Programs & Examples On #Irepository

Check if two lists are equal

Use SequenceEqual to check for sequence equality because Equals method checks for reference equality.

var a = ints1.SequenceEqual(ints2);

Or if you don't care about elements order use Enumerable.All method:

var a = ints1.All(ints2.Contains);

The second version also requires another check for Count because it would return true even if ints2 contains more elements than ints1. So the more correct version would be something like this:

var a = ints1.All(ints2.Contains) && ints1.Count == ints2.Count;

In order to check inequality just reverse the result of All method:

var a = !ints1.All(ints2.Contains)

How to convert Double to int directly?

If you really should use Double instead of double you even can get the int Value of Double by calling:

Double d = new Double(1.23);
int i = d.intValue();

Else its already described by Peter Lawreys answer.

Vim: insert the same characters across multiple lines

I wanted to comment out a lot of lines in some config file on a server that only had vi (no nano), so visual method was cumbersome as well Here's how i did that.

  1. Open file vi file
  2. Display line numbers :set number! or :set number
  3. Then use the line numbers to replace start-of-line with "#", how?


Note: the numbers are inclusive, lines from 35 to 77, both included will be modified.

To uncomment/undo that, simply use :35,77s/^#//

If you want to add a text word as a comment after every line of code, you can also use:

:35,77s/$/#test/ (for languages like Python)

:35,77s/;$/;\/\/test/ (for languages like Java)




Android "Only the original thread that created a view hierarchy can touch its views."

This happened to my when I called for an UI change from a doInBackground from Asynctask instead of using onPostExecute.

Dealing with the UI in onPostExecute solved my problem.

Default SecurityProtocol in .NET 4.5

Following code will:

  • print enabled protocols
  • print available protocols
  • enable TLS1.2 if platform supports it and if it is not enabled to begin with
  • disable SSL3 if it is enabled
  • print end result


  • 48 is SSL3
  • 192 is TLS1
  • 768 is TLS1.1
  • 3072 is TLS1.2

Other protocols will not be affected. This makes this compatible with future protocols (Tls1.3, etc).


// print initial status
    Console.WriteLine("Runtime: " + System.Diagnostics.FileVersionInfo.GetVersionInfo(typeof(int).Assembly.Location).ProductVersion);
    Console.WriteLine("Enabled protocols:   " + ServicePointManager.SecurityProtocol);
    Console.WriteLine("Available protocols: ");
    Boolean platformSupportsTls12 = false;
    foreach (SecurityProtocolType protocol in Enum.GetValues(typeof(SecurityProtocolType))) {                
        if (protocol.GetHashCode() == 3072){
            platformSupportsTls12 = true;
    Console.WriteLine("Is Tls12 enabled: " + ServicePointManager.SecurityProtocol.HasFlag((SecurityProtocolType)3072));    

// enable Tls12, if possible
    if (!ServicePointManager.SecurityProtocol.HasFlag((SecurityProtocolType)3072)){
        if (platformSupportsTls12){
            Console.WriteLine("Platform supports Tls12, but it is not enabled. Enabling it now.");
            ServicePointManager.SecurityProtocol |= (SecurityProtocolType)3072;
        } else {
            Console.WriteLine("Platform does not supports Tls12.");

// disable ssl3
   if (ServicePointManager.SecurityProtocol.HasFlag(SecurityProtocolType.Ssl3)) { 
      Console.WriteLine("Ssl3SSL3 is enabled. Disabling it now.");
      // disable SSL3. Has no negative impact if SSL3 is already disabled. The enclosing "if" if just for illustration.
      System.Net.ServicePointManager.SecurityProtocol &= ~SecurityProtocolType.Ssl3;                      
    Console.WriteLine("Enabled protocols:   " + ServicePointManager.SecurityProtocol);


Runtime: 4.7.2114.0
Enabled protocols:   Ssl3, Tls
Available protocols: 
Is Tls12 enabled: False
Platform supports Tls12, but it is not enabled. Enabling it now.
Ssl3 is enabled. Disabling it now.
Enabled protocols:   Tls, Tls12

Javascript geocoding from address to latitude and longitude numbers not working

Try using this instead:

var latitude = results[0];
var longitude = results[0].geometry.location.lng();

It's bit hard to navigate Google's api but here is the relevant documentation.

One thing I had trouble finding was how to go in the other direction. From coordinates to an address. Here is the code I neded upp using. Please not that I also use jquery.

$.each(results[0].address_components, function(){
    $("#CreateDialog").find('input[name="'+ this.types+'"]').attr('value', this.long_name);

What I'm doing is to loop through all the returned address_components and test if their types match any input element names I have in a form. And if they do I set the value of the element to the address_components value.
If you're only interrested in the whole formated address then you can follow Google's example

Passing a String by Reference in Java?

For passing an object (including String) by reference in java, you might pass it as member of a surrounding adapter. A solution with a generic is here:


public class ByRef<T extends Object> implements Serializable
    private static final long serialVersionUID = 6310102145974374589L;

    T v;

    public ByRef(T v)
        this.v = v;

    public ByRef()
        v = null;

    public void set(T nv)
        v = nv;

    public T get()
        return v;

// ------------------------------------------------------------------

    static void fillString(ByRef<String> zText)
        zText.set(zText.get() + "foo");

    public static void main(String args[])
        final ByRef<String> zText = new ByRef<String>(new String(""));

Image UriSource and Data Binding

WPF has built-in converters for certain types. If you bind the Image's Source property to a string or Uri value, under the hood WPF will use an ImageSourceConverter to convert the value to an ImageSource.


<Image Source="{Binding ImageSource}"/>

would work if the ImageSource property was a string representation of a valid URI to an image.

You can of course roll your own Binding converter:

public class ImageConverter : IValueConverter
    public object Convert(
        object value, Type targetType, object parameter, CultureInfo culture)
        return new BitmapImage(new Uri(value.ToString()));

    public object ConvertBack(
        object value, Type targetType, object parameter, CultureInfo culture)
        throw new NotSupportedException();

and use it like this:

<Image Source="{Binding ImageSource, Converter={StaticResource ImageConverter}}"/>

What is the difference between `sorted(list)` vs `list.sort()`?

The .sort() function stores the value of new list directly in the list variable; so answer for your third question would be NO. Also if you do this using sorted(list), then you can get it use because it is not stored in the list variable. Also sometimes .sort() method acts as function, or say that it takes arguments in it.

You have to store the value of sorted(list) in a variable explicitly.

Also for short data processing the speed will have no difference; but for long lists; you should directly use .sort() method for fast work; but again you will face irreversible actions.

Best way to randomize an array with .NET

You're looking for a shuffling algorithm, right?

Okay, there are two ways to do this: the clever-but-people-always-seem-to-misunderstand-it-and-get-it-wrong-so-maybe-its-not-that-clever-after-all way, and the dumb-as-rocks-but-who-cares-because-it-works way.

Dumb way

  • Create a duplicate of your first array, but tag each string should with a random number.
  • Sort the duplicate array with respect to the random number.

This algorithm works well, but make sure that your random number generator is unlikely to tag two strings with the same number. Because of the so-called Birthday Paradox, this happens more often than you might expect. Its time complexity is O(n log n).

Clever way

I'll describe this as a recursive algorithm:

To shuffle an array of size n (indices in the range [0..n-1]):

if n = 0
  • do nothing
if n > 0
  • (recursive step) shuffle the first n-1 elements of the array
  • choose a random index, x, in the range [0..n-1]
  • swap the element at index n-1 with the element at index x

The iterative equivalent is to walk an iterator through the array, swapping with random elements as you go along, but notice that you cannot swap with an element after the one that the iterator points to. This is a very common mistake, and leads to a biased shuffle.

Time complexity is O(n).

Copy struct to struct in C

For simple structures you can either use memcpy like you do, or just assign from one to the other:

RTCclk = RTCclkBuffert;

The compiler will create code to copy the structure for you.

An important note about the copying: It's a shallow copy, just like with memcpy. That means if you have e.g. a structure containing pointers, it's only the actual pointers that will be copied and not what they point to, so after the copy you will have two pointers pointing to the same memory.

How to update std::map after using the find method?

You can use std::map::at member function, it returns a reference to the mapped value of the element identified with key k.

std::map<char,int> mymap = {
                               { 'a', 0 },
                               { 'b', 0 },
                           };'a') = 10;'b') = 20;

Algorithm to compare two images

It is indeed much less simple than it seems :-) Nick's suggestion is a good one.

To get started, keep in mind that any worthwhile comparison method will essentially work by converting the images into a different form -- a form which makes it easier to pick similar features out. Usually, this stuff doesn't make for very light reading ...

One of the simplest examples I can think of is simply using the color space of each image. If two images have highly similar color distributions, then you can be reasonably sure that they show the same thing. At least, you can have enough certainty to flag it, or do more testing. Comparing images in color space will also resist things such as rotation, scaling, and some cropping. It won't, of course, resist heavy modification of the image or heavy recoloring (and even a simple hue shift will be somewhat tricky).

Another example involves something called the Hough Transform. This transform essentially decomposes an image into a set of lines. You can then take some of the 'strongest' lines in each image and see if they line up. You can do some extra work to try and compensate for rotation and scaling too -- and in this case, since comparing a few lines is MUCH less computational work than doing the same to entire images -- it won't be so bad.

How to drop all tables in a SQL Server database?

You can also delete all tables from database using only MSSMS UI tools (without using SQL script). Sometimes this way can be more comfortable (especially if it is performed occasionally)

I do this step by step as follows:

  1. Select 'Tables' on the database tree (Object Explorer)
  2. Press F7 to open Object Explorer Details view
  3. In this view select tables which have to be deleted (in this case all of them)
  4. Keep pressing Delete until all tables have been deleted (you repeat it as many times as amount of errors due to key constraints/dependencies)

What is the default access specifier in Java?

See here for more details. The default is none of private/public/protected, but a completely different access specification. It's not widely used, and I prefer to be much more specific in my access definitions.

How do I sort strings alphabetically while accounting for value when a string is numeric?

And, how about this ...

string[] sizes = new string[] { "105", "101", "102", "103", "90" };

var size = from x in sizes
           orderby x.Length, x
           select x;

foreach (var p in size)

jQuery Determine if a matched class has a given id

$('#' + theMysteryId + '.someClass').each(function() { /* do stuff */ });

Ruby capitalize every word first letter

I used this for a similar problem:

'catherine mc-nulty joséphina'.capitalize.gsub(/(\s+\w)/) { |stuff| stuff.upcase }

This handles the following weird cases I saw trying the previous answers:

  • non-word characters like -
  • accented characters common in names like é
  • capital characters in the middle of the string

Quick Sort Vs Merge Sort

I personally wanted to test the difference between Quick sort and merge sort myself and saw the running times for a sample of 1,000,000 elements.

Quick sort was able to do it in 156 milliseconds whereas Merge sort did the same in 247 milliseconds

The Quick sort data, however, was random and quick sort performs well if the data is random where as its not the case with merge sort i.e. merge sort performs the same, irrespective of whether data is sorted or not. But merge sort requires one full extra space and quick sort does not as its an in-place sort

I have written comprehensive working program for them will illustrative pictures too.

Referencing value in a closed Excel workbook using INDIRECT?

This seems to work with closed file: add a pivot table (rows, tabular layout, no subtotals, no grand totals) of the source to the current workbook, then reference all you want from that pivot table, INDIRECT, LOOKUPs,...

"cannot resolve symbol R" in Android Studio

  1. Type 1 : close the Project and delete .gradle file in your project and then Rebuild the project
  2. Type 2: If type 1 does not works, then just take back up of of that project9Zip file) and then delete the project. Then extract the Zipped project and just import the extracted project, it will works perfectly, because it works for me.

equivalent of rm and mv in windows .cmd

If you want to see a more detailed discussion of differences for the commands, see the Details about Differences section, below.

From the website1 (archived), specifically the Windows and Unix command line equivalents page (archived), I found the following2. There's a better/more complete table in the next edit.

Windows command     Unix command
rmdir               rmdir
rmdir /s            rm -r
move                mv

I'm interested to hear from @Dave and @javadba to hear how equivalent the commands are - how the "behavior and capabilities" compare, whether quite similar or "woefully NOT equivalent".

All I found out was that when I used it to try and recursively remove a directory and its constituent files and subdirectories, e.g.

(Windows cmd)>rmdir /s C:\my\dirwithsubdirs\

gave me a standard Windows-knows-better-than-you-do-are-you-sure message and prompt

dirwithsubdirs, Are you sure (Y/N)?

and that when I typed Y, the result was that my top directory and its constituent files and subdirectories went away.


I'm looking back at this after finding this answer. I retried each of the commands, and I'd change the table a little bit.

Windows command     Unix command
rmdir               rmdir
rmdir /s /q         rm -r
rmdir /s /q         rm -rf
rmdir /s            rm -ri
move                mv
del <file>          rm <file>

If you want the equivalent for

rm -rf

you can use

rmdir /s /q

or, as the author of the answer I sourced described,

But there is another "old school" way to do it that was used back in the day when commands did not have options to suppress confirmation messages. Simply ECHO the needed response and pipe the value into the command.

echo y | rmdir /s

Details about Differences

I tested each of the commands using Windows CMD and Cygwin (with its bash).

Before each test, I made the following setup.

Windows CMD

>mkdir this_directory
>echo some text stuff > this_directory/some.txt
>mkdir this_empty_directory

Cygwin bash

$ mkdir this_directory
$ echo "some text stuff" > this_directory/some.txt
$ mkdir this_empty_directory

That resulted in the following file structure for both.

|-- this_directory
|   `-- some.txt
`-- this_empty_directory

Here are the results. Note that I'll not mark each as CMD or bash; the CMD will have a > in front, and the bash will have a $ in front.


>rmdir this_directory
The directory is not empty.

>tree /a /f .
Folder PATH listing for volume Windows
Volume serial number is ¦¦¦¦¦¦¦¦ ¦¦¦¦:¦¦¦¦
|       some.txt

> rmdir this_empty_directory

>tree /a /f .
$ rmdir this_directory
rmdir: failed to remove 'this_directory': Directory not empty

$ tree --charset=ascii
|-- this_directory
|   `-- some.txt
`-- this_empty_directory

2 directories, 1 file

$ rmdir this_empty_directory

$ tree --charset=ascii
`-- this_directory
    `-- some.txt

RMDIR /S /Q and RM -R ; RM -RF

>rmdir /s /q this_directory

>tree /a /f

>rmdir /s /q this_empty_directory

>tree /a /f
No subfolders exist
$ rm -r this_directory

$ tree --charset=ascii
`-- this_empty_directory

$ rm -r this_empty_directory

$ tree --charset=ascii
0 directories, 0 files
$ rm -rf this_directory

$ tree --charset=ascii
`-- this_empty_directory

$ rm -rf this_empty_directory

$ tree --charset=ascii
0 directories, 0 files

RMDIR /S AND RM -RI Here, we have a bit of a difference, but they're pretty close.

>rmdir /s this_directory
this_directory, Are you sure (Y/N)? y

>tree /a /f

>rmdir /s this_empty_directory
this_empty_directory, Are you sure (Y/N)? y

>tree /a /f
No subfolders exist
$ rm -ri this_directory
rm: descend into directory 'this_directory'? y
rm: remove regular file 'this_directory/some.txt'? y
rm: remove directory 'this_directory'? y

$ tree --charset=ascii
`-- this_empty_directory

$ rm -ri this_empty_directory
rm: remove directory 'this_empty_directory'? y

$ tree --charset=ascii
0 directories, 0 files



  1. I know almost nothing about the LeMoDa website, other than the fact that the info is

Copyright © Ben Bullock 2009-2018. All rights reserved.

(archived copyright notice)

and that there seem to be a bunch of useful programming tips along with some humour (yes, the British spelling) and information on how to fix Japanese toilets. I also found some stuff talking about the "Ibaraki Report", but I don't know if that is the website.

I think I shall go there more often; it's quite useful. Props to Ben Bullock, whose email is on his page. If he wants me to remove this info, I will.

I will include the disclaimer (archived) from the site:

Disclaimer Please read the following disclaimer before using any of the computer program code on this site.

There Is No Warranty For The Program, To The Extent Permitted By Applicable Law. Except When Otherwise Stated In Writing The Copyright Holders And/Or Other Parties Provide The Program “As Is” Without Warranty Of Any Kind, Either Expressed Or Implied, Including, But Not Limited To, The Implied Warranties Of Merchantability And Fitness For A Particular Purpose. The Entire Risk As To The Quality And Performance Of The Program Is With You. Should The Program Prove Defective, You Assume The Cost Of All Necessary Servicing, Repair Or Correction.

In No Event Unless Required By Applicable Law Or Agreed To In Writing Will Any Copyright Holder, Or Any Other Party Who Modifies And/Or Conveys The Program As Permitted Above, Be Liable To You For Damages, Including Any General, Special, Incidental Or Consequential Damages Arising Out Of The Use Or Inability To Use The Program (Including But Not Limited To Loss Of Data Or Data Being Rendered Inaccurate Or Losses Sustained By You Or Third Parties Or A Failure Of The Program To Operate With Any Other Programs), Even If Such Holder Or Other Party Has Been Advised Of The Possibility Of Such Damages.

  1. Actually, I found the information with a Google search for "cmd equivalent of rm"

The information I'm sharing came up first.

How to parse a CSV file in Bash?

From the man page:

-d delim The first character of delim is used to terminate the input line, rather than newline.

You are using -d, which will terminate the input line on the comma. It will not read the rest of the line. That's why $y is empty.

Convert a dataframe to a vector (by rows)

You can try this to get your combination:

as.numeric(rbind(test$x, test$y))

which will return:

26, 34, 21, 29, 20, 28

How to re import an updated package while in Python Interpreter?

No matter how many times you import a module, you'll get the same copy of the module from sys.modules - which was loaded at first import mymodule

I am answering this late, as each of the above/previous answer has a bit of the answer, so I am attempting to sum it all up in a single answer.

Using built-in function:

For Python 2.x - Use the built-in reload(mymodule) function.

For Python 3.x - Use the imp.reload(mymodule).

For Python 3.4 - In Python 3.4 imp has been deprecated in favor of importlib i.e. importlib.reload(mymodule)

Few caveats:

  • It is generally not very useful to reload built-in or dynamically loaded modules. Reloading sys, __main__, builtins and other key modules is not recommended.
  • In many cases extension modules are not designed to be initialized more than once, and may fail in arbitrary ways when reloaded. If a module imports objects from another module using from ... import ..., calling reload() for the other module does not redefine the objects imported from it — one way around this is to re-execute the from statement, another is to use import and qualified names ( instead.
  • If a module instantiates instances of a class, reloading the module that defines the class does not affect the method definitions of the instances — they continue to use the old class definition. The same is true for derived classes.

External packages:

reimport - Reimport currently supports Python 2.4 through 2.7.

xreload- This works by executing the module in a scratch namespace, and then patching classes, methods and functions in place. This avoids the need to patch instances. New objects are copied into the target namespace.

livecoding - Code reloading allows a running application to change its behaviour in response to changes in the Python scripts it uses. When the library detects a Python script has been modified, it reloads that script and replaces the objects it had previously made available for use with newly reloaded versions. As a tool, it allows a programmer to avoid interruption to their workflow and a corresponding loss of focus. It enables them to remain in a state of flow. Where previously they might have needed to restart the application in order to put changed code into effect, those changes can be applied immediately.

Get DOM content of cross-domain iframe

There is a simple way.

  1. You create an iframe which have for source something like "

  2. Then, you just get this url with $_GET and display the contents with file_get_contents($_GET['url']);

You will obtain an iframe which has a domain same than yours, then you will be able to use the $("iframe").contents().find("body") to manipulate the content.

Java synchronized method lock on object, or method?

If you have some methods which are not synchronized and are accessing and changing the instance variables. In your example:

 private int a;
 private int b;

any number of threads can access these non synchronized methods at the same time when other thread is in the synchronized method of the same object and can make changes to instance variables. For e.g :-

 public void changeState() {

You need to avoid the scenario that non synchronized methods are accessing the instance variables and changing it otherwise there is no point of using synchronized methods.

In the below scenario:-

class X {

        private int a;
        private int b;

        public synchronized void addA(){

        public synchronized void addB(){
     public void changeState() {

Only one of the threads can be either in addA or addB method but at the same time any number of threads can enter changeState method. No two threads can enter addA and addB at same time(because of Object level locking) but at same time any number of threads can enter changeState.

What does git rev-parse do?

git rev-parse is an ancillary plumbing command primarily used for manipulation.

One common usage of git rev-parse is to print the SHA1 hashes given a revision specifier. In addition, it has various options to format this output such as --short for printing a shorter unique SHA1.

There are other use cases as well (in scripts and other tools built on top of git) that I've used for:

  • --verify to verify that the specified object is a valid git object.
  • --git-dir for displaying the abs/relative path of the the .git directory.
  • Checking if you're currently within a repository using --is-inside-git-dir or within a work-tree using --is-inside-work-tree
  • Checking if the repo is a bare using --is-bare-repository
  • Printing SHA1 hashes of branches (--branches), tags (--tags) and the refs can also be filtered based on the remote (using --remote)
  • --parse-opt to normalize arguments in a script (kind of similar to getopt) and print an output string that can be used with eval

Massage just implies that it is possible to convert the info from one form into another i.e. a transformation command. These are some quick examples I can think of:

  • a branch or tag name into the commit's SHA1 it is pointing to so that it can be passed to a plumbing command which only accepts SHA1 values for the commit.
  • a revision range A..B for git log or git diff into the equivalent arguments for the underlying plumbing command as B ^A

ORA-01036: illegal variable name/number when running query through C#

I just spent several days checking parameters because I have to pass 60 to a stored procedure. It turns out that the one of the variable names (which I load into a list and pass to the Oracle Write method I created) had a space in the name at the end. When comparing to the variables in the stored procedure they were the same, but in the editor I used to compare them, I didnt notice the extra space. Drove me crazy for the last 4 days trying everything I could find, and changing even the .net Oracle driver. Just wanted to throw that out here so it can help someone else. We tend to concentrate on the characters and ignore the spaces. . .

How, in general, does Node.js handle 10,000 concurrent requests?

What you seem to be thinking is that most of the processing is handled in the node event loop. Node actually farms off the I/O work to threads. I/O operations typically take orders of magnitude longer than CPU operations so why have the CPU wait for that? Besides, the OS can handle I/O tasks very well already. In fact, because Node does not wait around it achieves much higher CPU utilisation.

By way of analogy, think of NodeJS as a waiter taking the customer orders while the I/O chefs prepare them in the kitchen. Other systems have multiple chefs, who take a customers order, prepare the meal, clear the table and only then attend to the next customer.

Could not establish trust relationship for SSL/TLS secure channel -- SOAP

I had a similar problem in .NET app in Internet Explorer.

I solved the problem adding the certificate (VeriSign Class 3 certificate in my case) to trusted editors certificates.

Go to Internet Options-> Content -> Publishers and import it

You can get the certificate if you export it from:

Internet Options-> Content -> Certificates -> Intermediate Certification Authorities -> VeriSign Class 3 Public Primary Certification Authority - G5


Generate a Hash from string in Javascript

I'm a bit surprised nobody has talked about the new SubtleCrypto API yet.

To get an hash from a string, you can use the subtle.digest method :

function getHash(str, algo = "SHA-256") {_x000D_
  let strBuf = new TextEncoder('utf-8').encode(str);_x000D_
  return crypto.subtle.digest(algo, strBuf)_x000D_
    .then(hash => {_x000D_
      window.hash = hash;_x000D_
      // here hash is an arrayBuffer, _x000D_
      // so we'll connvert it to its hex version_x000D_
      let result = '';_x000D_
      const view = new DataView(hash);_x000D_
      for (let i = 0; i < hash.byteLength; i += 4) {_x000D_
        result += ('00000000' + view.getUint32(i).toString(16)).slice(-8);_x000D_
      return result;_x000D_
getHash('hello world')_x000D_
  .then(hash => {_x000D_

RestClientException: Could not extract response. no suitable HttpMessageConverter found

Other possible solution : I tried to map the result of a restTemplate.getForObject with a private class instance (defined inside of my working class). It did not work, but if I define the object to public, inside its own file, it worked correctly.

Hive insert query like SQL

You still can insert into complex type in Hive - it works (id is int, colleagues array)

insert into emp (id,colleagues) select 11, array('Alex','Jian') from (select '1')

How to get terminal's Character Encoding

To see the current locale information use locale command. Below is an example on RHEL 7.8

[usr@host ~]$ locale

Replace "\\" with "\" in a string in C#

Regex.Unescape(string) method converts any escaped characters in the input string.

The Unescape method performs one of the following two transformations:

  1. It reverses the transformation performed by the Escape method by removing the escape character ("\") from each character escaped by the method. These include the \, *, +, ?, |, {, [, (,), ^, $, ., #, and white space characters. In addition, the Unescape method unescapes the closing bracket (]) and closing brace (}) characters.

  2. It replaces the hexadecimal values in verbatim string literals with the actual printable characters. For example, it replaces @"\x07" with "\a", or @"\x0A" with "\n". It converts to supported escape characters such as \a, \b, \e, \n, \r, \f, \t, \v, and alphanumeric characters.

string str = @"a\\b\\c";
var output = System.Text.RegularExpressions.Regex.Unescape(str);


XML Schema minOccurs / maxOccurs default values

New, expanded answer to an old, commonly asked question...

Default Values

  • Occurrence constraints minOccurs and maxOccurs default to 1.

Common Cases Explained

<xsd:element name="A"/>

means A is required and must appear exactly once.

<xsd:element name="A" minOccurs="0"/>

means A is optional and may appear at most once.

 <xsd:element name="A" maxOccurs="unbounded"/>

means A is required and may repeat an unlimited number of times.

 <xsd:element name="A" minOccurs="0" maxOccurs="unbounded"/>

means A is optional and may repeat an unlimited number of times.

See Also

  • W3C XML Schema Part 0: Primer

    In general, an element is required to appear when the value of minOccurs is 1 or more. The maximum number of times an element may appear is determined by the value of a maxOccurs attribute in its declaration. This value may be a positive integer such as 41, or the term unbounded to indicate there is no maximum number of occurrences. The default value for both the minOccurs and the maxOccurs attributes is 1. Thus, when an element such as comment is declared without a maxOccurs attribute, the element may not occur more than once. Be sure that if you specify a value for only the minOccurs attribute, it is less than or equal to the default value of maxOccurs, i.e. it is 0 or 1. Similarly, if you specify a value for only the maxOccurs attribute, it must be greater than or equal to the default value of minOccurs, i.e. 1 or more. If both attributes are omitted, the element must appear exactly once.

  • W3C XML Schema Part 1: Structures Second Edition

      maxOccurs = (nonNegativeInteger | unbounded)  : 1
      minOccurs = nonNegativeInteger : 1

How is OAuth 2 different from OAuth 1?

Note there are serious security arguments against using Oauth 2:

one bleak article

and a more technical one

Note these are coming from Oauth 2's lead author.

Key points:

  • Oauth 2 offers no security on top of SSL while Oauth 1 is transport-independent.

  • in a sense SSL isn't secure in that the server does not verify the connection and the common client libraries make it easy to ignore failures.

    The problem with SSL/TLS, is that when you fail to verify the certificate on the client side, the connection still works. Any time ignoring an error leads to success, developers are going to do just that. The server has no way of enforcing certificate verification, and even if it could, an attacker will surely not.

  • you can fat-finger away all of your security, which is much harder to do in OAuth 1.0:

    The second common potential problem are typos. Would you consider it a proper design when omitting one character (the ‘s’ in ‘https’) voids the entire security of the token? Or perhaps sending the request (over a valid and verified SSL/TLS connection) to the wrong destination (say ‘’?). Remember, being able to use OAuth bearer tokens from the command line was clearly a use case bearer tokens advocates promoted.

What does it mean to inflate a view from an xml file?

Inflating is the process of adding a view (.xml) to activity on runtime. When we create a listView we inflate each of its items dynamically. If we want to create a ViewGroup with multiple views like buttons and textview, we can create it like so:

Button but = new Button();
but.setText ="button text";
but.background ...
but.leftDrawable.. and so on...

TextView txt = new TextView();
txt.setText ="button text";
txt.background ... and so on...

Then we have to create a layout where we can add above views:

RelativeLayout rel = new RelativeLayout();


And now if we want to add a button in the right-corner and a textview on the bottom, we have to do a lot of work. First by instantiating the view properties and then applying multiple constraints. This is time consuming.

Android makes it easy for us to create a simple .xml and design its style and attributes in xml and then simply inflate it wherever we need it without the pain of setting constraints programatically.

LayoutInflater inflater = 
View menuLayout = inflater.inflate(R.layout.your_menu_layout, mainLayout, true);
//now add menuLayout to wherever you want to add like


what is the difference between $_SERVER['REQUEST_URI'] and $_GET['q']?

In the context of Drupal, the difference will depend whether clean URLs are on or not.

With them off, $_SERVER['REQUEST_URI'] will have the full path of the page as called w/ /index.php, while $_GET["q"] will just have what is assigned to q.

With them on, they will be nearly identical w/o other arguments, but $_GET["q"] will be missing the leading /. Take a look towards the end of the default .htaccess to see what is going on. They will also differ if additional arguments are passed into the page, eg when a pager is active.

What does it mean "No Launcher activity found!"

You have not included Launcher intent filter in activity you want to appear first, so it does not know which activity to start when application launches, for this tell the system by including launcher filter intent in manifest.xml

How line ending conversions work with git core.autocrlf between different operating systems

No, the @jmlane answer is wrong.

For Checkin (git add, git commit):

  1. if text property is Set, Set value to 'auto', the conversion happens enen the file has been committed with 'CRLF'
  2. if text property is Unset:nothing happens, enen for Checkout
  3. if text property is Unspecified, conversion depends on core.autocrlf
    1. if autocrlf = input or autocrlf = true, the conversion only happens when the file in the repository is 'LF', if it has been 'CRLF', nothing will happens.
    2. if autocrlf = false, nothing happens

For Checkout:

  1. if text property is Unset: nothing happens.
  2. if text property is Set, Set value to 'auto: it depends on core.autocrlf, core.eol.
    1. core.autocrlf = input : nothing happens
    2. core.autocrlf = true : the conversion only happens when the file in the repository is 'LF', 'LF' -> 'CRLF'
    3. core.autocrlf = false : the conversion only happens when the file in the repository is 'LF', 'LF' -> core.eol
  3. if text property is Unspecified, it depends on core.autocrlf.
    1. the same as 2.1
    2. the same as 2.2
    3. None, nothing happens, core.eol is not effective when text property is Unspecified

Default behavior

So the Default behavior is text property is Unspecified and core.autocrlf = false:

  1. for checkin, nothing happens
  2. for checkout, nothing happens


  1. if text property is set, checkin behavior is depends on itself, not on autocrlf
  2. autocrlf or core.eol is for checkout behavior, and autocrlf > core.eol

TypeError: can't use a string pattern on a bytes-like object in re.findall()

The problem is that your regex is a string, but html is bytes:

>>> type(html)
<class 'bytes'>

Since python doesn't know how those bytes are encoded, it throws an exception when you try to use a string regex on them.

You can either decode the bytes to a string:

html = html.decode('ISO-8859-1')  # encoding may vary!
title = re.findall(pattern, html)  # no more error

Or use a bytes regex:

regex = rb'<title>(,+?)</title>'
#        ^

In this particular context, you can get the encoding from the response headers:

with urllib.request.urlopen(url) as response:
    encoding ='charset', 'utf8')
    html =

See the urlopen documentation for more details.

How to parse unix timestamp to time.Time

Sharing a few functions which I created for dates:

Please note that I wanted to get time for a particular location (not just UTC time). If you want UTC time, just remove loc variable and .In(loc) function call.

func GetTimeStamp() string {
     loc, _ := time.LoadLocation("America/Los_Angeles")
     t := time.Now().In(loc)
     return t.Format("20060102150405")
func GetTodaysDate() string {
    loc, _ := time.LoadLocation("America/Los_Angeles")
    current_time := time.Now().In(loc)
    return current_time.Format("2006-01-02")

func GetTodaysDateTime() string {
    loc, _ := time.LoadLocation("America/Los_Angeles")
    current_time := time.Now().In(loc)
    return current_time.Format("2006-01-02 15:04:05")

func GetTodaysDateTimeFormatted() string {
    loc, _ := time.LoadLocation("America/Los_Angeles")
    current_time := time.Now().In(loc)
    return current_time.Format("Jan 2, 2006 at 3:04 PM")

func GetTimeStampFromDate(dtformat string) string {
    form := "Jan 2, 2006 at 3:04 PM"
    t2, _ := time.Parse(form, dtformat)
    return t2.Format("20060102150405")

convert HTML ( having Javascript ) to PDF using JavaScript

You can do it using a jquery,

Use this code to link the button...

$(document).ready(function() {
    $("#button_id").click(function() {
        return false;

This link may be also helpful: jQuery Print HTML Pdf Page Options Link

Delaying function in swift

You can use GCD (in the example with a 10 second delay):

Swift 2

let triggerTime = (Int64(NSEC_PER_SEC) * 10)
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, triggerTime), dispatch_get_main_queue(), { () -> Void in

Swift 3 and Swift 4

DispatchQueue.main.asyncAfter(deadline: .now() + 10.0, execute: {

Swift 5 or Later

 DispatchQueue.main.asyncAfter(deadline: .now() + 10.0) {
        //call any function

Notepad++ cached files location

I lost somehow my temporary notepad++ files, they weren't showing in tabs. So I did some search in appdata folder, and I found all my temporary files there. It seems that they are stored there for a long time.




C# LINQ select from list

The "in" in Linq-To-Sql uses a reverse logic compared to a SQL query.

Let's say you have a list of integers, and want to find the items that match those integers.

int[] numbers = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

var items = from p in context.Items
                 where numbers.Contains(p.ItemId)
                select p;

Anyway, the above works fine in linq-to-sql but not in EF 1.0. Haven't tried it in EF 4.0

Windows Task Scheduler doesn't start batch file task

Make sure you set the 'Start in' and 'Program/script' options correctly. If your file address is: C:\Temp\foo.bat, set the 'start in' option to 'C:\Temp' and the 'Program/script' option to 'foo.bat'.

To set the 'Start in' option: Right click task in the task scheduler > Properties > Actions > Edit.

If this alone doesn't work then try moving the .bat file to a directory with basic permissions (maybe a shared directory for example).

I had a problem where my .bat file was located in a folder with some restrictive permissions on it, so that only my user account could access it. Even though I had set up the task scheduler to use my credentials it still failed. Moving the .bat file to another directory sorted the issue.

How to request Location Permission at runtime

check this code from MainActivity

 // Check location permission is granted - if it is, start
// the service, otherwise request the permission
fun checkOrAskLocationPermission(callback: () -> Unit) {
    // Check GPS is enabled
    val lm = getSystemService(Context.LOCATION_SERVICE) as LocationManager
    if (!lm.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
        Toast.makeText(this, "Please enable location services", Toast.LENGTH_SHORT).show()

    // Check location permission is granted - if it is, start
    // the service, otherwise request the permission
    val permission = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
    if (permission == PackageManager.PERMISSION_GRANTED) {
    } else {
        // callback will be inside the activity's onRequestPermissionsResult(


   override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults)
    if (requestCode == PERMISSIONS_REQUEST) {
        if (grantResults[0] == PackageManager.PERMISSION_GRANTED){
              // Permission ok. Do work.


 fun buildAlertMessageNoGps(context: Context) {
    val builder = AlertDialog.Builder(context);
    builder.setMessage("Your GPS is disabled. Do you want to enable it?")
        .setPositiveButton("Yes") { _, _ -> context.startActivity(Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS)) }
        .setNegativeButton("No") { dialog, _ -> dialog.cancel(); }
    val alert = builder.create();;


checkOrAskLocationPermission() {
            // Permission ok. Do work.

AngularJs ReferenceError: angular is not defined

Always make sure that js file (angular.min.js) is referenced first in the HTML file. For example:

----------------- This reference will THROW error -------------------------

< script src="otherXYZ.js"></script>
< script src="angular.min.js"></script>

----------------- This reference will WORK as expected -------------------

< script src="angular.min.js"></script>
< script src="otherXYZ.js"></script>

What does "@" mean in Windows batch scripts

The @ disables echo for that one command. Without it, the echo start eclipse.exe line would print both the intended start eclipse.exe and the echo start eclipse.exe line.

The echo off turns off the by-default command echoing.

So @echo off silently turns off command echoing, and only output the batch author intended to be written is actually written.

Error: [$injector:unpr] Unknown provider: $routeProvider

It looks like you forgot to include the ngRoute module in your dependency for myApp.

In Angular 1.2, they've made ngRoute optional (so you can use third-party route providers, etc.) and you have to explicitly depend on it in modules, along with including the separate file.

'use strict';

angular.module('myApp', ['ngRoute']).
    config(['$routeProvider', function($routeProvider) {
$routeProvider.otherwise({redirectTo: '/home'});

'Syntax Error: invalid syntax' for no apparent reason

You're missing a close paren in this line:


There are three ( and only two ).
I hope This will help you.

Spring Boot - How to get the running port

You can get the port that is being used by an embedded Tomcat instance during tests by injecting the local.server.port value as such:

// Inject which port we were assigned
int port;

How can I copy a conditional formatting from one document to another?

You can also copy a cell which contains the conditional formatting and then select the range (of destination document -or page-) where you want the conditional format to be applied and select "paste special" > "paste only conditional formatting"

SQL Bulk Insert with FIRSTROW parameter skips the following line

To let SQL handle quote escape and everything else do this

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

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

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

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

enter image description here

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Why is the default value of the string type null instead of an empty string?

You could also use the following, as of C# 6.0

string myString = null;
string result = myString?.ToUpper();

The string result will be null.

How to get current foreground activity context in android?

Personally I did as "Cheok Yan Cheng" said, but I used a "List" to have a "Backstack" of all my activities.

If you want to check Which is the Current Activity you just need to get the last activity class in the list.

Create an application which extends "Application" and do this:

public class MyApplication extends Application implements Application.ActivityLifecycleCallbacks,
EndSyncReceiver.IEndSyncCallback {

private List<Class> mActivitiesBackStack;
private EndSyncReceiver mReceiver;
    private Merlin mMerlin;
    private boolean isMerlinBound;
    private boolean isReceiverRegistered;

    public void onCreate() {
        mActivitiesBackStack = new ArrayList<>();

/* START Override ActivityLifecycleCallbacks Methods */
    public void onActivityCreated(Activity activity, Bundle bundle) {

    public void onActivityStarted(Activity activity) {

    public void onActivityResumed(Activity activity) {


    public void onActivityPaused(Activity activity) {


    public void onActivityStopped(Activity activity) {
            if(isMerlinBound) {
            if(RealmHelper.getInstance() != null){

    public void onActivitySaveInstanceState(Activity activity, Bundle bundle) {


    public void onActivityDestroyed(Activity activity) {
    /* END Override ActivityLifecycleCallbacks Methods */

/* START Override IEndSyncCallback Methods */
    public void onEndSync(Intent intent) {
        Constants.SyncType syncType = null;
            syncType = (Constants.SyncType) intent.getSerializableExtra(Constants.INTENT_DATA_SYNC_TYPE);
        if(syncType != null){
    /* END IEndSyncCallback Methods */

private void checkSyncType(Constants.SyncType){
    if( mActivitiesBackStack.contains(ActivityClass.class) ){
         doOperation()     }


In my case I used "Application.ActivityLifecycleCallbacks" to:

  • Bind/Unbind Merlin Instance (used to get event when the app lose or get connection, for example when you close mobile data or when you open it). It is useful after the "OnConnectivityChanged" intent action was disabled. For more info about MERLIN see: MERLIN INFO LINK

  • Close my last Realm Instance when the application is closed; I will init it inside a BaseActivity wich is extended from all others activities and which has a private RealmHelper Instance. For more info about REALM see: REALM INFO LINK For instance I have a static "RealmHelper" instance inside my "RealmHelper" class which is instantiated inside my application "onCreate". I have a synchronization service in which I create I new "RealmHelper" because Realm is "Thread-Linked" and a Realm Instance can't work inside a different Thread. So in order to follow Realm Documentation "You Need To Close All Opened Realm Instances to avoid System Resources Leaks", to accomplish this thing I used the "Application.ActivityLifecycleCallbacks" as you can see up.

  • Finally I have a receiver wich is triggered when I finish to synchronize my application, then when the sync end it will call the "IEndSyncCallback" "onEndSync" method in which I look if I have a specific Activity Class inside my ActivitiesBackStack List because I need to update the data on the view if the sync updated them and I could need to do others operations after the app sync.

That's all, hope this is helpful. See u :)

Only using @JsonIgnore during serialization, but not deserialization

"user": {
        "firstName": "Musa",
        "lastName": "Aliyev",
        "email": "[email protected]",
        "passwordIn": "98989898", (or encoded version in front if we not using https)
        "country": "Azeribaijan",
        "phone": "+994707702747"

public @ResponseBody MsgKit registerNewUsert(@RequestBody User u){


    return new MsgKit("registered");

public class RootBsn {

    @Autowired UserRepository userRepo;

    public void registerUser(User u) throws Exception{

        //Generate some salt and  setPassword (encoded -  salt+password)

        System.out.println("Registration information saved");


                    public class User implements Serializable {
                        private static final long serialVersionUID = 1L;

                        private Long id;

                        private String country;

                        private String createdBy;

                        private String email;

                        private String firstName;

                        private Timestamp lastLoginDate;

                        private String lastName;

                        private Timestamp modificationDate;

                        private String modifiedBy;

                        private String password;

                        private String passwordIn;

                        private String phone;

                        private Timestamp recordDate;

                        private String salt;

                        private String status;

                        private String userStatus;

                        public User() {
                // getters and setters

NavigationBar bar, tint, and title text color in iOS 8

Updated with swift 4

override func viewDidLoad() {
        self.navigationController?.navigationBar.tintColor =
        self.navigationController?.navigationBar.barStyle =

Clear form fields with jQuery

Some of you were complaining that radios and such are cleared of default "checked" status... All you have to do is add the :radio, :checkbox selectors to the .not and the problem is solved.

If you can't get all the other reset functions to work, this one will.

  • Adapted from ngen's answer

    function form_reset(formID){

Java Compare Two Lists

You can try intersection() and subtract() methods from CollectionUtils.

intersection() method gives you a collection containing common elements and the subtract() method gives you all the uncommon ones.

They should also take care of similar elements

How to reload a page using JavaScript

This works for me:

function refresh() {    
    setTimeout(function () {
    }, 100);

Textarea that can do syntax highlighting on the fly?

Why are you representing them as textareas? This is my favorite:

But if you are using a CMS, there's probably a better plugin. For example, wordpress has an evolved version:

How do I check if a variable exists?

The use of variables that have yet to been defined or set (implicitly or explicitly) is often a bad thing in any language, since it tends to indicate that the logic of the program hasn't been thought through properly, and is likely to result in unpredictable behaviour.

If you need to do it in Python, the following trick, which is similar to yours, will ensure that a variable has some value before use:

except NameError:
    myVar = None      # or some other default value.

# Now you're free to use myVar without Python complaining.

However, I'm still not convinced that's a good idea - in my opinion, you should try to refactor your code so that this situation does not occur.

Use a.any() or a.all()

This should also work and is a closer answer to what is asked in the question:

for i in range(len(x)):
    if valeur.item(i) <= 0.6:
        print ("this works")
        print ("valeur is too high")

How do I read all classes from a Java package in the classpath?

Java 1.6.0_24:

public static File[] getPackageContent(String packageName) throws IOException{
    ArrayList<File> list = new ArrayList<File>();
    Enumeration<URL> urls = Thread.currentThread().getContextClassLoader()
    while (urls.hasMoreElements()) {
        URL url = urls.nextElement();
        File dir = new File(url.getFile());
        for (File f : dir.listFiles()) {
    return list.toArray(new File[]{});

This solution was tested within the EJB environment.

How to stretch a table over multiple pages

You should \usepackage{longtable}.

ini_set("memory_limit") in PHP 5.3.3 is not working at all

Works for me, has nothing to do with PHP 5.3. Just like many such options it cannot be overriden via ini_set() when safe_mode is enabled. Check your updated php.ini (and better yet: change the memory_limit there too).

Python Socket Multiple Clients

import sys
import os
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)         
port = 50000

    s.bind((socket.gethostname() , port))
except socket.error as msg:
conn, addr = s.accept()  
print 'Got connection from'+addr[0]+':'+str(addr[1]))
while 1:
        msg = s.recv(1024)
        print +addr[0]+, ' >> ', msg
        msg = raw_input('SERVER >>'),host

jQuery - Create hidden form element on the fly

if you want to add more attributes just do like:



    type: 'hidden',
    id: 'foo',
    name: 'foo[]',
    value: 'bar'

How to get an object's methods?

function getMethods(obj)
    var res = [];
    for(var m in obj) {
        if(typeof obj[m] == "function") {
    return res;

Error: TypeError: $(...).dialog is not a function

if some reason two versions of jQuery are loaded (which is not recommended), calling $.noConflict(true) from the second version will return the globally scoped jQuery variables to those of the first version.

Some times it could be issue with older version (or not stable version) of JQuery files

Solution use $.noConflict();

<script src="other_lib.js"></script>
<script src="jquery.js"></script>
jQuery( document ).ready(function( $ ) {
   $("#opener").click(function() {
// Code that uses other library's $ can follow here.


In my case TOP LEVEL EXCEPTION was throw because of a special char in project path. Just closed the project, changed "á" to "a" and reopened the project. Works!

C++ Erase vector element by value rather than by position?

How about std::remove() instead:

#include <algorithm>
vec.erase(std::remove(vec.begin(), vec.end(), 8), vec.end());

This combination is also known as the erase-remove idiom.

C++ undefined reference to defined function

The declaration and definition of insertLike are different

In your header file:

void insertLike(const char sentence[], const int lengthTo, const int length, const char writeTo[]);

In your 'function file':

void insertLike(const char sentence[], const int lengthTo, const int length,char writeTo[]);

C++ allows function overloading, where you can have multiple functions/methods with the same name, as long as they have different arguments. The argument types are part of the function's signature.

In this case, insertLike which takes const char* as its fourth parameter and insertLike which takes char * as its fourth parameter are different functions.

Changing image sizes proportionally using CSS?

Put it as a background on your holder e.g.

<div style="background:url(path/to/image/myimage.jpg) center center; width:120px; height:120px;">

This will center your image inside a 120x120 div chopping off any excess of the image

Full width layout with twitter bootstrap

You'll find a great tutorial here: bootstrap-3-grid-introduction and answer for your question is <div class="container-fluid"> ... </div>

How do you POST to a page using the PHP header() function?

There is a good class that does what you want. It can be downloaded at:

Click a button with XPath containing partial id and title in Selenium IDE

Now that you have provided your HTML sample, we're able to see that your XPath is slightly wrong. While it's valid XPath, it's logically wrong.

You've got:

//*[contains(@id, 'ctl00_btnAircraftMapCell')]//*[contains(@title, 'Select Seat')]

Which translates into:

Get me all the elements that have an ID that contains ctl00_btnAircraftMapCell. Out of these elements, get any child elements that have a title that contains Select Seat.

What you actually want is:

//a[contains(@id, 'ctl00_btnAircraftMapCell') and contains(@title, 'Select Seat')]

Which translates into:

Get me all the anchor elements that have both: an id that contains ctl00_btnAircraftMapCell and a title that contains Select Seat.

How to upload files to server using Putty (ssh)

"C:\Program Files\PuTTY\pscp.exe" -scp will be uploaded into your HOME dir on remote server.

or when the remote server has a different user, use "C:\Program Files\PuTTY\pscp.exe" -l username -scp

After connecting to the server pscp will ask for a password.

C/C++ include header file order

To add my own brick to the wall.

  1. Each header needs to be self-sufficient, which can only be tested if it's included first at least once
  2. One should not mistakenly modify the meaning of a third-party header by introducing symbols (macro, types, etc.)

So I usually go like this:

// myproject/src/example.cpp
#include "myproject/example.h"

#include <algorithm>
#include <set>
#include <vector>

#include <3rdparty/foo.h>
#include <3rdparty/bar.h>

#include "myproject/another.h"
#include "myproject/specific/bla.h"

#include "detail/impl.h"

Each group separated by a blank line from the next one:

  • Header corresponding to this cpp file first (sanity check)
  • System headers
  • Third-party headers, organized by dependency order
  • Project headers
  • Project private headers

Also note that, apart from system headers, each file is in a folder with the name of its namespace, just because it's easier to track them down this way.

Removing leading zeroes from a field in a SQL statement

I had the same need and used this:

        when left(column,1) = '0' 
        then right(column, (len(column)-1)) 
        else column 

How can I add an ampersand for a value in a app config file value

Have you tried this?

  <add key="myurl" value=";cid=&amp;sid="/>

Execute a file with arguments in Python shell

runfile('', ['arg1', 'arg2'])

How can I check if a JSON is empty in NodeJS?

You can use this:

var isEmpty = function(obj) {
  return Object.keys(obj).length === 0;

or this:

function isEmpty(obj) {
  return !Object.keys(obj).length > 0;

You can also use this:

function isEmpty(obj) {
  for(var prop in obj) {
      return false;

  return true;

If using underscore or jQuery, you can use their isEmpty or isEmptyObject calls.

Table header to stay fixed at the top when user scrolls it out of view with jQuery

There are many really good solution here already. But one of the simplest CSS only solutions that I use in these situations is as follows:

table {_x000D_
  /* Not required only for visualizing */_x000D_
  border-collapse: collapse;_x000D_
  width: 100%;_x000D_
table thead tr th {_x000D_
  /* Important */_x000D_
  background-color: red;_x000D_
  position: sticky;_x000D_
  z-index: 100;_x000D_
  top: 0;_x000D_
td {_x000D_
  /* Not required only for visualizing */_x000D_
  padding: 1em;_x000D_

Because there is no requirement for JavaScript it simplifies the situation significantly. You essentially need to focus on the second CSS rule, which contains the conditions for ensuring that the head of the table remains of the top no matter the scroll space.

To elaborate on each of the rules in detail. position is meant to indicate to the browser that the head object, its row, and its cells all need to stick to the top. This necessarily needs to be accompanied by top, which specifies to the browser that the head will stick to the top of the page or viewport. Additionally, you can add z-index to ensure that the content of the head always remains on the top.

The background colour is merely to illustrate the point. You do not need to use any additional JavaScript to get this effect. This is supported in most major browsers after 2016.

Razor MVC Populating Javascript array with Model Array

JSON syntax is pretty much the JavaScript syntax for coding your object. Therefore, in terms of conciseness and speed, your own answer is the best bet.

I use this approach when populating dropdown lists in my KnockoutJS model. E.g.

var desktopGrpViewModel = {
    availableComputeOfferings: ko.observableArray(@Html.Raw(JsonConvert.SerializeObject(ViewBag.ComputeOfferings))),
    desktopGrpComputeOfferingSelected: ko.observable(),


<select name="ComputeOffering" class="form-control valid" id="ComputeOffering" data-val="true" 
data-bind="options: availableComputeOffering,
           optionsText: 'Name',
           optionsValue: 'Id',
           value: desktopGrpComputeOfferingSelect,
           optionsCaption: 'Choose...'">

Note that I'm using Json.NET NuGet package for serialization and the ViewBag to pass data.

is there any IE8 only css hack?

I was looking for a good option for IE10 and below CSS styling (but it would work for IE8 only as well) and I came up with this idea:

<!--[if lt IE 10]><div class="column IE10-fix"><![endif]-->
<!--[if !lt IE 10]><!--><div class="column"><!--<![endif]-->

I declare my div or whatever you want with an extra class, this allows me to have extra CSS in the same stylesheet in a very readable manner.

It's W3C valid and not a weird CSS hack.

Switch statement with returns -- code correctness

Wouldn't it be better to have an array with

arr[0] = "blah"
arr[1] = "foo"
arr[2] = "bar"

and do return arr[something];?

If it's about the practice in general, you should keep the break statements in the switch. In the event that you don't need return statements in the future, it lessens the chance it will fall through to the next case.

Options for embedding Chromium instead of IE WebBrowser control with WPF/C#

You've already listed the most notable solutions for embedding Chromium (CEF, Chrome Frame, Awesomium). There aren't any more projects that matter.

There is still the Berkelium project (see Berkelium Sharp and Berkelium Managed), but it emebeds an old version of Chromium.

CEF is your best bet - it's fully open source and frequently updated. It's the only option that allows you to embed the latest version of Chromium. Now that Per Lundberg is actively working on porting CEF 3 to CefSharp, this is the best option for the future. There is also Xilium.CefGlue, but this one provides a low level API for CEF, it binds to the C API of CEF. CefSharp on the other hand binds to the C++ API of CEF.

Adobe is not the only major player using CEF, see other notable applications using CEF on the CEF wikipedia page.

Updating Chrome Frame is pointless since the project has been retired.

Excel VBA - read cell value from code

I think you need this ..

Dim n as Integer   

For n = 5 to 17
  msgbox cells(n,3) '--> sched waste
  msgbox cells(n,4) '--> type of treatm
  msgbox format(cells(n,5),"dd/MM/yyyy") '--> Lic exp
  msgbox cells(n,6) '--> email col

Javascript form validation with password confirming

 if ($("#Password").val() != $("#ConfirmPassword").val()) {
          alert("Passwords do not match.");

A JQuery approach that will eliminate needless code.

List of Stored Procedures/Functions Mysql Command Line

As of MySQL 8.0, the mysql.procs table has been removed. Running any of the commands from answers here that use this table will yield you an error that says (quite logically):

Table 'mysql.proc' doesn't exist

Instead, to retrieve a list of only the names of procedures/functions, use:

SELECT specific_name FROM `information_schema`.`ROUTINES` WHERE routine_schema='<your_db_name>';

In my case, I edited it to show only the procedures and not the functions:

SELECT specific_name FROM `information_schema`.`ROUTINES` WHERE routine_schema='<your_db_name>' AND routine_type='PROCEDURE';

Just get column names from hive table

you could also do show columns in $table or see Hive, how do I retrieve all the database's tables columns for access to hive metadata

What does 'git blame' do?

The git blame command is used to examine the contents of a file line by line and see when each line was last modified and who the author of the modifications was.

If there was a bug in code,use it to identify who cased it,then you can blame him. Git blame is get blame(d).

If you need to know history of one line code,use git log -S"code here", simpler than git blame.

git log vs git blame

Could not load file or assembly 'System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies

Even I have experience some more strange things, I can see there is no dll in GAC from where the dll is loading but windows > Module shows system.dll version= loaded

How do I explicitly specify a Model's table-name mapping in Rails?

class Countries < ActiveRecord::Base
    self.table_name = "cc"

In Rails 3.x this is the way to specify the table name.

Toggle Checkboxes on/off

//this toggles the checkbox, and fires its event if it has    


SSRS - Checking whether the data is null

try like this

= IIF( MAX( iif( IsNothing(Fields!.Reading.Value ), -1, Fields!.Reading.Value ) ) = -1, "",  FormatNumber(  MAX( iif( IsNothing(Fields!.Reading.Value ), -1, Fields!.Reading.Value ), "CellReading_Reading"),3)) )

Android: Create a toggle button with image and no text

  1. Can I replace the toggle text with an image

    No, we can not, although we can hide the text by overiding the default style of the toggle button, but still that won't give us a toggle button you want as we can't replace the text with an image.

  2. How can I make a normal toggle button

    Create a file ic_toggle in your res/drawable folder

    <selector xmlns:android="">
        <item android:state_checked="false"
              android:drawable="@drawable/ic_slide_switch_off" />
        <item android:state_checked="true"
              android:drawable="@drawable/ic_slide_switch_on" />

    Here @drawable/ic_slide_switch_on & @drawable/ic_slide_switch_off are images you create.

    Then create another file in the same folder, name it ic_toggle_bg

    <?xml version="1.0" encoding="utf-8"?>
    <layer-list xmlns:android="">
        <item android:id="@+android:id/background"  
              android:drawable="@android:color/transparent" />
        <item android:id="@+android:id/toggle"
              android:drawable="@drawable/ic_toggle" />

    Now add to your custom theme, (if you do not have one create a styles.xml file in your res/values/folder)

    <style name="Widget.Button.Toggle" parent="android:Widget">
       <item name="android:background">@drawable/ic_toggle_bg</item>
       <item name="android:disabledAlpha">?android:attr/disabledAlpha</item>
    <style name="toggleButton"  parent="@android:Theme.Black">
       <item name="android:buttonStyleToggle">@style/Widget.Button.Toggle</item>
       <item name="android:textOn"></item>
       <item name="android:textOff"></item>

    This creates a custom toggle button for you.

  3. How to use it

    Use the custom style and background in your view.


Refreshing data in RecyclerView and keeping its scroll position

I have not used Recyclerview but I did it on ListView. Sample code in Recyclerview:

setOnScrollListener(new RecyclerView.OnScrollListener() {
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        rowPos = mLayoutManager.findFirstVisibleItemPosition();

It is the listener when user is scrolling. The performance overhead is not significant. And the first visible position is accurate this way.

Difference between declaring variables before or in loop?

As a general rule, I declare my variables in the inner-most possible scope. So, if you're not using intermediateResult outside of the loop, then I'd go with B.

How to disable the back button in the browser using JavaScript

history.pushState(null, null, document.title);
window.addEventListener('popstate', function () {
    history.pushState(null, null, document.title);

This script will overwrite attempts to navigate back and forth with the state of the current page.


Some users have reported better success with using document.URL instead of document.title:

history.pushState(null, null, document.URL);
window.addEventListener('popstate', function () {
    history.pushState(null, null, document.URL);

Spring + Web MVC: dispatcher-servlet.xml vs. applicationContext.xml (plus shared security)

To add to Kevin's answer, I find that in practice nearly all of your non-trivial Spring MVC applications will require an application context (as opposed to only the spring MVC dispatcher servlet context). It is in the application context that you should configure all non-web related concerns such as:

  • Security
  • Persistence
  • Scheduled Tasks
  • Others?

To make this a bit more concrete, here's an example of the Spring configuration I've used when setting up a modern (Spring version 4.1.2) Spring MVC application. Personally, I prefer to still use a WEB-INF/web.xml file but that's really the only xml configuration in sight.


<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="" xmlns:xsi="" xsi:schemaLocation="" version="3.1">






@ComponentScan(basePackages = "")
public class WebConfig {

  public InternalResourceViewResolver getInternalResourceViewResolver() {
    InternalResourceViewResolver resolver = new InternalResourceViewResolver();
    return resolver;

@ComponentScan(basePackages = "")
@Import(value = {SecurityConfig.class, PersistenceConfig.class, ScheduleConfig.class})
public class AppConfig {
  // application domain @Beans here...

public class SecurityConfig extends WebSecurityConfigurerAdapter {
  private LdapUserDetailsMapper ldapUserDetailsMapper;

    protected void configure(HttpSecurity http) throws Exception {

    http.logout().logoutRequestMatcher(new AntPathRequestMatcher("/logout"));

    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
      .userSearchBase("OU=App Users")

  private LdapContextSource getLdapContextSource() {
    LdapContextSource cs = new LdapContextSource();
    return cs;

@EnableJpaRepositories(transactionManagerRef = "getTransactionManager", entityManagerFactoryRef = "getEntityManagerFactory", basePackages = "")
public class PersistenceConfig {

  public LocalContainerEntityManagerFactoryBean getEntityManagerFactory(DataSource dataSource) {
    LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
    return lef;

  private HibernateJpaVendorAdapter getHibernateJpaVendorAdapter() {
    HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
    return hibernateJpaVendorAdapter;

  public JndiObjectFactoryBean getDataSource() {
    JndiObjectFactoryBean jndiFactoryBean = new JndiObjectFactoryBean();
    return jndiFactoryBean;

  public JpaTransactionManager getTransactionManager(DataSource dataSource) {
    JpaTransactionManager jpaTransactionManager = new JpaTransactionManager();
    return jpaTransactionManager;

public class ScheduleConfig {
  private EmployeeSynchronizer employeeSynchronizer;

  // cron pattern: sec, min, hr, day-of-month, month, day-of-week, year (optional)
  @Scheduled(cron="0 0 0 * * *")
  public void employeeSync() {

As you can see, the web configuration is only a small part of the overall spring web application configuration. Most web applications I've worked with have many concerns that lie outside of the dispatcher servlet configuration that require a full-blown application context bootstrapped via the org.springframework.web.context.ContextLoaderListener in the web.xml.

How do I load a file into the python console?

If your path environment variable contains Python (eg. C:\Python27\) you can run your py file simply from Windows command line (cmd). Howto here.

PostgreSQL wildcard LIKE for any of a list of words

All currently supported versions (9.5 and up) allow pattern matching in addition to LIKE.


C++ variable has initializer but incomplete type?

You use a forward declaration when you need a complete type.

You must have a full definition of the class in order to use it.

The usual way to go about this is:

1) create a file Cat_main.h

2) move

#include <string>

class Cat
        Cat(std::string str);
    // Variables
        std::string name;
    // Functions
        void Meow();

to Cat_main.h. Note that inside the header I removed using namespace std; and qualified string with std::string.

3) include this file in both Cat_main.cpp and Cat.cpp:

#include "Cat_main.h"

open link in iframe

Try this:

<iframe name="iframe1" src="target.html"></iframe>

<a href="link.html" target="iframe1">link</a>

The "target" attribute should open in the iframe.

Unable to read data from the transport connection : An existing connection was forcibly closed by the remote host

Another option would be to check the error code generated using try-catch block and first catching a WebException.

In my case, the error code was "SendFailure" because of certificate issue on HTTPS url, once I hit HTTP, that got resolved.

Android Eclipse - Could not find *.apk

None of these things worked for me. I'm trying to access native code through the jni, first with NDK samples. What I found was the build won't run if jarlist.cache is not present in the project bin directory. If I copy one from another project to that location (may need to refresh to see the folder in Eclipse), build works every time.

CodeIgniter PHP Model Access "Unable to locate the model you have specified"

I resolve this with this way:

  1. I rename file do Page_model.php
  2. Class name to Page_model extends...
  3. I call on autoload: $autoload['model'] = array('Page_model'=>'page');

Works fine.. I hope help.

How do you dynamically allocate a matrix?

The other answer describing arrays of arrays are correct.
BUT if you are planning of doing a anything mathematical with the arrays - or need something special like sparse matrices you should look at one of the many maths libs like TNT before re-inventing too many wheels

How do I get the current Date/time in DD/MM/YYYY HH:MM format?

require 'date'

current_time =

current_time.strftime "%d/%m/%Y %H:%M"
# => "14/09/2011 17:02"

current_time.next_month.strftime "%d/%m/%Y %H:%M"
# => "14/10/2011 17:02" cannot identify image file - Python?

I had a same issue.

from PIL import Image

instead of

import Image

fixed the issue

How to delete a specific line in a file?

Save the file lines in a list, then remove of the list the line you want to delete and write the remain lines to a new file

with open("file_name.txt", "r") as f:
    lines = f.readlines() 
    lines.remove("Line you want to delete\n")
    with open("new_file.txt", "w") as new_f:
        for line in lines:        

Django DateField default options

date = models.DateTimeField(, blank=True)

@font-face not working

I had this problem recently and the problem was that my web server was not configured to serve woff files. For IIS 7, you can select your site, then select the MIME Types icon. If .woff is not in the list, you need to add it. The correct values are

File name extension: .woff
MIME type: application/font-woff

How to revert the last migration?

If you are facing trouble while reverting back the migration, and somehow have messed it, you can perform fake migrations.

./ migrate <name> --ignore-ghost-migrations --merge --fake

For django version < 1.7 this will create entry in south_migrationhistory table, you need to delete that entry.

Now you'll be able to revert back the migration easily.

PS: I was stuck for a lot of time and performing fake migration and then reverting back helped me out.

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 ;.

The Role Manager feature has not been enabled

You can do this by reading from the boolean property at:


This is a direct read from the enabled attribute of the roleManager element in the web.config:

    <roleManager enabled="true" />

For more information, check out this MSDN sample:

sscanf in Python

If the separators are ':', you can split on ':', and then use x.strip() on the strings to get rid of any leading or trailing whitespace. int() will ignore the spaces.

How to get 30 days prior to current date?

Try using the excellent Datejs JavaScript date library (the original is no longer maintained so you may be interested in this actively maintained fork instead):; // or...{days:-30});


See also the excellent Moment.js JavaScript date library:

moment().subtract(30, 'days'); // or...
moment().add(-30, 'days');

On npm install: Unhandled rejection Error: EACCES: permission denied

Restore ownership of the user's npm related folders, to the current user, like this:

sudo chown -R $USER:$GROUP ~/.npm
sudo chown -R $USER:$GROUP ~/.config

WorksheetFunction.CountA - not working post upgrade to Office 2010

It may be obvious but, by stating the Range and not including which workbook or worksheet then it may be trying to CountA() on a different sheet entirely. I find to fully address these things saves a lot of headaches.

Python and pip, list all versions of a package that's available?

This works for me on OSX:

pip install docker-compose== 2>&1 \
| grep -oE '(\(.*\))' \
| awk -F:\  '{print$NF}' \
| sed -E 's/( |\))//g' \
| tr ',' '\n'

It returns the list one per line:


Or to get the latest version available:

pip install docker-compose== 2>&1 \
| grep -oE '(\(.*\))' \
| awk -F:\  '{print$NF}' \
| sed -E 's/( |\))//g' \
| tr ',' '\n' \
| gsort -r -V \
| head -1

Keep in mind gsort has to be installed (on OSX) to parse the versions. You can install it with brew install coreutils

Difference between a virtual function and a pure virtual function

A virtual function makes its class a polymorphic base class. Derived classes can override virtual functions. Virtual functions called through base class pointers/references will be resolved at run-time. That is, the dynamic type of the object is used instead of its static type:

 Derived d;
 Base& rb = d;
 // if Base::f() is virtual and Derived overrides it, Derived::f() will be called

A pure virtual function is a virtual function whose declaration ends in =0:

class Base {
  // ...
  virtual void f() = 0;
  // ...

A pure virtual function implicitly makes the class it is defined for abstract (unlike in Java where you have a keyword to explicitly declare the class abstract). Abstract classes cannot be instantiated. Derived classes need to override/implement all inherited pure virtual functions. If they do not, they too will become abstract.

An interesting 'feature' of C++ is that a class can define a pure virtual function that has an implementation. (What that's good for is debatable.)

Note that C++11 brought a new use for the delete and default keywords which looks similar to the syntax of pure virtual functions:

my_class(my_class const &) = delete;
my_class& operator=(const my_class&) = default;

See this question and this one for more info on this use of delete and default.

How do you use window.postMessage across domains?

You should post a message from frame to parent, after loaded.

frame script:

$(document).ready(function() {
    window.parent.postMessage("I'm loaded", "*");

And listen it in parent:

function listenMessage(msg) {

if (window.addEventListener) {
    window.addEventListener("message", listenMessage, false);
} else {
    window.attachEvent("onmessage", listenMessage);

Use this link for more info:

Warning: Null value is eliminated by an aggregate or other SET operation in Aqua Data Studio

I was getting this error; I just put a WHERE clause for the field which was used within count clause. it solved the issue. Note: if null value exist, check whether its critical for the report, as its excluded in the count.

Old query:

select city, Count(Emp_ID) as Emp_Count 
from Emp_DB
group by city

New query:

select city, Count(Emp_ID) as Emp_Count 
from Emp_DB
where Emp_ID is not null
group by city

An internal error occurred during: "Updating Maven Project". Unsupported IClasspathEntry kind=4

This issue ( is fixed in m2e 1.5.0 which is available for Eclipse Kepler and Luna from this p2 repo :

If you also use m2e-wtp, you'll need to install m2e-wtp 1.1.0 as well :

Service has zero application (non-infrastructure) endpoints

As another clue, that indeed fixed this issue in my case.

I'm migrating some WCF services from a console application (that configures in code few WCF services) to an Azure WebRole to publish them in Azure. Every time I add a new service VS edits my web.config and adds this line:

<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true">

Well, with all the advices and answers above I couldn't make it work until I removed all the attributes in the serviceHostingEnvironment element. As you can see I'm not a WCF rockstar but I made it to work with the first Service just by configuring it as:

<service name="FirstService" behaviorConfiguration="metadataBehavior">
                <endpoint address=""
                 contract="IFirstService" />


but when I added the second Service it stoped working and I realized that those attributes where there again.

I hope it saves you time.

Can an interface extend multiple interfaces in Java?

A Java class can only extend one parent class. Multiple inheritance is not allowed. Interfaces are not classes, however, and an interface can extend more than one parent interface.

for example, take a look here:

HTTP could not register URL http://+:8000/HelloWCF/. Your process does not have access rights to this namespace

Right Click on Visual Studio > Run as Administrator > Open your project and run the service. This is a privilege related issue.

htmlentities() vs. htmlspecialchars()

You probably want to use some Unicode character encoding, for example UTF-8, and htmlspecialchars. Because there isn't any need to generate "HTML entities" for "all [the] applicable characters" (that is what htmlentities does according to the documentation) if it's already in your character set.

Get domain name

I know this is old. I just wanted to dump this here for anyone that was looking for an answer to getting a domain name. This is in coordination with Peter's answer. There "is" a bug as stated by Rich. But, you can always make a simple workaround for that. The way I can tell if they are still on the domain or not is by pinging the domain name. If it responds, continue on with whatever it was that I needed the domain for. If it fails, I drop out and go into "offline" mode. Simple string method.

 string GetDomainName()
        string _domain = IPGlobalProperties.GetIPGlobalProperties().DomainName;

        Ping ping = new Ping();

            PingReply reply = ping.Send(_domain);

            if (reply.Status == IPStatus.Success)
                return _domain;
                return reply.Status.ToString();
        catch (PingException pExp)
            if (pExp.InnerException.ToString() == "No such host is known")
                return "Network not detected!";

            return "Ping Exception";

Check if a row exists, otherwise insert

Pass updlock, rowlock, holdlock hints when testing for existence of the row.

begin tran /* default read committed isolation level is fine */

if not exists (select * from Table with (updlock, rowlock, holdlock) where ...)
    /* insert */
    /* update */

commit /* locks are released here */

The updlock hint forces the query to take an update lock on the row if it already exists, preventing other transactions from modifying it until you commit or roll back.

The holdlock hint forces the query to take a range lock, preventing other transactions from adding a row matching your filter criteria until you commit or roll back.

The rowlock hint forces lock granularity to row level instead of the default page level, so your transaction won't block other transactions trying to update unrelated rows in the same page (but be aware of the trade-off between reduced contention and the increase in locking overhead - you should avoid taking large numbers of row-level locks in a single transaction).

See for more information.

Note that locks are taken as the statements which take them are executed - invoking begin tran doesn't give you immunity against another transaction pinching locks on something before you get to it. You should try and factor your SQL to hold locks for the shortest possible time by committing the transaction as soon as possible (acquire late, release early).

Note that row-level locks may be less effective if your PK is a bigint, as the internal hashing on SQL Server is degenerate for 64-bit values (different key values may hash to the same lock id).

How to call window.alert("message"); from C#?

You should try this.

ClientScript.RegisterStartupScript(this.GetType(), "myalert", "alert('Sakla Test');", true);

Check whether a path is valid

private bool IsValidPath(string path)
    Regex driveCheck = new Regex(@"^[a-zA-Z]:\\$");

    if (string.IsNullOrWhiteSpace(path) || path.Length < 3)
        return false;

    if (!driveCheck.IsMatch(path.Substring(0, 3)))
        return false;

    var x1 = (path.Substring(3, path.Length - 3));
    string strTheseAreInvalidFileNameChars = new string(Path.GetInvalidPathChars());
    strTheseAreInvalidFileNameChars += @":?*";
    Regex containsABadCharacter = new Regex("[" + Regex.Escape(strTheseAreInvalidFileNameChars) + "]");

    if (containsABadCharacter.IsMatch(path.Substring(3, path.Length - 3)))
        return false;

    var driveLetterWithColonAndSlash = Path.GetPathRoot(path);

    if (!DriveInfo.GetDrives().Any(x => x.Name == driveLetterWithColonAndSlash))
        return false;

    return true;

How to display the value of the bar on each bar with pyplot.barh()?

Use plt.text() to put text in the plot.


import matplotlib.pyplot as plt
N = 5
menMeans = (20, 35, 30, 35, 27)
ind = np.arange(N)

#Creating a figure with some fig size
fig, ax = plt.subplots(figsize = (10,5)),menMeans,width=0.4)
#Now the trick is here.
#plt.text() , you need to give (x,y) location , where you want to put the numbers,
#So here index will give you x pos and data+1 will provide a little gap in y axis.
for index,data in enumerate(menMeans):
    plt.text(x=index , y =data+1 , s=f"{data}" , fontdict=dict(fontsize=20))

This will show the figure as:

bar chart with values at the top

What does 'index 0 is out of bounds for axis 0 with size 0' mean?

In numpy, index and dimension numbering starts with 0. So axis 0 means the 1st dimension. Also in numpy a dimension can have length (size) 0. The simplest case is:

In [435]: x = np.zeros((0,), int)
In [436]: x
Out[436]: array([], dtype=int32)
In [437]: x[0]
IndexError: index 0 is out of bounds for axis 0 with size 0

I also get it if x = np.zeros((0,5), int), a 2d array with 0 rows, and 5 columns.

So someplace in your code you are creating an array with a size 0 first axis.

When asking about errors, it is expected that you tell us where the error occurs.

Also when debugging problems like this, the first thing you should do is print the shape (and maybe the dtype) of the suspected variables.

Applied to pandas

Resolving the error:

  1. Use a try-except block
  2. Verify the size of the array is not 0
    • if x.size != 0:

Adding gif image in an ImageView in android

This is what worked for me:

In your build.gradle (project) write mavenCentral() in the buildscript{} and allprojects {}. It should look like this:

buildscript {
    repositories {
//more code ...
allprojects {
    repositories {

Then, in build.gradle(module) add in dependencies{} this snippet:

compile 'pl.droidsonroids.gif:android-gif-drawable:1.2.4'

it should look like this:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('', {
        exclude group: '', module: 'support-annotations'
    compile ''
    testCompile 'junit:junit:4.12'
    **compile 'pl.droidsonroids.gif:android-gif-drawable:1.2.4'**

Put your .gif image in your drawable folder. Now go to app > res > layout > activity_main.xml and add this snipped for your .gif:

    android:background="#000000" //for black background

And you're done :)

Helpful links:

Hope this helps.

Get a particular cell value from HTML table using JavaScript

var table = document.getElementById("someTableID"); 
var totalRows = document.getElementById("someTableID").rows.length;
var totalCol = 3; // enter the number of columns in the table minus 1 (first column is 0 not 1)
//To display all values
for (var x = 0; x <= totalRows; x++)
  for (var y = 0; y <= totalCol; y++)
//To display a single cell value enter in the row number and column number under rows and cells below:
var firstCell = table.rows[0].cells[0].innerHTML;
//Note:  if you use <th> this will be row 0, so your data will start at row 1 col 0

How can I select all children of an element except the last child?

You can use the negation pseudo-class :not() against the :last-child pseudo-class. Being introduced CSS Selectors Level 3, it doesn't work in IE8 or below:

:not(:last-child) { /* styles */ }

How do I add a bullet symbol in TextView?

Another best way to add bullet in any text view is stated below two steps:

First, create a drawable

<?xml version="1.0" encoding="utf-8"?>

    <!--set color of the bullet-->
       android:color="#666666"/> //set color of bullet

    <!--set size of the bullet-->

Then add this drawable in textview and set its pedding by using below properties


How can I throw a general exception in Java?

The simplest way to do it would be something like:

throw new java.lang.Exception();

However, the following lines would be unreachable in your code. So, we have two ways:

  1. Throw a generic exception at the bottom of the method.
  2. Throw a custom exception in case you don't want to do 1.

In .NET, which loop runs faster, 'for' or 'foreach'?

Any time there's arguments over performance, you just need to write a small test so that you can use quantitative results to support your case.

Use the StopWatch class and repeat something a few million times, for accuracy. (This might be hard without a for loop):

using System.Diagnostics;
Stopwatch sw = new Stopwatch()
for(int i = 0; i < 1000000;i ++)
    //do whatever it is you need to time
//print out sw.ElapsedMilliseconds

Fingers crossed the results of this show that the difference is negligible, and you might as well just do whatever results in the most maintainable code

Swift Beta performance: sorting arrays

TL;DR: Yes, the only Swift language implementation is slow, right now. If you need fast, numeric (and other types of code, presumably) code, just go with another one. In the future, you should re-evaluate your choice. It might be good enough for most application code that is written at a higher level, though.

From what I'm seeing in SIL and LLVM IR, it seems like they need a bunch of optimizations for removing retains and releases, which might be implemented in Clang (for Objective-C), but they haven't ported them yet. That's the theory I'm going with (for now… I still need to confirm that Clang does something about it), since a profiler run on the last test-case of this question yields this “pretty” result:

Time profiling on -O3 Time profiling on -Ofast

As was said by many others, -Ofast is totally unsafe and changes language semantics. For me, it's at the “If you're going to use that, just use another language” stage. I'll re-evaluate that choice later, if it changes.

-O3 gets us a bunch of swift_retain and swift_release calls that, honestly, don't look like they should be there for this example. The optimizer should have elided (most of) them AFAICT, since it knows most of the information about the array, and knows that it has (at least) a strong reference to it.

It shouldn't emit more retains when it's not even calling functions which might release the objects. I don't think an array constructor can return an array which is smaller than what was asked for, which means that a lot of checks that were emitted are useless. It also knows that the integer will never be above 10k, so the overflow checks can be optimized (not because of -Ofast weirdness, but because of the semantics of the language (nothing else is changing that var nor can access it, and adding up to 10k is safe for the type Int).

The compiler might not be able to unbox the array or the array elements, though, since they're getting passed to sort(), which is an external function and has to get the arguments it's expecting. This will make us have to use the Int values indirectly, which would make it go a bit slower. This could change if the sort() generic function (not in the multi-method way) was available to the compiler and got inlined.

This is a very new (publicly) language, and it is going through what I assume are lots of changes, since there are people (heavily) involved with the Swift language asking for feedback and they all say the language isn't finished and will change.

Code used:

import Cocoa

let swift_start = NSDate.timeIntervalSinceReferenceDate();
let n: Int = 10000
let x = Int[](count: n, repeatedValue: 1)
for i in 0..n {
    for j in 0..n {
        let tmp: Int = x[j]
        x[i] = tmp
let y: Int[] = sort(x)
let swift_stop = NSDate.timeIntervalSinceReferenceDate();

println("\(swift_stop - swift_start)s")

P.S: I'm not an expert on Objective-C nor all the facilities from Cocoa, Objective-C, or the Swift runtimes. I might also be assuming some things that I didn't write.

New self vs. new static

If the method of this code is not static, you can get a work-around in 5.2 by using get_class($this).

class A {
    public function create1() {
        $class = get_class($this);
        return new $class();
    public function create2() {
        return new static();

class B extends A {


$b = new B();
var_dump(get_class($b->create1()), get_class($b->create2()));

The results:

string(1) "B"
string(1) "B"

React.js: onChange event for contentEditable

Edit 2015

Someone has made a project on NPM with my solution:

Edit 06/2016: I've just encoutered a new problem that occurs when the browser tries to "reformat" the html you just gave him, leading to component always re-rendering. See

Edit 07/2016: here's my production contentEditable implementation. It has some additional options over react-contenteditable that you might want, including:

  • locking
  • imperative API allowing to embed html fragments
  • ability to reformat the content


FakeRainBrigand's solution has worked quite fine for me for some time until I got new problems. ContentEditables are a pain, and are not really easy to deal with React...

This JSFiddle demonstrates the problem.

As you can see, when you type some characters and click on Clear, the content is not cleared. This is because we try to reset the contenteditable to the last known virtual dom value.

So it seems that:

  • You need shouldComponentUpdate to prevent caret position jumps
  • You can't rely on React's VDOM diffing algorithm if you use shouldComponentUpdate this way.

So you need an extra line so that whenever shouldComponentUpdate returns yes, you are sure the DOM content is actually updated.

So the version here adds a componentDidUpdate and becomes:

var ContentEditable = React.createClass({
    render: function(){
        return <div id="contenteditable"
            dangerouslySetInnerHTML={{__html: this.props.html}}></div>;

    shouldComponentUpdate: function(nextProps){
        return nextProps.html !== this.getDOMNode().innerHTML;

    componentDidUpdate: function() {
        if ( this.props.html !== this.getDOMNode().innerHTML ) {
           this.getDOMNode().innerHTML = this.props.html;

    emitChange: function(){
        var html = this.getDOMNode().innerHTML;
        if (this.props.onChange && html !== this.lastHtml) {
                target: {
                    value: html
        this.lastHtml = html;

The Virtual dom stays outdated, and it may not be the most efficient code, but at least it does work :) My bug is resolved


1) If you put shouldComponentUpdate to avoid caret jumps, then the contenteditable never rerenders (at least on keystrokes)

2) If the component never rerenders on key stroke, then React keeps an outdated virtual dom for this contenteditable.

3) If React keeps an outdated version of the contenteditable in its virtual dom tree, then if you try to reset the contenteditable to the value outdated in the virtual dom, then during the virtual dom diff, React will compute that there are no changes to apply to the DOM!

This happens mostly when:

  • you have an empty contenteditable initially (shouldComponentUpdate=true,prop="",previous vdom=N/A),
  • the user types some text and you prevent renderings (shouldComponentUpdate=false,prop=text,previous vdom="")
  • after user clicks a validation button, you want to empty that field (shouldComponentUpdate=false,prop="",previous vdom="")
  • as both the newly produced and old vdom are "", React does not touch the dom.

Why use Select Top 100 Percent?

I have seen other code which I have inherited which uses SELECT TOP 100 PERCENT

The reason for this is simple: Enterprise Manager used to try to be helpful and format your code to include this for you. There was no point ever trying to remove it as it didn't really hurt anything and the next time you went to change it EM would insert it again.

Add days Oracle SQL

It's Simple.You can use

select (sysdate+2) as new_date from dual;

This will add two days from current date.

TCP vs UDP on video stream

Usually a video stream is somewhat fault tolerant. So if some packages get lost (due to some router along the way being overloaded, for example), then it will still be able to display the content, but with reduced quality.

If your live stream was using TCP/IP, then it would be forced to wait for those dropped packages before it could continue processing newer data.

That's doubly bad:

  • old data be re-transmitted (that's probably for a frame that was already displayed and therefore worthless) and
  • new data can't arrive until after old data was re-transmitted

If your goal is to display as up-to-date information as possible (and for a live-stream you usually want to be up-to-date, even if your frames look a bit worse), then TCP will work against you.

For a recorded stream the situation is slightly different: you'll probably be buffering a lot more (possibly several minutes!) and would rather have data re-transmitted than have some artifacts due to lost packages. In this case TCP is a good match (this could still be implemented in UDP, of course, but TCP doesn't have as much drawbacks as for the live stream case).

How to scale images to screen size in Pygame

If you scale 1600x900 to 1280x720 you have

scale_x = 1280.0/1600
scale_y = 720.0/900

Then you can use it to find button size, and button position

button_width  = 300 * scale_x
button_height = 300 * scale_y

button_x = 1440 * scale_x
button_y = 860  * scale_y

If you scale 1280x720 to 1600x900 you have

scale_x = 1600.0/1280
scale_y = 900.0/720

and rest is the same.

I add .0 to value to make float - otherwise scale_x, scale_y will be rounded to integer - in this example to 0 (zero) (Python 2.x)

how to parse json using groovy

That response is a Map, with a single element with key '212315952136472'. There's no 'data' key in the Map. If you want to loop through all entries, use something like this:

JSONObject userJson = JSON.parse(jsonResponse)
userJson.each { id, data -> println }

If you know it's a single-element Map then you can directly access the link:

def data = userJson.values().iterator().next()
String link =

And if you knew the id (e.g. if you used it to make the request) then you can access the value more concisely:

String id = '212315952136472'
String link = userJson[id].link

How do I import a Swift file from another Swift file?

Check your PrimeNumberModelTests Target Settings.

If you can't see PrimeNumberModel.swift file in Build Phases/Compile Sources, add it.

error CS0103: The name ' ' does not exist in the current context

Simply move the declaration outside of the if block.

string currentstore=HttpContext.Current.Request.ServerVariables["HTTP_HOST"];
string imgsrc="";
if (currentstore == "")
    <link href="/path/to/my/stylesheets/styles1-print.css" rel="stylesheet" type="text/css" />
    <link href="/path/to/my/stylesheets/styles2-print.css" rel="stylesheet" type="text/css" />

<a href="@Url.RouteUrl("HomePage")" class="logo"><img  alt="" src="@imgsrc"></a>

You could make it a bit cleaner.

string currentstore=HttpContext.Current.Request.ServerVariables["HTTP_HOST"];
string imgsrc="/content/images/uploaded/store2_logo.gif";
if (currentstore == "")
    <link href="/path/to/my/stylesheets/styles1-print.css" rel="stylesheet" type="text/css" />
    <link href="/path/to/my/stylesheets/styles2-print.css" rel="stylesheet" type="text/css" />

Find an element in a list of tuples

There is actually a clever way to do this that is useful for any list of tuples where the size of each tuple is 2: you can convert your list into a single dictionary.

For example,

test = [("hi", 1), ("there", 2)]
test = dict(test)
print test["hi"] # prints 1

SQLite Query in Android to count rows

See rawQuery(String, String[]) and the documentation for Cursor

Your DADABASE_COMPARE SQL statement is currently invalid, loginname and loginpass won't be escaped, there is no space between loginname and the and, and you end the statement with ); instead of ; -- If you were logging in as bob with the password of password, that statement would end up as

select count(*) from users where uname=boband pwd=password);

Also, you should probably use the selectionArgs feature, instead of concatenating loginname and loginpass.

To use selectionArgs you would do something like

final String SQL_STATEMENT = "SELECT COUNT(*) FROM users WHERE uname=? AND pwd=?";

private void someMethod() {
    Cursor c = db.rawQuery(SQL_STATEMENT, new String[] { loginname, loginpass });

Python concatenate text files

  import os
  name=input('Enter the inclusive file name: ')
  exten=input('Enter the type(extension): ')
  for i in files:
    for x in f_j:

Add attribute 'checked' on click jquery

A simple answer is to add checked attributes within a checkbox:

$('input[id='+$(this).attr("id")+']').attr("checked", "checked");

Uncaught ReferenceError: $ is not defined error in jQuery

The MVC 5 stock install puts javascript references in the _Layout.cshtml file that is shared in all pages. So the javascript files were below the main content and document.ready function where all my $'s were.

BOTTOM PART OF _Layout.cshtml:

    <div class="container body-content">
        <hr />
            <p>&copy; @DateTime.Now.Year - My ASP.NET Application</p>

    @RenderSection("scripts", required: false)


I moved them above the @RenderBody() and all was fine.

    @RenderSection("scripts", required: false)

    <div class="container body-content">
        <hr />
            <p>&copy; @DateTime.Now.Year - My ASP.NET Application</p>


Get Row Index on Rowcommand event

this is answer for your question.

GridViewRow gvr = (GridViewRow)((ImageButton)e.CommandSource).NamingContainer;

int RowIndex = gvr.RowIndex; 

Python 3.2 Unable to import urllib2 (ImportError: No module named urllib2)


import urllib.request

wp = urllib.request.urlopen("")

pw =



import urllib

 import sys

 wp = urllib.urlopen("")

 for line in wp:


While I have tested both the Codes in respective versions.

How to insert text in a td with id, using JavaScript

There are several options... assuming you found your TD by var td = document.getElementyById('myTD_ID'); you can do:

  • td.innerHTML = "mytext";

  • td.textContent= "mytext";

  • td.innerText= "mytext"; - this one may not work outside IE? Not sure

  • Use firstChild or children array as previous poster noted.

If it's just the text that needs to be changed, textContent is faster and less prone to XSS attacks (

Git: Remove committed file after push

  1. Get the hash code of last commit.

    • git log
  2. Revert the commit
    • git revert <hash_code_from_git_log>
  3. Push the changes
    • git push

check out in the GHR. you might get what ever you need, hope you this is useful

C# error: Use of unassigned local variable

The compiler doesn't know that the Environment.Exit() is going to terminate the program; it just sees you executing a static method on a class. Just initialize queue to null when you declare it.

Queue queue = null;

MySQL show current connection info

There are MYSQL functions you can use. Like this one that resolves the user:


This will return something like root@localhost so you get the host and the user.

To get the current database run this statement:


Other useful functions can be found here:

Display tooltip on Label's hover?

Tooltips in bootstrap are good, but there is also a very good tooltip function in jQuery UI, which you can read about here.


<label for="male" id="foo" title="Hello This Will Have Some Value">Hello...</label>

Then, assuming you have already referenced jQuery and jQueryUI libraries in your head, add a script element like this:

<script type="text/javascript">

This will display the contents of the title attribute as a tooltip when you rollover any element with a title attribute.

How to avoid Number Format Exception in java?

Try to convert Prize into decimal format...

import java.math.BigDecimal;
import java.math.RoundingMode;

public class Bigdecimal {
    public static boolean isEmpty (String st) {
        return st == null || st.length() < 1; 
    public static BigDecimal bigDecimalFormat(String Preis){        
        //MathContext   mi = new MathContext(2);
        BigDecimal bd = new BigDecimal(0.00);

                         bd = new BigDecimal(Preis);

            return bd.setScale(2, RoundingMode.HALF_UP);

    public static void main(String[] args) {
        String cost = "12.12";
        if (!isEmpty(cost) ){
            try {
               BigDecimal intCost = bigDecimalFormat(cost);
               List<Book> books = bookService.findBooksCheaperThan(intCost);  
            } catch (NumberFormatException e) {
               System.out.println("This is not a number");


Change color of Back button in navigation bar


 override func viewDidLoad() {

 self.navigationController?.navigationBar.tintColor = UIColor.white

Reading a binary file with python

In general, I would recommend that you look into using Python's struct module for this. It's standard with Python, and it should be easy to translate your question's specification into a formatting string suitable for struct.unpack().

Do note that if there's "invisible" padding between/around the fields, you will need to figure that out and include it in the unpack() call, or you will read the wrong bits.

Reading the contents of the file in order to have something to unpack is pretty trivial:

import struct

data = open("from_fortran.bin", "rb").read()

(eight, N) = struct.unpack("@II", data)

This unpacks the first two fields, assuming they start at the very beginning of the file (no padding or extraneous data), and also assuming native byte-order (the @ symbol). The Is in the formatting string mean "unsigned integer, 32 bits".

Remove an element from a Bash array

If anyone finds themselves in a position where they need to remember set -e or set -x values and be able to restore them, please check out this gist which uses the first array deletion solution to manage it's own stack:

YouTube iframe embed - full screen

React.JS People, remember allowFullScreen and frameBorder="0"

Without camel-case, react strips these tags out!

Calling a JavaScript function returned from an Ajax response

Just remember if you create a function the way below through ajax...

function foo()

...and execute it via eval, you'll probably get a context problem. Take this as your callback function:

function callback(result)
    responseDiv = document.getElementById('responseDiv');
    responseDiv.innerHTML = result;
    scripts = responseDiv.getElementsByTagName('script');

You'll be declaring a function inside a function, so this new function will be accessible only on that scope.

If you want to create a global function in this scenario, you could declare it this way: = function ()

But, I also think you shouldn't be doing this...

Sorry for any mistake here...

String replace a Backslash


   sSource = sSource.replaceAll("\\\\", "");

Edit : Ok even in stackoverflow there is backslash escape... You need to have four backslashes in your replaceAll first String argument...

The reason of this is because backslash is considered as an escape character for special characters (like \n for instance).
Moreover replaceAll first arg is a regular expression that also use backslash as escape sequence.
So for the regular expression you need to pass 2 backslash. To pass those two backslashes by a java String to the replaceAll, you also need to escape both backslashes.
That drives you to have four backslashes for your expression! That's the beauty of regex in java ;)

Difference between single and double quotes in Bash

Others explained very well and just want to give with simple examples.

Single quotes can be used around text to prevent the shell from interpreting any special characters. Dollar signs, spaces, ampersands, asterisks and other special characters are all ignored when enclosed within single quotes.

$ echo 'All sorts of things are ignored in single quotes, like $ & * ; |.' 

It will give this:

All sorts of things are ignored in single quotes, like $ & * ; |.

The only thing that cannot be put within single quotes is a single quote.

Double quotes act similarly to single quotes, except double quotes still allow the shell to interpret dollar signs, back quotes and backslashes. It is already known that backslashes prevent a single special character from being interpreted. This can be useful within double quotes if a dollar sign needs to be used as text instead of for a variable. It also allows double quotes to be escaped so they are not interpreted as the end of a quoted string.

$ echo "Here's how we can use single ' and double \" quotes within double quotes"

It will give this:

Here's how we can use single ' and double " quotes within double quotes

It may also be noticed that the apostrophe, which would otherwise be interpreted as the beginning of a quoted string, is ignored within double quotes. Variables, however, are interpreted and substituted with their values within double quotes.

$ echo "The current Oracle SID is $ORACLE_SID"

It will give this:

The current Oracle SID is test

Back quotes are wholly unlike single or double quotes. Instead of being used to prevent the interpretation of special characters, back quotes actually force the execution of the commands they enclose. After the enclosed commands are executed, their output is substituted in place of the back quotes in the original line. This will be clearer with an example.

$ today=`date '+%A, %B %d, %Y'`
$ echo $today 

It will give this:

Monday, September 28, 2015 

CSS3 Transform Skew One Side

You try with the :before was pretty close, the only thing you had to change was actually using skew instead of the borders:

Edit: Your border approach would work too, the only thing you did wrong was having the before element on top of your div, so the transparent border wasnt showing. If you would have position the pseudo element to the left of your div, everything would have worked too:

How do I connect to a specific Wi-Fi network in Android programmatically?

In API level 29, WifiManager.enableNetwork() method is deprecated. As per Android API documentation(check here):

  1. See WifiNetworkSpecifier.Builder#build() for new mechanism to trigger connection to a Wi-Fi network.
  2. See addNetworkSuggestions(java.util.List), removeNetworkSuggestions(java.util.List) for new API to add Wi-Fi networks for consideration when auto-connecting to wifi. Compatibility Note: For applications targeting Build.VERSION_CODES.Q or above, this API will always return false.

From API level 29, to connect to WiFi network, you will need to use WifiNetworkSpecifier. You can find example code at

How to open a WPF Popup when another control is clicked, using XAML markup only?

I had some issues with the MouseDown part of this, but here is some code that might get your started.

<Window x:Class="WpfApplication1.Window1"
    Title="Window1" Height="300" Width="300">
        <Control VerticalAlignment="Top">
                    <TextBox x:Name="MyText"></TextBox>
                    <Popup x:Name="Popup" PopupAnimation="Fade" VerticalAlignment="Top">
                        <Border Background="Red">
                            <TextBlock>Test Popup Content</TextBlock>
                        <EventTrigger RoutedEvent="UIElement.MouseEnter" SourceName="MyText">
                                    <BooleanAnimationUsingKeyFrames Storyboard.TargetName="Popup" Storyboard.TargetProperty="(Popup.IsOpen)">
                                        <DiscreteBooleanKeyFrame KeyTime="00:00:00" Value="True"/>
                        <EventTrigger RoutedEvent="UIElement.MouseLeave" SourceName="MyText">
                                    <BooleanAnimationUsingKeyFrames Storyboard.TargetName="Popup" Storyboard.TargetProperty="(Popup.IsOpen)">
                                        <DiscreteBooleanKeyFrame KeyTime="00:00:00" Value="False"/>

Phone validation regex


You may try this....

How about this one....Hope this helps...


UnicodeEncodeError: 'charmap' codec can't encode - character maps to <undefined>, print function

For debugging purposes, you could use print(repr(data)).

To display text, always print Unicode. Don't hardcode the character encoding of your environment such as Cp850 inside your script. To decode the HTTP response, see A good way to get the charset/encoding of an HTTP response in Python.

To print Unicode to Windows console, you could use win-unicode-console package.

git clone: Authentication failed for <URL>

The culprit was russian account password.

Accidentally set up it (wrong keyboard layout). Everything was working, so didnt bother changing it.

Out of despair changed it now and it worked.

If someone looked up this thread and its not a solution for you - check out comments under the question and steps i described in question, they might be useful to you.


From the manual: The SELECT ... INTO OUTFILE statement is intended primarily to let you very quickly dump a table to a text file on the server machine. If you want to create the resulting file on some client host other than the server host, you cannot use SELECT ... INTO OUTFILE. In that case, you should instead use a command such as mysql -e "SELECT ..." > file_name to generate the file on the client host."

An example:

mysql -h -u usrname--password=pass db_name -e 'SELECT foo FROM bar' > /tmp/myfile.txt

How do you get/set media volume (not ringtone volume) in Android?

You can set your activity to use a specific volume. In your activity, use one of the following:


Eclipse plugin for generating a class diagram

Try Amateras. It is a very good plugin for generating UML diagrams including class diagram.

Checking if a key exists in a JavaScript object?

const object1 = {
  a: 'something',
  b: 'something',
  c: 'something'

const key = 's';

// Object.keys(object1) will return array of the object keys ['a', 'b', 'c']

Object.keys(object1).indexOf(key) === -1 ? 'the key is not there' : 'yep the key is exist';

Amazon Interview Question: Design an OO parking lot

In an Object Oriented parking lot, there will be no need for attendants because the cars will "know how to park".

Finding a usable car on the lot will be difficult; the most common models will either have all their moving parts exposed as public member variables, or they will be "fully encapsulated" cars with no windows or doors.

The parking spaces in our OO parking lot will not match the size and shape of the cars (an "impediance mismatch" between the spaces and the cars)

License tags on our lot will have a dot between each letter and digit. Handicaped parking will only be available for licenses beginning with "_", and licenses beginning with "m_" will be towed.

Programmatically set left drawable in a TextView

there are two ways of doing it either you can use XML or Java for it. If it's static and requires no changes then you can initialize in XML.


Now if you need to change the icons dynamically then you can do it by calling the icons based on the events

       textViewContext.setText("File Uploaded");
textViewContext.setCompoundDrawablesWithIntrinsicBounds(R.drawable.uploaded, 0, 0, 0);

How to read Data from Excel sheet in selenium webdriver

Don't know about what the error you are facing exactly. But log4j:WARN No appenders could be found for logger error, is due to the log4j jar file that you have included in your project.

Initializing log4j is needed but actually Log4j is not necessary for your project. So Right click on your Project → Properties → Java Build Path → Libraries.. Search for log4j jar file and remove it.

Hope it will work fine now.

Image resizing in React Native

In my case I could not set 'width' and 'height' to null because I'm using TypeScript.

The way I fixed it was by setting them to '100%':

backgroundImage: {
    flex: 1,
    width: '100%',
    height: '100%',
    resizeMode: 'cover',        

Can Mysql Split a column?

As an addendum to this, I've strings of the form: Some words 303

where I'd like to split off the numerical part from the tail of the string. This seems to point to a possible solution:

The problem however, is that you only get the answer "yes, it matches", and not the start index of the regexp match.

Create a List of primitive int?

This is not possible. The java specification forbids the use of primitives in generics. However, you can create ArrayList<Integer> and call add(i) if i is an int thanks to boxing.

How to access SOAP services from iPhone

One word: Don't.

OK obviously that isn't a real answer. But still SOAP should be avoided at all costs. ;-) Is it possible to add a proxy server between the iPhone and the web service? Perhaps something that converts REST into SOAP for you?

You could try CSOAP, a SOAP library that depends on libxml2 (which is included in the iPhone SDK).

I've written my own SOAP framework for OSX. However it is not actively maintained and will require some time to port to the iPhone (you'll need to replace NSXML with TouchXML for a start)

Disable building workspace process in Eclipse

Building workspace is about incremental build of any evolution detected in one of the opened projects in the currently used workspace.

You can also disable it through the menu "Project / Build automatically".

But I would recommend first to check:

  • if a Project Clean all / Build result in the same kind of long wait (after disabling this option)
  • if you have (this time with building automatically activated) some validation options you could disable to see if they have an influence on the global compilation time (Preferences / Validations, or Preferences / XML / ... if you have WTP installed)
  • if a fresh eclipse installation referencing the same workspace (see this eclipse.ini for more) results in the same issue (with building automatically activated)

Note that bug 329657 (open in 2011, in progress in 2014) is about interrupting a (too lengthy) build, instead of cancelling it:

There is an important difference between build interrupt and cancel.

  • When a build is cancelled, it typically handles this by discarding incremental build state and letting the next build be a full rebuild. This can be quite expensive in some projects.
    As a user I think I would rather wait for the 5 second incremental build to finish rather than cancel and result in a 30 second rebuild afterwards.

  • The idea with interrupt is that a builder could more efficiently handle interrupt by saving its intermediate state and resuming on the next invocation.
    In practice this is hard to implement so the most common boundary is when we check for interrupt before/after calling each builder in the chain.


How to sort a NSArray alphabetically?

A more powerful way of sorting a list of NSString to use things like NSNumericSearch :

NSArray *sortedArrayOfString = [arrayOfString sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
            return [(NSString *)obj1 compare:(NSString *)obj2 options:NSNumericSearch];

Combined with SortDescriptor, that would give something like :

NSSortDescriptor *sort = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES comparator:^NSComparisonResult(id obj1, id obj2) {
        return [(NSString *)obj1 compare:(NSString *)obj2 options:NSNumericSearch];
NSArray *sortedArray = [anArray sortedArrayUsingDescriptors:[NSArray arrayWithObject:sort]];

How do I write a compareTo method which compares objects?

This is the right way to compare strings:

int studentCompare = this.lastName.compareTo(s.getLastName()); 

This won't even compile:

if (this.getLastName() < s.getLastName())

Use if (this.getLastName().compareTo(s.getLastName()) < 0) instead.

So to compare fist/last name order you need:

int d = getFirstName().compareTo(s.getFirstName());
if (d == 0)
    d = getLastName().compareTo(s.getLastName());
return d;