Programs & Examples On #Command prompt

The command prompt is the string of text that a command-line interpreter displays to you, the user, to prompt you for input in interactive mode. For programs with textual user interfaces in general, not specifically addressing their prompts for user input, see either the CONSOLE-APPLICATION (Microsoft Windows) or TERMINAL (Unices, MacOS 10, and Linux) tags. See COMMAND-LINE or SuperUser for commands invoked by command lines at a command prompt.

How to get all Windows service names starting with a common word?

Using PowerShell, you can use the following

Get-Service | Where-Object {$_.displayName.StartsWith("NATION-")} | Select name

This will show a list off all services which displayname starts with "NATION-".

You can also directly stop or start the services;

Get-Service | Where-Object {$_.displayName.StartsWith("NATION-")} | Stop-Service
Get-Service | Where-Object {$_.displayName.StartsWith("NATION-")} | Start-Service

or simply

Get-Service | Where-Object {$_.displayName.StartsWith("NATION-")} | Restart-Service

Prevent overwriting a file using cmd if exist

Use the FULL path to the folder in your If Not Exist code. Then you won't even have to CD anymore:

If Not Exist "C:\Documents and Settings\John\Start Menu\Programs\SoftWareFolder\"

Compiling/Executing a C# Source File in Command Prompt

I have written a batch file CompileCS.cmd which allows to compile (and optionally run) a C# file, you can find the complete answer including the batch program 'CompileCS' here.

Its usage is simple:

CompileCS /run GetDotNetVersion.cs[arg1] ... [arg9]

will compile and run GetDotNetVersion.cs - if you just want to compile it, omit the /run parameter.

The console application GetDotNetVersion.cs is taken from this answer.

CMD command to check connected USB devices

You can use the wmic command:

wmic path CIM_LogicalDevice where "Description like 'USB%'" get /value

How to connect to SQL Server from command prompt with Windows authentication

Try This :

--Default Instance


--Named Instance




More details can be found here

How to start jenkins on different port rather than 8080 using command prompt in Windows?

In *nix In CentOS/RedHat

vim /etc/sysconfig/jenkins

# Port Jenkins is listening on.
# Set to -1 to disable

In windows open XML file C:\Program Files (x86)\Jenkins\jenkins.xml

  <arguments>-Xrs -Xmx256m -Dhudson.lifecycle=hudson.lifecycle.WindowsServiceLifecycle -jar "%BASE%\jenkins.war" --**httpPort=8083**</arguments>
 i made  above bold  to show you change then 
  <arguments>-Xrs -Xmx256m -Dhudson.lifecycle=hudson.lifecycle.WindowsServiceLifecycle -jar "%BASE%\jenkins.war" --httpPort=8083</arguments>

now you have to restart it doesnot work unless you restart http://localhost:8080/restart then after restart http://localhost:8083/ all should be well so looks like the all above response which says it does not work We have restart.

Using the "start" command with parameters passed to the started program

If you must use double quotation mark at any parameter, you can get error "'c:\somepath' is not recognized a an internal or external command, operable program or batch file". I suggest below solution when using double qoutation mark:

'git' is not recognized as an internal or external command

Just check whether the Bit Locker has enabled!. I faced a similar issue where my GIT in the cmd was working fine. But after a quick restart, it didn't work and I got the error as mentioned above.

So I had to unlock the Bit locker since I have installed GIT in the Hard drive volume (:E) which was encrypted by Bit Locker.

How to complete the RUNAS command in one line

The runas command does not allow a password on its command line. This is by design (and also the reason you cannot pipe a password to it as input). Raymond Chen says it nicely:

The RunAs program demands that you type the password manually. Why doesn't it accept a password on the command line?

This was a conscious decision. If it were possible to pass the password on the command line, people would start embedding passwords into batch files and logon scripts, which is laughably insecure.

In other words, the feature is missing to remove the temptation to use the feature insecurely.

how concatenate two variables in batch script?

You can do it without setlocal, because of the setlocal command the variable won't survive an endlocal because it was created in setlocal. In this way the variable will be defined the right way.

To do that use this code:

set var1=A

set var2=B

set AB=hi

call set newvar=%%%var1%%var2%%%

echo %newvar% 

Note: You MUST use call before you set the variable or it won't work.

How do I run a program from command prompt as a different user and as an admin

Runas doesn't magically run commands as an administrator, it runs them as whatever account you provide credentials for. If it's not an administrator account, runas doesn't care.

How to add a set path only for that batch file executing?

Just like any other environment variable, with SET:

SET PATH=%PATH%;c:\whatever\else

If you want to have a little safety check built in first, check to see if the new path exists first:

IF EXIST c:\whatever\else SET PATH=%PATH%;c:\whatever\else

If you want that to be local to that batch file, use setlocal:

set PATH=...

@REM Rest of your script

Read the docs carefully for setlocal/endlocal , and have a look at the other references on that site - Functions is pretty interesting too and the syntax is tricky.

The Syntax page should get you started with the basics.

Changing default startup directory for command prompt in Windows 7

  1. go to regedit ( go to search and type regedit)
  2. expand "HKEY_CURRENT_USER" node
  3. under HKEY_CURRENT_USER node expand "software" node
  4. under software node expand "microsoft" node
  5. under microsoft node click on "Command Processor"
  6. path looks like this : "HKEY_CURRENT_USER\Software\Microsoft\Command Processor"

it looks something like this :

  1. if you do not see "Autorun" String Value
  2. Right Click - New - Expandable String Value, and rename it to Autorun
  3. double click on "Autorun" 10.enter this value path format:
  4. "CD/d C:\yourfoldername\yoursubfoldername"

How to connect from windows command prompt to mysql command line

first type cmd then the windows command prompt will appear:

mysql -u root -p


  • -u is the user id
  • -p is the password, if you will not using a password just leave it blank.

Messages Using Command prompt in Windows 7

You can use the net send command to send a message over a network.


net send * How Are You

you can use the above statement to send a message to all members of your domain.But if you want to send a message to a single user named Mike, you can use

 net send mike hello!

this will send hello! to the user named Mike.

Run Command Line & Command From VBS

Set oShell = CreateObject ("WScript.Shell") "cmd.exe /C copy ""S:Claims\Sound.wav"" ""C:\WINDOWS\Media\Sound.wav"" "

xcopy file, rename, suppress "Does xxx specify a file name..." message

There is some sort of undocumented feature in XCOPY. you can use:

xcopy "bin\development\whee.config.example" "c:\mybackup\TestConnectionExternal\bin\Debug\whee.config*"

i tested it just today. :-)

Have bash script answer interactive prompts

If you only have Y to send :

$> yes Y |./your_script

If you only have N to send :

$> yes N |./your_script

javac is not recognized as an internal or external command, operable program or batch file

You mistyped the set command – you missed the backslash after C:. It should be:

C:\>set path=C:\Program Files (x86)\Java\jdk1.7.0\bin

How do I type a TAB character in PowerShell?

If it helps you can embed a tab character in a double quoted string:

PS> "`t hello"

How to write a multiline command?

In the Windows Command Prompt the ^ is used to escape the next character on the command line. (Like \ is used in strings.) Characters that need to be used in the command line as they are should have a ^ prefixed to them, hence that's why it works for the newline.

For reference the characters that need escaping (if specified as command arguments and not within quotes) are: &|()

So the equivalent of your linux example would be (the More? being a prompt):

C:\> dir ^
More? C:\Windows

Server is already running in Rails

On Windows Rails 5.2, delete this file


and run

rails s


How do I minimize the command prompt from my bat file

Use the start command, with the /min switch to run minimized. For example:

start /min C:\Ruby192\bin\setrbvars.bat

Since you've specified a batch file as the argument, the command processor is run, passing the /k switch. This means that the window will remain on screen after the command has finished. You can alter that behavior by explicitly running cmd.exe yourself and passing the appropriate switches if necessary.

Alternatively, you can create a shortcut to the batch file (are PIF files still around), and then alter its properties so that it starts minimized.

How to run TestNG from command line

Ok after 2 days of trying to figure out why I couldn't run the example from the following code did not work for me

C:\TestNG_WORKSPACE>java -cp "C:\TestNG_WORKSPACE" org.testng.TestNG testng.xml

The fix for it is as follows: I came to the following conclusion: First off install eclipse, and download the TestNG plugin. After that follow the instructions from the tutorial to create and compile the test class from cmd using javac, and add the testng.xml. To run the testng.xml on windows 10 cmd run the following line:

java -cp C:\Users\Lenovo\Desktop\eclipse\plugins\org.testng.eclipse_6.9.12.201607091356\lib\*;C:\Test org.testng.TestNG testng.xml

to clarify: C:\Users\Lenovo\Desktop\eclipse\plugins\org.testng.eclipse_6.9.12.201607091356\lib\* The path above represents the location of jcommander.jar and testng.jar that you downloaded by installing the TESTNG plugin for eclipse. The path may vary so to be sure just open the installation location of eclipse, go to plugins and search for jcommander.jar. Then copy that location and after that add * to select all the necessary .jars.


The path above represents the location of the testing.xml in your project. After getting all the necessary paths, append them by using ";".

I hope I have been helpful to some of you guys :)

How to grant permission to users for a directory using command line in Windows?

excellent point Calin Darie

I had a lot of scripts to use cacls I move them to icacls how ever I could not find a script to change the root mount volumes example: d:\datafolder. I finally crated the script below, which mounts the volume as a temporary drive then applies sec. then unmounts it. It is the only way I found that you can update the root mount security.

1 gets the folder mount GUID to a temp file then reads the GUID to mount the volume as a temp drive X: applies sec and logs the changes then unmounts the Volume only from the X: drive so the mounted folder is not altered or interrupted other then the applied sec.

here is sample of my script:

**mountvol "d:\%1" /L >tempDrive.temp && FOR /f "tokens=*" %%I IN (tempDrive.temp) DO mountvol X: %%I 
D:\tools\security\icacls.exe  %~2 /grant domain\group:(OI)(CI)F /T /C >>%~1LUNsec-%TDWEEK%-%TMONTH%-%TDAY%-%TYEAR%-%THOUR%-%TMINUTE%-%TAM%.txt
if exist x:\*.* mountvol X: /d**

How do I use a pipe to redirect the output of one command to the input of another?

You can also run exactly same command at Cmd.exe command-line using PowerShell. I'd go with this approach for simplicity...

C:\>PowerShell -Command "temperature | prismcom.exe usb"

Please read up on Understanding the Windows PowerShell Pipeline

You can also type in C:\>PowerShell at the command-line and it'll put you in PS C:\> mode instanctly, where you can directly start writing PS.

Aliases in Windows command prompt

Alternatively you can use cmder which lets you add aliases just like linux:

alias subl="C:\Program Files\Sublime Text 3\subl.exe" $*

Open text file and program shortcut in a Windows batch file

The command start [filename] opened the file in my default text editor.

This command also worked for opening a non-.txt file.

How to zip a file using cmd line?

If you are using Ubuntu Linux:

  1. Install zip

    sudo apt-get install zip
  2. Zip your folder:

    zip -r {} {foldername}

If you are using Microsoft Windows:

Windows does not come with a command-line zip program, despite Windows Explorer natively supporting Zip files since the Plus! pack for Windows 98.

I recommend the open-source 7-Zip utility which includes a command-line executable and supports many different archive file types, especially its own *.7z format which offers superior compression ratios to traditional (PKZIP) *.zip files:

  1. Download 7-Zip from the 7-Zip home page

  2. Add the path to 7z.exe to your PATH environment variable. See this QA: How to set the path and environment variables in Windows

  3. Open a new command-prompt window and use this command to create a PKZIP *.zip file:

    7z a -tzip {} {yourfolder}

Cross-platform Java:

If you have the Java JDK installed then you can use the jar utility to create Zip files, as *.jar files are essentially just renamed *.zip (PKZIP) files:

jar -cfM {} {yourfolder}

Explanation: * -c compress * -f specify filename * -M do not include a MANIFEST file

Can I mask an input text in a bat file?

I wrote an open source program called editenv that replaces my older editv32/editv64 utilities:

The --maskinput (-m) option[*] lets you hide (mask) the typed input and has a configurable character (default character is *); e.g.:

editenv -m -p "Password: " PWD

The --prompt (-p) option lets you specify an input prompt. The above will display a Password: prompt and wait for you to enter something. Typed characters will appear as *. Pressing Ctrl+C will end the program with an exit code of 1223.

Download is here:

[*] Note that the --maskinput (-m) option is not secure -- the entered string is entered as plain-text in the environment. This feature is for convenience only.

What is the alternative for ~ (user's home directory) on Windows command prompt?

I just tried set ~=%userprofile% and that works too if you want to keep using the same habit

You can then use %~% instead.

Command prompt won't change directory to another drive

In order to move to D drive in windows use, C:\Users\Balaji>d:

In order to move to E drive use, C:\Users\Balaji>e:

same will be applicable for other drives.

javac not working in windows command prompt

for /d %i in ("\Program Files\Java\jdk*") do set JAVA_HOME=%i

this solution worked to me

Change all files and folders permissions of a directory to 644/755

Easiest for me to remember is two operations:

chmod -R 644 dirName
chmod -R +X dirName

The +X only affects directories.

How to see the proxy settings on windows?

An update to @rleelr:
It's possible to view proxy settings in Google Chrome:


Then select

View live HTTP/2 sessions

Then select one of the live sessions (you need to have some tabs open). There you find:

t=504112 [st= 0] +HTTP2_SESSION  [dt=?]
                  --> host = ""
                  --> proxy = "PROXY"

How to run an application as "run as administrator" from the command prompt?

See this TechNet article: Runas command documentation

From a command prompt:

C:\> runas /user:<localmachinename>\administrator cmd

Or, if you're connected to a domain:

C:\> runas /user:<DomainName>\<AdministratorAccountName> cmd

Command line for looking at specific port

I use:

netstat –aon | find "<port number>"

here o represents process ID. now you can do whatever with the process ID. To terminate the process, for e.g., use:

taskkill /F /pid <process ID>

How can I move all the files from one folder to another using the command line?

OMG I Got A Quick File Move Command form CMD

1)Command will move All Files and Sub Folders into another location in 1 second .

check command

C:\user>move "your source path " "your destination path" 

Hint : For move all Files and Sub folders

C:\user>move "f:\wamp\www" "f:\wapm_3.2\www\old Projects"

check image enter image description here

you can see that it's before i try some other code that was not working due to more than 1 files and folder was there. when i try to execute code that is under line by red color then all folder move in 1 second.

now check this image. here Total 6.7GB data moved in 1 second... you can check date of post and move as well as Folder name. enter image description here

i will soon make a windows app that will do same..

PowerShell The term is not recognized as cmdlet function script file or operable program

For the benefit of searchers, there is another way you can produce this error message - by missing the $ off the script block name when calling it.

e.g. I had a script block like so:

$qa = {
    param($question, $answer)
    Write-Host "Question = $question, Answer = $answer"

I tried calling it using:

&qa -question "Do you like powershell?" -answer "Yes!"

But that errored. The correct way was:

&$qa -question "Do you like powershell?" -answer "Yes!"

How to use passive FTP mode in Windows command prompt?

Windows does not actually support passive mode.

You can send the command to the server in three different ways but that will not enable passive mode on the Windows client end.

Those arguments are for sending various commands and pasv is not something that Microsoft thought of when they wrote it.

You will have to find a 3rd party software like WinSCP that supports command line usage and use that instead of the Windows native one.

How can I set / change DNS using the command-prompt at windows 8

To change DNS to automatic via command, you can run the following command:

netsh interface ip set dns "Local Area Connection" dhcp

How to change current working directory using a batch file

Specify /D to change the drive also.

CD /D %root%

how to change directory using Windows command line

Another alternative is pushd, which will automatically switch drives as needed. It also allows you to return to the previous directory via popd:

C:\Temp>pushd D:\some\folder

Run a Command Prompt command from Desktop Shortcut

  1. first goto that folder from where you to what to open command prompt where its desktop or some other location
  2. make a text file in that location just write cmd -c and save name.bat
  3. double click so your CMD path will be of that folder enter image description here

open program minimized via command prompt

For the people which are looking for the opposite (aka fullscreen), it's very simple. Because you just have to replace the settings /min by /max.

Now the program will be open at the "maximized" size ! In the case, perhaps you will need an example : start /max explorer.exe.

Install a Windows service using a Windows command prompt?

the following code , install and uninstall the Service,

Open the command prompt and run the program as an administrator and fire the below command and press enter.


To Install

C:\windows\\framework\v4.0.30319>InstallUtil.exe + Your copied path + \your service name + .exe

eg :Our Path InstallUtil.exe C:\MyFirstService\bin\Debug\MyFirstService.exe

To uninstall

 C:\windows\\framework\v4.0.30319>InstallUtil.exe -u + Your copied path + \your service name + .exe

eg : Our path InstallUtil.exe -u C:\MyFirstService\bin\Debug\MyFirstService.exe

for more help you can see the following link: sample program

Get CPU Usage from Windows Command Prompt

typeperf "\processor(_total)\% processor time"

does work on Win7, you just need to extract the percent value yourself from the last quoted string.

Opening Chrome From Command Line

you can create batch file and insert into it the bellow line:

cmd /k start chrome "

after that you do just double click on this batch file.

batch file Copy files with certain extensions from multiple directories into one directory

Just use the XCOPY command with recursive option

xcopy c:\*.doc k:\mybackup /sy

/s will make it "recursive"

How to run Java program in command prompt

A very general command prompt how to for java is

java mainjava

You'll very often see people doing

javac *.java
java mainjava

As for the subclass problem that's probably occurring because a path is missing from your class path, the -c flag I believe is used to set that.

Start/Stop and Restart Jenkins service on Windows

       jenkins.exe stop
       jenkins.exe start
       jenkins.exe restart

These commands will work from cmd only if you run CMD with admin permissions

How do I kill the process currently using a port on localhost in Windows?

I know that is really old question, but found pretty easy to remember, fast command to kill app that are using port.

Requirements: [email protected]^ version

npx kill-port 8080

You can also read more about kill-port here:

PHP pass variable to include

I found that the include parameter needs to be the entire file path, not a relative path or partial path for this to work.

How to return a html page from a restful controller in spring boot?

The String you return here:

 return "login";

Is actually the whole content what you send back to the browser.

If you want to have the content of a file to be sent back, one way is:

  1. Open file
  2. Read contents into String
  3. Return the value

You can go by with this answer on the question Spring boot service to download a file

How to remove all callbacks from a Handler?

As josh527 said, handler.removeCallbacksAndMessages(null); can work.
But why?
If you have a look at the source code, you can understand it more clearly. There are 3 type of method to remove callbacks/messages from handler(the MessageQueue):

  1. remove by callback (and token)
  2. remove by message.what (and token)
  3. remove by token (leave some overload method)

 * Remove any pending posts of Runnable <var>r</var> with Object
 * <var>token</var> that are in the message queue.  If <var>token</var> is null,
 * all callbacks will be removed.
public final void removeCallbacks(Runnable r, Object token)
    mQueue.removeMessages(this, r, token);

 * Remove any pending posts of messages with code 'what' and whose obj is
 * 'object' that are in the message queue.  If <var>object</var> is null,
 * all messages will be removed.
public final void removeMessages(int what, Object object) {
    mQueue.removeMessages(this, what, object);

 * Remove any pending posts of callbacks and sent messages whose
 * <var>obj</var> is <var>token</var>.  If <var>token</var> is null,
 * all callbacks and messages will be removed.
public final void removeCallbacksAndMessages(Object token) {
    mQueue.removeCallbacksAndMessages(this, token);
} do the real work:

void removeMessages(Handler h, int what, Object object) {
    if (h == null) {

    synchronized (this) {
        Message p = mMessages;

        // Remove all messages at front.
        while (p != null && == h && p.what == what
               && (object == null || p.obj == object)) {
            Message n =;
            mMessages = n;
            p = n;

        // Remove all messages after front.
        while (p != null) {
            Message n =;
            if (n != null) {
                if ( == h && n.what == what
                    && (object == null || n.obj == object)) {
                    Message nn =;
           = nn;
            p = n;

void removeMessages(Handler h, Runnable r, Object object) {
    if (h == null || r == null) {

    synchronized (this) {
        Message p = mMessages;

        // Remove all messages at front.
        while (p != null && == h && p.callback == r
               && (object == null || p.obj == object)) {
            Message n =;
            mMessages = n;
            p = n;

        // Remove all messages after front.
        while (p != null) {
            Message n =;
            if (n != null) {
                if ( == h && n.callback == r
                    && (object == null || n.obj == object)) {
                    Message nn =;
           = nn;
            p = n;

void removeCallbacksAndMessages(Handler h, Object object) {
    if (h == null) {

    synchronized (this) {
        Message p = mMessages;

        // Remove all messages at front.
        while (p != null && == h
                && (object == null || p.obj == object)) {
            Message n =;
            mMessages = n;
            p = n;

        // Remove all messages after front.
        while (p != null) {
            Message n =;
            if (n != null) {
                if ( == h && (object == null || n.obj == object)) {
                    Message nn =;
           = nn;
            p = n;

Add all files to a commit except a single file?

To keep the change in file but not to commit I did this

git add .

git reset -- main/dontcheckmein.txt

git commit -m "commit message"

to verify the file is excluded do

git status

Unit Testing: DateTime.Now

Here is my anwer of this question. I combine the 'Ambient Context' pattern with IDisposable. So you can use the DateTimeProvider.Current in your normal program code and in the test you override the scope with a using statement.

using System;
using System.Collections.Immutable;

namespace ambientcontext {

public abstract class DateTimeProvider : IDisposable
    private static ImmutableStack<DateTimeProvider> stack = ImmutableStack<DateTimeProvider>.Empty.Push(new DefaultDateTimeProvider());

    protected DateTimeProvider()
        if (this.GetType() != typeof(DefaultDateTimeProvider))
            stack = stack.Push(this);

    public static DateTimeProvider Current => stack.Peek();
    public abstract DateTime Today { get; }
    public abstract DateTime Now {get; }

    public void Dispose()
        if (this.GetType() != typeof(DefaultDateTimeProvider))
            stack = stack.Pop();

    // Not visible Default Implementation 
    private class DefaultDateTimeProvider : DateTimeProvider {
        public override DateTime Today => DateTime.Today; 
        public override DateTime Now => DateTime.Now; 

Here is how to use the above DateTimeProvider inside a Unit-Test

using System;
using Xunit;

namespace ambientcontext
    public class TestDateTimeProvider
        public void TestDateTime()
            var actual = DateTimeProvider.Current.Today;
            var expected = DateTime.Today;

            Assert.Equal<DateTime>(expected, actual);

            using (new MyDateTimeProvider(new DateTime(2012,12,21)))
                Assert.Equal(2012, DateTimeProvider.Current.Today.Year);

                using (new MyDateTimeProvider(new DateTime(1984,4,4)))
                    Assert.Equal(1984, DateTimeProvider.Current.Today.Year);    

                Assert.Equal(2012, DateTimeProvider.Current.Today.Year);

            // Fall-Back to Default DateTimeProvider 
            Assert.Equal<int>(expected.Year,  DateTimeProvider.Current.Today.Year);

        private class MyDateTimeProvider : DateTimeProvider 
            private readonly DateTime dateTime; 

            public MyDateTimeProvider(DateTime dateTime):base()
                this.dateTime = dateTime; 

            public override DateTime Today => this.dateTime.Date;

            public override DateTime Now => this.dateTime;

React Native: JAVA_HOME is not set and no 'java' command could be found in your PATH

I ran this in the command prompt(have windows 7 os): JAVA_HOME=C:\Program Files\Android\Android Studio\jre

where what its = to is the path to that jre folder, so anyone's can be different.

jquery remove "selected" attribute of option?

The question is asked in a misleading manner. "Removing the selected attribute" and "deselecting all options" are entirely different things.

To deselect all options in a documented, cross-browser manner use either



// Note the use of .prop instead of .attr
$("select option").prop("selected", false);

Java Returning method which returns arraylist?

MyClass obj = new MyClass();
ArrayList<Integer> numbers = obj.myNumbers();

Value Change Listener to JTextField

You can use even "MouseExited" to control. example:

 private void jtSoMauMouseExited(java.awt.event.MouseEvent evt) {                                    
        // TODO add your handling code here:
        try {
            if (Integer.parseInt(jtSoMau.getText()) > 1) {
                //auto update field
                SoMau = Integer.parseInt(jtSoMau.getText());
                int result = SoMau / 5;

        } catch (Exception e) {



What is the difference between declarations, providers, and import in NgModule?

  1. declarations: This property tells about the Components, Directives and Pipes that belong to this module.
  2. exports: The subset of declarations that should be visible and usable in the component templates of other NgModules.
  3. imports: Other modules whose exported classes are needed by component templates declared in this NgModule.
  4. providers: Creators of services that this NgModule contributes to the global collection of services; they become accessible in all parts of the app. (You can also specify providers at the component level, which is often preferred.)
  5. bootstrap: The main application view, called the root component, which hosts all other app views. Only the root NgModule should set the bootstrap property.

How does Tomcat locate the webapps directory?

I'm using Tomcat through XAMPP which might have been the cause of this problem. When I changed appBase="C:/Java Project/", for example, I kept getting "This localhost page can't be found" in the browser.

I had to add a folder called ROOT inside the Java Project folder and then it worked. Any files you're working on have to be inside this ROOT folder but you need to leave appBase="C:/Java Project/" as changing it to appBase="C:/Java Project/ROOT" will cause "This localhost page can't be found" to be displayed again.

Maybe needing the ROOT folder is obvious to more experienced Java developers but it wasn't for me so hopefully this helps anyone else encountering the same problem.

Embed Youtube video inside an Android app

How it looks:

enter image description here

Best solution to my case. I need video fit web view size. Use embed youtube link with your video id. Example:

WebView youtubeWebView; //todo find or bind web view
String myVideoYoutubeId = "-bvXmLR3Ozc";

outubeWebView.setWebViewClient(new WebViewClient() {
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                return false;

WebSettings webSettings = youtubeWebView.getSettings();

youtubeWebView.loadUrl("" + myVideoYoutubeId);

Web view xml code


How do you strip a character out of a column in SQL Server?

This is done using the REPLACE function

To strip out "somestring" from "SomeColumn" in "SomeTable" in the SELECT query:

SELECT REPLACE([SomeColumn],'somestring','') AS [SomeColumn]  FROM [SomeTable]

To update the table and strip out "somestring" from "SomeColumn" in "SomeTable"

UPDATE [SomeTable] SET [SomeColumn] = REPLACE([SomeColumn], 'somestring', '')

How to compile a static library in Linux?

Generate the object files with gcc, then use ar to bundle them into a static library.

How to open a Bootstrap modal window using jQuery?

Check out the complete solution here:

Make sure to put libraries in required order to get result:

1- First bootstrap.min.css 2- jquery.min.js 3- bootstrap.min.js

(In other words jquery.min.js must be call before bootstrap.min.js)

    <link rel="stylesheet" href="">

<script src="">

 <script src=""></script>

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '...' is therefore not allowed access

Basically alter API header response by adding following additional parameters.

Access-Control-Allow-Credentials: true

Access-Control-Allow-Origin: *

But this is not good solution when it comes to the security

How to ignore certain files in Git

If you have already committed the file and you are trying to ignore it by adding to the .gitignore file, Git will not ignore it. For that, you first have to do the below things:

git rm --cached FILENAME

If you are starting the project freshly and you want to add some files to Git ignore, follow the below steps to create a Git ignore file:

  1. Navigate to your Git repository.
  2. Enter "touch .gitignore" which will create a .gitignore file.

Python - Count elements in list

To find count of unique elements of list use the combination of len() and set().

>>> ls = [1, 2, 3, 4, 1, 1, 2]
>>> len(ls)
>>> len(set(ls))

Meaning of *& and **& in C++

This *& in theory as well as in practical its possible and called as reference to pointer variable. and it's act like same. This *& combination is used in as function parameter for 'pass by' type defining. unlike ** can also be used for declaring a double pointer variable.
The passing of parameter is divided into pass by value, pass by reference, pass by pointer. there are various answer about "pass by" types available. however the basic we require to understand for this topic is.

pass by reference --> generally operates on already created variable refereed while passing to function e.g fun(int &a);

pass by pointer --> Operates on already initialized 'pointer variable/variable address' passing to function e.g fun(int* a);

auto addControl = [](SomeLabel** label, SomeControl** control) {
    *label = new SomeLabel;
    *control = new SomeControl;
    // few more operation further.


in the above example(this is the real life problem i came across) i am trying to init few pointer variable from the lambda function and for that we need to pass it by double pointer, so that comes with d-referencing of pointer for its all usage inside of that lambda + while passing pointer in function which takes double pointer, you need to pass reference to the pointer variable.

so with this same thing reference to the pointer variable, *& this combination helps. in below given way for the same example i have mentioned above.

auto addControl = [](SomeLabel*& label, SomeControl*& control) {
        label = new SomeLabel;
        control = new SomeControl;
        // few more operation further.


so here you can see that you neither require d-referencing nor we require to pass reference to pointer variable while passing in function, as current pass by type is already reference to pointer.

Hope this helps :-)

PKIX path building failed in Java application

In my case the issue was resolved by installing Oracle's official JDK 10 as opposed to using the default OpenJDK that came with my Ubuntu. This is the guide I followed:

How do you find the sum of all the numbers in an array in Java?

As of Java 8 The use of lambda expressions have become available.

See this:

int[] nums = /** Your Array **/;


int sum = 0;
Arrays.asList(nums).stream().forEach(each -> {
    sum += each;


int sum = 0;

ArrayList<Integer> list = new ArrayList<Integer>();

for (int each : nums) { //refer back to original array
     list.add(each); //there are faster operations…
} -> {
    sum += each;

Return or print sum.

HTTP POST Returns Error: 417 "Expectation Failed."

In my situation, this error seems to occur only if my client's computer has a strict firewall policy, which prevents my program from communicating with the web service.

So only solution I could find is to catch the error and inform user about changing the firewall settings manually.

How to get the last value of an ArrayList

guava provides another way to obtain the last element from a List:

last = Lists.reverse(list).get(0)

if the provided list is empty it throws an IndexOutOfBoundsException

SQL Server Group by Count of DateTime Per Hour?

Alternatively, just GROUP BY the hour and day:

SELECT  CAST(Startdate as DATE) as 'StartDate', 
        CAST(DATEPART(Hour, StartDate) as varchar) + ':00' as 'Hour', 
        COUNT(*) as 'Ct'
FROM #Events
GROUP BY CAST(Startdate as DATE), DATEPART(Hour, StartDate)


StartDate   Hour    Ct
2007-01-01  0:00    3
2007-01-02  5:00    2
2007-01-03  4:00    1
2007-01-07  3:00    1

Create thumbnail image

Here is a version based on the accepted answer. It fixes two problems...

  1. Improper disposing of the images.
  2. Maintaining the aspect ratio of the image.

I found this tool to be fast and effective for both JPG and PNG files.

private static FileInfo CreateThumbnailImage(string imageFileName, string thumbnailFileName)
    const int thumbnailSize = 150;
    using (var image = Image.FromFile(imageFileName))
        var imageHeight = image.Height;
        var imageWidth = image.Width;
        if (imageHeight > imageWidth)
            imageWidth = (int) (((float) imageWidth / (float) imageHeight) * thumbnailSize);
            imageHeight = thumbnailSize;
            imageHeight = (int) (((float) imageHeight / (float) imageWidth) * thumbnailSize);
            imageWidth = thumbnailSize;

        using (var thumb = image.GetThumbnailImage(imageWidth, imageHeight, () => false, IntPtr.Zero))
            //Save off the new thumbnail

    return new FileInfo(thumbnailFileName);

Angular IE Caching issue for $http

Instead of disabling caching for each single GET-request, I disable it globally in the $httpProvider:

myModule.config(['$httpProvider', function($httpProvider) {
    //initialize get if not there
    if (!$httpProvider.defaults.headers.get) {
        $httpProvider.defaults.headers.get = {};    

    // Answer edited to include suggestions from comments
    // because previous version of code introduced browser-related errors

    //disable IE ajax request caching
    $httpProvider.defaults.headers.get['If-Modified-Since'] = 'Mon, 26 Jul 1997 05:00:00 GMT';
    // extra
    $httpProvider.defaults.headers.get['Cache-Control'] = 'no-cache';
    $httpProvider.defaults.headers.get['Pragma'] = 'no-cache';

Is there a method for String conversion to Title Case?

The simplest way of converting any string into a title case, is to use googles package org.apache.commons.lang.WordUtils

System.out.println(WordUtils.capitalizeFully("tHis will BE MY EXAMple"));

Will result this

This Will Be My Example

I'm not sure why its named "capitalizeFully", where in fact the function is not doing a full capital result, but anyways, thats the tool that we need.

Execute a stored procedure in another stored procedure in SQL server

Yes , Its easy to way we call the function inside the store procedure.

for e.g. create user define Age function and use in select query.

select dbo.GetRegAge(R.DateOfBirth, r.RegistrationDate) as Age,R.DateOfBirth,r.RegistrationDate from T_Registration R

When should use Readonly and Get only properties

readonly properties are used to create a fail-safe code. i really like the Encapsulation posts series of Mark Seemann about properties and backing fields:

taken from Mark's example:

public class Fragrance : IFragrance
    private readonly string name;

    public Fragrance(string name)
        if (name == null)
            throw new ArgumentNullException("name");
        } = name;

    public string Spread()

in this example you use the readonly name field to make sure the class invariant is always valid. in this case the class composer wanted to make sure the name field is set only once (immutable) and is always present.

Run a single test method with maven

The test parameter mentioned by tobrien allows you to specify a method using a # before the method name. This should work for JUnit and TestNG. I've never tried it, just read it on the Surefire Plugin page:

Specify this parameter to run individual tests by file name, overriding the includes/excludes parameters. Each pattern you specify here will be used to create an include pattern formatted like **/${test}.java, so you can just type "-Dtest=MyTest" to run a single test called "foo/". This parameter overrides the includes/excludes parameters, and the TestNG suiteXmlFiles parameter. since 2.7.3 You can execute a limited number of method in the test with adding #myMethod or #my*ethod. Si type "-Dtest=MyTest#myMethod" supported for junit 4.x and testNg

Stop a gif animation onload, on mouseover start the activation

A more elegant version of Mark Kramer's would be to do the following:

function animateImg(id, gifSrc){
  var $el = $(id),
    staticSrc = $el.attr('src');
      $(this).attr("src", gifSrc);
      $(this).attr("src", staticSrc);

  animateImg('#id1', 'gif/gif1.gif');
  animateImg('#id2', 'gif/gif2.gif');

Or even better would be to use data attributes:

    var $el = $(this),
      staticSrc = $el.attr('src'),
      gifSrc = $'gifSrc');
        $(this).attr("src", gifSrc);
        $(this).attr("src", staticSrc);

And the img el would look something like:

<img class="animated-img" src=".../img.jpg" data-gif-src=".../gif.gif" />

Note: This code is untested but should work fine.

Peak-finding algorithm for Python/SciPy

There are standard statistical functions and methods for finding outliers to data, which is probably what you need in the first case. Using derivatives would solve your second. I'm not sure for a method which solves both continuous functions and sampled data, however.

Trying to pull files from my Github repository: "refusing to merge unrelated histories"

When I used --allow-unrelated-histories, this command generated too many conflicts. There were conflicts in files which I didn't even work on. To get over the error " Refusing to merge unrelated histories", I used following rebase command:

git pull --rebase=preserve --allow-unrelated-histories

After this commit the uncommitted changes with a commit message. Finally, run the following command:

git rebase --continue

After this, my working copy was up-to-date with the remote copy and I was able to push my changes as before. No more unrelated histories error while pulling.

Encrypt and decrypt a String in java

    public String encrypt(String str) {
        try {
            // Encode the string into bytes using utf-8
            byte[] utf8 = str.getBytes("UTF8");

            // Encrypt
            byte[] enc = ecipher.doFinal(utf8);

            // Encode bytes to base64 to get a string
            return new sun.misc.BASE64Encoder().encode(enc);
        } catch (javax.crypto.BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        } catch ( e) {
        return null;

    public String decrypt(String str) {
        try {
            // Decode base64 to get bytes
            byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

            // Decrypt
            byte[] utf8 = dcipher.doFinal(dec);

            // Decode using utf-8
            return new String(utf8, "UTF8");
        } catch (javax.crypto.BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        } catch ( e) {
        return null;

Here's an example that uses the class:

try {
    // Generate a temporary key. In practice, you would save this key.
    // See also Encrypting with DES Using a Pass Phrase.
    SecretKey key = KeyGenerator.getInstance("DES").generateKey();

    // Create encrypter/decrypter class
    DesEncrypter encrypter = new DesEncrypter(key);

    // Encrypt
    String encrypted = encrypter.encrypt("Don't tell anybody!");

    // Decrypt
    String decrypted = encrypter.decrypt(encrypted);
} catch (Exception e) {

Determining complexity for recursive functions (Big O notation)

I see that for the accepted answer (recursivefn5), some folks are having issues with the explanation. so I'd try to clarify to the best of my knowledge.

  1. The for loop runs for n/2 times because at each iteration, we are increasing i (the counter) by a factor of 2. so say n = 10, the for loop will run 10/2 = 5 times i.e when i is 0,2,4,6 and 8 respectively.

  2. In the same regard, the recursive call is reduced by a factor of 5 for every time it is called i.e it runs for n/5 times. Again assume n = 10, the recursive call runs for 10/5 = 2 times i.e when n is 10 and 5 and then it hits the base case and terminates.

  3. Calculating the total run time, the for loop runs n/2 times for every time we call the recursive function. since the recursive fxn runs n/5 times (in 2 above),the for loop runs for (n/2) * (n/5) = (n^2)/10 times, which translates to an overall Big O runtime of O(n^2) - ignoring the constant (1/10)...

How do I check out a specific version of a submodule using 'git submodule'?

Submodule repositories stay in a detached HEAD state pointing to a specific commit. Changing that commit simply involves checking out a different tag or commit then adding the change to the parent repository.

$ cd submodule
$ git checkout v2.0
Previous HEAD position was 5c1277e... bumped version to 2.0.5
HEAD is now at f0a0036... version 2.0

git-status on the parent repository will now report a dirty tree:

# On branch dev [...]
#   modified:   submodule (new commits)

Add the submodule directory and commit to store the new pointer.

MySQL table is marked as crashed and last (automatic?) repair failed

Try running the following query:

repair table <table_name>;

I had the same issue and it solved me the problem.

How to increase scrollback buffer size in tmux?

The history limit is a pane attribute that is fixed at the time of pane creation and cannot be changed for existing panes. The value is taken from the history-limit session option (the default value is 2000).

To create a pane with a different value you will need to set the appropriate history-limit option before creating the pane.

To establish a different default, you can put a line like the following in your .tmux.conf file:

set-option -g history-limit 3000

Note: Be careful setting a very large default value, it can easily consume lots of RAM if you create many panes.

For a new pane (or the initial pane in a new window) in an existing session, you can set that session’s history-limit. You might use a command like this (from a shell):

tmux set-option history-limit 5000 \; new-window

For (the initial pane of the initial window in) a new session you will need to set the “global” history-limit before creating the session:

tmux set-option -g history-limit 5000 \; new-session

Note: If you do not re-set the history-limit value, then the new value will be also used for other panes/windows/sessions created in the future; there is currently no direct way to create a single new pane/window/session with its own specific limit without (at least temporarily) changing history-limit (though show-option (especially in 1.7 and later) can help with retrieving the current value so that you restore it later).

Python executable not finding libpython shared library

just install python-lib. (python27-lib). It will install libpython2.7.so1.0. We don't require to manually set anything.

init-param and context-param

<init-param> will be used if you want to initialize some parameter for a particular servlet. When request come to servlet first its init method will be called then doGet/doPost whereas if you want to initialize some variable for whole application you will need to use <context-param> . Every servlet will have access to the context variable.

SQL: How to perform string does not equal

Try the following query

select * from table
where NOT (tester = 'username')

What is the equivalent of 'describe table' in SQL Server?

WHERE C.TABLE_NAME = '<Table Name>';

Sample Output

Remove last item from array

Just use the following for your use case:

var arr = [1,2,3,4];
arr.pop() //returns 4 as the value
arr // value 4 is removed from the **arr** array variable

Just a note. When you execute pop() function even though the line returns the popped item the original array is effected and the popped element is removed.

List Highest Correlation Pairs from a Large Correlation Matrix in Pandas?

Use the code below to view the correlations in the descending order.

# See the correlations in descending order

corr = df.corr() # df is the pandas dataframe
c1 = corr.abs().unstack()
c1.sort_values(ascending = False)

Android: Test Push Notification online (Google Cloud Messaging)

Pushwatch is a free to use online GCM and APNS push notification tester developed by myself in Django/Python as I have found myself in a similar situation while working on multiple projects. It can send both GCM and APNS notifications and also support JSON messages for extra arguments. Following are the links to the testers.

Please let me know if you have any questions or face issues using it.

How do I comment out a block of tags in XML?

You can wrap the text with a non-existing processing-instruction, e.g.:

  <band height="20">
      <reportElement x="180" y="0" width="200" height="20"/>
      <text><![CDATA[Hello World!]]></text>

Nested processing instructions are not allowed and '?>' ends the processing instruction (see

Failed to execute 'postMessage' on 'DOMWindow': The target origin provided does not match the recipient window's origin ('null')

Another reason this could be happening is if you are using an iframe that has the sandbox attribute and allow-same-origin isn't set e.g.:

// page.html
<iframe id="f" src="http://localhost:8000/iframe.html" sandbox="allow-scripts"></iframe>
<script type="text/javascript">
    var f = document.getElementById("f").contentWindow;
    // will throw exception
    f.postMessage("hello world!", 'http://localhost:8000');

// iframe.html
<script type="text/javascript">
    window.addEventListener("message", function(event) {
    }, false);

I haven't found a solution other than:

  • add allow-same-origin to the sandbox (didn't want to do that)
  • use f.postMessage("hello world!", '*');

What are the Ruby modes and options?

In Ruby IO module documentation, I suppose.

Mode |  Meaning
"r"  |  Read-only, starts at beginning of file  (default mode).
"r+" |  Read-write, starts at beginning of file.
"w"  |  Write-only, truncates existing file
     |  to zero length or creates a new file for writing.
"w+" |  Read-write, truncates existing file to zero length
     |  or creates a new file for reading and writing.
"a"  |  Write-only, starts at end of file if file exists,
     |  otherwise creates a new file for writing.
"a+" |  Read-write, starts at end of file if file exists,
     |  otherwise creates a new file for reading and
     |  writing.
"b"  |  Binary file mode (may appear with
     |  any of the key letters listed above).
     |  Suppresses EOL <-> CRLF conversion on Windows. And
     |  sets external encoding to ASCII-8BIT unless explicitly
     |  specified.
"t"  |  Text file mode (may appear with
     |  any of the key letters listed above except "b").

Using SSIS BIDS with Visual Studio 2012 / 2013

First Off, I object to this other question regarding Visual Studio 2015 as a duplicate question. How do I open SSRS (.rptproj) and SSIS (.dtproj) files in Visual Studio 2015? [duplicate]

Basically this question has the title ...Visual Studio 2012 / 2013 What about ALL the improvements and changes to VS 2015 ??? SSDT has been updated and changed. The entire way of doing various additions and updates is different.

So having vented / rant - I did open a VS 2015 update 2 instance and proceeded to open an existing solution that include a .rptproj project. Now this computer does not yet have sql server installed on it yet.

Solution for ME : Tools --> Extension and Updates --> Updates --> sql server tooling updates

Click on Update button and wait a long time and SSDT then installs and close visual studio 2015 and re-open and it works for me.

In case it is NOT found in VS 2015 for some reason : scroll to the bottom, pick your language iso

Accessing Objects in JSON Array (JavaScript)

You can loop the array with a for loop and the object properties with for-in loops.

for (var i=0; i<result.length; i++)
    for (var name in result[i]) {
        console.log("Item name: "+name);
        console.log("Source: "+result[i][name].sourceUuid);
        console.log("Target: "+result[i][name].targetUuid);

Find provisioning profile in Xcode 5

The following works for me at a command prompt

cd ~/Library/MobileDevice/Provisioning\ Profiles/
for f in *.mobileprovision; do echo $f; openssl asn1parse -inform DER -in $f | grep -A1 application-identifier; done

Finding out which signing keys are used by a particular profile is harder to do with a shell one-liner. Basically you need to do:

openssl asn1parse -inform DER -in your-mobileprovision-filename

then cut-and-paste each block of base64 data after the DeveloperCertificates entry into its own file. You can then use:

openssl asn1parse -inform PEM -in file-with-base64

to dump each certificate. The line after the second commonName in the output will be the key name e.g. "iPhone Developer: Joe Bloggs (ABCD1234X)".

Unexpected token ILLEGAL in webkit

Also for the Google-fodder: check in your text editor whether the .js file is saved as Unicode and consider setting it to ANSI; also check if the linefeeds are set to DOS and consider switching them to Unix (depending on your server, of course).

How do I get the information from a meta tag with JavaScript?

if the meta tag is:

<meta name="url" content="" />

JQuery will be:

const url = $('meta[name="url"]').attr('content'); // url = ''

JavaScript will be: (It will return whole HTML)

const metaHtml = document.getElementsByTagName('meta').url // metaHtml = '<meta name="url" content="" />'

Get the closest number out of an array

All of the solutions are over-engineered.

It is as simple as:

const needle = 5;
const haystack = [1, 2, 3, 4, 5, 6, 7, 8, 9];

haystack.sort((a, b) => {
  return Math.abs(a - needle) - Math.abs(b - needle);

// 5

PHP salt and hash SHA256 for login password

You couldn't login because you did't get proper solt text at login time. There are two options, first is define static salt, second is if you want create dynamic salt than you have to store the salt somewhere (means in database) with associate with user. Than you concatenate user solt+password_hash string now with this you fire query with username in your database table.

Differences between C++ string == and compare()?

compare has overloads for comparing substrings. If you're comparing whole strings you should just use == operator (and whether it calls compare or not is pretty much irrelevant).

Can't connect to MySQL server error 111

If you're running cPanel/WHM, make sure that IP is whitelisted in the firewall. You will als need to add that IP to the remote SQL IP list in the cPanel account you're trying to connect to.

How to install pip for Python 3.6 on Ubuntu 16.10?

This answer assumes that you have python3.6 installed. For python3.7, replace 3.6 with 3.7. For python3.8, replace 3.6 with 3.8, but it may also first require the python3.8-distutils package.

Installation with sudo

With regard to installing pip, using curl (instead of wget) avoids writing the file to disk.

curl | sudo -H python3.6

The -H flag is evidently necessary with sudo in order to prevent errors such as the following when installing pip for an updated python interpreter:

The directory '/home/someuser/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.

The directory '/home/someuser/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.

Installation without sudo

curl | python3.6 - --user

This may sometimes give a warning such as:

WARNING: The script wheel is installed in '/home/ubuntu/.local/bin' which is not on PATH. Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.


After this, pip, pip3, and pip3.6 can all be expected to point to the same target:

$ (pip -V && pip3 -V && pip3.6 -V) | uniq
pip 18.0 from /usr/local/lib/python3.6/dist-packages (python 3.6)

Of course you can alternatively use python3.6 -m pip as well.

$ python3.6 -m pip -V
pip 18.0 from /usr/local/lib/python3.6/dist-packages (python 3.6)

error LNK2038: mismatch detected for '_ITERATOR_DEBUG_LEVEL': value '0' doesn't match value '2' in main.obj

I had this problem as well.

My problem was that I had copy/pasted the library include directories from my debug configurations.

So project "Indep" was including static library "Dep.lib" from "../Debug", even in release. The fix was to change the library directory to "../Release" so I caught the release-built library rather than the previously-built debug library.

C++ getters/setters coding style

I think the C++11 approach would be more like this now.

#include <string>
#include <iostream>
#include <functional>

template<typename T>
class LambdaSetter {
    LambdaSetter() :
        getter([&]() -> T { return m_value; }),
        setter([&](T value) { m_value = value; }),

    T operator()() { return getter(); }
    void operator()(T value) { setter(value); }

    LambdaSetter operator=(T rhs)
        return *this;

    T operator=(LambdaSetter rhs)
        return rhs.getter();

    operator T()
        return getter();

    void SetGetter(std::function<T()> func) { getter = func; }
    void SetSetter(std::function<void(T)> func) { setter = func; }

    T& GetRawData() { return m_value; }

    T m_value;
    std::function<const T()> getter;
    std::function<void(T)> setter;

    template <typename TT>
    friend std::ostream & operator<<(std::ostream &os, const LambdaSetter<TT>& p);

    template <typename TT>
    friend std::istream & operator>>(std::istream &is, const LambdaSetter<TT>& p);

template <typename T>
std::ostream & operator<<(std::ostream &os, const LambdaSetter<T>& p)
    os << p.getter();
    return os;

template <typename TT>
std::istream & operator>>(std::istream &is, const LambdaSetter<TT>& p)
    TT value;
    is >> value;
    return is;

class foo {
        myString.SetGetter([&]() -> std::string { 
            myString.GetRawData() = "Hello";
            return myString.GetRawData();
        myString2.SetSetter([&](std::string value) -> void { 
            myString2.GetRawData() = (value + "!"); 

    LambdaSetter<std::string> myString;
    LambdaSetter<std::string> myString2;

int _tmain(int argc, _TCHAR* argv[])
    foo f;
    std::string hi = f.myString;

    f.myString2 = "world";

    std::cout << hi << " " << f.myString2 << std::endl;

    std::cin >> f.myString2;

    std::cout << hi << " " << f.myString2 << std::endl;

    return 0;

I tested this in Visual Studio 2013. Unfortunately in order to use the underlying storage inside the LambdaSetter I needed to provide a "GetRawData" public accessor which can lead to broken encapsulation, but you can either leave it out and provide your own storage container for T or just ensure that the only time you use "GetRawData" is when you are writing a custom getter/setter method.

Only read selected columns

Say the data are in file data.txt, you can use the colClasses argument of read.table() to skip columns. Here the data in the first 7 columns are "integer" and we set the remaining 6 columns to "NULL" indicating they should be skipped

> read.table("data.txt", colClasses = c(rep("integer", 7), rep("NULL", 6)), 
+            header = TRUE)
  Year Jan Feb Mar Apr May Jun
1 2009 -41 -27 -25 -31 -31 -39
2 2010 -41 -27 -25 -31 -31 -39
3 2011 -21 -27  -2  -6 -10 -32

Change "integer" to one of the accepted types as detailed in ?read.table depending on the real type of data.

data.txt looks like this:

$ cat data.txt 
"Year" "Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov" "Dec"
2009 -41 -27 -25 -31 -31 -39 -25 -15 -30 -27 -21 -25
2010 -41 -27 -25 -31 -31 -39 -25 -15 -30 -27 -21 -25
2011 -21 -27 -2 -6 -10 -32 -13 -12 -27 -30 -38 -29

and was created by using

write.table(dat, file = "data.txt", row.names = FALSE)

where dat is

dat <- structure(list(Year = 2009:2011, Jan = c(-41L, -41L, -21L), Feb = c(-27L, 
-27L, -27L), Mar = c(-25L, -25L, -2L), Apr = c(-31L, -31L, -6L
), May = c(-31L, -31L, -10L), Jun = c(-39L, -39L, -32L), Jul = c(-25L, 
-25L, -13L), Aug = c(-15L, -15L, -12L), Sep = c(-30L, -30L, -27L
), Oct = c(-27L, -27L, -30L), Nov = c(-21L, -21L, -38L), Dec = c(-25L, 
-25L, -29L)), .Names = c("Year", "Jan", "Feb", "Mar", "Apr", 
"May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"), class = "data.frame",
row.names = c(NA, -3L))

If the number of columns is not known beforehand, the utility function count.fields will read through the file and count the number of fields in each line.

## returns a vector equal to the number of lines in the file
count.fields("data.txt", sep = "\t")
## returns the maximum to set colClasses
max(count.fields("data.txt", sep = "\t"))

Cannot make a static reference to the non-static method fxn(int) from the type Two

You can't access the method fxn since it's not static. Static methods can only access other static methods directly. If you want to use fxn in your main method you need to:

Two two = new Two();
x = two.fxn(x)

That is, make a Two-Object and call the method on that object.

...or make the fxn method static.

Create Carriage Return in PHP String?

Carriage return is "\r". Mind the double quotes!

I think you want "\r\n" btw to put a line break in your text so it will be rendered correctly in different operating systems.

  • Mac: \r
  • Linux/Unix: \n
  • Windows: \r\n

Getting byte array through input type = file

    (function (document) {_x000D_
  var input = document.getElementById("files"),_x000D_
  output = document.getElementById("result"),_x000D_
  fileData; // We need fileData to be visible to getBuffer._x000D_
  // Eventhandler for file input. _x000D_
  function openfile(evt) {_x000D_
    var files = input.files;_x000D_
    // Pass the file to the blob, not the input[0]._x000D_
    fileData = new Blob([files[0]]);_x000D_
    // Pass getBuffer to promise._x000D_
    var promise = new Promise(getBuffer);_x000D_
    // Wait for promise to be resolved, or log error._x000D_
    promise.then(function(data) {_x000D_
      // Here you can pass the bytes to another function._x000D_
      output.innerHTML = data.toString();_x000D_
    }).catch(function(err) {_x000D_
      console.log('Error: ',err);_x000D_
  /* _x000D_
    Create a function which will be passed to the promise_x000D_
    and resolve it when FileReader has finished loading the file._x000D_
  function getBuffer(resolve) {_x000D_
    var reader = new FileReader();_x000D_
    reader.onload = function() {_x000D_
      var arrayBuffer = reader.result_x000D_
      var bytes = new Uint8Array(arrayBuffer);_x000D_
  // Eventlistener for file input._x000D_
  input.addEventListener('change', openfile, false);_x000D_
<!DOCTYPE html>_x000D_
<script src=""></script>_x000D_
<input type="file" id="files"/>_x000D_
<div id="result"></div>_x000D_

Swift 3 URLSession.shared() Ambiguous reference to member 'dataTask(with:completionHandler:) error (bug)

let task = URLSession.shared.dataTask(with: request as URLRequest, completionHandler: { data,response,error in
        if error != nil{
        if let responseJSON = (try? JSONSerialization.jsonObject(with: data!, options: [])) as? [String:AnyObject]{
            if let response_token:String = responseJSON["token"] as? String {
                print("Singleton Firebase Token : \(response_token)")

Comparing object properties in c#

I would add the following line to the PublicInstancePropertiesEqual method to avoid copy & paste errors:

Assert.AreNotSame(self, to);

Adding a caption to an equation in LaTeX

You may want to look at which allows you to define new floats using \newfloat

I say this because captions are usually applied to floats.

Straight ahead equations (those written with $ ... $, $$ ... $$, begin{equation}...) are in-line objects that do not support \caption.

This can be done using the following snippet just before \begin{document}



and when adding an equation use something like

f( x ) = ax + b
\caption{Caption goes here}

How do you explicitly set a new property on `window` in TypeScript?

For those using the Angular CLI it's straightforward:


declare global {
  interface Window {
    myCustomFn: () => void;


window.myCustomFn = function () {

If you're using IntelliJ, you also needed to change the following setting in the IDE before your new polyfills pick up:

> File 
> Settings 
> Languages & Frameworks 
> TypeScript 
> check 'Use TypeScript Service'.

How to compare values which may both be null in T-SQL

You will have to use IS NULL or ISNULL. There really isn't a away around it.

Angularjs: input[text] ngChange fires while the value is changing

This post shows an example of a directive that delays the model changes to an input until the blur event fires.

Here is a fiddle that shows the ng-change working with the new ng-model-on-blur directive. Note this is a slight tweak to the original fiddle.

If you add the directive to your code you would change your binding to this:

<input type="text" ng-model="name" ng-model-onblur ng-change="update()" />

Here is the directive:

// override the default input to update on blur
angular.module('app', []).directive('ngModelOnblur', function() {
    return {
        restrict: 'A',
        require: 'ngModel',
        priority: 1, // needed for angular 1.2.x
        link: function(scope, elm, attr, ngModelCtrl) {
            if (attr.type === 'radio' || attr.type === 'checkbox') return;

            elm.bind('blur', function() {
                scope.$apply(function() {

Note: as @wjin mentions in the comments below this feature is supported directly in Angular 1.3 (currently in beta) via ngModelOptions. See the docs for more info.

How to call a shell script from python code?

Subprocess is good but some people may like scriptine better. Scriptine has more high-level set of methods like, path.rename(new_name) and path.move(src,dst). Scriptine is based on subprocess and others.

Two drawbacks of scriptine:

  • Current documentation level would be more comprehensive even though it is sufficient.
  • Unlike subprocess, scriptine package is currently not installed by default.

Time in milliseconds in C

The standard C library provides timespec_get. It can tell time up to nanosecond precision, if the system supports. Calling it, however, takes a bit more effort because it involves a struct. Here's a function that just converts the struct to a simple 64-bit integer so you can get time in milliseconds.

#include <stdio.h>
#include <inttypes.h>
#include <time.h>

int64_t millis()
    struct timespec now;
    timespec_get(&now, TIME_UTC);
    return ((int64_t) now.tv_sec) * 1000 + ((int64_t) now.tv_nsec) / 1000000;

int main(void)
    printf("Unix timestamp with millisecond precision: %" PRId64 "\n", millis());

Unlike clock, this function returns a Unix timestamp so it will correctly account for the time spent in blocking functions, such as sleep.

Local and global temporary tables in SQL Server

1.) A local temporary table exists only for the duration of a connection or, if defined inside a compound statement, for the duration of the compound statement.

Local temp tables are only available to the SQL Server session or connection (means single user) that created the tables. These are automatically deleted when the session that created the tables has been closed. Local temporary table name is stared with single hash ("#") sign.

 UserID int,
 Name varchar(50), 
 Address varchar(150)
insert into #LocalTemp values ( 1, 'Name','Address');
Select * from #LocalTemp

The scope of Local temp table exist to the current session of current user means to the current query window. If you will close the current query window or open a new query window and will try to find above created temp table, it will give you the error.

2.) A global temporary table remains in the database permanently, but the rows exist only within a given connection. When connection is closed, the data in the global temporary table disappears. However, the table definition remains with the database for access when database is opened next time.

Global temp tables are available to all SQL Server sessions or connections (means all the user). These can be created by any SQL Server connection user and these are automatically deleted when all the SQL Server connections have been closed. Global temporary table name is stared with double hash ("##") sign.

 UserID int,
 Name varchar(50), 
 Address varchar(150)
insert into ##GlobalTemp values ( 1, 'Name','Address');
Select * from ##GlobalTemp

Global temporary tables are visible to all SQL Server connections while Local temporary tables are visible to only current SQL Server connection.

JAX-WS and BASIC authentication, when user names and passwords are in a database

If you put the username and password at clientside into the request this way:

URL url = new URL("http://localhost:8080/myapplication?wsdl");
MyWebService webservice = new MyWebServiceImplService(url).getMyWebServiceImplPort();
Map<String, Object> requestContext = ((BindingProvider) webservice).getRequestContext();
requestContext.put(BindingProvider.USERNAME_PROPERTY, "myusername");
requestContext.put(BindingProvider.PASSWORD_PROPERTY, "mypassword");

and call your webservice

String response = webservice.someMethodAtMyWebservice("test");

Then you can read the Basic Authentication string like this at the server side (you have to add some checks and do some exceptionhandling):

WebServiceContext webserviceContext;

public void someMethodAtMyWebservice(String parameter) {
    MessageContext messageContext = webserviceContext.getMessageContext();
    Map<String, ?> httpRequestHeaders = (Map<String, ?>) messageContext.get(MessageContext.HTTP_REQUEST_HEADERS);
    List<?> authorizationList = (List<?>) httpRequestHeaders.get("Authorization");
    if (authorizationList != null && !authorizationList.isEmpty()) {
        String basicString = (String) authorizationList.get(0);
        String encodedBasicString = basicString.substring("Basic ".length());
        String decoded = new String(Base64.getDecoder().decode(encodedBasicString), StandardCharsets.UTF_8);
        String[] splitter = decoded.split(":");
        String usernameFromBasicAuth = splitter[0];
        String passwordFromBasicAuth = splitter[1];

Counting Line Numbers in Eclipse

A very simple plugin for counting actual lines of source code is step counter eclipse plugin. Please download and try.

github link

Place the downloaded jar file under eclipse\plugin folder and restart eclipse.

Rightclick and select step counter enter image description here

Step Result enter image description here

How do I POST a x-www-form-urlencoded request using Fetch?

According to the spec, using encodeURIComponent won't give you a conforming query string. It states:

  1. Control names and values are escaped. Space characters are replaced by +, and then reserved characters are escaped as described in [RFC1738], section 2.2: Non-alphanumeric characters are replaced by %HH, a percent sign and two hexadecimal digits representing the ASCII code of the character. Line breaks are represented as "CR LF" pairs (i.e., %0D%0A).
  2. The control names/values are listed in the order they appear in the document. The name is separated from the value by = and name/value pairs are separated from each other by &.

The problem is, encodeURIComponent encodes spaces to be %20, not +.

The form-body should be coded using a variation of the encodeURIComponent methods shown in the other answers.

const formUrlEncode = str => {
  return str.replace(/[^\d\w]/g, char => {
    return char === " " 
      ? "+" 
      : encodeURIComponent(char);

const data = {foo: "bar߃©??  baz", boom: "pow"};

const dataPairs = Object.keys(data).map( key => {
  const val = data[key];
  return (formUrlEncode(key) + "=" + formUrlEncode(val));

// dataPairs is "foo=bar%C3%9F%C6%92%C2%A9%CB%99%E2%88%91++baz&boom=pow"

If statement for strings in python?

Python is case sensitive and needs proper indentation. You need to use lowercase "if", indent your conditions properly and the code has a bug. proceed will evaluate to y

How to make php display \t \n as tab and new line instead of characters

"\n" = new line
'\n' = \n
"\t" = tab
'\t' = \t

How to pass arguments and redirect stdin from a file to program run in gdb?

Start GDB on your project.

  1. Go to project directory, where you've already compiled the project executable. Issue the command gdb and the name of the executable as below:

    gdb projectExecutablename

This starts up gdb, prints the following: GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04) 7.11.1 Copyright (C) 2016 Free Software Foundation, Inc. ................................................. Type "apropos word" to search for commands related to "word"... Reading symbols from projectExecutablename...done. (gdb)

  1. Before you start your program running, you want to set up your breakpoints. The break command allows you to do so. To set a breakpoint at the beginning of the function named main:

    (gdb) b main

  2. Once you've have the (gdb) prompt, the run command starts the executable running. If the program you are debugging requires any command-line arguments, you specify them to the run command. If you wanted to run my program on the "xfiles" file (which is in a folder "mulder" in the project directory), you'd do the following:

    (gdb) r mulder/xfiles

Hope this helps.

Disclaimer: This solution is not mine, it is adapted from This short guide to gdb was, most probably, developed at Stanford University.

I get a "An attempt was made to load a program with an incorrect format" error on a SQL Server replication project

change it to 32-bit (true) it works

if you get this Length cannot be less than zero. Parameter name: length issue in iis server configuation do the simple thing change the connection string in web.config file like your sql server name and server name and restart iis then try to load the page it works

AttributeError: 'module' object has no attribute 'model'

As the error message says in the last line: the module models in the file c:\projects\mysite..\mysite\polls\ contains no class model. This error occurs in the definition of the Poll class:

class Poll(models.model):

Either the class model is misspelled in the definition of the class Poll or it is misspelled in the module models. Another possibility is that it is completely missing from the module models. Maybe it is in another module or it is not yet implemented in models.

SQL Server FOR EACH Loop

declare @counter as int
set @counter = 0
declare @date as varchar(50)
set @date = cast(1+@counter as varchar)+'/01/2013'
while(@counter < 12)
select  cast(1+@counter as varchar)+'/01/2013' as date
set @counter = @counter + 1

Javascript window.print() in chrome, closing new window or tab instead of cancelling print leaves javascript blocked in parent window

Run this code It will open google print service popup.

function openPrint(x) {

   if (x > 0) { 
       openPrint(--x); print(x); openPrint(--x);


Try it on console where x is integer .

openPrint(1);   // Will open Chrome Print Popup Once
openPrint(2);   // Will open Chrome Print Popup Twice after 1st close and so on


How do I set up a simple delegate to communicate between two view controllers?

Following solution is very basic and simple approach to send data from VC2 to VC1 using delegate .

PS: This solution is made in Xcode 9.X and Swift 4

Declared a protocol and created a delegate var into ViewControllerB

    import UIKit

    //Declare the Protocol into your SecondVC
    protocol DataDelegate {
        func sendData(data : String)

    class ViewControllerB : UIViewController {

    //Declare the delegate property in your SecondVC
        var delegate : DataDelegate?
        var data : String = "Send data to ViewControllerA."
        override func viewDidLoad() {

        @IBAction func btnSendDataPushed(_ sender: UIButton) {
                // Call the delegate method from SecondVC
                dismiss(animated: true, completion: nil)

ViewControllerA confirms the protocol and expected to receive data via delegate method sendData

    import UIKit
        // Conform the  DataDelegate protocol in ViewControllerA
        class ViewControllerA : UIViewController , DataDelegate {
        @IBOutlet weak var dataLabel: UILabel!

        override func viewDidLoad() {

        @IBAction func presentToChild(_ sender: UIButton) {
            let childVC =  UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier:"ViewControllerB") as! ViewControllerB
            //Registered delegate
            childVC.delegate = self
            self.present(childVC, animated: true, completion: nil)

        // Implement the delegate method in ViewControllerA
        func sendData(data : String) {
            if data != "" {
                self.dataLabel.text = data

What is WEB-INF used for in a Java EE web application?

This convention is followed for security reasons. For example if unauthorized person is allowed to access root JSP file directly from URL then they can navigate through whole application without any authentication and they can access all the secured data.

How to enable Logger.debug() in Log4j

If you are coming here because you are using Apache commons logging with log4j and log4j isn't working as you expect then check that you actually have a log4j.jar in your run-time classpath. That one had me puzzled for a little while. I have now configured the runner in my dev environment to include -Dlog4j.debug in the Java command line so I can always see that Log4j is being initialized correctly

If statement with String comparison fails

Strings in java are objects, so when comparing with ==, you are comparing references, rather than values. The correct way is to use equals().

However, there is a way. If you want to compare String objects using the == operator, you can make use of the way the JVM copes with strings. For example:

String a = "aaa";
String b = "aaa";
boolean b = a == b;

b would be true. Why?

Because the JVM has a table of String constants. So whenever you use string literals (quotes "), the virtual machine returns the same objects, and therefore == returns true.

You can use the same "table" even with non-literal strings by using the intern() method. It returns the object that corresponds to the current string value from that table (or puts it there, if it is not). So:

String a = new String("aa");
String b = new String("aa");
boolean check1 = a == b; // false
boolean check1 = a.intern() == b.intern(); // true

It follows that for any two strings s and t, s.intern() == t.intern() is true if and only if s.equals(t) is true.

ApiNotActivatedMapError for simple html page using google-places-api

I had the same error. To fix the error:

  1. Open the console menu Gallery Menu and select API Manager.
  2. On the left, click Credentials and then click New Credentials.
  3. Click Create Credentials.
  4. Click API KEY.
  5. Click Navigator Key (there are more options; It depends on when consumed).

You must use this new API Navigator Key, generated by the system.

correct way to use super (argument passing)

Sometimes two classes may have some parameter names in common. In that case, you can't pop the key-value pairs off of **kwargs or remove them from *args. Instead, you can define a Base class which unlike object, absorbs/ignores arguments:

class Base(object):
    def __init__(self, *args, **kwargs): pass

class A(Base):
    def __init__(self, *args, **kwargs):
        print "A"
        super(A, self).__init__(*args, **kwargs)

class B(Base):
    def __init__(self, *args, **kwargs):
        print "B"
        super(B, self).__init__(*args, **kwargs)

class C(A):
    def __init__(self, arg, *args, **kwargs):
        print "C","arg=",arg
        super(C, self).__init__(arg, *args, **kwargs)

class D(B):
    def __init__(self, arg, *args, **kwargs):
        print "D", "arg=",arg
        super(D, self).__init__(arg, *args, **kwargs)

class E(C,D):
    def __init__(self, arg, *args, **kwargs):
        print "E", "arg=",arg
        super(E, self).__init__(arg, *args, **kwargs)

print "MRO:", [x.__name__ for x in E.__mro__]


MRO: ['E', 'C', 'A', 'D', 'B', 'Base', 'object']
E arg= 10
C arg= 10
D arg= 10

Note that for this to work, Base must be the penultimate class in the MRO.

JavaScript - XMLHttpRequest, Access-Control-Allow-Origin errors

I think you've missed the point of access control.

A quick recap on why CORS exists: Since JS code from a website can execute XHR, that site could potentially send requests to other sites, masquerading as you and exploiting the trust those sites have in you(e.g. if you have logged in, a malicious site could attempt to extract information or execute actions you never wanted) - this is called a CSRF attack. To prevent that, web browsers have very stringent limitations on what XHR you can send - you are generally limited to just your domain, and so on.

Now, sometimes it's useful for a site to allow other sites to contact it - sites that provide APIs or services, like the one you're trying to access, would be prime candidates. CORS was developed to allow site A(e.g. to say "I trust site B, so you can send XHR from it to me". This is specified by site A sending "Access-Control-Allow-Origin" headers in its responses.

In your specific case, it seems that doesn't bother to use CORS. Your best bet is to contact the site owner and find out why, if you want to use with a browser script. Alternatively, you could try using an extension(those should have higher XHR privileges).

Automatic creation date for Django model form objects?

Well, the above answer is correct, auto_now_add and auto_now would do it, but it would be better to make an abstract class and use it in any model where you require created_at and updated_at fields.

class TimeStampMixin(models.Model):
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True

Now anywhere you want to use it you can do a simple inherit and you can use timestamp in any model you make like.

class Posts(TimeStampMixin):
    name = models.CharField(max_length=50)

In this way, you can leverage object-oriented reusability, in Django DRY(don't repeat yourself)

What is the Linux equivalent to DOS pause?

This function works in both bash and zsh, and ensures I/O to the terminal:

# Prompt for a keypress to continue. Customise prompt with $*
function pause {
  >/dev/tty printf '%s' "${*:-Press any key to continue... }"
  [[ $ZSH_VERSION ]] && read -krs  # Use -u0 to read from STDIN
  [[ $BASH_VERSION ]] && </dev/tty read -rsn1
  printf '\n'
export_function pause

Put it in your .{ba,z}shrc for Great Justice!

Fatal error: Maximum execution time of 300 seconds exceeded

In my case, when I faced that error in Phpmyadmin, I tried MySQL-Front and import my DB successfully.

Note: You can still use the provided solutions under this question to solve your problem in Phpmyadmin.

Waiting for HOME ('android.process.acore') to be launched

I had only 12 Mb for the SD Card in the AVD device.

Increasing it to 2 Gb solved the issue.

How to convert UTF8 string to byte array?

I was using Joni's solution and it worked fine, but this one is much shorter.

This was inspired by the atobUTF16() function of Solution #3 of Mozilla's Base64 Unicode discussion

function convertStringToUTF8ByteArray(str) {
    let binaryArray = new Uint8Array(str.length), function (el, idx, arr) { arr[idx] = str.charCodeAt(idx) })
    return binaryArray

How to have a default option in Angular.js select box

If you have some thing instead of just init the date part, you can use ng-init() by declare it in your controller, and use it in the top of your HTML. This function will work like a constructor for your controller, and you can initiate your variables there.

angular.module('myApp', [])
 .controller('myController', ['$scope', ($scope) => {
   $scope.allOptions = [
     { name: 'Apple', value: 'apple' }, 
     { name: 'Banana', value: 'banana' }
   $scope.myInit = () => {
      $scope.userSelected = 'apple'
      // Other initiations can goes here..

<body ng-app="myApp">
  <div ng-controller="myController" ng-init="init()">
    <select ng-model="userSelected" ng-options="option.value as for option in allOptions"></select>

Execute jar file with multiple classpath libraries from command prompt

You cannot use both -jar and -cp on the command line - see the java documentation that says that if you use -jar:

the JAR file is the source of all user classes, and other user class path settings are ignored.

You could do something like this:

java -cp lib\*.jar;. myproject.MainClass

Notice the ;. in the -cp argument, to work around a Java command-line bug. Also, please note that this is the Windows version of the command. The path separator on Unix is :.

What is difference between Axios and Fetch?

Axios is a stand-alone 3rd party package that can be easily installed into a React project using NPM.

The other option you mentioned is the fetch function. Unlike Axios, fetch() is built into most modern browsers. With fetch you do not need to install a third party package.

So its up to you, you can go with fetch() and potentially mess up if you don't know what you are doing OR just use Axios which is more straightforward in my opinion.

How to re-sign the ipa file?

  1. Unzip the .ipa file by changing its extension with .zip
  2. Go to Payload. You will find .app file
  3. Right click the .app file and click Show package contents
  4. Delete the _CodeSigned folder
  5. Replace the embedded.mobileprovision file with the new provision profile
  6. Go to KeyChain Access and make sure the certificate associated with the provisional profile is present
  7. Execute the below mentioned command: /usr/bin/codesign -f -s "iPhone Distribution: Certificate Name" --resource-rules "Payload/" "Payload/"

  8. Now zip the Payload folder again and change the .zip extension with .ipa

Hope this helpful.

For reference follow below mentioned link:

How can I get a Bootstrap column to span multiple rows?

Like the comments suggest, the solution is to use nested spans/rows.

<div class="container">
    <div class="row">
        <div class="span4">1</div>
        <div class="span8">
            <div class="row">
                <div class="span4">2</div>
                <div class="span4">3</div>
            <div class="row">
                <div class="span4">4</div>
                <div class="span4">5</div>
    <div class="row">
        <div class="span4">6</div>
        <div class="span4">7</div>
        <div class="span4">8</div>

How to find longest string in the table column data


Python string class like StringBuilder in C#?

Relying on compiler optimizations is fragile. The benchmarks linked in the accepted answer and numbers given by Antoine-tran are not to be trusted. Andrew Hare makes the mistake of including a call to repr in his methods. That slows all the methods equally but obscures the real penalty in constructing the string.

Use join. It's very fast and more robust.

$ ipython3
Python 3.5.1 (default, Mar  2 2016, 03:38:02) 
IPython 4.1.2 -- An enhanced Interactive Python.

In [1]: values = [str(num) for num in range(int(1e3))]

In [2]: %%timeit
   ...: ''.join(values)
100000 loops, best of 3: 7.37 µs per loop

In [3]: %%timeit
   ...: result = ''
   ...: for value in values:
   ...:     result += value
10000 loops, best of 3: 82.8 µs per loop

In [4]: import io

In [5]: %%timeit
   ...: writer = io.StringIO()
   ...: for value in values:
   ...:     writer.write(value)
   ...: writer.getvalue()
10000 loops, best of 3: 81.8 µs per loop

Bootstrap tab activation with JQuery

Perform a click on the link to the tab anchor whenever the page is ready i.e.

$('a[href="' + window.location.hash + '"]').trigger('click');

Or in vanilla JavaScript

document.querySelector('a[href="' + window.location.hash + '"]').click();

How do I check OS with a preprocessor directive?

In most cases it is better to check whether a given functionality is present or not. For example: if the function pipe() exists or not.

Get Application Directory

For current Android application package:

public String getDataDir(Context context) throws Exception {
    return context.getPackageManager().getPackageInfo(context.getPackageName(), 0).applicationInfo.dataDir;

For any package:

public String getAnyDataDir(Context context, String packageName) throws Exception {
    return context.getPackageManager().getPackageInfo(packageName, 0).applicationInfo.dataDir;

How to cut a string after a specific character in unix

This should do the trick:

$ echo "$var" | awk -F':' '{print $NF}'

Python Pandas: How to read only first n rows of CSV files in?

If you only want to read the first 999,999 (non-header) rows:

read_csv(..., nrows=999999)

If you only want to read rows 1,000,000 ... 1,999,999

read_csv(..., skiprows=1000000, nrows=999999)

nrows : int, default None Number of rows of file to read. Useful for reading pieces of large files*

skiprows : list-like or integer Row numbers to skip (0-indexed) or number of rows to skip (int) at the start of the file

and for large files, you'll probably also want to use chunksize:

chunksize : int, default None Return TextFileReader object for iteration documentation

AngularJS $resource RESTful example

you can just do $scope.todo = Todo.get({ id: 123 }). .get() and .query() on a Resource return an object immediately and fill it with the result of the promise later (to update your template). It's not a typical promise which is why you need to either use a callback or the $promise property if you have some special code you want executed after the call. But there is no need to assign it to your scope in a callback if you are only using it in the template.

Pandas DataFrame: replace all values in a column, based on condition

We can update the First Season column in df with the following syntax:

df['First Season'] = expression_for_new_values

To map the values in First Season we can use pandas‘ .map() method with the below syntax:


Read text from response

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("");
request.Method = "GET";
HttpWebResponse response = (HttpWebResponse)request.GetResponse();

Stream dataStream = response.GetResponseStream();
StreamReader reader = new StreamReader(dataStream);
string strResponse = reader.ReadToEnd();

Watermark / hint text / placeholder TextBox


    <Style x:Key="TextBoxUserStyle" BasedOn="{x:Null}" TargetType="{x:Type TextBox}">
      <Setter Property="Foreground" Value="Black"/>
      <Setter Property="HorizontalAlignment" Value="Center"/>
      <Setter Property="VerticalContentAlignment" Value="Center"/>
      <Setter Property="Width" Value="225"/>
      <Setter Property="Height" Value="25"/>
      <Setter Property="FontSize" Value="12"/>
      <Setter Property="Padding" Value="1"/>
      <Setter Property="Margin" Value="5"/>
      <Setter Property="AllowDrop" Value="true"/>
      <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
      <Setter Property="Template">
          <ControlTemplate TargetType="{x:Type TextBox}">
            <Border x:Name="OuterBorder" BorderBrush="#5AFFFFFF" BorderThickness="1,1,1,1" CornerRadius="4,4,4,4">
              <Border x:Name="InnerBorder" Background="#FFFFFFFF" BorderBrush="#33000000" BorderThickness="1,1,1,1" CornerRadius="3,3,3,3">
                <ScrollViewer SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" x:Name="PART_ContentHost"/>

    <Style x:Key="PasswordBoxVistaStyle" BasedOn="{x:Null}" TargetType="{x:Type PasswordBox}">
      <Setter Property="Foreground" Value="Black"/>
      <Setter Property="HorizontalAlignment" Value="Center"/>
      <Setter Property="VerticalContentAlignment" Value="Center"/>
      <Setter Property="Width" Value="225"/>
      <Setter Property="Height" Value="25"/>
      <Setter Property="FontSize" Value="12"/>
      <Setter Property="Padding" Value="1"/>
      <Setter Property="Margin" Value="5"/>
      <Setter Property="AllowDrop" Value="true"/>
      <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
      <Setter Property="Template">
          <ControlTemplate TargetType="{x:Type PasswordBox}">
            <Border x:Name="OuterBorder" BorderBrush="#5AFFFFFF" BorderThickness="1,1,1,1" CornerRadius="4,4,4,4">
              <Border x:Name="InnerBorder" Background="#FFFFFFFF" BorderBrush="#33000000" BorderThickness="1,1,1,1" CornerRadius="3,3,3,3">
                  <Label x:Name="lblPwd" Content="Password" FontSize="11" VerticalAlignment="Center" Margin="2,0,0,0" FontFamily="Verdana" Foreground="#828385" Padding="0"/>
                  <ScrollViewer SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" x:Name="PART_ContentHost"/>
              <Trigger Property="IsFocused" Value="True">
                <Setter Property="Visibility" TargetName="lblPwd" Value="Hidden"/>

        <PasswordBox Style="{StaticResource PasswordBoxVistaStyle}" Margin="169,143,22,0" Name="txtPassword" FontSize="14" TabIndex="2" Height="31" VerticalAlignment="Top" />

This can help check it with your code.When applied to password box,it will show Password,which will disappear when usertypes.

Running Facebook application on localhost

You need to setup your app to run over https for localhost

You can follow steps given in this to setup HTTPS on ubuntu

You need to do following steps:

install apache (if you do not have)

sudo apt-get install apache2

Step One—Activate the SSL Module

sudo a2enmod ssl
sudo service apache2 restart

Step Two—Create a New Directory

sudo mkdir /etc/apache2/ssl

Step Three—Create a Self Signed SSL Certificate

sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/apache/ssl/apache.key -out /etc/apache2/ssl/apache.crt

With this command, we will be both creating the self-signed SSL certificate and the server key that protects it, and placing both of them into the new directory. The most important line is "Common Name". Enter your official domain name here or, if you don't have one yet, your site's IP address.

Common Name (e.g. server FQDN or YOUR name) [] or localhost

Step Four—Set Up the Certificate

sudo vim /etc/apache2/sites-available/default-ssl

Find following lines and edit those with your settings

ServerName localhost or

SSLEngine on SSLCertificateFile /etc/apache2/ssl/apache.crt

SSLCertificateKeyFile /etc/apache2/ssl/apache.key

Step Five—Activate the New Virtual Host

sudo a2ensite default-ssl
sudo service apache2 reload

How do I refresh a DIV content?

For div refreshing without creating div inside yours with same id, you should use this inside your function

$("#yourDiv").load(" #yourDiv > *");

Python Inverse of a Matrix

For those like me, who were looking for a pure Python solution without pandas or numpy involved, check out the following GitHub project:

It generously provides a very good explanation of how the process looks like "behind the scenes". The author has nicely described the step-by-step approach and presented some practical examples, all easy to follow.

This is just a little code snippet from there to illustrate the approach very briefly (AM is the source matrix, IM is the identity matrix of the same size):

def invert_matrix(AM, IM):
    for fd in range(len(AM)):
        fdScaler = 1.0 / AM[fd][fd]
        for j in range(len(AM)):
            AM[fd][j] *= fdScaler
            IM[fd][j] *= fdScaler
        for i in list(range(len(AM)))[0:fd] + list(range(len(AM)))[fd+1:]:
            crScaler = AM[i][fd]
            for j in range(len(AM)):
                AM[i][j] = AM[i][j] - crScaler * AM[fd][j]
                IM[i][j] = IM[i][j] - crScaler * IM[fd][j]
    return IM

But please do follow the entire thing, you'll learn a lot more than just copy-pasting this code! There's a Jupyter notebook as well, btw.

Hope that helps someone, I personally found it extremely useful for my very particular task (Absorbing Markov Chain) where I wasn't able to use any non-standard packages.

How to prevent SIGPIPEs (or handle them properly)

Handle SIGPIPE Locally

It's usually best to handle the error locally rather than in a global signal event handler since locally you will have more context as to what's going on and what recourse to take.

I have a communication layer in one of my apps that allows my app to communicate with an external accessory. When a write error occurs I throw and exception in the communication layer and let it bubble up to a try catch block to handle it there.


The code to ignore a SIGPIPE signal so that you can handle it locally is:

// We expect write failures to occur but we want to handle them where 
// the error occurs rather than in a SIGPIPE handler.

This code will prevent the SIGPIPE signal from being raised, but you will get a read / write error when trying to use the socket, so you will need to check for that.

dismissModalViewControllerAnimated deprecated

[self dismissModalViewControllerAnimated:NO]; has been deprecated.

Use [self dismissViewControllerAnimated:NO completion:nil]; instead.

how to set default method argument values?

You can overload the method with different parameters:

public int doSomething(int arg1, int arg2)
//some logic here
        return 0;

public int doSomething(

Angular2 Routing with Hashtag to page anchor

Unlike other answers I'd additionally also add focus() along with scrollIntoView(). Also I'm using setTimeout since it jumps to top otherwise when changing the URL. Not sure what was the reason for that but it seems setTimeout does the workaround.


<a [routerLink] fragment="some-id" (click)="scrollIntoView('some-id')">Jump</a>


<a id="some-id" tabindex="-1"></a>


scrollIntoView(anchorHash) {
    setTimeout(() => {
        const anchor = document.getElementById(anchorHash);
        if (anchor) {

Execution failed for task ':app:compileDebugJavaWithJavac' Android Studio 3.1 Update

Just solve the problem which come from java compiler instead of Build-Run task

Programmatically obtain the phone number of the Android phone

while working on a security app which needed to get the phone number of who so ever my phone might get into their hands, I had to do this; 1. receive Boot completed and then try getting Line1_Number from telephonyManager which returns a string result. 2. compare the String result with my own phone number and if they don't match or string returns null then, 3. secretly send an SMS containing the string result plus a special sign to my office number. 4. if message sending fails, start a service and keep trying after each hour until sent SMS pending intent returns successful. With this steps I could get the number of the person using my lost phone. it doesn't matter if the person is charged.

MS Access DB Engine (32-bit) with Office 64-bit

Install the 2007 version, it seems that if you install the version opposite to the version of Office you are using you can make it work.

Git ignore file for Xcode projects

You should checkout for Objective-C and Swift.

Here is the .gitignore file I'm using:

# Xcode


PostgreSQL error: Fatal: role "username" does not exist

Use the operating system user postgres to create your database - as long as you haven't set up a database role with the necessary privileges that corresponds to your operating system user of the same name (h9uest in your case):

sudo -u postgres -i

As recommended here or here.

Then try again. Type exit when done with operating as system user postgres.

Or execute the single command createuser as postgres with sudo, like demonstrated by drees in another answer.

The point is to use the operating system user matching the database role of the same name to be granted access via ident authentication. postgres is the default operating system user to have initialized the database cluster. The manual:

In order to bootstrap the database system, a freshly initialized system always contains one predefined role. This role is always a “superuser”, and by default (unless altered when running initdb) it will have the same name as the operating system user that initialized the database cluster. Customarily, this role will be named postgres. In order to create more roles you first have to connect as this initial role.

I have heard of odd setups with non-standard user names or where the operating system user does not exist. You'd need to adapt your strategy there.

Read about database roles and client authentication in the manual.

Why use sys.path.append(path) instead of sys.path.insert(1, path)?

If you have multiple versions of a package / module, you need to be using virtualenv (emphasis mine):

virtualenv is a tool to create isolated Python environments.

The basic problem being addressed is one of dependencies and versions, and indirectly permissions. Imagine you have an application that needs version 1 of LibFoo, but another application requires version 2. How can you use both these applications? If you install everything into /usr/lib/python2.7/site-packages (or whatever your platform’s standard location is), it’s easy to end up in a situation where you unintentionally upgrade an application that shouldn’t be upgraded.

Or more generally, what if you want to install an application and leave it be? If an application works, any change in its libraries or the versions of those libraries can break the application.

Also, what if you can’t install packages into the global site-packages directory? For instance, on a shared host.

In all these cases, virtualenv can help you. It creates an environment that has its own installation directories, that doesn’t share libraries with other virtualenv environments (and optionally doesn’t access the globally installed libraries either).

That's why people consider insert(0, to be wrong -- it's an incomplete, stopgap solution to the problem of managing multiple environments.

java.lang.IllegalStateException: The specified child already has a parent

It also happens when the view returned by onCreateView() isn't the view that was inflated.


View rootView = inflater.inflate(R.layout.my_fragment, container, false);

TextView textView = (TextView) rootView.findViewById(;
textView.setText("Some text.");

return textView;


return rootView;

Instead of:

return textView; // or whatever you returned

how to inherit Constructor from super class to sub class

Default constructors -- public constructors with out arguments (either declared or implied) -- are inherited by default. You can try the following code for an example of this:

public class CtorTest {
    public static void main(String[] args) {
        final Sub sub = new Sub();

    private static class Base {
        public Base() {
            System.err.println("In Base ctor");

    private static class Sub extends Base {
        public Sub() {
            System.err.println("In Sub ctor");

If you want to explicitly call a constructor from a super class, you need to do something like this:

public class Ctor2Test {
    public static void main(String[] args) {
        final Sub sub = new Sub();

    private static class Base {
        public Base() {
            System.err.println("In Base ctor");

        public Base(final String toPrint) {
            System.err.println("In Base ctor.  To Print: " + toPrint);

    private static class Sub extends Base {
        public Sub() {
            super("Hello World!");
            System.err.println("In Sub ctor");

The only caveat is that the super() call must come as the first line of your constructor, else the compiler will get mad at you.

How to search text using php if ($text contains "World")

This might be what you are looking for:


$text = 'This is a Simple text.';

// this echoes "is is a Simple text." because 'i' is matched first
echo strpbrk($text, 'mi');

// this echoes "Simple text." because chars are case sensitive
echo strpbrk($text, 'S');

Is it?

Or maybe this:

$mystring = 'abc';
$findme   = 'a';
$pos = strpos($mystring, $findme);

// Note our use of ===.  Simply == would not work as expected
// because the position of 'a' was the 0th (first) character.
if ($pos === false) {
    echo "The string '$findme' was not found in the string '$mystring'";
} else {
    echo "The string '$findme' was found in the string '$mystring'";
    echo " and exists at position $pos";

Or even this

$email  = '[email protected]';
$domain = strstr($email, '@');
echo $domain; // prints

$user = strstr($email, '@', true); // As of PHP 5.3.0
echo $user; // prints name

You can read all about them in the documentation here:

How to add a column in TSQL after a specific column?

Unfortunately you can't.

If you really want them in that order you'll have to create a new table with the columns in that order and copy data. Or rename columns etc. There is no easy way.

Allow access permission to write in Program Files of Windows 7

You can't cause a .Net application to elevate its own rights. It's simply not allowed. The best you can do is to specify elevated rights when you spawn another process. In this case you would have a two-stage application launch.

Stage 1 does nothing but prepare an elevated spawn using the System.Diagnostics.ProcessStartInfo object and the Start() call.

Stage 2 is the application running in an elevated state.

As mentioned above, though, you very rarely want to do this. And you certainly don't want to do it just so you can write temporary files into %programfiles%. Use this method only when you need to perform administrative actions like service start/stop, etc. Write your temporary files into a better place, as indicated in other answers here.

Compare given date with today

Expanding on Josua's answer from w3schools:

//create objects for the dates to compare
//now convert the $diff object to type integer
$intDiff = $diff->format("%R%a");
$intDiff = intval($intDiff);
//now compare the two dates
if ($intDiff > 0)  {echo '$date1 is in the past';}
else {echo 'date1 is today or in the future';}

I hope this helps. My first post on stackoverflow!

how to get files from <input type='file' .../> (Indirect) with javascript

Based on Ray Nicholus's answer :

inputElement.onchange = function(event) {
   var fileList = inputElement.files;
   //TODO do something with fileList.  

using this will also work :

inputElement.onchange = function(event) {
   var fileList =;
   //TODO do something with fileList.  

How to convert all elements in an array to integer in JavaScript?

You need to loop through and parse/convert the elements in your array, like this:

var result_string = 'a,b,c,d|1,2,3,4',
    result = result_string.split("|"),
    alpha = result[0],
    count = result[1],
    count_array = count.split(",");
for(var i=0; i<count_array.length;i++) count_array[i] = +count_array[i];
//now count_array contains numbers

You can test it out here. If the +, is throwing, think of it as:

for(var i=0; i<count_array.length;i++) count_array[i] = parseInt(count_array[i], 10);

How to get HttpRequestMessage data

  System.IO.StreamReader reader = new System.IO.StreamReader(HttpContext.Current.Request.InputStream);
  reader.BaseStream.Position = 0;
  string requestFromPost = reader.ReadToEnd();

POI setting Cell Background to a Custom Color


Custom colors


HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet = wb.createSheet();
HSSFRow row = sheet.createRow((short) 0);
HSSFCell cell = row.createCell((short) 0);
cell.setCellValue("Default Palette");

//apply some colors from the standard palette,
// as in the previous examples.
//we'll use red text on a lime background

HSSFCellStyle style = wb.createCellStyle();

HSSFFont font = wb.createFont();


//save with the default palette
FileOutputStream out = new FileOutputStream("default_palette.xls");

//now, let's replace RED and LIME in the palette
// with a more attractive combination
// (lovingly borrowed from

cell.setCellValue("Modified Palette");

//creating a custom palette for the workbook
HSSFPalette palette = wb.getCustomPalette();

//replacing the standard red with red
        (byte) 153,  //RGB red (0-255)
        (byte) 0,    //RGB green
        (byte) 0     //RGB blue
//replacing lime with gold
palette.setColorAtIndex(HSSFColor.LIME.index, (byte) 255, (byte) 204, (byte) 102);

//save with the modified palette
// note that wherever we have previously used RED or LIME, the
// new colors magically appear
out = new FileOutputStream("modified_palette.xls");


XSSFWorkbook wb = new XSSFWorkbook();
XSSFSheet sheet = wb.createSheet();
XSSFRow row = sheet.createRow(0);
XSSFCell cell = row.createCell( 0);
cell.setCellValue("custom XSSF colors");

XSSFCellStyle style1 = wb.createCellStyle();
style1.setFillForegroundColor(new XSSFColor(new java.awt.Color(128, 0, 128)));

How can I iterate over an enum?

For MS compilers:

#define inc_enum(i) ((decltype(i)) ((int)i + 1))

enum enumtype { one, two, three, count};
for(enumtype i = one; i < count; i = inc_enum(i))

Note: this is a lot less code than the simple templatized custom iterator answer.

You can get this to work with GCC by using typeof instead of decltype, but I don't have that compiler handy at the moment to make sure it compiles.

npm can't find package.json

Thank you! I also tried many options for this. I am also using windows.This command helped and saved my time:

npm install -g npm@lts

Getting only hour/minute of datetime

Just use Hour and Minute properties

var date = DateTime.Now;

Or you can easily zero the seconds using

var zeroSecondDate = date.AddSeconds(-date.Second);

Validation error: "No validator could be found for type: java.lang.Integer"

As per the javadoc of NotEmpty, Integer is not a valid type for it to check. It's for Strings and collections. If you just want to make sure an Integer has some value, javax.validation.constraints.NotNull is all you need.

public @interface NotEmpty

Asserts that the annotated string, collection, map or array is not null or empty.

Are there any Open Source alternatives to Crystal Reports?

You can use jasper report.

iReport is a very effective tool to develop jasper reports.

It supports almost all the facilities provided by crystal report like formatting, grouping, creation of charts etc.

Refer the link for tutorial:

Node.js Port 3000 already in use but it actually isn't?

check for any process running on the same port by entering the command:

sudo ps -ef

You can find the process running on the respective node port, then kill the node by

kill -9 <node id>

If the problem still remains then just kill all the node

killall node

How to build and run Maven projects after importing into Eclipse IDE

1.Update project

Right Click on your project maven > update project

2.Build project

Right Click on your project again. run as > Maven build

If you have not created a “Run configuration” yet, it will open a new configuration with some auto filled values.

You can change the name. "Base directory" will be a auto filled value for you. Keep it as it is. Give maven command to ”Goals” fields.

i.e, “clean install” for building purpose

Click apply

Click run.

3.Run project on tomcat

Right Click on your project again. run as > Run-Configuration. It will open Run-Configuration window for you.

Right Click on “Maven Build” from the right side column and Select “New”. It will open a blank configuration for you.

Change the name as you want. For the base directory field you can choose values using 3 buttons(workspace,FileSystem,Variables). You can also copy and paste the auto generated value from previously created Run-configuration. Give the Goals as “tomcat:run”. Click apply. Click run.

If you want to get more clear idea with snapshots use the following link.

Build and Run Maven project in Eclipse

(I hope this answer will help someone come after the topic of the question)

How to do a HTTP HEAD request from the windows command line?

On Linux, I often use curl with the --head parameter. It is available for several operating systems, including Windows.

[edit] related to the answer below, is currently down as of February 23 2012. Check for updated info.

How can I know if Object is String type object?

Either use instanceof or method Class.isAssignableFrom(Class<?> cls).

How can I find out the total physical memory (RAM) of my linux box suitable to be parsed by a shell script?

In Linux Kernel, present pages are physical pages of RAM which kernel can see. Literally, present pages is total size of RAM in 4KB unit.

grep present /proc/zoneinfo | awk '{sum+=$2}END{print sum*4,"KB"}'

The 'MemTotal' form /proc/meminfo is the total size of memory managed by buddy system.And we can also compute it like this:

grep managed /proc/zoneinfo | awk '{sum+=$2}END{print sum*4,"KB"}'

How to write loop in a Makefile?

Dynamically assign variables in the loop

The promblem with the for number in 1 2 3 4 ; do \ ...-solution is, that no variables can be assigned within the loop. $(eval VAR=...) can only be used, if the content of the assignment is known at the beginning of the target execution. If the assignment depends on the loop-variable, VAR will be empty.

To circumvent this issue, one can use the target functionality to model a loop. The following example takes the n-th file from SRC / OBJ and processes them together. Using this construction you can even use $(eval ...) to process the loop variable, as demonstrated with VAR3.


SRC = f1.c f2.cpp f3.cpp
OBJ = f1.o f2.o f3.o

SRC2 = $(addsuffix _,$(SRC))
JOIN = $(join $(SRC2),$(OBJ))

PHONY: all
all : info loop

loop : $(JOIN)

$(JOIN) :
    @echo "TARGET: $@"
    $(eval VAR1=$(word 1,$(subst _, ,$@)))
    @echo "VAR1: "$(VAR1)
    $(eval VAR2=$(word 2,$(subst _, ,$@)))
    @echo "VAR2: "$(VAR2)
    $(eval VAR3=$(subst .o,.x,$(VAR2)))
    @echo "You can even substitute you loop variable VAR3: "$(VAR3)
    #g++ -o $(VAR2) $(VAR1)

PHONY: info
    @printf "\n"
    @echo "JOIN: "$(JOIN)
    @printf "\n"


$ make

JOIN: f1.c_f1.o f2.cpp_f2.o f3.cpp_f3.o

TARGET: f1.c_f1.o
VAR1: f1.c
VAR2: f1.o
You can even substitute you loop variable VAR3: f1.x
#g++ -o f1.o f1.c

TARGET: f2.cpp_f2.o
VAR1: f2.cpp
VAR2: f2.o
You can even substitute you loop variable VAR3: f2.x
#g++ -o f2.o f2.cpp

TARGET: f3.cpp_f3.o
VAR1: f3.cpp
VAR2: f3.o
You can even substitute you loop variable VAR3: f3.x
#g++ -o f3.o f3.cpp

Running stages in parallel with Jenkins workflow / pipeline

You may not place the deprecated non-block-scoped stage (as in the original question) inside parallel.

As of JENKINS-26107, stage takes a block argument. You may put parallel inside stage or stage inside parallel or stage inside stage etc. However visualizations of the build are not guaranteed to support all nestings; in particular

  • The built-in Pipeline Steps (a “tree table” listing every step run by the build) shows arbitrary stage nesting.
  • The Pipeline Stage View plugin will currently only display a linear list of stages, in the order they started, regardless of nesting structure.
  • Blue Ocean will display top-level stages, plus parallel branches inside a top-level stage, but currently no more.

JENKINS-27394, if implemented, would display arbitrarily nested stages.

Redirecting to a new page after successful login

You could also provide a link to the page after login and have it auto redirect using javascript after 10 seconds.

Test if string begins with a string?

The best methods are already given but why not look at a couple of other methods for fun? Warning: these are more expensive methods but do serve in other circumstances.

The expensive regex method and the css attribute selector with starts with ^ operator

Option Explicit

Public Sub test()

    Debug.Print StartWithSubString("ab", "abc,d")

End Sub


Public Function StartWithSubString(ByVal substring As String, ByVal testString As String) As Boolean
    'required reference Microsoft VBScript Regular Expressions
    Dim re As VBScript_RegExp_55.RegExp
    Set re = New VBScript_RegExp_55.RegExp

    re.Pattern = "^" & substring

    StartWithSubString = re.test(testString)

End Function

Css attribute selector with starts with operator

Public Function StartWithSubString(ByVal substring As String, ByVal testString As String) As Boolean
    'required reference Microsoft HTML Object Library
    Dim html As MSHTML.HTMLDocument
    Set html = New MSHTML.HTMLDocument

    html.body.innerHTML = "<div test=""" & testString & """></div>"

    StartWithSubString = html.querySelectorAll("[test^=" & substring & "]").Length > 0

End Function

How to find all links / pages on a website

If you have the developer console (JavaScript) in your browser, you can type this code in:

urls = document.querySelectorAll('a'); for (url in urls) console.log(urls[url].href);


n=$$('a');for(u in n)console.log(n[u].href)

Is it possible to use the SELECT INTO clause with UNION [ALL]?

Try something like this: Create the final object table, tmpFerdeen with the structure of the union.


INSERT INTO tmpFerdeen (
SELECT top(100)* 
FROM Customers
SELECT top(100)* 
FROM CustomerEurope
SELECT top(100)* 
FROM CustomerAsia
SELECT top(100)* 
FROM CustomerAmericas

Double precision - decimal places

IEEE 754 floating point is done in binary. There's no exact conversion from a given number of bits to a given number of decimal digits. 3 bits can hold values from 0 to 7, and 4 bits can hold values from 0 to 15. A value from 0 to 9 takes roughly 3.5 bits, but that's not exact either.

An IEEE 754 double precision number occupies 64 bits. Of this, 52 bits are dedicated to the significand (the rest is a sign bit and exponent). Since the significand is (usually) normalized, there's an implied 53rd bit.

Now, given 53 bits and roughly 3.5 bits per digit, simple division gives us 15.1429 digits of precision. But remember, that 3.5 bits per decimal digit is only an approximation, not a perfectly accurate answer.

Many (most?) debuggers actually look at the contents of the entire register. On an x86, that's actually an 80-bit number. The x86 floating point unit will normally be adjusted to carry out calculations to 64-bit precision -- but internally, it actually uses a couple of "guard bits", which basically means internally it does the calculation with a few extra bits of precision so it can round the last one correctly. When the debugger looks at the whole register, it'll usually find at least one extra digit that's reasonably accurate -- though since that digit won't have any guard bits, it may not be rounded correctly.

How to prevent a jQuery Ajax request from caching in Internet Explorer?

Cache-Control: no-cache, no-store

These two header values can be combined to get the required effect on both IE and Firefox

Mocha / Chai not catching thrown errors

One other possible implementation, more cumbersome than the .bind() solution, but one that helps to make the point that expect() requires a function that provides a this context to the covered function, you can use a call(), e.g.,

expect(function() {, 'z');}).to.throw('...');

How do I change the default index page in Apache?

I recommend using .htaccess. You only need to add:

DirectoryIndex home.php

or whatever page name you want to have for it.

EDIT: basic htaccess tutorial.

1) Create .htaccess file in the directory where you want to change the index file.

  • no extension
  • . in front, to ensure it is a "hidden" file

Enter the line above in there. There will likely be many, many other things you will add to this (AddTypes for webfonts / media files, caching for headers, gzip declaration for compression, etc.), but that one line declares your new "home" page.

2) Set server to allow reading of .htaccess files (may only be needed on your localhost, if your hosting servce defaults to allow it as most do)

Assuming you have access, go to your server's enabled site location. I run a Debian server for development, and the default site setup is at /etc/apache2/sites-available/default for Debian / Ubuntu. Not sure what server you run, but just search for "sites-available" and go into the "default" document. In there you will see an entry for Directory. Modify it to look like this:

<Directory /var/www/>
    Options Indexes FollowSymLinks MultiViews
    AllowOverride None
    Order allow,deny
    allow from all

Then restart your apache server. Again, not sure about your server, but the command on Debian / Ubuntu is:

sudo service apache2 restart

Technically you only need to reload, but I restart just because I feel safer with a full refresh like that.

Once that is done, your site should be reading from your .htaccess file, and you should have a new default home page! A side note, if you have a sub-directory that runs a site (like an admin section or something) and you want to have a different "home page" for that directory, you can just plop another .htaccess file in that sub-site's root and it will overwrite the declaration in the parent.

How can bcrypt have built-in salts?

This is bcrypt:

Generate a random salt. A "cost" factor has been pre-configured. Collect a password.

Derive an encryption key from the password using the salt and cost factor. Use it to encrypt a well-known string. Store the cost, salt, and cipher text. Because these three elements have a known length, it's easy to concatenate them and store them in a single field, yet be able to split them apart later.

When someone tries to authenticate, retrieve the stored cost and salt. Derive a key from the input password, cost and salt. Encrypt the same well-known string. If the generated cipher text matches the stored cipher text, the password is a match.

Bcrypt operates in a very similar manner to more traditional schemes based on algorithms like PBKDF2. The main difference is its use of a derived key to encrypt known plain text; other schemes (reasonably) assume the key derivation function is irreversible, and store the derived key directly.

Stored in the database, a bcrypt "hash" might look something like this:


This is actually three fields, delimited by "$":

  • 2a identifies the bcrypt algorithm version that was used.
  • 10 is the cost factor; 210 iterations of the key derivation function are used (which is not enough, by the way. I'd recommend a cost of 12 or more.)
  • vI8aWBnW3fID.ZQ4/zo1G.q1lRps.9cGLcZEiGDMVr5yUP1KUOYTa is the salt and the cipher text, concatenated and encoded in a modified Base-64. The first 22 characters decode to a 16-byte value for the salt. The remaining characters are cipher text to be compared for authentication.

This example is taken from the documentation for Coda Hale's ruby implementation.

Reading a huge .csv file

For someone who lands to this question. Using pandas with ‘chunksize’ and ‘usecols’ helped me to read a huge zip file faster than the other proposed options.

import pandas as pd

sample_cols_to_keep =['col_1', 'col_2', 'col_3', 'col_4','col_5']

# First setup dataframe iterator, ‘usecols’ parameter filters the columns, and 'chunksize' sets the number of rows per chunk in the csv. (you can change these parameters as you wish)
df_iter = pd.read_csv('../data/huge_csv_file.csv.gz', compression='gzip', chunksize=20000, usecols=sample_cols_to_keep) 

# this list will store the filtered dataframes for later concatenation 
df_lst = [] 

# Iterate over the file based on the criteria and append to the list
for df_ in df_iter: 
        tmp_df = (df_.rename(columns={col: col.lower() for col in df_.columns}) # filter eg. rows where 'col_1' value grater than one
                                  .pipe(lambda x:  x[x.col_1 > 0] ))
        df_lst += [tmp_df.copy()] 

# And finally combine filtered df_lst into the final lareger output say 'df_final' dataframe 
df_final = pd.concat(df_lst)

Convert DateTime to String PHP

echo date_format($date,"Y/m/d H:i:s");

What is the difference between mocking and spying when using Mockito?

The answer is in the documentation:

Real partial mocks (Since 1.8.0)

Finally, after many internal debates & discussions on the mailing list, partial mock support was added to Mockito. Previously we considered partial mocks as code smells. However, we found a legitimate use case for partial mocks.

Before release 1.8 spy() was not producing real partial mocks and it was confusing for some users. Read more about spying: here or in javadoc for spy(Object) method.

callRealMethod() was introduced after spy(), but spy() was left there of course, to ensure backward compatibility.

Otherwise, you're right: all the methods of a spy are real unless stubbed. All the methods of a mock are stubbed unless callRealMethod() is called. In general, I would prefer using callRealMethod(), because it doesn't force me to use the doXxx().when() idiom instead of the traditional when().thenXxx()

Calculating number of full months between two dates in SQL

The dateadd function can be used to offset to the beginning of the month. If the endDate has a day part less than startDate, it will get pushed to the previous month, thus datediff will give the correct number of months.

DATEDIFF(MONTH, DATEADD(DAY,-DAY(startDate)+1,startDate),DATEADD(DAY,-DAY(startDate)+1,endDate))

Set attribute without value

Perhaps try:

var body = document.getElementsByTagName('body')[0];

How to convert an array to object in PHP?

Little complicated but easy to extend technique:

Suppose you have an array

$a = [
     'name' => 'ankit',
     'age' => '33',
     'dob' => '1984-04-12'

Suppose you have have a Person class which may have more or less attributes from this array. for example

class Person 
    private $name;
    private $dob;
    private $age;
    private $company;
    private $city;

If you still wanna change your array to the person object. You can use ArrayIterator Class.

$arrayIterator = new \ArrayIterator($a); // Pass your array in the argument.

Now you have iterator object.

Create a class extending FilterIterator Class; where you have to define the abstract method accept. Follow the example

class PersonIterator extends \FilterIterator
    public function accept()
        return property_exists('Person', parent::current());

The above impelmentation will bind the property only if it exists in the class.

Add one more method in the class PersonIterator

public function getObject(Person $object)
        foreach ($this as $key => $value)
            $object->{'set' . underscoreToCamelCase($key)}($value);
        return $object;

Make sure you have mutators defined in your class. Now you are ready to call these function where you want to create object.

$arrayiterator = new \ArrayIterator($a);
$personIterator = new \PersonIterator($arrayiterator);

$personIterator->getObject(); // this will return your Person Object. 

How to access the correct `this` inside a callback?

this in JS:

The value of this in JS is 100% determined by how a function is called, and not how it is defined. We can relatively easily find the value of this by the 'left of the dot rule':

  1. When the function is created using the function keyword the value of this is the object left of the dot of the function which is called
  2. If there is no object left of the dot then the value of this inside a function is often the global object (global in node, window in browser). I wouldn't recommend using the this keyword here because it is less explicit than using something like window!
  3. There exist certain constructs like arrow functions and functions created using the Function.prototype.bind() a function that can fix the value of this. These are exceptions of the rule but are really helpful to fix the value of this.

Example in nodeJS = 'module data';
// This outside a function in node refers to module.exports object

const obj1 = {
    data: "obj1 data",
    met1: function () {
    met2: () => {

const obj2 = {
    data: "obj2 data",
    test1: function () {
    test2: function () {
    test3: obj1.met1,
    test4: obj1.met2,



enter image description here

Let me walk you through the outputs 1 by 1 (ignoring the first log starting from the second):

  1. this is obj2 because of the left of the dot rule, we can see how test1 is called obj2.test1();. obj2 is left of the dot and thus the this value.
  2. Even though obj2 is left of the dot, test2 is bound to obj1 via the bind() method. So the this value is obj1.
  3. obj2 is left of the dot from the function which is called: obj2.test3(). Therefore obj2 will be the value of this.
  4. In this case: obj2.test4() obj2 is left of the dot. However, arrow functions don't have their own this binding. Therefore it will bind to the this value of the outer scope which is the module.exports an object which was logged in the beginning.
  5. We can also specify the value of this by using the call function. Here we can pass in the desired this value as an argument, which is obj2 in this case.

how to read value from string.xml in android?

By the way, it is also possible to create string arrays in the strings.xml like so:

<string-array name="tabs_names"> 
    <item>My Tab 1</item> 
    <item>My Tab 2</item>

And then from your Activity you can get the reference like so:

String[] tab_names = getResources().getStringArray(R.array.tab_names);
String tabname1=tab_names[0];//"My Tab 1"

How to fix: Error device not found with ADB.exe

Another issue here is that you likely need to turn off "connect as media device" to be able to connect with adb.

Stop absolutely positioned div from overlapping text

Put a z-indez of -1 on your absolute (or relative) positioned element.

This will pull it out of the stacking context. (I think.) Read more wonderful things about "stacking contexts" here:

How to calculate mean, median, mode and range from a set of numbers

    public static Set<Double> getMode(double[] data) {
            if (data.length == 0) {
                return new TreeSet<>();
            TreeMap<Double, Integer> map = new TreeMap<>(); //Map Keys are array values and Map Values are how many times each key appears in the array
            for (int index = 0; index != data.length; ++index) {
                double value = data[index];
                if (!map.containsKey(value)) {
                    map.put(value, 1); //first time, put one
                else {
                    map.put(value, map.get(value) + 1); //seen it again increment count
            Set<Double> modes = new TreeSet<>(); //result set of modes, min to max sorted
            int maxCount = 1;
            Iterator<Integer> modeApperance = map.values().iterator();
            while (modeApperance.hasNext()) {
                maxCount = Math.max(maxCount,; //go through all the value counts
            for (double key : map.keySet()) {
                if (map.get(key) == maxCount) { //if this key's value is max
                    modes.add(key); //get it
            return modes;

        //std dev function for good measure
        public static double getStandardDeviation(double[] data) {
            final double mean = getMean(data);
            double sum = 0;
            for (int index = 0; index != data.length; ++index) {
                sum += Math.pow(Math.abs(mean - data[index]), 2);
            return Math.sqrt(sum / data.length);

        public static double getMean(double[] data) {
        if (data.length == 0) {
            return 0;
        double sum = 0.0;
        for (int index = 0; index != data.length; ++index) {
            sum += data[index];
        return sum / data.length;

//by creating a copy array and sorting it, this function can take any data.
    public static double getMedian(double[] data) {
        double[] copy = Arrays.copyOf(data, data.length);
        return (copy.length % 2 != 0) ? copy[copy.length / 2] : (copy[copy.length / 2] + copy[(copy.length / 2) - 1]) / 2;

Get integer value of the current year in Java

In Java version 8+ can (advised to) use java.time library. ISO 8601 sets standard way to write dates: YYYY-MM-DD and java.time.Instant uses it, so (for UTC):

import java.time.Instant;
int myYear = Integer.parseInt(,4));

P.S. just in case (and shorted for getting String, not int), using Calendar looks better and can be made zone-aware.

any tool for java object to object mapping?

Another one is Orika -

Orika is a Java Bean mapping framework that recursively copies (among other capabilities) data from one object to another. It can be very useful when developing multi-layered applications.

Orika focuses on automating as much as possible, while providing customization through configuration and extension where needed.

Orika enables the developer to :

  • Map complex and deeply structured objects
  • "Flatten" or "Expand" objects by mapping nested properties to top-level properties, and vice versa
  • Create mappers on-the-fly, and apply customizations to control some or all of the mapping
  • Create converters for complete control over the mapping of a specific set of objects anywhere in the object graph--by type, or even by specific property name
  • Handle proxies or enhanced objects (like those of Hibernate, or the various mock frameworks)
  • Apply bi-directional mapping with one configuration
  • Map to instances of an appropriate concrete class for a target abstract class or interface
  • Handle reverse mappings
  • Handle complex conventions beyond JavaBean specs.

Orika uses byte code generation to create fast mappers with minimal overhead.

Run bash command on jenkins pipeline

The Groovy script you provided is formatting the first line as a blank line in the resultant script. The shebang, telling the script to run with /bin/bash instead of /bin/sh, needs to be on the first line of the file or it will be ignored.

So instead, you should format your Groovy like this:

stage('Setting the variables values') {
    steps {
         sh '''#!/bin/bash
                 echo "hello world" 

And it will execute with /bin/bash.

Changing datagridview cell color based on condition

Kyle's and Simon's answers are gross waste of CPU resources. CellFormatting and CellPainting events occur far too many times and should not be used for applying styles. Here are two better ways of doing it:

If your DataGridView or at least the columns that decide cell style are read-only, you should change DefaultCellStyle of rows in RowsAdded event. This event occurs only once when a new row is added. The condition should be evaluated at that time and DefaultCellStyle of the row should be set therein. Note that this event occurs for DataBound situations too.

If your DataGridView or those columns allow editing, you should use CellEndEdit or CommitEdit events to change DefaultCellStyle.

ALTER TABLE add constraint

Omit the parenthesis:

    ADD CONSTRAINT userProperties
    FOREIGN KEY(properties)
    REFERENCES Properties(ID)

Ping a site in Python?

Here's a short snippet using subprocess. The check_call method either returns 0 for success, or raises an exception. This way, I don't have to parse the output of ping. I'm using shlex to split the command line arguments.

  import subprocess
  import shlex

  command_line = "ping -c 1"
  args = shlex.split(command_line)
      print "Website is there."
  except subprocess.CalledProcessError:
      print "Couldn't get a ping."

length and length() in Java

Whenever an array is created, its size is specified. So length can be considered as a construction attribute. For String, it essentially a char array. Length is a property of the char array. There is no need to put length as a field, because not everything needs this field.

Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM

The trick is to represent the algorithms state, which is an integer multi-set, as a compressed stream of "increment counter"="+" and "output counter"="!" characters. For example, the set {0,3,3,4} would be represented as "!+++!!+!", followed by any number of "+" characters. To modify the multi-set you stream out the characters, keeping only a constant amount decompressed at a time, and make changes inplace before streaming them back in compressed form.


We know there are exactly 10^6 numbers in the final set, so there are at most 10^6 "!" characters. We also know that our range has size 10^8, meaning there are at most 10^8 "+" characters. The number of ways we can arrange 10^6 "!"s amongst 10^8 "+"s is (10^8 + 10^6) choose 10^6, and so specifying some particular arrangement takes ~0.965 MiB` of data. That'll be a tight fit.

We can treat each character as independent without exceeding our quota. There are exactly 100 times more "+" characters than "!" characters, which simplifies to 100:1 odds of each character being a "+" if we forget that they are dependent. Odds of 100:101 corresponds to ~0.08 bits per character, for an almost identical total of ~0.965 MiB (ignoring the dependency has a cost of only ~12 bits in this case!).

The simplest technique for storing independent characters with known prior probability is Huffman coding. Note that we need an impractically large tree (A huffman tree for blocks of 10 characters has an average cost per block of about 2.4 bits, for a total of ~2.9 Mib. A huffman tree for blocks of 20 characters has an average cost per block of about 3 bits, which is a total of ~1.8 MiB. We're probably going to need a block of size on the order of a hundred, implying more nodes in our tree than all the computer equipment that has ever existed can store.). However, ROM is technically "free" according to the problem and practical solutions that take advantage of the regularity in the tree will look essentially the same.


  • Have a sufficiently large huffman tree (or similar block-by-block compression data) stored in ROM
  • Start with a compressed string of 10^8 "+" characters.
  • To insert the number N, stream out the compressed string until N "+" characters have gone past then insert a "!". Stream the recompressed string back over the previous one as you go, keeping a constant amount of buffered blocks to avoid over/under-runs.
  • Repeat one million times: [input, stream decompress>insert>compress], then decompress to output

how to display employee names starting with a and then b in sql

Here what I understood from the question is starting with "a " and then "b" ex:

  • abhay
  • abhishek
  • abhinav

So there should be two conditions and both should be true means you cant use "OR" operator Ordered by is not not compulsory but its good if you use.

Select e_name from emp 
where  e_name like 'a%' AND e_name like '_b%'
Ordered by e_name

Getting attribute using XPath

You can try below xPath pattern,

  XPathExpression expr = xPath.compile("/bookstore/book/title[@lang='eng']")

How to detect the OS from a Bash script?

Detecting operating system and CPU type is not so easy to do portably. I have a sh script of about 100 lines that works across a very wide variety of Unix platforms: any system I have used since 1988.

The key elements are

  • uname -p is processor type but is usually unknown on modern Unix platforms.

  • uname -m will give the "machine hardware name" on some Unix systems.

  • /bin/arch, if it exists, will usually give the type of processor.

  • uname with no arguments will name the operating system.

Eventually you will have to think about the distinctions between platforms and how fine you want to make them. For example, just to keep things simple, I treat i386 through i686 , any "Pentium*" and any "AMD*Athlon*" all as x86.

My ~/.profile runs an a script at startup which sets one variable to a string indicating the combination of CPU and operating system. I have platform-specific bin, man, lib, and include directories that get set up based on that. Then I set a boatload of environment variables. So for example, a shell script to reformat mail can call, e.g., $LIB/mailfmt which is a platform-specific executable binary.

If you want to cut corners, uname -m and plain uname will tell you what you want to know on many platforms. Add other stuff when you need it. (And use case, not nested if!)


Have a look at <openssl/pem.h>. It gives possible BEGIN markers.

Copying the content from the above link for quick reference:

#define PEM_STRING_X509_CRL "X509 CRL"
#define PEM_STRING_PKCS7    "PKCS7"
#define PEM_STRING_CMS      "CMS"

How to test if list element exists?

Here is a performance comparison of the proposed methods in other answers.

> foo <- sapply(letters, function(x){runif(5)}, simplify = FALSE)
> microbenchmark::microbenchmark('k' %in% names(foo), 
                                 exists('k', where = foo))
Unit: nanoseconds
                     expr  min   lq    mean median   uq   max neval cld
      "k" %in% names(foo)  467  933 1064.31    934  934 10730   100  a 
      is.null(foo[["k"]])    0    0  168.50      1  467  3266   100  a 
 exists("k", where = foo) 6532 6998 7940.78   7232 7465 56917   100   b

If you are planing to use the list as a fast dictionary accessed many times, then the is.null approach might be the only viable option. I assume it is O(1), while the %in% approach is O(n)?

Could not autowire field:RestTemplate in Spring boot application

Please make sure two things:

1- Use @Bean annotation with the method.

public RestTemplate restTemplate(RestTemplateBuilder builder){

2- Scope of this method should be public not private.

Complete Example -

public class MakeHttpsCallImpl implements MakeHttpsCall {

private RestTemplate restTemplate;

public String makeHttpsCall() {
    return restTemplate.getForObject("https://localhost:8085/onewayssl/v1/test",String.class);

public RestTemplate restTemplate(RestTemplateBuilder builder){

Change the Arrow buttons in Slick slider

its very easy. Use the bellow code, Its works for me. Here I have used fontawesome icon but you can use anything as image or any other Icon's code.

            arrows: true,
            prevArrow:"<button type='button' class='slick-prev pull-left'><i class='fa fa-angle-left' aria-hidden='true'></i></button>",
            nextArrow:"<button type='button' class='slick-next pull-right'><i class='fa fa-angle-right' aria-hidden='true'></i></button>"

Quick easy way to migrate SQLite3 to MySQL?

Everyone seems to starts off with a few greps and perl expressions and you sorta kinda get something that works for your particular dataset but you have no idea if it's imported the data correctly or not. I'm seriously surprised nobody's built a solid library that can convert between the two.

Here a list of ALL the differences in SQL syntax that I know about between the two file formats: The lines starting with:

  • sqlite_sequence

are not used in MySQL

  • SQLite uses CREATE TABLE/INSERT INTO "table_name" and MySQL uses CREATE TABLE/INSERT INTO table_name
  • MySQL doesn't use quotes inside the schema definition
  • MySQL uses single quotes for strings inside the INSERT INTO clauses
  • SQLite and MySQL have different ways of escaping strings inside INSERT INTO clauses
  • SQLite uses 't' and 'f' for booleans, MySQL uses 1 and 0 (a simple regex for this can fail when you have a string like: 'I do, you don't' inside your INSERT INTO)

Here is a very basic hacked up perl script which works for my dataset and checks for many more of these conditions that other perl scripts I found on the web. Nu guarantees that it will work for your data but feel free to modify and post back here.

#! /usr/bin/perl

while ($line = <>){
    if (($line !~  /BEGIN TRANSACTION/) && ($line !~ /COMMIT/) && ($line !~ /sqlite_sequence/) && ($line !~ /CREATE UNIQUE INDEX/)){
        if ($line =~ /CREATE TABLE \"([a-z_]*)\"(.*)/i){
            $name = $1;
            $sub = $2;
            $sub =~ s/\"//g;
            $line = "DROP TABLE IF EXISTS $name;\nCREATE TABLE IF NOT EXISTS $name$sub\n";
        elsif ($line =~ /INSERT INTO \"([a-z_]*)\"(.*)/i){
            $line = "INSERT INTO $1$2\n";
            $line =~ s/\"/\\\"/g;
            $line =~ s/\"/\'/g;
            $line =~ s/\'\'/\\\'/g;
        $line =~ s/([^\\'])\'t\'(.)/$1THIS_IS_TRUE$2/g;
        $line =~ s/THIS_IS_TRUE/1/g;
        $line =~ s/([^\\'])\'f\'(.)/$1THIS_IS_FALSE$2/g;
        $line =~ s/THIS_IS_FALSE/0/g;
        print $line;

Setting up enviromental variables in Windows 10 to use java and javac

  • Right click Computer
  • Click the properties
  • On the left pane select Advanced System Settings
  • Select Environment Variables
  • Under the System Variables, Select PATH and click edit,
    and then click new and add path as C:\Program
    (depending on your installation path)
    and finally click ok
  • Next restart your command prompt and open it and try javac

Using XAMPP, how do I swap out PHP 5.3 for PHP 5.2?

For OSX it's even easier. Your machine should come with a version of Apache already installed. All you need to do is locate the php lib for that version (which is likely 5.2.x) and swap it out.

This is the command you'd run from terminal*

cp /usr/libexec/apache2/ /Applications/XAMPP/xamppfiles/modules/

I tested this on 10.5 (Leopard), so ymmv. * all the caveats about this might break your system, make a backup, blah blah blah.

Edit: On 10.4 (Tiger), Xampp 1.73, using the found at Mamp, this does not work at all.

WSDL vs REST Pros and Cons

You can easily transition your WSDL-spewing WCF web components to other uses just by changing your configuration settings. You can go across HTTP and then also named pipes, tcp, custom protocols, etc without having to change your code. I believe WCF components may also be easier to set up for stuff like security, two-way calling, transactions, concurrency, etc.

REST pretty much limits you to HTTP (which is fine in many cases).

Does Ruby have a string.startswith("abc") built in method?

It's called String#start_with?, not String#startswith: In Ruby, the names of boolean-ish methods end with ? and the words in method names are separated with an _. Not sure where the s went, personally, I'd prefer String#starts_with? over the actual String#start_with?

How can I solve ORA-00911: invalid character error?

Remove the semicolon (;), backtick (``) etc. from inside a query

How to push elements in JSON from javascript array

If you want to stick with the way you're populating the values array, you can then assign this array like so:

BODY.values = values;

after the loop.

It should look like this:

var BODY = {
    "recipients": {
      "values": [
   "subject": title,
   "body": message

var values = [];
for (var ln = 0; ln < names.length; ln++) {
var item1 = {
    "person": {
            "_path": "/people/"+names[ln],
BODY.values = values;

JSON.stringify() will be useful once you pass it as parameter for an AJAX call. Remember: the values array in your BODY object is different from the var values = []. You must assign that outer values[] to BODY.values. This is one of the good things about OOP.

"The certificate chain was issued by an authority that is not trusted" when connecting DB in VM Role from Azure website

If you're seeing this error message when attempting to connect using SSMS, add TrustServerCertificate=True to the Additional Connection Parameters.

Get the index of the object inside an array, matching a condition

You can use the Array.prototype.some() in the following way (as mentioned in the other answers):

function findIndexInData(data, property, value) {
    var result = -1;
    data.some(function (item, i) {
        if (item[property] === value) {
            result = i;
            return true;
    return result;
var data = [{prop1:"abc",prop2:"qwe"},{prop1:"bnmb",prop2:"yutu"},{prop1:"zxvz",prop2:"qwrq"}]

alert(findIndexInData(data, 'prop2', "yutu")); // shows index of 1

How to restart ADB manually from Android Studio

I do not find a perfect way in Android Studio, get the process id and kill it from terminal:

ps -e | grep adb
kill -9 pid_adb

How to print / echo environment variables?

To bring the existing answers together with an important clarification:

As stated, the problem with NAME=sam echo "$NAME" is that $NAME gets expanded by the current shell before assignment NAME=sam takes effect.

Solutions that preserve the original semantics (of the (ineffective) solution attempt NAME=sam echo "$NAME"):

Use either eval[1] (as in the question itself), or printenv (as added by Aaron McDaid to heemayl's answer), or bash -c (from Ljm Dullaart's answer), in descending order of efficiency:

NAME=sam eval 'echo "$NAME"'  # use `eval` only if you fully control the command string
NAME=sam printenv NAME
NAME=sam bash -c 'echo "$NAME"'

printenv is not a POSIX utility, but it is available on both Linux and macOS/BSD.

What this style of invocation (<var>=<name> cmd ...) does is to define NAME:

  • as an environment variable
  • that is only defined for the command being invoked.

In other words: NAME only exists for the command being invoked, and has no effect on the current shell (if no variable named NAME existed before, there will be none after; a preexisting NAME variable remains unchanged).

POSIX defines the rules for this kind of invocation in its Command Search and Execution chapter.

The following solutions work very differently (from heemayl's answer):

NAME=sam; echo "$NAME"
NAME=sam && echo "$NAME"

While they produce the same output, they instead define:

  • a shell variable NAME (only) rather than an environment variable
    • if echo were a command that relied on environment variable NAME, it wouldn't be defined (or potentially defined differently from earlier).
  • that lives on after the command.

Note that every environment variable is also exposed as a shell variable, but the inverse is not true: shell variables are only visible to the current shell and its subshells, but not to child processes, such as external utilities and (non-sourced) scripts (unless they're marked as environment variables with export or declare -x).

[1] Technically, bash is in violation of POSIX here (as is zsh): Since eval is a special shell built-in, the preceding NAME=sam assignment should cause the the variable $NAME to remain in scope after the command finishes, but that's not what happens.
However, when you run bash in POSIX compatibility mode, it is compliant.
dash and ksh are always compliant.
The exact rules are complicated, and some aspects are left up to the implementations to decide; again, see Command Search and Execution.
Also, the usual disclaimer applies: Use eval only on input you fully control or implicitly trust.

At runtime, find all classes in a Java application that extend a base class

I solved this problem pretty elegantly using Package Level Annotations and then making that annotation have as an argument a list of classes.

Find Java classes implementing an interface

Implementations just have to create a and put the magic annotation in with the list of classes they want to support.

How to delete from multiple tables in MySQL?

The syntax looks right to me ... try to change it to use INNER JOIN ...

Have a look at this.

How to convert an Array to a Set in Java

With Guava you can do:

T[] array = ...
Set<T> set = Sets.newHashSet(array);

How to List All Redis Databases?

Or you can just run the following command and you will see all databases of the Redis instance without firing up redis-cli:

$ redis-cli INFO | grep ^db

using where and inner join in mysql

You can use as many joins as you want, however, the more you use the more it will impact performance