如何将php文件包含在不同目录中的另外两个文件中? (不是相反!)

I'm having a problem with the folowing:

I have a file called config.php, which I include in two other pages: login.php and index.php. The pages are organized as follows:

           index.php
           Config/config.php
           Page/Users/Login/login.php
           lib/smarty.php

My problem, is that, within config.php, I have another include to a different file: smarty.php. But because index.php and login.php are not on the same level, the smarty file only works for one of them:

Example : if I have, in config.php:
include('lib/smarty.php')

then it only works for index.php

      if I have          include('../../../lib/smarty.php') 

then it only works for login.php

Is there a way for me to use the same config.php for both login.php and index.php and have smarty.php work for both?

I hope I was clear, and thank you in advance

NOTE: The problem is not how to include files from different folders into another, it is to include one file into two different pages in different directories and with different paths.

Use dirname(__FILE__), or if available, __DIR__ (PHP >= 5.3). They resolve to the full path of the directory the current file is in. It is better than explicitly using the current absolute path to the file because it allows you to move the files in the file system (as long as the files stay in the same location, relative to each other).

You'll have to change Config/config.php to include lib/smarty.php like so:

include(dirname(__FILE__) . '/../lib/smarty.php');

While you're at it, you should probably change your other include/require to use a similar construct.

Use the absolute path in all of your includes.

like:

include '/var/www/html/Config/config.php';