Can I check if an object is kind of a specific class, in PHP?

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/1965722/can-i-check-if-an-object-is-kind-of-a-specific-class-in-php

Answer 1

You can use the instanceof operator, to check if an object is an instance of :

• A class
• Or a child class of that class
• Or an instance of a class that implements an interface

Which means that it cannot be used to detect if your object is an instance of a specific class -- as it will say "yes" if your object is an instance of a child-class of that class.

For instance, this portion of code :

class ClassA {}
class ClassB extends ClassA {}

$a = new ClassB();
if ($a instanceof ClassA) {
    echo '$a is an instanceof ClassA<br />';
}
if ($a instanceof ClassB) {
    echo '$a is an instanceof ClassB<br />';
}

Will get you this output :

$a is an instanceof ClassA
$a is an instanceof ClassB

$a, in a way, is an instance of ClassA, as ClassB is a child-class of ClassA.

And, of course, $a is also an instance of ClassB -- see the line where it's instanciated.