(PHP 4, PHP 5) class_exists- Checking whether a class is defined
BOOL class_exists ( string $class _name [, bool $autoload ])
If the class referred to by class_name is already defined, this function returns TRUE, otherwise FALSEis returned.
Example #1 class_exists () Example
<? PHP // Check The class exists before trying to use it if (class_exists(' MyClass ')) { $myclassnew MyClass ();}? >
class_exists () will attempt to call _autoload by default, and if you do not want class_exists () to call _autoload, you can AutoLoad The parameter is set to FALSE.
Example #2 autoload parameter examples
<?PHPfunction__autoload ($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=NewMyClass ();}?>
PHP class_exists Check if class is defined