Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!bu-cs!purdue!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.std.c
Subject: Re: What is the domain of strerror()?
Message-ID: <9997@smoke.BRL.MIL>
Date: 6 Apr 89 22:10:56 GMT
References: <1249@microsoft.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 13

In article <1249@microsoft.UUCP> w-colinp@microsoft.uucp (Colin Plumb) writes:
>It says that strerror() maps the error number passed to it to an error
>string, but I can't find any description of what a valid error number is.

That's easy; anything the standard says is an error number is allowed,
and anything else is up to the implementation.  I.e. the non-zero value
of errno, as set by some functions according to the standard, is an
acceptable "error number" for strerror().  Presumably any other non-zero
value that the implementation assigns to arrno is also acceptable to
strerror().

The Rationale refers you to perror(), 4.9.10.4, where this connection
is clearer.