Path: utzoo!mnetor!uunet!husc6!sri-unix!quintus!ok
From: ok@quintus.UUCP (Richard A. O'Keefe)
Newsgroups: comp.lang.c
Subject: Re: exit(-1)
Message-ID: <551@cresswell.quintus.UUCP>
Date: 20 Jan 88 00:40:11 GMT
References: <502@cresswell.quintus.UUCP> <6935@brl-smoke.ARPA> <1179@wjvax.UUCP> <7133@brl-smoke.ARPA>
Organization: Quintus Computer Systems, Mountain View, CA
Lines: 42
Summary: VMS *does* handle exit(0)

In article <7133@brl-smoke.ARPA>, gwyn@brl-smoke.ARPA (Doug Gwyn ) writes:
> In article <1225@nmtsun.nmt.edu> hydrovax@nmtsun.nmt.edu (M. Warner Losh) writes:
> >Why would you expect an operating system dependent scheme such as exit(0)
> >to work on all OS's?  The whole world isn't using UNIX.
> If, as you report, VMS C does not currently map exit(0) to something
> sensible, that will have to be fixed before VMS C is ANSI-conforming.

Everything that has been said about VMS and exit(0) so far is false.
I decide that it was time to check the manual.
	Programming in VAX C
	Order Number AA-L370B-TE
	For VAX/VMS version 4.0 or later
	Compiler version VAX C version 2.0
	April 1985.
Section 22.1.2 exit, _exit
	exit([status])
	_exit([status])
	The optional argument status corresponds with [sic!] an errno
	value.  ... The functions return the specified status to the
	parent process.  ... The two functions are identical.

[I do not understand how an argument can exchange letters with
(correspond with) a number.  No doubt they meant "correspond to".
Aren't eddicayshun wunnerful?]

Checking SYS$LIBRARY:ERRNO.H, I found that not only were the errno
symbols (such as EPERM) the same as in UNIX, they had been given the
same numbers as well.  It is clear, therefore, that in the VMS
implementation of C, the argument of exit() is a ***UNIX*** error
number (including 0 as specifying NO error), *NOT* a VMS error code.

Trying several values of N in
	main() { exit(N); }
and	main() { return N; }
I found that *none* of them resulted in any message from DCL;
*all* of them produced a quiet exit.  {But the return code was
available to DCL for inspection, and perror() does plausible things.}

VAX-11 C does more optimisation than most C compilers do.
For compatibility with other compilers, the preprocessor accepts
but IGNORES #pragma.  I wonder about the other compilers that "need"
it, I really do.