Re: gcc version 2.95.3 20010315 (release/MontaVista) cross compiler

[Guy Streeter <streeter@redhat.com>]

On Wed, 2003-12-17 at 17:02, David C. Chiu wrote:
> We're experiencing some unexpected behavior with binary generated with
> the said version of gcc; namely that variables declared to char appear
> to be defaulting to unsigned char.
>
> #include <stdio.h>
> #include <stdlib.h>
>
> int main( int argc, char** args, char** envs )
> {
>         char sc;
>         unsigned char uc;
>
>         sc = uc = -3;
>
>         printf( "signed char: %d unsigned char: %d\n", sc, uc );
>         if ( sc > (char)0 )
>                 printf( "sc is greater than zero\n" );
>         else
>                 printf( "sc is less or equal to zero\n" );
>
>         return 0;
> }
>
> The preceeding code would produce the following unexpected result --
>
> signed char: 253 unsigned char: 253
> sc is greater than zero
>
> Making the following change --
>
>         signed char sc;
>         unsigned char uc;
> 	.
> 	.
>
> Would produce the expected result --
>
> signed char: -3 unsigned char: 253
> sc is less or equal to zero
>
> Can someone shed some light on this? (As in, is this "normal" and we do
> not know only because we've been living under a rock ;-)

This behavior is indeed "normal". For some reason (compatibility with
AIX, I think) the gcc compiler for ppc has always made char unsigned by
default.
Try adding the -fsigned-char option to you gcc command line.

--Guy


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