On Wed, Nov 24, 2010 at 12:18:16PM -0600, Pat Kane wrote: > What the deal with the "!!" operator? I read it as a double logical negation. > A NOOP, does it have some useful side effect?
http://stackoverflow.com/questions/1406604/what-does-the-operator-double-exclamation-point-mean-in-javascript is the first link I found. yes, I used to think it was dirty too, but I've grown to like it. Cheers, Peter > > On Wed, Nov 24, 2010 at 10:30 AM, walter harms <[email protected]> wrote: > > > > > > Am 24.11.2010 07:25, schrieb Keith Packard: > >> On Wed, 24 Nov 2010 14:40:11 +1000, Peter Hutterer > >> <[email protected]> wrote: > >> > >>> -#define BitIsOn(ptr, bit) (((BYTE *) (ptr))[(bit)>>3] & (1 << ((bit) & > >>> 7))) > >>> +#define BitIsOn(ptr, bit) !!(((BYTE *) (ptr))[(bit)>>3] & (1 << ((bit) & > >>> 7))) > >> > > > > bit is checked to be less than 8 with "(bit) & 7" but only in the second > > statement. > > the linux kernel specifies them as inline code. maybe this is the way to go > > here also. > > > > re, > > wh _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
