Programs & Examples On #Squirrel

Squirrel is a high-level object-oriented light-weight scripting language that's designed to be used in real-time requirements applications, like video games.

Using Lato fonts in my css (@font-face)

Font Squirrel has a wonderful web font generator.

I think you should find what you need here to generate OTF fonts and the needed CSS to use them. It will even support older IE versions.

Rails: Address already in use - bind(2) (Errno::EADDRINUSE)

To kill the puma process first run

    lsof -wni tcp:3000 

to show what is using port 3000. Then use the PID that comes with the result to run the kill process.

For example after running lsof -wni tcp:3000 you might get something like

    ruby    3366 dummy    8u  IPv4  16901      0t0  TCP (LISTEN)

Now run the following to kill the process. (where 3366 is the PID)

kill -9 3366

Should resolve the issue

Jenkins could not run git

For Jenkins 2.121.3 version, Go to Manage jenkins -> Global tool configuration -> Git installations -> Path to Git executable: C:\Program Files\Git\bin\git.exe It works!

In Jenkins, give the http URL. SSH URL shows similar error.

Why is @font-face throwing a 404 error on woff files?

If you dont have access to your webserver config, you can also just RENAME the font file so that it ends in svg (but retain the format). Works fine for me in Chrome and Firefox.

@font-face src: local - How to use the local font if the user already has it?

I haven’t actually done anything with font-face, so take this with a pinch of salt, but I don’t think there’s any way for the browser to definitively tell if a given web font installed on a user’s machine or not.

The user could, for example, have a different font with the same name installed on their machine. The only way to definitively tell would be to compare the font files to see if they’re identical. And the browser couldn’t do that without downloading your web font first.

Does Firefox download the font when you actually use it in a font declaration? (e.g. h1 { font: 'DejaVu Serif';)?

String comparison in Python: is vs. ==

The logic is not flawed. The statement

if x is y then x==y is also True

should never be read to mean

if x==y then x is y

It is a logical error on the part of the reader to assume that the converse of a logic statement is true. See

Embedding JavaScript engine into .NET

I guess I am still unclear about what it is you are trying to do, but JScript.NET might be worth looking into, though Managed JScript seems like it may be more appropriate for your needs (it is more like JavaScript than JScript.NET).

Personally, I thought it would be cool to integrate V8 somehow, but I didn't get past downloading the source code; wish I had the time to actually do something with it.

Allowed memory size of 262144 bytes exhausted (tried to allocate 24576 bytes)

I see my problem is a little bit different from yours, but I'll post this answer in case it helps someone else. I was using MB as shorthand instead of M when defining my memory_limit, and php was silently ignoring it. I changed it to an integer (in bytes) and the problem was solved.

My php.ini changed as follows: memory_limit = 512MB to memory_limit = 536870912. This fixed my problem. Hope it helps with someone else's! You can read up on php's shorthand here.

Good luck!


As Yaodong points out, you can just as easily use the correct shorthand, "M", instead of using byte values. I changed mine to byte values for debugging purposes and then didn't bother to change it back.

How to stop execution after a certain time in Java?

you should try the new Java Executor Services.

With this you don't need to program the loop the time measuring by yourself.

public class Starter {

    public static void main(final String[] args) {
        final ExecutorService service = Executors.newSingleThreadExecutor();

        try {
            final Future<Object> f = service.submit(() -> {
                // Do you long running calculation here
                Thread.sleep(1337); // Simulate some delay
                return "42";

            System.out.println(f.get(1, TimeUnit.SECONDS));
        } catch (final TimeoutException e) {
            System.err.println("Calculation took to long");
        } catch (final Exception e) {
            throw new RuntimeException(e);
        } finally {

Generating a random hex color code with PHP

you can use md5 for that purpose,very short

$color = substr(md5(rand()), 0, 6);

How can I use iptables on centos 7?

I had the problem that rebooting wouldn't start iptables.

This fixed it:

yum install iptables-services
systemctl mask firewalld
systemctl enable iptables
systemctl enable ip6tables
systemctl stop firewalld
systemctl start iptables
systemctl start ip6tables

How to solve java.lang.NoClassDefFoundError?

For my project, what solved the issue was that Chrome browser and chromedriver were not compatibles. I had a very old version of the driver that could not even open the browser. I just downloaded the latest version of both and problem solved. How did I discovered the issue? Because I ran my project using the Selenium native firefox driver with an old version of FF inculded with my application, I realized then that the problem was incompatibility of between browser and driver.

Hope this can help anyone with a similiar issue as mine, that generated this same Error Message.

Why is Git better than Subversion?

This is the wrong question to be asking. It's all too easy to focus on git's warts and formulate an argument about why subversion is ostensibly better, at least for some use cases. The fact that git was originally designed as a low-level version control construction set and has a baroque linux-developer-oriented interface makes it easier for the holy wars to gain traction and perceived legitimacy. Git proponents bang the drum with millions of workflow advantages, which svn guys proclaim unnecessary. Pretty soon the whole debate is framed as centralized vs distributed, which serves the interests of the enterprise svn tool community. These companies, which typically put out the most convincing articles about subversion's superiority in the enterprise, are dependent on the perceived insecurity of git and the enterprise-readiness of svn for the long-term success of their products.

But here's the problem: Subversion is an architectural dead-end.

Whereas you can take git and build a centralized subversion replacement quite easily, despite being around for more than twice as long svn has never been able to get even basic merge-tracking working anywhere near as well as it does in git. One basic reason for this is the design decision to make branches the same as directories. I don't know why they went this way originally, it certainly makes partial checkouts very simple. Unfortunately it also makes it impossible to track history properly. Now obviously you are supposed to use subversion repository layout conventions to separate branches from regular directories, and svn uses some heuristics to make things work for the daily use cases. But all this is just papering over a very poor and limiting low-level design decision. Being able to a do a repository-wise diff (rather than directory-wise diff) is basic and critical functionality for a version control system, and greatly simplifies the internals, making it possible to build smarter and useful features on top of it. You can see in the amount of effort that has been put into extending subversion, and yet how far behind it is from the current crop of modern VCSes in terms of fundamental operations like merge resolution.

Now here's my heart-felt and agnostic advice for anyone who still believes Subversion is good enough for the foreseeable future:

Subversion will never catch up to the newer breeds of VCSes that have learned from the mistakes of RCS and CVS; it is a technical impossibility unless they retool the repository model from the ground up, but then it wouldn't really be svn would it? Regardless of how much you think you don't the capabilities of a modern VCS, your ignorance will not protect you from the Subversion's pitfalls, many of which are situations that are impossible or easily resolved in other systems.

It is extremely rare that the technical inferiority of a solution is so clear-cut as it is with svn, certainly I would never state such an opinion about win-vs-linux or emacs-vs-vi, but in this case it is so clearcut, and source control is such a fundamental tool in the developer's arsenal, that I feel it must be stated unequivocally. Regardless of the requirement to use svn for organizational reasons, I implore all svn users not to let their logical mind construct a false belief that more modern VCSes are only useful for large open-source projects. Regardless of the nature of your development work, if you are a programmer, you will be a more effective programmer if you learn how to use better-designed VCSes, whether it be Git, Mercurial, Darcs, or many others.

Pandas merge two dataframes with different columns

I think in this case concat is what you want:

In [12]:

pd.concat([df,df1], axis=0, ignore_index=True)
   attr_1  attr_2  attr_3  id  quantity
0       0       1     NaN   1        20
1       1       1     NaN   2        23
2       1       1     NaN   3        19
3       0       0     NaN   4        19
4       1     NaN       0   5         8
5       0     NaN       1   6        13
6       1     NaN       1   7        20
7       1     NaN       1   8        25

by passing axis=0 here you are stacking the df's on top of each other which I believe is what you want then producing NaN value where they are absent from their respective dfs.

ValueError: max() arg is an empty sequence

Since you are always initialising self.listMyData to an empty list in clkFindMost your code will always lead to this error* because after that both unique_names and frequencies are empty iterables, so fix this.

Another thing is that since you're iterating over a set in that method then calculating frequency makes no sense as set contain only unique items, so frequency of each item is always going to be 1.

Lastly dict.get is a method not a list or dictionary so you can't use [] with it:

Correct way is:

if frequencies.get(name):

And Pythonic way is:

if name in frequencies:

The Pythonic way to get the frequency of items is to use collections.Counter:

from collections import Counter   #Add this at the top of file.

def clkFindMost(self, parent):

        #self.listMyData = []   
        if self.listMyData:
           frequencies = Counter(self.listMyData)
           self.txtResults.Value = max(frequencies, key=frequencies.get)
           self.txtResults.Value = '' 

max() and min() throw such error when an empty iterable is passed to them. You can check the length of v before calling max() on it.

>>> lst = []
>>> max(lst)

Traceback (most recent call last):
  File "<pyshell#2>", line 1, in <module>
ValueError: max() arg is an empty sequence
>>> if lst:
    mx = max(lst)
    #Handle this here

If you are using it with an iterator then you need to consume the iterator first before calling max() on it because boolean value of iterator is always True, so we can't use if on them directly:

>>> it = iter([])
>>> bool(it)
>>> lst = list(it)
>>> if lst:
       mx = max(lst)
      #Handle this here   

Good news is starting from Python 3.4 you will be able to specify an optional return value for min() and max() in case of empty iterable.

Ionic android build Error - Failed to find 'ANDROID_HOME' environment variable

Windows - set environment variable permanently:

setx ANDROID_HOME "C:\Program Files\Android\android-sdk"


setx ANDROID_HOME "C:\Program Files (x86)\Android\android-sdk"

Escape curly brace '{' in String.Format

Use double braces {{ or }} so your code becomes:

sb.AppendLine(String.Format("public {0} {1} {{ get; private set; }}", 
prop.Type, prop.Name));

// For prop.Type of "Foo" and prop.Name of "Bar", the result would be:
// public Foo Bar { get; private set; }

Interface type check with Typescript

I would like to point out that TypeScript does not provide a direct mechanism for dynamically testing whether an object implements a particular interface.

Instead, TypeScript code can use the JavaScript technique of checking whether an appropriate set of members are present on the object. For example:

var obj : any = new Foo();

if (obj.someInterfaceMethod) {

What's the PowerShell syntax for multiple values in a switch statement?

    {($_ -eq "y") -or ($_ -eq "yes")} { "You entered Yes." } 
    default { "You entered No." } 

jquery data selector

I've created a new data selector that should enable you to do nested querying and AND conditions. Usage:


The pattern is:

:data( {namespace} [{operator} {check}]  )

"operator" and "check" are optional. So, if you only have :data(a.b.c) it will simply check for the truthiness of a.b.c.

You can see the available operators in the code below. Amongst them is ~= which allows regex testing:


I've tested it with a few variations and it seems to work quite well. I'll probably add this as a Github repo soon (with a full test suite), so keep a look out!

The code:


    var matcher = /\s*(?:((?:(?:\\\.|[^.,])+\.?)+)\s*([!~><=]=|[><])\s*("|')?((?:\\\3|.)*?)\3|(.+?))\s*(?:,|$)/g;

    function resolve(element, data) {

        data = data.match(/(?:\\\.|[^.])+(?=\.|$)/g);

        var cur =[data.shift()];

        while (cur && data[0]) {
            cur = cur[data.shift()];

        return cur || undefined;


    jQuery.expr[':'].data = function(el, i, match) {

        matcher.lastIndex = 0;

        var expr = match[3],
            check, val,
            allMatch = null,
            foundMatch = false;

        while (m = matcher.exec(expr)) {

            check = m[4];
            val = resolve(el, m[1] || m[5]);

            switch (m[2]) {
                case '==': foundMatch = val == check; break;
                case '!=': foundMatch = val != check; break;
                case '<=': foundMatch = val <= check; break;
                case '>=': foundMatch = val >= check; break;
                case '~=': foundMatch = RegExp(check).test(val); break;
                case '>': foundMatch = val > check; break;
                case '<': foundMatch = val < check; break;
                default: if (m[5]) foundMatch = !!val;

            allMatch = allMatch === null ? foundMatch : allMatch && foundMatch;


        return allMatch;



store and retrieve a class object in shared preference

Not possible.

You can only store, simple values in SharedPrefences SharePreferences.Editor

What particularly about the class do you need to save?

How to add composite primary key to table

The ALTER TABLE statement presented by Chris should work, but first you need to declare the columns NOT NULL. All parts of a primary key need to be NOT NULL.

How do I import material design library to Android Studio?

If u are using Android X: follow the instruction here

when the latest library is

implementation ''

Update : Get latest material design library from here

For older SDK

Add the design support library version as same as of your appcompat-v7 library

You can get the latest library from android developer documentation

implementation ''

How to layout multiple panels on a jFrame? (java)

You'll want to use a number of layout managers to help you achieve the basic results you want.

Check out A Visual Guide to Layout Managers for a comparision.

You could use a GridBagLayout but that's one of the most complex (and powerful) layout managers available in the JDK.

You could use a series of compound layout managers instead.

I'd place the graphics component and text area on a single JPanel, using a BorderLayout, with the graphics component in the CENTER and the text area in the SOUTH position.

I'd place the text field and button on a separate JPanel using a GridBagLayout (because it's the simplest I can think of to achieve the over result you want)

I'd place these two panels onto a third, master, panel, using a BorderLayout, with the first panel in the CENTER and the second at the SOUTH position.

But that's me

How to delete object from array inside foreach loop?

You can also use references on foreach values:

foreach($array as $elementKey => &$element) {
    // $element is the same than &$array[$elementKey]
    if (isset($element['id']) and $element['id'] == 'searched_value') {

What bitrate is used for each of the youtube video qualities (360p - 1080p), in regards to flowplayer?

Looking at this official google link: Youtube Live encoder settings, bitrates and resolutions they have this table:

                   240p       360p        480p        720p        1080p
Resolution      426 x 240   640 x 360   854x480     1280x720    1920x1080
Video Bitrates                   
Maximum         700 Kbps    1000 Kbps   2000 Kbps   4000 Kbps   6000 Kbps
Recommended     400 Kbps    750 Kbps    1000 Kbps   2500 Kbps   4500 Kbps
Minimum         300 Kbps    400 Kbps    500 Kbps    1500 Kbps   3000 Kbps

It would appear as though this is the case, although the numbers dont sync up to the google table above:

// the bitrates, video width and file names for this clip
      bitrates: [
        { url: "bbb-800.mp4", width: 480, bitrate: 800 }, //360p video
        { url: "bbb-1200.mp4", width: 720, bitrate: 1200 }, //480p video
        { url: "bbb-1600.mp4", width: 1080, bitrate: 1600 } //720p video

How can I play sound in Java?

For whatever reason, the top answer by wchargin was giving me a null pointer error when I was calling this.getClass().getResourceAsStream().

What worked for me was the following:

void playSound(String soundFile) {
    File f = new File("./" + soundFile);
    AudioInputStream audioIn = AudioSystem.getAudioInputStream(f.toURI().toURL());  
    Clip clip = AudioSystem.getClip();;

And I would play the sound with:


sounds/effects/sheep1.wav was located in the base directory of my project in Eclipse (so not inside the src folder).

How to add an existing folder with files to SVN?

If the intention is adding the local/working copy to SVN, I used to do it the following way.

Note: I use the TortoiseSVN client and these steps assume that you already have the TortoiseSVN client installed.

  1. I have a project (Test-4.2.2) in my local. I want to upload/add it to an SVN repository.
  2. Using the TortoiseSVN repo-browser, I created an empty directory, "Test-4.2.2"
  3. In my local I renamed the existing "Test-4.2.2" directory to "Test-" (temporary)
  4. Checkout the empty "Test-4.2.2" from SVN to your local
  5. Copy all the sub-directories under to this checkout directory 4.2.2
  6. Now, right click "Test-4.2.2" and commit.
  7. Delete the temp folder, "Test-"

Typescript: How to extend two classes?

A very hacky solution would be to loop through the class you want to inherit from adding the functions one by one to the new parent class

class ChildA {
    public static x = 5

class ChildB {
    public static y = 6

class Parent {}

for (const property in ChildA) {
    Parent[property] = ChildA[property]
for (const property in ChildB) {
    Parent[property] = ChildB[property]

// 5
// 6

All properties of ChildA and ChildB can now be accessed from the Parent class, however they will not be recognised meaning that you will receive warnings such as Property 'x' does not exist on 'typeof Parent'

AngularJS access parent scope from child controller

Super easy and works, but not sure why....

  .directive('details', function () {
        return {
              templateUrl: 'components/details.template.html',
              restrict: 'E',                 
              controller: function ($scope) {
                    $scope.details=$scope.details;  <=== can see the parent details doing this                     

What is the "__v" field in Mongoose

We can use versionKey: false in Schema definition

'use strict';

const mongoose = require('mongoose');

export class Account extends mongoose.Schema {

    constructor(manager) {

        var trans = {
            tran_date: Date,
            particulars: String,
            debit: Number,
            credit: Number,
            balance: Number

            account_number: Number,
            account_name: String,
            ifsc_code: String,
            password: String,
            currency: String,
            balance: Number,
            beneficiaries: Array,
            transaction: [trans]
        }, {
            versionKey: false // set to false then it wont create in mongodb

        this.pre('remove', function(next) {
                    _id: {
                        $in: this.beneficiaries


How to check whether a file is empty or not?

An important gotcha: a compressed empty file will appear to be non-zero when tested with getsize() or stat() functions:

$ python
>>> import os
>>> os.path.getsize('empty-file.txt.gz')
>>> os.stat("empty-file.txt.gz").st_size == 0

$ gzip -cd empty-file.txt.gz | wc
0 0 0

So you should check whether the file to be tested is compressed (e.g. examine the filename suffix) and if so, either bail or uncompress it to a temporary location, test the uncompressed file, and then delete it when done.

How to pad a string to a fixed length with spaces in Python?

string = ""
name = raw_input() #The value at the field
length = input() #the length of the field
string += name
string += " "*(length-len(name)) # Add extra spaces

This will add the number of spaces needed, provided the field has length >= the length of the name provided

Does Python's time.time() return the local or UTC timestamp?

There is no such thing as an "epoch" in a specific timezone. The epoch is well-defined as a specific moment in time, so if you change the timezone, the time itself changes as well. Specifically, this time is Jan 1 1970 00:00:00 UTC. So time.time() returns the number of seconds since the epoch.

Search for value in DataGridView in a column

It's better also to separate your logic in another method, or maybe in another class.

This method will help you retreive the DataGridViewCell object in which the text was found.

    /// <summary>
    /// Check if a given text exists in the given DataGridView at a given column index
    /// </summary>
    /// <param name="searchText"></param>
    /// <param name="dataGridView"></param>
    /// <param name="columnIndex"></param>
    /// <returns>The cell in which the searchText was found</returns>
    private DataGridViewCell GetCellWhereTextExistsInGridView(string searchText, DataGridView dataGridView, int columnIndex)
        DataGridViewCell cellWhereTextIsMet = null;

        // For every row in the grid (obviously)
        foreach (DataGridViewRow row in dataGridView.Rows)
            // I did not test this case, but cell.Value is an object, and objects can be null
            // So check if the cell is null before using .ToString()
            if (row.Cells[columnIndex].Value != null && searchText == row.Cells[columnIndex].Value.ToString())
                // the searchText is equals to the text in this cell.
                cellWhereTextIsMet = row.Cells[columnIndex];

        return cellWhereTextIsMet;

    private void button_click(object sender, EventArgs e)
        DataGridViewCell cell = GetCellWhereTextExistsInGridView(textBox1.Text, myGridView, 2);
        if (cell != null)
            // Value exists in the grid
            // you can do extra stuff on the cell
            cell.Style = new DataGridViewCellStyle { ForeColor = Color.Red };
            // Value does not exist in the grid

"This SqlTransaction has completed; it is no longer usable."... configuration error?

I had this recently after refactoring in a new connection manager. A new routine accepted a transaction so it could be run as part of a batch, problem was with a using block:

public IEnumerable<T> Query<T>(IDbTransaction transaction, string command, dynamic param = null)
  using (transaction.Connection)
    using (transaction)
      return transaction.Connection.Query<T>(command, new DynamicParameters(param), transaction, commandType: CommandType.StoredProcedure);

It looks as though the outer using was closing the underlying connection thus any attempts to commit or rollback the transaction threw up the message "This SqlTransaction has completed; it is no longer usable."

I removed the usings added a covering test and the problem went away.

public IEnumerable<T> Query<T>(IDbTransaction transaction, string command, dynamic param = null)
  return transaction.Connection.Query<T>(command, new DynamicParameters(param), transaction, commandType: CommandType.StoredProcedure);

Check for anything that might be closing the connection while inside the context of a transaction.

How to split a dataframe string column into two columns?

I saw that no one had used the slice method, so here I put my 2 cents here.


This method will create two new columns.

JAVA Unsupported major.minor version 51.0

This is because of a higher JDK during compile time and lower JDK during runtime. So you just need to update your JDK version, possible to JDK 7

You may also check Unsupported major.minor version 51.0

Change limit for "Mysql Row size too large"

If this occures on a SELECT with many columns, the cause can be that mysql is creating a temporary table. If this table is too large to fit in memory, it will use its default temp table format, which is InnoDB, to store it on Disk. In this case the InnoDB size limits apply.

You then have 4 options:

  1. change the innodb row size limit like stated in another post, which requires reinitialization of the server.
  2. change your query to include less columns or avoid causing it to create a temporary table (by i.e. removing order by and limit clauses).
  3. changing max_heap_table_size to be large so the result fits in memory and does not need to get written to disk.
  4. change the default temp table format to MYISAM, this is what i did. Change in my.cnf:


Restart mysql, query works.

How to use stringstream to separate comma separated strings

#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main()
    std::string input = "abc,def,   ghi";
    std::istringstream ss(input);
    std::string token;
    size_t pos=-1;
    while(ss>>token) {
      while ((pos=token.rfind(',')) != std::string::npos) {
        token.erase(pos, 1);
      std::cout << token << '\n';

Sorting HashMap by values

                .sorted((k1, k2) -> -k1.getValue().compareTo(k2.getValue()))
                .forEach(k -> System.out.println(k.getKey() + ": " + k.getValue()));

"insufficient memory for the Java Runtime Environment " message in eclipse

Your application (Eclipse) needs more memory and JVM is not allocating enough.You can increase the amount of memory JVM allocates by following the answers given here

stopPropagation vs. stopImmediatePropagation

1)event.stopPropagation(): =>It is used to stop executions of its corresponding parent handler only.

2) event.stopImmediatePropagation(): => It is used to stop the execution of its corresponding parent handler and also handler or function attached to itself except the current handler. => It also stops all the handler attached to the current element of entire DOM.

Here is the example: Jsfiddle!

Thanks, -Sahil

How to parse XML using vba

Add reference Project->References Microsoft XML, 6.0 and you can use example code:

    Dim xml As String

    xml = "<root><person><name>Me </name> </person> <person> <name>No Name </name></person></root> "
    Dim oXml As MSXML2.DOMDocument60
    Set oXml = New MSXML2.DOMDocument60
    oXml.loadXML xml
    Dim oSeqNodes, oSeqNode As IXMLDOMNode

    Set oSeqNodes = oXml.selectNodes("//root/person")
    If oSeqNodes.length = 0 Then
       'show some message
        For Each oSeqNode In oSeqNodes
             Debug.Print oSeqNode.selectSingleNode("name").Text
    End If 

be careful with xml node //Root/Person is not same with //root/person, also selectSingleNode("Name").text is not same with selectSingleNode("name").text

console.log timestamps in Chrome?

+new Date and are alternate ways to get timestamps

How do I get my solution in Visual Studio back online in TFS?

I am using Visual Studio 2017 15.4.0 version. Especially when i started use lightweight solution option, this offline thing happened to me. I tried to above solutions which are:

  1. Tried to regedit option but can not see appropriate menu options. Didn't work.
  2. Right click on solution, there is go online option and when i choose it that gives this error message: "The solution is offline because its associated Team Foundation Server is offline. Unable to determine the workspace for this solution."

Then from File -> Source Control -> Advanced -> Change Source Control. I saw my files. I select them and then chose bind option. That worked for me.

"Sources directory is already netbeans project" error when opening a project from existing sources

Usually this happened when we copy source code of a already created project and copied in different folder and try to create a project from it. as netBeans create its folder nbproject in our project folder this folder also get copied with our source code and it give error "Sources directory is already NetBeans project (maybe only in memory)" remove this folder from you newly copied folder and voila you can create a new project.

Popup Message boxes


hi guys i was searching pop up windows in applet all over the internet but could not find answer for windows.

Although it is simple i am just helping you. Hope you will like it as it is in simpliest form. here's the code :

Filename: for java file and we need html file too.

For applet let us take its popup.html


import java.awt.*;

import java.applet.*;

import java.awt.event.*;

public class PopUpWindow extends Applet{

public void init(){

Button open = new Button("open window");


Button close = new Button("close window");


 Frame f = new Frame("pupup win");


 open.addActionListener(new ActionListener() {

                 public void actionPerformed(ActionEvent e) {
                     if(!f.isShowing()) {


 close.addActionListener(new ActionListener() {

                 public void actionPerformed(ActionEvent e) {
                     if(f.isShowing()) {







<APPLET CODE="PopUpWindow" width="" height="">





to run:
$javac && appletviewer popup.html

Bitbucket fails to authenticate on git pull

I think is only an authentication problem...

  1. Click on your Bitbucket account icon (up right) and go to "Manage account".
  2. Go to "Change password" option in left menu.
  3. Enter your password in "New password" and "Confirm password" fields.
  4. Click on "Change password".

That's all :)

How can I determine if a variable is 'undefined' or 'null'?

jQuery check element not null:

var dvElement = $('#dvElement');

if (dvElement.length  > 0) {
    // Do something
    // Else do something else

Bootstrap carousel multiple frames at once

Update 2019-03-06 -- Bootstrap v4.3.1

It seems the new Bootstrap version adds a margin-right: -100% to each item, therefore in the responsive solution given in the most upvoted answer in here, this property should be reset, e.g.:

.carousel-inner .carousel-item {
    margin-right: inherit;

A working codepen with v4.3.1 in LESS.

Setting Authorization Header of HttpClient

This is how i have done it:

using (HttpClient httpClient = new HttpClient())
   Dictionary<string, string> tokenDetails = null;
   var messageDetails = new Message { Id = 4, Message1 = des };
   HttpClient client = new HttpClient();
   client.BaseAddress = new Uri("http://localhost:3774/");
   var login = new Dictionary<string, string>
           {"grant_type", "password"},
           {"username", "[email protected]"},
           {"password", "lopzwsx@23"},
   var response = client.PostAsync("Token", new FormUrlEncodedContent(login)).Result;
   if (response.IsSuccessStatusCode)
      tokenDetails = JsonConvert.DeserializeObject<Dictionary<string, string>>(response.Content.ReadAsStringAsync().Result);
      if (tokenDetails != null && tokenDetails.Any())
         var tokenNo = tokenDetails.FirstOrDefault().Value;
         client.DefaultRequestHeaders.Add("Authorization", "Bearer " + tokenNo);
         client.PostAsJsonAsync("api/menu", messageDetails)
             .ContinueWith((postTask) => postTask.Result.EnsureSuccessStatusCode());

This you-tube video help me out a lot. Please check it out.

why should I make a copy of a data frame in pandas

Assumed you have data frame as below

     A    B    C    D
4 -1.0 -1.0 -1.0 -1.0
5 -1.0 -1.0 -1.0 -1.0
6 -1.0 -1.0 -1.0 -1.0
6 -1.0 -1.0 -1.0 -1.0

When you would like create another df2 which is identical to df1, without copy

     A    B    C    D
4 -1.0 -1.0 -1.0 -1.0
5 -1.0 -1.0 -1.0 -1.0
6 -1.0 -1.0 -1.0 -1.0
6 -1.0 -1.0 -1.0 -1.0

And would like modify the df2 value only as below


         A    B    C    D
4  changed -1.0 -1.0 -1.0
5       -1 -1.0 -1.0 -1.0
6       -1 -1.0 -1.0 -1.0
6       -1 -1.0 -1.0 -1.0

At the same time the df1 is changed as well

         A    B    C    D
4  changed -1.0 -1.0 -1.0
5       -1 -1.0 -1.0 -1.0
6       -1 -1.0 -1.0 -1.0
6       -1 -1.0 -1.0 -1.0

Since two df as same object, we can check it by using the id


So they as same object and one change another one will pass the same value as well.

If we add the copy, and now df1 and df2 are considered as different object, if we do the same change to one of them the other will not change.


         A    B    C    D
4  changed -1.0 -1.0 -1.0
5       -1 -1.0 -1.0 -1.0
6       -1 -1.0 -1.0 -1.0
6       -1 -1.0 -1.0 -1.0

Good to mention, when you subset the original dataframe, it is safe to add the copy as well in order to avoid the SettingWithCopyWarning

Remove Sub String by using Python

import re
re.sub('<.*?>', '', string)
"i think mabe 124 + but I don't have a big experience it just how I see it in my eyes fun stuff"

The re.sub function takes a regular expresion and replace all the matches in the string with the second parameter. In this case, we are searching for all tags ('<.*?>') and replacing them with nothing ('').

The ? is used in re for non-greedy searches.

More about the re module.

How to create PDFs in an Android app?

A trick to make a PDF with complex features is to make a dummy activity with the desired xml layout. You can then open this dummy activity, take a screenshot programmatically and convert that image to pdf using this library. Of course there are limitations such as not being able to scroll, not more than one page,but for a limited application this is quick and easy. Hope this helps someone!

Return char[]/string from a function

Including "string.h" makes things easier. An easier way to tackle your problem is:

#include <string.h>
    char* createStr(){
    static char str[20] = "my";
    return str;
int main(){
    char a[20];
    strcpy(a,createStr()); //this will copy the returned value of createStr() into a[]
    return 0;

NullPointerException in Java with no StackTrace

Alternate suggestion - if you're using Eclipse, you could set a breakpoint on NullPointerException itself (in the Debug perspective, go to the "Breakpoints" tab and click on the little icon that has a ! in it)

Check both the "caught" and "uncaught" options - now when you trigger the NPE, you'll immediately breakpoint and you can then step through and see how exactly it is handled and why you're not getting a stack trace.

How to draw circle by canvas in Android?

    private Paint green = new Paint();

    private int greenx , greeny;




How to keep two folders automatically synchronized?

You can take advantage of fschange. It’s a Linux filesystem change notification. The source code is downloadable from the above link, you can compile it yourself. fschange can be used to keep track of file changes by reading data from a proc file (/proc/fschange). When data is written to a file, fschange reports the exact interval that has been modified instead of just saying that the file has been changed. If you are looking for the more advanced solution, I would suggest checking Resilio Connect. It is cross-platform, provides extended options for use and monitoring. Since it’s BitTorrent-based, it is faster than any other existing sync tool. It was written on their behalf.

Windows command for file size only

Since you're using Windows XP, Windows PowerShell is an option.

(Get-Item filespec ).Length 

or as a function

function Get-FileLength { (Get-Item $args).Length }
Get-FileLength filespec

Using the passwd command from within a shell script

The only solution works on Ubuntu 12.04:

echo -e "new_password\nnew_password" | (passwd user)

But the second option only works when I change from:

echo "password:name" | chpasswd


echo "user:password" | chpasswd

See explanations in original post: Changing password via a script

How do I print the percent sign(%) in c

Use "%%". The man page describes this requirement:

% A '%' is written. No argument is converted. The complete conversion specification is '%%'.

How to compare two maps by their values

Since you asked about ready-made Api's ... well Apache's commons. collections library has a CollectionUtils class that provides easy-to-use methods for Collection manipulation/checking, such as intersection, difference, and union.

Embedding VLC plugin on HTML page

Unfortunately, IE and VLC don't really work right now... I found this on the vlc forums:

VLC included activex support up until version 0.8.6, I believe. At that time, you could
access a cab on the videolan and therefore 'automatic' installation into IE and Firefox
family browsers was fine. Thereafter support for activex seemed to stop; no cab, no
activex component.

VLC 1.0.* once again contains activex support, and that's brilliant. A good decision in
my opinion. What's lacking is a cab installer for the latest version.

This basically means that even if you found a way to make it work, anyone trying to view the video on your site in IE would have to download and install the entire VLC player program to have it work in IE, and users probably don't want to do that. I can't get your code to work in firefox or IE8 on my boyfriends computer, although I might not have been putting the video address in properly... I get some message about no video output...

I'll take a guess and say it probably works for you locally because you have VLC installed, but your server doesn't. Unfortunately you'll probably have to use Windows media player or something similar (Microsoft is great at forcing people to use their stuff!)

And if you're wondering, it appears that the reason there is no cab file is because of the cost of having an active-x control signed.

It's rather simple to have your page use VLC for firefox and chrome users, and Windows Media Player for IE users, if that would work for you.

Add placeholder text inside UITextView in Swift?

One more solution (Swift 3):

import UIKit

protocol PlaceholderTextViewDelegate {
    func placeholderTextViewDidChangeText(_ text:String)
    func placeholderTextViewDidEndEditing(_ text:String)

final class PlaceholderTextView: UITextView {

    var notifier:PlaceholderTextViewDelegate?

    var placeholder: String? {
        didSet {
            placeholderLabel?.text = placeholder
    var placeholderColor = UIColor.lightGray
    var placeholderFont = UIFont.appMainFontForSize(14.0) {
        didSet {
            placeholderLabel?.font = placeholderFont

    fileprivate var placeholderLabel: UILabel?

    // MARK: - LifeCycle

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

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

    override func awakeFromNib() {

        self.delegate = self
        NotificationCenter.default.addObserver(self, selector: #selector(PlaceholderTextView.textDidChangeHandler(notification:)), name: .UITextViewTextDidChange, object: nil)

        placeholderLabel = UILabel()
        placeholderLabel?.textColor = placeholderColor
        placeholderLabel?.text = placeholder
        placeholderLabel?.textAlignment = .left
        placeholderLabel?.numberOfLines = 0

    override func layoutSubviews() {

        placeholderLabel?.font = placeholderFont

        var height:CGFloat = placeholderFont.lineHeight
        if let data = placeholderLabel?.text {

            let expectedDefaultWidth:CGFloat = bounds.size.width
            let fontSize:CGFloat = placeholderFont.pointSize

            let textView = UITextView()
            textView.text = data
            textView.font = UIFont.appMainFontForSize(fontSize)
            let sizeForTextView = textView.sizeThatFits(CGSize(width: expectedDefaultWidth,
                                                               height: CGFloat.greatestFiniteMagnitude))
            let expectedTextViewHeight = sizeForTextView.height

            if expectedTextViewHeight > height {
                height = expectedTextViewHeight

        placeholderLabel?.frame = CGRect(x: 5, y: 0, width: bounds.size.width - 16, height: height)

        if text.isEmpty {
            bringSubview(toFront: placeholderLabel!)
        } else {

    func textDidChangeHandler(notification: Notification) {


extension PlaceholderTextView : UITextViewDelegate {
    // MARK: - UITextViewDelegate
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        if(text == "\n") {
            return false
        return true

    func textViewDidChange(_ textView: UITextView) {

    func textViewDidEndEditing(_ textView: UITextView) {


enter image description here

Sqlite primary key on multiple columns

According to the documentation, it's

CREATE TABLE something (
  PRIMARY KEY (column1, column2)

Sharing a variable between multiple different threads

You can use lock variables "a" and "b" and synchronize them for locking the "critical section" in reverse order. Eg. Notify "a" then Lock "b" ,"PRINT", Notify "b" then Lock "a".

Please refer the below the code :

public class EvenOdd {

    static int a = 0;

    public static void main(String[] args) {

        EvenOdd eo = new EvenOdd();

        A aobj = A();
        B bobj = B();

        aobj.a = Lock.lock1;
        aobj.b = Lock.lock2;

        bobj.a = Lock.lock2;
        bobj.b = Lock.lock1;

        Thread t1 = new Thread(aobj);
        Thread t2 = new Thread(bobj);


    static class Lock {
        final static Object lock1 = new Object();
        final static Object lock2 = new Object();

    class A implements Runnable {

        Object a;
        Object b;

        public void run() {
            while (EvenOdd.a < 10) {
                try {
                    System.out.println(++EvenOdd.a + " A ");
                    synchronized (a) {
                    synchronized (b) {
                } catch (InterruptedException e) {

    class B implements Runnable {

        Object a;
        Object b;

        public void run() {
            while (EvenOdd.a < 10) {

                try {
                    synchronized (b) {
                        System.out.println(++EvenOdd.a + " B ");
                    synchronized (a) {
                } catch (InterruptedException e) {


1 A 
2 B 
3 A 
4 B 
5 A 
6 B 
7 A 
8 B 
9 A 
10 B 

How to exit a function in bash

If you want to return from an outer function with an error without exiting you can use this trick:

do-something-complex() {
  # Using `return` here would only return from `fail`, not from `do-something-complex`.
  # Using `exit` would close the entire shell.
  # So we (ab)use a different feature. :)
  fail() { : "${__fail_fast:?$1}"; }

  nested-func() {
      try-this || fail "This didn't work"
      try-that || fail "That didn't work"

Trying it out:

$ do-something-complex
try-this: command not found
bash: __fail_fast: This didn't work

This has the added benefit/drawback that you can optionally turn off this feature: __fail_fast=x do-something-complex.

Note that this causes the outermost function to return 1.

find the array index of an object with a specific key value in underscore

If you're expecting multiple matches and hence need an array to be returned, try:

_.where(Users, {age: 24})

If the property value is unique and you need the index of the match, try:

_.findWhere(Users, {_id: 10})

How to convert a structure to a byte array in C#?

You can use Marshal (StructureToPtr, ptrToStructure), and Marshal.copy but this is plataform dependent.

Serialization includes Functions to Custom Serialization.

public virtual void GetObjectData(SerializationInfo info, StreamingContext context)
Protected Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext) 

SerializationInfo include functions to serialize each member.

BinaryWriter and BinaryReader also contains methods to Save / Load to Byte Array (Stream).

Note that you can create a MemoryStream from a Byte Array or a Byte Array from a MemoryStream.

You can create a method Save and a method New on your structure:

   Save(Bw as BinaryWriter)
   New (Br as BinaryReader)

Then you select members to Save / Load to Stream -> Byte Array.

C# : Passing a Generic Object

You cannot access var with the generic.

Try something like

Console.WriteLine("Generic : {0}", test);

And override ToString method [1]


Export to CSV using jQuery and html

 <a id="export" role='button'>
        Click Here To Download Below Report
    <table id="testbed_results" style="table-layout:fixed">
            <tr width="100%" style="color:white" bgcolor="#3195A9" id="tblHeader">
                <th>COmpany result</th>
            <tr id="samplerow">

    $(document).ready(function () {
        Html2CSV('testbed_results', 'myfilename','export');

    function Html2CSV(tableId, filename,alinkButtonId) {
        var array = [];
        var headers = [];
        var arrayItem = [];
        var csvData = new Array();
        $('#' + tableId + ' th').each(function (index, item) {
            headers[index] = '"' + $(item).html() + '"';
        $('#' + tableId + ' tr').has('td').each(function () {

            $('td', $(this)).each(function (index, item) {
                arrayItem[index] = '"' + $(item).html() + '"';

        var fileName = filename + '.csv';
        var buffer = csvData.join("\n");
        var blob = new Blob([buffer], {
            "type": "text/csv;charset=utf8;"
        var link = document.getElementById(alinkButton);

        if ( !== undefined) { // feature detection
            // Browsers that support HTML5 download attribute
            link.setAttribute("href", window.URL.createObjectURL(blob));
            link.setAttribute("download", fileName);
        else if (navigator.msSaveBlob) { // IE 10+
            link.setAttribute("href", "#");
            link.addEventListener("click", function (event) {
                navigator.msSaveBlob(blob, fileName);
            }, false);
        else {
            // it needs to implement server side export
            link.setAttribute("href", "");


What is a Data Transfer Object (DTO)?

A Data Transfer Object is an object that is used to encapsulate data, and send it from one subsystem of an application to another.

DTOs are most commonly used by the Services layer in an N-Tier application to transfer data between itself and the UI layer. The main benefit here is that it reduces the amount of data that needs to be sent across the wire in distributed applications. They also make great models in the MVC pattern.

Another use for DTOs can be to encapsulate parameters for method calls. This can be useful if a method takes more than 4 or 5 parameters.

When using the DTO pattern, you would also make use of DTO assemblers. The assemblers are used to create DTOs from Domain Objects, and vice versa.

The conversion from Domain Object to DTO and back again can be a costly process. If you're not creating a distributed application, you probably won't see any great benefits from the pattern, as Martin Fowler explains here

Update Git submodule to latest commit on origin

git pull --recurse-submodules

This will pull all the latest commits.

Removing fields from struct or hiding them in JSON Response

You can use tagging attribute "omitifempty" or make optional fields pointers and leave those you want skipped uninitialized.

Difference between InvariantCulture and Ordinal string comparison

Another handy difference (in English where accents are uncommon) is that an InvariantCulture comparison compares the entire strings by case-insensitive first, and then if necessary (and requested) distinguishes by case after first comparing only on the distinct letters. (You can also do a case-insensitive comparison, of course, which won't distinguish by case.) Corrected: Accented letters are considered to be another flavor of the same letters and the string is compared first ignoring accents and then accounting for them if the general letters all match (much as with differing case except not ultimately ignored in a case-insensitive compare). This groups accented versions of the otherwise same word near each other instead of completely separate at the first accent difference. This is the sort order you would typically find in a dictionary, with capitalized words appearing right next to their lowercase equivalents, and accented letters being near the corresponding unaccented letter.

An ordinal comparison compares strictly on the numeric character values, stopping at the first difference. This sorts capitalized letters completely separate from the lowercase letters (and accented letters presumably separate from those), so capitalized words would sort nowhere near their lowercase equivalents.

InvariantCulture also considers capitals to be greater than lower case, whereas Ordinal considers capitals to be less than lowercase (a holdover of ASCII from the old days before computers had lowercase letters, the uppercase letters were allocated first and thus had lower values than the lowercase letters added later).

For example, by Ordinal: "0" < "9" < "A" < "Ab" < "Z" < "a" < "aB" < "ab" < "z" < "Á" < "Áb" < "á" < "áb"

And by InvariantCulture: "0" < "9" < "a" < "A" < "á" < "Á" < "ab" < "aB" < "Ab" < "áb" < "Áb" < "z" < "Z"

How to print a string multiple times?

For example if you want to repeat a word called "HELP" for 1000 times the following is the best way.

word = ['HELP']
repeat = 1000 * word

Then you will get the list of 1000 words and make that into a data frame if you want by using following command

word_data =pd.DataFrame(repeat)
word_data.columns = ['list_of_words'] #To change the column name 

HTML table sort

The way I have sorted HTML tables in the browser uses plain, unadorned Javascript.

The basic process is:

  1. add a click handler to each table header
  2. the click handler notes the index of the column to be sorted
  3. the table is converted to an array of arrays (rows and cells)
  4. that array is sorted using javascript sort function
  5. the data from the sorted array is inserted back into the HTML table

The table should, of course, be nice HTML. Something like this...


So, first adding the click handlers...

const table = document.querySelector('table'); //get the table to be sorted

table.querySelectorAll('th') // get all the table header elements
  .forEach((element, columnNo)=>{ // add a click handler for each 
    element.addEventListener('click', event => {
        sortTable(table, columnNo); //call a function which sorts the table by a given column number

This won't work right now because the sortTable function which is called in the event handler doesn't exist.

Lets write it...

function sortTable(table, sortColumn){
  // get the data from the table cells
  const tableBody = table.querySelector('tbody')
  const tableData = table2data(tableBody);
  // sort the extracted data
  tableData.sort((a, b)=>{
    if(a[sortColumn] > b[sortColumn]){
      return 1;
    return -1;
  // put the sorted data back into the table
  data2table(tableBody, tableData);

So now we get to the meat of the problem, we need to make the functions table2data to get data out of the table, and data2table to put it back in once sorted.

Here they are ...

// this function gets data from the rows and cells 
// within an html tbody element
function table2data(tableBody){
  const tableData = []; // create the array that'll hold the data rows
    .forEach(row=>{  // for each table row...
      const rowData = [];  // make an array for that row
      row.querySelectorAll('td')  // for each cell in that row
          rowData.push(cell.innerText);  // add it to the row data
      tableData.push(rowData);  // add the full row to the table data 
  return tableData;

// this function puts data into an html tbody element
function data2table(tableBody, tableData){
  tableBody.querySelectorAll('tr') // for each table row...
    .forEach((row, i)=>{  
      const rowData = tableData[i]; // get the array for the row data
      row.querySelectorAll('td')  // for each table cell ...
        .forEach((cell, j)=>{
          cell.innerText = rowData[j]; // put the appropriate array element into the cell

And that should do it.

A couple of things that you may wish to add (or reasons why you may wish to use an off the shelf solution): An option to change the direction and type of sort i.e. you may wish to sort some columns numerically ("10" > "2" is false because they're strings, probably not what you want). The ability to mark a column as sorted. Some kind of data validation.

Groovy built-in REST/HTTP client?

You can take advantage of Groovy features like with(), improvements to URLConnection, and simplified getters/setters:


String getResult = new URL('http://mytestsite/bloop').text


String postResult
((HttpURLConnection)new URL('http://mytestsite/bloop').openConnection()).with({
    requestMethod = 'POST'
    doOutput = true
    setRequestProperty('Content-Type', '...') // Set your content type.
    outputStream.withPrintWriter({printWriter ->
        printWriter.write('...') // Your post data. Could also use withWriter() if you don't want to write a String.
    // Can check 'responseCode' here if you like.
    postResult = inputStream.text // Using 'inputStream.text' because 'content' will throw an exception when empty.

Note, the POST will start when you try to read a value from the HttpURLConnection, such as responseCode, inputStream.text, or getHeaderField('...').

What is the difference between cache and persist?

Spark gives 5 types of Storage level


cache() will use MEMORY_ONLY. If you want to use something else, use persist(StorageLevel.<*type*>).

By default persist() will store the data in the JVM heap as unserialized objects.

Use component from another module

The main rule here is that:

The selectors which are applicable during compilation of a component template are determined by the module that declares that component, and the transitive closure of the exports of that module's imports.

So, try to export it:

  declarations: [TaskCardComponent],
  imports: [MdCardModule],
  exports: [TaskCardComponent] <== this line
export class TaskModule{}

What should I export?

Export declarable classes that components in other modules should be able to reference in their templates. These are your public classes. If you don't export a class, it stays private, visible only to other component declared in this module.

The minute you create a new module, lazy or not, any new module and you declare anything into it, that new module has a clean state(as Ward Bell said in

Angular creates transitive module for each of @NgModules.

This module collects directives that either imported from another module(if transitive module of imported module has exported directives) or declared in current module.

When angular compiles template that belongs to module X it is used those directives that had been collected in X.transitiveModule.directives.

compiledTemplate = new CompiledTemplate(
    false, compMeta.type, compMeta, ngModule, ngModule.transitiveModule.directives);

enter image description here

This way according to the picture above

  • YComponent can't use ZComponent in its template because directives array of Transitive module Y doesn't contain ZComponent because YModule has not imported ZModule whose transitive module contains ZComponent in exportedDirectives array.

  • Within XComponent template we can use ZComponent because Transitive module X has directives array that contains ZComponent because XModule imports module (YModule) that exports module (ZModule) that exports directive ZComponent

  • Within AppComponent template we can't use XComponent because AppModule imports XModule but XModule doesn't exports XComponent.

See also

How to get a float result by dividing two integer values using T-SQL?

It's not necessary to cast both of them. Result datatype for a division is always the one with the higher data type precedence. Thus the solution must be:

SELECT CAST(1 AS float) / 3


SELECT 1 / CAST(3 AS float)

Catch checked change event of a checkbox

use the click event for best compatibility with MSIE

$(document).ready(function() {
    $("input[type=checkbox]").click(function() {
        alert("state changed");

Reference to a non-shared member requires an object reference occurs when calling public sub

You either have to make the method Shared or use an instance of the class General:

Dim gen = New General()



Public Shared Sub updateDynamics(dynID As Int32)
    ' ... '
End Sub


Passing parameter to controller action from a Html.ActionLink

You are using the incorrect overload of ActionLink. Try this

<%= Html.ActionLink("Create New Part", "CreateParts", "PartList", new { parentPartId = 0 }, null)%>

How can I delete all cookies with JavaScript?

There is no 100% solution to delete browser cookies.

The problem is that cookies are uniquely identified by not just by their key "name" but also their "domain" and "path".

Without knowing the "domain" and "path" of a cookie, you cannot reliably delete it. This information is not available through JavaScript's document.cookie. It's not available through the HTTP Cookie header either!

However, if you know the name, path and domain of a cookie, then you can clear it by setting an empty cookie with an expiry date in the past, for example:

function clearCookie(name, domain, path){
    var domain = domain || document.domain;
    var path = path || "/";
    document.cookie = name + "=; expires=" + +new Date + "; domain=" + domain + "; path=" + path;

How can I map "insert='false' update='false'" on a composite-id key-property which is also used in a one-to-many FK?

I think the annotation you are looking for is:

public class CompanyName implements Serializable {
@JoinColumn(name = "COMPANY_ID", referencedColumnName = "COMPANY_ID", insertable = false, updatable = false)
private Company company;

And you should be able to use similar mappings in a hbm.xml as shown here (in 23.4.2):

How do I encode and decode a base64 string?

    using System;
    using System.Text;

    public static class Base64Conversions
        public static string EncodeBase64(this string text, Encoding encoding = null)
            if (text == null) return null;

            encoding = encoding ?? Encoding.UTF8;
            var bytes = encoding.GetBytes(text);
            return Convert.ToBase64String(bytes);

        public static string DecodeBase64(this string encodedText, Encoding encoding = null)
            if (encodedText == null) return null;

            encoding = encoding ?? Encoding.UTF8;
            var bytes = Convert.FromBase64String(encodedText);
            return encoding.GetString(bytes);


    var text = "Sample Text";
    var base64 = text.EncodeBase64();
    base64 = text.EncodeBase64(Encoding.UTF8); //or with Encoding

What is the difference between "long", "long long", "long int", and "long long int" in C++?

This looks confusing because you are taking long as a datatype itself.

long is nothing but just the shorthand for long int when you are using it alone.

long is a modifier, you can use it with double also as long double.

long == long int.

Both of them take 4 bytes.

How to change the size of the radio button using CSS?

try this code... it may be the ans what you exactly looking for

body, html{_x000D_
  height: 100%;_x000D_
  background: #222222;_x000D_
  display: block;_x000D_
  position: relative;_x000D_
  margin: 40px auto;_x000D_
  height: auto;_x000D_
  width: 500px;_x000D_
  padding: 20px;_x000D_
h2 {_x000D_
 color: #AAAAAA;_x000D_
.container ul{_x000D_
  list-style: none;_x000D_
  margin: 0;_x000D_
  padding: 0;_x000D_
 overflow: auto;_x000D_
ul li{_x000D_
  color: #AAAAAA;_x000D_
  display: block;_x000D_
  position: relative;_x000D_
  float: left;_x000D_
  width: 100%;_x000D_
  height: 100px;_x000D_
 border-bottom: 1px solid #333;_x000D_
ul li input[type=radio]{_x000D_
  position: absolute;_x000D_
  visibility: hidden;_x000D_
ul li label{_x000D_
  display: block;_x000D_
  position: relative;_x000D_
  font-weight: 300;_x000D_
  font-size: 1.35em;_x000D_
  padding: 25px 25px 25px 80px;_x000D_
  margin: 10px auto;_x000D_
  height: 30px;_x000D_
  z-index: 9;_x000D_
  cursor: pointer;_x000D_
  -webkit-transition: all 0.25s linear;_x000D_
ul li:hover label{_x000D_
 color: #FFFFFF;_x000D_
ul li .check{_x000D_
  display: block;_x000D_
  position: absolute;_x000D_
  border: 5px solid #AAAAAA;_x000D_
  border-radius: 100%;_x000D_
  height: 25px;_x000D_
  width: 25px;_x000D_
  top: 30px;_x000D_
  left: 20px;_x000D_
 z-index: 5;_x000D_
 transition: border .25s linear;_x000D_
 -webkit-transition: border .25s linear;_x000D_
ul li:hover .check {_x000D_
  border: 5px solid #FFFFFF;_x000D_
ul li .check::before {_x000D_
  display: block;_x000D_
  position: absolute;_x000D_
 content: '';_x000D_
  border-radius: 100%;_x000D_
  height: 15px;_x000D_
  width: 15px;_x000D_
  top: 5px;_x000D_
 left: 5px;_x000D_
  margin: auto;_x000D_
 transition: background 0.25s linear;_x000D_
 -webkit-transition: background 0.25s linear;_x000D_
input[type=radio]:checked ~ .check {_x000D_
  border: 5px solid #0DFF92;_x000D_
input[type=radio]:checked ~ .check::before{_x000D_
  background: #0DFF92;_x000D_
    <input type="radio" id="f-option" name="selector">_x000D_
    <label for="f-option">Male</label>_x000D_
    <div class="check"></div>_x000D_
    <input type="radio" id="s-option" name="selector">_x000D_
    <label for="s-option">Female</label>_x000D_
    <div class="check"><div class="inside"></div></div>_x000D_
    <input type="radio" id="t-option" name="selector">_x000D_
    <label for="t-option">Transgender</label>_x000D_
    <div class="check"><div class="inside"></div></div>_x000D_

Cast int to varchar

I don't have MySQL, but there are RDBMS (Postgres, among others) in which you can use the hack

SELECT id || '' FROM some_table;

The concatenate does an implicit conversion.

Get PostGIS version

Other way to get the minor version is:

SELECT extversion
FROM pg_catalog.pg_extension
WHERE extname='postgis'

Count the items from a IEnumerable<T> without iterating?

IEnumerable cannot count without iterating.

Under "normal" circumstances, it would be possible for classes implementing IEnumerable or IEnumerable<T>, such as List<T>, to implement the Count method by returning the List<T>.Count property. However, the Count method is not actually a method defined on the IEnumerable<T> or IEnumerable interface. (The only one that is, in fact, is GetEnumerator.) And this means that a class-specific implementation cannot be provided for it.

Rather, Count it is an extension method, defined on the static class Enumerable. This means it can be called on any instance of an IEnumerable<T> derived class, regardless of that class's implementation. But it also means it is implemented in a single place, external to any of those classes. Which of course means that it must be implemented in a way that is completely independent of these class' internals. The only such way to do counting is via iteration.

Endless loop in C/C++

The problem with asking this question is that you'll get so many subjective answers that simply state "I prefer this...". Instead of making such pointless statements, I'll try to answer this question with facts and references, rather than personal opinions.

Through experience, we can probably start by excluding the do-while alternatives (and the goto), as they are not commonly used. I can't recall ever seeing them in live production code, written by professionals.

The while(1), while(true) and for(;;) are the 3 different versions commonly existing in real code. They are of course completely equivalent and results in the same machine code.


  • This is the original, canonical example of an eternal loop. In the ancient C bible The C Programming Language by Kernighan and Ritchie, we can read that:

    K&R 2nd ed 3.5:

    for (;;) {

    is an "infinite" loop, presumably to be broken by other means, such as a break or return. Whether to use while or for is largely a matter of personal preference.

    For a long while (but not forever), this book was regarded as canon and the very definition of the C language. Since K&R decided to show an example of for(;;), this would have been regarded as the most correct form at least up until the C standardization in 1990.

    However, K&R themselves already stated that it was a matter of preference.

    And today, K&R is a very questionable source to use as a canonical C reference. Not only is it outdated several times over (not addressing C99 nor C11), it also preaches programming practices that are often regarded as bad or blatantly dangerous in modern C programming.

    But despite K&R being a questionable source, this historical aspect seems to be the strongest argument in favour of the for(;;).

  • The argument against the for(;;) loop is that it is somewhat obscure and unreadable. To understand what the code does, you must know the following rule from the standard:

    ISO 9899:2011

    for ( clause-1 ; expression-2 ; expression-3 ) statement


    Both clause-1 and expression-3 can be omitted. An omitted expression-2 is replaced by a nonzero constant.

    Based on this text from the standard, I think most will agree that it is not only obscure, it is subtle as well, since the 1st and 3rd part of the for loop are treated differently than the 2nd, when omitted.


  • This is supposedly a more readable form than for(;;). However, it relies on another obscure, although well-known rule, namely that C treats all non-zero expressions as boolean logical true. Every C programmer is aware of that, so it is not likely a big issue.

  • There is one big, practical problem with this form, namely that compilers tend to give a warning for it: "condition is always true" or similar. That is a good warning, of a kind which you really don't want to disable, because it is useful for finding various bugs. For example a bug such as while(i = 1), when the programmer intended to write while(i == 1).

    Also, external static code analysers are likely to whine about "condition is always true".


  • To make while(1) even more readable, some use while(true) instead. The consensus among programmers seem to be that this is the most readable form.

  • However, this form has the same problem as while(1), as described above: "condition is always true" warnings.

  • When it comes to C, this form has another disadvantage, namely that it uses the macro true from stdbool.h. So in order to make this compile, we need to include a header file, which may or may not be inconvenient. In C++ this isn't an issue, since bool exists as a primitive data type and true is a language keyword.

  • Yet another disadvantage of this form is that it uses the C99 bool type, which is only available on modern compilers and not backwards compatible. Again, this is only an issue in C and not in C++.

So which form to use? Neither seems perfect. It is, as K&R already said back in the dark ages, a matter of personal preference.

Personally, I always use for(;;) just to avoid the compiler/analyser warnings frequently generated by the other forms. But perhaps more importantly because of this:

If even a C beginner knows that for(;;) means an eternal loop, then who are you trying to make the code more readable for?

I guess that's what it all really boils down to. If you find yourself trying to make your source code readable for non-programmers, who don't even know the fundamental parts of the programming language, then you are only wasting time. They should not be reading your code.

And since everyone who should be reading your code already knows what for(;;) means, there is no point in making it further readable - it is already as readable as it gets.

How to open an elevated cmd using command line for Windows?

Dheeraj Bhaskar's method with Powershell has a missing space in it, alt least for the Windows 10 incarnation of Powershell.

The command line inside his sudo.bat should be

powershell.exe -Command "Start-Process cmd \"/k cd /d %cd% \" -Verb RunAs"

Note the extra space after %cd%


What is the maximum length of a Push Notification alert text?

For regular remote notifications, the maximum size is 4KB (4096 bytes)

###iOS the size limit is 256 bytes, but since the introduction of iOS 8 has changed to 2kb!

With iOS 8, Apple introduced new features that enable some rich new use cases for mobile push notifications — interactive push notifications, third party widgets, and larger (2 KB) payloads. Today, we are pleased to announce support for the new mobile push capabilities announced with iOS 8. We are publishing a new iOS 8 Sample App that demonstrates how these new features can be implemented with SNS, and have also implemented support for larger 2KB payloads.

Understanding `scale` in R

log simply takes the logarithm (base e, by default) of each element of the vector.
scale, with default settings, will calculate the mean and standard deviation of the entire vector, then "scale" each element by those values by subtracting the mean and dividing by the sd. (If you use scale(x, scale=FALSE), it will only subtract the mean but not divide by the std deviation.)

Note that this will give you the same values

   x <- runif(7)

   # Manually scaling
   (x - mean(x)) / sd(x)


iPhone is not available. Please reconnect the device

Going to Window ? Devices and Simulators will give you a better idea of what's going on. In my case, I had to update the iPhone since Xcode updated overnight and stopped supporting my iPhone.

Enter image description here

How do I expand the output display to see more columns of a pandas DataFrame?

import pandas as pd
pd.set_option('display.max_columns', 100)
pd.set_option('display.width', 1000)

SentenceA = "William likes Piano and Piano likes William"
SentenceB = "Sara likes Guitar"
SentenceC = "Mamoosh likes Piano"
SentenceD = "William is a CS Student"
SentenceE = "Sara is kind"
SentenceF = "Mamoosh is kind"

bowA = SentenceA.split(" ")
bowB = SentenceB.split(" ")
bowC = SentenceC.split(" ")
bowD = SentenceD.split(" ")
bowE = SentenceE.split(" ")
bowF = SentenceF.split(" ")

# Creating a set consisted of all words

wordSet = set(bowA).union(set(bowB)).union(set(bowC)).union(set(bowD)).union(set(bowE)).union(set(bowF))
print("Set of all words is: ", wordSet)

# Initiating dictionary with 0 value for all BOWs

wordDictA = dict.fromkeys(wordSet, 0)
wordDictB = dict.fromkeys(wordSet, 0)
wordDictC = dict.fromkeys(wordSet, 0)
wordDictD = dict.fromkeys(wordSet, 0)
wordDictE = dict.fromkeys(wordSet, 0)
wordDictF = dict.fromkeys(wordSet, 0)

for word in bowA:
    wordDictA[word] += 1
for word in bowB:
    wordDictB[word] += 1
for word in bowC:
    wordDictC[word] += 1
for word in bowD:
    wordDictD[word] += 1
for word in bowE:
    wordDictE[word] += 1
for word in bowF:
    wordDictF[word] += 1

# Printing Term frequency

print("SentenceA TF: ", wordDictA)
print("SentenceB TF: ", wordDictB)
print("SentenceC TF: ", wordDictC)
print("SentenceD TF: ", wordDictD)
print("SentenceE TF: ", wordDictE)
print("SentenceF TF: ", wordDictF)

print(pd.DataFrame([wordDictA, wordDictB, wordDictB, wordDictC, wordDictD, wordDictE, wordDictF]))


   CS  Guitar  Mamoosh  Piano  Sara  Student  William  a  and  is  kind  likes
0   0       0        0      2     0        0        2  0    1   0     0      2
1   0       1        0      0     1        0        0  0    0   0     0      1
2   0       1        0      0     1        0        0  0    0   0     0      1
3   0       0        1      1     0        0        0  0    0   0     0      1
4   1       0        0      0     0        1        1  1    0   1     0      0
5   0       0        0      0     1        0        0  0    0   1     1      0
6   0       0        1      0     0        0        0  0    0   1     1      0

XOR operation with two strings in java

the abs function is when the Strings are not the same length so the legth of the result will be the same as the min lenght of the two String a and b

public String xor(String a, String b){
    StringBuilder sb = new StringBuilder();
    for(int k=0; k < a.length(); k++)
       sb.append((a.charAt(k) ^ b.charAt(k + (Math.abs(a.length() - b.length()))))) ;
       return sb.toString();

How to view files in binary from bash?

vi your_filename

hit esc

Type :%!xxd to view the hex strings, the n :%!xxd -r to return to normal editing.

Show hide fragment in android

In addittion, you can do in a Fragment (for example when getting server data failed):


Formatting a Date String in React Native

The beauty of the React Native is that it supports lots of JS libraries like Moment.js. Using moment.js would be a better/easier way to handle date/time instead coding from scratch

just run this in the terminal (yarn add moment also works if using React's built-in package manager):

npm install moment --save

And in your React Native js page:

import Moment from 'moment';

    var dt = '2016-05-02T00:00:00';
    return(<View> {Moment(dt).format('d MMM')} </View>) //basically you can do all sorts of the formatting and others

You may check the moment.js official docs here

Setting a backgroundImage With React Inline Styles

If you are using ES5 -

backgroundImage: "url(" + Background + ")"

If you are using ES6 -

backgroundImage: `url(${Background})`

Basically removing unnecessary curly braces while adding value to backgroundImage property works will work.

Eclipse - "Workspace in use or cannot be created, chose a different one."

Go to TaskManager(Right Click in the Task Bar) and select Processess menu bar and select eclipse.exe and Click EndProcess

Can functions be passed as parameters?

Yes Go does accept first-class functions.

See the article "First Class Functions in Go" for useful links.

Git: How to squash all commits on branch

Another simple way to do this: go on the origin branch and do a merge --squash. This command doesn't do the "squashed" commit. when you do it, all commit messages of yourBranch will be gathered.

$ git checkout master
$ git merge --squash yourBranch
$ git commit # all commit messages of yourBranch in one, really useful
 > [status 5007e77] Squashed commit of the following: ...

How to read fetch(PDO::FETCH_ASSOC);

/* Design Pattern "table-data gateway" */

class Gateway
    protected $connection = null;

    public function __construct()
        $this->connection = new PDO("mysql:host=localhost; dbname=db_users", 'root', '');

    public function loadAll()
        $sql = 'SELECT * FROM users';
        $rows = $this->connection->query($sql);

        return $rows;

    public function loadById($id)
        $sql = 'SELECT * FROM users WHERE user_id = ' . (int) $id;
        $result = $this->connection->query($sql);

        return $result->fetch(PDO::FETCH_ASSOC);
        // //                   

/* Print all row with column 'user_id' only */

$gateway  = new Gateway();
$users    = $gateway->loadAll();

$no = 1;
foreach ($users as $key => $value) {
    echo $no . '. ' . $key . ' => ' . $value['user_id'] . '<br />';

/* Print user_id = 1 with all column */

$user = $gateway->loadById(1);

$no = 1;
foreach ($user as $key => $value) {
    echo $no . '. ' . $key . ' => ' . $value . '<br />';

/* Print user_id = 1 with column 'email and password' */

$user = $gateway->loadById(1);

echo $user['email'];
echo $user['password'];

How to display data from database into textbox, and update it

Wrap your all statements in !IsPostBack condition on page load.

protected void Page_Load(object sender, EventArgs e)
      // all statements

This will fix your issue.

string to string array conversion in java

You could use string.chars().mapToObj(e -> new String(new char[] {e}));, though this is quite lengthy and only works with java 8. Here are a few more methods:

string.split(""); (Has an extra whitespace character at the beginning of the array if used before Java 8) string.split("|"); string.split("(?!^)"); Arrays.toString(string.toCharArray()).substring(1, string.length() * 3 + 1).split(", ");

The last one is just unnecessarily long, it's just for fun!

String in function parameter

char *arr; above statement implies that arr is a character pointer and it can point to either one character or strings of character

& char arr[]; above statement implies that arr is strings of character and can store as many characters as possible or even one but will always count on '\0' character hence making it a string ( e.g. char arr[]= "a" is similar to char arr[]={'a','\0'} )

But when used as parameters in called function, the string passed is stored character by character in formal arguments making no difference.

How do I find the length of an array?

#include <iostream>

int main ()
    using namespace std;
    int arr[] = {2, 7, 1, 111};
    auto array_length = end(arr) - begin(arr);
    cout << "Length of array: " << array_length << endl;

Setting timezone in Python

You can use pytz as well..

import datetime
import pytz
def utcnow():
   datetime.datetime(2020, 8, 15, 14, 45, 19, 182703, tzinfo=<UTC>)



In Mongoose, how do I sort by date? (node.js)

I do this:

Data.find( { $query: { user: req.user }, $orderby: { dateAdded: -1 } } function ( results ) {

This will show the most recent things first.

How can I get query string values in JavaScript?

This is very simple method to get parameter value(query string)

Use gV(para_name) function to retrieve its value

a=a.replace(a.charAt(0),""); //Removes '?'

function gV(x){
  var b=a[i].substr(0,a[i].indexOf("="));
   return a[i].substr(a[i].indexOf("=")+1,a[i].length)}

Regular expression to search multiple strings (Textpad)

If I understand what you are asking, it is a regular expression like this:


This matches the three sets of digit strings at beginning of line only.

Changing the color of an hr element

You could do this :

hr {_x000D_
  border: 1px solid red;_x000D_
<hr />_x000D_
This s a test_x000D_
<hr />

Line break in HTML with '\n'

You could use the <pre> tag

<div class="text">_x000D_

how to pass data in an hidden field from one jsp page to another?

The code from Alex works great. Just note that when you use request.getParameter you must use a request dispatcher

//Pass results back to the client
RequestDispatcher dispatcher =   getServletContext().getRequestDispatcher("TestPages/ServiceServlet.jsp");
dispatcher.forward(request, response);

How to check if a Docker image with a specific tag exist locally?

I usually test the result of docker images -q (as in this script):

if [[ "$(docker images -q myimage:mytag 2> /dev/null)" == "" ]]; then
  # do something

But since docker images only takes REPOSITORY as parameter, you would need to grep on tag, without using -q.

docker images takes tags now (docker 1.8+) [REPOSITORY[:TAG]]

The other approach mentioned below is to use docker inspect.
But with docker 17+, the syntax for images is: docker image inspect (on an non-existent image, the exit status will be non-0)

As noted by iTayb in the comments:

  • The docker images -q method can get really slow on a machine with lots of images. It takes 44s to run on a 6,500 images machine.
  • The docker image inspect returns immediately.

vbscript output to console

You only need to force cscript instead wscript. I always use this template. The function ForceConsole() will execute your vbs into cscript, also you have nice alias to print and scan text.

 Set oWSH = CreateObject("WScript.Shell")
 vbsInterpreter = "cscript.exe"

 Call ForceConsole()

 Function printf(txt)
    WScript.StdOut.WriteLine txt
 End Function

 Function printl(txt)
    WScript.StdOut.Write txt
 End Function

 Function scanf()
    scanf = LCase(WScript.StdIn.ReadLine)
 End Function

 Function wait(n)
    WScript.Sleep Int(n * 1000)
 End Function

 Function ForceConsole()
    If InStr(LCase(WScript.FullName), vbsInterpreter) = 0 Then
        oWSH.Run vbsInterpreter & " //NoLogo " & Chr(34) & WScript.ScriptFullName & Chr(34)
    End If
 End Function

 Function cls()
    For i = 1 To 50
        printf ""
 End Function

 printf " _____ _ _           _____         _    _____         _     _   "
 printf "|  _  |_| |_ ___ ___|     |_ _ _ _| |  |   __|___ ___|_|___| |_ "
 printf "|     | | '_| . |   |   --| | | | . |  |__   |  _|  _| | . |  _|"
 printf "|__|__|_|_,_|___|_|_|_____|_____|___|  |_____|___|_| |_|  _|_|  "
 printf "                                                       |_|     v1.0"
 printl " Enter your name:"
 MyVar = scanf
 printf "Your name is: " & MyVar

Batch file to perform start, run, %TEMP% and delete all

@echo off
RD %TEMP%\. /S /Q

explorer %temp%

This batch can run from anywhere. RD stands for Remove Directory but this can remove both folders and files which available to delete.

Setting Spring Profile variable

For Eclipse, setting variable in the VM arguments would do the trick.

Go to

Right Click Project --> Run as --> Run Configurations --> Arguments

And add your in the VM arguments

How to populate a sub-document in mongoose after creating it?

In order to populate referenced subdocuments, you need to explicitly define the document collection to which the ID references to (like created_by: { type: Schema.Types.ObjectId, ref: 'User' }).

Given this reference is defined and your schema is otherwise well defined as well, you can now just call populate as usual (e.g. populate('comments.created_by'))

Proof of concept code:

// Schema
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var UserSchema = new Schema({
  name: String

var CommentSchema = new Schema({
  text: String,
  created_by: { type: Schema.Types.ObjectId, ref: 'User' }

var ItemSchema = new Schema({
   comments: [CommentSchema]

// Connect to DB and instantiate models    
var db = mongoose.connect('enter your database here');
var User = db.model('User', UserSchema);
var Comment = db.model('Comment', CommentSchema);
var Item = db.model('Item', ItemSchema);

// Find and populate
Item.find({}).populate('comments.created_by').exec(function(err, items) {

Finally note that populate works only for queries so you need to first pass your item into a query and then call it:, item) {
    Item.findOne(item).populate('comments.created_by').exec(function (err, item) {
            status: 'success',
            message: "You have commented on this item",

How to create a box when mouse over text in pure CSS?

You can also do it by toggling between display: block on hover and display:none without hover to produce the effect.

jQuery ui dialog change title after load-callback

I tried to implement the result of Nick which is:

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

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

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

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

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

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

Using Javascript in CSS

I think what you may be thinking of is expressions or "dynamic properties", which are only supported by IE and let you set a property to the result of a javascript expression. Example:

width:expression(document.body.clientWidth > 800? "800px": "auto" );

This code makes IE emulate the max-width property it doesn't support.

All things considered, however, avoid using these. They are a bad, bad thing.

What is Java EE?

Seems like Oracle is now trying to do away with JSPs (replace with Faces) and emulate Spring's REST (JAX-RS) and DI.


Table 2-1 Web-Tier Java EE Technologies

JavaServer Faces technology

A user-interface component framework for web applications that allows you to include UI components (such as fields and buttons) on a XHTML page, called a Facelets page; convert and validate UI component data; save UI component data to server-side data stores; and maintain component state

Expression Language

A set of standard tags used in Facelets pages to refer to Java EE components


Java programming language classes that dynamically process requests and construct responses, usually for HTML pages

Contexts and Dependency Injection for Java EE

A set of contextual services that make it easy for developers to use enterprise beans along with JavaServer Faces technology in web applications

How to get unique values in an array

These days, you can use ES6's Set data type to convert your array to a unique Set. Then, if you need to use array methods, you can turn it back into an Array:

var arr = ["a", "a", "b"];
var uniqueSet = new Set(arr); // {"a", "b"}
var uniqueArr = Array.from(uniqueSet); // ["a", "b"]
//Then continue to use array methods:
uniqueArr.join(", "); // "a, b"

How to append output to the end of a text file

To append a file use >>

echo "hello world"  >> read.txt   
cat read.txt     
echo "hello siva" >> read.txt   
cat read.txt

then the output should be

hello world   # from 1st echo command
hello world   # from 2nd echo command
hello siva

To overwrite a file use >

echo "hello tom" > read.txt
cat read.txt  

then the out put is

hello tom

WAITING at sun.misc.Unsafe.park(Native Method)

unsafe.park is pretty much the same as thread.wait, except that it's using architecture specific code (thus the reason it's 'unsafe'). unsafe is not made available publicly, but is used within java internal libraries where architecture specific code would offer significant optimization benefits. It's used a lot for thread pooling.

So, to answer your question, all the thread is doing is waiting for something, it's not really using any CPU. Considering that your original stack trace shows that you're using a lock I would assume a deadlock is going on in your case.

Yes I know you have almost certainly already solved this issue by now. However, you're one of the top results if someone googles sun.misc.unsafe.park. I figure answering the question may help others trying to understand what this method that seems to be using all their CPU is.

How do I vertical center text next to an image in html/css?

Does "pure HTML/CSS" exclude the use of tables? Because they will easily do what you want:

        <td valign="top"><img src="myImage.jpg" alt="" /></td>
        <td valign="middle">This is my text!</td>

Flame me all you like, but that works (and works in old, janky browsers).

jQuery override default validation error message display (Css) Popup/Tooltip like

If you could provide some reason as to why you need to replace the label with a div, that would certainly help...

Also, could you paste a sample that'd be helpful ( or

How to plot multiple functions on the same figure, in Matplotlib?

To plot multiple graphs on the same figure you will have to do:

from numpy import *
import math
import matplotlib.pyplot as plt

t = linspace(0, 2*math.pi, 400)
a = sin(t)
b = cos(t)
c = a + b

plt.plot(t, a, 'r') # plotting t, a separately 
plt.plot(t, b, 'b') # plotting t, b separately 
plt.plot(t, c, 'g') # plotting t, c separately

enter image description here

How can I inspect the file system of a failed `docker build`?

Debugging build step failures is indeed very annoying.

The best solution I have found is to make sure that each step that does real work succeeds, and adding a check after those that fails. That way you get a committed layer that contains the outputs of the failed step that you can inspect.

A Dockerfile, with an example after the # Run DB2 silent installer line:

# DB2 10.5 Client Dockerfile (Part 1)
# Requires
#   - DB2 10.5 Client for 64bit Linux ibm_data_server_runtime_client_linuxx64_v10.5.tar.gz
#   - Response file for DB2 10.5 Client for 64bit Linux db2rtcl_nr.rsp 
# Using Ubuntu 14.04 base image as the starting point.
FROM ubuntu:14.04

MAINTAINER David Carew <[email protected]>

# DB2 prereqs (also installing sharutils package as we use the utility uuencode to generate password - all others are required for the DB2 Client) 
RUN dpkg --add-architecture i386 && apt-get update && apt-get install -y sharutils binutils libstdc++6:i386 libpam0g:i386 && ln -s /lib/i386-linux-gnu/ /lib/
RUN apt-get install -y libxml2

# Create user db2clnt
# Generate strong random password and allow sudo to root w/o password
RUN  \
   adduser --quiet --disabled-password -shell /bin/bash -home /home/db2clnt --gecos "DB2 Client" db2clnt && \
   echo db2clnt:`dd if=/dev/urandom bs=16 count=1 2>/dev/null | uuencode -| head -n 2 | grep -v begin | cut -b 2-10` | chgpasswd && \
   adduser db2clnt sudo && \
   echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers

# Install DB2
RUN mkdir /install
# Copy DB2 tarball - ADD command will expand it automatically
ADD v10.5fp9_linuxx64_rtcl.tar.gz /install/
# Copy response file
COPY  db2rtcl_nr.rsp /install/
# Run  DB2 silent installer
RUN mkdir /logs
RUN (/install/rtcl/db2setup -t /logs/trace -l /logs/log -u /install/db2rtcl_nr.rsp && touch /install/done) || /bin/true
RUN test -f /install/done || (echo ERROR-------; echo install failed, see files in container /logs directory of the last container layer; echo run docker run '<last image id>' /bin/cat /logs/trace; echo ----------)
RUN test -f /install/done

# Clean up unwanted files
RUN rm -fr /install/rtcl

# Login as db2clnt user
CMD su - db2clnt

ArrayList or List declaration in Java

The first declaration has to be an ArrayList, the second can be easily changed to another List type. As such, the second is preferred as it make it clear you don't require a specific implementation. (Sometimes you really do need one implementation, but that is rare)

How to check if a file exists from inside a batch file

Try something like the following example, quoted from the output of IF /? on Windows XP:

IF EXIST filename. (
    del filename.
) ELSE (
    echo filename. missing.

You can also check for a missing file with IF NOT EXIST.

The IF command is quite powerful. The output of IF /? will reward careful reading. For that matter, try the /? option on many of the other built-in commands for lots of hidden gems.  

Error java.lang.OutOfMemoryError: GC overhead limit exceeded

In Netbeans, it may be helpful to design a max heap size. Go to Run => Set Project Configuration => Customise. In the Run of its popped up window, go to VM Option, fill in -Xms2048m -Xmx2048m. It could solve heap size problem.

Getting value of HTML Checkbox from onclick/onchange events

Use this

<input type="checkbox" onclick="onClickHandler()" id="box" />

function onClickHandler(){
    var chk=document.getElementById("box").value;

    //use this value


Prepare for Segue in Swift

this is one of the ways you can use this function, it is when you want access a variable of another class and change the output based on that variable.

   override func prepare(for segue: UIStoryboardSegue, sender: Any?)  {
        let something = segue.destination as! someViewController
       something.aVariable = anotherVariable

Bridged networking not working in Virtualbox under Windows 10

WINDOWS FIX: Ive' Fixed it by downloading a new VMbox installer from the Official Website Here.

  • Just run the installer and install it to override your current VMBox version, that should fix it.

Dont worry about your VM's they will not disappear if you override your current installation.

NOTE: If you already have the latest version, you need to export all your VM's, unninstall your current VMBox and install it from new installer.

Clearing Magento Log Data

TRUNCATE `log_url_info`;
TRUNCATE `log_visitor_info`;
TRUNCATE `index_event`;
TRUNCATE `log_visitor`;
TRUNCATE `log_url`;
TRUNCATE `report_event`;
TRUNCATE `dataflow_batch_import`;
TRUNCATE `dataflow_batch_export`;

I just use it.

How can I create directories recursively?

Here is my implementation for your reference:

def _mkdir_recursive(self, path):
    sub_path = os.path.dirname(path)
    if not os.path.exists(sub_path):
    if not os.path.exists(path):

Hope this help!

SQL Server add auto increment primary key to existing table

This answer is a small addition to the highest voted answer and works for SQL Server. The question requested an auto increment primary key, the current answer does add the primary key, but it is not flagged as auto-increment. The script below checks for the columns, existence, and adds it with the autoincrement flag enabled.


ALTER TABLE dbo.YourTable
   ADD PKColumnName INT IDENTITY(1,1)




Using Postman to access OAuth 2.0 Google APIs

This is an old question, but it has no chosen answer, and I just solved this problem myself. Here's my solution:

  1. Make sure you are set up to work with your Google API in the first place. See Google's list of prerequisites. I was working with Google My Business, so I also went through it's Get Started process.

  2. In the OAuth 2.0 playground, Step 1 requires you to select which API you want to authenticate. Select or input as applicable for your case (in my case for Google My Business, I had to input into the "Input your own scopes" input field). Note: this is the same as what's described in step 6 of the "Make a simple HTTP request" section of the Get Started guide.

  3. Assuming successful authentication, you should get an "Access token" returned in the "Step 1's result" step in the OAuth playground. Copy this token to your clipboard.

  4. Open Postman and open whichever collection you want as necessary.

  5. In Postman, make sure "GET" is selected as the request type, and click on the "Authorization" tab below the request type drop-down.

  6. In the Authorization "TYPE" dropdown menu, select "Bearer Token"

  7. Paste your previously copied "Access Token" which you copied from the OAuth playground into the "Token" field which displays in Postman.

  8. Almost there! To test if things work, put into the main URL input bar in Postman and click the send button. You should get a JSON list of accounts back in the response that looks something like the following:

        "accounts": [
                "name": "accounts/REDACTED",
                "accountName": "REDACTED",
                "type": "PERSONAL",
                "state": {
                    "status": "UNVERIFIED"
                "name": "accounts/REDACTED",
                "accountName": "REDACTED",
                "type": "LOCATION_GROUP",
                "role": "OWNER",
                "state": {
                    "status": "UNVERIFIED"
                "permissionLevel": "OWNER_LEVEL"

DBNull if statement

This should work.

if (rsData["usr.ursrdaystime"] != System.DBNull.Value))
    strLevel = rsData["usr.ursrdaystime"].ToString();

also need to add using statement, like bellow:

using (var objConn = new SqlConnection(strConnection))
        using (var objCmd = new SqlCommand(strSQL, objConn))
           using (var rsData = objCmd.ExecuteReader())
              while (rsData.Read())
                 if (rsData["usr.ursrdaystime"] != System.DBNull.Value)
                    strLevel = rsData["usr.ursrdaystime"].ToString();

this'll automaticly dispose (close) resources outside of block { .. }.

Javascript logical "!==" operator?

Copied from the formal specification: ECMAScript 5.1 section 11.9.5

11.9.4 The Strict Equals Operator ( === )

The production EqualityExpression : EqualityExpression === RelationalExpression is evaluated as follows:

  1. Let lref be the result of evaluating EqualityExpression.
  2. Let lval be GetValue(lref).
  3. Let rref be the result of evaluating RelationalExpression.
  4. Let rval be GetValue(rref).
  5. Return the result of performing the strict equality comparison rval === lval. (See 11.9.6)

11.9.5 The Strict Does-not-equal Operator ( !== )

The production EqualityExpression : EqualityExpression !== RelationalExpression is evaluated as follows:

  1. Let lref be the result of evaluating EqualityExpression.
  2. Let lval be GetValue(lref).
  3. Let rref be the result of evaluating RelationalExpression.
  4. Let rval be GetValue(rref). Let r be the result of performing strict equality comparison rval === lval. (See 11.9.6)
  5. If r is true, return false. Otherwise, return true.

11.9.6 The Strict Equality Comparison Algorithm

The comparison x === y, where x and y are values, produces true or false. Such a comparison is performed as follows:

  1. If Type(x) is different from Type(y), return false.
  2. Type(x) is Undefined, return true.
  3. Type(x) is Null, return true.
  4. Type(x) is Number, then
    1. If x is NaN, return false.
    2. If y is NaN, return false.
    3. If x is the same Number value as y, return true.
    4. If x is +0 and y is -0, return true.
    5. If x is -0 and y is +0, return true.
    6. Return false.
  5. If Type(x) is String, then return true if x and y are exactly the same sequence of characters (same length and same characters in corresponding positions); otherwise, return false.
  6. If Type(x) is Boolean, return true if x and y are both true or both false; otherwise, return false.
  7. Return true if x and y refer to the same object. Otherwise, return false.

How do I pipe a subprocess call to a text file?

You could also just call the script from the terminal, outputting everything to a file, if that helps. This way:

$ /path/to/the/ > output.txt

This will overwrite the file. You can use >> to append to it.

If you want errors to be logged in the file as well, use &>> or &>.

Remove ListView items in Android

            names = db.getSites();
            la = new ArrayAdapter<String>(EditSiteList.this,
                    android.R.layout.simple_list_item_1, names);

this code works fine for me.

Copying a rsa public key to clipboard

Another alternative solution:

cat  ~/.ssh/ |  xsel -i -b

From man xsel :

-i, --input

read standard input into the selection.

-b, --clipboard

operate on the CLIPBOARD selection.

AngularJS - add HTML element to dom in directive without jQuery

Why not to try simple (but powerful) html() method:

iElement.html('<svg width="600" height="100" class="svg"></svg>');

Or append as an alternative:

iElement.append('<svg width="600" height="100" class="svg"></svg>');

And , of course , more cleaner way:

 var svg = angular.element('<svg width="600" height="100" class="svg"></svg>');


"use database_name" command in PostgreSQL

The basic problem while migrating from MySQL I faced was, I thought of the term database to be same in PostgreSQL also, but it is not. So if we are going to switch the database from our application or pgAdmin, the result would not be as expected. As in my case, we have separate schemas (Considering PostgreSQL terminology here.) for each customer and separate admin schema. So in application, I have to switch between schemas.

For this, we can use the SET search_path command. This does switch the current schema to the specified schema name for the current session.


SET search_path = different_schema_name;

This changes the current_schema to the specified schema for the session. To change it permanently, we have to make changes in postgresql.conf file.

How to make div follow scrolling smoothly with jQuery?

I needed the div to stop when it reach a certain object, so i did it like this:

var el = $('#followdeal');
    var elpos_original = el.offset().top;
        var elpos = el.offset().top;
        var windowpos = $(window).scrollTop();
        var finaldestination = windowpos;
        var stophere = ( $('#filtering').offset().top ) - 170;
        if(windowpos<elpos_original || windowpos>=stophere) {
            finaldestination = elpos_original;
        } else {

Visual Studio debugger error: Unable to start program Specified file cannot be found

I think that what you have to check is:

  1. if the target EXE is correctly configured in the project settings ("command", in the debugging tab). Since all individual projects run when you start debugging it's well possible that only the debugging target for the "ALL" solution is missing, check which project is currently active (you can also select the debugger target by changing the active project).

  2. dependencies (DLLs) are also located at the target debugee directory or can be loaded (you can use the "depends.exe" tool for checking dependencies of an executable or DLL).

How to get the path of src/test/resources directory in JUnit?

Use .getAbsolutePath() on your File object.


unable to start mongodb local server

Andreas Jung:

"Sat Jun 25 09:38:51 [initandlisten] listen(): bind() failed errno:98 Address already in use for socket:

is self-speaking.

Another instance of mongod is already running and allocating the MongoDB default port which is 27017.

Either kill the other process or use a different port."

In this case, type the following command

ps wuax | grep mongo

You should see something that looks like this

User           31936   0.5 0.4 2719784 35624   ?? S     7:34pm   0:09.98 mongod
User           31945   0.0 0.0 2423368   184 s000 R+   8:24pm   0:00.00 grep mongo

Now enter the kill command for the mongod instance (31936 in this case):

kill 31936

MySQL Where DateTime is greater than today

Remove the date() part

SELECT name, datum 
FROM tasks 
WHERE datum >= NOW()

and if you use a specific date, don't forget the quotes around it and use the proper format with :

SELECT name, datum 
FROM tasks 
WHERE datum >= '2014-05-18 15:00:00'

How to delete an array element based on key?

You don't say what language you're using, but looking at that output, it looks like PHP output (from print_r()).
If so, just use unset():


Adding a newline into a string in C#

Based on your replies to everyone else, something like this is what you're looking for.

string file = @"C:\file.txt";
string strToProcess = "fkdfdsfdflkdkfk@dfsdfjk72388389@kdkfkdfkkl@jkdjkfjd@jjjk@";
string[] lines = strToProcess.Split(new char[] { '@' }, StringSplitOptions.RemoveEmptyEntries);

using (StreamWriter writer = new StreamWriter(file))
    foreach (string line in lines)
        writer.WriteLine(line + "@");

What are the rules about using an underscore in a C++ identifier?

The rules to avoid collision of names are both in the C++ standard (see Stroustrup book) and mentioned by C++ gurus (Sutter, etc.).

Personal rule

Because I did not want to deal with cases, and wanted a simple rule, I have designed a personal one that is both simple and correct:

When naming a symbol, you will avoid collision with compiler/OS/standard libraries if you:

  • never start a symbol with an underscore
  • never name a symbol with two consecutive underscores inside.

Of course, putting your code in an unique namespace helps to avoid collision, too (but won't protect against evil macros)

Some examples

(I use macros because they are the more code-polluting of C/C++ symbols, but it could be anything from variable name to class name)

#define _WRONG
#define __WRONG_AGAIN
#define RIGHT_
#define WRONG__WRONG
#define RIGHT_x_RIGHT

Extracts from C++0x draft

From the n3242.pdf file (I expect the final standard text to be similar): Global names [global.names]

Certain sets of names and function signatures are always reserved to the implementation:

— Each name that contains a double underscore _ _ or begins with an underscore followed by an uppercase letter (2.12) is reserved to the implementation for any use.

— Each name that begins with an underscore is reserved to the implementation for use as a name in the global namespace.

But also: User-defined literal suffixes [usrlit.suffix]

Literal suffix identifiers that do not start with an underscore are reserved for future standardization.

This last clause is confusing, unless you consider that a name starting with one underscore and followed by a lowercase letter would be Ok if not defined in the global namespace...

Illegal character in path at index 16

the install directory can't have space. reinstall the software will correct it

What are the ascii values of up down left right?

You can utilzed the special function for activating the navigation for your programming purpose. Below is the sample code for it.

   void Specialkey(int key, int x, int y)
    case GLUT_KEY_UP: 
/*Do whatever you want*/        
    case GLUT_KEY_DOWN: 
/*Do whatever you want*/
    case GLUT_KEY_LEFT:
/*Do whatever you want*/
    case GLUT_KEY_RIGHT:
/*Do whatever you want*/


Add this to your main function


Hope this will to solve the problem!

how to change the dist-folder path in angular-cli after 'ng build'

Another option would be to set the webroot path to the angular cli dist folder. In your Program.cs when configuring the WebHostBuilder just say

.UseWebRoot(Directory.GetCurrentDirectory() + "\\Frontend\\dist")

or whatever the path to your dist dir is.

How to config routeProvider and locationProvider in angularJS?

you could try:

<a href="#/controllerone">Controller One</a>||
<a href="#/controllerTwo">Controller Two</a>||
<a href="#/controllerThree">Controller Three</a>

    <div ng-view=""></div>

What is the difference between Set and List?

List is an ordered sequence of elements whereas Set is a distinct list of elements which is unordered (thank you, Quinn Taylor).


An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list.


A collection that contains no duplicate elements. More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2), and at most one null element. As implied by its name, this interface models the mathematical set abstraction.

JVM option -Xss - What does it do exactly?

Each thread has a stack which used for local variables and internal values. The stack size limits how deep your calls can be. Generally this is not something you need to change.

When to use references vs. pointers

References are cleaner and easier to use, and they do a better job of hiding information. References cannot be reassigned, however. If you need to point first to one object and then to another, you must use a pointer. References cannot be null, so if any chance exists that the object in question might be null, you must not use a reference. You must use a pointer. If you want to handle object manipulation on your own i.e if you want to allocate memory space for an object on the Heap rather on the Stack you must use Pointer

int *pInt = new int; // allocates *pInt on the Heap

What is the difference between ApplicationContext and WebApplicationContext in Spring MVC?

ApplicationContext (Root Application Context) : Every Spring MVC web application has an applicationContext.xml file which is configured as the root of context configuration. Spring loads this file and creates an applicationContext for the entire application. This file is loaded by the ContextLoaderListener which is configured as a context param in web.xml file. And there will be only one applicationContext per web application.

WebApplicationContext : WebApplicationContext is a web aware application context i.e. it has servlet context information. A single web application can have multiple WebApplicationContext and each Dispatcher servlet (which is the front controller of Spring MVC architecture) is associated with a WebApplicationContext. The webApplicationContext configuration file *-servlet.xml is specific to a DispatcherServlet. And since a web application can have more than one dispatcher servlet configured to serve multiple requests, there can be more than one webApplicationContext file per web application.

How to save as a new file and keep working on the original one in Vim?

After save new file press


This is shortcut to alternate file

Can I mask an input text in a bat file?

I wrote an open source program called editenv that replaces my older editv32/editv64 utilities:

The --maskinput (-m) option[*] lets you hide (mask) the typed input and has a configurable character (default character is *); e.g.:

editenv -m -p "Password: " PWD

The --prompt (-p) option lets you specify an input prompt. The above will display a Password: prompt and wait for you to enter something. Typed characters will appear as *. Pressing Ctrl+C will end the program with an exit code of 1223.

Download is here:

[*] Note that the --maskinput (-m) option is not secure -- the entered string is entered as plain-text in the environment. This feature is for convenience only.

How to set up default schema name in JPA configuration?

If you are using (org.springframework.jdbc.datasource.DriverManagerDataSource) in ApplicationContext.xml to specify Database details then use below simple property to specify the schema.

<property name="schema" value="schemaName" />

Simple tool to 'accept theirs' or 'accept mine' on a whole file using git

Try this:

To accept theirs changes: git merge --strategy-option theirs

To accept yours: git merge --strategy-option ours

Multiple separate IF conditions in SQL Server

IF you are checking one variable against multiple condition then you would use something like this Here the block of code where the condition is true will be executed and other blocks will be ignored.

IF(@Var1 Condition1)
      /*Your Code Goes here*/

ELSE IF(@Var1 Condition2)
        /*Your Code Goes here*/ 

    ELSE      --<--- Default Task if none of the above is true
       /*Your Code Goes here*/

If you are checking conditions against multiple variables then you would have to go for multiple IF Statements, Each block of code will be executed independently from other blocks.

IF(@Var1 Condition1)
   /*Your Code Goes here*/

IF(@Var2 Condition1)
   /*Your Code Goes here*/

IF(@Var3 Condition1)
   /*Your Code Goes here*/

After every IF statement if there are more than one statement being executed you MUST put them in BEGIN..END Block. Anyway it is always best practice to use BEGIN..END blocks


Found something in your code some BEGIN END you are missing

ELSE IF(@ID IS NOT NULL AND @ID in (SELECT ID FROM Places))   -- Outer Most Block ELSE IF
     SELECT @MyName = Name ...  
    ...Some stuff....                       
    IF(SOMETHNG_1)         -- IF
        BEGIN TRY               
            UPDATE ....                                                                 
        END TRY

            SELECT ERROR_MESSAGE() AS 'Message' 
            RETURN -1
        END CATCH
                -- END
                 -- BEGIN
        BEGIN TRY
            UPDATE ...                                                      
        END TRY
            SELECT ERROR_MESSAGE() AS 'Message' 
            RETURN -1
        END CATCH   
               -- END
    ELSE                  -- ELSE
            BEGIN TRY
                UPDATE ...                                                              
            END TRY
            BEGIN CATCH
                SELECT ERROR_MESSAGE() AS 'Message' 
                RETURN -1
            END CATCH   
      --The above works I then insert this below and these if statement become nested----
          IF(@A!= @SA)
             exec Store procedure 
                    @FIELD = 15,
                    ... more params...
        IF(@S!= @SS)
             exec Store procedure 
                    @FIELD = 10,
                    ... more params...

How can I remove the search bar and footer added by the jQuery DataTables plugin?

$(document).ready(function() {
        "bPaginate": false,
        "bFilter": false,
        "bInfo": false

in your datatable constructor

How to specify legend position in matplotlib in graph coordinates

According to the matplotlib legend documentation:

The location can also be a 2-tuple giving the coordinates of the lower-left corner of the legend in axes coordinates (in which case bbox_to_anchor will be ignored).

Thus, one could use:

plt.legend(loc=(x, y))

to set the legend's lower left corner to the specified (x, y) position.

How to retry image pull in a kubernetes Pods?

$ kubectl replace --force -f <resource-file>

if all goes well, you should see something like:

<resource-type> <resource-name> deleted
<resource-type> <resource-name> replaced

details of this can be found in the Kubernetes documentation, "manage-deployment" and kubectl-cheatsheet pages at the time of writing.

Vertical (rotated) text in HTML table

After having tried for over two hours, I can safely say that all the method mentioned so far don't work across browsers, or for IE even across browser versions...

For example (top upvoted answer):

 filter:  progid:DXImageTransform.Microsoft.BasicImage(rotation=0.083);  /* IE6,IE7 */
     -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=0.083)"; /* IE8 */

rotates twice in IE9, once for filter, and once for -ms-filter, so...

All other mentioned methods do not work either, at least not if you have to set no fixed height/width of the table header cell (with background color), where it should automatically adjust to size of the highest element.

So to elaborate on the server-side image generation proposed by Nathan Long, which is really the only universially working method, here my VB.NET code for a generic handler (*.ashx ):

Imports System.Web
Imports System.Web.Services

Public Class GenerateImage
    Implements System.Web.IHttpHandler

    Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
        'context.Response.ContentType = "text/plain"
        'context.Response.Write("Hello World!")
        context.Response.ContentType = "image/png"

        Dim strText As String = context.Request.QueryString("text")
        Dim strRotate As String = context.Request.QueryString("rotate")
        Dim strBGcolor As String = context.Request.QueryString("bgcolor")

        Dim bRotate As Boolean = True

        If String.IsNullOrEmpty(strText) Then
            strText = "No Text"
        End If

            If Not String.IsNullOrEmpty(strRotate) Then
                bRotate = System.Convert.ToBoolean(strRotate)
            End If
        Catch ex As Exception

        End Try

        'Dim img As System.Drawing.Image = GenerateImage(strText, "Arial", bRotate)
        'Dim img As System.Drawing.Image = CreateBitmapImage(strText, bRotate)

        ' Generic error in GDI+
        'img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Png)

        'Dim bm As System.Drawing.Bitmap = New System.Drawing.Bitmap(img)
        'bm.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Png)

        Using msTempOutputStream As New System.IO.MemoryStream
            'Dim img As System.Drawing.Image = GenerateImage(strText, "Arial", bRotate)
            Using img As System.Drawing.Image = CreateBitmapImage(strText, bRotate, strBGcolor)
                img.Save(msTempOutputStream, System.Drawing.Imaging.ImageFormat.Png)

                context.Response.Buffer = True
                context.Response.ContentType = "image/png"
            End Using ' img

        End Using ' msTempOutputStream

    End Sub ' ProcessRequest

    Private Function CreateBitmapImage(strImageText As String) As System.Drawing.Image
        Return CreateBitmapImage(strImageText, True)
    End Function ' CreateBitmapImage

    Private Function CreateBitmapImage(strImageText As String, bRotate As Boolean) As System.Drawing.Image
        Return CreateBitmapImage(strImageText, bRotate, Nothing)
    End Function

    Private Function InvertMeAColour(ColourToInvert As System.Drawing.Color) As System.Drawing.Color
        Const RGBMAX As Integer = 255
        Return System.Drawing.Color.FromArgb(RGBMAX - ColourToInvert.R, RGBMAX - ColourToInvert.G, RGBMAX - ColourToInvert.B)
    End Function

    Private Function CreateBitmapImage(strImageText As String, bRotate As Boolean, strBackgroundColor As String) As System.Drawing.Image
        Dim bmpEndImage As System.Drawing.Bitmap = Nothing

        If String.IsNullOrEmpty(strBackgroundColor) Then
            strBackgroundColor = "#E0E0E0"
        End If

        Dim intWidth As Integer = 0
        Dim intHeight As Integer = 0

        Dim bgColor As System.Drawing.Color = System.Drawing.Color.LemonChiffon ' LightGray
        bgColor = System.Drawing.ColorTranslator.FromHtml(strBackgroundColor)

        Dim TextColor As System.Drawing.Color = System.Drawing.Color.Black
        TextColor = InvertMeAColour(bgColor)

        'TextColor = Color.FromArgb(102, 102, 102)

        ' Create the Font object for the image text drawing.
        Using fntThisFont As New System.Drawing.Font("Arial", 11, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Pixel)

            ' Create a graphics object to measure the text's width and height.
            Using bmpInitialImage As New System.Drawing.Bitmap(1, 1)

                Using gStringMeasureGraphics As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(bmpInitialImage)
                    ' This is where the bitmap size is determined.
                    intWidth = CInt(gStringMeasureGraphics.MeasureString(strImageText, fntThisFont).Width)
                    intHeight = CInt(gStringMeasureGraphics.MeasureString(strImageText, fntThisFont).Height)

                    ' Create the bmpImage again with the correct size for the text and font.
                    bmpEndImage = New System.Drawing.Bitmap(bmpInitialImage, New System.Drawing.Size(intWidth, intHeight))

                    ' Add the colors to the new bitmap.
                    Using gNewGraphics As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(bmpEndImage)
                        ' Set Background color
                        gNewGraphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias
                        gNewGraphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias


                        'gNewGraphics.TranslateTransform(bmpEndImage.Width, bmpEndImage.Height)
                        'gNewGraphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SystemDefault

                        gNewGraphics.DrawString(strImageText, fntThisFont, New System.Drawing.SolidBrush(TextColor), 0, 0)


                        If bRotate Then
                            'bmpEndImage = rotateImage(bmpEndImage, 90)
                            'bmpEndImage = RotateImage(bmpEndImage, New PointF(0, 0), 90)
                        End If ' bRotate

                    End Using ' gNewGraphics

                End Using ' gStringMeasureGraphics

            End Using ' bmpInitialImage

        End Using ' fntThisFont

        Return bmpEndImage
    End Function ' CreateBitmapImage

    Public Shared Function GenerateImage_CrappyOldReportingServiceVariant(ByVal strText As String, ByVal strFont As String, bRotate As Boolean) As System.Drawing.Image
        Dim bgColor As System.Drawing.Color = System.Drawing.Color.LemonChiffon ' LightGray
        bgColor = System.Drawing.ColorTranslator.FromHtml("#E0E0E0")

        Dim TextColor As System.Drawing.Color = System.Drawing.Color.Black
        'TextColor = System.Drawing.Color.FromArgb(255, 0, 0, 255)

        If String.IsNullOrEmpty(strFont) Then
            strFont = "Arial"
            If strFont.Trim().Equals(String.Empty) Then
                strFont = "Arial"
            End If
        End If

        'Dim fsFontStyle As System.Drawing.FontStyle = System.Drawing.FontStyle.Regular
        Dim fsFontStyle As System.Drawing.FontStyle = System.Drawing.FontStyle.Bold
        Dim fontFamily As New System.Drawing.FontFamily(strFont)
        Dim iFontSize As Integer = 8 '//Change this as needed

        ' vice-versa, because 270° turn
        'Dim height As Double = 2.25
        Dim height As Double = 4
        Dim width As Double = 1

        ' width = 10
        ' height = 10

        Dim bmpImage As New System.Drawing.Bitmap(1, 1)
        Dim iHeight As Integer = CInt(height * 0.393700787 * bmpImage.VerticalResolution) 'y DPI
        Dim iWidth As Integer = CInt(width * 0.393700787 * bmpImage.HorizontalResolution) 'x DPI

        bmpImage = New System.Drawing.Bitmap(bmpImage, New System.Drawing.Size(iWidth, iHeight))

        '// Create the Font object for the image text drawing.
        'Dim MyFont As New System.Drawing.Font("Arial", iFontSize, fsFontStyle, System.Drawing.GraphicsUnit.Point)
        '// Create a graphics object to measure the text's width and height.
        Dim MyGraphics As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(bmpImage)

        Dim stringFormat As New System.Drawing.StringFormat()
        stringFormat.FormatFlags = System.Drawing.StringFormatFlags.DirectionVertical
        'stringFormat.FormatFlags = System.Drawing.StringFormatFlags.DirectionVertical Or System.Drawing.StringFormatFlags.DirectionRightToLeft
        Dim solidBrush As New System.Drawing.SolidBrush(TextColor)
        Dim pointF As New System.Drawing.PointF(CSng(iWidth / 2 - iFontSize / 2 - 2), 5)
        Dim font As New System.Drawing.Font(fontFamily, iFontSize, fsFontStyle, System.Drawing.GraphicsUnit.Point)

        MyGraphics.TranslateTransform(bmpImage.Width, bmpImage.Height)
        MyGraphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SystemDefault
        MyGraphics.DrawString(strText, font, solidBrush, pointF, stringFormat)


        'If Not bRotate Then
        'End If

        Return bmpImage
    End Function ' GenerateImage

    ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
            Return False
        End Get
    End Property ' IsReusable

End Class

Note that if you think that this part

        Using msTempOutputStream As New System.IO.MemoryStream
            'Dim img As System.Drawing.Image = GenerateImage(strText, "Arial", bRotate)
            Using img As System.Drawing.Image = CreateBitmapImage(strText, bRotate, strBGcolor)
                img.Save(msTempOutputStream, System.Drawing.Imaging.ImageFormat.Png)

                context.Response.Buffer = True
                context.Response.ContentType = "image/png"
            End Using ' img

        End Using ' msTempOutputStream

can be replaced with

img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Png)

because it works on the development server, then you are sorely mistaken to assume the very same code wouldn't throw a Generic GDI+ exception if you deploy it to a Windows 2003 IIS 6 server...

then use it like this:

<img alt="bla" src="GenerateImage.ashx?no_cache=123&text=Hello%20World&rotate=true" />

Conflict with dependency '' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ.

If you using Android Studio 3.1.+ or above

just put this in your gradle depedencies:

implementation ''

Overall like this:

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation ''
    implementation ''
    testImplementation 'junit:junit:4.12'
    androidTestImplementation ''
    androidTestImplementation ''

    implementation ''

What is the non-jQuery equivalent of '$(document).ready()'?

This does not answer the question nor does it show any non-jQuery code. See @ sospedra's answer below.

The nice thing about $(document).ready() is that it fires before window.onload. The load function waits until everything is loaded, including external assets and images. $(document).ready, however, fires when the DOM tree is complete and can be manipulated. If you want to acheive DOM ready, without jQuery, you might check into this library. Someone extracted just the ready part from jQuery. Its nice and small and you might find it useful:

domready at Google Code

How can I show/hide component with JSF?

You should use <h:panelGroup ...> tag with attribute rendered. If you set true to rendered, the content of <h:panelGroup ...> won't be shown. Your XHTML file should have something like this:

<h:panelGroup rendered="#{userBean.showPassword}">
    <h:outputText id="password" value="#{userBean.password}"/>

import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
public class UserBean implements Serializable{
    private boolean showPassword = false;
    private String password = "";

    public boolean isShowPassword(){
        return showPassword;
    public void setPassword(password){
        this.password = password;
    public String getPassword(){
        return this.password;

DataGrid get selected rows' column values

An easy way that works:

private void dataGrid_SelectedCellsChanged(object sender, SelectedCellsChangedEventArgs e)
    foreach (var item in e.AddedCells)
        var col = item.Column as DataGridColumn;
        var fc = col.GetCellContent(item.Item);

        if (fc is CheckBox)
            Debug.WriteLine("Values" + (fc as CheckBox).IsChecked);
        else if(fc is TextBlock)
            Debug.WriteLine("Values" + (fc as TextBlock).Text);
        //// Like this for all available types of cells

Best way to work with transactions in MS SQL Server Management Studio

The easisest thing to do is to wrap your code in a transaction, and then execute each batch of T-SQL code line by line.

For example,

Begin Transaction

         -Do some T-SQL queries here.

Rollback transaction -- OR commit transaction

If you want to incorporate error handling you can do so by using a TRY...CATCH BLOCK. Should an error occur you can then rollback the tranasction within the catch block.

For example:

USE AdventureWorks;

    -- Generate a constraint violation error.
    DELETE FROM Production.Product
    WHERE ProductID = 980;
        ERROR_NUMBER() AS ErrorNumber
        ,ERROR_SEVERITY() AS ErrorSeverity
        ,ERROR_STATE() AS ErrorState
        ,ERROR_PROCEDURE() AS ErrorProcedure
        ,ERROR_LINE() AS ErrorLine
        ,ERROR_MESSAGE() AS ErrorMessage;

    IF @@TRANCOUNT > 0


See the following link for more details.

Hope this helps but please let me know if you need more details.

How to send json data in the Http request using NSURLRequest

Here's an updated example that is using NSURLConnection +sendAsynchronousRequest: (10.7+, iOS 5+), The "Post" request remains the same as with the accepted answer and is omitted here for the sake of clarity:

NSURL *apiURL = [NSURL URLWithString:
    [NSString stringWithFormat:@"", @"someRequest"]];
NSURLRequest *request = [NSURLRequest requestWithURL:apiURL]; // this is using GET, for POST examples see the other answers here on this page
[NSURLConnection sendAsynchronousRequest:request
                                   queue:[NSOperationQueue mainQueue]
                       completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
     if(data.length) {
         NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
         if(responseString && responseString.length) {
             NSLog(@"%@", responseString);

Python: pandas merge multiple dataframes

@everestial007 's solution worked for me. This is how I improved it for my use case, which is to have the columns of each different df with a different suffix so I can more easily differentiate between the dfs in the final merged dataframe.

from functools import reduce
import pandas as pd
dfs = [df1, df2, df3, df4]
suffixes = [f"_{i}" for i in range(len(dfs))]
# add suffixes to each df
dfs = [dfs[i].add_suffix(suffixes[i]) for i in range(len(dfs))]
# remove suffix from the merging column
dfs = [dfs[i].rename(columns={f"date{suffixes[i]}":"date"}) for i in range(len(dfs))]
# merge
dfs = reduce(lambda left,right: pd.merge(left,right,how='outer', on='date'), dfs)

In Python, how do I create a string of n characters in one line of code?

if you just want any letters:

 'a'*10  # gives 'aaaaaaaaaa'

if you want consecutive letters (up to 26):

 ''.join(['%c' % x for x in range(97, 97+10)])  # gives 'abcdefghij'

Programmatically get own phone number in iOS

Update: capability appears to have been removed by Apple on or around iOS 4

Just to expand on an earlier answer, something like this does it for me:

NSString *num = [[NSUserDefaults standardUserDefaults] stringForKey:@"SBFormattedPhoneNumber"];

Note: This retrieves the "Phone number" that was entered during the iPhone's iTunes activation and can be null or an incorrect value. It's NOT read from the SIM card.

At least that does in 2.1. There are a couple of other interesting keys in NSUserDefaults that may also not last. (This is in my app which uses a UIWebView)


and so on.

Not sure what, if anything, the others do.

How to fix a header on scroll

You need some JS to do scroll events. The best way to do this is to set a new CSS class for the fixed position that will get assigned to the relevant div when scrolling goes past a certain point.


<div class="sticky"></div>


.fixed {
    position: fixed;
    top:0; left:0;
    width: 100%; }


  var sticky = $('.sticky'),
      scroll = $(window).scrollTop();

  if (scroll >= 100) sticky.addClass('fixed');
  else sticky.removeClass('fixed');

Example fiddle:

EDIT: Extended example

If the trigger point is unknown but should be whenever the sticky element reaches the top of the screen, offset().top can be used.

var stickyOffset = $('.sticky').offset().top;

  var sticky = $('.sticky'),
      scroll = $(window).scrollTop();

  if (scroll >= stickyOffset) sticky.addClass('fixed');
  else sticky.removeClass('fixed');

Extended example fiddle:

Batch file to copy directories recursively

After reading the accepted answer's comments, I tried the robocopy command, which worked for me (using the standard command prompt from Windows 7 64 bits SP 1):

robocopy source_dir dest_dir /s /e

Dump a NumPy array into a csv file

numpy.savetxt saves an array to a text file.

import numpy
a = numpy.asarray([ [1,2,3], [4,5,6], [7,8,9] ])
numpy.savetxt("foo.csv", a, delimiter=",")

How to fix 'Unchecked runtime.lastError: The message port closed before a response was received' chrome issue?

For those coming here to debug this error in Chrome 73, one possibility is because Chrome 73 onwards disallows cross-origin requests in content scripts.

More reading:


This affects many Chrome extension authors, who now need to scramble to fix the extensions because Chrome thinks "Our data shows that most extensions will not be affected by this change."

(it has nothing to do with your app code)

UPDATE: I fixed the CORs issue but I still see this error. I suspect it is Chrome's fault here.

How to set the size of a column in a Bootstrap responsive table

You could use inline styles and define the width in the <th> tag. Make it so that the sum of the widths = 100%.

        <th style="width:10%">Size</th>
        <th style="width:30%">Bust</th>
        <th style="width:50%">Waist</th>
        <th style="width:10%">Hips</th>

Bootply demo

Typically using inline styles is not ideal, however this does provide flexibility because you can get very specific and granular with exact widths.

Force file download with php using header()

Here is a snippet from me in testing... obviously passing via get to the script may not be the best... should post or just send an id and grab guid from db... anyhow.. this worked. I take the URL and convert it to a path.

// Initialize a file URL to the variable
$file = $_GET['url'];
$file = str_replace(Polepluginforrvms_Plugin::$install_url, $DOC_ROOT.'/pole-permitter/', $file );

$quoted = sprintf('"%s"', addcslashes(basename($file), '"\\'));
$size   = filesize($file);

header( "Content-type: application/octet-stream" );
header( "Content-Disposition: attachment; filename={$quoted}" );
header( "Content-length: " . $size );
header( "Pragma: no-cache" );
header( "Expires: 0" );
readfile( "{$file}" );

Convert XML String to Object

In addition to the other answers here you can naturally use the XmlDocument class, for XML DOM-like reading, or the XmlReader, fast forward-only reader, to do it "by hand".

Command to run a .bat file

"F:\- Big Packets -\kitterengine\Common\Template.bat" maybe prefaced with call (see call /?). Or Cd /d "F:\- Big Packets -\kitterengine\Common\" & Template.bat.

CMD Cheat Sheet

  • Cmd.exe

  • Getting Help

  • Punctuation

  • Naming Files

  • Starting Programs

  • Keys


First thing to remember its a way of operating a computer. It's the way we did it before WIMP (Windows, Icons, Mouse, Popup menus) became common. It owes it roots to CPM, VMS, and Unix. It was used to start programs and copy and delete files. Also you could change the time and date.

For help on starting CMD type cmd /?. You must start it with either the /k or /c switch unless you just want to type in it.

Getting Help

For general help. Type Help in the command prompt. For each command listed type help <command> (eg help dir) or <command> /? (eg dir /?).

Some commands have sub commands. For example schtasks /create /?.

The NET command's help is unusual. Typing net use /? is brief help. Type net help use for full help. The same applies at the root - net /? is also brief help, use net help.

References in Help to new behaviour are describing changes from CMD in OS/2 and Windows NT4 to the current CMD which is in Windows 2000 and later.

WMIC is a multipurpose command. Type wmic /?.


&    seperates commands on a line.

&&    executes this command only if previous command's errorlevel is 0.

||    (not used above) executes this command only if previous command's 
errorlevel is NOT 0

>    output to a file

>>    append output to a file

<    input from a file

2> Redirects command error output to the file specified. (0 is StdInput, 1 is StdOutput, and 2 is StdError)

2>&1 Redirects command error output to the same location as command output. 

|    output of one command into the input of another command

^    escapes any of the above, including itself, if needed to be passed 
to a program

"    parameters with spaces must be enclosed in quotes

+ used with copy to concatenate files. E.G. copy file1+file2 newfile

, used with copy to indicate missing parameters. This updates the files 
modified date. E.G. copy /b file1,,

%variablename% a inbuilt or user set environmental variable

!variablename! a user set environmental variable expanded at execution 
time, turned with SelLocal EnableDelayedExpansion command

%<number> (%1) the nth command line parameter passed to a batch file. %0 
is the batchfile's name.

%* (%*) the entire command line.

%CMDCMDLINE% - expands to the original command line that invoked the
Command Processor (from set /?).

%<a letter> or %%<a letter> (%A or %%A) the variable in a for loop. 
Single % sign at command prompt and double % sign in a batch file.

\\ (\\servername\sharename\folder\file.ext) access files and folders via UNC naming.

: (win.ini:streamname) accesses an alternative steam. Also separates drive from rest of path.

. (win.ini) the LAST dot in a file path separates the name from extension

. (dir .\*.txt) the current directory

.. (cd ..) the parent directory

\\?\ (\\?\c:\windows\win.ini) When a file path is prefixed with \\?\ filename checks are turned off. 

Naming Files

< > : " / \ | Reserved characters. May not be used in filenames.

Reserved names. These refer to devices eg, 

copy filename con 

which copies a file to the console window.


COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, 

LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9



Maximum path length              260 characters
Maximum path length (\\?\)      32,767 characters (approx - some rare characters use 2 characters of storage)
Maximum filename length        255 characters

Starting a Program

See start /? and call /? for help on all three ways.

There are two types of Windows programs - console or non console (these are called GUI even if they don't have one). Console programs attach to the current console or Windows creates a new console. GUI programs have to explicitly create their own windows.

If a full path isn't given then Windows looks in

  1. The directory from which the application loaded.

  2. The current directory for the parent process.

  3. Windows NT/2000/XP: The 32-bit Windows system directory. Use the GetSystemDirectory function to get the path of this directory. The name of this directory is System32.

  4. Windows NT/2000/XP: The 16-bit Windows system directory. There is no function that obtains the path of this directory, but it is searched. The name of this directory is System.

  5. The Windows directory. Use the GetWindowsDirectory function to get the path of this directory.

  6. The directories that are listed in the PATH environment variable.

Specify a program name

This is the standard way to start a program.


In a batch file the batch will wait for the program to exit. When typed the command prompt does not wait for graphical programs to exit.

If the program is a batch file control is transferred and the rest of the calling batch file is not executed.

Use Start command

Start starts programs in non standard ways.

start "" c:\windows\notepad.exe

Start starts a program and does not wait. Console programs start in a new window. Using the /b switch forces console programs into the same window, which negates the main purpose of Start.

Start uses the Windows graphical shell - same as typing in WinKey + R (Run dialog). Try

start shell:cache

Also program names registered under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths can also be typed without specifying a full path.

Also note the first set of quotes, if any, MUST be the window title.

Use Call command

Call is used to start batch files and wait for them to exit and continue the current batch file.

Other Filenames

Typing a non program filename is the same as double clicking the file.


Ctrl + C exits a program without exiting the console window.

For other editing keys type Doskey /?.

  • ? and ? recall commands

  • ESC clears command line

  • F7 displays command history

  • ALT+F7 clears command history

  • F8 searches command history

  • F9 selects a command by number

  • ALT+F10 clears macro definitions

Also not listed

  • Ctrl + ?or? Moves a word at a time

  • Ctrl + Backspace Deletes the previous word

  • Home Beginning of line

  • End End of line

  • Ctrl + End Deletes to end of line

Post form data using HttpWebRequest

Use this code:

internal void SomeFunction() {
    Dictionary<string, string> formField = new Dictionary<string, string>();
    formField.Add("Name", "Henry");
    formField.Add("Age", "21");
    string body = GetBodyStringFromDictionary(formField);
    // output : Name=Henry&Age=21

internal string GetBodyStringFromDictionary(Dictionary<string, string> formField)
    string body = string.Empty;
    foreach (var pair in formField)
        body += $"{pair.Key}={pair.Value}&";   

    // delete last "&"
    body = body.Substring(0, body.Length - 1);

    return body;

How to extract a single value from JSON response?

Extract single value from JSON response Python

Try this

import json
import sys

#load the data into an element
data={"test1" : "1", "test2" : "2", "test3" : "3"}

#dumps the json object into an element
json_str = json.dumps(data)

#load the json to a string
resp = json.loads(json_str)

#print the resp
print (resp)

#extract an element in the response
print (resp['test1'])

How to filter wireshark to see only dns queries that are sent/received from/by my computer?

I would go through the packet capture and see if there are any records that I know I should be seeing to validate that the filter is working properly and to assuage any doubts.

That said, please try the following filter and see if you're getting the entries that you think you should be getting:

dns and ip.dst== or dns and ip.src==