PHP interface_exists() Function

The interface_exists() function is an inbuilt function in PHP that checks interface is defined or not.

Syntax:

bool interface_exists(string $interface, bool $autoload = true)

Parameters: This function accept two parameters that are described below:

• $interface: This parameter holds the interface name.
• $autoload: This parameter checks whether to call autoload or not by default.

Return Value: If the given interface is defined, then it returns “true”, otherwise it will return “false”.

Example 1: In this example, we will check interface is defined or not by using the interface_exists() function.

PHP

<?php
    if (interface_exists('MyInterface')) {
        class MyClass implements MyInterface {
    }
        echo "A class using 'Interface' is created.";
    } else {
        echo "'Interface' do not exist!.";
    }
?>

Output:

'Interface' does not exist!

Example 2: In the below code example, we will define an interface and then use the interface_exists() function.

PHP

<?php
    interface MyInterface{
        public function hello() ;
    }
    if (interface_exists('MyInterface')) {
        class MyClass implements MyInterface {
            function hello(){
                echo "Hey GeeksforGeeks";
            }
        }
        echo "A class using 'Interface' is created.\n";
    } else {
        echo "'Interface' does not exist!.";
    }

    $MyInterface = new MyClass() ;
    $MyInterface->hello() ;
?>

Output:

A class using 'Interface' is created.
Hey GeeksforGeeks

Reference: https://www.php.net/manual/en/function.interface-exists.php