problem with require_once

Question

I have a file structure like this

config 
  config.php
library
  data.php
folder
  file1.php
libs.inc.php
test1.php

In config file iam including require_once('libs.inc.php'); and require_once('./library/data.php'); In file1.php i am including config file using 'require_once('../config/config.php');' But it showing error in require_once('libs.inc.php'); and require_once('./library/data.php'); How i can solve this problem Thanks in advance..

Answer 1

In config.php:

require_once('../library/data.php');
require_once('../libs.inc.php');

Answer 2

require_once(dirname(__FILE__).'/../library/data.php');
require_once(dirname(__FILE__).'/../libs.inc.php');

or

require_once($_SERVER['DOCUMENT_ROOT'].'/library/data.php');
require_once($_SERVER['DOCUMENT_ROOT'].'/libs.inc.php');