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From: karl@haddock.ISC.COM (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: Does ANSI C have lengthof() ?
Message-ID: <1059@haddock.ISC.COM>
Date: Fri, 4-Sep-87 17:34:10 EDT
Article-I.D.: haddock.1059
Posted: Fri Sep  4 17:34:10 1987
Date-Received: Sat, 5-Sep-87 20:47:26 EDT
References: <9154@brl-adm.ARPA> <1265@mhres.mh.nl>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 20

In article <1265@mhres.mh.nl> jv@mhres.mh.nl (Johan Vromans) writes:
>I think there is more need for these functions in the pre-processor:
>    # if sizeof (char*) == sizeof (int)

I've often wanted this sort of thing myself, but have grudgingly had to accept
the fact that a preprocessor that only examines "#" lines cannot possibly
understand "sizeof(time_t)".

But, ignoring for the moment the question of whether it's "good" that the
preprocessor doesn't know C, this enhancement shouldn't require all that much
"spurious knowledge", should it?  In particular, couldn't one write a cpp that
recognizes "typedef" declarations?  Such a preprocessor ought to be able to
handle any "sizeof(TYPE)" expression, and I'd be willing to do without
"sizeof(EXPR)".

Has anyone tried to write such a preprocessor?  Or is the problem more subtle
than this?  (Restricted-scope typedefs complicate things, but not much; and
nobody uses them, anyway.)

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint