Determine the difference between two DateTimes, only counting opening hours

Question

For our support software in C#, I need to determine the time span between two DateTimes, but I only want opening hours counted (i.e. weekdays from 09:00 to 17:00).

S

Answer 1

Use LINQ:

DateTime dt1 = new DateTime(2010, 10, 1, 16, 0, 0);
DateTime dt2 = new DateTime(2010, 10, 2, 10, 0, 0);

int hours = Enumerable.Range(1, (dt2 - dt1).Hours)
                 .Where(h =>
                    {
                        var dt = dt1.AddHours(h);
                        return dt.DayOfWeek != DayOfWeek.Saturday
                               && dt.DayOfWeek != DayOfWeek.Sunday
                               && dt.Hour >= 9 && dt.Hour <= 17;
                    }).Count();

Here I assume all Minute and Second are zero. Otherwise (dt2 - dt1).Hours will give unexpected value.