use strict;
use warnings;
use Config;

use Inline C => Config =>
  USING => 'ParseRegExp',
  CCFLAGSEX => '-DMY_FORMAT="%.16e"',
  BUILD_NOISY => 1,
;

use Inline C =><<'EOC';

SV * foo(void) {
  printf(MY_FORMAT, sqrt(2.0));
  printf("\n");
}

EOC

foo();