PHP OOP - Classes and Objects

PHP OOP Classes and Objects

A class is a template for objects, and it defines the structure (properties) and behavior (methods) of an object.

An object is an individual instance of a class.

Define a Class

A class is defined with the class keyword, followed by the name of the class and a pair of curly braces ({}). All its properties and methods go inside the braces.

Assume we create a class named Fruit. The Fruit class can have properties like name and color. In addition, the Fruit class has two methods for setting and getting the details:

<?php
class Fruit {
// Properties
public $name;
public $color;

// Method to set the properties
function set_details($name, $color) {
    $this->name = $name;
    $this->color = $color;
}

// Method to display the properties
function get_details() {
    echo "Name: " . $this->name . ". Color: " . $this->color .".<br>";
}
}
?>

Note: Properties are variables within in a class and methods are functions within a class.

Note: The this keyword is used within a method to refer to the current object's properties and methods.

Define Objects

Classes are nothing without objects! We can create multiple objects (instances) from a class. Each object inherits all the properties and methods defined in the class, but each object will have their own property values.

Objects of a class are created with the new keyword.

In the example below, we create two objects ($apple and $banana) from the Fruit class:

Example

<?php
public $name;
public $color;

function set_details($name, $color) {
    $this->name = $name;
    $this->color = $color;
}

function get_details() {
    echo "Name: " . $this->name . ". Color: " . $this->color .".<br>";
}
}

// Create an object named $apple from the Fruit class
$apple = new Fruit();
$apple->set_details('Apple', 'Red'); // Set property values
$apple->get_details(); // Get output

// Create an object named $banana from the Fruit class
$banana = new Fruit();
$banana->set_details('Banana', 'Yellow'); // Set property values
$banana->get_details(); // Get output
?>

Try it Yourself »