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

Question

Example: A method is supposed to return an instance of a SpecificClass. How can I check that return value if it is from that class?

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.