C# Writing Time Through Two Dates as String

Question

I have a begin and start DateTime for a conversion that gets logged at the start and end of this event. I then generate a report that lists a bunch of information about the event including its runtime. I have a column for total time elapsed (in days) and a date representation of start and stop. Everything is in days, I don't care about hours/minutes/seconds.

If the start time is 9/29/2010 and the end time is 9/31/2010 I want to print:

9/29-31/2010

If the start time is 9/29/2010 and the end time is 10/2/2010 I want to print:

9/29-10/2/2010

If the start time is 12/29/2010 and the end time is 1/2/2011 I want to print:

12/29/2010-1/2/2011

I know I can use the ToString("M/d/yyyy") method of datetime to print each individual date, but I'm hoping for an easy way to print two dates in a similar format.

Answer 1

I think you just have to code it, it is just 2 if statements... is year different, is month different, else.

Something like

if (d1.year == d2.year)
{
  if (d1.month == d2.month)
     print format 1
  else
     print format 2
}
else
  print format 3

Answer 2

Your rules are pretty simple to translate to code, no need to get fancy.

static string GetDateRangeString(DateTime startDate, DateTime endDate)
{
    if (endDate.Year != startDate.Year)
    {
        return startDate.ToString("M/d/yyyy") + "-" + endDate.ToString("M/d/yyyy");
    }
    else if (endDate.Month != startDate.Month)
    {
        return startDate.ToString("M/d") + "-" + endDate.ToString("M/d/yyyy");
    }
    else
    {
        return startDate.ToString("M/d") + "-" + endDate.ToString("d/yyyy");
    }
}

Demos:

Console.WriteLine(GetDateRangeString(new DateTime(2010, 9, 29), new DateTime(2010, 9, 30)));
Console.WriteLine(GetDateRangeString(new DateTime(2010, 9, 29), new DateTime(2010, 10, 30)));
Console.WriteLine(GetDateRangeString(new DateTime(2010, 9, 29), new DateTime(2011, 1, 30)));

Answer 3

// Precondition: dt1 < dt2
string dateString1 = dt1.ToString("M/d/yyyy");
string dateString2 = dt2.ToString("M/d/yyyy");
if (dt1.Year == dt2.Year)
{
    dateString1 = dateString1.Substring(0, dateString1.Length - 5);
    if (dt1.Month == dt2.Month)
    {
        dateString2 = dateString2.Substring(dt1.Month < 10 ? 2 : 3);
    }
}
string finalValue = String.Format("{0}-{1}", dateString1, dateString2);

Answer 4

You didn't specify how it should be printed out if they are in fact the same date. Going to assume in that case that only a single date should be printed out.

static string DateRangeToString(DateTime left, DateTime right) { 
  if ( left.Year != right.Year ) {
    return String.Format("{0}-{1}", left.ToString("M/d/yyyy"), right.ToString("M/d/yyyy"));
  } else if ( left.Month != right.Month ) { 
    return String.Format("{0}-{1}", left.ToString("M/d"), right.ToString("M/d/yyyy"));
  } else if ( left.Day != right.Day ) { 
    return String.Format("{0}-{1}", left.ToString("M/d"), right.ToString("d/yyyy"));
  } else {
    return left.ToString("M/d/yyyy");
  }
}