$session set-bug?

It's working for me. Are you forgot to add this line?

PHP Code:

$session->start(); 


Thanks, I forget!!! it works well now. 
I am using the file to save session data, Can I save it to cookie via encrypt？

Now, the session was saved as file in my hosting. how long will the session be cleaned? 
frankly I don't like to save the data in webhosing. because the reading speed is slow than from cookie.

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