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PHP Manual

Classes/Object Functions
PHP Manual

class_exists

(PHP 4, PHP 5)

class_exists — Checks if the class has been defined

Description

bool class_exists ( string $class_name [, bool $autoload = true ] )

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.

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 #1 class_exists() example

<?php
// Check that 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 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();
}

?>

See Also

Classes/Object Functions
PHP Manual


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PHP-Index
  1. Introduction
  2. Installation and Configuration
  3. Language reference
  4. Security
  5. Features
  6. Function reference
  7. PHP and zend engine internal
  8. FAQ: Frequently Asked Questions
  9. Appendices



 

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