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Function overloading and Overriding in PHP

  • Difficulty Level : Medium
  • Last Updated : 22 Oct, 2021

Function overloading and overriding is the OOPs feature in PHP. In function overloading, more than one function can have same method signature but different number of arguments. But in case of function overriding, more than one functions will have same method signature and number of arguments. 
Function Overloading: Function overloading contains same function name and that function performs different task according to number of arguments. For example, find the area of certain shapes where radius are given then it should return area of circle if height and width are given then it should give area of rectangle and others. Like other OOP languages function overloading can not be done by native approach. In PHP function overloading is done with the help of magic function __call(). This function takes function name and arguments. 
Example: 
 

php




<?php
// PHP program to explain function
// overloading in PHP
 
// Creating a class of type shape
class shape {
     
    // __call is magic function which accepts
    // function name and arguments
    function __call($name_of_function, $arguments) {
             
        // It will match the function name
        if($name_of_function == 'area') {
             
            switch (count($arguments)) {
                     
                // If there is only one argument
                // area of circle
                case 1:
                    return 3.14 * $arguments[0];
                         
                // IF two arguments then area is rectangle;
                case 2:
                    return $arguments[0]*$arguments[1];
            }
        }
    }
}
     
// Declaring a shape type object
$s = new Shape;
     
// Functio call
echo($s->area(2));
echo "\n";
     
// calling area method for rectangle
echo ($s->area(4, 2));
?>
Output: 
6.28
8

 

Function Overriding: Function overriding is same as other OOPs programming languages. In function overriding, both parent and child classes should have same function name with and number of arguments. It is used to replace parent method in child class. The purpose of overriding is to change the behavior of parent class method. The two methods with the same name and same parameter is called overriding.
Example: 
 

php




<?php
// PHP program to implement
// function overriding
 
// This is parent class
class P {
     
    // Function geeks of parent class
    function geeks() {
        echo "Parent";
    }
}
 
// This is child class
class C extends P {
     
    // Overriding geeks method
    function geeks() {
        echo "\nChild";
    }
}
 
// Reference type of parent
$p = new P;
 
// Reference type of child
$c= new C;
 
// print Parent
$p->geeks();
 
// Print child
$c->geeks();
?>
Output: 
Parent
Child

 

PHP is a server-side scripting language designed specifically for web development. You can learn PHP from the ground up by following this PHP Tutorial and PHP Examples.




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