获取当前时间是周几

        /// <summary>
        /// 获取当前时间是周几
        /// </summary>
        /// <returns></returns>
        public string GetWeek(DateTime? dt = null)
        {
            if (!dt.HasValue)
                dt = DateTime.Now;

            var weeks = new[] { "周日", "周一", "周二", "周三", "周四", "周五", "周六" };
            return weeks[Convert.ToInt32(dt.Value.DayOfWeek)];
        }