Programs & Examples On #Radupload

What is the difference between pip and conda?

pip is for Python only

conda is only for Anaconda + other scientific packages like R dependencies etc. NOT everyone needs Anaconda that already comes with Python. Anaconda is mostly for those who do Machine learning/deep learning etc. Casual Python dev won't run Anaconda on his laptop.

How to quickly drop a user with existing privileges

I had to add one more line to REVOKE...

After running:


I was still receiving the error: username cannot be dropped because some objects depend on it DETAIL: privileges for schema public

I was missing this:


Then I was able to drop the role.

DROP USER username;

How do I check for vowels in JavaScript?

I created a simplified version using Array.prototype.includes(). My technique is similar to @Kunle Babatunde.

const isVowel = (char) => ["a", "e", "i", "o", "u"].includes(char);_x000D_
console.log(isVowel("o"), isVowel("s"));

Iterate over a Javascript associative array in sorted order

Get the keys in the first for loop, sort it, use the sorted result in the 2nd for loop.

var a = new Array();
a['b'] = 1;
a['z'] = 1;
a['a'] = 1;

var b = [];
for (k in a) b.push(k);
for (var i = 0; i < b.length; ++i) alert(b[i]);

Unable to use Intellij with a generated sources folder

You can just change the project structure to add that folder as a "source" directory.

Project Structure ? Modules ? Click the generated-sources folder and make it a sources folder.



Maximum concurrent Socket.IO connections

This guy appears to have succeeded in having over 1 million concurrent connections on a single Node.js server.

It's not clear to me exactly how many ports he was using though.

Convert char array to a int number in C

It's not what the question asks but I used @Rich Drummond 's answer for a char array read in from stdin which is null terminated.

char *buff;
size_t buff_size = 100;
int choice;
    buff = (char *)malloc(buff_size *sizeof(char));
    getline(&buff, &buff_size, stdin);
    choice = atoi(buff);

Java - How do I make a String array with values?

By using the array initializer list syntax, ie:

String myArray[] = { "one", "two", "three" };

Create a txt file using batch file in a specific folder

Changed the set to remove % as that will write to text file as Echo on or off

echo off
title Custom Text File
set /p txt=What do you want it to say? ; 
echo %txt% > "D:\Testing\dblank.txt"

How to get row index number in R?

Perhaps this complementary example of "match" would be helpful.

Having two datasets:

first_dataset <- data.frame(name = c("John", "Luke", "Simon", "Gregory", "Mary"),
                            role = c("Audit", "HR", "Accountant", "Mechanic", "Engineer"))

second_dataset <- data.frame(name = c("Mary", "Gregory", "Luke", "Simon"))

If the name column contains only unique across collection values (across whole collection) then you can access row in other dataset by value of index returned by match

name_mapping <- match(second_dataset$name, first_dataset$name)

match returns proper row indexes of names in first_dataset from given names from second: 5 4 2 1 example here - accesing roles from first dataset by row index (by given name value)

for(i in 1:length(name_mapping)) {
    role <- as.character(first_dataset$role[name_mapping[i]])   
    second_dataset$role[i] = role


second dataset with new column:
     name       role
1    Mary   Engineer
2 Gregory   Mechanic
3    Luke Supervisor
4   Simon Accountant

Handle JSON Decode Error when nothing returned

There is a rule in Python programming called "it is Easier to Ask for Forgiveness than for Permission" (in short: EAFP). It means that you should catch exceptions instead of checking values for validity.

Thus, try the following:

    qByUser =
    qUserData = json.loads(qByUser).decode('utf-8')
    questionSubjs = qUserData["all"]["questions"]
except ValueError:  # includes simplejson.decoder.JSONDecodeError
    print 'Decoding JSON has failed'

EDIT: Since simplejson.decoder.JSONDecodeError actually inherits from ValueError (proof here), I simplified the catch statement by just using ValueError.

Error : java.lang.NoSuchMethodError: org.objectweb.asm.ClassWriter.<init>(I)V

I change my APIs as * cglib --- to ---> cglib-nodep-2.2.jar * cglib-asm --- to ---> cglib-asm.jar (i.e. latest one )

Does it make sense to use Require.js with Angular.js?

This I believe is a subjective question, so I will provide my subjective opinion.

Angular has a modularization mechanism built in. When you create your app, the first thing you would do is

var app = angular.module("myApp");

and then




If you have a look at the angular-seed which is neat starter app for angular, they have separated out the directives, services, controllers etc into different modules and then loaded those modules as dependancies on your main app.

Something like :

var app = angular.module("myApp",["Directives","Controllers","Services"];

Angular also lazy loads these modules ( into memory) not their script files.

In terms of lazy loading script files, to be frank unless you are writing something extremely large it would be an overkill because angular by its very nature reduces the amount of code you write. A typical app written in most other frameworks could expect a reduction in around 30-50% in LOC if written in angular.

How do I extract the contents of an rpm?

Copy the .rpm file in a separate folder then run the following command $ yourfile.rpm | cpio -idmv

Placeholder in UITextView

Another solution

import UIKit

protocol PlaceholderTextViewDelegate: class {

    func placeholderTextViewDidChangeText(_ text: String)
    func placeholderTextViewDidEndEditing(_ text: String)

final class PlaceholderTextView: UITextView {

    weak var notifier: PlaceholderTextViewDelegate?
    var ignoreEnterAction: Bool = true

    var placeholder: String? {
        didSet {
            text = placeholder
            selectedRange = NSRange(location: 0, length: 0)

    var placeholderColor = UIColor.lightGray {
        didSet {
            if text == placeholder {
                textColor = placeholderColor
    var normalTextColor = UIColor.lightGray

    var placeholderFont = UIFont.sfProRegular(28)

    fileprivate var placeholderLabel: UILabel?

    // MARK: - LifeCycle

    override var text: String? {
        didSet {
            if text == placeholder {
                textColor = placeholderColor
            } else {
                textColor = normalTextColor

    init() {
        super.init(frame:, textContainer: nil)

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

    override func awakeFromNib() {

        self.delegate = self

extension PlaceholderTextView: UITextViewDelegate {

    // MARK: - UITextViewDelegate
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {

        if text == "" && textView.text == placeholder {
            return false

        if let placeholder = placeholder,
            textView.text == placeholder,
            range.location <= placeholder.count {
            textView.text = ""

        if ignoreEnterAction && text == "\n" {
            return false
        return true

    func textViewDidChange(_ textView: UITextView) {
        if let placeholder = placeholder {
            textView.text = textView.text.replacingOccurrences(of: placeholder, with: "")

        if let placeholder = placeholder,
            text?.isEmpty == true {
            text = placeholder
            textColor = placeholderColor

            selectedRange = NSRange(location: 0, length: 0)
        } else {
            textColor = normalTextColor


    func textViewDidChangeSelection(_ textView: UITextView) {
        if let placeholder = placeholder,
            text == placeholder {
            selectedRange = NSRange(location: 0, length: 0)

    func textViewDidEndEditing(_ textView: UITextView) {

        if let placeholder = placeholder,
            text?.isEmpty == true {
            text = placeholder
            textColor = placeholderColor
            selectedRange = NSRange(location: 0, length: 0)
        } else {
            textColor = normalTextColor


enter image description here

Dynamic loading of images in WPF

This is strange behavior and although I am unable to say why this is occurring, I can recommend some options.

First, an observation. If you include the image as Content in VS and copy it to the output directory, your code works. If the image is marked as None in VS and you copy it over, it doesn't work.

Solution 1: FileStream

The BitmapImage object accepts a UriSource or StreamSource as a parameter. Let's use StreamSource instead.

        FileStream stream = new FileStream("picture.png", FileMode.Open, FileAccess.Read);
        Image i = new Image();
        BitmapImage src = new BitmapImage();
        src.StreamSource = stream;
        i.Source = src;
        i.Stretch = Stretch.Uniform;

The problem: stream stays open. If you close it at the end of this method, the image will not show up. This means that the file stays write-locked on the system.

Solution 2: MemoryStream

This is basically solution 1 but you read the file into a memory stream and pass that memory stream as the argument.

        MemoryStream ms = new MemoryStream();
        FileStream stream = new FileStream("picture.png", FileMode.Open, FileAccess.Read);
        stream.Read(ms.GetBuffer(), 0, (int)stream.Length);


        Image i = new Image();
        BitmapImage src = new BitmapImage();
        src.StreamSource = ms;
        i.Source = src;
        i.Stretch = Stretch.Uniform;

Now you are able to modify the file on the system, if that is something you require.

Is there a way to override class variables in Java?

If you are going to override it I don't see a valid reason to keep this static. I would suggest the use of abstraction (see example code). :

     public interface Person {
        public abstract String getName();
       //this will be different for each person, so no need to make it concrete
        public abstract void setName(String name);

Now we can add the Dad:

public class Dad implements Person {

    private String name;

    public Dad(String name) {

    public final String getName() {
    return name;

    public final void setName(String name) { = name;

the son:

public class Son implements Person {

    private String name;

    public Son(String name) {

    public final String getName() {
        return name;

    public final void setName(String name) { = name;

and Dad met a nice lady:

public class StepMom implements Person {

    private String name;

    public StepMom(String name) {

    public final String getName() {
        return name;

    public final void setName(String name) { = name;

Looks like we have a family, lets tell the world their names:

public class ConsoleGUI {

    public static void main(String[] args) {
        List<Person> family = new ArrayList<Person>();
        family.add(new Son("Tommy"));
        family.add(new StepMom("Nancy"));
        family.add(new Dad("Dad"));
        for (Person person : family) {
            //using the getName vs printName lets the caller, in this case the
            //ConsoleGUI determine versus being forced to output through the console. 
            System.out.print(person.getName() + " ");
            System.err.print(person.getName() + " ");
            JOptionPane.showMessageDialog(null, person.getName());


System.out Output : Tommy Nancy Dad
System.err is the same as above(just has red font)
JOption Output:
Tommy then
Nancy then

what is Segmentation fault (core dumped)?

"Segmentation fault" means that you tried to access memory that you do not have access to.

The first problem is with your arguments of main. The main function should be int main(int argc, char *argv[]), and you should check that argc is at least 2 before accessing argv[1].

Also, since you're passing in a float to printf (which, by the way, gets converted to a double when passing to printf), you should use the %f format specifier. The %s format specifier is for strings ('\0'-terminated character arrays).

What does `set -x` do?

set -x enables a mode of the shell where all executed commands are printed to the terminal. In your case it's clearly used for debugging, which is a typical use case for set -x: printing every command as it is executed may help you to visualize the control flow of the script if it is not functioning as expected.

set +x disables it.

SQL Server 2008: how do I grant privileges to a username?

If you want to give your user all read permissions, you could use:

EXEC sp_addrolemember N'db_datareader', N'your-user-name'

That adds the default db_datareader role (read permission on all tables) to that user.

There's also a db_datawriter role - which gives your user all WRITE permissions (INSERT, UPDATE, DELETE) on all tables:

EXEC sp_addrolemember N'db_datawriter', N'your-user-name'

If you need to be more granular, you can use the GRANT command:

GRANT SELECT, INSERT ON dbo.YourTable2 TO YourUserName
GRANT SELECT, DELETE ON dbo.YourTable3 TO YourUserName

and so forth - you can granularly give SELECT, INSERT, UPDATE, DELETE permission on specific tables.

This is all very well documented in the MSDN Books Online for SQL Server.

And yes, you can also do it graphically - in SSMS, go to your database, then Security > Users, right-click on that user you want to give permissions to, then Properties adn at the bottom you see "Database role memberships" where you can add the user to db roles.

alt text

Read a file one line at a time in node.js?

Since posting my original answer, I found that split is a very easy to use node module for line reading in a file; Which also accepts optional parameters.

var split = require('split');
    .on('data', function (line) {
      //each chunk now is a seperate line! 

Haven't tested on very large files. Let us know if you do.

Error: Selection does not contain a main type

I hope you are trying to run the main class in this way, see screenshot:
screenshot of Eclipse file context menu

If not, then try this way. If yes, then please make sure that your class you are trying to run has a main method, that is, the same method definition as below:

public static void main(String[] args) {
    // some code here

I hope this will help you.

Undefined columns selected when subsetting data frame

You want rows where that condition is true so you need a comma:

data[data$Ozone > 14, ]

What do all of Scala's symbolic operators mean?

<= is just like you would "read" it: 'less than or equals'. So it's a mathematical operator, in the list of < (is less than?), > (is greater than?), == (equals?), != (is not equal?), <= (is less than or equal?), and >= (is greater than or equal?).

This must not be confused with => which is kind of a double right-hand arrow, used to separate the argument list from the body of a function and to separate the testing condition in pattern matching (a case block) from the body executed when a match occurs. You can see example of this in my previous two answers. First, the function use: => tup._2.reverse)

which is already abbreviated as the types are omitted. The follow function would be

// function arguments         function body
(tup: Tuple2[Int, String]) => tup._2.reverse

and the pattern matching use:

def extract2(l: List[Int]) = l match {
   // if l matches Nil    return "empty"
   case Nil            => "empty"
   // etc.
   case ::(head, Nil)  => "exactly one element (" + head + ")"
   // etc.
   case ::(head, tail) => "more than one element"

Fitting a Normal distribution to 1D data

Here you are not fitting a normal distribution. Replacing sns.distplot(data) by sns.distplot(data, fit=norm, kde=False) should do the trick.

How to implement a custom AlertDialog View

The easiest way to do this is by using instead of where public AlertDialog.Builder setView (int layoutResId) can be used below API 21.

new AlertDialog.Builder(getActivity())
        new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                //Do something
        new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                //Do something

Return only string message from Spring MVC 3 Controller

@RequestMapping(value="/get-text", produces="text/plain")
public String myMethod() {
     return "Response!";
  • You see that @ResponseBody ?

It's telling that the method returns some text and not to interpret it as a view etc.

  • You see that produces="text/plain" ?

It's just a good practice as it tells what will be returned from the method :)

Debugging Spring configuration

If you use Spring Boot, you can also enable a “debug” mode by starting your application with a --debug flag.

java -jar myapp.jar --debug

You can also specify debug=true in your

When the debug mode is enabled, a selection of core loggers (embedded container, Hibernate, and Spring Boot) are configured to output more information. Enabling the debug mode does not configure your application to log all messages with DEBUG level.

Alternatively, you can enable a “trace” mode by starting your application with a --trace flag (or trace=true in your Doing so enables trace logging for a selection of core loggers (embedded container, Hibernate schema generation, and the whole Spring portfolio).

How can I add a space in between two outputs?


class Main
    public static void main(String[] args)  
        int a=10, b=20;
        System.out.println(a + " " + b);

Input: none

Output: 10 20

Do fragments really need an empty constructor?

As noted by CommonsWare in this question, this error can also occur if you are creating an anonymous subclass of a Fragment, since anonymous classes cannot have constructors.

Don't make anonymous subclasses of Fragment :-)

Python: Pandas pd.read_excel giving ImportError: Install xlrd >= 0.9.0 for Excel support

I was getting an error

"ImportError: Install xlrd >= 1.0.0 for Excel support"

on Pycharm for below code

import pandas as pd
df2 = pd.read_excel("data.xlsx")

Solution : pip install xlrd

It resolved error after using this. Also no need to use "import xlrd"

How to edit default dark theme for Visual Studio Code?

Any color theme can be changed in this settings section on VS Code version 1.12 or higher:

 // Overrides colors from the currently selected color theme.
  "workbench.colorCustomizations": {}


Available values to edit:

EDIT: To change syntax colors, see here: and here:

Execute a terminal command from a Cocoa app

fork, exec, and wait should work, if you're not really looking for a Objective-C specific way. fork creates a copy of the currently running program, exec replaces the currently running program with a new one, and wait waits for the subprocess to exit. For example (without any error checking):

#include <stdlib.h>
#include <unistd.h>

pid_t p = fork();
if (p == 0) {
    /* fork returns 0 in the child process. */
    execl("/other/program/to/run", "/other/program/to/run", "foo", NULL);
} else {
    /* fork returns the child's PID in the parent. */
    int status;
    /* The child has exited, and status contains the way it exited. */

/* The child has run and exited by the time execution gets to here. */

There's also system, which runs the command as if you typed it from the shell's command line. It's simpler, but you have less control over the situation.

I'm assuming you're working on a Mac application, so the links are to Apple's documentation for these functions, but they're all POSIX, so you should be to use them on any POSIX-compliant system.

How to avoid the "Windows Defender SmartScreen prevented an unrecognized app from starting warning"

After clicking on Properties of any installer(.exe) which block your application to install (Windows Defender SmartScreen prevented an unrecognized app ) for that issue i found one solution

  1. Right click on installer(.exe)
  2. Select properties option.
  3. Click on checkbox to check Unblock at the bottom of Properties.

This solution work for Heroku CLI (heroku-x64) installer(.exe)

Get the ID of a drawable in ImageView

I recently run into the same problem. I solved it by implementing my own ImageView class.

Here is my Kotlin implementation:

class MyImageView(context: Context): ImageView(context) {
    private var currentDrawableId: Int? = null

    override fun setImageResource(resId: Int) {
        currentDrawableId = resId

    fun getDrawableId() {
        return currentDrawableId

    fun compareCurrentDrawable(toDrawableId: Int?): Boolean {
        if (toDrawableId == null || currentDrawableId != toDrawableId) {
            return false

        return true


Is there any way of configuring Eclipse IDE proxy settings via an autoproxy configuration script?

In the file: $your_eclipse_installation\configuration.settings\

you need the option: systemProxiesEnabled=true

You can set it also by the Eclipse GUI: Go to Window -> Preferences -> General -> Network Connections Change the provider to "Native"

The first way is working even if your Eclipse is broken due to wrong configuration attempts.

Given URL is not permitted by the application configuration

Missing from the other answers is how to allow localhost(or or whatever) as an oauth callback url. Here is the explanation. How can I add localhost:3000 to Facebook App for development

How do I remove an array item in TypeScript?

You can use the splice method on an array to remove the elements.

for example if you have an array with the name arr use the following:

arr.splice(2, 1);

so here the element with index 2 will be the starting point and the argument 2 will determine how many elements to be deleted.

If you want to delete the last element of the array named arr then do this:

arr.splice(arr.length-1, 1);

This will return arr with the last element deleted.


var arr = ["orange", "mango", "banana", "sugar", "tea"];
arr.splice(arr.length-1, 1)
console.log(arr); // return ["orange", "mango", "banana", "sugar"]

Purpose of __repr__ method?

This is explained quite well in the Python documentation:

repr(object): Return a string containing a printable representation of an object. This is the same value yielded by conversions (reverse quotes). It is sometimes useful to be able to access this operation as an ordinary function. For many types, this function makes an attempt to return a string that would yield an object with the same value when passed to eval(), otherwise the representation is a string enclosed in angle brackets that contains the name of the type of the object together with additional information often including the name and address of the object. A class can control what this function returns for its instances by defining a __repr__() method.

So what you're seeing here is the default implementation of __repr__, which is useful for serialization and debugging.

How to create a DateTime equal to 15 minutes ago?

Use DateTime in addition to a timedelta object

Meaning of end='' in the statement print("\t",end='')?

The default value of end is \n meaning that after the print statement it will print a new line. So simply stated end is what you want to be printed after the print statement has been executed

Eg: - print ("hello",end=" +") will print hello +

How to change maven logging level to display only warning and errors?

Unfortunately, even with maven 3 the only way to do that is to patch source code.

Here is short instruction how to do that.

Clone or fork Maven 3 repo: "git clone"

Edit org.apache.maven.cli.MavenCli#logging, and change

cliRequest.request.setLoggingLevel( MavenExecutionRequest.LOGGING_LEVEL_INFO );


cliRequest.request.setLoggingLevel( MavenExecutionRequest.LOGGING_LEVEL_WARN );

In current snapshot version it's at line 270

Then just run "mvn install", your new maven distro will be located in "apache-maven\target\" folder

See this diff for the reference:

The cause of "bad magic number" error when loading a workspace and how to avoid it?

I had this problem when I saved the Rdata file in an older version of R and then I tried to open in a new one. I solved by updating my R version to the newest.

Git resolve conflict using --ours/--theirs for all files

git diff --name-only --diff-filter=U | xargs git checkout --theirs

Seems to do the job. Note that you have to be cd'ed to the root directory of the git repo to achieve this.

Is there a way to make mv create the directory to be moved to if it doesn't exist?

The following shell script, perhaps?

if [[ -e $1 ]]
  if [[ ! -d $2 ]]
    mkdir --parents $2
mv $1 $2

That's the basic part. You might want to add in a bit to check for arguments, and you may want the behavior to change if the destination exists, or the source directory exists, or doesn't exist (i.e. don't overwrite something that doesn't exist).

Forbidden You don't have permission to access /wp-login.php on this server

I had a similar error, which was fixed by adding:

Options FollowSymLinks

... in the apps/[app-name]/conf/httpd-app.conf file. This is because, in my case, an .htaccess file wants to use rewrite rules, that are not allowed with FollowSymLinks AND SymLinksIfOwnerMatch turned off.

If your conf file already has a line with Options ..., you can just add FollowSymLinks to the list of options. You could end up with something like this:

Options Indexes MultiViews FollowSymLinks

show/hide html table columns using css

I don't think there is anything you can do to avoid what you are already doing, however, if you are building the table on the client with javascript, you can always add the style rules dynamically, so you can allow for any number of columns without cluttering up your css file with all those rules. See if you don't know how to do this.

Edit: For your "sticky" toggle, you should just append class names rather than replacing them. For instance, you can give it a class name of "hide2 hide3" etc. I don't think you really need the "show" classes, since that would be the default. Libraries like jQuery make this easy, but in the absence, a function like this might help:

var modifyClassName = function (elem, add, string) {
var s = (elem.className) ? elem.className : "";
var a = s.split(" ");
if (add) {
  for (var i=0; i<a.length; i++) {
      if (a[i] == string) {
  s += " " + string;
else {
    s = "";
    for (var i=0; i<a.length; i++) {
        if (a[i] != string)
            s += a[i] + " "; 
elem.className = s;

How can I create a simple message box in Python?

ctype module with threading

i was using the tkinter messagebox but it would crash my code. i didn't want to find out why so i used the ctypes module instead.

for example:

import ctypes
ctypes.windll.user32.MessageBoxW(0, "Your text", "Your title", 1)

i got that code from Arkelis

i liked that it didn't crash the code so i worked on it and added a threading so the code after would run.

example for my code

import ctypes
import threading

def MessageboxThread(buttonstyle, title, text, icon):
        target=lambda: ctypes.windll.user32.MessageBoxW(buttonstyle, text, title, icon)

messagebox(0, "Your title", "Your text", 1)

for button styles and icon numbers:

## Button styles:
# 0 : OK
# 1 : OK | Cancel
# 2 : Abort | Retry | Ignore
# 3 : Yes | No | Cancel
# 4 : Yes | No
# 5 : Retry | No
# 6 : Cancel | Try Again | Continue

## To also change icon, add these values to previous number
# 16 Stop-sign icon
# 32 Question-mark icon
# 48 Exclamation-point icon
# 64 Information-sign icon consisting of an 'i' in a circle

Android Studio: Module won't show up in "Edit Configuration"

I fixed this by adding facets in Module settings. They were missing. right click on project > open Module settings > Facets > Add facets ( "+" sign at the top ) > Android. After adding facets you will have modules.


For latest version of gradle, Facets have been removed, you can directly add modules now. right click on project > open Module settings > Add module ( "+" sign at the top ) > Phone and Tablet Application (Now you can create a new module and configure it).

simulate background-size:cover on <video> or <img>

Right after our long comment section, I think this is what you're looking for, it's jQuery based:


<img width="100%" id="img" src="">


<script type="text/javascript">
window.onload = function(){
       var img = document.getElementById('img')


    overflow: hidden;

?The code above is using the browsers width and height if you where doing this within a div, you would have to change it to something like this:

For Div:


<div style="width:100px; max-height: 100px;" id="div">
     <img width="100%" id="img" src="">


<script type="text/javascript">
window.onload = function(){
       var img = document.getElementById('img')


   overflow: hidden;

I should also state that I've only tested this is Google Chrome... here is a jsfiddle:

How to get the full path of the file from a file input

You cannot do so - the browser will not allow this because of security concerns. Although there are workarounds, the fact is that you shouldn't count on this working. The following Stack Overflow questions are relevant here:

In addition to these, the new HTML5 specification states that browsers will need to feed a Windows compatible fakepath into the input type="file" field, ostensibly for backward compatibility reasons.

So trying to obtain the path is worse then useless in newer browsers - you'll actually get a fake one instead.

Making a div vertically scrollable using CSS

You can use overflow-y: scroll for vertical scrolling.

<div  style="overflow-y:scroll; height:400px; background:gray">_x000D_
  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum._x000D_
  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum._x000D_
  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum._x000D_
  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum._x000D_
  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum._x000D_

Sample random rows in dataframe

You could do this:

sample_data = data[sample(nrow(data), sample_size, replace = FALSE), ]

Event when window.location.href changes

You can't avoid polling, there isn't any event for href change.

Using intervals is quite light anyways if you don't go overboard. Checking the href every 50ms or so will not have any significant effect on performance if you're worried about that.

Angular 1 - get current URL parameters

In your route configuration you typically define a route like,


You can then either get the route in the resolve object by using $route.current.params or in a controller, $routeParams. In either case the parameters is extracted using the mapping of the route, so param1 can be accessed by $routeParams.param1 in the controller.

Edit: Also note that the mapping has to be exact


Will only match a single parameter.


Will only match two parameters.

This is a bit different then most dynamic server side routes. For example NodeJS (Express) route mapping where you can supply only a single route with X number of parameters.

How to use ConfigurationManager

Okay, it took me a while to see this, but there's no way this compiles:

return String.(ConfigurationManager.AppSettings[paramName]);

You're not even calling a method on the String type. Just do this:

return ConfigurationManager.AppSettings[paramName];

The AppSettings KeyValuePair already returns a string. If the name doesn't exist, it will return null.

Based on your edit you have not yet added a Reference to the System.Configuration assembly for the project you're working in.

In Excel, sum all values in one column in each row where another column is a specific value

You could do this using SUMIF. This allows you to SUM a value in a cell IF a value in another cell meets the specified criteria. Here's an example:

 -   A         B
 1   100       YES
 2   100       YES
 3   100       NO

Using the formula: =SUMIF(B1:B3, "YES", A1:A3), you will get the result of 200.

Here's a screenshot of a working example I just did in Excel:

Excel SUMIF Example

PHP shell_exec() vs exec()

Here are the differences. Note the newlines at the end.

> shell_exec('date')
string(29) "Wed Mar  6 14:18:08 PST 2013\n"
> exec('date')
string(28) "Wed Mar  6 14:18:12 PST 2013"

> shell_exec('whoami')
string(9) "mark\n"
> exec('whoami')
string(8) "mark"

> shell_exec('ifconfig')
string(1244) "eth0      Link encap:Ethernet  HWaddr 10:bf:44:44:22:33  \n          inet addr:  Bcast:  Mask:\n          inet6 addr: fe80::12bf:ffff:eeee:2222/64 Scope:Link\n          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1\n          RX packets:16264200 errors:0 dropped:1 overruns:0 frame:0\n          TX packets:7205647 errors:0 dropped:0 overruns:0 carrier:0\n          collisions:0 txqueuelen:1000 \n          RX bytes:13151177627 (13.1 GB)  TX bytes:2779457335 (2.7 GB)\n"...
> exec('ifconfig')
string(0) ""

Note that use of the backtick operator is identical to shell_exec().

Update: I really should explain that last one. Looking at this answer years later even I don't know why that came out blank! Daniel explains it above -- it's because exec only returns the last line, and ifconfig's last line happens to be blank.

Should I use <i> tag for icons instead of <span>?

My guess: Because Twitter sees the need to support legacy browsers, otherwise they would be using the :before / :after pseudo-elements.

Legacy browsers don't support those pseudo-elements I mentioned, so they need to use an actual HTML element for the icons, and since icons don't have an 'exclusive' tag, they just went with the <i> tag, and all browsers support that tag.

They could've certainly used a <span>, just like you are (which is TOTALLY fine), but probably for the reason I mentioned above plus the ones mentioned by Quentin, is also why Bootstrap is using the <i> tag.

It's a bad practice when you use extra markup for styling reasons, that's why pseudo-elements were invented, to separate content from style... but when you see the need to support legacy browsers, sometimes you're forced to do these kind of things.

PS. The fact that icons start with an 'i' and that there's an <i> tag, is completely coincidental.

How to pass multiple arguments in processStartInfo?

It is purely a string:

startInfo.Arguments = "-sk server -sky exchange -pe -n CN=localhost -ir LocalMachine -is Root -ic MyCA.cer -sr LocalMachine -ss My MyAdHocTestCert.cer"

Of course, when arguments contain whitespaces you'll have to escape them using \" \", like:

"... -ss \"My MyAdHocTestCert.cer\""

See MSDN for this.

How to zip a whole folder using PHP

Why not Try EFS PhP-ZiP MultiVolume Script ... I zipped and transferred hundreds of gigs and millions of files ... ssh is needed to effectively create archives.

But i belive that resulting files can be used with exec directly from php:

exec('zip -r backup-2013-03-30_0 . -i@backup-2013-03-30_0.txt');

I do not know if it works. I have not tried ...

"the secret" is that the execution time for archiving should not exceed the time allowed for execution of PHP code.

How do I set up a simple delegate to communicate between two view controllers?

Following solution is very basic and simple approach to send data from VC2 to VC1 using delegate .

PS: This solution is made in Xcode 9.X and Swift 4

Declared a protocol and created a delegate var into ViewControllerB

    import UIKit

    //Declare the Protocol into your SecondVC
    protocol DataDelegate {
        func sendData(data : String)

    class ViewControllerB : UIViewController {

    //Declare the delegate property in your SecondVC
        var delegate : DataDelegate?
        var data : String = "Send data to ViewControllerA."
        override func viewDidLoad() {

        @IBAction func btnSendDataPushed(_ sender: UIButton) {
                // Call the delegate method from SecondVC
                dismiss(animated: true, completion: nil)

ViewControllerA confirms the protocol and expected to receive data via delegate method sendData

    import UIKit
        // Conform the  DataDelegate protocol in ViewControllerA
        class ViewControllerA : UIViewController , DataDelegate {
        @IBOutlet weak var dataLabel: UILabel!

        override func viewDidLoad() {

        @IBAction func presentToChild(_ sender: UIButton) {
            let childVC =  UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier:"ViewControllerB") as! ViewControllerB
            //Registered delegate
            childVC.delegate = self
            self.present(childVC, animated: true, completion: nil)

        // Implement the delegate method in ViewControllerA
        func sendData(data : String) {
            if data != "" {
                self.dataLabel.text = data

What is difference between sleep() method and yield() method of multi threading?

Yield(): method will stop the currently executing thread and give a chance to another thread of same priority which are waiting in queue. If thier is no thread then current thread will continue to execute. CPU will never be in ideal state.

Sleep(): method will stop the thread for particular time (time will be given in milisecond). If this is single thread which is running then CPU will be in ideal state at that period of time.

Both are static menthod.

What is the difference between ManualResetEvent and AutoResetEvent in .NET?

AutoResetEvent maintains a boolean variable in memory. If the boolean variable is false then it blocks the thread and if the boolean variable is true it unblocks the thread.

When we instantiate an AutoResetEvent object, we pass the default value of boolean value in the constructor. Below is the syntax of instantiate an AutoResetEvent object.

AutoResetEvent autoResetEvent = new AutoResetEvent(false);

WaitOne method

This method blocks the current thread and wait for the signal by other thread. WaitOne method puts the current thread into a Sleep thread state. WaitOne method returns true if it receives the signal else returns false.


Second overload of WaitOne method wait for the specified number of seconds. If it does not get any signal thread continues its work.

static void ThreadMethod()

    Console.WriteLine("Thread got signal");

We called WaitOne method by passing the 2 seconds as arguments. In the while loop, it wait for the signal for 2 seconds then it continues its work. When the thread got the signal WaitOne returns true and exits the loop and print the "Thread got signal".

Set method

AutoResetEvent Set method sent the signal to the waiting thread to proceed its work. Below is the syntax of calling Set method.


ManualResetEvent maintains a boolean variable in memory. When the boolean variable is false then it blocks all threads and when the boolean variable is true it unblocks all threads.

When we instantiate a ManualResetEvent, we initialize it with default boolean value.

ManualResetEvent manualResetEvent = new ManualResetEvent(false);

In the above code, we initialize the ManualResetEvent with false value, that means all the threads which calls the WaitOne method will block until some thread calls the Set() method.

If we initialize ManualResetEvent with true value, all the threads which calls the WaitOne method will not block and free to proceed further.

WaitOne Method

This method blocks the current thread and wait for the signal by other thread. It returns true if its receives a signal else returns false.

Below is the syntax of calling WaitOne method.


In the second overload of WaitOne method, we can specify the time interval till the current thread wait for the signal. If within time internal, it does not receives a signal it returns false and goes into the next line of method.

Below is the syntax of calling WaitOne method with time interval.

bool isSignalled = manualResetEvent.WaitOne(TimeSpan.FromSeconds(5));

We have specify 5 seconds into the WaitOne method. If the manualResetEvent object does not receives a signal between 5 seconds, it set the isSignalled variable to false.

Set Method

This method is used for sending the signal to all waiting threads. Set() Method set the ManualResetEvent object boolean variable to true. All the waiting threads are unblocked and proceed further.

Below is the syntax of calling Set() method.


Reset Method

Once we call the Set() method on the ManualResetEvent object, its boolean remains true. To reset the value we can use Reset() method. Reset method change the boolean value to false.

Below is the syntax of calling Reset method.


We must immediately call Reset method after calling Set method if we want to send signal to threads multiple times.

Showing Difference between two datetime values in hours

Here is another example of subtracting two dates in C# ...

if ( DateTime.Now.Subtract(Convert.ToDateTime(objDateValueFromDatabase.CreatedOn)).TotalHours > 24 ) 

Understanding slice notation

Explain Python's slice notation

In short, the colons (:) in subscript notation (subscriptable[subscriptarg]) make slice notation - which has the optional arguments, start, stop, step:


Python slicing is a computationally fast way to methodically access parts of your data. In my opinion, to be even an intermediate Python programmer, it's one aspect of the language that it is necessary to be familiar with.

Important Definitions

To begin with, let's define a few terms:

start: the beginning index of the slice, it will include the element at this index unless it is the same as stop, defaults to 0, i.e. the first index. If it's negative, it means to start n items from the end.

stop: the ending index of the slice, it does not include the element at this index, defaults to length of the sequence being sliced, that is, up to and including the end.

step: the amount by which the index increases, defaults to 1. If it's negative, you're slicing over the iterable in reverse.

How Indexing Works

You can make any of these positive or negative numbers. The meaning of the positive numbers is straightforward, but for negative numbers, just like indexes in Python, you count backwards from the end for the start and stop, and for the step, you simply decrement your index. This example is from the documentation's tutorial, but I've modified it slightly to indicate which item in a sequence each index references:

 | P | y | t | h | o | n |
   0   1   2   3   4   5 
  -6  -5  -4  -3  -2  -1

How Slicing Works

To use slice notation with a sequence that supports it, you must include at least one colon in the square brackets that follow the sequence (which actually implement the __getitem__ method of the sequence, according to the Python data model.)

Slice notation works like this:


And recall that there are defaults for start, stop, and step, so to access the defaults, simply leave out the argument.

Slice notation to get the last nine elements from a list (or any other sequence that supports it, like a string) would look like this:


When I see this, I read the part in the brackets as "9th from the end, to the end." (Actually, I abbreviate it mentally as "-9, on")


The full notation is


and to substitute the defaults (actually when step is negative, stop's default is -len(my_list) - 1, so None for stop really just means it goes to whichever end step takes it to):


The colon, :, is what tells Python you're giving it a slice and not a regular index. That's why the idiomatic way of making a shallow copy of lists in Python 2 is

list_copy = sequence[:]

And clearing them is with:

del my_list[:]

(Python 3 gets a list.copy and list.clear method.)

When step is negative, the defaults for start and stop change

By default, when the step argument is empty (or None), it is assigned to +1.

But you can pass in a negative integer, and the list (or most other standard slicables) will be sliced from the end to the beginning.

Thus a negative slice will change the defaults for start and stop!

Confirming this in the source

I like to encourage users to read the source as well as the documentation. The source code for slice objects and this logic is found here. First we determine if step is negative:

 step_is_negative = step_sign < 0;

If so, the lower bound is -1 meaning we slice all the way up to and including the beginning, and the upper bound is the length minus 1, meaning we start at the end. (Note that the semantics of this -1 is different from a -1 that users may pass indexes in Python indicating the last item.)

if (step_is_negative) {
    lower = PyLong_FromLong(-1L);
    if (lower == NULL)
        goto error;

    upper = PyNumber_Add(length, lower);
    if (upper == NULL)
        goto error;

Otherwise step is positive, and the lower bound will be zero and the upper bound (which we go up to but not including) the length of the sliced list.

else {
    lower = _PyLong_Zero;
    upper = length;

Then, we may need to apply the defaults for start and stop - the default then for start is calculated as the upper bound when step is negative:

if (self->start == Py_None) {
    start = step_is_negative ? upper : lower;

and stop, the lower bound:

if (self->stop == Py_None) {
    stop = step_is_negative ? lower : upper;

Give your slices a descriptive name!

You may find it useful to separate forming the slice from passing it to the list.__getitem__ method (that's what the square brackets do). Even if you're not new to it, it keeps your code more readable so that others that may have to read your code can more readily understand what you're doing.

However, you can't just assign some integers separated by colons to a variable. You need to use the slice object:

last_nine_slice = slice(-9, None)

The second argument, None, is required, so that the first argument is interpreted as the start argument otherwise it would be the stop argument.

You can then pass the slice object to your sequence:

>>> list(range(100))[last_nine_slice]
[91, 92, 93, 94, 95, 96, 97, 98, 99]

It's interesting that ranges also take slices:

>>> range(100)[last_nine_slice]
range(91, 100)

Memory Considerations:

Since slices of Python lists create new objects in memory, another important function to be aware of is itertools.islice. Typically you'll want to iterate over a slice, not just have it created statically in memory. islice is perfect for this. A caveat, it doesn't support negative arguments to start, stop, or step, so if that's an issue you may need to calculate indices or reverse the iterable in advance.

length = 100
last_nine_iter = itertools.islice(list(range(length)), length-9, None, 1)
list_last_nine = list(last_nine_iter)

and now:

>>> list_last_nine
[91, 92, 93, 94, 95, 96, 97, 98, 99]

The fact that list slices make a copy is a feature of lists themselves. If you're slicing advanced objects like a Pandas DataFrame, it may return a view on the original, and not a copy.

Variable not accessible when initialized outside function

A global variable would be best expressed in an external JavaScript file:

var system_status;

Make sure that this has not been used anywhere else. Then to access the variable on your page, just reference it as such. Say, for example, you wanted to fill in the results on a textbox,

document.getElementById("textbox1").value = system_status;

To ensure that the object exists, use the document ready feature of jQuery.


$(function() {
    $("#textbox1")[0].value = system_status;

How do I install Eclipse Marketplace in Eclipse Classic?

Go to Help=>install new software=>workwith choice kEPLER and

search in the below "type filter text" --------------market,

  1. Select and expand general purpose tools and find MPC Marketplace Client
  2. Restart After installed..

No 'Access-Control-Allow-Origin' header in Angular 2 app

You can read more about that from here:

Your resource methods won't get hit, so their headers will never get set. The reason is that there is what's called a preflight request before the actual request, which is an OPTIONS request. So the error comes from the fact that the preflight request doesn't produce the necessary headers. check that you will need to add following in your .htaccess file:

Header set Access-Control-Allow-Origin "*"

Using ffmpeg to encode a high quality video

A couple of things:

  • You need to set the video bitrate. I have never used minrate and maxrate so I don't know how exactly they work, but by setting the bitrate using the -b switch, I am able to get high quality video. You need to come up with a bitrate that offers a good tradeoff between compression and video quality. You may have to experiment with this because it all depends on the frame size, frame rate and the amount of motion in the content of your video. Keep in mind that DVD tends to be around 4-5 Mbit/s on average for 720x480, so I usually start from there and decide whether I need more or less and then just experiment. For example, you could add -b 5000k to the command line to get more or less DVD video bitrate.

  • You need to specify a video codec. If you don't, ffmpeg will default to MPEG-1 which is quite old and does not provide near the amount of compression as MPEG-4 or H.264. If your ffmpeg version is built with libx264 support, you can specify -vcodec libx264 as part of the command line. Otherwise -vcodec mpeg4 will also do a better job than MPEG-1, but not as well as x264.

  • There are a lot of other advanced options that will help you squeeze out the best quality at the lowest bitrates. Take a look here for some examples.

VBA copy cells value and format

Instead of setting the value directly you can try using copy/paste, so instead of:

Worksheets(2).Cells(a, 15) = Worksheets(1).Cells(i, 3).Value

Try this:

Worksheets(1).Cells(i, 3).Copy
Worksheets(2).Cells(a, 15).PasteSpecial Paste:=xlPasteFormats
Worksheets(2).Cells(a, 15).PasteSpecial Paste:=xlPasteValues

To just set the font to bold you can keep your existing assignment and add this:

If Worksheets(1).Cells(i, 3).Font.Bold = True Then
  Worksheets(2).Cells(a, 15).Font.Bold = True
End If

Is there a way to automatically build the package.json file for Node.js projects

First off, run

npm init

...will ask you a few questions (read this first) about your project/package and then generate a package.json file for you.

Then, once you have a package.json file, use

npm install <pkg> --save


npm install <pkg> --save-dev install a dependency and automatically append it to your package.json's dependencies list.

(Note: You may need to manually tweak the version ranges for your dependencies.)

org.hibernate.MappingException: Unknown entity: annotations.Users

Instead of using, to create sessionfactory object, you should use this:

SessionFactory sessionFactory=new AnnotationConfiguration().configure().buildSessionFactory();

Because in order to avoid the exception, you'll have to declare the class object in file as configuration.addAnnotatedClass(Student_Info.class); which looks dumb because we have provided the entry already in hibernate.cfg.xml file.

To use the AnnotationConfiguration class you'll have to add a jar to your project build path: Read error: ssl=0x9524b800: I/O error during system call, Connection reset by peer

Another possible cause for this error message is if the HTTP Method is blocked by the server or load balancer.

It seems to be standard security practice to block unused HTTP Methods. We ran into this because HEAD was being blocked by the load balancer (but, oddly, not all of the load balanced servers, which caused it to fail only some of the time). I was able to test that the request itself worked fine by temporarily changing it to use the GET method.

The error code on iOS was: Error requesting App Code: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."

Center a button in a Linear layout

Did you try this?

  <TableLayout xmlns:android=""
android:id="@+id/mainlayout" android:orientation="vertical"
android:layout_width="fill_parent" android:layout_height="fill_parent">
    android:apiKey="apikey" />


R - argument is of length zero in if statement

The simplest solution to the problem is to change your for loop statement :

Instead of using

      for (i in **0**:n))


      for (i in **1**:n))

PHP: check if any posted vars are empty - form: all fields required

I use my own custom function...

public function areNull() {
    if (func_num_args() == 0) return false;
    $arguments = func_get_args();
    foreach ($arguments as $argument):
        if (is_null($argument)) return true;
    return false;
$var = areNull("username", "password", "etc");

I'm sure it can easily be changed for you scenario. Basically it returns true if any of the values are NULL, so you could change it to empty or whatever.

python requests get cookies

Alternatively, you can use requests.Session and observe cookies before and after a request:

>>> import requests
>>> session = requests.Session()
>>> print(session.cookies.get_dict())
>>> response = session.get('')
>>> print(session.cookies.get_dict())
{'PREF': 'ID=5514c728c9215a9a:FF=0:TM=1406958091:LM=1406958091:S=KfAG0U9jYhrB0XNf', 'NID': '67=TVMYiq2wLMNvJi5SiaONeIQVNqxSc2RAwVrCnuYgTQYAHIZAGESHHPL0xsyM9EMpluLDQgaj3db_V37NjvshV-eoQdA8u43M8UwHMqZdL-S2gjho8j0-Fe1XuH5wYr9v'}

How to convert an int value to string in Go?

In this case both strconv and fmt.Sprintf do the same job but using the strconv package's Itoa function is the best choice, because fmt.Sprintf allocate one more object during conversion.

check the nenchmark result of both check the benchmark here:

see for example.

How can one see the structure of a table in SQLite?

You can query sqlite_master

SELECT sql FROM sqlite_master WHERE name='foo';

which will return a create table SQL statement, for example:

$ sqlite3 mydb.sqlite
sqlite> create table foo (id int primary key, name varchar(10));
sqlite> select sql from sqlite_master where name='foo';
CREATE TABLE foo (id int primary key, name varchar(10))

sqlite> .schema foo
CREATE TABLE foo (id int primary key, name varchar(10));

sqlite> pragma table_info(foo)

sendKeys() in Selenium web driver

Try using Robot class in java for pressing TAB key. Use the below code.

driver.findElement(By.xpath("//label[text()='User Name:']/following::div/input")).sendKeys("UserName");

Robot robot = new Robot();

How to check SQL Server version

Here is what i have done to find the version Here is what i have done to find the version: just write SELECT @@version and it will give you the version.

How to get substring of NSString?

Use this also

NSString *ChkStr = [MyString substringWithRange:NSMakeRange(5, 26)];

Note - Your NSMakeRange(start, end) should be NSMakeRange(start, end- start);

What does asterisk * mean in Python?

All of the above answers were perfectly clear and complete, but just for the record I'd like to confirm that the meaning of * and ** in python has absolutely no similarity with the meaning of similar-looking operators in C.

They are called the argument-unpacking and keyword-argument-unpacking operators.

What is the difference between HTTP_HOST and SERVER_NAME in PHP?

As I mentioned in this answer, if the server runs on a port other than 80 (as might be common on a development/intranet machine) then HTTP_HOST contains the port, while SERVER_NAME does not.

$_SERVER['HTTP_HOST'] == 'localhost:8080'
$_SERVER['SERVER_NAME'] == 'localhost'

(At least that's what I've noticed in Apache port-based virtualhosts)

Note that HTTP_HOST does not contain :443 when running on HTTPS (unless you're running on a non-standard port, which I haven't tested).

As others have noted, the two also differ when using IPv6:

$_SERVER['HTTP_HOST'] == '[::1]'
$_SERVER['SERVER_NAME'] == '::1'

Scroll to the top of the page after render in react.js

Using Hooks in functional components, assuming the component updates when theres an update in the result props

import React, { useEffect } from 'react';

export const scrollTop = ({result}) => {
  useEffect(() => {
    window.scrollTo(0, 0);
  }, [result])

Alternative for frames in html5 using iframes

While I agree with everyone else, if you are dead set on using frames anyway, you can just do index.html in XHTML and then do the contents of the frames in HTML5.

Sort dataGridView columns in C# ? (Windows Form)

This one is simplier :)

dataview dataview1; 
this.dataview1= dataset.tables[0].defaultview;
this.dataview1.sort = "[ColumnName] ASC, [ColumnName] DESC";
this.datagridview.datasource = dataview1;

Slicing a dictionary

You should be iterating over the tuple and checking if the key is in the dict not the other way around, if you don't check if the key exists and it is not in the dict you are going to get a key error:

print({k:d[k] for k in l if k in d})

Some timings:

 {k:d[k] for k in set(d).intersection(l)}

In [22]: %%timeit                        
l = xrange(100000)
{k:d[k] for k in l}
100 loops, best of 3: 11.5 ms per loop

In [23]: %%timeit                        
l = xrange(100000)
{k:d[k] for k in set(d).intersection(l)}
10 loops, best of 3: 20.4 ms per loop

In [24]: %%timeit                        
l = xrange(100000)
l = set(l)                              
{key: d[key] for key in d.viewkeys() & l}
10 loops, best of 3: 24.7 ms per

In [25]: %%timeit                        

l = xrange(100000)
{k:d[k] for k in l if k in d}
100 loops, best of 3: 17.9 ms per loop

I don't see how {k:d[k] for k in l} is not readable or elegant and if all elements are in d then it is pretty efficient.

In oracle, how do I change my session to display UTF8?

The character set is part of the locale, which is determined by the value of NLS_LANG. As the documentation makes clear this is an operating system variable:

NLS_LANG is set as an environment variable on UNIX platforms. NLS_LANG is set in the registry on Windows platforms.

Now we can use ALTER SESSION to change the values for a couple of locale elements, NLS_LANGUAGE and NLS_TERRITORY. But not, alas, the character set. The reason for this discrepancy is - I think - that the language and territory simply effect how Oracle interprets the stored data, e.g. whether to display a comma or a period when displaying a large number. Wheareas the character set is concerned with how the client application renders the displayed data. This information is picked up by the client application at startup time, and cannot be changed from within.

Is there a way that I can check if a data attribute exists?

Wrong answer - see EDIT at the end

Let me build on Alex's answer.

To prevent the creation of a data object if it doesn't exists, I would better do:

$.fn.hasData = function(key) {
    var $this = $(this);
    return $.hasData($this) && typeof $ !== 'undefined';

Then, where $this has no data object created, $.hasData returns false and it will not execute $

EDIT: function $.hasData(element) works only if the data was set using $.data(element, key, value), not, value). Due to that, my answer is not correct.

Windows batch: call more than one command in a FOR loop?

SilverSkin and Anders are both correct. You can use parentheses to execute multiple commands. However, you have to make sure that the commands themselves (and their parameters) do not contain parentheses. cmd greedily searches for the first closing parenthesis, instead of handling nested sets of parentheses gracefully. This may cause the rest of the command line to fail to parse, or it may cause some of the parentheses to get passed to the commands (e.g. DEL myfile.txt)).

A workaround for this is to split the body of the loop into a separate function. Note that you probably need to jump around the function body to avoid "falling through" into it.

FOR /r %%X IN (*.txt) DO CALL :loopbody %%X
REM Don't "fall through" to :loopbody.

DEL %1

How to use sha256 in php5.3.0

First of all, sha256 is a hashing algorithm, not a type of encryption. An encryption would require having a way to decrypt the information back to its original value (collisions aside).

Looking at your code, it seems it should work if you are providing the correct parameter.

  • Try using a literal string in your code first, and verify its validity instead of using the $_POST[] variable

  • Try moving the comparison from the database query to the code (get the hash for the given user and compare to the hash you have just calculated)

But most importantly before deploying this in any kind of public fashion, please remember to sanitize your inputs. Don't allow arbitrary SQL to be insert into the queries. The best idea here would be to use parameterized queries.

regex to match a single character that is anything but a space

The following should suffice:

[^ ]

If you want to expand that to anything but white-space (line breaks, tabs, spaces, hard spaces):



\S  # Note this is a CAPITAL 'S'!

Junit - run set up method once

JUnit 5 now has a @BeforeAll annotation:

Denotes that the annotated method should be executed before all @Test methods in the current class or class hierarchy; analogous to JUnit 4’s @BeforeClass. Such methods must be static.

The lifecycle annotations of JUnit 5 seem to have finally gotten it right! You can guess which annotations available without even looking (e.g. @BeforeEach @AfterAll)

What does "Git push non-fast-forward updates were rejected" mean?

you might want to use force with push operation in this case

git push origin master --force

How to disable Paste (Ctrl+V) with jQuery?

I tried this in my Angular project and it worked fine without jQuery.

<input type='text' ng-paste='preventPaste($event)'>

And in script part:

$scope.preventPaste = function(e){
   return false;

In non angular project, use 'onPaste' instead of 'ng-paste' and 'event' instesd of '$event'.

How do you round a double in Dart to a given degree of precision AFTER the decimal point?

I think the accepted answer is not the perfect solution because it converts to string.

If you don't wanna convert to string and back to a double use double.toPrecision(decimalNumber) from GetX package.

If you don't wanna use GetX just for this (I highly recommend GetX, it will change your life with flutter) you can copy and paste this.

import 'dart:math';

extension Precision on double {
  double toPrecision(int fractionDigits) {
    var mod = pow(10, fractionDigits.toDouble()).toDouble();
    return ((this * mod).round().toDouble() / mod);

Wrapping a react-router Link in an html button

For anyone looking for a solution using React 16.8+ (hooks) and React Router 5:

You can change the route using a button with the following code:

<button onClick={() => props.history.push("path")}>

React Router provides some props to your components, including the push() function on history which works pretty much like the < Link to='path' > element.

You don't need to wrap your components with the Higher Order Component "withRouter" to get access to those props.

How to Deep clone in javascript

This is the deep cloning method I use, I think it Great, hope you make suggestions

function deepClone (obj) {
    var _out = new obj.constructor;

    var getType = function (n) {
        return, -1);

    for (var _key in obj) {
        if (obj.hasOwnProperty(_key)) {
            _out[_key] = getType(obj[_key]) === 'Object' || getType(obj[_key]) === 'Array' ? deepClone(obj[_key]) : obj[_key];
    return _out;

Viewing unpushed Git commits

This worked better for me:

git log --oneline @{upstream}..


git log --oneline origin/(remotebranch)..

Batch command date and time in file name

From the answer above, I have made a ready-to-use function.

Validated with french local settings.

:::::::: PROGRAM ::::::::::

call:genname "my file 1.txt"
echo "%newname%"
call:genname "my file 2.doc"
echo "%newname%"

:::::::: FUNCTIONS :::::::::

    set d1=%date:~-4,4%
    set d2=%date:~-10,2%
    set d3=%date:~-7,2%
    set t1=%time:~0,2%
    ::if "%t1:~0,1%" equ " " set t1=0%t1:~1,1%
    set t1=%t1: =0%
    set t2=%time:~3,2%
    set t3=%time:~6,2%
    set filename=%~1
    set newname=%d1%%d2%%d3%_%t1%%t2%%t3%-%filename%

Setting DIV width and height in JavaScript

The properties you're using may not work in Firefox, Chrome, and other non-IE browsers. To make this work in all browsers, I also suggest adding the following:


For cross-compatibility, you will still need to use the property. Order may also matter. For instance, in my code, when setting style properties with JavaScript, I set the style attribute first, then I set the properties:

document.getElementById("mydiv").style.display = "block";
document.getElementById("mydiv").style.cursor = "hand";

Thus, the most cross-browser compatible example for you would be:


I also want to point out that a much easier method of managing styles is to use a CSS class selector and put your styles in external CSS files. Not only will your code be much more maintainable, but you'll actually make friends with your Web designers!


.wide {

.hide {

.narrow {

Now, I can easily just add and remove a class attribute, one single property, instead of calling multiple properties. In addition, when your Web designer wants to change the definition of what it means to be wide, he or she does not need to go poking around in your beautifully maintained JavaScript code. Your JavaScript code remains untouched, yet the theme of your application can be easily customized.

This technique follows the rule of separating your content (HTML) from your behavior (JavaScript), and your presentation (CSS).

Case insensitive access for generic dictionary

For you LINQers out there that never use a regular dictionary constructor

myCollection.ToDictionary(x => x.PartNumber, x => x.PartDescription, StringComparer.OrdinalIgnoreCase)

smooth scroll to top

Came up with this solution:

function scrollToTop() {
let currentOffset = window.pageYOffset;
const arr = [];

for (let i = 100; i >= 0; i--) {
    arr.push(new Promise(res => {
            setTimeout(() => {
                    res(currentOffset * (i / 100));
                2 * (100 - i))

arr.reduce((acc, curr, index, arr) => {
    return acc.then((res) => {
        if (typeof res === 'number')
            window.scrollTo(0, res)
        return curr
}, Promise.resolve(currentOffset)).then(() => {
    window.scrollTo(0, 0)

How to remove the arrow from a select element in Firefox

A lot of Discussions Happening here & there but I don't see some proper solution for this problem. Finally Ended up by writing a small Jquery + CSS code for doing this HACK on IE & Firefox.

Calculate Element Width (SELECT Element) using Jquery. Add a Wrapper Around Select Element and Keep overflow hidden for this element. Make sure that Width of this wrapper is appox. 25px less as that of SELECT Element. This could be easily done with Jquery. So Now Our Icon is Gone..! and it is time for adding our image icon on SELECT element...!!! Just add few simple lines for adding background and you are all Done..!! Make sure to use overflow hidden for outer wrapper,

Here is a Sample of Code which was done for Drupal. However could be used for others also by removing few lines of code which is Drupal Specific.

 * Jquery Code for Removing Dropdown Arrow.
 * @by: North Web Studio
(function($) {
  Drupal.behaviors.nwsJS = {
    attach: function(context, settings) {
      $('.form-select').once('nws-arrow', function() {
        $wrap_width = $(this).outerWidth();
        $element_width = $wrap_width + 20;
        $(this).css('width', $element_width);
        $(this).wrap('<div class="nws-select"></div>');
        $(this).parent('.nws-select').css('width', $wrap_width);
 * CSS Code for Removing Dropdown Arrow.
 * @by: North Web Studio

.nws-select {
  border: 1px solid #ccc;
  overflow: hidden;
  background: url('../images/icon.png') no-repeat 95% 50%;
.nws-select .form-select {
  border: none;
  background: transparent;

Solution works on All Browsers IE, Chrome & Firefox No need of Adding fixed Widths Hacks Using CSS. It is all being handled Dynamically using JQuery.!

More Described at:-

Create a variable name with "paste" in R?

In my case function eval() works very good. Below I generate 10 variables and assign them 10 values.

lhs <- rnorm(10)
rhs <- paste("perf.a", 1:10, "<-", lhs, sep="")

How to make `setInterval` behave more in sync, or how to use `setTimeout` instead?

function appendTaskOnStack(task, ms, loop) {
    window.nextTaskAfter = (window.nextTaskAfter || 0) + ms;

    if (!loop) {
        setTimeout(function() {
            appendTaskOnStack(task, ms, true);
        }, window.nextTaskAfter);
    else {
        if (task) 
        window.nextTaskAfter = 0;

for (var n=0; n < 10; n++) {
    }, 100);

How to install python modules without root access?

Important question. The server I use (Ubuntu 12.04) had easy_install3 but not pip3. This is how I installed Pip and then other packages to my home folder

  1. Asked admin to install Ubuntu package python3-setuptools

  2. Installed pip

Like this:

 easy_install3 --prefix=$HOME/.local pip
 mkdir -p $HOME/.local/lib/python3.2/site-packages
 easy_install3 --prefix=$HOME/.local pip
  1. Add Pip (and other Python apps to path)

Like this:

echo PATH="$HOME/.local/bin:$PATH" > $HOME/.profile
  1. Install Python package

like this

pip3 install --user httpie

# test httpie package

jQuery attr('onclick')

Felix Kling's way will work, (actually beat me to the punch), but I was also going to suggest to use

$('#next').die().live('click', stopMoving);

this might be a better way to do it if you run into problems and strange behaviors when the element is clicked multiple times.

Mysql: Select all data between two dates

You can use as an alternate solution:

SELECT * FROM TABLE_NAME WHERE `date` >= '1-jan-2013' 
OR `date` <= '12-jan-2013'

What is an uber jar?

A self-contained, executable Java archive. In the case of WildFly Swarm uberjars, it is a single .jar file containing your application, the portions of WildFly required to support it, an internal Maven repository of dependencies, plus a shim to bootstrap it all. see this

Spring AMQP + RabbitMQ 3.3.5 ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN

To complete @cpu-100 answer,

in case you don't want to enable/use web interface, you can create a new credentials using command line like below and use it in your code to connect to RabbitMQ.

$ rabbitmqctl add_user YOUR_USERNAME YOUR_PASSWORD
$ rabbitmqctl set_user_tags YOUR_USERNAME administrator
$ rabbitmqctl set_permissions -p / YOUR_USERNAME ".*" ".*" ".*"

How to see JavaDoc in IntelliJ IDEA?

For me, it wasn't just getting the javadoc window to open, but also getting the complete javadoc to present. You may still get a sparse javadoc that is based solely on the method signature if you are importing libraries from a Maven repository and do not tell Idea to include the javadocs in the download. Be sure to tick the "JavaDocs" option in the "Download Library From Maven Repository" dialog, which can be found under Project Structure -> Projtect Settings -> Libraries.

Understanding the basics of Git and GitHub

  1. What is the difference between Git and GitHub?

    Git is a version control system; think of it as a series of snapshots (commits) of your code. You see a path of these snapshots, in which order they where created. You can make branches to experiment and come back to snapshots you took.

    GitHub, is a web-page on which you can publish your Git repositories and collaborate with other people.

  2. Is Git saving every repository locally (in the user's machine) and in GitHub?

    No, it's only local. You can decide to push (publish) some branches on GitHub.

  3. Can you use Git without GitHub? If yes, what would be the benefit for using GitHub?

    Yes, Git runs local if you don't use GitHub. An alternative to using GitHub could be running Git on files hosted on Dropbox, but GitHub is a more streamlined service as it was made especially for Git.

  4. How does Git compare to a backup system such as Time Machine?

    It's a different thing, Git lets you track changes and your development process. If you use Git with GitHub, it becomes effectively a backup. However usually you would not push all the time to GitHub, at which point you do not have a full backup if things go wrong. I use git in a folder that is synchronized with Dropbox.

  5. Is this a manual process, in other words if you don't commit you won't have a new version of the changes made?

    Yes, committing and pushing are both manual.

  6. If are not collaborating and you are already using a backup system why would you use Git?

    • If you encounter an error between commits you can use the command git diff to see the differences between the current code and the last working commit, helping you to locate your error.

    • You can also just go back to the last working commit.

    • If you want to try a change, but are not sure that it will work. You create a branch to test you code change. If it works fine, you merge it to the main branch. If it does not you just throw the branch away and go back to the main branch.

    • You did some debugging. Before you commit you always look at the changes from the last commit. You see your debug print statement that you forgot to delete.

Make sure you check

Sonar properties files

Do the build job on Jenkins first without Sonar configured. Then add Sonar, and run a build job again. Should fix the problem

Show row number in row header of a DataGridView

just enhancing above solution.. so header it self resize its width in order to accommodate lengthy string like 12345

private void advancedDataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
    var grid = sender as DataGridView;
    var rowIdx = (e.RowIndex + 1).ToString();

    var centerFormat = new StringFormat()
        // right alignment might actually make more sense for numbers
        Alignment = StringAlignment.Center,

        LineAlignment = StringAlignment.Center
    //get the size of the string
    Size textSize = TextRenderer.MeasureText(rowIdx, this.Font);
    //if header width lower then string width then resize
    if (grid.RowHeadersWidth < textSize.Width + 40)
        grid.RowHeadersWidth = textSize.Width + 40;
    var headerBounds = new Rectangle(e.RowBounds.Left, e.RowBounds.Top, grid.RowHeadersWidth, e.RowBounds.Height);
    e.Graphics.DrawString(rowIdx, this.Font, SystemBrushes.ControlText, headerBounds, centerFormat);

Show Current Location and Update Location in MKMapView in Swift

Swift 5.1

Get Current Location and Set on MKMapView

Import libraries:

import MapKit
import CoreLocation

set delegates:

CLLocationManagerDelegate , MKMapViewDelegate

Declare variable:

let locationManager = CLLocationManager()

Write this code on viewDidLoad():


if CLLocationManager.locationServicesEnabled() {
    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
mapView.delegate = self
mapView.mapType = .standard
mapView.isZoomEnabled = true
mapView.isScrollEnabled = true

if let coor = mapView.userLocation.location?.coordinate{
    mapView.setCenter(coor, animated: true)

Write delegate method for location:

func locationManager(_ manager: CLLocationManager, didUpdateLocations 
    locations: [CLLocation]) {
    let locValue:CLLocationCoordinate2D = manager.location!.coordinate

    mapView.mapType = MKMapType.standard

    let span = MKCoordinateSpan(latitudeDelta: 0.05, longitudeDelta: 0.05)
    let region = MKCoordinateRegion(center: locValue, span: span)
    mapView.setRegion(region, animated: true)

    let annotation = MKPointAnnotation()
    annotation.coordinate = locValue
    annotation.title = "You are Here"

Set permission in info.plist *

<string>This application requires location services to work</string>

<string>This application requires location services to work</string>

Detect network connection type on Android

Currently, only MOBILE and WIFI is supported. Take a look and human readable type function.

100% width in React Native Flexbox

First add Dimension component:

import { AppRegistry, Text, View,Dimensions } from 'react-native';

Second define Variables:

var height = Dimensions.get('window').height;
var width = Dimensions.get('window').width;

Third put it in your stylesheet:

textOutputView: {

Actually in this example I wanted to make responsive view and wanted to view only 0.25 of the screen view so I multiplied it with 0.25, if you wanted 100% of the screen don't multiply it with any thing like this:

textOutputView: {

What are good grep tools for Windows?

Well, beside the Windows port of the GNU grep at:

there's also Borland's grep (very similar to GNU one) available in the freeware Borland's Free C++ Compiler (it's a freeware with command line tools).

How do I run pip on python for windows?

First go to the pip documentation if not install before:

and follow the install pip which is first download from

Then run the following (which may require administrator access): python

Adding padding to a tkinter widget only on one side

The padding options padx and pady of the grid and pack methods can take a 2-tuple that represent the left/right and top/bottom padding.

Here's an example:

import tkinter as tk

class MyApp():
    def __init__(self):
        self.root = tk.Tk()
        l1 = tk.Label(self.root, text="Hello")
        l2 = tk.Label(self.root, text="World")
        l1.grid(row=0, column=0, padx=(100, 10))
        l2.grid(row=1, column=0, padx=(10, 100)) 

app = MyApp()

Printing variables in Python 3.4

Try the format syntax:

print ("{0}. {1} appears {2} times.".format(1, 'b', 3.1415))


1. b appears 3.1415 times.

The print function is called just like any other function, with parenthesis around all its arguments.

Couldn't process file resx due to its being in the Internet or Restricted zone or having the mark of the web on the file

I stumbled upon another possible reason of this error. If you use NTFS symbolic links in your project tree, and probably subst'ed drives, you may get this error even if they point to your local drive. If this is the case, try to avoid the situation when .resx files are reached via symlinks.

How to cancel/abort jQuery AJAX request?

The jquery ajax method returns a XMLHttpRequest object. You can use this object to cancel the request.

The XMLHttpRequest has a abort method, which cancels the request, but if the request has already been sent to the server then the server will process the request even if we abort the request but the client will not wait for/handle the response.

The xhr object also contains a readyState which contains the state of the request(UNSENT-0, OPENED-1, HEADERS_RECEIVED-2, LOADING-3 and DONE-4). we can use this to check whether the previous request was completed.

    var xhr;

    var fn = function(){
        if(xhr && xhr.readyState != 4){
        xhr = $.ajax({
            url: 'ajax/progress.ftl',
            success: function(data) {
                //do something

    var interval = setInterval(fn, 500);

javascript: calculate x% of a number

It may be a bit pedantic / redundant with its numeric casting, but here's a safe function to calculate percentage of a given number:

function getPerc(num, percent) {
    return Number(num) - ((Number(percent) / 100) * Number(num));

// Usage: getPerc(10000, 25);

Convert a space delimited string to list

states = "Alaska Alabama Arkansas American Samoa Arizona California Colorado"
states_list = states.split (' ')

How to put more than 1000 values into an Oracle IN clause

Instead of using IN clause, can you try using JOIN with the other table, which is fetching the id. that way we don't need to worry about limit. just a thought from my side.


Your setting is all right. Some web servers require to specify the media and static folder files specifically. For example in you have to go to the 'Web' section and add the url od the media folders and static folder. For example:

  URL                     Directory                
/static/            /home/Saidmamad/discoverthepamirs/static     
/accounts/static/   /home/Saidmamad/discoverthepamirs/accounts/static    
/media/            /home/Saidmamad/discoverthepamirs/discoverthepamirs/media    

I know that it is late, but just to help those who visit this link because of the same problem ;)

SQL statement to get column type

In my case I needed to get the data type for Dynamic SQL (Shudder!) anyway here is a function that I created that returns the full data type. For example instead of returning 'decimal' it would return DECIMAL(18,4): dbo.GetLiteralDataType

How to vertically center a container in Bootstrap?

The Flexible box way

Vertical alignment is now very simple by the use of Flexible box layout. Nowadays, this method is supported in a wide range of web browsers except Internet Explorer 8 & 9. Therefore we'd need to use some hacks/polyfills or different approaches for IE8/9.

In the following I'll show you how to do that in only 3 lines of text (regardless of old flexbox syntax).

Note: it's better to use an additional class instead of altering .jumbotron to achieve the vertical alignment. I'd use vertical-center class name for instance.

Example Here (A Mirror on jsbin).

<div class="jumbotron vertical-center"> <!-- 
                      ^--- Added class  -->
  <div class="container">
.vertical-center {
  min-height: 100%;  /* Fallback for browsers do NOT support vh unit */
  min-height: 100vh; /* These two lines are counted as one :-)       */

  display: flex;
  align-items: center;

Important notes (Considered in the demo):

  1. A percentage values of height or min-height properties is relative to the height of the parent element, therefore you should specify the height of the parent explicitly.

  2. Vendor prefixed / old flexbox syntax omitted in the posted snippet due to brevity, but exist in the online example.

  3. In some of old web browsers such as Firefox 9 (in which I've tested), the flex container - .vertical-center in this case - won't take the available space inside the parent, therefore we need to specify the width property like: width: 100%.

  4. Also in some of web browsers as mentioned above, the flex item - .container in this case - may not appear at the center horizontally. It seems the applied left/right margin of auto doesn't have any effect on the flex item.
    Therefore we need to align it by box-pack / justify-content.

For further details and/or vertical alignment of columns, you could refer to the topic below:

The traditional way for legacy web browsers

This is the old answer I wrote at the time I answered this question. This method has been discussed here and it's supposed to work in Internet Explorer 8 and 9 as well. I'll explain it in short:

In inline flow, an inline level element can be aligned vertically to the middle by vertical-align: middle declaration. Spec from W3C:

Align the vertical midpoint of the box with the baseline of the parent box plus half the x-height of the parent.

In cases that the parent - .vertical-center element in this case - has an explicit height, by any chance if we could have a child element having the exact same height of the parent, we would be able to move the baseline of the parent to the midpoint of the full-height child and surprisingly make our desired in-flow child - the .container - aligned to the center vertically.

Getting all together

That being said, we could create a full-height element within the .vertical-center by ::before or ::after pseudo elements and also change the default display type of it and the other child, the .container to inline-block.

Then use vertical-align: middle; to align the inline elements vertically.

Here you go:

<div class="jumbotron vertical-center">
  <div class="container">
.vertical-center {

  text-align: center;  /* align the inline(-block) elements horizontally */
  font: 0/0 a;         /* remove the gap between inline(-block) elements */

.vertical-center:before {    /* create a full-height inline block pseudo=element */
  content: " ";
  display: inline-block;
  vertical-align: middle;    /* vertical alignment of the inline element */
  height: 100%;

.vertical-center > .container {
  max-width: 100%;

  display: inline-block;
  vertical-align: middle;  /* vertical alignment of the inline element */
                           /* reset the font property */
  font: 16px/1 "Helvetica Neue", Helvetica, Arial, sans-serif;


Also, to prevent unexpected issues in extra small screens, you can reset the height of the pseudo-element to auto or 0 or change its display type to none if needed so:

@media (max-width: 768px) {
  .vertical-center:before {
    height: auto;
    /* Or */
    display: none;


And one more thing:

If there are footer/header sections around the container, it's better to position that elements properly (relative, absolute? up to you.) and add a higher z-index value (for assurance) to keep them always on the top of the others.

How do I create dynamic properties in C#?

I'm not sure what your reasons are, and even if you could pull it off somehow with Reflection Emit (I' not sure that you can), it doesn't sound like a good idea. What is probably a better idea is to have some kind of Dictionary and you can wrap access to the dictionary through methods in your class. That way you can store the data from the database in this dictionary, and then retrieve them using those methods.

How to use OKHTTP to make a post request?

 public static JSONObject doPostRequestWithSingleFile(String url,HashMap<String, String> data, File file,String fileParam) {

        try {
            final MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");

            RequestBody requestBody;
            MultipartBuilder mBuilder = new MultipartBuilder().type(MultipartBuilder.FORM);

            for (String key : data.keySet()) {
                String value = data.get(key);
                Utility.printLog("Key Values", key + "-----------------" + value);

                mBuilder.addFormDataPart(key, value);

            if(file!=null) {
                Log.e("File Name", file.getName() + "===========");
                if (file.exists()) {
                    mBuilder.addFormDataPart(fileParam, file.getName(), RequestBody.create(MEDIA_TYPE_PNG, file));
            requestBody =;
            Request request = new Request.Builder()

            OkHttpClient client = new OkHttpClient();
            Response response = client.newCall(request).execute();
            String result=response.body().string();
            return new JSONObject(result);

        } catch (UnknownHostException | UnsupportedEncodingException e) {
            Log.e(TAG, "Error: " + e.getLocalizedMessage());
            JSONObject jsonObject=new JSONObject();

            try {
            } catch (JSONException e1) {
        } catch (Exception e) {
            Log.e(TAG, "Other Error: " + e.getMessage());
            JSONObject jsonObject=new JSONObject();

            try {
            } catch (JSONException e1) {
        return null;
    public static JSONObject doGetRequest(HashMap<String, String> param,String url) {
        JSONObject result = null;
        String response;
        Set keys = param.keySet();

        int count = 0;
        for (Iterator i = keys.iterator(); i.hasNext(); ) {
            String key = (String);
            String value = (String) param.get(key);
            if (count == param.size()) {
                url += key + "=" + URLEncoder.encode(value);

            } else {

                url += key + "=" + URLEncoder.encode(value) + "&";

        try {
            url=  URLEncoder.encode(url, "utf-8");
        } catch (UnsupportedEncodingException e) {
        Log.e("URL", url);
        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
        Response responseClient = null;
        try {

            responseClient = client.newCall(request).execute();
            response = responseClient.body().string();
            result = new JSONObject(response);
            Log.e("response", response+"==============");
        } catch (Exception e) {
            JSONObject jsonObject=new JSONObject();

            try {
                return  jsonObject;
            } catch (JSONException e1) {

        return result;


How to delete mysql database through shell command

No need for mysqladmin:

just use mysql command line

mysql -u [username] -p[password] -e 'drop database db-name;'

This will send the drop command although I wouldn't pass the password this way as it'll be exposed to other users of the system via ps aux

Move view with keyboard using Swift

swift 3.0 insert in viewDidLoad(), this->



    view.addConstraintWithFormat(format: "H:|[v0]|", views:Your_messageInputConteinerView)

    view.addConstraintWithFormat(format: "V:[v0(48)]", views:Your_messageInputConteinerView)

NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardNotification(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardNotification(notification:)), name: .UIKeyboardWillHide, object: nil)

bottomConstraint = NSLayoutConstraint(item: Your_messageInputConteinerView, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1, constant: 0)



func handleKeyboardNotification(notification:Notification){

if let userInfo = notification.userInfo {

    if let keyBoardFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue{


        if bottomConstraint?.constant != CGFloat(0) {
                bottomConstraint?.constant = 0
     bottomConstraint?.constant = -keyBoardFrame.height
        self.view.frame.origin.y = -keyBoardFrame.height


How can I count the number of elements with same class?


The document.getElementsByClassName("classstringhere") method returns an array of all the elements with that class name, so .length gives you the amount of them.

What happened to the .pull-left and .pull-right classes in Bootstrap 4?

Update 2021, Bootstrap 5

In bootstrap 5 these classes have been renamed to .float-end and .float-start.



<div class="row">
    <div class="col-12">
       <button class="btn btn-primary float-end">Login</div>

Scroll to bottom of div?

If this is being done for scrolling to the bottom of chat window, do the following

The idea of scrolling to a particular div in the chat was the following

1) Each chat div consisting of Person, time and message is run in a for loop with class chatContentbox

2) querySelectorAll finds all such arrays. It could be 400 nodes (400 chats)

3) go to the last one

4) scrollIntoView()

let lastChatBox = document.querySelectorAll('.chatContentBox'); 
lastChatBox = lastChatBox[lastChatBox.length-1]; 

Get the Highlighted/Selected text

Use window.getSelection().toString().

You can

Visual Studio 2017 errors on standard headers

If anyone's still stuck on this, the easiest solution I found was to "Retarget Solution". In my case, the project was built of SDK 8.1, upgrading to VS2017 brought with it SDK

To retarget solution: Project->Retarget Solution->"Select whichever SDK you have installed"->OK

From there on you can simply build/debug your solution. Hope it helps

enter image description here

How to get a list of images on docker registry v2

Here's an example that lists all tags of all images on the registry. It handles a registry configured for HTTP Basic auth too.


# Get username:password from docker configuration. You could
# inject these some other way instead if you wanted.
CREDS=$(jq -r ".[\"auths\"][\"$THE_REGISTRY\"][\"auth\"]" .docker/config.json | base64 -d)

curl -s --user $CREDS https://$THE_REGISTRY/v2/_catalog | \
    jq -r '.["repositories"][]' | \
    xargs -I @REPO@ curl -s --user $CREDS https://$THE_REGISTRY/v2/@REPO@/tags/list | \
    jq -M '.["name"] + ":" + .["tags"][]'


  • extract username:password from .docker/config.json
  • make a https request to the registry to list all "repositories"
  • filter the json result to a flat list of repository names
  • for each repository name:
  • make a https request to the registry to list all "tags" for that "repository"
  • filter the stream of result json objects, printing "repository":"tag" pairs for each tag found in each repository

#pragma once vs include guards?

Atop explanation by Konrad Kleine above.

A brief summary:

  • when we use # pragma once it is much of the compiler responsibility, not to allow its inclusion more than once. Which means, after you mention the code-snippet in the file, it is no more your responsibility.

Now, compiler looks, for this code-snippet at the beginning of the file, and skips it from being included (if already included once). This definitely will reduce the compilation-time (on an average and in huge-system). However, in case of mocks/test environment, will make the test-cases implementation difficult, due to circular etc dependencies.

  • Now, when we use the #ifndef XYZ_H for the headers, it is more of the developers responsibility to maintain the dependency of headers. Which means, whenever due to some new header file, there is possibility of the circular dependency, compiler will just flag some "undefined .." error messages at compile time, and it is user to check the logical connection/flow of the entities and rectify the improper includes.

This definitely will add to the compilation time (as needs to rectified and re-run). Also, as it works on the basis of including the file, based on the "XYZ_H" defined-state, and still complains, if not able to get all the definitions.

Therefore, to avoid situations like this, we should use, as;

#pragma once
#ifndef XYZ_H
#define XYZ_H

i.e. the combination of both.

Returning anonymous type in C#

In C# 7 we can use tuples to accomplish this:

public List<(int SomeVariable, string AnotherVariable)> TheMethod(SomeParameter)
  using (MyDC TheDC = new MyDC())
     var TheQueryFromDB = (....
                       select new { SomeVariable = ....,
                                    AnotherVariable = ....}

      return TheQueryFromDB
                .Select(s => (
                     SomeVariable = s.SomeVariable, 
                     AnotherVariable = s.AnotherVariable))

You might need to install System.ValueTuple nuget package though.

How do I lock the orientation to portrait mode in a iPhone Web Application?

In coffee if anyone needs it.

    $(window).bind 'orientationchange', ->
        if window.orientation % 180 == 0
                "-webkit-transform-origin" : ''
                "-webkit-transform" : ''
            if window.orientation > 0
                    "-webkit-transform-origin" : "200px 190px"
                    "-webkit-transform" : "rotate(-90deg)"
                    "-webkit-transform-origin" : "280px 190px"
                    "-webkit-transform" : "rotate(90deg)"

Full Screen DialogFragment in Android

public void onCreate(Bundle savedInstanceState) {


How do I declare an array of undefined or no initial size?

Here's a sample program that reads stdin into a memory buffer that grows as needed. It's simple enough that it should give some insight in how you might handle this kind of thing. One thing that's would probably be done differently in a real program is how must the array grows in each allocation - I kept it small here to help keep things simpler if you wanted to step through in a debugger. A real program would probably use a much larger allocation increment (often, the allocation size is doubled, but if you're going to do that you should probably 'cap' the increment at some reasonable size - it might not make sense to double the allocation when you get into the hundreds of megabytes).

Also, I used indexed access to the buffer here as an example, but in a real program I probably wouldn't do that.

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

void fatal_error(void);

int main( int argc, char** argv)
    int buf_size = 0;
    int buf_used = 0;

    char* buf = NULL;
    char* tmp = NULL;    

    char c;
    int i = 0;

    while ((c = getchar()) != EOF) {
        if (buf_used == buf_size) {
             //need more space in the array

             buf_size += 20;
             tmp = realloc(buf, buf_size); // get a new larger array
             if (!tmp) fatal_error();

             buf = tmp;

        buf[buf_used] = c; // pointer can be indexed like an array

    puts("\n\n*** Dump of stdin ***\n");

    for (i = 0; i < buf_used; ++i) {


    return 0;

void fatal_error(void)
    fputs("fatal error - out of memory\n", stderr);

This example combined with examples in other answers should give you an idea of how this kind of thing is handled at a low level.


I'm currently working on such a statement and figured out another fact to notice: INSERT OR REPLACE will replace any values not supplied in the statement. For instance if your table contains a column "lastname" which you didn't supply a value for, INSERT OR REPLACE will nullify the "lastname" if possible (constraints allow it) or fail.

Angular pass callback function to child component as @Input similar to AngularJS way

Passing method with argument, using .bind inside template

  template: '<child [action]="foo.bind(this, 'someArgument')"></child>',
export class ParentComponent {
  public foo(someParameter: string){

export class ChildComponent{

  public action: Function; 


copy all files and folders from one drive to another drive using DOS (command prompt)

try this command, xcopy c:\ (file or directory path) F:\ /e. If you want more details refer this site [[]]

How to create json by JavaScript for loop?

Your question is pretty hard to decode, but I'll try taking a stab at it.

You say:

I want to create a json object having two fields uniqueIDofSelect and optionValue in javascript.

And then you say:

I need output like


Well, this example output doesn't have the field named uniqueIDofSelect, it only has optionValue.

Anyway, you are asking for array of objects...

Then in the comment to michaels answer you say:

It creates json object array. but I need only one json object.

So you don't want an array of objects?

What do you want then?

Please make up your mind.

How to get the selected value from RadioButtonList?

The ASPX code will look something like this:

 <asp:RadioButtonList ID="rblist1" runat="server">

    <asp:ListItem Text ="Item1" Value="1" />
    <asp:ListItem Text ="Item2" Value="2" />
    <asp:ListItem Text ="Item3" Value="3" />
    <asp:ListItem Text ="Item4" Value="4" />


    <asp:Button ID="btn1" runat="server" OnClick="Button1_Click" Text="select value" />

And the code behind:

protected void Button1_Click(object sender, EventArgs e)
            string selectedValue = rblist1.SelectedValue;

How can I parse a string with a comma thousand separator to a number?

Replace the comma with an empty string:

var x = parseFloat("2,299.00".replace(",",""))_x000D_

linux find regex

Note that -regex depends on whole path.

 -regex pattern
              File name matches regular expression pattern.  
              This is a match on the whole path, not a search.

You don't actually have to use -regex for what you are doing.

find . -iname "*[0-9]"

Why is the <center> tag deprecated in HTML?

Food for thought: what would a text-to-speech synthesizer do with <center>?

How to append one file to another in Linux from the shell?

Just for reference, using ddrescue provides an interruptible way of achieving the task if, for example, you have large files and the need to pause and then carry on at some later point:

ddrescue -o $(wc --bytes file1 | awk '{ print $1 }') file2 file1 logfile

The logfile is the important bit. You can interrupt the process with Ctrl-C and resume it by specifying the exact same command again and ddrescue will read logfile and resume from where it left off. The -o A flag tells ddrescue to start from byte A in the output file (file1). So wc --bytes file1 | awk '{ print $1 }' just extracts the size of file1 in bytes (you can just paste in the output from ls if you like).

As pointed out by ngks in the comments, the downside is that ddrescue will probably not be installed by default, so you will have to install it manually. The other complication is that there are two versions of ddrescue which might be in your repositories: see this askubuntu question for more info. The version you want is the GNU ddrescue, and on Debian-based systems is the package named gddrescue:

sudo apt install gddrescue

For other distros check your package management system for the GNU version of ddrescue.

Facebook login "given URL not allowed by application configuration"

You can set up a developer application and set the url to Make sure to map to localhost on your hosts file

Works for me

how do I use an enum value on a switch statement in C++

#include <iostream>
using namespace std;

int main() {

    enum level {EASY = 1, NORMAL, HARD};

    // Present menu
    int choice;
    cout << "Choose your level:\n\n";
    cout << "1 - Easy.\n";
    cout << "2 - Normal.\n";
    cout << "3 - Hard.\n\n";
    cout << "Choice --> ";
    cin >> choice;
    cout << endl;

    switch (choice) {
    case EASY:
        cout << "You chose Easy.\n";
    case NORMAL:
        cout << "You chose Normal.\n";
    case HARD:
        cout << "You chose Hard.\n";
        cout << "Invalid choice.\n";

    return 0;

How do I add all new files to SVN

This will add all unknown (except ignored) files under the specified directory tree:

svn add --force path/to/dir

This will add all unknown (except ignored) files in the current directory and below:

svn add --force .

jquery input select all on focus

This version works on ios and also fixes standard drag-to-select on windows chrome

var srcEvent = null;


    .mousedown(function (event) {
        srcEvent = event;

    .mouseup(function (event) {
        var delta = Math.abs(event.clientX - srcEvent.clientX) 
                  + Math.abs(event.clientY - srcEvent.clientY);

        var threshold = 2;
        if (delta <= threshold) {
                   try {
                        // ios likes this but windows-chrome does not on number fields
                        $(this)[0].selectionStart = 0;
                        $(this)[0].selectionEnd = 1000;
                    } catch (e) {
                        // windows-chrome likes this

PHP "pretty print" json_encode

Here's a function to pretty up your json: pretty_json

Is there a function in python to split a word into a list?

Abuse of the rules, same result: (x for x in 'Word to split')

Actually an iterator, not a list. But it's likely you won't really care.

Div height 100% and expands to fit content


A really cool way I've figured this out for a recent menu was setting the body to:

position: relative

and set your wrapper class like this:

#overlaywrapper {
    position: absolute;
    top: 0;
    width: 100%;
    height: 100%;
    background: #00000080;
    z-index: 100;

This means that you don't have to set position fixed and can still allow for scrolling. I've used this for overlaying menu's that are REALLY big.

groovy.lang.MissingPropertyException: No such property: jenkins for class: groovy.lang.Binding

As pointed out by @Jayan in another post, the solution was to do the following

import jenkins.model.*
jenkins = Jenkins.instance

Then I was able to do the rest of my scripting the way it was.

Java List.contains(Object with field value equal to x)

contains method uses equals internally. So you need to override the equals method for your class as per your need.

Btw this does not look syntatically correct:

new Object().setName("John")

"Error 1067: The process terminated unexpectedly" when trying to start MySQL

I've got the same problem, and what worked for me is in THIS OTHER ANSWER.

I didn't replicated it here because it is NOT A CORRECT THING TO DO.

Basically is a re-install being sure to delete everything very well and using 32 bit versions.

python date of the previous month

Simple, one liner:

import datetime as dt
previous_month = ( - dt.timedelta(days=1)).month

What's the quickest way to multiply multiple cells by another number?

Select Product from formula bar in your answer cell.

Select cells you want to multiply.

applying css to specific li class

You have specified different colors for the li elements but it is being overridden by the specified color in the a within the li. Remove color: #C1C1C1; style from a element and it should work.

How to initialize a static array?

If you are creating an array then there is no difference, however, the following is neater:

String[] suit = {

But, if you want to pass an array into a method you have to call it like this:

myMethod(new String[] {"spades", "hearts"});

myMethod({"spades", "hearts"}); //won't compile!

Running command line silently with VbScript and getting output?

I have taken this and various other comments and created a bit more advanced function for running an application and getting the output.

Example to Call Function: Will output the DIR list of C:\ for Directories only. The output will be returned to the variable CommandResults as well as remain in C:\OUTPUT.TXT.

CommandResults = vFn_Sys_Run_CommandOutput("CMD.EXE /C DIR C:\ /AD",1,1,"C:\OUTPUT.TXT",0,1)


Function vFn_Sys_Run_CommandOutput (Command, Wait, Show, OutToFile, DeleteOutput, NoQuotes)
'Run Command similar to the command prompt, for Wait use 1 or 0. Output returned and
'stored in a file.
'Command = The command line instruction you wish to run.
'Wait = 1/0; 1 will wait for the command to finish before continuing.
'Show = 1/0; 1 will show for the command window.
'OutToFile = The file you wish to have the output recorded to.
'DeleteOutput = 1/0; 1 deletes the output file. Output is still returned to variable.
'NoQuotes = 1/0; 1 will skip wrapping the command with quotes, some commands wont work
'                if you wrap them in quotes.
  On Error Resume Next
  'On Error Goto 0
    Set f_objShell = CreateObject("Wscript.Shell")
    Set f_objFso = CreateObject("Scripting.FileSystemObject")
    Const ForReading = 1, ForWriting = 2, ForAppending = 8
        If OutToFile = "" Then OutToFile = "TEMP.TXT"
        tCommand = Command
        If Left(Command,1)<>"""" And NoQuotes <> 1 Then tCommand = """" & Command & """"
        tOutToFile = OutToFile
        If Left(OutToFile,1)<>"""" Then tOutToFile = """" & OutToFile & """"
        If Wait = 1 Then tWait = True
        If Wait <> 1 Then tWait = False
        If Show = 1 Then tShow = 1
        If Show <> 1 Then tShow = 0
        f_objShell.Run tCommand & ">" & tOutToFile, tShow, tWait
        Set f_objFile = f_objFso.OpenTextFile(OutToFile, 1)
          tMyOutput = f_objFile.ReadAll
          Set f_objFile = Nothing
        If DeleteOutput = 1 Then
          Set f_objFile = f_objFso.GetFile(OutToFile)
            Set f_objFile = Nothing
          End If
        vFn_Sys_Run_CommandOutput = tMyOutput
        If Err.Number <> 0 Then vFn_Sys_Run_CommandOutput = "<0>"
        On Error Goto 0
      Set f_objFile = Nothing
      Set f_objShell = Nothing
  End Function

What is Bit Masking?

Masking means to keep/change/remove a desired part of information. Lets see an image-masking operation; like- this masking operation is removing any thing that is not skin-

enter image description here

We are doing AND operation in this example. There are also other masking operators- OR, XOR.

Bit-Masking means imposing mask over bits. Here is a bit-masking with AND-

     1 1 1 0 1 1 0 1   [input]
(&)  0 0 1 1 1 1 0 0    [mask]
     0 0 1 0 1 1 0 0  [output]

So, only the middle 4 bits (as these bits are 1 in this mask) remain.

Lets see this with XOR-

     1 1 1 0 1 1 0 1   [input]
(^)  0 0 1 1 1 1 0 0    [mask]
     1 1 0 1 0 0 0 1  [output]

Now, the middle 4 bits are flipped (1 became 0, 0 became 1).

So, using bit-mask we can access individual bits [examples]. Sometimes, this technique may also be used for improving performance. Take this for example-

bool isOdd(int i) {
    return i%2;

This function tells if an integer is odd/even. We can achieve the same result with more efficiency using bit-mask-

bool isOdd(int i) {
    return i&1;

Short Explanation: If the least significant bit of a binary number is 1 then it is odd; for 0 it will be even. So, by doing AND with 1 we are removing all other bits except for the least significant bit i.e.:

     55  ->  0 0 1 1 0 1 1 1   [input]
(&)   1  ->  0 0 0 0 0 0 0 1    [mask]
      1  <-  0 0 0 0 0 0 0 1  [output]

Does Java support default parameter values?

This is how I did it ... it's not as convenient perhaps as having an 'optional argument' against your defined parameter, but it gets the job done:

public void postUserMessage(String s,boolean wipeClean)
        userInformation.setText(s + "\n");

public void postUserMessage(String s)
    userInformation.appendText(s + "\n");

Notice I can invoke the same method name with either just a string or I can invoke it with a string and a boolean value. In this case, setting wipeClean to true will replace all of the text in my TextArea with the provided string. Setting wipeClean to false or leaving it out all together simply appends the provided text to the TextArea.

Also notice I am not repeating code in the two methods, I am merely adding the functionality of being able to reset the TextArea by creating a new method with the same name only with the added boolean.

I actually think this is a little cleaner than if Java provided an 'optional argument' for our parameters since we would need to then code for default values etc. In this example, I don't need to worry about any of that. Yes, I have added yet another method to my class, but it's easier to read in the long run in my humble opinion.

Java, how to compare Strings with String Arrays

I presume you are wanting to check if the array contains a certain value, yes? If so, use the contains method.


Filling a List with all enum values in Java

You can use also:


conditional Updating a list using LINQ

Try this:

li.ForEach(x => x.age = ( == "di") ?
                10 : ( == "marks") ?
                20 : ( == "grade") ?
                30 : 0 );

All values are updated in one line of code and you browse the List only ONE time. You have also a way to set a default value.

How do I add BundleConfig.cs to my project?

BundleConfig is nothing more than bundle configuration moved to separate file. It used to be part of app startup code (filters, bundles, routes used to be configured in one class)

To add this file, first you need to add the Microsoft.AspNet.Web.Optimization nuget package to your web project:

Install-Package Microsoft.AspNet.Web.Optimization

Then under the App_Start folder create a new cs file called BundleConfig.cs. Here is what I have in my mine (ASP.NET MVC 5, but it should work with MVC 4):

using System.Web;
using System.Web.Optimization;

namespace CodeRepository.Web
    public class BundleConfig
        // For more information on bundling, visit
        public static void RegisterBundles(BundleCollection bundles)
            bundles.Add(new ScriptBundle("~/bundles/jquery").Include(

            bundles.Add(new ScriptBundle("~/bundles/jqueryval").Include(

            // Use the development version of Modernizr to develop with and learn from. Then, when you're
            // ready for production, use the build tool at to pick only the tests you need.
            bundles.Add(new ScriptBundle("~/bundles/modernizr").Include(

            bundles.Add(new ScriptBundle("~/bundles/bootstrap").Include(

            bundles.Add(new StyleBundle("~/Content/css").Include(

Then modify your Global.asax and add a call to RegisterBundles() in Application_Start():

using System.Web.Optimization;

protected void Application_Start()

A closely related question: How to add reference to System.Web.Optimization for MVC-3-converted-to-4 app

How to calculate the time interval between two time strings

This site says to try:

import datetime as dt
start_dt = dt.datetime.strptime(start, '%H:%M:%S')
end_dt = dt.datetime.strptime(end, '%H:%M:%S')
diff = (end_dt - start_dt) 

This forum uses time.mktime()

Cannot install packages using node package manager in Ubuntu

Try linking node to nodejs. First find out where nodejs is

whereis nodejs

Then soft link node to nodejs

ln -s [the path of nodejs] /usr/bin/node 

I am assuming /usr/bin is in your execution path. Then you can test by typing node or npm into your command line, and everything should work now.

What is a good way to handle exceptions when trying to read a file in python?

fname = 'filenotfound.txt'
    f = open(fname, 'rb')
except FileNotFoundError:
    print("file {} does not exist".format(fname))

file filenotfound.txt does not exist

exception FileNotFoundError Raised when a file or directory is requested but doesn’t exist. Corresponds to errno ENOENT.
This exception does not exist in Python 2.

Loading scripts after page load?

So, there's no way that this works:

window.onload = function(){
  <script language="JavaScript" src=""></script>

You can't freely drop HTML into the middle of javascript.

If you have jQuery, you can just use:


whenever you want. If you want to make sure the document has finished loading, you can do this:

$(document).ready(function() {

In plain javascript, you can load a script dynamically at any time you want to like this:

var tag = document.createElement("script");
tag.src = "";

What is the meaning of curly braces?

In languages like C curly braces ({}) are used to create program blocks used in flow control. In Python, curly braces are used to define a data structure called a dictionary (a key/value mapping), while white space indentation is used to define program blocks.

Limiting number of displayed results when using ngRepeat

This works better in my case if you have object or multi-dimensional array. It will shows only first items, other will be just ignored in loop.

.filter('limitItems', function () {
  return function (items) {
    var result = {}, i = 1;
    angular.forEach(items, function(value, key) {
      if (i < 5) {
        result[key] = value;
      i = i + 1;
    return result;

Change 5 on what you want.

Java: Casting Object to Array type

Your values object is obviously an Object[] containing a String[] containing the values.

String[] stringValues = (String[])values[0];

How to get body of a POST in php?

return value in array

 $data = json_decode(file_get_contents('php://input'), true);

Language Books/Tutorials for popular languages

For REALbasic:

Buginning REALbasic, From Novice to Professional by Jerry Lee Ford

Very basic, but a good way to get started

How to write a cron that will run a script every day at midnight?

Here's a good tutorial on what crontab is and how to use it on Ubuntu. Your crontab line will look something like this:

00 00 * * * ruby path/to/your/script.rb

(00 00 indicates midnight--0 minutes and 0 hours--and the *s mean every day of every month.)

  mm hh dd mt wd  command

  mm minute 0-59
  hh hour 0-23
  dd day of month 1-31
  mt month 1-12
  wd day of week 0-7 (Sunday = 0 or 7)
  command: what you want to run
  all numeric values can be replaced by * which means all

How to get second-highest salary employees in a table

Simple way WITHOUT using any special feature specific to Oracle, MySQL etc.

Suppose EMPLOYEE table has data as below. Salaries can be repeated. enter image description here

By manual analysis we can decide ranks as follows :-
enter image description here

Same result can be achieved by query

select  *
from  (
select tout.sal, id, (select count(*) +1 from (select distinct(sal) distsal from     
EMPLOYEE ) where  distsal >tout.sal)  as rank  from EMPLOYEE tout
) result
order by rank

enter image description here

First we find out distinct salaries. Then we find out count of distinct salaries greater than each row. This is nothing but the rank of that id. For highest salary, this count will be zero. So '+1' is done to start rank from 1.

Now we can get IDs at Nth rank by adding where clause to above query.

select  *
from  (
select tout.sal, id, (select count(*) +1 from (select distinct(sal) distsal from     
EMPLOYEE ) where  distsal >tout.sal)  as rank  from EMPLOYEE tout
) result
where rank = N;

Why is "except: pass" a bad programming practice?

In my opinion errors have a reason to appear, that my sound stupid, but thats the way it is. Good programming only raises errors when you have to handle them. Also, as i read some time ago, "the pass-Statement is a Statement that Shows code will be inserted later", so if you want to have an empty except-statement feel free to do so, but for a good program there will be a part missing. because you dont handle the things you should have. Appearing exceptions give you the chance to correct input data or to change your data structure so these exceptions dont occur again (but in most cases (Network-exceptions, General input-exceptions) exceptions indicate that the next parts of the program wont execute well. For example a NetworkException can indicate a broken network-connection and the program cant send/recieve data in the next program steps.

But using a pass block for only one execption-block is valid, because you still differenciate beetween the types of exceptions, so if you put all exception-blocks in one, it is not empty:

    #code here
except Error1:
    #exception handle1

except Error2:
    #exception handle2
#and so on

can be rewritten that way:

    #code here
except BaseException as e:
    if isinstance(e, Error1):
        #exception handle1

    elif isinstance(e, Error2):
        #exception handle2



So even multiple except-blocks with pass-statements can result in code, whose structure handles special types of exceptions.

String contains - ignore case

You can use

org.apache.commons.lang3.StringUtils.containsIgnoreCase(CharSequence str,
                                     CharSequence searchStr);

Checks if CharSequence contains a search CharSequence irrespective of case, handling null. Case-insensitivity is defined as by String.equalsIgnoreCase(String).

A null CharSequence will return false.

This one will be better than regex as regex is always expensive in terms of performance.

For official doc, refer to : StringUtils.containsIgnoreCase

Update :

If you are among the ones who

  • don't want to use Apache commons library
  • don't want to go with the expensive regex/Pattern based solutions,
  • don't want to create additional string object by using toLowerCase,

you can implement your own custom containsIgnoreCase using java.lang.String.regionMatches

public boolean regionMatches(boolean ignoreCase,
                             int toffset,
                             String other,
                             int ooffset,
                             int len)

ignoreCase : if true, ignores case when comparing characters.

public static boolean containsIgnoreCase(String str, String searchStr)     {
    if(str == null || searchStr == null) return false;

    final int length = searchStr.length();
    if (length == 0)
        return true;

    for (int i = str.length() - length; i >= 0; i--) {
        if (str.regionMatches(true, i, searchStr, 0, length))
            return true;
    return false;

Name attribute in @Entity and @Table

@Entity(name = "someThing") => this name will be used to identify the domain ..this name will only be identified by hql queries of the domain object

@Table(name = "someThing") => this name will be used to which table referred by domain of the table

Rails 3 check if attribute changed

For rails 5.1+ callbacks

As of Ruby on Rails 5.1, the attribute_changed? and attribute_was ActiveRecord methods will be deprecated

Use saved_change_to_attribute? instead of attribute_changed?

@user.saved_change_to_street1? # => true/false

More examples here

Java: How to read a text file

Look at this example, and try to do your own:


public class ReadFile {

    public static void main(String[] args){
        String string = "";
        String file = "textFile.txt";

        // Reading
            InputStream ips = new FileInputStream(file);
            InputStreamReader ipsr = new InputStreamReader(ips);
            BufferedReader br = new BufferedReader(ipsr);
            String line;
            while ((line = br.readLine()) != null){
                string += line + "\n";
        catch (Exception e){

        // Writing
        try {
            FileWriter fw = new FileWriter (file);
            BufferedWriter bw = new BufferedWriter (fw);
            PrintWriter fileOut = new PrintWriter (bw);
                fileOut.println (string+"\n test of read and write !!");
            System.out.println("the file " + file + " is created!");
        catch (Exception e){

how to modify the size of a column

If you run it, it will work, but in order for SQL Developer to recognize and not warn about a possible error you can change it as:


Displaying the Indian currency symbol on a website

It's possible with simple HTML entity code.

Example 1 : <span class="ex">&#x20b9;1200/-</span><br>_x000D_
Example 2 : <span class="ex">&#8377;3545/-</span><br>_x000D_
Example 3 : <span class="ex">&#2352;134/-</span> *Is not the exact Rupee symbol

ant build.xml file doesn't exist

Using ant debug after building build.xml file :

in your cmd your root should be your project at first then use the ant debug command e.g:

c:\testApp>ant debug 

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

To understand it better, run this following program (in jdk1.7.x) :

$ java -Xms1025k -Xmx1025k -XshowSettings:vm  MemoryTest

This will print jvm options and the used, free, total and maximum memory available in jvm.

public class MemoryTest {    
    public static void main(String args[]) {
                System.out.println("Used Memory   :  " + (Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) + " bytes");
                System.out.println("Free Memory   : " + Runtime.getRuntime().freeMemory() + " bytes");
                System.out.println("Total Memory  : " + Runtime.getRuntime().totalMemory() + " bytes");
                System.out.println("Max Memory    : " + Runtime.getRuntime().maxMemory() + " bytes");            

How to delete node from XML file using C#

It may be easier to use XPath to locate the nodes that you wish to delete. This stackoverflow thread might give you some ideas.

In your case you will find the four nodes that you want using this expression:

XmlDocument doc = new XmlDocument();
XmlNodeList nodes = doc.SelectNodes("//Setting[@name='File1']");