On Mon, 11 May 2009, Bob Beers wrote:
> On Mon, May 11, 2009 at 5:00 PM, RT Mistler <rtmistler@xxxxxxxxxx> wrote:
> > Hi,
> >
> > I've been looking at some kernel modules trying to map an embedded
> > devices resources and while going through a driver, I encountered an
> > "if" test that employed "!!", example:
> >
> > if !!function_foo(args) {
> > ...
> > }
> >
> > What does the "!!" do? (I'm familiar with a single "!")
>
> IIANM, it does "!" and then does "!" again, forcing boolean value,
> true or false.
it's not clear why that would make any difference since 0 is boolean
false and everything else is boolean true. so under what
circumstances would doing a double negation change execution
behaviour? or am i missing something?
rday
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Robert P. J. Day Waterloo, Ontario, CANADA
Linux Consulting, Training and Annoying Kernel Pedantry.
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