How to make a #define global

This is a discussion on How to make a #define global within the C++ Programming forums, part of the General Programming Boards category; Ok i have a problem, I want to do some conditional compilation using some #define's but I have to do ...

  1. #1
    Registered User xds4lx's Avatar
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    How to make a #define global

    Ok i have a problem, I want to do some conditional compilation using some #define's but I have to do them in every file that uses this conditional compiling and its anoying, even if i put it into a header file and then include that header somewhere else the #define is not recognized in the other file, ex:

    Code:
    //file Test1.h
    #define USERDEF 1
    
    //file Test2.h
    #include"Test1.h"
    
    int SomeFunc()
    {#ifdef USERDEF
     // code here
     #elif !defined USERDEF
     // other code here
     return(something);
    }
    When I try this MSVC keeps complaining about USERDEF being undefined and this i really dont want to have to do the #define in all the files that use the conditional compilation, any way around this b/c im pretty new to messing w/ the preprocessor.
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  2. #2
    Code Goddess Prelude's Avatar
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    A #define is global to all files that include the header or include headers that include the header. Double check your spelling, the problem is probably a syntax error somewhere.

    -Prelude
    My best code is written with the delete key.

  3. #3
    Ted
    Ted is offline
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    Review the article under: file scope, regarding scope and visibility in the MSDN lirary. It's online at microsoft. Or you could just get a programming text book and read up about it. Otherwise, you must incude it in every file that defines your constants and functions.

  4. #4
    Registered User xds4lx's Avatar
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    Well its not a spelling error lol, first i just typed it in the second file and it said that so then i was like ok and did a copy and paste and it still says USERDEF is still underfined. So is the only way to define this in every header that uses this? Ive changed this to using constants but now its not conditional compilation so instead it has to pick the correct method at runtime which is something i wanted to avoid but oh well, thanx for the help anyways guys.
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  5. #5
    TheG3
    Guest

    space maybe?

    Code:
    #include"Test1.h"
    
    #include "Test1.h"
    Missing space maybe? Not sure on syntax on that though...

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