最近有一个项目要用到年份周期，用于数据统计图表展示使用，当中用到年份周期,以及年份周期所在的日期范围。当初设想通过已知数据来换算年份周期，经过搜索资料发现通过数据库SQL语句来做，反而更加复杂。现在改变思路通过C#后台代码来算出两段日期范围中年份周期，在依据年份周期所对应的日期范围进行数据库查询进行统计。需要解决以下两个点问题，
第一点：依据日期查找所在年份的第几周；
第二点：依据年份所在的周期计算出周期所在的日期范围。
using System; using System.Collections.Generic; using System.Globalization; using System.Linq; using System.Text; using System.Threading.Tasks; namespace ConsoleApplication6 { class Program { static void Main(string[] args) { GregorianCalendar gc = new GregorianCalendar(); int weekOfYear = gc.GetWeekOfYear(DateTime.Now, CalendarWeekRule.FirstDay, DayOfWeek.Monday); Console.WriteLine("当前第{0}周", weekOfYear); DateTime startDate, lastDate; for (int i = 1; i <= 53; i++) { GetDaysOfWeeks(DateTime.Now.Year, i, out startDate, out lastDate); Console.WriteLine("第{0}周", i); Console.WriteLine(startDate); Console.WriteLine(lastDate); } Console.ReadLine(); } public static bool GetDaysOfWeeks(int year, int index, out DateTime first, out DateTime last) { first = DateTime.MinValue; last = DateTime.MinValue; if (year < 1700 || year > 9999) { //"年份超限" return false; } if (index < 1 || index > 53) { //"周数错误" return false; } DateTime startDay = new DateTime(year, 1, 1); //该年第一天 DateTime endDay = new DateTime(year + 1, 1, 1).AddMilliseconds(-1); int dayOfWeek = 0; if (Convert.ToInt32(startDay.DayOfWeek.ToString("d")) > 0) dayOfWeek = Convert.ToInt32(startDay.DayOfWeek.ToString("d")); //该年第一天为星期几 if (dayOfWeek == 0) { dayOfWeek = 7; } if (index == 1) { first = startDay.AddDays(7 - dayOfWeek - 6); if (dayOfWeek == 6) { last = first; } else { last = startDay.AddDays((7 - dayOfWeek)); } } else { first = startDay.AddDays((8 - dayOfWeek) + (index - 2) * 7); //index周的起始日期 last = first.AddDays(6); //if (last > endDay) //{ // last = endDay; //} } if (first > endDay) //startDayOfWeeks不在该年范围内 { //"输入周数大于本年最大周数"; return false; } return true; } } }