Question

I have a function that get the current weeknumber from the given date

e.g.

GregorianCalendar cal = new GregorianCalendar(GregorianCalendarTypes.Localized);
return cal.GetWeekOfYear(date, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);

gives back weeknumber 40 for DateTime.Now.

So my question is , also my problem, i need to get the dates in the returned week. I’ve tried several thing and none so for worked.

Answer 1

You could use this function to get the first date of a week:

public static DateTime FirstDateOfWeek(int year, int weekOfYear)
{
    DateTime jan1 = new DateTime(year, 1, 1);
    int daysOffset = Convert.ToInt32(System.Globalization.CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek) - Convert.ToInt32(jan1.DayOfWeek);
    DateTime firstWeekDay = jan1.AddDays(daysOffset);
    System.Globalization.CultureInfo curCulture = System.Globalization.CultureInfo.CurrentCulture;
    int firstWeek = curCulture.Calendar.GetWeekOfYear(jan1, curCulture.DateTimeFormat.CalendarWeekRule, curCulture.DateTimeFormat.FirstDayOfWeek);
    if (firstWeek <= 1) {
        weekOfYear -= 1;
    }
    return firstWeekDay.AddDays(weekOfYear * 7);
}

Then you can get all dates in this week in the following way:

var firstDate = FirstDateOfWeek(2012, 40);
var allWeekDays = new List<DateTime>();
allWeekDays.Add(firstDate);
var currentDate = firstDate;
for(int d = 1; d < 7; d++)
{
    currentDate=currentDate.AddDays(1);
    allWeekDays.Add(currentDate);
}

or in one line:

var week = Enumerable.Range(0,7).Select(d => firstDate.AddDays(d)).ToList();