Beginner: How to use session in PHP development?

How do I use session?

The following are the referenced contents: <?php Must be added before use; Session_Start (); ?> <?php Consider that we have time to consider whether to write session if (Isset ($_post[' userid ')) { If you really agree to write: $_session[' userid ' = $ccdot }else{ Or return cannot be written to session } ?>

To clear the time:

The following are the referenced contents: Session_Start (); unset ($_session[' userid ')); Or:session_register (' username ');

The primary function of the Session_unregister () function is to note that the current session variable is deleted. But be aware that if you use $http_session_vars or $_session on the current page