C#获得当周起始日期

    /// <summary>
        /// 获得当周起始日期 贾世义
        /// </summary>
        /// <param name="startDate">提供日期</param>
        /// <param name="weekStart">周开始(0为周日 1周一 2周二 3周三 4周四 5 周五 6 周六)</param>
        /// <returns></returns>
        public static DateTime GetWeekStart(DateTime startDate, int weekStart)
        {
            int day = (int)startDate.DayOfWeek;
            if (day > weekStart)
            {
                return startDate.AddDays(weekStart - day);
            }
            else if (day < weekStart)
            {
                return startDate.AddDays(weekStart - day - 7);
            }
            else
            {
                return startDate;
            }
        }