#region 得到一个月的第一天和最后一天的日期 /// <summary> /// 得到本月的第一天日期 /// </summary> /// <returns>DateTime</returns> public static DateTime GetFirstDayOfMonth() { return GetFirstDayOfMonth(DateTime.Now); } /// <summary> /// 得到本月的最有一天的日期 /// </summary> /// <returns>DateTime</returns> public static DateTime GetLastDayOfMonth() { return GetLastDayOfMonth(DateTime.Now); } /// <summary> /// 得到一个月的第一天 /// </summary> /// <param name="someday">这个月的随便一天</param> /// <returns>DateTime</returns> public static DateTime GetFirstDayOfMonth(DateTime someday) { int totalDays = DateTime.DaysInMonth(someday.Year, someday.Month); DateTime result; int ts = 1 - someday.Day; result = someday.AddDays(ts); return result; } /// <summary> /// 得到一个月的最后一天 /// </summary> /// <param name="someday">这个月的随便一天</param> /// <returns>DateTime</returns> public static DateTime GetLastDayOfMonth(DateTime someday) { int totalDays = DateTime.DaysInMonth(someday.Year, someday.Month); DateTime result; int ts = totalDays - someday.Day; result = someday.AddDays(ts); return result; } #endregion