Programs & Examples On #Unhandled exception

An unhandled exception is an Exception that is thrown by execution but is never caught by the program, which results in a Exception Stack.

Java 8: How do I work with exception throwing methods in streams?

I suggest to use Google Guava Throwables class

propagate(Throwable throwable)

Propagates throwable as-is if it is an instance of RuntimeException or Error, or else as a last resort, wraps it in a RuntimeException and then propagates.**

void bar() {
    Stream<A> as = ...
    as.forEach(a -> {
        try {
        } catch(Exception e) {
            throw Throwables.propagate(e);


Now that it is deprecated use:

void bar() {
    Stream<A> as = ...
    as.forEach(a -> {
        try {
        } catch(Exception e) {
            throw new RuntimeException(e);

What is an unhandled promise rejection?

In my case was Promise with no reject neither resolve, because my Promise function threw an exception. This mistake cause UnhandledPromiseRejectionWarning message.

Why is "throws Exception" necessary when calling a function?

Basically, if you are not handling the exception in the same place as you are throwing it, then you can use "throws exception" at the definition of the function.

React Native: Getting the position of an element

If you use function components and don't want to use a forwardRef to measure your component's absolute layout, you can get a reference to it from the LayoutChangeEvent in the onLayout callback.

This way, you can get the absolute position of the element:

  onLayout={(event) => {
      (x, y, width, height, pageX, pageX) => {
          x: x + pageX, 
          y: y + pageY,

Tested with React Native 0.63.3.

Iterate through 2 dimensional array

Consider it as an array of arrays and this will work for sure.

int mat[][] = { {10, 20, 30, 40, 50, 60, 70, 80, 90},
                {15, 25, 35, 45},
                {27, 29, 37, 48},
                {32, 33, 39, 50, 51, 89},

    for(int i=0; i<mat.length; i++) {
        for(int j=0; j<mat[i].length; j++) {
            System.out.println("Values at arr["+i+"]["+j+"] is "+mat[i][j]);

custom facebook share button

You can simply do something like...

  window.fbAsyncInit = function() {
      appId            : 'your-app-id', // you need to create an facebook app
      autoLogAppEvents : true,
      xfbml            : true,
      version          : 'v3.3'
<script async defer src=""></script>
<button id="share-btn"></button>
<!-- load jquery -->
    $('#share-btn').on('click', function () {
            method: 'share',
            href: location.href, // Current url
        }, function (response) { });

How to resolve Unneccessary Stubbing exception

At first you should check your test logic. Usually there are 3 cases. First, you are mocking wrong method (you made a typo or someone changed tested code so that mocked method is no longer used). Second, your test is failing before this method is called. Third, you logic falls in wrong if/switch branch somewhere in the code so that mocked method is no called.

If this is first case you always want to change mocked method for the one used in the code. With second and the third it depends. Usually you should just delete this mock if it has no use. But sometimes there are certain cases in parametrized tests, which should take this different path or fail earlier. Then you can split this test into two or more separate ones but that's not always good looking. 3 test methods with possibly 3 arguments providers can make you test look unreadable. In that case for JUnit 4 you silent this exception with either


annotation or if you are using rule approach

public MockitoRule rule = MockitoJUnit.rule().strictness(Strictness.LENIENT);

or (the same behaviour)

public MockitoRule rule = MockitoJUnit.rule().silent();

For JUnit 5 tests you can silent this exception using annotation provided in mockito-junit-jupiter package.

@MockitoSettings(strictness = Strictness.LENIENT)
class JUnit5MockitoTest {

"RuntimeError: Make sure the Graphviz executables are on your system's path" after installing Graphviz 2.38

1.install windows package from: and download msi file

Add in Environmental variables 2. Add C:\Program Files (x86)\Graphviz2.38\bin to User path

  1. Add C:\Program Files (x86)\Graphviz2.38\bin\dot.exe to System Path

  2. Restart your python notebook.

It will work.

What is the right way to POST multipart/form-data using curl?

The following syntax fixes it for you:

curl -v -F key1=value1 -F upload=@localfilename URL

URL to load resources from the classpath in Java

If you have tomcat on the classpath, it's as simple as:


This will register handlers for "war" and "classpath" protocols.

Minimum 6 characters regex expression

Something along the lines of this?

<asp:TextBox id="txtUsername" runat="server" />

    ErrorMessage="Field not valid!"
    ValidationExpression="[0-9a-zA-Z]{6,}" />

How do I use MySQL through XAMPP?

Changing XAMPP Default Port: If you want to get XAMPP up and running, you should consider changing the port from the default 80 to say 7777.

  • In the XAMPP Control Panel, click on the Apache – Config button which is located next to the ‘Logs’ button.

  • Select ‘Apache (httpd.conf)’ from the drop down. (Notepad should open)

  • Do Ctrl+F to find ’80’ and change line Listen 80 to Listen 7777

  • Find again and change line ServerName localhost:80 to ServerName localhost:7777

  • Save and re-start Apache. It should be running by now.

The only demerit to this technique is, you have to explicitly include the port number in the localhost url. Rather than http://localhost it becomes http://localhost:7777.

How can I set a cookie in react?

By default, when you fetch your URL, React native sets the cookie.

To see cookies and make sure that you can use the package. I used to be very satisfied with it.

Of course, Fetch does this when it does

credentials: "include",// or "some-origin"

Well, but how to use it

--- after installation this package ----

to get cookies:

import Cookie from 'react-native-cookie';

Cookie.get('url').then((cookie) => {

to set cookies:

Cookie.set('url', 'name of cookies', 'value  of cookies');

only this

But if you want a few, you can do it

1- as nested:

Cookie.set('url', 'name of cookies 1', 'value  of cookies 1')
        .then(() => {
            Cookie.set('url', 'name of cookies 2', 'value  of cookies 2')
            .then(() => {

2- as back together

Cookie.set('url', 'name of cookies 1', 'value  of cookies 1');
Cookie.set('url', 'name of cookies 2', 'value  of cookies 2');
Cookie.set('url', 'name of cookies 3', 'value  of cookies 3');

Now, if you want to make sure the cookies are set up, you can get it again to make sure.

Cookie.get('url').then((cookie) => {

Print Pdf in C#

You can create the PDF document using PdfSharp. It is an open source .NET library.

When trying to print the document it get worse. I have looked allover for a open source way of doing it. There are some ways do do it using AcroRd32.exe but it all depends on the version, and it cannot be done without acrobat reader staying open.

I finally ended up using VintaSoftImaging.NET SDK. It costs some money but is much cheaper than the alternative and it solves the problem really easy.

var doc = new Vintasoft.Imaging.Print.ImagePrintDocument { DocumentName = @"C:\Test.pdf" };

That just prints to the default printer without showing. There are several alternatives and options.

How to edit Docker container files from the host?

There are two ways to mount files into your container. It looks like you want a bind mount.

Bind Mounts

This mounts local files directly into the container's filesystem. The containerside path and the hostside path both point to the same file. Edits made from either side will show up on both sides.

  • mount the file:
? echo foo > ./foo
? docker run --mount type=bind,source=$(pwd)/foo,target=/foo -it debian:latest
# cat /foo
foo # local file shows up in container
  • in a separate shell, edit the file:
? echo 'bar' > ./foo # make a hostside change
  • back in the container:
# cat /foo
bar # the hostside change shows up
# echo baz > /foo # make a containerside change
# exit
? cat foo
baz # the containerside change shows up

Volume Mounts

  • mount the volume
? docker run --mount type=volume,source=foovolume,target=/foo  -it debian:latest
root@containerB# echo 'this is in a volume' > /foo/data
  • the local filesystem is unchanged
  • docker sees a new volume:
? docker volume ls
local     foovolume
  • create a new container with the same volume
? docker run --mount type=volume,source=foovolume,target=/foo  -it debian:latest
root@containerC:/# cat /foo/data
this is in a volume # data is still available

syntax: -v vs --mount

These do the same thing. -v is more concise, --mount is more explicit.

bind mounts

-v /hostside/path:/containerside/path
--mount type=bind,source=/hostside/path,target=/containerside/path

volume mounts

-v /containerside/path
-v volumename:/containerside/path
--mount type=volume,source=volumename,target=/containerside/path

(If a volume name is not specified, a random one is chosen.)

The documentaion tries to convince you to use one thing in favor of another instead of just telling you how it works, which is confusing.

Why won't eclipse switch the compiler to Java 8?

Two things:

First, JRE is not the same as the JDK. If you do have the JDK, you need to configure eclipse to point to that in your settings.

Second, in your screenshot above, your compiler compliance level is set to 1.7. This will treat all your code as if it's using Java 1.7. Change this to 1.8 to fix your error.

You will need to have Eclipse Luna in order to get support for Java 8, but you can add it to Kepler SR2 if you want. I'd try with Luna and the above suggestions before you go any further. See this reference.

Once you get Luna, your JAVA_HOME variable should be enough to get Eclipse to recognize JDK 8. If you want to specify an additional JDK, you can add a new Java System Library by going to:

Project -> Properties -> Java Build Path -> Libraries -> Add Library -> Java System Library

and navigating to a valid location for the JDK 8.

You can download your platform's JDK 8 here

How can I clone a JavaScript object except for one key?

For those who can't use ES6, you can use lodash or underscore.

_.omit(x, 'b')

Or ramda.

R.omit('b', x)

Mockito match any class argument

the solution from millhouse is not working anymore with recent version of mockito

This solution work with java 8 and mockito 2.2.9

where ArgumentMatcher is an instanceof org.mockito.ArgumentMatcher

public class ClassOrSubclassMatcher<T> implements ArgumentMatcher<Class<T>> {

   private final Class<T> targetClass;

    public ClassOrSubclassMatcher(Class<T> targetClass) {
        this.targetClass = targetClass;

    public boolean matches(Class<T> obj) {
        if (obj != null) {
            if (obj instanceof Class) {
                return targetClass.isAssignableFrom( obj);
        return false;

And the use

when(a.method(ArgumentMatchers.argThat(new ClassOrSubclassMatcher<>(A.class)))).thenReturn(b);

Radio/checkbox alignment in HTML/CSS

This is a bit of a hack but this CSS seems to get it working very nicely in all browsers the same as using tables (apart from chrome)

input[type=radio] { vertical-align: middle; margin: 0; *margin-top: -2px; }
label { vertical-align: middle; }
@media screen and (-webkit-min-device-pixel-ratio:0) {
 input[type=radio] { margin-top: -2px; }

Make sure you use labels with your radios for it to work. i.e.

<option> <label>My Radio</label>

Ajax success event not working

Put an alert() in your success callback to make sure it's being called at all.

If it's not, that's simply because the request wasn't successful at all, even though you manage to hit the server. Reasonable causes could be that a timeout expires, or something in your php code throws an exception.

Install the firebug addon for firefox, if you haven't already, and inspect the AJAX callback. You'll be able to see the response, and whether or not it receives a successful (200 OK) response. You can also put another alert() in the complete callback, which should definitely be invoked.

How to remove and clear all localStorage data

It only worked for me in Firefox when accessing it from the window object.


window.onload = function()

Converting string into datetime

datetime.strptime is the main routine for parsing strings into datetimes. It can handle all sorts of formats, with the format determined by a format string you give it:

from datetime import datetime

datetime_object = datetime.strptime('Jun 1 2005  1:33PM', '%b %d %Y %I:%M%p')

The resulting datetime object is timezone-naive.



  • strptime = "string parse time"
  • strftime = "string format time"
  • Pronounce it out loud today & you won't have to search for it again in 6 months.

How to clear PermGen space Error in tomcat

If your using eclipse with tomcat follow the below steps

  1. On server window Double click on tomcat, It will open the tomcat's Overview window .

  2. In the Overview window you will find Open launch configuration under General information and click on Open launch configuration.

  3. In the edit Configuration window look for Arguments and click on It.
  4. In the arguments tag look for VM arguments.
  5. simply paste this -Xms256m -Xmx512m -XX:PermSize=256m -XX:MaxPermSize=512m to the end of the arguments.

edit launch configuration properties

No suitable driver found for 'jdbc:mysql://localhost:3306/mysql

This error happened to me, generally it'll be a problem due to not including the mysql-connector.jar in your eclipse project (or your IDE).

In my case, it was because of a problem on the OS.

I was editing a table in phpmyadmin, and mysql hung, I restarted Ubuntu. I cleaned the project without being successful. This morning, when I've tried the web server, it work perfectly the first time.

At the first reboot, the OS recognized that there was a problem, and after the second one, it was fixed. I hope this will save some time to somebody that "could" have this problem!

Should I use past or present tense in git commit messages?

I wrote a fuller description on 365git.

The use of the imperative, present tense is one that takes a little getting used to. When I started mentioning it, it was met with resistance. Usually along the lines of “The commit message records what I have done”. But, Git is a distributed version control system where there are potentially many places to get changes from. Rather than writing messages that say what you’ve done; consider these messages as the instructions for what applying the commit will do. Rather than having a commit with the title:

Renamed the iVars and removed the common prefix.

Have one like this:

Rename the iVars to remove the common prefix

Which tells someone what applying the commit will do, rather than what you did. Also, if you look at your repository history you will see that the Git generated messages are written in this tense as well - “Merge” not “Merged”, “Rebase” not “Rebased” so writing in the same tense keeps things consistent. It feels strange at first but it does make sense (testimonials available upon application) and eventually becomes natural.

Having said all that - it’s your code, your repository: so set up your own guidelines and stick to them.

If, however, you do decide to go this way then git rebase -i with the reword option would be a good thing to look into.

Using jQuery how to get click coordinates on the target element

In percentage :

$('.your-class').click(function (e){
    var $this = $(this); // or use $( in some cases;
    var offset = $this.offset();
    var width = $this.width();
    var height = $this.height();
    var posX = offset.left;
    var posY =;
    var x = e.pageX-posX;
        x = parseInt(x/width*100,10);
        x = x<0?0:x;
        x = x>100?100:x;
    var y = e.pageY-posY;
        y = parseInt(y/height*100,10);
        y = y<0?0:y;
        y = y>100?100:y;
    console.log(x+'% '+y+'%');

String split on new line, tab and some number of spaces

Just use .strip(), it removes all whitespace for you, including tabs and newlines, while splitting. The splitting itself can then be done with data_string.splitlines():

[s.strip() for s in data_string.splitlines()]


>>> [s.strip() for s in data_string.splitlines()]
['Name: John Smith', 'Home: Anytown USA', 'Phone: 555-555-555', 'Other Home: Somewhere Else', 'Notes: Other data', 'Name: Jane Smith', 'Misc: Data with spaces']

You can even inline the splitting on : as well now:

>>> [s.strip().split(': ') for s in data_string.splitlines()]
[['Name', 'John Smith'], ['Home', 'Anytown USA'], ['Phone', '555-555-555'], ['Other Home', 'Somewhere Else'], ['Notes', 'Other data'], ['Name', 'Jane Smith'], ['Misc', 'Data with spaces']]

Go install fails with error: no install location for directory xxx outside GOPATH

You need to setup both GOPATH and GOBIN. Make sure you have done the following (please replace ~/go with your preferred GOPATH and subsequently change GOBIN). This is tested on Ubuntu 16.04 LTS.

export GOPATH=~/go 

mkdir ~/go/bin

export GOBIN=$GOPATH/bin

The selected answer did not solve the problem for me.

How can I read a text file in Android?

Try this code

public static String pathRoot = "/sdcard/system/temp/";
public static String readFromFile(Context contect, String nameFile) {
    String aBuffer = "";
    try {
        File myFile = new File(pathRoot + nameFile);
        FileInputStream fIn = new FileInputStream(myFile);
        BufferedReader myReader = new BufferedReader(new InputStreamReader(fIn));
        String aDataRow = "";
        while ((aDataRow = myReader.readLine()) != null) {
            aBuffer += aDataRow;
    } catch (FileNotFoundException e) {
    } catch (IOException e) {
    return aBuffer;

Android: Scale a Drawable or background image?

The Below code make the bitmap perfectly with same size of the imageview. Get the bitmap image height and width and then calculate the new height and width with the help of imageview's parameters. That give you required image with best aspect ratio.

int bwidth=bitMap1.getWidth();
int bheight=bitMap1.getHeight();
int swidth=imageView_location.getWidth();
int sheight=imageView_location.getHeight();
new_height = (int) Math.floor((double) bheight *( (double) new_width / (double) bwidth));
Bitmap newbitMap = Bitmap.createScaledBitmap(bitMap1,new_width,new_height, true);

How do I analyze a program's core dump file with GDB when it has command-line parameters?

objdump + gdb minimal runnable example


Now for the full educational test setup:


#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int myfunc(int i) {
    *(int*)(NULL) = i; /* line 7 */
    return i - 1;

int main(int argc, char **argv) {
    /* Setup some memory. */
    char data_ptr[] = "string in data segment";
    char *mmap_ptr;
    char *text_ptr = "string in text segment";
    mmap_ptr = (char *)malloc(sizeof(data_ptr) + 1);
    strcpy(mmap_ptr, data_ptr);
    mmap_ptr[10] = 'm';
    mmap_ptr[11] = 'm';
    mmap_ptr[12] = 'a';
    mmap_ptr[13] = 'p';
    printf("text addr: %p\n", text_ptr);
    printf("data addr: %p\n", data_ptr);
    printf("mmap addr: %p\n", mmap_ptr);

    /* Call a function to prepare a stack trace. */
    return myfunc(argc);

Compile, and run to generate core:

gcc -ggdb3 -std=c99 -Wall -Wextra -pedantic -o main.out main.c
ulimit -c unlimited
rm -f core


text addr: 0x4007d4
data addr: 0x7ffec6739220
mmap addr: 0x1612010
Segmentation fault (core dumped)

GDB points us to the exact line where the segmentation fault happened, which is what most users want while debugging:

gdb -q -nh main.out core


Reading symbols from main.out...done.
[New LWP 27479]
Core was generated by `./main.out'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000400635 in myfunc (i=1) at main.c:7
7           *(int*)(NULL) = i;
(gdb) bt
#0  0x0000000000400635 in myfunc (i=1) at main.c:7
#1  0x000000000040072b in main (argc=1, argv=0x7ffec6739328) at main.c:28

which points us directly to the buggy line 7.

CLI arguments are stored in the core file and don't need to be passed again

To answer the specific CLI argument questions, we see that if we change the cli arguments e.g. with:

rm -f core
./main.out 1 2

then this does get reflected in the previous bactrace without any changes in our commands:

Reading symbols from main.out...done.
[New LWP 21838]
Core was generated by `./main.out 1 2'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000564583cf2759 in myfunc (i=3) at main.c:7
7           *(int*)(NULL) = i; /* line 7 */
(gdb) bt
#0  0x0000564583cf2759 in myfunc (i=3) at main.c:7
#1  0x0000564583cf2858 in main (argc=3, argv=0x7ffcca4effa8) at main.c:2

So note how now argc=3. Therefore this must mean that the core file stores that information. I'm guessing it just stores it as the arguments of main, just like it stores the arguments of any other functions.

This makes sense if you consider that the core dump must be storing the entire memory and register state of the program, and so it has all the information needed to determine the value of function arguments on the current stack.

Less obvious is how to inspect the environment variables: How to get environment variable from a core dump Environment variables are also present in memory so the objdump does contain that information, but I'm not sure how to list all of them in one go conveniently, one by one as follows did work on my tests though:

p __environ[0]

Binutils analysis

By using binutils tools like readelf and objdump, we can bulk dump information contained in the core file such as the memory state.

Most/all of it must also be visible through GDB, but those binutils tools offer a more bulk approach which is convenient for certain use cases, while GDB is more convenient for a more interactive exploration.


file core

tells us that the core file is actually an ELF file:

core: ELF 64-bit LSB core file x86-64, version 1 (SYSV), SVR4-style, from './main.out'

which is why we are able to inspect it more directly with usual binutils tools.

A quick look at the ELF standard shows that there is actually an ELF type dedicated to it:

Elf32_Ehd.e_type == ET_CORE

Further format information can be found at:

man 5 core


readelf -Wa core

gives some hints about the file structure. Memory appears to be contained in regular program headers:

Program Headers:
  Type           Offset   VirtAddr           PhysAddr           FileSiz  MemSiz   Flg Align
  NOTE           0x000468 0x0000000000000000 0x0000000000000000 0x000b9c 0x000000     0
  LOAD           0x002000 0x0000000000400000 0x0000000000000000 0x001000 0x001000 R E 0x1000
  LOAD           0x003000 0x0000000000600000 0x0000000000000000 0x001000 0x001000 R   0x1000
  LOAD           0x004000 0x0000000000601000 0x0000000000000000 0x001000 0x001000 RW  0x1000

and there is some more metadata present in a notes area, notably prstatus contains the PC:

Displaying notes found at file offset 0x00000468 with length 0x00000b9c:
  Owner                 Data size       Description
  CORE                 0x00000150       NT_PRSTATUS (prstatus structure)
  CORE                 0x00000088       NT_PRPSINFO (prpsinfo structure)
  CORE                 0x00000080       NT_SIGINFO (siginfo_t data)
  CORE                 0x00000130       NT_AUXV (auxiliary vector)
  CORE                 0x00000246       NT_FILE (mapped files)
    Page size: 4096
                 Start                 End         Page Offset
    0x0000000000400000  0x0000000000401000  0x0000000000000000
    0x0000000000600000  0x0000000000601000  0x0000000000000000
    0x0000000000601000  0x0000000000602000  0x0000000000000001
    0x00007f8d939ee000  0x00007f8d93bae000  0x0000000000000000
    0x00007f8d93bae000  0x00007f8d93dae000  0x00000000000001c0
    0x00007f8d93dae000  0x00007f8d93db2000  0x00000000000001c0
    0x00007f8d93db2000  0x00007f8d93db4000  0x00000000000001c4
    0x00007f8d93db8000  0x00007f8d93dde000  0x0000000000000000
    0x00007f8d93fdd000  0x00007f8d93fde000  0x0000000000000025
    0x00007f8d93fde000  0x00007f8d93fdf000  0x0000000000000026
  CORE                 0x00000200       NT_FPREGSET (floating point registers)
  LINUX                0x00000340       NT_X86_XSTATE (x86 XSAVE extended state)

objdump can easily dump all memory with:

objdump -s core

which contains:

Contents of section load1:

 4007d0 01000200 73747269 6e672069 6e207465  ....string in te
 4007e0 78742073 65676d65 6e740074 65787420  xt segment.text 

Contents of section load15:

 7ffec6739220 73747269 6e672069 6e206461 74612073  string in data s
 7ffec6739230 65676d65 6e740000 00a8677b 9c6778cd  egment....g{.gx.

Contents of section load4:

 1612010 73747269 6e672069 6e206d6d 61702073  string in mmap s
 1612020 65676d65 6e740000 11040000 00000000  egment..........

which matches exactly with the stdout value in our run.

This was tested on Ubuntu 16.04 amd64, GCC 6.4.0, and binutils 2.26.1.

Strange problem with Subversion - "File already exists" when trying to recreate a directory that USED to be in my repository

What you need is the svn 'export' command. With this you can put a file or entire directory tree in the state of another revision in another branch.

So something like

rm file #without 'svn' in front!
svn export myrepo/path/to/file@<revision> .
svn commit

"Sub or Function not defined" when trying to run a VBA script in Outlook

This error “Sub or Function not defined”, will come every time when there is some compile error in script, so please check syntax again of your script.

I guess that is why when you used msqbox instead of msgbox it throws the error.

How to remove space from string?

A funny way to remove all spaces from a variable is to use printf:

$ myvar='a cool variable    with   lots of   spaces in it'
$ printf -v myvar '%s' $myvar
$ echo "$myvar"

It turns out it's slightly more efficient than myvar="${myvar// /}", but not safe regarding globs (*) that can appear in the string. So don't use it in production code.

If you really really want to use this method and are really worried about the globbing thing (and you really should), you can use set -f (which disables globbing altogether):

$ ls
file1  file2
$ myvar='  a cool variable with spaces  and  oh! no! there is  a  glob  *  in it'
$ echo "$myvar"
  a cool variable with spaces  and  oh! no! there is  a  glob  *  in it
$ printf '%s' $myvar ; echo
$ # See the trouble? Let's fix it with set -f:
$ set -f
$ printf '%s' $myvar ; echo
$ # Since we like globbing, we unset the f option:
$ set +f

I posted this answer just because it's funny, not to use it in practice.

jQuery Ajax error handling, show custom exception messages

If someone is here as in 2016 for the answer, use .fail() for error handling as .error() is deprecated as of jQuery 3.0

$.ajax( "example.php" )
  .done(function() {
    alert( "success" );
  .fail(function(jqXHR, textStatus, errorThrown) {
    //handle error here

I hope it helps

Convert Date format into DD/MMM/YYYY format in SQL Server

Simply get date and convert

Declare @Date as Date =Getdate()

Select Format(@Date,'dd/MM/yyyy') as [dd/MM/yyyy] // output: 22/10/2020
Select Format(@Date,'dd-MM-yyyy') as [dd-MM-yyyy] // output: 22-10-2020

//string date
Select Format(cast('25/jun/2013' as date),'dd/MM/yyyy') as StringtoDate // output: 25/06/2013

Source: SQL server date format and converting it (Various examples)

How to split string using delimiter char using T-SQL?

For your specific data, you can use

Select col1, col2, LTRIM(RTRIM(SUBSTRING(
    STUFF(col3, CHARINDEX('|', col3,
    PATINDEX('%|Client Name =%', col3) + 14), 1000, ''),
    PATINDEX('%|Client Name =%', col3) + 14, 1000))) col3
from Table01

EDIT - charindex vs patindex


select col3='Clent ID = 4356hy|Client Name = B B BOB|Client Phone = 667-444-2626|Client Fax = 666-666-0151|Info = INF8888877 -MAC333330554/444400800'
into t1m
from master..spt_values a
cross join master..spt_values b
where a.number < 100
-- (711704 row(s) affected)

set statistics time on

dbcc dropcleanbuffers
dbcc freeproccache
select a=CHARINDEX('|Client Name =', col3) into #tmp1 from t1m
drop table #tmp1

dbcc dropcleanbuffers
dbcc freeproccache
select a=PATINDEX('%|Client Name =%', col3) into #tmp2 from t1m
drop table #tmp2

set statistics time off



 SQL Server Execution Times (1):
   CPU time = 5656 ms,  elapsed time = 6418 ms.
 SQL Server Execution Times (2):
   CPU time = 5813 ms,  elapsed time = 6114 ms.
 SQL Server Execution Times (3):
   CPU time = 5672 ms,  elapsed time = 6108 ms.


 SQL Server Execution Times (1):
   CPU time = 5906 ms,  elapsed time = 6296 ms.
 SQL Server Execution Times (2):
   CPU time = 5860 ms,  elapsed time = 6404 ms.
 SQL Server Execution Times (3):
   CPU time = 6109 ms,  elapsed time = 6301 ms.


The timings for CharIndex and PatIndex for 700k calls are within 3.5% of each other, so I don't think it would matter whichever is used. I use them interchangeably when both can work.

Converting JSON String to Dictionary Not List

The best way to Load JSON Data into Dictionary is You can user the inbuilt json loader.

Below is the sample snippet that can be used.

import json
f = open("data.json")
data = json.load(f))

CSS "and" and "or"

To select properties a AND b of a X element:


To select properties a OR b of a X element:


Content Security Policy "data" not working for base64 Images in Chrome 28

Try this

data to load:

<svg xmlns='' viewBox='0 0 4 5'><path fill='#343a40' d='M2 0L0 2h4zm0 5L0 3h4z'/></svg>

get a utf8 to base64 convertor and convert the "svg" string to:


and the CSP is

img-src data: image/svg+xml;base64,PHN2ZyB4bWxucz0naHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmcnIHZpZXdCb3g9JzAgMCA0IDUn

Android Studio: Default project directory

Top of The Android Studio Title bar its shows the complete file path or LocationLook this image

Wait for page load in Selenium

I use node + selenium-webdriver(which version is 3.5.0 now). what I do for this is:

var webdriver = require('selenium-webdriver'),
    driver = new webdriver.Builder().forBrowser('chrome').build();
driver.wait(driver.executeScript("return document.readyState").then(state => {
  return state === 'complete';

Error when checking Java version: could not find java.dll

Reinstall JDK and set system variable JAVA_HOME on your JDK. (e.g. C:\tools\jdk7)
And add JAVA_HOME variable to your PATH system variable

Type in command line

echo %JAVA_HOME%


java -version

To verify whether your installation was done successfully.

This problem generally occurs in Windows when your "Java Runtime Environment" registry entry is missing or mismatched with the installed JDK. The mismatch can be due to multiple JDKs.

Steps to resolve:

  1. Open the Run window:

    Press windows+R

  2. Open registry window:

    Type regedit and enter.


  4. If Java Runtime Environment is not present inside JavaSoft, then create a new Key and give the name Java Runtime Environment.

  5. For Java Runtime Environment create "CurrentVersion" String Key and give appropriate version as value:

JRE regedit entry

  1. Create a new subkey of 1.8.

  2. For 1.8 create a String Key with name JavaHome with the value of JRE home:

    JRE regedit entry 2


Postgresql : Connection refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections

The error you quote has nothing to do with pg_hba.conf; it's failing to connect, not failing to authorize the connection.

Do what the error message says:

Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections

You haven't shown the command that produces the error. Assuming you're connecting on localhost port 5432 (the defaults for a standard PostgreSQL install), then either:

  • PostgreSQL isn't running

  • PostgreSQL isn't listening for TCP/IP connections (listen_addresses in postgresql.conf)

  • PostgreSQL is only listening on IPv4 ( or and you're connecting on IPv6 (::1) or vice versa. This seems to be an issue on some older Mac OS X versions that have weird IPv6 socket behaviour, and on some older Windows versions.

  • PostgreSQL is listening on a different port to the one you're connecting on

  • (unlikely) there's an iptables rule blocking loopback connections

(If you are not connecting on localhost, it may also be a network firewall that's blocking TCP/IP connections, but I'm guessing you're using the defaults since you didn't say).

So ... check those:

  • ps -f -u postgres should list postgres processes

  • sudo lsof -n -u postgres |grep LISTEN or sudo netstat -ltnp | grep postgres should show the TCP/IP addresses and ports PostgreSQL is listening on

BTW, I think you must be on an old version. On my 9.3 install, the error is rather more detailed:

$ psql -h localhost -p 12345
psql: could not connect to server: Connection refused
        Is the server running on host "localhost" (::1) and accepting
        TCP/IP connections on port 12345?

Switch on ranges of integers in JavaScript

If you are trying to do something fast, efficient and readable, use a standard if...then...else structure like this:

var d =;
if (d < 12) {
    if (d < 5) {
        alert("less than five");
    }else if (d < 9) {
        alert("between 5 and 8");
        alert("between 9 and 11");

If you want to obfuscate it and make it awful (but small), try this:

var;d<12?(d<5?alert("less than five"):d<9?alert("between 5 and 8"):alert("between 9 and 11")):alert("none");

BTW, the above code is a JavaScript if...then...else shorthand statement. It is a great example of how NOT to write code unless obfuscation or code minification is the goal. Be aware that code maintenance can be an issue if written this way. Very few people can easily read through it, if at all. The code size, however, is 50% smaller than the standard if...then...else without any loss of performance. This means that in larger codebases, minification like this can greatly speed code delivery across bandwidth constrained or high latency networks.

This, however, should not be considered a good answer. It is just an example of what CAN be done, not what SHOULD be done.

Get protocol, domain, and port from URL

ES6 style with configurable parameters.

 * Get the current URL from `window` context object.
 * Will return the fully qualified URL if neccessary:
 *   getCurrentBaseURL(true, false) // `http://localhost/` - `https://localhost:3000/`
 *   getCurrentBaseURL(true, true) // `` - ``
 *   getCurrentBaseURL(false, true) // `` - `localhost:3000`
 * @param {boolean} [includeProtocol=true]
 * @param {boolean} [removeTrailingSlash=false]
 * @returns {string} The current base URL.
export const getCurrentBaseURL = (includeProtocol = true, removeTrailingSlash = false) => {
  if (!window || !window.location || !window.location.hostname || !window.location.protocol) {
      `The getCurrentBaseURL function must be called from a context in which window object exists. Yet, window is ${window}`,
      [window, window.location, window.location.hostname, window.location.protocol],
    throw new TypeError('Whole or part of window is not defined.')

  const URL = `${includeProtocol ? `${window.location.protocol}//` : ''}${window.location.hostname}${
    window.location.port ? `:${window.location.port}` : ''
  }${removeTrailingSlash ? '' : '/'}`

  // console.log(`The URL is ${URL}`)

  return URL

How do AX, AH, AL map onto EAX?

No, that's not quite right.

EAX is the full 32-bit value
AX is the lower 16-bits
AL is the lower 8 bits
AH is the bits 8 through 15 (zero-based)

So AX is composed of AH:AL halves, and is itself the low half of EAX. (The upper half of EAX isn't directly accessible as a 16-bit register; you can shift or rotate EAX if you want to get at it.)

For completeness, in addition to the above, which was based on a 32-bit CPU, 64-bit Intel/AMD CPUs have

RAX, which hold a 64-bit value, and where EAX is mapped to the lower 32 bits.

All of this also applies to EBX/RBX, ECX/RCX, and EDX/RDX. The other registers like EDI/RDI have a DI low 16-bit partial register, but no high-8 part, and the low-8 DIL is only accessible in 64-bit mode: Assembly registers in 64-bit architecture

Writing AL, AH, or AX merges into the full AX/EAX/RAX, leaving other bytes unmodified for historical reasons. (In 32 or 64-bit code, prefer a movzx eax, byte [mem] or movzx eax, word [mem] load if you don't specifically want this merging: Why doesn't GCC use partial registers?)

Writing EAX zero-extends into RAX. (Why do x86-64 instructions on 32-bit registers zero the upper part of the full 64-bit register?)

Regex date format validation on Java

Below added code is working for me if you are using pattern dd-MM-yyyy.

public boolean isValidDate(String date) {
        boolean check;
        String date1 = "^(0?[1-9]|[12][0-9]|3[01])-(0?[1-9]|1[012])-([12][0-9]{3})$";
        check = date.matches(date1);

        return check;

How to convert JSONObjects to JSONArray?

Even shorter and with json-functions:

JSONObject songsObject = json.getJSONObject("songs");
JSONArray songsArray = songsObject.toJSONArray(songsObject.names());

How can I use nohup to run process as a background process in linux?

In general, I use nohup CMD & to run a nohup background process. However, when the command is in a form that nohup won't accept then I run it through bash -c "...".

For example:

nohup bash -c "(time ./script arg1 arg2 > script.out) &> time_n_err.out" &

stdout from the script gets written to script.out, while stderr and the output of time goes into time_n_err.out.

So, in your case:

nohup bash -c "(time bash executeScript 1 input fileOutput > scrOutput) &> timeUse.txt" &

Creating a LinkedList class from scratch

class Node
  int data;
     Node link;

     public Node()

     Node ptr,start,temp;

    void create()throws  IOException
         int n;
         BufferedReader br=new BufferedReader(new InputStreamReader(;
         System.out.println("Enter first data");;
         char ins ='y';
             System.out.println("Wanna Insert another node???");
                 temp=new Node();
                 System.out.println("Enter next data");

public static void main(String args[])throws IOException
       Node first= new Node();

How-to turn off all SSL checks for postman for a specific site

enter image description here

click here in settings, one pop up window will get open. There we have switcher to make SSL verification certificate (Off)

How do I determine whether my calculation of pi is accurate?

You could use multiple approaches and see if they converge to the same answer. Or grab some from the 'net. The Chudnovsky algorithm is usually used as a very fast method of calculating pi.

Illegal mix of collations error in MySql

You need to change each column Collation from latin1_general_ci to latin1_swedish_ci

How to add a new column to an existing sheet and name it?

For your question as asked

Range("c1:c4") = Application.Transpose(Array("Loc", "uk", "us", "nj"))

If you had a way of automatically looking up the data (ie matching uk against employer id) then you could do that in VBA

Javascript Regex: How to put a variable inside a regular expression?

const regex = new RegExp(`ReGeX${testVar}ReGeX`);
string.replace(regex, "replacement");


Per some of the comments, it's important to note that you may want to escape the variable if there is potential for malicious content (e.g. the variable comes from user input)

ES6 Update

In 2019, this would usually be written using a template string, and the above code has been updated. The original answer was:

var regex = new RegExp("ReGeX" + testVar + "ReGeX");
string.replace(regex, "replacement");

Centos/Linux setting logrotate to maximum file size for all logs

It specifies the size of the log file to trigger rotation. For example size 50M will trigger a log rotation once the file is 50MB or greater in size. You can use the suffix M for megabytes, k for kilobytes, and G for gigabytes. If no suffix is used, it will take it to mean bytes. You can check the example at the end. There are three directives available size, maxsize, and minsize. According to manpage:

minsize size
              Log  files  are  rotated when they grow bigger than size bytes,
              but not before the additionally specified time interval (daily,
              weekly,  monthly, or yearly).  The related size option is simi-
              lar except that it is mutually exclusive with the time interval
              options,  and  it causes log files to be rotated without regard
              for the last rotation time.  When minsize  is  used,  both  the
              size and timestamp of a log file are considered.

size size
              Log files are rotated only if they grow bigger then size bytes.
              If size is followed by k, the size is assumed to  be  in  kilo-
              bytes.  If the M is used, the size is in megabytes, and if G is
              used, the size is in gigabytes. So size 100,  size  100k,  size
              100M and size 100G are all valid.
maxsize size
              Log files are rotated when they grow bigger than size bytes even before
              the additionally specified time interval (daily, weekly, monthly, 
              or yearly).  The related size option is  similar  except  that  it 
              is mutually exclusive with the time interval options, and it causes
              log files to be rotated without regard for the last rotation time.  
              When maxsize is used, both the size and timestamp of a log file are                  

Here is an example:

"/var/log/httpd/access.log" /var/log/httpd/error.log {
           rotate 5
           mail [email protected]
           size 100k
               /usr/bin/killall -HUP httpd

Here is an explanation for both files /var/log/httpd/access.log and /var/log/httpd/error.log. They are rotated whenever it grows over 100k in size, and the old logs files are mailed (uncompressed) to [email protected] after going through 5 rotations, rather than being removed. The sharedscripts means that the postrotate script will only be run once (after the old logs have been compressed), not once for each log which is rotated. Note that the double quotes around the first filename at the beginning of this section allows logrotate to rotate logs with spaces in the name. Normal shell quoting rules apply, with ,, and \ characters supported.

Best way to implement multi-language/globalization in large .NET project

We use a custom provider for multi language support and put all texts in a database table. It works well except we sometimes face caching problems when updating texts in the database without updating the web application.

javascript remove "disabled" attribute from html input

method 1 <input type="text" onclick="this.disabled=false;" disabled>
method 2 <input type="text" onclick="this.removeAttribute('disabled');" disabled>
method 3 <input type="text" onclick="this.removeAttribute('readonly');" readonly>

code of the previous answers don't seem to work in inline mode, but there is a workaround: method 3.

see demo

Where can I find Android source code online?

This eclipse plugin allows for inline source viewing and even stepping inside the Android source code:

(edit: specifically the "Android Sources" plugin:

Unable to connect to SQL Express "Error: 26-Error Locating Server/Instance Specified)

Have you Disabled the VIA setting in the SQL configuration manager? If not, do disable it first (if VIA is enabled, you cannot get connected) and yes TCP must be enabled. Give it a try and it should be working fine.

Make the changes only for that's particular instance name.


Difference between DOM parentNode and parentElement

In Internet Explorer, parentElement is undefined for SVG elements, whereas parentNode is defined.

How to get the nvidia driver version from the command line?

[NOTE: I am not deleting my answer on purpose, so people see how not to do it]

If you use:

me@over_there:~$  dpkg --status nvidia-current | grep Version | cut -f 1 -d '-' | sed 's/[^.,0-9]//g'

you will get the version of the nVIDIA driver package installed through your distribution's packaging mechanism. But this may not be the version that is actually running as part of your kernel right now.

How to execute Python code from within Visual Studio Code

A simple and direct Python extension would save both time and efforts. Linting, debugging, code completion are the available features once installation is done. After this, to run the code proper Python installation path needs to be configured in order to run the code. General settings are available in User scope and Workspace can be configured for Python language– "python.pythonPath": "c:/python27/python.exe" With above steps at least the basic Python programs can be executed.

How can I install an older version of a package via NuGet?

Try the following:

Uninstall-Package Newtonsoft.Json -Force

Followed by:

Install-Package Newtonsoft.Json -Version <press tab key for autocomplete>

How do I access my webcam in Python?

import cv2 as cv

capture = cv.VideoCapture(0)

while True:
    isTrue,frame =
    if cv.waitKey(20) & 0xFF==ord('d'):


0 <-- refers to the camera , replace it with file path to read a video file

cv.waitKey(20) & 0xFF==ord('d') <-- to destroy window when key is pressed

Angular error: "Can't bind to 'ngModel' since it isn't a known property of 'input'"

If you want to use two-way data binding for form inputs you need to import theFormsModule package in your Angular module. For more info see the Angular 2 official tutorial here and the official documentation for forms

in the app.module.ts add below lines :

import { FormsModule } from '@angular/forms';


  imports: [

How to set column header text for specific column in Datagridview C#

Dg_View.Columns.Add("userid","User Id");
Dg_View.Columns[0].Width = 100;

Dg_View.Columns.Add("username", "User name");
Dg_View.Columns[0].Width = 100;

np.mean() vs np.average() in Python NumPy?

In addition to the differences already noted, there's another extremely important difference that I just now discovered the hard way: unlike np.mean, np.average doesn't allow the dtype keyword, which is essential for getting correct results in some cases. I have a very large single-precision array that is accessed from an h5 file. If I take the mean along axes 0 and 1, I get wildly incorrect results unless I specify dtype='float64':

(4096, 4096, 720)

m1 = np.average(T, axis=(0,1))                #  garbage
m2 = np.mean(T, axis=(0,1))                   #  the same garbage
m3 = np.mean(T, axis=(0,1), dtype='float64')  # correct results

Unfortunately, unless you know what to look for, you can't necessarily tell your results are wrong. I will never use np.average again for this reason but will always use np.mean(.., dtype='float64') on any large array. If I want a weighted average, I'll compute it explicitly using the product of the weight vector and the target array and then either np.sum or np.mean, as appropriate (with appropriate precision as well).

Java getHours(), getMinutes() and getSeconds()

Java 8

    System.out.println(;       // 7
    System.out.println(;     // 45
    System.out.println(;     // 32


System.out.println(Calendar.getInstance().get(Calendar.HOUR_OF_DAY));  // 7 
System.out.println(Calendar.getInstance().get(Calendar.MINUTE));       // 45
System.out.println(Calendar.getInstance().get(Calendar.SECOND));       // 32

Joda Time

    System.out.println(new DateTime().getHourOfDay());      // 7
    System.out.println(new DateTime().getMinuteOfHour());   // 45
    System.out.println(new DateTime().getSecondOfMinute()); // 32


Java 8

    // 07:48:55.056
    // 7:48:55
    System.out.println( + ":" + + ":" +;

    // 07:48:55
    System.out.println(new SimpleDateFormat("HH:mm:ss").format(Calendar.getInstance().getTime()));

    // 074855
    System.out.println(new SimpleDateFormat("HHmmss").format(Calendar.getInstance().getTime()));

    // 07:48:55 
    System.out.println(new Date().toString().substring(11, 20));

jQuery rotate/transform

I came up with some kind of solution to the problem. It involves jquery and css. This works like toggle but instead of toggling the display of elements it just changes its properties upon alternate clicks. Upon clicking the div it rotates the element with tag 180 degrees and when you click it again the element with tag returns to its original position. If you want to change the animation duration just change transition-duration property.




$(document).ready( function ()  {  var toggle = 1;
  $('div').click( function () {
      if ( (toggle%2)==0){
          $('#example1').css( {'transform': 'rotate(180deg)'});
          $('#example1').css({'transform': 'rotate(0deg)'});


Check whether number is even or odd

     * Check if a number is even or not using modulus operator.
     * @param number the number to be checked.
     * @return {@code true} if the given number is even, otherwise {@code false}.
    public static boolean isEven(int number) {
        return number % 2 == 0;

     * Check if a number is even or not using & operator.
     * @param number the number to be checked.
     * @return {@code true} if the given number is even, otherwise {@code false}.
    public static boolean isEvenFaster(int number) {
        return (number & 1) == 0;


How To Run PHP From Windows Command Line in WAMPServer

The PHP CLI as its called ( php for the Command Line Interface ) is called php.exe It lives in c:\wamp\bin\php\php5.x.y\php.exe ( where x and y are the version numbers of php that you have installed )

If you want to create php scrips to run from the command line then great its easy and very useful.

Create yourself a batch file like this, lets call it phppath.cmd :

php -v

Change x.y.z to a valid folder name for a version of PHP that you have installed within WAMPServer

Save this into one of your folders that is already on your PATH, so you can run it from anywhere.

Now from a command window, cd into your source folder and run >phppath.

Then run

php your_script.php

It should work like a dream.

Here is an example that configures PHP Composer and PEAR if required and they exist

@echo off

REM **************************************************************
REM * PLACE This file in a folder that is already on your PATH
REM * Or just put it in your C:\Windows folder as that is on the
REM * Search path by default
REM * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
REM * EDIT THE NEXT 3 Parameters to fit your installed WAMPServer
REM **************************************************************

set baseWamp=D:\wamp
set defaultPHPver=7.4.3
set composerInstalled=%baseWamp%\composer
set phpFolder=\bin\php\php

if %1.==. (
    set phpver=%baseWamp%%phpFolder%%defaultPHPver%
) else (
    set phpver=%baseWamp%%phpFolder%%1

php -v
echo ---------------------------------------------------------------


IF exist %phpver%\pear (
    set PHP_PEAR_SYSCONF_DIR=%baseWamp%%phpFolder%%phpver%
    set PHP_PEAR_INSTALL_DIR=%baseWamp%%phpFolder%%phpver%\pear
    set PHP_PEAR_DOC_DIR=%baseWamp%%phpFolder%%phpver%\docs
    set PHP_PEAR_BIN_DIR=%baseWamp%%phpFolder%%phpver%
    set PHP_PEAR_DATA_DIR=%baseWamp%%phpFolder%%phpver%\data
    set PHP_PEAR_PHP_BIN=%baseWamp%%phpFolder%%phpver%\php.exe
    set PHP_PEAR_TEST_DIR=%baseWamp%%phpFolder%%phpver%\tests

    echo ---------------------------------------------------------------
) else (
    echo ---------------------------------------------------------------

REM **************************************************************
REM * This assumes that composer is installed in /wamp/composer
REM **************************************************************
IF EXIST %composerInstalled% (
    echo ---------------------------------------------------------------
    set COMPOSER_HOME=%baseWamp%\composer
    set COMPOSER_CACHE_DIR=%baseWamp%\composer


    rem echo TO UPDATE COMPOSER do > composer self-update
    echo ---------------------------------------------------------------
) else (
    echo ---------------------------------------------------------------
    echo ---------------------------------------------------------------

set baseWamp=
set defaultPHPver=
set composerInstalled=
set phpFolder=

Call this command file like this to use the default version of PHP

> phppath

Or to get a specific version of PHP like this

> phppath 5.6.30

What are major differences between C# and Java?

Comparing Java 7 and C# 3

(Some features of Java 7 aren't mentioned here, but the using statement advantage of all versions of C# over Java 1-6 has been removed.)

Not all of your summary is correct:

  • In Java methods are virtual by default but you can make them final. (In C# they're sealed by default, but you can make them virtual.)
  • There are plenty of IDEs for Java, both free (e.g. Eclipse, Netbeans) and commercial (e.g. IntelliJ IDEA)

Beyond that (and what's in your summary already):

  • Generics are completely different between the two; Java generics are just a compile-time "trick" (but a useful one at that). In C# and .NET generics are maintained at execution time too, and work for value types as well as reference types, keeping the appropriate efficiency (e.g. a List<byte> as a byte[] backing it, rather than an array of boxed bytes.)
  • C# doesn't have checked exceptions
  • Java doesn't allow the creation of user-defined value types
  • Java doesn't have operator and conversion overloading
  • Java doesn't have iterator blocks for simple implemetation of iterators
  • Java doesn't have anything like LINQ
  • Partly due to not having delegates, Java doesn't have anything quite like anonymous methods and lambda expressions. Anonymous inner classes usually fill these roles, but clunkily.
  • Java doesn't have expression trees
  • C# doesn't have anonymous inner classes
  • C# doesn't have Java's inner classes at all, in fact - all nested classes in C# are like Java's static nested classes
  • Java doesn't have static classes (which don't have any instance constructors, and can't be used for variables, parameters etc)
  • Java doesn't have any equivalent to the C# 3.0 anonymous types
  • Java doesn't have implicitly typed local variables
  • Java doesn't have extension methods
  • Java doesn't have object and collection initializer expressions
  • The access modifiers are somewhat different - in Java there's (currently) no direct equivalent of an assembly, so no idea of "internal" visibility; in C# there's no equivalent to the "default" visibility in Java which takes account of namespace (and inheritance)
  • The order of initialization in Java and C# is subtly different (C# executes variable initializers before the chained call to the base type's constructor)
  • Java doesn't have properties as part of the language; they're a convention of get/set/is methods
  • Java doesn't have the equivalent of "unsafe" code
  • Interop is easier in C# (and .NET in general) than Java's JNI
  • Java and C# have somewhat different ideas of enums. Java's are much more object-oriented.
  • Java has no preprocessor directives (#define, #if etc in C#).
  • Java has no equivalent of C#'s ref and out for passing parameters by reference
  • Java has no equivalent of partial types
  • C# interfaces cannot declare fields
  • Java has no unsigned integer types
  • Java has no language support for a decimal type. (java.math.BigDecimal provides something like System.Decimal - with differences - but there's no language support)
  • Java has no equivalent of nullable value types
  • Boxing in Java uses predefined (but "normal") reference types with particular operations on them. Boxing in C# and .NET is a more transparent affair, with a reference type being created for boxing by the CLR for any value type.

This is not exhaustive, but it covers everything I can think of off-hand.

What does the exclamation mark do before the function?

There is a good point for using ! for function invocation marked on airbnb JavaScript guide

Generally idea for using this technique on separate files (aka modules) which later get concatenated. The caveat here is that files supposed to be concatenated by tools which put the new file at the new line (which is anyway common behavior for most of concat tools). In that case, using ! will help to avoid error in if previously concatenated module missed trailing semicolon, and yet that will give the flexibility to put them in any order with no worry.

!function abc(){}();
!function bca(){}();

Will work the same as

!function abc(){}();
(function bca(){})();

but saves one character and arbitrary looks better.

And by the way any of +,-,~,void operators have the same effect, in terms of invoking the function, for sure if you have to use something to return from that function they would act differently.

abcval = !function abc(){return true;}() // abcval equals false
bcaval = +function bca(){return true;}() // bcaval equals 1
zyxval = -function zyx(){return true;}() // zyxval equals -1
xyzval = ~function xyz(){return true;}() // your guess?

but if you using IIFE patterns for one file one module code separation and using concat tool for optimization (which makes one line one file job), then construction

!function abc(/*no returns*/) {}()
+function bca() {/*no returns*/}()

Will do safe code execution, same as a very first code sample.

This one will throw error cause JavaScript ASI will not be able to do its work.

!function abc(/*no returns*/) {}()
(function bca() {/*no returns*/})()

One note regarding unary operators, they would do similar work, but only in case, they used not in the first module. So they are not so safe if you do not have total control over the concatenation order.

This works:

!function abc(/*no returns*/) {}()
^function bca() {/*no returns*/}()

This not:

^function abc(/*no returns*/) {}()
!function bca() {/*no returns*/}()

Download file of any type in Asp.Net MVC using FileResult?

If you're using .NET Framework 4.5 then you use use the MimeMapping.GetMimeMapping(string FileName) to get the MIME-Type for your file. This is how I've used it in my action.

return File(Path.Combine(@"c:\path", fileFromDB.FileNameOnDisk), MimeMapping.GetMimeMapping(fileFromDB.FileName), fileFromDB.FileName);

Convert datetime object to a String of date only in Python

You can use strftime to help you format your date.


import datetime
t = datetime.datetime(2012, 2, 23, 0, 0)

will yield:


More information about formatting see here

Is it possible to use jQuery .on and hover?

(Look at the last edit in this answer if you need to use .on() with elements populated with JavaScript)

Use this for elements that are not populated using JavaScript:

$(".selector").on("mouseover", function () {
    //stuff to do on mouseover

.hover() has it's own handler:

If you want to do multiple things, chain them in the .on() handler like so:

    mouseenter: function () {
        //stuff to do on mouse enter
    mouseleave: function () {
        //stuff to do on mouse leave

According to the answers provided below you can use hover with .on(), but:

Although strongly discouraged for new code, you may see the pseudo-event-name "hover" used as a shorthand for the string "mouseenter mouseleave". It attaches a single event handler for those two events, and the handler must examine event.type to determine whether the event is mouseenter or mouseleave. Do not confuse the "hover" pseudo-event-name with the .hover() method, which accepts one or two functions.

Also, there are no performance advantages to using it and it's more bulky than just using mouseenter or mouseleave. The answer I provided requires less code and is the proper way to achieve something like this.


It's been a while since this question was answered and it seems to have gained some traction. The above code still stands, but I did want to add something to my original answer.

While I prefer using mouseenter and mouseleave (helps me understand whats going on in the code) with .on() it is just the same as writing the following with hover()

$(".selector").hover(function () {
    //stuff to do on mouse enter
function () {
    //stuff to do on mouse leave

Since the original question did ask how they could properly use on() with hover(), I thought I would correct the usage of on() and didn't find it necessary to add the hover() code at the time.


Some new answers provided below detail how .on() should work if the div in question is populated using JavaScript. For example, let's say you populate a div using jQuery's .load() event, like so:

(function ($) {
    //append div to document body
    $('<div class="selector">Test</div>').appendTo(document.body);

The above code for .on() would not stand. Instead, you should modify your code slightly, like this:

    mouseenter: function () {
        //stuff to do on mouse enter
    mouseleave: function () {
        //stuff to do on mouse leave
}, ".selector"); //pass the element as an argument to .on

This code will work for an element populated with JavaScript after a .load() event has happened. Just change your argument to the appropriate selector.

Python Math - TypeError: 'NoneType' object is not subscriptable

lista = list.sort(lista)

This should be


The .sort() method is in-place, and returns None. If you want something not in-place, which returns a value, you could use

sorted_list = sorted(lista)

Aside #1: please don't call your lists list. That clobbers the builtin list type.

Aside #2: I'm not sure what this line is meant to do:

print str("value 1a")+str(" + ")+str("value 2")+str(" = ")+str("value 3a ")+str("value 4")+str("\n")

is it simply

print "value 1a + value 2 = value 3a value 4"

? In other words, I don't know why you're calling str on things which are already str.

Aside #3: sometimes you use print("something") (Python 3 syntax) and sometimes you use print "something" (Python 2). The latter would give you a SyntaxError in py3, so you must be running 2.*, in which case you probably don't want to get in the habit or you'll wind up printing tuples, with extra parentheses. I admit that it'll work well enough here, because if there's only one element in the parentheses it's not interpreted as a tuple, but it looks strange to the pythonic eye..

The exception TypeError: 'NoneType' object is not subscriptable happens because the value of lista is actually None. You can reproduce TypeError that you get in your code if you try this at the Python command line:


The reason that lista gets set to None is because the return value of list.sort() is None... it does not return a sorted copy of the original list. Instead, as the documentation points out, the list gets sorted in-place instead of a copy being made (this is for efficiency reasons).

If you do not want to alter the original version you can use

other_list = sorted(lista)

Recursive sub folder search and return files in a list python

Its not the most pythonic answer, but I'll put it here for fun because it's a neat lesson in recursion

def find_files( files, dirs=[], extensions=[]):
    new_dirs = []
    for d in dirs:
            new_dirs += [ os.path.join(d, f) for f in os.listdir(d) ]
        except OSError:
            if os.path.splitext(d)[1] in extensions:

    if new_dirs:
        find_files(files, new_dirs, extensions )

On my machine I have two folders, root and root2

mender@multivax ]ls -R root root2
temp1 temp2

temp1.1 temp1.2


f.mi  f.mid


dummie.txt temp3


Lets say I want to find all .txt and all .mid files in either of these directories, then I can just do

files = []
find_files( files, dirs=['root','root2'], extensions=['.mid','.txt'] )

# 'root/temp2/tmp.mid',
# 'root2/temp3/song.mid',
# 'root/temp1/temp1.1/f1.mid',
# 'root/temp1/temp1.2/f.mid']

Search for highest key/index in an array

This should work fine

$arr = array( 1 => "A", 10 => "B", 5 => "C" );

How can I install a CPAN module into a local directory?

I had a similar problem, where I couldn't even install local::lib

I created an installer that installed the module somewhere relative to the .pl files

The install goes like:

perl Makefile.PL PREFIX=./modulos
make install

Then, in the .pl file that requires the module, which is in ./

use lib qw(./modulos/share/perl/5.8.8/); # You may need to change this path
use module::name;

The rest of the files (,, etc) require no changes.

You can call the .pl file with just


Sorting a set of values

From a comment:

I want to sort each set.

That's easy. For any set s (or anything else iterable), sorted(s) returns a list of the elements of s in sorted order:

>>> s = set(['0.000000000', '0.009518000', '10.277200999', '0.030810999', '0.018384000', '4.918560000'])
>>> sorted(s)
['0.000000000', '0.009518000', '0.018384000', '0.030810999', '10.277200999', '4.918560000']

Note that sorted is giving you a list, not a set. That's because the whole point of a set, both in mathematics and in almost every programming language,* is that it's not ordered: the sets {1, 2} and {2, 1} are the same set.

You probably don't really want to sort those elements as strings, but as numbers (so 4.918560000 will come before 10.277200999 rather than after).

The best solution is most likely to store the numbers as numbers rather than strings in the first place. But if not, you just need to use a key function:

>>> sorted(s, key=float)
['0.000000000', '0.009518000', '0.018384000', '0.030810999', '4.918560000', '10.277200999']

For more information, see the Sorting HOWTO in the official docs.

* See the comments for exceptions.

How to save the output of a console.log(object) to a file?

There is another open-source tool that allows you to save all console.log output in a file on your server - JS LogFlush (plug!).

JS LogFlush is an integrated JavaScript logging solution which include:

  • cross-browser UI-less replacement of console.log - on client side.
  • log storage system - on server side.


What exactly is RESTful programming?

Here is my basic outline of REST. I tried to demonstrate the thinking behind each of the components in a RESTful architecture so that understanding the concept is more intuitive. Hopefully this helps demystify REST for some people!

REST (Representational State Transfer) is a design architecture that outlines how networked resources (i.e. nodes that share information) are designed and addressed. In general, a RESTful architecture makes it so that the client (the requesting machine) and the server (the responding machine) can request to read, write, and update data without the client having to know how the server operates and the server can pass it back without needing to know anything about the client. Okay, cool...but how do we do this in practice?

  • The most obvious requirement is that there needs to be a universal language of some sort so that the server can tell the client what it is trying to do with the request and for the server to respond.

  • But to find any given resource and then tell the client where that resource lives, there needs to be a universal way of pointing at resources. This is where Universal Resource Identifiers (URIs) come in; they are basically unique addresses to find the resources.

But the REST architecture doesn’t end there! While the above fulfills the basic needs of what we want, we also want to have an architecture that supports high volume traffic since any given server usually handles responses from a number of clients. Thus, we don’t want to overwhelm the server by having it remember information about previous requests.

  • Therefore, we impose the restriction that each request-response pair between the client and the server is independent, meaning that the server doesn’t have to remember anything about previous requests (previous states of the client-server interaction) to respond to a new request. This means that we want our interactions to be stateless.

  • To further ease the strain on our server from redoing computations that have already been recently done for a given client, REST also allows caching. Basically, caching means to take a snapshot of the initial response provided to the client. If the client makes the same request again, the server can provide the client with the snapshot rather than redo all of the computations that were necessary to create the initial response. However, since it is a snapshot, if the snapshot has not expired--the server sets an expiration time in advance--and the response has been updated since the initial cache (i.e. the request would give a different answer than the cached response), the client will not see the updates until the cache expires (or the cache is cleared) and the response is rendered from scratch again.

  • The last thing that you’ll often here about RESTful architectures is that they are layered. We have actually already been implicitly discussing this requirement in our discussion of the interaction between the client and server. Basically, this means that each layer in our system interacts only with adjacent layers. So in our discussion, the client layer interacts with our server layer (and vice versa), but there might be other server layers that help the primary server process a request that the client does not directly communicate with. Rather, the server passes on the request as necessary.

Now, if all of this sounds familiar, then great. The Hypertext Transfer Protocol (HTTP), which defines the communication protocol via the World Wide Web is an implementation of the abstract notion of RESTful architecture (or an implementation of the abstract REST class if you're an OOP fanatic like me). In this implementation of REST, the client and server interact via GET, POST, PUT, DELETE, etc., which are part of the universal language and the resources can be pointed to using URLs.

Using DataContractSerializer to serialize, but can't deserialize back

This best for XML Deserialize

 public static object Deserialize(string xml, Type toType)

        using (MemoryStream memoryStream = new MemoryStream(Encoding.UTF8.GetBytes(xml)))
            System.IO.StreamReader str = new System.IO.StreamReader(memoryStream);
            System.Xml.Serialization.XmlSerializer xSerializer = new System.Xml.Serialization.XmlSerializer(toType);
            return xSerializer.Deserialize(str);


Simple and fast method to compare images for similarity

If for matching identical images - code for L2 distance

// Compare two images by getting the L2 error (square-root of sum of squared error).
double getSimilarity( const Mat A, const Mat B ) {
if ( A.rows > 0 && A.rows == B.rows && A.cols > 0 && A.cols == B.cols ) {
    // Calculate the L2 relative error between images.
    double errorL2 = norm( A, B, CV_L2 );
    // Convert to a reasonable scale, since L2 error is summed across all pixels of the image.
    double similarity = errorL2 / (double)( A.rows * A.cols );
    return similarity;
else {
    //Images have a different size
    return 100000000.0;  // Return a bad value

Fast. But not robust to changes in lighting/viewpoint etc. Source

Importing two classes with same name. How to handle?

This scenario is not so common in real-world programming, but not so strange too. It happens sometimes that two classes in different packages have same name and we need both of them.

It is not mandatory that if two classes have same name, then both will contain same functionalities and we should pick only one of them.

If we need both, then there is no harm in using that. And it's not a bad programming idea too.

But we should use fully qualified names of the classes (that have same name) in order to make it clear which class we are referring too.


What do *args and **kwargs mean?

Another good use for *args and **kwargs: you can define generic "catch all" functions, which is great for decorators where you return such a wrapper instead of the original function.

An example with a trivial caching decorator:

import pickle, functools
def cache(f):
  _cache = {}
  def wrapper(*args, **kwargs):
    key = pickle.dumps((args, kwargs))
    if key not in _cache:
      _cache[key] = f(*args, **kwargs) # call the wrapped function, save in cache
    return _cache[key] # read value from cache
  functools.update_wrapper(wrapper, f) # update wrapper's metadata
  return wrapper

import time
def foo(n):
  return n*2

foo(10) # first call with parameter 10, sleeps
foo(10) # returns immediately

What is the "Temporary ASP.NET Files" folder for?

These are what's known as Shadow Copy Folders.

Simplistically....and I really mean it:

When ASP.NET runs your app for the first time, it copies any assemblies found in the /bin folder, copies any source code files (found for example in the App_Code folder) and parses your aspx, ascx files to c# source files. ASP.NET then builds/compiles all this code into a runnable application.

One advantage of doing this is that it prevents the possibility of .NET assembly DLL's #(in the /bin folder) becoming locked by the ASP.NET worker process and thus not updatable.

ASP.NET watches for file changes in your website and will if necessary begin the whole process all over again.

Theoretically the folder shouldn't need any maintenance, but from time to time, and only very rarely you may need to delete contents. That said, I work for a hosting company, we run up to 1200 sites per shared server and I haven't had to touch this folder on any of the 250 or so machines for years.

This is outlined in the MSDN article Understanding ASP.NET Dynamic Compilation

Replace all elements of Python NumPy Array that are greater than some value

Another way is to use which does in-place replacement and works with multidimentional arrays:

import numpy as np

# create 2x3 array with numbers 0..5
arr = np.arange(6).reshape(2, 3)

# replace 0 with -10, arr == 0, -10)

How to get my Android device Internal Download Folder path

if a device has an SD card, you use:


if you don't have an SD card, you use:


if there is no SD card, you can create your own directory on the device locally.

    //if there is no SD card, create new directory objects to make directory on device
        if (Environment.getExternalStorageState() == null) {
                        //create new file directory object
            directory = new File(Environment.getDataDirectory()
                    + "/RobotiumTestLog/");
            photoDirectory = new File(Environment.getDataDirectory()
                    + "/Robotium-Screenshots/");
             * this checks to see if there are any previous test photo files
             * if there are any photos, they are deleted for the sake of
             * memory
            if (photoDirectory.exists()) {
                File[] dirFiles = photoDirectory.listFiles();
                if (dirFiles.length != 0) {
                    for (int ii = 0; ii <= dirFiles.length; ii++) {
            // if no directory exists, create new directory
            if (!directory.exists()) {

            // if phone DOES have sd card
        } else if (Environment.getExternalStorageState() != null) {
            // search for directory on SD card
            directory = new File(Environment.getExternalStorageDirectory()
                    + "/RobotiumTestLog/");
            photoDirectory = new File(
                            + "/Robotium-Screenshots/");
            if (photoDirectory.exists()) {
                File[] dirFiles = photoDirectory.listFiles();
                if (dirFiles.length > 0) {
                    for (int ii = 0; ii < dirFiles.length; ii++) {
                    dirFiles = null;
            // if no directory exists, create new directory to store test
            // results
            if (!directory.exists()) {
        }// end of SD card checking

add permissions on your manifest.xml

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

Happy coding..

When should we call System.exit in Java

In applications that may have complex shutdown hooks, this method should not be called from an unknown thread. System.exit never exits normally because the call will block until the JVM is terminated. It's as if whatever code is running that has the power plug pulled on it before it can finish. Calling System.exit will initiate the program's shutdown hooks and whatever thread that calls System.exit will block until program termination. This has the implication that if the shutdown hook in turn submits a task to the thread from which System.exit was called, the program will deadlock.

I'm handling this in my code with the following:

public static void exit(final int status) {
    new Thread("App-exit") {
        public void run() {

How to navigate to to different directories in the terminal (mac)?

To check that the file you're trying to open actually exists, you can change directories in terminal using cd. To change to ~/Desktop/sass/css: cd ~/Desktop/sass/css. To see what files are in the directory: ls.

If you want information about either of those commands, use the man page: man cd or man ls, for example.

Google for "basic unix command line commands" or similar; that will give you numerous examples of moving around, viewing files, etc in the command line.

On Mac OS X, you can also use open to open a finder window: open . will open the current directory in finder. (open ~/Desktop/sass/css will open the ~/Desktop/sass/css).

Can I force pip to reinstall the current version?

sudo pip3 install --upgrade --force-reinstall --no-deps --no-cache-dir <package-name>==<package-version>

Some relevant answers:

Difference between pip install options "ignore-installed" and "force-reinstall"

Does WGET timeout?

Since in your question you said it's a PHP script, maybe the best solution could be to simply add in your script:


In this way even if wget terminates, the PHP script goes on being processed at least until it does not exceeds max_execution_time limit (ini directive: 30 seconds by default).

As per wget anyay you should not change its timeout, according to the UNIX manual the default wget timeout is 900 seconds (15 minutes), whis is much larger that the 5-6 minutes you need.

jQuery: select an element's class and id at the same time?

How about this code?


How to remove non-alphanumeric characters?

here's a really simple regex for that:


and used as you need it (with a forward / slash delimiter).

preg_replace("/\W|_/", '', $string);

Test it here with this great tool that explains what the regex is doing:

Replace all 0 values to NA

Replacing all zeroes to NA:

df[df == 0] <- NA


1. It is not NULL what you should want to replace zeroes with. As it says in ?'NULL',

NULL represents the null object in R

which is unique and, I guess, can be seen as the most uninformative and empty object.1 Then it becomes not so surprising that

data.frame(x = c(1, NULL, 2))
#   x
# 1 1
# 2 2

That is, R does not reserve any space for this null object.2 Meanwhile, looking at ?'NA' we see that

NA is a logical constant of length 1 which contains a missing value indicator. NA can be coerced to any other vector type except raw.

Importantly, NA is of length 1 so that R reserves some space for it. E.g.,

data.frame(x = c(1, NA, 2))
#    x
# 1  1
# 2 NA
# 3  2

Also, the data frame structure requires all the columns to have the same number of elements so that there can be no "holes" (i.e., NULL values).

Now you could replace zeroes by NULL in a data frame in the sense of completely removing all the rows containing at least one zero. When using, e.g., var, cov, or cor, that is actually equivalent to first replacing zeroes with NA and setting the value of use as "complete.obs". Typically, however, this is unsatisfactory as it leads to extra information loss.

2. Instead of running some sort of loop, in the solution I use df == 0 vectorization. df == 0 returns (try it) a matrix of the same size as df, with the entries TRUE and FALSE. Further, we are also allowed to pass this matrix to the subsetting [...] (see ?'['). Lastly, while the result of df[df == 0] is perfectly intuitive, it may seem strange that df[df == 0] <- NA gives the desired effect. The assignment operator <- is indeed not always so smart and does not work in this way with some other objects, but it does so with data frames; see ?'<-'.

1 The empty set in the set theory feels somehow related.
2 Another similarity with the set theory: the empty set is a subset of every set, but we do not reserve any space for it.

Parsing JSON Array within JSON Object

mainJSON.getJSONArray("source") returns a JSONArray, hence you can remove the new JSONArray.

The JSONArray contructor with an object parameter expects it to be a Collection or Array (not JSONArray)

Try this:

JSONArray jsonMainArr = mainJSON.getJSONArray("source"); 

Div vertical scrollbar show

Have you tried overflow-y:auto ? It is not exactly what you want, as the scrollbar will appear only when needed.

How to change python version in anaconda spyder

If you want to keep python 3, you can follow these directions to create a python 2.7 environment, called py27.

Then you just need to activate py27:

$ conda activate py27

Then you can install spyder on this environment, e.g.:

$ conda install spyder

Then you can start spyder from the command line or navigate to 2.7 version of spyder.exe below the envs directory (e.g. C:\ProgramData\Anaconda3\envs\py27\Scripts)

node.js http 'get' request with query string parameters

No need for a 3rd party library. Use the nodejs url module to build a URL with query parameters:

const requestUrl = url.parse(url.format({
    protocol: 'https',
    hostname: '',
    pathname: '/the/path',
    query: {
        key: value

Then make the request with the formatted url. requestUrl.path will include the query parameters.

const req = https.get({
    hostname: requestUrl.hostname,
    path: requestUrl.path,
}, (res) => {
   // ...

How do I bind onchange event of a TextBox using JQuery?

if you're trying to use jQuery autocomplete plugin, then I think you don't need to bind to onChange event, it will

How to POST JSON data with Python Requests?

It turns out I was missing the header information. The following works:

url = "http://localhost:8080"
data = {'sender': 'Alice', 'receiver': 'Bob', 'message': 'We did it!'}
headers = {'Content-type': 'application/json', 'Accept': 'text/plain'}
r =, data=json.dumps(data), headers=headers)

angularjs make a simple countdown

You should use $scope.$apply() when you execute an angular expression from outside of the angular framework.

function countController($scope){
    $scope.countDown = 10;    
    var timer = setInterval(function(){
    }, 1000);  

ReSharper "Cannot resolve symbol" even when project builds

I am using VS2015, R#10. None of the suggested solution worked for me. I deleted the contents of the bin folder of my solution and rebuild the entire solution, that seems to have resolved the issue. Before deleting the contents of the bin folder, I had tried suspending and resuming R#, doing clear cache from R# -> option -> general setting, and also manually deleting the contents from \AppData\Local\JetBrains\Transient\ReSharperPlatformVs12\v01\SolutionCaches.. Hope it helps someone.

What are Runtime.getRuntime().totalMemory() and freeMemory()?

According to the API


Returns the total amount of memory in the Java virtual machine. The value returned by this method may vary over time, depending on the host environment. Note that the amount of memory required to hold an object of any given type may be implementation-dependent.


Returns the maximum amount of memory that the Java virtual machine will attempt to use. If there is no inherent limit then the value Long.MAX_VALUE will be returned.


Returns the amount of free memory in the Java Virtual Machine. Calling the gc method may result in increasing the value returned by freeMemory.

In reference to your question, maxMemory() returns the -Xmx value.

You may be wondering why there is a totalMemory() AND a maxMemory(). The answer is that the JVM allocates memory lazily. Lets say you start your Java process as such:

java -Xms64m -Xmx1024m Foo

Your process starts with 64mb of memory, and if and when it needs more (up to 1024m), it will allocate memory. totalMemory() corresponds to the amount of memory currently available to the JVM for Foo. If the JVM needs more memory, it will lazily allocate it up to the maximum memory. If you run with -Xms1024m -Xmx1024m, the value you get from totalMemory() and maxMemory() will be equal.

Also, if you want to accurately calculate the amount of used memory, you do so with the following calculation :

final long usedMem = totalMemory() - freeMemory();

Why does JS code "var a = document.querySelector('a[data-a=1]');" cause error?

Because you need parentheses around the value your looking for. So here : document.querySelector('a[data-a="1"]')

If you don't know in advance the value but is looking for it via variable you can use template literals :

Say we have divs with data-price

<div data-price="99">My okay price</div>
<div data-price="100">My too expensive price</div>

We want to find an element but with the number that someone chose (so we don't know it):

// User chose 99    
let chosenNumber = 99

Printing all global variables/local variables?

In addition, since info locals does not display the arguments to the function you're in, use

(gdb) info args

For example:

int main(int argc, char *argv[]) {
    argc = 6*7;    //Break here.
    return 0;

argc and argv won't be shown by info locals. The message will be "No locals."

Reference: info locals command.

Using Excel VBA to run SQL query

Below is code that I currently use to pull data from a MS SQL Server 2008 into VBA. You need to make sure you have the proper ADODB reference [VBA Editor->Tools->References] and make sure you have Microsoft ActiveX Data Objects 2.8 Library checked, which is the second from the bottom row that is checked (I'm using Excel 2010 on Windows 7; you might have a slightly different ActiveX version, but it will still begin with Microsoft ActiveX):

References required for SQL

Sub Module for Connecting to MS SQL with Remote Host & Username/Password

Sub Download_Standard_BOM()
'Initializes variables
Dim cnn As New ADODB.Connection
Dim rst As New ADODB.Recordset
Dim ConnectionString As String
Dim StrQuery As String

'Setup the connection string for accessing MS SQL database
   'Make sure to change:
       '1: PASSWORD
       '2: USERNAME
       '4: DATABASE
    ConnectionString = "Provider=SQLOLEDB.1;Password=PASSWORD;Persist Security Info=True;User ID=USERNAME;Data Source=REMOTE_IP_ADDRESS;Use Procedure for Prepare=1;Auto Translate=True;Packet Size=4096;Use Encryption for Data=False;Tag with column collation when possible=False;Initial Catalog=DATABASE"

    'Opens connection to the database
    cnn.Open ConnectionString
    'Timeout error in seconds for executing the entire query; this will run for 15 minutes before VBA timesout, but your database might timeout before this value
    cnn.CommandTimeout = 900

    'This is your actual MS SQL query that you need to run; you should check this query first using a more robust SQL editor (such as HeidiSQL) to ensure your query is valid
    StrQuery = "SELECT TOP 10 * FROM tbl_table"

    'Performs the actual query
    rst.Open StrQuery, cnn
    'Dumps all the results from the StrQuery into cell A2 of the first sheet in the active workbook
    Sheets(1).Range("A2").CopyFromRecordset rst
End Sub

Object cannot be cast from DBNull to other types

For others that arrive on this page from google:

DataRow also has a function .IsNull("ColumnName")

    public DateTime? TestDt; 
    public Parse(DataRow row)
        if (!row.IsNull("TEST_DT"))
            TestDt = Convert.ToDateTime(row["TEST_DT"]);

Making authenticated POST requests with Spring RestTemplate for Android

Slightly different approach:

MultiValueMap<String, String> headers = new LinkedMultiValueMap<String, String>();
headers.add("HeaderName", "value");
headers.add("Content-Type", "application/json");

RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());

HttpEntity<ObjectToPass> request = new HttpEntity<ObjectToPass>(objectToPass, headers);

restTemplate.postForObject(url, request, ClassWhateverYourControllerReturns.class);

on change event for file input element

Use the files filelist of the element instead of val()


Python error: AttributeError: 'module' object has no attribute

When you import lib, you're importing the package. The only file to get evaluated and run in this case is the 0 byte in the lib directory.

If you want access to your function, you can do something like this from lib.mod1 import mod1 and then run the mod12 function like so mod1.mod12().

If you want to be able to access mod1 when you import lib, you need to put an import mod1 inside the file inside the lib directory.

React PropTypes : Allow different types of PropTypes for one prop

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

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

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

Delaying AngularJS route change until model loaded to prevent flicker

I see some people asking how to do this using the angular.controller method with minification friendly dependency injection. Since I just got this working I felt obliged to come back and help. Here's my solution (adopted from the original question and Misko's answer):

angular.module('phonecat', ['phonecatFilters', 'phonecatServices', 'phonecatDirectives']).
  config(['$routeProvider', function($routeProvider) {
      when('/phones', {
        templateUrl: 'partials/phone-list.html', 
        controller: PhoneListCtrl, 
        resolve: { 
            phones: ["Phone", "$q", function(Phone, $q) {
                var deferred = $q.defer();
                Phone.query(function(successData) {
                }, function(errorData) {
                  deferred.reject(); // you could optionally pass error data here
                return deferred.promise;
            delay: ["$q","$defer", function($q, $defer) {
               var delay = $q.defer();
               $defer(delay.resolve, 1000);
               return delay.promise;

      when('/phones/:phoneId', {
        templateUrl: 'partials/phone-detail.html', 
        controller: PhoneDetailCtrl, 
        resolve: PhoneDetailCtrl.resolve}).
      otherwise({redirectTo: '/phones'});

angular.controller("PhoneListCtrl", [ "$scope", "phones", ($scope, phones) {
  $scope.phones = phones;
  $scope.orderProp = 'age';

Since this code is derived from the question/most popular answer it is untested, but it should send you in the right direction if you already understand how to make minification friendly angular code. The one part that my own code didn't requires was an injection of "Phone" into the resolve function for 'phones', nor did I use any 'delay' object at all.

I also recommend this youtube video , which helped me quite a bit

Should it interest you I've decided to also paste my own code (Written in coffeescript) so you can see how I got it working.

FYI, in advance I use a generic controller that helps me do CRUD on several models:

appModule.config ['$routeProvider', ($routeProvider) ->
  genericControllers = ["boards","teachers","classrooms","students"]
  for controllerName in genericControllers
      .when "/#{controllerName}/",
        action: 'confirmLogin'
        controller: 'GenericController'
        controllerName: controllerName
        templateUrl: "/static/templates/#{controllerName}.html"
          items : ["$q", "$route", "$http", ($q, $route, $http) ->
             deferred = $q.defer()
             controllerName = $route.current.controllerName
               method: "GET"
               url: "/api/#{controllerName}/"
             .success (response) ->
             .error (response) ->

             return deferred.promise

      redirectTo: '/'
      action: 'checkStatus'

appModule.controller "GenericController", ["$scope", "$route", "$http", "$cookies", "items", ($scope, $route, $http, $cookies, items) ->

  $scope.items = items
      #etc ....

Storing database records into array

$memberId =$_SESSION['TWILLO']['Id'];

    $QueryServer=mysql_query("select * from smtp_server where memberId='".$memberId."'");
    $data = array();

     $data[$ser['Id']] =array('ServerName','ServerPort','Server_limit','email','password','status');


How to use environment variables in docker compose

You cannot ... yet. But this is an alternative, think like a docker-composer.yml generator:

Basically a shell script that will replace your variables. Also you can use Grunt task to build your docker compose file at the end of your CI process.

Swift addsubview and remove it

Assuming you have access to it via outlets or programmatic code, you can remove it by referencing your view foo and the removeFromSuperview method


Using PropertyInfo to find out the property type

I just stumbled upon this great post. If you are just checking whether the data is of string type then maybe we can skip the loop and use this struct (in my humble opinion)

public static bool IsStringType(object data)
        return (data.GetType().GetProperties().Where(x => x.PropertyType == typeof(string)).FirstOrDefault() != null);

Removing the textarea border in HTML

This one is great:

<style type="text/css">
width: 100%;
height: 100%;
border-color: Transparent;     
<textarea class="test"></textarea>

Does Java read integers in little endian or big endian?

Java is 'Big-endian' as noted above. That means that the MSB of an int is on the left if you examine memory (on an Intel CPU at least). The sign bit is also in the MSB for all Java integer types.
Reading a 4 byte unsigned integer from a binary file stored by a 'Little-endian' system takes a bit of adaptation in Java. DataInputStream's readInt() expects Big-endian format.
Here's an example that reads a four byte unsigned value (as displayed by HexEdit as 01 00 00 00) into an integer with a value of 1:

 // Declare an array of 4 shorts to hold the four unsigned bytes
 short[] tempShort = new short[4];
 for (int b = 0; b < 4; b++) {
    tempShort[b] = (short)dIStream.readUnsignedByte();           
 int curVal = convToInt(tempShort);

 // Pass an array of four shorts which convert from LSB first 
 public int convToInt(short[] sb)
   int answer = sb[0];
   answer += sb[1] << 8;
   answer += sb[2] << 16;
   answer += sb[3] << 24;
   return answer;        

CSS ''background-color" attribute not working on checkbox inside <div>

My solution

Initially posted here.

input[type="checkbox"] {_x000D_
  cursor: pointer;_x000D_
  -webkit-appearance: none;_x000D_
  -moz-appearance: none;_x000D_
  appearance: none;_x000D_
  outline: 0;_x000D_
  background: lightgray;_x000D_
  height: 16px;_x000D_
  width: 16px;_x000D_
  border: 1px solid white;_x000D_
input[type="checkbox"]:checked {_x000D_
  background: #2aa1c0;_x000D_
input[type="checkbox"]:hover {_x000D_
  filter: brightness(90%);_x000D_
input[type="checkbox"]:disabled {_x000D_
  background: #e6e6e6;_x000D_
  opacity: 0.6;_x000D_
  pointer-events: none;_x000D_
input[type="checkbox"]:after {_x000D_
  content: '';_x000D_
  position: relative;_x000D_
  left: 40%;_x000D_
  top: 20%;_x000D_
  width: 15%;_x000D_
  height: 40%;_x000D_
  border: solid #fff;_x000D_
  border-width: 0 2px 2px 0;_x000D_
  transform: rotate(45deg);_x000D_
  display: none;_x000D_
input[type="checkbox"]:checked:after {_x000D_
  display: block;_x000D_
input[type="checkbox"]:disabled:after {_x000D_
  border-color: #7b7b7b;_x000D_
<input type="checkbox"><br>_x000D_
<input type="checkbox" checked><br>_x000D_
<input type="checkbox" disabled><br>_x000D_
<input type="checkbox" disabled checked><br>

CSS disable hover effect

     background-color: unset !important;
    color: unset !important;

Have bash script answer interactive prompts

In my situation I needed to answer some questions without Y or N but with text or blank. I found the best way to do this in my situation was to create a shellscript file. In my case I called it

I was needing to answer some questions for a doctrine schema exporter so my file looked like this.

-- This is an example only --

php vendor/bin/mysql-workbench-schema-export mysqlworkbenchfile.mwb ./doctrine << EOF
`#Export to Doctrine Annotation Format`                                     1
`#Would you like to change the setup configuration before exporting`        y
`#Log to console`                                                           y
`#Log file`                                                                 testing.log
`#Filename [%entity%.%extension%]`
`#Indentation [4]`
`#Use tabs [no]`
`#Eol delimeter (win, unix) [win]`
`#Backup existing file [yes]`
`#Add generator info as comment [yes]`
`#Skip plural name checking [no]`
`#Use logged storage [no]`
`#Sort tables and views [yes]`
`#Export only table categorized []`
`#Enhance many to many detection [yes]`
`#Skip many to many tables [yes]`
`#Bundle namespace []`
`#Entity namespace []`
`#Repository namespace []`
`#Use automatic repository [yes]`
`#Skip column with relation [no]`
`#Related var name format [%name%%related%]`
`#Nullable attribute (auto, always) [auto]`
`#Generated value strategy (auto, identity, sequence, table, none) [auto]`
`#Default cascade (persist, remove, detach, merge, all, refresh, ) [no]`
`#Use annotation prefix [ORM\]`
`#Skip getter and setter [no]`
`#Generate entity serialization [yes]`
`#Generate extendable entity [no]`                                          y
`#Quote identifier strategy (auto, always, none) [auto]`
`#Extends class []`
`#Property typehint [no]`

The thing I like about this strategy is you can comment what your answers are and using EOF a blank line is just that (the default answer). Turns out by the way this exporter tool has its own JSON counterpart for answering these questions, but I figured that out after I did this =).

to run the script simply be in the directory you want and run 'sh' in terminal.

In short by using << EOL & EOF in combination with Return Lines you can answer each question of the prompt as necessary. Each new line is a new answer.

My example just shows how this can be done with comments also using the ` character so you remember what each step is.

Note the other advantage of this method is you can answer with more then just Y or N ... in fact you can answer with blanks!

Hope this helps someone out.

JavaScript alert not working in Android WebView

You can try with this, it worked for me

WebView wb_previewSurvey=new WebView(this); 

       wb_previewSurvey.setWebChromeClient(new WebChromeClient() {
        public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
            //Required functionality here
            return super.onJsAlert(view, url, message, result);


Remove Blank option from Select Option with AngularJS

There are multiple ways like -

<select ng-init="feed.config = options[0]" ng-model="feed.config"
        ng-options="template.value as for template in feed.configs">


$scope.feed.config = $scope.configs[0].name;

SELECT with LIMIT in Codeigniter

For further visitors:

// Executes: SELECT * FROM mytable LIMIT 10 OFFSET 20
// get([$table = ''[, $limit = NULL[, $offset = NULL]]])
$query = $this->db->get('mytable', 10, 20);

// get_where sample, 
$query = $this->db->get_where('mytable', array('id' => $id), 10, 20);

// Produces: LIMIT 10

// Produces: LIMIT 10 OFFSET 20
// limit($value[, $offset = 0])
$this->db->limit(10, 20);

Regular expression [Any number]

if("123".search(/^\d+$/) >= 0){
   // its a number

append option to select menu?

Something like this:

var option = document.createElement("option");
option.text = "Text";
option.value = "myvalue";
var select = document.getElementById("id-to-my-select-box");

Fatal error: Class 'PHPMailer' not found

Just from reading what you have written, you will need to add the file class.phpmailer.php to your directory as well.

Getting Serial Port Information

There is a post about this same issue on MSDN:

Getting more information about a serial port in C#

Hi Ravenb,

We can't get the information through the SerialPort type. I don't know why you need this info in your application. However, there's a solved thread with the same question as you. You can check out the code there, and see if it can help you.

If you have any further problem, please feel free to let me know.

Best regards, Bruce Zhou

The link in that post goes to this one:

How to get more info about port using System.IO.Ports.SerialPort

You can probably get this info from a WMI query. Check out this tool to help you find the right code. Why would you care though? This is just a detail for a USB emulator, normal serial ports won't have this. A serial port is simply know by "COMx", nothing more.

SQL Server r2 installation error .. update Visual Studio 2008 to SP1

Finally, I solved it. Even though the solution is a bit lengthy, I think its the simplest. The solution is as follows:

  1. Install Visual Studio 2008
  2. Install the service Package 1 (SP1)
  3. Install SQL Server 2008 r2

Tar a directory, but don't store full absolute paths in the archive

One minor detail:

tar -cjf site1.tar.bz2 -C /var/www/site1 .

adds the files as

tar -tf site1.tar.bz2

If you really want

tar -tf site1.tar.bz2

You should either cd into the directory first or run

tar -cjf site1.tar.bz2 -C /var/www/site1 $(ls /var/www/site1)

Couldn't load memtrack module Logcat Error

do you called the ViewTreeObserver and not remove it.

    mEtEnterlive.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
         // do nothing here can cause such problem

How to save a plot as image on the disk?

If you want to keep seeing the plot in R, another option is to use dev.copy:

X11 ()
plot (x,y)

dev.copy(jpeg,filename="plot.jpg"); ();

If you reach a clutter of too many plot windows in R, use to close all of the plot windows.

Display alert message and redirect after click on accept

that worked but try it this way.

echo "<script>
alert('There are no fields to generate a report');

alert on top then location next

How to replace a character by a newline in Vim

But if one has to substitute, then the following thing works:


In the above, every next line is substituted with next line, and then |- and again a new line. This is used in wiki tables.

If the text is as follows:


It is changed to


Difference between "Complete binary tree", "strict binary tree","full binary Tree"?

Full binary tree are a complete binary tree but reverse is not possible, and if the depth of the binary is n the no. of nodes in the full binary tree is ( 2^n-1 ). It is not necessary in the binary tree that it have two child but in the full binary it every node have no or two child.

Error: Local workspace file ('angular.json') could not be found

For people who have simply cloned a project and trying to run it, you need to run npm install first. I totally forgot to run this and was simply running ng serve before installing node modules.

I need to convert an int variable to double

Either use casting as others have already said, or multiply one of the int variables by 1.0:

double firstSolution = ((1.0* b1 * a22 - b2 * a12) / (a11 * a22 - a12 * a21));

Select a dummy column with a dummy value in SQL?

Try this:

select col1, col2, 'ABC' as col3 from Table1 where col1 = 0;

SQL Server Creating a temp table for this query

If you want to create a temp table after check exist table.You can use the following code

DROP TABLE IF EXISTS tempdb.dbo.#temptable
CREATE TABLE #temptable
   SiteName             NVARCHAR(50),
   BillingMonth         varchar(10),
   Consumption          INT,

After creating the temporary table, you can insert data into this table as a regular table:

INSERT INTO #temptable


INSERT INTO #temptable
VALUES (value1, value2, value3, ...);

The SELECT statement is used to select data from a temp table.

SELECT * FROM #temptable

you can manually remove the temporary table by using the DROP TABLE statement:

DROP TABLE #temptable;

Spring Maven clean error - The requested profile "pom.xml" could not be activated because it does not exist

I was getting this same warning everytime I was doing 'maven clean'. I found the solution :

Step - 1 Right click on your project in Eclipse

Step - 2 Click Properties

Step - 3 Select Maven in the left hand side list.

Step - 4 You will notice "pom.xml" in the Active Maven Profiles text box on the right hand side. Clear it and click Apply.

Below is the screen shot :

Properties dialog box

Hope this helps. :)

Converting an integer to a string in PHP

There are a number of ways to "convert" an integer to a string in PHP.

The traditional computer science way would be to cast the variable as a string:

$int = 5;
$int_as_string = (string) $int;
echo $int . ' is a '. gettype($int) . "\n";
echo $int_as_string . ' is a ' . gettype($int_as_string) . "\n";

You could also take advantage of PHP's implicit type conversion and string interpolation:

$int = 5;
echo $int . ' is a '. gettype($int) . "\n";

$int_as_string = "$int";
echo $int_as_string . ' is a ' . gettype($int_as_string) . "\n";

$string_int = $int.'';
echo $int_as_string . ' is a ' . gettype($int_as_string) . "\n";

Finally, similar to the above, any function that accepts and returns a string could be used to convert and integer. Consider the following:

$int = 5;
echo $int . ' is a '. gettype($int) . "\n";

$int_as_string = trim($int);
echo $int_as_string . ' is a ' . gettype($int_as_string) . "\n";

I wouldn't recommend the final option, but I've seen code in the wild that relied on this behavior, so thought I'd pass it along.

How to debug Apache mod_rewrite

The LogRewrite directive as mentioned by Ben is not available anymore in Apache 2.4. You need to use the LogLevel directive instead. E.g.

LogLevel alert rewrite:trace6


Declaring abstract method in TypeScript

I use to throw an exception in the base class.

protected abstractMethod() {
    throw new Error("abstractMethod not implemented");

Then you have to implement in the sub-class. The cons is that there is no build error, but run-time. The pros is that you can call this method from the super class, assuming that it will work :)



excel vba getting the row,cell value from selection.address

Dim f as Range

Set f=ActiveSheet.Cells.Find(...)

If Not f Is Nothing then
    msgbox "Row=" & f.Row & vbcrlf & "Column=" & f.Column
    msgbox "value not found!"
End If

What does DIM stand for in Visual Basic and BASIC?

It stands for Dimension, but is generally read as "Create Variable," or "Allocate Space for This."

Check whether an input string contains a number in javascript

function validate(){    
    var re = /^[A-Za-z]+$/;
       alert('Valid Name.');
       alert('Invalid Name.');      

handle textview link click in my android app

Example: Suppose you have set some text in textview and you want to provide a link on a particular text expression: "Click on #facebook will take you to"

In layout xml:

            android:layout_height="wrap_content" />

In Activity:

String text  =  "Click on #facebook will take you to";
Pattern tagMatcher = Pattern.compile("[#]+[A-Za-z0-9-_]+\\b");
String newActivityURL = "content://ankit.testactivity/";
Linkify.addLinks(tv, tagMatcher, newActivityURL);

Also create one tag provider as:

public class TagProvider extends ContentProvider {

    public int delete(Uri arg0, String arg1, String[] arg2) {
        // TODO Auto-generated method stub
        return 0;

    public String getType(Uri arg0) {
        return "";

    public Uri insert(Uri arg0, ContentValues arg1) {
        // TODO Auto-generated method stub
        return null;

    public boolean onCreate() {
        // TODO Auto-generated method stub
        return false;

    public Cursor query(Uri arg0, String[] arg1, String arg2, String[] arg3,
                        String arg4) {
        // TODO Auto-generated method stub
        return null;

    public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {
        // TODO Auto-generated method stub
        return 0;


In manifest file make as entry for provider and test activity as:

    android:authorities="ankit.testactivity" />

<activity android:name=".TestActivity"
    android:label = "@string/app_name">
    <intent-filter >
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <data android:mimeType="" />

Now when you click on #facebook, it will invoke testactivtiy. And in test activity you can get the data as:

Uri uri = getIntent().getData();

How to write header row with csv.DictWriter?

In 2.7 / 3.2 there is a new writeheader() method. Also, John Machin's answer provides a simpler method of writing the header row.
Simple example of using the writeheader() method now available in 2.7 / 3.2:

from collections import OrderedDict
ordered_fieldnames = OrderedDict([('field1',None),('field2',None)])
with open(outfile,'wb') as fou:
    dw = csv.DictWriter(fou, delimiter='\t', fieldnames=ordered_fieldnames)
    # continue on to write data

Instantiating DictWriter requires a fieldnames argument.
From the documentation:

The fieldnames parameter identifies the order in which values in the dictionary passed to the writerow() method are written to the csvfile.

Put another way: The Fieldnames argument is required because Python dicts are inherently unordered.
Below is an example of how you'd write the header and data to a file.
Note: with statement was added in 2.6. If using 2.5: from __future__ import with_statement

with open(infile,'rb') as fin:
    dr = csv.DictReader(fin, delimiter='\t')

# dr.fieldnames contains values from first row of `f`.
with open(outfile,'wb') as fou:
    dw = csv.DictWriter(fou, delimiter='\t', fieldnames=dr.fieldnames)
    headers = {} 
    for n in dw.fieldnames:
        headers[n] = n
    for row in dr:

As @FM mentions in a comment, you can condense header-writing to a one-liner, e.g.:

with open(outfile,'wb') as fou:
    dw = csv.DictWriter(fou, delimiter='\t', fieldnames=dr.fieldnames)
    dw.writerow(dict((fn,fn) for fn in dr.fieldnames))
    for row in dr:

Programmatic equivalent of default(Type)

This is optimized Flem's solution:

using System.Collections.Concurrent;

namespace System
    public static class TypeExtension
        //a thread-safe way to hold default instances created at run-time
        private static ConcurrentDictionary<Type, object> typeDefaults =
           new ConcurrentDictionary<Type, object>();

        public static object GetDefaultValue(this Type type)
            return type.IsValueType
               ? typeDefaults.GetOrAdd(type, Activator.CreateInstance)
               : null;

Installing MySQL in Docker fails with error message "Can't connect to local MySQL server through socket"

Don't know how do i achieve this, but, i've be able to reach MYSQL by typing

$ mysql -u root -h

  image: benftwc/pldev-webserver
    - ./
  working_dir: /var/www/
    - "8009:8009"
  command: php -S
    - database
  image: library/mysql
    - "3310:3306

root@422f4d1f454a:/# mysql -u root -h -p3310
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

root@422f4d1f454a:/# mysql -u root -h database -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g...........

Delete files older than 10 days using shell script in Unix

If you can afford working via the file data, you can do

find -mmin +14400 -delete

Inline <style> tags vs. inline css properties

I agree with the majority view that external stylesheets are the prefered method.

However, here are some practical exceptions:

  • Dynamic background images. CSS stylesheets are static files so you need to use an inline style to add a dynamic (from a database, CMS etc...) background-image style.

  • If an element needs to be hidden when the page loads, using an external stylesheet for this is not practical, since there will always be some delay before the stylesheet is processed and the element will be visible until that happens. style="display: none;" is the best way to achieve this.

  • If an application is going to give the user fine control over a particular CSS value, e.g. text color, then it may be necessary to add this to inline style elements or in-page <style></style> blocks. E.g. style="color:#{{ page.color }}", or <style> p.themed { color: #{{ page.color }}; }</style>

DB query builder toArray() laravel 4

try this one


just remove the "=" sign . . . .because you are trying to array just the name 'jhon' . . . . . . . .I hope it's help you . .

How to set the max value and min value of <input> in html5 by javascript or jquery?

Try this



Efficient way to insert a number into a sorted array of numbers?

function insertOrdered(array, elem) {
    let _array = array;
    let i = 0;
    while ( i < array.length && array[i] < elem ) {i ++};
    _array.splice(i, 0, elem);
    return _array;

How can I clear the Scanner buffer in Java?

This should fix it...

Scanner in=new Scanner(;
    int rounds = 0;
    while (rounds < 1 || rounds > 3) {
        System.out.print("How many rounds? ");
        if (in.hasNextInt()) {
            rounds = in.nextInt();
        } else {
            System.out.println("Invalid input. Please try again.");
  ; // -->important
        // Clear buffer
    System.out.print(rounds+" rounds.");

CSS Child vs Descendant selectors

div > p matches ps that have a div parent - <div><p> in your question

div p matches ps that have a div ancestor (parent, grandparent, great grandparent, etc.) - <div><p> and <div><div><p> in your question

glm rotate usage in Opengl

GLM has good example of rotation :

glm::mat4 Projection = glm::perspective(45.0f, 4.0f / 3.0f, 0.1f, 100.f);
glm::mat4 ViewTranslate = glm::translate(
    glm::vec3(0.0f, 0.0f, -Translate)
glm::mat4 ViewRotateX = glm::rotate(
    glm::vec3(-1.0f, 0.0f, 0.0f)
glm::mat4 View = glm::rotate(
    glm::vec3(0.0f, 1.0f, 0.0f)
glm::mat4 Model = glm::scale(
glm::mat4 MVP = Projection * View * Model;
glUniformMatrix4fv(LocationMVP, 1, GL_FALSE, glm::value_ptr(MVP));

download and install visual studio 2008

For Microsoft Visual C++ 2008, not the general Visual Studio (

Google Visual Studio 2008 Express instead of just Visual Studio 2008. Click to the first link that appears which is a download link from Microsoft mentioned above.

TypeError: 'builtin_function_or_method' object is not subscriptable

instead of writing listb.pop[0] write


HTML5 Form Input Pattern Currency Format

The best we could come up with is this:


I realize it might seem too much, but as far as I can test it matches anything that a human eye would accept as valid currency value and weeds out everything else.

It matches these:

1 => true
1.00 => true
$1 => true
$1000 => true
0.1 => true
1,000.00 => true
$1,000,000 => true
5678 => true

And weeds out these:

1.001 => false
02.0 => false
22,42 => false
001 => false => false
, => false
.55 => false
2000,000 => false

'Incorrect SET Options' Error When Building Database Project

According to BOL:

Indexed views and indexes on computed columns store results in the database for later reference. The stored results are valid only if all connections referring to the indexed view or indexed computed column can generate the same result set as the connection that created the index.

In order to create a table with a persisted, computed column, the following connection settings must be enabled:


These values are set on the database level and can be viewed using:

FROM sys.databases

However, the SET options can also be set by the client application connecting to SQL Server.

A perfect example is SQL Server Management Studio which has the default values for SET ANSI_NULLS and SET QUOTED_IDENTIFIER both to ON. This is one of the reasons why I could not initially duplicate the error you posted.

Anyway, to duplicate the error, try this (this will override the SSMS default settings):



You can fix the test case above by using:


I would recommend tweaking these two settings in your script before the creation of the table and related indexes.

What is .Net Framework 4 extended?

Got this from Bing. Seems Microsoft has removed some features from the core framework and added it to a separate optional(?) framework component.

To quote from MSDN (

The .NET Framework 4 Client Profile does not include the following features. You must install the .NET Framework 4 to use these features in your application:

* Advanced Windows Communication Foundation (WCF) functionality
* .NET Framework Data Provider for Oracle
* MSBuild for compiling

How to show only next line after the matched one?

I don't know of any way to do this with grep, but it is possible to use awk to achieve the same result:

awk '/blah/ {getline;print}' < logfile

Counting words in string

function totalWordCount() {
  var str ="My life is happy"
  var totalSoFar = 0;

  for (var i = 0; i < str.length; i++)
    if (str[i] === " ") { 
     totalSoFar = totalSoFar+1;
  totalSoFar = totalSoFar+ 1; 
  return totalSoFar


Add a pipe separator after items in an unordered list unless that item is the last on a line

Slightly modified SCSS version which gives you control of the pipe | size and will eliminate padding from first and last list items while respects borders.

$pipe-list-height: 20px;
$pipe-list-padding: 15px;

.pipe-list {
    position: relative;
    overflow: hidden;
    height: $pipe-list-height;

    > ul {
        display: flex;
        flex-direction: row;

        > li {
            position: relative;
            padding: 0 $pipe-list-padding;

            &:after {
                content: " ";
                position: absolute;
                border-right: 1px solid gray;
                top: 10%;
                right: 0;
                height: 75%;
                margin-top: auto;
                margin-bottom: auto;

            &:first-child {
                padding-left: 0;

            &:last-child {
                padding-right: 0;

                &:after {
                    border-right: none;
<div class="pipe-list">

How can I print to the same line?

First, I'd like to apologize for bringing this question back up, but I felt that it could use another answer.

Derek Schultz is kind of correct. The '\b' character moves the printing cursor one character backwards, allowing you to overwrite the character that was printed there (it does not delete the entire line or even the character that was there unless you print new information on top). The following is an example of a progress bar using Java though it does not follow your format, it shows how to solve the core problem of overwriting characters (this has only been tested in Ubuntu 12.04 with Oracle's Java 7 on a 32-bit machine, but it should work on all Java systems):

public class BackSpaceCharacterTest
    // the exception comes from the use of accessing the main thread
    public static void main(String[] args) throws InterruptedException
            Notice the user of print as opposed to println:
            the '\b' char cannot go over the new line char.
        System.out.print("Start[          ]");
        System.out.flush(); // the flush method prints it to the screen

        // 11 '\b' chars: 1 for the ']', the rest are for the spaces
        Thread.sleep(500); // just to make it easy to see the changes

        for(int i = 0; i < 10; i++)
            System.out.print("."); //overwrites a space

        System.out.print("] Done\n"); //overwrites the ']' + adds chars

What exactly is the function of Application.CutCopyMode property in Excel

By referring this( link the answer is as below:

Application.CutCopyMode=False is seen in macro recorder-generated code when you do a copy/cut cells and paste . The macro recorder does the copy/cut and paste in separate statements and uses the clipboard as an intermediate buffer. I think Application.CutCopyMode = False clears the clipboard. Without that line you will get the warning 'There is a large amount of information on the Clipboard....' when you close the workbook with a large amount of data on the clipboard.

With optimised VBA code you can usually do the copy/cut and paste operations in one statement, so the clipboard isn't used and Application.CutCopyMode = False isn't needed and you won't get the warning.

Use PHP to create, edit and delete crontab jobs?

Its simple You can you curl to do so, make sure curl installed on server :

for triggering every minute : * * * * * curl --request POST ''

        • *

    minute hour day month week

Let say you want to send this notification 2:15 PM everyday You may change POST/GET based on your API:

15 14 * * * curl --request POST 'url of ur API'

How to open port in Linux

First, you should disable selinux, edit file /etc/sysconfig/selinux so it looks like this:


Save file and restart system.

Then you can add the new rule to iptables:

iptables -A INPUT -m state --state NEW -p tcp --dport 8080 -j ACCEPT

and restart iptables with /etc/init.d/iptables restart

If it doesn't work you should check other network settings.

How do I tell Matplotlib to create a second (new) plot, then later plot on the old one?

One way I found after some struggling is creating a function which gets data_plot matrix, file name and order as parameter to create boxplots from the given data in the ordered figure (different orders = different figures) and save it under the given file_name.

def plotFigure(data_plot,file_name,order):
    fig = plt.figure(order, figsize=(9, 6))
    ax = fig.add_subplot(111)
    bp = ax.boxplot(data_plot)
    fig.savefig(file_name, bbox_inches='tight')

Can't pickle <type 'instancemethod'> when using multiprocessing

I ran into this same issue but found out that there is a JSON encoder that can be used to move these objects between processes.

from pyVmomi.VmomiSupport import VmomiJSONEncoder

Use this to create your list:

jsonSerialized = json.dumps(pfVmomiObj, cls=VmomiJSONEncoder)

Then in the mapped function, use this to recover the object:

pfVmomiObj = json.loads(jsonSerialized)

Convert this string to datetime

The Problem is with your code formatting,

inorder to use strtotime() You should replace '06/Oct/2011:19:00:02' with 06/10/2011 19:00:02 and date('d/M/Y:H:i:s', $date); with date('d/M/Y H:i:s', $date);. Note the spaces in between.

So the final code looks like this

$s = '06/10/2011 19:00:02';
$date = strtotime($s);
echo date('d/M/Y H:i:s', $date);

Switching users inside Docker image to a non-root user

You should not use su in a dockerfile, however you should use the USER instruction in the Dockerfile.

At each stage of the Dockerfile build, a new container is created so any change you make to the user will not persist on the next build stage.

For example:

RUN whoami
RUN su test
RUN whoami

This would never say the user would be test as a new container is spawned on the 2nd whoami. The output would be root on both (unless of course you run USER beforehand).

If however you do:

RUN whoami
USER test
RUN whoami

You should see root then test.

Alternatively you can run a command as a different user with sudo with something like

sudo -u test whoami

But it seems better to use the official supported instruction.

React - Component Full Screen (with height 100%)

I had trouble until i used the inspector and realized react puts everything inside a div with id='root' granting that 100% height along with body and html worked for me.

.htaccess, order allow, deny, deny from all: confused?

This is a quite confusing way of using Apache configuration directives.

Technically, the first bit is equivalent to

Allow From All

This is because Order Deny,Allow makes the Deny directive evaluated before the Allow Directives. In this case, Deny and Allow conflict with each other, but Allow, being the last evaluated will match any user, and access will be granted.

Now, just to make things clear, this kind of configuration is BAD and should be avoided at all cost, because it borders undefined behaviour.

The Limit sections define which HTTP methods have access to the directory containing the .htaccess file.

Here, GET and POST methods are allowed access, and PUT and DELETE methods are denied access. Here's a link explaining what the various HTTP methods are:

However, it's more than often useless to use these limitations as long as you don't have custom CGI scripts or Apache modules that directly handle the non-standard methods (PUT and DELETE), since by default, Apache does not handle them at all.

It must also be noted that a few other methods exist that can also be handled by Limit, namely CONNECT, OPTIONS, PATCH, PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, LOCK, and UNLOCK.

The last bit is also most certainly useless, since any correctly configured Apache installation contains the following piece of configuration (for Apache 2.2 and earlier):

# The following lines prevent .htaccess and .htpasswd files from being 
# viewed by Web clients. 
<Files ~ "^\.ht">
    Order allow,deny
    Deny from all
    Satisfy all

which forbids access to any file beginning by ".ht".

The equivalent Apache 2.4 configuration should look like:

<Files ~ "^\.ht">
    Require all denied

How can I get the data type of a variable in C#?

One option would be to use a helper extension method like follows:

public static class MyExtensions
    public static System.Type Type<T>(this T v)=>typeof(T);

var i=0;

Keystore change passwords

Keystore only has one password. You can change it using keytool:

keytool -storepasswd -keystore my.keystore

To change the key's password:

keytool -keypasswd  -alias <key_name> -keystore my.keystore

Gridview get Checkbox.Checked value

Try this,

Using foreach Loop:

foreach (GridViewRow row in GridView1.Rows)
     CheckBox chk = row.Cells[0].Controls[0] as CheckBox;
     if (chk != null && chk.Checked)
       // ...

Use it in OnRowCommand event and get checked CheckBox value.

GridViewRow row = (GridViewRow)(((Control)e.CommandSource).NamingContainer);
int requisitionId = Convert.ToInt32(e.CommandArgument);
CheckBox cbox = (CheckBox)row.Cells[3].Controls[0];

How can one print a size_t variable portably using the printf family?

For C89, use %lu and cast the value to unsigned long:

size_t foo;
printf("foo = %lu\n", (unsigned long) foo);

For C99 and later, use %zu:

size_t foo;
printf("foo = %zu\n", foo);

How do I drop a foreign key constraint only if it exists in sql server?

I think this will helpful to you...

    DECLARE @ConstraintName nvarchar(200)
    @ConstraintName = KCU.CONSTRAINT_NAME
IF @ConstraintName IS NOT NULL EXEC('alter table TABLE_NAME drop  CONSTRAINT ' + @ConstraintName)

It will delete foreign Key Constraint based on specific table and column.

Convert string to date in bash

date only work with GNU date (usually comes with Linux)

for OS X, two choices:

  1. change command (verified)

    #date -jf "%Y%m%d%H%M%S" $DATE "+date \"%A,%_d %B %Y %H:%M:%S\""
    date "Saturday, 1 August 2009 20:41:50"

  2. Download the GNU Utilities from Coreutils - GNU core utilities (not verified yet)

TypeError: Object of type 'bytes' is not JSON serializable

I guess the answer you need is referenced here Python sets are not json serializable

Not all datatypes can be json serialized . I guess pickle module will serve your purpose.

Opening popup windows in HTML

I feel like this is the simplest way. (Feel free to change the width and height values).

<a href="" 
onclick="'','popup','width=600,height=600'); return false;">
Link Text goes here...

Select columns from result set of stored procedure

To achieve this, first you create a #test_table like below:

create table #test_table(
    col1 int,
    col2 int,
    col80 int

Now execute procedure and put value in #test_table:

insert into #test_table
EXEC MyStoredProc 'param1', 'param2'

Now you fetch the value from #test_table:

select col1,col2....,col80 from #test_table

Does Hive have a String split function?

There does exist a split function based on regular expressions. It's not listed in the tutorial, but it is listed on the language manual on the wiki:

split(string str, string pat)
   Split str around pat (pat is a regular expression) 

In your case, the delimiter "|" has a special meaning as a regular expression, so it should be referred to as "\\|".

Tkinter example code for multiple windows, why won't buttons load correctly?

I rewrote your code in a more organized, better-practiced way:

import tkinter as tk

class Demo1:
    def __init__(self, master):
        self.master = master
        self.frame = tk.Frame(self.master)
        self.button1 = tk.Button(self.frame, text = 'New Window', width = 25, command = self.new_window)

    def new_window(self):
        self.newWindow = tk.Toplevel(self.master) = Demo2(self.newWindow)

class Demo2:
    def __init__(self, master):
        self.master = master
        self.frame = tk.Frame(self.master)
        self.quitButton = tk.Button(self.frame, text = 'Quit', width = 25, command = self.close_windows)

    def close_windows(self):

def main(): 
    root = tk.Tk()
    app = Demo1(root)

if __name__ == '__main__':


Demo1 window Demo2 window

"Cannot start compilation: the output path is not specified for module..."

Bugs caused by missing predefined folder for store compiled class file which is normally is /out folder by default. You can give a try to close Intellij > Import Project > From existing source. This will solve this problem.

mySQL convert varchar to date

As gratitude to the timely help I got from here - a minor update to above.

$query = "UPDATE `db`.`table` SET `fieldname`=  str_to_date(  fieldname, '%d/%m/%Y')";

CSS horizontal scroll

You can use display:inline-block with white-space:nowrap. Write like this:

.scrolls {
    overflow-x: scroll;
    overflow-y: hidden;
    height: 80px;
.imageDiv img {
    box-shadow: 1px 1px 10px #999;
    margin: 2px;
    max-height: 50px;
    cursor: pointer;
    *display:inline;/* For IE7*/
    *zoom:1;/* For IE7*/

Check this

Export multiple classes in ES6 modules

// export in index.js
export { default as Foo } from './Foo';
export { default as Bar } from './Bar';

// then import both
import { Foo, Bar } from 'my/module';

Insert into a MySQL table or update if exists

Any of these solution will work regarding your question:

INSERT IGNORE INTO table (id, name, age) VALUES (1, "A", 19);


INSERT INTO TABLE (id, name, age) VALUES(1, "A", 19) 


REPLACE INTO table (id, name, age) VALUES(1, "A", 19);

If you want to know in details regarding these statement visit this link

Execute bash script from URL

For bash, Bourne shell and fish:

curl -s http://server/path/ | bash -s arg1 arg2

Flag "-s" makes shell read from stdin.

Split Div Into 2 Columns Using CSS

Floats don't affect the flow. What I tend to do is add a

<p class="extro" style="clear: both">possibly some content</p>

at the end of the 'wrapping div' (in this case content). I can justify this on a semantic basis by saying that such a paragraph might be needed. Another approach is to use a clearfix CSS:

#content:after {
  content: ".";
  display: block;
  height: 0;
  clear: both;
  visibility: hidden;

#content {
  display: inline-block;
/*  \*/
* html #content {
  height: 1%;

#content {
  display: block;
/*  */

The trickery with the comments is for cross-browser compatibility.