Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #11056

Re: macro with the same name in translation unit

Show all headers | View raw

On 09/28/2011 12:22 PM, Keith Thompson wrote:
> James Kuyper <jameskuyper@verizon.net> writes:
> [...]
>> The following two alternatives don't violate that constraint, and have
>> behavior corresponding to the two "obvious ways" I mentioned above:
>>
>> Option 1:
>> #ifdef DUMMY
>> #undef DUMMY
>> #endif
>> #define DUMMY 200
>>
>> Option 2:
>> #ifndef DUMMY
>> #define DUMMY 200
>> #endif
> 
> Option 3:

This is more like Option 1a:

> #undef DUMMY
> #define DUMMY 200
> 
> #undef does nothing if the macro isn't currently defined (though I
> suppose some compilers might issue a warning).

I should have remembered that! I still have fond memories of pointing
out the same issue to Nick Maclauren nearly two decades ago. It was one
of the few times I ever successfully corrected him on any issue.

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

macro with the same name in translation unit "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2011-09-28 10:53 -0400
  Re: macro with the same name in translation unit James Kuyper <jameskuyper@verizon.net> - 2011-09-28 11:41 -0400
    Re: macro with the same name in translation unit Keith Thompson <kst-u@mib.org> - 2011-09-28 09:22 -0700
      Re: macro with the same name in translation unit James Kuyper <jameskuyper@verizon.net> - 2011-09-28 13:16 -0400
        Re: macro with the same name in translation unit Keith Thompson <kst-u@mib.org> - 2011-09-28 13:42 -0700
          Re: macro with the same name in translation unit James Kuyper <jameskuyper@verizon.net> - 2011-09-28 17:18 -0400

csiph-web