Programs & Examples On #Bitstream

FFMPEG mp4 from http live streaming m3u8 file?

Your command is completely incorrect. The output format is not rawvideo and you don't need the bitstream filter h264_mp4toannexb which is used when you want to convert the h264 contained in an mp4 to the Annex B format used by MPEG-TS for example. What you want to use instead is the aac_adtstoasc for the AAC streams.

ffmpeg -i http://.../playlist.m3u8 -c copy -bsf:a aac_adtstoasc output.mp4

Multiple condition in single IF statement

Yes that is valid syntax but it may well not do what you want.

Execution will continue after your RAISERROR except if you add a RETURN. So you will need to add a block with BEGIN ... END to hold the two statements.

Also I'm not sure why you plumped for severity 15. That usually indicates a syntax error.

Finally I'd simplify the conditions using IN

CREATE PROCEDURE [dbo].[AddApplicationUser] (@TenantId BIGINT,
                                            @UserType TINYINT,
                                            @UserName NVARCHAR(100),
                                            @Password NVARCHAR(100))
      IF ( @TenantId IS NULL
           AND @UserType IN ( 0, 1 ) )
            RAISERROR('The value for @TenantID should not be null',15,1);


Opening port 80 EC2 Amazon web services

Some quick tips:

  1. Disable the inbuilt firewall on your Windows instances.
  2. Use the IP address rather than the DNS entry.
  3. Create a security group for tcp ports 1 to 65000 and for source It's obviously not to be used for production purposes, but it will help avoid the Security Groups as a source of problems.
  4. Check that you can actually ping your server. This may also necessitate some Security Group modification.

Run a vbscript from another vbscript

Just to complete, you could send 3 arguments like this:

objShell.Run "TestScript.vbs 42 ""an arg containing spaces"" foo" 

comparing elements of the same array in java

Try this or purpose will solve with lesser no of steps

for (int i = 0; i < a.length; i++) 
    for (int k = i+1; k < a.length; k++) 
        if (a[i] != a[k]) 
            System.out.println(a[i]+"not the same with"+a[k]+"\n");

Copy struct to struct in C

memcpy expects the first two arguments to be void*.

Try: memcpy( (void*)&RTCclk, (void*)&RTCclkBuffert, sizeof(RTCclk) );

P.S. although not necessary, convention dictates the brackets for the sizeof operator. You can get away with a lot in C that leaves code impossible to maintain, so following convention is the mark of a good (employable) C programmer.

sudo echo "something" >> /etc/privilegedFile doesn't work

You can also use sponge from the moreutils package and not need to redirect the output (i.e., no tee noise to hide):

echo 'Add this line' | sudo sponge -a privfile

Hyper-V: Create shared folder between host and guest with internal network

  • Open Hyper-V Manager
  • Create a new internal virtual switch (e.g. "Internal Network Connection")
  • Go to your Virtual Machine and create a new Network Adapter -> choose "Internal Network Connection" as virtual switch
  • Start the VM
  • Assign both your host as well as guest an IP address as well as a Subnet mask (IP4, e.g. (host) / (guest) and
  • Open cmd both on host and guest and check via "ping" if host and guest can reach each other (if this does not work disable/enable the network adapter via the network settings in the control panel, restart...)
  • If successfull create a folder in the VM (e.g. "VMShare"), right-click on it -> Properties -> Sharing -> Advanced Sharing -> checkmark "Share this folder" -> Permissions -> Allow "Full Control" -> Apply
  • Now you should be able to reach the folder via the host -> to do so: open Windows Explorer -> enter the path to the guest (\192.168.1.xx...) in the address line -> enter the credentials of the guest (Choose "Other User" - it can be necessary to change the domain therefore enter ".\"[username] and [password])

There is also an easy way for copying via the clipboard:

  • If you start your VM and go to "View" you can enable "Enhanced Session". If you do it is not possible to drag and drop but to copy and paste.

Enhanced Session

Android 8.0: java.lang.IllegalStateException: Not allowed to start service Intent

if you have integrated firebase messaging push notification then,

Add new/update firebase messaging dependencies for android O (Android 8.0), due to Background Execution Limits.

compile ''

upgrade google play services and google repositories if needed.


 compile ''

Get escaped URL parameter

There's a lot of buggy code here and regex solutions are very slow. I found a solution that works up to 20x faster than the regex counterpart and is elegantly simple:

    *   @param      string      parameter to return the value of.
    *   @return     string      value of chosen parameter, if found.
    function get_param(return_this)
        return_this = return_this.replace(/\?/ig, "").replace(/=/ig, ""); // Globally replace illegal chars.

        var url = window.location.href;                                   // Get the URL.
        var parameters = url.substring(url.indexOf("?") + 1).split("&");  // Split by "param=value".
        var params = [];                                                  // Array to store individual values.

        for(var i = 0; i < parameters.length; i++)
            if(parameters[i].search(return_this + "=") != -1)
                return parameters[i].substring(parameters[i].indexOf("=") + 1).split("+");

        return "Parameter not found";


Regex is not the be-all and end-all solution, for this type of problem simple string manipulation can work a huge amount more efficiently. Code source.

How can I get useful error messages in PHP?

I recommend Nette Tracy for better visualization of errors and exceptions in PHP:

Nette Tracy screenshot

Copy files to network computers on windows command line

Below command will work in command prompt:

copy c:\folder\file.ext \\dest-machine\destfolder /Z /Y

To Copy all files:

copy c:\folder\*.* \\dest-machine\destfolder /Z /Y

How to compile a Perl script to a Windows executable with Strawberry Perl?

  :: short answer :
  :: perl -MCPAN -e "install PAR::Packer" 
  pp -o <<DesiredExeName>>.exe <<MyFancyPerlScript>> 

  :: long answer - create the following cmd , adjust vars to your taste ...
  :: next_line_is_templatized
  :: v1.0.0
  :: disable the echo
  @echo off

  :: this is part of the name of the file - not used
  set _Action=run

  :: the name of the Product next_line_is_templatized
  set _ProductName=morphus

  :: the version of the current Product next_line_is_templatized
  set _ProductVersion=1.2.3

  :: could be dev , test , dev , prod next_line_is_templatized
  set _ProductType=dev

  :: who owns this Product / environment next_line_is_templatized
  set _ProductOwner=ysg

  :: identifies an instance of the tool ( new instance for this version could be created by simply changing the owner )   
  set _EnvironmentName=%_ProductName%.%_ProductVersion%.%_ProductType%.%_ProductOwner%

  :: go the run dir
  cd %~dp0

  :: do 4 times going up
  for /L %%i in (1,1,5) do pushd ..

  :: The BaseDir is 4 dirs up than the run dir
  set _ProductBaseDir=%CD%
  :: debug echo BEFORE _ProductBaseDir is %_ProductBaseDir%
  :: remove the trailing \

  IF %_ProductBaseDir:~-1%==\ SET _ProductBaseDir=%_ProductBaseDir:~0,-1%
  :: debug echo AFTER _ProductBaseDir is %_ProductBaseDir%
  :: debug pause

  :: The version directory of the Product 
  set _ProductVersionDir=%_ProductBaseDir%\%_ProductName%\%_EnvironmentName%

  :: the dir under which all the perl scripts are placed
  set _ProductVersionPerlDir=%_ProductVersionDir%\sfw\perl

  :: The Perl script performing all the tasks
  set _PerlScript=%_ProductVersionPerlDir%\

  :: where the log events are stored 
  set _RunLog=%_ProductVersionDir%\data\log\compile-%_ProductName%.cmd.log

  :: define a favorite editor 
  set _MyEditor=textpad

  ECHO Check the variables 
  set _
  :: debug PAUSE
  :: truncate the run log
  echo date is %date% time is %time% > %_RunLog%

  :: uncomment this to debug all the vars 
  :: debug set  >> %_RunLog%

  :: for each perl pm and or pl file to check syntax and with output to logs
  for /f %%i in ('dir %_ProductVersionPerlDir%\*.pl /s /b /a-d' ) do echo %%i >> %_RunLog%&perl -wc %%i | tee -a  %_RunLog% 2>&1

  :: for each perl pm and or pl file to check syntax and with output to logs
  for /f %%i in ('dir %_ProductVersionPerlDir%\*.pm /s /b /a-d' ) do echo %%i >> %_RunLog%&perl -wc %%i | tee -a  %_RunLog% 2>&1

  :: now open the run log
  cmd /c start /max %_MyEditor% %_RunLog%

  :: this is the call without debugging
  :: old 
  echo CFPoint1  OK The run cmd script %0 is executed >> %_RunLog%
  echo CFPoint2  OK  compile the exe file  STDOUT and STDERR  to a single _RunLog file >> %_RunLog%
  cd %_ProductVersionPerlDir%

  pp -o %_Action%_%_ProductName%.exe %_PerlScript% | tee -a %_RunLog% 2>&1 

  :: open the run log
  cmd /c start /max %_MyEditor% %_RunLog%

  :: uncomment this line to wait for 5 seconds
  :: ping localhost -n 5

  :: uncomment this line to see what is happening 
  :: PAUSE

  :: Purpose: 
  :: To compile every *.pl file into *.exe file under a folder 
  :: Requirements : 
  :: perl , pp , win gnu utils tee 
  :: perl -MCPAN -e "install PAR::Packer" 
  :: text editor supporting <<textEditor>> <<FileNameToOpen>> cmd call syntax
  :: VersionHistory
  :: 1.0.0 --- 2012-06-23 12:05:45 --- ysg --- Initial creation from run_morphus.cmd
  :: eof v1.0.0

Error:java: invalid source release: 8 in Intellij. What does it mean?

I checked all above said project version, module version, project bytecode version, target bytecode version settings in IntelliJ Idea, but all were the same as I scratched.

I face this error Error:java: invalid source release: 1.8 in IntelliJ Idea 2017.2.6 because I upgraded the dependency version Maven pom file, which(dependency) were supposed to build for JDK 1.8 application and I were building my application on and with maven compiler source and target JDK 1.7.

Hence I again downgrade the dependency version to earlier one in Maven pom, and the error gone after project Rebuild Module 'xyz_project'.

How to add System.Windows.Interactivity to project?

I have had the exact same problem with a solution, that System.Windows.Interactivity was required for one of the project in Visual Studio 2019, and I tried to install Blend for Visual Studio SDK for .NET from Visual Studio 2019 Individual components, but it did not exist in it.

The consequence of that, I was not able to build the project in my solution with repetitive of following similar error on different XAML parts of the project:

The tag 'Interaction.Behaviors' does not exist in XML namespace 'clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity'.

Image with all errors The above mentioned errors snapshot example

The solution, the way I solved it, is by installing Microsoft Expression Blend Software Development Kit (SDK) for .NET 4 from Microsoft.

Thanks to my colleague @felza, mentioned that System.Windows.Interactivity requires this sdk, that is suppose to be located in this folder:

C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.0

In my case it was not installed. I have had this folder C:\Program Files (x86)\Microsoft SDKs with out Expression\Blend\.NETFramework\v4.0 folder inside it.

After installing it, all errors disappeared.

How to display an IFRAME inside a jQuery UI dialog

The problems were:

  1. iframe content comes from another domain
  2. iframe dimensions need to be adjusted for each video

The solution based on omerkirk's answer involves:

  • Creating an iframe element
  • Creating a dialog with autoOpen: false, width: "auto", height: "auto"
  • Specifying iframe source, width and height before opening the dialog

Here is a rough outline of code:


<div class="thumb">
    <a href=""   data-title="Std 4:3 ratio video" data-width="512" data-height="384"><img src="" /></a></li>
    <a href="" data-title="HD 16:9 ratio video" data-width="512" data-height="288"><img src="" /></a></li>


$(function () {
    var iframe = $('<iframe frameborder="0" marginwidth="0" marginheight="0" allowfullscreen></iframe>');
    var dialog = $("<div></div>").append(iframe).appendTo("body").dialog({
        autoOpen: false,
        modal: true,
        resizable: false,
        width: "auto",
        height: "auto",
        close: function () {
            iframe.attr("src", "");
    $(".thumb a").on("click", function (e) {
        var src = $(this).attr("href");
        var title = $(this).attr("data-title");
        var width = $(this).attr("data-width");
        var height = $(this).attr("data-height");
            width: +width,
            height: +height,
            src: src
        dialog.dialog("option", "title", title).dialog("open");

Demo here and code here. And another example along similar lines

Pandas: ValueError: cannot convert float NaN to integer

Also, even at the lastest versions of pandas if the column is object type you would have to convert into float first, something like:


NB: You have to go through numpy float first and then to nullable Int32, for some reason.

The size of the int if it's 32 or 64 depends on your variable, be aware you may loose some precision if your numbers are to big for the format.

Node Version Manager install - nvm command not found

After trying multiple steps, not sure what was the problem in my case but running this helped:

touch ~/.bash_profile
curl -o- | bash

Verified by nvm --version

nvm -v output

How to catch an Exception from a thread

That's because exceptions are local to a thread, and your main thread doesn't actually see the run method. I suggest you read more about how threading works, but to quickly summarize: your call to start starts up a different thread, totally unrelated to your main thread. The call to join simply waits for it to be done. An exception that is thrown in a thread and never caught terminates it, which is why join returns on your main thread, but the exception itself is lost.

If you want to be aware of these uncaught exceptions you can try this:

Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
    public void uncaughtException(Thread t, Throwable e) {
        System.out.println("Caught " + e);

More information about uncaught exception handling can be found here.

json: cannot unmarshal object into Go value of type

Here's a fixed version of it:

The biggest fix that was needed is when Unmarshalling an array, that property needs to be an array/slice in the struct as well.

For example:

{ "things": ["a", "b", "c"] }

Would Unmarshal into a:

type Item struct {
    Things []string

And not into:

type Item struct {
    Things string

The other thing to watch out for when Unmarshaling is that the types line up exactly. It will fail when Unmarshalling a JSON string representation of a number into an int or float field -- "1" needs to Unmarshal into a string, not into an int like we saw with ShippingAdditionalCost int

How to install PIP on Python 3.6?

Since python 3.4 pip is included in the installation of python.

Math operations from string

Warning: this way is not a safe way, but is very easy to use. Use it wisely.

Use the eval function.

print eval('2 + 4')



You can even use variables or regular python code.

a = 5
print eval('a + 4')



You also can get return values:

d = eval('4 + 5')
print d



Or call functions:

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

a = 20
b = 10    
print eval('add(a, b)')
print eval('subtract(a, b)')



In case you want to write a parser, maybe instead you can built a python code generator if that is easier and use eval to run the code. With eval you can execute any Python evalution.

Why eval is unsafe?

Since you can put literally anything in the eval, e.g. if the input argument is:

os.system(‘rm -rf /’)

It will remove all files on your system (at least on Linux/Unix). So only use eval when you trust the input.

Activity, AppCompatActivity, FragmentActivity, and ActionBarActivity: When to Use Which?

Since the name is likely to change in future versions of Android (currently the latest is AppCompatActivity but it will probably change at some point), I believe a good thing to have is a class Activity that extends AppCompatActivity and then all your activities extend from that one. If tomorrow, they change the name to AppCompatActivity2 for instance you will have to change it just in one place.

No Main class found in NetBeans

If the advice to add the closing braces work, I suggest adding indentation to your code so every closing brace is on a spaced separately, i.e.:

public class LuisRp3 {

    public static void main(String[] args) throws FileNotFoundException  {

    // stuff


This just helps with readability.

If, on the other hand, you just forgot to copy the closing braces in your code, or the above suggestion doesn't work: open up the configuration and see if you can manually set the main class. I'm afraid I haven't used NetBeans much, so I can't help you with where that option is. My best guess is under "Run Configuration", or something like that.

Edit: See peeskillet's answer if adding closing braces doesn't work.

What is console.log?

An example - suppose you want to know which line of code you were able to run your program (before it broke!), simply type in

console.log("You made it to line 26. But then something went very, very wrong.")

Bootstrap 3 .col-xs-offset-* doesn't work?

Its not working because col-xs-offset-* is mentioned out of the media query. if you want to use it, you have to mention all the offset (eg: class="col-xs-offset-3 col-sm-offset-2 col-md-offset-1 col-lg-offset-0")

But this is not right, they should mention col-xs-offset-* in the media query

Node.js - SyntaxError: Unexpected token import

As mentioned in other answers Node JS currently doesn't support ES6 imports.

(As of now, read EDIT 2)

Enable ES6 imports in node js provides a solution to this issue. I have tried this and it worked for me.

Run the command:

    npm install babel-register babel-preset-env --save-dev

Now you need to create a new file (config.js) and add the following code to it.

        presets: [ 'env' ]
    // Import the rest of our application.
    module.exports = require('./your_server_file.js')

Now you can write import statements without getting any errors.

Hope this helps.


You need to run the new file which you created with above code. In my case it was config.js. So I have to run:

    node config.js


While experimenting, I found one easy solution to this issue.

Create .babelrc file in the root of your project.

Add following (and any other babel presets you need, can be added in this file):

        "presets": ["env"]

Install babel-preset-env using command npm install babel-preset-env --save, and then install babel-cli using command npm install babel-cli -g --save

Now, go to the folder where your server or index file exists and run using: babel-node fileName.js

Or you can run using npm start by adding following code to your package.json file:

    "scripts": {
        "start": "babel-node src/index.js"

How to get directory size in PHP

Code adjusted to access main directory and all sub folders within it. This would return the full directory size.

function get_dir_size($directory){
    $size = 0;
    $files= glob($directory.'/*');
    foreach($files as $path){
        is_file($path) && $size += filesize($path);

        if (is_dir($path))
            $size += get_dir_size($path);
    return $size;

How do I see the extensions loaded by PHP?

You asked where do you see loaded extensions in phpinfo() output.


They are listed towards the bottom as separate sections/tables and ONLY if they are loaded. Here is an example of extension Curl loaded.

enter image description here ...

... enter image description here

I installed it on Linux Debian with

sudo apt-get install php7.4-curl

Check orientation on Android phone

A fully way to specify the current orientation of the phone:

public String getRotation(Context context) {
    final int rotation = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay().getOrientation();
    switch (rotation) {
        case Surface.ROTATION_0:
            return "portrait";
        case Surface.ROTATION_90:
            return "landscape";
        case Surface.ROTATION_180:
            return "reverse portrait";
            return "reverse landscape";

How to Import 1GB .sql file to WAMP/phpmyadmin

A phpMyAdmin feature called UploadDir permits to upload your file via another mechanism, then importing it from the server's file system. See

How can I tell where mongoDB is storing data? (its not in the default /data/db!)

If you could somehow locate mongod.log and the do a grep over it

grep dbpath mongod.log

The value for dbpath is the data location for mongodb!! All the best :)

How do I load an HTML page in a <div> using JavaScript?

Use this simple code

<div w3-include-HTML="content.html"></div>

tkinter: how to use after method

I believe, the 500ms run in the background, while the rest of the code continues to execute and empties the list.

Then after 500ms nothing happens, as no function-call is implemented in the after-callup (same as frame.after(500, function=None))

How to set time to 24 hour format in Calendar

Replace this:

c1.set(Calendar.HOUR, d1.getHours());

with this:

c1.set(Calendar.HOUR_OF_DAY, d1.getHours());

Calendar.HOUR is strictly for 12 hours.

Average of multiple columns

If the data is stored as INT, you may want to try

Average = (R1 + R2 + R3 + R4 + R5) / 5.0

Check whether there is an Internet connection available on Flutter app

late answer, but use this package to to check. Package Name: data_connection_checker

in you pubspec.yuml file:

    data_connection_checker: ^0.3.4

create a file called connection.dart or any name you want. import the package:

import 'package:data_connection_checker/data_connection_checker.dart';

check if there is internet connection or not:

print(await DataConnectionChecker().hasConnection);

Could not find any resources appropriate for the specified culture or the neutral culture

Just another case. I copied a solution with two projects and renamed them partially in the Windows explorer (folder names, .sln and .csproj file names) and partially with a massive Find & Replace action in Visual Studio (namespaces etc.). Nevertheless the exception stated by the OP still occurred. I found out that the Assembly and Namespace names were still old.

Although the project and everything else was already named OfficeStyle the Assembly name and Default namespace were still named Linckus.

Old situation

After this correction everything worked fine again, compile and run time :)

New situation

What is the difference between public, protected, package-private and private in Java?

Easy rule. Start with declaring everything private. And then progress towards the public as the needs arise and design warrants it.

When exposing members ask yourself if you are exposing representation choices or abstraction choices. The first is something you want to avoid as it will introduce too many dependencies on the actual representation rather than on its observable behavior.

As a general rule I try to avoid overriding method implementations by subclassing; it's too easy to screw up the logic. Declare abstract protected methods if you intend for it to be overridden.

Also, use the @Override annotation when overriding to keep things from breaking when you refactor.

DateTime.Today.ToString("dd/mm/yyyy") returns invalid DateTime Value

Use MM for months. mm is for minutes.


You probably run this code at the begining an hour like (00:00, 05.00, 18.00) and mm gives minutes (00) to your datetime.

From Custom Date and Time Format Strings

"mm" --> The minute, from 00 through 59.

"MM" --> The month, from 01 through 12.

Here is a DEMO. (Which the month part of first line depends on which time do you run this code ;) )

Received fatal alert: handshake_failure through SSLHandshakeException

I found an HTTPS server which failed in this way if my Java client process was configured with


The connection failed with handshake_failure after the ServerHello had finished successfully but before the data stream started.

There was no clear error message that identified the problem, the error just looked like

main, READ: TLSv1.2 Alert, length = 2
main, RECV TLSv1.2 ALERT:  fatal, handshake_failure
%% Invalidated:  [Session-3, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384]
main, called closeSocket()
main, handling exception: Received fatal alert: handshake_failure

I isolated the issue by trying with and without the "-Djsse.enableSNIExtension=false" option

Open mvc view in new window from controller

Yeah you can do some tricky works to simulate what you want:

1) Call your controller from a view by ajax. 2) Return your View

3) Use something like the following in the success (or maybe error! error works for me!) section of your $.ajax request:

$("#imgPrint").click(function () {
            url: ...,
            type: 'POST', dataType: 'json',
            data: $("#frm").serialize(),
            success: function (data, textStatus, jqXHR) {
                //Here it is:
                //Gets the model state
                var isValid = '@Html.Raw(Json.Encode(ViewData.ModelState.IsValid))'; 
                // checks that model is valid                    
                if (isValid == 'true') {
                    //open new tab or window - according to configs of browser
                    var w =;
                    //put what controller gave in the new tab or win 
            error: function (jqXHR, textStatus, errorThrown) {
                // And here it is for error section. 
                //Pay attention to different order of 
                //parameters of success and error sections!
                var isValid = '@Html.Raw(Json.Encode(ViewData.ModelState.IsValid))';                    
                if (isValid == 'true') {
                    var w =;
            beforeSend: function () { $("#imgSpinner1").show(); },
            complete: function () { $("#imgSpinner1").hide(); }

Pandas df.to_csv("file.csv" encode="utf-8") still gives trash characters for minus sign

Your "bad" output is UTF-8 displayed as CP1252.

On Windows, many editors assume the default ANSI encoding (CP1252 on US Windows) instead of UTF-8 if there is no byte order mark (BOM) character at the start of the file. While a BOM is meaningless to the UTF-8 encoding, its UTF-8-encoded presence serves as a signature for some programs. For example, Microsoft Office's Excel requires it even on non-Windows OSes. Try:


That encoder will add the BOM.

Install MySQL on Ubuntu without a password prompt

Another way to make it work:

echo "mysql-server-5.5 mysql-server/root_password password root" | debconf-set-selections
echo "mysql-server-5.5 mysql-server/root_password_again password root" | debconf-set-selections
apt-get -y install mysql-server-5.5

Note that this simply sets the password to "root". I could not get it to set a blank password using simple quotes '', but this solution was sufficient for me.

Based on a solution here.

Android read text raw resource file

InputStream is=getResources().openRawResource(;
BufferedReader reader=new BufferedReader(new InputStreamReader(is));
StringBuffer data=new StringBuffer();
String line=reader.readLine();

Oracle comparing timestamp with date

You can truncate the date

FROM Table1
WHERE trunc(field1) = to_Date('2012-01-01','YYY-MM-DD')

Look at the SQL Fiddle for more examples.

remove duplicates from sql union

Others have already answered your direct question, but perhaps you could simplify the query to eliminate the question (or have I missed something, and a query like the following will really produce substantially different results?):

select * 
    from calls c join users u
        on c.assigned_to = u.user_id 
        or c.requestor_id = u.user_id
    where u.dept = 4

How can I get the timezone name in JavaScript?

You can simply write your own code by using the mapping table here:

or, use moment-timezone library:

See; // America/Los_Angeles

or, this library:

postgresql - add boolean column to table set default

If you are using postgresql then you have to use column type BOOLEAN in lower case as boolean.

ALTER TABLE users ADD "priv_user" boolean DEFAULT false;

Convert String to Type in C#

If you really want to get the type by name you may use the following:

System.AppDomain.CurrentDomain.GetAssemblies().SelectMany(x => x.GetTypes()).First(x => x.Name == "theassembly");

Note that you can improve the performance of this drastically the more information you have about the type you're trying to load.


---- Remove Constraint ----

---- Delete Data ----
EXEC sp_MSForEachTable "DELETE FROM ?"

---- Add Constraint ----

---- Reset Identity value ----
EXEC sp_MSForEachTable "DBCC CHECKIDENT ( '?', RESEED, 0)"

What causes HttpHostConnectException?

You must set proxy server for gradle at some time, you can try to change the proxy server ip address in which is under .gradle document

While variable is not defined - wait

Shorter way:

   var queue = function (args){
      typeof variableToCheck !== "undefined"? doSomething(args) : setTimeout(function () {queue(args)}, 2000);

You can also pass arguments

'POCO' definition

Most people have said it - Plain Old CLR Object (as opposed to the earlier POJO - Plain Old Java Object)

The POJO one came out of EJB, which required you to inherit from a specific parent class for things like value objects (what you get back from a query in an ORM or similar), so if you ever wanted to move from EJB (eg to Spring), you were stuffed.

POJO's are just classes which dont force inheritance or any attribute markup to make them "work" in whatever framework you are using.

POCO's are the same, except in .NET.

Generally it'll be used around ORM's - older (and some current ones) require you to inherit from a specific base class, which ties you to that product. Newer ones dont (nhibernate being the variant I know) - you just make a class, register it with the ORM, and you are off. Much easier.

Matching special characters and letters in regex

Add them to the allowed characters, but you'll need to escape some of them, such as -]/\

var pattern = /^[a-zA-Z0-9!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]*$/

That way you can remove any individual character you want to disallow.

Also, you want to include the start and end of string placemarkers ^ and $


As elclanrs understood (and the rest of us didn't, initially), the only special characters needing to be allowed in the pattern are &-._


[\w] is the same as [a-zA-Z0-9_]

Though the dash doesn't need escaping when it's at the start or end of the list, I prefer to do it in case other characters are added. Additionally, the + means you need at least one of the listed characters. If zero is ok (ie an empty value), then replace it with a * instead:


Label on the left side instead above an input field

I am sure you would've already found your answer... here is the solution I derived at.

That's my CSS.

.field, .actions {
    margin-bottom: 15px;
  .field label {
    float: left;
    width: 30%;
    text-align: right;
    padding-right: 10px;
    margin: 5px 0px 5px 0px;
  .field input {
    width: 70%;
    margin: 0px;

And my HTML...

<h1>New customer</h1>
<div class="container form-center">
    <form accept-charset="UTF-8" action="/customers" class="new_customer" id="new_customer" method="post">
    <div style="margin:0;padding:0;display:inline"></div>

  <div class="field">
    <label for="customer_first_name">First name</label>
    <input class="form-control" id="customer_first_name" name="customer[first_name]" type="text" />
  <div class="field">
    <label for="customer_last_name">Last name</label>
    <input class="form-control" id="customer_last_name" name="customer[last_name]" type="text" />
  <div class="field">
    <label for="customer_addr1">Addr1</label>
    <input class="form-control" id="customer_addr1" name="customer[addr1]" type="text" />
  <div class="field">
    <label for="customer_addr2">Addr2</label>
    <input class="form-control" id="customer_addr2" name="customer[addr2]" type="text" />
  <div class="field">
    <label for="customer_city">City</label>
    <input class="form-control" id="customer_city" name="customer[city]" type="text" />
  <div class="field">
    <label for="customer_pincode">Pincode</label>
    <input class="form-control" id="customer_pincode" name="customer[pincode]" type="text" />
  <div class="field">
    <label for="customer_homephone">Homephone</label>
    <input class="form-control" id="customer_homephone" name="customer[homephone]" type="text" />
  <div class="field">
    <label for="customer_mobile">Mobile</label>
    <input class="form-control" id="customer_mobile" name="customer[mobile]" type="text" />
  <div class="actions">
    <input class="btn btn-primary btn-large btn-block" name="commit" type="submit" value="Create Customer" />

You can see the working example here...

PS: I am a beginner too, pro designers... feel free share your reviews.

recyclerview No adapter attached; skipping layout

In Kotlin we had this weird illogical issue.

This didn't work:

 mBinding.serviceProviderCertificates.apply {
            adapter = adapter
            layoutManager =  LinearLayoutManager(activity)

While this worked:

mBinding.serviceProviderCertificates.adapter = adapter
mBinding.serviceProviderCertificates.layoutManager = LinearLayoutManager(activity)

Once I get more after work hours, I will share more insights.

How to POST a JSON object to a JAX-RS service

Jersey makes the process very easy, my service class worked well with JSON, all I had to do is to add the dependencies in the pom.xml

public class CustomerService {

    private static Map<Integer, Customer> customers = new HashMap<Integer, Customer>();

    public SaveResult save(Customer c) {

        customers.put(c.getId(), c);

        SaveResult sr = new SaveResult();
        sr.sucess = true;
        return sr;

    public Customer getCustomer(@PathParam("id") int id) {
        Customer c = customers.get(id);
        if (c == null) {
            c = new Customer();
            c.setId(id * 3);
            c.setName("unknow " + id);
        return c;

And in the pom.xml


Ajax - 500 Internal Server Error

The 500 (internal server error) means something went wrong on the server's side. It could be several things, but I would start by verifying that the URL and parameters are correct. Also, make sure that whatever handles the request is expecting the request as a GET and not a POST.

One useful way to learn more about what's going on is to use a tool like Fiddler which will let you watch all HTTP requests and responses so you can see exactly what you're sending and the server is responding with.

If you don't have a compelling reason to write your own Ajax code, you would be far better off using a library that handles the Ajax interactions for you. jQuery is one option.

What is the use of join() in Python threading?

There are a few reasons for the main thread (or any other thread) to join other threads

  1. A thread may have created or holding (locking) some resources. The join-calling thread may be able to clear the resources on its behalf

  2. join() is a natural blocking call for the join-calling thread to continue after the called thread has terminated.

If a python program does not join other threads, the python interpreter will still join non-daemon threads on its behalf.

How to run cron job every 2 hours

0 */2 * * *

The answer is from It is interesting.

What are the uses of "using" in C#?

Everything outside the curly brackets is disposed, so it is great to dispose your objects if you are not using them. This is so because if you have a SqlDataAdapter object and you are using it only once in the application life cycle and you are filling just one dataset and you don't need it anymore, you can use the code:

using(SqlDataAdapter adapter_object = new SqlDataAdapter(sql_command_parameter))
   // do stuff
} // here adapter_object is disposed automatically

How can I make one python file run another?

I used it's almost same like subprocess.Popen

from subprocess import call
call(["python", ""])

Client to send SOAP request and receive response

As an alternative, and pretty close to debiasej approach. Since a SOAP request is just a HTTP request, you can simply perform a GET or POST using with HTTP client, but it's not mandatory to build SOAP envelope.

Something like this:

using Microsoft.Extensions.Logging;
using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

namespace HGF.Infraestructure.Communications
    public class SOAPSample
        private readonly IHttpClientFactory _clientFactory;
        private readonly ILogger<DocumentProvider> _logger;

        public SOAPSample(ILogger<DocumentProvider> logger,
                          IHttpClientFactory clientFactory)
            _clientFactory = clientFactory;
            _logger = logger;

        public async Task<string> UsingGet(int value1, int value2)
                var client = _clientFactory.CreateClient();
                var response = await client.GetAsync($"{value1}&value2={value2}", HttpCompletionOption.ResponseHeadersRead);

                //NULL check, HTTP Status Check....

                return await response.Content.ReadAsStringAsync();
            catch (Exception ex)
                _logger.LogError(ex, "Oops! Something went wrong");
                return ex.Message;

        public async Task<string> UsingPost(int value1, int value2)
                var content = new StringContent($"value1={value1}&value2={value2}", Encoding.UTF8, "application/x-www-form-urlencoded");

                var client = _clientFactory.CreateClient();
                var response = await client.PostAsync("", content);

                //NULL check, HTTP Status Check....

                return await response.Content.ReadAsStringAsync();
            catch (Exception ex)
                _logger.LogError(ex, "Oops! Something went wrong");
                return ex.Message;

Of course, it depends on your scenario. If the payload is too complex, then this won't work

How to sort in-place using the merge sort algorithm?

The critical step is getting the merge itself to be in-place. It's not as difficult as those sources make out, but you lose something when you try.

Looking at one step of the merge:


We know that the sorted sequence is less than everything else, that x is less than everything else in A, and that y is less than everything else in B. In the case where x is less than or equal to y, you just move your pointer to the start of A on one. In the case where y is less than x, you've got to shuffle y past the whole of A to sorted. That last step is what makes this expensive (except in degenerate cases).

It's generally cheaper (especially when the arrays only actually contain single words per element, e.g., a pointer to a string or structure) to trade off some space for time and have a separate temporary array that you sort back and forth between.

How do you concatenate Lists in C#?

It also worth noting that Concat works in constant time and in constant memory. For example, the following code

        long boundary = 60000000;
        for (long i = 0; i < boundary; i++)
        var listConcat = list1.Concat(list2);
        var list = listConcat.ToList();

gives the following timing/memory metrics:

After lists filled mem used: 1048730 KB
concat two enumerables: 00:00:00.0023309 mem used: 1048730 KB
convert concat to list: 00:00:03.7430633 mem used: 2097307 KB
list1.AddRange(list2) : 00:00:00.8439870 mem used: 2621595 KB

How do I send an HTML Form in an Email .. not just MAILTO

I don't know that what you want to do is possible. From my understanding, sending an email from a web form requires a server side language to communicate with a mail server and send messages.

Are you running PHP or ASP.NET?

ASP.NET Example

PHP Example

How to add bootstrap in angular 6 project?

npm install --save bootstrap

afterwards, inside angular.json (previously .angular-cli.json) inside the project's root folder, find styles and add the bootstrap css file like this:

for angular 6

"styles": [

for angular 7

"styles": [

Extracting extension from filename in Python

Just join all pathlib suffixes.

>>> x = 'file/path/archive.tar.gz'
>>> y = 'file/path/text.txt'
>>> ''.join(pathlib.Path(x).suffixes)
>>> ''.join(pathlib.Path(y).suffixes)


TIME_WAIT might not be the culprit.

int listen(int sockfd, int backlog);

According to Unix Network Programming Volume1, backlog is defined to be the sum of completed connection queue and incomplete connection queue.

Let's say the backlog is 5. If you have 3 completed connections (ESTABLISHED state), and 2 incomplete connections (SYN_RCVD state), and there is another connect request with SYN. The TCP stack just ignores the SYN packet, knowing it'll be retransmitted some other time. This might be causing the degradation.

At least that's what I've been reading. ;)

Save string to the NSUserDefaults?

Something like this:

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

// saving an NSString
[prefs setObject:@"TextToSave" forKey:@"keyToLookupString"];

Then to retrieve:

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

// getting an NSString
NSString *myString = [prefs stringForKey:@"keyToLookupString"];

You should really check out Apple's NSUserDefaults Class Reference and also maybe this tutorial: iPhone Programming Tutorial – Saving/Retrieving Data Using NSUserDefaults

Pandas - replacing column values

Can try this too!
Create a dictionary of replacement values.

import pandas as pd
data = pd.DataFrame([[1,0],[0,1],[1,0],[0,1]], columns=["sex", "split"])

enter image description here

replace_dict= {0:'Female',1:'Male'}

enter image description here

Use the map function for replacing values


Output after replacing
enter image description here

Keystore change passwords

To change the password for a key myalias inside of the keystore mykeyfile:

keytool -keystore mykeyfile -keypasswd -alias myalias

How exactly does the android:onClick XML attribute differ from setOnClickListener?

   Add Button in xml and give onclick attribute name that is the name of Method.
   <!--xml --!>

    Button btnAdd = (Button) findViewById(; btnAdd.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {

  Private void addNumber(View v){
  //Logic implement 
    switch (v.getId()) {
    case :

Split string in JavaScript and detect line break

Split string in JavaScript

var array = str.match(/[^\r\n]+/g);


var array = str.split(/\r?\n/);


How to convert an entire MySQL database characterset and collation to UTF-8?

  1. Make a backup!

  2. Then you need to set the default char sets on the database. This does not convert existing tables, it only sets the default for newly created tables.

    ALTER DATABASE dbname CHARACTER SET utf8 COLLATE utf8_general_ci;
  3. Then, you will need to convert the char set on all existing tables and their columns. This assumes that your current data is actually in the current char set. If your columns are set to one char set but your data is really stored in another then you will need to check the MySQL manual on how to handle this.

    ALTER TABLE tbl_name CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;

What is the difference between an Instance and an Object?

Java is an object-oriented programming language (OOP). This means, that everything in Java, except of the primitive types is an object.

Now, Java objects are similar to real-world objects. For example we can create a car object in Java, which will have properties like current speed and color; and behavior like: accelerate and park.

That's Object.

enter image description here

Instance, on the other side, is a uniquely initialized copy of that object that looks like Car car = new Car().

Check it out to learn more about Java classes and object

Quickest way to clear all sheet contents VBA

Technically, and from Comintern's accepted workaround, I believe you actually want to Delete all the Cells in the Sheet. Which removes Formatting (See footnote for exceptions), etc. as well as the Cells Contents. I.e. Sheets("Zeroes").Cells.Delete

Combined also with UsedRange, ScreenUpdating and Calculation skipping it should be nearly intantaneous:

Sub DeleteCells ()
    Application.Calculation = XlManual
    Application.ScreenUpdating = False
    Application.ScreenUpdating = True
    Application.Calculation = xlAutomatic
End Sub

Or if you prefer to respect the Calculation State Excel is currently in:

Sub DeleteCells ()
    Dim SaveCalcState
    SaveCalcState = Application.Calculation
    Application.Calculation = XlManual
    Application.ScreenUpdating = False
    Application.ScreenUpdating = True
    Application.Calculation = SaveCalcState
End Sub

Footnote: If formatting was applied for an Entire Column, then it is not deleted. This includes Font Colour, Fill Colour and Borders, the Format Category (like General, Date, Text, Etc.) and perhaps other properties too, but

Conditional formatting IS deleted, as is Entire Row formatting.

(Entire Column formatting is quite useful if you are importing raw data repeatedly to a sheet as it will conform to the Formats originally applied if a simple Paste-Values-Only type import is done.)

XPath: How to select elements based on their value?

//Element[@attribute1="abc" and @attribute2="xyz" and .="Data"]

The reason why I add this answer is that I want to explain the relationship of . and text() .

The first thing is when using [], there are only two types of data:

  1. [number] to select a node from node-set
  2. [bool] to filter a node-set from node-set

In this case, the value is evaluated to boolean by function boolean(), and there is a rule:

Filters are always evaluated with respect to a context.

When you need to compare text() or . with a string "Data", it first uses string() function to transform those to string type, than gets a boolean result.

There are two important rule about string():

  1. The string() function converts a node-set to a string by returning the string value of the first node in the node-set, which in some instances may yield unexpected results.

    text() is relative path that return a node-set contains all the text node of current node(context node), like ["Data"]. When it is evaluated by string(["Data"]), it will return the first node of node-set, so you get "Data" only when there is only one text node in the node-set.

  2. If you want the string() function to concatenate all child text, you must then pass a single node instead of a node-set.

    For example, we get a node-set ['a', 'b'], you can pass there parent node to string(parent), this will return 'ab', and of cause string(.) in you case will return an concatenated string "Data".

Both way will get same result only when there is a text node.

IntelliJ: Never use wildcard imports

The solution above was not working for me. I had to set 'class count to use import with '*'' to a high value, e.g. 999.

Safely limiting Ansible playbooks to a single machine?

I really don't understand how all the answers are so complicated, the way to do it is simply:

ansible-playbook user.yml -i hosts/hosts --limit imac-2.local --check

The check mode allows you to run in dry-run mode, without making any change.

TypeError: worker() takes 0 positional arguments but 1 was given

Your worker method needs 'self' as a parameter, since it is a class method and not a function. Adding that should make it work fine.

How to prevent tensorflow from allocating the totality of a GPU memory?

If you're using Tensorflow 2 try the following:

config = tf.compat.v1.ConfigProto()
config.gpu_options.allow_growth = True
session = tf.compat.v1.Session(config=config)

Redis - Connect to Remote Server

Setting tcp-keepalive to 60 (it was set to 0) in server's redis configuration helped me resolve this issue.

Extract a page from a pdf as a jpeg

Here is a solution which requires no additional libraries and is very fast. This was found from: I have added the code in a function to make it more convenient.

def convert(filepath):
    with open(filepath, "rb") as file:
        pdf =

    startmark = b"\xff\xd8"
    startfix = 0
    endmark = b"\xff\xd9"
    endfix = 2
    i = 0

    njpg = 0
    while True:
        istream = pdf.find(b"stream", i)
        if istream < 0:
        istart = pdf.find(startmark, istream, istream + 20)
        if istart < 0:
            i = istream + 20
        iend = pdf.find(b"endstream", istart)
        if iend < 0:
            raise Exception("Didn't find end of stream!")
        iend = pdf.find(endmark, iend - 20)
        if iend < 0:
            raise Exception("Didn't find end of JPG!")

        istart += startfix
        iend += endfix
        jpg = pdf[istart:iend]
        newfile = "{}jpg".format(filepath[:-3])
        with open(newfile, "wb") as jpgfile:

        njpg += 1
        i = iend

        return newfile

Call convert with the pdf path as the argument and the function will create a .jpg file in the same directory

Splitting applicationContext to multiple files

There are two types of contexts we are dealing with:

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

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

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

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

How do I clear all variables in the middle of a Python script?

If you write a function then once you leave it all names inside disappear.

The concept is called namespace and it's so good, it made it into the Zen of Python:

Namespaces are one honking great idea -- let's do more of those!

The namespace of IPython can likewise be reset with the magic command %reset -f. (The -f means "force"; in other words, "don't ask me if I really want to delete all the variables, just do it.")

How do I get the web page contents from a WebView?

Have you considered fetching the HTML separately, and then loading it into a webview?

String fetchContent(WebView view, String url) throws IOException {
    HttpClient httpClient = new DefaultHttpClient();
    HttpGet get = new HttpGet(url);
    HttpResponse response = httpClient.execute(get);
    StatusLine statusLine = response.getStatusLine();
    int statusCode = statusLine.getStatusCode();
    HttpEntity entity = response.getEntity();
    String html = EntityUtils.toString(entity); // assume html for simplicity
    view.loadDataWithBaseURL(url, html, "text/html", "utf-8", url); // todo: get mime, charset from entity
    if (statusCode != 200) {
        // handle fail
    return html;

How to send post request with x-www-form-urlencoded body

As you set application/x-www-form-urlencoded as content type so data sent must be like this format.

String urlParameters  = "param1=data1&param2=data2&param3=data3";

Sending part now is quite straightforward.

byte[] postData = urlParameters.getBytes( StandardCharsets.UTF_8 );
int postDataLength = postData.length;
String request = "<Url here>";
URL url = new URL( request );
HttpURLConnection conn= (HttpURLConnection) url.openConnection();           
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); 
conn.setRequestProperty("charset", "utf-8");
conn.setRequestProperty("Content-Length", Integer.toString(postDataLength ));
try(DataOutputStream wr = new DataOutputStream(conn.getOutputStream())) {
   wr.write( postData );

Or you can create a generic method to build key value pattern which is required for application/x-www-form-urlencoded.

private String getDataString(HashMap<String, String> params) throws UnsupportedEncodingException{
    StringBuilder result = new StringBuilder();
    boolean first = true;
    for(Map.Entry<String, String> entry : params.entrySet()){
        if (first)
            first = false;
        result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
        result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
    return result.toString();

vertical align middle in <div>

I found this solution by Sebastian Ekström. It's quick, dirty, and works really well. Even if you don't know the parent's height:

.element {
  position: relative;
  top: 50%;
  -webkit-transform: translateY(-50%);
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);

Read the full article here.

Android: Difference between Parcelable and Serializable?

I am late in answer, but posting with hope that it will help others.

In terms of Speed, Parcelable > Serializable. But, Custom Serializable is exception. It is almost in range of Parcelable or even more faster.

Reference :

Example :

Custom Class to be serialized

class MySerialized implements Serializable { 

    String deviceAddress = "MyAndroid-04"; 

    transient String token = "AABCDS"; // sensitive information which I do not want to serialize

    private void writeObject(ObjectOutputStream oos) throws Exception {
        oos.writeObject("111111" + token); // Encrypted token to be serialized

    private void readObject(ObjectInputStream ois) throws Exception {
        token = ((String) ois.readObject()).subString(6);  // Decrypting token


Python: create dictionary using dict() with integer keys?

Yes, but not with that version of the constructor. You can do this:

>>> dict([(1, 2), (3, 4)])
{1: 2, 3: 4}

There are several different ways to make a dict. As documented, "providing keyword arguments [...] only works for keys that are valid Python identifiers."

How to create an installer for a .net Windows Service using Visual Studio

InstallUtil classes ( ServiceInstaller ) are considered an anti-pattern by the Windows Installer community. It's a fragile, out of process, reinventing of the wheel that ignores the fact that Windows Installer has built-in support for Services.

Visual Studio deployment projects ( also not highly regarded and deprecated in the next release of Visual Studio ) do not have native support for services. But they can consume merge modules. So I would take a look at this blog article to understand how to create a merge module using Windows Installer XML that can express the service and then consume that merge module in your VDPROJ solution.

Augmenting InstallShield using Windows Installer XML - Windows Services

IsWiX Windows Service Tutorial

IsWiX Windows Service Video

JQuery datepicker not working

You did not include the datepicker library

so add

<script type="text/javascript" src=""></script>

to your <head> tag

live demo

Determine the process pid listening on a certain port

on windows, the netstat option to get the pid's is -o and -p selects a protocol filter, ex.: netstat -a -p tcp -o

How to parse a JSON file in swift?

I just wrote a class called JSON, which makes JSON handling in Swift as easy as JSON object in ES5.

Turn your swift object to JSON like so:

let obj:[String:AnyObject] = [
    "array": [JSON.null, false, 0, "",[],[:]],
        "null":   JSON.null,
        "bool":   true,
        "int":    42,
        "double": 3.141592653589793,
        "string": "a a\t?\n",
        "array":  [],
        "object": [:]

let json = JSON(obj)

...or string...

let json = JSON.parse("{\"array\":[...}")

...or URL.

let json = JSON.fromURL("")
Tree Traversal

Just traverse elements via subscript:

json["object"]["null"].asNull       // NSNull()
// ...
json["object"]["string"].asString   // "a a\t?\n"
json["array"][0].asNull             // NSNull()
json["array"][1].asBool             // false
// ...

Just like SwiftyJSON you don't worry if the subscripted entry does not exist.

if let b = json["noexistent"][1234567890]["entry"].asBool {
    // ....
} else {
    let e = json["noexistent"][1234567890]["entry"].asError

If you are tired of subscripts, add your scheme like so:

//// schema by subclassing
class MyJSON : JSON {
    init(_ obj:AnyObject){ super.init(obj) }
    init(_ json:JSON)  { super.init(json) }
    var null  :NSNull? { return self["null"].asNull }
    var bool  :Bool?   { return self["bool"].asBool }
    var int   :Int?    { return self["int"].asInt }
    var double:Double? { return self["double"].asDouble }
    var string:String? { return self["string"].asString }

And you go:

let myjson = MyJSON(obj)
// ...

Hope you like it.

With the new xCode 7.3+ its important to add your domain to the exception list (How can I add NSAppTransportSecurity to my info.plist file?), refer to this posting for instructions, otherwise you will get a transport authority error.

How do I make an Event in the Usercontrol and have it handled in the Main Form?

Try mapping it. Try placing this code in your UserControl:

public event EventHandler ValueChanged {
  add { numericUpDown1.ValueChanged += value; }
  remove { numericUpDown1.ValueChanged -= value; }

then your UserControl will have the ValueChanged event you normally see with the NumericUpDown control.

Elegant way to report missing values in a data.frame

Another function that would help you look at missing data would be df_status from funModeling library


iris.2 is the iris dataset with some added NAs.You can replace this with your dataset.


This will give you the number and percentage of NAs in each column.

How can I bring my application window to the front?

Here is a piece of code that worked for me

this.WindowState = FormWindowState.Minimized;
this.WindowState = FormWindowState.Normal;

It always brings the desired window to the front of all the others.

Python argparse command line flags without arguments

As you have it, the argument w is expecting a value after -w on the command line. If you are just looking to flip a switch by setting a variable True or False, have a look here (specifically store_true and store_false)

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('-w', action='store_true')

where action='store_true' implies default=False.

Conversely, you could haveaction='store_false', which implies default=True.

Create PDF from a list of images

Ready-to-use solution that converts all PNG in the current folder to a PDF, inspired by @ilovecomputer's answer:

import glob, PIL.Image
L = [ for f in glob.glob('*.png')]
L[0].save('out.pdf', "PDF" ,resolution=100.0, save_all=True, append_images=L[1:])

Nothing else than PIL is needed :)

How can I use external JARs in an Android project?

If using Android Studio, do the following (I've copied and modified @Vinayak Bs answer):

  1. Select the Project view in the Project sideview (instead of Packages or Android)
  2. Create a folder called libs in your project's root folder
  3. Copy your JAR files to the libs folder
  4. The sideview will be updated and the JAR files will show up in your project
  5. Now right click on each JAR file you want to import and then select "Add as Library...", which will include it in your project
  6. After that, all you need to do is reference the new classes in your code, eg. import javax.mail.*

How do I add options to a DropDownList using jQuery?

Pease note @Phrogz's solution doesn't work in IE 8 while @nickf's works in all major browsers. Another approach is:

$.each(myOptions, function(val, text) {
    $("#mySelect").append($("&lt;option/&gt;").attr("value", val).text(text));

Click event on select option element in chrome

Looking for this on 2018. Click event on option tag, inside a select tag, is not fired on Chrome.

Use change event, and capture the selected option:

$(document).delegate("select", "change", function() {
    //capture the option
    var $target = $("option:selected",$(this));

Be aware that $target may be a collection of objects if the select tag is multiple.

How to create a new instance from a class object in Python

This is how you can dynamically create a class named Child in your code, assuming Parent already exists... even if you don't have an explicit Parent class, you could use object...

The code below defines __init__() and then associates it with the class.

>>> child_name = "Child"
>>> child_parents = (Parent,)
>>> child body = """
def __init__(self, arg1):
    # Initialization for the Child class = do_something(arg1)
>>> child_dict = {}
>>> exec(child_body, globals(), child_dict)
>>> childobj = type(child_name, child_parents, child_dict)
>>> childobj.__name__
>>> childobj.__bases__
(<type 'object'>,)
>>> # Instantiating the new Child object...
>>> childinst = childobj()
>>> childinst
<__main__.Child object at 0x1c91710>

Visual Studio: How to show Overloads in IntelliSense?

Tested only on Visual Studio 2010.

Place your cursor within the (), press Ctrl+K, then P.

Now navigate by pressing the  ?  / ?   arrow keys.

Set IDENTITY_INSERT ON is not working

You might be just missing the column list, as the message says

SET IDENTITY_INSERT [MyDB].[dbo].[Equipment] ON

INSERT INTO [MyDB].[dbo].[Equipment]
FROM   [MyDBQA].[dbo].[Equipment]

SET IDENTITY_INSERT [MyDB].[dbo].[Equipment] OFF 

Toolbar navigation icon never set

I had simillar problem. After a big headache I found, that my ActionBarDrawerToggle was modifying the icon, also when it should not modify the icon (because I didn't give reference to toolbar to the toggle component). So in my NavigationDrawerFragment class (that handles the opening and closing) in setUp(...) method I set
and finally it worked.

Get PostGIS version

Did you try using SELECT PostGIS_version();

Change tab bar item selected color in a storyboard

You can change colors UITabBarItem by storyboard but if you want to change colors by code it's very easy:

// Use this for change color of selected bar

   [[UITabBar appearance] setTintColor:[UIColor blueColor]];

// This for change unselected bar (iOS 10)

   [[UITabBar appearance] setUnselectedItemTintColor:[UIColor yellowColor]];

// And this line for change color of all tabbar

   [[UITabBar appearance] setBarTintColor:[UIColor whiteColor]];

How to enumerate an object's properties in Python?

This is totally covered by the other answers, but I'll make it explicit. An object may have class attributes and static and dynamic instance attributes.

class foo:
    classy = 1
    def dyno(self):
        return 1
    def __init__(self):
        self.stasis = 2

    def fx(self):
        return 3

stasis is static, dyno is dynamic (cf. property decorator) and classy is a class attribute. If we simply do __dict__ or vars we will only get the static one.

o = foo()
print(o.__dict__) #{'stasis': 2}
print(vars(o)) #{'stasis': 2}

So if we want the others __dict__ will get everything (and more). This includes magic methods and attributes and normal bound methods. So lets avoid those:

d = {k: getattr(o, k, '') for k in o.__dir__() if k[:2] != '__' and type(getattr(o, k, '')).__name__ != 'method'}
print(d) #{'stasis': 2, 'classy': 1, 'dyno': 1}

The type called with a property decorated method (a dynamic attribute) will give you the type of the returned value, not method. To prove this let's json stringify it:

import json
print(json.dumps(d)) #{"stasis": 2, "classy": 1, "dyno": 1}

Had it been a method it would have crashed.

TL;DR. try calling extravar = lambda o: {k: getattr(o, k, '') for k in o.__dir__() if k[:2] != '__' and type(getattr(o, k, '')).__name__ != 'method'} for all three, but not methods nor magic.

Error in MySQL when setting default value for DATE or DATETIME

I had this error with WAMP 3.0.6 with MySql 5.7.14.


change line 70 (if your ini file is untouched) in c:\wamp\bin\mysql\mysql5.7.14\my.ini file from




and restart all services.

This will disable strict mode. As per the documentation, “strict mode” means a mode with either or both STRICT_TRANS_TABLES or STRICT_ALL_TABLES enabled. The documentation says:


How to center horizontal table-cell

If you add text-align: center to the declarations for .columns-container then they align centrally:

.columns-container {
    display: table-cell;
    height: 100%;
    text-align: center;

 * Sticky footer hack_x000D_
 * Source:
/* Stretching all container's parents to full height */_x000D_
body {_x000D_
  height: 100%;_x000D_
  margin: 0;_x000D_
  padding: 0;_x000D_
/* Setting the container to be a table with maximum width and height */_x000D_
#container {_x000D_
  display: table;_x000D_
  height: 100%;_x000D_
  width: 100%;_x000D_
/* All sections (container's children) should be table rows with minimal height */_x000D_
.section {_x000D_
  display: table-row;_x000D_
  height: 1px;_x000D_
/* The last-but-one section should be stretched to automatic height */_x000D_
.section.expand {_x000D_
  height: auto;_x000D_
 * Full height columns_x000D_
/* We need one extra container, setting it to full width */_x000D_
.columns-container {_x000D_
display: table-cell;_x000D_
height: 100%;_x000D_
text-align: center;_x000D_
/* Creating columns */_x000D_
.column {_x000D_
  /* The float:left won't work for Chrome for some reason, so inline-block */_x000D_
  display: inline-block;_x000D_
  /* for this to work, the .column elements should have NO SPACE BETWEEN THEM */_x000D_
  vertical-align: top;_x000D_
  height: 100%;_x000D_
  width: 100px;_x000D_
 * Just some coloring so that we're able to see height of columns_x000D_
header {_x000D_
  background-color: yellow;_x000D_
#a {_x000D_
  background-color: pink;_x000D_
#b {_x000D_
  background-color: lightgreen;_x000D_
#c {_x000D_
  background-color: lightblue;_x000D_
footer {_x000D_
  background-color: purple;_x000D_
<div id="container">_x000D_
  <header class="section">_x000D_
  <div class="section expand">_x000D_
    <div class="columns-container">_x000D_
      <div class="column" id="a">_x000D_
        <p>Contents A</p>_x000D_
      <div class="column" id="b">_x000D_
        <p>Contents B</p>_x000D_
      <div class="column" id="c">_x000D_
        <p>Contents C</p>_x000D_
  <footer class="section">_x000D_

This does, though, require that you reset the .column elements to text-align: left (assuming you want them left-aligned, obviously (JS Fiddle demo).

What is Gradle in Android Studio?

I refer two tutorial to write the Answer one,two

Gradle is a general purpose, declarative build tool. It is general purpose because it can be used to build pretty much anything you care to implement in the build script. It is declarative since you don't want to see lots of code in the build file, which is not readable and less maintainable. So, while Gradle provides the idea of conventions and a simple and declarative build, it also makes the tool adaptable and developers the ability to extend. It also provides an easy way to customize the default behavior and different hooks to add any third-party features.

Gradle combines the good parts of both tools and provides additional features and uses Groovy as a Domain Specific Language (DSL). It has power and flexibility of Ant tool with Maven features such as build life cycle and ease of use.

Why Gradle? Why Now?

The build tool's response is to add scripting functionality through nonstandard extension mechanisms. You end up mixing scripting code with XML or invoking external scripts from your build logic. It's easy to imagine that you'll need to add more and more custom code over time. As a result, you inevitably introduce accidental complexity, and maintainability goes out the window.

Let's say you want to copy a file to a specific location when you're building the release version of your project. To identify the version, you check a string in the metadata describing your project. If it matches a specific numbering scheme (for example, 1.0-RELEASE), you copy the file from point A to point B. From an outside perspective, this may sound like a trivial task. If you have to rely on XML, the build language of many traditional tools, expressing this simple logic becomes fairly difficult.

Evolution of Java Build Tools

Java build logic has to be described in XML. XML is great for describing hierarchical data but falls short on expressing program flow and conditional logic. As a build script grows in complexity, maintaining the building code becomes a nightmare.

In Ant, you make the JAR target depend on the compile target. Ant doesn't give any guidance on how to structure your project. Though it allows for maximum flexibility, Ant makes each build script unique and hard to understand. External libraries required by your project are usually checked into version control because there is no automated mechanism to pull them from a central location.

Maven 1, released in July 2004, tried to ease that process. It provided a standardized project and directory structure, as well as dependency management. Unfortunately, custom logic is hard to implement

Gradle fits right into that generation of build tools and satisfies many requirements of modern build tools (Figure 1). It provides an expressive DSL, a convention over configuration approach, and powerful dependency management. It makes the right move to abandon XML and introduce the dynamic language Groovy to define your build logic. Sounds compelling, doesn't it?

Gradle combines the best features of other build tools.

enter image description here

Gradle's Compelling Feature Set

enter image description here

Why Build Your Java Projects with Gradle Rather than Ant or Maven?

The default build tool for Android (and the new star of build tools on the JVM) is designed to ease scripting of complex, multi-language builds. Should you change to it, though, if you're using Ant or Maven?

The key to unlocking Gradle's power features within your build script lies in discovering and applying its domain model, as shown in below image. enter image description here

Gradle can't know all the requirements specific to your enterprise build. By exposing hooks into lifecycle phases, Gradle allows for monitoring and configuring the build script's execution behavior.

Gradle establishes a vocabulary for its model by exposing a DSL implemented in Groovy. When dealing with a complex problem domain, in this case, the task of building software, being able to use a common language to express your logic can be a powerful tool.

Another example is the way you can express dependencies to external libraries, a very common problem solved by build tools. Out-of-the-box Gradle provides you with two configuration blocks for your build script that allow you to define the dependencies and repositories that you want to retrieve them from. If the standard DSL elements don't fit your needs, you can even introduce your own vocabulary through Gradle's extension mechanism.

Integration with Other Build Tools

Gradle plays well with its predecessors' Ant, Maven, and Ivy, as shown in the image below.

enter image description here

Automating Your Project from Build to Deployment

enter image description here

In image: Stages of a deployment pipeline.

  • Compiling the code

  • Running unit and integration tests

  • Performing static code analysis and generating test coverage

  • Creating the distribution

  • Provisioning the target environment

  • Deploying the deliverable

  • Performing smoke and automated functional tests

I refer two tutorial to write the Answer one,two

Dropping connected users in Oracle database

I was trying to follow the flow described here - but haven't luck to completely kill the session.. Then I fond additional step here:

What I did:
1. select 'alter system kill session ''' || sid || ',' || serial# || ''';' from v$session where username = '<your_schema>'; - as described below.
Out put will be something like this:
alter system kill session '22,15' immediate;
2. alter system disconnect session '22,15' IMMEDIATE ; - 22-sid, 15-serial - repeat the command for each returned session from previous command
3. Repeat steps 1-2 while select... not return an empty table
4. Call drop user...

What was missed - call alter system disconnect session '22,15' IMMEDIATE ; for each of session returned by select 'alter system kill session '..

How to capture UIView to UIImage without loss of quality on retina display

Some times drawRect Method makes problem so I got these answers more appropriate. You too may have a look on it Capture UIImage of UIView stuck in DrawRect method

Highcharts - how to have a chart with dynamic height?

Another good option is, to pass a renderTo HTML reference. If it is a string, the element by that id is used. Otherwise you can do:

chart: {
    renderTo: document.getElementById('container')

or with jquery:

chart: {
    renderTo: $('#container')[0]

Further information can be found here:

CSS: Center block, but align contents to the left

THIS works

<div style="display:inline-block;margin:10px auto;">
    <ul style="list-style-type:none;">
        <li style="text-align:left;"><span class="red">?</span> YouTube AutoComplete Keyword Scraper software <em>root keyword text box</em>.</li>
        <li style="text-align:left;"><span class="red">?</span> website <em>video search text box</em>.</li>
        <li style="text-align:left;"><span class="red">?</span> YouTube AutoComplete Keyword Scraper software <em>scraped keywords listbox</em>.</li>
        <li style="text-align:left;"><span class="red">?</span> YouTube AutoComplete Keyword Scraper software <em>right click context menu</em>.</li>

How do you get assembler output from C/C++ source in gcc?

If you're looking for LLVM assembly:

llvm-gcc -emit-llvm -S hello.c

Multi-Line Comments in Ruby?

Despite the existence of =begin and =end, the normal and a more correct way to comment is to use #'s on each line. If you read the source of any ruby library, you will see that this is the way multi-line comments are done in almost all cases.

Hide Twitter Bootstrap nav collapse on click

Add an id then to each

<li> add data-target="myMenu" data-toggle="collapse"
<div id="myMenu" class="nav-collapse">
    <ul class="nav">
      <li class="active" data-target="myMenu" data-toggle="collapse"><a href="#home">Home</a></li>
      <li data-target="myMenu" data-toggle="collapse"><a href="#about">About</a></li>
      <li data-target="myMenu" data-toggle="collapse"><a href="#portfolio">Portfolio</a></li>
      <li data-target="myMenu" data-toggle="collapse"><a href="#services">Services</a></li>
      <li data-target="myMenu" data-toggle="collapse"><a href="#contact">Contact</a></li>

How to enable external request in IIS Express?

The accepted answer to this question is a guide for getting IIS Express to work with webmatrix. I found this guide more useful when trying to get it to work with VS 2010.

I just followed steps 3 & 4 (running IIS Express as administrator) and had to temporarily disable my firewall to get it working.

You don't have permission to access / on this server

Check the apache User and Group setting in the httpd.conf. It should default to apache on AMI/RedHat or www-data on Debian.

grep '^Group\|^User' /etc/httpd/conf/httpd.conf

Then add the apache user to the group setting of your site's root directory.

sudo usermod -a -G <your-site-root-dir-group> apache

Convert Java Object to JsonNode in Jackson

As of Jackson 1.6, you can use:

JsonNode node = mapper.valueToTree(map);


JsonNode node = mapper.convertValue(object, JsonNode.class);

Source: is there a way to serialize pojo's directly to treemodel?

MS-access reports - The search key was not found in any record - on save

Also check the database version. I was having the problem with VBA CreateDatabase(sTempDBName, dbLangGeneral) in Access 2010 where I was using a 2003 database trying to link a table in a 2010 database. When I manually tried the link I got a message about no support for linking to a later version. Creating the temp database I was trying to link to using the option dbVersion40 "CreateDatabase(sTempDBName, dbLangGeneral, dbVersion40)" cured it.

warning: Insecure world writable dir /usr/local/bin in PATH, mode 040777

This should resolve your problem: chmod go-w {/path/of/user}

Build and Install unsigned apk on device without the development server?

There are two extensions you can use for this. This is added to react-native for setting these:

  1. disableDevInDebug: true: Disables dev server in debug buildType
  2. bundleInDebug: true: Adds jsbundle to debug buildType.

So, your final project.ext.react in android/app/build.gradle should look like below

project.ext.react = [
    enableHermes: false,  // clean and rebuild if changing
    devDisabledInDev: true, // Disable dev server in dev release
    bundleInDev: true, // add bundle to dev apk

Access Control Request Headers, is added to header in AJAX request with jQuery

Here is an example how to set a request header in a jQuery Ajax call:

  type: "POST",
  beforeSend: function(request) {
    request.setRequestHeader("Authority", authorizationToken);
  url: "entities",
  data: "json=" + escape(JSON.stringify(createRequestObject)),
  processData: false,
  success: function(msg) {
    $("#results").append("The result =" + StringifyPretty(msg));

Validation failed for one or more entities while saving changes to SQL Server Database using Entity Framework

Make sure that if you have nvarchar(50)in DB row you don't trying to insert more than 50characters in it. Stupid mistake but took me 3 hours to figure it out.

"Cannot verify access to path (C:\inetpub\wwwroot)", when adding a virtual directory

I had the same problem and couldn't figure it out for almost a day. I added IUSR and NetworkService to the folder permissions, I made sure it was running as NetworkService. I tried impersonation and even running as administrator (DO NOT DO THIS). Then someone recommended that I try running the page from inside the Windows 2008 R2 server and it pointed me to the Handler Mappings, which were all disabled.

I got it to work with this:

  • Open the Feature View of your website.
  • Go to Handler Mappings.
  • Find the path for .cshtml
  • Right Click and Click Edit Feature Permissions
  • Select Execute
  • Hit OK.

Now try refreshing your website.

How to get user name using Windows authentication in

This should work:


Identity returns an IPrincipal

Here is the link to the Microsoft documentation.

Keras input explanation: input_shape, units, batch_size, dim, etc


The amount of "neurons", or "cells", or whatever the layer has inside it.

It's a property of each layer, and yes, it's related to the output shape (as we will see later). In your picture, except for the input layer, which is conceptually different from other layers, you have:

  • Hidden layer 1: 4 units (4 neurons)
  • Hidden layer 2: 4 units
  • Last layer: 1 unit


Shapes are consequences of the model's configuration. Shapes are tuples representing how many elements an array or tensor has in each dimension.

Ex: a shape (30,4,10) means an array or tensor with 3 dimensions, containing 30 elements in the first dimension, 4 in the second and 10 in the third, totaling 30*4*10 = 1200 elements or numbers.

The input shape

What flows between layers are tensors. Tensors can be seen as matrices, with shapes.

In Keras, the input layer itself is not a layer, but a tensor. It's the starting tensor you send to the first hidden layer. This tensor must have the same shape as your training data.

Example: if you have 30 images of 50x50 pixels in RGB (3 channels), the shape of your input data is (30,50,50,3). Then your input layer tensor, must have this shape (see details in the "shapes in keras" section).

Each type of layer requires the input with a certain number of dimensions:

  • Dense layers require inputs as (batch_size, input_size)
    • or (batch_size, optional,...,optional, input_size)
  • 2D convolutional layers need inputs as:
    • if using channels_last: (batch_size, imageside1, imageside2, channels)
    • if using channels_first: (batch_size, channels, imageside1, imageside2)
  • 1D convolutions and recurrent layers use (batch_size, sequence_length, features)

Now, the input shape is the only one you must define, because your model cannot know it. Only you know that, based on your training data.

All the other shapes are calculated automatically based on the units and particularities of each layer.

Relation between shapes and units - The output shape

Given the input shape, all other shapes are results of layers calculations.

The "units" of each layer will define the output shape (the shape of the tensor that is produced by the layer and that will be the input of the next layer).

Each type of layer works in a particular way. Dense layers have output shape based on "units", convolutional layers have output shape based on "filters". But it's always based on some layer property. (See the documentation for what each layer outputs)

Let's show what happens with "Dense" layers, which is the type shown in your graph.

A dense layer has an output shape of (batch_size,units). So, yes, units, the property of the layer, also defines the output shape.

  • Hidden layer 1: 4 units, output shape: (batch_size,4).
  • Hidden layer 2: 4 units, output shape: (batch_size,4).
  • Last layer: 1 unit, output shape: (batch_size,1).


Weights will be entirely automatically calculated based on the input and the output shapes. Again, each type of layer works in a certain way. But the weights will be a matrix capable of transforming the input shape into the output shape by some mathematical operation.

In a dense layer, weights multiply all inputs. It's a matrix with one column per input and one row per unit, but this is often not important for basic works.

In the image, if each arrow had a multiplication number on it, all numbers together would form the weight matrix.

Shapes in Keras

Earlier, I gave an example of 30 images, 50x50 pixels and 3 channels, having an input shape of (30,50,50,3).

Since the input shape is the only one you need to define, Keras will demand it in the first layer.

But in this definition, Keras ignores the first dimension, which is the batch size. Your model should be able to deal with any batch size, so you define only the other dimensions:

input_shape = (50,50,3)
    #regardless of how many images I have, each image has this shape        

Optionally, or when it's required by certain kinds of models, you can pass the shape containing the batch size via batch_input_shape=(30,50,50,3) or batch_shape=(30,50,50,3). This limits your training possibilities to this unique batch size, so it should be used only when really required.

Either way you choose, tensors in the model will have the batch dimension.

So, even if you used input_shape=(50,50,3), when keras sends you messages, or when you print the model summary, it will show (None,50,50,3).

The first dimension is the batch size, it's None because it can vary depending on how many examples you give for training. (If you defined the batch size explicitly, then the number you defined will appear instead of None)

Also, in advanced works, when you actually operate directly on the tensors (inside Lambda layers or in the loss function, for instance), the batch size dimension will be there.

  • So, when defining the input shape, you ignore the batch size: input_shape=(50,50,3)
  • When doing operations directly on tensors, the shape will be again (30,50,50,3)
  • When keras sends you a message, the shape will be (None,50,50,3) or (30,50,50,3), depending on what type of message it sends you.


And in the end, what is dim?

If your input shape has only one dimension, you don't need to give it as a tuple, you give input_dim as a scalar number.

So, in your model, where your input layer has 3 elements, you can use any of these two:

  • input_shape=(3,) -- The comma is necessary when you have only one dimension
  • input_dim = 3

But when dealing directly with the tensors, often dim will refer to how many dimensions a tensor has. For instance a tensor with shape (25,10909) has 2 dimensions.

Defining your image in Keras

Keras has two ways of doing it, Sequential models, or the functional API Model. I don't like using the sequential model, later you will have to forget it anyway because you will want models with branches.

PS: here I ignored other aspects, such as activation functions.

With the Sequential model:

from keras.models import Sequential  
from keras.layers import *  

model = Sequential()    

#start from the first hidden layer, since the input is not actually a layer   
#but inform the shape of the input, with 3 elements.    
model.add(Dense(units=4,input_shape=(3,))) #hidden layer 1 with input

#further layers:    
model.add(Dense(units=4)) #hidden layer 2
model.add(Dense(units=1)) #output layer   

With the functional API Model:

from keras.models import Model   
from keras.layers import * 

#Start defining the input tensor:
inpTensor = Input((3,))   

#create the layers and pass them the input tensor to get the output tensor:    
hidden1Out = Dense(units=4)(inpTensor)    
hidden2Out = Dense(units=4)(hidden1Out)    
finalOut = Dense(units=1)(hidden2Out)   

#define the model's start and end points    
model = Model(inpTensor,finalOut)

Shapes of the tensors

Remember you ignore batch sizes when defining layers:

  • inpTensor: (None,3)
  • hidden1Out: (None,4)
  • hidden2Out: (None,4)
  • finalOut: (None,1)

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.

Making Python loggers output all messages to stdout in addition to log file

It's possible using multiple handlers.

import logging
import auxiliary_module

# create logger with 'spam_application'
log = logging.getLogger('spam_application')

# create formatter and add it to the handlers
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')

# create file handler which logs even debug messages
fh = logging.FileHandler('spam.log')

# create console handler with a higher log level
ch = logging.StreamHandler()
log.addHandler(ch)'creating an instance of auxiliary_module.Auxiliary')
a = auxiliary_module.Auxiliary()'created an instance of auxiliary_module.Auxiliary')'calling auxiliary_module.Auxiliary.do_something')
a.do_something()'finished auxiliary_module.Auxiliary.do_something')'calling auxiliary_module.some_function()')
auxiliary_module.some_function()'done with auxiliary_module.some_function()')

# remember to close the handlers
for handler in log.handlers:

Please see:

How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

if ( window.location !== window.parent.location ) 
      // The page is in an iframe   
      // The page is not in an iframe   

how to add values to an array of objects dynamically in javascript?

In Year 2019, we can use Javascript's ES6 Spread syntax to do it concisely and efficiently

data = [, {"label": 2, "value": 13}]


var data = [_x000D_
      {"label" : "1", "value" : 12},_x000D_
      {"label" : "1", "value" : 12},_x000D_
      {"label" : "1", "value" : 12},_x000D_
data = [, {"label" : "2", "value" : 14}] _x000D_

For your case (i know it was in 2011), we can do it with map() & forEach() like below

var lab = ["1","2","3","4"];_x000D_
var val = [42,55,51,22];_x000D_
//Using forEach()_x000D_
var data = [];_x000D_
val.forEach((v,i) => _x000D_
   data= [, {"label": lab[i], "value":v}]_x000D_
//Using map()_x000D_
var dataMap =,i) => _x000D_
 ({"label": lab[i], "value":v})_x000D_
console.log('data: ', data);_x000D_
console.log('dataMap : ', dataMap);

Is there a performance difference between i++ and ++i in C?

Executive summary: No.

i++ could potentially be slower than ++i, since the old value of i might need to be saved for later use, but in practice all modern compilers will optimize this away.

We can demonstrate this by looking at the code for this function, both with ++i and i++.

$ cat i++.c
extern void g(int i);
void f()
    int i;

    for (i = 0; i < 100; i++)


The files are the same, except for ++i and i++:

$ diff i++.c ++i.c
<     for (i = 0; i < 100; i++)
>     for (i = 0; i < 100; ++i)

We'll compile them, and also get the generated assembler:

$ gcc -c i++.c ++i.c
$ gcc -S i++.c ++i.c

And we can see that both the generated object and assembler files are the same.

$ md5 i++.s ++i.s
MD5 (i++.s) = 90f620dda862cd0205cd5db1f2c8c06e
MD5 (++i.s) = 90f620dda862cd0205cd5db1f2c8c06e

$ md5 *.o
MD5 (++i.o) = dd3ef1408d3a9e4287facccec53f7d22
MD5 (i++.o) = dd3ef1408d3a9e4287facccec53f7d22


The right Syntax for your query is:

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

anaconda update all possible packages?

To answer more precisely to the question:

conda (which is conda for miniconda as for Anaconda) updates all but ONLY within a specific version of a package -> major and minor. That's the paradigm.

In the documentation you will find "NOTE: Conda updates to the highest version in its series, so Python 2.7 updates to the highest available in the 2.x series and 3.6 updates to the highest available in the 3.x series." doc

If Wang does not gives a reproducible example, one can only assist. e.g. is it really the virtual environment he wants to update or could Wang get what he/she wants with

conda update -n ENVIRONMENT --all

*PLEASE read the docs before executing "update --all"! This does not lead to an update of all packages by nature. Because conda tries to resolve the relationship of dependencies between all packages in your environment, this can lead to DOWNGRADED packages without warnings.

If you only want to update almost all, you can create a pin file

echo "conda ==4.0.0" >> ~/miniconda3/envs/py35/conda-meta/pinned
echo "numpy 1.7.*" >> ~/miniconda3/envs/py35/conda-meta/pinned

before running the update. conda issues not pinned

If later on you want to ignore the file in your env for an update, you can do:

conda update --all --no-pin

You should not do update --all. If you need it nevertheless you are saver to test this in a cloned environment.

First step should always be to backup your current specification:

conda list -n py35 --explicit 

(but even so there is not always a link to the source available - like for jupyterlab extensions)

Next you can clone and update:

conda create -n py356 --clone py35

conda activate py356
conda config --set pip_interop_enabled True # for conda>=4.6
conda update --all

conda config


Because the idea of conda is nice but it is not working out very well for complex environments I personally prefer the combination of nix-shell (or lorri) and poetry [as superior pip/conda .-)] (intro poetry2nix).

Alternatively you can use nix and mach-nix (where you only need you requirements file. It resolves and builds environments best.

On Linux / macOS you could use nix like

nix-env -iA nixpkgs.python37

to enter an environment that has e.g. in this case Python3.7 (for sure you can change the version)

or as a very good Python (advanced) environment you can use mach-nix (with nix) like

mach-nix env ./env -r requirements.txt 

(which even supports conda [but currently in beta])

or via api like

nix-shell -p nixFlakes --run "nix run github:davhau/mach-nix#with.ipython.pandas.seaborn.bokeh.scikit-learn "

Finally if you really need to work with packages that are not compatible due to its dependencies, it is possible with technologies like NixOS/nix-pkgs.

jQuery Toggle Text?

Modifying my answer from your other question, I would do this:

$(function() {
 $("#show-background").click(function () {
  var c = $("#content-area");
  var o = (c.css('opacity') == 0) ? 1 : 0;
  var t = (o==1) ? 'Show Background' : 'Show Text';
  c.animate({opacity: o}, 'slow');

How to create a Custom Dialog box in android?

Dialog Fragment is the simplest way of creating a custom Alert Dialog.Follow the above code to create a custom view for your dialog and then implement it using Dialog Fragment. Add the following code to your layout file:

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

        android:text="Do you realy want to exit ?"
        android:textStyle="bold" />


            android:textStyle="bold" />

            android:textStyle="bold" />


Bootstrap 3 Glyphicons CDN

Although Bootstrap CDN restored glyphicons to bootstrap.min.css, Bootstrap CDN's Bootswatch css files doesn't include glyphicons.

For example Amelia theme:

Default Amelia has glyphicons in this file:

But Bootstrap CDN's css file doesn't include glyphicons:

So as @edsioufi mentioned, you should include you should include glphicons css, if you use Bootswatch files from the bootstrap CDN. File:

Getting current unixtimestamp using Moment.js

for UNIX time-stamp in milliseconds

moment().format('x') // lowerCase x

for UNIX time-stamp in seconds moment().format('X') // capital X

Is <div style="width: ;height: ;background: "> CSS?

For example :

<div style="height:100px; width:100px; background:#000000"></div>


you give css to div of height and width having 100px and background as black.

PS : try to avoid inline-css you can make external CSS and import in your html file.

you can refer here for CSS

hope this helps.

Uncaught TypeError: $(...).datepicker is not a function(anonymous function)

if you are using ASP.NET MVC

Open the layout file "_Layout.cshtml" or your custom one

At the part of the code you see, as below:

@RenderSection("scripts", required: false)

Remove the line "@Scripts.Render("~/bundles/jquery")"

(at the part of the code you see) past as the latest line, as below:


This help me and hope helps you as well.

How to Determine the Screen Height and Width in Flutter

The below code doesn't return the correct screen size sometimes:


I tested on SAMSUNG SM-T580, which returns {width: 685.7, height: 1097.1} instead of the real resolution 1920x1080.

Please use:

import 'dart:ui';


Use of Application.DoEvents()

I saw jheriko's comment above and was initially agreeing that I couldn't find a way to avoid using DoEvents if you end up spinning your main UI thread waiting for a long running asynchronous piece of code on another thread to complete. But from Matthias's answer a simple Refresh of a small panel on my UI can replace the DoEvents (and avoid a nasty side effect).

More detail on my case ...

I was doing the following (as suggested here) to ensure that a progress bar type splash screen (How to display a "loading" overlay...) updated during a long running SQL command:

IAsyncResult asyncResult = sqlCmd.BeginExecuteNonQuery();
while (!asyncResult.IsCompleted)  //UI thread needs to Wait for Async SQL command to return
      Application.DoEvents();  //to make the UI responsive

The bad: For me calling DoEvents meant that mouse clicks were sometimes firing on forms behind my splash screen, even if I made it TopMost.

The good/answer: Replace the DoEvents line with a simple Refresh call to a small panel in the centre of my splash screen, FormSplash.Panel1.Refresh(). The UI updates nicely and the DoEvents weirdness others have warned of was gone.

Passing null arguments to C# methods

You can use NullableValueTypes (like int?) for this. The code would be like this:

private void Example(int? arg1, int? arg2)
        //do something
        //do something else

How to support placeholder attribute in IE8 and 9

the $.Browser.msie is not on the latest JQuery anymore... you have to use the $.support

like below:


     (function ($) {
         $.support.placeholder = ('placeholder' in document.createElement('input'));

     //fix for IE7 and IE8
     $(function () {
         if (!$.support.placeholder) {
             $("[placeholder]").focus(function () {
                 if ($(this).val() == $(this).attr("placeholder")) $(this).val("");
             }).blur(function () {
                 if ($(this).val() == "") $(this).val($(this).attr("placeholder"));

             $("[placeholder]").parents("form").submit(function () {
                 $(this).find('[placeholder]').each(function() {
                     if ($(this).val() == $(this).attr("placeholder")) {

Can I export a variable to the environment from a bash script without sourcing it?

Found an interesting and neat way to export environment variables from a file:

in env.vars:


test script:

eval `cat env.vars`
echo $foo         # => test
sh -c 'echo $foo' # => 

export eval `cat env.vars`
echo $foo         # => test
sh -c 'echo $foo' # => test

# a better one. "--" stops processing options, 
# key=value list given as params
export -- `cat env.vars`
echo $foo         # => test
sh -c 'echo $foo' # => test

Importing modules from parent folder

import sys sys.path.append('../')

Hashset vs Treeset

1.HashSet allows null object.

2.TreeSet will not allow null object. If you try to add null value it will throw a NullPointerException.

3.HashSet is much faster than TreeSet.


 TreeSet<String> ts = new TreeSet<String>();
 ts.add(null); // throws NullPointerException

 HashSet<String> hs = new HashSet<String>();
 hs.add(null); // runs fine

How do I force my .NET application to run as administrator?

I implemented some code to do it manually:

using System.Security.Principal;
public bool IsUserAdministrator()
    bool isAdmin;
        WindowsIdentity user = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(user);
        isAdmin = principal.IsInRole(WindowsBuiltInRole.Administrator);
    catch (UnauthorizedAccessException ex)
        isAdmin = false;
    catch (Exception ex)
        isAdmin = false;
    return isAdmin;

Cordova app not displaying correctly on iPhone X (Simulator)

I'm developing cordova apps for 2 years and I spent weeks to solve related problems (eg: webview scrolls when keyboard open). Here's a tested and proven solution for both ios and android

P.S.: I'm using iScroll for scrolling content

  1. Never use viewport-fit=cover at index.html's meta tag, leave the app stay out of statusbar. iOS will handle proper area for all iPhone variants.
  2. In XCode uncheck hide status bar and requires full screen and don't forget to select Launch Screen File as CDVLaunchScreen
  3. In config.xml set fullscreen as false
  4. Finally, (thanks to Eddy Verbruggen for great plugins) add his plugin cordova-plugin-webviewcolor to set statusbar and bottom area background color. This plugin will allow you to set any color you want.
  5. Add below to config.xml (first ff after x is opacity)

    <preference name="BackgroundColor" value="0xff088c90" />
  6. Handle your scroll position yourself by adding focus events to input elements

    iscrollObj.scrollToElement(elm, transitionduration ... etc)

For android, do the same but instead of cordova-plugin-webviewcolor, install cordova-plugin-statusbar and cordova-plugin-navigationbar-color

Here's a javascript code using those plugins to work on both ios and android:

function setStatusColor(colorCode) {
    //colorCode is smtg like '#427309';
    if (cordova.platformId == 'android') {
    } else if (cordova.platformId == 'ios') {

The opposite of Intersect()

As stated, if you want to get 4 as the result, you can do like this:

var nonintersect = array2.Except(array1);

If you want the real non-intersection (also both 1 and 4), then this should do the trick:

var nonintersect = array1.Except(array2).Union( array2.Except(array1));

This will not be the most performant solution, but for small lists it should work just fine.

React.js: Set innerHTML vs dangerouslySetInnerHTML

Yes there is a difference!

The immediate effect of using innerHTML versus dangerouslySetInnerHTML is identical -- the DOM node will update with the injected HTML.

However, behind the scenes when you use dangerouslySetInnerHTML it lets React know that the HTML inside of that component is not something it cares about.

Because React uses a virtual DOM, when it goes to compare the diff against the actual DOM, it can straight up bypass checking the children of that node because it knows the HTML is coming from another source. So there's performance gains.

More importantly, if you simply use innerHTML, React has no way to know the DOM node has been modified. The next time the render function is called, React will overwrite the content that was manually injected with what it thinks the correct state of that DOM node should be.

Your solution to use componentDidUpdate to always ensure the content is in sync I believe would work but there might be a flash during each render.

CSS how to make scrollable list

Another solution would be as below where the list is placed under a drop-down button.

  <button class="btn dropdown-toggle btn-primary btn-sm" data-toggle="dropdown"
    >Markets<span class="caret"></span></button>

    <ul class="dropdown-menu", style="height:40%; overflow:hidden; overflow-y:scroll;">
      {{ }}

C++ style cast from unsigned char * to const char *

char * and const unsigned char * are considered unrelated types. So you want to use reinterpret_cast.

But if you were going from const unsigned char* to a non const type you'd need to use const_cast first. reinterpret_cast cannot cast away a const or volatile qualification.

Get Request and Session Parameters and Attributes from JSF pages

You can also use a tool like OcpSoft's PrettyFaces to inject dynamic parameter values directly into JSF Beans.

Convert string to datetime

This will convert the string in date to datetime, if using Rails:


Doc Reference:

"Strict Standards: Only variables should be passed by reference" error

This should be OK

   $value = explode(".", $value);
   $extension = strtolower(array_pop($value));   //Line 32
   // the file name is before the last "."
   $fileName = array_shift($value);  //Line 34

Set line height in Html <p> to make the html looks like a office word when <p> has different font sizes

You can set the line-height in pixels instead of percentage. Is that what you mean?

How long will my session last?

If session.cookie_lifetime is 0, the session cookie lives until the browser is quit.

EDIT: Others have mentioned the session.gc_maxlifetime setting. When session garbage collection occurs, the garbage collector will delete any session data that has not been accessed in longer than session.gc_maxlifetime seconds. To set the time-to-live for the session cookie, call session_set_cookie_params() or define the session.cookie_lifetime PHP setting. If this setting is greater than session.gc_maxlifetime, you should increase session.gc_maxlifetime to a value greater than or equal to the cookie lifetime to ensure that your sessions won't expire.

How do I write good/correct package files

__all__ is very good - it helps guide import statements without automatically importing modules

using __all__ and import * is redundant, only __all__ is needed

I think one of the most powerful reasons to use import * in an to import packages is to be able to refactor a script that has grown into multiple scripts without breaking an existing application. But if you're designing a package from the start. I think it's best to leave files empty.

for example: - contains classes related to foo such as fooFactory, tallFoo, shortFoo

then the app grows and now it's a whole folder


then the init script can say

__all__ = ['foofactories', 'tallFoos', 'shortfoos', 'medumfoos',
           'santaslittlehelperfoo', 'superawsomefoo', 'anotherfoo']
# deprecated to keep older scripts who import this from breaking
from foo.foofactories import fooFactory
from foo.tallfoos import tallFoo
from foo.shortfoos import shortFoo

so that a script written to do the following does not break during the change:

from foo import fooFactory, tallFoo, shortFoo

How to change the Eclipse default workspace?

You can check the option that shows up when you start eclipse. Please see the figure below

enter image description here

Static Initialization Blocks

You can execute bits of code once for a class before an object is constructed in the static blocks.


class A {
  static int var1 = 6;
  static int var2 = 9;
  static int var3;
  static long var4;

  static Date date1;
  static Date date2;

  static {
    date1 = new Date();

    for(int cnt = 0; cnt < var2; cnt++){
      var3 += var1;

    System.out.println("End first static init: " + new Date());

Chrome hangs after certain amount of data transfered - waiting for available socket

simple and correct solution is put off preload your audio and video file from setting and recheck your page your problem of waiting for available socket will resolved ...

if you use jplayer then replace preload:"metadata" to preload:"none" from jplayer JS file ...

preload:"metadata" is the default value which play your audio/video file on page load thats why google chrome showing "waiting for available socket" error

In laymans terms, what does 'static' mean in Java?

static means that the variable or method marked as such is available at the class level. In other words, you don't need to create an instance of the class to access it.

public class Foo {
    public static void doStuff(){
        // does stuff

So, instead of creating an instance of Foo and then calling doStuff like this:

Foo f = new Foo();

You just call the method directly against the class, like so:


TypeScript Objects as Dictionary types as in C#

In newer versions of typescript you can use:

type Customers = Record<string, Customer>

In older versions you can use:

var map: { [email: string]: Customer; } = { };
map['[email protected]'] = new Customer(); // OK
map[14] = new Customer(); // Not OK, 14 is not a string
map['[email protected]'] = 'x'; // Not OK, 'x' is not a customer

You can also make an interface if you don't want to type that whole type annotation out every time:

interface StringToCustomerMap {
    [email: string]: Customer;

var map: StringToCustomerMap = { };
// Equivalent to first line of above

How to run TypeScript files from command line?

To add to @Aamod answer above, If you want to use one command line to compile and run your code, you can use the following:


tsc main.ts | node main.js

Linux / macOS:

tsc main.ts && node main.js

iPhone 6 Plus resolution confusion: Xcode or Apple's website? for development

On the physical device, iPhone 6 Plus's main screen's bounds is 2208x1242 and nativeBounds is 1920x1080. There is hardware scaling involved to resize to the physical display.

On the simulator, the iPhone 6 Plus's main screen's bounds and nativeBounds are both 2208x1242.

In other words... Videos, OpenGL, and other things based on CALayers that deal with pixels will deal with the real 1920x1080 frame buffer on device (or 2208x1242 on sim). Things dealing with points in UIKit will be deal with the 2208x1242 (x3) bounds and get scaled as appropriate on device.

The simulator does not have access to the same hardware that is doing the scaling on device and there's not really much of a benefit to simulating it in software as they'd produce different results than the hardware. Thus it makes sense to set the nativeBounds of a simulated device's main screen to the bounds of the physical device's main screen.

iOS 8 added API to UIScreen (nativeScale and nativeBounds) to let a developer determine the resolution of the CADisplay corresponding to the UIScreen.

Swift - iOS - Dates and times in different format

Time Picker In swift

class ViewController: UIViewController {
    @IBOutlet weak var lblTime: UILabel!
    @IBOutlet weak var timePicker: UIDatePicker!
    @IBOutlet weak var cancelTime_Btn: UIBarButtonItem!
    @IBOutlet weak var donetime_Btn: UIBarButtonItem!
    @IBOutlet weak var toolBar: UIToolbar!
    //Date picker
//    @IBOutlet weak var datePicker: UIDatePicker!
    override func viewDidLoad() {
        ishidden(bool: true)
        let dateFormatter2 = DateFormatter()
        dateFormatter2.dateFormat = "HH:mm a" //"hh:mm a"
        lblTime.text = dateFormatter2.string(from:
    @IBAction func selectTime_Action(_ sender: Any) {
        timePicker.datePickerMode = .time
        ishidden(bool: false)
    @IBAction func timeCancel_Action(_ sender: Any) {
        ishidden(bool: true)
    @IBAction func timeDoneBtn(_ sender: Any) {
        let dateFormatter1 = DateFormatter()
        dateFormatter1.dateFormat =  "HH:mm a"//"hh:mm"
        let str = dateFormatter1.string(from:
        lblTime.text = str
        ishidden(bool: true)
    func ishidden(bool:Bool){
           timePicker.isHidden = bool
           toolBar.isHidden = bool

How can I generate an apk that can run without server with react-native?

Try below, it will generate an app-debug.apk on your root/android/app/build/outputs/apk/debug folder

react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/ --assets-dest android/app/src/main/res

then go to android folder and run

./gradlew assembleDebug

Show all current locks from get_lock

Reference taken from this post:

You can also use this script to find lock in MySQL.

    ,it.trx_query AS query
    ,it.trx_id AS blocking_trx_id
    ,it.trx_mysql_thread_id AS blocking_thread
    ,it.trx_query AS blocking_query
FROM information_schema.processlist AS pl 
INNER JOIN information_schema.innodb_trx AS it
    ON = it.trx_mysql_thread_id
INNER JOIN information_schema.innodb_lock_waits AS ilw
    ON it.trx_id = ilw.requesting_trx_id 
        AND it.trx_id = ilw.blocking_trx_id

How can I echo HTML in PHP?

Simply use the print function to echo text in the PHP file as follows:


    <div class="wrap">

      <span class="textClass">TESTING</span>


How to select an item in a ListView programmatically?

        int i=99;//is what row you want to select and focus
        listViewRamos.FocusedItem = listViewRamos.Items[0];
        listViewRamos.Items[i].Selected = true;
        listViewRamos.EnsureVisible(i);//This is the trick

AngularJS ng-click to go to another page (with Ionic framework)

Based on comments, and due to the fact that @Thinkerer (the OP - original poster) created a plunker for this case, I decided to append another answer with more details.

The first and important change:

// instead of this

// we have to use this

because the states definition is:

.state('tab', {
  url: "/tab",
  abstract: true,
  templateUrl: 'tabs.html'

.state('tab.posts', {
  url: '/posts',
  views: {
    'tab-posts': {
      templateUrl: 'tab-posts.html',
      controller: 'PostsCtrl'

and we need their concatenated url '/tab' + '/posts'. That's the url we want to use as a otherwise

The rest of the application is really close to the result we need...
E.g. we stil have to place the content into same view targetgood, just these were changed:

.state('tab.newpost', {
  url: '/newpost',
  views: {
    // 'tab-newpost': {
    'tab-posts': {
      templateUrl: 'tab-newpost.html',
      controller: 'NavCtrl'

because .state('tab.newpost' would be replacing the .state('tab.posts' we have to place it into the same anchor:

<ion-nav-view name="tab-posts"></ion-nav-view>  

Finally some adjustments in controllers:

$scope.create = function() {
$scope.close = function() { 

As I already said in my previous answer and comments ... the $state.go() is the only right way how to use ionic or ui-router

Check that all here Final note - I made running just navigation between tab.posts... tab.newpost... the rest would be similar

Is there any way to delete local commits in Mercurial?

[Hg Tortoise 4.6.1] If it's recent action, you can use "Rollback/Undo" action (Ctrl+U).

HG Tortoise Image

Android Starting Service at Boot Time , How to restart service class after device Reboot?

To Restart service in Android O or more ie OS >28 Use this code KOTLIN VERSION 1) Add permission in manifest

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

2) Create a Class and extend it with BroadcastReceiver

import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.os.Build
import android.util.Log
import androidx.core.content.ContextCompat

class BootCompletedReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, arg1: Intent?) {
        Log.d("BootCompletedReceiver", "starting service...")
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            ContextCompat.startForegroundService(context, Intent(context,
        } else {

3) Declare in Manifest file like this under application tag

<receiver android:name=".utils.BootCompletedReceiver" >
            <action android:name="android.intent.action.BOOT_COMPLETED" />
            <action android:name="android.intent.action.QUICKBOOT_POWERON" />

A fast way to delete all rows of a datatable at once

Here we have same question. You can use the following code:

SqlConnection con = new SqlConnection();
con.ConnectionString = ConfigurationManager.ConnectionStrings["yourconnectionstringnamehere"].ConnectionString;
SqlCommand com = new SqlCommand();
com.Connection = con;
com.CommandText = "DELETE FROM [tablenamehere]";
SqlDataReader data = com.ExecuteReader();

But before you need to import following code to your project:

using System.Configuration;
using System.Data.SqlClient;

This is the specific part of the code that can delete all rows is a table:

DELETE FROM [tablenamehere]

This must be your table name:tablenamehere - This can delete all rows in table: DELETE FROM

Check if an apt-get package is installed and then install it if it's not on Linux

This feature already exists in Ubuntu and Debian, in the command-not-found package.

jQuery get the name of a select option


means the name of the select tag not option name.

To get option name

 $("#band_type_choices option:selected").attr('name');

How do you take a git diff file, and apply it to a local branch that is a copy of the same repository?

It seems like you can also use the patch command. Put the diff in the root of the repository and run patch from the command line.

patch -i yourcoworkers.diff


patch -p0 -i yourcoworkers.diff

You may need to remove the leading folder structure if they created the diff without using --no-prefix.

If so, then you can remove the parts of the folder that don't apply using:

patch -p1 -i yourcoworkers.diff

The -p(n) signifies how many parts of the folder structure to remove.

More information on creating and applying patches here.

You can also use

git apply yourcoworkers.diff --stat 

to see if the diff by default will apply any changes. It may say 0 files affected if the patch is not applied correctly (different folder structure).

MVC 5 Access Claims Identity User Data

shortest and simplified version of @Rosdi Kasim'd answer is

string claimvalue = ((System.Security.Claims.ClaimsIdentity)User.Identity).

Claimname is the claim you want to retrieve i.e if you are looking for "StreedAddress" claim then the above answer will be like this

string claimvalue = ((System.Security.Claims.ClaimsIdentity)User.Identity).

Bootstrap 4 datapicker.js not included

Most of bootstrap datepickers as I write this answer are rather buggy when included in Bootstrap 4. In my view the least code adding solution is a jQuery plugin. I used this one - you can see its usage here: It sure is not as smooth as the whole BS interface, but it only requires its css and js files along with jQuery which is already included in bootstrap.

HTML table with 100% width, with vertical scroll inside tbody


for Chrome, Firefox, Edge (and other evergreen browsers)

Simply position: sticky; top: 0; your th elements:

/* Fix table head */
.tableFixHead    { overflow-y: auto; height: 100px; }
.tableFixHead th { position: sticky; top: 0; }

/* Just common table stuff. */
table  { border-collapse: collapse; width: 100%; }
th, td { padding: 8px 16px; }
th     { background:#eee; }
<div class="tableFixHead">
      <tr><th>TH 1</th><th>TH 2</th></tr>

PS: if you need borders for TH elements th {box-shadow: 1px 1px 0 #000; border-top: 0;} will help (since the default borders are not painted correctly on scroll).

For a variant of the above that uses just a bit of JS in order to accommodate for IE11 see this answer Table fixed header and scrollable body

ip address validation in python using regex

\d{1,3} will match numbers like 00 or 333 as well which wouldn't be a valid ID.

This is an excellent answer from smink, citing:

ValidIpAddressRegex = "^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$";

How does one target IE7 and IE8 with valid CSS?

The answer to your question

A completely valid way to select all browsers but IE8 and below is using the :root selector. Since IE versions 8 and below do not support :root, selectors containing it are ignored. This means you could do something like this:

p {color:red;}
:root p {color:blue;}

This is still completely valid CSS, but it does cause IE8 and lower to render different styles.

Other tricks

Here's a list of all completely valid CSS browser-specific selectors I could find, except for some that seem quite redundant, such as ones that select for just 1 type of ancient browser (1, 2):

/******  First the hacks that target certain specific browsers  ******/
* html p                        {color:red;} /* IE 6- */
*+html p                        {color:red;} /* IE 7 only */
@media screen and (-webkit-min-device-pixel-ratio:0) {
    p                           {color:red;}
}                                            /* Chrome, Safari 3+ */
p, body:-moz-any-link           {color:red;} /* Firefox 1+ */
:-webkit-any(html) p            {color:red;} /* Chrome 12+, Safari 5.1.3+ */
:-moz-any(html) p               {color:red;} /* Firefox 4+ */

/****** And then the hacks that target all but certain browsers ******/
html> body p                  {color:green;} /* not: IE<7 */
head~body p                   {color:green;} /* not: IE<7, Opera<9, Safari<3 */
html:first-child p            {color:green;} /* not: IE<7, Opera<9.5, Safari&Chrome<4, FF<3 */
html>/**/body p               {color:green;} /* not: IE<8 */
body:first-of-type p          {color:green;} /* not: IE<9, Opera<9, Safari<3, FF<3.5 */
:not([ie8min]) p              {color:green;} /* not: IE<9, Opera<9.5, Safari<3.2 */
body:not([oldbrowser]) p      {color:green;} /* not: IE<9, Opera<9.5, Safari<3.2 */

Credits & sources:

Get content uri from file path in android

Its late, but may help someone in future.

To get content URI for a file, you may use the following method:

FileProvider.getUriForFile(Context context, String authority, File file)

It returns the content URI.

Check this out to learn how to setup a FileProvider

Team Build Error: The Path ... is already mapped to workspace

I had this issue with this with Azure DevOps automated builds in an on-prem TFS build agent. Removing the workspace using TFS Sidekicks did not work. And tf.exe could not even find the workspace to delete it.

This solution should work for TFS 2017, TFS 2018, Azure DevOps, and possibly other versions:

  1. Take note of the workspace GUID in the error message.
  2. On the machine where the build is taking place, navigate to: %USERPROFILE%\AppData\Local\Microsoft\Team Foundation\ (where %USERPROFILE% belongs to the user that triggered the build).
  3. Search for and remove all instances of the workspace GUID under that directory. There will likely be a folder in a 'cache' directory, as well as entries in 'LocationServerMap.xml' and 'LocalItemExclusions.config'. Remove them all.

That worked in my circumstance.

format a Date column in a Data Frame

The data.table package has its IDate class and functionalities similar to lubridate or the zoo package. You could do:

dt = data.table(
  Name = c('Joe', 'Amy', 'John'),
  JoiningDate = c('12/31/09', '10/28/09', '05/06/10'),
  AmtPaid = c(1000, 100, 200)

dt[ , JoiningDate := as.IDate(JoiningDate, '%m/%d/%y') ]

Is there a way to use PhantomJS in Python?

If using Anaconda, install with:

conda install PhantomJS

in your script:

from selenium import webdriver

works perfectly.

What does 'public static void' mean in Java?

  • public means you can access the class from anywhere in the class/object or outside of the package or class
  • static means constant in which block of statement used only 1 time
  • void means no return type

Strip double quotes from a string in .NET

s = s.Replace("\"", "");

You need to use the \ to escape the double quote character in a string.