Destroying Sessions and Unsetting Variables

You can use session_destroy() to end a session, erasing all session variables. The session_destroy() function requires no arguments. You should have an established session for this function to work as expected. The following code fragment resumes a session and abruptly destroys it:

session_start();
session_destroy();

When you move on to other pages that work with a session, the session you have destroyed will not be available to them, forcing them to initiate new sessions of their own. Any registered variables will be lost.

The session_destroy() function does not instantly destroy registered variables, however. They remain accessible to the script in which session_destroy() is called (until it is reloaded). The following code fragment resumes or initiates a session and registers a variable called test, which we set to 5. Destroying the session does not destroy the registered variable.

session_start();
$_SESSION[test] = 5;
session_destroy();
print $_SESSION[test]; // prints 5

To remove all registered variables from a session, you simply unset the variable:

session_start();
$_SESSION[test] = 5;
session_destroy();
unset($_SESSION[test]);
print $_SESSION[test]; // prints nothing.