Programs & Examples On #Storage class specifier

String comparison in bash. [[: not found

I had this problem when installing Heroku Toolbelt

This is how I solved the problem

$ ls -l /bin/sh
lrwxrwxrwx 1 root root 4 ago 15  2012 /bin/sh -> dash

As you can see, /bin/sh is a link to "dash" (not bash), and [[ is bash syntactic sugarness. So I just replaced the link to /bin/bash. Careful using rm like this in your system!

$ sudo rm /bin/sh
$ sudo ln -s /bin/bash /bin/sh

List all files from a directory recursively with Java

Just so you know isDirectory() is quite a slow method. I'm finding it quite slow in my file browser. I'll be looking into a library to replace it with native code.

How to create a JPA query with LEFT OUTER JOIN

If you have entities A and B without any relation between them and there is strictly 0 or 1 B for each A, you could do:

select a, (select b from B b where b.joinProperty = a.joinProperty) from A a

This would give you an Object[]{a,b} for a single result or List<Object[]{a,b}> for multiple results.

How to sum a list of integers with java streams?

class Pojo{
    int num;

    public Pojo(int num) {
        this.num = num;

    public int getNum() {
        return num;

    public void setNum(int num) {
        this.num = num;

List<Pojo> list = new ArrayList<Pojo>();
            list.add(new Pojo(1));
            list.add(new Pojo(5));
            list.add(new Pojo(3));
            list.add(new Pojo(4));
            list.add(new Pojo(5));

            int totalSum = -> pojo.getNum()).sum();

How do I detect if I am in release or debug mode?

Make sure that you are importing the correct BuildConfig class And yes, you will have no problems using:

if (BuildConfig.DEBUG) {
   //It's not a release version.

Downloading an entire S3 bucket?

The answer by @Layke is good, but if you have a ton of data and don't want to wait forever, you should read "AWS CLI S3 Configuration".

The following commands will tell the AWS CLI to use 1,000 threads to execute jobs (each a small file or one part of a multipart copy) and look ahead 100,000 jobs:

aws configure set default.s3.max_concurrent_requests 1000
aws configure set default.s3.max_queue_size 100000

After running these, you can use the simple sync command:

aws s3 sync s3://source-bucket/source-path s3://destination-bucket/destination-path


aws s3 sync s3://source-bucket/source-path c:\my\local\data\path

On a system with CPU 4 cores and 16GB RAM, for cases like mine (3-50GB files) the sync/copy speed went from about 9.5MiB/s to 700+MiB/s, a speed increase of 70x over the default configuration.

Remove '\' char from string c#

Try using

String sOld = ...;
String sNew =     sOld.Replace("\\", String.Empty);

What is a "callable"?

From Python's sources object.c:

/* Test whether an object can be called */

PyCallable_Check(PyObject *x)
    if (x == NULL)
        return 0;
    if (PyInstance_Check(x)) {
        PyObject *call = PyObject_GetAttrString(x, "__call__");
        if (call == NULL) {
            return 0;
        /* Could test recursively but don't, for fear of endless
           recursion if some joker sets self.__call__ = self */
        return 1;
    else {
        return x->ob_type->tp_call != NULL;

It says:

  1. If an object is an instance of some class then it is callable iff it has __call__ attribute.
  2. Else the object x is callable iff x->ob_type->tp_call != NULL

Desciption of tp_call field:

ternaryfunc tp_call An optional pointer to a function that implements calling the object. This should be NULL if the object is not callable. The signature is the same as for PyObject_Call(). This field is inherited by subtypes.

You can always use built-in callable function to determine whether given object is callable or not; or better yet just call it and catch TypeError later. callable is removed in Python 3.0 and 3.1, use callable = lambda o: hasattr(o, '__call__') or isinstance(o, collections.Callable).

Example, a simplistic cache implementation:

class Cached:
    def __init__(self, function):
        self.function = function
        self.cache = {}

    def __call__(self, *args):
        try: return self.cache[args]
        except KeyError:
            ret = self.cache[args] = self.function(*args)
            return ret    


def ack(x, y):
    return ack(x-1, ack(x, y-1)) if x*y else (x + y + 1) 

Example from standard library, file, definition of built-in exit() and quit() functions:

class Quitter(object):
    def __init__(self, name): = name
    def __repr__(self):
        return 'Use %s() or %s to exit' % (, eof)
    def __call__(self, code=None):
        # Shells like IDLE catch the SystemExit, but listen when their
        # stdin wrapper is closed.
        raise SystemExit(code)
__builtin__.quit = Quitter('quit')
__builtin__.exit = Quitter('exit')

Selecting the last value of a column

Actually I found a simpler solution here:

It looks like this:

=FILTER( A10:A100 , ROW(A10:A100) =MAX( FILTER( ArrayFormula(ROW(A10:A100)) , NOT(ISBLANK(A10:A100)))))

What CSS selector can be used to select the first div within another div

The closest thing to what you're looking for is the :first-child pseudoclass; unfortunately this will not work in your case because you have an <h1> before the <div>s. What I would suggest is that you either add a class to the <div>, like <div class="first"> and then style it that way, or use jQuery if you really can't add a class:

$('#content > div:first')

How to find substring from string?

If you are utilizing arrays too much then you should include cstring.h because it has too many functions including finding substrings.

Angular2: custom pipe could not be found

see this is working for me.

ActStatus.pipe.ts First this is my pipe

import {Pipe,PipeTransform} from "@angular/core";

export class ActStatusPipe implements PipeTransform{
    switch (status) {
      case 1:
        return "UN_PUBLISH";
      case 2:
        return "PUBLISH";
        return status

main-pipe.module.ts in pipe module, i need to declare my pipe/s and export it.

import { NgModule } from '@angular/core';
import {CommonModule} from "@angular/common";

import {ActStatusPipe} from "./ActStatusPipe.pipe"; // <---

  declarations:[ActStatusPipe], // <---
  exports:[ActStatusPipe] // <---

export class MainPipe{}

app.module.ts user this pipe module in any module.

  declarations: [...],
  imports: [..., MainPipe], // <---
  providers: [...],
  bootstrap: [AppComponent]

you can directly user pipe in this module. but if you feel that your pipe is used with in more than one component i suggest you to follow my approach.

  1. create pipe .
  2. create separate module and declare and export one or more pipe.
  3. user that pipe module.

How to use pipe totally depends on your project complexity and requirement. you might have just one pipe which used only once in the whole project. in that case you can directly use it without creating a pipe/s module (module approach).

adb devices command not working

restarting the adb server as root worked for me. see:

derek@zoe:~/Downloads$ adb sideload 
loading: ''
error: insufficient permissions for device
derek@zoe:~/Downloads$ adb devices
List of devices attached
XXXXXXXXXXXXXXXX    no permissions

derek@zoe:~/Downloads$ adb kill-server
derek@zoe:~/Downloads$ sudo adb start-server
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
derek@zoe:~/Downloads$ adb devices
List of devices attached

In SQL Server, how do I generate a CREATE TABLE statement for a given table?

Here's the script that I came up with. It handles Identity columns, default values, and primary keys. It does not handle foreign keys, indexes, triggers, or any other clever stuff. It works on SQLServer 2000, 2005 and 2008.

declare @schema varchar(100), @table varchar(100)
set @schema = 'dbo' -- set schema name here
set @table = 'MyTable' -- set table name here
declare @sql table(s varchar(1000), id int identity)

-- create statement
insert into  @sql(s) values ('create table [' + @table + '] (')

-- column list
insert into @sql(s)
    '  ['+column_name+'] ' + 
    data_type + coalesce('('+cast(character_maximum_length as varchar)+')','') + ' ' +
    case when exists ( 
        select id from syscolumns
        where object_name(id)=@table
        and name=column_name
        and columnproperty(id,name,'IsIdentity') = 1 
    ) then
        'IDENTITY(' + 
        cast(ident_seed(@table) as varchar) + ',' + 
        cast(ident_incr(@table) as varchar) + ')'
    else ''
    end + ' ' +
    ( case when IS_NULLABLE = 'No' then 'NOT ' else '' end ) + 'NULL ' + 
    coalesce('DEFAULT '+COLUMN_DEFAULT,'') + ','

 from INFORMATION_SCHEMA.COLUMNS where table_name = @table AND table_schema = @schema
 order by ordinal_position

-- primary key
declare @pkname varchar(100)
select @pkname = constraint_name from INFORMATION_SCHEMA.TABLE_CONSTRAINTS
where table_name = @table and constraint_type='PRIMARY KEY'

if ( @pkname is not null ) begin
    insert into @sql(s) values('  PRIMARY KEY (')
    insert into @sql(s)
        where constraint_name = @pkname
        order by ordinal_position
    -- remove trailing comma
    update @sql set s=left(s,len(s)-1) where id=@@identity
    insert into @sql(s) values ('  )')
else begin
    -- remove trailing comma
    update @sql set s=left(s,len(s)-1) where id=@@identity

-- closing bracket
insert into @sql(s) values( ')' )

-- result!
select s from @sql order by id

Override hosts variable of Ansible playbook from the command line

I'm using another approach that doesn't need any inventory and works with this simple command:

ansible-playbook site.yml -e working_host=myhost

To perform that, you need a playbook with two plays:

  • first play runs on localhost and add a host (from given variable) in a known group in inmemory inventory
  • second play runs on this known group

A working example (copy it and runs it with previous command):

- hosts: localhost
  connection: local
  - add_host:
      name: "{{ working_host }}"
      groups: working_group
    changed_when: false

- hosts: working_group
  gather_facts: false
  - debug:
      msg: "I'm on {{ ansible_host }}"

I'm using ansible 2.4.3 and 2.3.3

Apache 2.4.3 (with XAMPP 1.8.1) not starting in windows 8

Enter services.msc and shutdown anything SQL you have running. The SQL server might be taking over the port.

When is it acceptable to call GC.Collect?

The short answer is: never!

How do I add a library project to Android Studio?

I would consider Dependencies, Android Libraries and Multi-project setup necessary reading. Please take a few minutes to do so.

Particularly, in the case of a non-jar library project, read the following snippet from above source:

Gradle projects can also depend on other gradle projects by using a multi-project setup. A multi-project setup usually works by having all the projects as sub folders of a given root project.

For instance, given to following structure:

 + app/
 + libraries/
    + lib1/
    + lib2/

We can identify 3 projects. Gradle will reference them with the following name:


Each projects will have its own build.gradle declaring how it gets built. Additionally, there will be a file called settings.gradle at the root declaring the projects. This gives the following structure:

 | settings.gradle
 + app/
    | build.gradle
 + libraries/
    + lib1/
       | build.gradle
    + lib2/
       | build.gradle

The content of settings.gradle is very simple:

include ':app', ':libraries:lib1', ':libraries:lib2'

This defines which folder is actually a Gradle project.

The :app project is likely to depend on the libraries, and this is done by declaring the following dependencies:

dependencies {
    compile project(':libraries:lib1')

Kindly note that there was little or no use of Android Studio GUI to make this happen.

I am currently using git submodules to link the nested library to the actual library git repo to avoid a dependency mess.

How to make an Android device vibrate? with different frequency?

Vibrate without using permission

If you want to simply vibrate the device once to provide a feedback on a user action. You can use performHapticFeedback() function of a View. This doesn't need the VIBRATE permission to be declared in the manifest.

Use the following function as a top level function in some common class like Utils.kt of your project:

 * Vibrates the device. Used for providing feedback when the user performs an action.
fun vibrate(view: View) {

And then use it anywhere in your Fragment or Activity as following:


Simple as that!

How can I include null values in a MIN or MAX?

Use IsNull

SELECT recordid, MIN(startdate), MAX(IsNull(enddate, Getdate()))
FROM tmp 
GROUP BY recordid

I've modified MIN in the second instruction to MAX

How do I convert from int to Long in Java?

If you already have the int typed as an Integer you can do this:

Integer y = 1;
long x = y.longValue();

How to convert a char array back to a string?

Try this:

CharSequence[] charArray = {"a","b","c"};

for (int i = 0; i < charArray.length; i++){
    String str = charArray.toString().join("", charArray[i]);

minimize app to system tray

...and for your right click notification menu add a context menu to the form and edit it and set mouseclick events for each of contextmenuitems by double clicking them and then attach it to the notifyicon1 by selecting the ContextMenuStrip in notifyicon property.

javax.xml.bind.UnmarshalException: unexpected element. Expected elements are (none)

Alternatively if you want to persist in using the DocumentType class. Then you could just add the following annotation on top of your DocumentType class.


Note: the String value "document" refers to the name of the root tag of the xml message.

Login failed for user 'NT AUTHORITY\NETWORK SERVICE'

Make sure that the database is created. I got the same error when I applied the migration to the wrong project in the solution. When I applied the migration to the right project, it created the database and that solved the error.

Open application after clicking on Notification

public void addNotification()
    NotificationCompat.Builder mBuilder=new NotificationCompat.Builder(MainActivity.this);
    mBuilder.setContentTitle("Notification Alert, Click Me!");
    mBuilder.setContentText("Hi,This notification for you let me check");
    Intent notificationIntent = new Intent(this,MainActivity.class);
    PendingIntent conPendingIntent = PendingIntent.getActivity(this,0,notificationIntent,PendingIntent.FLAG_UPDATE_CURRENT);


    NotificationManager manager=(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
    Toast.makeText(MainActivity.this, "Notification", Toast.LENGTH_SHORT).show();


How can I trim beginning and ending double quotes from a string?

If the double quotes only exist at the beginning and the end, a simple code as this would work perfectly:

string = string.replace("\"", "");

Eclipse projects not showing up after placing project files in workspace/projects

I have tried many of the option suggested but at last importing project in new workspace solved my problem.

I think there is some problem in metadata files in old workspace.

PDO::__construct(): Server sent charset (255) unknown to the client. Please, report to the developers

I had this problem also. The issue was because I was running an old version of PHP (5.6) and once I upgraded to PHP 7.4 the errors went away.

This was on Amazon Linux 2 for me and the command to upgrade was:

amazon-linux-extras install php7.4

Other flavors of *nix might have it in their repositories otherwise if you're on a flavor of Linux then Remi might have it for you here:

ASP.NET Web API - PUT & DELETE Verbs Not Allowed - IIS 8

Enable CORS (nice and neat)

1.Add CORS nuget package

Install-Package microsoft.aspnet.webapi.cors the WebApiConfig.cs file to Register method add bellow code :


using System.Web.Http;

namespace test
public static class WebApiConfig
    public static void Register(HttpConfiguration config)
        // Web API configuration and services

        config.EnableCors(); //add this**************************

        // Web API routes

            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }

3.Add bellow code into namespace of the controller include get,post,delete,put or any http method

[EnableCors(origins: "The address from which the request comes", headers: "*", methods: "*")]


using System.Web.Http.Cors;//add this******************************
namespace Test.Controllers
[EnableCors(origins: "http://localhost:53681/HTML/Restaurant.html", headers: "*", methods: "*")]
public class RestaurantController : ApiController
    protected TestBusinessLayer DevTestBLL = new TestBusinessLayer();

    public List<Restaurant> GET()
        return DevTestBLL.GetRestaurant();

    public List<Restaurant> DELETE(int id)
        return DevTestBLL.DeleteRestaurant(id);

reference :

How to parse a JSON object to a TypeScript Object

The reason that the compiler lets you cast the object returned from JSON.parse to a class is because typescript is based on structural subtyping.
You don't really have an instance of an Employee, you have an object (as you see in the console) which has the same properties.

A simpler example:

class A {
    constructor(public str: string, public num: number) {}

function logA(a: A) {
    console.log(`A instance with str: "${ a.str }" and num: ${ a.num }`);

let a1 = { str: "string", num: 0, boo: true };
let a2 = new A("stirng", 0);
logA(a1); // no errors

(code in playground)

There's no error because a1 satisfies type A because it has all of its properties, and the logA function can be called with no runtime errors even if what it receives isn't an instance of A as long as it has the same properties.

That works great when your classes are simple data objects and have no methods, but once you introduce methods then things tend to break:

class A {
    constructor(public str: string, public num: number) { }

    multiplyBy(x: number): number {
        return this.num * x;

// this won't compile:
let a1 = { str: "string", num: 0, boo: true } as A; // Error: Type '{ str: string; num: number; boo: boolean; }' cannot be converted to type 'A'

// but this will:
let a2 = { str: "string", num: 0 } as A;

// and then you get a runtime error:
a2.multiplyBy(4); // Error: Uncaught TypeError: a2.multiplyBy is not a function

(code in playground)


This works just fine:

const employeeString = '{"department":"<anystring>","typeOfEmployee":"<anystring>","firstname":"<anystring>","lastname":"<anystring>","birthdate":"<anydate>","maxWorkHours":0,"username":"<anystring>","permissions":"<anystring>","lastUpdate":"<anydate>"}';
let employee1 = JSON.parse(employeeString);

(code in playground)

If you're trying to use JSON.parse on your object when it's not a string:

let e = {
    "department": "<anystring>",
    "typeOfEmployee": "<anystring>",
    "firstname": "<anystring>",
    "lastname": "<anystring>",
    "birthdate": "<anydate>",
    "maxWorkHours": 3,
    "username": "<anystring>",
    "permissions": "<anystring>",
    "lastUpdate": "<anydate>"
let employee2 = JSON.parse(e);

Then you'll get the error because it's not a string, it's an object, and if you already have it in this form then there's no need to use JSON.parse.

But, as I wrote, if you're going with this way then you won't have an instance of the class, just an object that has the same properties as the class members.

If you want an instance then:

let e = new Employee();
Object.assign(e, {
    "department": "<anystring>",
    "typeOfEmployee": "<anystring>",
    "firstname": "<anystring>",
    "lastname": "<anystring>",
    "birthdate": "<anydate>",
    "maxWorkHours": 3,
    "username": "<anystring>",
    "permissions": "<anystring>",
    "lastUpdate": "<anydate>"

Convert absolute path into relative path given a current directory using Bash

Here's a shell script that does it without calling other programs:

#! /bin/env bash 

#bash script to find the relative path between two directories


shopt -s extglob

relpath_ () {
        path1=$("$creadlink" "$1")
        path2=$("$creadlink" "$2")

        while :; do
                if test ! "$path1"; then
                if test "${part1#/}" = "$part1"; then
                if test "${path2#$path1}" = "$path2"; then
        if test ! "$path1"; then
        printf "$path1"


relpath_test () {
        res=$(relpath_ /path1/to/dir1 /path1/to/dir2 )
        test_results "$res" "$expected"

        res=$(relpath_ / /path1/to/dir2 )
        test_results "$res" "$expected"

        res=$(relpath_ /path1/to/dir2 / )
        test_results "$res" "$expected"

        res=$(relpath_ / / )
        test_results "$res" "$expected"

        res=$(relpath_ /path/to/dir2/dir3 /path/to/dir1/dir4/dir4a )
        test_results "$res" "$expected"

        res=$(relpath_ /path/to/dir1/dir4/dir4a /path/to/dir2/dir3 )
        test_results "$res" "$expected"

        #res=$(relpath_ . /path/to/dir2/dir3 )
        #test_results "$res" "$expected"

test_results () {
        if test ! "$1" = "$2"; then
                printf 'failed!\nresult:\nX%sX\nexpected:\nX%sX\n\n' "$@"



hasOwnProperty in JavaScript

hasOwnProperty expects the property name as a string, so it would be shape1.hasOwnProperty("name")

How do I make an HTML button not reload the page

As stated in one of the comments (burried) above, this can be fixed by not placing the button tag inside the form tag. When the button is outside the form, the page does not refresh itself.

How to remove an iOS app from the App Store

You can "Deselect All" to remove the app (temporarily) from all App Stores, as Noah mentioned.

And you can "Select All" to get the App back to all App Stores.

You can find it in: iTunes Connect Link

use a javascript array to fill up a drop down select box

This is a part from a REST-Service I´ve written recently.

var select = $("#productSelect")
for (var prop in data) {
    var option = document.createElement('option');
    option.innerHTML = data[prop].ProduktName
    option.value = data[prop].ProduktName;

The reason why im posting this is because appendChild() wasn´t working in my case so I decided to put up another possibility that works aswell.

Access denied for user 'test'@'localhost' (using password: YES) except root user

Make sure the user has a localhost entry in the users table. That was the problem I was having. EX:

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

How can I convert a string to an int in Python?

While calling your sub functions from your main functions you can convert the variables into int and then call. Please refer the below code:

import sys

print("Welcome to Calculator\n")
print("Please find the options:\n" + "1. Addition\n" + "2. Subtraction\n" + 
"3. Multiplication\n" + "4. Division\n" + "5. Exponential\n" + "6. Quit\n")

def calculator():
    choice = input("Enter choice\n")

    if int(choice) == 1:
        a = input("Enter first number\n")
        b = input("Enter second number\n")
        add(int(a), int(b))

    if int(choice) == 2:
        a = input("Enter first number\n")
        b = input("Enter second number\n")
        diff(int(a), int(b))

    if int(choice) == 3:
        a = input("Enter first number\n")
        b = input("Enter second number\n")
        mult(int(a), int(b))

    if int(choice) == 4:
        a = input("Enter first number\n")
        b = input("Enter second number\n")
        div(float(a), float(b))

    if int(choice) == 5:
        a = input("Enter the base number\n")
        b = input("Enter the exponential\n")
        exp(int(a), int(b))

    if int(choice) == 6:

def add(a, b):
    c = a+b
    print("Sum of {} and {} is {}".format(a, b, c))

def diff(a,b):
    c = a-b
    print("Difference between {} and {} is {}".format(a, b, c))

def mult(a, b):
    c = a*b
    print("The Product of {} and {} is {}".format(a, b, c))

def div(a, b):
    c = a/b
    print("The Quotient of {} and {} is {}".format(a, b, c))

def exp(a, b):
    c = a**b
    print("The result of {} to the power of {} is {}".format(a, b, c))


Here what I did is I called each of the function while converting the parameters inputted to int. I hope this has been helpful.

In your case it could be changed like this:

 if choice == "0":
        numberA = raw_input("Enter your first number: ")
        numberB = raw_input("Enter your second number: ")
        print "Your result is:"
        print addition(int(numberA), int(numberB))

Does bootstrap have builtin padding and margin classes?

Bootstrap 4 has a new notation for margin and padding classes. Refer to Bootstrap 4.0 Documentation - Spacing.

From the documentation:


Spacing utilities that apply to all breakpoints, from xs to xl, have no breakpoint abbreviation in them. This is because those classes are applied from min-width: 0 and up, and thus are not bound by a media query. The remaining breakpoints, however, do include a breakpoint abbreviation.

The classes are named using the format {property}{sides}-{size} for xs and {property}{sides}-{breakpoint}-{size} for sm, md, lg, and xl.


.mt-0 { margin-top: 0 !important; }

.p-3 { padding: $spacer !important; }

Why is there no Constant feature in Java?

What does const mean
First, realize that the semantics of a "const" keyword means different things to different people:

  • read-only reference - Java final semantics - reference variable itself cannot be reassigned to point to another instance (memory location), but the instance itself is modifiable
  • readable-only reference - C const pointer/reference semantics - means this reference cannot be used to modify the instance (e.g. cannot assign to instance variables, cannot invoke mutable methods) - affects the reference variable only, so a non-const reference pointing to the same instance could modify the instance
  • immutable object - means the instance itself cannot be modified - applies to instance, so any non-const reference would not be allowed or could not be used to modify the instance
  • some combination of the the above?
  • others?

Why or Why Not const
Second, if you really want to dig into some of the "pro" vs "con" arguments, see the discussion under this request for enhancement (RFE) "bug". This RFE requests a "readable-only reference"-type "const" feature. Opened in 1999 and then closed/rejected by Sun in 2005, the "const" topic was vigorously debated:

While there are a lot of good arguments on both sides, some of the oft-cited (but not necessarily compelling or clear-cut) reasons against const include:

  • may have confusing semantics that may be misused and/or abused (see the What does const mean above)
  • may duplicate capability otherwise available (e.g. designing an immutable class, using an immutable interface)
  • may be feature creep, leading to a need for other semantic changes such as support for passing objects by value

Before anyone tries to debate me about whether these are good or bad reasons, note that these are not my reasons. They are simply the "gist" of some of the reasons I gleaned from skimming the RFE discussion. I don't necessarily agree with them myself - I'm simply trying to cite why some people (not me) may feel a const keyword may not be a good idea. Personally, I'd love more "const" semantics to be introduced to the language in an unambiguous manner.

How do I reset the setInterval timer?

If by "restart", you mean to start a new 4 second interval at this moment, then you must stop and restart the timer.

function myFn() {console.log('idle');}

var myTimer = setInterval(myFn, 4000);

// Then, later at some future time, 
// to restart a new 4 second interval starting at this exact moment in time
myTimer = setInterval(myFn, 4000);

You could also use a little timer object that offers a reset feature:

function Timer(fn, t) {
    var timerObj = setInterval(fn, t);

    this.stop = function() {
        if (timerObj) {
            timerObj = null;
        return this;

    // start timer using current settings (if it's not already running)
    this.start = function() {
        if (!timerObj) {
            timerObj = setInterval(fn, t);
        return this;

    // start with new or original interval, stop current interval
    this.reset = function(newT = t) {
        t = newT;
        return this.stop().start();


var timer = new Timer(function() {
    // your function here
}, 5000);

// switch interval to 10 seconds

// stop the timer

// start the timer

Working demo:

Syntax of for-loop in SQL Server

Try it, learn it:

DECLARE @F varchar(max) = ''
WHILE @i < @r

    DECLARE @j INT = 0
    DECLARE @o varchar(max) = ''
    WHILE @j < @r - @i - 1
        SET @o = @o + ' '
        SET @j += 1

    DECLARE @k INT = 0
    WHILE @k < @i + 1
        SET @o = @o + ' *'  -- '*'
        SET @k += 1
    SET @i += 1
    SET @F = @F + @o + CHAR(13)

With date:

DECLARE @d DATE = '2019-11-01'
    PRINT @d
    SET @d = DATEADD(DAY,1,@d)

How do I horizontally center a span element inside a div

only css div you can center content

       margin:0 auto;

C# : changing listbox row color?

I think you have to draw the listitems yourself to achieve this.

Here's a post with the same kind of question.

How to format a phone number with jQuery

Here's a combination of some of these answers. This can be used for input fields. Deals with phone numbers that are 7 and 10 digits long.

// Used to format phone number
function phoneFormatter() {
  $('.phone').on('input', function() {
    var number = $(this).val().replace(/[^\d]/g, '')
    if (number.length == 7) {
      number = number.replace(/(\d{3})(\d{4})/, "$1-$2");
    } else if (number.length == 10) {
      number = number.replace(/(\d{3})(\d{3})(\d{4})/, "($1) $2-$3");

Live example: JSFiddle

I know this doesn't directly answer the question, but when I was looking up answers this was one of the first pages I found. So this answer is for anyone searching for something similar to what I was searching for.

initialize a numpy array

Maybe something like this will fit your needs..

import numpy as np

N = 5
res = []

for i in range(N):

res = np.array(res).reshape((10, 4))

Which produces the following output

[[ 1.  2.  3.  4.]
 [ 5.  6.  7.  8.]
 [ 1.  2.  3.  4.]
 [ 5.  6.  7.  8.]
 [ 1.  2.  3.  4.]
 [ 5.  6.  7.  8.]
 [ 1.  2.  3.  4.]
 [ 5.  6.  7.  8.]
 [ 1.  2.  3.  4.]
 [ 5.  6.  7.  8.]]

How to read a file in other directory in python

For folks like me looking at the accepted answer, and not understanding why it's not working, you need to add quotes around your sub directory, in the green checked example,

x_file = open(os.path.join(direct, "5_1.txt"), "r")  

should actually be

x_file = open(os.path.join('direct', "5_1.txt"), "r")   

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

This works perfectly, from ECMA

document.addEventListener("DOMContentLoaded", function() {
  // code...

The window.onload doesn't equal to JQuery $(document).ready because $(document).ready waits only to the DOM tree while window.onload check all elements including external assets and images.

EDIT: Added IE8 and older equivalent, thanks to Jan Derk's observation. You may read the source of this code on MDN at this link:

// alternative to DOMContentLoaded
document.onreadystatechange = function () {
    if (document.readyState == "interactive") {
        // Initialize your application or run some code.

There are other options apart from "interactive". See the MDN link for details.

get DATEDIFF excluding weekends using sql server

Example query below, here are some details on how I solved it.

Using DATEDIFF(WK, ...) will give us the number of weeks between the 2 dates. SQL Server evaluates this as a difference between week numbers rather than based on the number of days. This is perfect, since we can use this to determine how many weekends passed between the dates.

So we can multiple that value by 2 to get the number of weekend days that occurred and subtract that from the DATEDIFF(dd, ...) to get the number of weekdays.

This doesn't behave 100% correctly when the start or end date falls on Sunday, though. So I added in some case logic at the end of the calculation to handle those instances.

You may also want to consider whether or not the DATEDIFF should be fully inclusive. e.g. Is the difference between 9/10 and 9/11 1 day or 2 days? If the latter, you'll want to add 1 to the final product.

declare @d1 datetime, @d2 datetime
select @d1 = '9/9/2011',  @d2 = '9/18/2011'

select datediff(dd, @d1, @d2) - (datediff(wk, @d1, @d2) * 2) -
       case when datepart(dw, @d1) = 1 then 1 else 0 end +
      case when datepart(dw, @d2) = 1 then 1 else 0 end

Receive result from DialogFragment

if you want to send arguments and receive the result from second fragment, you may use Fragment.setArguments to accomplish this task

static class FirstFragment extends Fragment {
    final Handler mUIHandler = new Handler() {
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 101: // receive the result from SecondFragment
                Object result = msg.obj;
                // do something according to the result

    void onStartSecondFragments() {
        Message msg = Message.obtain(mUIHandler, 101, 102, 103, new Object()); // replace Object with a Parcelable if you want to across Save/Restore
                                                                               // instance
        putParcelable(new SecondFragment(), msg).show(getFragmentManager().beginTransaction(), null);

static class SecondFragment extends DialogFragment {
    Message mMsg; // arguments from the caller/FirstFragment

    public void onViewCreated(View view, Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onViewCreated(view, savedInstanceState);
        mMsg = getParcelable(this);

    void onClickOK() {
        mMsg.obj = new Object(); // send the result to the caller/FirstFragment

static <T extends Fragment> T putParcelable(T f, Parcelable arg) {
    if (f.getArguments() == null) {
        f.setArguments(new Bundle());
    f.getArguments().putParcelable("extra_args", arg);
    return f;
static <T extends Parcelable> T getParcelable(Fragment f) {
    return f.getArguments().getParcelable("extra_args");

What is

Often, a Python program is run by naming a .py file on the command line:

$ python

You can also create a directory or zipfile full of code, and include a Then you can simply name the directory or zipfile on the command line, and it executes the automatically:

$ python my_program_dir
$ python
# Or, if the program is accessible as a module
$ python -m my_program

You'll have to decide for yourself whether your application could benefit from being executed like this.

Note that a __main__ module usually doesn't come from a file. It can, but it usually doesn't. When you run a script like python, the script will run as the __main__ module instead of the my_program module. This also happens for modules run as python -m my_module, or in several other ways.

If you saw the name __main__ in an error message, that doesn't necessarily mean you should be looking for a file.

Get underlined text with Markdown

Both <ins>text</ins> and <span style="text-decoration:underline">text</span> work perfectly in Joplin, although I agree with @nfm that underlined text looks like a link and can be misleading in Markdown.

Line break (like <br>) using only css

You can use ::after to create a 0px-height block after the <h4>, which effectively moves anything after the <h4> to the next line:

h4 {_x000D_
  display: inline;_x000D_
h4::after {_x000D_
  content: "";_x000D_
  display: block;_x000D_
    Text, text, text, text, text. <h4>Sub header</h4>_x000D_
    Text, text, text, text, text._x000D_

Determine distance from the top of a div to top of window with javascript

You can use .offset() to get the offset compared to the document element and then use the scrollTop property of the window element to find how far down the page the user has scrolled:

var scrollTop     = $(window).scrollTop(),
    elementOffset = $('#my-element').offset().top,
    distance      = (elementOffset - scrollTop);

The distance variable now holds the distance from the top of the #my-element element and the top-fold.

Here is a demo:

Note that negative values mean that the element is above the top-fold.

How to find minimum value from vector?

You have an error in your code. This line:

for(int i=0;i<v[n];i++)

should be

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

because you want to search n places in your vector, not v[n] places (which wouldn't mean anything)

How to return Json object from MVC controller to view

You could use AJAX to call this controller action. For example if you are using jQuery you might use the $.ajax() method:

<script type="text/javascript">
        url: '@Url.Action("NameOfYourAction")',
        type: 'GET',
        cache: false,
        success: function(result) {
            // you could use the result.values dictionary here

Trim a string in C

/* Function to remove white spaces on both sides of a string i.e trim */

void trim (char *s)
    int i;

    while (isspace (*s)) s++;   // skip left side white spaces
    for (i = strlen (s) - 1; (isspace (s[i])); i--) ;   // skip right side white spaces
    s[i + 1] = '\0';
    printf ("%s\n", s);

How to display the value of the bar on each bar with pyplot.barh()?

I have noticed api example code contains an example of barchart with the value of the bar displayed on each bar:


A bar plot with errorbars and height labels on individual bars
import numpy as np
import matplotlib.pyplot as plt

N = 5
men_means = (20, 35, 30, 35, 27)
men_std = (2, 3, 4, 1, 2)

ind = np.arange(N)  # the x locations for the groups
width = 0.35       # the width of the bars

fig, ax = plt.subplots()
rects1 =, men_means, width, color='r', yerr=men_std)

women_means = (25, 32, 34, 20, 25)
women_std = (3, 5, 2, 3, 3)
rects2 = + width, women_means, width, color='y', yerr=women_std)

# add some text for labels, title and axes ticks
ax.set_title('Scores by group and gender')
ax.set_xticks(ind + width / 2)
ax.set_xticklabels(('G1', 'G2', 'G3', 'G4', 'G5'))

ax.legend((rects1[0], rects2[0]), ('Men', 'Women'))

def autolabel(rects):
    Attach a text label above each bar displaying its height
    for rect in rects:
        height = rect.get_height()
        ax.text(rect.get_x() + rect.get_width()/2., 1.05*height,
                '%d' % int(height),
                ha='center', va='bottom')



enter image description here

FYI What is the unit of height variable in "barh" of matplotlib? (as of now, there is no easy way to set a fixed height for each bar)

Access a global variable in a PHP function

For many years I have always used this format:

    $data = "Hello";

    function sayHello(){
        echo $GLOBALS["data"];


I find it straightforward and easy to follow. The $GLOBALS is how PHP lets you reference a global variable. If you have used things like $_SERVER, $_POST, etc. then you have reference a global variable without knowing it.

How to set JVM parameters for Junit Unit Tests?

In IntelliJ you can specify default settings for each run configuration. In Run/Debug configuration dialog (the one you use to configure heap per test) click on Defaults and JUnit. These settings will be automatically applied to each new JUnit test configuration. I guess similar setting exists for Eclipse.

However there is no simple option to transfer such settings (at least in IntelliJ) across environments. You can commit IntelliJ project files to your repository: it might work, but I do not recommend it.

You know how to set these for maven-surefire-plugin. Good. This is the most portable way (see Ptomli's answer for an example).

For the rest - you must remember that JUnit test cases are just a bunch of Java classes, not a standalone program. It is up to the runner (let it be a standalone JUnit runner, your IDE, maven-surefire-plugin to set those options. That being said there is no "portable" way to set them, so that memory settings are applied irrespective to the runner.

To give you an example: you cannot define Xmx parameter when developing a servlet - it is up to the container to define that. You can't say: "this servlet should always be run with Xmx=1G.

JavaScript getElementByID() not working

You need to put the JavaScript at the end of the body tag.

It doesn't find it because it's not in the DOM yet!

You can also wrap it in the onload event handler like this:

window.onload = function() {
var refButton = document.getElementById( 'btnButton' );
refButton.onclick = function() {
   alert( 'I am clicked!' );

ajax jquery simple get request

var settings = {
        "async": true,
        "crossDomain": true,
        "url": "<your URL Here>",
        "method": "GET",
        "headers": {
            "content-type": "application/x-www-form-urlencoded"
        "data": {
            "username": "[email protected]",
            "password": "12345678"

    $.ajax(settings).done(function (response) {

jQuery Dialog Box

I had the same problem and was looking for a way to solve it which brought me here. After reviewing the suggestion made from RaeLehman it led me to the solution. Here's my implementation.

In my $(document).ready event I initialize my dialog with the autoOpen set to false. I also chose to bind a click event to an element, like a button, which will open my dialog.


    // Initialize my dialog
        autoOpen: false,
        modal: true,
        buttons: {
        "OK":function() { // do something },
        "Cancel": function() { $(this).dialog("close"); }

    // Bind to the click event for my button and execute my function

Next, I make sure that the function is defined and that is where I implement the dialog open method.

var Foo = {
    DoSomething: function(){

By the way, I tested this in IE7 and Firefox and it works fine. Hope this helps!

Best practice for using assert?

Well, this is an open question, and I have two aspects that I want to touch on: when to add assertions and how to write the error messages.


To explain it to a beginner - assertions are statements which can raise errors, but you won't be catching them. And they normally should not be raised, but in real life they sometimes do get raised anyway. And this is a serious situation, which the code cannot recover from, what we call a 'fatal error'.

Next, it's for 'debugging purposes', which, while correct, sounds very dismissive. I like the 'declaring invariants, which should never be violated' formulation better, although it works differently on different beginners... Some 'just get it', and others either don't find any use for it, or replace normal exceptions, or even control flow with it.


In Python, assert is a statement, not a function! (remember assert(False, 'is true') will not raise. But, having that out of the way:

When, and how, to write the optional 'error message'?

This acually applies to unit testing frameworks, which often have many dedicated methods to do assertions (assertTrue(condition), assertFalse(condition), assertEqual(actual, expected) etc.). They often also provide a way to comment on the assertion.

In throw-away code you could do without the error messages.

In some cases, there is nothing to add to the assertion:

def dump(something): assert isinstance(something, Dumpable) # ...

But apart from that, a message is useful for communication with other programmers (which are sometimes interactive users of your code, e.g. in Ipython/Jupyter etc.).

Give them information, not just leak internal implementation details.

instead of:

assert meaningless_identifier <= MAGIC_NUMBER_XXX, 'meaningless_identifier is greater than MAGIC_NUMBER_XXX!!!'


assert meaningless_identifier > MAGIC_NUMBER_XXX, 'reactor temperature above critical threshold'

or maybe even:

assert meaningless_identifier > MAGIC_NUMBER_XXX, f'reactor temperature({meaningless_identifier }) above critical threshold ({MAGIC_NUMBER_XXX})'

I know, I know - this is not a case for a static assertion, but I want to point to the informational value of the message.

Negative or positive message?

This may be conroversial, but it hurts me to read things like:

assert a == b, 'a is not equal to b'
  • these are two contradictory things written next to eachother. So whenever I have an influence on the codebase, I push for specifying what we want, by using extra verbs like 'must' and 'should', and not to say what we don't want.

    assert a == b, 'a must be equal to b'

Then, getting AssertionError: a must be equal to b is also readable, and the statement looks logical in code. Also, you can get something out of it without reading the traceback (which can sometimes not even be available).

Using Git, show all commits that are in one branch, but not the other(s)

To show the commits in oldbranch but not in newbranch:

git log newbranch..oldbranch

To show the diff by these commits (note there are three dots):

git diff newbranch...oldbranch

Here is the doc with a diagram illustration

how to get rid of notification circle in right side of the screen?

This stuff comes from ES file explorer

Just go into this app > settings

Then there is an option that says logging floating window, you just need to disable that and you will get rid of this infernal bubble for good

Set Label Text with JQuery

I would just query for the for attribute instead of repetitively recursing the DOM tree.

$("input:checkbox").on("change", function() {

Lodash - difference between .extend() / .assign() and .merge()

It might be also helpful to consider what they do from a semantic point of view:


   will assign the values of the properties of its second parameter and so on,
   as properties with the same name of the first parameter. (shallow copy & override)


   merge is like assign but does not assign objects but replicates them instead.
  (deep copy)


   provides default values for missing values.
   so will assign only values for keys that do not exist yet in the source.


   works like _defaults but like merge will not simply copy objects
   and will use recursion instead.

I believe that learning to think of those methods from the semantic point of view would let you better "guess" what would be the behavior for all the different scenarios of existing and non existing values.

JavaScript adding decimal numbers issue

Use toFixed to convert it to a string with some decimal places shaved off, and then convert it back to a number.

+(0.1 + 0.2).toFixed(12) // 0.3

It looks like IE's toFixed has some weird behavior, so if you need to support IE something like this might be better:

Math.round((0.1 + 0.2) * 1e12) / 1e12

How do I redirect to another webpage?

I already use the function redirect() of JavaScript. It's working.

<script type="text/javascript">
    $(function () {
        //It's similar to HTTP redirect

        //It's similar to clicking on a link
        window.location.href = "Http://";

How do I ignore ampersands in a SQL script running from SQL Plus?

This may work for you:

set define off

Otherwise the ampersand needs to be at the end of a string,

'StackOverflow &' || ' you'

EDIT: I was click-happy when saving... This was referenced from a blog.

How get data from material-ui TextField, DropDownMenu components?

I don't know about y'all but for my own lazy purposes I just got the text fields from 'document' by ID and set the values as parameters to my back-end JS function:

      onClick={() => { printIt(document.getElementById('field1').value,_x000D_
      document.getElementById('field2').value)    _x000D_
export function printIt(text1, text2) {_x000D_
console.log('on button clicked');_x000D_

It works just fine.

Remove duplicate values from JS array

For anyone looking to flatten arrays with duplicate elements into one unique array:

function flattenUniq(arrays) {
  var args =;

  var array = [].concat.apply([], args)

  var result = array.reduce(function(prev, curr){
    if (prev.indexOf(curr) < 0) prev.push(curr);
    return prev;

  return result;

How to select a CRAN mirror in R

A drop down menu should pop up for you to select from (or you will get a bunch of numbers to choose from), whether you are using R in the terminal or an IDE such as RStudio. This is supported on Windows, Mac OS, and most Linux systems. However, it may require additional configuration or dependencies such as X-windows.

To enable X-windows when using remote access use the following -XY flags:

ssh -XY [email protected]

There is often a default repo but this can be specified if you have any issue, such as running scripts or Rmarkdown/knitr. You can use the repo opset the mirror or repository for CRAN each time you install with:

install.packages("package", repo="<your.nearest.mirror>")

It is advisable to use the nearest mirror to your location for faster downloads. For example:

install.packages("RMySQL", repos="")

You can also set the repos option in your session so you only need to it once per interactive session (or script). You can check whether repos is configured with:


If you get "Error in options(repos) : object 'repos' not found" then you can set the repository option. For example:

options(repos = "")

Then it should work to install packages like usual. For Example:


As mentioned by others, you can configure the repository in your .Rprofile file and have this work across all of your scripts. It's up to you whether your prefer these "global" options on your system or "local" options in your session or script. These "local" options take more time to use each session but have the benefit of making others able to use your scripts if they don't have your .Rprofile.

duplicate 'row.names' are not allowed error

The answer here ( by @adrianoesch should help (e.g., solves "If you know of a solution that does not require the awkward workaround mentioned in your comment (shift the column names, copy the data), that would be great." and "...requiring that the data be copied" proposed by @Frank).

Note that if you open in some text editor, you should see that the number of header fields less than number of columns below the header row. In my case, the data set had a "," missing at the end of the last header field.

VHDL - How should I create a clock in a testbench?

Concurrent signal assignment:

library ieee;
use ieee.std_logic_1164.all;

entity foo is
architecture behave of foo is
    signal clk: std_logic := '0';
clk <=  '1' after 0.5 ns when clk = '0' else
        '0' after 0.5 ns when clk = '1';

ghdl -a foo.vhdl
ghdl -r foo --stop-time=10ns --wave=foo.ghw
ghdl:info: simulation stopped by --stop-time
gtkwave foo.ghw

enter image description here

Simulators simulate processes and it would be transformed into the equivalent process to your process statement. Simulation time implies the use of wait for or after when driving events for sensitivity clauses or sensitivity lists.

HSL to RGB color conversion

Found the easiest way, python to the rescue :D

colorsys.hls_to_rgb(h, l, s)

Convert the color from HLS coordinates to RGB coordinates.

Bootstrap 4 - Responsive cards in card-columns

I have created a Cards Layout - 3 cards in a row using Bootstrap 4 / CSS3 (of course its responsive). The following example uses basic Bootstrap 4 classes such as container, row, col-x, list-group and list-group-item. Thought to share here if someone is interested in this sort of a layout.

enter image description here


<div class="container">
  <div class="row">
    <div class="col-sm-12 col-md-4">
      <div class="custom-column">
        <div class="custom-column-header">Header</div>
        <div class="custom-column-content">
          <ul class="list-group">
            <li class="list-group-item"><i class="fa fa-check"></i> Cras justo odio</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Dapibus ac facilisis in</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Morbi leo risus</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Porta ac consectetur ac</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Vestibulum at eros</li>
        <div class="custom-column-footer"><button class="btn btn-primary btn-lg">Click here</button></div>
    <div class="col-sm-12 col-md-4">
      <div class="custom-column">        
        <div class="custom-column-header">Header</div>
        <div class="custom-column-content">
          <ul class="list-group">
            <li class="list-group-item"><i class="fa fa-check"></i> Cras justo odio</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Dapibus ac facilisis in</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Morbi leo risus</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Porta ac consectetur ac</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Vestibulum at eros</li>
        <div class="custom-column-footer"><button class="btn btn-primary btn-lg">Click here</button></div>
    <div class="col-sm-12 col-md-4">
      <div class="custom-column">
        <div class="custom-column-header">Header</div>
        <div class="custom-column-content">
          <ul class="list-group">
            <li class="list-group-item"><i class="fa fa-check"></i> Cras justo odio</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Dapibus ac facilisis in</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Morbi leo risus</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Porta ac consectetur ac</li>
            <li class="list-group-item"><i class="fa fa-check"></i> Vestibulum at eros</li>
        <div class="custom-column-footer"><button class="btn btn-primary btn-lg">Click here</button></div>


$primary-color: #ccc;
$col-bg-color: #eee;
$col-footer-bg-color: #eee;
$col-header-bg-color: #007bff;
$col-content-bg-color: #fff;

body {
  background-color: $primary-color;

.custom-column {  
  background-color: $col-bg-color;
  border: 5px solid $col-bg-color;    
  padding: 10px;
  box-sizing: border-box;  

.custom-column-header {
  font-size: 24px;
  background-color: #007bff;  
  color: white;
  padding: 15px;  
  text-align: center;

.custom-column-content {
  background-color: $col-content-bg-color;
  border: 2px solid white;  
  padding: 20px;  

.custom-column-footer {
  background-color: $col-footer-bg-color;   
  padding-top: 20px;
  text-align: center;

Link :-

How can we convert an integer to string in AngularJs

.toString() is available, or just add "" to the end of the int

var x = 3,
    toString = x.toString(),
    toConcat = x + "";

Angular is simply JavaScript at the core.

Responsive image map

For responsive image maps you will need to use a plugin: (No longer maintained)


No major browsers understand percentage coordinates correctly, and all interpret percentage coordinates as pixel coordinates.

And also this page for testing whether browsers implement

Console.log(); How to & Debugging javascript

Learn to use a javascript debugger. Venkman (for Firefox) or the Web Inspector (part of Chome & Safari) are excellent tools for debugging what's going on.

You can set breakpoints and interrogate the state of the machine as you're interacting with your script; step through parts of your code to make sure everything is working as planned, etc.

Here is an excellent write up from WebMonkey on JavaScript Debugging for Beginners. It's a great place to start.

How to ignore whitespace in a regular expression subject string?

If you only want to allow spaces, then

\bc *a *t *s\b

should do it. To also allow tabs, use

\bc[ \t]*a[ \t]*t[ \t]*s\b

Remove the \b anchors if you also want to find cats within words like bobcats or catsup.

Simplest way to set image as JPanel background

class Logo extends JPanel
    public void paintComponent(Graphics g) 
        ImageIcon img = new ImageIcon("logo.jpg");
        g.drawImage(img.getImage(), 0, 0, this.getWidth(), this.getHeight(), null);

Move cursor to end of file in vim

  • Ctrl + Home = Jump to start of file
  • Ctrl + End = Jump to end of file

How is TeamViewer so fast?

A bit late answer, but I suggest you have a look at a not well known project on codeplex called ConferenceXP

ConferenceXP is an open source research platform that provides simple, flexible, and extensible conferencing and collaboration using high-bandwidth networks and the advanced multimedia capabilities of Microsoft Windows. ConferenceXP helps researchers and educators develop innovative applications and solutions that feature broadcast-quality audio and video in support of real-time distributed collaboration and distance learning environments.

Full source (it's huge!) is provided. It implements the RTP protocol.

What is the difference between iterator and iterable and how to use them?

The most important consideration is whether the item in question should be able to be traversed more than once. This is because you can always rewind an Iterable by calling iterator() again, but there is no way to rewind an Iterator.

Change GridView row color based on condition

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    e.Row.Attributes.Add("style", "cursor:help;");
    if (e.Row.RowType == DataControlRowType.DataRow && e.Row.RowState == DataControlRowState.Alternate)
        if (e.Row.RowType == DataControlRowType.DataRow)
            e.Row.Attributes.Add("onmouseover", "'orange'");
            e.Row.Attributes.Add("onmouseout", "'#E56E94'");
            e.Row.BackColor = Color.FromName("#E56E94");                
        if (e.Row.RowType == DataControlRowType.DataRow)
            e.Row.Attributes.Add("onmouseover", "'orange'");
            e.Row.Attributes.Add("onmouseout", "'gray'");
            e.Row.BackColor = Color.FromName("gray");                

Send value of submit button when form gets posted

The button names are not submit, so the php $_POST['submit'] value is not set. As in isset($_POST['submit']) evaluates to false.

<form action="" method="post">
    <input type="hidden" name="action" value="submit" />
    <select name="name">
make sure all html elements that have an ID are unique and name the buttons submit 
    <input id="tea-submit" type="submit" name="submit" value="Tea">
    <input id="coffee-submit" type="submit" name="submit" value="Coffee">

if (isset($_POST['action'])) {
    echo '<br />The ' . $_POST['submit'] . ' submit button was pressed<br />';

Error installing mysql2: Failed to build gem native extension

Another way for MacOS users

If you used "brew" to install mysql:

gem install mysql2 -v 'x.x.x' -- --with-mysql-config=/usr/local/Cellar/mysql/y.y.y/bin/mysql_config

x.x.x = version of the mysql2 gem you want to install
y.y.y = the version of mysql you have installed ls /usr/local/Cellar/mysql to find it.

How to access a dictionary element in a Django template?

You could use a namedtuple instead of a dict. This is a shorthand for using a data class. Instead of

person = {'name':  'John', 'age':  14}

from collections import namedtuple
Person = namedtuple('person', ['name', 'age'])
p = Person(name='John', age=14) # 'John'

This is the same as writing a class that just holds data. In general I would avoid using dicts in django templates because they are awkward.

How to convert currentTimeMillis to a date in Java?

The easiest way to do this is to use the Joda DateTime class and specify both the timestamp in milliseconds and the DateTimeZone you want.

I strongly recommend avoiding the built-in Java Date and Calendar classes; they're terrible.

no overload for matches delegate 'system.eventhandler'

Change the klik method as follows:

public void klik(object pea, EventArgs e)
    Bitmap c = this.DrawMandel();
    Button btn = pea as Button;
    Graphics gr = btn.CreateGraphics();
    gr.DrawImage(b, 150, 200);

Facebook Graph API v2.0+ - /me/friends returns empty, or only friends who also use my application

In the Facebook SDK Graph API v2.0 or above, you must request the user_friends permission from each user in the time of Facebook login since user_friends is no longer included by default in every login; we have to add that.

Each user must grant the user_friends permission in order to appear in the response to /me/friends.

let fbLoginManager : FBSDKLoginManager = FBSDKLoginManager()
fbLoginManager.loginBehavior = FBSDKLoginBehavior.web
fbLoginManager.logIn(withReadPermissions: ["email","user_friends","public_profile"], from: self) { (result, error) in
    if (error == nil) {

        let fbloginresult : FBSDKLoginManagerLoginResult = result!
        if fbloginresult.grantedPermissions != nil {
            if (fbloginresult.grantedPermissions.contains("email")) {
                // Do the stuff
            else {
        else {

So at the time of Facebook login, it prompts with a screen which contain all the permissions:

Enter image description here

If the user presses the Continue button, the permissions will be set. When you access the friends list using Graph API, your friends who logged into the application as above will be listed

if ((FBSDKAccessToken.current()) != nil) {
    FBSDKGraphRequest(graphPath: "/me/friends", parameters: ["fields" : "id,name"]).start(completionHandler: { (connection, result, error) -> Void in
        if (error == nil) {


The output will contain the users who granted the user_friends permission at the time of login to your application through Facebook.

    data = (
                 id = xxxxxxxxxx;
                 name = "xxxxxxxx";
    paging = {
        cursors = {
            after = xxxxxx;
            before = xxxxxxx;
    summary = {
        "total_count" = 8;

Go To Definition: "Cannot navigate to the symbol under the caret."

I've done all things above but my problem did not solve (trying to open project by VS 2017),

after that I realized that the problem was my csproj file. My project (mvc)

was created by VS 2015... So I edit my csproj file and replace

<Import Project="..\packages\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.1.0.0\build\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.props" Condition="Exists('..\packages\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.1.0.0\build\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.props')" />

by this :

<Import Project="..\packages\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.1.0.7\build\net45\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.props" Condition="Exists('..\packages\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.1.0.7\build\net45\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.props')" />

It was all about the version of DotNetCompilerPlatform.

(the way that I understood this issue was that I created new mvc project by VS 2017 and compared both csproj files - the new one and the one that created by VS 2015 - )

Additional related info by (since answers are locked)

For me (VS2019 opening an older solution) it was only affecting one project in the solution. The Imports looked like this:

<Import Project="..\packages\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.1.0.0\build\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.props" Condition="Exists('..\packages\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.1.0.0\build\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.props')" />
<Import Project="..\packages\Microsoft.Net.Compilers.1.0.0\build\Microsoft.Net.Compilers.props" Condition="Exists('..\packages\Microsoft.Net.Compilers.1.0.0\build\Microsoft.Net.Compilers.props')" />
<Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />

The working projects only had the

<Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />

line, so I removed the first 2 and intelisense / go to definition etc. started working again.

HOWEVER the web project now wouldn't run due to missing Roslyn csc compiler.

In the end the solution that worked overall was to update the Microsoft.CodeDom.Providers.DotNetCompilerPlatform and Microsoft.Net.Compilers Nuget packages for the project.

Creating Scheduled Tasks

You can use Task Scheduler Managed Wrapper:

using System;
using Microsoft.Win32.TaskScheduler;

class Program
   static void Main(string[] args)
      // Get the service on the local machine
      using (TaskService ts = new TaskService())
         // Create a new task definition and assign properties
         TaskDefinition td = ts.NewTask();
         td.RegistrationInfo.Description = "Does something";

         // Create a trigger that will fire the task at this time every other day
         td.Triggers.Add(new DailyTrigger { DaysInterval = 2 });

         // Create an action that will launch Notepad whenever the trigger fires
         td.Actions.Add(new ExecAction("notepad.exe", "c:\\test.log", null));

         // Register the task in the root folder
         ts.RootFolder.RegisterTaskDefinition(@"Test", td);

         // Remove the task we just created

Alternatively you can use native API or go for Quartz.NET. See this for details.

MySQL - Get row number on select

SELECT @rn:=@rn+1 AS rank, itemID, ordercount
  SELECT itemID, COUNT(*) AS ordercount
  FROM orders
  ORDER BY ordercount DESC
) t1, (SELECT @rn:=0) t2;

How to disable "prevent this page from creating additional dialogs"?

You can't. It's a browser feature there to prevent sites from showing hundreds of alerts to prevent you from leaving.

You can, however, look into modal popups like jQuery UI Dialog. These are javascript alert boxes that show a custom dialog. They don't use the default alert() function and therefore, bypass the issue you're running into completely.

I've found that an apps that has a lot of message boxes and confirms has a much better user experience if you use custom dialogs instead of the default alerts and confirms.

How to convert float to int with Java

If you want to convert a float value into an integer value, you have several ways to do it that depends on how do you want to round the float value.

First way is floor rounding the float value:

float myFloat = 3.14f;
int myInteger = (int)myFloat;

The output of this code will be 3, even if the myFloat value is closer to 4.

The second way is ceil rounding the float value:

float myFloat = 3.14f;
int myInteger = Math.ceil(myFloat);

The output of this code will be 4, because the rounding mode is always looking for the highest value.

How can I generate a list of consecutive numbers?

Depending on how you want the result, you can also print each number in a for loop:

def numbers():
    for i in range(int(input('How far do you wanna go? '))+1):

So if the user input was 7 for example:

How far do you wanna go? 7

You can also delete the '+1' in the for loop and place it on the print statement, which will change it to starting at 1 instead of 0.

jQuery UI Dialog OnBeforeUnload

This works for me:

window.addEventListener("beforeunload", function(event) {_x000D_
  event.returnValue = "You may have unsaved Data";_x000D_

How to expand textarea width to 100% of parent (or how to expand any HTML element to 100% of parent width)?

You need to define width of the div containing the textarea and when you declare textarea, you can then set .main > textarea to have width: inherit.

Note: .main > textarea means a <textarea> inside of an element with class="main".

Here is the working solution


<div class="wrapper">
  <div class="left">left</div>
  <div class="main">
    <textarea name="" cols="" rows=""></textarea>

The CSS:

.wrapper {
  display: table;
  width: 100%;

.left {
  width: 20%;
  background: #cccccc;
  display: table-cell;

.main {
  width: 80%;
  background: gray;
  display: inline;

.main > textarea {
  width: inherit;

Hashmap with Streams in Java 8 Streams to collect value of Map

You can also do it like this

public Map<Boolean, List<Student>> getpartitionMap(List<Student> studentsList) {

    List<Predicate<Student>> allPredicates = getAllPredicates();
    Predicate<Student> compositePredicate =
                             .reduce(w -> true, Predicate::and)
     Map<Boolean, List<Student>> studentsMap= studentsList
    return studentsMap;

public List<Student> getValidStudentsList(Map<Boolean, List<Student>> studentsMap) throws Exception {

    List<Student> validStudentsList =  studentsMap.entrySet()
             .filter(p -> p.getKey() == Boolean.TRUE)
             .flatMap(p -> p.getValue().stream())

    return validStudentsList;

public List<Student> getInValidStudentsList(Map<Boolean, List<Student>> studentsMap) throws Exception {

    List<Student> invalidStudentsList = 
             .filter(p -> p.getKey() == Boolean.FALSE)
             .flatMap(p -> p.getValue().stream())

    return invalidStudentsList;


With flatMap you will get just List<Student> instead of List<List<Student>>.


How to change a css class style through Javascript?

If you want to manipulate the actual CSS class instead of modifying the DOM elements or using modifier CSS classes, see

How do I force "git pull" to overwrite local files?

I was trying to use the Material2 branch on the Angular2-Webpack-Starter and had a heck of a time. This was the only way I could download and use that branch.

git clone --depth 1

cd angular2-webpack-starter/

git checkout -b material2

Open the project folder and delete all non-hidden files and folders. Leave all the hidden ones.

git add .

git commit -m "pokemon go"

git reset --hard

git pull origin material2

(When the editor pops up, hit ':wq', and then press Enter)

Now you are ready.

How do I bind a WPF DataGrid to a variable number of columns?

I've continued my research and have not found any reasonable way to do this. The Columns property on the DataGrid isn't something I can bind against, in fact it's read only.

Bryan suggested something might be done with AutoGenerateColumns so I had a look. It uses simple .Net reflection to look at the properties of the objects in ItemsSource and generates a column for each one. Perhaps I could generate a type on the fly with a property for each column but this is getting way off track.

Since this problem is so easily sovled in code I will stick with a simple extension method I call whenever the data context is updated with new columns:

public static void GenerateColumns(this DataGrid dataGrid, IEnumerable<ColumnSchema> columns)

    int index = 0;
    foreach (var column in columns)
        dataGrid.Columns.Add(new DataGridTextColumn
            Header = column.Name,
            Binding = new Binding(string.Format("[{0}]", index++))

// E.g. myGrid.GenerateColumns(schema);

iterating quickly through list of tuples

I think that you can use

for j,k in my_list:
  [ ... stuff ... ]

How to remove "onclick" with JQuery?

Old Way (pre-1.7):

$("...").attr("onclick", "").unbind("click");

New Way (1.7+):

$("...").prop("onclick", null).off("click");

(Replace ... with the selector you need.)

// use the "[attr=value]" syntax to avoid syntax errors with special characters (like "$")_x000D_
<script src=""></script>_x000D_
<a id="a$id" onclick="alert('get rid of this')" href="javascript:void(0)"  class="black">Qualify</a>

flutter corner radius with transparent background

If you want to round corners with transparent background, the best approach is using ClipRRect.

return ClipRRect(
  borderRadius: BorderRadius.circular(40.0),
  child: Container(
    height: 800.0,
    width: double.infinity,
    child: Center(
      child: new Text("Hi modal sheet"),

Karma: Running a single test file from command line

This option is no longer supported in recent versions of karma:


The files array can be redefined using the CLI as such:

karma start --files=Array("test/Spec/services/myServiceSpec.js")

or escaped:

karma start --files=Array\(\"test/Spec/services/myServiceSpec.js\"\)


Is there a simple way to delete a list element by value?

With a for loop and a condition:

def cleaner(seq, value):    
    temp = []                      
    for number in seq:
        if number != value:
    return temp

And if you want to remove some, but not all:

def cleaner(seq, value, occ):
    temp = []
    for number in seq:
        if number == value and occ:
            occ -= 1
    return temp

WHERE Clause to find all records in a specific month

SELECT * FROM yourtable WHERE yourtimestampfield LIKE 'AAAA-MM%';

Where AAAA is the year you want and MM is the month you want

How do I use a custom deleter with a std::unique_ptr member?

Assuming that create and destroy are free functions (which seems to be the case from the OP's code snippet) with the following signatures:

Bar* create();
void destroy(Bar*);

You can write your class Foo like this

class Foo {

    std::unique_ptr<Bar, void(*)(Bar*)> ptr_;

    // ...


    Foo() : ptr_(create(), destroy) { /* ... */ }

    // ...

Notice that you don't need to write any lambda or custom deleter here because destroy is already a deleter.

Finding moving average from data points in Python

Before reading this answer, bear in mind that there is another answer below, from Roman Kh, which uses numpy.cumsum and is MUCH MUCH FASTER than this one.

Best One common way to apply a moving/sliding average (or any other sliding window function) to a signal is by using numpy.convolve().

def movingaverage(interval, window_size):
    window = numpy.ones(int(window_size))/float(window_size)
    return numpy.convolve(interval, window, 'same')

Here, interval is your x array, and window_size is the number of samples to consider. The window will be centered on each sample, so it takes samples before and after the current sample in order to calculate the average. Your code would become:


x_av = movingaverage(interval, r)
plot(x_av, y)

xlabel("Months since Jan 1749.")
ylabel("No. of Sun spots")

Hope this helps!

Get source jar files attached to Eclipse for Maven-managed dependencies

If the source jars are in the local repository and you are using Eclipses maven support the sources are getting automatically attached. You can run mvn dependency:sources to download all source jars for a given project. Not sure how to do the same with the documentation though.

Excel VBA: Copying multiple sheets into new workbook

Rethink your approach. Why would you copy only part of the sheet? You are referring to a named range "WholePrintArea" which doesn't exist. Also you should never use activate, select, copy or paste in your script. These make the "script" vulnerable to user actions and other simultaneous executions. In worst case scenario data ends up in wrong hands.

ASP.NET Background image

body {
    background-image: url('../images/background.jpg');
    background-repeat: no-repeat;
    background-size: cover; /* will auto resize to fill the screen */

remove url parameters with javascript or jquery

What am I missing?

Why not:


add onclick function to a submit button

if you need to do something before submitting data, you could use form's onsubmit.

<form method=post onsubmit="return doSomething()">
  <input type=text name=text1>
  <input type=submit>

Project vs Repository in GitHub

This is my personal understanding about the topic.

For a project, we can do the version control by different repositories. And for a repository, it can manage a whole project or part of projects.

Regarding on your project (several prototype applications which are independent of each them). You can manage the project by one repository or by several repositories, the difference:

  1. Manage by one repository. If one of the applications is changed, the whole project (all the applications) will be committed to a new version.

  2. Manage by several repositories. If one application is changed, it will only affect the repository which manages the application. Version for other repositories was not changed.

SQL - Update multiple records in one query

in my case I have to update the records which are more than 1000, for this instead of hitting the update query each time I preferred this,

   UPDATE mst_users 
   SET base_id = CASE user_id 
   WHEN 78 THEN 999 
   WHEN 77 THEN 88 
   ELSE base_id END WHERE user_id IN(78, 77)

78,77 are the user Ids and for those user id I need to update the base_id 999 and 88 respectively.This works for me.

In Python, how do I use urllib to see if a website is 404 or 200?

The getcode() method (Added in python2.6) returns the HTTP status code that was sent with the response, or None if the URL is no HTTP URL.

>>> a=urllib.urlopen('')
>>> a.getcode()
>>> a=urllib.urlopen('')
>>> a.getcode()

Convert from enum ordinal to enum type

You could use a static lookup table:

public enum Suit {
  spades, hearts, diamonds, clubs;

  private static final Map<Integer, Suit> lookup = new HashMap<Integer, Suit>();

    int ordinal = 0;
    for (Suit suit : EnumSet.allOf(Suit.class)) {
      lookup.put(ordinal, suit);
      ordinal+= 1;

  public Suit fromOrdinal(int ordinal) {
    return lookup.get(ordinal);

Why does Python code use len() function instead of a length method?

Strings do have a length method: __len__()

The protocol in Python is to implement this method on objects which have a length and use the built-in len() function, which calls it for you, similar to the way you would implement __iter__() and use the built-in iter() function (or have the method called behind the scenes for you) on objects which are iterable.

See Emulating container types for more information.

Here's a good read on the subject of protocols in Python: Python and the Principle of Least Astonishment

Check if boolean is true?

i personally would prefer

if(true == foo)

there is no chance for the ==/= mistype and i find it more expressive in terms of foo's type. But it is a very subjective question.

Wi-Fi Direct and iOS Support

It took me a while to find out what is going on, but here is the summary. I hope this save people a lot of time.

Apple are not playing nice with Wi-Fi Direct, not in the same way that Android is. The Multipeer Connectivity Framework that Apple provides combines both BLE and WiFi Direct together and will only work with Apple devices and not any device that is using Wi-Fi Direct.

It states the following in this documentation - "The Multipeer Connectivity framework provides support for discovering services provided by nearby iOS devices using infrastructure Wi-Fi networks, peer-to-peer Wi-Fi, and Bluetooth personal area networks and subsequently communicating with those services by sending message-based data, streaming data, and resources (such as files)."

Additionally, Wi-Fi direct in this mode between i-Devices will need iPhone 5 and above.

There are apps that use a form of Wi-Fi Direct on the App Store, but these are using their own libraries.

OracleCommand SQL Parameters Binding

string strConn = "Data Source=ORCL134; User ID=user; Password=psd;";

System.Data.OracleClient.OracleConnection con = newSystem.Data.OracleClient.OracleConnection(strConn);

    System.Data.OracleClient.OracleCommand Cmd = 
        new System.Data.OracleClient.OracleCommand(
            "SELECT * FROM TBLE_Name WHERE ColumnName_year= :year", con);

//for is :object_name and for sql it s @object_name
    Cmd.Parameters.Add(new System.Data.OracleClient.OracleParameter("year", (txtFinYear.Text).ToString()));

    System.Data.OracleClient.OracleDataAdapter da = new System.Data.OracleClient.OracleDataAdapter(Cmd);
    DataSet myDS = new DataSet();
        lblBatch.Text = "Batch Number is : " + Convert.ToString(myDS.Tables[0].Rows[0][19]);
        lblBatch.ForeColor = System.Drawing.Color.Green;
        lblBatch.Visible = true;
        lblBatch.Text = "No Data Found for the Year : " + txtFinYear.Text;
        lblBatch.ForeColor = System.Drawing.Color.Red;
        lblBatch.Visible = true;   

Start HTML5 video at a particular position when loading?

On Safari Mac for an HLS source, I needed to use the loadeddata event instead of the metadata event.

View tabular file such as CSV from command line

Tabview: lightweight python curses command line CSV file viewer (and also other tabular Python data, like a list of lists) is here on Github


  • Python 2.7+, 3.x
  • Unicode support
  • Spreadsheet-like view for easily visualizing tabular data
  • Vim-like navigation (h,j,k,l, g(top), G(bottom), 12G goto line 12, m - mark, ' - goto mark, etc.)
  • Toggle persistent header row
  • Dynamically resize column widths and gap
  • Sort ascending or descending by any column. 'Natural' order sort for numeric values.
  • Full-text search, n and p to cycle between search results
  • 'Enter' to view the full cell contents
  • Yank cell contents to clipboard
  • F1 or ? for keybindings
  • Can also use from python command line to visualize any tabular data (e.g. list-of-lists)

Using an Alias in a WHERE clause

 SELECT A.identifier
 , TO_NUMBER(DECODE( A.month_no
         , 1, 200803 
         , 2, 200804 
         , 3, 200805 
         , 4, 200806 
         , 5, 200807 
         , 6, 200808 
         , 7, 200809 
         , 8, 200810 
         , 9, 200811 
         , 10, 200812 
         , 11, 200701 
         , 12, 200702
         , NULL)) as MONTH_NO
 , TO_NUMBER(TO_CHAR(B.last_update_date, 'YYYYMM')) as UPD_DATE
FROM table_a A, table_b B
WHERE .identifier = B.identifier

How to count items in JSON object using command line?

The shortest expression is

curl 'http://…' | jq length

Check if SQL Connection is Open or Closed

I use the following manner sqlconnection.state

if(conexion.state !=;

Hashmap holding different data types as values for instance Integer, String and Object

Do simply like below....

HashMap<String,Object> yourHash = new HashMap<String,Object>();
yourHash.put(yourKey+"count ",count);
yourHash.put(yourKey+"version ",version);

typecast the value while getting back. For ex:

    int count = Integer.parseInt(yourHash.get(yourKey+"count"));
int count = Integer.valueOf(yourHash.get(yourKey+"count"));
int count = (Integer)yourHash.get(yourKey+"count"); //or (int)

Replace all occurrences of a String using StringBuilder?

Even simple one is using the String ReplaceAll function itself. You can write it as

StringBuilder sb = new StringBuilder("Hi there, are you there?")

find if an integer exists in a list of integers

If you just need a true/false result

bool isInList = intList.IndexOf(intVariable) != -1;

if the intVariable does not exist in the List it will return -1

How can I fix the form size in a C# Windows Forms application and not to let user change its size?

Properties -> FormBorderStyle -> FixedSingle

if you can not find your Properties tool. Go to View -> Properties Window

Java 32-bit vs 64-bit compatibility

Add a paramter as below in you in configuration while creating the exe

I hope it helps.



How to write to file in Ruby?

Are you looking for the following?, 'w') { |file| file.write("your text") }

Set icon for Android application

It's better to do this through Android Studio rather than the file browser as it updates all icon files with the correct resolution for each.

To do so go to menu File ? New ? Image Asset. This will open a new dialogue and then make sure Launcher Icons is selected (Which it is by default) and then browse to the directory of your icon (it doesn't have to be in the project resources) and then once selected make sure other settings are to your liking and hit done.

Now all resolutions are saved into their respective folders, and you don't have to worry about copying it yourself or using tools, etc.

Enter image description here

Don't forget "Shape - none" for a transparent background.

Please don't edit my answer without asking.

How to use makefiles in Visual Studio?

A UNIX guy probably told you that. :)

You can use makefiles in VS, but when you do it bypasses all the built-in functionality in MSVC's IDE. Makefiles are basically the reinterpret_cast of the builder. IMO the simplest thing is just to use Solutions.

WiX tricks and tips

Using the Msi Diagnostic logging to get detailed failure Information

msiexec /i Package.msi /l*v c:\Package.log


is the name of your package and
is where you want the output of the log

Msi Error Codes

Wix Intro Video
Oh and Random Wix intro video featuring "Mr. WiX" Rob Mensching is "conceptual big picture" helpful.

How to input matrix (2D list) in Python?

The problem is on the initialization step.

for i in range (0,m):
  matrix[i] = columns

This code actually makes every row of your matrix refer to the same columns object. If any item in any column changes - every other column will change:

>>> for i in range (0,m):
...     matrix[i] = columns
>>> matrix
[[0, 0, 0], [0, 0, 0]]
>>> matrix[1][1] = 2
>>> matrix
[[0, 2, 0], [0, 2, 0]]

You can initialize your matrix in a nested loop, like this:

matrix = []
for i in range(0,m):
    for j in range(0,n):

or, in a one-liner by using list comprehension:

matrix = [[0 for j in range(n)] for i in range(m)]


matrix = [x[:] for x in [[0]*n]*m]

See also:

Hope that helps.

Is there a "previous sibling" selector?

There is no "previous" sibling selector unfortunately, but you can possibly still get the same effect by using positioning (e.g. float right). It depends on what you are trying to do.

In my case, I wanted a primarily CSS 5-star rating system. I would need to color (or swap the icon of) the previous stars. By floating each element right, I am essentially getting the same effect (the html for the stars thus must be written 'backwards').

I'm using FontAwesome in this example and swapping between the unicodes of fa-star-o and fa-star


.fa {
    display: inline-block;
    font-family: FontAwesome;
    font-style: normal;
    font-weight: normal;
    line-height: 1;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;

/* set all stars to 'empty star' */
.stars-container {
    display: inline-block;      

/* set all stars to 'empty star' */
.stars-container .star {
    float: right;
    display: inline-block;
    padding: 2px;
    color: orange;
    cursor: pointer;


.stars-container .star:before {
    content: "\f006"; /* fontAwesome empty star code */

/* set hovered star to 'filled star' */
    content: "\f005"; /* fontAwesome filled star code */

/* set all stars after hovered to'filled star' 
** it will appear that it selects all after due to positioning */
.star:hover ~ .star:before {
    content: "\f005"; /* fontAwesome filled star code */

HTML: (40)


Is there a constraint that restricts my generic method to numeric types?

Beginning with C# 7.3, you can use closer approximation - the unmanaged constraint to specify that a type parameter is a non-pointer, non-nullable unmanaged type.

class SomeGeneric<T> where T : unmanaged

The unmanaged constraint implies the struct constraint and can't be combined with either the struct or new() constraints.

A type is an unmanaged type if it's any of the following types:

  • sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal, or bool
  • Any enum type
  • Any pointer type
  • Any user-defined struct type that contains fields of unmanaged types only and, in C# 7.3 and earlier, is not a constructed type (a type that includes at least one type argument)

To restrict further and eliminate pointer and user-defined types that do not implement IComparable add IComparable (but enum is still derived from IComparable, so restrict enum by adding IEquatable < T >, you can go further depending on your circumstances and add additional interfaces. unmanaged allows to keep this list shorter):

    class SomeGeneric<T> where T : unmanaged, IComparable, IEquatable<T>

But this doesn't prevent from DateTime instantiation.

setting global sql_mode in mysql

Check the documentation of sql_mode

Method 1:

Check default value of sql_mode:

SELECT @@sql_mode //check current value for sql_mode


Method 2:

Access phpmyadmin for editing your sql_mode

  • Login on phpmyadmin and open localhost
  • Top on Variables present on the top in menu items and search out for sql mode
  • Click on edit button to modify sql_mode based on your requirements
  • Save the changes

sql mode settings in phpmyadmin

Restart server after executing above things

Recyclerview and handling different type of row inflation

The trick is to create subclasses of ViewHolder and then cast them.

public class GroupViewHolder extends RecyclerView.ViewHolder {
    TextView mTitle;
    TextView mContent;
    public GroupViewHolder(View itemView) {
        super (itemView);
        // init views...

public class ImageViewHolder extends RecyclerView.ViewHolder {
    ImageView mImage;
    public ImageViewHolder(View itemView) {
        super (itemView);
        // init views...

private static final int TYPE_IMAGE = 1;
private static final int TYPE_GROUP = 2;  

And then, at runtime do something like this:

public int getItemViewType(int position) {
    // here your custom logic to choose the view type
    return position == 0 ? TYPE_IMAGE : TYPE_GROUP;

public void onBindViewHolder (ViewHolder viewHolder, int i) {

    switch (viewHolder.getItemViewType()) {

        case TYPE_IMAGE:
            ImageViewHolder imageViewHolder = (ImageViewHolder) viewHolder;

        case TYPE_GROUP:
            GroupViewHolder groupViewHolder = (GroupViewHolder) viewHolder;

Hope it helps.

How to position a table at the center of div horizontally & vertically

I discovered that I had to include

body { width:100%; }

for "margin: 0 auto" to work for tables.

convert string to char*

There are many ways. Here are at least five:

 * An example of converting std::string to (const)char* using five
 * different methods. Error checking is emitted for simplicity.
 * Compile and run example (using gcc on Unix-like systems):
 *  $ g++ -Wall -pedantic -o test ./test.cpp
 *  $ ./test
 *  Original string (0x7fe3294039f8): hello
 *  s1 (0x7fe3294039f8): hello
 *  s2 (0x7fff5dce3a10): hello
 *  s3 (0x7fe3294000e0): hello
 *  s4 (0x7fe329403a00): hello
 *  s5 (0x7fe329403a10): hello

#include <alloca.h>
#include <string>
#include <cstring>

int main()
    std::string s0;
    const char *s1;
    char *s2;
    char *s3;
    char *s4;
    char *s5;

    // This is the initial C++ string.
    s0 = "hello";

    // Method #1: Just use "c_str()" method to obtain a pointer to a
    // null-terminated C string stored in std::string object.
    // Be careful though because when `s0` goes out of scope, s1 points
    // to a non-valid memory.
    s1 = s0.c_str();

    // Method #2: Allocate memory on stack and copy the contents of the
    // original string. Keep in mind that once a current function returns,
    // the memory is invalidated.
    s2 = (char *)alloca(s0.size() + 1);
    memcpy(s2, s0.c_str(), s0.size() + 1);

    // Method #3: Allocate memory dynamically and copy the content of the
    // original string. The memory will be valid until you explicitly
    // release it using "free". Forgetting to release it results in memory
    // leak.
    s3 = (char *)malloc(s0.size() + 1);
    memcpy(s3, s0.c_str(), s0.size() + 1);

    // Method #4: Same as method #3, but using C++ new/delete operators.
    s4 = new char[s0.size() + 1];
    memcpy(s4, s0.c_str(), s0.size() + 1);

    // Method #5: Same as 3 but a bit less efficient..
    s5 = strdup(s0.c_str());

    // Print those strings.
    printf("Original string (%p): %s\n", s0.c_str(), s0.c_str());
    printf("s1 (%p): %s\n", s1, s1);
    printf("s2 (%p): %s\n", s2, s2);
    printf("s3 (%p): %s\n", s3, s3);
    printf("s4 (%p): %s\n", s4, s4);
    printf("s5 (%p): %s\n", s5, s5);

    // Release memory...
    delete [] s4;

How do I get a range's address including the worksheet name, but not the workbook name, in Excel VBA?

[edit on 2009-04-21]

    As Micah pointed out, this only works when you have named that
    particular range (hence .Name anyone?) Yeah, oops!


A little late to the party, I know, but in case anyone else catches this in a google search (as I just did), you could also try the following:

Dim cell as Range
Dim address as String
Set cell = Sheet1.Range("A1")
address = cell.Name

This should return the full address, something like "=Sheet1!$A$1".

Assuming you don't want the equal sign, you can strip it off with a Replace function:

address = Replace(address, "=", "")

Use mysql_fetch_array() with foreach() instead of while()

You can code like this:

$query_select = "SELECT * FROM shouts ORDER BY id DESC LIMIT 8;";
$result_select = mysql_query($query_select) or die(mysql_error());
$rows = array();
while($row = mysql_fetch_array($result_select))
    $rows[] = $row;
foreach($rows as $row){ 
    $ename = stripslashes($row['name']);
    $eemail = stripcslashes($row['email']);
    $epost = stripslashes($row['post']);
    $eid = $row['id'];

    $grav_url = "".md5(strtolower($eemail))."&size=70";

    echo ('<img src = "' . $grav_url . '" alt="Gravatar">'.'<br/>');

    echo $eid . '<br/>';

    echo $ename . '<br/>';

    echo $eemail . '<br/>';

    echo $epost . '<br/><br/><br/><br/>';

As you can see, it's still need a loop while to get data from mysql_fetch_array

ASP.NET MVC View Engine Comparison

I like ndjango. It is very easy to use and very flexible. You can easily extend view functionality with custom tags and filters. I think that "greatly tied to F#" is rather advantage than disadvantage.

Ascending and Descending Number Order in java

use reverse for loop to print in descending order,

for (int i = ar.length - 1; i >= 0; i--) {

How to get thread id from a thread pool?

There is the way of current thread getting:

Thread t = Thread.currentThread();

After you have got Thread class object (t) you are able to get information you need using Thread class methods.

Thread ID gettting:

long tId = t.getId(); // e.g. 14291

Thread name gettting:

String tName = t.getName(); // e.g. "pool-29-thread-7"

How to revert uncommitted changes including files and folders?

git clean -fd

didn't help, new files remained. What I did is totally deleting all the working tree and then

git reset --hard

See "How do I clear my local working directory in git?" for advice to add the -x option to clean:

git clean -fdx

Note -x flag will remove all files ignored by Git so be careful (see discussion in the answer I refer to).

App can't be opened because it is from an unidentified developer

It is prohibiting the opening of Eclipse app because it was not registered with Apple by an identified developer. This is a security feature, however, you can override the security setting and open the app by doing the following:

  1. Locate the (eclipse/ in Finder. (Make sure you use Finder so that you can perform the subsequent steps.)
  2. Press the Control key and then click the icon.
  3. Choose Open from the shortcut menu.
  4. Click the Open button when the alert window appears.

The last step will add an exception for Eclipse to your security settings and now you will be able to open it without any warnings.

Note, these steps work for other *.app apps that may encounter the same issue.

How to specify table's height such that a vertical scroll bar appears?

You need to wrap the table inside another element and set the height of that element. Example with inline css:

<div style="height: 500px; overflow: auto;">

How to select all elements with a particular ID in jQuery?

Your document should not contain two divs with the same id. This is invalid HTML, and as a result, the underlying DOM API does not support it.

From the HTML standard:

id = name [CS] This attribute assigns a name to an element. This name must be unique in a document.

You can either assign different ids to each div and select them both using $('#id1, #id2). Or assign the same class to both elements (.cls for example), and use $('.cls') to select them both.

SQL Server 2005 How Create a Unique Constraint?

            <namingconventionconstraint> UNIQUE NONCLUSTERED
    ) ON [PRIMARY]

How to set session attribute in java?

Java file :

package Jclasspackage

public class Jclass {

    public String uname ;
     * @return the uname
    public String getUname() {
        return uname;

     * @param uname the uname to set
    public void setUname(String uname) {
        this.uname = uname;

    public Jclass() {
        this.uname = null;

    public static void main(String[] args) {


JSP file: sample.jsp

    <%@ page language="java"

< import="" />   
<% Jclass jc = new Jclass();
String username = (String)request.getAttribute("un")


In this way you can access the username in the java file using "this.username" in the class

How to print the current time in a Batch-File?

set time1=%time%
call timeout 10
set time2=%time%
echo. time1
echo. time2

#pragma once vs include guards?

#pragma once allows the compiler to skip the file completely when it occurs again - instead of parsing the file until it reaches the #include guards.

As such, the semantics are a little different, but they are identical if they are used they way they are intended to be used.

Combining both is probably the safest route to go, as in the worst case (a compiler flagging unknown pragmas as actual errors, not just warnings) you would just to have to remove the #pragma's themselves.

When you limit your platforms to, say "mainstream compilers on the desktop", you could safely omit the #include guards, but I feel uneasy on that, too.

OT: if you have other tips/experiences to share on speeding up builds, I'd be curious.

How to export a Hive table into a CSV file?

That should work for you

  • tab separated

    hive -e 'select * from some_table' > /home/yourfile.tsv
  • comma separated

    hive -e 'select * from some_table' | sed 's/[\t]/,/g' > /home/yourfile.csv

How to trim leading and trailing white spaces of a string?

A quick string "GOTCHA" with JSON Unmarshall which will add wrapping quotes to strings.

(example: the string value of {"first_name":" I have whitespace "} will convert to "\" I have whitespace \"")

Before you can trim anything, you'll need to remove the extra quotes first:

playground example

// ScrubString is a string that might contain whitespace that needs scrubbing.
type ScrubString string

// UnmarshalJSON scrubs out whitespace from a valid json string, if any.
func (s *ScrubString) UnmarshalJSON(data []byte) error {
    ns := string(data)
    // Make sure we don't have a blank string of "\"\"".
    if len(ns) > 2 && ns[0] != '"' && ns[len(ns)] != '"' {
        *s = ""
        return nil
    // Remove the added wrapping quotes.
    ns, err := strconv.Unquote(ns)
    if err != nil {
        return err
    // We can now trim the whitespace.
    *s = ScrubString(strings.TrimSpace(ns))

    return nil

How do I mount a host directory as a volume in docker compose

If you would like to mount a particular host directory (/disk1/prometheus-data in the following example) as a volume in the volumes section of the Docker Compose YAML file, you can do it as below, e.g.:

version: '3'

    image: prom/prometheus
      - prometheus-data:/prometheus

    driver: local
      o: bind
      type: none
      device: /disk1/prometheus-data

By the way, in prometheus's Dockerfile, You may find the VOLUME instruction as below, which marks it as holding externally mounted volumes from native host, etc. (Note however: this instruction is not a must though to mount a volume into a container.):


VOLUME ["/prometheus"]


git replace local version with remote version

I understand the question as this: you want to completely replace the contents of one file (or a selection) from upstream. You don't want to affect the index directly (so you would go through add + commit as usual).

Simply do

git checkout remote/branch -- a/file b/another/file

If you want to do this for extensive subtrees and instead wish to affect the index directly use

git read-tree remote/branch:subdir/

You can then (optionally) update your working copy by doing

git checkout-index -u --force

Reverse colormap in matplotlib

As a LinearSegmentedColormaps is based on a dictionary of red, green and blue, it's necessary to reverse each item:

import matplotlib.pyplot as plt
import matplotlib as mpl
def reverse_colourmap(cmap, name = 'my_cmap_r'):
    cmap, name 

    t[0] goes from 0 to 1
    row i:   x  y0  y1 -> t[0] t[1] t[2]
    row i+1: x  y0  y1 -> t[n] t[1] t[2]

    so the inverse should do the same:
    row i+1: x  y1  y0 -> 1-t[0] t[2] t[1]
    row i:   x  y1  y0 -> 1-t[n] t[2] t[1]
    reverse = []
    k = []   

    for key in cmap._segmentdata:    
        channel = cmap._segmentdata[key]
        data = []

        for t in channel:                    

    LinearL = dict(zip(k,reverse))
    my_cmap_r = mpl.colors.LinearSegmentedColormap(name, LinearL) 
    return my_cmap_r

See that it works:

<matplotlib.colors.LinearSegmentedColormap at 0xd5a0518>

my_cmap_r = reverse_colourmap(my_cmap)

fig = plt.figure(figsize=(8, 2))
ax1 = fig.add_axes([0.05, 0.80, 0.9, 0.15])
ax2 = fig.add_axes([0.05, 0.475, 0.9, 0.15])
norm = mpl.colors.Normalize(vmin=0, vmax=1)
cb1 = mpl.colorbar.ColorbarBase(ax1, cmap = my_cmap, norm=norm,orientation='horizontal')
cb2 = mpl.colorbar.ColorbarBase(ax2, cmap = my_cmap_r, norm=norm, orientation='horizontal')

enter image description here


I don't get the comment of user3445587. It works fine on the rainbow colormap:

cmap =
cmap_r = reverse_colourmap(cmap)

fig = plt.figure(figsize=(8, 2))
ax1 = fig.add_axes([0.05, 0.80, 0.9, 0.15])
ax2 = fig.add_axes([0.05, 0.475, 0.9, 0.15])
norm = mpl.colors.Normalize(vmin=0, vmax=1)
cb1 = mpl.colorbar.ColorbarBase(ax1, cmap = cmap, norm=norm,orientation='horizontal')
cb2 = mpl.colorbar.ColorbarBase(ax2, cmap = cmap_r, norm=norm, orientation='horizontal')

enter image description here

But it especially works nice for custom declared colormaps, as there is not a default _r for custom declared colormaps. Following example taken from

cdict1 = {'red':   ((0.0, 0.0, 0.0),
                   (0.5, 0.0, 0.1),
                   (1.0, 1.0, 1.0)),

         'green': ((0.0, 0.0, 0.0),
                   (1.0, 0.0, 0.0)),

         'blue':  ((0.0, 0.0, 1.0),
                   (0.5, 0.1, 0.0),
                   (1.0, 0.0, 0.0))

blue_red1 = mpl.colors.LinearSegmentedColormap('BlueRed1', cdict1)
blue_red1_r = reverse_colourmap(blue_red1)

fig = plt.figure(figsize=(8, 2))
ax1 = fig.add_axes([0.05, 0.80, 0.9, 0.15])
ax2 = fig.add_axes([0.05, 0.475, 0.9, 0.15])

norm = mpl.colors.Normalize(vmin=0, vmax=1)
cb1 = mpl.colorbar.ColorbarBase(ax1, cmap = blue_red1, norm=norm,orientation='horizontal')
cb2 = mpl.colorbar.ColorbarBase(ax2, cmap = blue_red1_r, norm=norm, orientation='horizontal')

enter image description here

HAProxy redirecting http to https (ssl)

Like Jay Taylor said, HAProxy 1.5-dev has the redirect scheme configuration directive, which accomplishes exactly what you need.

However, if you are unable to use 1.5, and if you're up for compiling HAProxy from source, I backported the redirect scheme functionality so it works in 1.4. You can get the patch here:

Lodash remove duplicates from array

Or simply Use union, for simple array.

_.union([1,2,3,3], [3,5])

// [1,2,3,5]

scp files from local to remote machine error: no such file or directory

If you want to copy everything in a Folder + have a special Port use this one. Works for me on Ubuntu 18.04 and a local machine with Mac OS X.

-r for recursive
-P for Port

scp -rP 1234 /Your_Directory/Source_Folder/ [email protected]:/target/folder

How to check if PHP array is associative or sequential?

Simple and performance friendly solution which only checks the first key.

function isAssoc($arr = NULL)
    if ($arr && is_array($arr))
        foreach ($arr as $key => $val)
            if (is_numeric($key)) { return true; }


    return false;

Using both Python 2.x and Python 3.x in IPython Notebook

From my Linux installation I did:

sudo ipython2 kernelspec install-self

And now my python 2 is back on the list.



The method above is now deprecated and will be dropped in the future. The new method should be:

sudo ipython2 kernel install

Mocha / Chai not catching thrown errors

And if you are already using ES6/ES2015 then you can also use an arrow function. It is basically the same as using a normal anonymous function but shorter.

expect(() => model.get('z')).to.throw('Property does not exist in model schema.');

How to find the location of the Scheduled Tasks folder

On newer versions of Windows (Windows 10 and Windows Server 2016) the tasks you create are located in C:\Windows\Tasks. They will have the extension .job

For example if you create the task "DoWork" it will create the task in


How to set time to a date object in java

Calendar cal = Calendar.getInstance();

Date d = cal.getTime();

Also See

how to concat two columns into one with the existing column name in mysql?

I am a novice and I did it this way:

Create table Name1
F_Name varchar(20),
L_Name varchar(20),

Insert into Name1
('Tom', 'Bombadil', 32),
('Danny', 'Fartman', 43),
('Stephine', 'Belchlord', 33),
('Corry', 'Smallpants', 95)

Update Name1
Set F_Name = CONCAT(F_Name, ' ', L_Name)

Alter Table Name1
Drop column L_Name

Update Table_Name
Set F_Name

merge one local branch into another local branch

First, checkout to your Branch3:

git checkout Branch3

Then merge the Branch1:

git merge Branch1

And if you want the updated commits of Branch1 on Branch2, you are probaly looking for git rebase

git checkout Branch2
git rebase Branch1

This will update your Branch2 with the latest updates of Branch1.

Is there a standard function to check for null, undefined, or blank variables in JavaScript?

For my case I tried with if null,'', !variable, But it did not work.

See my code below to get the text from an html field

var status=$(this).text(); //for example (for my case)

if there was no value(no text) in the status variable ,I was trying to set the value 'novalue' to status variable.

the following code worked.

if(status == false)

when there was no text found for satus variable the above code assigned 'novalue' to the status variable

File.Move Does Not Work - File Already Exists

If file really exists and you want to replace it use below code:

string file = "c:\test\SomeFile.txt"
string moveTo = "c:\test\test\SomeFile.txt"

if (File.Exists(moveTo))

File.Move(file, moveTo);

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

A message has a header part and a message body separated by a blank line. The blank line is ALWAYS needed even if there is no message body. The header starts with a command and has additional lines of key value pairs separated by a colon and a space. If there is a message body, it can be anything you want it to be.

Lines in the header and the blank line at the end of the header must end with a carraige return and linefeed pair (see HTTP header line break style) so that's why those lines have \r\n at the end.

A URL has the form of http://host:port/path?query_string

There are two main ways of submitting a request to a website:

  • GET: The query string is optional but, if specified, must be reasonably short. Because of this the header could just be the GET command and nothing else. A sample message could be:

    GET /path?query_string HTTP/1.0\r\n
  • POST: What would normally be in the query string is in the body of the message instead. Because of this the header needs to include the Content-Type: and Content-Length: attributes as well as the POST command. A sample message could be:

    POST /path HTTP/1.0\r\n
    Content-Type: text/plain\r\n
    Content-Length: 12\r\n

So, to answer your question: if the URL you are interested in POSTing to is then there is no body or query string and, consequently, no reason to POST because there is nothing to put in the body of the message and so nothing to put in the Content-Type: and Content-Length:

I guess you could POST if you really wanted to. In that case your message would look like:

POST /apikey=ARG1&command=ARG2 HTTP/1.0\r\n

So to send the message the C program needs to:

  • create a socket
  • lookup the IP address
  • open the socket
  • send the request
  • wait for the response
  • close the socket

The send and receive calls won't necessarily send/receive ALL the data you give them - they will return the number of bytes actually sent/received. It is up to you to call them in a loop and send/receive the remainder of the message.

What I did not do in this sample is any sort of real error checking - when something fails I just exit the program. Let me know if it works for you:

#include <stdio.h> /* printf, sprintf */
#include <stdlib.h> /* exit */
#include <unistd.h> /* read, write, close */
#include <string.h> /* memcpy, memset */
#include <sys/socket.h> /* socket, connect */
#include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
#include <netdb.h> /* struct hostent, gethostbyname */

void error(const char *msg) { perror(msg); exit(0); }

int main(int argc,char *argv[])
    /* first what are we going to send and where are we going to send it? */
    int portno =        80;
    char *host =        "";
    char *message_fmt = "POST /apikey=%s&command=%s HTTP/1.0\r\n\r\n";

    struct hostent *server;
    struct sockaddr_in serv_addr;
    int sockfd, bytes, sent, received, total;
    char message[1024],response[4096];

    if (argc < 3) { puts("Parameters: <apikey> <command>"); exit(0); }

    /* fill in the parameters */

    /* create the socket */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) error("ERROR opening socket");

    /* lookup the ip address */
    server = gethostbyname(host);
    if (server == NULL) error("ERROR, no such host");

    /* fill in the structure */
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(portno);

    /* connect the socket */
    if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
        error("ERROR connecting");

    /* send the request */
    total = strlen(message);
    sent = 0;
    do {
        bytes = write(sockfd,message+sent,total-sent);
        if (bytes < 0)
            error("ERROR writing message to socket");
        if (bytes == 0)
    } while (sent < total);

    /* receive the response */
    total = sizeof(response)-1;
    received = 0;
    do {
        bytes = read(sockfd,response+received,total-received);
        if (bytes < 0)
            error("ERROR reading response from socket");
        if (bytes == 0)
    } while (received < total);

    if (received == total)
        error("ERROR storing complete response from socket");

    /* close the socket */

    /* process response */

    return 0;

Like the other answer pointed out, 4096 bytes is not a very big response. I picked that number at random assuming that the response to your request would be short. If it can be big you have two choices:

  • read the Content-Length: header from the response and then dynamically allocate enough memory to hold the whole response.
  • write the response to a file as the pieces arrive

Additional information to answer the question asked in the comments:

What if you want to POST data in the body of the message? Then you do need to include the Content-Type: and Content-Length: headers. The Content-Length: is the actual length of everything after the blank line that separates the header from the body.

Here is a sample that takes the following command line arguments:

  • host
  • port
  • command (GET or POST)
  • path (not including the query data)
  • query data (put into the query string for GET and into the body for POST)
  • list of headers (Content-Length: is automatic if using POST)

So, for the original question you would run:

a.out 80 GET "/apikey=ARG1&command=ARG2"

And for the question asked in the comments you would run:

a.out 80 POST / "name=ARG1&value=ARG2" "Content-Type: application/x-www-form-urlencoded"

Here is the code:

#include <stdio.h> /* printf, sprintf */
#include <stdlib.h> /* exit, atoi, malloc, free */
#include <unistd.h> /* read, write, close */
#include <string.h> /* memcpy, memset */
#include <sys/socket.h> /* socket, connect */
#include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
#include <netdb.h> /* struct hostent, gethostbyname */

void error(const char *msg) { perror(msg); exit(0); }

int main(int argc,char *argv[])
    int i;

    /* first where are we going to send it? */
    int portno = atoi(argv[2])>0?atoi(argv[2]):80;
    char *host = strlen(argv[1])>0?argv[1]:"localhost";

    struct hostent *server;
    struct sockaddr_in serv_addr;
    int sockfd, bytes, sent, received, total, message_size;
    char *message, response[4096];

    if (argc < 5) { puts("Parameters: <host> <port> <method> <path> [<data> [<headers>]]"); exit(0); }

    /* How big is the message? */
        message_size+=strlen("%s %s%s%s HTTP/1.0\r\n");        /* method         */
        message_size+=strlen(argv[3]);                         /* path           */
        message_size+=strlen(argv[4]);                         /* headers        */
            message_size+=strlen(argv[5]);                     /* query string   */
        for(i=6;i<argc;i++)                                    /* headers        */
        message_size+=strlen("\r\n");                          /* blank line     */
        message_size+=strlen("%s %s HTTP/1.0\r\n");
        message_size+=strlen(argv[3]);                         /* method         */
        message_size+=strlen(argv[4]);                         /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
            message_size+=strlen("Content-Length: %d\r\n")+10; /* content length */
        message_size+=strlen("\r\n");                          /* blank line     */
            message_size+=strlen(argv[5]);                     /* body           */

    /* allocate space for the message */

    /* fill in the parameters */
            sprintf(message,"%s %s%s%s HTTP/1.0\r\n",
                strlen(argv[3])>0?argv[3]:"GET",               /* method         */
                strlen(argv[4])>0?argv[4]:"/",                 /* path           */
                strlen(argv[5])>0?"?":"",                      /* ?              */
                strlen(argv[5])>0?argv[5]:"");                 /* query string   */
            sprintf(message,"%s %s HTTP/1.0\r\n",
                strlen(argv[3])>0?argv[3]:"GET",               /* method         */
                strlen(argv[4])>0?argv[4]:"/");                /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
        strcat(message,"\r\n");                                /* blank line     */
        sprintf(message,"%s %s HTTP/1.0\r\n",
            strlen(argv[3])>0?argv[3]:"POST",                  /* method         */
            strlen(argv[4])>0?argv[4]:"/");                    /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
            sprintf(message+strlen(message),"Content-Length: %d\r\n",strlen(argv[5]));
        strcat(message,"\r\n");                                /* blank line     */
            strcat(message,argv[5]);                           /* body           */

    /* What are we going to send? */

    /* create the socket */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) error("ERROR opening socket");

    /* lookup the ip address */
    server = gethostbyname(host);
    if (server == NULL) error("ERROR, no such host");

    /* fill in the structure */
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(portno);

    /* connect the socket */
    if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
        error("ERROR connecting");

    /* send the request */
    total = strlen(message);
    sent = 0;
    do {
        bytes = write(sockfd,message+sent,total-sent);
        if (bytes < 0)
            error("ERROR writing message to socket");
        if (bytes == 0)
    } while (sent < total);

    /* receive the response */
    total = sizeof(response)-1;
    received = 0;
    do {
        bytes = read(sockfd,response+received,total-received);
        if (bytes < 0)
            error("ERROR reading response from socket");
        if (bytes == 0)
    } while (received < total);

    if (received == total)
        error("ERROR storing complete response from socket");

    /* close the socket */

    /* process response */

    return 0;

Extract values in Pandas value_counts()

First you have to sort the dataframe by the count column max to min if it's not sorted that way already. In your post, it is in the right order already but I will sort it anyways:

dataframe.sort_index(by='count', ascending=[False])
    col     count
0   apple   5
1   sausage 2
2   banana  2
3   cheese  1 

Then you can output the col column to a list:

['apple', 'sausage', 'banana', 'cheese']

Pointers in Python?

I wrote the following simple class as, effectively, a way to emulate a pointer in python:

class Parameter:
    """Syntactic sugar for getter/setter pair

    p = Parameter(getter, setter)

    Set parameter value:
    p.val = value

    Retrieve parameter value:
    def __init__(self, getter, setter):
        """Create parameter

        Required positional parameters:
        getter: called with no arguments, retrieves the parameter value.
        setter: called with value, sets the parameter.
        self._get = getter
        self._set = setter

    def __call__(self, val=None):
        if val is not None:
        return self._get()

    def get(self):
        return self._get()

    def set(self, val):

    def val(self):
        return self._get()

    def val(self, val):

Here's an example of use (from a jupyter notebook page):

l1 = list(range(10))
def l1_5_getter(lst=l1, number=5):
    return lst[number]

def l1_5_setter(val, lst=l1, number=5):
    lst[number] = val


Out = [5, None, [0, 1, 2, 3, 4, 12, 6, 7, 8, 9], 12]

p = Parameter(l1_5_getter, l1_5_setter)

p.val = 15
print(p.val, l1)

[12, 12, 12, 13, 13, None, 14]
15 [0, 1, 2, 3, 4, 15, 6, 7, 8, 9]

Of course, it is also easy to make this work for dict items or attributes of an object. There is even a way to do what the OP asked for, using globals():

def setter(val, dict=globals(), key='a'):
    dict[key] = val

def getter(dict=globals(), key='a'):
    return dict[key]

pa = Parameter(getter, setter)

This will print out 2, followed by 3.

Messing with the global namespace in this way is kind of transparently a terrible idea, but it shows that it is possible (if inadvisable) to do what the OP asked for.

The example is, of course, fairly pointless. But I have found this class to be useful in the application for which I developed it: a mathematical model whose behavior is governed by numerous user-settable mathematical parameters, of diverse types (which, because they depend on command line arguments, are not known at compile time). And once access to something has been encapsulated in a Parameter object, all such objects can be manipulated in a uniform way.

Although it doesn't look much like a C or C++ pointer, this is solving a problem that I would have solved with pointers if I were writing in C++.

Converting String to Int using try/except in Python

It is important to be specific about what exception you're trying to catch when using a try/except block.

string = "abcd"
    string_int = int(string)
except ValueError:
    # Handle the exception
    print('Please enter an integer')

Try/Excepts are powerful because if something can fail in a number of different ways, you can specify how you want the program to react in each fail case.

SQL Server PRINT SELECT (Print a select query result)?


PRINT 'Hardcoded table name -' + CAST(@@RowCount as varchar(10))

immediately after the query.

How to Clear Console in Java?

Try this code


public class CLS {
    public static void main(String... arg) throws IOException, InterruptedException {
        new ProcessBuilder("cmd", "/c", "cls").inheritIO().start().waitFor();

Now when the Java process is connected to a console, it will clear the console.

How is Pythons glob.glob ordered?

glob.glob() is a wrapper around os.listdir() so the underlaying OS is in charge for delivering the data. In general: you can not make an assumption on the ordering here. The basic assumption is: no ordering. If you need some sorting: sort on the application level.

What does a bitwise shift (left or right) do and what is it used for?

Some examples:

  • Bit operations for example converting to and from Base64 (which is 6 bits instead of 8)
  • doing power of 2 operations (1 << 4 equal to 2^4 i.e. 16)
  • Writing more readable code when working with bits. For example, defining constants using 1 << 4 or 1 << 5 is more readable.

Default SQL Server Port

The default port 1433 is used when there is only one SQL Server named instance running on the computer.

When multiple SQL Server named instances are running, they run by default under a dynamic port (49152–65535). In this scenario, an application will connect to the SQL Server Browser service port (UDP 1434) to get the dynamic port and then connect to the dynamic port directly.

What is the difference between `sorted(list)` vs `list.sort()`?

Note: Simplest difference between sort() and sorted() is: sort() doesn't return any value while, sorted() returns an iterable list.

sort() doesn't return any value.

The sort() method just sorts the elements of a given list in a specific order - Ascending or Descending without returning any value.

The syntax of sort() method is:

list.sort(key=..., reverse=...)

Alternatively, you can also use Python's in-built function sorted() for the same purpose. sorted function return sorted list

 list=sorted(list, key=..., reverse=...)

MySQL - How to increase varchar size of an existing column in a database without breaking existing data?

It's safe to increase the size of your varchar column. You won't corrupt your data.

If it helps your peace of mind, keep in mind, you can always run a database backup before altering your data structures.

By the way, correct syntax is:

ALTER TABLE table_name MODIFY col_name VARCHAR(10000)

Also, if the column previously allowed/did not allow nulls, you should add the appropriate syntax to the end of the alter table statement, after the column type.

How to apply CSS to iframe?

Edit: This does not work cross domain unless the appropriate CORS header is set.

There are two different things here: the style of the iframe block and the style of the page embedded in the iframe. You can set the style of the iframe block the usual way:

<iframe name="iframe1" id="iframe1" src="empty.htm" 
        frameborder="0" border="0" cellspacing="0"
        style="border-style: none;width: 100%; height: 120px;"></iframe>

The style of the page embedded in the iframe must be either set by including it in the child page:

<link type="text/css" rel="Stylesheet" href="Style/simple.css" />

Or it can be loaded from the parent page with Javascript:

var cssLink = document.createElement("link");
cssLink.href = "style.css"; 
cssLink.rel = "stylesheet"; 
cssLink.type = "text/css"; 

Difference between Select Unique and Select Distinct

  1. Unique was the old syntax while Distinct is the new syntax,which is now the Standard sql.
  2. Unique creates a constraint that all values to be inserted must be different from the others. An error can be witnessed if one tries to enter a duplicate value. Distinct results in the removal of the duplicate rows while retrieving data.
  3. Example: SELECT DISTINCT names FROM student ;

    CREATE TABLE Persons ( Id varchar NOT NULL UNIQUE, Name varchar(20) );

linking problem: fatal error LNK1112: module machine type 'x64' conflicts with target machine type 'X86'

Since the problem is due to the difference in compilation and target machine specifications (x86 & x64) Follow the steps below:

  1. Open the C++ project that you want to configure.
  2. Choose the Configuration Manager button to open the Configuration Manager dialog box.
  3. In the Active Solution Platform drop-down list, select the option to open the New Solution Platform dialog box.
  4. In the Type or select the new platform drop-down list, select a 64-bit platform.

This solved my problem.

What's the simplest way to list conflicted files in Git?

If you attempt to commit, and if there are conflicts, then git will give you the list of the currently unresolved conflicts... but not as a plain list. This is usually what you want when working interactively because the list gets shorter as you fix the conflicts.

.htaccess file to allow access to images folder to view pictures?

Give permission in .htaccess as follows:

<Directory "Your directory path/uploads/">
Allow from all