class_exists
(PHP 4 , PHP 5)
class_exists -- Checks if the class has been defined
Description
bool
class_exists ( string class_name [, bool autoload])
Note:
The autoload parameter was added in PHP 5
This function returns TRUE if the class given by
class_name has been defined,
FALSE otherwise.
class_exists() will attempt to call __autoload by
default, if you don't want class_exists() to
call __autoload(), you can set the parameter autoload
to FALSE.
Example 1. autoload parameter example
<?php
function __autoload($class) {
include($class . '.php');
/* Check to see it the include defined the class */
if ( !class_exists($class, false) ) {
trigger_error("Unable to load class $class", E_USER_ERROR);
}
}
if( class_exists('MyClass') ) {
$myclass = new MyClass();
}
?>
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See also get_declared_classes().