use strict;
use warnings;

use Inline C => Config =>
 BUILD_NOISY => 1,
 ;

use Inline C => <<'EOC';

double nxtafter(double in, double dir) {
  return nextafter(in, dir);
}

EOC

my $pos_inf = (99 ** 99) ** 99;
my $neg_inf = -$pos_inf;

my $next_down = nxtafter(1.9041105342991877e+258, $neg_inf);

printf "%.16e\n", $next_down;

my $next_up = nxtafter(-8.2727285363069939e-293, $pos_inf);

printf "%.16e\n", $next_up;

__END__
Outputs:
1.9041105342991875e+258
-8.2727285363069927e-293

##</code><code>##

1.9041105342991884e+258
-7.9999999999999937e-293