is it a php bug? (about extends)

Question

class A extends B {}
class B extends C{}
class C {}

result

PHP Fatal error: class 'B' not found ...

if the order is like this

class A extends B {}
class C {}
class B extends C{}

everything is ok.

---

PS: if I remove class C {}

class A extends B {}
class B extends C{}

php tells me class 'B' is not found, why?

php version 5.3.4

Answer 1

The PHP manual clearly mentions:

Classes must be defined before they are used! If you want the class Named_Cart to extend the class Cart, you will have to define the class Cart first. If you want to create another class called Yellow_named_cart based on the class Named_Cart you have to define Named_Cart first. To make it short: the order in which the classes are defined is important.