Calculate DateTime Weeks into Rows

Here is the method that does it:

public int GetWeekRows(int year, int month)
{
    DateTime firstDayOfMonth = new DateTime(year, month, 1);
    DateTime lastDayOfMonth = new DateTime(year, month, 1).AddMonths(1).AddDays(-1);
    System.Globalization.Calendar calendar = System.Threading.Thread.CurrentThread.CurrentCulture.Calendar;
    int lastWeek = calendar.GetWeekOfYear(lastDayOfMonth, System.Globalization.CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
    int firstWeek = calendar.GetWeekOfYear(firstDayOfMonth, System.Globalization.CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
    return lastWeek - firstWeek + 1;
}

You can customize the calendar week rule by modifying the System.Globalization.CalendarWeekRule.FirstFourDayWeek part. I hope the code is self explanatory.

Well, it depends on the culture you're using, but let's assume you can use Thread.CurrentThread.CurrentCulture, then the code to get the week of today would be:

Culture culture = Thread.CurrentThread.CurrentCulture;
Calendar cal = culture.Calendar;
Int32 week = cal.GetWeekOfYear(DateTime.Today,
    culture.DateTimeFormat.CalendarWeekRule,
    culture.DateTimeFormat.FirstDayOfWeek);