会话开始但重定向后它不存在？

Question

I made a question today about sessions, so finaly i resolved my problem with it. But now after i start my session and:

header('Location: main.php');

it redirects mi to this main.php file but whe i ask in this very file:

if (!isset($_SESSION['uname'])) {

     echo '<script type="text/javascript">alert("not set");</script>';
}

i get answer not set.Why ? i have set my session. why after redirect when i ask about the existence of this session it says it doesnt exist ?

Answer 1

in every file where you are using session you need to start session.

session_start();

it seems that you have missed that in main.php.

Add this line at the top of every php page where you are using session.