如何检查日期是否在给定范围内？

$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));
}