C#获取每个年,月,周的起始日期和结束日期的方法

/// <summary>/// 声明期间类型枚举/// </summary>public enum Period {Day, Week, Month, Year};/// <summary>/// 获取指定期间的起止日期/// </summary>/// <param name="period">期间类型</param>/// <param name="beginDate">开始日期</param>/// <param name="endDate">结束日期</param>public static void GetPeriod(Period period, out DateTime beginDate, out DateTime endDate){  int year = DateTime.Today.Year;  int month = DateTime.Today.Month;  switch (period)  {    case Period.Year: //年      beginDate = new DateTime(year, 1, 1);      endDate = new DateTime(year, 12, 31);      break;    case Period.Month: //月      beginDate = new DateTime(year, month, 1);      endDate = beginDate.AddMonths(1).AddDays(-1);      break;    case Period.Week: //周      int week = (int)DateTime.Today.DayOfWeek;      if (week == 0) week = 7; //周日      beginDate = DateTime.Today.AddDays(-(week - 1));      endDate = beginDate.AddDays(6);      break;    default: //日      beginDate = DateTime.Today;      endDate = DateTime.Today;      break;  }}