Calculate the number of business days between two dates?

Question

In C#, how can I calculate the number of business (or weekdays) days between two dates?

Answer 1

Here's some code for that purpose, with swedish holidays but you can adapt what holidays to count. Note that I added a limit you might want to remove, but it was for a web-based system and I didnt want anyone to enter some huge date to hog the process

  public static int GetWorkdays(DateTime from ,DateTime to)
    {
        int limit = 9999;
        int counter = 0;
        DateTime current = from;
        int result = 0;

        if (from > to)
        {
            DateTime temp = from;
            from = to;
            to = temp;
        }

        if (from >= to)
        {
            return 0;
        }


        while (current <= to && counter < limit)
        {
            if (IsSwedishWorkday(current))
            {
                result++;
            }
            current = current.AddDays(1);
            counter++;

        }
        return result;
    }


    public static bool IsSwedishWorkday(DateTime date)
    {
        return (!IsSwedishHoliday(date) && date.DayOfWeek != DayOfWeek.Saturday && date.DayOfWeek != DayOfWeek.Sunday);
    }

    public static bool IsSwedishHoliday(DateTime date)
    {
        return (
        IsSameDay(GetEpiphanyDay(date.Year), date) ||
        IsSameDay(GetMayDay(date.Year), date) ||
        IsSameDay(GetSwedishNationalDay(date.Year), date) ||
        IsSameDay(GetChristmasDay(date.Year), date) ||
        IsSameDay(GetBoxingDay(date.Year), date) ||
        IsSameDay(GetGoodFriday(date.Year), date) ||
        IsSameDay(GetAscensionDay(date.Year), date) ||
        IsSameDay(GetAllSaintsDay(date.Year), date) ||
        IsSameDay(GetMidsummersDay(date.Year), date) ||
        IsSameDay(GetPentecostDay(date.Year), date) ||
        IsSameDay(GetEasterMonday(date.Year), date) ||
        IsSameDay(GetNewYearsDay(date.Year), date) ||
        IsSameDay(GetEasterDay(date.Year), date)
        );
    }

    // Trettondagen
    public static DateTime GetEpiphanyDay(int year)
    {
        return new DateTime(year, 1, 6);
    }

    // Första maj
    public static DateTime GetMayDay(int year)
    {
        return new DateTime(year,5,1);
    }

    // Juldagen
    public static DateTime GetSwedishNationalDay(int year)
    {
        return new DateTime(year, 6, 6);
    }


    // Juldagen
    public static DateTime GetNewYearsDay(int year)
    {
        return new DateTime(year,1,1);
    }

    // Juldagen
    public static DateTime GetChristmasDay(int year)
    {
        return new DateTime(year,12,25);
    }

    // Annandag jul
    public static DateTime GetBoxingDay(int year)
    {
        return new DateTime(year, 12, 26);
    }


    // Långfredagen
    public static DateTime GetGoodFriday(int year)
    {
        return GetEasterDay(year).AddDays(-3);
    }

    // Kristi himmelsfärdsdag
    public static DateTime GetAscensionDay(int year)
    {
        return GetEasterDay(year).AddDays(5*7+4);
    }

    // Midsommar
    public static DateTime GetAllSaintsDay(int year)
    {
        DateTime result = new DateTime(year,10,31);
        while (result.DayOfWeek != DayOfWeek.Saturday)
        {
            result = result.AddDays(1);
        }
        return result;
    }

    // Midsommar
    public static DateTime GetMidsummersDay(int year)
    {
        DateTime result = new DateTime(year, 6, 20);
        while (result.DayOfWeek != DayOfWeek.Saturday)
        {
            result = result.AddDays(1);
        }
        return result;
    }

    // Pingstdagen
    public static DateTime GetPentecostDay(int year)
    {
        return GetEasterDay(year).AddDays(7 * 7);
    }

    // Annandag påsk
    public static DateTime GetEasterMonday(int year)
    {
        return GetEasterDay(year).AddDays(1);
    }
    public static DateTime GetEasterDay(int y)
    {
        double c;
        double n;
        double k;
        double i;
        double j;
        double l;
        double m;
        double d;
        c = System.Math.Floor(y / 100.0);
        n = y - 19 * System.Math.Floor(y / 19.0);
        k = System.Math.Floor((c - 17) / 25.0);
        i = c - System.Math.Floor(c / 4) - System.Math.Floor((c - k) / 3) + 19 * n + 15;
        i = i - 30 * System.Math.Floor(i / 30);
        i = i - System.Math.Floor(i / 28) * (1 - System.Math.Floor(i / 28) * System.Math.Floor(29 / (i + 1)) * System.Math.Floor((21 - n) / 11));
        j = y + System.Math.Floor(y / 4.0) + i + 2 - c + System.Math.Floor(c / 4);
        j = j - 7 * System.Math.Floor(j / 7);
        l = i - j;
        m = 3 + System.Math.Floor((l + 40) / 44);// month
        d = l + 28 - 31 * System.Math.Floor(m / 4);// day

        double days = ((m == 3) ? d : d + 31);

        DateTime result = new DateTime(y, 3, 1).AddDays(days-1);

        return result;
    }