On 4/17/07, mwmarkland / yahoo.com <mwmarkland / gmail.com> wrote:
> I have been reading _The Ruby Way_ and am confused by the temperature
> conversion sample program on page 14.
>
> The line in question is
>
> abort "#{temp} is not a valid number." if temp !~ /-?\d+/
>
> What I do not understand is that if \d matches "digits", which I
> understand to be [0-9], how can this expression match "98.6", which it
> seems to do just fine.
>
> Thank you in advance for the clarification.
Well I guess you are a bright student.
The regexp part has been nicely answered by Bill and it follows that a
regular expression allowing for all kind of different string
representations of Floats is quite
complex.
Why not let ruby do the work for us ;)
May I introduce you to this idiom:

Float( temp ) rescue abort temp << " is not a valid number."

Cheers
Robert

>
> (I have the 2nd Edition of _The Ruby Way_, First Printing. I have run
> the example using ruby 1.8.5 (2007-03-13 patchlevel 35) [i386-linux]).
>
> Matt
>
>
>


-- 
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw