How do you know the correct path to use in a PHP require_once() statement

Question

As many do I have a config.php file in the root of a web app that I want to include in almost every other php file. So most of them have a line like:

require_on         


        

Answer 1

I like to do this:

require_once(dirname(__FILE__)."/../_include/header.inc");

That way your paths can always be relative to the current file location.