How do I format a PHP include() absolute (rather than relative) path?

Question

On various pages throughout my PHP web site and in various nested directories I want to include a specific file at a path relative to the root.

What single command can I put on both of these pages...

http://www.example.com/pageone.php

http://www.example.com/somedirectory/pagetwo.php

...to include this page:

http://www.example.com/includes/analytics.php

This does not work:

<?php include('/includes/analytics.php'); ?> 

Does it matter that this is hosted in IIS on Windows?

Answer 1

You can just use include $_SERVER['DOCUMENT_ROOT'] . "/includes/analytics.php";