NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/std/c/213

Text File | 1996-08-06 | 3.8 KB | 83 lines

Newsgroups: comp.lang.c,comp.std.c
Path: blackbush.xlink.net!slsv6bt!slsv6bt!kanze
From: [e-mail] (James Kanze US/ESC 60/3/141 #40763)
Subject: Re: Integral conversion e.t.c. (was: Re: Hungarian notation)
In-Reply-To: [e-mail]'s message of 27 Jan 1996 12:22:26 -0600
Message-ID: <[e-mail]>
Sender: [e-mail]
Organization: SEL
References: <[e-mail]> <[e-mail]>
    <[e-mail]> <[e-mail]>
    <4edqh2$[e-mail]>
Date: 29 Jan 1996 11:19:56 GMT

In article <4edqh2$[e-mail]> [e-mail]
(Peter Seebach) writes:

|> In article <[e-mail]>, Michael Furman <[e-mail]> wrote:
|> [Re a rule forbidding extensions.]
    [And in particular, additional forms of main...]

|> >My question was: is such rule exists?

|> Sort of.

|> There are two kinds of things called "legal" C.  One is a strictly
|> conforming program, which must be accepted by, and work on, *any*
|> conforming C compiler.  The other is merely a conforming
|> program, which must be accepted by, and work on, *at least one*
|> conforming compiler.  The latter class is meaningless; FORTRAN is
|> conforming C.  (gcc with g77 compiles it.  Technically, gcc is not
|> quite conforming, but nothing is.)

There is more to it than that.  There are many programs (including
most legal fortran programs) for which the compiler is required to
issue a diagnostic (after which, it may go ahead and compile it as
fortran, or cobol, or whatever).

In the particular case which you cite, I do *not* believe that gcc
will compile the program without a diagnostic if the program is in a
file called a.c.  More ever, the compiler documentation definitly
states that only programs in files whose names end in .c will be
compiled as C.  (A legal restriction, as far as I can see.)

I think the crux of Michael Furman's question lies therein.  Does the
standard require a diagnostic if the function main is not of one of
the two types given?

To tell the truth, I'm not sure what the answer is.  The text
concerning main is in the chapter describing the environment.  It
doesn't appear as a semantic restriction or anything.  It simply
states that on start-up, a function called main will be called, and
that the implementation must support the following forms.  It doesn't
seem (to me, at least) to say anything about what other forms it might
support, or what the implementation must do if given a fully other
definition of main.

Normally, I would expect (at the very least) a compiler to generate a
warning or an error for a main that it did not support.  In fact,
however, my compiler (gcc) accepts the following definition without
the slightest complaint, although I'd rather not think about what will
happen when I access parameter d:

    int main( char a , int b , long c , double d )

|> For purposes of the C newsgroups, discussion of what is/isn't legal
|> is generally restricted to strictly conforming C.

Yes and no.  In comp.std.c, the discussion is exactly about what is
legal according to the standard.  In comp.lang.c (to which this
article is also cross-posted), the discussion should generally be a
bit more open.

Thus, for example, in comp.std.c, a program with a variable named far
is illegal, and that is it.  In comp.lang.c (and I hope in its
moderated variant), I would hope that someone would point out that,
legal or not, it's going to get you into trouble.
--
James Kanze         Tel.: [phone]        email: [e-mail]
GABI Software, Sarl., 8 rue des Francs-Bourgeois, F-67000 Strasbourg, France
Conseils, Θtudes et rΘalisations en logiciel orientΘ objet --
                -- A la recherche d'une activitΘ dans une region francophone