Programs & Examples On #Fractals

Fractals are interesting mathematical objects with a special behaviour in a complex-plane [Re, Im], depending on their initial position ( location ). Visualised in popular media, typically as shapes with infinite dimensionality that exhibit a sort of self-similarity. Well-known fractal sets include the named Mandelbrot set, Julia sets, and Phoenix sets. Tree-like fractal drawings are also common.

How to program a fractal?

Here is a codepen that I wrote for the Mandelbrot fractal using plain javascript and HTML.

Hopefully it is easy to understand the code.

The most complicated part is scale and translate the coordinate systems. Also complicated is making the rainbow palette.

function mandel(x,y) {
  var a=0; var b=0;
  for (i = 0; i<250; ++i) {
    // Complex z = z^2 + c
    var t = a*a - b*b;
    b = 2*a*b;
    a = t;
    a = a + x;
    b = b + y;
    var m = a*a + b*b;
    if (m > 10)  return i;
  return 250;

enter image description here

What is the C# equivalent of friend?

There's no direct equivalent of "friend" - the closest that's available (and it isn't very close) is InternalsVisibleTo. I've only ever used this attribute for testing - where it's very handy!

Example: To be placed in AssemblyInfo.cs

[assembly: InternalsVisibleTo("OtherAssembly")]

Can I embed a .png image into an html page?

There are a few base64 encoders online to help you with this, this is probably the best I've seen:

As that page shows your main options for this are CSS:

div.image {

Or the <img> tag itself, like this:

<img alt="My Image" src="data:image/png;base64,iVBORwA<MoreBase64SringHere>" />

Clean up a fork and restart it from the upstream

The simplest solution would be (using 'upstream' as the remote name referencing the original repo forked):

git remote add upstream /url/to/original/repo
git fetch upstream
git checkout master
git reset --hard upstream/master  
git push origin master --force 

(Similar to this GitHub page, section "What should I do if I’m in a bad situation?")

Be aware that you can lose changes done on the master branch (both locally, because of the reset --hard, and on the remote side, because of the push --force).

An alternative would be, if you want to preserve your commits on master, to replay those commits on top of the current upstream/master.
Replace the reset part by a git rebase upstream/master. You will then still need to force push.
See also "What should I do if I’m in a bad situation?"

A more complete solution, backing up your current work (just in case) is detailed in "Cleanup git master branch and move some commit to new branch".

See also "Pull new updates from original GitHub repository into forked GitHub repository" for illustrating what "upstream" is.


Note: recent GitHub repos do protect the master branch against push --force.
So you will have to un-protect master first (see picture below), and then re-protect it after force-pushing).

enter image description here

Note: on GitHub specifically, there is now (February 2019) a shortcut to delete forked repos for pull requests that have been merged upstream.

How to retrieve a single file from a specific revision in Git?

Using git show $REV:$FILE as it was already pointed out by others is probably the right answer. I'm posting another answer because when I tried this method, I sometimes got the following error from git:

fatal: path 'link/foo' exists on disk, but not in 'HEAD'

The problem occurs when parts of the path to the file are a symbolic link. In those cases, the git show $REV:$FILE method will not work. Steps to reproduce:

$ git init .
$ mkdir test
$ echo hello > test/foo
$ ln -s test link
$ git add .
$ git commit -m "initial commit"
$ cat link/foo
$ git show HEAD:link/foo
fatal: path 'link/foo' exists on disk, but not in 'HEAD'

The problem is, that utilities like realpath don't help here, because the symlink might not exist in the current commit anymore. I don't know about a good general solution. In my case, I knew that the symlink could only exist in the first component of the path, so I solved the problem by using the git show $REV:$FILE method twice. This works, because when git show $REV:$FILE is used on a symlink, then its target gets printed:

$ git show HEAD:link

Whereas with directories, the command will output a header, followed by the directory content:

$ git show HEAD:test
tree HEAD:test


So in my case, I just checked the output of the first call to git show $REV:$FILE and if it was only a single line, then I replaced the first component of my path with the result to resolve the symlink through git.

How to get value from form field in django framework?

It is easy if you are using django version 3.1 and above

def login_view(request):
        yourForm= YourForm(request.POST)
        itemValue = yourForm['your_filed_name'].value()
        # Check if you get the value
        return HttpResponse(itemValue )
        return render(request, "base.html")

Reading from memory stream to string

If you'd checked the results of stream.Read, you'd have seen that it hadn't read anything - because you haven't rewound the stream. (You could do this with stream.Position = 0;.) However, it's easier to just call ToArray:

settingsString = LocalEncoding.GetString(stream.ToArray());

(You'll need to change the type of stream from Stream to MemoryStream, but that's okay as it's in the same method where you create it.)

Alternatively - and even more simply - just use StringWriter instead of StreamWriter. You'll need to create a subclass if you want to use UTF-8 instead of UTF-16, but that's pretty easy. See this answer for an example.

I'm concerned by the way you're just catching Exception and assuming that it means something harmless, by the way - without even logging anything. Note that using statements are generally cleaner than writing explicit finally blocks.

Transferring files over SSH

No, you still need to scp [from] [to] whichever way you're copying

The difference is, you need to scp -p server:serverpath localpath

specifying goal in pom.xml

I ran into this when trying to run spring boot from the command line...

mvn spring-boot:run

I accidentally mis-typed the command as...

mvn spring-boot run

So it was looking for the commands... run, build etc...

Redirect to external URL with return in laravel

You should be able to redirect to the url like this

return Redirect::to($url);

You can read about Redirects in the Laravel docs here.

How to specify function types for void (not Void) methods in Java8?

When you need to accept a function as argument which takes no arguments and returns no result (void), in my opinion it is still best to have something like

  public interface Thunk { void apply(); }

somewhere in your code. In my functional programming courses the word 'thunk' was used to describe such functions. Why it isn't in java.util.function is beyond my comprehension.

In other cases I find that even when java.util.function does have something that matches the signature I want - it still doesn't always feel right when the naming of the interface doesn't match the use of the function in my code. I guess it's a similar point that is made elsewhere here regarding 'Runnable' - which is a term associated with the Thread class - so while it may have he signature I need, it is still likely to confuse the reader.

Write variable to file, including name

The default string representation for a dictionary seems to be just right:

>>> a={3: 'foo', 17: 'bar' }
>>> a
{17: 'bar', 3: 'foo'}
>>> print a
{17: 'bar', 3: 'foo'}
>>> print "a=", a
a= {17: 'bar', 3: 'foo'}

Not sure if you can get at the "variable name", since variables in Python are just labels for values. See this question.

Android: Expand/collapse animation

I adapted the currently accepted answer by Tom Esterez, which worked but had a choppy and not very smooth animation. My solution basically replaces the Animation with a ValueAnimator, which can be fitted with an Interpolator of your choice to achieve various effects such as overshoot, bounce, accelerate, etc.

This solution works great with views that have a dynamic height (i.e. using WRAP_CONTENT), as it first measures the actual required height and then animates to that height.

public static void expand(final View v) {
    v.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    final int targetHeight = v.getMeasuredHeight();

    // Older versions of android (pre API 21) cancel animations for views with a height of 0.
    v.getLayoutParams().height = 1;

    ValueAnimator va = ValueAnimator.ofInt(1, targetHeight);
    va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        public void onAnimationUpdate(ValueAnimator animation) {
            v.getLayoutParams().height = (Integer) animation.getAnimatedValue();
    va.addListener(new Animator.AnimatorListener() {
        public void onAnimationEnd(Animator animation) {
            v.getLayoutParams().height = ViewGroup.LayoutParams.WRAP_CONTENT;

        @Override public void onAnimationStart(Animator animation) {}
        @Override public void onAnimationCancel(Animator animation) {}
        @Override public void onAnimationRepeat(Animator animation) {}
    va.setInterpolator(new OvershootInterpolator());

public static void collapse(final View v) {
    final int initialHeight = v.getMeasuredHeight();

    ValueAnimator va = ValueAnimator.ofInt(initialHeight, 0);
    va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        public void onAnimationUpdate(ValueAnimator animation) {
            v.getLayoutParams().height = (Integer) animation.getAnimatedValue();
    va.addListener(new Animator.AnimatorListener() {
        public void onAnimationEnd(Animator animation) {

        @Override public void onAnimationStart(Animator animation) {}
        @Override public void onAnimationCancel(Animator animation) {}
        @Override public void onAnimationRepeat(Animator animation) {}
    va.setInterpolator(new DecelerateInterpolator());

You then simply call expand( myView ); or collapse( myView );.


You could have used DISTINCT or just remove the PARTITION BY portions and use GROUP BY:

       ,TotalICount = SUM(ICount) OVER ()    
       ,Percentage = SUM(ICount) OVER ()*1.0 / SUM(ICount) 
FROM Table 
WHERE DateId  = 20130618

Not sure why you are dividing the total by the count per BrandID, if that's a mistake and you want percent of total then reverse those bits above to:

           ,TotalICount = SUM(ICount) OVER ()    
           ,Percentage = SUM(ICount)*1.0 / SUM(ICount) OVER () 
    FROM Table 
    WHERE DateId  = 20130618
    GROUP BY BrandID

Int to Char in C#


for example:

Console.WriteLine("(char)122 is {0}", (char)122);


(char)122 is z

Targeting .NET Framework 4.5 via Visual Studio 2010

There are pretty limited scenarios that I can think of where this would be useful, but let's assume you can't get funds to purchase VS2012 or something to that effect. If that's the case and you have Windows 7+ and VS 2010 you may be able to use the following hack I put together which seems to work (but I haven't fully deployed an application using this method yet).

  1. Backup your project file!!!

  2. Download and install the Windows 8 SDK which includes the .NET 4.5 SDK.

  3. Open your project in VS2010.

  4. Create a text file in your project named Compile_4_5_CSharp.targets with the following contents. (Or just download it here - Make sure to remove the ".txt" extension from the file name):

    <Project DefaultTargets="Build"
        <!-- Change the target framework to 4.5 if using the ".NET 4.5" configuration -->
        <PropertyGroup Condition=" '$(Platform)' == '.NET 4.5' ">
            <DefineConstants Condition="'$(DefineConstants)'==''">
            <DefineConstants Condition="'$(DefineConstants)'!='' and '$(DefineConstants)'!='TARGETTING_FX_4_5'">
            <PlatformTarget Condition="'$(PlatformTarget)'!=''"/>
        <!-- Import the standard C# targets -->
        <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
        <!-- Add .NET 4.5 as an available platform -->
           <AvailablePlatforms>$(AvailablePlatforms),.NET 4.5</AvailablePlatforms>
  5. Unload your project (right click -> unload).

  6. Edit the project file (right click -> Edit *.csproj).

  7. Make the following changes in the project file:

    a. Replace the default Microsoft.CSharp.targets with the target file created in step 4

    <!-- Old Import Entry -->
    <!-- <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" /> -->
    <!-- New Import Entry -->
    <Import Project="Compile_4_5_CSharp.targets" />

    b. Change the default platform to .NET 4.5

    <!-- Old default platform entry -->
    <!-- <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform> -->
    <!-- New default platform entry -->
    <Platform Condition=" '$(Platform)' == '' ">.NET 4.5</Platform>

    c. Add AnyCPU platform to allow targeting other frameworks as specified in the project properties. This should be added just before the first <ItemGroup> tag in the file

    <PropertyGroup Condition="'$(Platform)' == 'AnyCPU'">
  8. Save your changes and close the *.csproj file.

  9. Reload your project (right click -> Reload Project).

  10. In the configuration manager (Build -> Configuration Manager) make sure the ".NET 4.5" platform is selected for your project.

  11. Still in the configuration manager, create a new solution platform for ".NET 4.5" (you can base it off "Any CPU") and make sure ".NET 4.5" is selected for the solution.

  12. Build your project and check for errors.

  13. Assuming the build completed you can verify that you are indeed targeting 4.5 by adding a reference to a 4.5 specific class to your source code:

    using System;
    using System.Text;
    namespace testing
        using net45check = System.Reflection.ReflectionContext;
  14. When you compile using the ".NET 4.5" platform the build should succeed. When you compile under the "Any CPU" platform you should get a compiler error:

    Error 6: The type or namespace name 'ReflectionContext' does not exist in
    the namespace 'System.Reflection' (are you missing an assembly reference?)

How to get the last value of an ArrayList

The last item in the list is list.size() - 1. The collection is backed by an array and arrays start at index 0.

So element 1 in the list is at index 0 in the array

Element 2 in the list is at index 1 in the array

Element 3 in the list is at index 2 in the array

and so on..

HTML anchor tag with Javascript onclick event

You can even try below option:

<a href="javascript:show_more_menu();">More >>></a>

How can I set a custom baud rate on Linux?

dougg3 has this pretty much (I can't comment there). The main additional thing you need to know is the headers which don't conflict with each other but do provide the correct prototypes. The answer is

#include <stropts.h>
#include <asm/termios.h>

After that you can use dougg3's code, preferably with error checking round the ioctl() calls. You will probably need to put this in a separate .c file to the rest of your serial port code which uses the normal termios to set other parameters. Doing POSIX manipulations first, then this to set the custom speed, works fine on the built-in UART of the Raspberry Pi to get a 250k baud rate.

Why docker container exits immediately

Add this to the end of Dockerfile:

CMD tail -f /dev/null

Sample Docker file:

FROM ubuntu:16.04

# other commands

CMD tail -f /dev/null


How to Run Terminal as Administrator on Mac Pro

search for terminal after opening the termincal type

su <admin-user-name>   //su - switch user

enter and then give the admin password then run your sudo commands e.g:

sudo open

Rebasing remote branches in Git

You can disable the check (if you're really sure you know what you're doing) by using the --force option to git push.

Creating an Arraylist of Objects

ArrayList<Matrices> list = new ArrayList<Matrices>();
list.add( new Matrices(1,1,10) );
list.add( new Matrices(1,2,20) );

Javascript form validation with password confirming

add this to your form:

<form  id="regform" action="insert.php" method="post">

add this to your function:

    function myFunction() {
        var pass1 = document.getElementById("pass1").value;
        var pass2 = document.getElementById("pass2").value;
        if (pass1 != pass2) {
            //alert("Passwords Do not match");
            document.getElementById("pass1").style.borderColor = "#E34234";
            document.getElementById("pass2").style.borderColor = "#E34234";
        else {
            alert("Passwords Match!!!");

How does Tomcat find the HOME PAGE of my Web App?

I already had index.html in the WebContent folder but it was not showing up , finally i added the following piece of code in my projects web.xml and it started showing up


iOS UIImagePickerController result image orientation after upload

I transposed this into Xamarin:

private static UIImage FixImageOrientation(UIImage image)
        if (image.Orientation == UIImageOrientation.Up)
            return image;

        var transform = CGAffineTransform.MakeIdentity();

        float pi = (float)Math.PI;

        switch (image.Orientation)
            case UIImageOrientation.Down:
            case UIImageOrientation.DownMirrored:
                transform = CGAffineTransform.Translate(transform, image.Size.Width, image.Size.Height);
                transform = CGAffineTransform.Rotate(transform, pi);

            case UIImageOrientation.Left:
            case UIImageOrientation.LeftMirrored:
                transform = CGAffineTransform.Translate(transform, image.Size.Width, 0);
                transform = CGAffineTransform.Rotate(transform, pi / 2);

            case UIImageOrientation.Right:
            case UIImageOrientation.RightMirrored:
                transform = CGAffineTransform.Translate(transform, 0, image.Size.Height);
                transform = CGAffineTransform.Rotate(transform, -(pi / 2));

        switch (image.Orientation)
            case UIImageOrientation.UpMirrored:
            case UIImageOrientation.DownMirrored:
                transform = CGAffineTransform.Translate(transform, image.Size.Width, 0);
                transform = CGAffineTransform.Scale(transform, -1, 1);

            case UIImageOrientation.LeftMirrored:
            case UIImageOrientation.RightMirrored:
                transform = CGAffineTransform.Translate(transform, image.Size.Height, 0);
                transform = CGAffineTransform.Scale(transform, -1, 1);

        var ctx = new CGBitmapContext(null, (nint)image.Size.Width, (nint)image.Size.Height, image.CGImage.BitsPerComponent,
            image.CGImage.BytesPerRow, image.CGImage.ColorSpace, image.CGImage.BitmapInfo);


        switch (image.Orientation)
            case UIImageOrientation.Left:
            case UIImageOrientation.LeftMirrored:
            case UIImageOrientation.Right:
            case UIImageOrientation.RightMirrored:
                ctx.DrawImage(new CGRect(0, 0, image.Size.Height, image.Size.Width), image.CGImage);

                ctx.DrawImage(new CGRect(0, 0, image.Size.Width, image.Size.Height), image.CGImage);

        var cgimg = ctx.ToImage();
        var img = new UIImage(cgimg);

        ctx = null;
        cgimg = null;

        return img;

sql server Get the FULL month name from a date

select datename(DAY,GETDATE()) +'-'+ datename(MONTH,GETDATE()) +'- '+ 
       datename(YEAR,GETDATE()) as 'yourcolumnname'

Check if element is in the list (contains)

They really should add a wrapper. Like this:

namespace std
    template<class _container,
        class _Ty> inline
        bool contains(_container _C, const _Ty& _Val)
        {return std::find(_C.begin(), _C.end(), _Val) != _C.end(); }
    if( std::contains(my_container, what_to_find) )


Implementing two interfaces in a class with same method. Which interface method is overridden?

As in interface,we are just declaring methods,concrete class which implements these both interfaces understands is that there is only one method(as you described both have same name in return type). so there should not be an issue with it.You will be able to define that method in concrete class.

But when two interface have a method with the same name but different return type and you implement two methods in concrete class:

Please look at below code:

public interface InterfaceA {
  public void print();

public interface InterfaceB {
  public int print();

public class ClassAB implements InterfaceA, InterfaceB {
  public void print()
    System.out.println("Inside InterfaceA");
  public int print()
    System.out.println("Inside InterfaceB");
    return 5;

when compiler gets method "public void print()" it first looks in InterfaceA and it gets it.But still it gives compile time error that return type is not compatible with method of InterfaceB.

So it goes haywire for compiler.

In this way, you will not be able to implement two interface having a method of same name but different return type.

How to use table variable in a dynamic sql statement?

Your EXEC executes in a different context, therefore it is not aware of any variables that have been declared in your original context. You should be able to use a temp table instead of a table variable as shown in the simple demo below.

create table #t (id int)

declare @value nchar(1)
set @value = N'1'

declare @sql nvarchar(max)
set @sql = N'insert into #t (id) values (' + @value + N')'

exec (@sql)

select * from #t

drop table #t

How to detect IE11?

IE11 no longer reports as MSIE, according to this list of changes it's intentional to avoid mis-detection.

What you can do if you really want to know it's IE is to detect the Trident/ string in the user agent if navigator.appName returns Netscape, something like (the untested);

function getInternetExplorerVersion()_x000D_
  var rv = -1;_x000D_
  if (navigator.appName == 'Microsoft Internet Explorer')_x000D_
    var ua = navigator.userAgent;_x000D_
    var re = new RegExp("MSIE ([0-9]{1,}[\\.0-9]{0,})");_x000D_
    if (re.exec(ua) != null)_x000D_
      rv = parseFloat( RegExp.$1 );_x000D_
  else if (navigator.appName == 'Netscape')_x000D_
    var ua = navigator.userAgent;_x000D_
    var re  = new RegExp("Trident/.*rv:([0-9]{1,}[\\.0-9]{0,})");_x000D_
    if (re.exec(ua) != null)_x000D_
      rv = parseFloat( RegExp.$1 );_x000D_
  return rv;_x000D_
console.log('IE version:', getInternetExplorerVersion());

Note that IE11 (afaik) still is in preview, and the user agent may change before release.

Javascript checkbox onChange

Pure javascript:

const checkbox = document.getElementById('myCheckbox')

checkbox.addEventListener('change', (event) => {
  if (event.currentTarget.checked) {
  } else {
    alert('not checked');
My Checkbox: <input id="myCheckbox" type="checkbox" />

How to link an image and target a new window

Assuming you want to show an Image thumbnail which is 50x50 pixels and link to the the actual image you can do

<a href="path/to/image.jpg" alt="Image description" target="_blank" style="display: inline-block; width: 50px; height; 50px; background-image: url('path/to/image.jpg');"></a>

Of course it's best to give that link a class or id and put it in your css

How to convert the background to transparent?

For Photoshop you need to download Photoshop portable.... Load image e press "w" click in image e suave as png or gif....

Proxies with Python 'Requests' module

I share some code how to fetch proxies from the site "" and store data to a file compatible with tools like "Elite Proxy Switcher"(format IP:PORT):

##PROXY_UPDATER - get free proxies from

from lxml.html import fromstring
import requests
from itertools import cycle
import traceback
import re

######################FIND PROXIES#########################################
def get_proxies():
    url = ''
    response = requests.get(url)
    parser = fromstring(response.text)
    proxies = set()
    for i in parser.xpath('//tbody/tr')[:299]:   #299 proxies max
        proxy = ":".join([i.xpath('.//td[1]/text()') 
    return proxies

######################write to file in format   IP:PORT######################
    proxies = get_proxies()
    for proxy in proxies:
    print ("DONE")
    print ("MAJOR ERROR")

How to make the 'cut' command treat same sequental delimiters as one?

This Perl one-liner shows how closely Perl is related to awk:

perl -lane 'print $F[3]' text.txt

However, the @F autosplit array starts at index $F[0] while awk fields start with $1

Ways to save enums in database

If saving enums as strings in the database, you can create utility methods to (de)serialize any enum:

   public static String getSerializedForm(Enum<?> enumVal) {
        String name =;
        // possibly quote value?
        return name;

    public static <E extends Enum<E>> E deserialize(Class<E> enumType, String dbVal) {
        // possibly handle unknown values, below throws IllegalArgEx
        return Enum.valueOf(enumType, dbVal.trim());

    // Sample use:
    String dbVal = getSerializedForm(Suit.SPADE);
    // save dbVal to db in larger insert/update ...
    Suit suit = deserialize(Suit.class, dbVal);

How to uninstall Jenkins?

There is no uninstaller. Therefore, you need to:

  • Delete the directory containing Jenkins (or, if you're deploying the war -- remove the war from your container).

  • Remove ~/.jenkins.

  • Remove you startup scripts.

What is wrong with my SQL here? #1089 - Incorrect prefix key

according to the latest version of MySQL (phpMyAdmin), add a correct INDEX while choosing primary key. for example: id[int] INDEX 0 ,if id is your primary key and at the first index. Or,

For your problem try this one

CREATE TABLE `table`.`users` (
    `username` VARCHAR(50) NOT NULL,
    `password` VARCHAR(50) NOT NULL,
    `dir` VARCHAR(100) NOT NULL,
    PRIMARY KEY (`id`)

Scala best way of turning a Collection into a Map-by-key?

Another solution (might not work for all types)

import scala.collection.breakOut
val m:Map[P, T] = => (t.getP, t))(breakOut)

this avoids the creation of the intermediary list, more info here: Scala 2.8 breakOut

Android custom dropdown/popup menu

Update: To create a popup menu in android with Kotlin refer my answer here.

To create a popup menu in android with Java:

Create a layout file activity_main.xml under res/layout directory which contains only one button.

Filename: activity_main.xml

<RelativeLayout xmlns:android=""  
    tools:context=".MainActivity" >  

        android:text="Show Popup" />  


Create a file popup_menu.xml under res/menu directory

It contains three items as shown below.

Filename: poupup_menu.xml

<menu xmlns:android="" >  





MainActivity class which displays the popup menu on button click.


public class MainActivity extends Activity {  
    private Button button1;  

    protected void onCreate(Bundle savedInstanceState) {

        button1 = (Button) findViewById(;
        button1.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                //Creating the instance of PopupMenu
                PopupMenu popup = new PopupMenu(MainActivity.this, button1);
                //Inflating the Popup using xml file
                    .inflate(, popup.getMenu());

                //registering popup with OnMenuItemClickListener
                popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                    public boolean onMenuItemClick(MenuItem item) {
                            "You Clicked : " + item.getTitle(),
                        return true;

      ; //showing popup menu
        }); //closing the setOnClickListener method

To add programmatically:

PopupMenu menu = new PopupMenu(this, view);


Follow this link for creating menu programmatically.

DateTime's representation in milliseconds?

You're probably trying to convert to a UNIX-like timestamp, which are in UTC:

    new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)

This also avoids summertime issues, since UTC doesn't have those.

Upload File With Ajax XmlHttpRequest

  1. There is no such thing as xhr.file = file;; the file object is not supposed to be attached this way.
  2. xhr.send(file) doesn't send the file. You have to use the FormData object to wrap the file into a multipart/form-data post data object:

    var formData = new FormData();
    formData.append("thefile", file);

After that, the file can be access in $_FILES['thefile'] (if you are using PHP).

Remember, MDC and Mozilla Hack demos are your best friends.

EDIT: The (2) above was incorrect. It does send the file, but it would send it as raw post data. That means you would have to parse it yourself on the server (and it's often not possible, depend on server configuration). Read how to get raw post data in PHP here.

Error:Unable to locate adb within SDK in Android Studio

It will be happen when

not enough space

available for adb to start emulator.

Just free some space (6 GB) in SDK parent directory.

If Dose not work so go and test other ways that mentioned here.

Redirect using AngularJS

Check your routing method:

if your routing state is like this

 .state('app.register', {
    url: '/register',
    views: {
      'menuContent': {
        templateUrl: 'templates/register.html',

then you should use


Javascript Array Alert

If you want to see the array as an array, you can say


instead of all those document.writes.

However, if you want to display them cleanly, one per line, in your popup, do this:


How to ssh from within a bash script?

What you need to do is to exchange the SSH keys for the user the script runs as. Have a look at this tutorial

After doing so, your scripts will run without the need for entering a password. But, for security's sake, you don't want to do this for root users!

How to bring back "Browser mode" in IE11?

While using virtual machines is the best way of testing old IEs, it is possible to bring back old-fashioned F12 tools by editing registry as IE11 overwrites this value when new F12 tool is activated.

Thanks to awesome Dimitri Nickola? for this trick. enter image description here

This works for me (save as .reg file and run):

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Toolbar\WebBrowser]

How to Avoid Response.End() "Thread was being aborted" Exception during the Excel file download

Just put the


within a finally block instead of within the try block.

This has worked for me!!!.

I had the following problematic (with the Exception) code structure

 if (something){






and it throws the exception. I suspect the Exception is thrown where there is code / work to execute after response.End(); . In my case the extra code was just the return itself.

When I just moved the response.End(); to the finally block (and left the return in its place - which causes skipping the rest of code in the try block and jumping to the finally block (not just exiting the containing function) ) the Exception ceased to take place.

The following works OK:

 if (something){






html5 localStorage error with Safari: "QUOTA_EXCEEDED_ERR: DOM Exception 22: An attempt was made to add something to storage that exceeded the quota."

The accepted answer seems not adequate in several situations.

To check whether the localStorage or sessionStorage are supported, I use the following snippet from MDN.

function storageAvailable(type) {
    var storage;
    try {
        storage = window[type];
        var x = '__storage_test__';
        storage.setItem(x, x);
        return true;
    catch(e) {
        return e instanceof DOMException && (
            // everything except Firefox
            e.code === 22 ||
            // Firefox
            e.code === 1014 ||
            // test name field too, because code might not be present
            // everything except Firefox
   === 'QuotaExceededError' ||
            // Firefox
            // acknowledge QuotaExceededError only if there's something already stored
            (storage && storage.length !== 0);

Use this snippet like this, and fallback to, for example, using cookie:

if (storageAvailable('localStorage')) {
  // Yippee! We can use localStorage awesomeness
else {
  // Too bad, no localStorage for us
  document.cookie = key + "=" + encodeURIComponent(value) + expires + "; path=/";

I have made the fallbackstorage package which uses this snippet to check for the storage availability and fallback to a manually implemented MemoryStorage.

import {getSafeStorage} from 'fallbackstorage'

getSafeStorage().setItem('test', '1') // always work

Eslint: How to disable "unexpected console statement" in Node.js?

My 2 cents contribution:

Besides removing the console warning (as shown above), it's best to remove yours logs from PROD environments (for security reasons). The best way I found to do so, is by adding this to nuxt.config.js

  build: {
   terser: {
      terserOptions: {
        compress: {
          //this removes console.log from production environment
          drop_console: true

How it works: Nuxt already uses terser as minifier. This config will force terser to ignore/remove all console logs commands during compression.

How should I load files into my Java application?

getResource is fine, but using relative paths will work just as well too, as long as you can control where your working directory is (which you usually can).

Furthermore the platform dependence regarding the separator character can be gotten around using File.separator, File.separatorChar, or System.getProperty("file.separator").

Adjust plot title (main) position

To summarize and explain visually how it works. Code construction is as follows:

par(mar = c(3,2,2,1))
barplot(...all parameters...)
title("Title text", adj = 0.5, line = 0)


par(mar = c(low, left, top, right)) - margins of the graph area.

title("text" - title text
      adj  = from left (0) to right (1) with anything in between: 0.1, 0.2, etc...
      line = positive values move title text up, negative - down)

enter image description here

Getting URL

Facebook uses's services to shorten links from their site. While pages that have a username turns into "<username>", other links associated with Facebook turns into "*****". To you use the service, just use your account. Note that if you change the default link shortener on your account to from this service won't work.

Multiple definition of ... linker error

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

In config.h

extern const char *names[];

In some .c file:

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

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

Showing loading animation in center of page while making a call to Action method in ASP .NET MVC

I defined two functions in Site.Master:

    <script type="text/javascript">
    var spinnerVisible = false;
    function showProgress() {
        if (!spinnerVisible) {
            spinnerVisible = true;
    function hideProgress() {
        if (spinnerVisible) {
            var spinner = $("div#spinner");
            spinnerVisible = false;

And special section:

    <div id="spinner">

Visual style is defined in CSS:

    display: none;
    height: 100px;
    position: fixed;
    top: 50%;
    left: 50%;
    background:url(spinner.gif) no-repeat center #fff;
    font:normal 16px Tahoma, Geneva, sans-serif;
    border:1px solid #666;
    margin-left: -50px;
    margin-top: -50px;
    overflow: auto;

Why does C# XmlDocument.LoadXml(string) fail when an XML header is included?

Simple and effective solution: Instead of using the LoadXml() method use the Load() method

For example:

XmlDocument xmlDoc = new XmlDocument();

Convert a JSON string to object in Java ME?

Like many stated already, A pretty simple way to do this using JSON.simple as below

import org.json.JSONObject;

String someJsonString = "{name:"MyNode", width:200, height:100}";
JSONObject jsonObj = new JSONObject(someJsonString);

And then use jsonObj to deal with JSON Object. e.g jsonObj.get("name");

As per the below link, JSON.simple is showing constant efficiency for both small and large JSON files

instanceof Vs getClass( )

The reason that the performance of instanceof and getClass() == ... is different is that they are doing different things.

  • instanceof tests whether the object reference on the left-hand side (LHS) is an instance of the type on the right-hand side (RHS) or some subtype.

  • getClass() == ... tests whether the types are identical.

So the recommendation is to ignore the performance issue and use the alternative that gives you the answer that you need.

Is using the instanceOf operator bad practice ?

Not necessarily. Overuse of either instanceOf or getClass() may be "design smell". If you are not careful, you end up with a design where the addition of new subclasses results in a significant amount of code reworking. In most situations, the preferred approach is to use polymorphism.

However, there are cases where these are NOT "design smell". For example, in equals(Object) you need to test the actual type of the argument, and return false if it doesn't match. This is best done using getClass().

Terms like "best practice", "bad practice", "design smell", "antipattern" and so on should be used sparingly and treated with suspicion. They encourage black-or-white thinking. It is better to make your judgements in context, rather than based purely on dogma; e.g. something that someone said is "best practice". I recommend that everyone read No Best Practices if they haven't already done so.

Close Android Application


This code kill the process from OS Using this code disturb the OS. So I would recommend you to use the below code

Intent intent = new Intent(Intent.ACTION_MAIN);

Conversion failed when converting the nvarchar value ... to data type int

I got this error when I used a where clause which looked at a nvarchar field but didn't use single quotes.

My invalid SQL query looked like this:

SELECT * FROM RandomTable WHERE Id IN (SELECT Id FROM RandomTable WHERE [Number] = 13028533)

This didn't work since the Number column had the data type nvarchar. It wasn't an int as I first thought.

I changed it to:

SELECT * FROM RandomTable WHERE Id IN (SELECT Id FROM RandomTable WHERE [Number] = '13028533')

And it worked.

How disable / remove android activity label and label bar?

If your application theme is AppTheme(or anything else), then in styles.xml add the following code:

<style name="HiddenTitleTheme" parent="AppTheme">
    <item name="windowNoTitle">true</item>
    <item name="windowActionBar">false</item>

Then in manifest file add the following in the activity tag for which you want to disable activity label:


Network usage top/htop on Linux

jnettop is another candidate.

edit: it only shows the streams, not the owner processes.

How to correctly close a feature branch in Mercurial?

imho there are two cases for branches that were forgot to close

Case 1: branch was not merged into default

in this case I update to the branch and do another commit with --close-branch, unfortunatly this elects the branch to become the new tip and hence before pushing it to other clones I make sure that the real tip receives some more changes and others don't get confused about that strange tip.

hg up myBranch
hg commit --close-branch

Case 2: branch was merged into default

This case is not that much different from case 1 and it can be solved by reproducing the steps for case 1 and two additional ones.

in this case I update to the branch changeset, do another commit with --close-branch and merge the new changeset that became the tip into default. the last operation creates a new tip that is in the default branch - HOORAY!

hg up myBranch
hg commit --close-branch
hg up default
hg merge myBranch

Hope this helps future readers.

Facebook Android Generate Key Hash

One line solution to generate for facebook

keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore | openssl sha1 -binary | openssl base64

Valid content-type for XML, HTML and XHTML documents

HTML: text/html, full-stop.

XHTML: application/xhtml+xml, or only if following HTML compatbility guidelines, text/html. See the W3 Media Types Note.

XML: text/xml, application/xml (RFC 2376).

There are also many other media types based around XML, for example application/rss+xml or image/svg+xml. It's a safe bet that any unrecognised but registered ending in +xml is XML-based. See the IANA list for registered media types ending in +xml.

(For unregistered x- types, all bets are off, but you'd hope +xml would be respected.)

SQL Bulk Insert with FIRSTROW parameter skips the following line

To let SQL handle quote escape and everything else do this

FROM  'C:\MyCSV.csv' 
 --FIRSTROW = 2,  --uncomment this if your CSV contains header, so start parsing at line 2

In regards to other answers, here is valuable info as well:

I keep seeing this in all answers: ROWTERMINATOR = '\n'
The \n means LF and it is Linux style EOL

In Windows the EOL is made of 2 chars CRLF so you need ROWTERMINATOR = '\r\n'

enter image description here

enter image description here

jquery (or pure js) simulate enter key pressed for testing

For those who want to do this in pure javascript, look at:

Using standard KeyboardEvent

As Joe comment it, KeyboardEvent is now the standard.

Same example to fire an enter (keyCode 13):

const ke = new KeyboardEvent('keydown', {
    bubbles: true, cancelable: true, keyCode: 13

You can use this page help you to find the right keyboard event.

Outdated answer:

You can do something like (here for Firefox)

var ev = document.createEvent('KeyboardEvent');
// Send key '13' (= enter)
    'keydown', true, true, window, false, false, false, false, 13, 0);

How can I create a copy of an object in Python?

How can I create a copy of an object in Python?

So, if I change values of the fields of the new object, the old object should not be affected by that.

You mean a mutable object then.

In Python 3, lists get a copy method (in 2, you'd use a slice to make a copy):

>>> a_list = list('abc')
>>> a_copy_of_a_list = a_list.copy()
>>> a_copy_of_a_list is a_list
>>> a_copy_of_a_list == a_list

Shallow Copies

Shallow copies are just copies of the outermost container.

list.copy is a shallow copy:

>>> list_of_dict_of_set = [{'foo': set('abc')}]
>>> lodos_copy = list_of_dict_of_set.copy()
>>> lodos_copy[0]['foo'].pop()
>>> lodos_copy
[{'foo': {'b', 'a'}}]
>>> list_of_dict_of_set
[{'foo': {'b', 'a'}}]

You don't get a copy of the interior objects. They're the same object - so when they're mutated, the change shows up in both containers.

Deep copies

Deep copies are recursive copies of each interior object.

>>> lodos_deep_copy = copy.deepcopy(list_of_dict_of_set)
>>> lodos_deep_copy[0]['foo'].add('c')
>>> lodos_deep_copy
[{'foo': {'c', 'b', 'a'}}]
>>> list_of_dict_of_set
[{'foo': {'b', 'a'}}]

Changes are not reflected in the original, only in the copy.

Immutable objects

Immutable objects do not usually need to be copied. In fact, if you try to, Python will just give you the original object:

>>> a_tuple = tuple('abc')
>>> tuple_copy_attempt = a_tuple.copy()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'copy'

Tuples don't even have a copy method, so let's try it with a slice:

>>> tuple_copy_attempt = a_tuple[:]

But we see it's the same object:

>>> tuple_copy_attempt is a_tuple

Similarly for strings:

>>> s = 'abc'
>>> s0 = s[:]
>>> s == s0
>>> s is s0

and for frozensets, even though they have a copy method:

>>> a_frozenset = frozenset('abc')
>>> frozenset_copy_attempt = a_frozenset.copy()
>>> frozenset_copy_attempt is a_frozenset

When to copy immutable objects

Immutable objects should be copied if you need a mutable interior object copied.

>>> tuple_of_list = [],
>>> copy_of_tuple_of_list = tuple_of_list[:]
>>> copy_of_tuple_of_list[0].append('a')
>>> copy_of_tuple_of_list
>>> tuple_of_list
>>> deepcopy_of_tuple_of_list = copy.deepcopy(tuple_of_list)
>>> deepcopy_of_tuple_of_list[0].append('b')
>>> deepcopy_of_tuple_of_list
(['a', 'b'],)
>>> tuple_of_list

As we can see, when the interior object of the copy is mutated, the original does not change.

Custom Objects

Custom objects usually store data in a __dict__ attribute or in __slots__ (a tuple-like memory structure.)

To make a copyable object, define __copy__ (for shallow copies) and/or __deepcopy__ (for deep copies).

from copy import copy, deepcopy

class Copyable:
    __slots__ = 'a', '__dict__'
    def __init__(self, a, b):
        self.a, self.b = a, b
    def __copy__(self):
        return type(self)(self.a, self.b)
    def __deepcopy__(self, memo): # memo is a dict of id's to copies
        id_self = id(self)        # memoization avoids unnecesary recursion
        _copy = memo.get(id_self)
        if _copy is None:
            _copy = type(self)(
                deepcopy(self.a, memo), 
                deepcopy(self.b, memo))
            memo[id_self] = _copy 
        return _copy

Note that deepcopy keeps a memoization dictionary of id(original) (or identity numbers) to copies. To enjoy good behavior with recursive data structures, make sure you haven't already made a copy, and if you have, return that.

So let's make an object:

>>> c1 = Copyable(1, [2])

And copy makes a shallow copy:

>>> c2 = copy(c1)
>>> c1 is c2
>>> c2.b.append(3)
>>> c1.b
[2, 3]

And deepcopy now makes a deep copy:

>>> c3 = deepcopy(c1)
>>> c3.b.append(4)
>>> c1.b
[2, 3]

Index of Currently Selected Row in DataGridView


Here find all about datagridview C# datagridview tutorial


how to check if the input is a number or not in C?

I was struggling with this for awhile, so I thought I'd just add my two cents:

1) Create a separate function to check if an fgets input consists entirely of numbers:

int integerCheck(){
char myInput[4];
fgets(myInput, sizeof(myInput), stdin);
    int counter = 0;
    int i;
    for (i=0; myInput[i]!= '\0'; i++){
        if (isalpha(myInput[i]) != 0){
            if(counter > 0){
                printf("Input error: Please try again. \n ");
                return main();

    return atoi(myInput); 

The above starts a loop through every unit of an fgets input until the ending NULL value. If it comes across a letter or an operator, it adds "1" to the int "counter" which is initially set to 0. Once the counter becomes greater than 0, the nested if statement instructs the loop to print an error message & then restart the program. When the loops completes, if int 'counter' is still the value of 0, it returns the initially inputted integer to be used in the main function ...

2) the main function would be:

int main(void){
unsigned int numberOne;
unsigned int numberTwo;
numberOne = integerCheck();
numberTwo = integerCheck();
return numberOne*numberTwo;


Assuming both integers are inputted correctly, the example provided will yield the result of int "numberOne" multiplied by int "numberTwo". The program will repeat for however long it takes to get two properly inputted integers.

Parse JSON with R

For the record, rjson and RJSONIO do change the file type, but they don't really parse per se. For instance, I receive ugly MongoDB data in JSON format, convert it with rjson or RJSONIO, then use unlist and tons of manual correction to actually parse it into a usable matrix.

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

Thou the above answer is widely accepted and well documented, I found some of the reason to post my answer here :-

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

Here, I dont understand why we are calling InternalUtils.sendEmail ourself. I will explain in my code why we don't need to do that.


So, we have mocked the class which is fine. Now, lets have a look how we need to verify the sendEmail(/..../) method.

public class InternalServiceTest {

    private InternalService.Order order;

    private InternalService internalService;

    public void setup() {
        internalService = new InternalService();

    public void processOrder() throws Exception {



        InternalService.InternalUtils.sendEmail(anyString(), any(String[].class), anyString(), anyString());


These two lines is where the magic is, First line tells the PowerMockito framework that it needs to verify the class it statically mocked. But which method it need to verify ?? Second line tells which method it needs to verify.

InternalService.InternalUtils.sendEmail(anyString(), any(String[].class), anyString(), anyString());

This is code of my class, sendEmail api twice.

public class InternalService {

    public void processOrder(Order order) {
        if (order.isSuccessful()) {
            InternalUtils.sendEmail("", new String[1], "", "");
            InternalUtils.sendEmail("", new String[1], "", "");

    public static class InternalUtils{

        public static void sendEmail(String from, String[]  to, String msg, String body){



    public class Order{

        public boolean isSuccessful(){
            return true;



As it is calling twice you just need to change the verify(times(2))... that's all.

Angular 4: InvalidPipeArgument: '[object Object]' for pipe 'AsyncPipe'

In your MoviesService you should import FirebaseListObservable in order to define return type FirebaseListObservable<any[]>

import { AngularFireDatabase, FirebaseListObservable } from 'angularfire2/database';

then get() method should like this-

get (): FirebaseListObservable<any[]>{
        return this.db.list('/movies');

this get() method will return FirebaseListObervable of movies list

In your MoviesComponent should look like this

export class MoviesComponent implements OnInit {
  movies: any[];

  constructor(private moviesDb: MoviesService) { }

  ngOnInit() {
    this.moviesDb.get().subscribe((snaps) => {
       this.movies = snaps;

Then you can easily iterate through movies without async pipe as movies[] data is not observable type, your html should be this

  li(*ngFor='let movie of movies')
    {{ movie.title }}

if you declear movies as a

movies: FirebaseListObservable<any[]>;

then you should simply call

movies: FirebaseListObservable<any[]>;
ngOnInit() {
    this.movies = this.moviesDb.get();

and your html should be this

  li(*ngFor='let movie of movies | async')
    {{ movie.title }}

How to format JSON in notepad++

Always google so you can locate the latest package for both NPP and NPP Plugins.

I googled "notepad++ 64bit". Downloaded the free latest version at Notepad++ (64-bit) - Free download and software. Installed notepad++ by double-click on npp.?.?.?.Installer.x64.exe, installed the .exe to default Windows 64bit path which is, "C:\Program Files".

Then, I googled "notepad++ 64 json viewer plug". Knowing SourceForge.Net is a renowned download site, downloaded JSToolNpp [email protected]. I unzipped and copied JSMinNPP.dll to notePad++ root dir.

I loaded my newly installed notepad++ 64bit. I went to Settings and selected [import plug-in]. I pointed to the location of JSMinNPP.dll and clicked open.

I reloaded notepad++, went to PlugIns menu. To format one-line json string to multi-line json doc, I clicked JSTool->JSFormat or reverse multi-line json doc to one-line json string by JSTool->JSMin (json-Minified)!

All items are in this picture.

ERROR: SQLSTATE[HY000] [2002] No connection could be made because the target machine actively refused it

I had a similar issue when trying to migrate a Drupal website from one local host to another. From Mac running XAMMP to Windows running WAMP.

This was the error message I kept getting when trying to access the pages of the website.

PDOException: SQLSTATE[HY000] [2002] No connection could be made because the target machine actively refused it. 
in drupal_get_installed_schema_version() (line 155 of C:\wamp\www\chia\includes\

In settings.php, I've changed everything correctly, database name, user and password.

$databases = array (
  'default' => 
  array (
    'default' => 
    array (
      'database' => 'mydatabasename',
      'username' => 'mydbusername',
      'password' => 'mydbpass',
      'host' => 'localhost',
      'port' => '8889',
      'driver' => 'mysql',
      'prefix' => '',

After a couple of hours of mindless google searching I've changed the port to a empty value:

'port' => '',

And after that the site loaded properly.

How to make a link open multiple pages when clicked

I created a bit of a hybrid approach between Paul & Adam's approach:

The link that opens the array of links is already in the html. The jquery just creates the array of links and opens each one when the "open-all" button is clicked:


<ul class="links">
<li><a href=""></a></li>
<li><a href=""></a></li>

<a id="open-all" href="#">OPEN ALL</a>


$(function() { // On DOM content ready...
    var hrefs = [];

    $('.links a').each(function() {
        hrefs.push(this.href); // Store the URLs from the links...

    $('#open-all').click(function() {
        for (var i in hrefs) {
  [i]); // ...that opens each stored link in its own window when clicked...

You can check it out here:

Get list of certificates from the certificate store in C#

X509Store store = new X509Store(StoreName.My, StoreLocation.LocalMachine);


foreach (X509Certificate2 certificate in store.Certificates){

How to assign multiple classes to an HTML container?

Just remove the comma like this:

<article class="column wrapper"> 

'cl' is not recognized as an internal or external command,

I had the same problem and I solved it by switching to MinGW from MSVC2010.

Select the Project Tab from your left pane. Then select the "Target". From there change Qt version to MinGW instead of VC++.

Running MSBuild fails to read SDKToolsPath

We have a winXP build pc, and use Visual Build Pro 6 to build our software. since some of our developers use VS 2010 the project files now contain reference to "tool version 4.0" and from what I can tell, this tells Visual Build it needs to find a sdk7.x somewhere, even though we only build for .NET 3.5. This caused it not to find lc.exe. I tried to fool it by pointing all the macros to the 6.0A sdk that came with VS2008 which is installed on the pc, but that did not work.

I eventually got it working by downloading and installing sdk 7.1. I then created a registry key for 7.0A and pointed the install path to the install path of the 7.1 sdk. now it happily finds a compatible "lc.exe" and all the code compiles fine. I have a feeling I will now also be able to compile .NET 4.0 code even though VS2010 is not installed, but I have not tried that yet.

How do I check particular attributes exist or not in XML?

If your code is dealing with XmlElements objects (rather than XmlNodes) then there is the method XmlElement.HasAttribute(string name).

So if you are only looking for attributes on elements (which it looks like from the OP) then it may be more robust to cast as an element, check for null, and then use the HasAttribute method.

foreach (XmlNode xNode in nodeListName)
  XmlElement xParentEle = xNode.ParentNode as XmlElement;
  if((xParentEle != null) && xParentEle.HasAttribute("split"))
     parentSplit = xParentEle.Attributes["split"].Value;

How to use zIndex in react-native

UPDATE: Supposedly, zIndex has been added to the react-native library. I've been trying to get it to work without success. Check here for details of the fix.

phonegap open link in browser

There are 2 different ways to open URL in android and iphone.

FOR IOS use following code."", '_system');

and for android OS use following code."", {openExternal : true});

Setting a backgroundImage With React Inline Styles

Sometimes your SVG will be inlined by React so you need quotes around it:

     backgroundImage: `url("${Background}")`

otherwise it's invalid CSS and the browser dev tools will not show that you've set background-image at all.

How to skip to next iteration in jQuery.each() util?

The loop only breaks if you return literally false. Ex:

// this is how jquery calls your function
// notice hard comparison (===) against false
if ( obj[ i ], i, obj[ i ] ) === false ) {

This means you can return anything else, including undefined, which is what you return if you return nothing, so you can simply use an empty return statement:

$.each(collection, function (index, item) {
   if (!someTestCondition)
      return; // go to next iteration

   // otherwise do something

It's possible this might vary by version; this is applicable for jquery 1.12.4. But really, when you exit out the bottom of the function, you are also returning nothing, and that's why the loop continues, so I would expect that there is no possibility whatsoever that returning nothing could not continue the loop. Unless they want to force everyone to start returning something to keep the loop going, returning nothing has to be a way to keep it going.

Update select2 data without rebuilding the control

Try this one:

var data = [{id: 1, text: 'First'}, {id: 2, text: 'Second'}, {...}];
    data: data

PowerShell Connect to FTP server and get files

The AlexFTPS library used in the question seems to be dead (was not updated since 2011).

With no external libraries

You can try to implement this without any external library. But unfortunately, neither the .NET Framework nor PowerShell have any explicit support for downloading all files in a directory (let only recursive file downloads).

You have to implement that yourself:

  • List the remote directory
  • Iterate the entries, downloading files (and optionally recursing into subdirectories - listing them again, etc.)

Tricky part is to identify files from subdirectories. There's no way to do that in a portable way with the .NET framework (FtpWebRequest or WebClient). The .NET framework unfortunately does not support the MLSD command, which is the only portable way to retrieve directory listing with file attributes in FTP protocol. See also Checking if object on FTP server is file or directory.

Your options are:

  • If you know that the directory does not contain any subdirectories, use the ListDirectory method (NLST FTP command) and simply download all the "names" as files.
  • Do an operation on a file name that is certain to fail for file and succeeds for directories (or vice versa). I.e. you can try to download the "name".
  • You may be lucky and in your specific case, you can tell a file from a directory by a file name (i.e. all your files have an extension, while subdirectories do not)
  • You use a long directory listing (LIST command = ListDirectoryDetails method) and try to parse a server-specific listing. Many FTP servers use *nix-style listing, where you identify a directory by the d at the very beginning of the entry. But many servers use a different format. The following example uses this approach (assuming the *nix format)
function DownloadFtpDirectory($url, $credentials, $localPath)
    $listRequest = [Net.WebRequest]::Create($url)
    $listRequest.Method = [System.Net.WebRequestMethods+Ftp]::ListDirectoryDetails
    $listRequest.Credentials = $credentials

    $lines = New-Object System.Collections.ArrayList

    $listResponse = $listRequest.GetResponse()
    $listStream = $listResponse.GetResponseStream()
    $listReader = New-Object System.IO.StreamReader($listStream)
    while (!$listReader.EndOfStream)
        $line = $listReader.ReadLine()
        $lines.Add($line) | Out-Null

    foreach ($line in $lines)
        $tokens = $line.Split(" ", 9, [StringSplitOptions]::RemoveEmptyEntries)
        $name = $tokens[8]
        $permissions = $tokens[0]

        $localFilePath = Join-Path $localPath $name
        $fileUrl = ($url + $name)

        if ($permissions[0] -eq 'd')
            if (!(Test-Path $localFilePath -PathType container))
                Write-Host "Creating directory $localFilePath"
                New-Item $localFilePath -Type directory | Out-Null

            DownloadFtpDirectory ($fileUrl + "/") $credentials $localFilePath
            Write-Host "Downloading $fileUrl to $localFilePath"

            $downloadRequest = [Net.WebRequest]::Create($fileUrl)
            $downloadRequest.Method = [System.Net.WebRequestMethods+Ftp]::DownloadFile
            $downloadRequest.Credentials = $credentials

            $downloadResponse = $downloadRequest.GetResponse()
            $sourceStream = $downloadResponse.GetResponseStream()
            $targetStream = [System.IO.File]::Create($localFilePath)
            $buffer = New-Object byte[] 10240
            while (($read = $sourceStream.Read($buffer, 0, $buffer.Length)) -gt 0)
                $targetStream.Write($buffer, 0, $read);

Use the function like:

$credentials = New-Object System.Net.NetworkCredential("user", "mypassword") 
$url = ""
DownloadFtpDirectory $url $credentials "C:\target\directory"

The code is translated from my C# example in C# Download all files and subdirectories through FTP.

Using 3rd party library

If you want to avoid troubles with parsing the server-specific directory listing formats, use a 3rd party library that supports the MLSD command and/or parsing various LIST listing formats. And ideally with a support for downloading all files from a directory or even recursive downloads.

For example with WinSCP .NET assembly you can download whole directory with a single call to Session.GetFiles:

# Load WinSCP .NET assembly
Add-Type -Path "WinSCPnet.dll"

# Setup session options
$sessionOptions = New-Object WinSCP.SessionOptions -Property @{
    Protocol = [WinSCP.Protocol]::Ftp
    HostName = ""
    UserName = "user"
    Password = "mypassword"

$session = New-Object WinSCP.Session

    # Connect

    # Download files
    $session.GetFiles("/directory/to/download/*", "C:\target\directory\*").Check()
    # Disconnect, clean up

Internally, WinSCP uses the MLSD command, if supported by the server. If not, it uses the LIST command and supports dozens of different listing formats.

The Session.GetFiles method is recursive by default.

(I'm the author of WinSCP)

Error: Address already in use while binding socket with address but the port number is shown free by `netstat`

Even icfantv's answer to this question is already perfect, I still have more findings in my test.

As a server socket in listening status, if it only in listening status, and even it accepts request and getting data from the client side, but without any data sending action. We still could restart the server at once after it's stopped. But if any data sending action happens in the server side to the client, the same service(same port) restart will have this error: (Address already in use).

I think this is caused by the TCP/IP design principles. When the server send the data back to client, it must ensure the data sending succeed, in order to do this, the OS(Linux) need monitor the connection even the server application closed this socket. But I still believe kernel socket designer could improve this issue.

Fastest way(s) to move the cursor on a terminal command line?

Hold down the Option key and click where you'd like the cursor to move, and Terminal rushes the cursor that precise spot.

Does Java have a path joining method?


String path1 = "path1";
String path2 = "path2";

String joinedPath = new File(path1, path2).toString();

Best radio-button implementation for IOS

Try DLRadioButton, works for both Swift and ObjC. You can also use images to indicate selection status or customize your own style.

Check it out at GitHub.

radio button for iOS

**Update: added the option for putting selection indicator on the right side.

**Update: added square button, IBDesignable, improved performance.

**Update: added multiple selection support.

Is the Javascript date object always one day off?

This through me for a loop, +1 on zzzBov's answer. Here is a full conversion of a date that worked for me using the UTC methods:

//myMeeting.MeetingDate = '2015-01-30T00:00:00'

var myDate = new Date(myMeeting.MeetingDate);
//convert to JavaScript date format
//returns date of 'Thu Jan 29 2015 19:00:00 GMT-0500 (Eastern Standard Time)' <-- One Day Off!

myDate = new Date(myDate.getUTCFullYear(), myDate.getUTCMonth(), myDate.getUTCDate());
//returns date of 'Fri Jan 30 2015 00:00:00 GMT-0500 (Eastern Standard Time)' <-- Correct Date!

How can I give access to a private GitHub repository?

Your team members must be accessing the repository using SSH & for that they have to have their ssh key mapped with github account. This will work if they map their ssh key with github account and also the repository has public rights, which they want to access.

Convert char to int in C and C++

I have absolutely null skills in C, but for a simple parsing:

char* something = "123456";

int number = parseInt(something);

...this worked for me:

int parseInt(char* chars)
    int sum = 0;
    int len = strlen(chars);
    for (int x = 0; x < len; x++)
        int n = chars[len - (x + 1)] - '0';
        sum = sum + powInt(n, x);
    return sum;

int powInt(int x, int y)
    for (int i = 0; i < y; i++)
        x *= 10;
    return x;

How to include CSS file in Symfony 2 and Twig?

You are doing everything right, except passing your bundle path to asset() function.

According to documentation - in your example this should look like below:

{{ asset('bundles/webshome/css/main.css') }}

Tip: you also can call assets:install with --symlink key, so it will create symlinks in web folder. This is extremely useful when you often apply js or css changes (in this way your changes, applied to src/YouBundle/Resources/public will be immediately reflected in web folder without need to call assets:install again):

app/console assets:install web --symlink

Also, if you wish to add some assets in your child template, you could call parent() method for the Twig block. In your case it would be like this:

{% block stylesheets %}
    {{ parent() }}

    <link href="{{ asset('bundles/webshome/css/main.css') }}" rel="stylesheet">
{% endblock %}

Eclipse - Failed to load class "org.slf4j.impl.StaticLoggerBinder"

Did you update the project (right-click on the project, "Maven" > "Update project...")? Otherwise, you need to check if pom.xml contains the necessary slf4j dependencies, e.g.:


nodejs module.js:340 error: cannot find module

I executed following command and it works for me.

PM> npm install ee-first [email protected] node_modules\ee-first

PHP - Failed to open stream : No such file or directory

To add to the (really good) existing answer

Shared Hosting Software

open_basedir is one that can stump you because it can be specified in a web server configuration. While this is easily remedied if you run your own dedicated server, there are some shared hosting software packages out there (like Plesk, cPanel, etc) that will configure a configuration directive on a per-domain basis. Because the software builds the configuration file (i.e. httpd.conf) you cannot change that file directly because the hosting software will just overwrite it when it restarts.

With Plesk, they provide a place to override the provided httpd.conf called vhost.conf. Only the server admin can write this file. The configuration for Apache looks something like this

<Directory /var/www/vhosts/>
    <IfModule mod_php5.c>
        php_admin_flag engine on
        php_admin_flag safe_mode off
        php_admin_value open_basedir "/var/www/vhosts/"

Have your server admin consult the manual for the hosting and web server software they use.

File Permissions

It's important to note that executing a file through your web server is very different from a command line or cron job execution. The big difference is that your web server has its own user and permissions. For security reasons that user is pretty restricted. Apache, for instance, is often apache, www-data or httpd (depending on your server). A cron job or CLI execution has whatever permissions that the user running it has (i.e. running a PHP script as root will execute with permissions of root).

A lot of times people will solve a permissions problem by doing the following (Linux example)

chmod 777 /path/to/file

This is not a smart idea, because the file or directory is now world writable. If you own the server and are the only user then this isn't such a big deal, but if you're on a shared hosting environment you've just given everyone on your server access.

What you need to do is determine the user(s) that need access and give only those them access. Once you know which users need access you'll want to make sure that

  1. That user owns the file and possibly the parent directory (especially the parent directory if you want to write files). In most shared hosting environments this won't be an issue, because your user should own all the files underneath your root. A Linux example is shown below

     chown apache:apache /path/to/file
  2. The user, and only that user, has access. In Linux, a good practice would be chmod 600 (only owner can read and write) or chmod 644 (owner can write but everyone can read)

You can read a more extended discussion of Linux/Unix permissions and users here

join on multiple columns

Below is the structure of SQL that you may write. You can do multiple joins by using "AND" or "OR".

Select TableA.Col1, TableA.Col2, TableB.Val
FROM TableA, 
 ON TableA.Col1 = TableB.Col1 OR TableA.Col2 = TableB.Col2

Case in Select Statement

The MSDN is a good reference for these type of questions regarding syntax and usage. This is from the Transact SQL Reference - CASE page.

USE AdventureWorks2012;
SELECT   ProductNumber, Name, "Price Range" = 
     WHEN ListPrice =  0 THEN 'Mfg item - not for resale'
     WHEN ListPrice < 50 THEN 'Under $50'
     WHEN ListPrice >= 50 and ListPrice < 250 THEN 'Under $250'
     WHEN ListPrice >= 250 and ListPrice < 1000 THEN 'Under $1000'
     ELSE 'Over $1000'
FROM Production.Product
ORDER BY ProductNumber ;

Another good site you may want to check out if you're using SQL Server is SQL Server Central. This has a large variety of resources available for whatever area of SQL Server you would like to learn.

How to pass data from Javascript to PHP and vice versa?

I run into a similar issue the other day. Say, I want to pass data from client side to server and write the data into a log file. Here is my solution:

My simple client side code:

   <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
   <script src="" type="text/javascript"></script>
   <title>Test Page</title>
    function passVal(){
        var data = {
            fn: "filename",
            str: "this_is_a_dummy_test_string"

        $.post("test.php", data);


And php code on server side:

   $fn  = $_POST['fn'];
   $str = $_POST['str'];
   $file = fopen("/opt/lampp/htdocs/passVal/".$fn.".record","w");
   echo fwrite($file,$str);

Hope this works for you and future readers!

MySQL foreign key constraints, cascade delete

If your cascading deletes nuke a product because it was a member of a category that was killed, then you've set up your foreign keys improperly. Given your example tables, you should have the following table setup:

CREATE TABLE categories (
    id int unsigned not null primary key,
    name VARCHAR(255) default null

CREATE TABLE products (
    id int unsigned not null primary key,
    name VARCHAR(255) default null

CREATE TABLE categories_products (
    category_id int unsigned not null,
    product_id int unsigned not null,
    PRIMARY KEY (category_id, product_id),
    KEY pkey (product_id),
    FOREIGN KEY (category_id) REFERENCES categories (id)
    FOREIGN KEY (product_id) REFERENCES products (id)

This way, you can delete a product OR a category, and only the associated records in categories_products will die alongside. The cascade won't travel farther up the tree and delete the parent product/category table.


products: boots, mittens, hats, coats
categories: red, green, blue, white, black

prod/cats: red boots, green mittens, red coats, black hats

If you delete the 'red' category, then only the 'red' entry in the categories table dies, as well as the two entries prod/cats: 'red boots' and 'red coats'.

The delete will not cascade any farther and will not take out the 'boots' and 'coats' categories.

comment followup:

you're still misunderstanding how cascaded deletes work. They only affect the tables in which the "on delete cascade" is defined. In this case, the cascade is set in the "categories_products" table. If you delete the 'red' category, the only records that will cascade delete in categories_products are those where category_id = red. It won't touch any records where 'category_id = blue', and it would not travel onwards to the "products" table, because there's no foreign key defined in that table.

Here's a more concrete example:

categories:     products:
+----+------+   +----+---------+
| id | name |   | id | name    |
+----+------+   +----+---------+
| 1  | red  |   | 1  | mittens |
| 2  | blue |   | 2  | boots   |
+---++------+   +----+---------+

| product_id | category_id |
| 1          | 1           | // red mittens
| 1          | 2           | // blue mittens
| 2          | 1           | // red boots
| 2          | 2           | // blue boots

Let's say you delete category #2 (blue):

DELETE FROM categories WHERE (id = 2);

the DBMS will look at all the tables which have a foreign key pointing at the 'categories' table, and delete the records where the matching id is 2. Since we only defined the foreign key relationship in products_categories, you end up with this table once the delete completes:

| product_id | category_id |
| 1          | 1           | // red mittens
| 2          | 1           | // red boots

There's no foreign key defined in the products table, so the cascade will not work there, so you've still got boots and mittens listed. There's just no 'blue boots' and no 'blue mittens' anymore.

Python csv string to array

>>> a = "1,2"
>>> a
>>> b = a.split(",")
>>> b
['1', '2']

To parse a CSV file:

f = open(file.csv, "r")
lines ="\n") # "\r\n" if needed

for line in lines:
    if line != "": # add other needed checks to skip titles
        cols = line.split(",")
        print cols

How to clone git repository with specific revision/changeset?

git clone (clone the repository)

cd repository (navigate to the repository)

git fetch origin 2600f4f928773d79164964137d514b85400b09b2

git checkout FETCH_HEAD

Convert JSONObject to Map

Note to the above solution (from A Paul): The solution doesn't work, cause it doesn't reconstructs back a HashMap< String, Object > - instead it creates a HashMap< String, LinkedHashMap >.

Reason why is because during demarshalling, each Object (JSON marshalled as a LinkedHashMap) is used as-is, it takes 1-on-1 the LinkedHashMap (instead of converting the LinkedHashMap back to its proper Object).

If you had a HashMap< String, MyOwnObject > then proper demarshalling was possible - see following example:

ObjectMapper mapper = new ObjectMapper();
TypeFactory typeFactory = mapper.getTypeFactory();
MapType mapType = typeFactory.constructMapType(HashMap.class, String.class, MyOwnObject.class);
HashMap<String, MyOwnObject> map = mapper.readValue(new StringReader(hashTable.toString()), mapType);

How many socket connections can a web server handle?

In short: You should be able to achieve in the order of millions of simultaneous active TCP connections and by extension HTTP request(s). This tells you the maximum performance you can expect with the right platform with the right configuration.

Today, I was worried whether IIS with ASP.NET would support in the order of 100 concurrent connections (look at my update, expect ~10k responses per second on older ASP.Net Mono versions). When I saw this question/answers, I couldn't resist answering myself, many answers to the question here are completely incorrect.

Best Case

The answer to this question must only concern itself with the simplest server configuration to decouple from the countless variables and configurations possible downstream.

So consider the following scenario for my answer:

  1. No traffic on the TCP sessions, except for keep-alive packets (otherwise you would obviously need a corresponding amount of network bandwidth and other computer resources)
  2. Software designed to use asynchronous sockets and programming, rather than a hardware thread per request from a pool. (ie. IIS, Node.js, Nginx... webserver [but not Apache] with async designed application software)
  3. Good performance/dollar CPU / Ram. Today, arbitrarily, let's say i7 (4 core) with 8GB of RAM.
  4. A good firewall/router to match.
  5. No virtual limit/governor - ie. Linux somaxconn, IIS web.config...
  6. No dependency on other slower hardware - no reading from harddisk, because it would be the lowest common denominator and bottleneck, not network IO.

Detailed Answer

Synchronous thread-bound designs tend to be the worst performing relative to Asynchronous IO implementations.

WhatsApp can handle a million WITH traffic on a single Unix flavoured OS machine -

And finally, this one,, goes into a lot of detail, exploring how even 10 million could be achieved. Servers often have hardware TCP offload engines, ASICs designed for this specific role more efficiently than a general purpose CPU.

Good software design choices

Asynchronous IO design will differ across Operating Systems and Programming platforms. Node.js was designed with asynchronous in mind. You should use Promises at least, and when ECMAScript 7 comes along, async/await. C#/.Net already has full asynchronous support like node.js. Whatever the OS and platform, asynchronous should be expected to perform very well. And whatever language you choose, look for the keyword "asynchronous", most modern languages will have some support, even if it's an add-on of some sort.

To WebFarm?

Whatever the limit is for your particular situation, yes a web-farm is one good solution to scaling. There are many architectures for achieving this. One is using a load balancer (hosting providers can offer these, but even these have a limit, along with bandwidth ceiling), but I don't favour this option. For Single Page Applications with long-running connections, I prefer to instead have an open list of servers which the client application will choose from randomly at startup and reuse over the lifetime of the application. This removes the single point of failure (load balancer) and enables scaling through multiple data centres and therefore much more bandwidth.

Busting a myth - 64K ports

To address the question component regarding "64,000", this is a misconception. A server can connect to many more than 65535 clients. See

By the way, Http.sys on Windows permits multiple applications to share the same server port under the HTTP URL schema. They each register a separate domain binding, but there is ultimately a single server application proxying the requests to the correct applications.

Update 2019-05-30

Here is an up to date comparison of the fastest HTTP libraries -

  • Test date: 2018-06-06
  • Hardware used: Dell R440 Xeon Gold + 10 GbE
  • The leader has ~7M plaintext reponses per second (responses not connections)
  • The second one Fasthttp for golang advertises 1.5M concurrent connections - see
  • The leading languages are Rust, Go, C++, Java, C, and even C# ranks at 11 (6.9M per second). Scala and Clojure rank further down. Python ranks at 29th at 2.7M per second.
  • At the bottom of the list, I note laravel and cakephp, rails, aspnet-mono-ngx, symfony, zend. All below 10k per second. Note, most of these frameworks are build for dynamic pages and quite old, there may be newer variants that feature higher up in the list.
  • Remember this is HTTP plaintext, not for the Websocket specialty: many people coming here will likely be interested in concurrent connections for websocket.

Debugging in Maven?

Just as Brian said, you can use remote debugging:

mvn exec:exec -Dexec.executable="java" -Dexec.args="-classpath %classpath -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=1044"

Then in your eclipse, you can use remote debugging and attach the debugger to localhost:1044.

Why is `input` in Python 3 throwing NameError: name... is not defined

In operating systems like Ubuntu python comes preinstalled. So the default version is python 2.7 you can confirm the version by typing below command in your terminal

python -V

if you installed it but didn't set default version you will see

python 2.7

in terminal. I will tell you how to set the default python version in Ubuntu.

A simple safe way would be to use an alias. Place this into ~/.bashrc or ~/.bash_aliases file:

alias python=python3

After adding the above in the file, run the command below:

source ~/.bash_aliases or source ~/.bashrc

now check python version again using python -V

if python version 3.x.x one, then the error is in your syntax like using print with parenthesis. change it to

test = input("enter the test")

List all employee's names and their managers by manager name using an inner join

Your query is close you need to join using the mgr and the empid

on e1.mgr = e2.empid

So the full query is:

select e1.ename Emp,
  e2.eName Mgr
from employees e1
inner join employees e2
  on e1.mgr = e2.empid

See SQL Fiddle with Demo

If you want to return all rows including those without a manager then you would change it to a LEFT JOIN (for example the president):

select e1.ename Emp,
  e2.eName Mgr
from employees e1
left join employees e2
  on e1.mgr = e2.empid

See SQL Fiddle with Demo

The president in your sample data will return a null value for the manager because they do not have a manager.

When to use React setState callback

Sometimes we need a code block where we need to perform some operation right after setState where we are sure the state is being updated. That is where setState callback comes into play

For example, there was a scenario where I needed to enable a modal for 2 customers out of 20 customers, for the customers where we enabled it, there was a set of time taking API calls, so it looked like this

async componentDidMount() {
  const appConfig = getCustomerConfig();
  this.setState({enableModal: appConfig?.enableFeatures?.paymentModal }, async 
       //make some API call for data needed in poput

enableModal boolean was required in UI blocks in the render function as well, that's why I did setState here, otherwise, could've just checked condition once and either called API set or not.

Rotating a two-dimensional array in Python

There are three parts to this:

  1. original[::-1] reverses the original array. This notation is Python list slicing. This gives you a "sublist" of the original list described by [start:end:step], start is the first element, end is the last element to be used in the sublist. step says take every step'th element from first to last. Omitted start and end means the slice will be the entire list, and the negative step means that you'll get the elements in reverse. So, for example, if original was [x,y,z], the result would be [z,y,x]
  2. The * when preceding a list/tuple in the argument list of a function call means "expand" the list/tuple so that each of its elements becomes a separate argument to the function, rather than the list/tuple itself. So that if, say, args = [1,2,3], then zip(args) is the same as zip([1,2,3]), but zip(*args) is the same as zip(1,2,3).
  3. zip is a function that takes n arguments each of which is of length m and produces a list of length m, the elements of are of length n and contain the corresponding elements of each of the original lists. E.g., zip([1,2],[a,b],[x,y]) is [[1,a,x],[2,b,y]]. See also Python documentation.

React Native: How to select the next TextInput after pressing the "next" keyboard button?

This is the way I achieved it. And the example below has used the React.createRef() API introduced in React 16.3.

class Test extends React.Component {
  constructor(props) {
    this.secondTextInputRef = React.createRef();

  render() {
                placeholder = "FirstTextInput"
                onSubmitEditing={() => { this.secondTextInputRef.current.focus(); }}
                placeholder = "secondTextInput"

I think this will help you.

Parallel foreach with asynchronous lambda

With SemaphoreSlim you can achieve parallelism control.

var bag = new ConcurrentBag<object>();
var maxParallel = 20;
var throttler = new SemaphoreSlim(initialCount: maxParallel);
var tasks = myCollection.Select(async item =>
     await throttler.WaitAsync();
     var response = await GetData(item);
await Task.WhenAll(tasks);
var count = bag.Count;

How do I get the current date and time in PHP?

 $date = new DateTime('now', new DateTimeZone('Asia/Kolkata'));
 echo $date->format('d-m-Y H:i:s');


 //Also get am/pm in datetime:
 echo $date->format('d-m-Y H:i:s a'); // output 30-12-2013 10:16:15 am

For the date format, PHP date() Function is useful.

How do I change the text of a span element using JavaScript?

I used this one document.querySelector('ElementClass').innerText = 'newtext';

Appears to work with span, texts within classes/buttons

BootStrap : Uncaught TypeError: $(...).datetimepicker is not a function

I had this problem. Solution for me was to remove links to Vue.js files. Vue.js and JQuery have some conflicts in datepicker and datetimepicker functions.

finished with non zero exit value

You have to do the following instructions :

Click on Build located in the toolbar, then

Clean project -> Rebuild Project

Simulating group_concat MySQL function in Microsoft SQL Server 2005?

Possibly too late to be of benefit now, but is this not the easiest way to do things?

SELECT     empName, projIDs = replace
                          ((SELECT Surname AS [data()]
                              FROM project_members
                              WHERE  empName = a.empName
                              ORDER BY empName FOR xml path('')), ' ', REQUIRED SEPERATOR)
FROM         project_members a
GROUP BY empName

Regular Expressions: Search in list

Full Example (Python 3):
For Python 2.x look into Note below

import re

mylist = ["dog", "cat", "wildcat", "thundercat", "cow", "hooo"]
r = re.compile(".*cat")
newlist = list(filter(r.match, mylist)) # Read Note


['cat', 'wildcat', 'thundercat']


For Python 2.x developers, filter returns a list already. In Python 3.x filter was changed to return an iterator so it has to be converted to list (in order to see it printed out nicely).

Python 3 code example
Python 2.x code example

When should I use git pull --rebase?

You should use git pull --rebase when

  • your changes do not deserve a separate branch

Indeed -- why not then? It's more clear, and doesn't impose a logical grouping on your commits.

Ok, I suppose it needs some clarification. In Git, as you probably know, you're encouraged to branch and merge. Your local branch, into which you pull changes, and remote branch are, actually, different branches, and git pull is about merging them. It's reasonable, since you push not very often and usually accumulate a number of changes before they constitute a completed feature.

However, sometimes--by whatever reason--you think that it would actually be better if these two--remote and local--were one branch. Like in SVN. It is here where git pull --rebase comes into play. You no longer merge--you actually commit on top of the remote branch. That's what it actually is about.

Whether it's dangerous or not is the question of whether you are treating local and remote branch as one inseparable thing. Sometimes it's reasonable (when your changes are small, or if you're at the beginning of a robust development, when important changes are brought in by small commits). Sometimes it's not (when you'd normally create another branch, but you were too lazy to do that). But that's a different question.

How can I simulate a click to an anchor tag?

Quoted from

The click method is intended to be used with INPUT elements of type button, checkbox, radio, reset or submit. Gecko does not implement the click method on other elements that might be expected to respond to mouse–clicks such as links (A elements), nor will it necessarily fire the click event of other elements.

Non–Gecko DOMs may behave differently.

Unfortunately it sounds like you have already discovered the best solution to your problem.

As a side note, I agree that your solution seems less than ideal, but if you encapsulate the functionality inside a method (much like JQuery would do) it is not so bad.

Reading file input from a multipart/form-data POST

I have dealt WCF with large file (serveral GB) upload where store data in memory is not an option. My solution is to store message stream to a temp file and use seek to find out begin and end of binary data.

Could not load file or assembly 'System.Net.Http.Formatting' or one of its dependencies. The system cannot find the path specified

For Me adding few below line in WebApi.config works as after updating the new nuget package did not works out

var setting = config.Formatters.JsonFormatter.SerializerSettings;
setting.ContractResolver = new CamelCasePropertyNamesContractResolver();
setting.Formatting = Formatting.Indented;

Don't forget to add namespace:

using Newtonsoft.Json.Serialization; 
using Newtonsoft.Json;

Difference between static and shared libraries?

On top of all the other answers, one thing not mentionned yet is decoupling :

Let me speak about a real world production code,that I have been dealing with :

A very big software, made of >300 projects (with visual studio), mostly build as static lib and finally all link together in one huge executable , you end up with the following problems :

-Link time is extremely long. You might end up by more than 15min of link, for let's say 10s of compilation time -Some tools are on their knee with such a big executable , like memory check tools that must instrument the code. You might fall into reaching limits that had been seen as fools.

More problematic is the decoupling of your software : on this real world example, headers files of every project were reacheable from any others projects. As a consequence it was extremely easy for one developer to add dependencies; it was just about including the header, because link at the end will allwaws find symbols. It ends up by horrible cycling dependencies and complete mess.

With shared library, it's a bit of extra work because developer must edit the project build system to add the dependent library. I observed that shared library code tends to offer a cleaner code API.

How to reset a form using jQuery with .reset() method

Your code should work. Make sure static/jquery-1.9.1.min.js exists. Also, you can try reverting to static/jquery.min.js. If that fixes the problem then you've pinpointed the problem.

Changing one character in a string

Like other people have said, generally Python strings are supposed to be immutable.

However, if you are using CPython, the implementation at, it is possible to use ctypes to modify the string structure in memory.

Here is an example where I use the technique to clear a string.

Mark data as sensitive in python

I mention this for the sake of completeness, and this should be your last resort as it is hackish.

Remove 'standalone="yes"' from generated XML

You can use: marshaller.setProperty("jaxb.fragment", Boolean.TRUE);

It works for me on Java 8

How to redirect page after click on Ok button on sweet alert?

setTimeout(function () { _x000D_
  title: "Wow!",_x000D_
  text: "Message!",_x000D_
  type: "success",_x000D_
  confirmButtonText: "OK"_x000D_
  if (isConfirm) {_x000D_
    window.location.href = "//";_x000D_
}); }, 1000);
<script src=""></script>_x000D_
  <script src=""></script>_x000D_
  <link rel="stylesheet" href="">

Or you can use the build-in function timer, i.e.:

  title: "Success!",_x000D_
  text: "Redirecting in 2 seconds.",_x000D_
  type: "success",_x000D_
  timer: 2000,_x000D_
  showConfirmButton: false_x000D_
}, function(){_x000D_
      window.location.href = "//";_x000D_
<script src=""></script>_x000D_
  <script src=""></script>_x000D_
  <link rel="stylesheet" href="">

How to enable named/bind/DNS full logging?

I usually expand each log out into it's own channel and then to a separate log file, certainly makes things easier when you are trying to debug specific issues. So my logging section looks like the following:

logging {
    channel default_file {
        file "/var/log/named/default.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel general_file {
        file "/var/log/named/general.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel database_file {
        file "/var/log/named/database.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel security_file {
        file "/var/log/named/security.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel config_file {
        file "/var/log/named/config.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel resolver_file {
        file "/var/log/named/resolver.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel xfer-in_file {
        file "/var/log/named/xfer-in.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel xfer-out_file {
        file "/var/log/named/xfer-out.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel notify_file {
        file "/var/log/named/notify.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel client_file {
        file "/var/log/named/client.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel unmatched_file {
        file "/var/log/named/unmatched.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel queries_file {
        file "/var/log/named/queries.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel network_file {
        file "/var/log/named/network.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel update_file {
        file "/var/log/named/update.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel dispatch_file {
        file "/var/log/named/dispatch.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel dnssec_file {
        file "/var/log/named/dnssec.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;
    channel lame-servers_file {
        file "/var/log/named/lame-servers.log" versions 3 size 5m;
        severity dynamic;
        print-time yes;

    category default { default_file; };
    category general { general_file; };
    category database { database_file; };
    category security { security_file; };
    category config { config_file; };
    category resolver { resolver_file; };
    category xfer-in { xfer-in_file; };
    category xfer-out { xfer-out_file; };
    category notify { notify_file; };
    category client { client_file; };
    category unmatched { unmatched_file; };
    category queries { queries_file; };
    category network { network_file; };
    category update { update_file; };
    category dispatch { dispatch_file; };
    category dnssec { dnssec_file; };
    category lame-servers { lame-servers_file; };

Hope this helps.

The imported project "C:\Microsoft.CSharp.targets" was not found

Sometimes the problem might be with hardcoded VS version in .csproj file. If you have in your csproj something like this:


You should check if the number is correct (the reason it's wrong can be the project was created with another version of Visual Studio). If it's wrong, replace it with your current version of build tools OR use the VS variable:


Order by descending date - month, day and year

You have the field in a string, so you'll need to convert it to datetime

order by CONVERT(datetime, EventDate ) desc

How to part DATE and TIME from DATETIME in MySQL

For only date use

and for only time use

A button to start php script, how?

I know this question is 5 years old, but for anybody wondering how to do this without re-rendering the main page. This solution uses the dart editor/scripting language.

You could have an <object> tag that contains a data attribute. Make the <object> 1px by 1px and then use something like dart to dynamically change the <object>'s data attribute which re-renders the data in the 1px by 1px object.

HTML Script:

<object id="external_source" type="text/html" data="" width="1px" height="1px">

<button id="button1" type="button">Start Script</button>

<script async type="application/dart" src="dartScript.dart"></script>
<script async src="packages/browser/dart.js"></script>


echo 'hello world';


import 'dart:html';

InputElement button1;
ObjectElement externalSource;

void main() {
    button1 = querySelector('#button1')

    externalSource = querySelector('#external_source');

void runExternalSource(Event e) {
    externalSource.setAttribute('data', 'someScript.php');

So long as you aren't posting any information and you are just looking to run a script, this should work just fine.

Just build the dart script using "pub Build(generate JS)" and then upload the package onto your server.

Git credential helper - update password

Solution using command line for Windows, Linux, and MacOS

If you have updated your GitHub password on the GitHub server, in the first attempt of the git fetch/pull/push command it generates the authentication failed message.

Execute the same git fetch/pull/push command a second time and it prompts for credentials (username and password). Enter the username and the new updated password of the GitHub server and login will be successful.

Even I had this problem, and I performed the above steps and done!!

Git Pull is Not Possible, Unmerged Files

Ryan Stewart's answer was almost there. In the case where you actually don't want to delete your local changes, there's a workflow you can use to merge:

  • Run git status. It will give you a list of unmerged files.
  • Merge them (by hand, etc.)
  • Run git commit

Git will commit just the merges into a new commit. (In my case, I had additional added files on disk, which weren't lumped into that commit.)

Git then considers the merge successful and allows you to move forward.

Troubleshooting "Warning: session_start(): Cannot send session cache limiter - headers already sent"

use ob_start(); before session_start(); at top of your page like this


WPF MVVM ComboBox SelectedItem or SelectedValue not working

I have a very simply answer for this problem. First add the following code to the View IsSynchronizedWithCurrentItem="True".

Next when ever you assign a new object in the ViewModel to that Property SelectedObject should be saved to that Property and not the private member.

The viewmodel Proptery should look like this

    public Role SelectedObject 
        get { return object; }
            if (value != null)
                if (!object.Equals(value))
                    object = value;
                    OnPropertyChanged(() => SelectedObject );

This should fix the issue.

Remove git mapping in Visual Studio 2015

The solution is much simpler than that. You simply need to remove three files from the project UNC Path.

Navigate to your solution's UNC Path.

Example: C:\Users\Your User Name\Documents\Visual Studio 2015\Projects\Your Project Folder

Then permanently delete ("SHIFT + DEL") the .git* files and folder. There are two files and one folder, which may be hidden so ensure you have your folders and search options > View > show hidden files, folder, and drives (Radio Button) Selected.

The files to permanently delete are:

.gitignore (file)

.gitattributes (file)

.git (folder)

Reopen Visual Studio and there is no more relationship to the Git Source Control. If you wanted to take it as far as removing it from the registry as mentioned above, you could, but that shouldn't be necessary aside from the "house keeping" of your machine.

Authenticate with GitHub using a token

Step 1: Get access token

In your github account
Click on the image on the top corner of the page that contains your profile picture ->
Settings ->
In the side menu ->
Developer Settings ->
Personal access Tokens ->
Generate new token.

Step 2: Use the token

$ git push
Username: <your username>
Password: <the access token>

Now I do not have to type username and password every time I push changes.
I just type git push and press Enter, And changes will be pushed.

How to get a list of sub-folders and their files, ordered by folder-names

Hej man, why are you using this ?

dir /s/b/o:gn > f.txt (wrong one)

Don't you know what is that 'g' in '/o' ??

Check this out: or dir /? for dir help

You should be using this instead:

dir /s/b/o:n > f.txt (right one)

How do CSS triangles work?

Others have already explained this well. Let me give you an animation which will explain this quickly:

Here is some code for you to play with and learn the concepts.


    <div id="border-demo">


/*border-width is border thickness*/
#border-demo {
    background: gray;
    border-color: yellow blue red green;/*top right bottom left*/
    border-style: solid;
    border-width: 25px 25px 25px 25px;/*top right bottom left*/
    height: 50px;
    width: 50px;

Play with this and see what happens. Set height and width to zero. Then remove top border and make left and right transparent, or just look at the code below to make a css triangle:

#border-demo {
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
    border-bottom: 100px solid blue;

How to re-index all subarray elements of a multidimensional array?

PHP native function exists for this. See

Simply do this: mixed reset ( array &$array )

Can't create a docker image for COPY failed: stat /var/lib/docker/tmp/docker-builder error

Here is the reason why it happens, i.e. your local directory in the host OS where you are running the docker should have the file, otherwise you get this error

One solution is to : use RUN cp <src> <dst> instead of COPY <src> <dst>

then run the command it works!

Beamer: How to show images as step-by-step images

I found a solution to my problem, by using the visble-command.


   \textbf{Some text}

Relationship between hashCode and equals method in Java

The contract is that if obj1.equals(obj2) then obj1.hashCode() == obj2.hashCode() , it is mainly for performance reasons, as maps are mainly using hashCode method to compare entries keys.

How do you push just a single Git branch (and no other branches)?

So let's say you have a local branch foo, a remote called origin and a remote branch origin/master.

To push the contents of foo to origin/master, you first need to set its upstream:

git checkout foo
git branch -u origin/master

Then you can push to this branch using:

git push origin HEAD:master

In the last command you can add --force to replace the entire history of origin/master with that of foo.

Is there a standard sign function (signum, sgn) in C/C++?

If all you want is to test the sign, use signbit (returns true if its argument has a negative sign). Not sure why you would particularly want -1 or +1 returned; copysign is more convenient for that, but it sounds like it will return +1 for negative zero on some platforms with only partial support for negative zero, where signbit presumably would return true.

Python object deleting itself

I think I've finally got it!
NOTE: You should not use this in normal code, but it is possible. This is only meant as a curiosity, see other answers for real-world solutions to this problem.

Take a look at this code:

# NOTE: This is Python 3 code, it should work with python 2, but I haven't tested it.
import weakref

class InsaneClass(object):
    _alive = []
    def __new__(cls):
        self = super().__new__(cls)

        return weakref.proxy(self)

    def commit_suicide(self):

instance = InsaneClass()

# Raises Error: ReferenceError: weakly-referenced object no longer exists

When the object is created in the __new__ method, the instance is replaced by a weak reference proxy and the only strong reference is kept in the _alive class attribute.

What is a weak-reference?

Weak-reference is a reference which does not count as a reference when the garbage collector collects the object. Consider this example:

>>> class Test(): pass

>>> a = Test()
>>> b = Test()

>>> c = a
>>> d = weakref.proxy(b)
>>> d
<weakproxy at 0x10671ae58 to Test at 0x10670f4e0> 
# The weak reference points to the Test() object

>>> del a
>>> c
<__main__.Test object at 0x10670f390> # c still exists

>>> del b
>>> d
<weakproxy at 0x10671ab38 to NoneType at 0x1002050d0> 
# d is now only a weak-reference to None. The Test() instance was garbage-collected

So the only strong reference to the instance is stored in the _alive class attribute. And when the commit_suicide() method removes the reference the instance is garbage-collected.

Change a Nullable column to NOT NULL with Default Value

Try this

ALTER TABLE table_name ALTER COLUMN col_name data_type NOT NULL;

Favicon dimensions?

Wikipedia has this to say:

Additionally, such icon files can be either 16×16 or 32×32 pixels in size, and either 8-bit or 24-bit in color depth (note that GIF files have a limited, 256 color palette entries).

I think the best way is to use a 32x32 gif and test it with different browsers.

What is the difference between JavaScript and ECMAScript?

Javascript was the original name, meant to capitalize on the popularity of java. ECMA is the standards body that oversees the standard that was eventually put in place so the names are roughly equivalent.

Implementations have other names, like V8 or Rhino, etc.

Uncaught Error: Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function but got: object

By mistake i tried to import Container and Content from react-native instead of native-base.

Error because of this line:

import { ActivityIndicator, RefreshControl,  StyleSheet, View, Keyboard, Container, Content } from 'react-native';

Below is the code fix:

import { ActivityIndicator, RefreshControl,  StyleSheet, View, Keyboard } from 'react-native';
import { Container, Content} from 'native-base';

How do I repair an InnoDB table?

stop your application...or stop your slave so no new rows are being added

create table <new table> like <old table>;
insert <new table> select * from <old table>;
truncate table  <old table>;
insert <old table> select * from <new table>;

restart your server or slave

Bash foreach loop

"foreach" is not the name for bash. It is simply "for". You can do things in one line only like:

for fn in `cat filenames.txt`; do cat "$fn"; done


how can I set visible back to true in jquery

Remove the visible="false" attribute and add a CSS class that is not visible by default. Then you should be able to reference the dropdown by the correct id, for example:


Above ID you should serach for in the source of the rendered page in your browser.

Populating VBA dynamic arrays

Yes, you're looking for the ReDim statement, which dynamically allocates the required amount of space in the array.

The following statement

Dim MyArray()

declares an array without dimensions, so the compiler doesn't know how big it is and can't store anything inside of it.

But you can use the ReDim statement to resize the array:

ReDim MyArray(0 To 3)

And if you need to resize the array while preserving its contents, you can use the Preserve keyword along with the ReDim statement:

ReDim Preserve MyArray(0 To 3)

But do note that both ReDim and particularly ReDim Preserve have a heavy performance cost. Try to avoid doing this over and over in a loop if at all possible; your users will thank you.

However, in the simple example shown in your question (if it's not just a throwaway sample), you don't need ReDim at all. Just declare the array with explicit dimensions:

Dim MyArray(0 To 3)

Replace one substring for another string in shell script

If tomorrow you decide you don't love Marry either she can be replaced as well:

echo "${tomorrow//Marry/Jesica}" > /tmp/lovers.txt

There must be 50 ways to leave your lover.

How to download videos from youtube on java?

Regarding the format (mp4 or flv) decide which URL you want to use. Then use this tutorial to download the video and save it into a local directory.

React PropTypes : Allow different types of PropTypes for one prop

import React from 'react';              <--as normal
import PropTypes from 'prop-types';     <--add this as a second line

    App.propTypes = {
        monkey: PropTypes.string,           <--omit "React."
        cat: PropTypes.number.isRequired    <--omit "React."

    Wrong:  React.PropTypes.string
    Right:  PropTypes.string

How can I issue a single command from the command line through sql plus?

This is how I solved the problem:

<target name="executeSQLScript">
    <exec executable="sqlplus" failonerror="true" errorproperty="exit.status">
        <arg value="${dbUser}/${dbPass}@<DBHOST>:<DBPORT>/<SID>"/>
        <arg value="@${basedir}/db/scripttoexecute.sql"/>

ImportError: No module named psycopg2

Try installing


with pip install psycopg2-binary --user

How to display two digits after decimal point in SQL Server

You can also use below code which helps me:

select convert(numeric(10,2), column_name) as Total from TABLE_NAME

where Total is alias of the field you want.

Is it possible to declare two variables of different types in a for loop?

Define a macro:

#define FOR( typeX,x,valueX,  typeY,y,valueY,  condition, increments) typeX x; typeY y; for(x=valueX,y=valueY;condition;increments)

FOR(int,i,0,  int,f,0.0,  i < 5, i++)

Just remember, your variable scopes will not be within the for loop this way either.

Apache error: _default_ virtualhost overlap on port 443

On a vanilla Apache2 install in CentOS, when you install mod_ssl it will automatically add a configuration file in:


This configuration file contains a default virtual host definition for port 443, named default:443. If you also have your own virtual host definition for 443 (i.e. in httpd.conf) then you will have a confict. Since the conf.d files are included first, they will win over yours.

To solve the conflict you can either remove the virtual host definition from conf.d/ssl.conf or update it to your own settings.

Trying to load local JSON file to show data in a html page using JQuery

Due to security issues (same origin policy), javascript access to local files is restricted if without user interaction.

According to

A file can read another file only if the parent directory of the originating file is an ancestor directory of the target file.

Imagine a situation when javascript from a website tries to steal your files anywhere in your system without you being aware of. You have to deploy it to a web server. Or try to load it with a script tag. Like this:

<script type="text/javascript" language="javascript" src="jquery-1.8.2.min.js"></script>        
<script type="text/javascript" language="javascript" src="priorities.json"></script> 

<script type="text/javascript">
   $(document).ready(function(e) {

Your priorities.json file:

var jsonObject = {
"start": {
    "count": "5",
    "title": "start",
    "priorities": [
            "txt": "Work"
            "txt": "Time Sense"
            "txt": "Dicipline"
            "txt": "Confidence"
            "txt": "CrossFunctional"

Or declare a callback function on your page and wrap it like jsonp technique:

<script type="text/javascript" language="javascript" src="jquery-1.8.2.min.js">    </script> 
     <script type="text/javascript">
           $(document).ready(function(e) {


           function jsonCallback(jsonObject){

 <script type="text/javascript" language="javascript" src="priorities.json"></script> 

Your priorities.json file:

    "start": {
        "count": "5",
        "title": "start",
        "priorities": [
                "txt": "Work"
                "txt": "Time Sense"
                "txt": "Dicipline"
                "txt": "Confidence"
                "txt": "CrossFunctional"

Using script tag is a similar technique to JSONP, but with this approach it's not so flexible. I recommend deploying it on a web server.

With user interaction, javascript is allowed access to files. That's the case of File API. Using file api, javascript can access files selected by the user from <input type="file"/> or dropped from the desktop to the browser.

Can you get the column names from a SqlDataReader?

It is easier to achieve it in SQL


Disable copy constructor

You can make the copy constructor private and provide no implementation:

    SymbolIndexer(const SymbolIndexer&);

Or in C++11, explicitly forbid it:

SymbolIndexer(const SymbolIndexer&) = delete;

How does one target IE7 and IE8 with valid CSS?

The actual problem is not IE8, but the hacks that you use for earlier versions of IE.

IE8 is pretty close to be standards compliant, so you shouldn't need any hacks at all for it, perhaps only some tweaks. The problem is if you are using some hacks for IE6 and IE7; you will have to make sure that they only apply to those versions and not IE8.

I made the web site of our company compatible with IE8 a while ago. The only thing that I actually changed was adding the meta tag that tells IE that the pages are IE8 compliant...

Facebook Callback appends '#_=_' to Return URL

I know this reply is late, but if you are using passportjs, you might want to see this.

return (req, res, next) => {

I have written this middleware and applied it to express server instance, and the original URL I've got is without the "#_=_". Looks like it when we apply passporJS' instance as middleware to the server instance, it doesn't take those characters, but are only visible on the address bar of our browsers.

How do you beta test an iphone app?

Diawi Alternatives

Since have added some limitations for free accounds.

Next best available and easy to use alternative is




Happy build sharing!

Setting the default active profile in Spring-boot

I do it this way

    System.setProperty("spring.profiles.default", "dev");

in the very beginning of main(...)

How to save final model using keras?

you can save the model in json and weights in a hdf5 file format.

# keras library import  for Saving and loading model and weights

from keras.models import model_from_json
from keras.models import load_model

# serialize model to JSON
#  the keras model which is trained is defined as 'model' in this example
model_json = model.to_json()

with open("model_num.json", "w") as json_file:

# serialize weights to HDF5

files "model_num.h5" and "model_num.json" are created which contain our model and weights

To use the same trained model for further testing you can simply load the hdf5 file and use it for the prediction of different data. here's how to load the model from saved files.

# load json and create model
json_file = open('model_num.json', 'r')

loaded_model_json =
loaded_model = model_from_json(loaded_model_json)

# load weights into new model
print("Loaded model from disk")'model_num.hdf5')

To predict for different data you can use this

loaded_model.predict_classes("your_test_data here")

Writing a new line to file in PHP (line feed)

Use PHP_EOL which outputs \r\n or \n depending on the OS.

Angular HttpClient "Http failure during parsing"

I had the same problem and the cause was That at time of returning a string in your backend (spring) you might be returning as return "spring used"; But this isn't parsed right according to spring. Instead use return "\" spring used \""; -Peace out

exception.getMessage() output with class name

I think you are wrapping your exception in another exception (which isn't in your code above). If you try out this code:

public static void main(String[] args) {
    try {
        throw new RuntimeException("Cannot move file");
    } catch (Exception ex) {
        JOptionPane.showMessageDialog(null, "Error: " + ex.getMessage());
} will see a popup that says exactly what you want.

However, to solve your problem (the wrapped exception) you need get to the "root" exception with the "correct" message. To do this you need to create a own recursive method getRootCause:

public static void main(String[] args) {
    try {
        throw new Exception(new RuntimeException("Cannot move file"));
    } catch (Exception ex) {
                                      "Error: " + getRootCause(ex).getMessage());

public static Throwable getRootCause(Throwable throwable) {
    if (throwable.getCause() != null)
        return getRootCause(throwable.getCause());

    return throwable;

Note: Unwrapping exceptions like this however, sort of breaks the abstractions. I encourage you to find out why the exception is wrapped and ask yourself if it makes sense.

Java web start - Unable to load resource

Include your IP address in your host file (C:\Windows\System32\drivers\etc\host) for the respective server:

Sample Entry: Vijay's Server

How do I convert a date/time to epoch time (unix time/seconds since 1970) in Perl?

I'm using a very old O/S that I don't dare install libraries onto, so here's what I use;

if ($LeapYearCount==($YearFourDigits/4)) { if ($EpochDayNumber<32) { $EpochDayNumber--; }}

The input variables are;


...which should be self-explanatory.

The input variables, of course, assume GMT (UTC). The output variable is "$ActualEpochTime". (Often, I only need $EpochDayNumber, so that's why that otherwise superfluous variable sits on its own.)

I've used this formula for years with nary an error.

Adding a y-axis label to secondary y-axis in matplotlib

For everyone stumbling upon this post because pandas gets mentioned, you now have the very elegant and straighforward option of directly accessing the secondary_y axis in pandas with ax.right_ax

So paraphrasing the example initially posted, you would write:

table = sql.read_frame(query,connection)

ax = table[[0, 1]].plot(ylim=(0,100), secondary_y=table[1])
ax.right_ax.set_ylabel('Your second Y-Axis Label goes here!')

(this is already mentioned in these posts as well: 1 2)

Programmatically stop execution of python script?

You could raise SystemExit(0) instead of going to all the trouble to import sys; sys.exit(0).

Git push rejected "non-fast-forward"

I had this problem! I tried: git fetch + git merge, but dont resolved! I tried: git pull, and also dont resolved

Then I tried this and resolved my problem (is similar of answer of Engineer):

git fetch origin master:tmp
git rebase tmp
git push origin HEAD:master
git branch -D tmp

How to convert an ASCII character into an int in C

Are you searching for this:

int c = some_ascii_character;

Or just converting without assignment:


Is there a simple way to remove unused dependencies from a maven pom.xml?

The Maven Dependency Plugin will help, especially the dependency:analyze goal:

dependency:analyze analyzes the dependencies of this project and determines which are: used and declared; used and undeclared; unused and declared.

Another thing that might help to do some cleanup is the Dependency Convergence report from the Maven Project Info Reports Plugin.

UITableView, Separator color where to set?

Swift version:

override func viewDidLoad() {

    // Assign your color to this property, for example here we assign the red color.
    tableView.separatorColor = UIColor.redColor()

How can I convert String to Int?

This would do

string x = TextBoxD1.Text;
int xi = Convert.ToInt32(x);

Or you can use

int xi = Int32.Parse(x);

Refer Microsoft Developer Network for more information

Simple jQuery, PHP and JSONP example?


        type:     "GET",
        url: '<?php echo Base_url("user/your function");?>',
        data: {name: mail},
        dataType: "jsonp",
        jsonp: 'callback',
        jsonpCallback: 'chekEmailTaken',
        success: function(msg){
return true;

In controller:

public function ajax_checkjp(){
$checkType = $_GET['name'];
echo $_GET['callback']. '(' . json_encode($result) . ');';  

SQL Server: Multiple table joins with a WHERE clause

try this

INSERT @Application ( Id, NAME )
VALUES  ( 1,'Word' ), ( 2,'Excel' ), ( 3,'PowerPoint' )
DECLARE @software TABLE(Id INT PRIMARY KEY, ApplicationId INT, Version INT)
INSERT @software ( Id, ApplicationId, Version )
VALUES  ( 1,1, 2003 ), ( 2,1,2007 ), ( 3,2, 2003 ), ( 4,2,2007 ),( 5,3, 2003 ), ( 6,3,2007 )

INSERT @Computer ( Id, NAME )
VALUES  ( 1,'Name1' ), ( 2,'Name2' )

DECLARE @Software_Computer  TABLE(Id INT PRIMARY KEY, SoftwareId int, ComputerId int)
INSERT @Software_Computer ( Id, SoftwareId, ComputerId )
VALUES  ( 1,1, 1 ), ( 2,4,1 ), ( 3,2, 2 ), ( 4,5,2 )

SELECT Computer.Name ComputerName, Application.Name ApplicationName, MAX(Software2.Version) Version
FROM @Application Application 
JOIN @Software Software
    ON Application.ID = Software.ApplicationID
CROSS JOIN @Computer Computer
LEFT JOIN @Software_Computer Software_Computer
    ON Software_Computer.ComputerId = Computer.Id AND Software_Computer.SoftwareId = Software.Id
LEFT JOIN @Software Software2
    ON Software2.ID = Software_Computer.SoftwareID
WHERE Computer.ID = 1 
GROUP BY Computer.Name, Application.Name

UnmodifiableMap (Java Collections) vs ImmutableMap (Google)

An unmodifiable map may still change. It is only a view on a modifiable map, and changes in the backing map will be visible through the unmodifiable map. The unmodifiable map only prevents modifications for those who only have the reference to the unmodifiable view:

Map<String, String> realMap = new HashMap<String, String>();
realMap.put("A", "B");

Map<String, String> unmodifiableMap = Collections.unmodifiableMap(realMap);

// This is not possible: It would throw an 
// UnsupportedOperationException
//unmodifiableMap.put("C", "D");

// This is still possible:
realMap.put("E", "F");

// The change in the "realMap" is now also visible
// in the "unmodifiableMap". So the unmodifiableMap
// has changed after it has been created.
unmodifiableMap.get("E"); // Will return "F". 

In contrast to that, the ImmutableMap of Guava is really immutable: It is a true copy of a given map, and nobody may modify this ImmutableMap in any way.


As pointed out in a comment, an immutable map can also be created with the standard API using

Map<String, String> immutableMap = 
    Collections.unmodifiableMap(new LinkedHashMap<String, String>(realMap)); 

This will create an unmodifiable view on a true copy of the given map, and thus nicely emulates the characteristics of the ImmutableMap without having to add the dependency to Guava.

multiple conditions for JavaScript .includes() method

You can use the .some method referenced here.

The some() method tests whether at least one element in the array passes the test implemented by the provided function.

// test cases
var str1 = 'hi, how do you do?';
var str2 = 'regular string';

// do the test strings contain these terms?
var conditions = ["hello", "hi", "howdy"];

// run the tests against every element in the array
var test1 = conditions.some(el => str1.includes(el));
var test2 = conditions.some(el => str2.includes(el));

// display results
console.log(str1, ' ===> ', test1);
console.log(str2, ' ===> ', test2);

Accessing an array out of bounds gives no error, why?

libstdc++, which is part of gcc, has a special debug mode for error checking. It is enabled by compiler flag -D_GLIBCXX_DEBUG. Among other things it does bounds checking for std::vector at the cost of performance. Here is online demo with recent version of gcc.

So actually you can do bounds checking with libstdc++ debug mode but you should do it only when testing because it costs notable performance compared to normal libstdc++ mode.

Use string value from a cell to access worksheet of same name

You need INDIRECT function:


Responding with a JSON object in Node.js (converting object/array to JSON string)

const http = require('http');
const url = require('url');


    const parseObj =  url.parse(req.url,true);
    const users = [{id:1,name:'soura'},{id:2,name:'soumya'}]

    if(parseObj.pathname == '/user-details' && req.method == "GET") {
        let Id =;
        let user_details = {};
            if( == Id){
                user_details = data;
        res.writeHead(200,{'x-auth-token':'Auth Token'})
        res.write(JSON.stringify(user_details)) // Json to String Convert

I have used the above code in my existing project.

UnicodeEncodeError: 'charmap' codec can't encode characters

In Python 3.7, and running Windows 10 this worked (I am not sure whether it will work on other platforms and/or other versions of Python)

Replacing this line:

with open('filename', 'w') as f:

With this:

with open('filename', 'w', encoding='utf-8') as f:

The reason why it is working is because the encoding is changed to UTF-8 when using the file, so characters in UTF-8 are able to be converted to text, instead of returning an error when it encounters a UTF-8 character that is not suppord by the current encoding.

Access all Environment properties as a Map or Properties object

As this Spring's Jira ticket, it is an intentional design. But the following code works for me.

public static Map<String, Object> getAllKnownProperties(Environment env) {
    Map<String, Object> rtn = new HashMap<>();
    if (env instanceof ConfigurableEnvironment) {
        for (PropertySource<?> propertySource : ((ConfigurableEnvironment) env).getPropertySources()) {
            if (propertySource instanceof EnumerablePropertySource) {
                for (String key : ((EnumerablePropertySource) propertySource).getPropertyNames()) {
                    rtn.put(key, propertySource.getProperty(key));
    return rtn;

Error retrieving parent for item: No resource found that matches the given name after upgrading to AppCompat v23

I found the solution, Problem started when I updated sdk, after that I used different buildToolsVersion ('22.0.1') and I was using different support library like compile '', showing you in image below

enter image description here

This was raising problem of "android.widget.Material..." Then I used same version for support library like compile '' and its DONE. (Showing you in below screenshot)

enter image description here

How do I add a library path in cmake?

The simplest way of doing this would be to add


add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # is found in ${CMAKE_SOURCE_DIR}/lib

The modern CMake version that doesn't add the -I and -L flags to every compiler invocation would be to use imported libraries:

add_library(bar SHARED IMPORTED) # or STATIC instead of SHARED
set_target_properties(bar PROPERTIES

set(FOO_SRCS "foo.cpp")
add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # also adds the required include path

If setting the INTERFACE_INCLUDE_DIRECTORIES doesn't add the path, older versions of CMake also allow you to use target_include_directories(bar PUBLIC /path/to/include). However, this no longer works with CMake 3.6 or newer.

IndentationError: unexpected unindent WHY?

you didn't complete your try statement. You need and except in there too.

convert php date to mysql format

$date = mysql_real_escape_string($_POST['intake_date']);

1. If your MySQL column is DATE type:

$date = date('Y-m-d', strtotime(str_replace('-', '/', $date)));

2. If your MySQL column is DATETIME type:

$date = date('Y-m-d H:i:s', strtotime(str_replace('-', '/', $date)));

You haven't got to work strototime(), because it will not work with dash - separators, it will try to do a subtraction.

Update, the way your date is formatted you can't use strtotime(), use this code instead:

$date = '02/07/2009 00:07:00';
$date = preg_replace('#(\d{2})/(\d{2})/(\d{4})\s(.*)#', '$3-$2-$1 $4', $date);
echo $date;


2009-07-02 00:07:00

Default value for field in Django model

Set editable to False and default to your default value.

b = models.CharField(max_length=7, default='0000000', editable=False)

Also, your id field is unnecessary. Django will add it automatically.