C#에서 Datetime의 사용법은 현재 시간의 다양한 형식을 가져옵니다.

        ： DateTime dt = DateTime.Now;

Environment.TickCount    “       ”    

DateTime now = DateTime.Now;
Console.WriteLine(now.ToString("yyyy-MM-dd"));  // yyyy-MM-dd    s

Console.WriteLine(dt.ToString());    //  26/11/2009 AM 11:21:30

Console.WriteLine(dt.ToFileTime().ToString());   //   129036792908014024

// Converts the value of the current System.DateTime object to a Windows file time

Console.WriteLine(dt.ToFileTimeUtc().ToString());  //     129036792908014024

// Converts the value of the current System.DateTime object to a Windows file time

Console.WriteLine(dt.ToLocalTime().ToString());   //       26/11/2009 AM 11:21:30

// Converts the value of the current System.DateTime object to local time.

Console.WriteLine(dt.ToLongDateString().ToString());   //      2009 11 26 

Console.WriteLine(dt.ToLongTimeString().ToString());  //      AM 11:21:30

Console.WriteLine(dt.ToOADate().ToString());   //      40143.4732731597

Console.WriteLine(dt.ToShortDateString().ToString());   //     26/11/2009

Console.WriteLine(dt.ToShortTimeString().ToString());   //     AM 11:21

Console.WriteLine(dt.ToUniversalTime().ToString());   //       26/11/2009 AM 3:21:30

Console.WriteLine(dt.Year.ToString());   //        2009

Console.WriteLine(dt.Date.ToString());   //        26/11/2009 AM 12:00:00

Console.WriteLine(dt.DayOfWeek.ToString());  //       Thursday

Console.WriteLine(dt.DayOfYear.ToString());   //       330

Console.WriteLine(dt.Hour.ToString());       //        11

Console.WriteLine(dt.Millisecond.ToString());   //     801        （  ）

Console.WriteLine(dt.Minute.ToString());   //      21

Console.WriteLine(dt.Month.ToString());   //       11

Console.WriteLine(dt.Second.ToString());   //      30

Console.WriteLine(dt.Ticks.ToString());   //       633948312908014024


Console.WriteLine(dt.TimeOfDay.ToString());   //       12:29:51.5181524

// Gets the time of day for this instance.

//    A System.TimeSpan that represents the fraction of the day that has elapsed since midnight.

Console.WriteLine(dt.ToString());     //     26/11/2009 PM 12:29:51

Console.WriteLine(dt.AddYears(1).ToString());    //         26/11/2010 PM 12:29:51

Console.WriteLine(dt.AddDays(1.1).ToString());    //        27/11/2009 PM 2:53:51

Console.WriteLine(dt.AddHours(1.1).ToString());    //       26/11/2009 PM 1:35:51

Console.WriteLine(dt.AddMilliseconds(1.1).ToString());    //26/11/2009 PM 12:29:51

Console.WriteLine(dt.AddMonths(1).ToString());    //        26/12/2009 PM 12:29:51

Console.WriteLine(dt.AddSeconds(1.1).ToString());    //     26/11/2009 PM 12:29:52

Console.WriteLine(dt.AddMinutes(1.1).ToString());    //     26/11/2009 PM 12:30:57

Console.WriteLine(dt.AddTicks(1000).ToString());    //      26/11/2009 PM 12:29:51

Console.WriteLine(dt.CompareTo(dt).ToString());    //       0

Console.WriteLine(dt.Add(new TimeSpan(1,0,0,0)).ToString());    //        

（ ：

System.TimeSpan      ，      

public TimeSpan(long ticks); // ticks: A time period expressed in 100-nanosecond units.

                           //nanosecond：         new TimeSpan(10,000,000)           

public TimeSpan(int hours, int minutes, int seconds);

public TimeSpan(int days, int hours, int minutes, int seconds);

public TimeSpan(int days, int hours, int minutes, int seconds, int milliseconds);

）

Console.WriteLine(dt.Equals("2005-11-6 16:11:04").ToString());     //        False

Console.WriteLine(dt.Equals(dt).ToString());    //      True

Console.WriteLine(dt.GetHashCode().ToString());    //       1103291775

Console.WriteLine(dt.GetType().ToString());    //       System.DateTime

Console.WriteLine(dt.GetTypeCode().ToString());    //       DateTime
  

long Start = Environment.TickCount;   //     

long End = Environment.TickCount;

Console.WriteLine("Start is : "+Start);

Console.WriteLine("End is : "+End);

Console.WriteLine("The Time is {0}",End-Start);
Console.WriteLine(dt.GetDateTimeFormats('s')[0].ToString());    //2009-11-26T13:29:06

Console.WriteLine(dt.GetDateTimeFormats('t')[0].ToString());    //PM 1:29

Console.WriteLine(dt.GetDateTimeFormats('y')[0].ToString());    //2009 11 

Console.WriteLine(dt.GetDateTimeFormats('D')[0].ToString());    //2009 11 26 

Console.WriteLine(dt.GetDateTimeFormats('D')[1].ToString());    //   , 26    , 2009

Console.WriteLine(dt.GetDateTimeFormats('D')[2].ToString());    //26    , 2009

Console.WriteLine(dt.GetDateTimeFormats('D')[3].ToString());    //    2009 11 26

Console.WriteLine(dt.GetDateTimeFormats('M')[0].ToString());    //26    

Console.WriteLine(dt.GetDateTimeFormats('f')[0].ToString());    //2009 11 26  PM 1:29

Console.WriteLine(dt.GetDateTimeFormats('g')[0].ToString());    //26/11/2009 PM 1:29

Console.WriteLine(dt.GetDateTimeFormats('r')[0].ToString());    //Thu, 26 Nov 2009 13:29:06 GMT

( ：

         ：

                
d        MM/dd/yyyy 
D        dddd, MMMM dd, yyyy 
f          (long date + short time) dddd, MMMM dd, yyyy HH:mm 
F          (long date + long time) dddd, MMMM dd, yyyy HH:mm:ss 
g      (short date + short time) MM/dd/yyyy HH:mm 
G      (short date + long time) MM/dd/yyyy HH:mm:ss 
m,M      MMMM dd 
s          yyyy-MM-dd HH:mm:ss 
t        HH:mm 
T        HH:mm:ss

)


Console.WriteLine(string.Format("{0:d}", dt));    //28/12/2009

Console.WriteLine(string.Format("{0:D}", dt));    //2009 12 28 

Console.WriteLine(string.Format("{0:f}", dt));    //2009 12 28  AM 10:29

Console.WriteLine(string.Format("{0:F}", dt));    //2009 12 28  AM 10:29:18

Console.WriteLine(string.Format("{0:g}", dt));    //28/12/2009 AM 10:29

Console.WriteLine(string.Format("{0:G}", dt));    //28/12/2009 AM 10:29:18

Console.WriteLine(string.Format("{0:M}", dt));    //28    

Console.WriteLine(string.Format("{0:R}", dt));    //Mon, 28 Dec 2009 10:29:18 GMT

Console.WriteLine(string.Format("{0:s}", dt));    //2009-12-28T10:29:18

Console.WriteLine(string.Format("{0:t}", dt));    //AM 10:29

Console.WriteLine(string.Format("{0:T}", dt));    //AM 10:29:18

Console.WriteLine(string.Format("{0:u}", dt));    //2009-12-28 10:29:18Z

Console.WriteLine(string.Format("{0:U}", dt));    //2009 12 28  AM 2:29:18

Console.WriteLine(string.Format("{0:Y}", dt));    //2009 12 

Console.WriteLine(string.Format("{0}", dt));    //28/12/2009 AM 10:29:18

Console.WriteLine(string.Format("{0:yyyyMMddHHmmssffff}", dt));    //200912281029182047

  2         
DateTime dt1 = Convert.ToDateTime("2007-8-1");    
DateTime dt2 = Convert.ToDateTime("2007-8-15");   
TimeSpan span = dt2.Subtract(dt1);              
int dayDiff = span.Days ;                    

         
int days = DateTime.DaysInMonth(2009, 8);       
days = 31;                                      

       、    
DateTime dt =DateTime.Now;
dt.AddDays(1); //     dt      
dt.AddDays(-1);//     dt