从日期范围确定Midnights的数量

I have a reservation system, which charges a daily rate for overnights. I'm trying to figure out how to calculate the number of times midnight has been crossed for a given date range in PHP.

I have 2 unix timestamps:

$start_date        = 1404349200; // 07/02/14 07:00:00 pm
$end_date          = 1404936000; // 07/09/14 02:00:00 pm
$total_time_here   = $end_date - $start_date; // number of seconds here
$number_overnights = (int) ($total_time_here / 60 / 60 / 24); // calculate number of 24-hour periods

$number_overnights evaluates to 6, however the number of times midnight occurred for that date range is 7, which is what I want to count. This happens when the $start_date happens later in the day than the $end_date (7:00pm vs 2:00pm).

Both the $start_date and $end_date are in the same time zone, and are stored in UTC in the database and then converted back in PHP.

Thanks for your help!

I think this might work:

$start_date = strtotime(date('Y-m-d 00:00:00', 1404349200));
$end_date = strtotime(date('Y-m-d 23:59:59', 1404936000));
$total_time_here   = $end_date - $start_date;
$number_overnights = (int) ($total_time_here / 60 / 60 / 24);