(PHP 4, PHP 5, PHP 7, PHP 8)
is_subclass_of — 如果此對象是該類(lèi)的子類(lèi)，則返回 true
$object, string $class_name): bool
如果對象 object
所屬類(lèi)是類(lèi) class_name
的子類(lèi)，則返回 true，否則返回 false。
注意:
自 PHP 5.0.3 起也可以用一個(gè)字符串來(lái)指定
object參數（類(lèi)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";
}
?>
以上例程會(huì )輸出：
yes, $WFC is a subclass of WidgetFactory no, $WF is not a subclass of WidgetFactory yes, WidgetFactory_Child is a subclass of WidgetFactory
參見(jiàn) 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";
}
?>
以上例程會(huì )輸出：
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:
如果此類(lèi)不是已知類(lèi)，使用此函數會(huì )使用任何已注冊的 autoloader。