[NMLUG] gcc pre-defined macros

[nmlug@swcp.com (Michael Maddex)]

Aaron Birenboim wrote:

>     I remember once apon a time, I found a way to list
> all the pre-defined macros from gcc.  It was like
> several PAGES long.  Things like:  __unix, __linux__,
> i386, __i386, __STDC__, LITTLE_ENDIAN....
>
>    I'm having a devil of a time remembering how I did that.
> And...   I NEED it again.   Could anybody give me hint
> about how to get such a list again?

Are you looking for something like this?  This show the defaults when
gcc is invoked.

 $ echo 'main(){printf("hello world\n");}' | gcc -E -v -
 Reading specs from /usr/lib/gcc-lib/i486-box-linux/2.7.2/specs
 gcc version 2.7.2
  /usr/lib/gcc-lib/i486-box-linux/2.7.2/cpp -lang-c -v -undef
 -D__GNUC__=2 -D__GNUC_MINOR__=7 -D__ELF__ -Dunix -Di386 -Dlinux
 -D__ELF__ -D__unix__ -D__i386__ -D__linux__ -D__unix -D__i386
 -D__linux -Asystem(unix) -Asystem(posix) -Acpu(i386)
 -Amachine(i386) -D__i486__ -

The above pasted from the GCC-HOWTO.

Also I think that

 $ info gcc

will list and describe all of the pre-defines, but that's a large
collection of files and I don't remember exactly where to start looking,
but I believe the list is near the beginning.

Hope that's some help.

--

Michael Maddex                     Instructor, Computer Science
                Northern New Mexico Community College
921 Paseo de Oñate                            Española NM 87531

        Ignorance is not bliss, ignorance is ignorance.


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