Question

I’ve been attempting to make a folder for each architecture my code can support. In this folder are platform specific files to include. I include them as follows:

#define STR(x) #x
#define ASSTR(x) STR(x)

#include ASSTR(ARCHITECTURE/sizes.h)

My compilation line in make looks like this:

gcc -o $@ -c $< -DARCHITECTURE=i386

Which works, until I define ARCHITECTURE to be i386. When this happens, it looks for 1/sizes.h, so I assume it’s already defined somewhere.

Answer 1

I believe the C preprocessor (cpp), which is called by gcc, defines i386 (for i386 systems). You can find out what it defines like so:

touch foo.h; cpp -dM foo.h; rm foo.h

This method is described by the cpp man page, under -d, with the character M (so, -dM):

Instead of the normal output, generate a list of #define directives for all the macros defined during the execution of the preprocessor, including predefined macros. This gives you a way of finding out what is predefined in your version of the preprocessor. Assuming you have no file foo.h, the command

    touch foo.h; cpp -dM foo.h

will show all the predefined macros.