Session time out in PHP

HI, i have code for session time out but i dont know whats the issue its not working someone pls look at this and help me. Here is the code:

  $inactive = 10;

  // check to see if $_SESSION['timeout'] is set

  if(isset($_SESSION[开发者_如何学Go'timeout']) ) {

  $session_life = time() - $_SESSION['timeout'];

  if($session_life > $inactive)

  { 
      session_destroy(); 
      header("Location: logoutpage.php"); }
   }

  $_SESSION['timeout'] = time();

Thanks.

the time() variable returns the current time measured in the number of seconds since the Unix Epoch (January 1 1970 00:00:00 GMT). Your $inactive variable implies you wish to keep sessions open for 10 minutes, but you might find it more convenient to switch this to seconds to stay consistent with using the time() function.

// set inactive to 10 minutes (in seconds)
$inactive = 600;

if (!empty($_SESSION['timeout'])) {

    // set session life to current time minus timeout
    $session_life = time() - $_SESSION['timeout'];

    // check if your session life is greater than 10 minutes
    if ($session_life > $inactive) {
        session_destroy();
        header("Location: logoutpage.php");
        die;
    }

}

$_SESSION['timeout'] = time();