Tutorial by Examples: c

Validates a value is a valid MAC address var_dump(filter_var('FA-F9-DD-B2-5E-0D', FILTER_VALIDATE_MAC)); var_dump(filter_var('DC-BB-17-9A-CE-81', FILTER_VALIDATE_MAC)); var_dump(filter_var('96-D5-9E-67-40-AB', FILTER_VALIDATE_MAC)); var_dump(filter_var('96-D5-9E-67-40', FILTER_VALIDATE_MAC)); v...

The process.env property returns an object containing the user environment. It returns an object like this one : { TERM: 'xterm-256color', SHELL: '/usr/local/bin/bash', USER: 'maciej', PATH: '~/.bin/:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin', PWD: '/Users/maciej', EDITOR: 'vi...

Spacemacs is a distribution of emacs that comes with a lot of packages preconfigured and easily installed. Also, it is very friendly for those who are familiar with vim style of editing. Spacemacs provides a CIDER-based Clojure layer. To install and configure it for use with Clojure, first install ...

Interfaces should be named with nouns or noun phrases, or adjectives that describe behaviour. For example IComponent uses a descriptive noun, ICustomAttributeProvider uses a noun phrase and IPersistable uses an adjective. Interface names should be prefixed with the letter I, to indicate that the ty...

Backpressure is when in an Observable processing pipeline, some asynchronous stages can't process the values fast enough and need a way to tell the upstream producer to slow down. The classic case of the need for backpressure is when the producer is a hot source: PublishSubject<Integer> sour...

As well as allowing module entities to have access control (being public or private) modules entities may also have the protect attribute. A public protected entity may be use associated, but the used entity is subject to restrictions on its use. module mod integer, public, protected :: i=1 en...

Asynchronously var fs = require('fs'); fs.stat('path/to/file', function(err) { if (!err) { console.log('file or directory exists'); } else if (err.code === 'ENOENT') { console.log('file or directory does not exist'); } }); Synchronously here, we must wr...

There may be situations where you have setup a pool of MySQL connections, but you have a number of queries you would like to run in sequence: SELECT 1; SELECT 2; You could just run then using pool.query as seen elsewhere, however if you only have one free connection in the pool you must wait un...

You can attach the query executed to your err object when an error occurs: var q = mysql.query('SELECT `name` FROM `pokedex` WHERE `id` = ?', [ 25 ], function (err, result) { if (err) { // Table 'test.pokedex' doesn't exist err.query = q.sql; // SELECT `name` FROM `pokedex` WHERE `id` ...

0-1 Knapsack The Knapsack Problem is a problem when given a set of items, each with a weight, a value and exactly 1 copy, determine the which item(s) to include in a collection so that the total weight is less than or equal to a given limit and the total value is as large as possible. C++ Exampl...

Callback-based: db.notification.email.find({subject: 'promisify callback'}, (error, result) => { if (error) { console.log(error); } // normal code here }); This uses bluebird's promisifyAll method to promisify what is conventionally callback-based code like above. blueb...

Dependencies can also be injected by setters. interface Logger { public function log($message); } class Component { private $logger; private $databaseConnection; public function __construct(DatabaseConnection $databaseConnection) { $this->databaseConnection = $...

The most important application events are: Application_Start - It is raised when the application/website is started. Application_End - It is raised when the application/website is stopped. Similarly, the most used Session events are: Session_Start - It is raised when a user first requests a page...

Common page and control events are: DataBinding - It is raised when a control binds to a data source. Disposed - It is raised when the page or the control is released. Error - It is a page event, occurs when an unhandled exception is thrown. Init - It is raised when the page or the control is in...

PHP 5.x5.4 When you build REST API's, you may need to reduce the information of an object to be passed to the client application. For this purpose, this example illustrates how to use the JsonSerialiazble interface. In this example, the class User actually extends a DB model object of a hypotetica...

Laravel allows user work on multiple database connections. If you need to connect to multiple databases and make them work together, you are beware of the connection setup. You also allow using different types of database in the same application if you required. Default connection In config/dat...

You've made a stash and wish to checkout only some of the files in that stash. git checkout stash@{0} -- myfile.txt

We can use the Service Container as a Dependency Injection Container by binding the creation process of objects with their dependencies in one point of the application Let's suppose that the creation of a PdfCreator needs two objects as dependencies; every time we need to build an instance of PdfCr...

There are multiple ways to create a sequence. You can use functions from the Seq module: // Create an empty generic sequence let emptySeq = Seq.empty // Create an empty int sequence let emptyIntSeq = Seq.empty<int> // Create a sequence with one element let singletonSeq = Seq.s...

TCO is only available in strict mode As always check browser and Javascript implementations for support of any language features, and as with any javascript feature or syntax, it may change in the future. It provides a way to optimise recursive and deeply nested function calls by eliminating the n...