Format a timespan with up to two fields

Question

I'm looking to achieve a time format that looks like this: 2d 4h remaining; or 1h 36m remaining; or 35s remaining, etc. So that it only displays the two largest values of time (this is how Clash of Clans and some other mobile games format wait times.)

Currently my code is below, but I'm wondering if there might be a shorter way to format the timespan in this manner? I'm not fully sure if String.Format will work…

public string FormatRushTime ( System.TimeSpan span )
{
    string t1;
    string t2;
    if ( span.Days > 0 )
    {
        t1 = span.ToString("%d") + "d";
        t2 = span.Hours > 0 ? span.ToString("%h") + "h" : String.Empty;
    }
    else if ( span.Hours > 0 )
    {
        t1 = span.ToString("%h") + "h";
        t2 = span.Minutes > 0 ? span.ToString("%m") + "m" : String.Empty;
    }
    else if ( span.Minutes > 0 )
    {
        t1 = span.ToString("%m") + "m";
        t2 = span.Seconds > 0 ? span.ToString("%s") + "s" : String.Empty;
    }
    else if ( span.Seconds > 0 )
    {
        t1 = span.ToString("%s") + "s";
        t2 = String.Empty;
    }
    else
    {
        t1 = String.Empty;
        t2 = String.Empty;
    }

    return t1+" "+t2;
}

Answer 1

What you want to do, is use early-returns (FTW). Also, let the formatter do the string work for you. Right tool for the job.

Consider your code, rewritten in Ideone...:

static string FormatRushTime (TimeSpan span)
{
    if ( span.Days != 0 )
    {
        return String.Format("{0:d}d {1:d}h", span.Days, Math.Abs(span.Hours));
    }
    if ( span.Hours != 0 )
    {
        return String.Format("{0:d}h {1:d}m", span.Hours, Math.Abs(span.Minutes));
    }
    if ( span.Minutes != 0 )
    {
        return String.Format("{0:d}m {1:d}s", span.Minutes, Math.Abs(span.Seconds));
    }
    return String.Format("{0:d}s", span.Seconds);
}

Answer 2

I love LINQ so I present two solutions.

public static string FormatRushTime(System.TimeSpan span)
{
    var time = new[] 
        {
            new { Unit = "d", Value = span.Days },
            new { Unit = "h", Value = span.Hours},
            new { Unit = "m", Value = span.Minutes},
            new { Unit = "s", Value = span.Seconds}
        };

    var filtred = time.SkipWhile(t => t.Value == 0)
                      .Take(2)
                      .Where(t => t.Value != 0)
                      .Select(t => String.Format("{0}{1} ", t.Value, t.Unit));

    return String.Concat(filtred);
}

I'm not sure if it's readable beacause I'm pretty tired. :)

public static string FormatRushTime(System.TimeSpan span)
{
    string[] units = { "d", "h", "m", "s" };

    var r = units.Select(unit => new { Unit = unit, Value = span.ToString("%" + unit) })
                 .SkipWhile(time => time.Value == "0")
                 .Take(2)
                 .Where(time => time.Value != "0")
                 .Select(time => String.Format("{0}{1} ", time.Value, time.Unit));

    return string.Concat(r);
}

Answer 3

You can take advantage of custom format strings for TimeSpan. Modifying rolfl's answer to use those, it could look something like:

public static string FormatRushTime(TimeSpan span)
{
    var result = span.ToString(GetRushTimeFormat(span));

    if (span < TimeSpan.Zero)
        result = "-" + result;

    return result;
}

private static string GetRushTimeFormat(TimeSpan span)
{
    if (span.Days != 0)
        return @"d\d\ h\h";

    if (span.Hours != 0)
        return @"h\h\ m\m";

    if (span.Minutes != 0)
        return @"m\m\ s\s";

    return @"s\s";
}