use Benchmark 'cmpthese';
my @a = map {"$_\n"} 1..1000000;
cmpthese(100, {
    forloop => sub {
        open FILE, ">file.out" or die "Can't open file: $!\n";
        print FILE $_ for @a;
        close FILE;
        },
    array   => sub {
        open FILE, ">file.out" or die "Can't open file: $!\n";
        print FILE @a;
        close FILE;
        }
});