(PHP 4, PHP 5)

is_subclass_ofChecks if the object has this class as one of its parents


bool is_subclass_of ( mixed $object , string $class_name )

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



A class name or an object instance


The class name

Return Values

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


Version Description
5.0.3 You may also specify the object parameter as a string (the name of the class)


Example #1 is_subclass_of() example

// define a class
class WidgetFactory
$oink 'moo';

// define a child class
class WidgetFactory_Child extends WidgetFactory
$oink 'oink';

// create a new object
$WF = new WidgetFactory();
$WFC = new WidgetFactory_Child();

if (
is_subclass_of($WFC'WidgetFactory')) {
"yes, \$WFC is a subclass of WidgetFactory\n";
} else {
"no, \$WFC is not a subclass of WidgetFactory\n";

if (
is_subclass_of($WF'WidgetFactory')) {
"yes, \$WF is a subclass of WidgetFactory\n";
} else {
"no, \$WF is not a subclass of WidgetFactory\n";

// usable only since PHP 5.0.3
if (is_subclass_of('WidgetFactory_Child''WidgetFactory')) {
"yes, WidgetFactory_Child is a subclass of WidgetFactory\n";
} else {
"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



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

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