#!usr/bin/perl -w
use strict;
use constant LEN => 3;
use Benchmark qw(:all);

my $str;
my $count = -2;

my $re = timethese(
    $count,
    {
    substring => sub {

        my $offset = 0;
        my $length = LEN;

        while ( $_ = substr $ARGV[0], $offset, $length ) {
            last if length != LEN;
            $str .= $_ . $/;
            $offset += $length;
        }
    },

    regex => sub {

        $str .= $1 . $/ while ( $ARGV[0] =~ m/(.{3})/g );
    }
  }
);

cmpthese($re);