Programs & Examples On #Mouseleave

For issues relating to setting up, subscribing to, or handling mouseleave events.

How to use mouseover and mouseout in Angular 6

CSS solution works without a glitch!

.col-info:hover>.popoverIcon {
    visibility: visible;

.popoverIcon {
  visibility: hidden;
<div *ngFor="let i of [1,2,3,4]">

  <div class="col-info">
    <span class=" popoverIcon ">Show {{i}}</span>


Unable to preventDefault inside passive event listener

In plain JS add { passive: false } as third argument

document.addEventListener('wheel', function(e) {
}, { passive: false });

How do you Hover in ReactJS? - onMouseLeave not registered during fast hover over

Use Radium!

The following is an example from their website:

var Radium = require('radium');_x000D_
var React = require('react');_x000D_
var color = require('color');_x000D_
class Button extends React.Component {_x000D_
  static propTypes = {_x000D_
    kind: React.PropTypes.oneOf(['primary', 'warning']).isRequired_x000D_
  render() {_x000D_
    // Radium extends the style attribute to accept an array. It will merge_x000D_
    // the styles in order. We use this feature here to apply the primary_x000D_
    // or warning styles depending on the value of the `kind` prop. Since its_x000D_
    // all just JavaScript, you can use whatever logic you want to decide which_x000D_
    // styles are applied (props, state, context, etc)._x000D_
    return (_x000D_
// You can create your style objects dynamically or share them for_x000D_
// every instance of the component._x000D_
var styles = {_x000D_
  base: {_x000D_
    color: '#fff',_x000D_
    // Adding interactive state couldn't be easier! Add a special key to your_x000D_
    // style object (:hover, :focus, :active, or @media) with the additional rules._x000D_
    ':hover': {_x000D_
      background: color('#0074d9').lighten(0.2).hexString()_x000D_
  primary: {_x000D_
    background: '#0074D9'_x000D_
  warning: {_x000D_
    background: '#FF4136'_x000D_

Inline CSS styles in React: how to implement a:hover?

With a using of the hooks:

const useFade = () => {
  const [ fade, setFade ] = useState(false);

  const onMouseEnter = () => {

  const onMouseLeave = () => {

  const fadeStyle = !fade ? {
    opacity: 1, transition: 'all .2s ease-in-out',
  } : {
    opacity: .5, transition: 'all .2s ease-in-out',

  return { fadeStyle, onMouseEnter, onMouseLeave };

const ListItem = ({ style }) => {
  const { fadeStyle, ...fadeProps } = useFade();

  return (

ng-mouseover and leave to toggle item using mouse in angularjs

Here is example with only CSS for that. In example I'm using SASS and SLIM.


  span joined
  span leave


  @each $vendor in ('-webkit-', '')
    #{$vendor}transition-property: $property
    #{$vendor}transition-duration: .3s
    #{$vendor}transition-timing-function: ease-in

  +animate(opacity, max-height, visibility)
  max-height: 150px
  opacity: 1
  visibility: visible

  +animate(opacity, max-height, visibility)
  max-height: 0
  opacity: 0
  visibility: hidden

  @each $vendor in ('-webkit-', '-ms-', '')
    #{$vendor}transform: $var

  border: 1px solid blue

    position: relative

      position: absolute
      left: 50%

        border-color: blue

angularjs ng-style: background-image isn't working

Correct syntax for background-image is:

background-image: url("path_to_image");

Correct syntax for ng-style is:


How can I keep Bootstrap popovers alive while being hovered?

Vikas answer works perfectly for me, here I also add support for the delay (show / hide).

var popover = $('#example');
var options = {
    animation : true,
    html: true,
    trigger: 'manual',
    placement: 'right',
    delay: {show: 500, hide: 100}
    .on("mouseenter", function () {

        var t = this;
        var popover = $(this);    
        setTimeout(function () {

            if (":hover")) {

                popover.siblings(".popover").on("mouseleave", function () {
    .on("mouseleave", function () {
        var t = this;
        var popover = $(this);

        setTimeout(function () {
            if (popover.siblings(".popover").length && !popover.siblings(".popover").is(":hover")) {
        }, options.delay.hide);

Also please pay attention I changed:

if (!$(".popover:hover").length) {


if (popover.siblings(".popover").length && !popover.siblings(".popover").is(":hover")) {

so that it references exactly at that opened popover, and not any other (since now, through the delay, more than 1 could be open at the same time)

JQuery .on() method with multiple event handlers to one selector

I learned something really useful and fundamental from here.

chaining functions is very usefull in this case which works on most jQuery Functions including on function output too.

It works because output of most jQuery functions are the input objects sets so you can use them right away and make it shorter and smarter

function showPhotos() {

    .on("mouseenter", "li", showPhotos)
    .on("mouseleave", "li", showPhotos);

Disable hover effects on mobile browsers

You can trigger the mouseLeave event whenever you touch an element on touchscreen. Here is a solution for all <a> tags:

function removeHover() {
    var anchors = document.getElementsByTagName('a');
    for(i=0; i<anchors.length; i++) {
        anchors[i].addEventListener('touchstart', function(e){
        }, false);

How to prevent page scrolling when scrolling a DIV element?

Pure javascript version of Vidas's answer, el$ is the DOM node of the plane you are scrolling.

function onlyScrollElement(event, el$) {
    var delta = event.wheelDelta || -event.detail;
    el$.scrollTop += (delta < 0 ? 1 : -1) * 10;

Make sure you dont attach the even multiple times! Here is an example,

var ul$ = document.getElementById('yo-list');
// IE9, Chrome, Safari, Opera
ul$.removeEventListener('mousewheel', onlyScrollElement);
ul$.addEventListener('mousewheel', onlyScrollElement);
// Firefox
ul$.removeEventListener('DOMMouseScroll', onlyScrollElement);
ul$.addEventListener('DOMMouseScroll', onlyScrollElement);

Word of caution, the function there needs to be a constant, if you reinitialize the function each time before attaching it, ie. var func = function (...) the removeEventListener will not work.

How can I make a jQuery UI 'draggable()' div draggable for touchscreen?

After wasting many hours, I came across this!


It translates tap events as click events. Remember to load the script after jquery.

I got this working on the iPad and iPhone

$('#movable').draggable({containment: "parent"});

Click outside menu to close in jquery

I found a variant of Grsmto's solution and Dennis' solution fixed my issue.

$(".MainNavContainer").click(function (event) {
    //event.preventDefault();  // Might cause problems depending on implementation

    $(document).one('click', function (e) {
        if(!$('.MainNavContainer')) {
            // code to hide menus

Working around MySQL error "Deadlock found when trying to get lock; try restarting transaction"

The idea of retrying the query in case of Deadlock exception is good, but it can be terribly slow, since mysql query will keep waiting for locks to be released. And incase of deadlock mysql is trying to find if there is any deadlock, and even after finding out that there is a deadlock, it waits a while before kicking out a thread in order to get out from deadlock situation.

What I did when I faced this situation is to implement locking in your own code, since it is the locking mechanism of mysql is failing due to a bug. So I implemented my own row level locking in my java code:

private HashMap<String, Object> rowIdToRowLockMap = new HashMap<String, Object>();
private final Object hashmapLock = new Object();
public void handleShortCode(Integer rowId)
    Object lock = null;
      lock = rowIdToRowLockMap.get(rowId);
      if (lock == null)
          rowIdToRowLockMap.put(rowId, lock = new Object());
    synchronized (lock)
        // Execute your queries on row by row id

JS how to cache a variable

I have written a generic caching func() which will cache any variable easily and very readable format. Caching function:

function calculateSomethingMaybe(args){
  return args;

function caching(fn){
  const cache = {};
  return function(){
    const string = arguments[0];
      const result = fn.apply(this, arguments);
      cache[string] = result;
      return result;
    return cache[string];

const letsCache = caching(calculateSomethingMaybe);

console.log(letsCache('a book'), letsCache('a pen'), letsCache('a book'));

Could not find or load main class with a Jar File

I know this is an old question, but I had this problem recently and none of the answers helped me. However, Corral's comment on Ryan Atkinson's answer did tip me off to the problem.

I had all my compiled class files in target/classes, which are not packages in my case. I was trying to package it with jar cvfe App.jar target/classes App, from the root directory of my project, as my App class was in the default unnamed package.

This doesn't work, as the newly created App.jar will have the class App.class in the directory target/classes. If you try to run this jar with java -jar App.jar, it will complain that it cannot find the App class. This is because the packages inside App.jar don't match the actual packages in the project.

This could be solved by creating the jar directly from the target/classes directory, using jar cvfe App.jar . App. This is rather cumbersome in my opinion.

The simple solution is to list the folders you want to add with the -C option instead of using the default way of listing folders. So, in my case, the correct command is java cvfe App.jar App -C target/classes .. This will directly add all files in the target/classes directory to the root of App.jar, thus solving the problem.

How to close Android application?

Just write this code on your button EXIT click.

Intent intent = new Intent(getApplicationContext(), MainActivity.class);
intent.putExtra("LOGOUT", true);

And in the onCreate() method of your MainActivity.class write below code as a first line,

if (getIntent().getBooleanExtra("LOGOUT", false))

Oracle to_date, from mm/dd/yyyy to dd-mm-yyyy

You don't need to muck about with extracting parts of the date. Just cast it to a date using to_date and the format in which its stored, then cast that date to a char in the format you want. Like this:

select to_char(to_date('1/10/2011','mm/dd/yyyy'),'mm-dd-yyyy') from dual

Get parent of current directory from Python script

import os
import sys
from os.path import dirname, abspath

d = dirname(dirname(abspath(__file__)))
path1 = os.path.dirname(os.path.realpath(sys.argv[0]))
path = os.path.split(os.path.realpath(__file__))[0]

What is the equivalent of Java's System.out.println() in Javascript?

I'm using Chrome and print() literally prints the text on paper. This is what works for me:

document.write("My message");

Bootstrap onClick button event

There is no show event in js - you need to bind your button either to the click event:

$('#id').on('click', function (e) {

     //your awesome code here


Mind that if your button is inside a form, you may prefer to bind the whole form to the submit event.

Detect IE version (prior to v9) in JavaScript

// Detect ie <= 10
var ie = /MSIE ([0-9]+)/g.exec(window.navigator.userAgent)[1] || undefined;

// Return version ie or undefined if not ie or ie > 10

How to create a user in Django?

Have you confirmed that you are passing actual values and not None?

from django.shortcuts import render

def createUser(request):
    userName = request.REQUEST.get('username', None)
    userPass = request.REQUEST.get('password', None)
    userMail = request.REQUEST.get('email', None)

    # TODO: check if already existed
    if userName and userPass and userMail:
       u,created = User.objects.get_or_create(userName, userMail)
       if created:
          # user was created
          # set the password here
          # user was retrieved
       # request was empty

    return render(request,'home.html')

Bootstrap 3: How do you align column content to bottom of row

When working with bootsrap usually face three main problems:

  1. How to place the content of the column to the bottom?
  2. How to create a multi-row gallery of columns of equal height in one .row?
  3. How to center columns horizontally if their total width is less than 12 and the remaining width is odd?

To solve first two problems download this small plugin

The third problem is solved here

Common code

    [class*=col-] {position: relative}
    .row-conformity .to-bottom {position:absolute; bottom:0; left:0; right:0}
    .row-centered {text-align:center}   
    .row-centered [class*=col-] {display:inline-block; float:none; text-align:left; margin-right:-4px; vertical-align:top} 

<script src="assets/conformity/conformity.js"></script>
    $(document).ready(function () {
        $('.row-conformity > [class*=col-]').conformity();
        $(window).on('resize', function() {
            $('.row-conformity > [class*=col-]').conformity();

1. Aligning content of the column to the bottom

<div class="row row-conformity">
    <div class="col-sm-3">
    <div class="col-sm-3">
        <div class="to-bottom">
            I am on the bottom

2. Gallery of columns of equal height

<div class="row row-conformity">
    <div class="col-sm-4">We all have equal height</div>
    <div class="col-sm-4">...</div>
    <div class="col-sm-4">...</div>
    <div class="col-sm-4">...</div>
    <div class="col-sm-4">...</div>
    <div class="col-sm-4">...</div>

3. Horizontal alignment of columns to the center (less than 12 col units)

<div class="row row-centered">
    <div class="col-sm-3">...</div>
    <div class="col-sm-4">...</div>

All classes can work together

<div class="row row-conformity row-centered">

How to activate a specific worksheet in Excel?

I would recommend you to use worksheet's index instead of using worksheet's name, in this way you can also loop through sheets "dynamically"

for i=1 to thisworkbook.sheets.count
'You can add more code 
with activesheet
end with
next i

It will also, improve performance.

Distinct by property of class with LINQ

You can't effectively use Distinct on a collection of objects (without additional work). I will explain why.

The documentation says:

It uses the default equality comparer, Default, to compare values.

For objects that means it uses the default equation method to compare objects (source). That is on their hash code. And since your objects don't implement the GetHashCode() and Equals methods, it will check on the reference of the object, which are not distinct.

How to run server written in js with Node.js

Nodejs is a scripting language (like Python or Ruby, and unlike PHP or C++). To run your code, you need to enter a command in the terminal / shell / command prompt. Look for an application shortcut in your operating system by one of those names.

The command to run in the terminal will be

node server.js

But you will first need to browse in the terminal to the same folder as the file server.js. The syntax for using the terminal varies by operating system, look for its documentation.

How to give a Linux user sudo access?

You need run visudo and in the editor that it opens write:

igor    ALL=(ALL) ALL

That line grants all permissions to user igor.

If you want permit to run only some commands, you need to list them in the line:

igor    ALL=(ALL) /bin/kill, /bin/ps

Listing available com ports with Python

This is the code I use.

Successfully tested on Windows 8.1 x64, Windows 10 x64, Mac OS X 10.9.x / 10.10.x / 10.11.x and Ubuntu 14.04 / 14.10 / 15.04 / 15.10 with both Python 2 and Python 3.

import sys
import glob
import serial

def serial_ports():
    """ Lists serial port names

        :raises EnvironmentError:
            On unsupported or unknown platforms
            A list of the serial ports available on the system
    if sys.platform.startswith('win'):
        ports = ['COM%s' % (i + 1) for i in range(256)]
    elif sys.platform.startswith('linux') or sys.platform.startswith('cygwin'):
        # this excludes your current terminal "/dev/tty"
        ports = glob.glob('/dev/tty[A-Za-z]*')
    elif sys.platform.startswith('darwin'):
        ports = glob.glob('/dev/tty.*')
        raise EnvironmentError('Unsupported platform')

    result = []
    for port in ports:
            s = serial.Serial(port)
        except (OSError, serial.SerialException):
    return result

if __name__ == '__main__':

Connection timeout for SQL server

If you want to dynamically change it, I prefer using SqlConnectionStringBuilder .

It allows you to convert ConnectionString i.e. a string into class Object, All the connection string properties will become its Member.

In this case the real advantage would be that you don't have to worry about If the ConnectionTimeout string part is already exists in the connection string or not?

Also as it creates an Object and its always good to assign value in object rather than manipulating string.

Here is the code sample:

var sscsb = new SqlConnectionStringBuilder(_dbFactory.Database.ConnectionString);

sscsb.ConnectTimeout = 30;

var conn = new SqlConnection(sscsb.ConnectionString);

How to align texts inside of an input?

Here you go:

input[type=text] { text-align:right }
    <input type="text" name="name" value="">_x000D_

Switching to a TabBar tab view programmatically?

Use in AppDelegate.m file:

(void)tabBarController:(UITabBarController *)tabBarController
 didSelectViewController:(UIViewController *)viewController

     NSLog(@"Selected index: %d", tabBarController.selectedIndex);

    if (viewController == tabBarController.moreNavigationController)
        tabBarController.moreNavigationController.delegate = self;

    NSUInteger selectedIndex = tabBarController.selectedIndex;

    switch (selectedIndex) {

        case 0:
            NSLog(@"click me %u",self.tabBarController.selectedIndex);
        case 1:
            NSLog(@"click me again!! %u",self.tabBarController.selectedIndex);




How can I use jQuery in Greasemonkey?

If you are using chrome you have to opt for an alternative as Chromium does not support @require.

Source: The Chromium Project - User scripts

More details and alternatives on How can I use jQuery in Greasemonkey scripts in Google Chrome?

How to coerce a list object to type 'double'

If your list as multiple elements that need to be converted to numeric, you can achieve this with lapply(a, as.numeric).

How can I get the max (or min) value in a vector?

You can print it directly using max_element/min_element function. Eg:



How do I fetch only one branch of a remote Git repository?

  1. Pick any <remote_name> you'd like to use (feel free to use origin and skip step 1.)
  2. git remote add <remote_name> <remote_url>
  3. git fetch <remote_name> <branch>
  4. Pick any <your_local_branch_name> you'd like to use. Could be the same as <branch>.
  5. git checkout <remote_name>/<branch> -b <your_local_branch_name>

Hope that helps!

How to set all elements of an array to zero or any same value?

You could use memset, if you sure about the length.

memset(ptr, 0x00, length)

Is SMTP based on TCP or UDP?

In theory SMTP can be handled by either TCP, UDP, or some 3rd party protocol.

As defined in RFC 821, RFC 2821, and RFC 5321:

SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel.

In addition, the Internet Assigned Numbers Authority has allocated port 25 for both TCP and UDP for use by SMTP.

In practice however, most if not all organizations and applications only choose to implement the TCP protocol. For example, in Microsoft's port listing port 25 is only listed for TCP and not UDP.

The big difference between TCP and UDP that makes TCP ideal here is that TCP checks to make sure that every packet is received and re-sends them if they are not whereas UDP will simply send packets and not check for receipt. This makes UDP ideal for things like streaming video where every single packet isn't as important as keeping a continuous flow of packets from the server to the client.

Considering SMTP, it makes more sense to use TCP over UDP. SMTP is a mail transport protocol, and in mail every single packet is important. If you lose several packets in the middle of the message the recipient might not even receive the message and if they do they might be missing key information. This makes TCP more appropriate because it ensures that every packet is delivered.

ValueError: Length of values does not match length of index | Pandas DataFrame.unique()

The error comes up when you are trying to assign a list of numpy array of different length to a data frame, and it can be reproduced as follows:

A data frame of four rows:

df = pd.DataFrame({'A': [1,2,3,4]})

Now trying to assign a list/array of two elements to it:

df['B'] = [3,4]   # or df['B'] = np.array([3,4])

Both errors out:

ValueError: Length of values does not match length of index

Because the data frame has four rows but the list and array has only two elements.

Work around Solution (use with caution): convert the list/array to a pandas Series, and then when you do assignment, missing index in the Series will be filled with NaN:

df['B'] = pd.Series([3,4])

#   A     B
#0  1   3.0
#1  2   4.0
#2  3   NaN          # NaN because the value at index 2 and 3 doesn't exist in the Series
#3  4   NaN

For your specific problem, if you don't care about the index or the correspondence of values between columns, you can reset index for each column after dropping the duplicates:

df.apply(lambda col: col.drop_duplicates().reset_index(drop=True))

#   A     B
#0  1   1.0
#1  2   5.0
#2  7   9.0
#3  8   NaN

DateTime.TryParseExact() rejecting valid formats

Here you can check for couple of things.

  1. Date formats you are using correctly. You can provide more than one format for DateTime.TryParseExact. Check the complete list of formats, available here.
  2. CultureInfo.InvariantCulture which is more likely add problem. So instead of passing a NULL value or setting it to CultureInfo provider = new CultureInfo("en-US"), you may write it like. .

    if (!DateTime.TryParseExact(txtStartDate.Text, formats, 
                    System.Globalization.DateTimeStyles.None, out startDate))
        //your condition fail code goes here
        return false;
        //success code

When to use an interface instead of an abstract class and vice versa?

When to do what is a very simple thing if you have the concept clear in your mind.

Abstract classes can be Derived whereas Interfaces can be Implemented. There is some difference between the two. When you derive an Abstract class, the relationship between the derived class and the base class is 'is a' relationship. e.g., a Dog is an Animal, a Sheep is an Animal which means that a Derived class is inheriting some properties from the base class.

Whereas for implementation of interfaces, the relationship is "can be". e.g., a Dog can be a spy dog. A dog can be a circus dog. A dog can be a race dog. Which means that you implement certain methods to acquire something.

I hope I am clear.

php: how to get associative array key from numeric index?

If you only plan to work with one key in particular, you may accomplish this with a single line without having to store an array for all of the keys:

echo array_keys($array)[$i];

Should each and every table have a primary key?

I know that in order to use certain features of the gridview in .NET, you need a primary key in order for the gridview to know which row needs updating/deleting. General practice should be to have a primary key or primary key cluster. I personally prefer the former.

Docker Networking - nginx: [emerg] host not found in upstream

At the first glance, I missed, that my "web" service didn't actually start, so that's why nginx couldn't find any host

web_1    | python3: can't open file '/var/www/app/app/': [Errno 2] No such file or directory
web_1 exited with code 2
nginx_1  | [emerg] 1#1: host not found in upstream "web:4044" in /etc/nginx/conf.d/nginx.conf:2

Git fails when pushing commit to github

in these cases you can try ssh if https is stuck.

Also you can try increasing the buffer size to an astronomical figure so that you dont have to worry about the buffer size any more git config http.postBuffer 100000000

How to return the output of stored procedure into a variable in sql server

You can use the return statement inside a stored procedure to return an integer status code (and only of integer type). By convention a return value of zero is used for success.

If no return is explicitly set, then the stored procedure returns zero.

   CREATE PROCEDURE GetImmediateManager
      @employeeID INT,
      @managerID INT OUTPUT
     SELECT @managerID = ManagerID 
     FROM HumanResources.Employee 
     WHERE EmployeeID = @employeeID

     if @@rowcount = 0 -- manager not found?
       return 1;

And you call it this way:

DECLARE @return_status int;
DECLARE @managerID int;

EXEC @return_status = GetImmediateManager 2, @managerID output;
if @return_status = 1
  print N'Immediate manager not found!';
  print N'ManagerID is ' + @managerID;

You should use the return value for status codes only. To return data, you should use output parameters.

If you want to return a dataset, then use an output parameter of type cursor.

more on RETURN statement

How to check command line parameter in ".bat" file?

I've been struggling recently with the implementation of complex parameter switches in a batch file so here is the result of my research. None of the provided answers are fully safe, examples:

"%1"=="-?" will not match if the parameter is enclosed in quotes (needed for file names etc.) or will crash if the parameter is in quotes and has spaces (again often seen in file names)

echo starting parameter test...
rem echo First parameter is %1
if "%1"=="-?" (echo Condition is true, param=%1) else (echo Condition is false, param=%1)
C:\>test.bat -?

starting parameter test...

Condition is true, param=-?

C:\>test.bat "-?"

starting parameter test...

Condition is false, param="-?"

Any combination with square brackets [%1]==[-?] or [%~1]==[-?] will fail in case the parameter has spaces within quotes:

echo starting parameter test...
echo First parameter is %1
if [%~1]==[-?] (echo Condition is true, param=%1) else (echo Condition is false, param=%1)

C:\>test.bat "long file name"

starting parameter test...

First parameter is "long file name"
file was unexpected at this time.

The proposed safest solution "%~1"=="-?" will crash with a complex parameter that includes text outside the quotes and text with spaces within the quotes:

echo starting parameter test...
echo First parameter is %1
if "%~1"=="-?" (echo Condition is true, param=%1) else (echo Condition is false, param=%1)

C:\>test.bat -source:"long file name"

starting parameter test...

First parameter is -source:"long file name"
file was unexpected at this time.

The only way to ensure all above scenarios are covered is to use EnableDelayedExpansion and to pass the parameters by reference (not by value) using variables. Then even the most complex scenario will work fine:

SETLOCAL EnableDelayedExpansion
echo starting parameter test...
echo First parameter is %1
:: we assign the parameter to a variable to pass by reference with delayed expansion
set "var1=%~1"
echo var1 is !var1!
:: we assign the value to compare with to a second variable to pass by reference with delayed expansion
set "var2=-source:"c:\app images"\image.png"
echo var2 is !var2!
if "!var1!"=="!var2!" (echo Condition is true, param=!var1!) else (echo Condition is false, param=!var1!)
C:\>test.bat -source:"c:\app images"\image.png

starting parameter test...

First parameter is -source:"c:\app images"\image.png
var1 is -source:"c:\app images"\image.png
var2 is -source:"c:\app images"\image.png
Condition is true, param=-source:"c:\app images"\image.png

C:\>test.bat -source:"c:\app images"\image1.png

starting parameter test...

First parameter is -source:"c:\app images"\image1.png
var1 is -source:"c:\app images"\image1.png
var2 is -source:"c:\app images"\image.png
Condition is false, param=-source:"c:\app images"\image1.png

C:\>test.bat -source:"c:\app images\image.png"

starting parameter test...

First parameter is -source:"c:\app images\image.png"
var1 is -source:"c:\app images\image.png"
var2 is -source:"c:\app images"\image.png
Condition is false, param=-source:"c:\app images\image.png"

Check if a class is derived from a generic class

You can try this extension

    public static bool IsSubClassOfGenericClass(this Type type, Type genericClass,Type t)
        return type.IsSubclassOf(genericClass.MakeGenericType(new[] { t }));

DynamoDB vs MongoDB NoSQL

We chose a combination of Mongo/Dynamo for a healthcare product. Basically mongo allows better searching, but the hosted Dynamo is great because its HIPAA compliant without any extra work. So we host the mongo portion with no personal data on a standard setup and allow amazon to deal with the HIPAA portion in terms of infrastructure. We can query certain items from mongo which bring up documents with pointers (ID's) of the relatable Dynamo document.

The main reason we chose to do this using mongo instead of hosting the entire application on dynamo was for 2 reasons. First, we needed to preform location based searches which mongo is great at and at the time, Dynamo was not, but they do have an option now.

Secondly was that some documents were unstructured and we did not know ahead of time what the data would be, so for example lets say user a inputs a document in the "form" collection like this: {"username": "user1", "email": "[email protected]"}. And another user puts this in the same collection {"phone": "813-555-3333", "location": [28.1234,-83.2342]}. With mongo we can search any of these dynamic and unknown fields at any time, with Dynamo, you could do this but would have to make a index every time a new field was added that you wanted searchable. So if you have never had a phone field in your Dynamo document before and then all of the sudden, some one adds it, its completely unsearchable.

Now this brings up another point in which you have mentioned. Sometimes choosing the right solution for the job does not always mean choosing the best product for the job. For example you may have a client who needs and will use the system you created for 10+ years. Going with a SaaS/IaaS solution that is good enough to get the job done may be a better option as you can rely on amazon to have up-kept and maintained their systems over the long haul.

Angular2 QuickStart npm start is not working correctly

I encountered this same issue. However, none of the above answers were proper solutions for me. It turns out it was due more to my dev environment then any of the versions of things.

Since I used Visual Studio Code, I set up a build task in VSC to compile TypeScript as a watcher. This was the issue. VSC had already started a NPM task for TSC and so when executing the tutorial's 'start' script, it was having issues with the fact that VSC was still running tsc -w.

I stopped the task in VSC and reran the 'start' script and it worked just fine.

Solution A: Stop and npm Start

  • VSC Command>Tasks: Terminate running tasks
  • Terminal $ npm start

After that to bring everything working together I change the start script to just start the server and not actually launch TSC.

Solution B: Change npm start script

  • Replace

    "start": "concurrent \"npm run tsc:w\" \"npm run lite\" "

  • with

    "start": "npm run lite"

Solution C: Just run the lite server command

`npm run lite`

Style input type file?

Same solution via Jquery. Works if you have more than one file input in the page.

$j(".filebutton").click(function() {
    var input = $j(this).next().find('input');;


    var file = $j(this).val();
    var fileName = file.split("\\");
    var pai =$j(this).parent().parent().prev();

Prevent line-break of span element

If you only need to prevent line-breaks on space characters, you can use &nbsp; entities between words:


instead of

<span style="white-space:nowrap">No line break</span>

NSOperation vs Grand Central Dispatch

Another reason to prefer NSOperation over GCD is the cancelation mechanism of NSOperation. For example, an App like 500px that shows dozens of photos, use NSOperation we can cancel requests of invisible image cells when we scroll table view or collection view, this can greatly improve App performance and reduce memory footprint. GCD can't easily support this.

Also with NSOperation, KVO can be possible.

Here is an article from Eschaton which is worth reading.

Fixed height and width for bootstrap carousel

In your main styles.css file change height/auto to whatever settings you desire. For example, 500px:

#myCarousel {
  height: auto;
  width: auto;
  overflow: hidden;

Programmatically trigger "select file" dialog box

This worked for me:


Handling null values in Freemarker

Starting from freemarker 2.3.7, you can use this syntax :


or, if you want display a default text when the attribute is null :

${(object.attribute)!"default text"}

How to allow Cross domain request in apache2

OS=GNU/Linux Debian

Change in /etc/apache2/apache2.conf

<Directory /var/www/html>
     Order Allow,Deny
     Allow from all
     AllowOverride all
     Header set Access-Control-Allow-Origin "*"

Add/activate module

 a2enmod headers 

Restart service

/etc/init.d/apache2 restart

Which "href" value should I use for JavaScript links, "#" or "javascript:void(0)"?

I would use:

<a href="#" onclick="myJsFunc();return false;">Link</a>


  1. This makes the href simple, search engines need it. If you use anything else ( such as a string), it may cause a 404 not found error.
  2. When mouse hovers over the link, it doesn't show that it is a script.
  3. By using return false;, the page doesn't jump to the top or break the back button.

Adding an arbitrary line to a matplotlib plot in ipython notebook

You can directly plot the lines you want by feeding the plot command with the corresponding data (boundaries of the segments):

plot([x1, x2], [y1, y2], color='k', linestyle='-', linewidth=2)

(of course you can choose the color, line width, line style, etc.)

From your example:

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(1, 101)
y = 20 + 3 * x + np.random.normal(0, 60, 100)
plt.plot(x, y, "o")

# draw vertical line from (70,100) to (70, 250)
plt.plot([70, 70], [100, 250], 'k-', lw=2)

# draw diagonal line from (70, 90) to (90, 200)
plt.plot([70, 90], [90, 200], 'k-')

new chart

Bootstrap combining rows (rowspan)

Divs stack vertically by default, so there is no need for special handling of "rows" within a column.

div {_x000D_
.short-div {_x000D_
<link href="" rel="stylesheet" />_x000D_
<div class="container">_x000D_
  <h1>Responsive Bootstrap</h1>_x000D_
  <div class="row">_x000D_
    <div class="col-lg-5 col-md-5 col-sm-5 col-xs-5" style="background-color:red;">Span 5</div>_x000D_
    <div class="col-lg-3 col-md-3 col-sm-3 col-xs-3" style="background-color:blue">Span 3</div>_x000D_
    <div class="col-lg-2 col-md-2 col-sm-3 col-xs-2" style="padding:0px">_x000D_
      <div class="short-div" style="background-color:green">Span 2</div>_x000D_
      <div class="short-div" style="background-color:purple">Span 2</div>_x000D_
    <div class="col-lg-2 col-md-2 col-sm-3 col-xs-2" style="background-color:yellow">Span 2</div>_x000D_
<div class="container-fluid">_x000D_
  <div class="row-fluid">_x000D_
    <div class="col-lg-6 col-md-6 col-sm-6 col-xs-6">_x000D_
      <div class="short-div" style="background-color:#999">Span 6</div>_x000D_
      <div class="short-div">Span 6</div>_x000D_
    <div class="col-lg-6 col-md-6 col-sm-6 col-xs-6" style="background-color:#ccc">Span 6</div>_x000D_

Here's the fiddle.

The specified child already has a parent. You must call removeView() on the child's parent first

I encountered this error whenever I omitted a parameter while inflating the view for a fragment in the onCreateView() method like so:

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view=inflater.inflate(R.layout.fragment_reject, container);
    return view;

The solution is to change the view inflation line to:

View view=inflater.inflate(R.layout.fragment_reject, container,false);

The explanation can be found at the Android guide for fragments

Quoting from the guide, the final parameter in the view initialization statement is false because:

"the system is already inserting the inflated layout into the container—passing true would create a redundant view group in the final layout"

How to display images from a folder using php - PHP

You had a mistake on the statement below. Use . not ,

echo '<img src="', $dir, '/', $file, '" alt="', $file, $


echo '<img src="'. $dir. '/'. $file. '" alt="'. $file. $


echo 'Directory \'', $dir, '\' not found!';


echo 'Directory \''. $dir. '\' not found!';

What is the use of the %n format specifier in C?

Most of these answers explain what %n does (which is to print nothing and to write the number of characters printed thus far to an int variable), but so far no one has really given an example of what use it has. Here is one:

int n;
printf("%s: %nFoo\n", "hello", &n);
printf("%*sBar\n", n, "");

will print:

hello: Foo

with Foo and Bar aligned. (It's trivial to do that without using %n for this particular example, and in general one always could break up that first printf call:

int n = printf("%s: ", "hello");
printf("%*sBar\n", n, "");

Whether the slightly added convenience is worth using something esoteric like %n (and possibly introducing errors) is open to debate.)

How can I check if a Perl array contains a particular value?

If you need to know the amount of every element in array besides existing of that element you may use

my %bad_param_lookup;
@bad_param_lookup{ @bad_params } = ( 1 ) x @bad_params;
%bad_param_lookup = map { $_ => $bad_param_lookup{$_}++} @bad_params;

and then for every $i that is in @bad_params, $bad_param_lookup{$i} contains amount of $i in @bad_params

Java: Reading integers from a file into an array

File file = new File("E:/Responsibility.txt");  
    Scanner scanner = new Scanner(file);
    List<Integer> integers = new ArrayList<>();
    while (scanner.hasNext()) {
        if (scanner.hasNextInt()) {
        } else {

Maven: Failed to read artifact descriptor

I had the same problem for a while and despite doing mvn -U clean install the problem was not getting solved!

I finally solved the problem by deleting the whole .m2 folder and then restarted my IDE and the problem was gone!

So sometimes the problem would rise because of some incompatibilities or problems in your local maven repository.

How to export settings?

I'm preferred my own way to synchronize all Visual Studio Code extensions between laptops, using .dotfiles and small script to perform updates automatically. This way helps me every time when I want to install all extensions I have without any single mouse activity in Visual Studio Code after installing (via Homebrew).

So I just write each new added extension to .txt file stored at my .dotfiles folder. After that I pull master branch on another laptop to get up-to-date file with all extensions.

Using the script, which Big Rich had written before, with one more change, I can totally synchronise all extensions almost automatically.


cat dart-extensions.txt | xargs -L 1 code --install-extension

And also there is one more way to automate that process. Here you can add a script which looks up a Visual Studio Code extension in realtime and each time when you take a diff between the code --list-extensions command and your .txt file in .dotfiles, you can easily update your file and push it to your remote repository.

Could not connect to SMTP host: localhost, port: 25; nested exception is: Connection refused: connect

The mail server on CentOS 6 and other IPv6 capable server platforms may be bound to IPv6 localhost (::1) instead of IPv4 localhost (

Typical symptoms:

[root@host /]# telnet 25
telnet: connect to address Connection refused

[root@host /]# telnet localhost 25
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 host ESMTP Exim 4.72 Wed, 14 Aug 2013 17:02:52 +0100

[root@host /]# netstat -plant | grep 25
tcp        0      0 :::25                       :::*                        LISTEN      1082/exim           

If this happens, make sure that you don't have two entries for localhost in /etc/hosts with different IP addresses, like this (bad) example:

[root@host /]# cat /etc/hosts localhost.localdomain localhost localhost4.localdomain4 localhost4
::1       localhost localhost.localdomain localhost6 localhost6.localdomain6

To avoid confusion, make sure you only have one entry for localhost, preferably an IPv4 address, like this:

[root@host /]# cat /etc/hosts localhost  localhost.localdomain   localhost4.localdomain4 localhost4
::1       localhost6 localhost6.localdomain6

Confused about __str__ on list in Python

Because of the infinite superiority of Python over Java, Python has not one, but two toString operations.

One is __str__, the other is __repr__

__str__ will return a human readable string. __repr__ will return an internal representation.

__repr__ can be invoked on an object by calling repr(obj) or by using backticks `obj`.

When printing lists as well as other container classes, the contained elements will be printed using __repr__.

Inserting values into tables Oracle SQL

You can expend the following function in order to pull out more parameters from the DB before the insert:

-- insert_employee  (Function) 
CREATE OR REPLACE FUNCTION insert_employee(p_emp_id in number, p_emp_name in varchar2, p_emp_address in varchar2, p_emp_state in varchar2, p_emp_position in varchar2, p_emp_manager in varchar2) 

   p_state_id varchar2(30) := '';
      select state_id 
      into   p_state_id
      from states where lower(emp_state) = state_name;

      INSERT INTO Employee (emp_id, emp_name, emp_address, emp_state, emp_position, emp_manager) VALUES 
                (p_emp_id, p_emp_name, p_emp_address, p_state_id, p_emp_position, p_emp_manager);

    return 'SUCCESS';

   WHEN others THEN

C++ IDE for Linux?

Also you can try to setup emacs as an IDE.

Details are discussed here.

Java string split with "." (dot)

I believe you should escape the dot. Try:

String filename = "D:/some folder/001.docx";
String extensionRemoved = filename.split("\\.")[0];

Otherwise dot is interpreted as any character in regular expressions.

Rename Oracle Table or View

ALTER TABLE mytable RENAME TO othertable

In Oracle 10g also:

RENAME mytable TO othertable

How can I delete one element from an array by value

I think I've figured it out:

a = [3, 2, 4, 6, 3, 8]
#=> 3
#=> [2, 4, 6, 8]

Trying to detect browser close event

Try following code works for me under Linux chrome environment. Before running make sure jquery is attached to the document.

    $(window).bind("beforeunload", function() { 
        return confirm("Do you really want to close?"); 

For simple follow following steps:

  1. open
  2. enter something into html, css or javascript box
  3. try to close tab in chrome

It should show following picture:

enter image description here

conversion from infix to prefix

I saw this method on youtube hence posting here.

given infix expression : (a–b)/c*(d + e – f / g)

reverse it :


read characters from left to right.
maintain one stack for operators

 1. if character is operand add operand to the output
 2. else if character is operator or )
   2.1 while operator on top of the stack has lower or **equal** precedence than this character pop
   2.2 add the popped character to the output.
   push the character on stack

 3. else if character is parenthesis ( 
    3.1 [ same as 2 till you encounter ) . pop ) as well
 4. // no element left to read
   4.1 pop operators from stack till it is not empty
   4.2 add them to the output. 

reverse the output and print.

credits : youtube

Understanding colors on Android (six characters)

at new chrome version (maybe 67.0.3396.62) , CSS hex color can use this model display,



cc is opacity , but old chrome not support that mod

How can I make this try_files directive work?

a very common try_files line which can be applied on your condition is

location / {
    try_files $uri $uri/ /test/index.html;

you probably understand the first part, location / matches all locations, unless it's matched by a more specific location, like location /test for example

The second part ( the try_files ) means when you receive a URI that's matched by this block try $uri first, for example nginx will try to check if there's a file inside /images called image.jpg if found it will serve it first.

Second condition is $uri/ which means if you didn't find the first condition $uri try the URI as a directory, for example, ngixn will first check if a file called images exists then it wont find it, then goes to second check $uri/ and see if there's a directory called images exists then it will try serving it.

Side note: if you don't have autoindex on you'll probably get a 403 forbidden error, because directory listing is forbidden by default.

EDIT: I forgot to mention that if you have index defined, nginx will try to check if the index exists inside this folder before trying directory listing.

Third condition /test/index.html is considered a fall back option, (you need to use at least 2 options, one and a fall back), you can use as much as you can (never read of a constriction before), nginx will look for the file index.html inside the folder test and serve it if it exists.

If the third condition fails too, then nginx will serve the 404 error page.

Also there's something called named locations, like this

location @error {

You can call it with try_files like this

try_files $uri $uri/ @error;

TIP: If you only have 1 condition you want to serve, like for example inside folder images you only want to either serve the image or go to 404 error, you can write a line like this

location /images {
    try_files $uri =404;

which means either serve the file or serve a 404 error, you can't use only $uri by it self without =404 because you need to have a fallback option.
You can also choose which ever error code you want, like for example:

location /images {
    try_files $uri =403;

This will show a forbidden error if the image doesn't exist, or if you use 500 it will show server error, etc ..


You can achieve what you want with the mysql console with the -s (--silent) option passed in.

It's probably a good idea to also pass in the -r (--raw) option so that special characters don't get escaped. You can use this to pipe queries like you're wanting.

mysql -u username -h hostname -p -s -r -e "select concat('this',' ','works')"

EDIT: Also, if you want to remove the column name from your output, just add another -s (mysql -ss -r etc.)

How to add a constant column in a Spark DataFrame?

In spark 2.2 there are two ways to add constant value in a column in DataFrame:

1) Using lit

2) Using typedLit.

The difference between the two is that typedLit can also handle parameterized scala types e.g. List, Seq, and Map

Sample DataFrame:

val df = spark.createDataFrame(Seq((0,"a"),(1,"b"),(2,"c"))).toDF("id", "col1")

| id|col1|
|  0|   a|
|  1|   b|

1) Using lit: Adding constant string value in new column named newcol:

import org.apache.spark.sql.functions.lit
val newdf = df.withColumn("newcol",lit("myval"))


| id|col1|newcol|
|  0|   a| myval|
|  1|   b| myval|

2) Using typedLit:

import org.apache.spark.sql.functions.typedLit
df.withColumn("newcol", typedLit(("sample", 10, .044)))


| id|col1|           newcol|
|  0|   a|[sample,10,0.044]|
|  1|   b|[sample,10,0.044]|
|  2|   c|[sample,10,0.044]|

What is the difference between public, private, and protected?

 * Define MyClass
class MyClass
    public $public = 'Public';
    protected $protected = 'Protected';
    private $private = 'Private';

    function printHello()
        echo $this->public;
        echo $this->protected;
        echo $this->private;

$obj = new MyClass();
echo $obj->public; // Works
echo $obj->protected; // Fatal Error
echo $obj->private; // Fatal Error
$obj->printHello(); // Shows Public, Protected and Private

 * Define MyClass2
class MyClass2 extends MyClass
    // We can redeclare the public and protected method, but not private
    protected $protected = 'Protected2';

    function printHello()
        echo $this->public;
        echo $this->protected;
        echo $this->private;

$obj2 = new MyClass2();
echo $obj2->public; // Works
echo $obj2->private; // Undefined
echo $obj2->protected; // Fatal Error
$obj2->printHello(); // Shows Public, Protected2, Undefined

Extracted From :

Flexbox and Internet Explorer 11 (display:flex in <html>?)

Use another flex container to fix the min-height issue in IE10 and IE11:


<div class="ie-fixMinHeight">
    <div id="page">
        <div id="header"></div>
        <div id="content"></div>
        <div id="footer"></div>


.ie-fixMinHeight {

#page {

#content {

See a working demo.

  • Don't use flexbox layout directly on body because it screws up elements inserted via jQuery plugins (autocomplete, popup, etc.).
  • Don't use height:100% or height:100vh on your container because the footer will stick at the bottom of window and won't adapt to long content.
  • Use flex-grow:1 rather than flex:1 cause IE10 and IE11 default values for flex are 0 0 auto and not 0 1 auto.

How do I create a simple Qt console application in C++?

You don't need the QCoreApplication at all, just include your Qt objects as you would other objects, for example:

#include <QtCore>

int main()
    QVector<int> a; // Qt object

    for (int i=0; i<10; i++)

    /* manipulate a here */

    return 0;

jQuery Datepicker with text input that doesn't allow user input

replace the ID of time picker: IDofDatetimePicker to your id.

This will prevent the user from entering any further keyboard inputs but still, the user will be able to access the time popup.

$("#my_txtbox").keypress(function(event) {event.preventDefault();});

Try this source:

kubectl apply vs kubectl create?

When running in a CI script, you will have trouble with imperative commands as create raises an error if the resource already exists.

What you can do is applying (declarative pattern) the output of your imperative command, by using --dry-run=true and -o yaml options:

kubectl create whatever --dry-run=true -o yaml | kubectl apply -f -

The command above will not raise an error if the resource already exists (and will update the resource if needed).

This is very useful in some cases where you cannot use the declarative pattern (for instance when creating a docker-registry secret).

Why do I get PLS-00302: component must be declared when it exists?

I came here because I had the same problem.
What was the problem for me was that the procedure was defined in the package body, but not in the package header.
I was executing my function with a lose BEGIN END statement.

Unix command to find lines common in two files

Maybe you mean comm ?

Compare sorted files FILE1 and FILE2 line by line.

With no options, produce three-column output. Column one contains lines unique to FILE1, column two contains lines unique to FILE2, and column three contains lines common to both files.

The secret in finding these information are the info pages. For GNU programs, they are much more detailed than their man-pages. Try info coreutils and it will list you all the small useful utils.

Using Eloquent ORM in Laravel to perform search of database using LIKE

If you need to frequently use LIKE, you can simplify the problem a bit. A custom method like () can be created in the model that inherits the Eloquent ORM:

public  function scopeLike($query, $field, $value){
        return $query->where($field, 'LIKE', "%$value%");

So then you can use this method in such way:

User::like('name', 'Tomas')->get();

Add CSS3 transition expand/collapse

OMG, I tried to find a simple solution to this for hours. I knew the code was simple but no one provided me what I wanted. So finally got to work on some example code and made something simple that anyone can use no JQuery required. Simple javascript and css and html. In order for the animation to work you have to set the height and width or the animation wont work. Found that out the hard way.

        function dostuff() {
            if (document.getElementById('MyBox').style.height == "0px") {

                document.getElementById('MyBox').setAttribute("style", "background-color: #45CEE0; height: 200px; width: 200px; transition: all 2s ease;"); 
            else {
                document.getElementById('MyBox').setAttribute("style", "background-color: #45CEE0; height: 0px; width: 0px; transition: all 2s ease;"); 
    <div id="MyBox" style="height: 0px; width: 0px;">

    <input type="button" id="buttontest" onclick="dostuff()" value="Click Me">

How to add new line into txt file

var Line = textBox1.Text + "," + textBox2.Text;

File.AppendAllText(@"C:\Documents\m2.txt", Line + Environment.NewLine);

How to create a fix size list in python?

Note also that when you used arrays in C++ you might have had somewhat different needs, which are solved in different ways in Python:

  1. You might have needed just a collection of items; Python lists deal with this usecase just perfectly.
  2. You might have needed a proper array of homogenous items. Python lists are not a good way to store arrays.

Python solves the need in arrays by NumPy, which, among other neat things, has a way to create an array of known size:

from numpy import *

l = zeros(10)

How to get data from Magento System Configuration

you should you use following code

$configValue = Mage::getStoreConfig(

Mage::app()->getStore() this will add store code in fetch values so that you can get correct configuration values for current store this will avoid incorrect store's values because magento is also use for multiple store/views so must add store code to fetch anything in magento.

if we have more then one store or multiple views configured then this will insure that we are getting values for current store

Differences between hard real-time, soft real-time, and firm real-time?

The simplest way to distinguish between the different kinds of real-time system types is answering the question:

Is a delayed system response (after the deadline) is still useful or not?

So depending on the answer you get for this question, your system could be included as one of the following categories:

  1. Hard: No, and delayed answers are considered a system failure

This is the case when missing the dead-line will make the system unusable. For example the system controlling the car Airbag system should detect the crash and inflate rapidly the bag. The whole process takes more or less one-twenty-fifth of a second. Thus, if the system for example react with 1 second of delay the consequences could be mortal and it will be no benefit having the bag inflated once the car has already crashed.

  1. Firm: No, but delayed answers are not necessary a system failure

This is the case when missing the deadline is tolerable but it will affect the quality of the service. As a simple example consider a video encryption system. Normally the password of encryption is generated in the server (video Head end) and sent to the customer set-top box. This process should be synchronized so normally the set-top box receives the password before starts receiving the encrypted video frames. In this case a delay it may lead to video glitches since the set-top box is not able to decode the frames because it hasn't received the password yet. In this case the service (film, an interesting football match, etc) could be affected by not meeting the deadline. Receiving the password with delay in this case is not useful since the frames encrypted with the same have already caused the glitches.

  1. Soft: Yes, but the system service is degraded

As from the the wikipedia description the usefulness of a result degrades after its deadline. That means, getting a response from the system out of the deadline is still useful for the end user but its usefulness degrade after reaching the deadline. A simple example for this case is a software that automatically controls the temperature of a room (or a building). In this case if the system has some delays reading the temperature sensors it will be a little bit slow to react upon brusque temperature changes. However, at the end it will end up reacting to the change and adjusting accordingly the temperature to keep it constant for example. So in this case the delayed reaction is useful, but it degrades the system quality of service.

How to add a classname/id to React-Bootstrap Component?

1st way is to use props

<Row id = "someRandomID">

Wherein, in the Definition, you may just go

const Row = props  => {
 div id = {}

The same could be done with class, replacing id with className in the above example.

You might as well use react-html-id, that is an npm package. This is an npm package that allows you to use unique html IDs for components without any dependencies on other libraries.

Ref: react-html-id


JavaScript hashmap equivalent

Adding yet another solution: HashMap is pretty much the first class I ported from Java to JavaScript. You could say there is a lot of overhead, but the implementation is almost 100% equal to Java's implementation and includes all interfaces and subclasses.

The project can be found here: I'll also attach the (current) source code for the HashMap class, but as stated it also depends on the super class, etc. The OOP framework used is qooxdoo.

Please note that this code is already out-dated and refer to the GitHub project for the current work. As of writing this, there is also an ArrayList implementation.

qx.Class.define( 'jsava.util.HashMap', {
    extend: jsava.util.AbstractMap,
    implement: [jsava.util.Map,, jsava.lang.Cloneable],

    construct: function () {
        var args = arguments ),
            initialCapacity = this.self( arguments ).DEFAULT_INITIAL_CAPACITY,
            loadFactor = this.self( arguments ).DEFAULT_LOAD_FACTOR;

        switch( args.length ) {
            case 1:
                if( qx.Class.implementsInterface( args[0], jsava.util.Map ) ) {
                    initialCapacity = Math.max( ((args[0].size() / this.self( arguments ).DEFAULT_LOAD_FACTOR) | 0) + 1,
                        this.self( arguments ).DEFAULT_INITIAL_CAPACITY );
                    loadFactor = this.self( arguments ).DEFAULT_LOAD_FACTOR;
                } else {
                    initialCapacity = args[0];
            case 2:
                initialCapacity = args[0];
                loadFactor = args[1];

        if( initialCapacity < 0 ) {
            throw new jsava.lang.IllegalArgumentException( 'Illegal initial capacity: ' + initialCapacity );
        if( initialCapacity > this.self( arguments ).MAXIMUM_CAPACITY ) {
            initialCapacity = this.self( arguments ).MAXIMUM_CAPACITY;
        if( loadFactor <= 0 || isNaN( loadFactor ) ) {
            throw new jsava.lang.IllegalArgumentException( 'Illegal load factor: ' + loadFactor );

        var capacity = 1;
        while( capacity < initialCapacity ) {
            capacity <<= 1;

        this._loadFactor = loadFactor;
        this._threshold = (capacity * loadFactor) | 0;
        this._table = jsava.JsavaUtils.emptyArrayOfGivenSize( capacity, null );

    statics: {
        serialVersionUID: 1,

        MAXIMUM_CAPACITY: 1 << 30,
        DEFAULT_LOAD_FACTOR: 0.75,

        _hash: function (hash) {
            hash ^= (hash >>> 20) ^ (hash >>> 12);
            return hash ^ (hash >>> 7) ^ (hash >>> 4);

        _indexFor: function (hashCode, length) {
            return hashCode & (length - 1);

        Entry: qx.Class.define( 'jsava.util.HashMap.Entry', {
            extend: jsava.lang.Object,
            implement: [jsava.util.Map.Entry],

            construct: function (hash, key, value, nextEntry) {
                this._value = value;
                this._next = nextEntry;
                this._key = key;
                this._hash = hash;

            members: {
                _key: null,
                _value: null,
                /** @type jsava.util.HashMap.Entry */
                _next: null,
                /** @type Number */
                _hash: 0,

                getKey: function () {
                    return this._key;

                getValue: function () {
                    return this._value;

                setValue: function (newValue) {
                    var oldValue = this._value;
                    this._value = newValue;
                    return oldValue;

                equals: function (obj) {
                    if( obj === null || !qx.Class.implementsInterface( obj, jsava.util.HashMap.Entry ) ) {
                        return false;

                    /** @type jsava.util.HashMap.Entry */
                    var entry = obj,
                        key1 = this.getKey(),
                        key2 = entry.getKey();
                    if( key1 === key2 || (key1 !== null && key1.equals( key2 )) ) {
                        var value1 = this.getValue(),
                            value2 = entry.getValue();
                        if( value1 === value2 || (value1 !== null && value1.equals( value2 )) ) {
                            return true;

                    return false;

                hashCode: function () {
                    return (this._key === null ? 0 : this._key.hashCode()) ^
                        (this._value === null ? 0 : this._value.hashCode());

                toString: function () {
                    return this.getKey() + '=' + this.getValue();

                 * This method is invoked whenever the value in an entry is
                 * overwritten by an invocation of put(k,v) for a key k that's already
                 * in the HashMap.
                _recordAccess: function (map) {

                 * This method is invoked whenever the entry is
                 * removed from the table.
                _recordRemoval: function (map) {
        } )

    members: {
        /** @type jsava.util.HashMap.Entry[] */
        _table: null,
        /** @type Number */
        _size: 0,
        /** @type Number */
        _threshold: 0,
        /** @type Number */
        _loadFactor: 0,
        /** @type Number */
        _modCount: 0,
        /** @implements jsava.util.Set */
        __entrySet: null,

         * Initialization hook for subclasses. This method is called
         * in all constructors and pseudo-constructors (clone, readObject)
         * after HashMap has been initialized but before any entries have
         * been inserted.  (In the absence of this method, readObject would
         * require explicit knowledge of subclasses.)
        _init: function () {

        size: function () {
            return this._size;

        isEmpty: function () {
            return this._size === 0;

        get: function (key) {
            if( key === null ) {
                return this.__getForNullKey();

            var hash = this.self( arguments )._hash( key.hashCode() );
            for( var entry = this._table[this.self( arguments )._indexFor( hash, this._table.length )];
                 entry !== null; entry = entry._next ) {
                /** @type jsava.lang.Object */
                var k;
                if( entry._hash === hash && ((k = entry._key) === key || key.equals( k )) ) {
                    return entry._value;

            return null;

        __getForNullKey: function () {
            for( var entry = this._table[0]; entry !== null; entry = entry._next ) {
                if( entry._key === null ) {
                    return entry._value;

            return null;

        containsKey: function (key) {
            return this._getEntry( key ) !== null;

        _getEntry: function (key) {
            var hash = (key === null) ? 0 : this.self( arguments )._hash( key.hashCode() );
            for( var entry = this._table[this.self( arguments )._indexFor( hash, this._table.length )];
                 entry !== null; entry = entry._next ) {
                /** @type jsava.lang.Object */
                var k;
                if( entry._hash === hash
                    && ( ( k = entry._key ) === key || ( key !== null && key.equals( k ) ) ) ) {
                    return entry;

            return null;

        put: function (key, value) {
            if( key === null ) {
                return this.__putForNullKey( value );

            var hash = this.self( arguments )._hash( key.hashCode() ),
                i = this.self( arguments )._indexFor( hash, this._table.length );
            for( var entry = this._table[i]; entry !== null; entry = entry._next ) {
                /** @type jsava.lang.Object */
                var k;
                if( entry._hash === hash && ( (k = entry._key) === key || key.equals( k ) ) ) {
                    var oldValue = entry._value;
                    entry._value = value;
                    entry._recordAccess( this );
                    return oldValue;

            this._addEntry( hash, key, value, i );
            return null;

        __putForNullKey: function (value) {
            for( var entry = this._table[0]; entry !== null; entry = entry._next ) {
                if( entry._key === null ) {
                    var oldValue = entry._value;
                    entry._value = value;
                    entry._recordAccess( this );
                    return oldValue;

            this._addEntry( 0, null, value, 0 );
            return null;

        __putForCreate: function (key, value) {
            var hash = (key === null) ? 0 : this.self( arguments )._hash( key.hashCode() ),
                i = this.self( arguments )._indexFor( hash, this._table.length );
            for( var entry = this._table[i]; entry !== null; entry = entry._next ) {
                /** @type jsava.lang.Object */
                var k;
                if( entry._hash === hash
                    && ( (k = entry._key) === key || ( key !== null && key.equals( k ) ) ) ) {
                    entry._value = value;

            this._createEntry( hash, key, value, i );

        __putAllForCreate: function (map) {
            var iterator = map.entrySet().iterator();
            while( iterator.hasNext() ) {
                var entry =;
                this.__putForCreate( entry.getKey(), entry.getValue() );

        _resize: function (newCapacity) {
            var oldTable = this._table,
                oldCapacity = oldTable.length;
            if( oldCapacity === this.self( arguments ).MAXIMUM_CAPACITY ) {
                this._threshold = Number.MAX_VALUE;

            var newTable = jsava.JsavaUtils.emptyArrayOfGivenSize( newCapacity, null );
            this._transfer( newTable );
            this._table = newTable;
            this._threshold = (newCapacity * this._loadFactor) | 0;

        _transfer: function (newTable) {
            var src = this._table,
                newCapacity = newTable.length;
            for( var j = 0; j < src.length; j++ ) {
                var entry = src[j];
                if( entry !== null ) {
                    src[j] = null;
                    do {
                        var next = entry._next,
                            i = this.self( arguments )._indexFor( entry._hash, newCapacity );
                        entry._next = newTable[i];
                        newTable[i] = entry;
                        entry = next;
                    } while( entry !== null );

        putAll: function (map) {
            var numKeyToBeAdded = map.size();
            if( numKeyToBeAdded === 0 ) {

            if( numKeyToBeAdded > this._threshold ) {
                var targetCapacity = (numKeyToBeAdded / this._loadFactor + 1) | 0;
                if( targetCapacity > this.self( arguments ).MAXIMUM_CAPACITY ) {
                    targetCapacity = this.self( arguments ).MAXIMUM_CAPACITY;

                var newCapacity = this._table.length;
                while( newCapacity < targetCapacity ) {
                    newCapacity <<= 1;
                if( newCapacity > this._table.length ) {
                    this._resize( newCapacity );

            var iterator = map.entrySet().iterator();
            while( iterator.hasNext() ) {
                var entry =;
                this.put( entry.getKey(), entry.getValue() );

        remove: function (key) {
            var entry = this._removeEntryForKey( key );
            return entry === null ? null : entry._value;

        _removeEntryForKey: function (key) {
            var hash = (key === null) ? 0 : this.self( arguments )._hash( key.hashCode() ),
                i = this.self( arguments )._indexFor( hash, this._table.length ),
                prev = this._table[i],
                entry = prev;

            while( entry !== null ) {
                var next = entry._next,
                    /** @type jsava.lang.Object */
                if( entry._hash === hash
                    && ( (k = entry._key) === key || ( key !== null && key.equals( k ) ) ) ) {
                    if( prev === entry ) {
                        this._table[i] = next;
                    } else {
                        prev._next = next;
                    entry._recordRemoval( this );
                    return entry;
                prev = entry;
                entry = next;

            return entry;

        _removeMapping: function (obj) {
            if( obj === null || !qx.Class.implementsInterface( obj, jsava.util.Map.Entry ) ) {
                return null;

            /** @implements jsava.util.Map.Entry */
            var entry = obj,
                key = entry.getKey(),
                hash = (key === null) ? 0 : this.self( arguments )._hash( key.hashCode() ),
                i = this.self( arguments )._indexFor( hash, this._table.length ),
                prev = this._table[i],
                e = prev;

            while( e !== null ) {
                var next = e._next;
                if( e._hash === hash && e.equals( entry ) ) {
                    if( prev === e ) {
                        this._table[i] = next;
                    } else {
                        prev._next = next;
                    e._recordRemoval( this );
                    return e;
                prev = e;
                e = next;

            return e;

        clear: function () {
            var table = this._table;
            for( var i = 0; i < table.length; i++ ) {
                table[i] = null;
            this._size = 0;

        containsValue: function (value) {
            if( value === null ) {
                return this.__containsNullValue();

            var table = this._table;
            for( var i = 0; i < table.length; i++ ) {
                for( var entry = table[i]; entry !== null; entry = entry._next ) {
                    if( value.equals( entry._value ) ) {
                        return true;

            return false;

        __containsNullValue: function () {
            var table = this._table;
            for( var i = 0; i < table.length; i++ ) {
                for( var entry = table[i]; entry !== null; entry = entry._next ) {
                    if( entry._value === null ) {
                        return true;

            return false;

        clone: function () {
            /** @type jsava.util.HashMap */
            var result = null;
            try {
                result = this.base( arguments );
            } catch( e ) {
                if( !qx.Class.isSubClassOf( e.constructor, jsava.lang.CloneNotSupportedException ) ) {
                    throw e;

            result._table = jsava.JsavaUtils.emptyArrayOfGivenSize( this._table.length, null );
            result.__entrySet = null;
            result._modCount = 0;
            result._size = 0;
            result.__putAllForCreate( this );

            return result;

        _addEntry: function (hash, key, value, bucketIndex) {
            var entry = this._table[bucketIndex];
            this._table[bucketIndex] = new (this.self( arguments ).Entry)( hash, key, value, entry );
            if( this._size++ >= this._threshold ) {
                this._resize( 2 * this._table.length );

        _createEntry: function (hash, key, value, bucketIndex) {
            var entry = this._table[bucketIndex];
            this._table[bucketIndex] = new (this.self( arguments ).Entry)( hash, key, value, entry );

        keySet: function () {
            var keySet = this._keySet;
            return keySet !== null ? keySet : ( this._keySet = new this.KeySet( this ) );

        values: function () {
            var values = this._values;
            return values !== null ? values : ( this._values = new this.Values( this ) );

        entrySet: function () {
            return this.__entrySet0();

        __entrySet0: function () {
            var entrySet = this.__entrySet;
            return entrySet !== null ? entrySet : ( this.__entrySet = new this.EntrySet( this ) );

        /** @private */
        HashIterator: qx.Class.define( 'jsava.util.HashMap.HashIterator', {
            extend: jsava.lang.Object,
            implement: [jsava.util.Iterator],

            type: 'abstract',

            /** @protected */
            construct: function (thisHashMap) {
                this.__thisHashMap = thisHashMap;
                this._expectedModCount = this.__thisHashMap._modCount;
                if( this.__thisHashMap._size > 0 ) {
                    var table = this.__thisHashMap._table;
                    while( this._index < table.length && ( this._next = table[this._index++] ) === null ) {
                        // do nothing

            members: {
                __thisHashMap: null,

                /** @type jsava.util.HashMap.Entry */
                _next: null,
                /** @type Number */
                _expectedModCount: 0,
                /** @type Number */
                _index: 0,
                /** @type jsava.util.HashMap.Entry */
                _current: null,

                hasNext: function () {
                    return this._next !== null;

                _nextEntry: function () {
                    if( this.__thisHashMap._modCount !== this._expectedModCount ) {
                        throw new jsava.lang.ConcurrentModificationException();

                    var entry = this._next;
                    if( entry === null ) {
                        throw new jsava.lang.NoSuchElementException();

                    if( (this._next = entry._next) === null ) {
                        var table = this.__thisHashMap._table;
                        while( this._index < table.length && ( this._next = table[this._index++] ) === null ) {
                            // do nothing

                    this._current = entry;
                    return entry;

                remove: function () {
                    if( this._current === null ) {
                        throw new jsava.lang.IllegalStateException();

                    if( this.__thisHashMap._modCount !== this._expectedModCount ) {
                        throw new jsava.lang.ConcurrentModificationException();

                    var key = this._current._key;
                    this._current = null;
                    this.__thisHashMap._removeEntryForKey( key );
                    this._expectedModCount = this.__thisHashMap._modCount;
        } ),

        _newKeyIterator: function () {
            return new this.KeyIterator( this );

        _newValueIterator: function () {
            return new this.ValueIterator( this );

        _newEntryIterator: function () {
            return new this.EntryIterator( this );

        /** @private */
        ValueIterator: qx.Class.define( 'jsava.util.HashMap.ValueIterator', {
            extend: jsava.util.HashMap.HashIterator,

            construct: function (thisHashMap) {
                this.base( arguments, thisHashMap );

            members: {
                next: function () {
                    return this._nextEntry()._value;
        } ),

        /** @private */
        KeyIterator: qx.Class.define( 'jsava.util.HashMap.KeyIterator', {
            extend: jsava.util.HashMap.HashIterator,

            construct: function (thisHashMap) {
                this.base( arguments, thisHashMap );

            members: {
                next: function () {
                    return this._nextEntry().getKey();
        } ),

        /** @private */
        EntryIterator: qx.Class.define( 'jsava.util.HashMap.EntryIterator', {
            extend: jsava.util.HashMap.HashIterator,

            construct: function (thisHashMap) {
                this.base( arguments, thisHashMap );

            members: {
                next: function () {
                    return this._nextEntry();
        } ),

        /** @private */
        KeySet: qx.Class.define( 'jsava.util.HashMap.KeySet', {
            extend: jsava.util.AbstractSet,

            construct: function (thisHashMap) {
                this.base( arguments );
                this.__thisHashMap = thisHashMap;

            members: {
                __thisHashMap: null,

                iterator: function () {
                    return this.__thisHashMap._newKeyIterator();

                size: function () {
                    return this.__thisHashMap._size;

                contains: function (obj) {
                    return this.__thisHashMap.containsKey( obj );

                remove: function (obj) {
                    return this.__thisHashMap._removeEntryForKey( obj ) !== null;

                clear: function () {
        } ),

        /** @private */
        Values: qx.Class.define( 'jsava.util.HashMap.Values', {
            extend: jsava.util.AbstractCollection,

            construct: function (thisHashMap) {
                this.base( arguments );
                this.__thisHashMap = thisHashMap;

            members: {
                __thisHashMap: null,

                iterator: function () {
                    return this.__thisHashMap._newValueIterator();

                size: function () {
                    return this.__thisHashMap._size;

                contains: function (obj) {
                    return this.__thisHashMap.containsValue( obj );

                clear: function () {
        } ),

        /** @private */
        EntrySet: qx.Class.define( 'jsava.util.HashMap.EntrySet', {
            extend: jsava.util.AbstractSet,

            construct: function (thisHashMap) {
                this.base( arguments );
                this.__thisHashMap = thisHashMap;

            members: {
                __thisHashMap: null,

                iterator: function () {
                    return this.__thisHashMap._newEntryIterator();

                size: function () {
                    return this.__thisHashMap._size;

                contains: function (obj) {
                    if( obj === null || !qx.Class.implementsInterface( obj, jsava.util.Map.Entry ) ) {
                        return false;

                    /** @implements jsava.util.Map.Entry */
                    var entry = obj,
                        candidate = this.__thisHashMap._getEntry( entry.getKey() );
                    return candidate !== null && candidate.equals( entry );

                remove: function (obj) {
                    return this.__thisHashMap._removeMapping( obj ) !== null;

                clear: function () {
        } )
} );

What's the difference between `raw_input()` and `input()` in Python 3?

In Python 3, raw_input() doesn't exist which was already mentioned by Sven.

In Python 2, the input() function evaluates your input.


name = input("what is your name ?")
what is your name ?harsha

Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    name = input("what is your name ?")
  File "<string>", line 1, in <module>
NameError: name 'harsha' is not defined

In the example above, Python 2.x is trying to evaluate harsha as a variable rather than a string. To avoid that, we can use double quotes around our input like "harsha":

>>> name = input("what is your name?")
what is your name?"harsha"
>>> print(name)


The raw_input()` function doesn't evaluate, it will just read whatever you enter.


name = raw_input("what is your name ?")
what is your name ?harsha
>>> name


 name = eval(raw_input("what is your name?"))
what is your name?harsha

Traceback (most recent call last):
  File "<pyshell#11>", line 1, in <module>
    name = eval(raw_input("what is your name?"))
  File "<string>", line 1, in <module>
NameError: name 'harsha' is not defined

In example above, I was just trying to evaluate the user input with the eval function.

Load HTML page dynamically into div with jQuery

There's a jQuery plugin out there called pjax it states: "It's ajax with real permalinks, page titles, and a working back button that fully degrades."

The plugin uses HTML5 pushState and AJAX to dynamically change pages without a full load. If pushState isn't supported, PJAX performs a full page load, ensuring backwards compatibility.

What pjax does is that it listens on specified page elements such as <a>. Then when the <a href=""></a> element is invoked, the target page is fetched with either the X-PJAX header, or a specified fragment.


<script type="text/javascript">
  $(document).pjax('a', '#pjax-container');

Putting this code in the page header will listen on all links in the document and set the element that you are both fetching from the new page and replacing on the current page.

(meaning you want to replace #pjax-container on the current page with #pjax-container from the remote page)

When <a> is invoked, it will fetch the link with the request header X-PJAX and will look for the contents of #pjax-container in the result. If the result is #pjax-container, the container on the current page will be replaced with the new result.

<!DOCTYPE html>
  <script type="text/javascript" src="jquery.min.js"></script>
  <script type="text/javascript" src="jquery.pjax.js"></script> 
  <script type="text/javascript">
    $(document).pjax('a', '#pjax-container');
  <h1>My Site</h1>
  <div class="container" id="pjax-container">
    Go to <a href="/page2">next page</a>.

If #pjax-container is not the first element found in the response, PJAX will not recognize the content and perform a full page load on the requested link. To fix this, the server backend code would need to be set to only send #pjax-container.

Example server side code of page2:

//if header X-PJAX == true in request headers, send
<div class="container" id="pjax-container">
  Go to <a href="/page1">next page</a>.
//else send full page

If you can't change server-side code, then the fragment option is an alternative.

$(document).pjax('a', '#pjax-container', { 
  fragment: '#pjax-container' 

Note that fragment is an older pjax option and appears to fetch the child element of requested element.

ggplot2 line chart gives "geom_path: Each group consist of only one observation. Do you need to adjust the group aesthetic?"

You get this error because one of your variables is actually a factor variable . Execute


to check this. Then do this double variable change to keep the year numbers instead of transforming into "1,2,3,4" level numbers:

df$year <- as.numeric(as.character(df$year))

EDIT: it appears that your data.frame has a variable of class "array" which might cause the pb. Try then:

df <- data.frame(apply(df, 2, unclass))

and plot again?

undefined offset PHP error

If preg_match did not find a match, $matches is an empty array. So you should check if preg_match found an match before accessing $matches[0], for example:

function get_match($regex,$content)
    if (preg_match($regex,$content,$matches)) {
        return $matches[0];
    } else {
        return null;

Easiest way to pass an AngularJS scope variable from directive to controller?

Edited on 2014/8/25: Here was where I forked it.

Thanks @anvarik.

Here is the JSFiddle. I forgot where I forked this. But this is a good example showing you the difference between = and @

<div ng-controller="MyCtrl">
    <h2>Parent Scope</h2>
    <input ng-model="foo"> <i>// Update to see how parent scope interacts with component scope</i>    
    <!-- attribute-foo binds to a DOM attribute which is always
    a string. That is why we are wrapping it in curly braces so
    that it can be interpolated. -->
    <my-component attribute-foo="{{foo}}" binding-foo="foo"
        isolated-expression-foo="updateFoo(newFoo)" >
            <strong>get:</strong> {{isolatedAttributeFoo}}
            <strong>set:</strong> <input ng-model="isolatedAttributeFoo">
            <i>// This does not update the parent scope.</i>
            <strong>get:</strong> {{isolatedBindingFoo}}
            <strong>set:</strong> <input ng-model="isolatedBindingFoo">
            <i>// This does update the parent scope.</i>
            <input ng-model="isolatedFoo">
            <button class="btn" ng-click="isolatedExpressionFoo({newFoo:isolatedFoo})">Submit</button>
            <i>// And this calls a function on the parent scope.</i>
var myModule = angular.module('myModule', [])
    .directive('myComponent', function () {
        return {
                /* NOTE: Normally I would set my attributes and bindings
                to be the same name but I wanted to delineate between
                parent and isolated scope. */                
    .controller('MyCtrl', ['$scope', function ($scope) {
        $ = 'Hello!';
        $scope.updateFoo = function (newFoo) {
            $ = newFoo;

Error: stray '\240' in program

As mentioned in a previous reply, this generally comes when compiling copy pasted code. If you have a bash shell, the following command generally works:

iconv -f utf-8 -t ascii//translit input.c > output.c

What's a good, free serial port monitor for reverse-engineering?

I've been down this road and eventually opted for a hardware data scope that does non-instrusive in-line monitoring. The software solutions that I tried didn't work for me. If you had a spare PC you could probably build one, albeit rather bulky. This software data scope may work, as might this, but I haven't tried either.

Read binary file as string in Ruby

on os x these are the same for me... could this maybe be extra "\r" in windows?

in any case you may be better of with:

contents ="e.tgz")
newFile ="ee.tgz", "w")

Uploading Images to Server android

Try this method for uploading Image file from camera

package com.example.imageupload;


import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.message.BasicHeader;

public class MultipartEntity implements HttpEntity {

private String boundary = null;

ByteArrayOutputStream out = new ByteArrayOutputStream();
boolean isSetLast = false;
boolean isSetFirst = false;

public MultipartEntity() {
    this.boundary = System.currentTimeMillis() + "";

public void writeFirstBoundaryIfNeeds() {
    if (!isSetFirst) {
        try {
            out.write(("--" + boundary + "\r\n").getBytes());
        } catch (final IOException e) {

    isSetFirst = true;

public void writeLastBoundaryIfNeeds() {
    if (isSetLast) {
    try {
        out.write(("\r\n--" + boundary + "--\r\n").getBytes());
    } catch (final IOException e) {

    isSetLast = true;

public void addPart(final String key, final String value) {
    try {
        out.write(("Content-Disposition: form-data; name=\"" + key + "\"\r\n")
        out.write("Content-Type: text/plain; charset=UTF-8\r\n".getBytes());
        out.write("Content-Transfer-Encoding: 8bit\r\n\r\n".getBytes());
        out.write(("\r\n--" + boundary + "\r\n").getBytes());
    } catch (final IOException e) {


public void addPart(final String key, final String fileName,
        final InputStream fin) {
    addPart(key, fileName, fin, "application/octet-stream");

public void addPart(final String key, final String fileName,
        final InputStream fin, String type) {
    try {
        type = "Content-Type: " + type + "\r\n";
        out.write(("Content-Disposition: form-data; name=\"" + key
                + "\"; filename=\"" + fileName + "\"\r\n").getBytes());
        out.write("Content-Transfer-Encoding: binary\r\n\r\n".getBytes());

        final byte[] tmp = new byte[4096];
        int l = 0;
        while ((l = != -1) {
            out.write(tmp, 0, l);
    } catch (final IOException e) {

    } finally {
        try {
        } catch (final IOException e) {


public void addPart(final String key, final File value) {
    try {
        addPart(key, value.getName(), new FileInputStream(value));
    } catch (final FileNotFoundException e) {


public long getContentLength() {
    return out.toByteArray().length;

public Header getContentType() {
    return new BasicHeader("Content-Type", "multipart/form-data; boundary="
            + boundary);

public boolean isChunked() {
    return false;

public boolean isRepeatable() {
    return false;

public boolean isStreaming() {
    return false;

public void writeTo(final OutputStream outstream) throws IOException {

public Header getContentEncoding() {
    return null;

public void consumeContent() throws IOException,
        UnsupportedOperationException {
    if (isStreaming()) {
        throw new UnsupportedOperationException(
                "Streaming entity does not implement #consumeContent()");

public InputStream getContent() throws IOException,
        UnsupportedOperationException {
    return new ByteArrayInputStream(out.toByteArray());


Use of class for uploading

private void doFileUpload(File file_path) {

    Log.d("Uri", "Do file path" + file_path);

    try {

        HttpClient client = new DefaultHttpClient();
        //use your server path of php file
        HttpPost post = new HttpPost(ServerUploadPath);

        Log.d("ServerPath", "Path" + ServerUploadPath);

        FileBody bin1 = new FileBody(file_path);
        Log.d("Enter", "Filebody complete " + bin1);

        MultipartEntity reqEntity = new MultipartEntity();
        reqEntity.addPart("uploaded_file", bin1);
        reqEntity.addPart("email", new StringBody(useremail));

        Log.d("Enter", "Image send complete");

        HttpResponse response = client.execute(post);
        resEntity = response.getEntity();
        Log.d("Enter", "Get Response");
        try {

            final String response_str = EntityUtils.toString(resEntity);
            if (resEntity != null) {
                Log.i("RESPONSE", response_str);
                JSONObject jobj = new JSONObject(response_str);
                result = jobj.getString("ResponseCode");
                Log.e("Result", "...." + result);

        } catch (Exception ex) {
            Log.e("Debug", "error: " + ex.getMessage(), ex);
    } catch (Exception e) {
        Log.e("Upload Exception", "");

Service for uploading

$image_name = $_FILES["uploaded_file"]["name"]; 
$tmp_arr = explode(".",$image_name);
$img_extn = end($tmp_arr);
$new_image_name = 'image_'. uniqid() .'.'.$img_extn;    

if (file_exists("Images/".$new_image_name))
           $msg=$new_image_name . " already exists."
           header('Content-type: application/json');        
           echo json_encode(array("ResponseCode"=>"2","ResponseMsg"=>$msg));        
move_uploaded_file($_FILES["uploaded_file"]["tmp_name"],"Images/". $new_image_name);
                   $flag = 1;

if($flag == 1){                    
            require 'db.php';   
            $static_url =$new_image_name;
            $conn=mysql_connect($db_host,$db_username,$db_password) or die("unable to connect localhost".mysql_error());
            $db=mysql_select_db($db_database,$conn) or die("unable to select message_app"); 
            $email = "";
                     $email = $_REQUEST['email'];

    $sql ="insert into alert(images) values('$static_url')";


    echo json_encode(array("ResponseCode"=>"1","ResponseMsg"=> "Insert data successfully.","Result"=>"True","ImageName"=>$static_url,"email"=>$email));
       } else

         echo json_encode(array("ResponseCode"=>"2","ResponseMsg"=> "Could not insert data.","Result"=>"False","email"=>$email));
    echo json_encode(array("ResponseCode"=>"2","ResponseMsg"=> "Erroe While Inserting Image.","Result"=>"False"));

How to get the wsdl file from a webservice's URL

To download the wsdl from a url using Developer Command Prompt for Visual Studio, run it in Administrator mode and enter the following command:

 svcutil /t:metadata http://[your-service-url-here]

You can now consume the downloaded wsdl in your project as you see fit.

C++ alignment when printing cout <<

IO manipulators are what you need. setw, in particular. Here's an example from the reference page:

// setw example
#include <iostream>
#include <iomanip>
using namespace std;

int main () {
  cout << setw (10);
  cout << 77 << endl;
  return 0;

Justifying the field to the left and right is done with the left and right manipulators.

Also take a look at setfill. Here's a more complete tutorial on formatting C++ output with io manipulators.

Most efficient T-SQL way to pad a varchar on the left to a certain length?

This is simply an inefficient use of SQL, no matter how you do it.

perhaps something like

right('XXXXXXXXXXXX'+ rtrim(@str), @n)

where X is your padding character and @n is the number of characters in the resulting string (assuming you need the padding because you are dealing with a fixed length).

But as I said you should really avoid doing this in your database.

Escape curly brace '{' in String.Format

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

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

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

HashMap with multiple values under the same key

No, not just as a HashMap. You'd basically need a HashMap from a key to a collection of values.

If you're happy to use external libraries, Guava has exactly this concept in Multimap with implementations such as ArrayListMultimap and HashMultimap.

How to change font of UIButton with Swift

You don't need to force unwrap the titleLabel to set it.

myButton.titleLabel?.font = UIFont(name: YourfontName, size: 20)

Since you're not using the titleLabel here, you can just optionally use it and if it's nil it will just be a no-op.

I'll also add as other people are saying, the font property is deprecated, and make sure to use setTitle:forControlState: when setting the title text.

How to style a select tag's option element?

I have a workaround using jquery... although we cannot style a particular option, we can style the select itself - and use javascript to change the class of the select based on what is selected. It works sufficiently for simple cases.

$('select.potentially_red').on('change', function() {_x000D_
 if ($(this).val()=='red') {_x000D_
 } else {_x000D_
$('select.potentially_red').each( function() {_x000D_
 if ($(this).val()=='red') {_x000D_
 } else {_x000D_
.option_red {_x000D_
    background-color: #cc0000; _x000D_
    font-weight: bold; _x000D_
    font-size: 12px; _x000D_
    color: white;_x000D_
     <script src=""></script>_x000D_
<!-- The js will affect all selects which have the class 'potentially_red' -->_x000D_
<select name="color" class="potentially_red">_x000D_
    <option value="red">Red</option>_x000D_
    <option value="white">White</option>_x000D_
    <option value="blue">Blue</option>_x000D_
    <option value="green">Green</option>_x000D_

Note that the js is in two parts, the each part for initializing everything on the page correctly, the .on('change', ... part for responding to change. I was unable to mangle the js into a function to DRY it up, it breaks it for some reason

1114 (HY000): The table is full

I too faced this error while importing an 8GB sql database file. Checked my mysql installation drive. There was no space left in the drive. So got some space by removing unwanted items and re-ran my database import command. This time it was successful.

How to get "wc -l" to print just the number of lines without file name?

cat file.txt | wc -l

According to the man page (for the BSD version, I don't have a GNU version to check):

If no files are specified, the standard input is used and no file name is displayed. The prompt will accept input until receiving EOF, or [^D] in most environments.

Using grep to search for a string that has a dot in it

You need to escape the . as "0\.49".

A . is a regex meta-character to match any character(except newline). To match a literal period, you need to escape it.

How to find length of digits in an integer?

Assuming you are asking for the largest number you can store in an integer, the value is implementation dependent. I suggest that you don't think in that way when using python. In any case, quite a large value can be stored in a python 'integer'. Remember, Python uses duck typing!

Edit: I gave my answer before the clarification that the asker wanted the number of digits. For that, I agree with the method suggested by the accepted answer. Nothing more to add!

Resolving PKIX path building failed Error?

I was having this problem with Android Studio when I'm behind a proxy. I was using Crashlytics that tries to upload the mapping file during a build.

I added the missing proxy certificate to the truststore located at /Users/[username]/Documents/Android

with the following command: keytool -import -trustcacerts -keystore cacerts -storepass [password] -noprompt -alias [alias] -file [my_certificate_location]

for example with the default truststore password keytool -import -trustcacerts -keystore cacerts -storepass changeit -noprompt -alias myproxycert -file /Users/myname/Downloads/MyProxy.crt

2D array values C++

Like this:

int main()
    int arr[2][5] =

This should be covered by your C++ textbook: which one are you using?

Anyway, better, consider using std::vector or some ready-made matrix class e.g. from Boost.

How to get row from R data.frame


where r is the row you're interested in. Try this, for example:

#Add your data
x <- structure(list(A = c(5,    3.5, 3.25, 4.25,  1.5 ), 
                    B = c(4.25, 4,   4,    4.5,   4.5 ),
                    C = c(4.5,  2.5, 4,    2.25,  3   )
               .Names    = c("A", "B", "C"),
               class     = "data.frame",
               row.names = c(NA, -5L)

#The vector your result should match
y<-c(A=5, B=4.25, C=4.5)

#Test that the items in the row match the vector you wanted

This page (from this useful site) has good information on indexing like this.

How to reset form body in bootstrap modal box?

The below solution solved my problem and also kept the default values

$('body').on('', '.modal', function () { 
  $(this).find('input[type="text"],input[type="email"],textarea,select').each(function() { 
    if (this.defaultValue != '' || this.value != this.defaultValue) {
         this.value = this.defaultValue; 
    } else { this.value = ''; }

SQL to Query text in access with an apostrophe in it

When you include a string literal in a query, you can enclose the string in either single or double quotes; Access' database engine will accept either. So double quotes will avoid the problem with a string which contains a single quote.

SELECT * FROM tblStudents WHERE [name] Like "Daniel O'Neal";

If you want to keep the single quotes around your string, you can double up the single quote within it, as mentioned in other answers.

SELECT * FROM tblStudents WHERE [name] Like 'Daniel O''Neal';

Notice the square brackets surrounding name. I used the brackets to lessen the chance of confusing the database engine because name is a reserved word.

It's not clear why you're using the Like comparison in your query. Based on what you've shown, this should work instead.

SELECT * FROM tblStudents WHERE [name] = "Daniel O'Neal";

Monad in plain English? (For the OOP programmer with no FP background)

I would say the closest OO analogy to monads is the "command pattern".

In the command pattern you wrap an ordinary statement or expression in a command object. The command object expose an execute method which executes the wrapped statement. So statement are turned into first class objects which can passed around and executed at will. Commands can be composed so you can create a program-object by chaining and nesting command-objects.

The commands are executed by a separate object, the invoker. The benefit of using the command pattern (rather than just execute a series of ordinary statements) is that different invokers can apply different logic to how the commands should be executed.

The command pattern could be used to add (or remove) language features which is not supported by the host language. For example, in a hypothetical OO language without exceptions, you could add exception semantics by exposing "try" and "throw" methods to the commands. When a command calls throw, the invoker backtracks through the list (or tree) of commands until the last "try" call. Conversely, you could remove exception semantic from a language (if you believe exceptions are bad) by catching all exceptions thrown by each individual commands, and turning them into error codes which are then passed to the next command.

Even more fancy execution semantics like transactions, non-deterministic execution or continuations can be implemented like this in a language which doesn't support it natively. It is a pretty powerful pattern if you think about it.

Now in reality the command-patterns is not used as a general language feature like this. The overhead of turning each statement into a separate class would lead to an unbearable amount of boilerplate code. But in principle it can be used to solve the same problems as monads are used to solve in fp.

Maven build failed: "Unable to locate the Javac Compiler in: jre or jdk issue"

File eclipse.ini needs the vm argument to point to your JDK location.

Edit the eclipse.ini file to point to your JDK home, something as follows -

C:\Program Files\Java\jdk1.6.0_06

This ensures that Eclipse would be running off the JDK and not any default JRE on your machine.

Can I perform a DNS lookup (hostname to IP address) using client-side Javascript?

I am aware this is an old question but my solution may assist others.

I find that the JSON(P) services which make this easy do not last forever but the following JavaScript works well for me at the time of writing.

<script type="text/javascript">function z (x){ document.getElementById('y').innerHTML=x.query }</script>
<script type='text/javascript' src=''></script>

The above writes my server's IP on the page it is located but the script can be modified to find any IP by changing '' to another domain name. This can be seen in action on my page at:

JQuery Validate Dropdown list

This was my solution:

I added required to the select tag:

                <div class="col-lg-10">
                <select class="form-control" name="HoursEntry" id="HoursEntry" required>
                    <option value="">Select.....</option>
                    <option value="0.25">0.25</option>
                    <option value="0.5">0.50</option>
                    <option value="1">1.00</option>
                    <option value="1.25">1.25</option>
                    <option value="1.5">1.50</option>
                    <option value="2">2.00</option>
                    <option value="2.25">2.25</option>
                    <option value="2.5">2.50</option>
                    <option value="3">3.00</option>
                    <option value="3.25">3.25</option>
                    <option value="3.5">3.50</option>
                    <option value="4">4.00</option>
                    <option value="4.25">4.25</option>
                    <option value="4.5">4.50</option>
                    <option value="5">5.00</option>
                    <option value="5.25">5.25</option>
                    <option value="5.5">5.50</option>
                    <option value="6">6.00</option>
                    <option value="6.25">6.25</option>
                    <option value="6.5">6.50</option>
                    <option value="7">7.00</option>
                    <option value="7.25">7.25</option>
                    <option value="7.5">7.50</option>
                    <option value="8">8.00</option>

Python nonlocal statement

In short, it lets you assign values to a variable in an outer (but non-global) scope. See PEP 3104 for all the gory details.

Aborting a stash pop in Git

I solved this in a somewhat different way. Here's what happened.

First, I popped on the wrong branch and got conflicts. The stash remained intact but the index was in conflict resolution, blocking many commands.

A simple git reset HEAD aborted the conflict resolution and left the uncommitted (and UNWANTED) changes.

Several git co <filename> reverted the index to the initial state. Finally, I switched branch with git co <branch-name> and run a new git stash pop, which resolved without conflicts.

How to measure elapsed time

Even better!

long tStart = System.nanoTime();
long tEnd = System.nanoTime();
long tRes = tEnd - tStart; // time in nanoseconds

Read the documentation about nanoTime()!

JS: Uncaught TypeError: object is not a function (onclick)

I was able to figure it out by following the answer in this thread:

Basically, I renamed all values, function names, and element names to different values so they wouldn't conflict - and it worked!

Where are logs located?

  • Ensure debug mode is on - either add APP_DEBUG=true to .env file or set an environment variable

  • Log files are in storage/logs folder. laravel.log is the default filename. If there is a permission issue with the log folder, Laravel just halts. So if your endpoint generally works - permissions are not an issue.

  • In case your calls don't even reach Laravel or aren't caused by code issues - check web server's log files (check your Apache/nginx config files to see the paths).

  • If you use PHP-FPM, check its log files as well (you can see the path to log file in PHP-FPM pool config).

Multi-line string with extra space (preserved indentation)

it will work if you put it as below:

AA='first line
\nsecond line 
\nthird line'
echo $AA
first line
second line
third line

Difference between ApiController and Controller in ASP.NET MVC

Use Controller to render your normal views. ApiController action only return data that is serialized and sent to the client.

here is the link


Note If you have worked with ASP.NET MVC, then you are already familiar with controllers. They work similarly in Web API, but controllers in Web API derive from the ApiController class instead of Controller class. The first major difference you will notice is that actions on Web API controllers do not return views, they return data.

ApiControllers are specialized in returning data. For example, they take care of transparently serializing the data into the format requested by the client. Also, they follow a different routing scheme by default (as in: mapping URLs to actions), providing a REST-ful API by convention.

You could probably do anything using a Controller instead of an ApiController with the some(?) manual coding. In the end, both controllers build upon the ASP.NET foundation. But having a REST-ful API is such a common requirement today that WebAPI was created to simplify the implementation of a such an API.

It's fairly simple to decide between the two: if you're writing an HTML based web/internet/intranet application - maybe with the occasional AJAX call returning json here and there - stick with MVC/Controller. If you want to provide a data driven/REST-ful interface to a system, go with WebAPI. You can combine both, of course, having an ApiController cater AJAX calls from an MVC page.

To give a real world example: I'm currently working with an ERP system that provides a REST-ful API to its entities. For this API, WebAPI would be a good candidate. At the same time, the ERP system provides a highly AJAX-ified web application that you can use to create queries for the REST-ful API. The web application itself could be implemented as an MVC application, making use of the WebAPI to fetch meta-data etc.

How to refresh datagrid in WPF

Try mydatagrid.Items.Refresh()

Error:(23, 17) Failed to resolve: junit:junit:4.12

Just remove the "testCompile 'junit:junit:4.12'" from build.gradle file:

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'//remove this line and sync again... worked for me

androidTestCompile('', {
    exclude group: '', module: 'support-annotations'}) //if available, also delete these two lines

compile ''

worked for me and I am Happy! :)

Remember that this is not the actual answer of this question. I mentioned this because it works when you remove above lines.

How to do a Jquery Callback after form submit?

I just did this -

 $("#myform").bind('ajax:complete', function() {

         // tasks to do 


And things worked perfectly .

See this api documentation for more specific details.

Saving Excel workbook to constant path with filename from two fields


Sub save()
ActiveWorkbook.SaveAS Filename:="C:\-docs\cmat\Desktop\New folder\" & Range("C5").Text & chr(32) & Range("C8").Text &".xls", FileFormat:= _
  xlNormal, Password:="", WriteResPassword:="", ReadOnlyRecommended:=False _
 , CreateBackup:=False
End Sub

If you want to save the workbook with the macros use the below code

Sub save()
ActiveWorkbook.SaveAs Filename:="C:\Users\" & Environ$("username") & _
    "\Desktop\" & Range("C5").Text & Chr(32) & Range("C8").Text & ".xlsm", FileFormat:= _
    xlOpenXMLWorkbookMacroEnabled, Password:=vbNullString, WriteResPassword:=vbNullString, _
    ReadOnlyRecommended:=False, CreateBackup:=False
End Sub

if you want to save workbook with no macros and no pop-up use this

Sub save()
    Application.DisplayAlerts = False
    ActiveWorkbook.SaveAs Filename:="C:\Users\" & Environ$("username") & _
    "\Desktop\" & Range("C5").Text & Chr(32) & Range("C8").Text & ".xls", _
    FileFormat:=xlOpenXMLWorkbook, CreateBackup:=False
    Application.DisplayAlerts = True
End Sub

OpenSSL: unable to verify the first certificate for Experian URL

I came across the same issue installing my signed certificate on an Amazon Elastic Load Balancer instance.

All seemed find via a browser (Chrome) but accessing the site via my java client produced the exception

What I had not done was provide a "certificate chain" file when installing my certificate on my ELB instance (see

We were only sent our signed public key from the signing authority so I had to create my own certificate chain file. Using my browser's certificate viewer panel I exported each certificate in the signing chain. (The order of the certificate chain in important, see

Python 3 TypeError: must be str, not bytes with sys.stdout.write()

Python 3 handles strings a bit different. Originally there was just one type for strings: str. When unicode gained traction in the '90s the new unicode type was added to handle Unicode without breaking pre-existing code1. This is effectively the same as str but with multibyte support.

In Python 3 there are two different types:

  • The bytes type. This is just a sequence of bytes, Python doesn't know anything about how to interpret this as characters.
  • The str type. This is also a sequence of bytes, but Python knows how to interpret those bytes as characters.
  • The separate unicode type was dropped. str now supports unicode.

In Python 2 implicitly assuming an encoding could cause a lot of problems; you could end up using the wrong encoding, or the data may not have an encoding at all (e.g. it’s a PNG image).
Explicitly telling Python which encoding to use (or explicitly telling it to guess) is often a lot better and much more in line with the "Python philosophy" of "explicit is better than implicit".

This change is incompatible with Python 2 as many return values have changed, leading to subtle problems like this one; it's probably the main reason why Python 3 adoption has been so slow. Since Python doesn't have static typing2 it's impossible to change this automatically with a script (such as the bundled 2to3).

  • You can convert str to bytes with bytes('h€llo', 'utf-8'); this should produce b'H\xe2\x82\xacllo'. Note how one character was converted to three bytes.
  • You can convert bytes to str with b'H\xe2\x82\xacllo'.decode('utf-8').

Of course, UTF-8 may not be the correct character set in your case, so be sure to use the correct one.

In your specific piece of code, nextline is of type bytes, not str, reading stdout and stdin from subprocess changed in Python 3 from str to bytes. This is because Python can't be sure which encoding this uses. It probably uses the same as sys.stdin.encoding (the encoding of your system), but it can't be sure.

You need to replace:




or maybe:


You will also need to modify if nextline == '' to if nextline == b'' since:

>>> '' == b''

Also see the Python 3 ChangeLog, PEP 358, and PEP 3112.

1 There are some neat tricks you can do with ASCII that you can't do with multibyte character sets; the most famous example is the "xor with space to switch case" (e.g. chr(ord('a') ^ ord(' ')) == 'A') and "set 6th bit to make a control character" (e.g. ord('\t') + ord('@') == ord('I')). ASCII was designed in a time when manipulating individual bits was an operation with a non-negligible performance impact.

2 Yes, you can use function annotations, but it's a comparatively new feature and little used.

How to write some data to excel file(.xlsx)

You can use ClosedXML for this.

Store your table in a DataTable and you can export the table to excel by this simple snippet:

XLWorkbook workbook = new XLWorkbook();
DataTable table = GetYourTable();
workbook.Worksheets.Add(table );

You can read the documentation of ClosedXML to learn more. Hope this helps!

Rotate and translate

I can't comment so here goes. About @David Storey answer.

Be careful on the "order of execution" in CSS3 chains! The order is right to left, not left to right.

transformation: translate(0,10%) rotate(25deg);

The rotate operation is done first, then the translate.

See: CSS3 transform order matters: rightmost operation first

What is the difference between null=True and blank=True in Django?

This is how the ORM maps blank & null fields for Django 1.8

class Test(models.Model):
    charNull        = models.CharField(max_length=10, null=True)
    charBlank       = models.CharField(max_length=10, blank=True)
    charNullBlank   = models.CharField(max_length=10, null=True, blank=True)

    intNull         = models.IntegerField(null=True)
    intBlank        = models.IntegerField(blank=True)
    intNullBlank    = models.IntegerField(null=True, blank=True)

    dateNull        = models.DateTimeField(null=True)
    dateBlank       = models.DateTimeField(blank=True)
    dateNullBlank   = models.DateTimeField(null=True, blank=True)        

The database fields created for PostgreSQL 9.4 are :

  id              serial                    NOT NULL,

  "charNull"      character varying(10),
  "charBlank"     character varying(10)     NOT NULL,
  "charNullBlank" character varying(10),

  "intNull"       integer,
  "intBlank"      integer                   NOT NULL,
  "intNullBlank"  integer,

  "dateNull"      timestamp with time zone,
  "dateBlank"     timestamp with time zone  NOT NULL,
  "dateNullBlank" timestamp with time zone,

The database fields created for MySQL 5.6 are :

     `id`            INT(11)     NOT  NULL    AUTO_INCREMENT,

     `charNull`      VARCHAR(10) NULL DEFAULT NULL,
     `charBlank`     VARCHAR(10) NOT  NULL,
     `charNullBlank` VARCHAR(10) NULL DEFAULT NULL,

     `intNull`       INT(11)     NULL DEFAULT NULL,
     `intBlank`      INT(11)     NOT  NULL,
     `intNullBlank`  INT(11)     NULL DEFAULT NULL,

     `dateNull`      DATETIME    NULL DEFAULT NULL,
     `dateBlank`     DATETIME    NOT  NULL,
     `dateNullBlank` DATETIME    NULL DEFAULT NULL

How can I change NULL to 0 when getting a single value from a SQL function?

SELECT 0+COALESCE(SUM(Price),0) AS TotalPrice
FROM Inventory
WHERE (DateAdded BETWEEN @StartDate AND @EndDate)

JavaScript checking for null vs. undefined and difference between == and ===

How do I check a variable if it's null or undefined...

Is the variable null:

if (a === null)
// or
if (a == null) // but see note below

...but note the latter will also be true if a is undefined.

Is it undefined:

if (typeof a === "undefined")
// or
if (a === undefined)
// or
if (a == undefined) // but see note below

...but again, note that the last one is vague; it will also be true if a is null.

Now, despite the above, the usual way to check for those is to use the fact that they're falsey:

if (!a) {
    // `a` is falsey, which includes `undefined` and `null`
    // (and `""`, and `0`, and `NaN`, and [of course] `false`)

This is defined by ToBoolean in the spec.

...and what is the difference between the null and undefined?

They're both values usually used to indicate the absence of something. undefined is the more generic one, used as the default value of variables until they're assigned some other value, as the value of function arguments that weren't provided when the function was called, and as the value you get when you ask an object for a property it doesn't have. But it can also be explicitly used in all of those situations. (There's a difference between an object not having a property, and having the property with the value undefined; there's a difference between calling a function with the value undefined for an argument, and leaving that argument off entirely.)

null is slightly more specific than undefined: It's a blank object reference. JavaScript is loosely typed, of course, but not all of the things JavaScript interacts with are loosely typed. If an API like the DOM in browsers needs an object reference that's blank, we use null, not undefined. And similarly, the DOM's getElementById operation returns an object reference — either a valid one (if it found the DOM element), or null (if it didn't).

Interestingly (or not), they're their own types. Which is to say, null is the only value in the Null type, and undefined is the only value in the Undefined type.

What is the difference between "==" and "==="

The only difference between them is that == will do type coercion to try to get the values to match, and === won't. So for instance "1" == 1 is true, because "1" coerces to 1. But "1" === 1 is false, because the types don't match. ("1" !== 1 is true.) The first (real) step of === is "Are the types of the operands the same?" and if the answer is "no", the result is false. If the types are the same, it does exactly what == does.

Type coercion uses quite complex rules and can have surprising results (for instance, "" == 0 is true).

More in the spec:

Maven 3 Archetype for Project With Spring, Spring MVC, Hibernate, JPA

With appFuse framework, you can create an Spring MVC archetype with jpa support, etc ...

Take a look at it's quickStart guide to see how to create an archetype based on this Framework.

Foundational frameworks in AppFuse:

  • Bootstrap and jQuery
  • Maven, Hibernate, Spring and Spring Security
  • Java 7, Annotations, JSP 2.1, Servlet 3.0
  • Web Frameworks: JSF, Struts 2, Spring MVC, Tapestry 5, Wicket
  • JPA Support

For example to create an appFuse light archetype :

mvn archetype:generate -B -DarchetypeGroupId=org.appfuse.archetypes 
-DarchetypeArtifactId=appfuse-light-struts-archetype -DarchetypeVersion=2.2.1 
-DgroupId=com.mycompany -DartifactId=myproject

How to delete a selected DataGridViewRow and update a connected database table?

for (int j = dataGridView1.Rows.Count; j > 0 ; j--)
    if (dataGridView1.Rows[j-1].Selected)

Opening a folder in explorer and selecting a file

It might be a bit of a overkill but I like convinience functions so take this one:

    public static void ShowFileInExplorer(FileInfo file) {
        StartProcess("explorer.exe", null, "/select, "+file.FullName.Quote());
    public static Process StartProcess(FileInfo file, params string[] args) => StartProcess(file.FullName, file.DirectoryName, args);
    public static Process StartProcess(string file, string workDir = null, params string[] args) {
        ProcessStartInfo proc = new ProcessStartInfo();
        proc.FileName = file;
        proc.Arguments = string.Join(" ", args);
        Logger.Debug(proc.FileName, proc.Arguments); // Replace with your logging function
        if (workDir != null) {
            proc.WorkingDirectory = workDir;
            Logger.Debug("WorkingDirectory:", proc.WorkingDirectory); // Replace with your logging function
        return Process.Start(proc);

This is the extension function I use as <string>.Quote():

static class Extensions
    public static string Quote(this string text)
        return SurroundWith(text, "\"");
    public static string SurroundWith(this string text, string surrounds)
        return surrounds + text + surrounds;

isset() and empty() - what to use

It depends what you are looking for, if you are just looking to see if it is empty just use empty as it checks whether it is set as well, if you want to know whether something is set or not use isset.

Empty checks if the variable is set and if it is it checks it for null, "", 0, etc

Isset just checks if is it set, it could be anything not null

With empty, the following things are considered empty:

  • "" (an empty string)
  • 0 (0 as an integer)
  • 0.0 (0 as a float)
  • "0" (0 as a string)
  • NULL
  • array() (an empty array)
  • var $var; (a variable declared, but without a value in a class)


As mentioned in the comments the lack of warning is also important with empty()

PHP Manual says

empty() is the opposite of (boolean) var, except that no warning is generated when the variable is not set.

Regarding isset

PHP Manual says

isset() will return FALSE if testing a variable that has been set to NULL

Your code would be fine as:

    $var = '23';
    if (!empty($var)){
        echo 'not empty';
        echo 'is not set or empty';

For example:

$var = "";

if(empty($var)) // true because "" is considered empty
if(isset($var)) //true because var is set 

if(empty($otherVar)) //true because $otherVar is null
if(isset($otherVar)) //false because $otherVar is not set 

Replace comma with newline in sed on MacOS?

FWIW, the following line works in windows and replaces semicolons in my path variables with a newline. I'm using the tools installed under my git bin directory.

echo %path% | sed -e $'s/;/\\n/g' | less

Microsoft.Office.Core Reference Missing

If you are not able to find PIA for Office 2013 then follow these steps:

  1. Click on Solution Explorer in Visual Studio
  2. Right click on your project name (not solution name)
  3. Select 'Manage Nuget packages'
  4. Click on Browse and search for PIA 2013, choose the shown PIA and click on Install.....

And you are done.

How to increase scrollback buffer size in tmux?

This builds on ntc2 and Chris Johnsen's answer. I am using this whenever I want to create a new session with a custom history-limit. I wanted a way to create sessions with limited scrollback without permanently changing my history-limit for future sessions.

tmux set-option -g history-limit 100 \; new-session -s mysessionname \; set-option -g history-limit 2000

This works whether or not there are existing sessions. After setting history-limit for the new session it resets it back to the default which for me is 2000.

I created an executable bash script that makes this a little more useful. The 1st parameter passed to the script sets the history-limit for the new session and the 2nd parameter sets its session name:

tmux set-option -g history-limit "${1}" \; new-session -s "${2}" \; set-option -g history-limit 2000

Drop multiple tables in one shot in MySQL

declare @sql1 nvarchar(max) 
SELECT @sql1 =
           select ' drop table dbo.[' + name + ']'

           FROM sys.sysobjects AS sobjects
           WHERE (xtype = 'U') AND (name LIKE 'GROUP_BASE_NEW_WORK_%')
           for xml path('')
     1, 1, '')

  execute sp_executesql @sql1 Trust anchor for certification path not found

This is a Server-Side issue.

Server side have .crt file for HTTPS, here we have to do combine

cat your_domain.**crt** your_domain.**ca-bundle** >> ssl_your_domain_.crt 

then restart.

sudo service nginx restart

For me working fine.

Does Hibernate create tables in the database automatically

Yes it does in your case because of the below property in your config. This is ok during testing but in production you need to disable this.

<prop key="">create</prop>

onchange event on input type=range is not triggering in firefox while dragging

You could use the JavaScript "ondrag" event to fire continuously. It is better than "input" due to the following reasons:

  1. Browser support.

  2. Could differentiate between "ondrag" and "change" event. "input" fires for both drag and change.

In jQuery:




System.BadImageFormatException: Could not load file or assembly

I found a different solution to this issue. Apparently my IIS 7 did not have 32bit mode enabled in my Application Pool by default.

To enable 32bit mode, open IIS and select your Application Pool. Mine was named "ASP.NET v4.0".
Right click, go to "Advanced Settings" and change the section named: "Enabled 32-bit Applications" to true.

Restart your web server and try again.

I found the fix from this blog reference:

Additionally, you can change the settings on Visual Studio. In my case, I went to Tools > Options > Projects and Solutions > Web Projects and checked Use the 64 bit version of IIS Express for web sites and projects - This was on VS Pro 2015. Nothing else fixed it but this.

how to parse JSON file with GSON

In case you need to parse it from a file, I find the best solution to use a HashMap<String, String> to use it inside your java code for better manipultion.

Try out this code:

public HashMap<String, String> myMethodName() throws FileNotFoundException
    String path = "absolute path to your file";
    BufferedReader bufferedReader = new BufferedReader(new FileReader(path));

    Gson gson = new Gson();
    HashMap<String, String> json = gson.fromJson(bufferedReader, HashMap.class);
    return json;

Unable to begin a distributed transaction

My last adventure with MSDTC and this error today turned out to be a DNS issue. You're on the right track asking if the machines are on the same domain, EBarr. Terrific list for this issue, by the way!

My situation: I needed a server in a child domain to be able to run distributed transactions against a server in the parent domain through a firewall. I've used linked servers quite a bit over the years, so I had all the usual settings in SQL for a linked server and in MSDTC that Ian documented so nicely above. I set up MSDTC with a range of TCP ports (5000-5200) to use on both servers, and arranged for a firewall hole between the boxes for ports 1433 and 5000-5200. That should have worked. The linked server tested OK and I could query the remote SQL server via the linked server nicely, but I couldn't get it to allow a distributed transaction. I could even see a connection on the QA server from the DEV server, but something wasn't making the trip back.

I could PING the DEV server from QA using a FQDN like: PING

I could not PING the DEV server with just the machine name: PING DEVSQL

The DEVSQL server was supposed to be a member of both domains, but the name wasn't resolving in the parent domain's DNS... something had happened to the machine account for DEVSQL in the parent domain. Once we added DEVSQL to the DNS for the parent domain, and "PING DEVSQL" worked from the remote QA server, this issue was resolved for us.

I hope this helps!

Can I force a UITableView to hide the separator between empty cells?

You can achieve what you want by defining a footer for the tableview. See this answer for more details:Eliminate Extra separators below UITableView

Why doesn't C++ have a garbage collector?

What type? should it be optimised for embedded washing machine controllers, cell phones, workstations or supercomputers?
Should it prioritise gui responsiveness or server loading?
should it use lots of memory or lots of CPU?

C/c++ is used in just too many different circumstances. I suspect something like boost smart pointers will be enough for most users

Edit - Automatic garbage collectors aren't so much a problem of performance (you can always buy more server) it's a question of predicatable performance.
Not knowing when the GC is going to kick in is like employing a narcoleptic airline pilot, most of the time they are great - but when you really need responsiveness!

Programmatically navigate using react router V4

My answer is similar to Alex's. I'm not sure why React-Router made this so needlessly complicated. Why should I have to wrap my component with a HoC just to get access to what's essentially a global?

Anyway, if you take a look at how they implemented <BrowserRouter>, it's just a tiny wrapper around history.

We can pull that history bit out so that we can import it from anywhere. The trick, however, is if you're doing server-side rendering and you try to import the history module, it won't work because it uses browser-only APIs. But that's OK because we usually only redirect in response to a click or some other client-side event. Thus it's probably OK to fake it:

// history.js
if(__SERVER__) {
    module.exports = {};
} else {
    module.exports = require('history').createBrowserHistory();

With the help of webpack, we can define some vars so we know what environment we're in:

plugins: [
    new DefinePlugin({
        '__SERVER__': 'false',
        '__BROWSER__': 'true', // you really only need one of these, but I like to have both

And now you can

import history from './history';

From anywhere. It'll just return an empty module on the server.

If you don't want use these magic vars, you'll just have to require in the global object where it's needed (inside your event handler). import won't work because it only works at the top-level.

C: Run a System Command and Get Output?

You need some sort of Inter Process Communication. Use a pipe or a shared buffer.

How to add Android Support Repository to Android Studio?

Instead of doing this:

compile ""

Do this:

compile '' 

Worked for me

scp via java

-: Refining Fernando's answer a little, if you use Maven for dependency management :-



Add this dependency in your project. Latest version can be found here.

Java code:

public void scpUpload(String source, String destination) {
    Scp scp = new Scp();
    scp.setTodir(username + ":" + password + "@" + host + ":" + destination);
    scp.setProject(new Project());

convert php date to mysql format

If you know the format of date in $_POST[intake_date] you can use explode to get year , month and time and then concatenate to form a valid mySql date. for example if you are getting something like 12/15/1988 in date you can do like this

    $date = explode($_POST['intake_date'], '/');
    mysql_date = $date[2].'-'$date[1].'-'$date[0];

though if you have valid date date('y-m-d', strtotime($date)); should also work

JPA Hibernate One-to-One relationship

I'm not sure you can use a relationship as an Id/PrimaryKey in Hibernate.

Error when checking Java version: could not find java.dll

Reinstall JDK and set system variable JAVA_HOME on your JDK. (e.g. C:\tools\jdk7)
And add JAVA_HOME variable to your PATH system variable

Type in command line

echo %JAVA_HOME%


java -version

To verify whether your installation was done successfully.

This problem generally occurs in Windows when your "Java Runtime Environment" registry entry is missing or mismatched with the installed JDK. The mismatch can be due to multiple JDKs.

Steps to resolve:

  1. Open the Run window:

    Press windows+R

  2. Open registry window:

    Type regedit and enter.


  4. If Java Runtime Environment is not present inside JavaSoft, then create a new Key and give the name Java Runtime Environment.

  5. For Java Runtime Environment create "CurrentVersion" String Key and give appropriate version as value:

JRE regedit entry

  1. Create a new subkey of 1.8.

  2. For 1.8 create a String Key with name JavaHome with the value of JRE home:

    JRE regedit entry 2


WebService Client Generation Error with JDK8

Create a file named (if it doesn’t exist) under path to your "JDK version/jre/lib" and then add the following line in it.

javax.xml.accessExternalSchema = all

Convert object array to hash map, indexed by an attribute value of the Object

This is what I'm doing in TypeScript I have a little utils library where I put things like this

export const arrayToHash = (array: any[], id: string = 'id') => 
         array.reduce((obj, item) =>  (obj[item[id]] = item , obj), {})


const hash = arrayToHash([{id:1,data:'data'},{id:2,data:'data'}])

or if you have a identifier other than 'id'

const hash = arrayToHash([{key:1,data:'data'},{key:2,data:'data'}], 'key')

Batch - If, ElseIf, Else

Recommendation. Do not use user-added REM statements to block batch steps. Use conditional GOTO instead. That way you can predefine and test the steps and options. The users also get much simpler changes and better confidence.

@Echo on
rem Using flags to control command execution

SET ExecuteSection1=0
SET ExecuteSection2=1

@echo off

IF %ExecuteSection1%==0 GOTO EndSection1
ECHO Section 1 Here


IF %ExecuteSection2%==0 GOTO EndSection2
ECHO Section 2 Here

Math constant PI value in C

Just define:

#define M_PI acos(-1.0)

It should give you exact PI number that math functions are working with. So if they change PI value they are working with in tangent or cosine or sine, then your program should be always up-to-dated ;)

Laravel form html with PUT method for PUT routes

You CAN add css clases, and any type of attributes you need to blade template, try this:

{{ Form::open(array('url' => '/', 'method' => 'PUT', 'class'=>'col-md-12')) }}
.... wathever code here
{{ Form::close() }}

If you dont want to go the blade way you can add a hidden input. This is the form Laravel does, any way:

Note: Since HTML forms only support POST and GET, PUT and DELETE methods will be spoofed by automatically adding a _method hidden field to your form. (Laravel docs)

<form class="col-md-12" action="<?php echo URL::to('/');?>/post/<?=$post->postID?>" method="POST">

    <!-- Rendered blade HTML form use this hidden. Dont forget to put the form method to POST -->

    <input name="_method" type="hidden" value="PUT">

    <div class="form-group">
        <textarea type="text" class="form-control input-lg" placeholder="Text Here" name="post"><?=$post->post?></textarea>

    <div class="form-group">
        <button class="btn btn-primary btn-lg btn-block" type="submit" value="Edit">Edit</button>

Use grep --exclude/--include syntax to not grep through certain files

I find grepping grep's output to be very helpful sometimes:

grep -rn "foo=" . | grep -v "Binary file"

Though, that doesn't actually stop it from searching the binary files.

Jenkins - how to build a specific branch

Best solution can be:

Add a string parameter in the existing job enter image description here

Then in the Source Code Management section update Branches to build to use the string parameter you defined enter image description here

If you see a checkbox labeled Lightweight checkout, make sure it is unchecked.

The configuration indicated in the images will tell the jenkins job to use master as the default branch, and for manual builds it will ask you to enter branch details (FYI: by default it's set to master)enter image description here

Convert hours:minutes:seconds into total minutes in excel

The only way is to use a formula or to format cells. The method i will use will be the following: Add another column next to these values. Then use the following formula:


enter image description here

Fatal error: [] operator not supported for strings

Such behavior is described in Migrating from PHP 7.0.x to PHP 7.1.x/

The empty index operator is not supported for strings anymore Applying the empty index operator to a string (e.g. $str[] = $x) throws a fatal error instead of converting silently to array.

In my case it was a mere initialization. I fixed it by replacing $foo='' with $foo=[].


Spring Hibernate - Could not obtain transaction-synchronized Session for current thread

I added these configuration in web.xml and it works well for me!


Additionally, the most ranked answer give me clues to prevent application from panic at the first run.

How do I set up Eclipse/EGit with GitHub?

In Eclipse, go to Help -> Install New Software -> Add -> Name: any name like egit; Location: -> Okay. Now Search for egit in Work with and select all the check boxes and press Next till finish.

File -> Import -> search Git and select "Projects from Git" -> Clone URI. In the URI, paste the HTTPS URL of the repository (the one with .git extension). -> Next ->It will show all the branches "Next" -> Local Destination "Next" -> "Import as a general project" -> Next till finish.

You can refer to this Youtube tutorial:

ASP.NET MVC: What is the correct way to redirect to pages/actions in MVC?

1) To redirect to the login page / from the login page, don't use the Redirect() methods. Use FormsAuthentication.RedirectToLoginPage() and FormsAuthentication.RedirectFromLoginPage() !

2) You should just use RedirectToAction("action", "controller") in regular scenarios.. You want to redirect in side the Initialize method? Why? I don't see why would you ever want to do this, and in most cases you should review your approach imo.. If you want to do this for authentication this is DEFINITELY the wrong way (with very little chances foe an exception) Use the [Authorize] attribute on your controller or method instead :)

UPD: if you have some security checks in the Initialise method, and the user doesn't have access to this method, you can do a couple of things: a)

Response.StatusCode = 403;

This will send the user back to the login page. If you want to send him to a custom location, you can do something like this (cautios: pseudocode)

Response.Redirect(Url.Action("action", "controller"));

No need to specify the full url. This should be enough. If you completely insist on the full url:

Response.Redirect(new Uri(Request.Url, Url.Action("action", "controller")).ToString());

How to take column-slices of dataframe in pandas

Its equivalent

 >>> print(df2.loc[140:160,['Relevance','Title']])
 >>> print(df2.ix[140:160,[3,7]])

Do we need type="text/css" for <link> in HTML5

The HTML5 spec says that the type attribute is purely advisory and explains in detail how browsers should act if it's omitted (too much to quote here). It doesn't explicitly say that an omitted type attribute is either valid or invalid, but you can safely omit it knowing that browsers will still react as you expect.

Swift Error: Editor placeholder in source file

Go to Product > Clean Build Folder

CSS content property: is it possible to insert HTML instead of Text?

Unfortunately, this is not possible. Per the spec:

Generated content does not alter the document tree. In particular, it is not fed back to the document language processor (e.g., for reparsing).

In other words, for string values this means the value is always treated literally. It is never interpreted as markup, regardless of the document language in use.

As an example, using the given CSS with the following HTML:

<h1 class="header">Title</h1>

... will result in the following output:

<a href="#top">Back</a>Title

JavaScript: Upload file

Unless you're trying to upload the file using ajax, just submit the form to /upload/image.

<form enctype="multipart/form-data" action="/upload/image" method="post">
    <input id="image-file" type="file" />

If you do want to upload the image in the background (e.g. without submitting the whole form), you can use ajax:

Change a branch name in a Git repo

If you're currently on the branch you want to rename:

git branch -m new_name 

Or else:

git branch -m old_name new_name 

You can check with:

git branch -a

As you can see, only the local name changed Now, to change the name also in the remote you must do:

git push origin :old_name

This removes the branch, then upload it with the new name:

git push origin new_name


How to add google-services.json in Android?

It should be on Project -> app folder

Please find the screenshot from Firebase website

enter image description here

How to use a class from one C# project with another C# project

To provide another much simpler solution:-

  1. Within the project, right click and select "Add -> Existing"
  2. Navigate to the class file in the adjacent project.
  3. The Add button is also a dropdown, click the dropdown and select

"Add as link"

Thats it.

How can I add reflection to a C++ application?

This question is a bit old now (don't know why I keep hitting old questions today) but I was thinking about BOOST_FUSION_ADAPT_STRUCT which introduces compile-time reflection.

It is up to you to map this to run-time reflection of course, and it won't be too easy, but it is possible in this direction, while it would not be in the reverse :)

I really think a macro to encapsulate the BOOST_FUSION_ADAPT_STRUCT one could generate the necessary methods to get the runtime behavior.

Difference between SET autocommit=1 and START TRANSACTION in mysql (Have I missed something?)

Being aware of the transaction (autocommit, explicit and implicit) handling for your database can save you from having to restore data from a backup.

Transactions control data manipulation statement(s) to ensure they are atomic. Being "atomic" means the transaction either occurs, or it does not. The only way to signal the completion of the transaction to database is by using either a COMMIT or ROLLBACK statement (per ANSI-92, which sadly did not include syntax for creating/beginning a transaction so it is vendor specific). COMMIT applies the changes (if any) made within the transaction. ROLLBACK disregards whatever actions took place within the transaction - highly desirable when an UPDATE/DELETE statement does something unintended.

Typically individual DML (Insert, Update, Delete) statements are performed in an autocommit transaction - they are committed as soon as the statement successfully completes. Which means there's no opportunity to roll back the database to the state prior to the statement having been run in cases like yours. When something goes wrong, the only restoration option available is to reconstruct the data from a backup (providing one exists). In MySQL, autocommit is on by default for InnoDB - MyISAM doesn't support transactions. It can be disabled by using:

SET autocommit = 0

An explicit transaction is when statement(s) are wrapped within an explicitly defined transaction code block - for MySQL, that's START TRANSACTION. It also requires an explicitly made COMMIT or ROLLBACK statement at the end of the transaction. Nested transactions is beyond the scope of this topic.

Implicit transactions are slightly different from explicit ones. Implicit transactions do not require explicity defining a transaction. However, like explicit transactions they require a COMMIT or ROLLBACK statement to be supplied.


Explicit transactions are the most ideal solution - they require a statement, COMMIT or ROLLBACK, to finalize the transaction, and what is happening is clearly stated for others to read should there be a need. Implicit transactions are OK if working with the database interactively, but COMMIT statements should only be specified once results have been tested & thoroughly determined to be valid.

That means you should use:

SET autocommit = 0;

  UPDATE ...;

...and only use COMMIT; when the results are correct.

That said, UPDATE and DELETE statements typically only return the number of rows affected, not specific details. Convert such statements into SELECT statements & review the results to ensure correctness prior to attempting the UPDATE/DELETE statement.


DDL (Data Definition Language) statements are automatically committed - they do not require a COMMIT statement. IE: Table, index, stored procedure, database, and view creation or alteration statements.

Check if a parameter is null or empty in a stored procedure

To check if variable is null or empty use this:

IF LEN(ISNULL(@var, '')) = 0

Python Save to file

You need to open the file again using open(), but this time passing 'w' to indicate that you want to write to the file. I would also recommend using with to ensure that the file will be closed when you are finished writing to it.

with open('Failed.txt', 'w') as f:
    for ip in [k for k, v in ips.iteritems() if v >=5]:

Naturally you may want to include newlines or other formatting in your output, but the basics are as above.

The same issue with closing your file applies to the reading code. That should look like this:

ips = {}
with open('today','r') as myFile:
    for line in myFile:
        parts = line.split(' ')
        if parts[1] == 'Failure':
            if parts[0] in ips:
                ips[pars[0]] += 1
                ips[parts[0]] = 0

Row count on the Filtered data

If you try to count the number of rows in the already autofiltered range like this:

Rowz = rnData.SpecialCells(xlCellTypeVisible).Rows.Count

It will only count the number of rows in the first contiguous visible area of the autofiltered range. E.g. if the autofilter range is rows 1 through 10 and rows 3, 5, 6, 7, and 9 are filtered, four rows are visible (rows 2, 4, 8, and 10), but it would return 2 because the first contiguous visible range is rows 1 (the header row) and 2.

A more accurate alternative is this (assuming that ws contains the worksheet with the filtered data):

Rowz = ws.AutoFilter.Range.Columns(1).SpecialCells(xlCellTypeVisible).Cells.Count - 1

We have to subtract 1 to remove the header row. We need to include the header row in our counted range because SpecialCells will throw an error if no cells are found, which we want to avoid.

The Cells property will give you an accurate count even if the Range has multiple Areas, unlike the Rows property. So we just take the first column of the autofilter range and count the number of visible cells.

Redirect to external URL with return in laravel

Define the url you want to redirect in $url

Then just use

return Redirect::away($url);

If you want to redirect inside your views use

return Redirect::to($url);

Read more about Redirect here

Update 1 :

Here is the simple example

return Redirect::to('');

Update 2 :

As the Questioner wants to return in the same page

$triggersms = file_get_contents('');
return $triggersms;

Regex: Use start of line/end of line signs (^ or $) in different context

You can't use ^ and $ in character classes in the way you wish - they will be interpreted literally, but you can use an alternation to achieve the same effect:


What is the difference between "Form Controls" and "ActiveX Control" in Excel 2010?

Be careful, in some cases clicking on a Form Control or Active X Control will give two different results for the same macro - which should not be the case. I find Active X more reliable.

z-index not working with fixed positioning

This question can be solved in a number of ways, but really, knowing the stacking rules allows you to find the best answer that works for you.


The <html> element is your only stacking context, so just follow the stacking rules inside a stacking context and you will see that elements are stacked in this order

  1. The stacking context’s root element (the <html> element in this case)
  2. Positioned elements (and their children) with negative z-index values (higher values are stacked in front of lower values; elements with the same value are stacked according to appearance in the HTML)
  3. Non-positioned elements (ordered by appearance in the HTML)
  4. Positioned elements (and their children) with a z-index value of auto (ordered by appearance in the HTML)
  5. Positioned elements (and their children) with positive z-index values (higher values are stacked in front of lower values; elements with the same value are stacked according to appearance in the HTML)

So you can

  1. set a z-index of -1, for #under positioned -ve z-index appear behind non-positioned #over element
  2. set the position of #over to relative so that rule 5 applies to it

The Real Problem

Developers should know the following before trying to change the stacking order of elements.

  1. When a stacking context is formed
    • By default, the <html> element is the root element and is the first stacking context
  2. Stacking order within a stacking context

The Stacking order and stacking context rules below are from this link

When a stacking context is formed

  • When an element is the root element of a document (the <html> element)
  • When an element has a position value other than static and a z-index value other than auto
  • When an element has an opacity value less than 1
  • Several newer CSS properties also create stacking contexts. These include: transforms, filters, css-regions, paged media, and possibly others.
  • As a general rule, it seems that if a CSS property requires rendering in an offscreen context, it must create a new stacking context.

Stacking Order within a Stacking Context

The order of elements:

  1. The stacking context’s root element (the <html> element is the only stacking context by default, but any element can be a root element for a stacking context, see rules above)
    • You cannot put a child element behind a root stacking context element
  2. Positioned elements (and their children) with negative z-index values (higher values are stacked in front of lower values; elements with the same value are stacked according to appearance in the HTML)
  3. Non-positioned elements (ordered by appearance in the HTML)
  4. Positioned elements (and their children) with a z-index value of auto (ordered by appearance in the HTML)
  5. Positioned elements (and their children) with positive z-index values (higher values are stacked in front of lower values; elements with the same value are stacked according to appearance in the HTML)

jQuery if checkbox is checked

if ($('input.checkbox_check').is(':checked')) {

List of enum values in java

This is a more generic solution, that can be use for any Enum object, so be free of used.

static public List<Object> constFromEnumToList(Class enumType) {
    List<Object> nueva = new ArrayList<Object>();
    if (enumType.isEnum()) {
        try {
            Class<?> cls = Class.forName(enumType.getCanonicalName());
            Object[] consts = cls.getEnumConstants();
        } catch (ClassNotFoundException e) {
            System.out.println("No se localizo la clase");
    return nueva;

Now you must call this way:


Python locale error: unsupported locale setting

More permanent solution would be to fill the missing values, in the output shown by command: locale

Output from locale is:

 $ locale

To Fill the missing values edit ~/.bashrc :

 $ vim ~/.bashrc

Add the following lines after the above command (suppose you want en_US.UTF-8 to be your language):

export LANGUAGE="en_US.UTF-8"
export LC_ALL="en_US.UTF-8"

If this file is ReadOnly you would be needing to follow the steps mentioned by The GeekyBoy. The answer given by Dr Beco in Superuser has details relating to saving readonly files.

After saving the file do:

$ source ~/.bashrc

Now you wont be facing the same problem anymore.

Regular expression for floating point numbers

[+/-] [0-9]*.[0-9]+

Try this solution.

How to list installed packages from a given repo using yum


yum list installed | grep reponame

On one of my servers:

yum list installed | grep remi
ImageMagick2.x86_64                       installed
memcache.x86_64                          1.4.5-2.el5.remi             installed
mysql.x86_64                              5.1.54-1.el5.remi            installed
mysql-devel.x86_64                        5.1.54-1.el5.remi            installed
mysql-libs.x86_64                         5.1.54-1.el5.remi            installed
mysql-server.x86_64                       5.1.54-1.el5.remi            installed
mysqlclient15.x86_64                      5.0.67-1.el5.remi            installed
php.x86_64                                5.3.5-1.el5.remi             installed
php-cli.x86_64                            5.3.5-1.el5.remi             installed
php-common.x86_64                         5.3.5-1.el5.remi             installed
php-domxml-php4-php5.noarch               1.21.2-1.el5.remi            installed
php-fpm.x86_64                            5.3.5-1.el5.remi             installed
php-gd.x86_64                             5.3.5-1.el5.remi             installed
php-mbstring.x86_64                       5.3.5-1.el5.remi             installed
php-mcrypt.x86_64                         5.3.5-1.el5.remi             installed
php-mysql.x86_64                          5.3.5-1.el5.remi             installed
php-pdo.x86_64                            5.3.5-1.el5.remi             installed
php-pear.noarch                           1:1.9.1-6.el5.remi           installed
php-pecl-apc.x86_64                       3.1.6-1.el5.remi             installed
php-pecl-imagick.x86_64                   3.0.1-1.el5.remi.1           installed
php-pecl-memcache.x86_64                  3.0.5-1.el5.remi             installed
php-pecl-xdebug.x86_64                    2.1.0-1.el5.remi             installed
php-soap.x86_64                           5.3.5-1.el5.remi             installed
php-xml.x86_64                            5.3.5-1.el5.remi             installed
remi-release.noarch                       5-8.el5.remi                 installed

It works.

Lock, mutex, semaphore... what's the difference?

There are a lot of misconceptions regarding these words.

This is from a previous post ( which fits superb here:

1) Critical Section= User object used for allowing the execution of just one active thread from many others within one process. The other non selected threads (@ acquiring this object) are put to sleep.

[No interprocess capability, very primitive object].

2) Mutex Semaphore (aka Mutex)= Kernel object used for allowing the execution of just one active thread from many others, among different processes. The other non selected threads (@ acquiring this object) are put to sleep. This object supports thread ownership, thread termination notification, recursion (multiple 'acquire' calls from same thread) and 'priority inversion avoidance'.

[Interprocess capability, very safe to use, a kind of 'high level' synchronization object].

3) Counting Semaphore (aka Semaphore)= Kernel object used for allowing the execution of a group of active threads from many others. The other non selected threads (@ acquiring this object) are put to sleep.

[Interprocess capability however not very safe to use because it lacks following 'mutex' attributes: thread termination notification, recursion?, 'priority inversion avoidance'?, etc].

4) And now, talking about 'spinlocks', first some definitions:

Critical Region= A region of memory shared by 2 or more processes.

Lock= A variable whose value allows or denies the entrance to a 'critical region'. (It could be implemented as a simple 'boolean flag').

Busy waiting= Continuosly testing of a variable until some value appears.


Spin-lock (aka Spinlock)= A lock which uses busy waiting. (The acquiring of the lock is made by xchg or similar atomic operations).

[No thread sleeping, mostly used at kernel level only. Ineffcient for User level code].

As a last comment, I am not sure but I can bet you some big bucks that the above first 3 synchronizing objects (#1, #2 and #3) make use of this simple beast (#4) as part of their implementation.

Have a good day!.


-Real-Time Concepts for Embedded Systems by Qing Li with Caroline Yao (CMP Books).

-Modern Operating Systems (3rd) by Andrew Tanenbaum (Pearson Education International).

-Programming Applications for Microsoft Windows (4th) by Jeffrey Richter (Microsoft Programming Series).

Also, you can take a look at look at:

Is there a performance difference between CTE , Sub-Query, Temporary Table or Table Variable?

Just 2 things I think make it ALWAYS preferable to use a # Temp Table rather then a CTE are:

  1. You can not put a primary key on a CTE so the data being accessed by the CTE will have to traverse each one of the indexes in the CTE's tables rather then just accessing the PK or Index on the temp table.

  2. Because you can not add constraints, indexes and primary keys to a CTE they are more prone to bugs creeping in and bad data.

-onedaywhen yesterday

Here is an example where #table constraints can prevent bad data which is not the case in CTE's

                       ThisID int
                     , ThatID int );
       ( ThisID
       , ThatID
       ( 1, 1 ),
       ( 1, 2 ),
       ( 2, 2 ),
       ( 1, 1 );

IF OBJECT_ID('tempdb..#This') IS NOT NULL
    DROP TABLE #This;
             ThisID int NOT NULL
           , ThatID int NOT NULL
                        UNIQUE(ThisID, ThatID) );
     AS (SELECT *
           FROM @BadData)
     SELECT *
       FROM This_CTE;

Launch an app from within another (iPhone)

No it's not. Besides the documented URL handlers, there's no way to communicate with/launch another app.

Why do I need to configure the SQL dialect of a data source?

Short answer

"The irony of JDBC is that, although the programming interfaces are portable, the SQL language is not. Despite the many attempts to standardize it, it is still rare to write SQL of any complexity that will run unchanged on two major database platforms. Even where the SQL dialects are similar, each database performs differently depending on the structure of the query, necessitating vendor-specific tuning in most cases."

..stolen from Pro JPA 2 Mastering the Java Persistence API, chapter 1, page 9

So, we might think of JDBC as the ultimate specification that abstracts away everything related to databases, but it isn't.

A quote from the JDBC specification, chapter 4.4, page 20:

The driver layer may mask differences between standard SQL:2003 syntax and the native dialect supported by the data source.

May is no guarantee that the driver will, and therefore we should provide the dialect in order to have a working application. In a best-case scenario, the application will work but might not run as effectively as it could if the persistence provider knew which dialect to use. In the case of Hibernate he will refuse to deploy your application unless you feed him the dialect.

What about JPQL then?

The JDBC specification does not mention the word JPQL. JDBC is a standardized way of database access. Go read this JavaDoc and you will find that once the application can access the database, what must be fed into the JDBC compliant driver is vanilla = undecorated SQL.

It is worth noting that JPQL is a query language, not a data definition language (DDL). So even if we could feed the JDBC driver with JPQL, that would be of no use for the persistence provider during the phase of parsing the persistence.xml file and setting up tables.

Closer look at the property

For your reference, here is an example for Hibernate and EclipseLink on how to specify a Java DB dialect in the persistence.xml file:

<property name="hibernate.dialect" value="org.hibernate.dialect.DerbyTenSevenDialect"/>
<property name="" value="JavaDB"/>

Is the property mandatory?

In theory, the property has not been standardized and the JPA 2.1 specification says not a word about SQL dialects. So we're out of luck and must turn to vendor specific empirical studies and documentation thereof.

Hibernate refuse to accept a deployment archive that hasn't specified the property rendering the archive undeployable. Hibernate documentation says:

Always set the hibernate.dialect property to the correct org.hibernate.dialect.Dialect subclass for your database.

So that is pretty clear. Do note that the dialects listed in the documentation are specifically targeting one or the other vendor. There is no "generic" dialect or anything like that. Given then that the property is an absolute requirement for a successful deployment, you would expect that the documentation of the WildFly application server which bundles Hibernate should say something, but it doesn't.

EclipseLink on the other hand is a bit more forgiving. If you don't provide the property, the deployment deploys (without warning too). EclipseLink documentation says:

Use the property to specify the database to use, controlling custom operations and SQL generation for the specified database.

The talk is about "custom operations and SQL generation", meaning it is bit vague if you ask me. But one thing is clear: They don't say that the property is mandatory. Also note that one of the available values is "Database" which represent "a generic database" target. Hmm, what "dialect" would that be? SQL 2.0?? But then again, the property is called "target-database" and not "dialect" so maybe "Database" translates to no SQL at all lol. Moving on to the GlassFish server which bundles EclipseLink. Documentation (page "6-3") says:

You can specify the optional property to guarantee that the database type is correct.

So GlassFish argues that the property is "optional" and the value added is a "guarantee" that I am actually using Java DB - in case I didn't know.


Copy-paste whatever you can find on google and pray to God.

Case Insensitive String comp in C

As others have stated, there is no portable function that works on all systems. You can partially circumvent this with simple ifdef:

#include <stdio.h>

#ifdef _WIN32
#include <string.h>
#define strcasecmp _stricmp
#else // assuming POSIX or BSD compliant system
#include <strings.h>

int main() {
    printf("%d", strcasecmp("teSt", "TEst"));

psql: FATAL: Ident authentication failed for user "postgres"

If you've done all this and it still doesn't work, check the expiry for that user:

Postgres password authentication fails

How to write console output to a txt file

In addition to the several programatic approaches discussed, another option is to redirect standard output from the shell. Here are several Unix and DOS examples.

Creating and throwing new exception

You can throw your own custom errors by extending the Exception class.

class CustomException : Exception {
    [string] $additionalData

    CustomException($Message, $additionalData) : base($Message) {
        $this.additionalData = $additionalData

try {
    throw [CustomException]::new('Error message', 'Extra data')
} catch [CustomException] {
    # NOTE: To access your custom exception you must use $_.Exception
    Write-Output $_.Exception.additionalData

    # This will produce the error message: Didn't catch it the second time
    throw [CustomException]::new("Didn't catch it the second time", 'Extra data')

Pytorch tensor to numpy array

There are 4 dimensions of the tensor you want to convert.

[:, ::-1, :, :] 

: means that the first dimension should be copied as it is and converted, same goes for the third and fourth dimension.

::-1 means that for the second axes it reverses the the axes

SQL join: selecting the last records in a one-to-many relationship

Without getting into the code first, the logic/algorithm goes below:

  1. Go to the transaction table with multiple records for the same client.

  2. Select records of clientID and the latestDate of client's activity using group by clientID and max(transactionDate)

       select clientID, max(transactionDate) as latestDate 
       from transaction 
       group by clientID
  3. inner join the transaction table with the outcome from Step 2, then you will have the full records of the transaction table with only each client's latest record.

       select * from 
       transaction t 
       inner join (
         select clientID, max(transactionDate) as latestDate
         from transaction 
         group by clientID) d 
       on t.clientID = d.clientID and t.transactionDate = d.latestDate) 
  4. You can use the result from step 3 to join any table you want to get different results.

using where and inner join in mysql

    SELECT `locations`.`name`
      FROM `locations`
INNER JOIN `school_locations`
        ON `locations`.`id` = `school_locations`.`location_id`
INNER JOIN `schools`
        ON `school_locations`.`school_id` = `schools_id`
     WHERE `type` = 'coun';

the WHERE clause has to be at the end of the statement

Convert System.Drawing.Color to RGB and Hex Value

You could keep it simple and use the native color translator:

Color red = ColorTranslator.FromHtml("#FF0000");
string redHex = ColorTranslator.ToHtml(red);

Then break the three color pairs into integer form:

int value = int.Parse(hexValue, System.Globalization.NumberStyles.HexNumber);

How to compare datetime with only date in SQL Server

If you are on SQL Server 2008 or later you can use the date datatype:

FROM [User] U
WHERE CAST(U.DateCreated as DATE) = '2014-02-07'

It should be noted that if date column is indexed then this will still utilise the index and is SARGable. This is a special case for dates and datetimes.

enter image description here

You can see that SQL Server actually turns this into a > and < clause:

enter image description here

I've just tried this on a large table, with a secondary index on the date column as per @kobik's comments and the index is still used, this is not the case for the examples that use BETWEEN or >= and <:

FROM [User] U
WHERE CAST(U.DateCreated as DATE) = '2016-07-05'

showing index usage with secondary index