Including external file

[alessai2]

I want to know how to include external file.
i have already read the plugin system manual about including external file.
but it says '/path/to/file'
and my file is located at vbulletin's root directory .
name of file is random.php

What i want to know is the variable which contain the forum's url i.e /forum/
so that i can use this code :

PHP Code:

ob_start();
  include("".$vboptions['forumhome']."/random.php");
  $includedphp = ob_get_contents();
  ob_end_clean(); 


but the variable ".$vboptions['forumurl']." isnt working, it gives this error :

Warning: include(/random.php) [function.include]: failed to open stream: No such file or directory in \global.php(360) : eval()'d code on line 4

Warning: include() [function.include]: Failed opening '/random.php' for inclusion (include_path='.;D:\Softwares\Setups\xampp\php\pear\') in \global.php(360) : eval()'d code on line 4

Please help !!!