The class_exists() function is an inbuilt function in PHP which is used to check whether the given class is defined or not.
Syntax:
bool class_exists( string $class_name, bool $autoload = TRUE )
Parameters: This function accept two parameters as mentioned above and described below:
- $class_name: It holds the class name which need to check their existence.
- $autoload: It checks whether the __autoload is called or not by default.
Return Value: This function returns True if class name is defined otherwise returns False.
Below programs illustrate the class_exists() function in PHP:
Program 1:
<?php   // Create a class class GFG {     public $Geek_name = "Welcome to neveropen"; }   // Check class name exist or not if(class_exists('GFG')) {     echo "Class name exists"; } else {     echo "Class name does not exist"; }   ?> |
Output:
Class name exists
Program 2:
<?php   // Creating class class GFG {     public $data1;     public $data2;     public $data3; }   if(class_exists('GFG')) {       // Creating an object     $obj = new GFG();       // Set values of $obj object     $obj->data1 = "Geeks";     $obj->data2 = "for";     $obj->data3 = "Geeks";       // Print values of $obj object     echo "$obj->data1 \n$obj->data2 \n$obj->data3"; } else {     echo "Class does not exist"; }   ?> |
Output:
Geeks for Geeks
Reference: https://www.php.net/manual/en/function.class-exists.php
