Example of Inheritance in PHP

class_inheritance.php

<?php

class aParent {
    public $a = 'a';
	protected $b = 'b';
	private $c = 'c';
}

class aChild extends aParent {
	
	public function __construct()
	{
		$this->a .= 'a';
		$this->b .= 'b';
		$this->c .= 'c';
	}
}

class aGrandChild extends aChild {
	
	public function __construct()
	{
		$this->a .= 'a';
		$this->b .= 'b';
		$this->c .= 'c';
	}
}

# GrandChild
$gc = new aGrandChild();

echo $gc->a; // Outputs 'aa'
// echo $gc->b; /* Throws an access error */
// echo $gc-c; /* Throws an access error */

# Child
$c = new aChild();

echo $c->a; // Outputs 'aa'
// echo $c->b;	/* Throws an access error on variables, a protected */
				/*	method would be accessible */
// echo $c->c; /* Throws an access error */