Calculate the number of weekdays between two dates in C#

Question

How can I get the number of weekdays between two given dates without just iterating through the dates between and counting the weekdays?

Seems fairly straightforward

Answer 1

        public static int GetWeekDays(DateTime startDay, DateTime endDate, bool countEndDate = true)
        {
            var daysBetween = (int)(endDate - startDay).TotalDays;
            daysBetween = countEndDate ? daysBetween += 1 : daysBetween;
            return Enumerable.Range(0, daysBetween).Count(d => !startDay.AddDays(d).DayOfWeek.In(DayOfWeek.Saturday, DayOfWeek.Sunday));
        }

        public static bool In(this T source, params T[] list)
        {
            if (null == source)
            {
                throw new ArgumentNullException("source");
            }
            return list.Contains(source);
        }