(PHP 4, PHP 5, PHP 7, PHP 8)
is_subclass_of — 如果此对象是该类的子类，则返回 true
$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。
注意:
自 PHP 5.0.3 起也可以用一个字符串来指定
object参数（类名）。
示例 #1 is_subclass_of() 例子
<?php
// define a class
class WidgetFactory
{
var $oink = 'moo';
}
// define a child class
class 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 5.0.3
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";
}
?>
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()。
objectA class name or an object instance
class_nameThe 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.
This function returns true if the object object,
belongs to a class which is a subclass of
class_name, false otherwise.
示例 #2 is_subclass_of() example
<?php
// define a class
class WidgetFactory
{
var $oink = 'moo';
}
// define a child class
class 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 5.0.3
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";
}
?>
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
注意:
如果此类不是已知类，使用此函数会使用任何已注册的 autoloader。