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The or operator and the preprocessor?

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  The or operator and the preprocessor? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-02-13 02:08 +0000
    Re: The or operator and the preprocessor? Ian Collins <ian-news@hotmail.com> - 2012-02-13 15:59 +1300
      Re: The or operator and the preprocessor? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-02-13 05:32 +0000
        Re: The or operator and the preprocessor? Ian Collins <ian-news@hotmail.com> - 2012-02-13 20:27 +1300

#13957 — The or operator and the preprocessor?

error: "or" cannot be used as a macro name as it is an operator in C++

In C, the preprocessor does what its name says, and occurs before
the compiler sees tokens and reserved words.

Is that not true in C++?

extern "C" {
#include <stdio.h>
#define or "hi there!\n"
   int main() {
      printf( or );
   }
}

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#13958

On 02/13/12 03:08 PM, glen herrmannsfeldt wrote:
> error: "or" cannot be used as a macro name as it is an operator in C++
>
> In C, the preprocessor does what its name says, and occurs before
> the compiler sees tokens and reserved words.
>
> Is that not true in C++?
>
> extern "C" {
> #include<stdio.h>
> #define or "hi there!\n"
>     int main() {
>        printf( or );
>     }
> }

The error is valid, "or" is the alternative token for "||" in C++. 
Redefining it is a bad idea.

-- 
Ian Collins

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#13960

Ian Collins <ian-news@hotmail.com> wrote:

(snip, I wrote)

>> error: "or" cannot be used as a macro name as it is an operator in C++

(snip)

> The error is valid, "or" is the alternative token for "||" in C++. 

Oh, so also valid in preprocessor statements? 

So might cause problems similar to:

#define x define

#x y 1

> Redefining it is a bad idea.

Well, that is probably true of all the language keywords.
In most cases, though, it should't cause problems if you don't
use the keyword.

-- glen

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#13961

On 02/13/12 06:32 PM, glen herrmannsfeldt wrote:
> Ian Collins<ian-news@hotmail.com>  wrote:
>
> (snip, I wrote)
>
>>> error: "or" cannot be used as a macro name as it is an operator in C++
>
> (snip)
>
>> The error is valid, "or" is the alternative token for "||" in C++.
>
> Oh, so also valid in preprocessor statements?
>
> So might cause problems similar to:
>
> #define x define
>
> #x y 1
>
>> Redefining it is a bad idea.
>
> Well, that is probably true of all the language keywords.

"or" is an operator, not a keyword.

-- 
Ian Collins

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