Programs & Examples On #Electronic signature

How to use goto statement correctly

There is not 'goto' in the Java world. The main reason was developers realized that complex codes which had goto would lead to making the code really pathetic and it would be almost impossible to enhance or maintain the code.

However this code could be modified a little and using the concept of continue and break we could make the code work.

    import java.util.*;

public class Factorial 
    public static void main(String[] args) 
        int x = 1;
        int factValue = 1;
        Scanner userInput = new Scanner(;
        restart: while(true){
        System.out.println("Please enter a nonzero, nonnegative value to be factorialized.");
        int factInput = userInput.nextInt();

            System.out.println("Enter a nonzero, nonnegative value to be factorialized.");
            factInput = userInput.nextInt();

        if(x<1)//This is another way of doing what the above while loop does, I just wanted to have some fun.
            System.out.println("The number you entered is not valid. Please try again.");
            continue restart;
        System.out.println(factInput+"! = "+factValue);
        break restart;

ERROR 2003 (HY000): Can't connect to MySQL server on '' (111)

This problem may occur because your MySQL server is not installed and running. To do that start command prompt as admin and enter command:

"C:\Program Files (x86)\MySQL\MySQL Server 5.1\bin\mysqld" --install

If you get "service successfully installed" message then you need to start the MySQL service. To do that: go to Services window (Task Manager -> Services -> Open Services) Search for MySQL and Start it from the top navigation bar. Then if try to open mysql.exe it will work.

EF 5 Enable-Migrations : No context type was found in the assembly

I created a Class in the Models directory called: myData with the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;

namespace Vidly.Models
    public class MyDbContext : DbContext
        public MyDbContext()

rebuilt the app with: control-shift-b

then ran the following in the nuGet Console:

Enable-Migrations -StartUpProjectName Vidly -ContextTypeName Vidly.Models.MyDbContext -Verbose

the Console returned:

Using StartUp project 'Vidly'. Using NuGet project 'Vidly'. Checking if the context targets an existing database... Code First Migrations enabled for project Vidly. Enable-Migrations -StartUpProjectName Vidly -ContextTypeName Vidly.Models.myData -Verbose

And the FrameWork created a Migrations directory and wrote a Configuration.cs template in there with the following code:

namespace Vidly.Migrations
    using System;
    using System.Data.Entity;
    using System.Data.Entity.Migrations;
    using System.Linq;

    internal sealed class Configuration : DbMigrationsConfiguration<Vidly.Models.MyDbContext>
        public Configuration()
            AutomaticMigrationsEnabled = false;

        protected override void Seed(Vidly.Models.MyDbContext context)
            //  This method will be called after migrating to the latest version.

            //  You can use the DbSet<T>.AddOrUpdate() helper extension method 
            //  to avoid creating duplicate seed data.

Find out who is locking a file on a network share

Just in case someone looking for a solution to this for a Windows based system or NAS:

There is a built-in function in Windows that shows you what files on the local computer are open/locked by remote computer (which has the file open through a file share):

  • Select "Manage Computer" (Open "Computer Management")
  • click "Shared Folders"
  • choose "Open Files"

There you can even close the file forcefully.

How to execute logic on Optional if not present?

For those of you who want to execute a side-effect only if an optional is absent

i.e. an equivalent of ifAbsent() or ifNotPresent() here is a slight modification to the great answers already provided.

myOptional.ifPresentOrElse(x -> {}, () -> {
  // logic goes here

merge one local branch into another local branch

To merge one branch into another, such as merging "feature_x" branch into "master" branch:

git checkout master

git merge feature_x

This page is the first result for several search engines when looking for "git merge one branch into another". However, the original question is more specific and special case than the title would suggest.
It is also more complex than both the subject and the search expression. As such, this is a minimal but explanatory answer for the benefit of most visitors.

What's the difference between window.location and document.location in JavaScript?

window.location is the more reliably consistent of the two, considering older browsers.

How do you extract classes' source code from a dll file?

 public async void Decompile(string DllName)
     string destinationfilename = "";

     if (System.IO.File.Exists(DllName))
         destinationfilename = (@helperRoot + System.IO.Path.GetFileName(medRuleBook.Schemapath)).ToLower();
         if (System.IO.File.Exists(destinationfilename))

         System.IO.File.Copy(DllName, @destinationfilename);
        // use dll-> XSD
     var returnVal = await DoProcess(
            @helperRoot + "xsd.exe", "\"" + @destinationfilename + "\"");

     destinationfilename = destinationfilename.Replace(".dll", ".xsd");

     if (System.IO.File.Exists(@destinationfilename))
          // now use XSD
          returnVal =
            await DoProcess(
              @helperRoot + "xsd.exe", "/c /namespace:RuleBook /language:CS " + "\"" + @destinationfilename + "\"");

            if (System.IO.File.Exists(@destinationfilename.Replace(".xsd", ".cs")))
                string getXSD = System.IO.File.ReadAllText(@destinationfilename.Replace(".xsd", ".cs"));

What do two question marks together mean in C#?

It's the null coalescing operator, and quite like the ternary (immediate-if) operator. See also ?? Operator - MSDN.

FormsAuth = formsAuth ?? new FormsAuthenticationWrapper();

expands to:

FormsAuth = formsAuth != null ? formsAuth : new FormsAuthenticationWrapper();

which further expands to:

if(formsAuth != null)
    FormsAuth = formsAuth;
    FormsAuth = new FormsAuthenticationWrapper();

In English, it means "If whatever is to the left is not null, use that, otherwise use what's to the right."

Note that you can use any number of these in sequence. The following statement will assign the first non-null Answer# to Answer (if all Answers are null then the Answer is null):

string Answer = Answer1 ?? Answer2 ?? Answer3 ?? Answer4;

Also it's worth mentioning while the expansion above is conceptually equivalent, the result of each expression is only evaluated once. This is important if for example an expression is a method call with side effects. (Credit to @Joey for pointing this out.)

Where is the default log location for SharePoint/MOSS?

For Sharepoint 2007

C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\LOGS

How to make the background DIV only transparent using CSS


The opacity property of the outer DIV cannot be undone by the inner DIV. If you want to achieve transparency, use rgba or hsla:

Outer div:

background-color: rgba(255, 255, 255, 0.9); /* Color white with alpha 0.9*/

Inner div:

background-color: #FFF; /* Background white, to override the background propery*/

Because you've added filter:alpha(opacity=90) to your question, I assume that you also want a working solution for (older versions of) IE. This should work (-ms- prefix for the newest versions of IE):

/*Padded for readability, you can write the following at one line:*/
filter: progid:DXImageTransform.Microsoft.Gradient(

/*Similarly: */
filter: progid:DXImageTransform.Microsoft.Gradient(

I've used the Gradient filter, starting with the same start- and end-color, so that the background doesn't show a gradient, but a flat colour. The colour format is in the ARGB hex format. I've written a JavaScript snippet to convert relative opacity values to absolute alpha-hex values:

var opacity = .9;
var A_ofARGB = Math.round(opacity * 255).toString(16);
if(A_ofARGB.length == 1) A_ofARGB = "0"+a_ofARGB;
else if(!A_ofARGB.length) A_ofARGB = "00";

Dynamic WHERE clause in LINQ

You could use the Any() extension method. The following seems to work for me.

XStreamingElement root = new XStreamingElement("Results",
                from el in StreamProductItem(file)
                where fieldsToSearch.Any(s => el.Element(s) != null && el.Element(s).Value.Contains(searchTerm))
                select fieldsToReturn.Select(r => (r == "product") ? el : el.Element(r))

Where 'fieldsToSearch' and 'fieldsToReturn' are both List objects.

How to check if an alert exists using WebDriver?

I would suggest to use ExpectedConditions and alertIsPresent(). ExpectedConditions is a wrapper class that implements useful conditions defined in ExpectedCondition interface.

public boolean isAlertPresent(){
    boolean foundAlert = false;
    WebDriverWait wait = new WebDriverWait(driver, 0 /*timeout in seconds*/);
    try {
        foundAlert = true;
    } catch (TimeoutException eTO) {
        foundAlert = false;
    return foundAlert;

Note: this is based on the answer by nilesh, but adapted to catch the TimeoutException which is thrown by the wait.until() method.

Styling twitter bootstrap buttons

For Bootstrap (at least for version 3.1.1) and LESS, you can use this:

.btn-my-custom {
    .button-variant(@color; @background; @border)

This is defined in bootstrap/less/buttons.less.

What causes a java.lang.StackOverflowError

When a function call is invoked by a Java application, a stack frame is allocated on the call stack. The stack frame contains the parameters of the invoked method, its local parameters, and the return address of the method.

The return address denotes the execution point from which, the program execution shall continue after the invoked method returns. If there is no space for a new stack frame then, the StackOverflowError is thrown by the Java Virtual Machine (JVM).

The most common case that can possibly exhaust a Java application’s stack is recursion.

Please Have a look

How to solve StackOverflowError

How to convert datetime to integer in python

This in an example that can be used for example to feed a database key, I sometimes use instead of using AUTOINCREMENT options.

import datetime 

dt =
seq = int(dt.strftime("%Y%m%d%H%M%S"))

How to alias a table in Laravel Eloquent queries (or using Query Builder)?

Same as AMIB answer, for soft delete error "Unknown column 'table_alias.deleted_at'", just add ->withTrashed() then handle it yourself like ->whereRaw('items_alias.deleted_at IS NULL')

C++ error 'Undefined reference to Class::Function()'

What are you using to compile this? If there's an undefined reference error, usually it's because the .o file (which gets created from the .cpp file) doesn't exist and your compiler/build system is not able to link it.

Also, in your card.cpp, the function should be Card::Card() instead of void Card. The Card:: is scoping; it means that your Card() function is a member of the Card class (which it obviously is, since it's the constructor for that class). Without this, void Card is just a free function. Similarly,

void Card(Card::Rank rank, Card::Suit suit)

should be

Card::Card(Card::Rank rank, Card::Suit suit)

Also, in deck.cpp, you are saying #include "Deck.h" even though you referred to it as deck.h. The includes are case sensitive.

Removing carriage return and new-line from the end of a string in c#

This should work ...

var tst = "12345\n\n\r\n\r\r";
var res = tst.TrimEnd( '\r', '\n' );

Which font is used in Visual Studio Code Editor and how to change fonts?

In VSCode if "editor.fontFamily": "" is blank, the font size will NOT work. Set a font family to change the size.

"editor.fontFamily": "Verdana", or "editor.fontFamily": "Monaco",

Really, use whatever font family you like.

Then "editor.fontSize": 16, should work.

How to run script as another user without password?

Call visudo and add this:

user1 ALL=(user2) NOPASSWD: /home/user2/bin/

The command paths must be absolute! Then call sudo -u user2 /home/user2/bin/ from a user1 shell. Done.

Protractor : How to wait for page complete after click a button?

Use this I think it's better




For you to use this setting of isAngularSite should put this in your protractor.conf.js here:

        global.isAngularSite = function(flag) {
        browser.ignoreSynchronization = !flag;

Laravel PDOException SQLSTATE[HY000] [1049] Unknown database 'forge'

I did all of them but didn't work, I find out should stop php artisan serve(Ctrl + C) and start php artisan serve again.

How to show form input fields based on select value?

Demo on JSFiddle

$(document).ready(function () {
    toggleFields(); // call this first so we start out with the correct visibility depending on the selected form values
    // this will call our toggleFields function every time the selection value of our other field changes
    $("#dbType").change(function () {

// this toggles the visibility of other server
function toggleFields() {
    if ($("#dbType").val() === "other")


    <p>Choose type</p>
        <select id="dbType" name="dbType">
          <option>Choose Database Type</option>
          <option value="oracle">Oracle</option>
          <option value="mssql">MS SQL</option>
          <option value="mysql">MySQL</option>
          <option value="other">Other</option>
    <div id="otherServer">
            <input type="text" name="server_name" />
            <input type="text" name="port_no" />
    <p align="center">
        <input type="submit" value="Submit!" />

Check if enum exists in Java

I don't think there's a built-in way to do it without catching exceptions. You could instead use something like this:

public static MyEnum asMyEnum(String str) {
    for (MyEnum me : MyEnum.values()) {
        if (
            return me;
    return null;

Edit: As Jon Skeet notes, values() works by cloning a private backing array every time it is called. If performance is critical, you may want to call values() only once, cache the array, and iterate through that.

Also, if your enum has a huge number of values, Jon Skeet's map alternative is likely to perform better than any array iteration.

How to diff a commit with its parent?

Uses aliases, so doesn't answer your question exactly but I find these useful for doing what you intend...

alias gitdiff-1="git log --reverse|grep commit|cut -d ' ' -f2|tail -n 2|head -n 2|xargs echo|sed -e 's/\s/../'|xargs -n 1 git diff"
alias gitdiff-2="git log --reverse|grep commit|cut -d ' ' -f2|tail -n 3|head -n 2|xargs echo|sed -e 's/\s/../'|xargs -n 1 git diff"
alias gitdiff-3="git log --reverse|grep commit|cut -d ' ' -f2|tail -n 4|head -n 2|xargs echo|sed -e 's/\s/../'|xargs -n 1 git diff"

alias gitlog-1="git log --reverse|grep commit|cut -d ' ' -f2|tail -n 2|head -n 2|xargs echo|sed -e 's/\s/../'|xargs -n 1 git log --summary"
alias gitlog-2="git log --reverse|grep commit|cut -d ' ' -f2|tail -n 3|head -n 2|xargs echo|sed -e 's/\s/../'|xargs -n 1 git log --summary"
alias gitlog-3="git log --reverse|grep commit|cut -d ' ' -f2|tail -n 4|head -n 2|xargs echo|sed -e 's/\s/../'|xargs -n 1 git log --summary"

Run-time error '1004' - Method 'Range' of object'_Global' failed


Range(DataImportColumn & DataImportRow).Offset(0, 2).Value



When you just have the row and the column then you can use the cells() object. The syntax is Cells(Row,Column)

Also one more tip. You might want to fully qualify your Cells object. for example


Subset dataframe by multiple logical conditions of rows to remove

data <- data[-which(data[,1] %in% c("b","d","e")),]

Java generics - get class?

I'm able to get the Class of the generic type this way:

class MyList<T> {
  Class<T> clazz = (Class<T>) DAOUtil.getTypeArguments(MyList.class, this.getClass()).get(0);

You need two functions from this file:

For more explanation:

Reading file line by line (with space) in Unix Shell scripting - Issue

Try this,

while read line
    echo $line
done < file.txt


From man bash

IFS - The Internal Field Separator that is used for word
splitting after expansion and to split lines into words
with  the  read  builtin  command. The default value is

HTML input file selection event not firing upon selecting the same file

<form enctype='multipart/form-data'>
    <input onchange="alert(this.value); this.value=null; return false;" type='file'>
    <input type='submit' value='Upload'>

this.value=null; is only necessary for Chrome, Firefox will work fine just with return false;

Here is a FIDDLE

Removing padding gutter from grid columns in Bootstrap 4

Bootstrap4: Comes with .no-gutters out of the box. source:


Requires custom CSS.

Stylesheet: {
  margin-right: 0;
  margin-left: 0;

  & > [class^="col-"],
  & > [class*=" col-"] {
    padding-right: 0;
    padding-left: 0;

Then to use:

<div class="row no-gutters">
  <div class="col-xs-4">...</div>
  <div class="col-xs-4">...</div>
  <div class="col-xs-4">...</div>

It will:

  • Remove margin from the row
  • Remove padding from all columns directly beneath the row

Jquery check if element is visible in viewport

var visible = $(".media").visible();

Store boolean value in SQLite

SQLite Boolean Datatype:
SQLite does not have a separate Boolean storage class. Instead, Boolean values are stored as integers 0 (false) and 1 (true).

You can convert boolean to int in this way:

int flag = (boolValue)? 1 : 0;

You can convert int back to boolean as follows:

 // Select COLUMN_NAME  values from db. 
 // This will be integer value, you can convert this int value back to Boolean as follows
Boolean flag2 = (intValue == 1)? true : false;

If you want to explore sqlite, here is a tutorial.
I have given one answer here. It is working for them.

How to draw a circle with text in the middle?

I was combining some answers from other people and with float and relative it gave me the result I needed.

In HTML I use a div. I use it inside a li for a navigation bar.

.large-list-style {
    float: left;
    position: relative;
    top: -8px;

    border-radius: 50%;

    margin-right: 8px;

    background-color: rgb(34, 198, 200);

    font-size: 18px;
    color: white;
    .large-list-style:after {
        content: '\200B';

        padding-top: 50%;
        padding-bottom: 50%;
    .large-list-style:before {
        padding-left: 16px;
    .large-list-style:after {
        padding-right: 16px;

Submit a form in a popup, and then close the popup

I have executed the code in my machine its working for IE and FF also.

function closeSelf(){
    // do something

    if(condition satisfied){
       alert("conditions satisfied, submiting the form.");
       alert("conditions not satisfied, returning to form");    

<form action="/system/wpacert" method="post" enctype="multipart/form-data" name="certform">
       <div>Certificate 1: <input type="file" name="cert1"/></div>
       <div>Certificate 2: <input type="file" name="cert2"/></div>
       <div>Certificate 3: <input type="file" name="cert3"/></div>

       // change the submit button to normal button
       <div><input type="button" value="Upload"  onclick="closeSelf();"/></div>

How to configure socket connect timeout

I had the Same problem when connecting to a Socket and I came up with the below solution ,It works Fine for me. `

private bool CheckConnectivityForProxyHost(string hostName, int port)
           if (string.IsNullOrEmpty(hostName))
               return false;

           bool isUp = false;
           Socket testSocket = null;


               testSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
               IPAddress ip = null;
               if (testSocket != null && NetworkingCollaboratorBase.GetResolvedConnecionIPAddress(hostName, out ip))//Use a method to resolve your IP
                   IPEndPoint ipEndPoint = new IPEndPoint(ip, port);

                   isUp = false;
//time out 5 Sec
                  CallWithTimeout(ConnectToProxyServers, 5000, testSocket, ipEndPoint);

                       if (testSocket != null && testSocket.Connected)
                           isUp = true;

           catch (Exception ex)
               isUp = false;
                   if (testSocket != null)
               catch (Exception ex)

                   if (testSocket != null)


           return isUp;

 private void CallWithTimeout(Action<Socket, IPEndPoint> action, int timeoutMilliseconds, Socket socket, IPEndPoint ipendPoint)
               Action wrappedAction = () =>
                   action(socket, ipendPoint);

               IAsyncResult result = wrappedAction.BeginInvoke(null, null);

               if (result.AsyncWaitHandle.WaitOne(timeoutMilliseconds))

           catch (Exception ex)


  private void ConnectToProxyServers(Socket testSocket, IPEndPoint ipEndPoint)
               if (testSocket == null || ipEndPoint == null)


           catch (Exception ex)


Docker can't connect to docker daemon

I have the same error and trying docker-machine regenerate-certs or eval.. did not work for me.

This on OS X 10.11.3 (El Capitan) and Docker v1.10.1. I was able to fix it only by deleting and recreating docker-machine again. Source

If running docker-machine ls, it shows you a similar output to the one below;




Unable to query docker version: Cannot connect to the docker engine endpoint

Try removing your Docker machine with;

docker-machine rm -f default

Where default is your Docker machine name. Then;

docker-machine create -d virtualbox default

Creates a new Docker machine.

Double check that everything looks normal now (no errors or unknown Docker) with:

docker-machine ls

Finally don't forget to run "$(docker-machine env default)" before you continue or run the Docker Quickstart Terminal which does it for you...

JVM property -Dfile.encoding=UTF8 or UTF-8?

It will be:


See here for the definitions.

How to make a simple image upload using Javascript/HTML

Try this, It supports multi file uploading,

$('#multi_file_upload').change(function(e) {
    var file_id =;

    var file_name_arr = new Array();
    var process_path = site_url + 'public/uploads/';

    for (i = 0; i < $("#" + file_id).prop("files").length; i++) {

        var form_data = new FormData();
        var file_data = $("#" + file_id).prop("files")[i];
        form_data.append("file_name", file_data);

        if (check_multifile_logo($("#" + file_id).prop("files")[i]['name'])) {
                //url         :   site_url + "inc/upload_image.php?width=96&height=60&show_small=1",
                url: site_url + "inc/upload_contact_info.php",
                cache: false,
                contentType: false,
                processData: false,
                async: false,
                data: form_data,
                type: 'post',
                success: function(data) {
                    // display image
        } else {
            $("#" + html_div).html('');
            alert('We only accept JPG, JPEG, PNG, GIF and BMP files');


function check_multifile_logo(file) {
    var extension = file.substr((file.lastIndexOf('.') + 1))
    if (extension === 'jpg' || extension === 'jpeg' || extension === 'gif' || extension === 'png' || extension === 'bmp') {
        return true;
    } else {
        return false;

Here #multi_file_upload is the ID of image upload field.

How to allow access outside localhost

For the problem was Firewall. If you are on Windows, make sure node is allowed through enter image description here

destination path already exists and is not an empty directory

Steps to get this error ;

  1. Clone a repo (for eg take name as xyz)in a folder
  2. Not try to clone again in the same folder . Even after deleting the folder manually this error will come since deleting folder doesn't delete git info .

Solution : rm -rf "name of repo folder which in out case is xyz" . So

rm -rf xyz

How to troubleshoot an "AttributeError: __exit__" in multiproccesing in Python?

The error also happens when trying to use the

with multiprocessing.Pool() as pool:
   # ...

with a Python version that is too old (like Python 2.X) and does not support using with together with multiprocessing pools.

(See this answer to another question for more details)

What is the use of "object sender" and "EventArgs e" parameters?

Those two parameters (or variants of) are sent, by convention, with all events.

  • sender: The object which has raised the event
  • e an instance of EventArgs including, in many cases, an object which inherits from EventArgs. Contains additional information about the event, and sometimes provides ability for code handling the event to alter the event somehow.

In the case of the events you mentioned, neither parameter is particularly useful. The is only ever one page raising the events, and the EventArgs are Empty as there is no further information about the event.

Looking at the 2 parameters separately, here are some examples where they are useful.


Say you have multiple buttons on a form. These buttons could contain a Tag describing what clicking them should do. You could handle all the Click events with the same handler, and depending on the sender do something different

private void HandleButtonClick(object sender, EventArgs e)
    Button btn = (Button)sender;
    if(btn.Tag == "Hello")
    else if(btn.Tag == "Goodbye")
    // etc.

Disclaimer : That's a contrived example; don't do that!


Some events are cancelable. They send CancelEventArgs instead of EventArgs. This object adds a simple boolean property Cancel on the event args. Code handling this event can cancel the event:

private void HandleCancellableEvent(object sender, CancelEventArgs e)
    if(/* some condition*/)
       // Cancel this event
       e.Cancel = true;

Date minus 1 year?

an easiest way which i used and worked well

date('Y-m-d', strtotime('-1 year'));

this worked perfect.. hope this will help someone else too.. :)

Maven plugins can not be found in IntelliJ

For me which worked is putting the repository which contained the plugin under pluginRepository tags. Example,


WPF MVVM: How to close a window

There is a useful behavior for this task which doesn't break MVVM, a Behavior, introduced with Expression Blend 3, to allow the View to hook into commands defined completely within the ViewModel.

This behavior demonstrates a simple technique for allowing the ViewModel to manage the closing events of the View in a Model-View-ViewModel application.

This allows you to hook up a behavior in your View (UserControl) which will provide control over the control's Window, allowing the ViewModel to control whether the window can be closed via standard ICommands.

Using Behaviors to Allow the ViewModel to Manage View Lifetime in M-V-VM

Above link has been archived to

How does numpy.histogram() work?

Another useful thing to do with numpy.histogram is to plot the output as the x and y coordinates on a linegraph. For example:

arr = np.random.randint(1, 51, 500)
y, x = np.histogram(arr, bins=np.arange(51))
fig, ax = plt.subplots()
ax.plot(x[:-1], y)

enter image description here

This can be a useful way to visualize histograms where you would like a higher level of granularity without bars everywhere. Very useful in image histograms for identifying extreme pixel values.

Export from pandas to_excel without row names (index)?

You need to set index=False in to_excel in order for it to not write the index column out, this semantic is followed in other Pandas IO tools, see and

LISTAGG in Oracle to return distinct values

Further refining @YoYo's correction to @a_horse_with_no_name's row_number() based approach using DECODE vs CASE (i saw here). I see that @Martin Vrbovsky also has this case approach answer.

  listagg(col2, ',') within group (order by col2) AS col2_list,
  listagg(col3, ',') within group (order by col3) AS col3_list,
  SUM(col4) AS col4
from (
    decode(row_number() over (partition by col1, col2 order by null),1,col2) as col2,
    decode(row_number() over (partition by col1, col3 order by null),1,col3) as col3
  from foo
group by col1;

Get local href value from anchor (a) tag

document.getElementById("aaa").href; //for example:

Pass variables from servlet to jsp

Besides using an attribute to pass information from a servlet to a JSP page, one can also pass a parameter. That is done simply by redirecting to a URL that specifies the JSP page in question, and adding the normal parameter-passing-through-the-URL mechanism.

An example. The relevant part of the servlet code:

protected void doGet( HttpServletRequest request, HttpServletResponse response )
throws ServletException, IOException
    response.setContentType( "text/html" );
    // processing the request not shown...
    // here we decide to send the value "bar" in parameter
    // "foo" to the JSP page example.jsp:
    response.sendRedirect( "example.jsp?foo=bar" );

And the relevant part of JSP page example.jsp:

    String fooParameter = request.getParameter( "foo" );
    if ( fooParameter == null )
    <p>No parameter foo given to this page.</p>
    <p>The value of parameter foo is <%= fooParameter.toString() %>.</p>

How to get all options in a drop-down list by Selenium WebDriver using C#?

Select select = new Select(driver.findElement("searchDropdownBox")));

select.getOptions();//will get all options as List<WebElement>

RequiredIf Conditional Validation Attribute

The main difference from other solutions here is that this one reuses logic in RequiredAttribute on the server side, and uses required's validation method depends property on the client side:

public class RequiredIf : RequiredAttribute, IClientValidatable
    public string OtherProperty { get; private set; }
    public object OtherPropertyValue { get; private set; }

    public RequiredIf(string otherProperty, object otherPropertyValue)
        OtherProperty = otherProperty;
        OtherPropertyValue = otherPropertyValue;

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        PropertyInfo otherPropertyInfo = validationContext.ObjectType.GetProperty(OtherProperty);
        if (otherPropertyInfo == null)
            return new ValidationResult($"Unknown property {OtherProperty}");

        object otherValue = otherPropertyInfo.GetValue(validationContext.ObjectInstance, null);
        if (Equals(OtherPropertyValue, otherValue)) // if other property has the configured value
            return base.IsValid(value, validationContext);

        return null;

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
        var rule = new ModelClientValidationRule();
        rule.ErrorMessage = FormatErrorMessage(metadata.GetDisplayName());
        rule.ValidationType = "requiredif"; // data-val-requiredif
        rule.ValidationParameters.Add("other", OtherProperty); // data-val-requiredif-other
        rule.ValidationParameters.Add("otherval", OtherPropertyValue); // data-val-requiredif-otherval

        yield return rule;

$.validator.unobtrusive.adapters.add("requiredif", ["other", "otherval"], function (options) {
    var value = {
        depends: function () {
            var element = $(options.form).find(":input[name='" + options.params.other + "']")[0];
            return element && $(element).val() == options.params.otherval;
    options.rules["required"] = value;
    options.messages["required"] = options.message;

Escape a string for a sed replace pattern

If the case happens to be that you are generating a random password to pass to sed replace pattern, then you choose to be careful about which set of characters in the random string. If you choose a password made by encoding a value as base64, then there is is only character that is both possible in base64 and is also a special character in sed replace pattern. That character is "/", and is easily removed from the password you are generating:

# password 32 characters log, minus any copies of the "/" character.
pass=`openssl rand -base64 32 | sed -e 's/\///g'`;

How to calculate distance from Wifi router using Signal Strength?

Distance (km) = 10^((Free Space Path Loss – 92.45 – 20log10(f))/20)

What is Dispatcher Servlet in Spring?

Dispatcher Controller are displayed in the figure all the incoming request is in intercepted by the dispatcher servlet that works as front controller. The dispatcher servlet gets an entry to handler mapping from the XML file and forwords the request to the Controller.

How to use ternary operator in razor (specifically on HTML attributes)?

You can also use this method:

<input type="text" class="@(@mvccondition ? "true-class" : "false-class")">

Try this .. Good luck Thanks.

How to connect to LocalDb

I think you hit the same issue as discussed in this post. You forgot to escape your \ character.

How to install popper.js with Bootstrap 4?

I had problems installing it Bootstrap as well, so I did:

Install popper.js: npm install popper.js@^1.12.3 --save

Install jQuery: npm install [email protected] --save

Then I had a high severity vulnerability message when installing [email protected] and got this message:

run npm audit fix to fix them, or npm audit for details

So I did npm audit fix, and after another npm audit fix --force it successfully installed!

Python Write bytes to file

Write bytes and Create the file if not exists:

f = open('./put/your/path/here.png', 'wb')

wb means open the file in write binary mode.

Sublime text 3. How to edit multiple lines?

Select multiple lines by clicking first line then holding shift and clicking last line. Then press:


or on MAC: CMD+SHIFT+L (as per comments)

Alternatively you can select lines and go to SELECTION MENU >> SPLIT INTO LINES.

Now you can edit multiple lines, move cursors etc. for all selected lines.

setting textColor in TextView in layout/main.xml main layout file not referencing colors.xml file. (It wants a #RRGGBB instead of @color/text_color)

You have a typo in your xml; it should be:


that's "@color" without the 's'.

Cannot redeclare function php

Remove the function and check the output of:


In which case, change the name of the function.

If you get false, you're including the file with that function twice, replace :




And replace :




EDIT : I'm just a little too late, post before beat me to it !

Add Keypair to existing EC2 instance

For Elasticbeanstalk environments, you can apply a key-value pair to a running instance like this:

  • Create a key-value pair from EC2 -> Key Pairs (Under NETWORK & SECURITY tab)
  • Go to Elasticbeanstalk and click on your application
  • Go to configuration page and modify security settings
  • Choose your EC2 key pair and click Apply
  • Click confirm to confirm the update. It will terminate the environment and apply the key value to your environment.

App store link for "rate/review this app"

All previous links no more direct to "Reviews" tab,

This link would direct to "Reviews Tab" directly: ?

or ?


Repeat command automatically in Linux

To minimize drift more easily, use:

while :; do sleep 1m & some-command; wait; done

there will still be a tiny amount of drift due to bash's time to run the loop structure and the sleep command to actually execute.

hint: ':' evals to 0 ie true.

select unique rows based on single distinct column

If you are using MySql 5.7 or later, according to these links (MySql Official, SO QA), we can select one record per group by with out the need of any aggregate functions.

So the query can be simplified to this.

select * from comments_table group by commentname;

Try out the query in action here

How do you join on the same table, twice, in mysql?

you'd use another join, something along these lines:

SELECT toD.dom_url AS ToURL, 
    fromD.dom_url AS FromUrl, 

FROM reviews AS rvw

LEFT JOIN domain AS toD 
    ON toD.Dom_ID = rvw.rev_dom_for

LEFT JOIN domain AS fromD 
    ON fromD.Dom_ID = rvw.rev_dom_from


All you're doing is joining in the table multiple times. Look at the query in the post: it selects the values from the Reviews tables (aliased as rvw), that table provides you 2 references to the Domain table (a FOR and a FROM).

At this point it's a simple matter to left join the Domain table to the Reviews table. Once (aliased as toD) for the FOR, and a second time (aliased as fromD) for the FROM.

Then in the SELECT list, you will select the DOM_URL fields from both LEFT JOINS of the DOMAIN table, referencing them by the table alias for each joined in reference to the Domains table, and alias them as the ToURL and FromUrl.

For more info about aliasing in SQL, read here.

Compare two dates with JavaScript

The Date object will do what you want - construct one for each date, then compare them using the >, <, <= or >=.

The ==, !=, ===, and !== operators require you to use date.getTime() as in

var d1 = new Date();
var d2 = new Date(d1);
var same = d1.getTime() === d2.getTime();
var notSame = d1.getTime() !== d2.getTime();

to be clear just checking for equality directly with the date objects won't work

var d1 = new Date();
var d2 = new Date(d1);

console.log(d1 == d2);   // prints false (wrong!) 
console.log(d1 === d2);  // prints false (wrong!)
console.log(d1 != d2);   // prints true  (wrong!)
console.log(d1 !== d2);  // prints true  (wrong!)
console.log(d1.getTime() === d2.getTime()); // prints true (correct)

I suggest you use drop-downs or some similar constrained form of date entry rather than text boxes, though, lest you find yourself in input validation hell.

Build Android Studio app via command line

For Mac use this command

  ./gradlew task-name

Sort an array of objects in React and render them, b) => a.item.timeM > b.item.timeM).map(
    (item, i) => <div key={i}> {item.matchID} {item.timeM} {item.description}</div>

Soft keyboard open and close listener in an activity in Android

when keyboard show

rootLayout.getHeight() < rootLayout.getRootView().getHeight() - getStatusBarHeight() 

is true,else hide

How to change MySQL column definition?

This should do it:

ALTER TABLE test MODIFY locationExpert VARCHAR(120) 

How do I concatenate strings with variables in PowerShell?

Try this

Get-ChildItem  | % { Write-Host "$($_.FullName)\$buildConfig\$($_.Name).dll" }

In your code,

  1. $build-Config is not a valid variable name.
  2. $.FullName should be $_.FullName
  3. $ should be $_.Name

How do you compare two version Strings in Java?

I wrote an Open Source Library called MgntUtils that has a utility that works with String versions. It correctly compares them, works with version ranges and so forth. Here is this library javadoc See methods TextUtils.comapreVersions(...). It has been heavily used and well tested. Here is the article that describes the library and where to get it. It is available as Maven artifact and on the github (with sources and JavaDoc)

Binary Data in JSON String. Something better than Base64

Since you're looking for the ability to shoehorn binary data into a strictly text-based and very limited format, I think Base64's overhead is minimal compared to the convenience you're expecting to maintain with JSON. If processing power and throughput is a concern, then you'd probably need to reconsider your file formats.

Read tab-separated file line into array

You could also try,


animals=`cat animals.txt`

for animal in $animalArray
    echo $animal


How to access to the parent object in c#

I would give the parent an ID, and store the parentID in the child object, so that you can pull information about the parent as needed without creating a parent-owns-child/child-owns-parent loop.

Using JQuery to check if no radio button in a group has been checked

I'm using


And will return FALSE if all the items in the radiogroup are unchecked and TRUE if an item is checked.

Download image from the site in .NET/C#

I have used Fredrik's code above in a project with some slight modifications, thought I'd share:

private static bool DownloadRemoteImageFile(string uri, string fileName)
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    HttpWebResponse response;
        response = (HttpWebResponse)request.GetResponse();
    catch (Exception)
        return false;

    // Check that the remote file was found. The ContentType
    // check is performed since a request for a non-existent
    // image file might be redirected to a 404-page, which would
    // yield the StatusCode "OK", even though the image was not
    // found.
    if ((response.StatusCode == HttpStatusCode.OK ||
        response.StatusCode == HttpStatusCode.Moved ||
        response.StatusCode == HttpStatusCode.Redirect) &&
        response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))

        // if the remote file was found, download it
        using (Stream inputStream = response.GetResponseStream())
        using (Stream outputStream = File.OpenWrite(fileName))
            byte[] buffer = new byte[4096];
            int bytesRead;
                bytesRead = inputStream.Read(buffer, 0, buffer.Length);
                outputStream.Write(buffer, 0, bytesRead);
            } while (bytesRead != 0);
        return true;
        return false;

Main changes are:

  • using a try/catch for the GetResponse() as I was running into an exception when the remote file returned 404
  • returning a boolean

How can I exit from a javascript function?

You should use return as in:

function refreshGrid(entity) {
  var store = window.localStorage;
  var partitionKey;
  if (exit) {

pycharm convert tabs to spaces automatically

ctrl + shift + A => open pop window to select options, select to spaces to convert all tabs as space, or to tab to convert all spaces as tab.

Abort trap 6 error in C

Try this:

void drawInitialNim(int num1, int num2, int num3){
    int board[3][50] = {0}; // This is a local variable. It is not possible to use it after returning from this function. 

    int i, j, k;

    for(i=0; i<num1; i++)
        board[0][i] = 'O';
    for(i=0; i<num2; i++)
        board[1][i] = 'O';
    for(i=0; i<num3; i++)
        board[2][i] = 'O';

    for (j=0; j<3;j++) {
        for (k=0; k<50; k++) {
            if(board[j][k] != 0)
                printf("%c", board[j][k]);

write() versus writelines() and concatenated strings

Actually, I think the problem is that your variable "lines" is bad. You defined lines as a tuple, but I believe that write() requires a string. All you have to change is your commas into pluses (+).

nl = "\n"
lines = line1+nl+line2+nl+line3+nl

should work.

How can I wait In Node.js (JavaScript)? l need to pause for a period of time

Simple and elegant sleep function using modern Javascript

function sleep(millis) {
    return new Promise(resolve => setTimeout(resolve, millis));

No dependencies, no callback hell; that's it :-)

Considering the example given in the question, this is how we would sleep between two console logs:

async function main() {
    await sleep(2000);


The "drawback" is that your main function now has to be async as well. But, considering you are already writing modern Javascript code, you are probably (or at least should be!) using async/await all over your code, so this is really not an issue. All modern browsers today support it.

Giving a little insight into the sleep function for those that are not used to async/await and fat arrow operators, this is the verbose way of writing it:

function sleep(millis) {
    return new Promise(function (resolve, reject) {
        setTimeout(function () { resolve(); }, millis);

Using the fat arrow operator, though, makes it even smaller (and more elegant).

Email validation using jQuery

Look at http: // It is nice jQuery plugin, which allow to build powerfull validation system for forms. There are some usefull samples here. So, email field validation in form will look so:

  rules: {
    field: {
      required: true,
      email: true

See Email method documentation for details and samples.

Save child objects automatically using JPA Hibernate

I believe you need to set the cascade option in your mapping via xml/annotation. Refer to Hibernate reference example here.

In case you are using annotation, you need to do something like this,

@OneToMany(cascade = CascadeType.PERSIST) // Other options are CascadeType.ALL, CascadeType.UPDATE etc..

JPA & Criteria API - Select only specific columns

One of the JPA ways for getting only particular columns is to ask for a Tuple object.

In your case you would need to write something like this:

CriteriaQuery<Tuple> cq = builder.createTupleQuery();
// write the Root, Path elements as usual
Root<EntityClazz> root = cq.from(EntityClazz.class);
cq.multiselect(root.get(EntityClazz_.ID), root.get(EntityClazz_.VERSION));  //using metamodel
List<Tuple> tupleResult = em.createQuery(cq).getResultList();
for (Tuple t : tupleResult) {
    Long id = (Long) t.get(0);
    Long version = (Long) t.get(1);

Another approach is possible if you have a class representing the result, like T in your case. T doesn't need to be an Entity class. If T has a constructor like:

public T(Long id, Long version)

then you can use T directly in your CriteriaQuery constructor:

CriteriaQuery<T> cq = builder.createQuery(T.class);
// write the Root, Path elements as usual
Root<EntityClazz> root = cq.from(EntityClazz.class);
cq.multiselect(root.get(EntityClazz_.ID), root.get(EntityClazz_.VERSION));  //using metamodel
List<T> result = em.createQuery(cq).getResultList();

See this link for further reference.

Could someone explain this for me - for (int i = 0; i < 8; i++)

it's the same as think the next:

"starting with i = 0, while i is less than 8, and adding one to i at the end of the parenthesis, do the instructions between brackets"

It's also the same as:

while( i < 8 )
    // instrucctions like:

the For sentences is a basis of coding, and it's as useful as necessary its understanding.

It's the way to repeat n-times the same instrucction, or browse ( or do something with each element) an array

Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

Action y; //declared inside class


The absolute uri: cannot be resolved in either web.xml or the jar files deployed with this application

I was facing the same issue, to solve it I have added the below entry in pom.xml and performed a maven update.


How to save select query results within temporary table?

You can also do the following:

    Column1 type1,
    Column2 type2,
    Column3 type3




Vim and Ctags tips and tricks

I've been adapting my vim plugins for two years to support big enough c++ project. You can take a look at them.

They use ctags and cscsope.

/usr/bin/codesign failed with exit code 1

Kinda old question, but still happens it seems. Another solution:

Occurred for me after reverting a branch in git. Tried cleaning, cleaning builds, deleting derived and restarting Xcode, but no luck.

Try rebooting the comp.

npm install from Git in a specific version

If you're doing this with more than one module and want to have more control over versions, you should look into having your own private npm registry.

This way you can npm publish your modules to your private npm registry and use package.json entries the same way you would for public modules.

How to sort Counter by value? - python

A rather nice addition to @MartijnPieters answer is to get back a dictionary sorted by occurrence since Collections.most_common only returns a tuple. I often couple this with a json output for handy log files:

from collections import Counter, OrderedDict

x = Counter({'a':5, 'b':3, 'c':7})
y = OrderedDict(x.most_common())

With the output:

OrderedDict([('c', 7), ('a', 5), ('b', 3)])
  "c": 7, 
  "a": 5, 
  "b": 3

Eloquent Collection: Counting and Detect Empty


in this case you want to check two type of count for two cace

case 1:

if result contain only one record other word select single row from database using ->first()

       ...record is exist true...

case 2:

if result contain set of multiple row other word using ->get() or ->all()

  if($result->count()) {
         ...record is exist true...

Typescript interface default values

Default values to an interface are not possible because interfaces only exists at compile time.

Alternative solution:

You could use a factory method for this which returns an object which implements the XI interface.


class AnotherType {}

interface IX {
    a: string,
    b: any,
    c: AnotherType | null

function makeIX (): IX {
    return {
    a: 'abc',
    b: null,
    c: null

const x = makeIX();

x.a = 'xyz';
x.b = 123;
x.c = new AnotherType();

The only thing I changed with regard to your example is made the property c both AnotherType | null. Which will be necessary to not have any compiler errors (This error was also present in your example were you initialized null to property c).

How to write a Unit Test?

Like @CoolBeans mentioned, take a look at jUnit. Here is a short tutorial to get you started as well with jUnit 4.x

Finally, if you really want to learn more about testing and test-driven development (TDD) I recommend you take a look at the following book by Kent Beck: Test-Driven Development By Example.

How Do I Make Glyphicons Bigger? (Change Size?)

I've used bootstrap header classes ("h1", "h2", etc.) for this. This way you get all the style benefits without using the actual tags. Here is an example:

<div class="h3"><span class="glyphicon glyphicon-tags" aria-hidden="true"></span></div>

Java program to find the largest & smallest number in n numbers without using arrays

import java.util.Scanner;

public class LargestSmallestNumbers {

    private static Scanner input;

    public static void main(String[] args) {
       int count,items;
       int newnum =0 ;
       int highest=0;
       int lowest =0;

       input = new Scanner(;
       System.out.println("How many numbers you want to enter?");
       items = input.nextInt();

       System.out.println("Enter "+items+" numbers: ");

       for (count=0; count<items; count++){
           newnum = input.nextInt();               
           if (highest<newnum)

           if (lowest==0)

           else if (newnum<=lowest)

       System.out.println("The highest number is "+highest);
       System.out.println("The lowest number is "+lowest);

How to change the style of a DatePicker in android?

Calendar calendar = Calendar.getInstance();

DatePickerDialog datePickerDialog = new DatePickerDialog(getActivity(),, new DatePickerDialog.OnDateSetListener() {
  public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
    Calendar newDate = Calendar.getInstance();
    newDate.set(year, monthOfYear, dayOfMonth);

    SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd-MM-yyyy");
    String date = simpleDateFormat.format(newDate.getTime());
}, calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));;

And use this style:

<style name="DatePickerDialogTheme" parent="Theme.AppCompat.Light.Dialog">
  <item name="colorAccent">@color/colorPrimary</item>

Bash script to run php script

A previous poster said..

If you have PHP installed as a command line tool… your shebang (#!) line needs to look like this: #!/usr/bin/php

While this could be true… just because you can type in php does NOT necessarily mean that's where php is going to be... /usr/bin/php is A common location… but as with any shebang… it needs to be tailored to YOUR env.

a quick way to find out WHERE YOUR particular executable is located on your $PATH, try.. ?which -a php ENTER, which for me looks like..

php is /usr/local/php5/bin/php
php is /usr/bin/php
php is /usr/local/bin/php
php is /Library/WebServer/CGI-Executables/php

The first one is the default i'd get if I just typed in php at a command prompt… but I can use any of them in a shebang, or directly… You can also combine the executable name with env, as is often seen, but I don't really know much about / trust that. XOXO.

Break a previous commit into multiple commits

git rebase -i will do it.

First, start with a clean working directory: git status should show no pending modifications, deletions, or additions.

Now, you have to decide which commit(s) you want to split.

A) Splitting the most recent commit

To split apart your most recent commit, first:

$ git reset HEAD~

Now commit the pieces individually in the usual way, producing as many commits as you need.

B) Splitting a commit farther back

This requires rebasing, that is, rewriting history. To find the correct commit, you have several choices:

  • If it was three commits back, then

    $ git rebase -i HEAD~3

    where 3 is how many commits back it is.

  • If it was farther back in the tree than you want to count, then

    $ git rebase -i 123abcd~

    where 123abcd is the SHA1 of the commit you want to split up.

  • If you are on a different branch (e.g., a feature branch) that you plan to merge into master:

    $ git rebase -i master

When you get the rebase edit screen, find the commit you want to break apart. At the beginning of that line, replace pick with edit (e for short). Save the buffer and exit. Rebase will now stop just after the commit you want to edit. Then:

$ git reset HEAD~

Commit the pieces individually in the usual way, producing as many commits as you need, then

$ git rebase --continue

When to use a View instead of a Table?

You should design your table WITHOUT considering the views.
Apart from saving joins and conditions, Views do have a performance advantage: SQL Server may calculate and save its execution plan in the view, and therefore make it faster than "on the fly" SQL statements.
View may also ease your work regarding user access at field level.

How is Docker different from a virtual machine?

The docker documentation (and self-explanation) makes a distinction between "virtual machines" vs. "containers". They have the tendency to interpret and use things in a little bit uncommon ways. They can do that because it is up to them, what do they write in their documentation, and because the terminology for virtualization is not yet really exact.

Fact is what the Docker documentation understands on "containers", is paravirtualization (sometimes "OS-Level virtualization") in the reality, contrarily the hardware virtualization, which is docker not.

Docker is a low quality paravirtualisation solution. The container vs. VM distinction is invented by the docker development, to explain the serious disadvantages of their product.

The reason, why it became so popular, is that they "gave the fire to the ordinary people", i.e. it made possible the simple usage of typically server ( = Linux) environments / software products on Win10 workstations. This is also a reason for us to tolerate their little "nuance". But it does not mean that we should also believe it.

The situation is made yet more cloudy by the fact that docker on Windows hosts used an embedded Linux in HyperV, and its containers have run in that. Thus, docker on Windows uses a combined hardware and paravirtualization solution.

In short, Docker containers are low-quality (para)virtual machines with a huge advantage and a lot of disadvantages.

How to load a resource from WEB-INF directory of a web archive

The problem I had accessing the sqlite db file I created in my java (jersey) server had solely to due with path. Some of the docs say the jdbc connect url should look like "jdbc:sqlite://path-to-file/sample.db". I thought the double-slash was part of a htt protocol-style path and would map properly when deployed, but in actuality, it's an absolute or relative path. So, when I placed the file at the root of the WebContent folder (tomcat project), a uri like this worked "jdbc:sqlite:sample.db".

The one thing that was throwing me was that when I was stepping through the debugger, I received a message that said "opening db: ... permission denied". I thought it was a matter of file system permissions or perhaps sql user permissions. After finding out that SQLite doesn't have the concept of roles/permissions like MySQL, etc, I did eventually change the file permissions before I came to what I believe was the correct solution, but I think it was just a bad message (i.e. permission denied, instead of File not found).

Hope this helps someone.

jQuery hasAttr checking to see if there is an attribute on an element

Object.prototype.hasAttr = function(attr) {
    if(this.attr) {
        var _attr = this.attr(attr);
    } else {
        var _attr = this.getAttribute(attr);
    return (typeof _attr !== "undefined" && _attr !== false && _attr !== null);      

I came a crossed this while writing my own function to do the same thing... I though I'd share in case someone else stumbles here. I added null because getAttribute() will return null if the attribute does not exist.

This method will allow you to check jQuery objects and regular javascript objects.

Identifying Exception Type in a handler Catch Block

Alternative Solution

Instead halting a debug session to add some throw-away statements to then recompile and restart, why not just use the debugger to answer that question immediately when a breakpoint is hit?

That can be done by opening up the Immediate Window of the debugger and typing a GetType off of the exception and hitting Enter. The immediate window also allows one to interrogate variables as needed.

See VS Docs: Immediate Window

For example I needed to know what the exception was and just extracted the Name property of GetType as such without having to recompile:

enter image description here

Invalid column name sql error

Change this line:

cmd.CommandText = "INSERT INTO Data (Name,PhoneNo,Address) VALUES (" + txtName.Text + "," + txtPhone.Text + "," + txtAddress.Text + ");";

to this:

cmd.CommandText = "INSERT INTO Data (Name,PhoneNo,Address) VALUES ('" + txtName.Text + "','" + txtPhone.Text + "','" + txtAddress.Text + "');";

Your insert command is expecting text, and you need single quotes (') between the actual value so SQL can understand it as text.

EDIT: For those of you who aren't happy with this answer, I would like to point out that there is an issue with this code in regards to SQL Injection. When I answered this question I only considered the question in point which was the missing single-quote on his code and I pointed out how to fix it. A much better answer has been posted by Adam (and I voted for it), where he explains the issues with injection and shows a way to prevent. Now relax and be happy guys.

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

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

You've got:

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

Which translates into:

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

What you actually want is:

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

Which translates into:

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

Resizing a button

If you want to call a different size for the button inline, you would probably do it like this:

<div class="button" style="width:60px;height:100px;">This is a button</div>

Or, a better way to have different sizes (say there will be 3 standard sizes for the button) would be to have classes just for size.

For example, you would call your button like this:

<div class="button small">This is a button</div>

And in your CSS

.button.small { width: 60px; height: 100px; }

and just create classes for each size you wish to have. That way you still have the perks of using a stylesheet in case say, you want to change the size of all the small buttons at once.

Set auto height and width in CSS/HTML for different screen sizes

This is what do you want? DEMO. Try to shrink the browser's window and you'll see that the elements will be ordered.

What I used? Flexible Box Model or Flexbox.

Just add the follow CSS classes to your container element (in this case div#container):

flex-init-setup and flex-ppal-setup.


  1. flex-init-setup means flexbox init setup; and
  2. flex-ppal-setup means flexbox principal setup

Here are the CSS rules:

 .flex-init-setup {
     display: -webkit-box;
     display: -moz-box;
     display: -webkit-flex;
     display: -ms-flexbox;
     display: flex;
 .flex-ppal-setup {
     -webkit-flex-flow: column wrap;
     -moz-flex-flow: column wrap;
     flex-flow: column wrap;
     -webkit-justify-content: center;
     -moz-justify-content: center;
     justify-content: center;

Be good, Leonardo

How to alert using jQuery

$(".overdue").each( function() {
    alert("Your book is overdue.");

Note that ".addClass()" works because addClass is a function defined on the jQuery object. You can't just plop any old function on the end of a selector and expect it to work.

Also, probably a bad idea to bombard the user with n popups (where n = the number of books overdue).

Perhaps use the size function:

alert( "You have " + $(".overdue").size() + " books overdue." );

Extract specific columns from delimited file using Awk

You can use a for-loop to address a field with $i:

ls -l | awk '{for(i=3 ; i<8 ; i++) {printf("%s\t", $i)} print ""}'

What causes and what are the differences between NoClassDefFoundError and ClassNotFoundException?

A NoClassDefFoundError (NCDFE) happens when your code runs "new Y()" and it can't find the Y class.

It may simply be that Y is missing from your class loader like the other comments suggest, but it could be that the Y class isn't signed or has an invalid signature, or that Y is loaded by a different classloader not visible to your code, or even that Y depends on Z which couldn't be loaded for any of the above reasons.

If this happens, then the JVM will remember the result of loading X (NCDFE) and it will simply throw a new NCDFE every time you ask for Y without telling you why:

class a {
  static class b {}
  public static void main(String args[]) {
    System.out.println("First attempt new b():");
    try {new b(); } catch(Throwable t) {t.printStackTrace();}
    System.out.println("\nSecond attempt new b():");
    try {new b(); } catch(Throwable t) {t.printStackTrace();}

save this as somewhere

The code simply tries to instantiate a new "b" class twice, other than that, it doesn't have any bugs, and it doesn't do anything.

Compile the code with javac, Then run a by invoking java -cp . a -- it should just print out two lines of text, and it should run fine without errors.

Then delete the "a$b.class" file (or fill it with garbage, or copy a.class over it) to simulate the missing or corrupted class. Here's what happens:

First attempt new b():
java.lang.NoClassDefFoundError: a$b
    at a.main(
Caused by: java.lang.ClassNotFoundException: a$b
    at Method)
    at java.lang.ClassLoader.loadClass(
    at sun.misc.Launcher$AppClassLoader.loadClass(
    at java.lang.ClassLoader.loadClass(
    at java.lang.ClassLoader.loadClassInternal(
    ... 1 more

Second attempt new b():
java.lang.NoClassDefFoundError: a$b
    at a.main(

The first invocation results in a ClassNotFoundException (thrown by the class loader when it can't find the class), which must be wrapped in an unchecked NoClassDefFoundError, since the code in question (new b()) should just work.

The second attempt will of course fail too, but as you can see the wrapped exception is no more, because the ClassLoader seems to remember failed class loaders. You see only the NCDFE with absolutely no clue as to what really happened.

So if you ever see a NCDFE with no root cause, you need to see if you can track back to the very first time the class was loaded to find the cause of the error.

sklearn: Found arrays with inconsistent numbers of samples when calling

Some days I faced the same problem. Reason was different sizes arrays.

Getting the difference between two sets

Try this



Removes from this set all of its elements that are contained in the specified collection (optional operation). If the specified collection is also a set, this operation effectively modifies this set so that its value is the asymmetric set difference of the two sets.

onActivityResult is not being called in Fragment

I have a strong suspicion that all of the answers here are nothing more than hacks. I've tried them all and many others, but without any reliable conclusion as there is always some sort of stupid issue. I for one cannot rely on inconsistent results. If you look at the official Android API documentation for Fragments you will see Google clearly states the following:

Call startActivityForResult(Intent, int) from the fragment's containing Activity.

See: Android Fragment API

So, it would seem that the most correct and reliable approach would be to actually call startActivityForResult() from the hosting activity and also handle the resulting onActivityResult() from there.

How to check identical array in most efficient way?

You could compare String representations so:

array1.toString() == array2.toString()
array1.toString() !== array3.toString()

but that would also make

array4 = ['1',2,3,4,5]

equal to array1 if that matters to you

Rendering raw html with reactjs

I used this library called Parser. It worked for what I needed.

import React, { Component } from 'react';    
import Parser from 'html-react-parser';

class MyComponent extends Component {
  render() {

How to Set Focus on Input Field using JQuery

If the input happens to be in a bootstrap modal dialog, the answer is different. Copying from How to Set focus to first text input in a bootstrap modal after shown this is what is required:

$('#myModal').on('', function () {

dyld: Library not loaded: /usr/local/opt/openssl/lib/libssl.1.0.0.dylib

Above solution didn't work for me.

First run brew doctor. if you see something like

Error: unknown or unsupported macOS version: :mountain_lion

then there are some outdated packages which needs to be removed, mine was

It could be python@2, node@6 or some other package.

uninstall those packages brew uninstall [name] then run brew doctor to verify if everything is ok. Then you can reinstall those packages again after brew update && brew upgrade.

Return value in a Bash function

$(...) captures the text sent to stdout by the command contained within. return does not output to stdout. $? contains the result code of the last command.

fun1 (){
  return 34

fun2 (){
  local res=$?
  echo $res

mysql data directory location

If you install MySQL via homebrew on MacOS, you might need to delete your old data directory /usr/local/var/mysql. Otherwise, it will fail during the initialization process with the following error:

==> /usr/local/Cellar/mysql/8.0.16/bin/mysqld --initialize-insecure --user=hohoho --basedir=/usr/local/Cellar/mysql/8.0.16 --datadir=/usr/local/var/mysql --tmpdir=/tmp
2019-07-17T16:30:51.828887Z 0 [System] [MY-013169] [Server] /usr/local/Cellar/mysql/8.0.16/bin/mysqld (mysqld 8.0.16) initializing of server in progress as process 93487
2019-07-17T16:30:51.830375Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.
2019-07-17T16:30:51.830381Z 0 [ERROR] [MY-013236] [Server] Newly created data directory /usr/local/var/mysql/ is unusable. You can safely remove it.
2019-07-17T16:30:51.830410Z 0 [ERROR] [MY-010119] [Server] Aborting
2019-07-17T16:30:51.830540Z 0 [System] [MY-010910] [Server] /usr/local/Cellar/mysql/8.0.16/bin/mysqld: Shutdown complete (mysqld 8.0.16)  Homebrew.

c# dictionary one key many values

Use a dictionary of lists (or another type of collection), for example:

var myDictionary = new Dictionary<string, IList<int>>();

myDictionary["My key"] = new List<int> {1, 2, 3, 4, 5};

python: order a list of numbers without built-in sort, min, max function

Here's a more readable example of an in-place Insertion sort algorithm.

a = [3, 1, 5, 2, 4]

for i in a[1:]:
    j = a.index(i)
    while j > 0 and a[j-1] > a[j]:
        a[j], a[j-1] = a[j-1], a[j]
        j = j - 1

Convert an ArrayList to an object array

You can use this code

ArrayList<TypeA> a = new ArrayList<TypeA>();
Object[] o = a.toArray();

Then if you want that to get that object back into TypeA just check it with instanceOf method.

What's the difference between a single precision and double precision floating point operation?

As to the question "Can the ps3 and xbxo 360 pull off double precision floating point operations or only single precision and in generel use is the double precision capabilities made use of (if they exist?)."

I believe that both platforms are incapable of double floating point. The original Cell processor only had 32 bit floats, same with the ATI hardware which the XBox 360 is based on (R600). The Cell got double floating point support later on, but I'm pretty sure the PS3 doesn't use that chippery.

Content type 'application/x-www-form-urlencoded;charset=UTF-8' not supported for @RequestBody MultiValueMap

You can try to turn support on in spring's converter

public class WebConfig implements WebMvcConfigurer {

    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        // add converter suport Content-Type: 'application/x-www-form-urlencoded'
                .ifPresent(converter -> converter.addSupportedMediaTypes(MediaType.APPLICATION_FORM_URLENCODED_VALUE));


string sanitizer for filename

Making a small adjustment to Tor Valamo's solution to fix the problem noticed by Dominic Rodger, you could use:

// Remove anything which isn't a word, whitespace, number
// or any of the following caracters -_~,;[]().
// If you don't need to handle multi-byte characters
// you can use preg_replace rather than mb_ereg_replace
// Thanks @Lukasz Rysiak!
$file = mb_ereg_replace("([^\w\s\d\-_~,;\[\]\(\).])", '', $file);
// Remove any runs of periods (thanks falstro!)
$file = mb_ereg_replace("([\.]{2,})", '', $file);

How to unescape HTML character entities in Java?

I have used the Apache Commons StringEscapeUtils.unescapeHtml4() for this:

Unescapes a string containing entity escapes to a string containing the actual Unicode characters corresponding to the escapes. Supports HTML 4.0 entities.

ETag vs Header Expires

One additional thing I would like to mention that some of the answers may have missed is the downside to having both ETags and Expires/Cache-control in your headers.

Depending on your needs it may just add extra bytes in your headers which may increase packets which means more TCP overhead. Again, you should see if the overhead of having both things in your headers is necessary or will it just add extra weight in your requests which reduces performance.

You can read more about it on this excellent blog post by Kyle Simpson:

Get Excel sheet name and use as variable in macro

in a Visual Basic Macro you would use

pName = ActiveWorkbook.Path      ' the path of the currently active file
wbName = ActiveWorkbook.Name     ' the file name of the currently active file
shtName = ActiveSheet.Name       ' the name of the currently selected worksheet

The first sheet in a workbook can be referenced by


so after deleting the [Report] tab you would use

shtName = ActiveWorkbook.Worksheets(1).Name

to "work on that sheet later on" you can create a range object like

Dim MySheet as Range
MySheet = ActiveWorkbook.Worksheets(shtName).[A1]

and continue working on MySheet(rowNum, colNum) etc. ...

shortcut creation of a range object without defining shtName:

Dim MySheet as Range
MySheet = ActiveWorkbook.Worksheets(1).[A1]

Embed HTML5 YouTube video without iframe?

Yes, but it depends on what you mean by 'embed'; as far as I can tell after reading through the docs, it seems like you have a couple of options if you want to get around using the iframe API. You can use the javascript and flash API's ( to embed a player, but that involves creating Flash objects in your code (something I personally avoid, but not necessarily something that you have to). Below are some helpful sections from the dev docs for the Youtube API.

If you really want to get around all these methods and include video without any sort of iframe, then your best bet might be creating an HTML5 video player/app that can connect to the Youtube Data API ( I'm not sure what the extent of your needs are, but this would be the way to go if you really want to get around using any iframes or flash objects.

Hope this helps!



IFrame embeds using the IFrame Player API

Follow the IFrame Player API instructions to insert a video player in your web page or application after the Player API's JavaScript code has loaded. The second parameter in the constructor for the video player is an object that specifies player options. Within that object, the playerVars property identifies player parameters.

The HTML and JavaScript code below shows a simple example that inserts a YouTube player into the page element that has an id value of ytplayer. The onYouTubePlayerAPIReady() function specified here is called automatically when the IFrame Player API code has loaded. This code does not define any player parameters and also does not define other event handlers.


IFrame embeds using tags

Define an tag in your application in which the src URL specifies the content that the player will load as well as any other player parameters you want to set. The tag's height and width parameters specify the dimensions of the player.

If you are creating the element yourself (rather than using the IFrame Player API to create it), you can append player parameters directly to the end of the URL. The URL has the following format:


AS3 object embeds

Object embeds use an tag to specify the player's dimensions and parameters. The sample code below demonstrates how to use an object embed to load an AS3 player that automatically plays the same video as the previous two examples.

Compare data of two Excel Columns A & B, and show data of Column A that do not exist in B

Put this in C2 and copy down

=IF(ISNA(VLOOKUP(A2,$B$2:$B$65535,1,FALSE)),"not in B","")

Then if the value in A isn't in B the cell in column C will say "not in B".

What encoding/code page is cmd.exe using?

Command CHCP shows the current codepage. It has three digits: 8xx and is different from Windows 12xx. So typing a English-only text you wouldn't see any difference, but an extended codepage (like Cyrillic) will be printed wrongly.

HTML5 Local storage vs. Session storage

sessionStorage is the same as localStorage, except that it stores the data for only one session, and it will be removed when the user closes the browser window that created it.

How to copy and edit files in Android shell?

To copy dirs, it seems you can use adb pull <remote> <local> if you want to copy file/dir from device, and adb push <local> <remote> to copy file/dir to device. Alternatively, just to copy a file, you can use a simple trick: cat source_file > dest_file. Note that this does not work for user-inaccessible paths.

To edit files, I have not found a simple solution, just some possible workarounds. Try this, it seems you can (after the setup) use it to edit files like busybox vi <filename>. Nano seems to be possible to use too.

How to pass password to scp?

Nobody mentioned it, but Putty scp (pscp) has a -pw option for password.

Documentation can be found here:

What's the fastest way to do a bulk insert into Postgres?

PostgreSQL has a guide on how to best populate a database initially, and they suggest using the COPY command for bulk loading rows. The guide has some other good tips on how to speed up the process, like removing indexes and foreign keys before loading the data (and adding them back afterwards).

How to import Swagger APIs into Postman?

  • Click on the orange button ("choose files")
  • Browse to the Swagger doc (swagger.yaml)
  • After selecting the file, a new collection gets created in POSTMAN. It will contain folders based on your endpoints.

You can also get some sample swagger files online to verify this(if you have errors in your swagger doc).

C# - Fill a combo box with a DataTable

This line

mnuActionLanguage.ComboBox.DisplayMember = "Lang.Language";

is wrong. Change it to

mnuActionLanguage.ComboBox.DisplayMember = "Language";

and it will work (even without DataBind()).

Determine Whether Integer Is Between Two Other Integers?

if number >= 10000 and number <= 30000:
    print ("you have to pay 5% taxes")

How do I get extra data from intent on Android?

We can do it by simple means:

In FirstActivity:

Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
intent.putExtra("uid", uid.toString());
intent.putExtra("pwd", pwd.toString());

In SecondActivity:

    try {
        Intent intent = getIntent();

        String uid = intent.getStringExtra("uid");
        String pwd = intent.getStringExtra("pwd");

    } catch (Exception e) {
        Log.e("getStringExtra_EX", e + "");

How do I obtain crash-data from my Android application?

I'm one of the founders of Bugsnag which we designed for exactly this purpose. Bugsnag automatically captures unhandled exceptions in Android apps and sends them to our dashboard, where you can prioritize fixes and dive into diagnostic information.

Here are some important things to consider when selecting or building a crash reporting system, along with some code snippets:

  • Detects unhandled exceptions automatically (example code)
  • Collects diagnostic data such as memory usage, device info, etc (example code)
  • Effectively groups crashes together by root cause
  • Allows you to track actions the user took before each crash to help reproduce (example code)

If you want to see some best practices around crash handling/reporting on Android you can check out the full source code for Bugsnag's crash reporting library which is fully open source, feel free to tear this apart and use it in your own applications!

Adding a regression line on a ggplot

The simple solution using geom_abline:

geom_abline(slope = coef(data.lm)[[2]], intercept = coef(data.lm)[[1]])

Where data.lm is an lm object, and coef(data.lm) looks something like this:

> coef(data.lm)
(Intercept)    DepDelay 
  -2.006045    1.025109 

The numeric indexing assumes that (Intercept) is listed first, which is the case if the model includes an intercept. If you have some other linear model object, just plug in the slope and intercept values similarly.

Importing JSON into an Eclipse project

The link of accepted answer is old and can cause warnings with generics use,

You should download latest jar from JSON-java github site

Add jar to Java build Path

In existing project in Order and Export tab move the new jar, as json-20180813.jar, as the first (or above other dependencies with JSONObject)

How do I base64 encode a string efficiently using Excel VBA?

As Mark C points out, you can use the MSXML Base64 encoding functionality as described here.

I prefer late binding because it's easier to deploy, so here's the same function that will work without any VBA references:

Function EncodeBase64(text As String) As String
  Dim arrData() As Byte
  arrData = StrConv(text, vbFromUnicode)

  Dim objXML As Variant
  Dim objNode As Variant

  Set objXML = CreateObject("MSXML2.DOMDocument")
  Set objNode = objXML.createElement("b64")

  objNode.dataType = "bin.base64"
  objNode.nodeTypedValue = arrData
  EncodeBase64 = objNode.text

  Set objNode = Nothing
  Set objXML = Nothing
End Function

Getting a link to go to a specific section on another page

To link from a page to another section just use

<a href="index.php#firstdiv">my first div</a>

How to use HTTP GET in PowerShell?

Downloading Wget is not necessary; the .NET Framework has web client classes built in.

$wc = New-Object system.Net.WebClient;
$sms = Read-Host "Enter SMS text";
$sms = [System.Web.HttpUtility]::UrlEncode($sms);
$smsResult = $wc.downloadString("http://smsserver/SNSManager/msgSend.jsp?uid&to=smartsms:*+001XXXXXX&msg=$sms&encoding=windows-1255")

How do I convert two lists into a dictionary?

you can use this below code:

dict(zip(['name', 'age', 'food'], ['Monty', 42, 'spam']))

But make sure that length of the lists will be same.if length is not same.then zip function turncate the longer one.

is there something like isset of php in javascript/jQuery?

Here :)

function isSet(iVal){
 return (iVal!=="" && iVal!=null && iVal!==undefined && typeof(iVal) != "undefined") ? 1 : 0;
} // Returns 1 if set, 0 false

How to change default timezone for Active Record in Rails?

If you want to set the timezone to UTC globally, you can do the following in Rails 4:

# Inside config/application.rb
config.time_zone = "UTC"
config.active_record.default_timezone = :utc

Be sure to restart your application or you won't see the changes.

Node.js: Gzip compression?

There are multiple Gzip middlewares for Express, KOA and others. For example:

However, Node is awfully bad at doing CPU intensive tasks like gzipping, SSL termination, etc. Instead, use a ‘real’ middleware services like nginx or HAproxy, see bullet 3 here:

How to add element in Python to the end of list using list.insert?

You'll have to pass the new ordinal position to insert using len in this case:

In [62]:

[1, 2, 3, 4, 5]

Xcode swift am/pm time to 24 hour format

let calendar = Calendar.current
let hours    = calendar.component(.hour, from: Date())
let minutes  = calendar.component(.minute, from: Date())
let seconds  = calendar.component(.second, from: Date())

PHP is not recognized as an internal or external command in command prompt

You need to Go to My Computer->properties -> Advanced system setting

Now click on Environment Variables..

enter image description here

Add ;C:\xampp\php in path variable value

enter image description here

Now restart command prompt DONE!

Note: Make sure you run CMD via run as administrator

Is there a PowerShell "string does not contain" cmdlet or syntax?

To exclude the lines that contain any of the strings in $arrayOfStringsNotInterestedIn, you should use:

(Get-Content $FileName) -notmatch [String]::Join('|',$arrayofStringsNotInterestedIn)

The code proposed by Chris only works if $arrayofStringsNotInterestedIn contains the full lines you want to exclude.

Change the mouse cursor on mouse over to anchor-like style

You actually don't need jQuery, just CSS. For example, here's some HTML:

<div class="special"></div>

And here's the CSS:

    cursor: pointer;

Simple way to sort strings in the (case sensitive) alphabetical order

I recently answered a similar question here. Applying the same approach to your problem would yield following solution:

  p2Ord(stringOrd, stringOrd).comap(new F<String, P2<String, String>>() {
    public P2<String, String> f(String s) {
      return p(s.toLowerCase(), s);

Regular Expression with wildcards to match any character

Without knowing the exact regex implementation you're making use of, I can only give general advice. (The syntax I will be perl as that's what I know, some languages will require tweaking)

Looking at ABC: (z) jan 02 1999 \n

  • The first thing to match is ABC: So using our regex is /ABC:/

  • You say ABC is always at the start of the string so /^ABC/ will ensure that ABC is at the start of the string.

  • You can match spaces with the \s (note the case) directive. With all directives you can match one or more with + (or 0 or more with *)

  • You need to escape the usage of ( and ) as it's a reserved character. so \(\)

  • You can match any non space or newline character with .

  • You can match anything at all with .* but you need to be careful you're not too greedy and capture everything.

So in order to capture what you've asked. I would use /^ABC:\s*\(.+?\)\s*(.+)$/

Which I read as:

Begins with ABC:

May have some spaces

has (

has some characters

has )

may have some spaces

then capture everything until the end of the line (which is $).

I highly recommend keeping a copy of the following laying about

Showing Difference between two datetime values in hours

Is there a reason you're using Nullable?

If you want to use Nullable then you can write variable.Value.TotalHours.

Or you can just write: (datevalue1 - datevalue2).TotalHours.

Return True, False and None in Python

It's impossible to say without seeing your actual code. Likely the reason is a code path through your function that doesn't execute a return statement. When the code goes down that path, the function ends with no value returned, and so returns None.

Updated: It sounds like your code looks like this:

def b(self, p, data): 
    current = p 
    if == data: 
        return True 
    elif == 1:
        return False 
        self.b(, data)

That else clause is your None path. You need to return the value that the recursive call returns:

        return self.b(, data)

BTW: using recursion for iterative programs like this is not a good idea in Python. Use iteration instead. Also, you have no clear termination condition.

How to check if cursor exists (open status)

I rarely employ cursors, but I just discovered one other item that can bite you here, the scope of the cursor name.

If the database CURSOR_DEFAULT is global, you will get the "cursor already exists" error if you declare a cursor in a stored procedure with a particular name (eg "cur"), and while that cursor is open you call another stored procedure which declares and opens a cursor with the same name (eg "cur"). The error will occur in the nested stored procedure when it attempts to open "cur".

Run this bit of sql to see your CURSOR_DEFAULT:

select is_local_cursor_default from sys.databases where name = '[your database name]'

If this value is "0" then how you name your nested cursor matters!

How do I check the operating system in Python?

You can get a pretty coarse idea of the OS you're using by checking sys.platform.

Once you have that information you can use it to determine if calling something like os.uname() is appropriate to gather more specific information. You could also use something like Python System Information on unix-like OSes, or pywin32 for Windows.

There's also psutil if you want to do more in-depth inspection without wanting to care about the OS.

Date Conversion from String to sql Date in Java giving different output?

While using the date formats, you may want to keep in mind to always use MM for months and mm for minutes. That should resolve your problem.

Replacing few values in a pandas dataframe column with another value

Created the Data frame:

import pandas as pd

Now use DataFrame.replace() function:


finding multiples of a number in Python

For the first ten multiples of 5, say

>>> [5*n for n in range(1,10+1)]
[5, 10, 15, 20, 25, 30, 35, 40, 45, 50]

How to connect to mysql with laravel?

In Laravel 5, there is a .env file,

It looks like





Edit that .env There is .env.sample is there , try to create from that if no such .env file found.

Why do access tokens expire?

It is essentially a security measure. If your app is compromised, the attacker will only have access to the short-lived access token and no way to generate a new one.

Refresh tokens also expire but they are supposed to live much longer than the access token.

How to adjust an UIButton's imageSize?

If your image is too large (and you can't/don't want to just made the image smaller), a combination of the first two answers works great.

addButton.imageView?.contentMode = .scaleAspectFit
addButton.imageEdgeInsets = UIEdgeInsetsMake(15.0, 15.0, 15.0, 5.0)

Unless you get the image insets just right, the image will be skewed without changing the contentMode.

git clone error: RPC failed; curl 56 OpenSSL SSL_read: SSL_ERROR_SYSCALL, errno 10054

This happens when you push first time without net connection or poor net connection.But when you try again using good connection 2,3 times problem will be solved.

Bulk insert with SQLAlchemy ORM

The sqlalchemy docs have a writeup on the performance of various techniques that can be used for bulk inserts:

ORMs are basically not intended for high-performance bulk inserts - this is the whole reason SQLAlchemy offers the Core in addition to the ORM as a first-class component.

For the use case of fast bulk inserts, the SQL generation and execution system that the ORM builds on top of is part of the Core. Using this system directly, we can produce an INSERT that is competitive with using the raw database API directly.

Alternatively, the SQLAlchemy ORM offers the Bulk Operations suite of methods, which provide hooks into subsections of the unit of work process in order to emit Core-level INSERT and UPDATE constructs with a small degree of ORM-based automation.

The example below illustrates time-based tests for several different methods of inserting rows, going from the most automated to the least. With cPython 2.7, runtimes observed:

classics-MacBook-Pro:sqlalchemy classic$ python
SQLAlchemy ORM: Total time for 100000 records 12.0471920967 secs
SQLAlchemy ORM pk given: Total time for 100000 records 7.06283402443 secs
SQLAlchemy ORM bulk_save_objects(): Total time for 100000 records 0.856323003769 secs
SQLAlchemy Core: Total time for 100000 records 0.485800027847 secs
sqlite3: Total time for 100000 records 0.487842082977 sec


import time
import sqlite3

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String,  create_engine
from sqlalchemy.orm import scoped_session, sessionmaker

Base = declarative_base()
DBSession = scoped_session(sessionmaker())
engine = None

class Customer(Base):
    __tablename__ = "customer"
    id = Column(Integer, primary_key=True)
    name = Column(String(255))

def init_sqlalchemy(dbname='sqlite:///sqlalchemy.db'):
    global engine
    engine = create_engine(dbname, echo=False)
    DBSession.configure(bind=engine, autoflush=False, expire_on_commit=False)

def test_sqlalchemy_orm(n=100000):
    t0 = time.time()
    for i in xrange(n):
        customer = Customer() = 'NAME ' + str(i)
        if i % 1000 == 0:
        "SQLAlchemy ORM: Total time for " + str(n) +
        " records " + str(time.time() - t0) + " secs")

def test_sqlalchemy_orm_pk_given(n=100000):
    t0 = time.time()
    for i in xrange(n):
        customer = Customer(id=i+1, name="NAME " + str(i))
        if i % 1000 == 0:
        "SQLAlchemy ORM pk given: Total time for " + str(n) +
        " records " + str(time.time() - t0) + " secs")

def test_sqlalchemy_orm_bulk_insert(n=100000):
    t0 = time.time()
    n1 = n
    while n1 > 0:
        n1 = n1 - 10000
                dict(name="NAME " + str(i))
                for i in xrange(min(10000, n1))
        "SQLAlchemy ORM bulk_save_objects(): Total time for " + str(n) +
        " records " + str(time.time() - t0) + " secs")

def test_sqlalchemy_core(n=100000):
    t0 = time.time()
        [{"name": 'NAME ' + str(i)} for i in xrange(n)]
        "SQLAlchemy Core: Total time for " + str(n) +
        " records " + str(time.time() - t0) + " secs")

def init_sqlite3(dbname):
    conn = sqlite3.connect(dbname)
    c = conn.cursor()
    c.execute("DROP TABLE IF EXISTS customer")
        "CREATE TABLE customer (id INTEGER NOT NULL, "
        "name VARCHAR(255), PRIMARY KEY(id))")
    return conn

def test_sqlite3(n=100000, dbname='sqlite3.db'):
    conn = init_sqlite3(dbname)
    c = conn.cursor()
    t0 = time.time()
    for i in xrange(n):
        row = ('NAME ' + str(i),)
        c.execute("INSERT INTO customer (name) VALUES (?)", row)
        "sqlite3: Total time for " + str(n) +
        " records " + str(time.time() - t0) + " sec")

if __name__ == '__main__':

LaTeX: Prevent line break in a span of text

\mbox is the simplest answer. Regarding the update:

TeX prefers overlong lines to adding too much space between words on a line; I think the idea is that you will notice the lines that extend into the margin (and the black boxes it inserts after such lines), and will have a chance to revise the contents, whereas if there was too much space, you might not notice it.

Use \sloppy or \begin{sloppypar}...\end{sloppypar} to adjust this behavior, at least a little. Another possibility is \raggedright (or \begin{raggedright}...\end{raggedright}).

Eclipse keyboard shortcut to indent source code to the left?

On Mac (on french keyboard its) cmd + shift + F

Build an iOS app without owning a mac?

Also if you want to save some money you don't must buy a Mac. There is other ways how to do it:

1.) You can use practically any OS to run latest MacOS in virtual machine (look at YouTube). I am using this method really long time without any problems on windows with VMWare.

2.) Hackintosh. Install MacOS to your PC. You must have compatible components, but if you have, this is the best way, because you eliminate the lags in VM... I am using this in this time. Perfect. On my laptop, but please don't tell this to Apple, because practically this is illegal

3.) If you are making simple apps with minimum UI, you can use Theos. Also with Theos you can create cydia tweaks. Only one problem: codesign. If you want to publish app on App Store you still must have MacOS, but if you want to make app in home you can use CydiaImpactor to sign the apps with Apple ID.

I used all of this ways and all is working. By my VM is best solution if you don't want to spend lot of time by installing Hackintosh.

Android - Handle "Enter" in an EditText

First, you have to set EditText listen to key press

protected void onCreate(Bundle savedInstanceState) {

    // Set the EditText listens to key press
    EditText edittextproductnumber = (EditText) findViewById(;


Second, define the event upon the key press, for example, event to set TextView's text:

public boolean onKey(View v, int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub

 // Listen to "Enter" key press
 if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER))
     TextView textviewmessage = (TextView) findViewById(;
     textviewmessage.setText("You hit 'Enter' key");
     return true;

return false;   


And finally, do not forget to import EditText,TextView,OnKeyListener,KeyEvent at top:

import android.view.KeyEvent;
import android.view.View.OnKeyListener;
import android.widget.EditText;
import android.widget.TextView;

How to encrypt String in Java

How about this:

private static byte[] xor(final byte[] input, final byte[] secret) {
    final byte[] output = new byte[input.length];
    if (secret.length == 0) {
        throw new IllegalArgumentException("empty security key");
    int spos = 0;
    for (int pos = 0; pos < input.length; ++pos) {
        output[pos] = (byte) (input[pos] ^ secret[spos]);
        if (spos >= secret.length) {
            spos = 0;
    return output;

Works fine for me and is rather compact.

error: expected unqualified-id before ‘.’ token //(struct)

You are trying to access the struct statically with a . instead of ::, nor are its members static. Either instantiate ReducedForm:

ReducedForm rf;
rf.iSimplifiedNumerator = 5;

or change the members to static like this:

struct ReducedForm
    static int iSimplifiedNumerator;
    static int iSimplifiedDenominator;

In the latter case, you must access the members with :: instead of . I highly doubt however that the latter is what you are going for ;)

Reporting (free || open source) Alternatives to Crystal Reports in Winforms

MS' free SQL Server 2008 Express (with Advanced Services) looks to include reporting services.

Here how reporting features differ from the full version:

EDIT: I don't know if this works in winforms but it still looks useful.

How do I fix "for loop initial declaration used outside C99 mode" GCC error?

There is a compiler switch which enables C99 mode, which amongst other things allows declaration of a variable inside the for loop. To turn it on use the compiler switch -std=c99

Or as @OysterD says, declare the variable outside the loop.

Why does overflow:hidden not work in a <td>?

I'm not familiar with the specific issue, but you could stick a div, etc inside the td and set overflow on that.

How to print formatted BigDecimal values?

BigDecimal(19.0001).setScale(2, BigDecimal.RoundingMode.DOWN)

How to split and modify a string in NodeJS?

Use split and map function:

var str = "123, 124, 234,252";
var arr = str.split(",");
arr = (val) { return +val + 1; });

Notice +val - string is casted to a number.

Or shorter:

var str = "123, 124, 234,252";
var arr = str.split(",").map(function (val) { return +val + 1; });

edit 2015.07.29

Today I'd advise against using + operator to cast variable to a number. Instead I'd go with a more explicit but also more readable Number call:

var str = "123, 124, 234,252";_x000D_
var arr = str.split(",").map(function (val) {_x000D_
  return Number(val) + 1;_x000D_

edit 2017.03.09

ECMAScript 2015 introduced arrow function so it could be used instead to make the code more concise:

var str = "123, 124, 234,252";_x000D_
var arr = str.split(",").map(val => Number(val) + 1);_x000D_

jQuery posting JSON

In case you are sending this post request to a cross domain, you should check out this link.

Your server is not accepting the cross site post request. So the server configuration needs to be changed to allow cross site requests.

Elasticsearch: Failed to connect to localhost port 9200 - Connection refused

In this case, first of all you need to check the java version using below command:

java -version

after running this command you get something like this:

java version "1.7.0_51" OpenJDK Runtime Environment (rhel- u51-b31) OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode)

then use this command:

update-alternatives --config java

and select the below version

*+ 1 /usr/lib/jvm/java-1.7.0-openjdk- 2 /usr/java/jdk1.8.0_73/jre/bin/java

Enter to keep the current selection[+], or type selection number: 2

curl -XGET

How do I check if a C++ string is an int?

Use the all-powerful C stdio/string functions:

int dummy_int;
int scan_value = std::sscanf( some_string.c_str(), "%d", &dummy_int);

if (scan_value == 0)
    // does not start with integer
    // starts with integer

msvcr110.dll is missing from computer error while installing PHP

I am on a 64 bit system, and I only got this to work after installing both the 32 and 64 bit versions of the redistributable. I did not try the 64 bit version by itself due to the other posters' warnings about using the 32 bit version (and am too lazy to uninstall the 32 bit version now that I have it working), so I don't know if the 32 bit version is needed or not in cases like mine.

Take n rows from a spark dataframe and pass to toPandas()

Try it:

def showDf(df, count=None, percent=None, maxColumns=0):
    if (df == None): return
    import pandas
    from IPython.display import display
    pandas.set_option('display.encoding', 'UTF-8')
    # Pandas dataframe
    dfp = None
    # maxColumns param
    if (maxColumns >= 0):
        if (maxColumns == 0): maxColumns = len(df.columns)
        pandas.set_option('display.max_columns', maxColumns)
    # count param
    if (count == None and percent == None): count = 10 # Default count
    if (count != None):
        count = int(count)
        if (count == 0): count = df.count()
        pandas.set_option('display.max_rows', count)
        dfp = pandas.DataFrame(df.head(count), columns=df.columns)
    # percent param
    elif (percent != None):
        percent = float(percent)
        if (percent >=0.0 and percent <= 1.0):
            import datetime
            now =
            seed = long(now.strftime("%H%M%S"))
            dfs = df.sample(False, percent, seed)
            count = df.count()
            pandas.set_option('display.max_rows', count)
            dfp = dfs.toPandas()    

Examples of usages are:

# Shows the ten first rows of the Spark dataframe
showDf(df, 10)
showDf(df, count=10)

# Shows a random sample which represents 15% of the Spark dataframe
showDf(df, percent=0.15) 

jQuery rotate/transform

Why not just use, toggleClass on click?




button.up {
    -webkit-transform: rotate(180deg);
       -moz-transform: rotate(180deg);
        -ms-transform: rotate(180deg);
         -o-transform: rotate(180deg);
            transform: rotate(180deg);
               /* IE6–IE9 */
               filter: progid:DXImageTransform.Microsoft.Matrix(M11=0.9914448613738104, M12=-0.13052619222005157,M21=0.13052619222005157, M22=0.9914448613738104, sizingMethod='auto expand');
                 zoom: 1;

you can also add this to the css:

        -webkit-transition: all 500ms ease-in-out;
        -moz-transition: all 500ms ease-in-out;
        -o-transition: all 500ms ease-in-out;
        -ms-transition: all 500ms ease-in-out;

which will add the animation.


to answer your original question:

you said that it rotates but never stops. When using set timeout you need to make sure you have a condition that will not call settimeout or else it will run forever. So for your code:

<script type="text/javascript">
    $(function() {
     var $elie = $("#bkgimg");
     function rotate(degree) {

      // For webkit browsers: e.g. Chrome
    $elie.css({ WebkitTransform: 'rotate(' + degree + 'deg)'});
      // For Mozilla browser: e.g. Firefox
    $elie.css({ '-moz-transform': 'rotate(' + degree + 'deg)'});

    /* add a condition here for the extremity */ 
    if(degree < 180){
      // Animate rotation with a recursive call
      setTimeout(function() { rotate(++degree); },65);

How to lookup JNDI resources on WebLogic?

I just had to update legacy Weblogic 8 app to use a data-source instead of hard-coded JDBC string. Datasource JNDI name on the configuration tab in the Weblogic admin showed: "weblogic.jdbc.ESdatasource", below are two ways that worked:

      Context ctx = new InitialContext();
      DataSource dataSource;

      try {
        dataSource = (DataSource) ctx.lookup("weblogic.jdbc.ESdatasource");
        response.getWriter().println("A " +dataSource);
      }catch(Exception e) {
        response.getWriter().println("A " + e.getMessage() + e.getCause());


      try {
        dataSource = (DataSource) ctx.lookup("weblogic/jdbc/ESdatasource");
        response.getWriter().println("F "+dataSource);
      }catch(Exception e) {
        response.getWriter().println("F " + e.getMessage() + e.getCause());

      //use your datasource
      conn = datasource.getConnection();

That's all folks. No passwords and initial context factory needed from the inside of Weblogic app.

How to align texts inside of an input?

Without CSS: Use the STYLE property of text input

STYLE="text-align: right;"

Getting RSA private key from PEM BASE64 Encoded private key file

As others have responded, the key you are trying to parse doesn't have the proper PKCS#8 headers which Oracle's PKCS8EncodedKeySpec needs to understand it. If you don't want to convert the key using openssl pkcs8 or parse it using JDK internal APIs you can prepend the PKCS#8 header like this:

static final Base64.Decoder DECODER = Base64.getMimeDecoder();

private static byte[] buildPKCS8Key(File privateKey) throws IOException {
  final String s = new String(Files.readAllBytes(privateKey.toPath()));
  if (s.contains("--BEGIN PRIVATE KEY--")) {
    return DECODER.decode(s.replaceAll("-----\\w+ PRIVATE KEY-----", ""));
  if (!s.contains("--BEGIN RSA PRIVATE KEY--")) {
    throw new RuntimeException("Invalid cert format: "+ s);

  final byte[] innerKey = DECODER.decode(s.replaceAll("-----\\w+ RSA PRIVATE KEY-----", ""));
  final byte[] result = new byte[innerKey.length + 26];
  System.arraycopy(DECODER.decode("MIIEvAIBADANBgkqhkiG9w0BAQEFAASCBKY="), 0, result, 0, 26);
  System.arraycopy(BigInteger.valueOf(result.length - 4).toByteArray(), 0, result, 2, 2);
  System.arraycopy(BigInteger.valueOf(innerKey.length).toByteArray(), 0, result, 24, 2);
  System.arraycopy(innerKey, 0, result, 26, innerKey.length);
  return result;

Once that method is in place you can feed it's output to the PKCS8EncodedKeySpec constructor like this: new PKCS8EncodedKeySpec(buildPKCS8Key(privateKey));