Programs & Examples On #Glazedlists


Sorted array list in Java

Aioobe's approach is the way to go. I would like to suggest the following improvement over his solution though.

class SortedList<T> extends ArrayList<T> {

    public void insertSorted(T value) {
        int insertPoint = insertPoint(value);
        add(insertPoint, value);

     * @return The insert point for a new value. If the value is found the insert point can be any
     * of the possible positions that keeps the collection sorted (.33 or 3.3 or 33.).
    private int insertPoint(T key) {
        int low = 0;
        int high = size() - 1;

        while (low <= high) {
            int mid = (low + high) >>> 1;
            Comparable<? super T> midVal = (Comparable<T>) get(mid);
            int cmp = midVal.compareTo(key);

            if (cmp < 0)
                low = mid + 1;
            else if (cmp > 0)
                high = mid - 1;
            else {
                return mid; // key found

        return low;  // key not found

aioobe's solution gets very slow when using large lists. Using the fact that the list is sorted allows us to find the insert point for new values using binary search.

I would also use composition over inheritance, something along the lines of

SortedList<E> implements List<E>, RandomAccess, Cloneable,

MVC 4 Razor File Upload

you just have to change the name of your input filed because same name is required in parameter and input field name just replace this line Your code working fine

 <input type="file" name="file" />

How to paginate with Mongoose in Node.js?

Use this simple plugin.


npm install mongoose-paginate-v2
_x000D_ Usage Add plugin to a schema and then use model paginate method:

const mongoose         = require('mongoose');_x000D_
const mongoosePaginate = require('mongoose-paginate-v2');_x000D_
const mySchema = new mongoose.Schema({ _x000D_
  /* your schema definition */ _x000D_
const myModel = mongoose.model('SampleModel',  mySchema); _x000D_
myModel.paginate().then({}) // Usage

Use '=' or LIKE to compare strings in SQL?

For pattern matching use LIKE. For exact match =.

Determining whether an object is a member of a collection in VBA

Not exactly elegant, but the best (and quickest) solution i could find was using OnError. This will be significantly faster than iteration for any medium to large collection.

Public Function InCollection(col As Collection, key As String) As Boolean
  Dim var As Variant
  Dim errNumber As Long

  InCollection = False
  Set var = Nothing

  On Error Resume Next
    var = col.Item(key)
    errNumber = CLng(Err.Number)
  On Error GoTo 0

  '5 is not in, 0 and 438 represent incollection
  If errNumber = 5 Then ' it is 5 if not in collection
    InCollection = False
    InCollection = True
  End If

End Function

What does it mean to have an index to scalar variable error? python

exponent is a 1D array. This means that exponent[0] is a scalar, and exponent[0][i] is trying to access it as if it were an array.

Did you mean to say:

L = identity(len(l))
for i in xrange(len(l)):
    L[i][i] = exponent[i]

or even

L = diag(exponent)


Explanation of <script type = "text/template"> ... </script>

It's legit and very handy!

Try this:

<script id="hello" type="text/template">
  Hello world

Several Javascript templating libraries use this technique. Handlebars.js is a good example.

Check if an array is empty or exists

Probably your image_array is not array but some OBJECT with length property (like string) - try

if(image_array instanceof Array && image_array.length)

function test(image_array) {
  if(image_array instanceof Array && image_array.length) { 
    console.log(image_array,'- it is not empty array!')
  } else {
    console.log(image_array,'- it is empty array or not array at all!')


Difference between rake db:migrate db:reset and db:schema:load



  • rake db:migrate If you wanna make changes to the schema
  • rake db:reset If you wanna drop the database, reload the schema from schema.rb, and reseed the database
  • rake db:schema:load If you wanna reset database to schema as provided in schema.rb (This will delete all data)


rake db:schema:load will set up the schema as provided in schema.rb file. This is useful for a fresh install of app as it doesn't take as much time as db:migrate

Important note, db:schema:load will delete data on server.

rake db:migrate makes changes to the existing schema. Its like creating versions of schema. db:migrate will look in db/migrate/ for any ruby files and execute the migrations that aren't run yet starting with the oldest. Rails knows which file is the oldest by looking at the timestamp at the beginning of the migration filename. db:migrate comes with a benefit that data can also be put in the database. This is actually not a good practice. Its better to use rake db:seed to add data.

rake db:migrate provides tasks up, down etc which enables commands like rake db:rollback and makes it the most useful command.

rake db:reset does a db:drop and db:setup
It drops the database, create it again, loads the schema, and initializes with the seed data

Relevant part of the commands from databases.rake

namespace :schema do
  desc 'Creates a db/schema.rb file that is portable against any DB supported by Active Record'
  task :dump => [:environment, :load_config] do
    require 'active_record/schema_dumper'
    filename = ENV['SCHEMA'] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, 'schema.rb'), "w:utf-8") do |file|
      ActiveRecord::SchemaDumper.dump(ActiveRecord::Base.connection, file)

  desc 'Loads a schema.rb file into the database'
  task :load => [:environment, :load_config, :check_protected_environments] do
    ActiveRecord::Tasks::DatabaseTasks.load_schema_current(:ruby, ENV['SCHEMA'])

  # desc 'Drops and recreates the database from db/schema.rb for the current environment and loads the seeds.'
  task :reset => [ 'db:drop', 'db:setup' ]

namespace :migrate do
  # desc  'Rollbacks the database one migration and re migrate up (options: STEP=x, VERSION=x).'
  task :redo => [:environment, :load_config] do
    if ENV['VERSION']

SQL Combine Two Columns in Select Statement

SELECT StaffId,(Title+''+FirstName+''+LastName) AS FullName 
FROM StaffInformation

Where do you write with in the brackets this will be appear in the one single column. Where do you want a dot into the middle of the Title and First Name write syntax below,

SELECT StaffId,(Title+'.'+FirstName+''+LastName) AS FullName 
FROM StaffInformation

These syntax works with MS SQL Server 2008 R2 Express Edition.

How to Code Double Quotes via HTML Codes

Google recommend that you don't use any of them, source.

There is no need to use entity references like &mdash, &rdquo, or &#x263a, assuming the same encoding (UTF-8) is used for files and editors as well as among teams.

Is there a reason you can't simply use "?

How to call getResources() from a class which has no context?

Example: Getting app_name string:

Resources.getSystem().getString( R.string.app_name )

How to clear Tkinter Canvas?

Every canvas item is an object that Tkinter keeps track of. If you are clearing the screen by just drawing a black rectangle, then you effectively have created a memory leak -- eventually your program will crash due to the millions of items that have been drawn.

To clear a canvas, use the delete method. Give it the special parameter "all" to delete all items on the canvas (the string "all"" is a special tag that represents all items on the canvas):


If you want to delete only certain items on the canvas (such as foreground objects, while leaving the background objects on the display) you can assign tags to each item. Then, instead of "all", you could supply the name of a tag.

If you're creating a game, you probably don't need to delete and recreate items. For example, if you have an object that is moving across the screen, you can use the move or coords method to move the item.

How can I split and parse a string in Python?

If it's always going to be an even LHS/RHS split, you can also use the partition method that's built into strings. It returns a 3-tuple as (LHS, separator, RHS) if the separator is found, and (original_string, '', '') if the separator wasn't present:

>>> "2.7.0_bf4fda703454".partition('_')
('2.7.0', '_', 'bf4fda703454')

>>> "shazam".partition("_")
('shazam', '', '')

SQL Server : Transpose rows to columns

I had a slightly different requirement, whereby I had to selectively transpose columns into rows.

The table had columns:

create table tbl (ID, PreviousX, PreviousY, CurrentX, CurrentY)

I needed columns for Previous and Current, and rows for X and Y. A Cartesian product generated on a static table worked nicely, eg:

    max(case when metric='X' then PreviousX
        case when metric='Y' then PreviousY end) as Previous,
    max(case when metric='X' then CurrentX
        case when metric='Y' then CurrentY end) as Current
from tbl inner join
    /* Cartesian product - transpose by repeating row and 
    picking appropriate metric column for period */
    ( VALUES (1, 'X'), (2, 'Y')) AS x (sort, metric) ON 1=1
group by ID
order by ID, sort

How to check if NSString begins with a certain character

Use characterAtIndex:. If the first character is an asterisk, use substringFromIndex: to get the string sans '*'.


I changed the package name while coding an update so that I could debug it on my device via Eclipse, without deleting the old version that was installed. Without reverting the package name I was using when trying to reinstall, I got this same error. Using the same package name the reinstall was successful.

Should I use window.navigate or document.location in JavaScript?

window.navigate not supported in some browser

In java script many ways are there for redirection, see the below code and explanation

window.location.href = "";
window.location = "";

window.location.href loads page from browser's cache and does not always send the request to the server. So, if you have an old version of the page available in the cache then it will redirect to there instead of loading a fresh page from the server.

window.location.assign() method for redirection if you want to allow the user to use the back button to go back to the original document.

window.location.replace() method if you want to want to redirect to a new page and don't allow the user to navigate to the original page using the back button.

How to find and return a duplicate value in array

Ruby Array objects have a great method, select.

select {|item| block } ? new_ary
select ? an_enumerator

The first form is what interests you here. It allows you to select objects which pass a test.

Ruby Array objects have another method, count.

count ? int
count(obj) ? int
count { |item| block } ? int

In this case, you are interested in duplicates (objects which appear more than once in the array). The appropriate test is a.count(obj) > 1.

If a = ["A", "B", "C", "B", "A"], then{|item| a.count(item) > 1}.uniq
=> ["A", "B"]

You state that you only want one object. So pick one.

-didSelectRowAtIndexPath: not being called

All good answers, but there's one more to look out for...

(Particularly when creating a UITableView programmatically)

Make sure the tableView can respond to selection by setting [tableView setAllowsSelection:YES]; or removing any line that sets it to NO.

Jquery how to find an Object by attribute in an Array

copied from polyfill Array.prototype.find code of Array.find, and added the array as first parameter.

you can pass the search term as predicate function

// Example_x000D_
var listOfObjects = [{key: "1", value: "one"}, {key: "2", value: "two"}]_x000D_
var result = findInArray(listOfObjects, function(element) {_x000D_
  return element.key == "1";_x000D_
// the function you want_x000D_
function findInArray(listOfObjects, predicate) {_x000D_
      if (listOfObjects == null) {_x000D_
        throw new TypeError('listOfObjects is null or not defined');_x000D_
      var o = Object(listOfObjects);_x000D_
      var len = o.length >>> 0;_x000D_
      if (typeof predicate !== 'function') {_x000D_
        throw new TypeError('predicate must be a function');_x000D_
      var thisArg = arguments[1];_x000D_
      var k = 0;_x000D_
      while (k < len) {_x000D_
        var kValue = o[k];_x000D_
        if (, kValue, k, o)) {_x000D_
          return kValue;_x000D_
      return undefined;_x000D_

Smart cast to 'Type' is impossible, because 'variable' is a mutable property that could have been changed by this time

1) Also you can use lateinit If you sure do your initialization later on onCreate() or elsewhere.

Use this

lateinit var left: Node

Instead of this

var left: Node? = null

2) And there is other way that use !! end of variable when you use it like this

queue.add(left!!) // add !!

Programmatically set the initial view controller using Storyboards

I don't think it's possible. Instead you can have one initial controller which will have segues to different view controllers. On startup, you can decide which segue to perform programmatically.

How to print object array in JavaScript?

you can use console.log() to print object


in case you have big object and want to print some of its values then you can use this custom function to print array in console

this.print = function (data,bpoint=0) {
    var c = 0;
    for(var k=0; k<data.length; k++){
        console.log(c+'  '+data[k]);
        if(k!=0 && bpoint === k)break;  


print(array);   // to print entire obj array


print(array,50);  // 50 value to print only 

Reading HTTP headers in a Spring REST controller

The error that you get does not seem to be related to the RequestHeader.

And you seem to be confusing Spring REST services with JAX-RS, your method signature should be something like:

@RequestMapping(produces = "application/json", method = RequestMethod.GET, value = "data")
public ResponseEntity<Data> getData(@RequestHeader(value="User-Agent") String userAgent, @RequestParam(value = "ID", defaultValue = "") String id) {
    // your code goes here

And your REST class should have annotations like:


Regarding the actual question, another way to get HTTP headers is to insert the HttpServletRequest into your method and then get the desired header from there.


@RequestMapping(produces = "application/json", method = RequestMethod.GET, value = "data")
public ResponseEntity<Data> getData(HttpServletRequest request, @RequestParam(value = "ID", defaultValue = "") String id) {
    String userAgent = request.getHeader("user-agent");

Don't worry about the injection of the HttpServletRequest because Spring does that magic for you ;)

How do I create a WPF Rounded Corner container?

If you're trying to put a button in a rounded-rectangle border, you should check out msdn's example. I found this by googling for images of the problem (instead of text). Their bulky outer rectangle is (thankfully) easy to remove.

Note that you will have to redefine the button's behavior (since you've changed the ControlTemplate). That is, you will need to define the button's behavior when clicked using a Trigger tag (Property="IsPressed" Value="true") in the ControlTemplate.Triggers tag. Hope this saves someone else the time I lost :)

Value of type 'T' cannot be converted to

If you're checking for explicit types, why are you declaring those variables as T's?

T HowToCast<T>(T t)
    if (typeof(T) == typeof(string))
        var newT1 = "some text";
        var newT2 = t;  //this builds but I'm not sure what it does under the hood.
        var newT3 = t.ToString();  //for sure the string you want.

    return t;

How to catch all exceptions in c# using try and catch?

    static void Main(string[] args)
        AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;

    static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
        throw new NotImplementedException();

Raise an error manually in T-SQL to jump to BEGIN CATCH block

THROW (Transact-SQL)

Raises an exception and transfers execution to a CATCH block of a TRY…CATCH construct in SQL Server 2017.

Please refer the below link

T-SQL Throw Exception

Pandas timeseries plot setting x-axis major and minor ticks and labels

Both pandas and matplotlib.dates use matplotlib.units for locating the ticks.

But while matplotlib.dates has convenient ways to set the ticks manually, pandas seems to have the focus on auto formatting so far (you can have a look at the code for date conversion and formatting in pandas).

So for the moment it seems more reasonable to use matplotlib.dates (as mentioned by @BrenBarn in his comment).

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt 
import matplotlib.dates as dates

idx = pd.date_range('2011-05-01', '2011-07-01')
s = pd.Series(np.random.randn(len(idx)), index=idx)

fig, ax = plt.subplots()
ax.plot_date(idx.to_pydatetime(), s, 'v-')
ax.xaxis.grid(True, which="minor")


(my locale is German, so that Tuesday [Tue] becomes Dienstag [Di])

Spring Security redirect to previous page after successful login

I want to extend Olcay's nice answer. His approach is good, your login page controller should be like this to put the referrer url into session:

@RequestMapping(value = "/login", method = RequestMethod.GET)
public String loginPage(HttpServletRequest request, Model model) {
    String referrer = request.getHeader("Referer");
    request.getSession().setAttribute("url_prior_login", referrer);
    // some other stuff
    return "login";

And you should extend SavedRequestAwareAuthenticationSuccessHandler and override its onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) method. Something like this:

public class MyCustomLoginSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler {
    public MyCustomLoginSuccessHandler(String defaultTargetUrl) {

    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws ServletException, IOException {
        HttpSession session = request.getSession();
        if (session != null) {
            String redirectUrl = (String) session.getAttribute("url_prior_login");
            if (redirectUrl != null) {
                // we do not forget to clean this attribute from session
                // then we redirect
                getRedirectStrategy().sendRedirect(request, response, redirectUrl);
            } else {
                super.onAuthenticationSuccess(request, response, authentication);
        } else {
            super.onAuthenticationSuccess(request, response, authentication);

Then, in your spring configuration, you should define this custom class as a bean and use it on your security configuration. If you are using annotation config, it should look like this (the class you extend from WebSecurityConfigurerAdapter):

public AuthenticationSuccessHandler successHandler() {
    return new MyCustomLoginSuccessHandler("/yourdefaultsuccessurl");

In configure method:

protected void configure(HttpSecurity http) throws Exception {
            // bla bla
            // etc etc

Is there Unicode glyph Symbol to represent "Search"

You can simply add this CSS to your header

<link href='' rel='stylesheet' type='text/css'>

next add this code in place where you want to display a glyph symbol.

<div class="fa fa-search"></div> <!-- smaller -->
<div class="fa fa-search fa-2x"></div> <!-- bigger -->

Have fun.

Save range to variable

In your own answer, you effectively do this:

Dim SrcRange As Range ' you should always declare things explicitly
Set SrcRange = Sheets("Src").Range("A2:A9")
SrcRange.Copy Destination:=Sheets("Dest").Range("A2")

You're not really "extracting" the range to a variable, you're setting a reference to the range.

In many situations, this can be more efficient as well as more flexible:

Dim Src As Variant
Src= Sheets("Src").Range("A2:A9").Value 'Read range to array
'Here you can add code to manipulate your Src array
Sheets("Dest").Range("A2:A9").Value = Src 'Write array back to another range

jquery $('.class').each() how many items?

Use the .length property. It is not a function.

alert($('.class').length); // alerts a nonnegative number 

Check if character is number?

square = function(a) {
    if ((a * 0) == 0) {
        return a*a;
    } else {
        return "Enter a valid number.";


Linux: copy and create destination dir if it does not exist

Copy from source to an non existing path

mkdir –p /destination && cp –r /source/ $_

NOTE: this command copies all the files

cp –r for copying all folders and its content

$_ work as destination which is created in last command

Return index of greatest value in an array

function findIndicesOf(haystack, needle)
    var indices = [];

    var j = 0;
    for (var i = 0; i < haystack.length; ++i) {
        if (haystack[i] == needle)
            indices[j++] = i;
    return indices;

pass array to haystack and Math.max(...array) to needle. This will give all max elements of the array, and it is more extensible (for example, you also need to find min values)

how to get param in method post spring mvc?

When I want to get all the POST params I am using the code below,

@RequestMapping(value = "/", method = RequestMethod.POST)
public ViewForResponseClass update(@RequestBody AClass anObject) {
    // Source..

I am using the @RequestBody annotation for post/put/delete http requests instead of the @RequestParam which reads the GET parameters.

Java Long primitive type maximum limit

It will overflow and wrap around to Long.MIN_VALUE.

Its not too likely though. Even if you increment 1,000,000 times per second it will take about 300,000 years to overflow.

Stop jQuery .load response from being cached

 * Use this function as jQuery "load" to disable request caching in IE
 * Example: $('selector').loadWithoutCache('url', function(){ //success function callback... });
$.fn.loadWithoutCache = function (){
 var elem = $(this);
 var func = arguments[1];
     url: arguments[0],
     cache: false,
     dataType: "html",
     success: function(data, textStatus, XMLHttpRequest) {
   if(func != undefined){
    func(data, textStatus, XMLHttpRequest);
 return elem;

How do I debug "Error: spawn ENOENT" on node.js?

I got the same error for windows 8.The issue is because of an environment variable of your system path is missing . Add "C:\Windows\System32\" value to your system PATH variable.

IOS: verify if a point is inside a rect

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
            UITouch *touch = [[event allTouches] anyObject];
            CGPoint touchLocation = [touch locationInView:self.view];
            CGRect rect1 = CGRectMake(vwTable.frame.origin.x, 
            vwTable.frame.origin.y, vwTable.frame.size.width, 
            if (CGRectContainsPoint(rect1,touchLocation))

Confirm Password with jQuery Validate

I'm implementing it in Play Framework and for me it worked like this:

1) Notice that I used data-rule-equalTo in input tag for the id inputPassword1. The code section of userform in my Modal:

<div class="form-group">
    <label for="pass1">@Messages("authentication.password")</label>
    <input class="form-control required" id="inputPassword1" placeholder="@Messages("authentication.password")" type="password" name="password" maxlength=10 minlength=5>
<div class="form-group">
    <label for="pass2">@Messages("authentication.password2")</label>
    <input class="form-control required" data-rule-equalTo="#inputPassword1" id="inputPassword2" placeholder="@Messages("authentication.password")" type="password" name="password2">

2)Since I used validator within a Modal

$(document).on("click", ".createUserModal", function () {
           rules: {
               firstName: "required",
               lastName: "required",
               nationalId: {
                   required: true,
               email: {
                   required: true,
                   email: true
               optradio: "required",
               password :{
                   required: true,
                   minlength: 5
               password2: {
                   required: true
           highlight: function (element) {
           unhighlight: function (element) {
           onsubmit: true


Hope it helps someone :).

How to use Sublime over SSH

I've been working on a project called GiySync. It still needs some work, but it's open source and I've been using it every day for a couple of years. I'm also working on a native OS X version I've called GitSyncApp

Right now it's OS X only but it should be easy to add support for Linux, and possibly Windows too.

It works by watching file system events and it uses to git to sync a project folder on your local machine and a server.

I tried the other solutions like osx fuse, Expand Drive, Transmit, several solutions that used rsync, etc. They all work 'OK' for small projects, but if you're working with a lot of code they did not work for me.

A lot of the file system options do caching to improve performance, which is fine, until it's not. Like if you're working with other people and someone else changes the files on the server.

I also ran into issues if I was on a flaky or slow network where I'd end up with empty files. Or file that didn't sync, then the caching got weird; hopefully you committed recently. Using git solves this problem because it checks each commit's integrity.

Two bonus features:

  1. You end up with a commit for every save. It's not super useful but if you ever have to go back in time you can.
  2. It works with any text editor.

Open fancybox from function

What you need is:

${ .... });

See the "API methods" section at the bottom of here:

What is the mouse down selector in CSS?

I figured out that this behaves like a mousedown event:

button:active:hover {}

Errors: "INSERT EXEC statement cannot be nested." and "Cannot use the ROLLBACK statement within an INSERT-EXEC statement." How to solve this?

I encountered this issue when trying to import the results of a Stored Proc into a temp table, and that Stored Proc inserted into a temp table as part of its own operation. The issue being that SQL Server does not allow the same process to write to two different temp tables at the same time.

The accepted OPENROWSET answer works fine, but I needed to avoid using any Dynamic SQL or an external OLE provider in my process, so I went a different route.

One easy workaround I found was to change the temporary table in my stored procedure to a table variable. It works exactly the same as it did with a temp table, but no longer conflicts with my other temp table insert.

Just to head off the comment I know that a few of you are about to write, warning me off Table Variables as performance killers... All I can say to you is that in 2020 it pays dividends not to be afraid of Table Variables. If this was 2008 and my Database was hosted on a server with 16GB RAM and running off 5400RPM HDDs, I might agree with you. But it's 2020 and I have an SSD array as my primary storage and hundreds of gigs of RAM. I could load my entire company's database to a table variable and still have plenty of RAM to spare.

Table Variables are back on the menu!

Retrieve WordPress root directory path?

   Please try this for get the url of root file.

First Way:

 $path = get_home_path();
   print "Path: ".$path; 
// Return "Path: /var/www/htdocs/" or

// "Path: /var/www/htdocs/wordpress/" if it is subfolder

Second Way:

And you can also use 


this constant is define in wordpress config file.

Checking images for similarity with OpenCV

Sam's solution should be sufficient. I've used combination of both histogram difference and template matching because not one method was working for me 100% of the times. I've given less importance to histogram method though. Here's how I've implemented in simple python script.

import cv2

class CompareImage(object):

    def __init__(self, image_1_path, image_2_path):
        self.minimum_commutative_image_diff = 1
        self.image_1_path = image_1_path
        self.image_2_path = image_2_path

    def compare_image(self):
        image_1 = cv2.imread(self.image_1_path, 0)
        image_2 = cv2.imread(self.image_2_path, 0)
        commutative_image_diff = self.get_image_difference(image_1, image_2)

        if commutative_image_diff < self.minimum_commutative_image_diff:
            print "Matched"
            return commutative_image_diff
        return 10000 //random failure value

    def get_image_difference(image_1, image_2):
        first_image_hist = cv2.calcHist([image_1], [0], None, [256], [0, 256])
        second_image_hist = cv2.calcHist([image_2], [0], None, [256], [0, 256])

        img_hist_diff = cv2.compareHist(first_image_hist, second_image_hist, cv2.HISTCMP_BHATTACHARYYA)
        img_template_probability_match = cv2.matchTemplate(first_image_hist, second_image_hist, cv2.TM_CCOEFF_NORMED)[0][0]
        img_template_diff = 1 - img_template_probability_match

        # taking only 10% of histogram diff, since it's less accurate than template method
        commutative_image_diff = (img_hist_diff / 10) + img_template_diff
        return commutative_image_diff

    if __name__ == '__main__':
        compare_image = CompareImage('image1/path', 'image2/path')
        image_difference = compare_image.compare_image()
        print image_difference

How do I call a SQL Server stored procedure from PowerShell?

Here is a function that I use (slightly redacted). It allows input and output parameters. I only have uniqueidentifier and varchar types implemented, but any other types are easy to add. If you use parameterized stored procedures (or just parameterized sql...this code is easily adapted to that), this will make your life a lot easier.

To call the function, you need a connection to the SQL server (say $conn),

$res=exec-storedprocedure -storedProcName 'stp_myProc' -parameters @{Param1="Hello";Param2=50} -outparams @{ID="uniqueidentifier"} $conn

retrieve proc output from returned object

$ #dataset containing the datatables returned by selects

$res.outputparams.ID #output parameter ID (uniqueidentifier)

The function:

function exec-storedprocedure($storedProcName,  
        [hashtable] $parameters=@{},
        [hashtable] $outparams=@{},

        function put-outputparameters($cmd, $outparams){
            foreach($outp in $outparams.Keys){
                $cmd.Parameters.Add("@$outp", (get-paramtype $outparams[$outp])).Direction=[System.Data.ParameterDirection]::Output
        function get-outputparameters($cmd,$outparams){
            foreach($p in $cmd.Parameters){
                if ($p.Direction -eq [System.Data.ParameterDirection]::Output){

        function get-paramtype($typename,[switch]$help){
            switch ($typename){
                'uniqueidentifier' {[System.Data.SqlDbType]::UniqueIdentifier}
                'int' {[System.Data.SqlDbType]::Int}
                'xml' {[System.Data.SqlDbType]::Xml}
                'nvarchar' {[System.Data.SqlDbType]::NVarchar}
                default {[System.Data.SqlDbType]::Varchar}
        if ($help){
            $msg = @"
    Execute a sql statement.  Parameters are allowed.  
    Input parameters should be a dictionary of parameter names and values.
    Output parameters should be a dictionary of parameter names and types.
    Return value will usually be a list of datarows. 

    Usage: exec-query sql [inputparameters] [outputparameters] [conn] [-help]
            Write-Host $msg
        $close=($conn.State -eq [System.Data.ConnectionState]'Closed')
        if ($close) {

        $cmd=new-object system.Data.SqlClient.SqlCommand($sql,$conn)
        foreach($p in $parameters.Keys){

        put-outputparameters $cmd $outparams
        $ds=New-Object system.Data.DataSet
        $da=New-Object system.Data.SqlClient.SqlDataAdapter($cmd)
        if ($close) {
        get-outputparameters $cmd $outparams

        return @{data=$ds;outputparams=$outparams}

How to restore PostgreSQL dump file into Postgres databases?

The problem with your attempt at the psql command line is the direction of the slashes:

newTestDB-# /i E:\db-rbl-restore-20120511_Dump-20120514.sql   # incorrect
newTestDB-# \i E:/db-rbl-restore-20120511_Dump-20120514.sql   # correct

To be clear, psql commands start with a backslash, so you should have put \i instead. What happened as a result of your typo is that psql ignored everything until finding the first \, which happened to be followed by db, and \db happens to be the psql command for listing table spaces, hence why the output was a List of tablespaces. It was not a listing of "default tables of PostgreSQL" as you said.

Further, it seems that psql expects the filepath argument to delimit directories using the forward slash regardless of OS (thus on Windows this would be counter-intuitive).

It is worth noting that your attempt at "elevating permissions" had no relation to the outcome of the command you attempted to execute. Also, you did not say what caused the supposed "Permission Denied" error.

Finally, the extension on the dump file does not matter, in fact you don't even need an extension. Indeed, pgAdmin suggests a .backup extension when selecting a backup filename, but you can actually make it whatever you want, again, including having no extension at all. The problem is that pgAdmin seems to only allow a "Restore" of "Custom or tar" or "Directory" dumps (at least this is the case in the MAC OS X version of the app), so just use the psql \i command as shown above.

Resize a large bitmap file to scaled output file on Android

After reading these answers and android documentation here's the code to resize bitmap without loading it into memory:

public Bitmap getResizedBitmap(int targetW, int targetH,  String imagePath) {

    // Get the dimensions of the bitmap
    BitmapFactory.Options bmOptions = new BitmapFactory.Options();
    //inJustDecodeBounds = true <-- will not load the bitmap into memory
    bmOptions.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(imagePath, bmOptions);
    int photoW = bmOptions.outWidth;
    int photoH = bmOptions.outHeight;

    // Determine how much to scale down the image
    int scaleFactor = Math.min(photoW/targetW, photoH/targetH);

    // Decode the image file into a Bitmap sized to fill the View
    bmOptions.inJustDecodeBounds = false;
    bmOptions.inSampleSize = scaleFactor;
    bmOptions.inPurgeable = true;

    Bitmap bitmap = BitmapFactory.decodeFile(imagePath, bmOptions);

Calling pylab.savefig without display in ipython

We don't need to plt.ioff() or (if we use %matplotlib inline). You can test above code without plt.ioff(). plt.close() has the essential role. Try this one:

%matplotlib inline
import pylab as plt

# It doesn't matter you add line below. You can even replace it by 'plt.ion()', but you will see no changes.
## plt.ioff()

# Create a new figure, plot into it, then close it so it never gets displayed
fig = plt.figure()

# Create a new figure, plot into it, then don't close it so it does get displayed
fig2 = plt.figure()

If you run this code in iPython, it will display a second plot, and if you add plt.close(fig2) to the end of it, you will see nothing.

In conclusion, if you close figure by plt.close(fig), it won't be displayed.

How to center buttons in Twitter Bootstrap 3?

I tried the following code and it worked for me.

<button class="btn btn-default center-block" type="submit">Button</button>

The button control is in a div and using center-block class of bootstrap helped me to align the button to the center of div

Check the link where you will find the center-block class

Get folder name of the file in Python

you can use pathlib

from pathlib import Path

The output of the above was this:


Oracle: how to set user password unexpire?

While applying the new profile to the user,you should also check for resource limits are "turned on" for the database as a whole i.e.RESOURCE_LIMIT = TRUE

Let check the parameter value.
If in Case it is :

SQL> show parameter resource_limit
NAME                                 TYPE        VALUE
------------------------------------ ----------- ---------
resource_limit                       boolean     FALSE
Its mean resource limit is off,we ist have to enable it. 

Use the ALTER SYSTEM statement to turn on resource limits. 

System altered.

How to create a showdown.js markdown extension

In your last block you have a comma after 'lang', followed immediately with a function. This is not valid json.


It appears that the readme was incorrect. I had to to pass an array with the string 'twitter'.

var converter = new Showdown.converter({extensions: ['twitter']}); converter.makeHtml('whatever @meandave2020'); // output "<p>whatever <a href="">@meandave2020</a></p>" 

I submitted a pull request to update this.

Sorting a vector in descending order

According to my machine, sorting a long long vector of [1..3000000] using the first method takes around 4 seconds, while using the second takes about twice the time. That says something, obviously, but I don't understand why either. Just think this would be helpful.

Same thing reported here.

As said by Xeo, with -O3 they use about the same time to finish.

Python: Pandas Dataframe how to multiply entire column with a scalar

A bit old, but I was still getting the same SettingWithCopyWarning. Here was my solution:

df.loc[:, 'quantity'] = df['quantity'] * -1

Class JavaLaunchHelper is implemented in both. One of the two will be used. Which one is undefined

From what I've found online, this is a bug introduced in JDK 1.7.0_45. It appears to also be present in JDK 1.7.0_60. A bug report on Oracle's website states that, while there was a fix, it was removed before the JDK was released. I do not know why the fix was removed, but it confirms what we've already suspected -- the JDK is still broken.

The bug report claims that the error is benign and should not cause any run-time problems, though one of the comments disagrees with that. In my own experience, I have been able to work without any problems using JDK 1.7.0_60 despite seeing the message.

If this issue is causing serious problems, here are a few things I would suggest:

  • Revert back to JDK 1.7.0_25 until a fix is added to the JDK.

  • Keep an eye on the bug report so that you are aware of any work being done on this issue. Maybe even add your own comment so Oracle is aware of the severity of the issue.

  • Try the JDK early releases as they come out. One of them might fix your problem.

Instructions for installing the JDK on Mac OS X are available at JDK 7 Installation for Mac OS X. It also contains instructions for removing the JDK.

position: fixed doesn't work on iPad and iPhone

using jquery i am able to come up with this. it doesnt scroll smooth, but it does the trick. you can scroll down, and the fixed div pops up on top.


<style type="text/css">
    .btn_cardDetailsPg {height:5px !important;margin-top:-20px;}
    html, body {overflow-x:hidden;overflow-y:auto;}
    #lockDiv {
  background-color: #fff;
  color: #000;
  -moz-box-shadow: 0px 4px 2px 2px #ccc;-webkit-box-shadow: 0px 4px 2px 2px #ccc;box-shadow:0px 4px 2px 2px #ccc;
#lockDiv.stick {
  position: fixed;
  top: 0;
  z-index: 10000;


<div id="lockSticky"></div>
<div id="lockDiv">fooo</div>


<script type="text/javascript">
    function sticky_relocate() {
        var window_top = $(window).scrollTop();
        var div_top = $('#lockSticky').offset().top;
        if (window_top > div_top)
    $(function() {

Finally we want to determine if the ipod touch in landscape or portrait mode to display accordingly

<script type="text/javascript">
    if (navigator.userAgent.match(/like Mac OS X/i)) {
        window.onscroll = function() {

        if (window.innerWidth > window.innerHeight) {
            //alert("landscape [ ]");
            document.getElementById('lockDiv') =
            (window.pageYOffset + window.innerHeight - 268) + 'px';

        if (window.innerHeight > window.innerWidth) {
            //alert("portrait ||");
            document.getElementById('lockDiv') =
            (window.pageYOffset + window.innerHeight - 418) + 'px';

Is there a way to suppress JSHint warning for one given line?

As you can see in the documentation of JSHint you can change options per function or per file. In your case just place a comment in your file or even more local just in the function that uses eval:

/*jshint evil:true */

function helloEval(str) {
    /*jshint evil:true */

Extract column values of Dataframe as List in Apache Spark

sqlContext.sql(" select filename from tempTable") => r(0)).collect.toList.foreach(out_streamfn.println) //remove brackets

it works perfectly

Generate getters and setters in NetBeans

Position the cursor inside the class, then press ALT + Ins and select Getters and Setters from the contextual menu.

Parsing XML with namespace in Python via 'ElementTree'

ElementTree is not too smart about namespaces. You need to give the .find(), findall() and iterfind() methods an explicit namespace dictionary. This is not documented very well:

namespaces = {'owl': ''} # add more as needed

root.findall('owl:Class', namespaces)

Prefixes are only looked up in the namespaces parameter you pass in. This means you can use any namespace prefix you like; the API splits off the owl: part, looks up the corresponding namespace URL in the namespaces dictionary, then changes the search to look for the XPath expression {}Class instead. You can use the same syntax yourself too of course:


If you can switch to the lxml library things are better; that library supports the same ElementTree API, but collects namespaces for you in a .nsmap attribute on elements.

Actionbar notification count icon (badge) like Google has

Just to add. If someone wants to implement a filled circle bubble, heres the code (name it bage_circle.xml):

<shape xmlns:android=""

        android:color="#FFF" />



You may have to adjust the thickness according to your need.

enter image description here

EDIT: Here's the layout for button (name it badge_layout.xml):

<RelativeLayout xmlns:android=""



In Menu create item:


In onCreateOptionsMenu get reference to the Menu item:

    itemMessages = menu.findItem(;

    badgeLayout = (RelativeLayout) itemMessages.getActionView();
    itemMessagesBadgeTextView = (TextView) badgeLayout.findViewById(;
    itemMessagesBadgeTextView.setVisibility(View.GONE); // initially hidden

    iconButtonMessages = (IconButton) badgeLayout.findViewById(;

    iconButtonMessages.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            if (HJSession.getSession().getSessionId() != null) {

                Intent intent = new Intent(getThis(), HJActivityMessagesContexts.class);
                startActivityForResult(intent, HJRequestCodes.kHJRequestCodeActivityMessages.ordinal());
            } else {

After receiving notification for messages, set the count:

itemMessagesBadgeTextView.setText("" + count);

This code uses Iconify-fontawesome.

compile 'com.joanzapata.iconify:android-iconify-fontawesome:2.1.+'

Send raw ZPL to Zebra printer via USB

ZPL is the correct way to go. In most cases it is correct to use a driver that abstracts to GDI commands; however Zebra label printers are a special case. The best way to print to a Zebra printer is to generate ZPL directly. Note that the actual printer driver for a Zebra printer is a "plain text" printer - there is not a "driver" that could be updated or changed in the sense we think of most printers having drivers. It's just a driver in the absolute minimalist sense.

How to dynamically change header based on AngularJS partial view?

You could define controller at the <html> level.

 <html ng-app="app" ng-controller="titleCtrl">
     <title>{{ Page.title() }}</title>

You create service: Page and modify from controllers.

myModule.factory('Page', function() {
   var title = 'default';
   return {
     title: function() { return title; },
     setTitle: function(newTitle) { title = newTitle }

Inject Page and Call 'Page.setTitle()' from controllers.

Here is the concrete example:

How can I get the nth character of a string?

Array notation and pointer arithmetic can be used interchangeably in C/C++ (this is not true for ALL the cases but by the time you get there, you will find the cases yourself). So although str is a pointer, you can use it as if it were an array like so:

char char_E = str[1];
char char_L1 = str[2];
char char_O = str[4];

...and so on. What you could also do is "add" 1 to the value of the pointer to a character str which will then point to the second character in the string. Then you can simply do:

str = str + 1; // makes it point to 'E' now
char myChar =  *str;

I hope this helps.

Restricting input to textbox: allowing only numbers and decimal point

Extending the @rebisco's answer. this below code will allow only numbers and single '.'(period) in the text box.

function isNumberKey(evt) {
        var charCode = (evt.which) ? evt.which : event.keyCode;
        if (charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57)) {
            return false;
        } else {
            // If the number field already has . then don't allow to enter . again.
            if (\./) > -1 && charCode == 46) {
                return false;
            return true;

SQL query question: SELECT ... NOT IN

It's always dangerous to have NULL in the IN list - it often behaves as expected for the IN but not for the NOT IN:

IF 1 NOT IN (1, 2, 3, NULL) PRINT '1 NOT IN (1, 2, 3, NULL)'
IF 1 NOT IN (2, 3, NULL) PRINT '1 NOT IN (2, 3, NULL)'
IF 1 NOT IN (2, 3) PRINT '1 NOT IN (2, 3)' -- Prints
IF 1 IN (1, 2, 3, NULL) PRINT '1 IN (1, 2, 3, NULL)' -- Prints
IF 1 IN (2, 3, NULL) PRINT '1 IN (2, 3, NULL)'
IF 1 IN (2, 3) PRINT '1 IN (2, 3)'

Converting a JS object to an array using jQuery

You can create a simple function to do the conversion from object to array, something like this can do the job for you using pure javascript:

var objectToArray = function(obj) {
  var arr = [];
  if ('object' !== typeof obj || 'undefined' === typeof obj || Array.isArray(obj)) {
    return obj;
  } else {
  return arr;

or this one:

var objectToArray = function(obj) {
  var arr =[];
  for(let o in obj) {
    if (obj.hasOwnProperty(o)) {
  return arr;

and call and use the function as below:

var obj = {1:'a', 2:'b', 3:'c', 4:'d', 5:'e'};
objectToArray(obj); // return ["a", "b", "c", "d", "e"]

Also in the future we will have something called Object.values(obj), similar to Object.keys(obj) which will return all properties for you as an array, but not supported in many browsers yet...

What's the difference between isset() and array_key_exists()?

Answer to an old question as no answer here seem to address the 'warning' problem (explanation follows)

Basically, in this case of checking if a key exists in an array, isset

  • tells if the expression (array) is defined, and the key is set
  • no warning or error if the var is not defined, not an array ...
  • but returns false if the value for that key is null

and array_key_exists

  • tells if a key exists in an array as the name implies
  • but gives a warning if the array parameter is not an array

So how do we check if a key exists which value may be null in a variable

  • that may or may not be an array
  • (or similarly is a multidimensional array for which the key check happens at dim 2 and dim 1 value may not be an array for the 1st dim (etc...))

without getting a warning, without missing the existing key when its value is null (what were the PHP devs thinking would also be an interesting question, but certainly not relevant on SO). And of course we don't want to use @

isset($var[$key]);            // silent but misses null values
array_key_exists($key, $var); // works but warning if $var not defined/array

It seems is_array should be involved in the equation, but it gives a warning if $var is not defined, so that could be a solution:

if (isset($var[$key]) || 
    isset($var) && is_array($var) && array_key_exists($key, $var)) ...

which is likely to be faster if the tests are mainly on non-null values. Otherwise for an array with mostly null values

if (isset($var) && is_array($var) && array_key_exists($key, $var)) ...

will do the work.

DataGridView - Focus a specific cell

Set the Current Cell like:

DataGridView1.CurrentCell = DataGridView1.Rows[rowindex].Cells[columnindex]


DataGridView1.CurrentCell = DataGridView1.Item("ColumnName", 5)

and you can directly focus with Editing by:


Invalid self signed SSL cert - "Subject Alternative Name Missing"

To fix this, you need to supply an extra parameter to openssl when you're creating the cert, basically

-sha256 -extfile v3.ext

where v3.ext is a file like so, with %%DOMAIN%% replaced with the same name you use as your Common Name. More info here and over here. Note that typically you'd set the Common Name and %%DOMAIN%% to the domain you're trying to generate a cert for. So if it was, then you'd use that for both.


keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names

DNS.1 = %%DOMAIN%%

Note: Scripts that address this issue, and create fully trusted ssl certs for use in Chrome, Safari and from Java clients can be found here

Another note: If all you're trying to do is stop chrome from throwing errors when viewing a self signed certificate, you can can tell Chrome to ignore all SSL errors for ALL sites by starting it with a special command line option, as detailed here on SuperUser

Expression ___ has changed after it was checked

As stated by drewmoore, the proper solution in this case is to manually trigger change detection for the current component. This is done using the detectChanges() method of the ChangeDetectorRef object (imported from angular2/core), or its markForCheck() method, which also makes any parent components update. Relevant example:

import { Component, ChangeDetectorRef, AfterViewInit } from 'angular2/core'

  selector: 'my-app',
  template: `<div>I'm {{message}} </div>`,
export class App implements AfterViewInit {
  message: string = 'loading :(';

  constructor(private cdr: ChangeDetectorRef) {}

  ngAfterViewInit() {
    this.message = 'all done loading :)'


Here are also Plunkers demonstrating the ngOnInit, setTimeout, and enableProdMode approaches just in case.

AND/OR in Python?

if input == 'a':
    for char in 'abc':
        if char in some_list:

Determine if $.ajax error is a timeout

If your error event handler takes the three arguments (xmlhttprequest, textstatus, and message) when a timeout happens, the status arg will be 'timeout'.

Per the jQuery documentation:

Possible values for the second argument (besides null) are "timeout", "error", "notmodified" and "parsererror".

You can handle your error accordingly then.

I created this fiddle that demonstrates this.

    url: "/ajax_json_echo/",
    type: "GET",
    dataType: "json",
    timeout: 1000,
    success: function(response) { alert(response); },
    error: function(xmlhttprequest, textstatus, message) {
        if(textstatus==="timeout") {
            alert("got timeout");
        } else {

With jsFiddle, you can test ajax calls -- it will wait 2 seconds before responding. I put the timeout setting at 1 second, so it should error out and pass back a textstatus of 'timeout' to the error handler.

Hope this helps!

In Excel how to get the left 5 characters of each cell in a specified column and put them into a new column

1) Put =Left(E1,5) in F1

2) Copy F1, then select entire F column and paste.

How to view file diff in git before commit

Did you try -v (or --verbose) option for git commit? It adds the diff of the commit in the message editor.

How do you reset the stored credentials in 'git credential-osxkeychain'?

I'm not sure how to erase through the command line, but it's fairly easily to do it through the Keychain Access app. Just go to Applications -> Utilties -> Keychain Access, then enter "". You can either delete the invalid item or update the password from with the app.

show validation error messages on submit in angularjs

// This worked for me.
<form  name="myForm" class="css-form" novalidate ng-submit="Save(myForm.$invalid)">
<input type="text" name="uName" ng-model="User.Name" required/>
<span ng-show="User.submitted && myForm.uName.$error.required">Name is required.</span>
<input ng-click="User.submitted=true" ng-disabled="User.submitted && tForm.$invalid" type="submit" value="Save" />
// in controller
if(invalid) return;
// save form

PHP: Calling another class' method


class ClassA
   private $name = 'John';

   function getName()
     return $this->name;

   include ("file1.php");

   class ClassB

     function __construct()

     function callA()
       $classA = new ClassA();
       $name = $classA->getName();
       echo $name;    //Prints John

   $classb = new ClassB();

Change value of input onchange?

for jQuery we can use below:

by input name:

$('input[name="textboxname"]').val('some value');

by input class:

$('input[type=text].textboxclass').val('some value');

by input id:

$('#textboxid').val('some value');

CSS media queries for screen sizes

For all smartphones and large screens use this format of media query

/* Smartphones (portrait and landscape) ----------- */

@media only screen and (min-device-width : 320px) and (max-device-width : 480px) {
/* Styles */

/* Smartphones (landscape) ----------- */

@media only screen and (min-width : 321px) {
/* Styles */

/* Smartphones (portrait) ----------- */

@media only screen and (max-width : 320px) {
/* Styles */

/* iPads (portrait and landscape) ----------- */

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) {
/* Styles */

/* iPads (landscape) ----------- */

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) {
/* Styles */

/* iPads (portrait) ----------- */

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) {
/* Styles */

iPad 3

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */

/* Desktops and laptops ----------- */

@media only screen  and (min-width : 1224px) {
/* Styles */

/* Large screens ----------- */
@media only screen  and (min-width : 1824px) {
/* Styles */

/* iPhone 4 ----------- */

@media only screen and (min-device-width : 320px) and (max-device-width : 480px) and (orientation : landscape) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */

@media only screen and (min-device-width : 320px) and (max-device-width : 480px) and (orientation : portrait) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */

/* iPhone 5 ----------- */

@media only screen and (min-device-width: 320px) and (max-device-height: 568px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */

@media only screen and (min-device-width: 320px) and (max-device-height: 568px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */

/* iPhone 6 ----------- */

@media only screen and (min-device-width: 375px) and (max-device-height: 667px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */

@media only screen and (min-device-width: 375px) and (max-device-height: 667px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */

/* iPhone 6+ ----------- */

@media only screen and (min-device-width: 414px) and (max-device-height: 736px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */

@media only screen and (min-device-width: 414px) and (max-device-height: 736px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */

/* Samsung Galaxy S3 ----------- */

@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 2){
/* Styles */

@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 2){
/* Styles */

/* Samsung Galaxy S4 ----------- */
@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 3){
/* Styles */

@media only screen and (min-device-width: 320px) and (max-device-height: 640px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 3){
/* Styles */

/* Samsung Galaxy S5 ----------- */

@media only screen and (min-device-width: 360px) and (max-device-height: 640px) and (orientation : landscape) and (-webkit-device-pixel-ratio: 3){
/* Styles */

@media only screen and (min-device-width: 360px) and (max-device-height: 640px) and (orientation : portrait) and (-webkit-device-pixel-ratio: 3){
/* Styles */

How to use curl to get a GET request exactly same as using Chrome?

Check the HTTP headers that chrome is sending with the request (Using browser extension or proxy) then try sending the same headers with CURL - Possibly one at a time till you figure out which header(s) makes the request work.

curl -A [user-agent] -H [headers] ""

Visual Studio 2015 Update 3 Offline Installer (ISO)

Its better to go through the Recommended Microsoft's Way to download Visual Studio 2015 Update 3 ISO (Community Edition).

The instructions below will help you to download any version of Visual Studio or even SQL Server etc provided by Microsoft in an easy to remember way. Though I recommend people using VS 2017 as there are not much big differences between 2015 and 2017.

Please follow the steps as mentioned below.

  1. Visit the standard URL

  2. Scroll down and click on encircled below as shown in snapshot down Snapshot showing how to download older visual studio versions

  3. After that join Visual Studio Web Dev essentials for Free as shown below. Try loggin in with your microsoft account and see that if it works otherwise click on Joinenter image description here

  4. Click on Downloads ICON on the encircled as shown below. enter image description here

  5. Now Type Visual Studio Community in the Search Box as shown below in the snapshot enter image description here.
  6. From the drowdown select the DVD type and start downloading enter image description here

How can I list all the deleted files in a Git repository?

git log --diff-filter=D --summary

See Find and restore a deleted file in a Git repository

If you don't want all the information about which commit they were removed in, you can just add a grep delete in there.

git log --diff-filter=D --summary | grep delete

how to know status of currently running jobs

I found a better answer by Kenneth Fisher. The following query returns only currently running jobs:

    ja.job_id, AS job_name,
    ISNULL(last_executed_step_id,0)+1 AS current_executed_step_id,
FROM msdb.dbo.sysjobactivity ja 
LEFT JOIN msdb.dbo.sysjobhistory jh ON ja.job_history_id = jh.instance_id
JOIN msdb.dbo.sysjobs j ON ja.job_id = j.job_id
JOIN msdb.dbo.sysjobsteps js
    ON ja.job_id = js.job_id
    AND ISNULL(ja.last_executed_step_id,0)+1 = js.step_id
  ja.session_id = (
    SELECT TOP 1 session_id FROM msdb.dbo.syssessions ORDER BY agent_start_date DESC
AND start_execution_date is not null
AND stop_execution_date is null;

You can get more information about a job by adding more columns from msdb.dbo.sysjobactivity table in select clause.

QLabel: set color of text and background

I add this answer because I think it could be useful to anybody.

I step into the problem of setting RGBA colors (that is, RGB color with an Alpha value for transparency) for color display labels in my painting application.

As I came across the first answer, I was unable to set an RGBA color. I have also tried things like:

myLabel.setStyleSheet("QLabel { background-color : %s"

where color is an RGBA color.

So, my dirty solution was to extend QLabel and override paintEvent() method filling its bounding rect.

Today, I've open up the qt-assistant and read the style reference properties list. Affortunately, it has an example that states the following:

QLineEdit { background-color: rgb(255, 0, 0) }

Thats open up my mind in doing something like the code below, as an example:

myLabel= QLabel()
myLabel.setAutoFillBackground(True) # This is important!!
color  = QtGui.QColor(233, 10, 150)
alpha  = 140
values = "{r}, {g}, {b}, {a}".format(r =,
                                     g =,
                                     b =,
                                     a = alpha
myLabel.setStyleSheet("QLabel { background-color: rgba("+values+"); }")

Note that setAutoFillBackground() set in False will not make it work.


XPath: select text node

Having the following XML:


How do I select either the first or the second text node via XPath?



This selects all text-node children of the top element (named "node") of the XML document.


This selects the first text-node child of the top element (named "node") of the XML document.


This selects the second text-node child of the top element (named "node") of the XML document.


This selects the someInteger-th text-node child of the top element (named "node") of the XML document. It is equivalent to the following XPath expression:

/node/text()[position() = someInteger]

Java String.split() Regex

You could also do something like:

String str = "a + b - c * d / e < f > g >= h <= i == j";
String[] arr = str.split("(?<=\\G(\\w+(?!\\w+)|==|<=|>=|\\+|/|\\*|-|(<|>)(?!=)))\\s*");

It handles white spaces and words of variable length and produces the array:

[a, +, b, -, c, *, d, /, e, <, f, >, g, >=, h, <=, i, ==, j]

Qt Creator color scheme

I found a way to change the Application Output theme and everything that can't be edited from .css.

If you use osX:

  1. Navigate to your Qt install directory.
  2. Right click Qt Creator application and select "Show Package Contents"
  3. Copy the following file to your desktop> Contents/Resources/themes/dark.creatortheme or /default.creatortheme. Depending on if you are using dark theme or default theme.
  4. Edit the file in text editor.
  5. Under [Palette], there is a line that says error=ffff0000.
  6. Set a new color, save, and override the original file.

Check mySQL version on Mac 10.8.5

Every time you used the mysql console, the version is shown.

 mysql -u user

Successful console login shows the following which includes the mysql server version.

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1432
Server version: 5.5.9-log Source distribution

Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.


You can also check the mysql server version directly by executing the following command:

mysql --version

You may also check the version information from the mysql console itself using the version variables:

mysql> SHOW VARIABLES LIKE "%version%";

Output will be something like this:

| Variable_name           | Value               |
| innodb_version          | 1.1.5               |
| protocol_version        | 10                  |
| slave_type_conversions  |                     |
| version                 | 5.5.9-log           |
| version_comment         | Source distribution |
| version_compile_machine | i386                |
| version_compile_os      | osx10.4             |
7 rows in set (0.01 sec)

You may also use this:

mysql> select @@version;

The STATUS command display version information as well.

mysql> STATUS

You can also check the version by executing this command:

mysql -v

It's worth mentioning that if you have encountered something like this:

ERROR 2002 (HY000): Can't connect to local MySQL server through socket
'/tmp/mysql.sock' (2)

you can fix it by:

sudo ln -s /Applications/MAMP/tmp/mysql/mysql.sock /tmp/mysql.sock

Why is there no ForEach extension method on IEnumerable?

In 3.5, all the extension methods added to IEnumerable are there for LINQ support (notice that they are defined in the System.Linq.Enumerable class). In this post, I explain why foreach doesn't belong in LINQ: Existing LINQ extension method similar to Parallel.For?

how to display a javascript var in html body

Use document.write().

  <script type="text/javascript">_x000D_
    var number = 123;_x000D_
      the value for number is:_x000D_
      <script type="text/javascript">_x000D_

How to read from stdin with fgets()?

If you want to concatenate the input, then replace printf("%s\n", buffer); with strcat(big_buffer, buffer);. Also create and initialize the big buffer at the beginning: char *big_buffer = new char[BIG_BUFFERSIZE]; big_buffer[0] = '\0';. You should also prevent a buffer overrun by verifying the current buffer length plus the new buffer length does not exceed the limit: if ((strlen(big_buffer) + strlen(buffer)) < BIG_BUFFERSIZE). The modified program would look like this:

#include <stdio.h>
#include <string.h>

#define BUFFERSIZE 10
#define BIG_BUFFERSIZE 1024

int main (int argc, char *argv[])
    char buffer[BUFFERSIZE];
    char *big_buffer = new char[BIG_BUFFERSIZE];
    big_buffer[0] = '\0';
    printf("Enter a message: \n");
    while(fgets(buffer, BUFFERSIZE , stdin) != NULL)
        if ((strlen(big_buffer) + strlen(buffer)) < BIG_BUFFERSIZE)
            strcat(big_buffer, buffer);
    return 0;

How does Trello access the user's clipboard?

Disclosure: I wrote the code that Trello uses; the code below is the actual source code Trello uses to accomplish the clipboard trick.

We don't actually "access the user's clipboard", instead we help the user out a bit by selecting something useful when they press Ctrl+C.

Sounds like you've figured it out; we take advantage of the fact that when you want to hit Ctrl+C, you have to hit the Ctrl key first. When the Ctrl key is pressed, we pop in a textarea that contains the text we want to end up on the clipboard, and select all the text in it, so the selection is all set when the C key is hit. (Then we hide the textarea when the Ctrl key comes up.)

Specifically, Trello does this:

TrelloClipboard = new class
  constructor: ->
    @value = ""

    $(document).keydown (e) =>
      # Only do this if there's something to be put on the clipboard, and it
      # looks like they're starting a copy shortcut
      if !@value || !(e.ctrlKey || e.metaKey)

      if $("input:visible,textarea:visible")

      # Abort if it looks like they've selected some text (maybe they're trying
      # to copy out a bit of the description or something)
      if window.getSelection?()?.toString()

      if document.selection?.createRange().text

      _.defer =>
        $clipboardContainer = $("#clipboard-container")
        $("<textarea id='clipboard'></textarea>")

    $(document).keyup (e) ->
      if $("#clipboard")

  set: (@value) ->

In the DOM we've got:

<div id="clipboard-container"><textarea id="clipboard"></textarea></div>

CSS for the clipboard stuff:

#clipboard-container {
  position: fixed;
  left: 0px;
  top: 0px;
  width: 0px;
  height: 0px;
  z-index: 100;
  display: none;
  opacity: 0;
#clipboard {
  width: 1px;
  height: 1px;
  padding: 0px;

... and the CSS makes it so you can't actually see the textarea when it pops in ... but it's "visible" enough to copy from.

When you hover over a card, it calls


... so then the clipboard helper knows what to select when the Ctrl key is pressed.

find_spec_for_exe': can't find gem bundler (>= 0.a) (Gem::GemNotFoundException)

to install bundler that matches with your Gemfile.lock use:

gem install bundler -v "$(grep -A 1 "BUNDLED WITH" Gemfile.lock | tail -n 1)"

Python dictionary : TypeError: unhashable type: 'list'

It works fine :, your aSourceDictionary variable may have other datatype than dict

aSourceDictionary = { 'abc' : [1,2,3] , 'ccd' : [4,5] }
aTargetDictionary = {}
for aKey in aSourceDictionary:
        aTargetDictionary[aKey] = []
print aTargetDictionary

"Failed to load platform plugin "xcb" " while launching qt5 app on linux without qt installed

I like the solution with qt.conf.

Put qt.conf near to the executable with next lines:

Prefix = /path/to/qtbase

And it works like a charm :^)

For a working example:

Prefix = /home/user/SDKS/Qt/5.6.2/5.6/gcc_64/

The documentation on this is here:

pthread function from a class

C++ : How to pass class member function to pthread_create()?

typedef void * (*THREADFUNCPTR)(void *);

class C { 
   // ...
   void *print(void *) { cout << "Hello"; }

pthread_create(&threadId, NULL, (THREADFUNCPTR) &C::print, NULL);

Can't start Tomcat as Windows Service

  1. Check the apache tomcat catalina log: ../logs/catalina.log
  2. If in the log you find the "port was used" exception, then Check windows used ports and processes with following command: Run cmd netstat -ao it will list all listening ports and corresponding process Id, you can find the port which was used by Tomcat from the configuration file: ../conf/server.xml

    <Connector port="8080" protocol="HTTP/1.1"
           redirectPort="8443" />

and kill the process which use the tomcat port

How to print table using Javascript?

One cheeky solution :

  function printDiv(divID) {
        //Get the HTML of div
        var divElements = document.getElementById(divID).innerHTML;
        //Get the HTML of whole page
        var oldPage = document.body.innerHTML;
        //Reset the page's HTML with div's HTML only
        document.body.innerHTML = 
          "<html><head><title></title></head><body>" + 
          divElements + "</body>";
        //Print Page
        //Restore orignal HTML
        document.body.innerHTML = oldPage;



<form id="form1" runat="server">
    <div id="printablediv" style="width: 100%; background-color: Blue; height: 200px">
        Print me I am in 1st Div
    <div id="donotprintdiv" style="width: 100%; background-color: Gray; height: 200px">
        I am not going to print
    <input type="button" value="Print 1st Div" onclick="javascript:printDiv('printablediv')" />

Remove duplicates from a list of objects based on property in Java 8

Another version which is simple

BiFunction<TreeSet<Employee>,List<Employee> ,TreeSet<Employee>> appendTree = (y,x) -> (y.addAll(x))? y:y;

TreeSet<Employee> outputList = appendTree.apply(new TreeSet<Employee>(Comparator.comparing(p->p.getId())),personList);

If a DOM Element is removed, are its listeners also removed from memory?

Regarding jQuery, the following common methods will also remove other constructs such as data and event handlers:


In addition to the elements themselves, all bound events and jQuery data associated with the elements are removed.


To avoid memory leaks, jQuery removes other constructs such as data and event handlers from the child elements before removing the elements themselves.


Additionally, jQuery removes other constructs such as data and event handlers from child elements before replacing those elements with the new content.

How to remove single character from a String

I just implemented this utility class that removes a char or a group of chars from a String. I think it's fast because doesn't use Regexp. I hope that it helps someone!


 * Utility class that removes chars from a String.
public class RemoveChars {

    public static String remove(String string, String remove) {
        return new String(remove(string.toCharArray(), remove.toCharArray()));

    public static char[] remove(final char[] chars, char[] remove) {

        int count = 0;
        char[] buffer = new char[chars.length];

        for (int i = 0; i < chars.length; i++) {

            boolean include = true;
            for (int j = 0; j < remove.length; j++) {
                if ((chars[i] == remove[j])) {
                    include = false;

            if (include) {
                buffer[count++] = chars[i];

        char[] output = new char[count];
        System.arraycopy(buffer, 0, output, 0, count);

        return output;

     * For tests!
    public static void main(String[] args) {

        String remove = "AEIOU";

        System.out.println("Remove AEIOU: " + string);
        System.out.println("Result:       " + RemoveChars.remove(string, remove));

This is the output:


How to construct a relative path in Java from two absolute paths (or URLs)?

Actually my other answer didn't work if the target path wasn't a child of the base path.

This should work.

public class RelativePathFinder {

    public static String getRelativePath(String targetPath, String basePath, 
       String pathSeparator) {

        // find common path
        String[] target = targetPath.split(pathSeparator);
        String[] base = basePath.split(pathSeparator);

        String common = "";
        int commonIndex = 0;
        for (int i = 0; i < target.length && i < base.length; i++) {

            if (target[i].equals(base[i])) {
                common += target[i] + pathSeparator;

        String relative = "";
        // is the target a child directory of the base directory?
        // i.e., target = /a/b/c/d, base = /a/b/
        if (commonIndex == base.length) {
            relative = "." + pathSeparator + targetPath.substring(common.length());
        else {
            // determine how many directories we have to backtrack
            for (int i = 1; i <= commonIndex; i++) {
                relative += ".." + pathSeparator;
            relative += targetPath.substring(common.length());

        return relative;

    public static String getRelativePath(String targetPath, String basePath) {
        return getRelativePath(targetPath, basePath, File.pathSeparator);

public class RelativePathFinderTest extends TestCase {

    public void testGetRelativePath() {
        assertEquals("./stuff/xyz.dat", RelativePathFinder.getRelativePath(
                "/var/data/stuff/xyz.dat", "/var/data/", "/"));
        assertEquals("../../b/c", RelativePathFinder.getRelativePath("/a/b/c",
                "/a/x/y/", "/"));


What is a software framework?

A simple explanation is: A framework is a scaffold that you can you build applications around.

A framework generally provides some base functionality which you can use and extend to make more complex applications from, there are frameworks for all sorts of things. Microsofts MVC framework is a good example of this. It provides everything you need to get off the ground building website using the MVC pattern, it handles web requests, routes and the like. All you have to do is implement "Controllers" and provide "Views" which are two constructs defined by the MVC framework. The MVC framework then handles calling your controllers and rendering your views.

Perhaps not the best wording but I hope it helps

How can I split a text file using PowerShell?

I've made a little modification to split files based on size of each part.

# Breaks a text file into multiple text files in a destination, where each
# file contains a maximum number of lines.
# When working with files that have a header, it is often desirable to have
# the header information repeated in all of the split files. Split-File
# supports this functionality with the -rc (RepeatCount) parameter.
# Specifies the path to an item. Wildcards are permitted.
#.PARAMETER LiteralPath
# Specifies the path to an item. Unlike Path, the value of LiteralPath is
# used exactly as it is typed. No characters are interpreted as wildcards.
# If the path includes escape characters, enclose it in single quotation marks.
# Single quotation marks tell Windows PowerShell not to interpret any
# characters as escape sequences.
#.PARAMETER Destination
# (Or -d) The location in which to place the chunked output files.
# (Or -s) The maximum size of each file. Size must be expressed in MB.
#.PARAMETER RepeatCount
# (Or -rc) Specifies the number of "header" lines from the input file that will
# be repeated in each output file. Typically this is 0 or 1 but it can be any
# number of lines.
# Split-File bigfile.csv -s 20 -rc 1
# Out-TempFile
function Split-File {


        [Parameter(ParameterSetName='Path', Position=1, Mandatory=$true, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)]

        [Parameter(ParameterSetName='LiteralPath', Mandatory=$true, ValueFromPipelineByPropertyName=$true)]





    process {

  # yeah! the cmdlet supports wildcards
        if ($LiteralPath) { $ResolveArgs = @{LiteralPath=$LiteralPath} }
        elseif ($Path) { $ResolveArgs = @{Path=$Path} }

        Resolve-Path @ResolveArgs | %{

            $InputName = [IO.Path]::GetFileNameWithoutExtension($_)
            $InputExt  = [IO.Path]::GetExtension($_)

            if ($RepeatCount) { $Header = Get-Content $_ -TotalCount:$RepeatCount }

   Resolve-Path @ResolveArgs | %{

    $InputName = [IO.Path]::GetFileNameWithoutExtension($_)
    $InputExt  = [IO.Path]::GetExtension($_)

    if ($RepeatCount) { $Header = Get-Content $_ -TotalCount:$RepeatCount }

    # get the input file in manageable chunks

    $Part = 1
    $buffer = ""
    Get-Content $_ -ReadCount:1 | %{

     # make an output filename with a suffix
     $OutputFile = Join-Path $Destination ('{0}-{1:0000}{2}' -f ($InputName,$Part,$InputExt))

     # In the first iteration the header will be
     # copied to the output file as usual
     # on subsequent iterations we have to do it
     if ($RepeatCount -and $Part -gt 1) {
      Set-Content $OutputFile $Header

     # test buffer size and dump data only if buffer is greater than size
     if ($buffer.length -gt ($Size * 1MB)) {
      # write this chunk to the output file
      Write-Host "Writing $OutputFile"
      Add-Content $OutputFile $buffer
      $Part += 1
      $buffer = ""
     } else {
      $buffer += $_ + "`r"

How to replace unicode characters in string with something else python?

Funny the answer is hidden in among the answers.

str.replace("•", "something") 

would work if you use the right semantics.


works wonders ;) , thnx to RParadox for the hint.

How to compare two maps by their values

To see if two maps have the same values, you can do the following:

  • Get their Collection<V> values() views
  • Wrap into List<V>
  • Collections.sort those lists
  • Test if the two lists are equals

Something like this works (though its type bounds can be improved on):

static <V extends Comparable<V>>
boolean valuesEquals(Map<?,V> map1, Map<?,V> map2) {
    List<V> values1 = new ArrayList<V>(map1.values());
    List<V> values2 = new ArrayList<V>(map2.values());
    return values1.equals(values2);

Test harness:

Map<String, String> map1 = new HashMap<String,String>();
map1.put("A", "B");
map1.put("C", "D");

Map<String, String> map2 = new HashMap<String,String>();
map2.put("A", "D");
map2.put("C", "B");

System.out.println(valuesEquals(map1, map2)); // prints "true"

This is O(N log N) due to Collections.sort.

See also:

To test if the keys are equals is easier, because they're Set<K>:


See also:

How to make an AJAX call without jQuery?

I know this is a fairly old question, but there is now a nicer API available natively in newer browsers. The fetch() method allow you to make web requests. For example, to request some json from /get-data:

var opts = {
  method: 'GET',      
  headers: {}
fetch('/get-data', opts).then(function (response) {
  return response.json();
.then(function (body) {
  //doSomething with body;

See here for more details.

mvn command not found in OSX Mavrerick

Here is what worked for me.

First of all I checked if M2_HOME variable is set env | grep M2_HOME. I've got nothing.

I knew I had Maven installed in the folder "/usr/local/apache-maven-3.2.2", so executing the following 3 steps solved the problem for me:

  1. Set M2_HOME env variable


  1. Set M2 env variable


  1. Update the PATH

export PATH=$M2:$PATH

As mentioned above you can save that sequence in the .bash_profile file if you want it to be executed automatically.

Difference between applicationContext.xml and spring-servlet.xml in Spring Framework

One more point I want to add. In spring-servlet.xml we include component scan for Controller package. In following example we include filter annotation for controller package.

<!-- Scans for annotated @Controllers in the classpath -->
<context:component-scan base-package="org.test.web" use-default-filters="false">
    <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>

In applicationcontext.xml we add filter for remaining package excluding controller.

<context:component-scan base-package="org.test">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>

Simple C example of doing an HTTP POST and consuming the response

After weeks of research. I came up with the following code. I believe this is the bare minimum needed to make a secure connection with SSL to a web server.

#include <stdio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/bio.h>

#define PORT "443"

int main() {

    //  Initialize the variables
    BIO* bio;
    SSL* ssl;
    SSL_CTX* ctx;

    //   Registers the SSL/TLS ciphers and digests.
    //   Basically start the security layer.

    //  Creates a new SSL_CTX object as a framework to establish TLS/SSL
    //  or DTLS enabled connections
    ctx = SSL_CTX_new(SSLv23_client_method());

    //  -> Error check
    if (ctx == NULL)
        printf("Ctx is null\n");

    //   Creates a new BIO chain consisting of an SSL BIO
    bio = BIO_new_ssl_connect(ctx);

    //  Use the variable from the beginning of the file to create a 
    //  string that contains the URL to the site that you want to connect
    //  to while also specifying the port.
    BIO_set_conn_hostname(bio, HOST ":" PORT);

    //   Attempts to connect the supplied BIO
    if(BIO_do_connect(bio) <= 0)
        printf("Failed connection\n");
        return 1;

    //  The bare minimum to make a HTTP request.
    char* write_buf = "POST / HTTP/1.1\r\n"
                      "Host: " HOST "\r\n"
                      "Authorization: Basic " APIKEY "\r\n"
                      "Connection: close\r\n"

    //   Attempts to write len bytes from buf to BIO
    if(BIO_write(bio, write_buf, strlen(write_buf)) <= 0)
        //  Handle failed writes here
            // Not worth implementing, but worth knowing.

        //  -> Let us know about the failed writes
        printf("Failed write\n");

    //  Variables used to read the response from the server
    int size;
    char buf[1024];

    //  Read the response message
        //  Get chunks of the response 1023 at the time.
        size = BIO_read(bio, buf, 1023);

        //  If no more data, then exit the loop
        if(size <= 0)

        //  Terminate the string with a 0, to let know C when the string 
        //  ends.
        buf[size] = 0;

        //  ->  Print out the response
        printf("%s", buf);

    //  Clean after ourselves

    return 0;

The code above will explain in details how to establish a TLS connection with a remote server.

Important note: this code doesn't check if the public key was signed by a valid authority. Meaning I don't use root certificates for validation. Don't forget to implement this check otherwise you won't know if you are connecting the right website

When it comes to the request itself. It is nothing more then writing the HTTP request by hand.

You can also find under this link an explanation how to instal openSSL in your system, and how to compile the code so it uses the secure library.

How can I get a character in a string by index?

Do you mean like this

int index = 2;
string s = "hello";

string also implements IEnumberable<char> so you can also enumerate it like this

foreach (char c in s)

How to convert answer into two decimal point

If you just want to print a decimal number with 2 digits after decimal point in specific format no matter of locals use something like this

dim d as double = 1.23456789
dim s as string = d.Tostring("0.##", New System.Globalization.CultureInfo("en-US"))

How to access parameters in a Parameterized Build?

Hope the following piece of code works for you:

def item = hudson.model.Hudson.instance.getItem('MyJob')

def value = item.lastBuild.getEnvironment(null).get('foo')

How to use 'git pull' from the command line?

Try setting the HOME environment variable in Windows to your home folder (c:\users\username).

( you can confirm that this is the problem by doing echo $HOME in git bash and echo %HOME% in cmd - latter might not be available )

If statement for strings in python?

Python is a case-sensitive language. All Python keywords are lowercase. Use if, not If.

Also, don't put a colon after the call to print(). Also, indent the print() and exit() calls, as Python uses indentation rather than brackets to represent code blocks.

And also, proceed = "y" or "Y" won't do what you want. Use proceed = "y" and if answer.lower() == proceed:, or something similar.

There's also the fact that your program will exit as long as the input value is not the single character "y" or "Y", which contradicts the prompting of "N" for the alternate case. Instead of your else clause there, use elif answer.lower() == info_incorrect:, with info_incorrect = "n" somewhere beforehand. Then just reprompt for the response or something if the input value was something else.

I'd recommend going through the tutorial in the Python documentation if you're having this much trouble the way you're learning now.

How to write a UTF-8 file with Java?

The Java 7 Files utility type is useful for working with files:

import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.*;

public class WriteReadUtf8 {
  public static void main(String[] args) throws IOException {
    List<String> lines = Arrays.asList("These", "are", "lines");

    Path textFile = Paths.get("foo.txt");
    Files.write(textFile, lines, StandardCharsets.UTF_8);

    List<String> read = Files.readAllLines(textFile, StandardCharsets.UTF_8);


The Java 8 version allows you to omit the Charset argument - the methods default to UTF-8.

How to check if DST (Daylight Saving Time) is in effect, and if so, the offset?

Is there an issue using the Date.toString().indexOf('Daylight Time') > -1

"" + new Date()

Sat Jan 01 100050 00:00:00 GMT-0500 (Eastern Standard Time)

"" + new Date(...)

Sun May 01 100033 00:00:00 GMT-0400 (Eastern Daylight Time)

This seems compatible with all browsers.

href="javascript:" vs. href="javascript:void(0)"

It does not cause problems but it's a trick to do the same as PreventDefault

when you're way down in the page and an anchor as:

<a href="#" onclick="fn()">click here</a>

you will jump to the top and the URL will have the anchor # as well, to avoid this we simply return false; or use javascript:void(0);

regarding your examples

<a onclick="fn()">Does not appear as a link, because there's no href</a>

just do a {text-decoration:underline;} and you will have "link a-like"

<a href="javascript:void(0)" onclick="fn()">fn is called</a>
<a href="javascript:" onclick="fn()">fn is called too!</a>

it's ok, but in your function at the end, just return false; to prevent the default behavior, you don't need to do anything more.

Removing duplicates from a String in Java

import java.util.Scanner;

public class dublicate {
    public static void main(String... a) {
        System.out.print("Enter the String");
        Scanner Sc = new Scanner(;
        String st=Sc.nextLine();
        StringBuilder sb=new StringBuilder();
        boolean [] bc=new boolean[256];
        for(int i=0;i<st.length();i++)
            int index=st.charAt(i);


C: socket connection timeout

Set the socket non-blocking, and use select() (which takes a timeout parameter). If a non-blocking socket is trying to connect, then select() will indicate that the socket is writeable when the connect() finishes (either successfully or unsuccessfully). You then use getsockopt() to determine the outcome of the connect():

int main(int argc, char **argv) {
    u_short port;                /* user specified port number */
    char *addr;                  /* will be a pointer to the address */
    struct sockaddr_in address;  /* the libc network address data structure */
    short int sock = -1;         /* file descriptor for the network socket */
    fd_set fdset;
    struct timeval tv;

    if (argc != 3) {
        fprintf(stderr, "Usage %s <port_num> <address>\n", argv[0]);
        return EXIT_FAILURE;

    port = atoi(argv[1]);
    addr = argv[2];

    address.sin_family = AF_INET;
    address.sin_addr.s_addr = inet_addr(addr); /* assign the address */
    address.sin_port = htons(port);            /* translate int2port num */

    sock = socket(AF_INET, SOCK_STREAM, 0);
    fcntl(sock, F_SETFL, O_NONBLOCK);

    connect(sock, (struct sockaddr *)&address, sizeof(address));

    FD_SET(sock, &fdset);
    tv.tv_sec = 10;             /* 10 second timeout */
    tv.tv_usec = 0;

    if (select(sock + 1, NULL, &fdset, NULL, &tv) == 1)
        int so_error;
        socklen_t len = sizeof so_error;

        getsockopt(sock, SOL_SOCKET, SO_ERROR, &so_error, &len);

        if (so_error == 0) {
            printf("%s:%d is open\n", addr, port);

    return 0;

How to revert multiple git commits?

Clean way which I found useful

git revert --no-commit HEAD~3..

This command reverts last 3 commits with only one commit.

Also doesn't rewrite history.

The .. helps create a range. Meaning HEAD~3.. is the same as HEAD~3..HEAD

Could not resolve all dependencies for configuration ':classpath'

I installed new Android Studio and faced with this problem. Nothing is helped me except of downloading a few more Android SDK versions: Added Android Q and Android Pie to downloaded and installed SDK

React - Component Full Screen (with height 100%)

Despite using of React here - elements layout is completely html/css feature.

The root cause of the issue is in how height property in css works. When you are using relative values for height (in %) - this means that height will be set in relation to its parent.

So if you have a structure like html > body > div#root > - to make 100% height all its ancestors should have 100% height. You may play with next example:

html {_x000D_
  height: 100%;_x000D_
body {_x000D_
  height: 100%;_x000D_
div#root {_x000D_
  height: 100%; /* remove this line to see is no more 100% height */_x000D_
  background-color: indigo;_x000D_
  padding: 0 30px;_x000D_
_x000D_ {_x000D_
  height: 100%;_x000D_
  background-color: cornsilk;_x000D_
<div id="root">_x000D_
  <div class="app"> I will be 100% height if my parents are </div>_x000D_

Few arguments:

  • Usage of !important - despite some time this feature is useful in ~95% of cases, it indicates a poor structure of html/css. Also, this is not a solution to the current problem.
  • Why not position: absolute. Property positon is designed to change how the element will be rendered in relation to (own position - relative, viewport - fixed, nearest parent whos position is not static - absolute). Ans despite position: absolute; top: 0; right: 0; bottom: 0; left: 0; will result in the same look - it also pushes you to change parents position to something not static - so you need to maintain 2 elements. That also causes parent div be collapsed in a line (0-height), and inner - full screen. That makes confusion in element inspector.

How do I insert a drop-down menu for a simple Windows Forms app in Visual Studio 2008?

You can use a ComboBox with its ComboBoxStyle (appears as DropDownStyle in later versions) set to DropDownList. See:

How to know if two arrays have the same values

Object equality check:JSON.stringify(array1.sort()) === JSON.stringify(array2.sort())

The above test also works with arrays of objects in which case use a sort function as documented in

Might suffice for small arrays with flat JSON schemas.

How do I use Join-Path to combine more than two strings into a file path?

Here's something that will do what you'd want when using a string array for the ChildPath.

$path = "C:"
@( "Program Files", "Microsoft Office" ) | %{ $path = Join-Path $path $_ }
Write-Host $path

Which outputs

C:\Program Files\Microsoft Office

The only caveat I found is that the initial value for $path must have a value (cannot be null or empty).

centos: Another MySQL daemon already running with the same unix socket

To start the MySQL service, you can remove '/var/lib/mysql/mysql.sock' and start the MySQL service again:

Remove the socket file:

[root@server ~]# rm /var/lib/mysql/mysql.sock
rm: remove socket `/var/lib/mysql/mysql.sock'? yes

Start the MySQL service:

[root@server~]# service mysqld start
Starting mysqld:                                           [  OK  ]

It will help you to resolve your problem.

What is the most efficient way to loop through dataframes with pandas?

Just as a small addition, you can also do an apply if you have a complex function that you apply to a single column:

df[b] = df[a].apply(lambda col: do stuff with col here)

HTTP GET Request in Node.js Express

This version is based on the initially proposed by bryanmac function which uses promises, better error handling, and is rewritten in ES6.

let http = require("http"),
    https = require("https");

* getJSON:  REST get request returning JSON object(s)
* @param options: http options object
exports.getJSON = function (options) {
    let reqHandler = +options.port === 443 ? https : http;

    return new Promise((resolve, reject) => {
        let req = reqHandler.request(options, (res) => {
            let output = '';
            console.log('rest::', + ':' + res.statusCode);

            res.on('data', function (chunk) {
                output += chunk;

            res.on('end', () => {
                try {
                    let obj = JSON.parse(output);
                    // console.log('rest::', obj);
                        statusCode: res.statusCode,
                        data: obj
                catch (err) {
                    console.error('rest::end', err);

        req.on('error', (err) => {
            console.error('rest::request', err);


As a result you don't have to pass in a callback function, instead getJSON() returns a promise. In the following example the function is used inside of an ExpressJS route handler

router.get('/:id', (req, res, next) => {
        host: host,
        path: `/posts/${}`,
        method: 'GET'
    }).then(({ statusCode, data }) => {
    }, (error) => {

On error it delegates the error to the server error handling middleware.

Add to Array jQuery

For JavaScript arrays, you use Both push() and concat() function.

var array = [1, 2, 3];
array.push(4, 5);         //use push for appending a single array.

var array1 = [1, 2, 3];
var array2 = [4, 5, 6];

var array3 = array1.concat(array2);   //It is better use concat for appending more then one array.

Can I mask an input text in a bat file?

@echo off
color 0f
choice /C ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!?.# /N /CS /M Please enter your password to continue. (Valid characters include all letters, numbers, and ! ? .) Press # to submit: 
IF %ecode% EQU 66 goto submit
IF %ecode% EQU 1 SET out=A
IF %ecode% EQU 2 SET out=B
IF %ecode% EQU 3 SET out=C
IF %ecode% EQU 4 SET out=D
IF %ecode% EQU 5 SET out=E
IF %ecode% EQU 6 SET out=F
IF %ecode% EQU 7 SET out=G
IF %ecode% EQU 8 SET out=H
IF %ecode% EQU 9 SET out=I
IF %ecode% EQU 10 SET out=J
IF %ecode% EQU 11 SET out=K
IF %ecode% EQU 12 SET out=L
IF %ecode% EQU 13 SET out=M
IF %ecode% EQU 14 SET out=N
IF %ecode% EQU 15 SET out=O
IF %ecode% EQU 16 SET out=P
IF %ecode% EQU 17 SET out=Q
IF %ecode% EQU 18 SET out=R
IF %ecode% EQU 19 SET out=S
IF %ecode% EQU 20 SET out=T
IF %ecode% EQU 21 SET out=U
IF %ecode% EQU 22 SET out=V
IF %ecode% EQU 23 SET out=W
IF %ecode% EQU 24 SET out=X
IF %ecode% EQU 25 SET out=Y
IF %ecode% EQU 26 SET out=Z
IF %ecode% EQU 27 SET out=a
IF %ecode% EQU 28 SET out=b
IF %ecode% EQU 29 SET out=c
IF %ecode% EQU 30 SET out=d
IF %ecode% EQU 31 SET out=e
IF %ecode% EQU 32 SET out=f
IF %ecode% EQU 33 SET out=g
IF %ecode% EQU 34 SET out=h
IF %ecode% EQU 35 SET out=i
IF %ecode% EQU 36 SET out=j
IF %ecode% EQU 37 SET out=k
IF %ecode% EQU 38 SET out=l
IF %ecode% EQU 39 SET out=m
IF %ecode% EQU 40 SET out=n
IF %ecode% EQU 41 SET out=o
IF %ecode% EQU 42 SET out=p
IF %ecode% EQU 43 SET out=q
IF %ecode% EQU 44 SET out=r
IF %ecode% EQU 45 SET out=s
IF %ecode% EQU 46 SET out=t
IF %ecode% EQU 47 SET out=u
IF %ecode% EQU 48 SET out=v
IF %ecode% EQU 49 SET out=w
IF %ecode% EQU 50 SET out=x
IF %ecode% EQU 51 SET out=y
IF %ecode% EQU 52 SET out=z
IF %ecode% EQU 53 SET out=0
IF %ecode% EQU 54 SET out=1
IF %ecode% EQU 55 SET out=2
IF %ecode% EQU 56 SET out=3
IF %ecode% EQU 57 SET out=4
IF %ecode% EQU 58 SET out=5
IF %ecode% EQU 59 SET out=6
IF %ecode% EQU 60 SET out=7
IF %ecode% EQU 61 SET out=8
IF %ecode% EQU 62 SET out=9
IF %ecode% EQU 63 SET out=!
IF %ecode% EQU 64 SET out=?
IF %ecode% EQU 65 SET out=.
SET code=%out%
SET show=*
choice /C ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!?.# /N /CS /M Please enter your password to continue. (Valid characters include all letters, numbers, and ! ? .) Press # to submit: %code%
IF %ecode% EQU 66 goto submit
IF %ecode% EQU 1 SET out=A
IF %ecode% EQU 2 SET out=B
IF %ecode% EQU 3 SET out=C
IF %ecode% EQU 4 SET out=D
IF %ecode% EQU 5 SET out=E
IF %ecode% EQU 6 SET out=F
IF %ecode% EQU 7 SET out=G
IF %ecode% EQU 8 SET out=H
IF %ecode% EQU 9 SET out=I
IF %ecode% EQU 10 SET out=J
IF %ecode% EQU 11 SET out=K
IF %ecode% EQU 12 SET out=L
IF %ecode% EQU 13 SET out=M
IF %ecode% EQU 14 SET out=N
IF %ecode% EQU 15 SET out=O
IF %ecode% EQU 16 SET out=P
IF %ecode% EQU 17 SET out=Q
IF %ecode% EQU 18 SET out=R
IF %ecode% EQU 19 SET out=S
IF %ecode% EQU 20 SET out=T
IF %ecode% EQU 21 SET out=U
IF %ecode% EQU 22 SET out=V
IF %ecode% EQU 23 SET out=W
IF %ecode% EQU 24 SET out=X
IF %ecode% EQU 25 SET out=Y
IF %ecode% EQU 26 SET out=Z
IF %ecode% EQU 27 SET out=a
IF %ecode% EQU 28 SET out=b
IF %ecode% EQU 29 SET out=c
IF %ecode% EQU 30 SET out=d
IF %ecode% EQU 31 SET out=e
IF %ecode% EQU 32 SET out=f
IF %ecode% EQU 33 SET out=g
IF %ecode% EQU 34 SET out=h
IF %ecode% EQU 35 SET out=i
IF %ecode% EQU 36 SET out=j
IF %ecode% EQU 37 SET out=k
IF %ecode% EQU 38 SET out=l
IF %ecode% EQU 39 SET out=m
IF %ecode% EQU 40 SET out=n
IF %ecode% EQU 41 SET out=o
IF %ecode% EQU 42 SET out=p
IF %ecode% EQU 43 SET out=q
IF %ecode% EQU 44 SET out=r
IF %ecode% EQU 45 SET out=s
IF %ecode% EQU 46 SET out=t
IF %ecode% EQU 47 SET out=u
IF %ecode% EQU 48 SET out=v
IF %ecode% EQU 49 SET out=w
IF %ecode% EQU 50 SET out=x
IF %ecode% EQU 51 SET out=y
IF %ecode% EQU 52 SET out=z
IF %ecode% EQU 53 SET out=0
IF %ecode% EQU 54 SET out=1
IF %ecode% EQU 55 SET out=2
IF %ecode% EQU 56 SET out=3
IF %ecode% EQU 57 SET out=4
IF %ecode% EQU 58 SET out=5
IF %ecode% EQU 59 SET out=6
IF %ecode% EQU 60 SET out=7
IF %ecode% EQU 61 SET out=8
IF %ecode% EQU 62 SET out=9
IF %ecode% EQU 63 SET out=!
IF %ecode% EQU 64 SET out=?
IF %ecode% EQU 65 SET out=.
SET code=%code%%out%
SET show=%show%*
goto loop
SET password=%code%
IF %password% EQU 0cZrocks! SET result=1
IF ELSE SET result=2
IF %result% EQU 1 echo password correct
IF %result% EQU 2 echo password incorrect
timeout /T 2 /NOBREAK >nul
IF %result% EQU 1 goto end
IF ELSE goto start

How do you use a variable in a regular expression?

this.replace( new RegExp( replaceThis, 'g' ), withThis );

ios app maximum memory budget

By forking SPLITS repo, I built one to test iOS memory that can be allocated to the Today's Extension


Following is the result that i got in iPhone 5s

Memory Warning at 10 MB

App Crashed at 12 MB

By this means Apple is merely allowing any extensions to work with their full potential.

is vs typeof

They don't do the same thing. The first one works if obj is of type ClassA or of some subclass of ClassA. The second one will only match objects of type ClassA. The second one will be faster since it doesn't have to check the class hierarchy.

For those who want to know the reason, but don't want to read the article referenced in is vs typeof.

Difference between VARCHAR and TEXT in MySQL



  • fixed max size of 65535 characters (you cannot limit the max size)
  • takes 2 + c bytes of disk space, where c is the length of the stored string.
  • cannot be (fully) part of an index. One would need to specify a prefix length.


  • variable max size of M characters
  • M needs to be between 1 and 65535
  • takes 1 + c bytes (for M ≤ 255) or 2 + c (for 256 ≤ M ≤ 65535) bytes of disk space where c is the length of the stored string
  • can be part of an index

More Details

TEXT has a fixed max size of 2¹6-1 = 65535 characters.
VARCHAR has a variable max size M up to M = 2¹6-1.
So you cannot choose the size of TEXT but you can for a VARCHAR.

The other difference is, that you cannot put an index (except for a fulltext index) on a TEXT column.
So if you want to have an index on the column, you have to use VARCHAR. But notice that the length of an index is also limited, so if your VARCHAR column is too long you have to use only the first few characters of the VARCHAR column in your index (See the documentation for CREATE INDEX).

But you also want to use VARCHAR, if you know that the maximum length of the possible input string is only M, e.g. a phone number or a name or something like this. Then you can use VARCHAR(30) instead of TINYTEXT or TEXT and if someone tries to save the text of all three "Lord of the Ring" books in your phone number column you only store the first 30 characters :)

Edit: If the text you want to store in the database is longer than 65535 characters, you have to choose MEDIUMTEXT or LONGTEXT, but be careful: MEDIUMTEXT stores strings up to 16 MB, LONGTEXT up to 4 GB. If you use LONGTEXT and get the data via PHP (at least if you use mysqli without store_result), you maybe get a memory allocation error, because PHP tries to allocate 4 GB of memory to be sure the whole string can be buffered. This maybe also happens in other languages than PHP.

However, you should always check the input (Is it too long? Does it contain strange code?) before storing it in the database.

Notice: For both types, the required disk space depends only on the length of the stored string and not on the maximum length.
E.g. if you use the charset latin1 and store the text "Test" in VARCHAR(30), VARCHAR(100) and TINYTEXT, it always requires 5 bytes (1 byte to store the length of the string and 1 byte for each character). If you store the same text in a VARCHAR(2000) or a TEXT column, it would also require the same space, but, in this case, it would be 6 bytes (2 bytes to store the string length and 1 byte for each character).

For more information have a look at the documentation.

Finally, I want to add a notice, that both, TEXT and VARCHAR are variable length data types, and so they most likely minimize the space you need to store the data. But this comes with a trade-off for performance. If you need better performance, you have to use a fixed length type like CHAR. You can read more about this here.

sequelize findAll sort order in nodejs

You can accomplish this in a very back-handed way with the following code:

exports.getStaticCompanies = function () {
    var ids = [46128, 2865, 49569, 1488, 45600, 61991, 1418, 61919, 53326, 61680]
    return Company.findAll({
        where: {
            id: ids
        attributes: ['id', 'logo_version', 'logo_content_type', 'name', 'updated_at'],
        order: sequelize.literal('(' + {
            return '"Company"."id" = \'' + id + '\'');
        }).join(', ') + ') DESC')

This is somewhat limited because it's got very bad performance characteristics past a few dozen records, but it's acceptable at the scale you're using.

This will produce a SQL query that looks something like this:

[...] ORDER BY ("Company"."id"='46128', "Company"."id"='2865', "Company"."id"='49569', [...])

How to backup MySQL database in PHP?

Based on the good solution that provided by tazo todua, I've made some of changes since mysql_connect has deprecated and not supported in new php version. I've used mysqli_connect instead and increased the performance of inserting values to the database:


* Updated: Mohammad M. AlBanna
* Website:

//MySQL server and database
$dbhost = 'localhost';
$dbuser = 'my_user';
$dbpass = 'my_pwd';
$dbname = 'database_name';
$tables = '*';

//Call the core function
backup_tables($dbhost, $dbuser, $dbpass, $dbname, $tables);

//Core function
function backup_tables($host, $user, $pass, $dbname, $tables = '*') {
    $link = mysqli_connect($host,$user,$pass, $dbname);

    // Check connection
    if (mysqli_connect_errno())
        echo "Failed to connect to MySQL: " . mysqli_connect_error();

    mysqli_query($link, "SET NAMES 'utf8'");

    //get all of the tables
    if($tables == '*')
        $tables = array();
        $result = mysqli_query($link, 'SHOW TABLES');
        while($row = mysqli_fetch_row($result))
            $tables[] = $row[0];
        $tables = is_array($tables) ? $tables : explode(',',$tables);

    $return = '';
    //cycle through
    foreach($tables as $table)
        $result = mysqli_query($link, 'SELECT * FROM '.$table);
        $num_fields = mysqli_num_fields($result);
        $num_rows = mysqli_num_rows($result);

        $return.= 'DROP TABLE IF EXISTS '.$table.';';
        $row2 = mysqli_fetch_row(mysqli_query($link, 'SHOW CREATE TABLE '.$table));
        $return.= "\n\n".$row2[1].";\n\n";
        $counter = 1;

        //Over tables
        for ($i = 0; $i < $num_fields; $i++) 
        {   //Over rows
            while($row = mysqli_fetch_row($result))
                if($counter == 1){
                    $return.= 'INSERT INTO '.$table.' VALUES(';
                } else{
                    $return.= '(';

                //Over fields
                for($j=0; $j<$num_fields; $j++) 
                    $row[$j] = addslashes($row[$j]);
                    $row[$j] = str_replace("\n","\\n",$row[$j]);
                    if (isset($row[$j])) { $return.= '"'.$row[$j].'"' ; } else { $return.= '""'; }
                    if ($j<($num_fields-1)) { $return.= ','; }

                if($num_rows == $counter){
                    $return.= ");\n";
                } else{
                    $return.= "),\n";

    //save file
    $fileName = 'db-backup-'.time().'-'.(md5(implode(',',$tables))).'.sql';
    $handle = fopen($fileName,'w+');
        echo "Done, the file name is: ".$fileName;

Best Practice for Forcing Garbage Collection in C#

The best practise is to not force a garbage collection.

According to MSDN:

"It is possible to force garbage collection by calling Collect, but most of the time, this should be avoided because it may create performance issues. "

However, if you can reliably test your code to confirm that calling Collect() won't have a negative impact then go ahead...

Just try to make sure objects are cleaned up when you no longer need them. If you have custom objects, look at using the "using statement" and the IDisposable interface.

This link has some good practical advice with regards to freeing up memory / garbage collection etc:

Carriage Return\Line feed in Java

The method newLine() ensures a platform-compatible new line is added (0Dh 0Ah for DOS, 0Dh for older Macs, 0Ah for Unix/Linux). Java has no way of knowing on which platform you are going to send the text. This conversion should be taken care of by the mail sending entities.

SQL Server convert string to datetime

UPDATE MyTable SET MyDate = CONVERT(datetime, '2009/07/16 08:28:01', 120)

For a full discussion of CAST and CONVERT, including the different date formatting options, see the MSDN Library Link below:

Creating an Instance of a Class with a variable in Python

You can create variable like this:

x = 10 

Or this:

globals()['y'] = 100

Lets create a new class:

class Foo(object):
    def __init__(self): = 'John'

You can create class instance this way:

instance_name_1 = Foo()

Or this way:

globals()['instance_name_2'] = Foo()

Lets create a function:

def create_new_instance(class_name,instance_name):
    globals()[instance_name] = class_name()
    print('Class instance '{}' created!'.format(instance_name))

Call a function:

create_new_instance(Foo,'new_instance') #Class instance 'new_instance' created!
print( #John

Also we can write generator function:

def create_instance(class_name,instance_name):
    count = 0
    while True:
        name = instance_name + str(count)
        globals()[name] = class_name()
        count += 1
        print('Class instance: {}'.format(name))
        yield True

generator_instance = create_instance(Foo,'instance_') 

for i in range(5):

#Class instance: instance_0
#Class instance: instance_1
#Class instance: instance_2
#Class instance: instance_3
#Class instance: instance_4

print( #john
print( #john
print( #john
print( #john
print( #john

#print( #error.. we only created 5 instances.. 

next(generator_instance) #Class instance: instance_5
print( #John  Now it works.. 

A TypeScript GUID class?

There is an implementation in my TypeScript utilities based on JavaScript GUID generators.

Here is the code:

class Guid {_x000D_
  static newGuid() {_x000D_
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {_x000D_
      var r = Math.random() * 16 | 0,_x000D_
        v = c == 'x' ? r : (r & 0x3 | 0x8);_x000D_
      return v.toString(16);_x000D_
// Example of a bunch of GUIDs_x000D_
for (var i = 0; i < 100; i++) {_x000D_
  var id = Guid.newGuid();_x000D_

Please note the following:

C# GUIDs are guaranteed to be unique. This solution is very likely to be unique. There is a huge gap between "very likely" and "guaranteed" and you don't want to fall through this gap.

JavaScript-generated GUIDs are great to use as a temporary key that you use while waiting for a server to respond, but I wouldn't necessarily trust them as the primary key in a database. If you are going to rely on a JavaScript-generated GUID, I would be tempted to check a register each time a GUID is created to ensure you haven't got a duplicate (an issue that has come up in the Chrome browser in some cases).

IntelliJ IDEA 13 uses Java 1.5 despite setting to 1.7

I have same problem but with different situation. I can compile without any issue with maven in command line (mvn clean install), but in Intellij I always got "java: diamond operator is not supported in -source 1.5" compile error despite I have set the maven-compiler-plugin with java 1.8 in the pom.xml.

It turned out I have remote repository setting in my maven's settings.xml which the project depends on, but Intellij uses his own maven which doesn't have same setting with my local maven.

So my solution was changing the Intellij's maven setting (Settings -> Build, execution, Deployment -> Maven -> Maven home directory) to use the local maven.

How to update Pandas from Anaconda and is it possible to use eclipse with this last

Simply type conda update pandas in your preferred shell (on Windows, use cmd; if Anaconda is not added to your PATH use the Anaconda prompt). You can of course use Eclipse together with Anaconda, but you need to specify the Python-Path (the one in the Anaconda-Directory). See this document for a detailed instruction.

Difference between git pull and git pull --rebase

git pull = git fetch + git merge against tracking upstream branch

git pull --rebase = git fetch + git rebase against tracking upstream branch

If you want to know how git merge and git rebase differ, read this.

Gem Command not found

FWIW, the equivalent package for RHEL/Fedora/CentOS/etc and SuSE/OpenSuSE appears to be called 'rubygems'.

Java JTable setting Column Width

JTable.AUTO_RESIZE_LAST_COLUMN is defined as "During all resize operations, apply adjustments to the last column only" which means you have to set the autoresizemode at the end of your code, otherwise setPreferredWidth() won't affect anything!

So in your case this would be the correct way:


How to pass command line arguments to a shell alias?

You may also find this command useful:

mkdir dirname && cd $_

where dirname is the name of the directory you want to create

jQuery datepicker years shown

au, nz, ie, etc. are the country codes for the countries whose national days are being displayed (Australia, New Zealand, Ireland, ...). As seen in the code, these values are combined with '_day' and passed back to be applied to that day as a CSS style. The corresponding styles are of the form show below, which moves the text for that day out of the way and replaces it with an image of the country's flag.

.au_day {
  text-indent: -9999px;
  background: #eee url(au.gif) no-repeat center;

The 'false' value that is passed back with the new style indicates that these days may not be selected.

import an array in python

Checkout the entry on the numpy example list. Here is the entry on .loadtxt()

>>> from numpy import *
>>> data = loadtxt("myfile.txt")                       # myfile.txt contains 4 columns of numbers
>>> t,z = data[:,0], data[:,3]                         # data is 2D numpy array
>>> t,x,y,z = loadtxt("myfile.txt", unpack=True)                  # to unpack all columns
>>> t,z = loadtxt("myfile.txt", usecols = (0,3), unpack=True)     # to select just a few columns
>>> data = loadtxt("myfile.txt", skiprows = 7)                    # to skip 7 rows from top of file
>>> data = loadtxt("myfile.txt", comments = '!')                  # use '!' as comment char instead of '#'
>>> data = loadtxt("myfile.txt", delimiter=';')                   # use ';' as column separator instead of whitespace
>>> data = loadtxt("myfile.txt", dtype = int)                     # file contains integers instead of floats

ZIP file content type for HTTP request

[request setValue:@"application/zip" forHTTPHeaderField:@"Content-Type"];

How to flush output after each `echo` call?

Sometimes, the problem come from Apache settings. Apache can be set to gzip the output. In the file .htaccess you can add for instance :

SetEnv no-gzip 1

How to get the date and time values in a C program?

using namespace std;

int main()

return 0;

How to hide console window in python?

This will hide your console. Implement these lines in your code first to start hiding your console at first.

import win32gui, win32con

the_program_to_hide = win32gui.GetForegroundWindow()
win32gui.ShowWindow(the_program_to_hide , win32con.SW_HIDE)

Update May 2020 :

If you've got trouble on pip install win32con on Command Prompt, you can simply pip install pywin32.Then on your python script, execute import win32.lib.win32con as win32con instead of import win32con.

To show back your program again win32con.SW_SHOW works fine:

win32gui.ShowWindow(the_program_to_hide , win32con.SW_SHOW)

How to thoroughly purge and reinstall postgresql on ubuntu?

I had a similar situation: I needed to purge postgresql 9.1 on a debian wheezy ( I had previously migrated from 8.4 and I was getting errors ).

What I did:

First, I deleted config and database

$ sudo pg_dropcluster --stop 9.1 main

Then removed postgresql

$ sudo apt-get remove --purge postgresql postgresql-9.1 

and then reinstalled

$ sudo apt-get install postgresql postgresql-9.1

In my case I noticed /etc/postgresql/9.1 was empty, and running service postgresql start returned nothing

So, after more googling I got to this command:

$ sudo pg_createcluster 9.1 main

With that I could start the server, but now I was getting log-related errors. After more searching, I ended up changing permissions to the /var/log/postgresql directory

$ sudo chown root.postgres /var/log/postgresql
$ sudo chmod g+wx /var/log/postgresql

That fixed the issue, Hope this helps

vertical & horizontal lines in matplotlib

The pyplot functions you are calling, axhline() and axvline() draw lines that span a portion of the axis range, regardless of coordinates. The parameters xmin or ymin use value 0.0 as the minimum of the axis and 1.0 as the maximum of the axis.

Instead, use plt.plot((x1, x2), (y1, y2), 'k-') to draw a line from the point (x1, y1) to the point (x2, y2) in color k. See pyplot.plot.

Conditional WHERE clause with CASE statement in Oracle

You can write the where clause as:

where (case when (:stateCode = '') then (1)
            when (:stateCode != '') and (vw.state_cd in (:stateCode)) then 1
            else 0)
       end) = 1;

Alternatively, remove the case entirely:

where (:stateCode = '') or
      ((:stateCode != '') and vw.state_cd in (:stateCode));

Or, even better:

where (:stateCode = '') or vw.state_cd in (:stateCode)

Change the selected value of a drop-down list with jQuery

After looking at some solutions, this worked for me.

I have one drop-down list with some values and I want to select the same value from another drop-down list... So first I put in a variable the selectIndex of my first drop-down.

var indiceDatos = $('#myidddl')[0].selectedIndex;

Then, I select that index on my second drop-down list.

$('#myidddl2')[0].selectedIndex = indiceDatos;


I guess this is the shortest, reliable, general and elegant solution.

Because in my case, I'm using selected option's data attribute instead of value attribute. So if you do not have unique value for each option, above method is the shortest and sweet!!

Android ListView headers

Here is a sample project, based on antew's detailed and helpful answer, that implements a ListView with multiple headers that incorporates view holders to improve scrolling performance.

In this project, the objects represented in the ListView are instances of either the class HeaderItem or the class RowItem, both of which are subclasses of the abstract class Item. Each subclass of Item corresponds to a different view type in the custom adapter, ItemAdapter. The method getView() on ItemAdapter delegates the creation of the view for each list item to an individualized getView() method on either HeaderItem or RowItem, depending on the Item subclass used at the position passed to the getView() method on the adapter. Each Item subclass provides its own view holder.

The view holders are implemented as follows. The getView() methods on the Item subclasses check whether the View object that was passed to the getView() method on ItemAdapter is null. If so, the appropriate layout is inflated, and a view holder object is instantiated and associated with the inflated view via View.setTag(). If the View object is not null, then a view holder object was already associated with the view, and the view holder is retrieved via View.getTag(). The way in which the view holders are used can be seen in the following code snippet from HeaderItem:

View getView(LayoutInflater i, View v) {
    ViewHolder h;
    if (v == null) {
        v = i.inflate(R.layout.header, null);
        h = new ViewHolder(v);
    } else {
        h = (ViewHolder) v.getTag();
    return v;

private class ViewHolder {
    final TextView category;

    ViewHolder(View v) {
        category = v.findViewById(;

The complete implementation of the ListView follows. Here is the Java code:

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class MainActivity extends ListActivity {
    protected void onCreate(Bundle savedInstanceState) {
        setListAdapter(new ItemAdapter(getItems()));

    class ItemAdapter extends ArrayAdapter<Item> {
        final private List<Class<?>> viewTypes;

        ItemAdapter(List<Item> items) {
            super(MainActivity.this, 0, items);
            if (items.contains(null))
                throw new IllegalArgumentException("null item");
            viewTypes = getViewTypes(items);

        private List<Class<?>> getViewTypes(List<Item> items) {
            Set<Class<?>> set = new HashSet<>();
            for (Item i : items) 
            List<Class<?>> list = new ArrayList<>(set);
            return Collections.unmodifiableList(list);

        public int getViewTypeCount() {
            return viewTypes.size();

        public int getItemViewType(int position) {
            Item t = getItem(position);
            return viewTypes.indexOf(t.getClass());

        public View getView(int position, View v, ViewGroup unused) {
            return getItem(position).getView(getLayoutInflater(), v);

    abstract private class Item {
        final private String text;

        Item(String text) {
            this.text = text;

        String text() { return text; }

        abstract View getView(LayoutInflater i, View v);

    private class HeaderItem extends Item {
        HeaderItem(String text) {

        View getView(LayoutInflater i, View v) {
            ViewHolder h;
            if (v == null) {
                v = i.inflate(R.layout.header, null);
                h = new ViewHolder(v);
            } else {
                h = (ViewHolder) v.getTag();
            return v;

        private class ViewHolder {
            final TextView category;

            ViewHolder(View v) {
                category = v.findViewById(;

    private class RowItem extends Item {
        RowItem(String text) {

        View getView(LayoutInflater i, View v) {
            ViewHolder h;
            if (v == null) {
                v = i.inflate(R.layout.row, null);
                h = new ViewHolder(v);
            } else {
                h = (ViewHolder) v.getTag();
            return v;

        private class ViewHolder {
            final TextView option;

            ViewHolder(View v) {
                option = v.findViewById(;

    private List<Item> getItems() {
        List<Item> t = new ArrayList<>();
        t.add(new HeaderItem("Header 1"));
        t.add(new RowItem("Row 2"));
        t.add(new HeaderItem("Header 3"));
        t.add(new RowItem("Row 4"));

        t.add(new HeaderItem("Header 5"));
        t.add(new RowItem("Row 6"));
        t.add(new HeaderItem("Header 7"));
        t.add(new RowItem("Row 8"));

        t.add(new HeaderItem("Header 9"));
        t.add(new RowItem("Row 10"));
        t.add(new HeaderItem("Header 11"));
        t.add(new RowItem("Row 12"));

        t.add(new HeaderItem("Header 13"));
        t.add(new RowItem("Row 14"));
        t.add(new HeaderItem("Header 15"));
        t.add(new RowItem("Row 16"));

        t.add(new HeaderItem("Header 17"));
        t.add(new RowItem("Row 18"));
        t.add(new HeaderItem("Header 19"));
        t.add(new RowItem("Row 20"));

        t.add(new HeaderItem("Header 21"));
        t.add(new RowItem("Row 22"));
        t.add(new HeaderItem("Header 23"));
        t.add(new RowItem("Row 24"));

        t.add(new HeaderItem("Header 25"));
        t.add(new RowItem("Row 26"));
        t.add(new HeaderItem("Header 27"));
        t.add(new RowItem("Row 28"));
        t.add(new RowItem("Row 29"));
        t.add(new RowItem("Row 30"));

        t.add(new HeaderItem("Header 31"));
        t.add(new RowItem("Row 32"));
        t.add(new HeaderItem("Header 33"));
        t.add(new RowItem("Row 34"));
        t.add(new RowItem("Row 35"));
        t.add(new RowItem("Row 36"));

        return t;


There are also two list item layouts, one for each Item subclass. Here is the layout header, used by HeaderItem:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""

And here is the layout row, used by RowItem:

<LinearLayout xmlns:android=""

Here is an image of a portion of the resulting ListView:

ListView with multiple headers

How to assign the output of a Bash command to a variable?





Notice no spaces after the equals sign.

Also as Mr. Weiss points out; you don't assign to $pwd, you assign to pwd.

MATLAB, Filling in the area between two sets of data, lines in one figure

Personally, I find it both elegant and convenient to wrap the fill function. To fill between two equally sized row vectors Y1 and Y2 that share the support X (and color C):

fill_between_lines = @(X,Y1,Y2,C) fill( [X fliplr(X)],  [Y1 fliplr(Y2)], C );

Multiple parameters in a List. How to create without a class?

Get Schema Name and Table Name from a database.

        public IList<Tuple<string, string>> ListTables()

            DataTable dt = con.GetSchema("Tables");

            var tables = new List<Tuple<string, string>>();

            foreach (DataRow row in dt.Rows)
            string schemaName = (string)row[1];
            string tableName = (string)row[2];
            tables.Add(Tuple.Create(schemaName, tableName));
            Console.WriteLine(schemaName +" " + tableName) ;
            return tables;

UIView's frame, bounds, center, origin, when to use what?

Marco's answer above is correct, but just to expand on the question of "under what context"...

frame - this is the property you most often use for normal iPhone applications. most controls will be laid out relative to the "containing" control so the frame.origin will directly correspond to where the control needs to display, and frame.size will determine how big to make the control.

center - this is the property you will likely focus on for sprite based games and animations where movement or scaling may occur. By default animation and rotation will be based on the center of the UIView. It rarely makes sense to try and manage such objects by the frame property.

bounds - this property is not a positioning property, but defines the drawable area of the UIView "relative" to the frame. By default this property is usually (0, 0, width, height). Changing this property will allow you to draw outside of the frame or restrict drawing to a smaller area within the frame. A good discussion of this can be found at the link below. It is uncommon for this property to be manipulated unless there is specific need to adjust the drawing region. The only exception is that most programs will use the [[UIScreen mainScreen] bounds] on startup to determine the visible area for the application and setup their initial UIView's frame accordingly.

Why is there an frame rectangle and an bounds rectangle in an UIView?

Hopefully this helps clarify the circumstances where each property might get used.

Add Legend to Seaborn point plot

I tried using Adam B's answer, however, it didn't work for me. Instead, I found the following workaround for adding legends to pointplots.

import matplotlib.patches as mpatches
red_patch = mpatches.Patch(color='#bb3f3f', label='Label1')
black_patch = mpatches.Patch(color='#000000', label='Label2')

In the pointplots, the color can be specified as mentioned in previous answers. Once these patches corresponding to the different plots are set up,

plt.legend(handles=[red_patch, black_patch])

And the legend ought to appear in the pointplot.

How to select only the records with the highest date in LINQ

If you want the whole record,here is a lambda way:

var q = _context
             .GroupBy(s => s.AccountId)
             .Select(s => s.OrderByDescending(x => x.Date).FirstOrDefault());

What is JSON and why would I use it?

JSON (JavaScript Object Notation) is a lightweight format that is used for data interchanging. It is based on a subset of JavaScript language (the way objects are built in JavaScript). As stated in the MDN, some JavaScript is not JSON, and some JSON is not JavaScript.

An example of where this is used is web services responses. In the 'old' days, web services used XML as their primary data format for transmitting back data, but since JSON appeared (The JSON format is specified in RFC 4627 by Douglas Crockford), it has been the preferred format because it is much more lightweight

You can find a lot more info on the official JSON web site.

JSON is built on two structures:

  • A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.
  • An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence.

JSON Structure

JSON Object diagram

JSON Array diagram

JSON Value diagram

JSON String diagram

JSON Number diagram

Here is an example of JSON data:

     "firstName": "John",
     "lastName": "Smith",
     "address": {
         "streetAddress": "21 2nd Street",
         "city": "New York",
         "state": "NY",
         "postalCode": 10021
     "phoneNumbers": [
         "212 555-1234",
         "646 555-4567"

JSON in JavaScript

JSON (in Javascript) is a string!

People often assume all Javascript objects are JSON and that JSON is a Javascript object. This is incorrect.

In Javascript var x = {x:y} is not JSON, this is a Javascript object. The two are not the same thing. The JSON equivalent (represented in the Javascript language) would be var x = '{"x":"y"}'. x is an object of type string not an object in it's own right. To turn this into a fully fledged Javascript object you must first parse it, var x = JSON.parse('{"x":"y"}');, x is now an object but this is not JSON anymore.

See Javascript object Vs JSON

When working with JSON and JavaScript, you may be tempted to use the eval function to evaluate the result returned in the callback, but this is not suggested since there are two characters (U+2028 & U+2029) valid in JSON but not in JavaScript (read more of this here).

Therefore, one must always try to use Crockford's script that checks for a valid JSON before evaluating it. Link to the script explanation is found here and here is a direct link to the js file. Every major browser nowadays has its own implementation for this.

Example on how to use the JSON parser (with the json from the above code snippet):

//The callback function that will be executed once data is received from the server
var callback = function (result) {
    var johnny = JSON.parse(result);
    //Now, the variable 'johnny' is an object that contains all of the properties 
    //from the above code snippet (the json example)
    alert(johnny.firstName + ' ' + johnny.lastName); //Will alert 'John Smith'

The JSON parser also offers another very useful method, stringify. This method accepts a JavaScript object as a parameter, and outputs back a string with JSON format. This is useful for when you want to send data back to the server:

var anObject = {name: "Andreas", surname : "Grech", age : 20};
var jsonFormat = JSON.stringify(anObject);
//The above method will output this: {"name":"Andreas","surname":"Grech","age":20}

The above two methods (parse and stringify) also take a second parameter, which is a function that will be called for every key and value at every level of the final result, and each value will be replaced by result of your inputted function. (More on this here)

Btw, for all of you out there who think JSON is just for JavaScript, check out this post that explains and confirms otherwise.


pandas GroupBy columns with NaN (missing) values

Ancient topic, if someone still stumbles over this--another workaround is to convert via .astype(str) to string before grouping. That will conserve the NaN's.

df = pd.DataFrame({'a': ['1', '2', '3'], 'b': ['4', np.NaN, '6']})
df['b'] = df['b'].astype(str)
4   1
6   3
nan 2

Sort a Custom Class List<T>

You are right - you need to implement IComparable. To do this, simply declare your class:

public MyClass : IComparable
  int IComparable.CompareTo(object obj)

In CompareTo, you just implement your custom comparison algorithm (you can use DateTime objects to do this, but just be certain to check the type of "obj" first). For further information, see here and here.

using BETWEEN in WHERE condition

You should use

$this->db->where('$accommodation >=', minvalue);
$this->db->where('$accommodation <=', maxvalue);

I'm not sure of syntax, so I beg your pardon if it's not correct.
Anyway BETWEEN is implemented using >=min && <=max.
This is the meaning of my example.

Looking at this link I think you could write:

$this->db->where("$accommodation BETWEEN $minvalue AND $maxvalue");

Change visibility of ASP.NET label with JavaScript

If you wait until the page is loaded, and then set the button's display to none, that should work. Then you can make it visible at a later point.

Unable to run Java GUI programs with Ubuntu

Use JFrame instead of Frame. And do not extend from JFrame. Just write a class that has a JFrame property named gui, which configures this JFrame with the available methods, because it is better style doing it like this. Extending here is wrong the use of OOP.

What is the meaning of the CascadeType.ALL for a @ManyToOne JPA association

See here for an example from the OpenJPA docs. CascadeType.ALL means it will do all actions.


CascadeType.PERSIST: When persisting an entity, also persist the entities held in its fields. We suggest a liberal application of this cascade rule, because if the EntityManager finds a field that references a new entity during the flush, and the field does not use CascadeType.PERSIST, it is an error.

CascadeType.REMOVE: When deleting an entity, it also deletes the entities held in this field.

CascadeType.REFRESH: When refreshing an entity, also refresh the entities held in this field.

CascadeType.MERGE: When merging entity state, also merge the entities held in this field.


How do I perform the SQL Join equivalent in MongoDB?

You can do it using the aggregation pipeline, but it's a pain to write it yourself.

You can use mongo-join-query to create the aggregation pipeline automatically from your query.

This is how your query would look like:

const mongoose = require("mongoose");
const joinQuery = require("mongo-join-query");

        find: { pid:444 },
        populate: ["uid"]
    (err, res) => (err ? console.log("Error:", err) : console.log("Success:", res.results))

Your result would have the user object in the uid field and you can link as many levels deep as you want. You can populate the reference to the user, which makes reference to a Team, which makes reference to something else, etc..

Disclaimer: I wrote mongo-join-query to tackle this exact problem.


Both are used for data transmission between client to server, but there are subtle differences between them, which are:

Enter image description here


  • PUT i.e. take and put where it was.
  • POST as send mail in post office.

enter image description here

Social Media/Network Analogy:

  • Post on social media: when we post message, it creates new post.
  • Put(i.e. edit) for the message we already Posted.

What does %w(array) mean?

I was given a bunch of columns from a CSV spreadsheet of full names of users and I needed to keep the formatting, with spaces. The easiest way I found to get them in while using ruby was to do:

names = %( Porter Smith
Jimmy Jones
Ronald Jackson).split('\n')

This highlights that %() creates a string like "Porter Smith\nJimmyJones\nRonald Jackson" and to get the array you split the string on the "\n" ["Porter Smith", "Jimmy Jones", "Ronald Jackson"]

So to answer the OP's original question too, they could have wrote %(cgi\ spaeinfilename.rb;complex.rb;date.rb).split(';') if there happened to be space when you want the space to exist in the final array output.

Why does javascript map function return undefined?

You can implement like a below logic. Suppose you want an array of values.

let test = [ {name:'test',lastname:'kumar',age:30},

let result1 = => 
                 if (element.age === 30) 
                    return element.lastname;
              }).filter(notUndefined => notUndefined !== undefined);

output : ['kumar','kumar','kumar']

Auto generate function documentation in Visual Studio

In visual basic, if you create your function/sub first, then on the line above it, you type ' three times, it will auto-generate the relevant xml for documentation. This also shows up when you mouseover in intellisense, and when you are making use of the function.

jquery: animate scrollLeft

First off I should point out that css animations would probably work best if you are doing this a lot but I ended getting the desired effect by wrapping .scrollLeft inside .animate


    $('.swipeBox').animate( { scrollLeft: '+=460' }, 1000);

    $('.swipeBox').animate( { scrollLeft: '-=460' }, 1000);

The second parameter is speed, and you can also add a third parameter if you are using smooth scrolling of some sort.

byte[] to file in Java

Another solution using java.nio.file:

byte[] bytes = ...;
Path path = Paths.get("C:\\myfile.pdf");
Files.write(path, bytes);

React-Router: No Not Found Route?

In newer versions of react-router you want to wrap the routes in a Switch which only renders the first matched component. Otherwise you would see multiple components rendered.

For example:

import React from 'react';
import ReactDOM from 'react-dom';
import {
  BrowserRouter as Router,
} from 'react-router-dom';

import App from './app/App';
import Welcome from './app/Welcome';
import NotFound from './app/NotFound';

const Root = () => (
  <Router history={browserHistory}>
      <Route exact path="/" component={App}/>
      <Route path="/welcome" component={Welcome}/>
      <Route component={NotFound}/>


Insert some string into given string at given index in Python

Answer for Insert characters of string in other string al located positions

str1 = "ibuprofen"
str2 = "MEDICAL"
Value = 2
result=[str1[i:i+Value] for i in range(0, len(str1), Value)]
count = 0

for letter in result:
    if count < len(result)-1:
        final_string = letter + str2[count]
    elif ((len(result)-1)==count):
        list2.append(letter + str2[count:len(str2)])
    count += 1


C# - Print dictionary

More cleaner way using LINQ

var lines = dictionary.Select(kvp => kvp.Key + ": " + kvp.Value.ToString());
textBox3.Text = string.Join(Environment.NewLine, lines);

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

The currently accepted answer doesn't always work.

(To read about the problem and circumstances, read this: Defined function is "Not defined".)

So, you have 3 options:

1 (it has above-mentioned drawback)

<input type="checkbox" onchange="doAlert(this)">

function doAlert(checkboxElem) {
    if (checkboxElem.checked) {
        alert ('hi');
    } else {
        alert ('bye');

2 and 3

<input type="checkbox" id="foo">

function doAlert() {
    var input = document.querySelector('#foo');

    // input.addEventListener('change', function() { ... });
    // or
    // input.onchange = function() { ... };
    input.addEventListener('change', function() {
        if (input.checked) {
            alert ('hi');
        } else {
            alert ('bye');


Vue.js - How to properly watch for nested data

How if you want to watch a property for a while and then to un-watch it?

Or to watch a library child component property?

You can use the "dynamic watcher":

 '', //what you want to watch
 (newVal, oldVal) => {
    //execute your code here

The $watch returns an unwatch function which will stop watching if it is called.

var unwatch = vm.$watch('a', cb)
// later, teardown the watcher

Also you can use the deep option:

'someObject', () => {
    //execute your code here
{ deep: true }

Please make sure to take a look to docs

How to build a DataTable from a DataGridView?

one of best solution enjoyed it ;)

  public DataTable GetContentAsDataTable(bool IgnoreHideColumns=false)
                if (dgv.ColumnCount == 0) return null;
                DataTable dtSource = new DataTable();
                foreach (DataGridViewColumn col in dgv.Columns)
                    if (IgnoreHideColumns & !col.Visible) continue;
                    if (col.Name == string.Empty) continue;
                    dtSource.Columns.Add(col.Name, col.ValueType);
                    dtSource.Columns[col.Name].Caption = col.HeaderText;
                if (dtSource.Columns.Count == 0) return null;
                foreach (DataGridViewRow row in dgv.Rows)
                    DataRow drNewRow = dtSource.NewRow();
                    foreach (DataColumn  col in dtSource .Columns)
                        drNewRow[col.ColumnName] = row.Cells[col.ColumnName].Value;
                return dtSource;
            catch { return null; }

Run jQuery function onclick

Using obtrusive JavaScript (i.e. inline code) as in your example, you can attach the click event handler to the div element with the onclick attribute like so:

 <div id="some-id" class="some-class" onclick="slideonlyone('sms_box');">

However, the best practice is unobtrusive JavaScript which you can easily achieve by using jQuery's on() method or its shorthand click(). For example:

 $(document).ready( function() {
     $('.some-class').on('click', slideonlyone('sms_box'));
     // OR //

Inside your handler function (e.g. slideonlyone() in this case) you can reference the element that triggered the event (e.g. the div in this case) with the $(this) object. For example, if you need its ID, you can access it with $(this).attr('id').


After reading your comment to @fmsf below, I see you also need to dynamically reference the target element to be toggled. As @fmsf suggests, you can add this information to the div with a data-attribute like so:

<div id="some-id" class="some-class" data-target="sms_box">

To access the element's data-attribute you can use the attr() method as in @fmsf's example, but the best practice is to use jQuery's data() method like so:

 function slideonlyone() {
     var trigger_id = $(this).attr('id'); // This would be 'some-id' in our example
     var target_id  = $(this).data('target'); // This would be 'sms_box'

Note how data-target is accessed with data('target'), without the data- prefix. Using data-attributes you can attach all sorts of information to an element and jQuery would automatically add them to the element's data object.

Extract the first word of a string in a SQL Server query

     WHEN 0 THEN @Foo -- empty or single word
     ELSE SUBSTRING(@Foo, 1, CHARINDEX(' ', @Foo, 1) - 1) -- multi-word

You could perhaps use this in a UDF:

CREATE FUNCTION [dbo].[FirstWord] (@value varchar(max))
RETURNS varchar(max)
    RETURN CASE CHARINDEX(' ', @value, 1)
        WHEN 0 THEN @value
        ELSE SUBSTRING(@value, 1, CHARINDEX(' ', @value, 1) - 1) END
GO -- test:
SELECT dbo.FirstWord(NULL)
SELECT dbo.FirstWord('')
SELECT dbo.FirstWord('abc')
SELECT dbo.FirstWord('abc def')
SELECT dbo.FirstWord('abc def ghi')

Round number to nearest integer

I use and may advise the following solution (python3.6):

y = int(x + (x % (1 if x >= 0 else -1)))

It works fine for half-numbers (positives and negatives) and works even faster than int(round(x)):

round_methods = [lambda x: int(round(x)), 
                 lambda x: int(x + (x % (1 if x >= 0 else -1))),
                 lambda x: np.rint(x).astype(int),
                 lambda x: int(proper_round(x))]

for rm in round_methods:
    %timeit rm(112.5)
201 ns ± 3.96 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
159 ns ± 0.646 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
925 ns ± 7.66 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
1.18 µs ± 8.66 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

for rm in round_methods:
    print(rm(112.4), rm(112.5), rm(112.6))
    print(rm(-12.4), rm(-12.5), rm(-12.6))
    print('=' * 11)

112 112 113
-12 -12 -13
112 113 113
-12 -13 -13
112 112 113
-12 -12 -13
112 113 113
-12 -13 -13

Collections.emptyList() returns a List<Object>?

Since Java 8 this kind of code compiles as expected and the type parameter gets inferred by the compiler.

public Person(String name) {
    this(name, Collections.emptyList()); // Inferred to List<String> in Java 8

public Person(String name, List<String> nicknames) { = name;
    this.nicknames = nicknames;

The new thing in Java 8 is that the target type of an expression will be used to infer type parameters of its sub-expressions. Before Java 8 only direct assignments and arguments to methods where used for type parameter inference.

In this case the parameter type of the constructor will be the target type for Collections.emptyList(), and the return value type will get chosen to match the parameter type.

This mechanism was added in Java 8 mainly to be able to compile lambda expressions, but it improves type inferences generally.

Java is getting closer to proper Hindley–Milner type inference with every release!

IN vs OR in the SQL WHERE Clause

I think oracle is smart enough to convert the less efficient one (whichever that is) into the other. So I think the answer should rather depend on the readability of each (where I think that IN clearly wins)

How can I install packages using pip according to the requirements.txt file from a local directory?

This works for me:

$ pip install -r requirements.txt --no-index --find-links file:///tmp/packages

--no-index - Ignore package index (only looking at --find-links URLs instead).

-f, --find-links <URL> - If a URL or path to an HTML file, then parse for links to archives.

If a local path or file:// URL that's a directory, then look for archives in the directory listing.