alphanumeric_increment.pl

sub alphanumeric_increment {
    my $string = "" . shift;
    my $position = @_ ? shift : -1;

    if ($position == -1) {
        $position = (length $string) - 1;
    }

    my $increment_str = substr $string, $position, 1;


    if ($increment_str eq '9') {
        substr $string, $position, 1, 'a';
    } elsif ($increment_str eq 'z') {
        substr $string, $position, 1, 'A';
    } elsif ($increment_str eq 'Z') {
        if ($position == 0) {
            substr $string, $position, 1, '0';
            $string .= '0';
        } else {
            my $inc_position = $position - 1;
            $string = alphanumeric_increment($string, $inc_position);
            substr $string, $position, 1, '0';
        }
    } else {
        $increment_str++;
        substr $string, $position, 1, "".$increment_str;
    }

    return $string;
}