CodeIgniter : How to check if a session exist in PHP?

Problem :

How to check if a CodeIgniter or PHP session exist or not?

Solution :

From the official PHP documentation :

session_id() returns the session id for the current session or the empty string ("") if there is no current session (no current session id exists).

 $sid = session_id();
 if ($sid != '') {
 echo "Session exists!";
 } else {
 echo "No current session exists! Starting...";
 session_start();
 }