Programs & Examples On #Jambi

Qt Jambi is a Java binding for the Qt library.

Java GUI frameworks. What to choose? Swing, SWT, AWT, SwingX, JGoodies, JavaFX, Apache Pivot?

My personal opinion: Go for Swing together with the NetBeans platform.

If you need advanced components (more than NetBeans offers) you can easily integrate SwingX without problems (or JGoodies) as the NetBeans platform is completely based on Swing.

I would not start a large desktop application (or one that is going to be large) without a good platform that is build upon the underlying UI framework.

The other option is SWT together with the Eclipse RCP, but it's harder (though not impossible) to integrate "pure" Swing components into such an application.

The learning curve is a bit steep for the NetBeans platform (although I guess that's true for Eclipse as well) but there are some good books around which I would highly recommend.

Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"?

In order to eliminate this error, you have to fo to the wp-config file and add these lines of code

define('WP_DEBUG_DISPLAY', false);

R command for setting working directory to source file location in Rstudio

For rstudio, you can automatically set your working directory to the script directory using rstudioapi like that:


# Getting the path of your current open file
current_path = rstudioapi::getActiveDocumentContext()$path 
setwd(dirname(current_path ))
print( getwd() )

This works when Running or Sourceing your file.

You need to install the package rstudioapi first. Notice I print the path to be 100% sure I'm at the right place, but this is optional.

What is the best way to prevent session hijacking?

The SSL only helps with sniffing attacks. If an attacker has access to your machine I will assume they can copy your secure cookie too.

At the very least, make sure old cookies lose their value after a while. Even a successful hijaking attack will be thwarted when the cookie stops working. If the user has a cookie from a session that logged in more than a month ago, make them reenter their password. Make sure that whenever a user clicks on your site's "log out" link, that the old session UUID can never be used again.

I'm not sure if this idea will work but here goes: Add a serial number into your session cookie, maybe a string like this:

SessionUUID, Serial Num, Current Date/Time

Encrypt this string and use it as your session cookie. Regularly change the serial num - maybe when the cookie is 5 minutes old and then reissue the cookie. You could even reissue it on every page view if you wanted to. On the server side, keep a record of the last serial num you've issued for that session. If someone ever sends a cookie with the wrong serial number it means that an attacker may be using a cookie they intercepted earlier so invalidate the session UUID and ask the user to reenter their password and then reissue a new cookie.

Remember that your user may have more than one computer so they may have more than one active session. Don't do something that forces them to log in again every time they switch between computers.

Convert `List<string>` to comma-separated string

In .NET 4 you don't need the ToArray() call - string.Join is overloaded to accept IEnumerable<T> or just IEnumerable<string>.

There are potentially more efficient ways of doing it before .NET 4, but do you really need them? Is this actually a bottleneck in your code?

You could iterate over the list, work out the final size, allocate a StringBuilder of exactly the right size, then do the join yourself. That would avoid the extra array being built for little reason - but it wouldn't save much time and it would be a lot more code.

MVC Redirect to View from jQuery with parameters

If your click handler is successfully called then this should work:

$('#results').on('click', '.item', function () {
            var NestId = $(this).data('id');
            var url = "/Artists/Details?NestId=" + NestId; 
            window.location.href = url; 

EDIT: In this particular case given that the action method parameter is a string which is nullable, then if NestId == null, won't cause any exception at all, given that the ModelBinder won't complain about it.

Override console.log(); for production

console.log = function(){};

Override it like any other thing.

How do you refresh the MySQL configuration file without restarting?

Specific actions you can do from SQL client and you don't need to restart anything:

SET GLOBAL log = 'ON';

SSIS Excel Import Forcing Incorrect Column Type

You can also alter the registry to look at more values than just the first 8 rows. I have used this method and works quite well.

High CPU Utilization in java application - why?

You may be victim of a garbage collection problem.

When your application requires memory and it's getting low on what it's configured to use the garbage collector will run often which consume a lot of CPU cycles. If it can't collect anything your memory will stay low so it will be run again and again. When you redeploy your application the memory is cleared and the garbage collection won't happen more than required so the CPU utilization stays low until it's full again.

You should check that there is no possible memory leak in your application and that it's well configured for memory (check the -Xmx parameter, see What does Java option -Xmx stand for?)

Also, what are you using as web framework? JSF relies a lot on sessions and consumes a lot of memory, consider being stateless at most!

Setting the default page for ASP.NET (Visual Studio) server configuration

Go to the project's properties page, select the "Web" tab and on top (in the "Start Action" section), enter the page name in the "Specific Page" box. In your case index.aspx

javascript date to string

use this polyfill

var d = new Date("1/1/2014 10:00 am");
d.format("DDDD 'the' DS 'of' MMMM YYYY h:mm TT");
//output: Wednesday the 1st of January 2014 10:00 AM

PowerShell and the -contains operator

-Contains is actually a collection operator. It is true if the collection contains the object. It is not limited to strings.

-match and -imatch are regular expression string matchers, and set automatic variables to use with captures.

-like, -ilike are SQL-like matchers.

Output of git branch in tree like fashion

The answer below uses git log:

I mentioned a similar approach in 2009 with "Unable to show a Git tree in terminal":

git log --graph --pretty=oneline --abbrev-commit

But the full one I have been using is in "How to display the tag name and branch name using git log --graph" (2011):

git config --global alias.lgb "log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset%n' --abbrev-commit --date=relative --branches"

git lgb

Original answer (2010)

git show-branch --list comes close of what you are looking for (with the topo order)


By default, the branches and their commits are shown in reverse chronological order.
This option makes them appear in topological order (i.e., descendant commits are shown before their parents).

But the tool git wtf can help too. Example:

$ git wtf
Local branch: master
[ ] NOT in sync with remote (needs push)
    - Add before-search hook, for shortcuts for custom search queries. [4430d1b] (edwardzyang@...; 7 days ago)
Remote branch: origin/master ([email protected]:sup/mainline.git)
[x] in sync with local

Feature branches:
{ } origin/release-0.8.1 is NOT merged in (1 commit ahead)
    - bump to 0.8.1 [dab43fb] (wmorgan-sup@...; 2 days ago)
[ ] labels-before-subj is NOT merged in (1 commit ahead)
    - put labels before subject in thread index view [790b64d] (marka@...; 4 weeks ago)
{x} origin/enclosed-message-display-tweaks merged in
(x) experiment merged in (only locally)

NOTE: working directory contains modified files

git-wtf shows you:

  • How your branch relates to the remote repo, if it's a tracking branch.
  • How your branch relates to non-feature ("version") branches, if it's a feature branch.
  • How your branch relates to the feature branches, if it's a version branch

Mailto: Body formatting

Use %0D%0A for a line break in your body

Example (Demo):

<a href="mailto:[email protected]?subject=Suggestions&body=name:%0D%0Aemail:">test</a>?

g++ ld: symbol(s) not found for architecture x86_64

finally solved my problem.

I created a new project in XCode with the sources and changed the C++ Standard Library from the default libc++ to libstdc++ as in this and this.

Mutex lock threads

Q1.) Assuming process B tries to take ownership of the same mutex you locked in process A (you left that out of your pseudocode) then no, process B cannot access sharedResource while the mutex is locked since it will sit waiting to lock the mutex until it is released by process A. It will return from the mutex_lock() function when the mutex is locked (or when an error occurs!)

Q2.) In Process B, ensure you always lock the mutex, access the shared resource, and then unlock the mutex. Also, check the return code from the mutex_lock( pMutex ) routine to ensure that you actually own the mutex, and ONLY unlock the mutex if you have locked it. Do the same from process A.

Both processes should basically do the same thing when accessing the mutex.
lock() If the lock succeeds, then { access sharedResource unlock() }

Q3.) Yes, there are lots of diagrams: =)

How to add new item to hash, value) - Stores a key-value pair in hash.


hash   #=> {"a"=>9, "b"=>200, "c"=>4}"d", 42) #=> 42
hash   #=> {"a"=>9, "b"=>200, "c"=>4, "d"=>42}


Retrieve the maximum length of a VARCHAR column in SQL Server

For sql server (SSMS)

select MAX(LEN(ColumnName)) from table_name

This will returns number of characters.

 select MAX(DATALENGTH(ColumnName)) from table_name

This will returns number of bytes used/required.

IF some one use varchar then use DATALENGTH.More details

log4net vs. Nlog

Having had an experience with both frameworks recently, I thought I can share my views on each frameworks.

I was asked to evaluate the logging frameworks for an existing web application, I narrowed down my choices to NLog (v2.0) and log4net (v1.2.11) after going through various online forums. Here are my findings:

  1. Setting/starting up with NLog is dead easy. You go through the Getting started tutorial on their website and you are done. You get a fair idea, how thing might be with nlog. Config file is so intuitive that anyone can understand the config. For example: if you want to set the internal logging on, you set the flag in Nlog config file's header node, which is where you would expect it to be. In log4net, you set different flags in web.config's appSettings section.

  2. In log4net, internal logging doesnt output timestamp which is annoying. In Nlog, you get a nice log with timestamps. I found it very useful in my evaluations.

  3. Filters in log4net - You better check my this question - log4net filter - how to write AND filter to ignore log messages and if you find an answer/solution for this, please let me know. I understand, there is a workaround for this question, as you can write your own custom filter. But something which is not easily available in log4net.

  4. Performance - I logged around 3000 log messages to database using a stored procedure. I used simple for loop (int i=0; i<3000; i++... to log the same message 3000 times. For the writes: log4net AdoAppender took almost double the time than NLog.

  5. Log4net doesnt support asynchronous appender.

It was sufficient comparison for me to choose NLog as the logging framework. :)

SQL SELECT everything after a certain character

select SUBSTRING_INDEX(supplier_reference,'=',-1) from ps_product;

Please use for further reference.

Where is the Keytool application?

For me it turned out to be in c/Program Files/Java/jdk1.7.0_25/bin (Windows 8). A more general answer to this question is that it will most likely be in the bin sub directory of wherever your jdk is installed.

How to automatically reload a page after a given period of inactivity

If you want to refresh the page if there is no activity then you need to figure out how to define activity. Let's say we refresh the page every minute unless someone presses a key or moves the mouse. This uses jQuery for event binding:

     var time = new Date().getTime();
     $(document.body).bind("mousemove keypress", function(e) {
         time = new Date().getTime();

     function refresh() {
         if(new Date().getTime() - time >= 60000) 
             setTimeout(refresh, 10000);

     setTimeout(refresh, 10000);

Cell Style Alignment on a range

  ExcelApp.Sheets[1].Range[ExcelApp.Sheets[1].Cells[1, 1], ExcelApp.Sheets[1].Cells[70, 15]].Cells.HorizontalAlignment =

This works fine for me.

How to concat two ArrayLists?

var arr3 = new arraylist();
for(int i=0, j=0, k=0; i<arr1.size()+arr2.size(); i++){

as you say, "the names and numbers beside each other".

How do I correctly clean up a Python object?

Just wrap your destructor with a try/except statement and it will not throw an exception if your globals are already disposed of.


Try this:

from weakref import proxy

class MyList(list): pass

class Package:
    def __init__(self):
        self.__del__.im_func.files = MyList([1,2,3,4])
        self.files = proxy(self.__del__.im_func.files)

    def __del__(self):
        print self.__del__.im_func.files

It will stuff the file list in the del function that is guaranteed to exist at the time of call. The weakref proxy is to prevent Python, or yourself from deleting the self.files variable somehow (if it is deleted, then it will not affect the original file list). If it is not the case that this is being deleted even though there are more references to the variable, then you can remove the proxy encapsulation.

How do I create/edit a Manifest file?

Go to obj folder in you app folder, then Debug. In there delete the manifest file and build again. It worked for me.

Converting A String To Hexadecimal In Java

A short and convenient way to convert a String to its Hexadecimal notation is:

public static void main(String... args){
String str = "Hello! This is test string.";
char ch[] = str.toCharArray();
StringBuilder sb = new StringBuilder();
    for (int i = 0; i < ch.length; i++) {
        sb.append(Integer.toHexString((int) ch[i]));

Java Can't connect to X11 window server using 'localhost:10.0' as the value of the DISPLAY variable

I have fixed this issue by logging in using Xorg. By default, I have used Wayland. It looks like Wayland eliminates most of the design flaws of the Xorg it has its own issues.enter image description here

How to turn on WCF tracing?

In your web.config (on the server) add

  <source name="System.ServiceModel" switchValue="Information, ActivityTracing" propagateActivity="true">
    <add name="traceListener" type="System.Diagnostics.XmlWriterTraceListener" initializeData="C:\logs\Traces.svclog"/>

Find all matches in workbook using Excel VBA

Based on the idea of B Hart's answer, here's my version of a function that searches for a value in a range, and returns all found ranges (cells):

Function FindAll(ByVal rng As Range, ByVal searchTxt As String) As Range
    Dim foundCell As Range
    Dim firstAddress
    Dim rResult As Range
    With rng
        Set foundCell = .Find(What:=searchTxt, _
                              After:=.Cells(.Cells.Count), _
                              LookIn:=xlValues, _
                              LookAt:=xlWhole, _
                              SearchOrder:=xlByRows, _
                              SearchDirection:=xlNext, _
        If Not foundCell Is Nothing Then
            firstAddress = foundCell.Address
                If rResult Is Nothing Then
                    Set rResult = foundCell
                    Set rResult = Union(rResult, foundCell)
                End If
                Set foundCell = .FindNext(foundCell)
            Loop While Not foundCell Is Nothing And foundCell.Address <> firstAddress
        End If
    End With

    Set FindAll = rResult
End Function

To search for a value in the whole workbook:

Dim wSh As Worksheet
Dim foundCells As Range
For Each wSh In ThisWorkbook.Worksheets
    Set foundCells = FindAll(wSh.UsedRange, "YourSearchString")
    If Not foundCells Is Nothing Then
        Debug.Print ("Results in sheet '" & wSh.Name & "':")
        Dim cell As Range
        For Each cell In foundCells
            Debug.Print ("The value has been found in cell: " & cell.Address)
    End If

How to allow Cross domain request in apache2

In httpd.conf

  1. Make sure these are loaded:
LoadModule headers_module modules/

LoadModule rewrite_module modules/
  1. In the target directory:
<Directory "**/usr/local/PATH**">
    AllowOverride None
    Require all granted

    Header always set Access-Control-Allow-Origin "*"
    Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
    Header always set Access-Control-Allow-Headers "x-requested-with, Content-Type, origin, authorization, accept, client-security-token"
    Header always set Access-Control-Expose-Headers "Content-Security-Policy, Location"
    Header always set Access-Control-Max-Age "600"

    RewriteEngine On
    RewriteRule ^(.*)$ $1 [R=200,L]


If running outside container, you may need to restart apache service.

Named capturing groups in JavaScript regex?

You can use XRegExp, an augmented, extensible, cross-browser implementation of regular expressions, including support for additional syntax, flags, and methods:

  • Adds new regex and replacement text syntax, including comprehensive support for named capture.
  • Adds two new regex flags: s, to make dot match all characters (aka dotall or singleline mode), and x, for free-spacing and comments (aka extended mode).
  • Provides a suite of functions and methods that make complex regex processing a breeze.
  • Automagically fixes the most commonly encountered cross-browser inconsistencies in regex behavior and syntax.
  • Lets you easily create and use plugins that add new syntax and flags to XRegExp's regular expression language.

Copy Image from Remote Server Over HTTP

This answer helped to me download image from server to client side.

<a download="original_file.jpg" href="file/path.jpg">
  <img src="file/path.jpg" class="img-responsive" width="600" />

Javascript for "Add to Home Screen" on iPhone?

In javascript, it is not possible but yes with the help of “Web Clips” we can create a "add to home screen" icon or shortcut in iPhone( by the code file of .mobileconfig)

after create a mobileconfig file we can pass this url in iphone safari browser install certificate and after done it check your iphone home screen there is a shortcut icon of your Web page or webapp..

Batch: Remove file extension

This is a really late response, but I came up with this to solve a particular problem I had with DiskInternals LinuxReader appending '.efs_ntfs' to files that it saved to non-NTFS (FAT32) directories :

@echo off
REM %1 is the directory to recurse through and %2 is the file extension to remove
for /R "%1" %%f in (*.%2) do (
    REM Path (sans drive) is given by %%~pf ; drive is given by %%~df
    REM file name (sans ext) is given by %%~nf ; to 'rename' files, move them
    copy "%%~df%%~pf%%~nf.%2" "%%~df%%~pf%%~nf"
    echo "%%~df%%~pf%%~nf.%2" copied to "%%~df%%~pf%%~nf"

Writing a dictionary to a csv file with one line for every 'key: value'

The DictWriter doesn't work the way you expect.

with open('dict.csv', 'w') as csv_file:  
    writer = csv.writer(csv_file)
    for key, value in mydict.items():
       writer.writerow([key, value])

To read it back:

with open('dict.csv') as csv_file:
    reader = csv.reader(csv_file)
    mydict = dict(reader)

which is quite compact, but it assumes you don't need to do any type conversion when reading

Setting java locale settings

I had to control this in a script that ran on a machine with French locale, but a specific Java program had to run with en_US. As already pointed out, the following works:

java -Duser.language=en ...


LC_ALL=en_US.UTF-8 java ...

I prefer the latter.

How to update MySql timestamp column to current timestamp on PHP?

Use this query:

UPDATE `table` SET date_date=now();

Sample code can be:

$con = mysql_connect("localhost","peter","abc123");
if (!$con)
  die('Could not connect: ' . mysql_error());

mysql_select_db("my_db", $con);

mysql_query("UPDATE `table` SET date_date=now()");


Python - Get path of root project structure


ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

How to copy text from a div to clipboard

I was getting selectNode() param 1 is not of type node error.

changed the code to this and its working. (for chrome)

function copy_data(containerid) {_x000D_
  var range = document.createRange();_x000D_
  range.selectNode(containerid); //changed here_x000D_
  window.getSelection().removeAllRanges(); _x000D_
  window.getSelection().addRange(range); _x000D_
  alert("data copied");_x000D_
<div id="select_txt">This will be copied to clipboard!</div>_x000D_
<button type="button" onclick="copy_data(select_txt)">copy</button>_x000D_
<p>Try paste it here after copying</p>_x000D_

jQuery get mouse position within an element

I would suggest this:

e.pageX - this.getBoundingClientRect().left

Int to Char in C#

int i = 65;
char c = Convert.ToChar(i);

PLS-00103: Encountered the symbol "CREATE"

At line 5 there is a / missing.

There is a good answer on the differences between ; and / here.

Basically, when running a CREATE block via script, you need to use / to let SQLPlus know when the block ends, since a PL/SQL block can contain many instances of ;.

Is SMTP based on TCP or UDP?

In theory SMTP can be handled by either TCP, UDP, or some 3rd party protocol.

As defined in RFC 821, RFC 2821, and RFC 5321:

SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel.

In addition, the Internet Assigned Numbers Authority has allocated port 25 for both TCP and UDP for use by SMTP.

In practice however, most if not all organizations and applications only choose to implement the TCP protocol. For example, in Microsoft's port listing port 25 is only listed for TCP and not UDP.

The big difference between TCP and UDP that makes TCP ideal here is that TCP checks to make sure that every packet is received and re-sends them if they are not whereas UDP will simply send packets and not check for receipt. This makes UDP ideal for things like streaming video where every single packet isn't as important as keeping a continuous flow of packets from the server to the client.

Considering SMTP, it makes more sense to use TCP over UDP. SMTP is a mail transport protocol, and in mail every single packet is important. If you lose several packets in the middle of the message the recipient might not even receive the message and if they do they might be missing key information. This makes TCP more appropriate because it ensures that every packet is delivered.

MySQL: Selecting multiple fields into multiple variables in a stored procedure


@martin clayton Answer is correct, But this is an advise only.

Please avoid the use of ambiguous variable in the stored procedure.

Example :

SELECT Id, dateCreated
INTO id, datecreated
FROM products
WHERE pName = iName

The above example will cause an error (null value error)

Example give below is correct. I hope this make sense.

Example :

SELECT Id, dateCreated
INTO val_id, val_datecreated
FROM products
WHERE pName = iName

You can also make them unambiguous by referencing the table, like:

[ Credit : maganap ]

SELECT p.Id, p.dateCreated INTO id, datecreated FROM products p 
WHERE pName = iName

How do I add a margin between bootstrap columns without wrapping

You should work with padding on the inner container rather than with margin. Try this!


<div class="row info-panel">
    <div class="col-md-4" id="server_1">
       <div class="server-action-menu">
           Server 1


.server-action-menu {
    background-color: transparent;
    background-image: linear-gradient(to bottom, rgba(30, 87, 153, 0.2) 0%, rgba(125, 185, 232, 0) 100%);
    background-repeat: repeat;
    padding: 5px;

What is the difference between a static method and a non-static method?

- First we must know that the diff bet static and non static methods 
is differ from static and non static variables : 

- this code explain static method - non static method and what is the diff 

    public class MyClass {
        static {
            System.out.println("this is static routine ... ");

          public static void foo(){
            System.out.println("this is static method ");

        public void blabla(){

         System.out.println("this is non static method ");

        public static void main(String[] args) {

           /* ***************************************************************************  
            * 1- in static method you can implement the method inside its class like :  *       
            * you don't have to make an object of this class to implement this method   *      
            *;          // this is correct                                *     
            * MyClass.blabla();       // this is not correct because any non static     *
            * method you must make an object from the class to access it like this :    *            
            * MyClass m = new MyClass();                                                *     
            * m.blabla();                                                               *    
            * ***************************************************************************/

            // access static method without make an object 

            MyClass m = new MyClass();
            // access non static method via make object 
              access static method make a warning but the code run ok 
               because you don't have to make an object from MyClass 
               you can easily call it; 
    /* output of the code */
    this is static routine ... 
    this is static method 
    this is non static method 
    this is static method

 - this code explain static method - non static Variables and what is the diff 

     public class Myclass2 {

                // you can declare static variable here : 
                // or you can write  int callCount = 0; 
                // make the same thing 
                //static int callCount = 0; = int callCount = 0;
                static int callCount = 0;    

                public void method() {
                    Can i declare a static variable inside static member function in Java?
                    - no you can't 
                    static int callCount = 0;  // error                                                   
                /* static variable */
                System.out.println("Calls in method (1) : " + callCount);

                public void method2() {
                int callCount2 = 0 ; 
                /* non static variable */   
                System.out.println("Calls in method (2) : " + callCount2);

            public static void main(String[] args) {
             Myclass2 m = new Myclass2();
             /* method (1) calls */
             /* method (2) calls */

        // output 

        // Calls in method (1) : 1
        // Calls in method (1) : 2
        // Calls in method (1) : 3
        // Calls in method (2) : 1
        // Calls in method (2) : 1
        // Calls in method (2) : 1 

How to change Bootstrap's global default font size?

You can add a style.css, import this file after the bootstrap.css to override this code.

For example:

/* bootstrap.css */
* {
   font-size: 14px;
   line-height: 1.428;

/* style.css */
* {
   font-size: 16px;
   line-height: 2;

Don't change bootstrap.css directly for better maintenance of code.

How do I pull my project from github?

Run these commands:

cd /pathToYourLocalProjectFolder

git pull origin master

The iOS Simulator deployment targets is set to 7.0, but the range of supported deployment target version for this platform is 8.0 to 12.1

Try these steps:

  1. Delete your Podfile.lock
  2. Delete your Podfile
  3. Build Project
  4. Add initialization code from firebase
  5. cd /ios
  6. pod install
  7. run Project

This was what worked for me.

Split data frame string column into multiple columns

Yet another approach: use rbind on out:

before <- data.frame(attr = c(1,30,4,6), type=c('foo_and_bar','foo_and_bar_2'))  
out <- strsplit(as.character(before$type),'_and_'), out)

     [,1]  [,2]   
[1,] "foo" "bar"  
[2,] "foo" "bar_2"
[3,] "foo" "bar"  
[4,] "foo" "bar_2"

And to combine:

data.frame(before$attr,, out))

how to make div click-able?

add the onclick attribute

<div onclick="myFunction( event );"><span>shanghai</span><span>male</span></div>

To get the cursor to change use css's cursor rule.

div[onclick] {
  cursor: pointer;

The selector uses an attribute selector which does not work in some versions of IE. If you want to support those versions, add a class to your div.

Hide "NFC Tag type not supported" error on Samsung Galaxy devices

Before Android 4.4

What you are trying to do is simply not possible from an app (at least not on a non-rooted/non-modified device). The message "NFC tag type not supported" is displayed by the Android system (or more specifically the NFC system service) before and instead of dispatching the tag to your app. This means that the NFC system service filters MIFARE Classic tags and never notifies any app about them. Consequently, your app can't detect MIFARE Classic tags or circumvent that popup message.

On a rooted device, you may be able to bypass the message using either

  1. Xposed to modify the behavior of the NFC service, or
  2. the CSC (Consumer Software Customization) feature configuration files on the system partition (see /system/csc/. The NFC system service disables the popup and dispatches MIFARE Classic tags to apps if the CSC feature <CscFeature_NFC_EnableSecurityPromptPopup> is set to any value but "mifareclassic" or "all". For instance, you could use:


    You could add this entry to, for instance, the file "/system/csc/others.xml" (within the section <FeatureSet> ... </FeatureSet> that already exists in that file).

Since, you asked for the Galaxy S6 (the question that you linked) as well: I have tested this method on the S4 when it came out. I have not verified if this still works in the latest firmware or on other devices (e.g. the S6).

Since Android 4.4

This is pure guessing, but according to this (link no longer available), it seems that some apps (e.g. NXP TagInfo) are capable of detecting MIFARE Classic tags on affected Samsung devices since Android 4.4. This might mean that foreground apps are capable of bypassing that popup using the reader-mode API (see NfcAdapter.enableReaderMode) possibly in combination with NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK.

How to generate a random alpha-numeric string

public static String getRandomString(int length)
    String randomStr = UUID.randomUUID().toString();
    while(randomStr.length() < length) {
        randomStr += UUID.randomUUID().toString();
    return randomStr.substring(0, length);

What is key=lambda

 >>> sorted(['Some', 'words', 'sort', 'differently'], key=lambda word: word.lower())

Actually, above codes can be:

>>> sorted(['Some','words','sort','differently'],key=str.lower)

According to, key specifies a function of one argument that is used to extract a comparison key from each list element: key=str.lower. The default value is None (compare the elements directly).

How to delete empty folders using windows command prompt?

A simpler way is to do xcopy to make a copy of the entire directory structure using /s switch. help for /s says Copies directories and subdirectories except empty ones.

xcopy dirA dirB /S

where dirA is source with Empty folders. DirB will be the copy without empty folders

Angular.js programmatically setting a form field to dirty

I'm not sure exactly why you're trying to mark the fields dirty, but I found myself in a similar situation because I wanted validation errors to show up when somebody attempted to submit an invalid form. I ended up using jQuery to remove the .ng-pristine class tags and add .ng-dirty class tags to the appropriate fields. For example:

$scope.submit = function() {
    // `formName` is the value of the `name` attribute on your `form` tag
    if (this.formName.$invalid)
        $('.ng-invalid:not("form")').each(function() {
        // the form element itself is index zero, so the first input is typically at index 1

How do I get into a Docker container's shell?

SSH into a Docker container using this command:

sudo docker exec -i -t (container ID) bash

How to match, but not capture, part of a regex?



That will match apple, banana, or a blank string, and following it there will be a 0 or 1 hyphens. I was wrong about not having a need for a capturing group. Silly me.

How do I fill arrays in Java?


in java

int arrnum[] ={5,6,9,2,10};
for(int i=0;i<arrnum.length;i++){
  System.out.println(arrnum[i]+" ");
for(int i=0;i<arrnum.length;i++){
  System.out.println(arrnum[i]+" ");


5 6 9 2 10
0 0 0 0 0

How to loop over grouped Pandas dataframe?

Here is an example of iterating over a pd.DataFrame grouped by the column atable. For this sample, "create" statements for an SQL database are generated within the for loop:

import pandas as pd

df1 = pd.DataFrame({
    'atable':     ['Users', 'Users', 'Domains', 'Domains', 'Locks'],
    'column':     ['col_1', 'col_2', 'col_a', 'col_b', 'col'],
    'column_type':['varchar', 'varchar', 'int', 'varchar', 'varchar'],
    'is_null':    ['No', 'No', 'Yes', 'No', 'Yes'],

df1_grouped = df1.groupby('atable')

# iterate over each group
for group_name, df_group in df1_grouped:
    print('\nCREATE TABLE {}('.format(group_name))

    for row_index, row in df_group.iterrows():
        col = row['column']
        column_type = row['column_type']
        is_null = 'NOT NULL' if row['is_null'] == 'NO' else ''
        print('\t{} {} {},'.format(col, column_type, is_null))


urllib2 and json

To read json response use json.loads(). Here is the sample.

import json
import urllib
import urllib2

post_params = {
    'foo' : bar

params = urllib.urlencode(post_params)
response = urllib2.urlopen(url, params)
json_response = json.loads(

Using jquery to get element's position relative to viewport

Here is a function that calculates the current position of an element within the viewport:

 * Calculates the position of a given element within the viewport
 * @param {string} obj jQuery object of the dom element to be monitored
 * @return {array} An array containing both X and Y positions as a number
 * ranging from 0 (under/right of viewport) to 1 (above/left of viewport)
function visibility(obj) {
    var winw = jQuery(window).width(), winh = jQuery(window).height(),
        elw = obj.width(), elh = obj.height(),
        o = obj[0].getBoundingClientRect(),
        x1 = o.left - winw, x2 = o.left + elw,
        y1 = - winh, y2 = + elh;

    return [
        Math.max(0, Math.min((0 - x1) / (x2 - x1), 1)),
        Math.max(0, Math.min((0 - y1) / (y2 - y1), 1))

The return values are calculated like this:


visibility($('#example'));  // returns [0.3742887830933581, 0.6103752759381899]


function visibility(obj) {var winw = jQuery(window).width(),winh = jQuery(window).height(),elw = obj.width(),_x000D_
    elh = obj.height(), o = obj[0].getBoundingClientRect(),x1 = o.left - winw, x2 = o.left + elw, y1 = - winh, y2 = + elh; return [Math.max(0, Math.min((0 - x1) / (x2 - x1), 1)),Math.max(0, Math.min((0 - y1) / (y2 - y1), 1))];_x000D_
setInterval(function() {_x000D_
  res = visibility($('#block'));_x000D_
  $('#x').text(Math.round(res[0] * 100) + '%');_x000D_
  $('#y').text(Math.round(res[1] * 100) + '%');_x000D_
}, 100);
#block { width: 100px; height: 100px; border: 1px solid red; background: yellow; top: 50%; left: 50%; position: relative;_x000D_
} #container { background: #EFF0F1; height: 950px; width: 1800px; margin-top: -40%; margin-left: -40%; overflow: scroll; position: relative;_x000D_
} #res { position: fixed; top: 0; z-index: 2; font-family: Verdana; background: #c0c0c0; line-height: .1em; padding: 0 .5em; font-size: 12px;_x000D_
<script src=""></script>_x000D_
<div id="res">_x000D_
  <p>X: <span id="x"></span></p>_x000D_
  <p>Y: <span id="y"></span></p>_x000D_
<div id="container"><div id="block"></div></div>

Find the most popular element in int[] array

This one without maps:

public class Main {       

    public static void main(String[] args) {
        int[] a = new int[]{ 1, 2, 3, 4, 5, 6, 7, 7, 7, 7 };

    private static int getMostPopularElement(int[] a) {             
        int maxElementIndex = getArrayMaximumElementIndex(a); 
        int[] b = new int[a[maxElementIndex] + 1]

        for (int i = 0; i < a.length; i++) {

        return getArrayMaximumElementIndex(b);

    private static int getArrayMaximumElementIndex(int[] a) {
        int maxElementIndex = 0;

        for (int i = 1; i < a.length; i++) {
            if (a[i] >= a[maxElementIndex]) {
                maxElementIndex = i;

        return maxElementIndex;


You only have to change some code if your array can have elements which are < 0. And this algorithm is useful when your array items are not big numbers.

jQuery Ajax Request inside Ajax Request

Here is an example:

        type: "post",
        url: "ajax/example.php",
        data: 'page=' + btn_page,
        success: function (data) {
            var a = data; // This line shows error.
                type: "post",
                url: "example.php",
                data: 'page=' + a,
                success: function (data) {


Powershell 2 copy-item which creates a folder if doesn't exist

I modified @FrinkTheBrave 's answer to also create sub-directories, and resolve relative paths:

$src_root = Resolve-Path("./source/path/")
$target_root = Resolve-Path("./target/path/")
$glob_filter = "*.*"
Get-ChildItem -path $src_root -filter $glob_filter -recurse | 
  ForEach-Object {
        $target_filename=($_.FullName -replace [regex]::escape($src_root),$target_root) 
        $target_path=Split-Path $target_filename
        if (!(Test-Path -Path $target_path)) {
            New-Item $target_path -ItemType Directory
        Copy-Item $_.FullName -destination $target_filename

Angularjs $http post file and form data

I was unable to get Pavel's answer working as in when posting to a Web.Api application.

The issue appears to be with the deleting of the headers.

delete headers['Content-Type'];

In order to ensure the browsers was allowed to default the Content-Type along with the boundary parameter, I needed to set the Content-Type to undefined. Using Pavel's example the boundary was never being set resulting in a 400 HTTP exception.

The key was to remove the code deleting the headers shown above and to set the headers content type to null manually. Thus allowing the browser to set the properties.

headers: {'Content-Type': undefined}

Here is a full example.

$scope.Submit = form => {
                    method: 'POST',
                    url: 'api/FileTest',
                    headers: {'Content-Type': undefined},
                    data: {
                        FullName: $scope.FullName,
                        Email: $scope.Email,
                        File1: $scope.file
                    transformRequest: function (data, headersGetter) {
                        var formData = new FormData();
                        angular.forEach(data, function (value, key) {
                            formData.append(key, value);
                        return formData;
                .success(function (data) {

                .error(function (data, status) {


                return false;

React Native Responsive Font Size

I managed to overcome this by doing the following.

  1. Pick the font size you like for the current view you have (Make sure it looks good for the current device you are using in the simulator).

  2. import { Dimensions } from 'react-native' and define the width outside of the component like so: let width = Dimensions.get('window').width;

  3. Now console.log(width) and write it down. If your good looking font size is 15 and your width is 360 for example, then take 360 and divide by 15 ( = 24). This is going to be the important value that is going to adjust to different sizes.

    Use this number in your styles object like so: textFontSize: { fontSize = width / 24 },...

Now you have a responsive fontSize.

Why do I get TypeError: can't multiply sequence by non-int of type 'float'?

Maybe this will help others in the future - I had the same error while trying to multiple a float and a list of floats. The thing is that everyone here talked about multiplying a float with a string (but here all my element were floats all along) so the problem was actually using the * operator on a list.

For example:

import math
import numpy as np
alpha = 0.2 
C = (-math.log(1-beta))/alpha

coff = [0.0,0.01,0.0,0.35,0.98,0.001,0.0]
coff *= C

The error:

    coff *= C 
TypeError: can't multiply sequence by non-int of type 'float'

The solution - convert the list to numpy array:

coff = np.asarray(coff) * C

How do you create nested dict in Python?

If you want to create a nested dictionary given a list (arbitrary length) for a path and perform a function on an item that may exist at the end of the path, this handy little recursive function is quite helpful:

def ensure_path(data, path, default=None, default_func=lambda x: x):

    - Ensures a path exists within a nested dictionary


    - `data`:
        - Type: dict
        - What: A dictionary to check if the path exists
    - `path`:
        - Type: list of strs
        - What: The path to check


    - `default`:
        - Type: any
        - What: The default item to add to a path that does not yet exist
        - Default: None

    - `default_func`:
        - Type: function
        - What: A single input function that takes in the current path item (or default) and adjusts it
        - Default: `lambda x: x` # Returns the value in the dict or the default value if none was present
    if len(path)>1:
        if path[0] not in data:
        data[path[0]]=ensure_path(data=data[path[0]], path=path[1:], default=default, default_func=default_func)
        if path[0] not in data:
    return data


ensure_path(data=data, path=['a','c'], default=[1])
print(data) #=> {'a':{'b':1, 'c':[1]}}
ensure_path(data=data, path=['a','c'], default=[1], default_func=lambda x:x+[2])
print(data) #=> {'a': {'b': 1, 'c': [1, 2]}}

Add views in UIStackView programmatically

    //Image View
    let imageView               = UIImageView()
    imageView.backgroundColor   = UIColor.blueColor()
    imageView.heightAnchor.constraintEqualToConstant(120.0).active = true
    imageView.widthAnchor.constraintEqualToConstant(120.0).active = true
    imageView.image = UIImage(named: "buttonFollowCheckGreen")

    //Text Label
    let textLabel               = UILabel()
    textLabel.backgroundColor   = UIColor.greenColor()
    textLabel.widthAnchor.constraintEqualToConstant(self.view.frame.width).active = true
    textLabel.heightAnchor.constraintEqualToConstant(20.0).active = true
    textLabel.text  = "Hi World"
    textLabel.textAlignment = .Center

    //Third View
    let thirdView               = UIImageView()
    thirdView.backgroundColor   = UIColor.magentaColor()
    thirdView.heightAnchor.constraintEqualToConstant(120.0).active = true
    thirdView.widthAnchor.constraintEqualToConstant(120.0).active = true
    thirdView.image = UIImage(named: "buttonFollowMagenta")

    //Stack View
    let stackView   = UIStackView()
    stackView.axis  = UILayoutConstraintAxis.Vertical
    stackView.distribution  = UIStackViewDistribution.EqualSpacing
    stackView.alignment = UIStackViewAlignment.Center
    stackView.spacing   = 16.0

    stackView.translatesAutoresizingMaskIntoConstraints = false;


    stackView.centerXAnchor.constraintEqualToAnchor(self.view.centerXAnchor).active = true
    stackView.centerYAnchor.constraintEqualToAnchor(self.view.centerYAnchor).active = true

Improved on the answer by @Oleg Popov

What is the best way to implement constants in Java?

static final is my preference, I'd only use an enum if the item was indeed enumerable.

Python recursive folder read

I've found the following to be the easiest

from glob import glob
import os

files = [f for f in glob('rootdir/**', recursive=True) if os.path.isfile(f)]

Using glob('some/path/**', recursive=True) gets all files, but also includes directory names. Adding the if os.path.isfile(f) condition filters this list to existing files only

Regex to match URL end-of-line or "/" character


1st Capturing Group (.+)

.+ matches any character (except for line terminators)

  • + Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)

2nd Capturing Group (\d{4}-\d{2}-\d{2})

\d{4} matches a digit (equal to [0-9])

  • {4} Quantifier — Matches exactly 4 times

- matches the character - literally (case sensitive)

\d{2} matches a digit (equal to [0-9])

  • {2} Quantifier — Matches exactly 2 times

- matches the character - literally (case sensitive)

\d{2} matches a digit (equal to [0-9])

  • {2} Quantifier — Matches exactly 2 times

- matches the character - literally (case sensitive)

3rd Capturing Group (\d+)

\d+ matches a digit (equal to [0-9])

  • + Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)

4th Capturing Group (.*)?

? Quantifier — Matches between zero and one times, as many times as possible, giving back as needed (greedy)

.* matches any character (except for line terminators)

  • * Quantifier — Matches between zero and unlimited times, as many times as possible, giving back as needed (greedy)

$ asserts position at the end of the string

How to do jquery code AFTER page loading?

Edit: This code will wait until all content (images and scripts) are fully loaded and rendered in the browser.

I've had this problem where $(window).on('load',function(){ ... }) would fire too quick for my code since the Javascript I used was for formatting purposes and hiding elements. The elements where hidden too soon and where left with a height of 0.

I now use $(window).on('pageshow',function(){ //code here }); and it fires at the time I need.

Is there a Google Voice API?

I needed a C# API and after spending hours looking for it (all I found was outdated and non-working) and unsuccessfully trying to port the PHP/Python/Java versions listed here (none worked either) I decided to create my own. It's SMS-only for now...

Angular2 http.get() ,map(), subscribe() and observable pattern - basic understanding

import { HttpClientModule } from '@angular/common/http';

The HttpClient API was introduced in the version 4.3.0. It is an evolution of the existing HTTP API and has it's own package @angular/common/http. One of the most notable changes is that now the response object is a JSON by default, so there's no need to parse it with map method anymore .Straight away we can use like below

http.get('friends.json').subscribe(result => this.result =result);

Disable browser cache for entire ASP.NET website

Instead of rolling your own, simply use what's provided for you.

As mentioned previously, do not disable caching for everything. For instance, jQuery scripts used heavily in ASP.NET MVC should be cached. Actually ideally you should be using a CDN for those anyway, but my point is some content should be cached.

What I find works best here rather than sprinkling the [OutputCache] everywhere is to use a class:

[System.Web.Mvc.OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")]
public class NoCacheController  : Controller

All of your controllers you want to disable caching for then inherit from this controller.

If you need to override the defaults in the NoCacheController class, simply specify the cache settings on your action method and the settings on your Action method will take precedence.

[OutputCache(NoStore = true, Duration = 60, VaryByParam = "*")]
public ViewResult Index()

Why when a constructor is annotated with @JsonCreator, its arguments must be annotated with @JsonProperty?

Parameter names are normally not accessible by the Java code at runtime (because it's drop by the compiler), so if you want that functionality you need to either use Java 8's built-in functionality or use a library such as ParaNamer in order to gain access to it.

So in order to not having to utilize annotations for the constructor arguments when using Jackson, you can make use of either of these 2 Jackson modules:


This module allows you to get annotation-free constructor arguments when using Java 8. In order to use it you first need to register the module:

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new ParameterNamesModule());

Then compile your code using the -parameters flag:

javac -parameters ...



This other one simply requires you to register the module or configure an annotation introspection (but not both as pointed out by the comments). It allows you to use annotation-free constructor arguments on versions of Java prior to 1.8.

ObjectMapper mapper = new ObjectMapper();
// either via module
mapper.registerModule(new ParanamerModule());
// or by directly assigning annotation introspector (but not both!)
mapper.setAnnotationIntrospector(new ParanamerOnJacksonAnnotationIntrospector());


delete word after or around cursor in VIM

In old vi, b moves the cursor to the beginning of the word before cursor, w moves the cursor to the beginning of the word after cursor, e moves cursor at the end of the word after cursor and dw deletes from the cursor to the end of the word.

If you type wbdw, you delete the word around cursor, even if the cursor is at the beginning or at the end of the word. Note that whitespaces after a word are considerer to be part of the word to be deleted.

error: invalid type argument of ‘unary *’ (have ‘int’)

I have reformatted your code.

The error was situated in this line :

printf("%d", (**c));

To fix it, change to :

printf("%d", (*c));

The * retrieves the value from an address. The ** retrieves the value (an address in this case) of an other value from an address.

In addition, the () was optional.

#include <stdio.h>

int main(void)
    int b = 10; 
    int *a = NULL;
    int *c = NULL;

    a = &b;
    c = &a;

    printf("%d", *c);

    return 0;


The line :

c = &a;

must be replaced by :

c = a;

It means that the value of the pointer 'c' equals the value of the pointer 'a'. So, 'c' and 'a' points to the same address ('b'). The output is :



If you want to use a double * :

#include <stdio.h>

int main(void)
    int b = 10; 
    int *a = NULL;
    int **c = NULL;

    a = &b;
    c = &a;

    printf("%d", **c);

    return 0;



Selenium WebDriver: Wait for complex page with JavaScript to load

To do it properly, you need to handle the exceptions.

Here is how I do a wait for an iFrame. This requires that your JUnit test class pass the instance of RemoteWebDriver into the page object :

public class IFrame1 extends LoadableComponent<IFrame1> {

    private RemoteWebDriver driver;

    @FindBy(id = "iFrame1TextFieldTestInputControlID" )
    public WebElement iFrame1TextFieldInput;

    @FindBy(id = "iFrame1TextFieldTestProcessButtonID" )
    public WebElement copyButton;

    public IFrame1( RemoteWebDriver drv ) {
        this.driver = drv;
        waitTimer(1, 1000);
        this.driver.switchTo().frame("BodyFrame1");"IFrame1 constructor...");

    protected void isLoaded() throws Error {       "IFrame1.isLoaded()...");
        PageFactory.initElements( driver, this );
        try {
            assertTrue( "Page visible title is not yet available.", driver
     .findElementByCssSelector("body form#webDriverUnitiFrame1TestFormID h1")
                    .getText().equals("iFrame1 Test") );
        } catch ( NoSuchElementException e) {
  "No such element." );
            assertTrue("No such element.", false);

    protected void load() {"IFrame1.load()...");
        Wait<WebDriver> wait = new FluentWait<WebDriver>( driver )
                .withTimeout(30, TimeUnit.SECONDS)
                .pollingEvery(5, TimeUnit.SECONDS)
                .ignoring( NoSuchElementException.class ) 
                .ignoring( StaleElementReferenceException.class ) ;
            wait.until( ExpectedConditions.presenceOfElementLocated( 
            By.cssSelector("body form#webDriverUnitiFrame1TestFormID h1") ) );

NOTE: You can see my entire working example here.

How can I force gradle to redownload dependencies?

For those who are wondering where to run gradle commands:

  1. Open Android Studio
  2. Click on Terminal(You will find it in the base of Android Studio)
  3. The command tool will open
  4. Type your command gradlew build --refresh-dependencies

What's the difference between SoftReference and WeakReference in Java?

The Only Real Difference

Per the doc, loose WeakReferences must be cleared by a running GC.

Per the doc, loose SoftReferences must be cleared before OOM is thrown.

That's the only real difference. Everything else is not part of the contract. (I'll assume the latest docs are contractual.)

SoftReferences are useful. Memory-sensitive caches use SoftReferences, not WeakReferences.

The only proper use of WeakReference is to observe the GC run. You do this by creating a new WeakReference whose object immediately goes out of scope, then try to get null out of weak_ref.get(). When it's null, you learn that between this duration, the GC ran.

As for incorrect use of WeakReference, the list is endless:

  • a lousy hack to implement priority-2 softreference such that you don't have to write one, yet it doesn't work as expected because the cache would be cleared on every GC run, even when there is spare memory. See for phails. (Besides, what if you need more than 2 levels of cache priority? You'd still gotta need a real library for it.)

  • a lousy hack to associate data with an object of an existing class, yet it creates a memory leak (OutOfMemoryError) when your GC decides to take a break after your weakreferences are created. Besides, it's beyond ugly: A better approach is to use tuples.

  • a lousy hack to associate data with an object of an existing class, where the class has the nerve to make itself non-subclassable, and is used in an existing function code which you need to call. In such a case, the proper solution is to either edit the class and make it subclassable, or edit the function and make it take an interface instead of a class, or use an alternative function.

How to change the name of an iOS app?

Step 1 - Rename the project

Click on the project you want to rename in the "Project navigator" on the left of the Xcode view.
On the right select the "File inspector" and the name of your project should be in there under "Identity and Type", change it to the new name.
Click "Rename" in a dropdown menu

Step 2 - Rename the Scheme

In the top bar (near "Stop" button), there is a scheme for your OLD product, click on it, then go to "Manage schemes"
Click on the OLD name in the scheme, and it will become editable, change the name

Step 3 - Rename the folder with your assets

Quit Xcode
In the correctly named master folder, there is a newly named xcodeproj file with the the wrongly named OLD folder. Rename the OLD folder to your new name
Reopen the project, you will see a warning: "The folder OLD does not exist", dismiss the warning
In the "Project navigator" on the left, click the top level OLD folder name
In Utilities pane under "Identity and type" you will see the "Name" entry, change this from the OLD to the new name
Just below there is a "Location" entry. Click on a folder with the OLD name and chose the newly renamed folder

Step 4 - Rename the Build plist data

Click on the project in the "Project navigator" on the left, in the main panel select "Build Settings"
Search for "plist" in this section
Under packaging, you will see Info.plist, and Product bundle identifier
Rename the top entry in Info.plist
Do the same for Product Identifier

Finally, you are done and can rebuild (Command + Shift + K to clean, Command + B to build)

When using CocoaPods After step 2:

Quit XCode.
In the master folder, rename OLD.xcworkspace to NEW.xcworkspace.

After step 4:

In XCode: choose and edit Podfile from the project navigator. You should see a target clause with the OLD name. Change it to NEW.
Quit XCode.
In the project folder, delete the OLD.podspec file.
rm -rf Pods/
Run pod install.
Open XCode.
Click on your project name in the project navigator.
In the main pane, switch to the Build Phases tab.
Under Link Binary With Libraries, look for libPods-OLD.a and delete it.
If you have an objective-c Bridging header go to Build settings and change the location of the header from OLD/OLD-Bridging-Header.h to NEW/NEW-Bridging-Header.h
Clean and run.

vertical-align with Bootstrap 3

        border: 1px solid;_x000D_
        display: flex;_x000D_
        align-items: center;_x000D_
        width: 100px;_x000D_
        height: 50px;_x000D_
        float: left;_x000D_
        background: red;_x000D_
        width: 200px;_x000D_
        height: 24px;_x000D_
        float: left;_x000D_
        background: green;_x000D_
        <div class="col-5">_x000D_
        <div class="col-7"></div>_x000D_

Click to call html

tl;dr What to do in modern (2018) times? Assume tel: is supported, use it and forget about anything else.

The tel: URI scheme RFC5431 (as well as sms: but also feed:, maps:, youtube: and others) is handled by protocol handlers (as mailto: and http: are).

They're unrelated to HTML5 specification (it has been out there from 90s and documented first time back in 2k with RFC2806) then you can't check for their support using tools as modernizr. A protocol handler may be installed by an application (for example Skype installs a callto: protocol handler with same meaning and behaviour of tel: but it's not a standard), natively supported by browser or installed (with some limitations) by website itself.

What HTML5 added is support for installing custom web based protocol handlers (with registerProtocolHandler() and related functions) simplifying also the check for their support through isProtocolHandlerRegistered() function.

There is some easy ways to determine if there is an handler or not:" How to detect browser's protocol handlers?).

In general what I suggest is:

  1. If you're running on a mobile device then you can safely assume tel: is supported (yes, it's not true for very old devices but IMO you can ignore them).
  2. If JS isn't active then do nothing.
  3. If you're running on desktop browsers then you can use one of the techniques in the linked post to determine if it's supported.
  4. If tel: isn't supported then change links to use callto: and repeat check desctibed in 3.
  5. If tel: and callto: aren't supported (or - in a desktop browser - you can't detect their support) then simply remove that link replacing URL in href with javascript:void(0) and (if number isn't repeated in text span) putting, telephone number in title. Here HTML5 microdata won't help users (just search engines). Note that newer versions of Skype handle both callto: and tel:.

Please note that (at least on latest Windows versions) there is always a - fake - registered protocol handler called App Picker (that annoying window that let you choose with which application you want to open an unknown file). This may vanish your tests so if you don't want to handle Windows environment as a special case you can simplify this process as:

  1. If you're running on a mobile device then assume tel: is supported.
  2. If you're running on desktop then replace tel: with callto:. then drop tel: or leave it as is (assuming there are good chances Skype is installed).

Warning: mysqli_query() expects parameter 1 to be mysqli, null given in

use global scope on your $con and put it inside your getPosts() function like so.

function getPosts() {
global $con;
$query = mysqli_query($con,"SELECT * FROM Blog");
while($row = mysqli_fetch_array($query))
        echo "<div class=\"blogsnippet\">";
        echo "<h4>" . $row['Title'] . "</h4>" . $row['SubHeading'];
        echo "</div>";

Catching nullpointerexception in Java

As stated already within another answer it is not recommended to catch a NullPointerException. However you definitely could catch it, like the following example shows.

public class Testclass{

    public static void main(String[] args) {
        try {
        } catch (NullPointerException e) {
            System.out.print("Caught the NullPointerException");

    public static void doSomething() {
        String nullString = null;

Although a NPE can be caught you definitely shouldn't do that but fix the initial issue, which is the Check_Circular method.

CSS get height of screen resolution

You could use viewport-percentage lenghts.


It works like this:

    height: 100vh; /* For 100% screen height */
    width:  100vw; /* For 100% screen width */

More info also available through Mozilla Developer Network and W3C.

Equivalent VB keyword for 'break'

In both Visual Basic 6.0 and VB.NET you would use:

  • Exit For to break from For loop
  • Wend to break from While loop
  • Exit Do to break from Do loop

depending on the loop type. See Exit Statements for more details.

How to install PostgreSQL's pg gem on Ubuntu?

sudo apt-get install postgresql-client libpq5 libpq-dev then do gem install pg

Reversing a String with Recursion in Java

Run the code below - it prints:

Step 0: ello / H
Step 1: llo / e
Step 2: lo / l
Step 3: o / l
Step 3 returns: ol
Step 2 returns: oll
Step 1 returns: olle
Step 0 returns: olleH


public class Test {

    private static int i = 0;

    public static void main(String args[]) {

    public static String reverse(String str) {
        int localI = i++;
        if ((null == str) || (str.length()  <= 1)) {
            return str;
        System.out.println("Step " + localI + ": " + str.substring(1) + " / " + str.charAt(0));
        String reversed = reverse(str.substring(1)) + str.charAt(0);

        System.out.println("Step " + localI + " returns: " + reversed);
        return reversed;

Apache Spark: The number of cores vs. the number of executors

I haven't played with these settings myself so this is just speculation but if we think about this issue as normal cores and threads in a distributed system then in your cluster you can use up to 12 cores (4 * 3 machines) and 24 threads (8 * 3 machines). In your first two examples you are giving your job a fair number of cores (potential computation space) but the number of threads (jobs) to run on those cores is so limited that you aren't able to use much of the processing power allocated and thus the job is slower even though there is more computation resources allocated.

you mention that your concern was in the shuffle step - while it is nice to limit the overhead in the shuffle step it is generally much more important to utilize the parallelization of the cluster. Think about the extreme case - a single threaded program with zero shuffle.

How to define multiple CSS attributes in jQuery?

Agree with redsquare however it is worth mentioning that if you have a two word property like text-align you would do this:

$("#message").css({ width: '30px', height: '10px', 'text-align': 'center'});

BOOLEAN or TINYINT confusion

As of MySql 5.1 version reference

BIT(M) =  approximately (M+7)/8 bytes, 
BIT(1) =  (1+7)/8 = 1 bytes (8 bits)


TINYINT(1) take 8 bits.

How to use clock() in C++

clock() returns the number of clock ticks since your program started. There is a related constant, CLOCKS_PER_SEC, which tells you how many clock ticks occur in one second. Thus, you can test any operation like this:

clock_t startTime = clock();
clock_t endTime = clock();
clock_t clockTicksTaken = endTime - startTime;
double timeInSeconds = clockTicksTaken / (double) CLOCKS_PER_SEC;

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

Yo! I had lots of problems with this. It seems that Github brings its own console which you need to look for in your drive. I managed to finally run it by doing the following:

  1. Press Start.
  2. Search for "GitHub" (without quotes)
  3. Right click on "GitHub" and select "Open File Location"

*This shall open *

C:\Users\UserName\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\GitHub, Inc

Where username is your PC's username

  1. Look for a program called "Git Shell". Double click on it.

This will open a PowerShell command prompt. Then you can run your git commands normally on it.

How to write a full path in a batch file having a folder name with space?

Put double quotes around the path that has spaces like this:

REGSVR32 "E:\Documents and Settings\All Users\Application Data\xyz.dll"

What are the differences between B trees and B+ trees?

Example from Database system concepts 5th

B+-tree B+tree

corresponding B-tree Btree

How do I create a user account for basic authentication?

Right click on Computer and choose "Manage" (or go to Control Panel > Administrative Tools > Computer Management) and under "Local Users and Groups" you can add a new user. Then, give that user permission to read the directory where the site is hosted.

Note: After creating the user, be sure to edit the user and remove all roles.

How can I analyze a heap dump in IntelliJ? (memory leak)

You can also use VisualVM Launcher to launch VisualVM from within IDEA. I personally find this more convenient.

Tomcat is not running even though JAVA_HOME path is correct

Remove the 'bin' from JAVA_HOME. That solves the issue.

How to do multiple arguments to map function where one remains the same in python?

If you have it available, I would consider using numpy. It's very fast for these types of operations:

>>> import numpy
>>> numpy.array([1,2,3]) + 2
array([3, 4, 5])

This is assuming your real application is doing mathematical operations (that can be vectorized).

Multi-statement Table Valued Function vs Inline Table Valued Function

Your examples, I think, answer the question very well. The first function can be done as a single select, and is a good reason to use the inline style. The second could probably be done as a single statement (using a sub-query to get the max date), but some coders may find it easier to read or more natural to do it in multiple statements as you have done. Some functions just plain can't get done in one statement, and so require the multi-statement version.

I suggest using the simplest (inline) whenever possible, and using multi-statements when necessary (obviously) or when personal preference/readability makes it wirth the extra typing.

White space showing up on right side of page when background image should extend full length of page

I was experiencing the white line to the right on my iPad as well in horizontal position only. I was using a fixed-position div with a background set to 960px wide and z-index of -999. This particular div only shows up on an iPad due to a media query. Content was then placed into a 960px wide div wrapper. The answers provided on this page were not helping in my case. To fix the white stripe issue I changed the width of the content wrapper to 958px. Voilá. No more white right white stripe on the iPad in horizontal position.

OperationalError: database is locked

I've got the same error! One of the reasons was the DB connection was not closed. Therefore, check for unclosed DB connections. Also, check if you have committed the DB before closing the connection.

"X does not name a type" error in C++

When the compiler compiles the class User and gets to the MyMessageBox line, MyMessageBox has not yet been defined. The compiler has no idea MyMessageBox exists, so cannot understand the meaning of your class member.

You need to make sure MyMessageBox is defined before you use it as a member. This is solved by reversing the definition order. However, you have a cyclic dependency: if you move MyMessageBox above User, then in the definition of MyMessageBox the name User won't be defined!

What you can do is forward declare User; that is, declare it but don't define it. During compilation, a type that is declared but not defined is called an incomplete type. Consider the simpler example:

struct foo; // foo is *declared* to be a struct, but that struct is not yet defined

struct bar
    // this is okay, it's just a pointer;
    // we can point to something without knowing how that something is defined
    foo* fp; 

    // likewise, we can form a reference to it
    void some_func(foo& fr);

    // but this would be an error, as before, because it requires a definition
    /* foo fooMember; */

struct foo // okay, now define foo!
    int fooInt;
    double fooDouble;

void bar::some_func(foo& fr)
    // now that foo is defined, we can read that reference:
    fr.fooInt = 111605;
    fr.foDouble = 123.456;

By forward declaring User, MyMessageBox can still form a pointer or reference to it:

class User; // let the compiler know such a class will be defined

class MyMessageBox
    // this is ok, no definitions needed yet for User (or Message)
    void sendMessage(Message *msg, User *recvr); 

    Message receiveMessage();
    vector<Message>* dataMessageList;

class User
    // also ok, since it's now defined
    MyMessageBox dataMsgBox;

You cannot do this the other way around: as mentioned, a class member needs to have a definition. (The reason is that the compiler needs to know how much memory User takes up, and to know that it needs to know the size of its members.) If you were to say:

class MyMessageBox;

class User
    // size not available! it's an incomplete type
    MyMessageBox dataMsgBox;

It wouldn't work, since it doesn't know the size yet.

On a side note, this function:

 void sendMessage(Message *msg, User *recvr);

Probably shouldn't take either of those by pointer. You can't send a message without a message, nor can you send a message without a user to send it to. And both of those situations are expressible by passing null as an argument to either parameter (null is a perfectly valid pointer value!)

Rather, use a reference (possibly const):

 void sendMessage(const Message& msg, User& recvr);

Insert HTML from CSS

An alternative - which may work for you depending on what you're trying to do - is to have the HTML in place and then use the CSS to show or hide it depending on the class of a parent element.


Use jQuery append()

MySQL - Meaning of "PRIMARY KEY", "UNIQUE KEY" and "KEY" when used together while creating a table

Just to add to the other answers, the documentation gives this explanation:

  • KEY is normally a synonym for INDEX. The key attribute PRIMARY KEY can also be specified as just KEY when given in a column definition. This was implemented for compatibility with other database systems.

  • A UNIQUE index creates a constraint such that all values in the index must be distinct. An error occurs if you try to add a new row with a key value that matches an existing row. For all engines, a UNIQUE index permits multiple NULL values for columns that can contain NULL.

  • A PRIMARY KEY is a unique index where all key columns must be defined as NOT NULL. If they are not explicitly declared as NOT NULL, MySQL declares them so implicitly (and silently). A table can have only one PRIMARY KEY. The name of a PRIMARY KEY is always PRIMARY, which thus cannot be used as the name for any other kind of index.

Is there an "if -then - else " statement in XPath?

Personally, I would use XSLT to transform the XML and remove the trailing colons. For example, suppose I have this input:

<?xml version="1.0" encoding="UTF-8"?>
    <Paragraph>This paragraph ends in a period.</Paragraph>
    <Paragraph>This one ends in a colon:</Paragraph>
    <Paragraph>This one has a : in the middle.</Paragraph>

If I wanted to strip out trailing colons in my paragraphs, I would use this XSLT:

<?xml version="1.0" encoding="UTF-8"?>
    <!-- identity -->
    <xsl:template match="/|@*|node()">
            <xsl:apply-templates select="@*|node()"/>
    <!-- strip out colons at the end of paragraphs -->
    <xsl:template match="Paragraph">
            <!-- if it ends with a : -->
            <xsl:when test="fn:ends-with(.,':')">
                    <!-- copy everything but the last character -->
                    <xsl:value-of select="substring(., 1, string-length(.)-1)"></xsl:value-of>

How do you post to an iframe?

If you want to change inputs in an iframe then submit the form from that iframe, do this

var el = document.getElementById('targetFrame');

var doc, frame_win = getIframeWindow(el); // getIframeWindow is defined below

if (frame_win) {
  doc = (window.contentDocument || window.document);

if (doc) {
  doc.forms[0].someInputName.value = someValue;

Normally, you can only do this if the page in the iframe is from the same origin, but you can start Chrome in a debug mode to disregard the same origin policy and test this on any page.

function getIframeWindow(iframe_object) {
  var doc;

  if (iframe_object.contentWindow) {
    return iframe_object.contentWindow;

  if (iframe_object.window) {
    return iframe_object.window;

  if (!doc && iframe_object.contentDocument) {
    doc = iframe_object.contentDocument;

  if (!doc && iframe_object.document) {
    doc = iframe_object.document;

  if (doc && doc.defaultView) {
   return doc.defaultView;

  if (doc && doc.parentWindow) {
    return doc.parentWindow;

  return undefined;

Checking if a worksheet-based checkbox is checked

Try: Controls("Check Box 1") = True

Cannot attach the file *.mdf as database

Take a look at this: Entity Framework don't create database

I would try giving the database a different name. Sometimes you can run into problems with SQL Express when trying to create a database with the same name a second time. There is a way to fix this using SQL Server Management Studio but it's generally easier to just use a different database name.

Edit This answer was accepted because it confirms the bug and the workaround used by OP (renaming database could help). I totally agree that renaming the database is not really an acceptable way, and does not totally solve the issue. Unfortunatly I didn't check the other ways to really solve it in SSMS.

PHP Curl And Cookies

First create temporary cookie using tempnam() function:

$ckfile = tempnam ("/tmp", "CURLCOOKIE");

Then execute curl init witch saves the cookie as a temporary file:

$ch = curl_init ("");
curl_setopt ($ch, CURLOPT_COOKIEJAR, $ckfile);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
$output = curl_exec ($ch);

Or visit a page using the cookie stored in the temporary file:

$ch = curl_init ("");
curl_setopt ($ch, CURLOPT_COOKIEFILE, $ckfile);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
$output = curl_exec ($ch);

This will initialize the cookie for the page:

curl_setopt ($ch, CURLOPT_COOKIEFILE, $ckfile);

Import PEM into Java Key Store

If you need an easy way to load PEM files in Java without having to deal with external tools (opensll, keytool), here is my code I use in production :

import java.util.ArrayList;
import java.util.List;

import javax.xml.bind.DatatypeConverter;

public class PEMImporter {

    public static SSLServerSocketFactory createSSLFactory(File privateKeyPem, File certificatePem, String password) throws Exception {
        final SSLContext context = SSLContext.getInstance("TLS");
        final KeyStore keystore = createKeyStore(privateKeyPem, certificatePem, password);
        final KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
        kmf.init(keystore, password.toCharArray());
        final KeyManager[] km = kmf.getKeyManagers();
        context.init(km, null, null);
        return context.getServerSocketFactory();

     * Create a KeyStore from standard PEM files
     * @param privateKeyPem the private key PEM file
     * @param certificatePem the certificate(s) PEM file
     * @param the password to set to protect the private key
    public static KeyStore createKeyStore(File privateKeyPem, File certificatePem, final String password)
            throws Exception, KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
        final X509Certificate[] cert = createCertificates(certificatePem);
        final KeyStore keystore = KeyStore.getInstance("JKS");
        // Import private key
        final PrivateKey key = createPrivateKey(privateKeyPem);
        keystore.setKeyEntry(privateKeyPem.getName(), key, password.toCharArray(), cert);
        return keystore;

    private static PrivateKey createPrivateKey(File privateKeyPem) throws Exception {
        final BufferedReader r = new BufferedReader(new FileReader(privateKeyPem));
        String s = r.readLine();
        if (s == null || !s.contains("BEGIN PRIVATE KEY")) {
            throw new IllegalArgumentException("No PRIVATE KEY found");
        final StringBuilder b = new StringBuilder();
        s = "";
        while (s != null) {
            if (s.contains("END PRIVATE KEY")) {
            s = r.readLine();
        final String hexString = b.toString();
        final byte[] bytes = DatatypeConverter.parseBase64Binary(hexString);
        return generatePrivateKeyFromDER(bytes);

    private static X509Certificate[] createCertificates(File certificatePem) throws Exception {
        final List<X509Certificate> result = new ArrayList<X509Certificate>();
        final BufferedReader r = new BufferedReader(new FileReader(certificatePem));
        String s = r.readLine();
        if (s == null || !s.contains("BEGIN CERTIFICATE")) {
            throw new IllegalArgumentException("No CERTIFICATE found");
        StringBuilder b = new StringBuilder();
        while (s != null) {
            if (s.contains("END CERTIFICATE")) {
                String hexString = b.toString();
                final byte[] bytes = DatatypeConverter.parseBase64Binary(hexString);
                X509Certificate cert = generateCertificateFromDER(bytes);
                b = new StringBuilder();
            } else {
                if (!s.startsWith("----")) {
            s = r.readLine();

        return result.toArray(new X509Certificate[result.size()]);

    private static RSAPrivateKey generatePrivateKeyFromDER(byte[] keyBytes) throws InvalidKeySpecException, NoSuchAlgorithmException {
        final PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        final KeyFactory factory = KeyFactory.getInstance("RSA");
        return (RSAPrivateKey) factory.generatePrivate(spec);

    private static X509Certificate generateCertificateFromDER(byte[] certBytes) throws CertificateException {
        final CertificateFactory factory = CertificateFactory.getInstance("X.509");
        return (X509Certificate) factory.generateCertificate(new ByteArrayInputStream(certBytes));


Have fun.

The performance impact of using instanceof in Java

In modern Java version the instanceof operator is faster as a simple method call. This means:

if(a instanceof AnyObject){

is faster as:

if(a.getType() == XYZ){

Another thing is if you need to cascade many instanceof. Then a switch that only call once getType() is faster.

What values can I pass to the event attribute of the f:ajax tag?

The event attribute of <f:ajax> can hold at least all supported DOM events of the HTML element which is been generated by the JSF component in question. An easy way to find them all out is to check all on* attribues of the JSF input component of interest in the JSF tag library documentation and then remove the "on" prefix. For example, the <h:inputText> component which renders <input type="text"> lists the following on* attributes (of which I've already removed the "on" prefix so that it ultimately becomes the DOM event type name):

  • blur
  • change
  • click
  • dblclick
  • focus
  • keydown
  • keypress
  • keyup
  • mousedown
  • mousemove
  • mouseout
  • mouseover
  • mouseup
  • select

Additionally, JSF has two more special event names for EditableValueHolder and ActionSource components, the real HTML DOM event being rendered depends on the component type:

  • valueChange (will render as change on text/select inputs and as click on radio/checkbox inputs)
  • action (will render as click on command links/buttons)

The above two are the default events for the components in question.

Some JSF component libraries have additional customized event names which are generally more specialized kinds of valueChange or action events, such as PrimeFaces <p:ajax> which supports among others tabChange, itemSelect, itemUnselect, dateSelect, page, sort, filter, close, etc depending on the parent <p:xxx> component. You can find them all in the "Ajax Behavior Events" subsection of each component's chapter in PrimeFaces Users Guide.

C++: Where to initialize variables in constructor

Option 1 allows you to use a place specified exactly for explicitly initializing member variables.

Node.js EACCES error when listening on most ports

Try authbind:

After installing, you can add a file with the name of the port number you want to use in the following folder: /etc/authbind/byport/

Give it 500 permissions using chmod and change the ownership to the user you want to run the program under.

After that, do "authbind node ..." as that user in your project.

setBackground vs setBackgroundDrawable (Android)

Use ViewCompat.setBackground(view, background);

pip is not able to install packages correctly: Permission denied error

On a Mac, you need to use this command:

STATIC_DEPS=true sudo pip install lxml

MySQL compare DATE string with string from DATETIME field

SELECT * FROM `calendar` WHERE DATE(startTime) = '2010-04-29';

it helps , you can convert the values as DATE before comparing.

Shortest distance between a point and a line segment

And now my solution as well...... (Javascript)

It is very fast because I try to avoid any Math.pow functions.

As you can see, at the end of the function I have the distance of the line.

code is from the lib!/example

 * Static util function to determine is a point(px,py) on the line(x1,y1,x2,y2)
 * A simple hit test.
 * @return {boolean}
 * @static
 * @private
 * @param {Number} coronaWidth the accepted corona for the hit test
 * @param {Number} X1 x coordinate of the start point of the line
 * @param {Number} Y1 y coordinate of the start point of the line
 * @param {Number} X2 x coordinate of the end point of the line
 * @param {Number} Y2 y coordinate of the end point of the line
 * @param {Number} px x coordinate of the point to test
 * @param {Number} py y coordinate of the point to test
graphiti.shape.basic.Line.hit= function( coronaWidth, X1, Y1,  X2,  Y2, px, py)
  // Adjust vectors relative to X1,Y1
  // X2,Y2 becomes relative vector from X1,Y1 to end of segment
  X2 -= X1;
  Y2 -= Y1;
  // px,py becomes relative vector from X1,Y1 to test point
  px -= X1;
  py -= Y1;
  var dotprod = px * X2 + py * Y2;
  var projlenSq;
  if (dotprod <= 0.0) {
      // px,py is on the side of X1,Y1 away from X2,Y2
      // distance to segment is length of px,py vector
      // "length of its (clipped) projection" is now 0.0
      projlenSq = 0.0;
  } else {
      // switch to backwards vectors relative to X2,Y2
      // X2,Y2 are already the negative of X1,Y1=>X2,Y2
      // to get px,py to be the negative of px,py=>X2,Y2
      // the dot product of two negated vectors is the same
      // as the dot product of the two normal vectors
      px = X2 - px;
      py = Y2 - py;
      dotprod = px * X2 + py * Y2;
      if (dotprod <= 0.0) {
          // px,py is on the side of X2,Y2 away from X1,Y1
          // distance to segment is length of (backwards) px,py vector
          // "length of its (clipped) projection" is now 0.0
          projlenSq = 0.0;
      } else {
          // px,py is between X1,Y1 and X2,Y2
          // dotprod is the length of the px,py vector
          // projected on the X2,Y2=>X1,Y1 vector times the
          // length of the X2,Y2=>X1,Y1 vector
          projlenSq = dotprod * dotprod / (X2 * X2 + Y2 * Y2);
    // Distance to line is now the length of the relative point
    // vector minus the length of its projection onto the line
    // (which is zero if the projection falls outside the range
    //  of the line segment).
    var lenSq = px * px + py * py - projlenSq;
    if (lenSq < 0) {
        lenSq = 0;
    return Math.sqrt(lenSq)<coronaWidth;

"Permission Denied" trying to run Python on Windows 10

This appears to be a limitation in git-bash. The recommendation to use winpty python.exe worked for me. See Python not working in the command line of git bash for additional information.

How to use AND in IF Statement

If there are no typos in the question, you got the conditions wrong:

You said this:

IF cells (i,"A") contains the text 'Miami'

...but your code says:

If Cells(i, "A") <> "Miami"

--> <> means that the value of the cell is not equal to "Miami", so you're not checking what you think you are checking.

I guess you want this instead:

If Cells(i, "A") like "*Miami*"


Sorry, but I can't really help you more. As I already said in a comment, I'm no Excel VBA expert.
Normally I would open Excel now and try your code myself, but I don't even have Excel on any of my machines at home (I use OpenOffice).

Just one general thing: can you identify the row that does not work?
Maybe this helps someone else to answer the question.

Does it ever execute (or at least try to execute) the Cells(i, "C").Value = "BA" line?
Or is the If Cells(i, "A") like "*Miami*" stuff already False?
If yes, try checking just one cell and see if that works.

Entity Framework - Generating Classes

I found very nice solution. Microsoft released a beta version of Entity Framework Power Tools: Entity Framework Power Tools Beta 2

There you can generate POCO classes, derived DbContext and Code First mapping for an existing database in some clicks. It is very nice!

After installation some context menu options would be added to your Visual Studio.

Right-click on a C# project. Choose Entity Framework-> Reverse Engineer Code First (Generates POCO classes, derived DbContext and Code First mapping for an existing database):

Visual Studio Context Menu

Then choose your database and click OK. That's all! It is very easy.

Why is null an object and what's the difference between null and undefined?

First part of the question:

Why is null considered an object in JavaScript?

It is a JavaScript design error they can't fix now. It should have been type null, not type object, or not have it at all. It necessitates an extra check (sometimes forgotten) when detecting real objects and is source of bugs.

Second part of the question:

Is checking

if (object == null)
Do something

the same as

if (!object)
Do something

The two checks are always both false except for:

  • object is undefined or null: both true.

  • object is primitive, and 0, "", or false: first check false, second true.

If the object is not a primitive, but a real Object, like new Number(0), new String(""), or new Boolean(false), then both checks are false.

So if 'object' is interpreted to mean a real Object then both checks are always the same. If primitives are allowed then the checks are different for 0, "", and false.

In cases like object==null, the unobvious results could be a source of bugs. Use of == is not recommended ever, use === instead.

Third part of the question:

And also:

What is the difference between null and undefined?

In JavaScript, one difference is that null is of type object and undefined is of type undefined.

In JavaScript, null==undefined is true, and considered equal if type is ignored. Why they decided that, but 0, "" and false aren't equal, I don't know. It seems to be an arbitrary opinion.

In JavaScript, null===undefined is not true since the type must be the same in ===.

In reality, null and undefined are identical, since they both represent non-existence. So do 0, and "" for that matter too, and maybe the empty containers [] and {}. So many types of the same nothing are a recipe for bugs. One type or none at all is better. I would try to use as few as possible.

'false', 'true', and '!' are another bag of worms that could be simplified, for example, if(!x) and if(x) alone are sufficient, you don't need true and false.

A declared var x is type undefined if no value is given, but it should be the same as if x was never declared at all. Another bug source is an empty nothing container. So it is best to declare and define it together, like var x=1.

People are going round and round in circles trying to figure out all these various types of nothing, but it's all just the same thing in complicated different clothes. The reality is


And maybe all should throw exceptions.

How do you validate a URL with a regular expression in Python?

Nowadays, in 90% of case if you working with URL in Python you probably use python-requests. Hence the question here - why not reuse URL validation from requests?

from requests.models import PreparedRequest
import requests.exceptions

def check_url(url):
    prepared_request = PreparedRequest()
        prepared_request.prepare_url(url, None)
        return prepared_request.url
    except requests.exceptions.MissingSchema, e:
        raise SomeException


  • Don't reinvent the wheel
  • DRY
  • Work offline
  • Minimal resource

Truncate (not round off) decimal numbers in javascript

Dogbert's answer is good, but if your code might have to deal with negative numbers, Math.floor by itself may give unexpected results.

E.g. Math.floor(4.3) = 4, but Math.floor(-4.3) = -5

Use a helper function like this one instead to get consistent results:

truncateDecimals = function (number) {
    return Math[number < 0 ? 'ceil' : 'floor'](number);

// Applied to Dogbert's answer:
var a = 5.467;
var truncated = truncateDecimals(a * 100) / 100; // = 5.46

Here's a more convenient version of this function:

truncateDecimals = function (number, digits) {
    var multiplier = Math.pow(10, digits),
        adjustedNum = number * multiplier,
        truncatedNum = Math[adjustedNum < 0 ? 'ceil' : 'floor'](adjustedNum);

    return truncatedNum / multiplier;

// Usage:
var a = 5.467;
var truncated = truncateDecimals(a, 2); // = 5.46

// Negative digits:
var b = 4235.24;
var truncated = truncateDecimals(b, -2); // = 4200

If that isn't desired behaviour, insert a call to Math.abs on the first line:

var multiplier = Math.pow(10, Math.abs(digits)),

EDIT: shendz correctly points out that using this solution with a = 17.56 will incorrectly produce 17.55. For more about why this happens, read What Every Computer Scientist Should Know About Floating-Point Arithmetic. Unfortunately, writing a solution that eliminates all sources of floating-point error is pretty tricky with javascript. In another language you'd use integers or maybe a Decimal type, but with javascript...

This solution should be 100% accurate, but it will also be slower:

function truncateDecimals (num, digits) {
    var numS = num.toString(),
        decPos = numS.indexOf('.'),
        substrLength = decPos == -1 ? numS.length : 1 + decPos + digits,
        trimmedResult = numS.substr(0, substrLength),
        finalResult = isNaN(trimmedResult) ? 0 : trimmedResult;

    return parseFloat(finalResult);

For those who need speed but also want to avoid floating-point errors, try something like BigDecimal.js. You can find other javascript BigDecimal libraries in this SO question: "Is there a good Javascript BigDecimal library?" and here's a good blog post about math libraries for Javascript

Parsing command-line arguments in C

Instructional template for parsing command line arguments in C.

C:>programName -w -- fileOne.txt fileTwo.txt

BOOL argLine = FALSE;
BOOL argWord = FALSE;
BOOL argChar = FALSE;
char * fileName1 = NULL;
char * fileName2 = NULL;

int main(int argc, char * argv[]) {
    int i;
    printf("Argument count=%d\n",argc);
    for (i = 0; i < argc; i++) {
        printf("Argument %s\n",argv[i]);
        if (strcmp(argv[i],"-l")==0) {
            argLine = TRUE;
            printf("    argLine=TRUE\n");
        else if (strcmp(argv[i],"-w")==0) {
            argWord = TRUE;
            printf("    argWord=TRUE\n");
        else if (strcmp(argv[i],"-c")==0) {
            argChar = TRUE;
            printf("    argChar=TRUE\n");
        else if (strcmp(argv[i],"--")==0) {
            if (i+1 <= argc) {
                fileName1 = argv[++i];
                printf("    fileName1=%s\n",fileName1);
            if (i+1 <= argc) {
                fileName2 = argv[++i];
                printf("    fileName2=%s\n",fileName2);
    return 0;

How do I write a method to calculate total cost for all items in an array?

In your for loop you need to multiply the units * price. That gives you the total for that particular item. Also in the for loop you should add that to a counter that keeps track of the grand total. Your code would look something like

float total;
total += theItem.getUnits() * theItem.getPrice();

total should be scoped so it's accessible from within main unless you want to pass it around between function calls. Then you can either just print out the total or create a method that prints it out for you.

Drawing Isometric game worlds

Update: Corrected map rendering algorithm, added more illustrations, changed formating.

Perhaps the advantage for the "zig-zag" technique for mapping the tiles to the screen can be said that the tile's x and y coordinates are on the vertical and horizontal axes.

"Drawing in a diamond" approach:

By drawing an isometric map using "drawing in a diamond", which I believe refers to just rendering the map by using a nested for-loop over the two-dimensional array, such as this example:

tile_map[][] = [[...],...]

for (cellY = 0; cellY < tile_map.size; cellY++):
    for (cellX = 0; cellX < tile_map[cellY].size cellX++):
            screenX = (cellX * tile_width  / 2) + (cellY * tile_width  / 2)
            screenY = (cellY * tile_height / 2) - (cellX * tile_height / 2)


The advantage to the approach is that it is a simple nested for-loop with fairly straight forward logic that works consistently throughout all tiles.


One downside to that approach is that the x and y coordinates of the tiles on the map will increase in diagonal lines, which might make it more difficult to visually map the location on the screen to the map represented as an array:

Image of tile map

However, there is going to be a pitfall to implementing the above example code -- the rendering order will cause tiles that are supposed to be behind certain tiles to be drawn on top of the tiles in front:

Resulting image from incorrect rendering order

In order to amend this problem, the inner for-loop's order must be reversed -- starting from the highest value, and rendering toward the lower value:

tile_map[][] = [[...],...]

for (i = 0; i < tile_map.size; i++):
    for (j = tile_map[i].size; j >= 0; j--):  // Changed loop condition here.
            x = (j * tile_width / 2) + (i * tile_width / 2)
            y = (i * tile_height / 2) - (j * tile_height / 2)

With the above fix, the rendering of the map should be corrected:

Resulting image from correct rendering order

"Zig-zag" approach:


Perhaps the advantage of the "zig-zag" approach is that the rendered map may appear to be a little more vertically compact than the "diamond" approach:

Zig-zag approach to rendering seems compact


From trying to implement the zig-zag technique, the disadvantage may be that it is a little bit harder to write the rendering code because it cannot be written as simple as a nested for-loop over each element in an array:

tile_map[][] = [[...],...]

for (i = 0; i < tile_map.size; i++):
    if i is odd:
        offset_x = tile_width / 2
        offset_x = 0

    for (j = 0; j < tile_map[i].size; j++):
            x = (j * tile_width) + offset_x,
            y = i * tile_height / 2

Also, it may be a little bit difficult to try to figure out the coordinate of a tile due to the staggered nature of the rendering order:

Coordinates on a zig-zag order rendering

Note: The illustrations included in this answer were created with a Java implementation of the tile rendering code presented, with the following int array as the map:

tileMap = new int[][] {
    {0, 1, 2, 3},
    {3, 2, 1, 0},
    {0, 0, 1, 1},
    {2, 2, 3, 3}

The tile images are:

  • tileImage[0] -> A box with a box inside.
  • tileImage[1] -> A black box.
  • tileImage[2] -> A white box.
  • tileImage[3] -> A box with a tall gray object in it.

A Note on Tile Widths and Heights

The variables tile_width and tile_height which are used in the above code examples refer to the width and height of the ground tile in the image representing the tile:

Image showing the tile width and height

Using the dimensions of the image will work, as long as the image dimensions and the tile dimensions match. Otherwise, the tile map could be rendered with gaps between the tiles.

Bootstrap 3 scrollable div for table

You can use too

style="overflow-y: scroll; height:150px; width: auto;"

It's works for me

How to show image using ImageView in Android

shoud be @drawable/image where image could have any extension like: image.png, image.xml, image.gif. Android will automatically create a reference in R class with its name, so you cannot have in any drawable folder image.png and image.gif.

How to Generate Barcode using PHP and Display it as an Image on the same page

There is a library for this BarCode PHP. You just need to include a few files:


You can generate many types of barcodes, namely 1D or 2D. Add the required library:


Generate the colours:

// The arguments are R, G, and B for color.
$colorFront = new BCGColor(0, 0, 0);
$colorBack = new BCGColor(255, 255, 255);

After you have added all the codes, you will get this way:


Since several have asked for an example here is what I was able to do to get it done



header('Content-Type: image/png');

$color_white = new BCGColor(255, 255, 255);

$code = new BCGcode128();

$drawing = new BCGDrawing('', $color_white);


If you want to actually create the image file so you can save it then change

$drawing = new BCGDrawing('', $color_white);


$drawing = new BCGDrawing('image.png', $color_white);

How do you log content of a JSON object in Node.js?


Run: node app.js > output.txt

numpy division with RuntimeWarning: invalid value encountered in double_scalars

You can use np.logaddexp (which implements the idea in @gg349's answer):

In [33]: d = np.array([[1089, 1093]])

In [34]: e = np.array([[1000, 4443]])

In [35]: log_res = np.logaddexp(-3*d[0,0], -3*d[0,1]) - np.logaddexp(-3*e[0,0], -3*e[0,1])

In [36]: log_res
Out[36]: -266.99999385580668

In [37]: res = exp(log_res)

In [38]: res
Out[38]: 1.1050349147204485e-116

Or you can use scipy.special.logsumexp:

In [52]: from scipy.special import logsumexp

In [53]: res = np.exp(logsumexp(-3*d) - logsumexp(-3*e))

In [54]: res
Out[54]: 1.1050349147204485e-116

Setting the correct PATH for Eclipse

Go to System Properties > Advanced > Enviroment Variables and look under System variables

First, create/set your JAVA_HOME variable

Even though Eclipse doesn't consult the JAVA_HOME variable, it's still a good idea to set it. See How do I run Eclipse? for more information.

If you have not created and/or do not see JAVA_HOME under the list of System variables, do the following:

  1. Click New... at the very bottom
  2. For Variable name, type JAVA_HOME exactly
  3. For Variable value, this could be different depending on what bits your computer and java are.
    • If both your computer and java are 64-bit, type C:\Program Files\Java\jdk1.8.0_60
    • If both your computer and java are 32-bit, type C:\Program Files\Java\jdk1.8.0_60
    • If your computer is 64-bit, but your java is 32-bit, type C:\Program Files (x86)\Java\jdk1.8.0_60

If you have created and/or do see JAVA_HOME, do the following:

  1. Click on the row under System variables that you see JAVA_HOME in
  2. Click Edit... at the very bottom
  3. For Variable value, change it to what was stated in #3 above based on java's and your computer's bits. To repeat:
    • If both your computer and java are 64-bit, change it to C:\Program Files\Java\jdk1.8.0_60
    • If both your computer and java are 32-bit, change it to C:\Program Files\Java\jdk1.8.0_60
    • If your computer is 64-bit, but your java is 32-bit, change it to C:\Program Files (x86)\Java\jdk1.8.0_60

Next, add to your PATH variable

  1. Click on the row under System variables with PATH in it
  2. Click Edit... at the very bottom
  3. If you have a newer version of windows:
    • Click New
    • Type in C:\Program Files (x86)\Java\jdk1.8.0_60 OR C:\Program Files\Java\jdk1.8.0_60 depending on the bits of your computer and java (see above ^).
    • Press Enter and Click New again.
    • Type in C:\Program Files (x86)\Java\jdk1.8.0_60\jre OR C:\Program Files\Java\jdk1.8.0_60\jre depending on the bits of your computer and java (see above again ^).
    • Press Enter and press OK on all of the related windows
  4. If you have an older version of windows
    • In the Variable value textbox (or something similar) drag the cursor all the way to the very end
    • Add a semicolon (;) if there isn't one already
    • C:\Program Files (x86)\Java\jdk1.8.0_60 OR C:\Program Files\Java\jdk1.8.0_60
    • Add another semicolon (;)
    • C:\Program Files (x86)\Java\jdk1.8.0_60\jre OR C:\Program Files\Java\jdk1.8.0_60\jre

Changing eclipse.ini

  1. Find your eclipse.ini file and copy-paste it in the same directory (should be named eclipse(1).ini)
  2. Rename eclipse.ini to eclipse.ini.old just in case something goes wrong
  3. Rename eclipse(1).ini to eclipse.ini
  4. Open your newly-renamed eclipse.ini and replace all of it with this:

    C:\Program Files\Java\jdk1.8.0_60\bin\javaw.exe

XXMaxPermSize may be deprecated, so it might not work. If eclipse still does not launch, do the following:

  1. Delete the newer eclipse.ini
  2. Rename eclipse.ini.old to eclipse.ini
  3. Open command prompt
  4. type in eclipse -vm C:\Program Files (x86)\Java\jdk1.8.0_60\bin\javaw.exe

If the problem remains

Try updating your eclipse and java to the latest version. 8u60 (1.8.0_60) is not the latest version of java. Sometimes, the latest version of java doesn't work with older versions of eclipse and vice versa. Otherwise, leave a comment if you're still having problems. You could also try a fresh reinstallation of Java.

Remove part of string after "."

We can pretend they are filenames and remove extensions:

# [1] "NM_020506"    "NM_020519"    "NM_001030297" "NM_010281"    "NM_011419"    "NM_053155"

What's the difference between equal?, eql?, ===, and ==?

Equality operators: == and !=

The == operator, also known as equality or double equal, will return true if both objects are equal and false if they are not.

"koan" == "koan" # Output: => true

The != operator, also known as inequality, is the opposite of ==. It will return true if both objects are not equal and false if they are equal.

"koan" != "discursive thought" # Output: => true

Note that two arrays with the same elements in a different order are not equal, uppercase and lowercase versions of the same letter are not equal and so on.

When comparing numbers of different types (e.g., integer and float), if their numeric value is the same, == will return true.

2 == 2.0 # Output: => true


Unlike the == operator which tests if both operands are equal, the equal method checks if the two operands refer to the same object. This is the strictest form of equality in Ruby.

Example: a = "zen" b = "zen"

a.object_id  # Output: => 20139460
b.object_id  # Output :=> 19972120

a.equal? b  # Output: => false

In the example above, we have two strings with the same value. However, they are two distinct objects, with different object IDs. Hence, the equal? method will return false.

Let's try again, only this time b will be a reference to a. Notice that the object ID is the same for both variables, as they point to the same object.

a = "zen"
b = a

a.object_id  # Output: => 18637360
b.object_id  # Output: => 18637360

a.equal? b  # Output: => true


In the Hash class, the eql? method it is used to test keys for equality. Some background is required to explain this. In the general context of computing, a hash function takes a string (or a file) of any size and generates a string or integer of fixed size called hashcode, commonly referred to as only hash. Some commonly used hashcode types are MD5, SHA-1, and CRC. They are used in encryption algorithms, database indexing, file integrity checking, etc. Some programming languages, such as Ruby, provide a collection type called hash table. Hash tables are dictionary-like collections which store data in pairs, consisting of unique keys and their corresponding values. Under the hood, those keys are stored as hashcodes. Hash tables are commonly referred to as just hashes. Notice how the word hashcan refer to a hashcode or to a hash table. In the context of Ruby programming, the word hash almost always refers to the dictionary-like collection.

Ruby provides a built-in method called hash for generating hashcodes. In the example below, it takes a string and returns a hashcode. Notice how strings with the same value always have the same hashcode, even though they are distinct objects (with different object IDs).

"meditation".hash  # Output: => 1396080688894079547
"meditation".hash  # Output: => 1396080688894079547
"meditation".hash  # Output: => 1396080688894079547

The hash method is implemented in the Kernel module, included in the Object class, which is the default root of all Ruby objects. Some classes such as Symbol and Integer use the default implementation, others like String and Hash provide their own implementations.

Symbol.instance_method(:hash).owner  # Output: => Kernel
Integer.instance_method(:hash).owner # Output: => Kernel

String.instance_method(:hash).owner  # Output: => String
Hash.instance_method(:hash).owner  # Output: => Hash

In Ruby, when we store something in a hash (collection), the object provided as a key (e.g., string or symbol) is converted into and stored as a hashcode. Later, when retrieving an element from the hash (collection), we provide an object as a key, which is converted into a hashcode and compared to the existing keys. If there is a match, the value of the corresponding item is returned. The comparison is made using the eql? method under the hood.

"zen".eql? "zen"    # Output: => true
# is the same as
"zen".hash == "zen".hash # Output: => true

In most cases, the eql? method behaves similarly to the == method. However, there are a few exceptions. For instance, eql? does not perform implicit type conversion when comparing an integer to a float.

2 == 2.0    # Output: => true
2.eql? 2.0    # Output: => false
2.hash == 2.0.hash  # Output: => false

Case equality operator: ===

Many of Ruby's built-in classes, such as String, Range, and Regexp, provide their own implementations of the === operator, also known as case-equality, triple equals or threequals. Because it's implemented differently in each class, it will behave differently depending on the type of object it was called on. Generally, it returns true if the object on the right "belongs to" or "is a member of" the object on the left. For instance, it can be used to test if an object is an instance of a class (or one of its subclasses).

String === "zen"  # Output: => true
Range === (1..2)   # Output: => true
Array === [1,2,3]   # Output: => true
Integer === 2   # Output: => true

The same result can be achieved with other methods which are probably best suited for the job. It's usually better to write code that is easy to read by being as explicit as possible, without sacrificing efficiency and conciseness.

2.is_a? Integer   # Output: => true
2.kind_of? Integer  # Output: => true
2.instance_of? Integer # Output: => false

Notice the last example returned false because integers such as 2 are instances of the Fixnum class, which is a subclass of the Integer class. The ===, is_a? and instance_of? methods return true if the object is an instance of the given class or any subclasses. The instance_of method is stricter and only returns true if the object is an instance of that exact class, not a subclass.

The is_a? and kind_of? methods are implemented in the Kernel module, which is mixed in by the Object class. Both are aliases to the same method. Let's verify:

Kernel.instance_method(:kind_of?) == Kernel.instance_method(:is_a?) # Output: => true

Range Implementation of ===

When the === operator is called on a range object, it returns true if the value on the right falls within the range on the left.

(1..4) === 3  # Output: => true
(1..4) === 2.345 # Output: => true
(1..4) === 6  # Output: => false

("a".."d") === "c" # Output: => true
("a".."d") === "e" # Output: => false

Remember that the === operator invokes the === method of the left-hand object. So (1..4) === 3 is equivalent to (1..4).=== 3. In other words, the class of the left-hand operand will define which implementation of the === method will be called, so the operand positions are not interchangeable.

Regexp Implementation of ===

Returns true if the string on the right matches the regular expression on the left. /zen/ === "practice zazen today" # Output: => true # is the same as "practice zazen today"=~ /zen/

Implicit usage of the === operator on case/when statements

This operator is also used under the hood on case/when statements. That is its most common use.

minutes = 15

case minutes
  when 10..20
    puts "match"
    puts "no match"

# Output: match

In the example above, if Ruby had implicitly used the double equal operator (==), the range 10..20 would not be considered equal to an integer such as 15. They match because the triple equal operator (===) is implicitly used in all case/when statements. The code in the example above is equivalent to:

if (10..20) === minutes
  puts "match"
  puts "no match"

Pattern matching operators: =~ and !~

The =~ (equal-tilde) and !~ (bang-tilde) operators are used to match strings and symbols against regex patterns.

The implementation of the =~ method in the String and Symbol classes expects a regular expression (an instance of the Regexp class) as an argument.

"practice zazen" =~ /zen/   # Output: => 11
"practice zazen" =~ /discursive thought/ # Output: => nil

:zazen =~ /zen/    # Output: => 2
:zazen =~ /discursive thought/  # Output: => nil

The implementation in the Regexp class expects a string or a symbol as an argument.

/zen/ =~ "practice zazen"  # Output: => 11
/zen/ =~ "discursive thought" # Output: => nil

In all implementations, when the string or symbol matches the Regexp pattern, it returns an integer which is the position (index) of the match. If there is no match, it returns nil. Remember that, in Ruby, any integer value is "truthy" and nil is "falsy", so the =~ operator can be used in if statements and ternary operators.

puts "yes" if "zazen" =~ /zen/ # Output: => yes
"zazen" =~ /zen/?"yes":"no" # Output: => yes

Pattern-matching operators are also useful for writing shorter if statements. Example:

if meditation_type == "zazen" || meditation_type == "shikantaza" || meditation_type == "kinhin"
Can be rewritten as:
if meditation_type =~ /^(zazen|shikantaza|kinhin)$/

The !~ operator is the opposite of =~, it returns true when there is no match and false if there is a match.

More info is available at this blog post.

How to pass arguments to entrypoint in docker-compose.yml

To override the default entrypoint, use entrypoint option. To pass the arguments use command.

Here is the example of replacing bash with sh in ubuntu image:

version: '3'
    entrypoint: /bin/sh
    command: -c "ps $$(echo $$$$)"
    image: ubuntu
    tty: true
    entrypoint: /bin/bash
    command: -c "ps $$(echo $$$$)"
    image: ubuntu
    tty: true

Here is the output:

$ docker-compose up   
Starting test_sh_1                ... done
Starting 020211508a29_test_bash_1 ... done
Attaching to test_sh_1, 020211508a29_test_bash_1
sh_1    |   PID TTY      STAT   TIME COMMAND
sh_1    |     1 pts/0    Ss+    0:00 /bin/sh -c ps $(echo $$)
020211508a29_test_bash_1 |   PID TTY      STAT   TIME COMMAND
020211508a29_test_bash_1 |     1 pts/0    Rs+    0:00 ps 1

Inheriting constructors

Correct Code is

class A
      explicit A(int x) {}

class B: public A

     B(int a):A(a){

    B *b = new B(5);
     delete b;

Error is b/c Class B has not parameter constructor and second it should have base class initializer to call the constructor of Base Class parameter constructor

What does (function($) {})(jQuery); mean?

Just small addition to explanation

This structure (function() {})(); is called IIFE (Immediately Invoked Function Expression), it will be executed immediately, when the interpreter will reach this line. So when you're writing these rows:

(function($) {
  // do something

this means, that the interpreter will invoke the function immediately, and will pass jQuery as a parameter, which will be used inside the function as $.

Validate a username and password against Active Directory?

Try this code (NOTE: Reported to not work on windows server 2000)

#region NTLogonUser
#region Direct OS LogonUser Code
[DllImport( "advapi32.dll")]
private static extern bool LogonUser(String lpszUsername, 
    String lpszDomain, String lpszPassword, int dwLogonType, 
    int dwLogonProvider, out int phToken);

private static extern int GetLastError();

public static bool LogOnXP(String sDomain, String sUser, String sPassword)
   int token1, ret;
   int attmpts = 0;

   bool LoggedOn = false;

   while (!LoggedOn && attmpts < 2)
      LoggedOn= LogonUser(sUser, sDomain, sPassword, 3, 0, out token1);
      if (LoggedOn) return (true);
         switch (ret = GetLastError())
            case (126): ; 
               if (attmpts++ > 2)
                  throw new LogonException(
                      "Specified module could not be found. error code: " + 

            case (1314): 
               throw new LogonException(
                  "Specified module could not be found. error code: " + 

            case (1326): 
               // edited out based on comment
               //  throw new LogonException(
               //   "Unknown user name or bad password.");
            return false;

               throw new LogonException(
                  "Unexpected Logon Failure. Contact Administrator");
#endregion Direct Logon Code
#endregion NTLogonUser

except you'll need to create your own custom exception for "LogonException"

What is the "Illegal Instruction: 4" error and why does "-mmacosx-version-min=10.x" fix it?

The "illegal instruction" message is simply telling you that your binaries contain instructions the version of the OS that you are attempting to run them under does not understand. I can't give you the precise meaning of 4 but I expect that is internal to Apple.

Otherwise take a look at these... they are a little old, but probably tell you what you need to know

How does 64 bit code work on OS-X 10.5?
what does macosx-version-min imply?

How to detect when keyboard is shown and hidden

In the ViewDidLoad method of your class set up to listen for messages about the keyboard:

// Listen for keyboard appearances and disappearances
[[NSNotificationCenter defaultCenter] addObserver:self 

[[NSNotificationCenter defaultCenter] addObserver:self

Then in the methods you specify (in this case keyboardDidShow and keyboardDidHide) you can do something about it:

- (void)keyboardDidShow: (NSNotification *) notif{
    // Do something here

- (void)keyboardDidHide: (NSNotification *) notif{
    // Do something here

SQL Server: Get table primary key using sql query

The code I'll give you works and retrieves not only keys, but a lot of data from a table in SQL Server. Is tested in SQL Server 2k5/2k8, dunno about 2k. Enjoy!

    sys.tables.object_id AS TableId,
    sys.columns.column_id AS ColumnId, AS ColumnName, AS TypeName,
    sys.columns.precision AS NumericPrecision,
    sys.columns.scale AS NumericScale,
    sys.columns.is_nullable AS IsNullable,
    (   SELECT 
            TABLE_NAME = AND
            CONSTRAINT_NAME =
                (   SELECT
                        TABLE_NAME = AND                    
                        constraint_type = 'PRIMARY KEY' AND
                        COLUMN_NAME =
    ) AS IsPrimaryKey,
    sys.columns.max_length / 2 AS CharMaxLength /*BUG*/
    sys.columns, sys.types, sys.tables 
    sys.tables.object_id = sys.columns.object_id AND
    sys.types.system_type_id = sys.columns.system_type_id AND
    sys.types.user_type_id = sys.columns.user_type_id AND = 'TABLE'

You can use only the primary key part, but I think that the rest might become handy. Best regards, David

Show/hide 'div' using JavaScript

You can Hide/Show Div using Js function. sample below

    function showDivAttid(){

        if(Your Condition) {

            document.getElementById("attid").style.display = 'inline';
            document.getElementById("attid").style.display = 'none';



<div  id="attid" style="display:none;">Show/Hide this text</div>

How to get object length

Can be done easily with $.map():

var len = $.map(a, function(n, i) { return i; }).length;

How to set a DateTime variable in SQL Server 2008?

Check This:

    @_month TINYINT         = 5,
    @_year SMALLINT         = 2020,
    @date_ref DATETIME      = NULL 

    IF @_year IS NULL
        SET @date_ref = GETDATE() - 430
        SELECT @date_ref = CAST ( CAST ( @_year AS VARCHAR (4)) 
                WHEN @_month < 10 THEN '0' + CAST ( @_month AS VARCHAR(1)) 
                ELSE CAST ( @_month AS VARCHAR(2)) 
            '01' AS DATETIME )

How to load local html file into UIWebView

May be your HTML file doesn't support UTF-8 encoding, because the same code is working for me.

Or u can also these line of code:

NSString *htmlFile = [[NSBundle mainBundle] pathForResource:@"Notes For Apple" ofType:@"htm" inDirectory:nil];
NSString* htmlString = [NSString stringWithContentsOfFile:htmlFile encoding:NSUTF8StringEncoding error:nil];
[WebView loadHTMLString:htmlString baseURL:nil];

Cannot access mongodb through browser - It looks like you are trying to access MongoDB over HTTP on the native driver port

MongoDB has a simple web based administrative port at 28017 by default.

There is no HTTP access at the default port of 27017 (which is what the error message is trying to suggest). The default port is used for native driver access, not HTTP traffic.

To access MongoDB, you'll need to use a driver like the MongoDB native driver for NodeJS. You won't "POST" to MongoDB directly (but you might create a RESTful API using express which uses the native drivers). Instead, you'll use a wrapper library that makes accessing MongoDB convenient. You might also consider using Mongoose (which uses the native driver) which adds an ORM-like model for MongoDB in NodeJS.

If you can't get to the web interface, it may be disabled. Normally, I wouldn't expect that you'd need it for doing development unless you're checking logs and such.

How do I run a file on localhost?

Think of it this way.

Anything that you type after localhost/ is the path inside the root directory of your server(www or htdocs).

You don't need to specify the complete path of the file you want to run but just the path after the root folder because putting localhost/ takes you inside the root folder itself.

How to make a window always stay on top in .Net?

I was searching to make my WinForms application "Always on Top" but setting "TopMost" did not do anything for me. I knew it was possible because WinAmp does this (along with a host of other applications).

What I did was make a call to "user32.dll." I had no qualms about doing so and it works great. It's an option, anyway.

First, import the following namespace:

using System.Runtime.InteropServices;

Add a few variables to your class declaration:

private static readonly IntPtr HWND_TOPMOST = new IntPtr(-1);
private const UInt32 SWP_NOSIZE = 0x0001;
private const UInt32 SWP_NOMOVE = 0x0002;

Add prototype for user32.dll function:

[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);

Then in your code (I added the call in Form_Load()), add the call:

SetWindowPos(this.Handle, HWND_TOPMOST, 0, 0, 0, 0, TOPMOST_FLAGS);

Hope that helps. Reference

Get environment variable value in Dockerfile

So you can do: cat Dockerfile | envsubst | docker build -t my-target -

Then have a Dockerfile with something like:


I guess there might be a problem with some special characters, but this works for most cases at least.

Oracle Partition - Error ORA14400 - inserted partition key does not map to any partition

select partition_name,column_name,high_value,partition_position
where table_name='YOUR_TABLE' and a.table_name =;

This query lists the column name used as key and the allowed values. make sure, you insert the allowed values(high_value). Else, if default partition is defined, it would go there.


I presume, your TABLE DDL would be like this.

    PARTITION PDIA_98_20091023 VALUES LESS THAN (98,20091024)

Which means I had created a partition with multiple columns which holds value less than the composite range (98,20091024);

That is first COD_PAIS <= 98 and Also FEC_DATA < 20091024

Combinations And Result:

98, 20091024     FAIL
98, 20091023     PASS
99, ********     FAIL
97, ********     PASS
 < 98, ********     PASS

So the below INSERT fails with ORA-14400; because (98,20091024) in INSERT is EQUAL to the one in DDL but NOT less than it.

                                  VALUES(98, 20091024, 'CTA');  2
ERROR at line 1:
ORA-14400: inserted partition key does not map to any partition

But, we I attempt (97,20091024), it goes through

  2                                    VALUES(97, 20091024, 'CTA');

1 row created.

Type definition in object literal in TypeScript

// Use ..

const Per = {
  name: 'HAMZA',
  age: 20,
  coords: {
    tele: '09',
    lan: '190'
  setAge(age: Number): void {
    this.age = age;
  getAge(): Number {
    return age;
const { age, name }: { age: Number; name: String } = Per;
const {
  coords: { tele, lan }
}: { coords: { tele: String; lan: String } } = Per;


Are there any HTTP/HTTPS interception tools like Fiddler for mac OS X?

I know this is an old question, but I wanted to add ServiceCapture to the list, for those who may come across this.

I've been using ServiceCapture for about 4 years and love it. It's not free, but it is a great tool and not very expensive. If you debug a lot of Flash or AJAX apps it is invaluable.

Run MySQLDump without Locking Tables

This is about as late compared to the guy who said he was late as he was to the original answer, but in my case (MySQL via WAMP on Windows 7), I had to use:


Algorithm to convert RGB to HSV and HSV to RGB in range 0-255 for both

This isn't C, but it's certainly does work. All the other methods I see here work by casing everything into parts of a hexagon, and approximating "angles" from that. By instead starting with a different equation using cosines, and solving for h s and v, you get a lot nicer relationship between hsv and rgb, and tweening becomes smoother (at the cost of it being way slower).

Assume everything is floating point. If r g and b go from 0 to 1, h goes from 0 to 2pi, v goes from 0 to 4/3, and s goes from 0 to 2/3.

The following code is written in Lua. It's easily translatable into anything else.

local hsv do
    hsv         ={}
    local atan2 =math.atan2
    local cos   =math.cos
    local sin   =math.sin

    function hsv.fromrgb(r,b,g)
        local c=r+g+b
        if c<1e-4 then
            return 0,2/3,0
            local p=2*(b*b+g*g+r*r-g*r-b*g-b*r)^0.5
            local h=atan2(b-g,(2*r-b-g)/3^0.5)
            local s=p/(c+p)
            local v=(c+p)/3
            return h,s,v

    function hsv.torgb(h,s,v)
        local r=v*(1+s*(cos(h)-1))
        local g=v*(1+s*(cos(h-2.09439)-1))
        local b=v*(1+s*(cos(h+2.09439)-1))
        return r,g,b

    function hsv.tween(h0,s0,v0,h1,s1,v1,t)
        local dh=(h1-h0+3.14159)%6.28318-3.14159
        local h=h0+t*dh
        local s=s0+t*(s1-s0)
        local v=v0+t*(v1-v0)
        return h,s,v

Where to place JavaScript in an HTML file?

The answer is depends how you are using the objects of javascript. As already pointed loading the javascript files at footer rather than header certainly improves the performance but care should be taken that the objects which are used are initialized later than they are loaded at footer. One more way is load the 'js' files placed in folder which will be available to all the files.

git push rejected: error: failed to push some refs

Just do

git pull origin [branch]

and then you should be able to push.

If you have commits on your own and didn't push it the branch yet, try

git pull --rebase origin [branch]

and then you should be able to push.

Read more about handling branches with Git.

Read from file in eclipse

Sometimes, even when the file is in the right directory, there is still the "file not found" exception. One thing you could do is to drop the text file inside eclipse, where your classes are, on the left side. It is going to ask you if you want to copy, click yes. Sometimes it helps.

Break string into list of characters in Python

python >= 3.5

Version 3.5 onwards allows the use of PEP 448 - Extended Unpacking Generalizations:

>>> string = 'hello'
>>> [*string]
['h', 'e', 'l', 'l', 'o']

This is a specification of the language syntax, so it is faster than calling list:

>>> from timeit import timeit
>>> timeit("list('hello')")
>>> timeit("[*'hello']")

How does JPA orphanRemoval=true differ from the ON DELETE CASCADE DML clause

The difference is:
- orphanRemoval = true: "Child" entity is removed when it's no longer referenced (its parent may not be removed).
- CascadeType.REMOVE: "Child" entity is removed only when its "Parent" is removed.

How to type a new line character in SQL Server Management Studio

Either char(13) or char(10) would work. But it is recommended to use char(13) + char(10)

  • char(10) = \n - new line
  • char(13) = \r - go to the beginning of the line

Radio/checkbox alignment in HTML/CSS

This is a simple solution which solved the problem for me:


/* for firefox */

/*for internet explorer */



How to put two divs on the same line with CSS in simple_form in rails?

You can't float or set the width of an inline element. Remove display: inline; from both classes and your markup should present fine.

EDIT: You can set the width, but it will cause the element to be rendered as a block.

Best way to determine user's locale within browser

There's a difference between the user's preferred languages and the system/browser locale.

A user can configure preferred languages in the browser, and these will be used for navigator.language(s), and used when requesting resources from a server, to request content according to a list of language priorities.

However, the browser locale will decide how to render number, date, time and currency. This setting is likely the highest ranking language, but there is no guarantee. On Mac and Linux, the locale is decided by the system regardless of the user language preferences. On Windows is can be elected among the languages in the preferred list on Chrome.

By using Intl (, developers can override/set the locale to use to render these things, but there are elements that cannot be overridden, such as the <input type="date"> format.

To properly extract this language, the only way I've found is:

(new Intl.NumberFormat()).resolvedOptions().locale

(Intl.NumberFormat().resolvedOptions().locale also seems to work)

This will create a new NumberFormat instance for the default locale and then reading back the locale of those resolved options.

When to use which design pattern?

I completely agree with @Peter Rasmussen.

Design patterns provide general solution to commonly occurring design problem.

I would like you to follow below approach.

  1. Understand intent of each pattern
  2. Understand checklist or use case of each pattern
  3. Think of solution to your problem and check if your solution falls into checklist of particular pattern
  4. If not, simply ignore the design-patterns and write your own solution.

Useful links:

sourcemaking : Explains intent, structure and checklist beautifully in multiple languages including C++ and Java

wikipedia : Explains structure, UML diagram and working examples in multiple languages including C# and Java .

Check list and Rules of thumb in each sourcemakding design-pattern provides alram bell you are looking for.

Division of integers in Java

If you don't explicitly cast one of the two values to a float before doing the division then an integer division will be used (so that's why you get 0). You just need one of the two operands to be a floating point value, so that the normal division is used (and other integer value is automatically turned into a float).

Just try with

float completed = 50000.0f;

and it will be fine.

How do I request and process JSON with python?

Python's standard library has json and urllib2 modules.

import json
import urllib2

data = json.load(urllib2.urlopen('http://someurl/path/to/json'))

Show animated GIF

Using swing you could simply use a JLabel

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

        URL url = new URL("<URL to your Animated GIF>");
        Icon icon = new ImageIcon(url);
        JLabel label = new JLabel(icon);

        JFrame f = new JFrame("Animation");

Why do we need the "finally" clause in Python?

You can use finally to make sure files or resources are closed or released regardless of whether an exception occurs, even if you don't catch the exception. (Or if you don't catch that specific exception.)

myfile = open("test.txt", "w")

    myfile.write("the Answer is: ")
    myfile.write(42)   # raises TypeError, which will be propagated to caller
    myfile.close()     # will be executed before TypeError is propagated

In this example you'd be better off using the with statement, but this kind of structure can be used for other kinds of resources.

A few years later, I wrote a blog post about an abuse of finally that readers may find amusing.

CSS background image alt attribute

The general belief is that you shouldn't be using background images for things with meaningful semantic value so there isn't really a proper way to store alt data with those images. The important question is what are you going to be doing with that alt data? Do you want it to display if the images don't load? Do you need it for some programmatic function on the page? You could store the data arbitrarily using made up css properties that have no meaning (might cause errors?) OR by adding in hidden images that have the image and the alt tag, and then when you need a background images alt you can compare the image paths and then handle the data however you want using some custom script to simulate what you need. There's no way I know of to make the browser automatically handle some sort of alt attribute for background images though.

What are the differences between WCF and ASMX web services?

WCF completely replaces ASMX web services. ASMX is the old way to do web services and WCF is the current way to do web services. All new SOAP web service development, on the client or the server, should be done using WCF.

Specify multiple attribute selectors in CSS

Concatenate the attribute selectors:


How to select the last record from MySQL table using SQL syntax

SELECT * FROM your_table ORDER BY id ASC LIMIT 0, 1

The ASC will return resultset in ascending order thereby leaving you with the latest or most recent record. The DESC counterpart will do the exact opposite. That is, return the oldest record.

how to toggle (hide/show) a table onClick of <a> tag in java script

You are trying to alter the behaviour of onclick inside the same function call. Try it like this:

Anchor tag

<a id="loginLink" onclick="toggleTable();" href="#">Login</a>


function toggleTable() {
    var lTable = document.getElementById("loginTable"); = ( == "table") ? "none" : "table";

org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1

please do not set id of child class which is generator class is foreign only set parent class id if your parent class id is assigned... just do one thing dont set id of child class via setter method your problem will be fix.....definately.

Excel VBA: Copying multiple sheets into new workbook

This worked for me (I added an "if sheet visible" because in my case I wanted to skip hidden sheets)

   Sub Create_new_file()

Application.DisplayAlerts = False

Dim wb As Workbook
Dim wbNew As Workbook
Dim sh As Worksheet
Dim shNew As Worksheet
Dim pname, parea As String

Set wb = ThisWorkbook
Set wbNew = ActiveWorkbook

For Each sh In wb.Worksheets

    pname = sh.Name

    If sh.Visible = True Then

    sh.Copy After:=wbNew.Sheets(Sheets.Count)



    With Selection

        .PasteSpecial (xlValues)
        .PasteSpecial (xlFormats)
        .PasteSpecial (xlPasteColumnWidths)

    End With

    ActiveSheet.Name = pname

    End If



Application.DisplayAlerts = True

End Sub

Execute an action when an item on the combobox is selected

The simple solution would be to use a ItemListener. When the state changes, you would simply check the currently selected item and set the text accordingly

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestComboBox06 {

    public static void main(String[] args) {
        new TestComboBox06();

    public TestComboBox06() {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {

                JFrame frame = new JFrame("Test");
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());


    public class TestPane extends JPanel {

        private JComboBox cb;
        private JTextField field;

        public TestPane() {
            cb = new JComboBox(new String[]{"Item 1", "Item 2"});
            field = new JTextField(12);



            cb.addItemListener(new ItemListener() {
                public void itemStateChanged(ItemEvent e) {
                    Object item = cb.getSelectedItem();
                    if ("Item 1".equals(item)) {
                    } else if ("Item 2".equals(item)) {



A better solution would be to create a custom object that represents the value to be displayed and the value associated with it...


Now I no longer have a 10 month chewing on my ankles, I updated the example to use a ListCellRenderer which is a more correct approach then been lazy and overriding toString

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.DefaultListCellRenderer;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestComboBox06 {

    public static void main(String[] args) {
        new TestComboBox06();

    public TestComboBox06() {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {

                JFrame frame = new JFrame("Test");
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());


    public class TestPane extends JPanel {

        private JComboBox cb;
        private JTextField field;

        public TestPane() {
            cb = new JComboBox(new Item[]{
                new Item("Item 1", "20"), 
                new Item("Item 2", "30")});
            cb.setRenderer(new ItemCelLRenderer());
            field = new JTextField(12);



            cb.addItemListener(new ItemListener() {
                public void itemStateChanged(ItemEvent e) {
                    Item item = (Item)cb.getSelectedItem();


    public class Item {
        private String value;
        private String text;

        public Item(String text, String value) {
            this.text = text;
            this.value = value;

        public String getText() {
            return text;

        public String getValue() {
            return value;


    public class ItemCelLRenderer extends DefaultListCellRenderer {

        public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
            super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus); //To change body of generated methods, choose Tools | Templates.
            if (value instanceof Item) {
            return this;



How to set value to variable using 'execute' in t-sql?

You can try like below

DECLARE @sqlCommand NVARCHAR(4000)
SET @ID = 4
SET @sqlCommand = 'SELECT @Name = [Name]
FROM [AdventureWorks2014].[HumanResources].[Department]
WHERE DepartmentID = @ID'
EXEC sp_executesql @sqlCommand, N'@ID INT, @Name NVARCHAR(100) OUTPUT',
@ID = @ID, @Name = @Name OUTPUT
SELECT @Name ReturnedName

Source :

Remove duplicate elements from array in Ruby

If someone was looking for a way to remove all instances of repeated values, see "How can I efficiently extract repeated elements in a Ruby array?".

a = [1, 2, 2, 3]
counts =
a.each { |v| counts[v] += 1 }
p { |v, count| count == 1 }.keys # [1, 3]

Laravel 5.4 create model, controller and migration in single artisan command

You can make model + migration + controller, all in one line, using this command:

php artisan make:model --migration --controller test

Short version: php artisan make:model -mc test

Output :-

Model created successfully.

Created Migration:2018_03_10_002331_create_tests_table

Controller created successfully.

If you need to perform all CRUD operations in the controller then use this command:

php artisan make:model --migration --controller test --resource  

Short version: php artisan make:model -mc test --resource

Environment variables in Jenkins

The quick and dirty way, you can view the available environment variables from the below link.


Just replace localhost with your Jenkins hostname, if its different

SHA1 vs md5 vs SHA256: which to use for a PHP login?

Everyone is talking about this like they can be hacked over the internet. As already stated, limiting attempts makes it impossible to crack a password over the Internet and has nothing to do with the hash.

The salt is a must, but the complexity or multiple salts doesn't even matter. Any salt alone stops the attacker from using a premade rainbow table. A unique salt per user stops the attacker from creating a new rainbow table to use against your entire user base.

The security really comes into play when the entire database is compromised and a hacker can then perform 100 million password attempts per second against the md5 hash. SHA512 is about 10,000 times slower. A complex password with today's power could still take 100 years to bruteforce with md5 and would take 10,000 times as long with SHA512. The salts don't stop a bruteforce at all as they always have to be known, which if the attacker downloaded your database, he probably was in your system anyway.

Home does not contain an export named Home

I just ran into this error message (after upgrading to nextjs 9 some transpiled imports started giving this error). I managed to fix them using syntax like this:

import * as Home from './layouts/Home';

Combine multiple JavaScript files into one JS file

I usually have it on a Makefile:

# All .js compiled into a single one.

    @find ./path/of/js -type f -name "*.js" | xargs cat > $(compiled)

Then you run:

make compile

I hope it helps.

Android load from URL to Bitmap

Try this:

AQuery aq = new AQuery(getActivity());
  , true, true, 0,  0,
                    new BitmapAjaxCallback() {
                        public void callback(String url, ImageView iv, Bitmap bm, AjaxStatus status){
                    }.header("User-Agent", "android"));

window.history.pushState refreshing the browser


Only works after page is loaded, and when you will click on refresh it doesn't mean that there is any real URL.

What you should do here is knowing to which URL you are getting redirected when you reload this page. And on that page you can get the conditions by getting the current URL and making all of your conditions.

Extracting first n columns of a numpy matrix

I know this is quite an old question -

A = [[1, 2, 3],
     [4, 5, 6],
     [7, 8, 9]]

Let's say, you want to extract the first 2 rows and first 3 columns

A_NEW = A[0:2, 0:3]
A_NEW = [[1, 2, 3],
         [4, 5, 6]]

Understanding the syntax

A_NEW = A[start_index_row : stop_index_row, 
          start_index_column : stop_index_column)]

If one wants row 2 and column 2 and 3

A_NEW = A[1:2, 1:3]

Reference the numpy indexing and slicing article - Indexing & Slicing

how to call a onclick function in <a> tag?

Use the onclick as an attribute of your a, not part of the href

<a onclick='"lead_data.php?leadid=1", myWin, scrollbars=yes, width=400, height=650);'>1</a>


How do you allow spaces to be entered using scanf?

This example uses an inverted scanset, so scanf keeps taking in values until it encounters a '\n'-- newline, so spaces get saved as well

#include <stdio.h>

int main (int argc, char const *argv[])
    char name[20];
    printf("%s\n", name);
    return 0;

Can I convert a C# string value to an escaped string literal

What about Regex.Escape(String) ?

Regex.Escape escapes a minimal set of characters (\, *, +, ?, |, {, [, (,), ^, $,., #, and white space) by replacing them with their escape codes.