use strict;
use warnings;
use Scalar::Util qw(looks_like_number);

my $c="11111111111111111e11111111111111111";
my $d="22222222222222222e22222222222222222";

if (looks_like_number($c) and 
    looks_like_number($d) and 
    $c == $d) {
  print "$c = $d\n";
}