use strict;
use warnings;

use Test::More tests => 1;

my @arrayUnsorted = ('page1.html', 'page11.html', 'page2.html', 'page3.html');
my @arraySorted   = ('page1.html', 'page2.html', 'page3.html', 'page11.html');

my @have = sort { substr ($a, 4, 2) <=> substr ($b, 4, 2) } @arrayUnsorted;
is_deeply \@have, \@arraySorted;