1. Object Oriented Programming (OOP)

Object-Oriented Programming (OOP) is a type of programming added to php5,With the release of php5, php programmers finally had the power to code with the ‘big boys’. Like Java and C#, php finally has a complete OOP infrastructure.

Before we move onto writing object-oriented code in PHP, it’s important to understand 4 fundamental OOP concepts: classes, objects, properties, and methods.

Classes:
A class is a blueprint for objects. When you build your object-oriented application, you typically create one or more classes representing various types of entities in your app.For example, if you’re writing a forum application, you might create classes called Forum, Topic, Post, and Member.

oop-class

You define your own class by starting with the keyword ‘class’ followed by the name
you want to give your new class.

<?php class person { } ?>

This class doesn’t do much until you’ve added properties and methods to the class.
Nevertheless, the above code creates a valid, usable class in PHP.

[ It’s good programming practice to put each class’s code in its own file, with the same name as the class.For example, you might put the above Member class code in a file called Member.php, and store the file in a folder called classes. ]

Objects:
An object is a special type of variable that is created from a class.It contains actual data, and you can call the object’s functions to do stuff to that data.You can create as many objects as you like from a single class.Each object functions independently of the others, even if they all come from the same class.

To use a real-world analogy:
. A class is like a blueprint for a car. It defines how cars created from the blueprint will look and behave, but it’s still an abstract concept.
. An object is like a real car created from the blueprint. It has real properties (such as how fast it’s going), and real behaviors (like “accelerate” and “brake”).

object

How to create objects in PHP:
You create an object from a class by using the new keyword, as follows:

<?php $stefan = new person(); ?>

Properties:
Class member variables are called “properties”.They are defined by using one of the keywords public, protected, or private, followed by a normal variable declaration.This declaration may include an initialization,but this initialization must be a constant value–that is,it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.

Within class methods non-static properties may be accessed by using -> (Object Operator): $this->property (where property is the name of the property).
Static properties are accessed by using the :: (Double Colon): self::$property.
Scope Resolution Operator (::) (also called Paamayim Nekudotayim)

The ‘$this’ variable:
You probably noticed this line of code: $this->name = $new_name The $this is a built-in pseudo variable (built into all objects) which points to the current object. Or in other words, $this is a special self-referencing variable. You use $this to access properties and to call other methods of the current class.

Methods:
The functions that are defined within a class — and used in an object — are known as methods.In many ways, they’re just like regular functions — you can pass values to them,they can contain local variables, and they can return values.

method

method-declare

method-return

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s