is_a
(PHP 4 >= 4.2.0, PHP 5, PHP 7)
is_a — 如果对象属于该类或该类是此对象的父类则返回 TRUE
说明
is_a (
object
$object ,
string $class_name [,
bool $allow_string = FALSE ] ) :
bool
如果 object 是该类或该类是此对象的父类。
参数
-
object -
The tested object
-
class_name -
The class name
-
allow_string -
If this parameter set to
FALSE, string class name asobjectis not allowed. This also prevents from calling autoloader if the class doesn't exist.
返回值
Returns TRUE if the object is of this class or has this class as one of its parents, FALSE otherwise.
更新日志
| 版本 | 说明 |
|---|---|
| 5.3.9 | Added allow_string parameter |
| 5.3.0 | This function is no longer deprecated, and will therefore no longer throw E_STRICT warnings. |
| 5.0.0 | This function became deprecated in favour of the instanceof operator. Calling this function will result in an E_STRICT warning. |
范例
Example #1 is_a() 例子
<?php
// define a class
class WidgetFactory
{
var $oink = 'moo';
}
// create a new object
$WF = new WidgetFactory();
if (is_a($WF, 'WidgetFactory')) {
echo "yes, \$WF is still a WidgetFactory\n";
}
?>
Example #2 在 PHP 5 中使用 instanceof 运算符
<?php
if ($WF instanceof WidgetFactory) {
echo 'Yes, $WF is a WidgetFactory';
}
?>
