Count even days and not even days in a date range

its the number of days / 2 and then work out if the start day is 'even' or odd'

If the dates are 15th to 25th (inclusive) then this is 11 days

Those 11 days are;

• 5 odd and 6 even, or
• 5 even and 6 odd.

The key to this is if the first day of the week is even or odd

Some if constructs and look at carbon examples:

https://carbon.nesbot.com/docs/

Personally, I would set it up so that every day of the week has a different rate, and then seed it with your odd and even rates.

If you cope with every day of the week with a different price then when they come to you and say that saturday and sunday now have their own rates then its an easy fix.

if I use /2 on day and for example the booking id for friday to friday the math is not corect

$start = Carbon::create(2020, 1, 1);

$end = Carbon::create(2020, 12, 31);

$oddDays = $start->diffInDaysFiltered(function ($date) {
   return $date->isMonday() || 
     $date->isWednesday() || 
     $date->isFriday() || 
     $date->isSunday();
}, $end);

$evenDays = $start->diffInDaysFiltered(function ($date) {
   return $date->isTuesday() || 
     $date->isThursday() || 
     $date->isSaturday();
}, $end);

Or easier

$start = Carbon::create(2020, 1, 1);

$end = Carbon::create(2020, 12, 31);

$oddDays = $start->diffInDaysFiltered(function ($date) {
   return in_array($date->dayOfWeek, [1, 3, 5, 0]);
}, $end);

$evenDays = $start->diffInDaysFiltered(function ($date) {
   return in_array($date->dayOfWeek, [2, 4, 6]);
}, $end);

Was hoping carbon docs would be used as isMonday, etc is right in the docs. That way @kalimeromk would learn carbon usage. But great answer.

@kalimeromk then you did not read my answer fully

Friday to Friday is 8 days, 4 even and 4 odd.