Ben Wu writes: > Dear All： > 1> I found some placeuse two "!!", what's means > if(button->gpio != INVALID_GPIO) > state = !!((gpio_get_value(button->gpio) ? 1 : 0) ^ button->active_low); > else > state = !!button->adc_state;
if a = 1010011 then !a = 0 and !!a = 1 if a = 000000 then !a = 1 !! = 0 basically it means if a is non-zero then make a = exactly 1, else leave it at zero. > 2> is there some MSN group to study linux kernel or discuss it ? don't know, but it would be ironic. > Thanks and Best Regards > > Ben Wu > > MSN:[email protected] > > _______________________________________________ > Kernelnewbies mailing list > [email protected] > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies _______________________________________________ Kernelnewbies mailing list [email protected] http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
