php - class_exists

class_exists — Checks if the class has been defined

Description

bool class_exists ( string $class_name [, bool $autoload] )
This function checks whether or not the given class has been defined.

Parameters

class_name

The class name. The name is matched in a case-insensitive manner.

autoload

Whether or not to call __autoload by default. Defaults to TRUE.

Return Values

Returns TRUE if class_name is a defined class, FALSE otherwise.

ChangeLog

Version	Description
5.0.2	No longer returns TRUE for defined interfaces. Use interface_exists().
5.0.0	The autoload parameter was added.

Examples

Example 365. class_exists() example

<?php 
// Check that the class exists before trying to use it 
if (class_exists('MyClass')) {
$myclass = new MyClass();
}
?>

Example 366. autoload parameter example

<?php
function __autoload($class)
{
include($class . '.php');

// Check to see whether the include declared the class
if (!class_exists($class, false)) {
trigger_error("Unable to load class: $class", E_USER_WARNING);
}
}

if (class_exists('MyClass')) {
$myclass = new MyClass();
}
?>