สอบถามเรื่องการ Search Date ด้วย รูปแบบของ Week ครับ

public static DateTime FirstDateOfWeekISO8601(int year, int weekOfYear)
{
    DateTime jan1 = new DateTime(year, 1, 1);
    int daysOffset = DayOfWeek.Thursday - jan1.DayOfWeek;

    DateTime firstThursday = jan1.AddDays(daysOffset);
    var cal = CultureInfo.CurrentCulture.Calendar;
    int firstWeek = cal.GetWeekOfYear(firstThursday, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);

    var weekNum = weekOfYear;
    if (firstWeek <= 1)
    {
        weekNum -= 1;
    }
    var result = firstThursday.AddDays(weekNum * 7);
    return result.AddDays(-3);
}

public static System.DateTime getDateOfWeek(int intYear, int intWeek, string F_OR_L = "F")
{
	System.DateTime _1stPeriod = new System.DateTime(intYear, 1, 1);
	int dow = Convert.ToInt32(_1stPeriod.DayOfWeek);
	return F_OR_L == "F" ? _1stPeriod.AddDays(((intWeek - 1) * 7) - dow) : (_1stPeriod.AddDays(((intWeek - 1) * 7) - dow)).AddDays(6);
}

    Public Shared Function getDateOfWeek(ByVal intYear As Integer, ByVal intWeek As Integer, Optional ByVal F_OR_L As String = "F") As Date
        Dim _1stPeriod As New Date(intYear, 1, 1)
        Dim dow As Integer = CInt(_1stPeriod.DayOfWeek)
        Return If(F_OR_L = "F", _1stPeriod.AddDays(((intWeek - 1) * 7) - dow), (_1stPeriod.AddDays(((intWeek - 1) * 7) - dow)).AddDays(6))
    End Function