HI,
you can use like the following:
DateTime a = new DateTime(2008, 01, 02, 06, 30, 00);
DateTime b = new DateTime(2008, 01, 03, 06, 30, 00);
TimeSpan duration = b - a;
double hours = (b-a).TotalHours;
OR
int days = (int)Math.Ceiling(diff.TotalDays);
Thanks