有关日期、时间、星期

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace gettime
{
    class Program
    {
        static void Main(string[] args)
        {
          
           string str = "2011/11/12 ";
           int dt =Int32.Parse (DateTime.Parse(str).DayOfYear.ToString());//所表示的日期是该年中的第几天；
           string week = DateTime.Parse(str).DayOfWeek.ToString("D");//所表示的日期是星期几（用数字表示）；
           string ss = string.Empty;
           switch (week)
           {
               case "0":
                   ss = "星期日";
                   break;
               case "1":
                   ss = "星期一";
                   break;
               case "2":
                   ss = "星期二";
                   break;
               case "3":
                   ss = "星期三";
                   break;
               case "4":
                   ss = "星期四";
                   break;
               case "5":
                   ss = "星期五";
                   break;
               case "6":
                   ss = "星期六";
                   break;
               default:
                   break;
           }

           Console.WriteLine(ss);
           Console.WriteLine(dt);
           Console.WriteLine(DateTime.DaysInMonth(2001, 2));

            DateTime dt1 = DateTime.Parse("2011-3-12 18:39:00");
            DateTime dt2 = DateTime.Parse("2003-3-12 18:51:00");
            TimeSpan ts = (dt2 - dt1);
            Console.WriteLine(ts.Days);//得到天数

           Console.ReadLine();

        }
    }
}