Day of the year this DateTime is on.
assert(DateTime(Date(1999, 1, 1), TimeOfDay(12, 22, 7)).dayOfYear == 1); assert(DateTime(Date(1999, 12, 31), TimeOfDay(7, 2, 59)).dayOfYear == 365); assert(DateTime(Date(2000, 12, 31), TimeOfDay(21, 20, 0)).dayOfYear == 366);
See Implementation
Day of the year this DateTime is on.