Tutorial by Examples: b

Raise a number to a power (POW)

To raise a number x to a power y, use either the POW() or POWER() functions SELECT POW(2,2); => 4 SELECT POW(4,2); => 16

MySQL • Arithmetic

Random Numbers (RAND)

Generate a random number To generate a pseudorandom floating point number between 0 and 1, use the RAND() function Suppose you have the following query SELECT i, RAND() FROM t; This will return something like this iRAND()10.619143887068220.9384516830914230.83482678498591 Random Number in a r...

MySQL • Arithmetic

Absolute Value and Sign (ABS, SIGN)

Return the absolute value of a number SELECT ABS(2); -> 2 SELECT ABS(-46); -> 46 The sign of a number compares it to 0. SignResultExample-1n < 0SELECT SIGN(42); -> 10n = 0SELECT SIGN(0); -> 01n > 0SELECT SIGN(-3); -> -1 SELECT SIGN(-423421); -> -1

MySQL • Arithmetic

Create unconnected socket, try connect to it and check if connection is established

public class ConnectSocketExample { private int HTTP_PORT = 80; /** * example method to create unconnected socket * then connect to it * at end return connected socket * * @param httpHostName - endpoint host name fot socket connection * @throws IOEx...

sockets • Getting started with sockets

Implementing Enums Using Symbols

As ES6 introduced Symbols, which are both unique and immutable primitive values that may be used as the key of an Object property, instead of using strings as possible values for an enum, it's possible to use symbols. // Simple symbol const newSymbol = Symbol(); typeof newSymbol === 'symbol' // t...

JavaScript • Enumerations

Customising the CMS / White Labeling

The SilverStripe CMS can be customised to change the CMS logo, link and application name. This can be achieved with the following config.yml settings LeftAndMain: application_name: 'My Application' application_link: 'http://www.example.com/' extra_requirements_css: - mysite/css/cms.c...

silverstripe • Getting started with silverstripe

Subclassing SKScene to Implement Primary SpriteKit Functionality

SpriteKit functionality can be implemented in a subclass of SKScene. For example, a game may implement the main game functionality within an SKScene subclass called GameScene. In Swift: import SpriteKit class GameScene: SKScene { override func didMoveToView(view: SKView) { /* Co...

sprite-kit • SKScene

Objects as a function

class SomeClass { public function __invoke($param1, $param2) { // put your code here } } $instance = new SomeClass(); $instance('First', 'Second'); // call the __invoke() method An object with an __invoke method can be used exactly as any other function. The __invoke meth...

PHP • Functional Programming

Get some basic browser data and return it as a JSON object

The following function can be used to get some basic information about the current browser and return it in JSON format. function getBrowserInfo() { var json = "[{", /* The array containing the browser info */ info = [ navigator.userA...

JavaScript • Navigator Object

Bit Value Type

The BIT type is useful for storing bit-field values. BIT(M) allows storage of up to M-bit values where M is in the range of 1 to 64 You can also specify values with bit value notation. b'111' -> 7 b'10000000' -> 128 Sometimes it is handy to use 'shift' to construct a single-bit valu...

MySQL • Data Types

Creating a WebSocket communication

WebSocket provides a duplex/bidirectional communication protocol over a single TCP connection. the client opens a connection to a server that is listening for a WebSocket request a client connects to a server using a URI. A server may listen to requests from multiple clients. Server Endpoint...

java-ee • The WebSockets API

What characters need to be escaped?

Character escaping is what allows certain characters (reserved by the regex engine for manipulating searches) to be literally searched for and found in the input string. Escaping depends on context, therefore this example does not cover string or delimiter escaping. Backslashes Saying that backsla...

Regular Expressions • Escaping

Matching pairs (like parenthesis, brackets…)

Some regex engines (such as .NET) can handle context-free expressions, and will work it out. But that's not the case for most standard engines. And even if they do, you'll end up having a complex hard-to-read expression, whereas using a parsing library could make the job easier. How to find all p...

Regular Expressions • When you should NOT use Regular Expressions

Sending a POST Request with arguments using NSURLSession in Objective-C

There are two common ways to encode a POST request body: URL encoding (application/x-www-form-urlencoded) and form data (multipart/form-data). Much of the code is similar, but the way you construct the body data is different. Sending a request using URL encoding Be it you have a server for your s...

iOS • NSURLSession

Basics

GSP supports the usage of <% %> scriptlet blocks to embed Groovy code (this is discouraged): <html> <body> <% out << "Hello GSP!" %> </body> </html> You can also use the <%= %> syntax to output values, like in JSP: <htm...

grails • GSP

Communicating with a Web Worker

Since workers run in a separate thread from the one that created them, communication needs to happen via postMessage. Note: Because of the different export prefixes, some browsers have webkitPostMessage instead of postMessage. You should override postMessage to make sure workers "work" (n...

JavaScript • Workers

Basics of Higher Order Functions

Review Partial Application before proceeding. In Haskell, a function that can take other functions as arguments or return functions is called a higher-order function. The following are all higher-order functions: map :: (a -> b) -> [a] -> [b] filter :: (a -> Bool) -> [a] ...

Haskell Language • Higher-order functions

Creating Object and setting properties using reflection

Lets say we have a class Classy that has property Propertua public class Classy { public string Propertua {get; set;} } to set Propertua using reflection: var typeOfClassy = typeof (Classy); var classy = new Classy(); var prop = typeOfClassy.GetProperty("Propertua"); prop.Se...

.NET Framework • Reflection

Navigating to the beginning of a specific word

When editing text, a common task is to navigate to a particular word on the screen. In these examples we explore how we can navigate to the word updated. For the sake of consistency across the examples, we aim to land on the first letter of the word. Mid-screen jump M$B This approach is quick...

vim • Movement

A doubly linked list

An example of code showing how nodes can be inserted at a doubly linked list, how the list can easily be reversed, and how it can be printed in reverse. #include <stdio.h> #include <stdlib.h> /* This data is not always stored in a structure, but it is sometimes for ease of use */ s...

C Language • Linked lists