7 Dec
2010
7 Dec
'10
2:33 a.m.
On Mon, 6 Dec 2010, Brent Hilpert wrote:
Lame. It was the question.
No, it was stated by Sean Conner that if a (admittedly broken) compiler
used a value of 123 for !0, you could circumvent this behaviour with
a double negation, i.e. !!(!0) would produce a 1.
That's what he said:
It was thus said that the Great Philip Pemberton once
stated:
[...]
> However: the compiler would still be correct
to use the value 123
> instead of 1, thus that code may not work... So it's compiler
!!-1 = !(!-1) = !(0) = 123
!!123 = !(!123) = !(0) = 123
!!0 = !(!0) = !(123) = 0
Whether that's correct behaviour or not was not the question. Nope. !b will turn 0 to 1, and anything not 0 to 0.
!!-1 = !(!-1) = !(0) = 1
!!123 = !(!123) = !(0) = 1
!!0 = !(!0) = !(1) = 0
which is clearly not the case if you assume a broken compiler that doesn't
evaluate !(0) to 1. I think I have seen such a compiler (maybe a
cheap PD compiler on the Amiga, but I'm not sure), so it may well be
compiler dependent (although not correct and I've never questioned that).
Is it possible that we are talking past each other?
Christian