Boszormenyi Zoltan írta: > Tom Lane írta: > >> Boszormenyi Zoltan <z...@cybertec.at> writes: >> >> >>> for (; length > 0 && ptr[--length] == 0xff;); >>> >>> >> >> >>> I suspect that GCC does the "--length" after checking >>> "length > 0" and before checking the "ptr[...] == 0xff", >>> but HP CC does it before checking "length > 0". >>> >>> >> If it does, that is *unquestionably* a bug in HP's CC and should be >> reported to them. >> > > 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, i.e. they > can be freely reordered or placed anywhere in the > expression, provided that the postfix operator's evaluation > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Above is the prefix case obviously...
> is earlier than the usage of the variable it's used on and > evaluation is later than the variable usage in the postfix case. > This means that their usage has to be minimized so the > result is unambiguous. -- 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
