Platform Preprocessor Definitions

[John E]

Using VS2005 I'm building a source library that was originally written to be compiled using gcc. A couple of modules have code that looks like this:-

#if defined(__i386__) || defined(__x86_64__)
    // Do something
#elif defined(__powerpc__)
    // Do something else
#elif defined(__alpha__)
    // Do something else
#elif defined(__mips__)
    // etc, etc
#endif

For most of the above I wouldn't expect them to be recognised by VC++ because it can't cross-compile for powerpc, mips alpha or whatever. However, VC++ doesn't even recognise __i386__ or __x86_64__

Are there any equivalent identifiers that VC++ will recognise?

[ninja9578]

GCC doesn't have built in macros for those either, you have to define them in the project file. Certain IDEs will automatically define those for you when it creates the project. I'm pretty sure XCode does, which is what I assume you were using by the __powerpc__ macro. I think the Visual C++ argument is the same as GCC -D __x86_64__

[John E]

Are you sure about that? I always thought that definitions beginning with a double underscore (__mips__ / __alpha__ / __powerpc__ etc) were somehow predetermined by the compiler. In fact I'm pretty sure they are, although I don't know how.

[ninja9578]

Huh, I guess I was wrong, it is predetermined by the compiler. But it's not standard, it's predetermined by the GCC compiler. GCC does this, MinGW doesn't (I just tested it), so I would assume VC++ doesn't either. It shouldn't be hard to define though in your project. I'm not sure where you define the global definitions, but I know there is a way to do it.

[Codeplug]

http://predef.sourceforge.net/prearch.html
http://msdn.microsoft.com/en-us/library/b0084kay.aspx

gg