Php/docs/function.is-subclass-of

• PHP Manual
• Classes/Object Functions
• Checks if the object has this class as one of its parents or implements it

is_subclass_of

(PHP 4, PHP 5, PHP 7)

is_subclass_of — Checks if the object has this class as one of its parents or implements it

Description

is_subclass_of ( mixed $object , string $class_name [, bool $allow_string = TRUE ] ) : bool

Checks if the given object has the class class_name as one of its parents or implements it.

Parameters

object

A class name or an object instance. No error is generated if the class does not exist.

class_name

The class name

allow_string

If this parameter set to false, string class name as object is not allowed. This also prevents from calling autoloader if the class doesn't exist.

Return Values

This function returns TRUE if the object object, belongs to a class which is a subclass of class_name, FALSE otherwise.

Examples

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";}// usable only since PHP 5.0.3if (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

Notes

Note:

Using this function will use any registered autoloaders if the class is not already known.

See Also

• get_class() - Returns the name of the class of an object
• get_parent_class() - Retrieves the parent class name for object or class
• is_a() - Checks if the object is of this class or has this class as one of its parents
• class_parents() - Return the parent classes of the given class