I am trying to connect my php script with my database in an online server. I am trying to use require_once function however, I am getting the fatal_error with the following error message.

Warning: require_once(/home/username/public_html/droidDBtest/android_login_api/include/DB_Functions.php): failed to open stream: No such file or directory in /home/username/public_html/droidDBtest/android_login_api/register.php on line 3

Fatal error: require_once(): Failed opening required '/home/username/public_html/droidDBtest/android_login_api/include/DB_Functions.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/username/public_html/droidDBtest/android_login_api/register.php on line 3

I tried to follow the first result's of stackoverflow and added Document Root, however, it's still not working. This is the code where I am getting an error :

require_once ($_SERVER['DOCUMENT_ROOT'].'/android_login_api/include/DB_Functions.php');

The following is my folder structure in my server

 public_html/
     -- droidDBtest
        -- android_login_api
            -- include
                 config.php
                 DB_Connect.php
                 DB_Functions.php
               register.php

Thanks in advance.

Lookin at your directory structure, and assuming socument root is public_html, you shoud do this:

require_once ($_SERVER['DOCUMENT_ROOT'].'/droidDBtest/android_login_api/include/DB_Functions.php');