(PHP 4, PHP 5, PHP 7, PHP 8)
is_subclass_of — Checks if the object has this class as one of its parents or implements it
Checks if the given object_or_class
has the class
class
as one of its parents or implements it.
object_or_class
A class name or an object instance. No error is generated if the class does not exist.
class
The class name
allow_string
If this parameter set to false, string class name as object_or_class
is not allowed. This also prevents from calling autoloader if the class doesn't exist.
This function returns true
if the object object_or_class
,
belongs to a class which is a subclass of
class
, false
otherwise.
Example #1 is_subclass_of() example
<?php// define a classclass WidgetFactory{ var $oink = 'moo';}// define a child classclass WidgetFactory_Child extends WidgetFactory{ var $oink = 'oink';}// create a new object$WF = new WidgetFactory();$WFC = new WidgetFactory_Child();if (is_subclass_of($WFC, 'WidgetFactory')) { echo "yes, \$WFC is a subclass of WidgetFactory\n";} else { echo "no, \$WFC is not a subclass of WidgetFactory\n";}if (is_subclass_of($WF, 'WidgetFactory')) { echo "yes, \$WF is a subclass of WidgetFactory\n";} else { echo "no, \$WF is not a subclass of WidgetFactory\n";}if (is_subclass_of('WidgetFactory_Child', 'WidgetFactory')) { echo "yes, WidgetFactory_Child is a subclass of WidgetFactory\n";} else { echo "no, WidgetFactory_Child is not a subclass of WidgetFactory\n";}?>
The above example will output:
yes, $WFC is a subclass of WidgetFactory no, $WF is not a subclass of WidgetFactory yes, WidgetFactory_Child is a subclass of WidgetFactory
Example #2 is_subclass_of() using interface example
<?php// Define the Interfaceinterface MyInterface{ public function MyFunction();}// Define the class implementation of the interfaceclass MyClass implements MyInterface{ public function MyFunction() { return "MyClass Implements MyInterface!"; }}// Instantiate the object$my_object = new MyClass;// Works since 5.3.7// Test using the object instance of the classif (is_subclass_of($my_object, 'MyInterface')) { echo "Yes, \$my_object is a subclass of MyInterface\n";} else { echo "No, \$my_object is not a subclass of MyInterface\n";}// Test using a string of the class nameif (is_subclass_of('MyClass', 'MyInterface')) { echo "Yes, MyClass is a subclass of MyInterface\n";} else { echo "No, MyClass is not a subclass of MyInterface\n";}?>
The above example will output:
Yes, $my_object is a subclass of MyInterface Yes, MyClass is a subclass of MyInterface
Note:
Using this function will use any registered autoloaders if the class is not already known.