检查服务器上是否存在带有值的php变量

Question

My site requires users to log in after which the user's id is stored in a session. The db has a field called 'logged_in' with a value 1 when they log in and is changed to 0 when they log out. Problem is that if the user just closes the browser the value stays as 1.

I know that I can check to see if a session exists on the server but can I check if a session with a specific value exists? I guess the literal code would be

if(!isset($_SESSION['user_id'] == 41)){
   // do stuff because session with value 41 doesn't exist
}

Answer 1

You want to check if the session is set, and if it is, check if it matches the value:

<?php

if(!isset($_SESSION['user_id']) 
   || (isset($_SESSION['user_id']) && $_SESSION['user_id'] != 41)) {
   //session is not set, or value differs from 41
}

?>