SignOut in PHP website

Question

I am trying to log out from a PHP website by using the following code:

<?php
session_start();
if(isset($_GET['logout']))
{
   $_SESSION=array();
   if($_COOKIE[session_name()])

   {
    setcookie(session_name(), '', time()-42000, '/');
   }
session_destroy();
header('Location: login.php');
}

?>

The page gets redirected to Login page but when I click back button of browser, I am able to see the previous page. Please suggest a comprehensive solution that can resolve this, since on various posts, I am not able to find a solution where User can completely logout the php website. (if possible, without using javascript). I want to be on the login page itself even when back button is pressed after logout.

Answer 1

session_start(); 
session_unset(); 
session_destroy(); 
header ('location:login.php?message=logout');