Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Atomic #defines (was Re: Password checking program)
Message-ID: <10856@smoke.BRL.MIL>
Date: 28 Aug 89 14:02:49 GMT
References: <15257@duke.cs.duke.edu> <652@lakart.UUCP> <10765@smoke.BRL.MIL> <1625@mcgill-vision.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 20

In article <1625@mcgill-vision.UUCP> mouse@mcgill-vision.UUCP (der Mouse) writes:
>In article <10765@smoke.BRL.MIL>, gwyn@smoke.BRL.MIL (Doug Gwyn) writes:
>> EOF belongs to the C implementation.  Invent your own symbols for
>> your own uses.
>Fine.  But how?

#include <stdio.h>
#define MY_EOF (-1234) /* presumably in some local header */
#define MY_ERR (-4321)
int MyGetChar() { int c;
return (c = getchar()) == EOF ? ferror(stdin) ? MY_ERR : MY_EOF : c; }

>By the way, it seems to me that the required existence of EOF implies
>that it is not a legal implementation choice to make char and int
>identical.  Is this true?

Since in such an implementation an int would be unable to represent
all possible values in the range of a unsigned char, as required by
the specification for some library routines, it would not be standard
conforming.