Calendar og week

Fandt selv ud af det, visual studio kan ikke så jeg fandt noget kode som kunne gøre arbejdet.

private void Kalender_ValueChanged(object sender, EventArgs e)
        {
            // Calculates the ISO 8601 Week Number
            // In this scenario the first day of the week is monday,
            // and the week rule states that:
            // [...] the first calendar week of a year is the one
            // that includes the first Thursday of that year and
            // [...] the last calendar week of a calendar year is
            // the week immediately preceding the first
            // calendar week of the next year.
            // The first week of the year may thus start in the
            // preceding year

            const int JAN = 1;
            const int DEC = 12;
            const int LASTDAYOFDEC = 31;
            const int FIRSTDAYOFJAN = 1;
            const int THURSDAY = 4;
            bool ThursdayFlag = false;

            // Get the day number since the beginning of the year
            int DayOfYear = Kalender.Value.DayOfYear;

            // Get the numeric weekday of the first day of the
            // year (using sunday as FirstDay)
            int StartWeekDayOfYear =
                (int)(new DateTime(Kalender.Value.Year, JAN, FIRSTDAYOFJAN)).DayOfWeek;
            int EndWeekDayOfYear =
                (int)(new DateTime(Kalender.Value.Year, DEC, LASTDAYOFDEC)).DayOfWeek;

            // Compensate for the fact that we are using monday
            // as the first day of the week
            if (StartWeekDayOfYear == 0)
                StartWeekDayOfYear = 7;
            if (EndWeekDayOfYear == 0)
                EndWeekDayOfYear = 7;

            // Calculate the number of days in the first and last week
            int DaysInFirstWeek = 8 - (StartWeekDayOfYear);
            int DaysInLastWeek = 8 - (EndWeekDayOfYear);

            // If the year either starts or ends on a thursday it will have a 53rd week
            if (StartWeekDayOfYear == THURSDAY || EndWeekDayOfYear == THURSDAY)
                ThursdayFlag = true;

            // We begin by calculating the number of FULL weeks between the start of the year and
            // our date. The number is rounded up, so the smallest possible value is 0.
            int FullWeeks = (int)Math.Ceiling((DayOfYear - (DaysInFirstWeek)) / 7.0);

            WeekNumber = FullWeeks;

            // If the first week of the year has at least four days, then the actual week number for our date
            // can be incremented by one.
            if (DaysInFirstWeek >= THURSDAY)
                WeekNumber = WeekNumber + 1;

            // If week number is larger than week 52 (and the year doesn't either start or end on a thursday)
            // then the correct week number is 1.
            if (WeekNumber > 52 && !ThursdayFlag)
                WeekNumber = 1;

        }

Så jeg ligger selv et svarog tager mine point igen

Her er lige en metode der er 100 gange nemmere:

System.Globalization.CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(DateTime.Now, Globalization.CalendarWeekRule.FirstDay, DayOfWeek.Monday);

En lille rettelse, følgende er den korrekte måde at udregne det danske uge format:

System.Globalization.CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(DateTime.Now, System.Globalization.CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday)

tager den funktion datoen fra en calendar fra toolboxen og når man så trykker på en hvilken som helst dato i kalenderen, retunere den så den uge som den dag man har valgt indgår i?