On Fri, 15 Jun 2007 14:54:20 -0500
"David M. Lloyd" <[EMAIL PROTECTED]> wrote:
> On Fri, 15 Jun 2007 21:47:50 +0200 (CEST)
> Jan Engelhardt <[EMAIL PROTECTED]> wrote:
>
> > On Jun 15 2007 18:56, Vegard Nossum wrote:
> > > bool is_power_of_2(unsigned long n)
> > > {
> > >- return (n != 0 && ((n & (n - 1)) == 0));
> > >+ return n * !(n & (n - 1));
> > > }
> >
> > There is a third way which uses neither * nor &&, but []:
>
> I assume using something GCC-specific is right out?
>
> bool is_power_of_to(unsigned long n)
> {
> return __builtin_ffsl(n) == 1;
Pretend I typed this instead:
bool is_power_of_2(unsigned long n)
{
return __builtin_popcountl(n) == 1;
}
All I can say is, it's really hot here :P
- DML
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