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From: markb@sdcrdcf.UUCP (Mark Biggar)
Newsgroups: comp.lang.c
Subject: Re: Questions on X3J11 draft
Message-ID: <3508@sdcrdcf.UUCP>
Date: Mon, 8-Dec-86 18:04:05 EST
Article-I.D.: sdcrdcf.3508
Posted: Mon Dec  8 18:04:05 1986
Date-Received: Tue, 9-Dec-86 02:58:13 EST
References: <351@danews.ATT.COM> <7373@utzoo.UUCP> <3800@watmath.UUCP> <775@axis.UUCP>
Reply-To: markb@sdcrdcf.UUCP (Mark Biggar)
Organization: System Development Corporation R&D, Santa Monica
Lines: 26
Keywords: C,X3J11

In article <775@axis.UUCP> philip@axis.UUCP (Philip Peake) writes:
>In article <3800@watmath.UUCP> rbutterworth@watmath.UUCP writes:
>>I can think of a perfectly conforming ANSI compiler that will break
>>almost any existing C code.  Imagine a piece of code such as the following:
>>    #include <stdio.h>
>>    {
>>        extern int getchar();
>>        auto int c;
>>        c=getchar();
>>At the moment, this will blow up on (all?) existing C compilers since
>>"getchar" is a macro.  Of course everyone KNOWS this and so never puts
>>such things into their code.  But under ANSI, almost any function can
>>be defined as a macro in the header files.  That means that almost
>>any program that contains an "extern type libCfunc();" in it can
>>potentially break under a conforming ANSI compiler.
>How can I know, when trying to write portable code, if the 'library'
>function I am going to use is a real function or a macro ?

Easy, you say (using the above example):

#ifndef getchar
extern int getchar();
#endif

Mark Biggar
{allegra,burdvax,cbosgd,hplabs,ihnp4,akgua,sdcsvax}!sdcrdcf!markb