The below code is for getting number of sunday for a current month
//First We find out last date of mont
DateTime today = DateTime.Today;
DateTime endOfMonth = new DateTime(today.Year, today.Month, DateTime.DaysInMonth(today.Year, today.Month));
//get only last day of month
int day = endOfMonth.Day;
DateTime now = DateTime.Now;
int count;
count = 0;
for (int i = 0; i < day; ++i)
{
DateTime d = new DateTime(now.Year, now.Month, i + 1);
//Compare date with sunday
if (d.DayOfWeek == DayOfWeek.Sunday)
{
count = count + 1;
}
}