Trouble in destroying session - php

Question

I am having trouble in destroying session when user logout of its account. After logging out when i browse any page which is restricted to user not to access before login i can access that but if i close my browser after logging out and then try to access the page i cant. Please solve my problem so that user cannot access the pages after logging out even he/she has not closed the browser. Here's my code of logging out and destroying session.
<?php
// Initialize the session.
// If you are using session_name("something"), don't forget it now!
if(isset($_POST['logout'])){
session_start();
// Unset all of the session variables.
$_SESSION = array();
$_SESSION["Alogin"] = "";
// 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 (ini_get("session.use_cookies")) {
$params = session_get_cookie_params();
setcookie(session_name(), '', time() - 42000,
$params["path"], $params["domain"],
$params["secure"], $params["httponly"]
);
}
// Finally, destroy the session.
session_destroy();
}
?>

Answer 1

Session session_start() must be at the top
<?php
// Initialize the session.
session_start();
// If you are using session_name("something"), don't forget it now!
if(isset($_POST['logout'])){
//What ever you want
// Finally, destroy the session.
unset( $_SESSION );
session_destroy();
//redirect to loginpage
header('Location:../login.php');
exit;
}
?>

Answer 2

Put your session_start (); outside the if statement and
check with print_r ($_POST); if you send $_POST['logout']