Tutorial by Examples: b

WebSockets

var ws = new WebSocket('ws://host.com/path'); ws.onopen = () => { // connection opened ws.send('something'); // send a message }; ws.onmessage = (e) => { // a message was received console.log(e.data); }; ws.onerror = (e) => { // an error occurred console.log(e...

react-native • HTTP Requests

Versioning your builds via "version.properties" file

You can use Gradle to auto-increment your package version each time you build it. To do so create a version.properties file in the same directory as your build.gradle with the following contents: VERSION_MAJOR=0 VERSION_MINOR=1 VERSION_BUILD=1 (Changing the values for major and minor as you s...

Android • Gradle for Android

Cast an object to a base type

Given the following definitions : public interface IMyInterface1 { string GetName(); } public interface IMyInterface2 { string GetName(); } public class MyClass : IMyInterface1, IMyInterface2 { string IMyInterface1.GetName() { return "IMyInterface1"...

C# Language • Casting

C++ compatible helper functions

The use of Matlab Coder sometimes denies the use of some very common functions, if they are not compatible to C++. Relatively often there exist undocumented helper functions, which can be used as replacements. Here is a comprehensive list of supported functions.. And following a collection of alte...

MATLAB Language • Undocumented Features

Singleton & Companion Objects

Singleton Objects Scala supports static members, but not in the same manner as Java. Scala provides an alternative to this called Singleton Objects. Singleton objects are similar to a normal class, except they can not be instantiated using the new keyword. Below is a sample singleton class: object...

Scala Language • Classes and Objects

Using map to reformat objects in an array

Array.prototype.map(): Returns a new array with the results of calling a provided function on every element in the original array. The following code example takes an array of persons and creates a new array containing persons with a 'fullName' property var personsArray = [ { id: 1, f...

JavaScript • Arrays

Passing arguments by reference or value

In JavaScript all arguments are passed by value. When a function assigns a new value to an argument variable, that change will not be visible to the caller: var obj = {a: 2}; function myfunc(arg){ arg = {a: 5}; // Note the assignment is to the parameter variable itself } myfunc(obj); conso...

JavaScript • Functions

Inheritance - Abstract and Final Methods and Classes

Information The ABSTRACT and FINAL additions to the METHODS and CLASS statements allow you to define abstract and final methods or classes. An abstract method is defined in an abstract class and cannot be implemented in that class. Instead, it is implemented in a subclass of the class. Abstra...

ABAP • ABAP Objects

Assertion of Unreachable Code

During development, when certain code paths must be prevented from the reach of control flow, you may use assert(0) to indicate that such a condition is erroneous: switch (color) { case COLOR_RED: case COLOR_GREEN: case COLOR_BLUE: break; default: assert(0); ...

C Language • Assertion

Basic Note Outputs

#define NOTE_C4 262 //From pitches.h file defined in [Arduino Tone Tutorial][1] int Key = 2; int KeyVal = 0; byte speaker = 12; void setup() { pinMode(Key, INPUT); //Declare our key (button) as input pinMode(speaker, OUTPUT); } void loop() { KeyVal = digitalRead(Key); i...

arduino • Audio Output

Escaping curly brackets inside a String.Format() expression

string outsidetext = "I am outside of bracket"; string.Format("{{I am in brackets!}} {0}", outsidetext); //Outputs "{I am in brackets!} I am outside of bracket"

C# Language • String.Format

Basic View

index.html <html> <head> <title>Angular-UI Router Example</title> <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.9/angular.js"></script> <script type="text/java...

angular-ui-router • Getting started with angular-ui-router

Const local variables

Declaration and usage. // a is const int, so it can't be changed const int a = 15; a = 12; // Error: can't assign new value to const variable a += 1; // Error: can't assign new value to const variable Binding of references and pointers int &b = a; // Error: ca...

C++ • const keyword

Matplotlib

Matplotlib is a mathematical plotting library for Python that provides a variety of different plotting functionality. The matplotlib documentation can be found here, with the SO Docs being available here. Matplotlib provides two distinct methods for plotting, though they are interchangable for the...

Python Language • Data Visualization with Python

Basic example

This example shows setting up a small application with 3 routes, each with it's own view and controller, using the controllerAs syntax. We configure our router at the angular .config function We inject $routeProvider into .config We define our route names at the .when method with a route defini...

AngularJS • Routing using ngRoute

Draw a diagonal blue line using the L path command

SVG • Paths

RequiredAttribute

The Required attribute specifies that a property is required. An error message can be specified on using the ErrorMessage property on the attribute. First add the namespace: using System.ComponentModel.DataAnnotations; And apply the attribute on a property. public class Product { [Require...

asp.net-mvc • Data annotations

StringLengthAttribute

The StringLength attribute specifies the minimum and maximum length of characters that are allowed in a data field. This attribute can be applied on properties, public fields and parameters. The error message must be specified on the ErrorMessage property on the attribute. The properties MinimumLeng...

asp.net-mvc • Data annotations

Routing basics

When you request the url yourSite/Home/Index through a browser, the routing module will direct the request to the Index action method of HomeController class. How does it know to send the request to this specific class's specific method ? there comes the RouteTable. Every application has a route ta...

asp.net-mvc • Routing

Reassigning thread objects

We can create empty thread objects and assign work to them later. If we assign a thread object to another active, joinable thread, std::terminate will automatically be called before the thread is replaced. #include <thread> void foo() { std::this_thread::sleep_for(std::chrono::seco...

C++ • Threading