Absolute/relative path with includes

[earachefl]

I found one post that related to this topic but I want to make sure I understand. If I have a site with the structure:

 

/root/

____pageone.php

____common/

___________base.php

___________header.php

____inc/

______constants.inc.php

____admin/

_________login.php

 

and base.php includes:

<?php
// Include site constants
include_once "../inc/constants.inc.php";
?>

and login.php includes:

<?php
include_once "../common/base.php";
$pageTitle = "Log in";
include_once "../common/header.php";
?>

and pageone.php includes:

<?php
include_once "common/base.php";
$pageTitle = "Page One";
include_once "common/header.php";
?>

the login page loads normally, but pageone.php is broken; I get error messages like

Warning: include_once(../inc/constants.inc.php) [function.include-once]: failed to open stream: No such file or directory in /Applications/XAMPP/xamppfiles/htdocs/rootdirectory/common/base.php on line 10

.

 

From what I understand, PHP doesn't want to include the same files from different relative paths; you either need to use absolute paths or change the directory structure so that the included files are accessed through the exact same relative path. Is this correct? I find that if I move pageone.php to the admin folder and make the relative path the same, it does work.

 

I have to say, I'm leery of using absolute paths; and if I'm understanding this correctly, you're really constrained on how you set up your directory structure. Comments?