Csharp/C Sharp/Development Class/Date Time

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Add 2 month to the date time

<source lang="csharp"> using System; using System.Collections.Generic; using System.Text; class Program { 

   static void Main(string[] args) {
       DateTime dt = new DateTime(2004, 10, 17);
       dt.AddMonths(2);  // Month is now December.
       Console.WriteLine("Daylight savings: {0}", dt.IsDaylightSavingTime());
   }

} 

</source>


Add TimeSpan to DateTime

<source lang="csharp"> using System; using System.Globalization; class MainClass { 

   public static void Main() {
       DateTime dt = new DateTime();
       DateTime dt1 = new DateTime(2001, 12, 31);
       DateTime dt2 = new DateTime(2000, 12, 31, 23, 59, 59);
       TimeSpan year = new TimeSpan(365 * TimeSpan.TicksPerDay);
       for (int i = 0; i < 10; ++i)
           dt += year;
       Console.WriteLine("DT as string: {0}", dt.ToString());
   }

} 

</source>


A simple clock

<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852

  • /

// A simple clock.

using System;

public class SimpleClock { 

 public static void Main() {  
   string t; 
   int seconds; 

   DateTime dt = DateTime.Now; 
   seconds = dt.Second; 

   for(;;) { 
     dt = DateTime.Now; 

     // update time if seconds change 
     if(seconds != dt.Second) { 
       seconds = dt.Second; 

       t = dt.ToString("T"); 

       if(dt.Minute==0 && dt.Second==0)  
         t = t + "\a"; // ring bell at top of hour 

       Console.WriteLine(t); 
     } 
   } 
 }

} 

      </source>


comparisons between DateTime objects

<source lang="csharp"> using System; using System.Globalization; class MainClass { 

   public static void Main() {
       // Create some date/time objects
       DateTime dt = new DateTime();
       DateTime dt1 = new DateTime(2001, 12, 31);
       DateTime dt2 = new DateTime(2000, 12, 31, 23, 59, 59);
       
       if (dt2 < dt1)
           Console.WriteLine("Dt2 < Dt1");
       else
           if (dt2 == dt1)
               Console.WriteLine("Dt2 == Dt1");
           else
               Console.WriteLine("Dt2 > Dt1");
   }

} 

</source>


Constructors of DateTime

<source lang="csharp"> using System; using System.Globalization; class MainClass { 

   public static void Main() {
       DateTime dt = new DateTime();
       DateTime dt1 = new DateTime(2001, 12, 31);
       DateTime dt2 = new DateTime(2000, 12, 31, 23, 59, 59);
       // Print them out as strings   
       Console.WriteLine("DT as string: {0}", dt.ToString());
       Console.WriteLine("DT1 as string: {0}", dt1.ToString());
       Console.WriteLine("DT2 as string: {0}", dt2.ToString());
   }

} 

</source>


Current date and time

<source lang="csharp"> using System; using System.Globalization; class MainClass { 

   public static void Main() {
       
       Console.WriteLine("Current Date and Time: {0}", DateTime.Now.ToString());
       Console.WriteLine("Current Date Only: {0}", DateTime.Today.ToString());
   }

} 

</source>


DateTime and TimeSpan Instances

<source lang="csharp"> using System; class MainClass { 

   public static void DisplayDateTime(string name, DateTime myDateTime) {
       Console.WriteLine(name + " = " + myDateTime);
       Console.WriteLine(name + ".Year = " + myDateTime.Year);
       Console.WriteLine(name + ".Month = " + myDateTime.Month);
       Console.WriteLine(name + ".Day = " + myDateTime.Day);
       Console.WriteLine(name + ".Hour = " + myDateTime.Hour);
       Console.WriteLine(name + ".Minute = " + myDateTime.Minute);
       Console.WriteLine(name + ".Second = " + myDateTime.Second);
       Console.WriteLine(name + ".Millisecond = " + myDateTime.Millisecond);
       Console.WriteLine(name + ".Ticks = " + myDateTime.Ticks);
   }
   public static void Main() {
       int year = 2008;
       int month = 8;
       int day = 25;
       DateTime myDateTime = new DateTime(year, month, day);
       int hour = 23;
       int minute = 30;
       int second = 12;
       int millisecond = 5;
       DateTime myDateTime2 = new DateTime(year, month, day, hour, minute, second, millisecond);
       System.Globalization.JulianCalendar myCalendar = new System.Globalization.JulianCalendar();
       DateTime myDateTime3 = new DateTime(year, month, day, myCalendar);
       DateTime myDateTime4 = new DateTime(0);
       DisplayDateTime("myDateTime", myDateTime);
       DisplayDateTime("myDateTime2", myDateTime2);
       DisplayDateTime("myDateTime3", myDateTime3);
       DisplayDateTime("myDateTime4", myDateTime4);
       TimeSpan myTimeSpan = new TimeSpan(4, 12, 10);
       myDateTime4 += myTimeSpan;
       DisplayDateTime("myDateTime4", myDateTime4);
   }

} 

</source>


DateTime Now and its calculation

<source lang="csharp"> using System; 

   class MainClass
   {
       public static void Main()
       {
           TimeSpan timespan1 = new TimeSpan(2, 12, 0, 0);
           TimeSpan timespan2 = new TimeSpan(4, 12, 0, 0);
           TimeSpan oneWeek = timespan1 + timespan2;
           DateTime now = DateTime.Now;
           DateTime past = now - oneWeek;
           DateTime future = now + oneWeek;
           Console.WriteLine("Now   : {0}", now);
           Console.WriteLine("Past  : {0}", past);
           Console.WriteLine("Future: {0}", future); 
      }
   }
</source>


Displays the words "Hello World!" on the screen, along with the current date and time

<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110

  • /

/* 

 Example1_1.cs: a variation on the classic "Hello World!" program.
 This program displays the words "Hello World!" on the screen,
 along with the current date and time
  • /

public class Example1_1 { 

 public static void Main()
 {
   // display "Hello World!" on the screen
   System.Console.WriteLine("Hello World!");
   // display the current date and time
   System.Console.WriteLine("The current date and time is " +
     System.DateTime.Now);
 }

} 

      </source>


display the Date, Day, DayOfWeek, DayOfYear,Ticks, and TimeOfDayProperties of myDateTime

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       DateTime myDateTime = DateTime.Now;
       Console.WriteLine("myDateTime.Date = " + myDateTime.Date);
       Console.WriteLine("myDateTime.Day = " + myDateTime.Day);
       Console.WriteLine("myDateTime.DayOfWeek = " + myDateTime.DayOfWeek);
       Console.WriteLine("myDateTime.DayOfYear = " + myDateTime.DayOfYear);
       Console.WriteLine("myDateTime.Ticks = " + myDateTime.Ticks);
       Console.WriteLine("myDateTime.TimeOfDay = " + myDateTime.TimeOfDay);
   }

} 

</source>


Do some leap year checks

<source lang="csharp"> using System; using System.Globalization; class MainClass { 

   public static void Main() {
       // 
       int[] years = { 1984, 2000, 1999, 2002 };
       for (int i = 0; i < years.Length; ++i) {
           if (DateTime.IsLeapYear(years[i]))
               Console.WriteLine("Year {0} is a leap year", years[i]);
           else
               Console.WriteLine("Year {0} is NOT a leap year", years[i]);
       }
   }

} 

</source>


Estimates pi by throwing points into a square. Use to compare execution times

<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794

  • /

// // CalcPi.cs -- Estimates pi by throwing points into a square. Use to // compare execution times. // // Compile this program with the following command line: // C:>csc CalcPi.cs // namespace CalcPi { 

   using System;
   public class CalcPi
   {
       static void Main ()
       {
           const int throws = 10000000;
           DateTime now = DateTime.Now;
           Random rand = new Random ((int) now.Millisecond);
           int Inside = 0;
           for (int i = 0; i < throws; ++i)
           {
               double cx = rand.NextDouble();
               double cy = rand.NextDouble();
               double distance = Math.Sqrt ((cx * cx) + (cy * cy));
               if (distance < 1.0)
                   ++Inside;
           }
           double pi = 4 * (double) Inside / (double) throws;
           DateTime End = DateTime.Now;
           TimeSpan Diff = End - now;
           Console.WriteLine ("pi = " + pi);
           Console.WriteLine ("Milliseconds = " + Diff.TotalMilliseconds);
       }
   }

} 


      </source>


Illustrates the use of DateTime and TimeSpan instances

<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110

  • /

/* 

 Example9_3.cs illustrates the use of DateTime and TimeSpan instances
  • /

using System; public class Example9_3 { 

 public static void DisplayDateTime(
   string name, DateTime myDateTime
 )
 {
   Console.WriteLine(name + " = " + myDateTime);
   // display the DateTime"s properties
   Console.WriteLine(name + ".Year = " + myDateTime.Year);
   Console.WriteLine(name + ".Month = " + myDateTime.Month);
   Console.WriteLine(name + ".Day = " + myDateTime.Day);
   Console.WriteLine(name + ".Hour = " + myDateTime.Hour);
   Console.WriteLine(name + ".Minute = " + myDateTime.Minute);
   Console.WriteLine(name + ".Second = " + myDateTime.Second);
   Console.WriteLine(name + ".Millisecond = " +
     myDateTime.Millisecond);
   Console.WriteLine(name + ".Ticks = " +
     myDateTime.Ticks);
 }

 public static void Main()
 {
   // create a DateTime instance, specifying the year,
   // month, and day
   int year = 2002;
   int month = 12;
   int day = 25;
   DateTime myDateTime = new DateTime(year, month, day);
   // create a DateTime instance, specifying the year,
   // month, day, hour, minute, second, and millisecond
   int hour = 23;
   int minute = 30;
   int second = 12;
   int millisecond = 5;
   DateTime myDateTime2 =
     new DateTime(year, month, day, hour, minute, second, millisecond);
   // create a DateTime instance, specifying the year,
   // month, day, and JulianCalendar object
   System.Globalization.JulianCalendar myCalendar =
     new System.Globalization.JulianCalendar();
   DateTime myDateTime3 =
     new DateTime(year, month, day, myCalendar);
   // create a DateTime instance, specifying the number of ticks
   DateTime myDateTime4 = new DateTime(0);
   // display the various DateTime instances
   DisplayDateTime("myDateTime", myDateTime);
   DisplayDateTime("myDateTime2", myDateTime2);
   DisplayDateTime("myDateTime3", myDateTime3);
   DisplayDateTime("myDateTime4", myDateTime4);
   // create a TimeSpan instance, and add it to myDateTime4
   TimeSpan myTimeSpan = new TimeSpan(4, 12, 10);
   myDateTime4 += myTimeSpan;
   DisplayDateTime("myDateTime4", myDateTime4);
 }

} 


      </source>


illustrates the use of TimeSpan properties and methods

<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110

  • /

/* 

 Example9_5.cs illustrates the use of TimeSpan properties and methods
  • /

using System; public class Example9_5 { 

 public static void DisplayTimeSpan(
   string name, TimeSpan myTimeSpan
 )
 {
   Console.WriteLine(name + " = " + myTimeSpan);
   // display the TimeSpan"s properties
   Console.WriteLine(name + ".Days = " + myTimeSpan.Days);
   Console.WriteLine(name + ".Hours = " + myTimeSpan.Hours);
   Console.WriteLine(name + ".Minutes = " + myTimeSpan.Minutes);
   Console.WriteLine(name + ".Seconds = " + myTimeSpan.Seconds);
   Console.WriteLine(name + ".Milliseconds = " +
     myTimeSpan.Milliseconds);
   Console.WriteLine(name + ".Ticks = " + myTimeSpan.Ticks);
 }

 public static void Main()
 {
   // create a TimeSpan instance, specifying the hours, minutes,
   // and seconds
   int hours = 4;
   int minutes = 12;
   int seconds = 10;
   TimeSpan myTimeSpan = new TimeSpan(hours, minutes, seconds);
   Console.WriteLine("myTimeSpan = " + myTimeSpan);
   // create a TimeSpan instance, specifying the days, hours, minutes,
   // and seconds
   int days = 1;
   TimeSpan myTimeSpan2 = new TimeSpan(days, hours, minutes, seconds);
   Console.WriteLine("myTimeSpan2 = " + myTimeSpan2);
   // create a TimeSpan instance, specifying the days, hours, minutes,
   // seconds, and milliseconds
   int milliseconds = 20;
   TimeSpan myTimeSpan3 =
     new TimeSpan(days, hours, minutes, seconds, milliseconds);
   Console.WriteLine("myTimeSpan3 = " + myTimeSpan3);
   // create a TimeSpan instance, specifying the number of ticks
   long ticks = 300;
   TimeSpan myTimeSpan4 = new TimeSpan(ticks);
   Console.WriteLine("myTimeSpan4 = " + myTimeSpan4);
   // display the properties for myTimeSpan
   Console.WriteLine("myTimeSpan.Days = " +
     myTimeSpan.Days);
   Console.WriteLine("myTimeSpan.Hours = " +
     myTimeSpan.Hours);
   Console.WriteLine("myTimeSpan.Minutes = " +
     myTimeSpan.Minutes);
   Console.WriteLine("myTimeSpan.Seconds = " +
     myTimeSpan.Seconds);
   Console.WriteLine("myTimeSpan.Milliseconds = " +
     myTimeSpan.Milliseconds);
   Console.WriteLine("myTimeSpan.Ticks = " +
     myTimeSpan.Ticks);
   Console.WriteLine("myTimeSpan.TotalDays = " +
     myTimeSpan.TotalDays);
   Console.WriteLine("myTimeSpan.TotalHours = " +
     myTimeSpan.TotalHours);
   Console.WriteLine("myTimeSpan.TotalMinutes = " +
     myTimeSpan.TotalMinutes);
   Console.WriteLine("myTimeSpan.TotalSeconds = " +
     myTimeSpan.TotalSeconds);
   Console.WriteLine("myTimeSpan.TotalMilliseconds = " +
     myTimeSpan.TotalMilliseconds);
   // use the FromDays(), FromHours(), FromMinutes(), FromSeconds(),
   // FromMilliseconds(), and FromTicks() methods to create new
   // TimeSpan instances
   TimeSpan myTimeSpan5 = TimeSpan.FromDays(5);
   Console.WriteLine("TimeSpan.FromDays(5) = " +
     myTimeSpan5);
   TimeSpan myTimeSpan6 = TimeSpan.FromHours(10);
   Console.WriteLine("TimeSpan.FromHours(10) = " +
     myTimeSpan6);
   TimeSpan myTimeSpan7 = TimeSpan.FromMinutes(30);
   Console.WriteLine("TimeSpan.FromMinutes(30) = " +
     myTimeSpan7);
   TimeSpan myTimeSpan8 = TimeSpan.FromSeconds(15);
   Console.WriteLine("TimeSpan.FromSeconds(15) = " +
     myTimeSpan8);
   TimeSpan myTimeSpan9 = TimeSpan.FromMilliseconds(200);
   Console.WriteLine("TimeSpan.FromMilliseconds(200) = " +
     myTimeSpan9);
   TimeSpan myTimeSpan10 = TimeSpan.FromTicks(500);
   Console.WriteLine("TimeSpan.FromTicks(500) = " +
     myTimeSpan10);
   // use the Parse() method to convert strings to TimeSpan instances
   TimeSpan myTimeSpan11 = TimeSpan.Parse("8:10:30");
   Console.WriteLine("TimeSpan.Parse(\"8:10:30\") = " +
     myTimeSpan11);
   TimeSpan myTimeSpan12 = TimeSpan.Parse("1.8:10:30.1234567");
   Console.WriteLine("TimeSpan.Parse(\"1.8:10:30.1234567\") = " +
     myTimeSpan12);
   // use the Add() method to add a TimeSpan instance to another
   TimeSpan myTimeSpan13 = new TimeSpan(1, 10, 13);
   TimeSpan myTimeSpan14 = new TimeSpan(2, 6, 10);
   TimeSpan myTimeSpan15 = myTimeSpan13.Add(myTimeSpan14);
   Console.WriteLine("myTimeSpan13 = " + myTimeSpan13);
   Console.WriteLine("myTimeSpan14 = " + myTimeSpan14);
   Console.WriteLine("myTimeSpan15 = " + myTimeSpan15);
   // use the Subtract() method to subtract a TimeSpan instance
   // from another
   myTimeSpan15 = myTimeSpan13.Subtract(myTimeSpan14);
   Console.WriteLine("myTimeSpan15 = " + myTimeSpan15);
   // use the Duration() method to add two TimeSpan instances
   Console.WriteLine("myTimeSpan15.Duration() = " +
     myTimeSpan15.Duration());
   // use the Negate() method to add two TimeSpan instances
   Console.WriteLine("myTimeSpan15.Negate() = " +
     myTimeSpan15.Negate());
   Console.WriteLine("myTimeSpan14.Negate() = " +
     myTimeSpan14.Negate());
 }

} 


      </source>


Look at the min and max date/time values

<source lang="csharp">

using System; using System.Globalization; class MainClass { 

   public static void Main() {
       
       Console.WriteLine("Min Date: {0}", DateTime.MinValue.ToString());
       Console.WriteLine("Max Date: {0}", DateTime.MaxValue.ToString());
   }

} 

</source>


Measures the time taken to add some numbers

<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110

  • /

/* 

 Example9_6.cs measures the time taken to add some numbers
  • /

using System; public class Example9_6 { 

 public static void Main()
 {
   // create a DateTime object and set it to the
   // current date and time
   DateTime start = DateTime.Now;
   // add numbers using a for loop
   long total = 0;
   for (int count = 0; count < 1000000; count++)
   {
     total += count;
   }
   // subtract the current date and time from the start,
   // storing the difference in a TimeSpan
   TimeSpan timeTaken = DateTime.Now - start;
   // display the number of milliseconds taken to add the numbers
   Console.WriteLine("Milliseconds = " + timeTaken.Milliseconds);
   // display the total of the added numbers
   Console.WriteLine("total = " + total);
 }

} 


      </source>


new DateTime( 29)

<source lang="csharp"> 

   using System;
   class MainClass
   {
       public static void Main()
       {
           DateTime dt = new DateTime(1900, 2, 29);
      }
   }
</source>


new DateTime( 29, new JulianCalendar())

<source lang="csharp"> using System; using System.Globalization; class MainClass { 

   public static void Main() {
       DateTime dt = new DateTime(1900, 2, 29, new JulianCalendar());
   }

} 

</source>


Offset of DateTime

<source lang="csharp"> using System; public class MainClass { 

   public static void Main() {
       DateTimeOffset local = DateTimeOffset.Now;
       DateTimeOffset utc = local.ToUniversalTime();
       Console.WriteLine(local.Offset);   // -06:00:00 (in Central America)
       Console.WriteLine(utc.Offset);     // 00:00:00
       Console.WriteLine(local == utc);                 // True
       //To include the Offset in the comparison, you must use the EqualsExact method:
       Console.WriteLine(local.EqualsExact(utc));      // False
   }

} 

</source>


Output DateTime object

<source lang="csharp"> using System; using System.Globalization; public class DatesApp { 

   public static void Main(string[] args) {
       DateTime dt = DateTime.Now;
       Console.WriteLine(dt);
       Console.WriteLine("date = {0}, time = {1}\n",dt.Date, dt.TimeOfDay);
   }

} 

</source>


Parse and ParseExact

<source lang="csharp"> 

  using System;
  
  class MainClass
  {
     public static void Main(string[] args)
     {
        DateTime dt1 = DateTime.Parse("Sep 2005");
        Console.WriteLine(dt1);
        DateTime dt2 = DateTime.Parse("Monday 5 September 2005 14:15:33");
        Console.WriteLine(dt2);
        DateTime dt3 = DateTime.Parse("5, 9,05");
        Console.WriteLine(dt3);
        DateTime dt4 = DateTime.Parse("5/9/2005 14:15:33");
        Console.WriteLine(dt4);
        DateTime dt5 = DateTime.Parse("2:15 PM");
        Console.WriteLine(dt5);
        DateTime dt6 = DateTime.ParseExact("2:13:30 PM", "h:mm:ss tt", null);
        Console.WriteLine(dt6);
        DateTime dt7 = DateTime.ParseExact("Mon, 05 Sep 2005 14:13:30 GMT","ddd, dd MMM yyyy HH":"mm":"ss "GMT"", null);
        Console.WriteLine(dt7);
        DateTime dt8 = DateTime.ParseExact("September 05", "MMMM dd", null);
        Console.WriteLine(dt8);
      }
  }
</source>


Specify Kind DateTime

<source lang="csharp"> using System; public class MainClass { 

   public static void Main() {
       DateTime d = new DateTime(2000, 12, 12);
       DateTime utc = DateTime.SpecifyKind(d, DateTimeKind.Utc);
       Console.WriteLine(utc);
   }

} 

</source>


use the Add() method to add a TimeSpan to a DateTime

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       TimeSpan myTimeSpan = new TimeSpan(1, 2, 4, 10);
       DateTime myDateTime6 = DateTime.Parse("1/13/2004 23:10:30");
       DateTime myDateTime7 = myDateTime6.Add(myTimeSpan);
       Console.WriteLine("myTimeSpan = " + myTimeSpan);
       Console.WriteLine("myDateTime6.Add(myTimeSpan) = " + myDateTime7);
   }

} 

</source>


use the AddYears(), AddMonths(), AddDays(), AddMinutes(), and AddSeconds() methods to add periods to a DateTime

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       DateTime myDateTime9 = new DateTime(2004, 1, 1);
       Console.WriteLine("Initial myDateTime9 = " + myDateTime9);
       myDateTime9 = myDateTime9.AddYears(1);
       myDateTime9 = myDateTime9.AddMonths(5);
       myDateTime9 = myDateTime9.AddDays(3);
       myDateTime9 = myDateTime9.AddMinutes(30);
       myDateTime9 = myDateTime9.AddSeconds(15);
       Console.WriteLine("Final myDateTime9 = " + myDateTime9);
   }

} 

</source>


use the Compare() method to compare DateTime instances

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       DateTime myDateTime = DateTime.Now;
       DateTime myDateTime2 = DateTime.UtcNow;
       DateTime myDateTime3 = new DateTime(2004, 1, 13);
       DateTime myDateTime4 = new DateTime(2004, 1, 14);
       Console.WriteLine("myDateTime3 = " + myDateTime3);
       Console.WriteLine("myDateTime4 = " + myDateTime4);
       int intResult = DateTime.rupare(myDateTime3, myDateTime4);
       Console.WriteLine("DateTime.rupare(myDateTime3,myDateTime4) = " + DateTime.rupare(myDateTime, myDateTime2));
   }

} 

</source>


use the DaysInMonth() method to retrieve the number of days in a particular month and year

<source lang="csharp">

using System; class MainClass { 

   public static void Main() {
       int days = DateTime.DaysInMonth(2004, 1);
       Console.WriteLine("DateTime.DaysInMonth(2004, 1) = " + days);
   }

} 

</source>


use the Equals() method to compare DateTime instances

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       DateTime myDateTime3 = new DateTime(2004, 1, 13);
       DateTime myDateTime4 = new DateTime(2004, 1, 14);
       bool boolResult = DateTime.Equals(myDateTime3, myDateTime4);
       Console.WriteLine("DateTime.Equals(myDateTime3,myDateTime4) = " + boolResult);
       boolResult = myDateTime3.Equals(myDateTime4);
       Console.WriteLine("myDateTime3.Equals(myDateTime4) is " + boolResult);
   }

} 

</source>


use the IsLeapYear() method to determine if a particular year is a leap year

<source lang="csharp">

using System; class MainClass { 

   public static void Main() {
       bool boolResult = DateTime.IsLeapYear(2004);
       Console.WriteLine("DateTime.IsLeapYear(2004) = " + boolResult);
   }

} 

</source>


use the Now and UtcNow properties to get the currrent date and time

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       Console.WriteLine("DateTime.Now = " + DateTime.Now);
       Console.WriteLine("DateTime.UtcNow = " + DateTime.UtcNow);
       DateTime myDateTime = DateTime.Now;
       Console.WriteLine("myDateTime = " + myDateTime);
       DateTime myDateTime2 = DateTime.UtcNow;
       Console.WriteLine("myDateTime = " + myDateTime);
   }

} 

</source>


use the overloaded addition operator (+) to add a TimeSpan to a DateTime

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       TimeSpan myTimeSpan = new TimeSpan(1, 2, 4, 10);
       DateTime myDateTime6 = DateTime.Parse("1/13/2004 23:10:30");
       DateTime myDateTime8 = myDateTime6 + myTimeSpan;
       Console.WriteLine("myDateTime6 + myTimeSpan = " + myDateTime8);
   }

} 

</source>


use the overloaded less than operator (

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       DateTime myDateTime3 = new DateTime(2004, 1, 13);
       DateTime myDateTime4 = new DateTime(2004, 1, 14);
       bool boolResult = myDateTime3 < myDateTime4;
       Console.WriteLine("myDateTime3 < myDateTime4 is " + boolResult);
   }

} 

</source>


use the overloaded subtraction operator (-) to subtract a TimeSpan from a DateTime

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       TimeSpan myTimeSpan = new TimeSpan(1, 2, 4, 10);
       DateTime myDateTime6 = DateTime.Parse("1/13/2004 23:10:30");
       DateTime myDateTime8 = myDateTime6 - myTimeSpan;
       Console.WriteLine("myDateTime6 - myTimeSpan = " + myDateTime8);
   }

} 

</source>


use the Parse() method to convert strings to DateTime instances

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       DateTime myDateTime5 = DateTime.Parse("1/13/2004");
       DateTime myDateTime6 = DateTime.Parse("1/13/2004 23:10:30");
       Console.WriteLine("myDateTime5 = " + myDateTime5);
       Console.WriteLine("myDateTime6 = " + myDateTime6);

   }

} 

</source>


use the Subtract() method to subtract a TimeSpan from a DateTime

<source lang="csharp"> using System; class MainClass { 

   public static void Main() {
       TimeSpan myTimeSpan = new TimeSpan(1, 2, 4, 10);
       DateTime myDateTime6 = DateTime.Parse("1/13/2004 23:10:30");
       DateTime myDateTime7 = myDateTime6.Subtract(myTimeSpan);
       Console.WriteLine("myDateTime6.Subtract(myTimeSpan) = " + myDateTime7);

   }

} 

</source>


What day of the month is this?

<source lang="csharp"> using System; using System.Collections.Generic; using System.Text; class Program { 

   static void Main(string[] args) {
       DateTime dt = new DateTime(2004, 10, 17);
       
       Console.WriteLine("The day of {0} is {1}", dt.Date, dt.DayOfWeek);
   }

} 

</source>
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