Re: Rounding of OS match percentages differs between architectures

[David Fifield <david () bamsoftware com>]

On Wed, Nov 19, 2008 at 07:54:14PM -0500, Michael Pattrick wrote:
> On Wed, Nov 19, 2008 at 6:32 PM, David Fifield <david () bamsoftware com> wrote:
> > Nmap currently uses printf("%d%%", (int) (frac * 100)) to show match
> > percentages. Using printf("%.f%%", frac * 100) would remove this problem
> > but would create another, namely that everything 99.5% and above would
> > be rounded to 100%.
> >
> > Anyone have an opinion on this or see a good way to handle it?
>
> If I understand the problem properly - you want to strip the decimals,
> why not just use floor()?

Hey, thanks, that works! I guess I assumed that ((int) d) and floor(d)
would have the same result when d is positive. Apparently floor has
extra logic to know when its argument is less than but very close to an
integer.

(To see what I mean by "very close to," run python and type in "0.98". I
see "0.97999999999999998" as output.)

I wonder if this is really caused by the C library? Can anyone else
reproduce the "97% 98%" output from the test program I posted?

David Fifield

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