Php/docs/function.is-subclass-of
is_subclass_of
(PHP 4, PHP 5, PHP 7)
is_subclass_of — 如果此对象是该类的子类,则返回 true
说明
is_subclass_of
( object $object
, string $class_name
) : bool
如果对象 object
所属类是类 class_name
的子类,则返回 true
,否则返回 false
。
Note:
自 PHP 5.0.3 起也可以用一个字符串来指定
object
参数(类名)。
Example #1 is_subclass_of() 例子
<?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";}?>
以上例程会输出:
yes, $WFC is a subclass of WidgetFactory no, $WF is not a subclass of WidgetFactory yes, WidgetFactory_Child is a subclass of WidgetFactory
参见 get_class()、 get_parent_class() 和 is_a()。
参数
object
- A class name or an object instance
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.
返回值
This function returns true
if the object object
,
belongs to a class which is a subclass of
class_name
, false
otherwise.
范例
Example #2 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";}?>
以上例程会输出:
yes, $WFC is a subclass of WidgetFactory no, $WF is not a subclass of WidgetFactory yes, WidgetFactory_Child is a subclass of WidgetFactory
注释
Note:
如果此类不是已知类,使用此函数会使用任何已注册的 autoloader。
参见
- get_class() - 返回对象的类名
- get_parent_class() - 返回对象或类的父类名
- is_a() - 如果对象属于该类或该类是此对象的父类则返回 true
- class_parents() - 返回指定类的父类。