Xref: utzoo comp.unix.questions:12938 comp.std.c:1045
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.unix.questions,comp.std.c
Subject: Re: How can I find out cc or cpp symbols?
Keywords: cpp, cc, macros
Message-ID: <10084@smoke.BRL.MIL>
Date: 21 Apr 89 01:23:58 GMT
References: <1954@trantor.harris-atd.com>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 13

In article <1954@trantor.harris-atd.com> bbadger@x102c.harris-atd.com (Bernie Badger Jr.) writes:
>Is there a way to find out what macros are defined?  It's particularly hard 
>to predict which names will be _predefined_.  ...

This is not an issue for Standard C, since the only predefined macros
allowed are those specified in the Standard and optionally additional
implementation-specific ones that must have names starting with _.
If you do not use _-names in your application code, it will be impervious
to predefined vendor macros in any Standard conforming implementation;
thus why would you care what they were?

The particular set of predefined vendor macros may very well depend on
the options supplied to the compiler when it is invoked.