In HTML, I can find a file starting from the web server\'s root folder by beginning the filepath with "/". Like:
/images/some_image
What I do is put a config.php file in my root directory. This file is included by all PHP files in my project. In that config.php file, I then do the following;
define( 'ROOT_DIR', dirname(__FILE__) );
Then in all files, I know what the root of my project is and can do stuff like this
require_once( ROOT_DIR.'/include/functions.php' );
Sorry, no bonus points for getting outside of the public directory ;) This also has the unfortunate side affect that you still need a relative path for finding config.php, but it makes the rest of your includes much easier.