Sometimes, I’ve been formatting date in order to display them in an application.

DateTime.ToString Converts the value of the current DateTime object to its equivalent string representation using the specified format. Here is some nice code from msdn that shows you that.

using System;

public class DateToStringExample
{
   public static void Main()
   {
      DateTime dateValue = new DateTime(2008, 6, 15, 21, 15, 07);
      // Create an array of standard format strings.
      string[] standardFmts = {"d", "D", "f", "F", "g", "G", "m", "o", 
                               "R", "s", "t", "T", "u", "U", "y"};
      // Output date and time using each standard format string.
      foreach (string standardFmt in standardFmts)
         Console.WriteLine("{0}: {1}", standardFmt, 
                           dateValue.ToString(standardFmt));
      Console.WriteLine();

      // Create an array of some custom format strings.
      string[] customFmts = {"h:mm:ss.ff t", "d MMM yyyy", "HH:mm:ss.f", 
                             "dd MMM HH:mm:ss", @"\Mon\t\h\: M", "HH:mm:ss.ffffzzz" };
      // Output date and time using each custom format string.
      foreach (string customFmt in customFmts)
         Console.WriteLine("'{0}': {1}", customFmt,
                           dateValue.ToString(customFmt));
   }
}
// This example displays the following output to the console:
//       d: 6/15/2008
//       D: Sunday, June 15, 2008
//       f: Sunday, June 15, 2008 9:15 PM
//       F: Sunday, June 15, 2008 9:15:07 PM
//       g: 6/15/2008 9:15 PM
//       G: 6/15/2008 9:15:07 PM
//       m: June 15
//       o: 2008-06-15T21:15:07.0000000
//       R: Sun, 15 Jun 2008 21:15:07 GMT
//       s: 2008-06-15T21:15:07
//       t: 9:15 PM
//       T: 9:15:07 PM
//       u: 2008-06-15 21:15:07Z
//       U: Monday, June 16, 2008 4:15:07 AM
//       y: June, 2008
//       
//       'h:mm:ss.ff t': 9:15:07.00 P
//       'd MMM yyyy': 15 Jun 2008
//       'HH:mm:ss.f': 21:15:07.0
//       'dd MMM HH:mm:ss': 15 Jun 21:15:07
//       '\Mon\t\h\: M': Month: 6
//       'HH:mm:ss.ffffzzz': 21:15:07.0000-07:00