class not found when extending class that implements interface in PHP

Question

<?php

class A extends B {}

class B implements C {}

interface C {}

the code above throws "Fatal error: Class 'B' not found"... Is it a php bug? Or?

Environment: "PHP 5.3.6-13ubuntu3.2 with Suhosin-Patch (cli) (built: Oct 13 2011 23:19:13) Copyright (c) 1997-2011 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend Technologies with Xdebug v2.1.0, Copyright (c) 2002-2010, by Derick Rethans "

Is that all the code there is? Also, can't call C if its not created yet (order) — Jakub

Farray Farray · Accepted Answer · 2011-12-01T06:42:30

You have trouble specifically with the order of your class definitions. As long as the interface is defined in the same file, it can be declared anywhere - but classes must be defined before they can be extended.

The following is perfectly valid order in PHP:

class B implements C { ... }
class A extends B { ... }
interface C { ... }

There is a closed bug requesting clarification in the PHP5 docs.

An answer to a similar question (Does the order of class definition matter in PHP?) mentions Autoloading. You may want to look into this if you're using multiple files.

class not found when extending class that implements interface in PHP

2 Answers