c# GetWorkHours

 public static double[] GetWorkHours(DateTime start, DateTime end, TimeSpan workStartTime, TimeSpan workEndTime)
    {
        IList<double> result = new List<double>();

        if (start > end)
        {
            throw new ArgumentException("Start date is later than end date");
        }

        DateTime currentDate = start.Date;
        while (currentDate <= end.Date)
        {
            if (currentDate.DayOfWeek != DayOfWeek.Saturday && currentDate.DayOfWeek != DayOfWeek.Sunday)
            {
                TimeSpan realStartTime = GetStartTimeForDay(start, end, workStartTime, currentDate);
                TimeSpan realEndTime = GetEndTimeForDay(start, end, workEndTime, currentDate);

                if (realStartTime >= workEndTime || realEndTime <= workStartTime)
                {
                    result.Add(0);
                }
                else
                {
                    result.Add(GetHoursInTimePeriod(realStartTime, realEndTime));
                }
            }

            currentDate = currentDate.AddDays(1);
        }

        return result.ToArray();
    }

    private static TimeSpan GetStartTimeForDay(DateTime start, DateTime end, TimeSpan workStartTime, DateTime day)
    {
        return day == start.Date ? (start.TimeOfDay < workStartTime ? workStartTime : start.TimeOfDay) : workStartTime;
    }

    private static TimeSpan GetEndTimeForDay(DateTime start, DateTime end, TimeSpan workEndTime, DateTime day)
    {
        return day == end.Date ? (end.TimeOfDay < workEndTime ? end.TimeOfDay : workEndTime) : workEndTime;
    }

    private static double GetHoursInTimePeriod(TimeSpan start, TimeSpan end)
    {
        return (end - start).TotalHours;
    }

Source : https://stackoverflow.com/questions/47301975/c-sharp-get-working-hours-within-a-time-span