User Friendly Time Duration

The largest value for a .NET TimeSpan is the duration in Days. This sample uses the Time Period Library for .NET[^] to represent a TimeSpan in Months and Years.

An important aspect is the referring date of the TimeSpan. Because Months contain varying number of days, the same duration produces - depending to the referring date - different target dates.

The next snippet redirects a TimeSpan into two DateTime and returns an user friendly duration using DateDiff.GetDescription:

// ----------------------------------------------------------------------
public string GetTimeSpanDescription( TimeSpan timeSpan, int precision = int.MaxValue )
{
  return GetTimeSpanDescription( DateTime.Now, timeSpan, precision );
} // GetTimeSpanDescription

// ----------------------------------------------------------------------
public string GetTimeSpanDescription( DateTime moment, TimeSpan timeSpan, int precision = int.MaxValue )
{
  if ( timeSpan == TimeSpan.Zero )
  {
    return string.Empty;
  }

  bool isPositive = timeSpan > TimeSpan.Zero;
  DateTime date1 = isPositive ? moment : moment.Subtract( timeSpan );
  DateTime date2 = isPositive ?  moment.Add( timeSpan ) : moment;

  return new DateDiff( date1, date2 ).GetDescription( precision );
} // GetTimeSpanDescription

And now some samples:

// ----------------------------------------------------------------------
public void UserFriendlyTimeSpanSample()
{
  TimeSpan lastVisit = new TimeSpan( 400, 7, 25, 0 );
  Console.WriteLine( "last visit before {0}", 
    GetTimeSpanDescription( lastVisit, 3 ) );
    // > last visit before: 1 Year 1 Month 3 Days

  // 60 days
  TimeSpan reminderDuration = new TimeSpan( 60, 0, 0, 0, 0 );
  Console.WriteLine( "reminder duration: {0} Days", reminderDuration.TotalDays );

  DateTime now = DateTime.Now;
  DateTime moment1 = new DateTime( 2011, 4, 1 );
  DateTime moment2 = new DateTime( 2011, 2, 1 );
  DateTime moment3 = new DateTime( 2011, 3, 1 );

  // past
  Console.WriteLine( "last reminder (from now): {0}", 
    GetTimeSpanDescription( now, reminderDuration.Negate() ) );
    // > last reminder (from now): -1 Months -30 Days
  Console.WriteLine( "last reminder ({0:d}): {1}", moment1, 
    GetTimeSpanDescription( moment1, reminderDuration.Negate() ) );
    // > last reminder (01.04.2011): -1 Months -29 Days
  Console.WriteLine( "last reminder ({0:d}): {1}", moment2, 
    GetTimeSpanDescription( moment2, reminderDuration.Negate() ) );
    // > last reminder (01.02.2011): -2 Months -1 Days
  Console.WriteLine( "last reminder ({0:d}): {1}", moment3, 
    GetTimeSpanDescription( moment3, reminderDuration.Negate() ) );
    // > last reminder (01.03.2011): -1 Months -29 Days

  // future
  Console.WriteLine( "next reminder (from now): {0}", 
    GetTimeSpanDescription( now, reminderDuration ) );
    // > next reminder (from now): 1 Month 29 Days
  Console.WriteLine( "next reminder {0:d}: {1}", moment1, 
    GetTimeSpanDescription( moment1, reminderDuration ) );
    // > next reminder 01.04.2011: 1 Month 30 Days
  Console.WriteLine( "next reminder {0:d}: {1}", moment2, 
    GetTimeSpanDescription( moment2, reminderDuration ) );
    // > next reminder 01.02.2011: 2 Months 1 Day
  Console.WriteLine( "next reminder {0:d}: {1}", moment3, 
    GetTimeSpanDescription( moment3, reminderDuration ) );
    // > next reminder 01.03.2011: 1 Month 29 Days
} // UserFriendlyTimeSpanSample