Limit the scope of a define?

This is a discussion on Limit the scope of a define? within the C++ Programming forums, part of the General Programming Boards category; I am currently working with some pstat functions that require me to us the -D_PSTAT64 compile option. This would be ...

  1. #1
    Registered User deadpoet's Avatar
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    Question Limit the scope of a define?

    I am currently working with some pstat functions that require me to us the -D_PSTAT64 compile option. This would be fine except that it causes other pstat functions to report incorrectly. How do I limit the scope of such a statement. My first hunch is to not use the compiler flag and do something like the following:

    Code:
    int main ( void ) {
      // setup code as needed ...
    
    #ifndef( _PSTAT64 )
    #define _PSTAT64
       // what ever needs to be done in this space....
    #endif
    
    // What ever needs to be done out of the _PSTAT64 space...
    
      return( EXIT_SUCCESS );
    }
    However, when trying to use the pstat structure that is required to have _PSTAT64 defined the compiler tells me that "the type-specifier-list contains an incomplete class ."

    Now if I remove the manually created define for _PSTAT64 and use the compiler flag -D_PSTAT64 the code compiles but it causes other pstat functions to report incorrectly.

    Can someone tell me what I am doing wrong?

    As always, I give great thanks to all those who reply.

    Sincerely,

    DeadPoet

  2. #2
    Registered User major_small's Avatar
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  3. #3
    Yes, my avatar is stolen anonytmouse's Avatar
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    The symbol must be defined before you #include the header, not when you use the code.

    Therefore, within a file there is generally no way to have some code that "uses" the symbol and some that does not.

    However, you can #define a symbol before #including the header in some files and not others.

    file1:
    Code:
    #define _PSTAT64
    #include <pstat.h>
    
    // _PSTAT64 space
    file2:
    Code:
    #include <pstat.h>
    
    // non _PSTAT64 space
    Of course if you then pass data types that are altered on the basis of _PSTAT64 between files you will run into trouble.

  4. #4
    Registered User deadpoet's Avatar
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    Thanks to everyone.

    DeadPoet

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