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Groups > comp.lang.c > #162012
| From | James Kuyper <jameskuyper@alumni.caltech.edu> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: How to disambiguate macro? |
| Date | 2021-07-21 06:02 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <sd8rbp$fph$2@dont-email.me> (permalink) |
| References | (2 earlier) <sd6h5j$hng$2@reader1.panix.com> <87fsw9m4qd.fsf@bsb.me.uk> <sd7ud2$hkh$1@reader1.panix.com> <87eebs1h4j.fsf@nosuchdomain.example.com> <sd871m$r0p$1@reader1.panix.com> |
On 7/21/21 12:15 AM, John Forkosh wrote:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
>> John Forkosh <forkosh@panix.com> writes:
...
>>> Thanks, again, for the alternative solution. I actually like it
>>> a little better since it avoids the klutzy do-while construction
>>> that has no useful purpose and might only confuse the casual reader,
>>> i.e., "What the heck is he doing that for?" ...
...
>> The "do .. while (0)" idiom is very widely know. All C programmers
>> *should* know about it. If the macro body is intended to be used in at
>> statement context, that idiom is, as far as I know, the only method that
>> actually works in all cases. Saying that it "has no useful purpose" is
>> incorrect.
>
> I just meant that the semantics of do{xxx;}while(0); is identical
> to just xxx; without the decoration.
It's not a question of "do{xxx;} while(0);" vs. "xxx;". It's a key point
of the idiom that it's "do{xxx; yyy;} while(0)" vs. "{xxx; yyy;}". A
function-like macro should not include the terminating ";", because it
would result in a syntax error if used in various locations where a
function would be perfectly legal. And the problem that "do {xxx; yyy;}
while()" is designed to avoid isn't a problem unless there's at least
two statements inside the {}.
See the following for a more detailed explanation:
>> It's question 10.4 in the comp.lang.c FAQ, http://www.c-faq.com/
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How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 11:15 +0000
Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-20 13:49 +0100
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 12:56 +0000
Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-20 15:36 +0100
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-21 01:48 +0000
Re: How to disambiguate macro? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-20 19:18 -0700
Re: How to disambiguate macro? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-20 20:27 -0700
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-21 04:15 +0000
Re: How to disambiguate macro? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-21 02:00 -0700
Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-21 06:02 -0400
Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-21 06:00 -0400
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-21 10:10 +0000
Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 11:30 +0100
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 13:31 +0200
Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 13:02 +0100
Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 14:20 +0100
Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 15:15 +0100
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 16:28 +0200
Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 16:20 +0100
Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 17:34 +0100
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 19:46 +0200
Re: How to disambiguate macro? Manfred <noname@add.invalid> - 2021-07-21 20:42 +0200
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-22 08:37 +0200
Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 20:47 +0100
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-22 08:47 +0200
Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-22 11:31 +0100
Re: How to disambiguate macro? antispam@math.uni.wroc.pl - 2021-07-22 14:37 +0000
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-22 18:15 +0200
Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 21:19 +0100
Re: How to disambiguate macro? Manfred <noname@add.invalid> - 2021-07-21 15:42 +0200
Re: How to disambiguate macro? scott@slp53.sl.home (Scott Lurndal) - 2021-07-21 15:39 +0000
Re: How to disambiguate macro? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-21 09:22 -0700
Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-21 17:24 -0400
Re: How to disambiguate macro? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-21 16:42 -0700
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-22 05:49 +0000
Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-22 19:11 -0400
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-22 05:30 +0000
Re: How to disambiguate macro? scott@slp53.sl.home (Scott Lurndal) - 2021-07-22 14:14 +0000
Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-22 17:06 +0100
OT: possessive adjectives (Was: How to disambiguate macro?) Manfred <noname@add.invalid> - 2021-07-22 15:04 +0200
Re: OT: possessive adjectives Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 13:37 -0700
Re: How to disambiguate macro? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 13:58 -0700
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-20 14:50 +0200
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 13:19 +0000
Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-20 14:40 +0100
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-20 21:02 +0200
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-20 21:00 +0200
Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 08:15 +0200
Re: How to disambiguate macro? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 23:17 -0700
Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 12:51 +0000
Re: How to disambiguate macro? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-20 08:47 -0700
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