Formatting a negative TimeSpan

Question

I'm doing some math with the Timespans in .Net, and occasionally the sum results in a negative Timespan. When I display the result I am having trouble formatting it to include the negative indicator.

Dim ts as New Timespan(-10,0,0)  ts.ToString() 

This will display "-10:00:00", which is good but I don't want to show the seconds so tried this.

ts.ToString("hh\:mm") 

This returns "10:00" and has dropped the "-" from the front which is the crux of the issue. My current solution is this:

If(ts < TimeSpan.Zero, "-", "") & ts.ToString("hh\:mm") 

but I was hoping to accomplish the same by using only the format string.

Answer 1

I've used .Net Reflector on TimeSpan.ToString(...) and it really doesn't look like it supports any form of negative prefix on custom formats - so I think you're out of luck when it comes to getting it to work for you as above. :(

Answer 2

It seems like you're stuck with that code, but if so, this seems like a great time to write an extesion method, that way you can make your code clearer and you don't have to repeat that code in multiple places, so something like:

Module Extensions     <System.Runtime.CompilerServices.Extension()> _     Public Function HoursAndMinutes(ByVal ts As TimeSpan) As String         Return If(ts < TimeSpan.Zero, "-", "") & ts.ToString("hh\:mm")     End Function End Module 

And then you could just call it as:

ts.HoursAndMinutes()