inDays property
The number of entire days spanned by this Duration.
For example, a duration of four days and three hours has four entire days.
const duration = Duration(days: 4, hours: 3);
print(duration.inDays); // 4
A negative duration has a negative number of whole days,
so that (-duration).inDays = -(duration.inDays).
Implementation
int get inDays => inMicroseconds ~/ Duration.microsecondsPerDay;