Programs & Examples On #Cscope

Cscope is a code searching application originally written for searching C code bases. Cscope is useful for searching many other code bases as well: C++, Java, Python, etc.

Where does git config --global get written to?

The paths for msysgit are:

Windows XP -C:\Documents and Settings\<user_name>\.gitconfig

Windows Vista+ C:\Users\<user_name>\.gitconfig

Get all object attributes in Python?

What you probably want is dir().

The catch is that classes are able to override the special __dir__ method, which causes dir() to return whatever the class wants (though they are encouraged to return an accurate list, this is not enforced). Furthermore, some objects may implement dynamic attributes by overriding __getattr__, may be RPC proxy objects, or may be instances of C-extension classes. If your object is one these examples, they may not have a __dict__ or be able to provide a comprehensive list of attributes via __dir__: many of these objects may have so many dynamic attrs it doesn't won't actually know what it has until you try to access it.

In the short run, if dir() isn't sufficient, you could write a function which traverses __dict__ for an object, then __dict__ for all the classes in obj.__class__.__mro__; though this will only work for normal python objects. In the long run, you may have to use duck typing + assumptions - if it looks like a duck, cross your fingers, and hope it has .feathers.

Font Awesome not working, icons showing as squares

I had this issue. The problem was I had a font-family CSS style with !important overriding the fontawesome font.

Get first letter of a string from column

Cast the dtype of the col to str and you can perform vectorised slicing calling str:

In [29]:
df['new_col'] = df['First'].astype(str).str[0]

   First  Second new_col
0    123     234       1
1     22    4353       2
2     32     355       3
3    453     453       4
4     45     345       4
5    453     453       4
6     56      56       5

if you need to you can cast the dtype back again calling astype(int) on the column

Propagation Delay vs Transmission delay

Transmission Delay : Amount of time required to pump all bits/packets into the electric wire/optic fibre.

Propagation delay : It's the amount of time needed for a packet to reach the destination.

If propagation delay is very high than transmission delay the chance of losing the packet is high.

How to dismiss keyboard for UITextView with return key?

For Xcode 6.4., Swift 1.2. :

   override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent)
        super.touchesBegan(touches, withEvent: event)
        if let touch = touches.first as? UITouch

How to add fonts to create-react-app based projects?

You can use the Web API FontFace constructor (also Typescript) without need of CSS:

export async function loadFont(fontFamily: string, url: string): Promise<void> {
    const font = new FontFace(fontFamily, `local(${fontFamily}), url(${url})`);
    // wait for font to be loaded
    await font.load();
    // add font to document
    // enable font with CSS class
import ComicSans from "./assets/fonts/ComicSans.ttf";

loadFont("Comic Sans ", ComicSans).catch((e) => {

Declare a file font.ts with your modules (TS only):

declare module "*.ttf";
declare module "*.woff";
declare module "*.woff2";

If TS cannot find FontFace type as its still officially WIP, add this declaration to your project. It will work in your browser, except for IE.

Why use def main()?

"What does if __name__==“__main__”: do?" has already been answered.

Having a main() function allows you to call its functionality if you import the module. The main (no pun intended) benefit of this (IMHO) is that you can unit test it.

how to make password textbox value visible when hover an icon

I use this one line of code, it should do it:

<input type="password"

How to test abstract class in Java with JUnit?

My way of testing this is quite simple, within each I simply create a class in the that extend the abstract class. And test it that way.

Call a PHP function after onClick HTML event

<div id="sample"></div>   
            <legend>Add New Contact</legend>
            <input type="text" name="fullname" placeholder="First name and last name" required /> <br />
            <input type="email" name="email" placeholder="[email protected]" required /> <br />
            <input type="text" name="phone" placeholder="Personal phone number: mobile, home phone etc." required /> <br />
            <input type="submit" name="submit" id= "submitButton" class="button" value="Add Contact" onClick="" />
            <input type="button" name="cancel" class="button" value="Reset" />


            $("#sample").load(filenameofyourfunction?the the variable you need);


Active Directory LDAP Query by sAMAccountName and Domain

"Domain" is not a property of an LDAP object. It is more like the name of the database the object is stored in.

So you have to connect to the right database (in LDAP terms: "bind to the domain/directory server") in order to perform a search in that database.

Once you bound successfully, your query in it's current shape is all you need.

BTW: Choosing "ObjectCategory=Person" over "ObjectClass=user" was a good decision. In AD, the former is an "indexed property" with excellent performance, the latter is not indexed and a tad slower.

Remote debugging a Java application

I'd like to emphasize that order of arguments is important.

For me java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000 -jar app.jar command opens debugger port,

but java -jar app.jar -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000 command doesn't.

Want to show/hide div based on dropdown box selection

You need to either put your code at the end of the page or wrap it in a document ready call, otherwise you're trying to execute code on elements that don't yet exist. Also, you can reduce your code to:

$('#purpose').on('change', function () {
    $("#business").css('display', (this.value == '1') ? 'block' : 'none');

jsFiddle example

Code snippet or shortcut to create a constructor in Visual Studio

In case you want a constructor with properties, you need to do the following:

  1. Place your cursor in any empty line in a class;

  2. Press Ctrl + . to trigger the Quick Actions and Refactorings menu;

    Refactoring menu

  3. Select Generate constructor from the drop-down menu;

  4. Pick the members you want to include as constructor parameters. You can order them using the up and down arrows. Choose OK.

The constructor is created with the specified parameters.

Generate a constructor in Visual Studio

How to clean up R memory (without the need to restart my PC)?

I've found it helpful to go into my "tmp" folder and delete all hanging rsession files. This usually frees any memory that seems to be "stuck".

Any way to select without causing locking in MySQL?



Version 5.0 Docs are here.

Version 5.1 Docs are here.

MS Access VBA: Sending an email through Outlook

Add a reference to the Outlook object model in the Visual Basic editor. Then you can use the code below to send an email using outlook.

Sub sendOutlookEmail()
Dim oApp As Outlook.Application
Dim oMail As MailItem
Set oApp = CreateObject("Outlook.application")

Set oMail = oApp.CreateItem(olMailItem)
oMail.Body = "Body of the email"
oMail.Subject = "Test Subject"
oMail.To = "[email protected]"
Set oMail = Nothing
Set oApp = Nothing

End Sub

npm global path prefix

brew should not require you to use sudo even when running npm with -g. This might actually create more problems down the road.

Typically, brew or port let you update you path so it doesn't risk messing up your .zshrc, .bashrc, .cshrc, or whatever flavor of shell you use.

install cx_oracle for python

Try to reinstall it with the following code:

!pip install --proxy http://username:[email protected]:8080 --upgrade --force-reinstall cx_Oracle

how to write value into cell with vba code without auto type conversion?

Cells(1,1).Value2 = "'123,456"

note the single apostrophe before the number - this will signal to excel that whatever follows has to be interpreted as text.

Storing a Key Value Array into a compact JSON string

So why don't you simply use a key-value literal?

var params = {
    'slide0001.html': 'Looking Ahead',
    'slide0002.html': 'Forecase',

return params['slide0001.html']; // returns: Looking Ahead

Is multiplication and division using shift operators in C actually faster?

Python test performing same multiplication 100 million times against the same random numbers.

>>> from timeit import timeit
>>> setup_str = 'import scipy; from scipy import random; scipy.random.seed(0)'
>>> N = 10*1000*1000
>>> timeit('x=random.randint(65536);', setup=setup_str, number=N)
1.894096851348877 # Time from generating the random #s and no opperati

>>> timeit('x=random.randint(65536); x*2', setup=setup_str, number=N)
>>> timeit('x=random.randint(65536); x << 1', setup=setup_str, number=N)

>>> timeit('x=random.randint(65536); x*10', setup=setup_str, number=N)
>>> timeit('x=random.randint(65536); (x << 3) + (x<<1)', setup=setup_str, number=N)

>>> timeit('x=random.randint(65536); x // 2', setup=setup_str, number=N)
>>> timeit('x=random.randint(65536); x / 2', setup=setup_str, number=N)
>>> timeit('x=random.randint(65536); x >> 1', setup=setup_str, number=N)

So in doing a shift rather than multiplication/division by a power of two in python, there's a slight improvement (~10% for division; ~1% for multiplication). If its a non-power of two, there's likely a considerable slowdown.

Again these #s will change depending on your processor, your compiler (or interpreter -- did in python for simplicity).

As with everyone else, don't prematurely optimize. Write very readable code, profile if its not fast enough, and then try to optimize the slow parts. Remember, your compiler is much better at optimization than you are.

XAMPP, Apache - Error: Apache shutdown unexpectedly

For me, this problem began when I hosted a VPN-connection on my Windows 8 computer.

Simply deleting the connection from "Control Panel\Network and Internet\Network Connections" solved the problem.

A function to convert null to string

Its an old topic, but there is a "elegant" way to do that...

static string NullToString( object Value )
    return Value = Value ?? string.Empty;    

JSON response parsing in Javascript to get key/value pair

There are two ways to access properties of objects:

var obj = {a: 'foo', b: 'bar'};

obj.a //foo
obj['b'] //bar

Or, if you need to dynamically do it:

var key = 'b';
obj[key] //bar

If you don't already have it as an object, you'll need to convert it.

For a more complex example, let's assume you have an array of objects that represent users:

var users = [{name: 'Corbin', age: 20, favoriteFoods: ['ice cream', 'pizza']},
             {name: 'John', age: 25, favoriteFoods: ['ice cream', 'skittle']}];

To access the age property of the second user, you would use users[1].age. To access the second "favoriteFood" of the first user, you'd use users[0].favoriteFoods[2].

Another example: obj[2].key[3]["some key"]

That would access the 3rd element of an array named 2. Then, it would access 'key' in that array, go to the third element of that, and then access the property name some key.

As Amadan noted, it might be worth also discussing how to loop over different structures.

To loop over an array, you can use a simple for loop:

var arr = ['a', 'b', 'c'],
for (i = 0; i < arr.length; ++i) {

To loop over an object is a bit more complicated. In the case that you're absolutely positive that the object is a plain object, you can use a plain for (x in obj) { } loop, but it's a lot safer to add in a hasOwnProperty check. This is necessary in situations where you cannot verify that the object does not have inherited properties. (It also future proofs the code a bit.)

var user = {name: 'Corbin', age: 20, location: 'USA'},

for (key in user) {
    if (user.hasOwnProperty(key)) {
        console.log(key + " = " + user[key]);

(Note that I've assumed whatever JS implementation you're using has console.log. If not, you could use alert or some kind of DOM manipulation instead.)

jQuery Uncaught TypeError: Property '$' of object [object Window] is not a function

My favorite no-conflict-friendly construct:

jQuery(function($) {
  // ...

Calling jQuery with a function pointer is a shortcut for $(document).ready(...)

Or as we say in coffeescript:

jQuery ($) ->
  # code here

Rendering an in React

Dmitry Brin's answer worked for me, with one caveat. In my case, I needed to run a function between the list tags, which requires nested JSX braces. Example JSX below, which worked for me:

{ (object, i) { return <li>{JSON.stringify(object)}</li> })}

If you don't use nested JSX braces, for example:

{ (object, i) { return <li>JSON.stringify(object)</li>})}

then you get a list of "JSON.stringify(object)" in your HTML output, which probably isn't what you want.

How to measure the a time-span in seconds using System.currentTimeMillis()?

For conversion of milliseconds to seconds, since 1 second = 10³ milliseconds:

//here m will be in seconds
long m = System.currentTimeMillis()/1000;

//here m will be in minutes
long m = System.currentTimeMillis()/1000/60; //this will give in mins

How do I escape a single quote in SQL Server?

The following syntax will escape you ONLY ONE quotation mark:


The result will be a single quote. Might be very helpful for creating dynamic SQL :). enter image description here

How to make a new List in Java

More options to do the same thing with Java 8, not better, not worse, just different and if you want to do some extra work with the lists, Streams will provide you more alternatives (filter, map, reduce, etc.)

List<String> listA = Stream.of("a", "B", "C").collect(Collectors.toList());
List<Integer> listB = IntStream.range(10, 20).boxed().collect(Collectors.toList());
List<Double> listC = DoubleStream.generate(() -> { return new Random().nextDouble(); }).limit(10).boxed().collect(Collectors.toList());
LinkedList<Integer> listD = Stream.iterate(0, x -> x++).limit(10).collect(Collectors.toCollection(LinkedList::new));

Multiple Cursors in Sublime Text 2 Windows

Mac Users, let me save you the time:

  • Cmd+a: select the lines you want a cursor
  • Cmd+Shift+l: to create the cursor

CALL command vs. START with /WAIT option

For exe files, I suppose the differences are nearly unimportant.
But to start an exe you don't even need CALL.

When starting another batch it's a big difference,
as CALL will start it in the same window and the called batch has access to the same variable context.
So it can also change variables which affects the caller.

START will create a new cmd.exe for the called batch and without /b it will open a new window.
As it's a new context, variables can't be shared.


Using start /wait <prog>
- Changes of environment variables are lost when the <prog> ends
- The caller waits until the <prog> is finished

Using call <prog>
- For exe it can be ommited, because it's equal to just starting <prog>
- For an exe-prog the caller batch waits or starts the exe asynchronous, but the behaviour depends on the exe itself.
- For batch files, the caller batch continues, when the called <batch-file> finishes, WITHOUT call the control will not return to the caller batch


Using CALL can change the parameters (for batch and exe files), but only when they contain carets or percent signs.

call myProg param1 param^^2 "param^3" %%path%%

Will be expanded to (from within an batch file)

myProg param1 param2 param^^3 <content of path>

'this' implicitly has type 'any' because it does not have a type annotation

For method decorator declaration with configuration "noImplicitAny": true, you can specify type of this variable explicitly depends on @tony19's answer

function logParameter(this:any, target: Object, propertyName: string) {

Reactive forms - disabled attribute

in Angular-9 if you want to disable/enable on button click here is a simple solution if you are using reactive forms.

define a function in component.ts file

//enable example you can use the same approach for disable with .disable()

toggleEnable() {

Call it from your component.html


<button type="button" data-toggle="form-control" class="bg-primary text-white btn- 
                reset" style="width:100%"(click)="toggleEnable()">

Java: Rotating Images

Sorry, but all the answers are difficult to understand for me as a beginner in graphics...

After some fiddling, this is working for me and it is easy to reason about.

public void draw(Graphics2D g) {
    AffineTransform tr = new AffineTransform();
    // X and Y are the coordinates of the image
    tr.translate((int)getX(), (int)getY());
            img.getWidth() / 2,
            img.getHeight() / 2

    // img is a BufferedImage instance
    g.drawImage(img, tr, null);

I suppose that if you want to rotate a rectangular image this method wont work and will cut the image, but I thing you should create square png images and rotate that.

How to send characters in PuTTY serial communication only when pressing enter?

The settings you need are "Local echo" and "Line editing" under the "Terminal" category on the left.

To get the characters to display on the screen as you enter them, set "Local echo" to "Force on".

To get the terminal to not send the command until you press Enter, set "Local line editing" to "Force on".

PuTTY Line discipline options


From the PuTTY User Manual (Found by clicking on the "Help" button in PuTTY):

4.3.8 ‘Local echo’

With local echo disabled, characters you type into the PuTTY window are not echoed in the window by PuTTY. They are simply sent to the server. (The server might choose to echo them back to you; this can't be controlled from the PuTTY control panel.)

Some types of session need local echo, and many do not. In its default mode, PuTTY will automatically attempt to deduce whether or not local echo is appropriate for the session you are working in. If you find it has made the wrong decision, you can use this configuration option to override its choice: you can force local echo to be turned on, or force it to be turned off, instead of relying on the automatic detection.

4.3.9 ‘Local line editing’ Normally, every character you type into the PuTTY window is sent immediately to the server the moment you type it.

If you enable local line editing, this changes. PuTTY will let you edit a whole line at a time locally, and the line will only be sent to the server when you press Return. If you make a mistake, you can use the Backspace key to correct it before you press Return, and the server will never see the mistake.

Since it is hard to edit a line locally without being able to see it, local line editing is mostly used in conjunction with local echo (section 4.3.8). This makes it ideal for use in raw mode or when connecting to MUDs or talkers. (Although some more advanced MUDs do occasionally turn local line editing on and turn local echo off, in order to accept a password from the user.)

Some types of session need local line editing, and many do not. In its default mode, PuTTY will automatically attempt to deduce whether or not local line editing is appropriate for the session you are working in. If you find it has made the wrong decision, you can use this configuration option to override its choice: you can force local line editing to be turned on, or force it to be turned off, instead of relying on the automatic detection.

Putty sometimes makes wrong choices when "Auto" is enabled for these options because it tries to detect the connection configuration. Applied to serial line, this is a bit trickier to do.

How do I create a Bash alias?

On OS X you want to use ~/.bash_profile. This is because by default opens a login shell for each new window.

See more about the different configuration files and when they are used here: What's the difference between .bashrc, .bash_profile, and .environment?

and in relation to OSX here: About .bash_profile, .bashrc, and where should alias be written in?

ldconfig error: is not a symbolic link

simple run in shell : sudo apt-get install --reinstall libexpat1
got same problem with libxcb - solved in this way - very fast :)

sending email via php mail function goes to spam

Be careful with your tests. If you in your form you put the same email as the email address which must receive it will be directly in spam :)

Difference between static, auto, global and local variable in the context of c and c++

When a variable is declared static inside a class then it becomes a shared variable for all objects of that class which means that the variable is longer specific to any object. For example: -

class test
    void fun()
        static int a=0;
        cout<<"Value of a = "<<a<<"\n";
void main()
    test obj1;
    test obj2;
    test obj3;;;;

This program will generate the following output: -

Value of a = 1
Value of a = 2
Value of a = 3

The same goes for globally declared static variable. The above code will generate the same output if we declare the variable a outside function void fun()

Whereas if u remove the keyword static and declare a as a non-static local/global variable then the output will be as follows: -

Value of a = 1
Value of a = 1
Value of a = 1

Passing on command line arguments to runnable JAR

When you run your application this way, the java excecutable read the MANIFEST inside your jar and find the main class you defined. In this class you have a static method called main. In this method you may use the command line arguments.

What is the best open XML parser for C++?

TinyXML, and also Boost.PropertyTree. The latter does not fulfill all official requirements, but is very simple.

how to append a css class to an element by javascript?

When an element already has a class name defined, its influence on the element is tied to its position in the string of class names. Later classes override earlier ones, if there is a conflict.

Adding a class to an element ought to move the class name to the sharp end of the list, if it exists already.

document.addClass= function(el, css){
    var tem, C= el.className.split(/\s+/), A=[];    
        tem= C.shift();
        if(tem && tem!= css) A[A.length]= tem;
    A[A.length]= css;
    return el.className= A.join(' ');   

How can I get a vertical scrollbar in my ListBox?

The problem with your solution is you're putting a scrollbar around a ListBox where you probably want to put it inside the ListBox.

If you want to force a scrollbar in your ListBox, use the ScrollBar.VerticalScrollBarVisibility attached property.


Setting this value to Auto will popup the scrollbar on an as needed basis.

How to place object files in separate subdirectory

Since you're using GNUmake, use a pattern rule for compiling object files:

$(OBJDIR)/%.o: %.c
    $(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<

How to delete a line from a text file in C#?

string fileIN = @"C:\myTextFile.txt";
string fileOUT = @"C:\myTextFile_Out.txt";
if (File.Exists(fileIN))
    string[] data = File.ReadAllLines(fileIN);
    foreach (string line in data)
        if (!line.Equals("my line to remove"))
            File.AppendAllText(fileOUT, line);
    File.Move(fileOUT, fileIN);

What is the LD_PRELOAD trick?

Using LD_PRELOAD path, you can force the application loader to load provided shared object, over the default provided.

Developers uses this to debug their applications by providing different versions of the shared objects.

We've used it to hack certain applications, by overriding existing functions using prepared shared objects.

Get the first item from an iterable that matches a condition

By using

(index for index, value in enumerate(the_iterable) if condition(value))

one can check the condition of the value of the first item in the_iterable, and obtain its index without the need to evaluate all of the items in the_iterable.

The complete expression to use is

first_index = next(index for index, value in enumerate(the_iterable) if condition(value))

Here first_index assumes the value of the first value identified in the expression discussed above.

Closing database connections in Java

It is enough to close just Statement and Connection. There is no need to explicitly close the ResultSet object.

Java documentation says about java.sql.ResultSet:

A ResultSet object is automatically closed by the Statement object that generated it when that Statement object is closed, re-executed, or is used to retrieve the next result from a sequence of multiple results.

Thanks BalusC for comments: "I wouldn't rely on that. Some JDBC drivers fail on that."

C++11 thread-safe queue

This is probably how you should do it:

void push(std::string&& filename)
        std::lock_guard<std::mutex> lock(qMutex);



bool try_pop(std::string& filename, std::chrono::milliseconds timeout)
    std::unique_lock<std::mutex> lock(qMutex);

    if(!populatedNotifier.wait_for(lock, timeout, [this] { return !q.empty(); }))
        return false;

    filename = std::move(q.front());

    return true;    

currently unable to handle this request HTTP ERROR 500

Your site is serving a 500 Internal Server Error. This can be caused by a number of things, such as:

  • File Permissions
  • Fatal Code Errors
  • Web Server Issues


As you have highlighted it is a permission issue. You need to ensure that your files are executable by the web server user

Please see below article for some guidance on proper file permissions.

Using Mockito's generic "any()" method

You can use Mockito.isA() for that:

import static org.mockito.Matchers.isA;
import static org.mockito.Mockito.verify;


getting JRE system library unbound error in build path

Go to project then

Right click on project---> Build Path-->Configure build path

Now there are 4 tabs Source, Projects, Libraries, Order and Export

Go to

Libraries tab -->  Click on Add Library (shown at the right side) -->
select JRE System Library --> Next-->click Alternate JRE --> select
Installed JRE--> Finish --> Apply--> OK.

What methods of ‘clearfix’ can I use?

I'd float #content too, that way both columns contain floats. Also because it will allow you to clear elements inside #content without clearing the side bar.

Same thing with the wrapper, you'd need to make it a block formatting context to wrap the two columns.

This article mentions a few triggers you can use: block formatting contexts.

perform an action on checkbox checked or unchecked event on html form

The problem is how you've attached the listener:

<input type="checkbox" ...  onchange="doalert(">

Inline listeners are effectively wrapped in a function which is called with the element as this. That function then calls the doalert function, but doesn't set its this so it will default to the global object (window in a browser).

Since the window object doesn't have a checked property, this.checked always resolves to false.

If you want this within doalert to be the element, attach the listener using addEventListener:

window.onload = function() {
  var input = document.querySelector('#g01-01');
  if (input) {   
    input.addEventListener('change', doalert, false);

Or if you wish to use an inline listener:

<input type="checkbox" ...  onchange=",">

How to compare two dates to find time difference in SQL Server 2005, date manipulation

Take a look at DATEDIFF, this should be what you're looking for. It takes the two dates you're comparing, and the date unit you want the difference in (days, months, seconds...)

How to set character limit on the_content() and the_excerpt() in wordpress

For Using the_content() functions (for displaying the main content of the page)

$content = get_the_content();

echo substr($content, 0, 100);

For Using the_excerpt() functions (for displaying the excerpt-short content of the page)

$excerpt= get_the_excerpt();

echo substr($excerpt, 0, 100);

How to change the spinner background in Android?

Sample Image

When you set the spinner background color using android:background="@color/your_color" your spinner default arrow will disappear

And also need to add fixed width and height to spinner so you can show the full content of the spinner.

so i found a way to do it , just like the above image.

Write your spinner code inside a frame layout, here you don't need to use a separate image view for showing drop down icon.



                android:tooltipText="Select floor" />

Create a new xml for Frame layout background or set android:background="@color/your_color"


<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android=""
<corners android:radius="@dimen/dp_5" />
<solid android:color="@color/white" />

Can't bind to 'formControl' since it isn't a known property of 'input' - Angular2 Material Autocomplete issue

Start by adding a regular matInput to your template. Let's assume you're using the formControl directive from ReactiveFormsModule to track the value of the input.

Reactive forms provide a model-driven approach to handling form inputs whose values change over time. This guide shows you how to create and update a simple form control, progress to using multiple controls in a group, validate form values, and implement more advanced forms.

import { FormsModule, ReactiveFormsModule } from "@angular/forms"; //this to use ngModule


imports: [

How to install pip with Python 3?

Please follow below steps to install python 3 with pip:

Step 1 : Install Python from download here

Step 2 : you’ll need to download

Step 3 : After download , open your commant prompt and go to directory where your file saved .

Step 4 : Enter command python in cmd.

Step 5 : Pip installed successfully , Verify pip installation by type command in cmd pip --version

How to change environment's font size?

After Pressing Control+Shift+P as suggested by @Edwin:

  1. Look for Workspace Settings:

enter image description here

  1. Then "Place your settings in the file to the right to overwrite...default and user settings," or click the UserSettings tab to adjust the window.zoomLevel if that is the desired action.

enter image description here

How do you compare two version Strings in Java?

 *  written by: Stan Towianski - May 2018 
 * notes: I make assumption each of 3 version sections a.b.c is not longer then 4 digits: aaaa.bbbb.cccc-MODWORD1(-)modnum2
 * 5.10.13-release-1 becomes 0000500100013.501     6.0-snapshot becomes 0000600000000.100
 * MODWORD1 = -xyz/NotMatching, -SNAPSHOT, -ALPHA, -BETA, -RC, -RELEASE/nothing  return:  .0, .1, .2, .3, .4, .5
 * modnum2 = up to 2 digit/chars second version
 * */
public class VersionCk {

    private static boolean isVersionHigher( String baseVersion, String testVersion )
        System.out.println( "versionToComparable( baseVersion ) =" + versionToComparable( baseVersion ) );
        System.out.println( "versionToComparable( testVersion ) =" + versionToComparable( testVersion ) + " is this higher ?" );
        return versionToComparable( testVersion ).compareTo( versionToComparable( baseVersion ) ) > 0;

    //----  not worrying about += for something so small
    private static String versionToComparable( String version )
//        System.out.println("version - " + version);
        String versionNum = version;
        int at = version.indexOf( '-' );
        if ( at >= 0 )
            versionNum = version.substring( 0, at );

        String[] numAr = versionNum.split( "\\." );
        String versionFormatted = "0";
        for ( String tmp : numAr )
            versionFormatted += String.format( "%4s", tmp ).replace(' ', '0');
        while ( versionFormatted.length() < 12 )  // pad out to aaaa.bbbb.cccc
            versionFormatted += "0000";
//        System.out.println( "converted min version =" + versionFormatted + "=   : " + versionNum );
        return versionFormatted + getVersionModifier( version, at );

    //----  use order low to high: -xyz, -SNAPSHOT, -ALPHA, -BETA, -RC, -RELEASE/nothing  returns: 0, 1, 2, 3, 4, 5
    private static String getVersionModifier( String version, int at )
//        System.out.println("version - " + version );
        String[] wordModsAr = { "-SNAPSHOT", "-ALPHA", "-BETA", "-RC", "-RELEASE" };        

        if ( at < 0 )
            return "." + wordModsAr.length + "00";   // make nothing = RELEASE level

        int i = 1;
        for ( String word : wordModsAr )
            if ( ( at = version.toUpperCase().indexOf( word ) ) > 0 )
                return "." + i + getSecondVersionModifier( version.substring( at + word.length() ) );

        return ".000";

    //----  add 2 chars for any number after first modifier.  -rc2 or -rc-2   returns 02
    private static String getSecondVersionModifier( String version )
        System.out.println( "second modifier =" + version + "=" );
        Matcher m = Pattern.compile("(.*?)(\\d+).*").matcher( version );
//        if ( m.matches() )
//            System.out.println( "match ? =" + m.matches() + "= =" + + "= =" + + "= =" + (m.groupCount() >= 3 ? : "x") );
//        else
//            System.out.println( "No match" );
        return m.matches() ? String.format( "%2s", ).replace(' ', '0') : "00";

    public static void main(String[] args) 
        checkVersion( "3.10.0", "3.4.0");
        checkVersion( "5.4.2", "5.4.1");
        checkVersion( "5.4.4", "5.4.5");
        checkVersion( "5.4.9", "5.4.12");
        checkVersion( "5.9.222", "5.10.12");
        checkVersion( "5.10.12", "5.10.12");
        checkVersion( "5.10.13", "5.10.14");
        checkVersion( "6.7.0", "6.8");
        checkVersion( "6.7", "2.7.0");
        checkVersion( "6", "6.3.1");
        checkVersion( "4", "4.0.0");
        checkVersion( "6.3.0", "6");
        checkVersion( "5.10.12-Alpha", "5.10.12-beTA");
        checkVersion( "5.10.13-release", "5.10.14-beta");
        checkVersion( "6.7.0", "6.8-snapshot");
        checkVersion( "6.7.1", "6.7.0-release");
        checkVersion( "6-snapshot", "6.0.0-beta");
        checkVersion( "6.0-snapshot", "6.0.0-whatthe");
        checkVersion( "5.10.12-Alpha-1", "5.10.12-alpha-2");
        checkVersion( "5.10.13-release-1", "5.10.13-release2");
        checkVersion( "10-rc42", "10.0.0-rc53");

    private static void checkVersion(String baseVersion, String testVersion) 
        System.out.println( "baseVersion - " + baseVersion );
        System.out.println( "testVersion - " + testVersion );
        System.out.println( "isVersionHigher = " + isVersionHigher( baseVersion, testVersion ) );
        System.out.println( "---------------");


some output:

baseVersion - 6.7
testVersion - 2.7.0
versionToComparable( baseVersion ) =0000600070000.500
versionToComparable( testVersion ) =0000200070000.500 is this higher ?
isVersionHigher = false
baseVersion - 6
testVersion - 6.3.1
versionToComparable( baseVersion ) =0000600000000.500
versionToComparable( testVersion ) =0000600030001.500 is this higher ?
isVersionHigher = true
baseVersion - 4
testVersion - 4.0.0
versionToComparable( baseVersion ) =0000400000000.500
versionToComparable( testVersion ) =0000400000000.500 is this higher ?
isVersionHigher = false
baseVersion - 6.3.0
testVersion - 6
versionToComparable( baseVersion ) =0000600030000.500
versionToComparable( testVersion ) =0000600000000.500 is this higher ?
isVersionHigher = false
baseVersion - 5.10.12-Alpha
testVersion - 5.10.12-beTA
second modifier ==
versionToComparable( baseVersion ) =0000500100012.200
second modifier ==
versionToComparable( testVersion ) =0000500100012.300 is this higher ?
second modifier ==
second modifier ==
isVersionHigher = true
baseVersion - 5.10.13-release
testVersion - 5.10.14-beta
second modifier ==
versionToComparable( baseVersion ) =0000500100013.500
second modifier ==
versionToComparable( testVersion ) =0000500100014.300 is this higher ?
second modifier ==
second modifier ==
isVersionHigher = true
baseVersion - 6.7.0
testVersion - 6.8-snapshot
versionToComparable( baseVersion ) =0000600070000.500
second modifier ==
versionToComparable( testVersion ) =0000600080000.100 is this higher ?
second modifier ==
isVersionHigher = true
baseVersion - 6.7.1
testVersion - 6.7.0-release
versionToComparable( baseVersion ) =0000600070001.500
second modifier ==
versionToComparable( testVersion ) =0000600070000.500 is this higher ?
second modifier ==
isVersionHigher = false
baseVersion - 6-snapshot
testVersion - 6.0.0-beta
second modifier ==
versionToComparable( baseVersion ) =0000600000000.100
second modifier ==
versionToComparable( testVersion ) =0000600000000.300 is this higher ?
second modifier ==
second modifier ==
isVersionHigher = true
baseVersion - 6.0-snapshot
testVersion - 6.0.0-whatthe
second modifier ==
versionToComparable( baseVersion ) =0000600000000.100
versionToComparable( testVersion ) =0000600000000.000 is this higher ?
second modifier ==
isVersionHigher = false
baseVersion - 5.10.12-Alpha-1
testVersion - 5.10.12-alpha-2
second modifier =-1=
versionToComparable( baseVersion ) =0000500100012.201
second modifier =-2=
versionToComparable( testVersion ) =0000500100012.202 is this higher ?
second modifier =-2=
second modifier =-1=
isVersionHigher = true
baseVersion - 5.10.13-release-1
testVersion - 5.10.13-release2
second modifier =-1=
versionToComparable( baseVersion ) =0000500100013.501
second modifier =2=
versionToComparable( testVersion ) =0000500100013.502 is this higher ?
second modifier =2=
second modifier =-1=
isVersionHigher = true
baseVersion - 10-rc42
testVersion - 10.0.0-rc53
second modifier =42=
versionToComparable( baseVersion ) =0001000000000.442
second modifier =53=
versionToComparable( testVersion ) =0001000000000.453 is this higher ?
second modifier =53=
second modifier =42=
isVersionHigher = true

Python date string to date object

Use time module to convert data.

Code snippet:

import time 
var = int(time.mktime(time.strptime(tring, '%Y%m%d%H%M%S')))
print var

jquery variable syntax

The dollarsign as a prefix in the var name is a usage from the concept of the hungarian notation.

Copy/duplicate database without using mysqldump

You can duplicate a table without data by running:



You could write a script that takes the output from SHOW TABLES from one database and copies the schema to another. You should be able to reference schema+table names like:

CREATE TABLE x LIKE other_db.y;

As far as the data goes, you can also do it in MySQL, but it's not necessarily fast. After you've created the references, you can run the following to copy the data:


If you're using MyISAM, you're better off to copy the table files; it'll be much faster. You should be able to do the same if you're using INNODB with per table table spaces.

If you do end up doing an INSERT INTO SELECT, be sure to temporarily turn off indexes with ALTER TABLE x DISABLE KEYS!

EDIT Maatkit also has some scripts that may be helpful for syncing data. It may not be faster, but you could probably run their syncing scripts on live data without much locking.

Pythonic way to find maximum value and its index in a list?

sorry for reviving this thread, but thought my method was worth adding.

The list name in this example 'list'


That will print the highest value in the list easy as!

list.sort() sorts the list by the value of the item in the ASCII table, so effectively sorts the list lowest to highest. I then just print the last value in the list (which will be the greatest number) by using print(list[-1]).

Hope this helps!

IE Enable/Disable Proxy Settings via Registry

modifying the proxy value under

[HKEY_USERS\<your SID>\Software\Microsoft\Windows\CurrentVersion\Internet Settings]

doesnt need to restart ie

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

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

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

How to get css background color on <tr> tag to span entire row

Have you tried setting the spacing to zero?

/*alternating row*/
table, tr, td, th {margin:0;border:0;padding:0;spacing:0;}
tr.rowhighlight {background-color:#f0f8ff;margin:0;border:0;padding:0;spacing:0;}

How can I create a Java 8 LocalDate from a long Epoch time in Milliseconds?

replace now.getTime() with your long value.

//GET UTC time for current date
        Date now= new Date();
        //LocalDateTime utcDateTimeForCurrentDateTime = Instant.ofEpochMilli(now.getTime()).atZone(ZoneId.of("UTC")).toLocalDateTime();
        LocalDate localDate = Instant.ofEpochMilli(now.getTime()).atZone(ZoneId.of("UTC")).toLocalDate();
        DateTimeFormatter dTF2 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
        System.out.println(" formats as " + dTF2.format(utcDateTimeForCurrentDateTime));

RegEx to parse or validate Base64 data

To validate base64 image we can use this regex


  private validBase64Image(base64Image: string): boolean {
    const regex = /^data:image\/(?:gif|png|jpeg|bmp|webp)(?:;charset=utf-8)?;base64,(?:[A-Za-z0-9]|[+/])+={0,2}/;
    return base64Image && regex.test(base64Image);

How to select data from 30 days?

For those who could not get DATEADD to work, try this instead: ( NOW( ) - INTERVAL 1 MONTH )

how to make a cell of table hyperlink

you can give an <a> tag the visual behavior of a table cell:


    <a href="...">Cell 1</a>
    <td>Cell 2</td>


tr > a {
  display: table-cell;

Is it possible to declare a public variable in vba and assign a default value?

.NET has spoiled us :) Your declaration is not valid for VBA.

Only constants can be given a value upon application load. You declare them like so:


Here's a sample declaration from one of my vba projects:

VBA Constant Image

If you're looking for something where you declare a public variable and then want to initialize its value, you need to create a Workbook_Open sub and do your initialization there. Example:

Private Sub Workbook_Open()
  Dim iAnswer As Integer


  If sheetSetupInfo.Range("D6").Value = "Enter Facility Name" Then
    iAnswer = MsgBox("It appears you have not yet set up this workbook.  Would you like to do so now?", vbYesNo)
    If iAnswer = vbYes Then
      Exit Sub
    End If
  End If

  Application.Calculation = xlCalculationAutomatic
  Load frmInfoSheet

End Sub

Make sure you declare the sub in the Workbook Object itself: enter image description here

What is the function of FormulaR1C1?

Here's some info from my blog on how I like to use formular1c1 outside of vba:

You’ve just finished writing a formula, copied it to the whole spreadsheet, formatted everything and you realize that you forgot to make a reference absolute: every formula needed to reference Cell B2 but now, they all reference different cells.

How are you going to do a Find/Replace on the cells, considering that one has B5, the other C12, the third D25, etc., etc.?

The easy way is to update your Reference Style to R1C1. The R1C1 reference works with relative positioning: R marks the Row, C the Column and the numbers that follow R and C are either relative positions (between [ ]) or absolute positions (no [ ]).


  • R[2]C refers to the cell two rows below the cell in which the formula’s in
  • RC[-1] refers to the cell one column to the left
  • R1C1 refers the cell in the first row and first cell ($A$1)

What does it matter? Well, When you wrote your first formula back in the beginning of this post, B2 was the cell 4 rows above the cell you wrote it in, i.e. R[-4]C. When you copy it across and down, while the A1 reference changes, the R1C1 reference doesn’t. Throughout the whole spreadsheet, it’s R[-4]C. If you switch to R1C1 Reference Style, you can replace R[-4]C by R2C2 ($B$2) with a simple Find / Replace and be done in one fell swoop.

Total size of the contents of all the files in a directory

There are at least three ways to get the "sum total of all the data in files and subdirectories" in bytes that work in both Linux/Unix and Git Bash for Windows, listed below in order from fastest to slowest on average. For your reference, they were executed at the root of a fairly deep file system (docroot in a Magento 2 Enterprise installation comprising 71,158 files in 30,027 directories).


$ time find -type f -printf '%s\n' | awk '{ total += $1 }; END { print total" bytes" }'
748660546 bytes

real    0m0.221s
user    0m0.068s
sys     0m0.160s


$ time echo `find -type f -print0 | xargs -0 stat --format=%s | awk '{total+=$1} END {print total}'` bytes
748660546 bytes

real    0m0.256s
user    0m0.164s
sys     0m0.196s


$ time echo `find -type f -exec du -bc {} + | grep -P "\ttotal$" | cut -f1 | awk '{ total += $1 }; END { print total }'` bytes
748660546 bytes

real    0m0.553s
user    0m0.308s
sys     0m0.416s

These two also work, but they rely on commands that don't exist on Git Bash for Windows:


$ time echo `find -type f -printf "%s + " | dc -e0 -f- -ep` bytes
748660546 bytes

real    0m0.233s
user    0m0.116s
sys     0m0.176s


$ time echo `find -type f -printf '%s\n' | paste -sd+ | bc` bytes
748660546 bytes

real    0m0.242s
user    0m0.104s
sys     0m0.152s

If you only want the total for the current directory, then add -maxdepth 1 to find.

Note that some of the suggested solutions don't return accurate results, so I would stick with the solutions above instead.

$ du -sbh
832M    .

$ ls -lR | grep -v '^d' | awk '{total += $5} END {print "Total:", total}'
Total: 583772525

$ find . -type f | xargs stat --format=%s | awk '{s+=$1} END {print s}'
xargs: unmatched single quote; by default quotes are special to xargs unless you use the -0 option

$ ls -l| grep -v '^d'| awk '{total = total + $5} END {print "Total" , total}'
Total 968133

YouTube: How to present embed video with sound muted


Add &mute=1 to the end of your url.

Your new code would be:

<iframe src=";autoplay=1&mute=1" width="560" height="315" frameborder="0" allowfullscreen></iframe>

How to add a custom button to the toolbar that calls a JavaScript function?

There might be Several plugins but one may use CSS for creating button. First of all click on Source button mentioned in Editor then paste the button code over there, As I use CSS to create button and added href to it.

<p dir="ltr" style="text-align:center"><a href="" style="background-color:#0080ff; border: none;color: white;padding: 6px 20px;text-align: center;text-decoration: none;display: inline-block;border-radius: 8px;font-size: 15px; font-weight: bold;">Open App</a></p>

This is the Button Written Open App over It. You May change the Color as i am using #0080ff (Light Blue)

How do you do natural logs (e.g. "ln()") with numpy in Python?

I usually do like this:

from numpy import log as ln

Perhaps this can make you more comfortable.

Converting string format to datetime in mm/dd/yyyy

You need an uppercase M for the month part.

string strDate = DateTime.Now.ToString("MM/dd/yyyy");

Lowercase m is for outputting (and parsing) a minute (such as h:mm).

e.g. a full date time string might look like this:

string strDate = DateTime.Now.ToString("MM/dd/yyyy h:mm");

Notice the uppercase/lowercase mM difference.

Also if you will always deal with the same datetime format string, you can make it easier by writing them as C# extension methods.

public static class DateTimeMyFormatExtensions
  public static string ToMyFormatString(this DateTime dt)
    return dt.ToString("MM/dd/yyyy");

public static class StringMyDateTimeFormatExtension
  public static DateTime ParseMyFormatDateTime(this string s)
    var culture = System.Globalization.CultureInfo.CurrentCulture;
    return DateTime.ParseExact(s, "MM/dd/yyyy", culture);

EXAMPLE: Translating between DateTime/string

DateTime now = DateTime.Now;

string strNow = now.ToMyFormatString();
DateTime nowAgain = strNow.ParseMyFormatDateTime();

Note that there is NO way to store a custom DateTime format information to use as default as in .NET most string formatting depends on the currently set culture, i.e.


The only easy way you can do is to roll a custom extension method.

Also, the other easy way would be to use a different "container" or "wrapper" class for your DateTime, i.e. some special class with explicit operator defined that automatically translates to and from DateTime/string. But that is dangerous territory.

How to uncheck a radio button?

You can use this JQuery for uncheck radiobutton

                $('input:radio[name="IntroducerType"]').prop('checked', false);

How to stop IIS asking authentication for default website on localhost

This is most likely a NT file permissions problem. IUSR_ needs to have file system permissions to read whatever file you're requesting (like /inetpub/wwwroot/index.htm).

If you still have trouble, check the IIS logs, typically at \windows\system32\logfiles\W3SVC*.

How can I view a git log of just one user's commits?

try this tool


$ git standup [-a <author name>] 
              [-w <weekstart-weekend>] 
              [-m <max-dir-depth>]
              [-d <days-ago>]
              [-D <date-format>] 

Below is the description for each of the flags

- `-a`      - Specify author to restrict search to (name or email)
- `-w`      - Specify weekday range to limit search to (e.g. `git standup -w SUN-THU`)
- `-m`      - Specify the depth of recursive directory search
- `-L`      - Toggle inclusion of symbolic links in recursive directory search
- `-d`      - Specify the number of days back to include
- `-D`      - Specify the date format for "git log" (default: relative)
- `-h`      - Display the help screen
- `-g`      - Show if commit is GPG signed or not
- `-f`      - Fetch the latest commits beforehand

Cross-browser window resize event - JavaScript / jQuery

Sorry to bring up an old thread, but if someone doesn't want to use jQuery you can use this:

function foo(){....};

Logical operators for boolean indexing in Pandas

When you say

(a['x']==1) and (a['y']==10)

You are implicitly asking Python to convert (a['x']==1) and (a['y']==10) to boolean values.

NumPy arrays (of length greater than 1) and Pandas objects such as Series do not have a boolean value -- in other words, they raise

ValueError: The truth value of an array is ambiguous. Use a.empty, a.any() or a.all().

when used as a boolean value. That's because its unclear when it should be True or False. Some users might assume they are True if they have non-zero length, like a Python list. Others might desire for it to be True only if all its elements are True. Others might want it to be True if any of its elements are True.

Because there are so many conflicting expectations, the designers of NumPy and Pandas refuse to guess, and instead raise a ValueError.

Instead, you must be explicit, by calling the empty(), all() or any() method to indicate which behavior you desire.

In this case, however, it looks like you do not want boolean evaluation, you want element-wise logical-and. That is what the & binary operator performs:

(a['x']==1) & (a['y']==10)

returns a boolean array.

By the way, as alexpmil notes, the parentheses are mandatory since & has a higher operator precedence than ==. Without the parentheses, a['x']==1 & a['y']==10 would be evaluated as a['x'] == (1 & a['y']) == 10 which would in turn be equivalent to the chained comparison (a['x'] == (1 & a['y'])) and ((1 & a['y']) == 10). That is an expression of the form Series and Series. The use of and with two Series would again trigger the same ValueError as above. That's why the parentheses are mandatory.

How to Display blob (.pdf) in an AngularJS app

Most recent answer (for Angular 8+):"your-url",params,{responseType:'arraybuffer' as 'json'}).subscribe(
  (res) => {

public Content:SafeResourceUrl;
showpdf(response:ArrayBuffer) {
  var file = new Blob([response], {type: 'application/pdf'});
  var fileURL = URL.createObjectURL(file);
  this.Content = this.sanitizer.bypassSecurityTrustResourceUrl(fileURL);

  HTML :

  <embed [src]="Content" style="width:200px;height:200px;" type="application/pdf" />

AngularJS : ng-model binding not updating when changed with jQuery

You have to trigger the change event of the input element because ng-model listens to input events and the scope will be updated. However, the regular jQuery trigger didn't work for me. But here is what works like a charm

$("#myInput")[0].dispatchEvent(new Event("input", { bubbles: true })); //Works

Following didn't work

$("#myInput").trigger("change"); // Did't work for me

You can read more about creating and dispatching synthetic events.

Vue JS mounted()

Abstract your initialization into a method, and call the method from mounted and wherever else you want.

new Vue({
      //call API
      //Setup game

Then possibly have a button in your template to start over.

<button v-if="playerWon" @click="init">Play Again</button>

In this button, playerWon represents a boolean value in your data that you would set when the player wins the game so the button appears. You would set it back to false in init.

jQuery ui dialog change title after load-callback

I tried to implement the result of Nick which is:

$('.selectorUsedToCreateTheDialog').dialog('option', 'title', 'My New title');

But that didn't work for me because i had multiple dialogs on 1 page. In such a situation it will only set the title correct the first time. Trying to staple commands did not work:

    $("#modal_popup").dialog('option', 'title', 'My New Title');
    $("#modal_popup").dialog({ width: 950, height: 550);

I fixed this by adding the title to the javascript function arguments of each dialog on the page:

function show_popup1() {
    $("#modal_popup").dialog({ width: 950, height: 550, title: 'Popup Title of my First Dialog'});

function show_popup2() {
    $("#modal_popup").dialog({ width: 950, height: 550, title: 'Popup Title of my Other Dialog'});

How can I get a specific parameter from

You may use window.URL class:

new URL(location.href).searchParams.get('year')
// Returns 2008 for href = "http://localhost/search.php?year=2008".
// Or in two steps:
const params = new URL(location.href).searchParams;
const year = params.get('year');

C++ pass an array by reference

Arrays can only be passed by reference, actually:

void foo(double (&bar)[10])

This prevents you from doing things like:

double arr[20];
foo(arr); // won't compile

To be able to pass an arbitrary size array to foo, make it a template and capture the size of the array at compile time:

template<typename T, size_t N>
void foo(T (&bar)[N])
    // use N here

You should seriously consider using std::vector, or if you have a compiler that supports c++11, std::array.

How should I resolve java.lang.IllegalArgumentException: protocol = https host = null Exception?

URLs use forward slashes (/), not backward ones (as windows). Try:

serverURLS = "";

The reason why you get the error is that the URL class can't parse the host part of the string and therefore, host is null.

Overflow-x:hidden doesn't prevent content from overflowing in mobile browsers


html, body {

instead of just

body {

sql delete statement where date is greater than 30 days

Although the DATEADD is probably the most transparrent way of doing this, it is worth noting that simply getdate()-30 will also suffice.

Also, are you looking for 30 days from now, i.e. including hours, minutes, seconds, etc? Or 30 days from midnight today (e.g. 12/06/2010 00:00:00.000). In which case, you might consider:

FROM Results 
WHERE convert(varchar(8), [Date], 112) >= convert(varchar(8), getdate(), 112)

How to convert String to Date value in SAS?

input(char_val, date9.);

You can consider to convert it to word format using input(char_val, worddate.)

You can get a lot in this page

Map and filter an array at the same time

Since 2019, Array.prototype.flatMap is good option.

options.flatMap(o => o.assigned ? [] : []);

From the MDN page linked above:

flatMap can be used as a way to add and remove items (modify the number of items) during a map. In other words, it allows you to map many items to many items (by handling each input item separately), rather than always one-to-one. In this sense, it works like the opposite of filter. Simply return a 1-element array to keep the item, a multiple-element array to add items, or a 0-element array to remove the item.

I do not want to inherit the child opacity from the parent in CSS

If you have to use an image as the transparent background, you might be able to work around it using a pseudo element:


<div class="wrap"> 
   <p>I have 100% opacity</p>  


.wrap, .wrap > * {
  position: relative;
.wrap:before {
  content: " ";
  opacity: 0.2;
  background: url("") repeat;     
  position: absolute;
  width: 100%;
  height: 100%;

What are the differences between struct and class in C++?

**UPDATE: ** Please ignore this reply. I did not consider the possibility that for the struct, the value was uninitialized but just happened to be 0. There is not an initialization difference between struct and class.

I am seeing another different between structs and classes having to do with default initialization.

struct Foo {
    int a;

class Bar {
    int a;

class Tester {
    Foo m_Foo = Foo();
    Bar m_Bar = Bar();

    Tester() {}

int main() {
    auto myTester = Tester();

Run that code and examine myTester. You'll find that for m_Foo, the struct, m_Foo.a has been initialized to 0, but for m_Bar, the class, m_Bar.a is uninitialized. So there does appear to be a difference in what the default constructor does for struct vs. class. I'm seeing this with Visual Studio.

How to get error information when HttpWebRequest.GetResponse() fails

HttpWebRequest myHttprequest = null;
HttpWebResponse myHttpresponse = null;
myHttpRequest = (HttpWebRequest)WebRequest.Create(URL);
myHttpRequest.Method = "POST";
myHttpRequest.ContentType = "application/x-www-form-urlencoded";
myHttpRequest.ContentLength = urinfo.Length;
StreamWriter writer = new StreamWriter(myHttprequest.GetRequestStream());
myHttpresponse = (HttpWebResponse)myHttpRequest.GetResponse();
if (myHttpresponse.StatusCode == HttpStatusCode.OK)
   //Perform necessary action based on response

Run a vbscript from another vbscript

You can try using the Wshshell.Run method which gives you little control of the process you start with it. Or you could use the WshShell.Exec method which will give you control to terminate it, get a response, pass more parameters (other than commandline args), get status, and others

To use Run (Simple Method)

Dim ProgramPath, WshShell, ProgramArgs, WaitOnReturn,intWindowStyle
Set WshShell=CreateObject ("WScript.Shell")
ProgramPath="c:\test run script.vbs"
ProgramArgs="/hello /world"
WshShell.Run Chr (34) & ProgramPath & Chr (34) & Space (1) & ProgramArgs,intWindowStyle, WaitOnReturn

ProgramPath is the full path to your script you want to run
ProgramArgs is the arguments you want to pass to the script. (NOTE: the arguments are separated by a space, if you want to use an argument that contains a space then you will have to enclose that argument in quotes [Safe way to do this is use CHR (34) Example ProgramArgs= chr (34) & "/Hello World" & chr (34)])
IntWindowStyle is the integer that determines how the window will be displayed. More info on this and WaitOnReturn can be found here WshShell.Run Method
WaitOnReturn if true then the script will pause until the command has terminated, if false then the script will continue right after starting command.

NOTE: The Run method can return the exit code but you must set WaitOnReturn to True, and assign the 'WshShell.Run' to a variable. (EX: ExitCode=WshShell.Run (Command,intWindowStyle,True))

To Use EXEC (Advanced Method)

Dim ProgramPath, WshShell, ProgramArgs, Process, ScriptEngine
Set WshShell=CreateObject ("WScript.Shell")
ProgramPath="c:\test run script.vbs"
ProgramArgs="/hello /world"
Set Process=WshShell.Exec (ScriptEngine & space (1) & Chr(34) & ProgramPath & Chr (34) & Space (1) & ProgramArgs)
Do While Process.Status=0
    'Currently Waiting on the program to finish execution.
    WScript.Sleep 300

ProgramPath same as Run READ RUN'S DESCRIPTION
ProgramArgs DITTO
ScriptEngine The Engine you will be using for executing the script. since the exec method requires a win32 application, you need to specify this. Usually either "WScript.exe" or "CScript.exe". Note that in order to use stdin and stdout (we'll cover what these are a bit further down) you must choose "CScript.exe".
Process this is the Object that references to the program the script will start. It has several members and they are: ExitCode, ProcessID, Status, StdErr, StdIn, StdOut, Terminate.

More Details about the members of Process Object

  1. ExitCode This is the exit code that is returned when the process terminates.
  2. ProcessID This is the ID that is assigned to the process, every process has an unique processID.
  3. Status This is a code number that indicates the status of the process, it get set to '-1' when the process terminates.
  4. StdErr This is the object that represents the Standard Error Stream
  5. StdIn This is the Object that represents the Standard Input Stream, use it to write additional parameters or anything you want to pass to the script you are calling. (Process.StdIn.WriteLine "Hello Other Worlds")
  6. StdOut This is the Object that represents the Standard Output Stream, It is READONLY so you can use Process.StdOut.ReadLine. This is the stream that the called script will receive any information sent by the calling script's stdin. If you used the stdin's example then StdOut.Readline will return "Hello Other Worlds". If there is nothing to read then the script will hang while waiting for an output. meaning the script will appear to be Not Responding
    Note: you can use Read or ReadAll instead of ReadLine if you want. Use Read (X) if you want to read X amount of characters. Or ReadAll if you want the rest of the stream.
  7. Terminate Call this method to force terminate the process.

For more information about WshShell.Exec go to Exec Method Windows Scripting Host

Difference between hamiltonian path and euler path

Euler path is a graph using every edge(NOTE) of the graph exactly once. Euler circuit is a euler path that returns to it starting point after covering all edges.

While hamilton path is a graph that covers all vertex(NOTE) exactly once. When this path returns to its starting point than this path is called hamilton circuit.

Delete specific line number(s) from a text file using sed?

$ cat foo
$ sed -e '2d;4d' foo


Joins can only be used when there is an association between entities. Your Employee entity should not have a field named id_team, of type int, mapped to a column. It should have a ManyToOne association with the Team entity, mapped as a JoinColumn:

private Team team;

Then, the following query will work flawlessly:

select e from Employee e inner join

Which will load all the employees, except those that aren't associated to any team.

The same goes for all the other fields which are a foreign key to some other table mapped as an entity, of course (id_boss, id_profession).

It's time for you to read the Hibernate documentation, because you missed an extremely important part of what it is and how it works.

Catch Ctrl-C in C


void sig_handler(int signo)
  if (signo == SIGINT)
    printf("received SIGINT\n");

int main(void)
  if (signal(SIGINT, sig_handler) == SIG_ERR)
  printf("\ncan't catch SIGINT\n");
  // A long long wait so that we can easily issue a signal to this process
  return 0;

The function sig_handler checks if the value of the argument passed is equal to the SIGINT, then the printf is executed.

How to replace a set of tokens in a Java String?

String.format("Hello %s Please find attached %s which is due on %s", name, invoice, date)

SQL Query to search schema of all tables

Use this query :

SELECT AS table_name,
    SCHEMA_NAME(schema_id) AS schema_name, AS column_name , *
FROM sys.tables AS t
    INNER JOIN sys.columns c ON t.OBJECT_ID = c.OBJECT_ID 
    ( LIKE '%' + '<ColumnName>' + '%' )
    ( t.type = 'U' ) -- Use This To Prevent Selecting System Tables

How to Set Variables in a Laravel Blade Template

In , you can use the template comment syntax to define/set variables.

Comment syntax is {{-- anything here is comment --}} and it is rendered by engine as

<?php /* anything here is comment */ ?>

so with little trick we can use it to define variables, for example

{{-- */$i=0;/* --}}

will be rendered by as <?php /* */$i=0;/* */ ?> which sets the variable for us. Without changing any line of code.

How to get the Mongo database specified in connection string in C#

With version 1.7 of the official 10gen driver, this is the current (non-obsolete) API:

const string uri = "mongodb://localhost/mydb";
var client = new MongoClient(uri);
var db = client.GetServer().GetDatabase(new MongoUrl(uri).DatabaseName);
var collection = db.GetCollection("mycollection");

Floating point exception( core dump

You are getting Floating point exception because Number % i, when i is 0:

int Is_Prime( int Number ){

  int i ;

  for( i = 0 ; i < Number / 2 ; i++ ){

    if( Number % i != 0 ) return -1 ;


  return Number ;


Just start the loop at i = 2. Since i = 1 in Number % i it always be equal to zero, since Number is a int.

JAX-RS / Jersey how to customize error handling?

Approach 1: By extending WebApplicationException class

Create new exception by extending WebApplicationException

public class RestException extends WebApplicationException {

         private static final long serialVersionUID = 1L;

         public RestException(String message, Status status) {

Now throw 'RestException' whenever required.

public static Employee getEmployee(int id) {

         Employee emp = employees.get(id);

         if (emp == null) {
                 throw new RestException("Employee with id " + id + " not exist", Status.NOT_FOUND);
         return emp;

You can see complete application at this link.

Approach 2: Implement ExceptionMapper

Following mapper handles exception of type 'DataNotFoundException'

public class DataNotFoundExceptionMapper implements
        ExceptionMapper<DataNotFoundException> {

    public Response toResponse(DataNotFoundException ex) {
        ErrorMessage model = new ErrorMessage(ex.getErrorCode(),
        return Response.status(Status.NOT_FOUND).entity(model).build();


You can see complete application at this link.

Get Selected value from dropdown using JavaScript

The first thing i noticed is that you have a semi colon just after your closing bracket for your if statement );

You should also try and clean up your if statement by declaring a variable for the answer separately.

function answers() {

var select = document.getElementById("mySelect");
var answer = select.options[select.selectedIndex].value;

    if(answer == "To measure time"){
        alert("Thats correct"); 


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

Since c is holding the address of an integer pointer, its type should be int**:

int **c;
c = &a;

The entire program becomes:

#include <stdio.h>                                                              
int main(){
    int b=10;
    int *a;
    int **c;
    printf("%d",(**c));   //successfully prints 10
    return 0;

How to use Microsoft.Office.Interop.Excel on a machine without installed MS Office?

Look for GSpread.NET. You can work with Google Spreadsheets by using API from Microsoft Excel. You don't need to rewrite old code with the new Google API usage. Just add a few row:

Set objExcel = CreateObject("GSpreadCOM.Application");

app.MailLogon(Name, ClientIdAndSecret, ScriptId);

It's an OpenSource project and it doesn't require Office to be installed.

The documentation available over here

Difference between logical addresses, and physical addresses?

A logical address is a reference to memory location independent of the current assignment of data to memory. A physical address or absolute address is an actual location in main memory.

It is in chapter 7.2 of Stallings.

Why should we include ttf, eot, woff, svg,... in a font-face

WOFF 2.0, based on the Brotli compression algorithm and other improvements over WOFF 1.0 giving more than 30 % reduction in file size, is supported in Chrome, Opera, and Firefox. has an example on how to use it.

Basically you add a src url to the woff2 file and specify the woff2 format. It is important to have this before the woff-format: the browser will use the first format that it supports.

What are FTL files

An ftl file could just have a series of html tags just as a JSP page or it can have freemarker template coding for representing the objects passed on from a controller java file.
But, its actual ability is to combine the contents of a java class and view/client side stuff(html/ JQuery/ javascript etc). It is quite similar to velocity. You could map a method or object of a class to a freemarker (.ftl) page and use it as if it is a variable or a functionality created in the very page.

What is an idiomatic way of representing enums in Go?

Here is an example that will prove useful when there are many enumerations. It uses structures in Golang, and draws upon Object Oriented Principles to tie them all together in a neat little bundle. None of the underlying code will change when a new enumeration is added or deleted. The process is:

  • Define an enumeration structure for enumeration items: EnumItem. It has an integer and string type.
  • Define the enumeration as a list of enumeration items: Enum
  • Build methods for the enumeration. A few have been included:
    • enum.Name(index int): returns the name for the given index.
    • enum.Index(name string): returns the name for the given index.
    • enum.Last(): returns the index and name of the last enumeration
  • Add your enumeration definitions.

Here is some code:

type EnumItem struct {
    index int
    name  string

type Enum struct {
    items []EnumItem

func (enum Enum) Name(findIndex int) string {
    for _, item := range enum.items {
        if item.index == findIndex {
    return "ID not found"

func (enum Enum) Index(findName string) int {
    for idx, item := range enum.items {
        if findName == {
            return idx
    return -1

func (enum Enum) Last() (int, string) {
    n := len(enum.items)
    return n - 1, enum.items[n-1].name

var AgentTypes = Enum{[]EnumItem{{0, "StaffMember"}, {1, "Organization"}, {1, "Automated"}}}
var AccountTypes = Enum{[]EnumItem{{0, "Basic"}, {1, "Advanced"}}}
var FlagTypes = Enum{[]EnumItem{{0, "Custom"}, {1, "System"}}}

How to get the position of a character in Python?

There are two string methods for this, find() and index(). The difference between the two is what happens when the search string isn't found. find() returns -1 and index() raises ValueError.

Using find()

>>> myString = 'Position of a character'
>>> myString.find('s')
>>> myString.find('x')

Using index()

>>> myString = 'Position of a character'
>>> myString.index('s')
>>> myString.index('x')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found

From the Python manual

string.find(s, sub[, start[, end]])
Return the lowest index in s where the substring sub is found such that sub is wholly contained in s[start:end]. Return -1 on failure. Defaults for start and end and interpretation of negative values is the same as for slices.


string.index(s, sub[, start[, end]])
Like find() but raise ValueError when the substring is not found.

Hide/Show components in react native

Just simply use this because I wanted to use the "useRef" conditions were not an option for me. You can use this suppose when you want to use useRef hook and press the button.

      buttonStyle={{ width: 0, height: 0, opacity: 0, display: "none" }}

How to get distinct values for non-key column fields in Laravel?

$users = User::all();
foreach($users->unique('column_name') as $user){
    code here..

How can I add an item to a SelectList in MVC

May not sound very elegant, but I usually do something like this:

    var items = repository.func.ToList();
    items.Insert(0, new funcItem { ID = 0, TextValue = "[None]" });
    ViewBag.MyData = new SelectList(items);

How to implement WiX installer upgrade?

In the newest versions (from the 3.5.1315.0 beta), you can use the MajorUpgrade element instead of using your own.

For example, we use this code to do automatic upgrades. It prevents downgrades, giving a localised error message, and also prevents upgrading an already existing identical version (i.e. only lower versions are upgraded):

    AllowDowngrades="no" DowngradeErrorMessage="!(loc.NewerVersionInstalled)"

How do I change button size in Python?

Configuring a button (or any widget) in Tkinter is done by calling a configure method "config"

To change the size of a button called button1 you simple call

button1.config( height = WHATEVER, width = WHATEVER2 )

If you know what size you want at initialization these options can be added to the constructor.

button1 = Button(self, text = "Send", command = self.response1, height = 100, width = 100) 

Make child div stretch across width of page

With current browsers (this question is dating a bit now), you can use the much simpler vw (viewport width) unit:

#help_panel {
  margin-left: calc(50% - 50vw);
  width: 100vw;

(usage data:

From my tests, this should not break your flow while being easy to use.

Difference Between One-to-Many, Many-to-One and Many-to-Many?

One-to-Many: One Person Has Many Skills, a Skill is not reused between Person(s)

  • Unidirectional: A Person can directly reference Skills via its Set
  • Bidirectional: Each "child" Skill has a single pointer back up to the Person (which is not shown in your code)

Many-to-Many: One Person Has Many Skills, a Skill is reused between Person(s)

  • Unidirectional: A Person can directly reference Skills via its Set
  • Bidirectional: A Skill has a Set of Person(s) which relate to it.

In a One-To-Many relationship, one object is the "parent" and one is the "child". The parent controls the existence of the child. In a Many-To-Many, the existence of either type is dependent on something outside the both of them (in the larger application context).

Your subject matter (domain) should dictate whether or not the relationship is One-To-Many or Many-To-Many -- however, I find that making the relationship unidirectional or bidirectional is an engineering decision that trades off memory, processing, performance, etc.

What can be confusing is that a Many-To-Many Bidirectional relationship does not need to be symmetric! That is, a bunch of People could point to a skill, but the skill need not relate back to just those people. Typically it would, but such symmetry is not a requirement. Take love, for example -- it is bi-directional ("I-Love", "Loves-Me"), but often asymmetric ("I love her, but she doesn't love me")!

All of these are well supported by Hibernate and JPA. Just remember that Hibernate or any other ORM doesn't give a hoot about maintaining symmetry when managing bi-directional many-to-many relationships...thats all up to the application.

vertical & horizontal lines in matplotlib

If you want to add a bounding box, use a rectangle:

ax = plt.gca()
r = matplotlib.patches.Rectangle((.5, .5), .25, .1, fill=False)

Rectangle doc

JPA and Hibernate - Criteria vs. JPQL or HQL

Criteria is an object-oriented API, while HQL means string concatenation. That means all of the benefits of object-orientedness apply:

  1. All else being equal, the OO version is somewhat less prone to error. Any old string could get appended into the HQL query, whereas only valid Criteria objects can make it into a Criteria tree. Effectively, the Criteria classes are more constrained.
  2. With auto-complete, the OO is more discoverable (and thus easier to use, for me at least). You don't necessarily need to remember which parts of the query go where; the IDE can help you
  3. You also don't need to remember the particulars of the syntax (like which symbols go where). All you need to know is how to call methods and create objects.

Since HQL is very much like SQL (which most devs know very well already) then these "don't have to remember" arguments don't carry as much weight. If HQL was more different, then this would be more importatnt.

How to change colour of blue highlight on select box dropdown

i just found this site that give a cool themes for the select box

and you can try this themes if your problem with the overall look blue - yellow - grey

How to display both icon and title of action inside ActionBar?

Using app:showAsAction="always|withText". I am using Android 4.1.1, but it should applicable anyway. Mine look like below


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.

Notice: Undefined offset: 0 in

If you are using dompdf/dompdf and error occure in vendor/dompdf/dompdf/src/Cellmap.php then It looks like we're using the wrong frame id in the update_row_group method. Initial testing seems to confirm this. Though that may be because this is strictly a paged table issue and not too many of the documents in my test bed have paged tables.

Can you try changing line 800 to:

$r_rows = $this->_frames[$g_key]["rows"];
($g_key instead of $r_key)

Setting default values for columns in JPA

Neither JPA nor Hibernate annotations support the notion of a default column value. As a workaround to this limitation, set all default values just before you invoke a Hibernate save() or update() on the session. This closely as possible (short of Hibernate setting the default values) mimics the behaviour of the database which sets default values when it saves a row in a table.

Unlike setting the default values in the model class as this alternative answer suggests, this approach also ensures that criteria queries that use an Example object as a prototype for the search will continue to work as before. When you set the default value of a nullable attribute (one that has a non-primitive type) in a model class, a Hibernate query-by-example will no longer ignore the associated column where previously it would ignore it because it was null.

Django: OperationalError No Such Table

The Thing that worked for me:

  1. Find out which migrations in your migration folder created the table if not add the class in your
  2. If the class already exist in your, try to delete that one and run python makemigrations <appname>
  3. And while migrating fake that migrations as your error might say table not found to delete using python migrate <yourappname> --fake
  4. Add the class again and makemigrations again python makemigrations <appname>.
  5. And finally migrate again python migrate <appname>

Download an SVN repository?

Google page have a link that you can download the source code and the full tree.

Go to the Source tab, then click on Browse

then you see the link for Download it as:

Dependency injection with Jersey 2.0

Oracle recommends to add the @Path annotation to all types to be injected when combining JAX-RS with CDI: Though this is far from perfect (e.g. you will get warning from Jersey on startup), I decided to take this route, which saves me from maintaining all supported types within a binder.


public class ConfigurationService {

class MyProvider {
  @Inject ConfigurationService _configuration;

  public Object get() {..}

How to check if an integer is within a range of numbers in PHP?

You can try the following one-statement:

if (($x-$min)*($x-$max) < 0)


if (max(min($x, $max), $min) == $x)

Highcharts - how to have a chart with dynamic height?

What if you hooked the window resize event:


See example fiddle here.

Highcharts API Reference : setSize().

Android on-screen keyboard auto popping up

You can use either this in the onCreate() method of the activity


or paste this code in the Activity tags in AndroidManifest.xml


Sticky and NON-Sticky sessions

I've made an answer with some more details here :

Or you can read it there ==>

When you use loadbalancing it means you have several instances of tomcat and you need to divide loads.

  • If you're using session replication without sticky session : Imagine you have only one user using your web app, and you have 3 tomcat instances. This user sends several requests to your app, then the loadbalancer will send some of these requests to the first tomcat instance, and send some other of these requests to the secondth instance, and other to the third.
  • If you're using sticky session without replication : Imagine you have only one user using your web app, and you have 3 tomcat instances. This user sends several requests to your app, then the loadbalancer will send the first user request to one of the three tomcat instances, and all the other requests that are sent by this user during his session will be sent to the same tomcat instance. During these requests, if you shutdown or restart this tomcat instance (tomcat instance which is used) the loadbalancer sends the remaining requests to one other tomcat instance that is still running, BUT as you don't use session replication, the instance tomcat which receives the remaining requests doesn't have a copy of the user session then for this tomcat the user begin a session : the user loose his session and is disconnected from the web app although the web app is still running.
  • If you're using sticky session WITH session replication : Imagine you have only one user using your web app, and you have 3 tomcat instances. This user sends several requests to your app, then the loadbalancer will send the first user request to one of the three tomcat instances, and all the other requests that are sent by this user during his session will be sent to the same tomcat instance. During these requests, if you shutdown or restart this tomcat instance (tomcat instance which is used) the loadbalancer sends the remaining requests to one other tomcat instance that is still running, as you use session replication, the instance tomcat which receives the remaining requests has a copy of the user session then the user keeps on his session : the user continue to browse your web app without being disconnected, the shutdown of the tomcat instance doesn't impact the user navigation.

wget ssl alert handshake failure

I was having this problem on Ubuntu 12.04.3 LTS (well beyond EOL, I know...) and got around it with:

sudo apt-get update && sudo apt-get install ca-certificates

How to check Network port access and display useful message?

I improved Salselvaprabu's answer in several ways:

  1. It is now a function - you can put in your powershell profile and use anytime you need
  2. It can accept host as hostname or as ip address
  3. No more exceptions if host or port unavaible - just text

Call it like this:

Test-Port 999
Test-Port 80

function Test-Port($hostname, $port)
    # This works no matter in which form we get $host - hostname or ip address
    try {
        $ip = [System.Net.Dns]::GetHostAddresses($hostname) | 
            select-object IPAddressToString -expandproperty  IPAddressToString
        if($ip.GetType().Name -eq "Object[]")
            #If we have several ip's for that address, let's take first one
            $ip = $ip[0]
    } catch {
        Write-Host "Possibly $hostname is wrong hostname or IP"
    $t = New-Object Net.Sockets.TcpClient
    # We use Try\Catch to remove exception info from console if we can't connect
    } catch {}

        $msg = "Port $port is operational"
        $msg = "Port $port on $ip is closed, "
        $msg += "You may need to contact your IT team to open it. "                                 
    Write-Host $msg

How can I define fieldset border color?

I added it for all fieldsets with

fieldset {
        border: 1px solid lightgray;

I didnt work if I set it separately using for example

border-color : red

. Then a black line was drawn next to the red line.

How to work with complex numbers in C?

For convenience, one may include tgmath.h library for the type generate macros. It creates the same function name as the double version for all type of variable. For example, For example, it defines a sqrt() macro that expands to the sqrtf() , sqrt() , or sqrtl() function, depending on the type of argument provided.

So one don't need to remember the corresponding function name for different type of variables!

#include <stdio.h>
#include <tgmath.h>//for the type generate macros. 
#include <complex.h>//for easier declare complex variables and complex unit I

int main(void)
    double complex z1=1./4.*M_PI+1./4.*M_PI*I;//M_PI is just pi=3.1415...
    double complex z2, z3, z4, z5; 


    printf("exp(z1)=%lf + %lf I\n", creal(z2),cimag(z2));
    printf("sin(z1)=%lf + %lf I\n", creal(z3),cimag(z3));
    printf("sqrt(z1)=%lf + %lf I\n", creal(z4),cimag(z4));
    printf("log(z1)=%lf + %lf I\n", creal(z5),cimag(z5));

    return 0;

Getting RSA private key from PEM BASE64 Encoded private key file

You've just published that private key, so now the whole world knows what it is. Hopefully that was just for testing.

EDIT: Others have noted that the openssl text header of the published key, -----BEGIN RSA PRIVATE KEY-----, indicates that it is PKCS#1. However, the actual Base64 contents of the key in question is PKCS#8. Evidently the OP copy and pasted the header and trailer of a PKCS#1 key onto the PKCS#8 key for some unknown reason. The sample code I've provided below works with PKCS#8 private keys.

Here is some code that will create the private key from that data. You'll have to replace the Base64 decoding with your IBM Base64 decoder.

public class RSAToy {

    private static final String BEGIN_RSA_PRIVATE_KEY = "-----BEGIN RSA PRIVATE KEY-----\n"
            + "MIIEuwIBADAN ...skipped the rest\n"
         // + ...   
         // + ... skipped the rest
         // + ...   
            + "-----END RSA PRIVATE KEY-----";

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

        // Remove the first and last lines

        String privKeyPEM = BEGIN_RSA_PRIVATE_KEY.replace("-----BEGIN RSA PRIVATE KEY-----\n", "");
        privKeyPEM = privKeyPEM.replace("-----END RSA PRIVATE KEY-----", "");

        // Base64 decode the data

        byte [] encoded = Base64.decode(privKeyPEM);

        // PKCS8 decode the encoded RSA private key

        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encoded);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        PrivateKey privKey = kf.generatePrivate(keySpec);

        // Display the results


Disable Scrolling on Body

Set height and overflow:

html, body {margin: 0; height: 100%; overflow: hidden}

How to use the start command in a batch file?

I think this other Stack Overflow answer would solve your problem: How do I run a bat file in the background from another bat file?

Basically, you use the /B and /C options:

START /B CMD /C CALL "foo.bat" [args [...]] >NUL 2>&1

How to find index of list item in Swift?

In case somebody has this problem

Cannot invoke initializer for type 'Int' with an argument list of type '(Array<Element>.Index?)'

jsut do this

extension Int {
    var toInt: Int {
        return self


guard let finalIndex = index?.toInt else {
    return false

How do I prompt for Yes/No/Cancel input in a Linux shell script?

Bash has select for this purpose.

select result in Yes No Cancel
    echo $result

Delete default value of an input text on click

we can do it without using js in the following way using the "placeholder" attribute of html5 ( the default text disappears when the user starts to type in ,but not on just clicking )

<input type="email" id="email" placeholder="[email protected]">

see this:

Could not resolve in Android Studio new project

In my case, this error occur when i tried to use gridView

I resolved it by removing this line from build.grade(Module) file

implementation ''

How to get function parameter names/values dynamically?

Solution that is less error prone to spaces and comments would be:

var fn = function(/* whoa) */ hi, you){};


["hi", "you"]

How to format a java.sql.Timestamp(yyyy-MM-dd HH:mm:ss.S) to a date(yyyy-MM-dd HH:mm:ss)

You do not need to use substring at all since your format doesn't hold that info.

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String fechaStr = "2013-10-10 10:49:29.10000";  
Date fechaNueva = format.parse(fechaStr);

System.out.println(format.format(fechaNueva)); // Prints 2013-10-10 10:49:29

installing urllib in Python3.6

urllib is a standard python library (built-in) so you don't have to install it. just import it if you need to use request by:

import urllib.request

if it's not work maybe you compiled python in wrong way, so be kind and give us more details.

jQuery: more than one handler for same event

Suppose that you have two handlers, f and g, and want to make sure that they are executed in a known and fixed order, then just encapsulate them:


In this way there is (from the perspective of jQuery) only one handler, which calls f and g in the specified order.

Could not autowire field:RestTemplate in Spring boot application

Depending on what technologies you're using and what versions will influence how you define a RestTemplate in your @Configuration class.

Spring >= 4 without Spring Boot

Simply define an @Bean:

public RestTemplate restTemplate() {
    return new RestTemplate();

Spring Boot <= 1.3

No need to define one, Spring Boot automatically defines one for you.

Spring Boot >= 1.4

Spring Boot no longer automatically defines a RestTemplate but instead defines a RestTemplateBuilder allowing you more control over the RestTemplate that gets created. You can inject the RestTemplateBuilder as an argument in your @Bean method to create a RestTemplate:

public RestTemplate restTemplate(RestTemplateBuilder builder) {
   // Do any additional configuration here

Using it in your class

private RestTemplate restTemplate;


Bad Request - Invalid Hostname IIS7

For Visual Studio 2017 and Visual Studio 2015, IIS Express settings is stored in the hidden .vs directory and the path is something like this .vs\config\applicationhost.config, add binding like below will work

    <binding protocol="http" bindingInformation="*:8802:localhost" />
    <binding protocol="http" bindingInformation="*:8802:" />


How to allow only numeric (0-9) in HTML inputbox using jQuery?

try it within html code it self like onkeypress and onpast

<input type="text" onkeypress="return event.charCode >= 48 && event.charCode <= 57" onpaste="return false">

Free XML Formatting tool

Try The algorithm is similar to HTML Tidy, but is more complete. The program is written entirely in JavaScript, so you don't have to install anything.

What does O(log n) mean exactly?

In simple words:

The next iteration of the loop takes double the time the current one took --> n^2

The next iteration of the loop takes same the time the current one is going to take --> n

The next iteration of the loop takes half the time the current one is going to take --> log2(n)

The next iteration of the loop takes 1/3rd the time the current one is going to take --> log3(n)

The next iteration of the loop takes 1/4th the time the current one is going to take --> log4(n)

When it comes to Asymptotic analysis, we just call log(n) which can be basically any base as shown above. But since we computer scientists use binary trees more than other types of trees, we end up with log2(n) most of the times which we just term log(n).

List attributes of an object

attributes_list = [attribute for attribute in dir(obj) if attribute[0].islower()]

How to change maven java home

Appears to be a duplicate of assuming that you are using Ubuntu.

The key is to use the command sudo update-java-alternatives -s java-6-sun. Any commands that rely on javac will be affected and not just Maven.

Char array declaration and initialization in C

Yes, this is a kind of inconsistency in the language.

The "=" in myarray = "abc"; is assignment (which won't work as the array is basically a kind of constant pointer), whereas in char myarray[4] = "abc"; it's an initialization of the array. There's no way for "late initialization".

You should just remember this rule.

Set a:hover based on class

Cascading is biting you. Try this:

.menu > .main-nav-item:hover

This code says to grab all the links that have a class of main-nav-item AND are children of the class menu, and apply the color #DDD when they are hovered. error adding symbols: DSO missing from command line

What I have found is that sometimes the library that the linker complains about is not the one causing the problem. Possibly there is a clever way to work out where the problem is but this is what I do:

  • Comment out all the linked libraries in the link command.
  • Clean out all .o's, .so's etc (Usually make clean is enough, but you may want to run a recursive find + rm, or something similar).
  • Uncomment the libraries in the link command one at a time and re-arrange the order as necessary.

@peter karasev: I have come across the same problem with a gcc 4.8.2 cmake project on CentOS7. The order of the libraries in "target_link_libraries" section is important. I guess cmake just passes the list on to the linker as-is, i.e. it doesn't try and work out the correct order. This is reasonable - when you think about it cmake can't know what the correct order is until the linking is successfully completed.

What's the difference between deadlock and livelock?

Maybe these two examples illustrate you the difference between a deadlock and a livelock:

Java-Example for a deadlock:

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class DeadlockSample {

    private static final Lock lock1 = new ReentrantLock(true);
    private static final Lock lock2 = new ReentrantLock(true);

    public static void main(String[] args) {
        Thread threadA = new Thread(DeadlockSample::doA,"Thread A");
        Thread threadB = new Thread(DeadlockSample::doB,"Thread B");

    public static void doA() {
        System.out.println(Thread.currentThread().getName() + " : waits for lock 1");
        System.out.println(Thread.currentThread().getName() + " : holds lock 1");

        try {
            System.out.println(Thread.currentThread().getName() + " : waits for lock 2");
            System.out.println(Thread.currentThread().getName() + " : holds lock 2");

            try {
                System.out.println(Thread.currentThread().getName() + " : critical section of doA()");
            } finally {
                System.out.println(Thread.currentThread().getName() + " : does not hold lock 2 any longer");
        } finally {
            System.out.println(Thread.currentThread().getName() + " : does not hold lock 1 any longer");

    public static void doB() {
        System.out.println(Thread.currentThread().getName() + " : waits for lock 2");
        System.out.println(Thread.currentThread().getName() + " : holds lock 2");

        try {
            System.out.println(Thread.currentThread().getName() + " : waits for lock 1");
            System.out.println(Thread.currentThread().getName() + " : holds lock 1");

            try {
                System.out.println(Thread.currentThread().getName() + " : critical section of doB()");
            } finally {
                System.out.println(Thread.currentThread().getName() + " : does not hold lock 1 any longer");
        } finally {
            System.out.println(Thread.currentThread().getName() + " : does not hold lock 2 any longer");

Sample output:

Thread A : waits for lock 1
Thread B : waits for lock 2
Thread A : holds lock 1
Thread B : holds lock 2
Thread B : waits for lock 1
Thread A : waits for lock 2

Java-Example for a livelock:

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class LivelockSample {

    private static final Lock lock1 = new ReentrantLock(true);
    private static final Lock lock2 = new ReentrantLock(true);

    public static void main(String[] args) {
        Thread threadA = new Thread(LivelockSample::doA, "Thread A");
        Thread threadB = new Thread(LivelockSample::doB, "Thread B");

    public static void doA() {
        try {
            while (!lock1.tryLock()) {
                System.out.println(Thread.currentThread().getName() + " : waits for lock 1");
            System.out.println(Thread.currentThread().getName() + " : holds lock 1");

            try {
                while (!lock2.tryLock()) {
                    System.out.println(Thread.currentThread().getName() + " : waits for lock 2");
                System.out.println(Thread.currentThread().getName() + " : holds lock 2");

                try {
                    System.out.println(Thread.currentThread().getName() + " : critical section of doA()");
                } finally {
                    System.out.println(Thread.currentThread().getName() + " : does not hold lock 2 any longer");
            } finally {
                System.out.println(Thread.currentThread().getName() + " : does not hold lock 1 any longer");
        } catch (InterruptedException e) {
            // can be ignored here for this sample

    public static void doB() {
        try {
            while (!lock2.tryLock()) {
                System.out.println(Thread.currentThread().getName() + " : waits for lock 2");
            System.out.println(Thread.currentThread().getName() + " : holds lock 2");

            try {
                while (!lock1.tryLock()) {
                    System.out.println(Thread.currentThread().getName() + " : waits for lock 1");
                System.out.println(Thread.currentThread().getName() + " : holds lock 1");

                try {
                    System.out.println(Thread.currentThread().getName() + " : critical section of doB()");
                } finally {
                    System.out.println(Thread.currentThread().getName() + " : does not hold lock 1 any longer");
            } finally {
                System.out.println(Thread.currentThread().getName() + " : does not hold lock 2 any longer");
        } catch (InterruptedException e) {
            // can be ignored here for this sample

Sample output:

Thread B : holds lock 2
Thread A : holds lock 1
Thread A : waits for lock 2
Thread B : waits for lock 1
Thread B : waits for lock 1
Thread A : waits for lock 2
Thread A : waits for lock 2
Thread B : waits for lock 1
Thread B : waits for lock 1
Thread A : waits for lock 2
Thread A : waits for lock 2
Thread B : waits for lock 1

Both examples force the threads to aquire the locks in different orders. While the deadlock waits for the other lock, the livelock does not really wait - it desperately tries to acquire the lock without the chance of getting it. Every try consumes CPU cycles.

IO Error: The Network Adapter could not establish the connection

Most probably you have listener configured wrongly, the hostname you specify in connection string must be the same as in the listener.

First check the Firewall and network related issues.

Check if Oracle Listener service is available and running. If not you may use Oracle Net Configuration Assistant tool to add and register new listener.

If the above steps are ok then you need to configure Oracle Listener appropriately. You may use Oracle Net Manager tool or edit “%ORACLE_HOME%\network\admin\listener.ora” file manually.

There are 2 options that need to be considered carefully: Listening Locations associated with the Listener – Hostname(IP) and Port in Listening Location must exactly match the ones used in the connection string.

For example, if you use as target hostname, then there must be Listening Location registered with the same IP address.

Also make sure the you use the same SID as indicated in Database Service associated with the Listener.

How do I fit an image (img) inside a div and keep the aspect ratio?

Try CSS:

img {
  object-fit: cover;
  height: 48px;

How to set the image from drawable dynamically in android?

imageview= (ImageView)findViewById(;

Onclick function based on element id

you can try these:

document.getElementById("RootNode").onclick = function(){/*do something*/};


$('#RootNode').click(function(){/*do something*/});


$(document).on("click", "#RootNode", function(){/*do something*/});

There is a point for the first two method which is, it matters where in your page DOM, you should put them, the whole DOM should be loaded, to be able to find the, which is usually it gets solved if you wrap them in a window.onload or DOMReady event, like:

//in Vanilla JavaScript
window.addEventListener("load", function(){
     document.getElementById("RootNode").onclick = function(){/*do something*/};
//for jQuery
    $('#RootNode').click(function(){/*do something*/});

How do I use PHP to get the current year?

$year = date("Y", strtotime($yourDateVar));

Left join only selected columns in R with the merge() function

Nothing elegant but this could be another satisfactory answer.

merge(x = DF1, y = DF2, by = "Client", all.x=TRUE)[,c("Client","LO","CON")]

This will be useful especially when you don't need the keys that were used to join the tables in your results.

What is the difference between List and ArrayList?

There's no difference between list implementations in both of your examples. There's however a difference in a way you can further use variable myList in your code.

When you define your list as:

List myList = new ArrayList();

you can only call methods and reference members that are defined in the List interface. If you define it as:

ArrayList myList = new ArrayList();

you'll be able to invoke ArrayList-specific methods and use ArrayList-specific members in addition to those whose definitions are inherited from List.

Nevertheless, when you call a method of a List interface in the first example, which was implemented in ArrayList, the method from ArrayList will be called (because the List interface doesn't implement any methods).

That's called polymorphism. You can read up on it.

Better way to call javascript function in a tag

Neither is good.

Behaviour should be configured independent of the actual markup. For instance, in jQuery you might do something like

$('#the-element').click(function () { /* perform action here */ });

in a separate <script> block.

The advantage of this is that it

  1. Separates markup and behaviour in the same way that CSS separates markup and style
  2. Centralises configuration (this is somewhat a corollary of 1).
  3. Is trivially extensible to include more than one argument using jQuery’s powerful selector syntax

Furthermore, it degrades gracefully (but so would using the onclick event) since you can provide the link tags with a href in case the user doesn’t have JavaScript enabled.

Of course, these arguments still count if you’re not using jQuery or another JavaScript library (but why do that?).

how to open Jupyter notebook in chrome on windows

See response on this thread that has worked for me:

NOTE - Additional STEP 3 that has made the difference for me compared to similar approaches suggested here

In short:

Step 1 - Generate config for Jupyter Notebook:

jupyter notebook --generate-config

Step 2 - Edit the config file using "nano" or other editor

The config fileshould be under your home directory under ".jupyter" folder:


Step 3 - Disable launching browser by redirecting file

First comment out the line, then change True to False:

c.NotebookApp.use_redirect_file = False

Step 4 - add a line to your .bashrc file to set the BROWSER path

export BROWSER='/mnt/c/Program Files (x86)/Google/Chrome/Application/chrome.exe'

For me it was Chrome under my Windows Program File. Otherwise any linux installation under WSL doesn't have a native browser to launch, so need to set it to the Windows executable.

Step 5 - restart .bashrc

source .bashrc

Inverse of matrix in R

solve(c) does give the correct inverse. The issue with your code is that you are using the wrong operator for matrix multiplication. You should use solve(c) %*% c to invoke matrix multiplication in R.

R performs element by element multiplication when you invoke solve(c) * c.

Python non-greedy regexes

>>> x = "a (b) c (d) e"
>>>"\(.*\)", x).group()
'(b) c (d)'
>>>"\(.*?\)", x).group()

According to the docs:

The '*', '+', and '?' qualifiers are all greedy; they match as much text as possible. Sometimes this behavior isn’t desired; if the RE <.*> is matched against '<H1>title</H1>', it will match the entire string, and not just '<H1>'. Adding '?' after the qualifier makes it perform the match in non-greedy or minimal fashion; as few characters as possible will be matched. Using .*? in the previous expression will match only '<H1>'.

How Can I Bypass the X-Frame-Options: SAMEORIGIN HTTP Header?

As for second question - you can use Fiddler filters to set response X-Frame-Options header manually to something like ALLOW-FROM *. But, of course, this trick will work only for you - other users still won't be able to see iframe content(if they not do the same).

How do I print colored output with Python 3?

Here's a class of mine I use to color specific output in Python 3 scripts. You could import the class and use like so: from colorprint import ColorPrint as _ _.print_fail('Error occurred, quitting program')

import sys

# Colored printing functions for strings that use universal ANSI escape sequences.
# fail: bold red, pass: bold green, warn: bold yellow, 
# info: bold blue, bold: bold white

class ColorPrint:

    def print_fail(message, end = '\n'):
        sys.stderr.write('\x1b[1;31m' + message.strip() + '\x1b[0m' + end)

    def print_pass(message, end = '\n'):
        sys.stdout.write('\x1b[1;32m' + message.strip() + '\x1b[0m' + end)

    def print_warn(message, end = '\n'):
        sys.stderr.write('\x1b[1;33m' + message.strip() + '\x1b[0m' + end)

    def print_info(message, end = '\n'):
        sys.stdout.write('\x1b[1;34m' + message.strip() + '\x1b[0m' + end)

    def print_bold(message, end = '\n'):
        sys.stdout.write('\x1b[1;37m' + message.strip() + '\x1b[0m' + end)

How to check if a double is null?

To say that something "is null" means that it is a reference to the null value. Primitives (int, double, float, etc) are by definition not reference types, so they cannot have null values. You will need to find out what your database wrapper will do in this case.

C# equivalent to Java's charAt()?

Simply use String.ElementAt(). It's quite similar to java's String.charAt(). Have fun coding!

Develop Android app using C#

Here is a new one (Note: in Tech Preview stage):

It is basically a Visual Studio add-in that lets you compile your C# code directly to DEX code. This means there is no run-time requirement such as Mono.

Disclosure: I work for this company

UPDATE: all sources are now on

MS Access - execute a saved query by name in VBA

You can do it the following way:

DoCmd.OpenQuery "yourQueryName", acViewNormal, acEdit



How do I find out if the GPS of an Android device is enabled

Here are the steps:

Step 1: Create services running in background.

Step 2: You require following permission in Manifest file too:


Step 3: Write code:

 final LocationManager manager = (LocationManager)context.getSystemService    (Context.LOCATION_SERVICE );

if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) )
  Toast.makeText(context, "GPS is disabled!", Toast.LENGTH_LONG).show(); 
  Toast.makeText(context, "GPS is enabled!", Toast.LENGTH_LONG).show();

Step 4: Or simply you can check using:

LocationManager manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE );
boolean statusOfGPS = manager.isProviderEnabled(LocationManager.GPS_PROVIDER);

Step 5: Run your services continuously to monitor connection.

How to select first parent DIV using jQuery?

two of the best options are



and of course you can find the class attr by



Eclipse count lines of code

For static analysis, I've used and recommend SonarQube which runs just about all the metrics you could possibly want on a wide range of languages, and is free in the basic version (you have to pay to analyse the sorts of languages I'd only code in with a gun to my head).

You have to install it as a web-app running the analysis off your source code repository, but it also has an Eclipse plugin.

It's overkill if you just want to know, as a one-off, how many lines of code there are in your project. If you want to track metrics through time, compare across projects, fire warnings when a threshold is exceeded, etc., it's fantastic.

Disclosure: I have no financial relationship with SonarSource.

How to "properly" create a custom object in JavaScript?

I use this pattern fairly frequently - I've found that it gives me a pretty huge amount of flexibility when I need it. In use it's rather similar to Java-style classes.

var Foo = function()

    var privateStaticMethod = function() {};
    var privateStaticVariable = "foo";

    var constructor = function Foo(foo, bar)
        var privateMethod = function() {};
        this.publicMethod = function() {};

    constructor.publicStaticMethod = function() {};

    return constructor;

This uses an anonymous function that is called upon creation, returning a new constructor function. Because the anonymous function is called only once, you can create private static variables in it (they're inside the closure, visible to the other members of the class). The constructor function is basically a standard Javascript object - you define private attributes inside of it, and public attributes are attached to the this variable.

Basically, this approach combines the Crockfordian approach with standard Javascript objects to create a more powerful class.

You can use it just like you would any other Javascript object:

Foo.publicStaticMethod(); //calling a static method
var test = new Foo();     //instantiation
test.publicMethod();      //calling a method


When soapAction is missing in the SOAP 1.2 request (and many clients do not set it, even when it is specified in WSDL), some app servers (eg. jboss) infer the "actual" soapAction from {xsd:import namespace}+{wsdl:operation name}. So, to make the inferred "actual" soapAction match the expected soapAction, you can set the expected soapAction to {xsd:import namespace}+{wsdl:operation name} in your WS definition (@WebMethod(action=...) for Java EE)

Eg. for a typical Java EE case, this helps (not the Stewart's case, National Rail WS has 'soapAction' set):

@WebMethod(action = "")

If you cannot change the server, you will have to force client to fill soapAction.

How to make an element in XML schema optional?

Try this

<xs:element name="description" type="xs:string" minOccurs="0" maxOccurs="1" />

if you want 0 or 1 "description" elements, Or

<xs:element name="description" type="xs:string" minOccurs="0" maxOccurs="unbounded" />

if you want 0 to infinity number of "description" elements.

Recursively counting files in a Linux directory

You can use the command ncdu. It will recursively count how many files a Linux directory contains. Here is an example of output:

enter image description here

It has a progress bar, which is convenient if you have many files:

enter image description here

To install it on Ubuntu:

sudo apt-get install -y ncdu

Benchmark: I used (380390 files, 11 GB) as the folder where one has to count the number of files.

  • find . -type f | wc -l: around 1m20s to complete
  • ncdu: around 1m20s to complete

Finding the number of days between two dates

number of days between two dates in PHP

      function dateDiff($date1, $date2)  //days find function
            $diff = strtotime($date2) - strtotime($date1); 
            return abs(round($diff / 86400)); 
       //start day
       $date1 = "11-10-2018";        
       // end day
       $date2 = "31-10-2018";    
       // call the days find fun store to variable 
       $dateDiff = dateDiff($date1, $date2); 

       echo "Difference between two dates: ". $dateDiff . " Days "; 

List all the files and folders in a Directory with PHP recursive function

Here is what I came up with and this is with not much lines of code

function show_files($start) {
    $contents = scandir($start);
    array_splice($contents, 0,2);
    echo "<ul>";
    foreach ( $contents as $item ) {
        if ( is_dir("$start/$item") && (substr($item, 0,1) != '.') ) {
            echo "<li>$item</li>";
        } else {
            echo "<li>$item</li>";
    echo "</ul>";


It outputs something like


** The dots are the dots of unoordered list.

Hope this helps.

How to join multiple lines of file names into one with custom delimiter?

Don't reinvent the wheel.

ls -m

It does exactly that.

How do I fix a NoSuchMethodError?

One such instance where this error occurs: I happened to make a silly mistake of accessing private static member variables in a non static method. Changing the method to static solved the problem.

How to solve static declaration follows non-static declaration in GCC C code?

Try -Wno-traditional.

But better, add declarations for your static functions:

static void foo (void);

// ... somewhere in code
    foo ();

static void foo ()
    // do sth

How to return more than one value from a function in Python?

Return as a tuple, e.g.

def foo (a):
    return (x,y)

Array.push() and unique items

In case if you are looking for one liner

For primitives

this.items.indexOf(item) === -1) && this.items.push(item);

For objects

this.items.findIndex((item: ItemType) => item.var === checkValue) === -1 && this.items.push(item);

Read all files in a folder and apply a function to each data frame

usually i don't use for loop in R, but here is my solution using for loops and two packages : plyr and dostats

plyr is on cran and you can download dostats on (may be using install_github from Hadley devtools package)

Assuming that i have your first two data.frame (Df.1 and Df.2) in csv files, you can do something like this.


files <- list.files(pattern = ".csv")

for (i in seq_along(files)) {

    assign(paste("Df", i, sep = "."), read.csv(files[i]))

    assign(paste(paste("Df", i, sep = ""), "summary", sep = "."), 
           ldply(get(paste("Df", i, sep = ".")), dostats, sum, min, mean, median, max))


Here is the output

R> Df1.summary
  .id sum min   mean median max
1   A  34   4 5.6667    5.5   8
2   B  22   1 3.6667    3.0   9
R> Df2.summary
  .id sum min   mean median max
1   A  21   1 3.5000    3.5   6
2   B  16   1 2.6667    2.5   5