Area: " + area,"AREA",JOptionPane.INFORMATION_MESSAGE);
        JOptionPane.showMessageDialog(null, "circumference: " + circum, "Circumfernce",JOptionPane.INFORMATION_MESSAGE);


Is there an onSelect event or equivalent for HTML <select>?

Another solution is using the onMouseUp event. OnMouseUp works also with the same option re-selected as well as changed option.

Only disadvantage. The code is called when the dropdown box is openemd and a second time when the selection is made. Keep that in mind for AJAX requests. If this is not harming your logic you can use it as a simple inline hack.

<select id="bla" onmouseup="console.log( document.getElementById('bla').options[document.getElementById('bla').selectedIndex].value );">
  <option value="0">A</option>
  <option value="1">B</option>

jQuery won't parse my JSON from AJAX query

In a ColdFusion environment, one thing that will cause an error, even with well-formed JSON, is having Enable Request Debugging Output turned on in the ColdFusion Administrator (under Debugging & Logging > Debug Output Settings). Debugging information will be returned with the JSON data and will thus make it invalid.

Exit codes in Python

For the record, you can use POSIX standard exit codes defined here.


import sys, os

sys.exit(os.EX_OK) # code 0, all ok

How can you check for a #hash in a URL using JavaScript?

Have you tried this?

if (url.indexOf('#') !== -1) {
    // Url contains a #

(Where url is the URL you want to check, obviously.)

How to start a background process in Python?

You probably want to start investigating the os module for forking different threads (by opening an interactive session and issuing help(os)). The relevant functions are fork and any of the exec ones. To give you an idea on how to start, put something like this in a function that performs the fork (the function needs to take a list or tuple 'args' as an argument that contains the program's name and its parameters; you may also want to define stdin, out and err for the new thread):

    pid = os.fork()
except OSError, e:
    ## some debug output
if pid == 0:
    ## eventually use os.putenv(..) to set environment variables
    ## os.execv strips of args[0] for the arguments
    os.execv(args[0], args)

How do I specify the platform for MSBuild?

If you want to build your solution for x86 and x64, your solution must be configured for both platforms. Actually you just have an Any CPU configuration.

How to check the available configuration for a project

To check the available configuration for a given project, open the project file (*.csproj for example) and look for a PropertyGroup with the right Condition.

If you want to build in Release mode for x86, you must have something like this in your project file:

<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">

How to create and edit the configuration in Visual Studio

Configuration Manager panel

New solution platform button

New solution platform panel

How to create and edit the configuration (on MSDN)

HttpServlet cannot be resolved to a type .... is this a bug in eclipse?

You have to set the runtime for your web project to the Tomcat installation you are using; you can do it in the "Targeted runtimes" section of the project configuration.

In this way you will allow Eclipse to add Tomcat's Java EE Web Profile jars to the build path.

Remember that the HttpServlet class isn't in a JRE, but at least in an Enterprise Web Profile (e.g. a servlet container runtime /lib folder).

iptables LOG and DROP in one rule

nflog is better

sudo apt-get -y install ulogd2

ICMP Block rule example:

# Drop ICMP (PING)
$iptables -t mangle -A PREROUTING -p icmp -j NFLOG --nflog-prefix 'ICMP Block'
$iptables -t mangle -A PREROUTING -p icmp -j DROP

And you can search prefix "ICMP Block" in log:


How to change a css class style through Javascript?

document.getElementById("my").className = 'myclass';

Declare a variable in DB2 SQL

I'm coming from a SQL Server background also and spent the past 2 weeks figuring out how to run scripts like this in IBM Data Studio. Hope it helps.

CREATE VARIABLE v_lookupid INTEGER DEFAULT (4815162342); --where 4815162342 is your variable data 
DROP VARIABLE v_lookupid; 

How could I create a function with a completion handler in Swift?

Say you have a download function to download a file from network, and want to be notified when download task has finished.

typealias CompletionHandler = (success:Bool) -> Void

func downloadFileFromURL(url: NSURL,completionHandler: CompletionHandler) {

    // download code.

    let flag = true // true if download succeed,false otherwise

    completionHandler(success: flag)

// How to use it.

downloadFileFromURL(NSURL(string: "url_str")!, { (success) -> Void in

    // When download completes,control flow goes here.
    if success {
        // download success
    } else {
        // download fail

Hope it helps.

How to export data from Excel spreadsheet to Sql Server 2008 table

From your SQL Server Management Studio, you open Object Explorer, go to your database where you want to load the data into, right click, then pick Tasks > Import Data.

This opens the Import Data Wizard, which typically works pretty well for importing from Excel. You can pick an Excel file, pick what worksheet to import data from, you can choose what table to store it into, and what the columns are going to be. Pretty flexible indeed.

You can run this as a one-off, or you can store it as a SQL Server Integration Services (SSIS) package into your file system, or into SQL Server itself, and execute it over and over again (even scheduled to run at a given time, using SQL Agent).

Update: yes, yes, yes, you can do all those things you keep asking - have you even tried at least once to run that wizard??

OK, here it comes - step by step:

Step 1: pick your Excel source

enter image description here

Step 2: pick your SQL Server target database

enter image description here

Step 3: pick your source worksheet (from Excel) and your target table in your SQL Server database; see the "Edit Mappings" button!

enter image description here

Step 4: check (and change, if needed) your mappings of Excel columns to SQL Server columns in the table:

enter image description here

Step 5: if you want to use it later on, save your SSIS package to SQL Server:

enter image description here

Step 6: - success! This is on a 64-bit machine, works like a charm - just do it!!

How to delete the first row of a dataframe in R?

Keep the labels from your original file like this:

df = read.table('data.txt', header = T)

If you have columns named x and y, you can address them like this:


If you'd like to actually delete the first row from a data.frame, you can use negative indices like this:

df = df[-1,]

If you'd like to delete a column from a data.frame, you can assign NULL to it:

df$x = NULL

Here are some simple examples of how to create and manipulate a data.frame in R:

# create a data.frame with 10 rows
> x = rnorm(10)
> y = runif(10)
> df = data.frame( x, y )

# write it to a file
> write.table( df, 'test.txt', row.names = F, quote = F )

# read a data.frame from a file: 
> read.table( df, 'test.txt', header = T )

> df$x
 [1] -0.95343778 -0.63098637 -1.30646529  1.38906143  0.51703237 -0.02246754
 [7]  0.20583548  0.21530721  0.69087460  2.30610998
> df$y
 [1] 0.66658148 0.15355851 0.60098886 0.14284576 0.20408723 0.58271061
 [7] 0.05170994 0.83627336 0.76713317 0.95052671

> df$x = x
> df
            y           x
1  0.66658148 -0.95343778
2  0.15355851 -0.63098637
3  0.60098886 -1.30646529
4  0.14284576  1.38906143
5  0.20408723  0.51703237
6  0.58271061 -0.02246754
7  0.05170994  0.20583548
8  0.83627336  0.21530721
9  0.76713317  0.69087460
10 0.95052671  2.30610998

> df[-1,]
            y           x
2  0.15355851 -0.63098637
3  0.60098886 -1.30646529
4  0.14284576  1.38906143
5  0.20408723  0.51703237
6  0.58271061 -0.02246754
7  0.05170994  0.20583548
8  0.83627336  0.21530721
9  0.76713317  0.69087460
10 0.95052671  2.30610998

> df$x = NULL
> df 
1  0.66658148
2  0.15355851
3  0.60098886
4  0.14284576
5  0.20408723
6  0.58271061
7  0.05170994
8  0.83627336
9  0.76713317
10 0.95052671

Spring MVC - How to return simple String as JSON in Rest Controller

I know that this question is old but i would like to contribute too:

The main difference between others responses is the hashmap return.

public Map<String, Object> endPointExample(...) {

    Map<String, Object> rtn = new LinkedHashMap<>();

    rtn.put("pic", image);
    rtn.put("potato", "King Potato");

    return rtn;


This will return:

{"pic":"a17fefab83517fb...beb8ac5a2ae8f0449","potato":"King Potato"}

Android emulator failed to allocate memory 8

Update: Starting with Android SDK Manager version 21, the solution is to edit C:\Users\.android\avd\.avd\config.ini and change the value

hw.ramSize=1024 to




Getting all request parameters in Symfony 2

Since you are in a controller, the action method is given a Request parameter.

You can access all POST data with $request->request->all();. This returns a key-value pair array.

When using GET requests you access data using $request->query->all();

Displaying better error message than "No JSON object could be decoded"

You wont be able to get python to tell you where the JSON is incorrect. You will need to use a linter online somewhere like this

This will show you error in the JSON you are trying to decode.

Linking to a specific part of a web page

Just append a # followed by the ID of the <a> tag (or other HTML tag, like a <section>) that you're trying to get to. For example, if you are trying to link to the header in this HTML:

<p>This is some content.</p>
<h2><a id="target">Some Header</a></h2>
<p>This is some more content.</p>

You could use the link <a href="">Link</a>.

Does hosts file exist on the iPhone? How to change it?

It might exist, but you cannot change it on a non-jailbreaked iPhone.

Assuming that your development webserver is on a Mac, why don't you simply use its Bonjour name (e.g. MyMac.local.) instead of

Youtube autoplay not working on mobile devices with embedded HTML5 player

As it turns out, autoplay cannot be done on iOS devices (iPhone, iPad, iPod touch) and Android.

See and

onchange equivalent in angular2

@Mark Rajcok gave a great solution for ion projects that include a range type input.

In any other case of non ion projects I will suggest this:


<input type="text" name="points" #points maxlength="8" [(ngModel)]="range" (ngModelChange)="range=saverange($event, points)">


    onChangeAchievement(eventStr: string, eRef): string {

      //Do something (some manipulations) on input and than return it to be saved:

       //In case you need to force of modifing the Element-Reference value on-focus of input:
       var eventStrToReplace = eventStr.replace(/[^0-9,eE\.\+]+/g, "");
       if (eventStr != eventStrToReplace) {
           eRef.value = eventStrToReplace;

      return this.getNumberOnChange(eventStr);


The idea here:

  1. Letting the (ngModelChange) method to do the Setter job:

    (ngModelChange)="range=saverange($event, points)

  2. Enabling direct access to the native Dom element using this call:

    eRef.value = eventStrToReplace;

How do I grab an INI value within a shell script?

Just finished writing my own parser. I tried to use various parser found here, none seems to work with both ksh93 (AIX) and bash (Linux).

It's old programming style - parsing line by line. Pretty fast since it used few external commands. A bit slower because of all the eval required for dynamic name of the array.

The ini support 3 special syntaxs:

  • includefile=ini file --> Load an additionnal ini file. Useful for splitting ini in multiple files, or re-use some piece of configuration
  • includedir=directory --> Same as includefile, but include a complete directory
  • includesection=section --> Copy an existing section to the current section.

I used all thoses syntax to have pretty complex, re-usable ini file. Useful to install products when installing a new OS - we do that a lot.

Values can be accessed with ${ini[$section.$item]}. The array MUST be defined before calling this.

Have fun. Hope it's useful for someone else!

function Show_Debug {
    [[ $DEBUG = YES ]] && echo "DEBUG $@"

function Fatal {
    echo "$@. Script aborted"
    exit 2
# This function load an ini file in the array "ini"
# The "ini" array must be defined in the calling program (typeset -A ini)
# It could be any array name, the default array name is "ini".
# There is heavy usage of "eval" since ksh and bash do not support
# reference variable. The name of the ini is passed as variable, and must
# be "eval" at run-time to work. Very specific syntax was used and must be
# understood before making any modifications.
# It complexify greatly the program, but add flexibility.

function Load_Ini {
    Show_Debug "$0($@)"
    typeset ini_file="$1"
# Name of the array to fill. By default, it's "ini"
    typeset ini_array_name="${2:-ini}"
    typeset section variable value line my_section file subsection value_array include_directory all_index index sections pre_parse
    typeset LF="
    if [[ ! -s $ini_file ]]; then
        Fatal "The ini file is empty or absent in $0 [$ini_file]"

    include_directory=$(dirname $ini_file)

    Show_Debug "include_directory=$include_directory"

# Since this code support both bash and ksh93, you cannot use
# the syntax "echo xyz|while read line". bash doesn't work like
# that.
# It forces the use of "<<<", introduced in bash and ksh93.

    Show_Debug "Reading file $ini_file and putting the results in array $ini_array_name"
    pre_parse="$(sed 's/^ *//g;s/#.*//g;s/ *$//g' <$ini_file | egrep -v '^$')"
    while read line; do
        if [[ ${line:0:1} = "[" ]]; then # Is the line starting with "["?
# Replace [section_name] to section_name by removing the first and last character
            eval "sections=\${$ini_array_name[sections_list]}"
            sections="$sections${sections:+ }$section"
            eval "$ini_array_name[sections_list]=\"$sections\""
            Show_Debug "$ini_array_name[sections_list]=\"$sections\""
            eval "$ini_array_name[$section.exist]=YES"
            Show_Debug "$ini_array_name[$section.exist]='YES'"
            variable=${line%%=*}   # content before the =
            value=${line#*=}       # content after the =

            if [[ $variable = includefile ]]; then
# Include a single file
                Load_Ini "$include_directory/$value" "$ini_array_name"
            elif [[ $variable = includedir ]]; then
# Include a directory
# If the value doesn't start with a /, add the calculated include_directory
                if [[ $value != /* ]]; then
# go thru each file
                for file in $(ls $value/*.ini 2>/dev/null); do
                    if [[ $file != *.ini ]]; then continue; fi
# Load a single file
                    Load_Ini "$file" "$ini_array_name"
            elif [[ $variable = includesection ]]; then
# Copy an existing section into the current section
                eval "all_index=\"\${!$ini_array_name[@]}\""
# It's not necessarily fast. Need to go thru all the array
                for index in $all_index; do
# Only if it is the requested section
                    if [[ $index = $value.* ]]; then
# Evaluate the subsection [section.subsection] --> subsection
# Get the current value (source section)
                        eval "value_array=\"\${$ini_array_name[$index]}\""
# Assign the value to the current section
# The $value_array must be resolved on the second pass of the eval, so make sure the
# first pass doesn't resolve it (\$value_array instead of $value_array).
# It must be evaluated on the second pass in case there is special character like $1,
# or ' or " in it (code).
                        eval "$ini_array_name[$section.$subsection]=\"\$value_array\""
                        Show_Debug "$ini_array_name[$section.$subsection]=\"$value_array\""

# Add the value to the array
            eval "current_value=\"\${$ini_array_name[$section.$variable]}\""
# If there's already something for this field, add it with the current
# content separated by a LF (line_feed)
# Assign the content
# The $new_value must be resolved on the second pass of the eval, so make sure the
# first pass doesn't resolve it (\$new_value instead of $new_value).
# It must be evaluated on the second pass in case there is special character like $1,
# or ' or " in it (code).
            eval "$ini_array_name[$section.$variable]=\"\$new_value\""
            Show_Debug "$ini_array_name[$section.$variable]=\"$new_value\""
    done  <<< "$pre_parse"
    Show_Debug "exit $0($@)\n"

Where to find free public Web Services? -- Great collection of all category API's across web. It not only show cases the API's , but also Developers who use those API's in their applications and code samples, rating of the API and much more. They have more than apis they also have sdk and libraries too.

How can I see CakePHP's SQL dump in the controller?

for cakephp 2.0 Write this function in AppModel.php

function getLastQuery()
    $dbo = $this->getDatasource();
    $logs = $dbo->getLog();
    $lastLog = end($logs['log']);
    return $lastLog['query'];

To use this in Controller Write : echo $this->YourModelName->getLastQuery();

How do I vertically center an H1 in a div?

Just use padding top and bottom, it will automatically center the content vertically.

How do you get an iPhone's device name

For xamarin user, use this


Connection refused on docker container

If you are using Docker toolkit on window 10 home you will need to access the webpage through docker-machine ip command. It is generally

It is assumed that you are running with publish command like below.

docker run -it -p 8080:8080 demo

With Window 10 pro version you can access with localhost or corresponding loopback etc (Tomcat or whatever you wish). This is because you don't have a virtual box there and docker is running directly on Window Hyper V and loopback is directly accessible.

Verify the hosts file in window for any digression. It should have mapped to localhost

Is there a difference between "==" and "is"?

They are completely different. is checks for object identity, while == checks for equality (a notion that depends on the two operands' types).

It is only a lucky coincidence that "is" seems to work correctly with small integers (e.g. 5 == 4+1). That is because CPython optimizes the storage of integers in the range (-5 to 256) by making them singletons. This behavior is totally implementation-dependent and not guaranteed to be preserved under all manner of minor transformative operations.

For example, Python 3.5 also makes short strings singletons, but slicing them disrupts this behavior:

>>> "foo" + "bar" == "foobar"
>>> "foo" + "bar" is "foobar"
>>> "foo"[:] + "bar" == "foobar"
>>> "foo"[:] + "bar" is "foobar"

Android - get children inside a View?

I'm just going to provide this answer as an alternative @IHeartAndroid's recursive algorithm for discovering all child Views in a view hierarchy. Note that at the time of this writing, the recursive solution is flawed in that it will contains duplicates in its result.

For those who have trouble wrapping their head around recursion, here's a non-recursive alternative. You get bonus points for realizing this is also a breadth-first search alternative to the depth-first approach of the recursive solution.

private List<View> getAllChildrenBFS(View v) {
    List<View> visited = new ArrayList<View>();
    List<View> unvisited = new ArrayList<View>();

    while (!unvisited.isEmpty()) {
        View child = unvisited.remove(0);
        if (!(child instanceof ViewGroup)) continue;
        ViewGroup group = (ViewGroup) child;
        final int childCount = group.getChildCount();
        for (int i=0; i<childCount; i++) unvisited.add(group.getChildAt(i));

    return visited;

A couple of quick tests (nothing formal) suggest this alternative is also faster, although that has most likely to do with the number of new ArrayList instances the other answer creates. Also, results may vary based on how vertical/horizontal the view hierarchy is.

Cross-posted from: Android | Get all children elements of a ViewGroup

How do I break a string across more than one line of code in JavaScript?

ECMAScript 6 introduced template strings:

Template strings are string literals allowing embedded expressions. You can use multi-line strings and string interpolation features with them.

For example:

alert(`Please Select file   
to delete`);

will alert:

Please Select file   
to delete

How to convert the time from AM/PM to 24 hour format in PHP?

$Hour1 = "09:00 am";
$Hour =  date("H:i", strtotime($Hour1));  

Key hash for Android-Facebook app

1) Create a key to sign your application, and remember the alias.

2) Install OpenSSL.

3) Put the bin folder of OpenSSL in your path.

4) Follow the steps mentioned under "Setup Single Sign-On" on the FB-Android-SDK page, and generate your Hash Key. Make sure you put the correct alias and keystore file name.

5) Create an application on Facebok, and under Mobile Devices tab, enter this Hash Key.

twitter bootstrap autocomplete dropdown / combobox with Knockoutjs

Does the basic HTML5 datalist work? It's clean and you don't have to play around with the messy third party code. W3SCHOOL tutorial

The MDN Documentation is very eloquent and features examples.

How can I detect keydown or keypress event in angular.js?

JavaScript code using ng-controller:

$scope.checkkey = function (event) {
  alert(event.keyCode);  //this will show the ASCII value of the key pressed



<input type="text" ng-keypress="checkkey($event)" />

You can now place your checks and other conditions using the keyCode method.

Sending data back to the Main Activity in Android

There are some ways of doing this. 1. by using the startActivityForResult() which is very well explained in the above answers.

  1. by creating the static variables in your "Utils" class or any other class of your own. For example i want to pass studentId from ActivityB to ActivityA.First my ActivityA is calling the ActivityB. Then inside ActivityB set the studentId (which is a static field in Utils.class). Like this Utils.STUDENT_ID="1234"; then while comming back to the ActivityA use the studentId which is stored in Utils.STUDENT_ID.

  2. by creating a getter and setter method in your Application Class.

like this:

public class MyApplication extends Application {

    private static MyApplication instance = null;
    private String studentId="";

    public static MyApplication getInstance() {
        return instance;

    public void onCreate() {
        instance = this;

    public void setStudentId(String studentID){

    public String getStudentId(){
        return this.studentId;

so you are done . just set the data inside when u are in ActivityB and after comming back to ActivityA , get the data.