I have heard that return -1 is not portable. So what would be the answer
to portability in this case? What about exit(0) and exit (-1) or exit (1)?
Or would it be best to stick with C's macros, hence:

exit(EXIT_FAILURE)
exit (EXIT_SUCCESS)

Bill

In article <2YnWj.20544$5b3.14006@trnddc05>,
Bill Cunningham nspam.com> wrote:

It would be best to stick with C's macros. The results are implementation
defined if you use any value other than 0 or one of the macros.
In particular, exit(1) is *not* something that C assigns any meaning to.

Bill Cunningham wrote:

Presumably you're talking about the return value from main()?

exit(0) is fine.

Those are good too.

"Peter Nilsson" acay.com.au> wrote in message
news:3222fc05-7aee-4eb3-b874-eb55981751dd@v26g2000prm.googlegroups.com...

Yes. Would return -1 from a function other than main be ok? I'm guessing
no but I thought I'd ask.

Bill

On 13 May, 22:57, "Bill Cunningham" nspam.com> wrote:

exit(-1) is not portable no matter which function
calls it.

On Tue, 13 May 2008 21:57:23 +0000, Bill Cunningham wrote:

Are you asking if it's okay to return -1 in such cases as calling
add(2, -3), defined as

int add(int a, int b) {
return a + b;
}

? What else would you want to make this function return?

In article <79oWj.7860$Uz2.2677@trnddc06>,
Bill Cunningham nspam.com> wrote:

For any function other than main, it is fine to return to its
caller any value that lies within the range of the type of the return
value.

But, just in case you meant something different: if you are calling
exit() from *anywhere* in the program, you should restrict the
exit value to 0 or one of the two status macros.

"Harald van D?k" gmail.com> wrote in > Are you asking if it's okay
to return -1 in such cases as calling

No no. Not in this case. Of course return as you specified is correct I
understand. I mean to simply exit with say and error.

if ( argc != 5)
{ fprintf(stderr,"error\n");
return -1; /* exit(-1) is wrong I guess the proper return would be */
exit(EXIT_FAILURE);
}

Bill

Bill Cunningham wrote:

Obviously returning -1 from ANY function (including main)
is portable and well defined by the language.

Now, returning -1 from main could be interpreted by the OS
(when there is one) in different ways and could be non
portable in the sense that it could mean different things in
different OSes.

In article <79oWj.7860$Uz2.2677@trnddc06>,
Bill Cunningham nspam.com> wrote:

Yes of course. You can return any int from a function declared as
returning an int.

There's no problem returning -1 from main() either, as far as the C
program is concerned. All that's undefined is how the "host
environment" - the shell or operating system or parent program -
interprets it. 0 (or EXIT_SUCCESS) indicates success. EXIT_FAILURE
indicates failure. What anything else means depends on your system.

Most of my programs return 0, 1, or sometimes a larger value, which
can be interpreted reasonably in the unix environments I intend them
for. But you can perfectly well run them in other environments; you
just have to ensure that you run them in such a way that the return
value is not misinterpreted. I suppose it's possible that somewhere
there's an operating system that always shuts down completely if any
C program calls exit(1), but the solution to that is to get a different
operating system.