public static int GetWeekOfDay(DateTime start, DateTime end)        {            //总周数            var weekCount = Math.Ceiling(Convert.ToDouble((end - start).Days / 7));            //用于存储日期            var weekDic = new Dictionary
     
      ();            var today = Convert.ToDateTime(DateTime.Now.ToString("yyyy-MM-dd"));            for (var i = 0; i < weekCount; i++)            {                for (var j = 0; j < 7; j++)                {                    weekDic.Add(start.AddDays(i * 7 + j), i + 1);                }            }            return weekDic.ContainsKey(today) ? weekDic[today] : 1;        }
     

 调用： var result = DateHelper.GetWeekOfDay(new DateTime(2016, 04, 04), new DateTime(2016, 04, 25));

输出：3