PHP session timeout cookie lifetime

There are many ways to set cookie based session timeout in PHP. You can edit your php.ini or put it in .htaccess but I choose for today this piece of code:

<?php
ini_set('session.gc_maxlifetime', 172800);
ini_set('session.cookie_lifetime', 172800);
session_start();
?>

The session above will be valid for 2 days.