From: "Russ Cox" <rsc@swtch.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] PCC - #if
Date: Fri, 4 May 2007 17:57:23 -0400 [thread overview]
Message-ID: <20070504215727.040951E8C47@holo.morphisms.net> (raw)
In-Reply-To: <2af76db8bada74afa8aaf0a3b82635d8@proxima.alt.za>
> So if I have
>
> #undef C
>
> followed by
>
> #if C
>
> is it valid or invalid? Your explanation leaves it unclear (or I
> missed it, somehow).
It is valid. `#if C' macro-expands to `#if C' (no change)
and then all names in #if expressions turn into 0s, so it
is treated as `#if 0'.
Russ
next prev parent reply other threads:[~2007-05-04 21:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-04 20:23 lucio
2007-05-04 21:17 ` Russ Cox
2007-05-04 21:35 ` lucio
2007-05-04 21:56 ` geoff
2007-05-04 21:57 ` Russ Cox [this message]
2007-05-04 20:32 lucio
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