TimeSpan FormatString with optional hours

I 开发者_StackOverflow社区have a timespan, ts, that has mostly minutes and seconds, but sometimes hours. I'd like ts to return a formatted string that'll give the following results:

3:30 (hours not displayed, showing only full minutes)
13:30 
1:13:30 (shows only full hours instead of 01:13:30)

So far I have:

string TimeSpanText = string.Format("{0:h\\:mm\\:ss}", MyTimeSpan);

but it's not giving the above results. How can I achieve the results I want?

Maybe you want something like

string TimeSpanText = string.Format(
    MyTimeSpan.TotalHours >= 1 ? @"{0:h\:mm\:ss}" : @"{0:mm\:ss}",
    MyTimeSpan); 

I don't think a single format string will give you what you want, but building the output yourself is a simple task:

public string FormatTimeSpan(TimeSpan ts)
{
    var sb = new StringBuilder();

    if ((int) ts.TotalHours > 0)
    {
        sb.Append((int) ts.TotalHours);
        sb.Append(":");
    }

    sb.Append(ts.Minutes.ToString("m"));
    sb.Append(":");
    sb.Append(ts.Seconds.ToString("ss"));

    return sb.ToString();
}

EDIT: Better idea!

You could make the method above an extension method on the TimeSpan class like so:

public static class Extensions
{
    public static string ToMyFormat(this TimeSpan ts)
    {
        // Code as above.
    }
}

Then using this is as simple as invoking ts.ToMyFormat().