(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
$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。
objectThe tested object
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.
Returns TRUE if the object is of this class or has this class as one of
its parents, FALSE otherwise.
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';
}
?>