Re: C arcana, was type or identifier fundamental parsing issue - Need help from parsing experts

"christian.bau" <christian.bau@cbau.wanadoo.co.uk>
Thu, 12 Jul 2012 09:23:39 -0700 (PDT)

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Related articles
type or identifier fundamental parsing issue - Need help from parsing hsad005@gmail.com (AD) (2012-07-03)
Re: type or identifier fundamental parsing issue - Need help from pars DrDiettrich1@aol.com (Hans-Peter Diettrich) (2012-07-04)
Re: C arcana, was type or identifier fundamental parsing issue - Need christian.bau@cbau.wanadoo.co.uk (christian.bau) (2012-07-12)
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From: "christian.bau" <christian.bau@cbau.wanadoo.co.uk>
Newsgroups: comp.compilers
Date: Thu, 12 Jul 2012 09:23:39 -0700 (PDT)
Organization: Compilers Central
References: 12-07-004 12-07-007
Keywords: C, standards
Posted-Date: 12 Jul 2012 17:51:16 EDT

On Jul 4, 11:43 am, Hans-Peter Diettrich <DrDiettri...@aol.com> wrote:


> There exist pros and cons. The C preprocessor *requires* that sizeof
> is a built-in *macro*, so that it can be used in #if conditions.


Ahem... No, it doesn't. Unless you do something really perverse like


#define sizeof <whatever>


sizeof will not be defined as a macro, and any non-macro identifier
used within #if other than as an operand to "defined" will be replaced
by 0.
[After squinting at the various C standards and checking with
committee members, I found that the C preprocessor does not know
about any keywords at all, so it treats sizeof and int as ordinary
names. This allows occasionaly useful kludges like #define short int
-John]


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