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. 


Sams Teach Yourself PHP, MySQL and Apache in 24 Hours
Sams Teach Yourself PHP, MySQL and Apache in 24 Hours
ISBN: 067232489X
EAN: 2147483647
Year: 2005
Pages: 263

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