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Re: Using sizeof in the preprocessor

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On 2011-05-21 09:35:53 -0400, Johannes Schaub said:

> I have this code in my pet project
> 
>     #if sizeof -1 > 4
>     #error "This doesn't work on 64bit"
>     #endif
> 
> My friend was telling me that this shouldn't work because "sizeof is not
> evaluated in the preprocessor". Yet the compiler accepts it and my program
> works.
> 
> Can anybody please explain this? Is it a compiler bug? Thanks to all!

Bug or extension. The preprocessor does text manipulation; it doesn't 
know anything about types (although it has its own set of rules for 
arithmetic).

-- 
  Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The 
Standard C++ Library Extensions: a Tutorial and Reference 
(www.petebecker.com/tr1book)

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Thread

Using sizeof in the preprocessor Johannes Schaub <schaub.johannes@googlemail.com> - 2011-05-21 15:35 +0200
  Re: Using sizeof in the preprocessor Pete Becker <pete@versatilecoding.com> - 2011-05-21 09:42 -0400
  Re: Using sizeof in the preprocessor Huibert Bol <huibert.bol@quicknet.nl> - 2011-05-21 16:08 +0200
    Re: Using sizeof in the preprocessor Pete Becker <pete@versatilecoding.com> - 2011-05-21 10:37 -0400
    Re: Using sizeof in the preprocessor Juha Nieminen <nospam@thanks.invalid> - 2011-05-21 18:51 +0000
      Re: Using sizeof in the preprocessor Huibert Bol <huibert.bol@quicknet.nl> - 2011-05-21 21:52 +0200
      Re: Using sizeof in the preprocessor Johannes Schaub <schaub.johannes@googlemail.com> - 2011-05-21 21:54 +0200
      Re: Using sizeof in the preprocessor Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-05-21 21:54 +0200
        Re: Using sizeof in the preprocessor Juha Nieminen <nospam@thanks.invalid> - 2011-05-22 06:02 +0000
  Re: Using sizeof in the preprocessor Johannes Schaub <schaub.johannes@googlemail.com> - 2011-05-21 22:19 +0200

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