Re: Weird result for modulus operation

[Ang Way Chuang <wcang at nav6 dot org>]

Ang Way Chuang wrote:
> Andrew Pinski wrote:
> > On Tue, Apr 29, 2008 at 9:08 PM, Ang Way Chuang <wcang@nav6.org> wrote:
> > >  Thanks for the speedy reply. But why this code:
> > >
> > >         int a = 17, b = 16;
> > >         a = a++ % 16;
> > >
> > >  results in a = 2 then? I think I need to know what is sequence 
> > > point. I'll
> > > google that.
> >
> > As I mentioned, the code is undefined so it could be any value.
>
> Is there any flag in gcc that can provide warning to code that relies on 
> undefined behaviours?

Found it. -Wsequence-point which is enabled by -Wall. But gcc didn't 
fart out any warning with -Wall or -Wsequence-point flag :(

> > Thanks,
> > Andrew Pinski