PHP Manual: class_exists


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class_exists

(PHP 4, PHP 5)

class_exists -- Checks if the class has been defined

Description

bool class_exists ( string class_name [, bool autoload] )

This function checks if the given class have been defined.

Parameters

class_name

The class name

autoload

Whether to call __autoload or not by default

Return Values

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

ChangeLog

VersionDescription
5.0.0 The autoload was added.

Examples

Example 1. class_exists() example

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

?>

Example 2. autoload parameter example

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

    
// Check to see if 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();
}

?>