public static string[] DaysInWeek(DateTime dateTime, DayOfWeek firstDayOfWeek = DayOfWeek.Sunday)
{
int difference = dateTime.DayOfWeek - firstDayOfWeek;
if (difference < 0)
{
difference += 7;
}
var tmp = dateTime.AddDays(-difference);
return new[]
{
string.Format("{0:yyyyMMdd}", tmp),
string.Format("{0:yyyyMMdd}", tmp.AddDays(1)),
string.Format("{0:yyyyMMdd}", tmp.AddDays(2)),
string.Format("{0:yyyyMMdd}", tmp.AddDays(3)),
string.Format("{0:yyyyMMdd}", tmp.AddDays(4)),
string.Format("{0:yyyyMMdd}", tmp.AddDays(5)),
string.Format("{0:yyyyMMdd}", tmp.AddDays(6))
};
}