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From: comeau@ditka.Chicago.COM (Greg Comeau)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Side Effects == Rattlesnakes -- watch out for them Re: Compiler code (was a flame fest) (now a lesser flame fest)
Message-ID: <38214@ditka.Chicago.COM>
Date: 4 May 91 23:27:36 GMT
References: <jsmoller.4971@jsmami.UUCP> <24503@well.sf.ca.us> <1991May4.061257.14959@zorch.SF-Bay.ORG>
Sender: comeau@ditka.Chicago.COM (Greg Comeau)
Reply-To: comeau@csanta.attmail.com (Greg Comeau)
Organization: Comeau Computing
Lines: 28

In article <1991May4.061257.14959@zorch.SF-Bay.ORG> xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes:
>> jsmoller@jsmami.UUCP (Jesper Steen Moller) writes:
>>> Oh, by the way: func(a++) Is "a" increased before or after the
>>> function call. I think I once read in K&R that it was undefined, but
>>> I might be mistaken.
>> Nope, not undefined. a is evaluated, and passed to the function when
>> it is called, and then is incremented. This *is* guaranteed.
>Which still leaves the wide open "gotcha" that if func() modifies "a"
>by a side effect during execution, all bets are off as to whether the
>pre-call or the post-call value is what gets incremented and stored
>back in "a".

Not quite wide open in this situation.

I believe a message passed through here a few days ago which correctly
stated that although evaluation orders are still not dictated, that
there is a sequence point generated at function call time.

>Best rule for C side effects -- don't.

... although that rule is most always a good one!

- Greg
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