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From: guy%gorodish@Sun.COM (Guy Harris)
Newsgroups: comp.lang.c
Subject: Re: Talking of void ...
Message-ID: <31905@sun.uucp>
Date: Sat, 24-Oct-87 23:11:16 EST
Article-I.D.: sun.31905
Posted: Sat Oct 24 23:11:16 1987
Date-Received: Tue, 27-Oct-87 01:32:08 EST
References: <1400@mhres.mh.nl>
Sender: news@sun.uucp
Lines: 28
Keywords: return void cast

> This problem occured when I ported a program to a UN*X system on which
> signal handlers were "void (*func)()", instead of the usual "int (*func)()".

The "usual" type will become "void (*)()" in the future; that is the type
specified in ANSI C and thus in POSIX.  It is the type used by System V Release
3, and will be used in more systems as time goes on.  Had "void" been a part of
C all along, the type of a signal handler probably *would* have been "void
(*)()", since nobody actually *does* something with the return value of a
signal handler (and if somebody built a system where something *was* done with
that return value, all hell would break loose, since most people's signal
handlers don't return values).

> I used a "typedef int SHND_TYPE" in a system-dependent include file, 
> which I changed to "typedef void SHND_TYPE". But then I ran in problems
> with the return *action*, not the *value*:
> 
> SHND_TYPE catchit (...) {
> 	... some useful code ...
> 	return ((SNHD_TYPE) 0);
> }

Why are you returning a value here?  I know of no UNIX system where the return
value of a signal handler is used (and would doubt there *is* such a system,
for the reasons listed above).  Just put "return;" in place of the existing
return statement.
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com