Select Code to Download

for my $i (0 .. length($str1)) {
    if (substr($str1, $i, 1) ne substr($str2, $i, 1)) {
        $val++;
    }
}

my $step = 5;
my $bound = int (length($str1) / $step);

...
        $val++;
    }
}

for my $i (0 .. $bound) {
    my $substr1 = substr($str1, ($i * $step), $step);
    my $substr2 = substr($str2, ($i * $step), $step);
...
        }
    }
}