Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: Which code style do you prefer the most?
Date: Sat, 01 Mar 2025 21:56:47 -0800
Organization: A noiseless patient Spider
Lines: 47
Message-ID: <865xksx9eo.fsf@linuxsc.com>
References: <vpkmq0$21php$1@dont-email.me> <vplhc7$26ur1$3@dont-email.me> <87v7swzzl7.fsf@onesoftnet.eu.org> <vpn4qi$2j0hq$1@dont-email.me> <vpo20n$2o9ks$1@dont-email.me> <vpo7ec$2ovro$1@dont-email.me> <87a5a7k0ko.fsf@onesoftnet.eu.org> <vpps7v$34tq7$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Injection-Date: Sun, 02 Mar 2025 06:57:09 +0100 (CET)
Injection-Info: dont-email.me; posting-host="3262fa73ab11de5fd8cc37f0606a7eed";
	logging-data="695078"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX188D9zCOd4xtdiOi++nQmqlyqsanY1oR7I="
User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.4 (gnu/linux)
Cancel-Lock: sha1:bdQL9VuR8tsXHi7yOdBYa1JebmI=
	sha1:p2L2I0qT1+Zx3GEzpLiHKquCKIc=
Bytes: 2836

bart <bc@freeuk.com> writes:

> On 27/02/2025 12:56, Ar Rakin wrote:
>
>> [concerning line splicing with \ at end of line]
>
> Then line-splicing, which combines two lines if the first ends
> with \, is done before processing // comments.
>
>> I am aware that you can do the same thing with strings like this:
>>
>> fprintf(stderr, "multi\
>> line\
>> strings\
>> are fun.");
>>
>> I can understand how this might be useful;  but with *comments*??
>> Was that actually a thing in the official C standards?
>
> It's isn't that useful for strings;  the following is simpler and
> also works:
>
>   "multi"
>   "line"
>   "string"

Just as a historical note, this construction wasn't available in
pre-standard C.  So line splicing used to be needed in such cases.

> But it is needed for multi-line macros, as C's proprocessor is
> strictly line-oriented and a macro definition must fit onto one
> line.

Since 1989 when the original C standard was done, multi-line macros
can be written without needing to use \ for line splicing.  I was
surprised to learn this when I first saw it.  An example:

    #define MASK_WIDTH( m ) ( 0U + (unsigned)+(          /*
    */    (m)  /((m)%32767 +1)  /32767  %32767  *15      /*
    */    +  (m)  %32767  /((m)%31 +1)  /31  %31  *5     /*
    */    +  4  -  12 / ((m)%31 + 3)                     /*
    */))

Yes, it's ugly.  Yes, it means line breaks can be put in only at
token boundaries (although in practice that limitation is observed
anyway).  Yes, I know of no production code that uses this
technique.  Still I think this trick is one worth knowing about.