Re: About conversions

[Robert Dewar <robert_dewar@my-deja.com>]

In article <200011240739.IAA22865@bulgaria.otn.eurocopter.de>,
  comp.lang.ada@ada.eu.org wrote:
> About -14 mod 5:
>
> > Sorry, but "mod x" always delivers values between 0 and x (x
excluded).
> > So the result is 1 and not -4.
>
> As always 0 - X = X = 0 + X:
>
> 0 - 14 mod 5 = -14 mod 5 = -(14 mod 5) /= (-14) mod 5 = 0 +
(-14) mod 5
>

Well you can always trust some Ada expert to get egg on their
face with this one (I certainly did the first time I saw it)

-14 mod 5 = -(14 mod 5) = -4

Yes, that's the way precedences work in Ada :-)

chuckle chuckle

Robert

P.S. I asked nearly every Ada expert this question, and all
got it wrong, except for Robert Eachus :-)

The reason that it is tricky is that it misdirects in a nasty
way. You know of course that there must be a trick, otherwise
why ask the question, but you are too clever, and think the
trick has to do with the way mod works on negative numbers :-)

Needless to say, it is terrible Ada style to depend on this
peculiar precedence rule for minus :-)



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