Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uflorida!haven!ncifcrf!nlm-mcs!adm!smoke!gwyn
From: gwyn@smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: How big is the argv[] array?
Message-ID: <8631@smoke.ARPA>
Date: 5 Oct 88 05:01:56 GMT
References: <1239500004@osiris.cso.uiuc.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 15

In article <1239500004@osiris.cso.uiuc.edu> hood@osiris.cso.uiuc.edu writes:
>How big is the argv[] array?  Or to ask it another way, how safe is it to
>go past the argc-1'th element in the argv[] array?

What puzzles me is the line of reasoning you would use to conclude
that accessing nonexistent data could ever be safe.

argv[argc] is supposed to be a null pointer, and as you note you
can test for that instead of using a counter.  (However, getopt()
works best with the counter approach.)  Some older systems did
not have a null pointer in argv[argc], however.  I don't think
you're likely to encounter any such systems today.

argv[argc+1] is simply undefined.  Any use of it would be at your
own risk; in other words: don't do it.