Tom Lane írta: > Andrew Dunstan <and...@dunslane.net> writes: > >> Boszormenyi Zoltan wrote: >> >>> Is it *really* a bug? I recalled a comment from my C teacher >>> in '92 or '93 about this exact issue, that the prefix/postfix >>> increment/decrement operators are executed in the >>> statement in an implementation-defined order, >>> > > >> Not if they come after a short-circuit operator such as && - after all, >> that's what short-circuit evaluation implies. If the left hand operand >> of && is false the right hand should not be evaluated at all. >> > > Yes. && is a sequence point and the compiler is not allowed to move > side-effects across a sequence point. What your C teacher was warning > you against was things like > a[i] = i++; > '=' is not a sequence point so it's undefined which array index > will be stored into. > > regards, tom lane >
Thanks to both of you, this was really informative. Actually my C teacher didn't mention such optimization barriers. It seems I need to look up the raw C language specs... Best regards, Zoltán Böszörményi -- Bible has answers for everything. Proof: "But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil." (Matthew 5:37) - basics of digital technology. "May your kingdom come" - superficial description of plate tectonics ---------------------------------- Zoltán Böszörményi Cybertec Schönig & Schönig GmbH http://www.postgresql.at/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
