Microsoft Visual C#: Time of day arithmetic

• seanconnolly / 100 / Fri, 03 Apr 2009 13:50:00 GMT / Comments (5)
• Hi.

  I am working with a time string that I want to be able to add a value to. If I enter a time of day as hhmm (example 2000), I would like to add a time value as hhmm (0535 + 2000 would return 0135) and return this as a string.

  Can someone help me with an easy way to do this please?

  Thanks.

  My current routine doesn't work, but here is what I have done in sourcecode. The only part that seems to fail is the adding of hours and minutes to the time. Is there a shorter or better way to do this?

  public static string MinSearch(string MyTime, string MinConTime)

  {

  int MinMinutes;

  int MinHours;

  string timestring="";

  DateTime StartTime = Convert.ToDateTime(MyTime.Substring(0,2)+":"+MyTime.Substring(2,2));

  MinMinutes = Convert.ToInt32(MinConTime.Substring(2, 2));

  MinHours = Convert.ToInt32(MinConTime.Substring(0, 2));

  StartTime.AddMinutes(MinMinutes);

  StartTime.AddHours(MinHours);

  timestring = StartTime.ToString().Substring(11, 2) + StartTime.ToString().Substring(14, 2);

  return (timestring);
• Keywords:

  time, day, arithmetic, microsoft, visual c#, vc

• http://msdn.itags.org/visual-csharp/85470/«« Last Thread - Next Thread »»

• 1. I've fixed it! Spotted the obvious mistake

     StartTime = StartTime.AddMinutes(MinMinutes) + StartTime.AddHours(MinHours);

     seanconnolly | Fri, 31 Aug 2007 19:34:00 GMT |

  2. Hah, I'm late.

     Here is my 'corrected' code suggestion:

     using System;

     using System.Text;

     namespace nsTest

     {

     class Program

     {

     public static string MinSearch( string MyTime, string MinConTime )

     {

     int MinMinutes;

     int MinHours;

     StringBuilder timestring = new StringBuilder( 6 );

     DateTime StartTime = Convert.ToDateTime( MyTime.Substring( 0, 2 ) + ":" + MyTime.Substring( 2, 2 ) );

     MinMinutes = Convert.ToInt32( MinConTime.Substring( 2, 2 ) );

     MinHours = Convert.ToInt32( MinConTime.Substring( 0, 2 ) );

     DateTime endTime = StartTime.AddMinutes( MinMinutes ).AddHours( MinHours );

     // using SortableDateTimePattern 'yyyy-MM-ddTHH:mm:ss'

     timestring.Append( endTime.ToString( "s" ).Substring( 11, 2 ) ); // HH

     timestring.Append( endTime.ToString( "s" ).Substring( 14, 2 ) ); // mm

     return ( timestring.ToString() );

     }

     static void Main()

     {

     Console.WriteLine( "MinSearch function 0535 + 2000 = {0}", MinSearch( "0535", "2000" ) );

     Console.ReadKey();

     } // end main

     } // end class

     } // end namespace

     Is your code like this?

     Why you need DateTime in your code? You can do more simple:

     public static string MinSearch( string MyTime, string MinConTime )

     {

     int ret =( Convert.ToInt32( MinConTime)+Convert.ToInt32( MyTime)) % 2400;

     return ret.ToString("0000");

     }

     Selection is in Your hand ]:()

     peca55 | Fri, 31 Aug 2007 19:35:00 GMT |

  3. Hi.

     Thanks for your message. I don't need the date portion and I couldn't find something that just dealt with the time of day.

     Also, your last little function for adding on time does not work correctly. I spotted a big flaw in the logic.

     public static string MinSearch( string MyTime, string MinConTime )

     {

     int ret =( Convert.ToInt32( MinConTime)+Convert.ToInt32( MyTime)) % 2400;

     return ret.ToString("0000");

     }

     If I used an input time of 2057 and added 0535 on, it returns 0192 which is not a valid time. It should have returned 0232 (add another 40 to the number if the right hand portion of the last two digits returned were >= 60).

     I have only been dabbling in C# for the last 9-10 months, but with the pressure from my boss to get something working, I am progressing at full steam with trying to finish all logic operations rather than sit down and really get in deep with the language! Once the panic is over, I will sit down and properly learn the language and optimize it where I can!

     Of the above, is there a way to easily detect the last two digits are higher than 60 and if so, to add the other 40?

     Thanks.

     Sean

     seanconnolly | Fri, 31 Aug 2007 19:36:00 GMT |

  4. Do not fight the DateTime class embrace it......

      public static string MinSearch( string MyTime, string MinConTime ) {
      DateTime StartTime = DateTime.ParseExact(MyTime,"HHmm", CultureInfo.CurrentCulture); TimeSpan MinTime = DateTime.ParseExact(MinConTime, "HHmm", CultureInfo.CurrentCulture) - DateTime.Today;
      DateTime endTime = StartTime + MinTime; return ( endTime.ToString("HHmm") );
      }

     jamescurran | Fri, 31 Aug 2007 19:37:00 GMT |

  5. Thank you James!

     What an elegant way to do this!!! I didn't have any documentation about contolling the DateTime this way before. It's great!!!

     seanconnolly | Fri, 31 Aug 2007 19:38:00 GMT |