From: "A. Sinan Unur" <asu1 AT cornell DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Problems with pgcc
Date: Sun, 25 May 1997 11:17:55 -0400
Organization: Cornell University http://www.cornell.edu
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nikki wrote:
> 
> why pray?
> void main() has always worked before. works fine under gcc, cc and 
> every other c compiler i've ever touched. what's with the '*must* 
> return an int' stuff?

enough is enough. i am not affiliated with the pgcc project. however,
for the sake of public education, here is the relevant quote from the C
FAQ. i mean, if you are going to program in C, read that at least.

you can get it from:

http://www.cis.ohio-state.edu/hypertext/faq/usenet/C-faq/faq/faq.html
 
11.12:  Can I declare main() as void, to shut off these annoying "main
        returns no value" messages?

A:      No.  main() must be declared as returning an int, and as taking
        either zero or two arguments, of the appropriate types.  If
        you're calling exit() but still getting warnings, you may have
        to insert a redundant return statement (or use some kind of "not
        reached" directive, if available).

        Declaring a function as void does not merely shut off or
        rearrange warnings: it may also result in a different function
        call/return sequence, incompatible with what the caller (in
        main's case, the C run-time startup code) expects.

        (Note that this discussion of main() pertains only to "hosted"
        implementations; none of it applies to "freestanding"
        implementations, which may not even have main().  However,
        freestanding implementations are comparatively rare, and if
        you're using one, you probably know it.  If you've never heard
        of the distinction, you're probably using a hosted
        implementation, and the above rules apply.)

        References: ANSI Sec. 2.1.2.2.1, Sec. F.5.1; ISO Sec. 5.1.2.2.1,
        Sec. G.5.1; H&S Sec. 20.1 p. 416; CT&P Sec. 3.10 pp. 50-51.

11.14:  I believe that declaring void main() can't fail, since I'm
        calling exit() instead of returning, and anyway my operating
        system ignores a program's exit/return status.

A:      It doesn't matter whether main() returns or not, or whether
        anyone looks at the status; the problem is that when main() is
        misdeclared, its caller (the runtime startup code) may not even
        be able to *call* it correctly (due to the potential clash of
        calling conventions; see question 11.12).  Your operating system
        may ignore the exit status, and void main() may work for you,
        but it is not portable and not correct.

11.15:  The book I've been using, _C Programing for the Compleat Idiot_,
        always uses void main().

A:      Perhaps its author counts himself among the target audience.
        Many books unaccountably use void main() in examples.  They're
        wrong.

11.16:  Is exit(status) truly equivalent to returning the same status
        from main()?

A:      Yes and no.  The Standard says that they are equivalent.
        However, a few older, nonconforming systems may have problems
        with one or the other form.  Also, a return from main() cannot
        be expected to work if data local to main() might be needed
        during cleanup; see also question 16.4.  (Finally, the two forms
        are obviously not equivalent in a recursive call to main().)

        References: K&R2 Sec. 7.6 pp. 163-4; ANSI Sec. 2.1.2.2.3; ISO
        Sec. 5.1.2.2.3.
-- 
   Sinan
 
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