private function specialChar($char)
    {
        switch($char) {
            case "!":
                return $this->hexToChar('00A1');
            case "_":
                return $this->hexToChar('203E');
            case "&":
                return $this->hexToChar('214B');
            case "?":
                return $this->hexToChar('00BF');
            case ".":
                return $this->hexToChar('U2D9');
            case "\"":
                return $this->hexToChar('201E');
            case "'":
                return $this->hexToChar('002C');
            case "(":
                return $this->hexToChar('0029');
            case ")":
                return $this->hexToChar('0028');
            default:
                return $char;
        }

    }