How can I get the value at index in codeigniter?

I have generated the array containing session data as,

Array ( [session_id] => 8f9286115a38df9ed54a65b135d4e8c0 [ip_address] => ::1 [user_agent] => Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.101 Safari/537.36 [last_activity] => 1427600580 [user_data] => [roll_no] => 111416 [is_logged_in] => 1 [email] => [user_data ] => Array ( [email] => ) [0] => stdClass Object ( [name] => durex [email] => durex@gmail.com [year] => 2 [semester] => 4 [branch] => CSE [parent_email] => parent@durex.com ) )

How can I echo name(durex) using the above session $userdata?