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NNTP-Posting-Date: Sat, 11 Jun 2011 12:56:27 -0500
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Date: Sat, 11 Jun 2011 13:56:31 -0400
From: pete <pfiland@mindspring.com>
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Subject: Re: a doubt about c
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.c:5846

Shao Miller wrote:
> 
> On 6/11/2011 8:11 AM, Ya Shou wrote:
> >...
> > I read some open source c program code, found a problem that let me doubt.
> > All those programs are using macros to define constants, and did not use an enum to achieve, but I think in the enumeration constants is very convenient.
> > Enumeration defines constants used in c++, but not seen any in c, why?
> > ...
> 
> If you mean "integer constant expressions," I prefer to use 'enum's in C
> wherever possible.
> 
> If an integer constant expression needs to be used as part of an '#if'
> pre-processing directive, then I will '#define' and use a macro whose
> definition will not contain any identifiers (except other macros) or
> keywords.
> 
>    #define ALL_ONES_CHAR ((1 << CHAR_BIT) - 1)

That's undefined if sizeof (int) equals one.

-- 
pete