DateTime dt1 = DateTime.Parse("2009-12-30 12:00");
            DateTime dt2 = DateTime.Parse("2010-01-30 13:00");
            Console.WriteLine((new DateTime(dt2.Year, dt2.Month, dt2.Day, 12, 0, 0) - dt1.Date).Days);

太强大了..我刚知道还能这么使