say 'Please enter a time when you want to make a reservation for tomorrow (HHMM).'

do until res=""
	parse pull res
	call checknum
	call checktime
	say "Thank you. You've made a reservation for tomorrow at:" hours || ":" || min"." /* feedback if succsessful reservation */
	call lineout "reservations.txt", "Reservation made:" date() "For next day at" hours || ":" || min"." /* saves time to reservation.txt */
end

checknum: select
	when length(res) = 4 & datatype(res) = num then return /* checks if input is 4 digits long and if input is a number*/
	otherwise say "That is an invalid input."; exit		/* if invalid input, exit programm */
	end
	
checktime:
	parse var res 1 hours 3 min /* slices input into hours and minutes */
	select
		when hours < 0 | hours > 24 then say "That is an invalid input." /* if hours is impossible time then exit */
		when min < 0 | min > 59 then say "That is an invalid input."	/* if min is impossible time then exit */
		when hours < 8 | hours > 22 then say "The restaurant is closed at that time." /* if input is outside of opening hours then exit */
		otherwise return
	end