Redirect

    /**
     * Redirects user to destination, which can be
     * a URL or a relative path on the local host.
     *
     * Because this function outputs an HTTP header, it
     * must be called before caller outputs any HTML.
     */
    function redirect($destination)
    {
        // handle URL
        if (preg_match("/^https?:\/\//", $destination))
        {
            header("Location: " . $destination);
        }

        // handle absolute path
        else if (preg_match("/^\//", $destination))
        {
            $protocol = (isset($_SERVER["HTTPS"])) ? "https" : "http";
            $host = $_SERVER["HTTP_HOST"];
            header("Location: $protocol://$host$destination");
        }

        // handle relative path
        else
        {
            // adapted from http://www.php.net/header
            $protocol = (isset($_SERVER["HTTPS"])) ? "https" : "http";
            $host = $_SERVER["HTTP_HOST"];
            $path = rtrim(dirname($_SERVER["PHP_SELF"]), "/\\");
            header("Location: $protocol://$host$path/$destination");
        }

        // exit immediately since we're redirecting anyway
        exit;
    }