Re: [PLUG] #define for 32 vs 64 bit C program?

[John Ashmead <john.ashmead@ashmeadsoftware.com>]

I'm not aware of such a directive, but would "sizeof(int)" work? Worst 
case, there is "sizeof(i)".

On Apr 26, 2004, at 4:43 PM, Walt Mankowski wrote:

> I have a C app that was developed on a 32 bit Linux box, and I'm
> trying to get it to compile cleanly on a 64 bit opteron.  Does anyone
> know of a gcc preprocessor directive that will tell whether a source
> file is being compiled for 32 or 64 bits?
>
> For example, I'd like to do something like this:
>
> #include <stdio.h>
>
> int main () {
>         long i = 42;
> #ifdef __32_BITS__
>         printf("i = %d\n", i);
> #else
>         printf("i = %ld\n", i);
> #endif
>         return 0;
> }
>
> But I'm pretty sure that "__32_BITS__" isn't the right directive.
> Does anyone know what the recommended way to do this is?
>
> Thanks.
>
> Walt


John Ashmead
Ashmead Software & Consulting, Inc.
139 Montrose Avenue
Rosemont, PA 19010-1508
(610) 527 9560
fax (610) 527 4640
john.ashmead@ashmeadsoftware.com
http://www.ashmeadsoftware.com/

___________________________________________________________________________
Philadelphia Linux Users Group         --        http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion  --   http://lists.phillylinux.org/mailman/listinfo/plug