PHP Session_ Destroy or unset or Clear

Hi I am trying to clear a login session but whats the correct way to do this?

function logout(){

                    session_start();
                    $_SESSION = array();

                    if (ini_get("session.use_cookies")) {
                    $params = session_get_cookie_params();
     开发者_开发知识库               setcookie(session_name(), '', time() - 42000,
                    $params["path"], $params["domain"],
                    $params["secure"], $params["httponly"]);
                    }
                        session_destroy();
                        header ("Location: index.php");
    }

You could simply open the manual page for session_destroy and find all the necessary information, quote:

session_destroy() destroys all of the data associated with the current session. It does not unset any of the global variables associated with the session, or unset the session cookie.

In order to kill the session altogether, like to log the user out, the session id must also be unset. If a cookie is used to propagate the session id (default behavior), then the session cookie must be deleted. setcookie() may be used for that.

Example 2209. Destroying a session with $_SESSION

// Initialize the session.
// If you are using session_name("something"), don't forget it now!
session_start();

// Unset all of the session variables.
$_SESSION = array();

// If it's desired to kill the session, also delete the session cookie.
// Note: This will destroy the session, and not just the session data!
if (isset($_COOKIE[session_name()])) {
    setcookie(session_name(), '', time()-42000, '/');
}

// Finally, destroy the session.
session_destroy();