Function Overloading and Overriding in PHP

Function Overloading in PHP

Function overloading is a feature that permits making creating several methods with a similar name that works differently from one another in the type of the input parameters it accepts as arguments.

Example

Let us now see an example to implement function overloading−

 Live Demo

<?php
   class Shape {
      const PI = 3.142 ;
      function __call($name,$arg){
         if($name == 'area')
            switch(count($arg)){
               case 0 : return 0 ;
               case 1 : return self::PI * $arg[0] ;
               case 2 : return $arg[0] * $arg[1];
            }
      }
   }
   $circle = new Shape();
   echo $circle->area(3);
   $rect = new Shape();
   echo $rect->area(8,6);
?>

Output

This will produce the following output−

9.42648

Function Overriding in PHP

In function overriding, the parent and child classes have the same function name with and number of arguments

Example

Let us now see an example to implement function overriding−

 Live Demo

<?php
   class Base {
      function display() {
         echo "
Base class function declared final!";
      }
      function demo() {
         echo "
Base class function!";
      }
   }
   class Derived extends Base {
      function demo() {
         echo "
Derived class function!";
      }
   }
   $ob = new Base;
   $ob->demo();
   $ob->display();
   $ob2 = new Derived;
   $ob2->demo();
   $ob2->display();
?>

Output

This will produce the following output−

Base class function!
Base class function declared final!
Derived class function!
Base class function declared final!