PHP class_exists Check if class is defined

(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