日付が指定された範囲内にあるかどうかを確認するにはどうすればよいですか?

$start_date = '2009-06-17';
$end_date = '2009-09-05';
$date_from_user = '2009-08-28';

check_in_range($start_date, $end_date, $date_from_user);

function check_in_range($start_date, $end_date, $date_from_user)
{
  // Convert to timestamps
  $start_ts = strtotime($start_date);
  $end_ts = strtotime($end_date);
  $user_ts = strtotime($date_from_user);

  // Check if user date falls between start and end
  return (($user_ts >= $start_ts) && ($user_ts <= $end_ts));
}