RE: Slowness in bignum mode ( gmp | gawk -M ) when doubling extremely large inputs

[pjfarley3]

> -----Original Message-----
> From: arnold@skeeve.com <arnold@skeeve.com>
> Sent: Friday, January 28, 2022 3:46 AM
> To: pjfarley3@earthlink.net; bug-gawk@gnu.org
> Cc: jasonckwan@yahoo.com
> Subject: Re: Slowness in bignum mode ( gmp | gawk -M ) when doubling
> extremely large inputs
> 
> <pjfarley3@earthlink.net> wrote:
> 
> > There are also several strange uses of the exclamation point operator
> > (!) that I do not understand, but that is probably just my lack of
> > experience.  Examples of such use are:
> >
> > _n1-!!_n1
> > -!-""
> > !+""
> > !--_n10
> >
> > I THINK these are intended to be uses of the negation operator, but I
> > don’t understand what that operation is supposed to do to an empty
> > string.
> 
> Using ! converts non-zero to zero and zero to one, depending on the value of
> the expression to which it is applied.
> 
>       !! <something>
> 
> converts <something> into a canonical truth value of 1 or 0. This can
> occasionally be useful in C / C++ as well:
> 
>       const char *truth_value[] = { "false", "true" };
> 
>       printf("xyzzy is %s\n", truth_value[!! (some_expression)]);
> 
> Arnold

Thanks for the enlightenment Arnold.

So if I understand your explanation correctly,  the phrase -!!-"" translates to 
this sequence of operations:

1.      -""     Minus the empty string, becomes -0 which is still just zero
2.      !0      Not 0 becomes 1
3.      !1      Not 1 becomes zero
4.      -0      Minus 0 which is still just 0

So if I am understanding correctly, the phrase -!!-"" is just a convoluted way 
to say "zero"?

Peter