$username = $_POST['username'];    $password = $_POST['pwd'];    $file = file_get_contents("userdb.html");    if(!strpos($file, $username)) {        echo "Your username was not found in our database. Please go back and try again.";    } else {        echo "Redirecting...";        if (md5($password) == !strpos($file, md5($password))) {             echo "Redirecting...";             header ('Location: ./userhome.php');        } else {             print "Whoops! Your password seems to be incorrect. Go back and try again.";        }    }