PHP header（）＆exit（）会在重定向之前安全地终止脚本吗？

Question

Is the following a secure way of protecting a user only area?

if(!isset($_SESSION['username'])){redirect(SITE_ROOT . 'st_pages/login/');}

using:

function redirect($url)
    {
        header('Location: ' . $url);
        exit('<a href="' . $url . '">Redirecting you to: ' . $url . '</a>');
    }

Answer 1

yes it is secure

though header() do not terminate anything, but exit() indeed terminate a script. that's the only purpose of this function