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
- function_exists() - Return TRUE if the given function has been defined
- interface_exists() - Checks if the interface has been defined
- get_declared_classes() - Returns an array with the name of the defined classes