use strict;
use warnings;
use Devel::Peek;

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

use Inline C => <<'EOC';

SV * foo(SV * arg) {
  SV * keysv;

  keysv = NEWSV(0, 32);

  /* Make sure arg is an NV */
  if(!SvNOK(arg)) croak("Not a valid arg passed to foo for this demo");

  sv_setpvf(keysv, "%.19" NVgf, SvNV(arg));

  return keysv;
}

SV * bar(SV * arg) {
  SV * keysv;
  char buff[30];

  keysv = NEWSV(0, 32);

  /* Make sure arg is an NV */
  if(!SvNOK(arg)) croak("Not a valid arg  passed to bar for this demo");

  sprintf(buff, "%.19" NVgf, SvNV(arg));
  sv_setpvf(keysv, "%s", buff);

  return keysv;
}

EOC

my $sv_foo = foo(2 ** 63);
my $sv_bar = bar(2 ** 63);

Dump $sv_foo;
print "#####################\n";
Dump $sv_bar;