class NumberEncode
{

    private $strbase = "Flpvf70CsakVjqgeWUPXQxSyJizmNH6B1u3b8cAEKwTd54nRtZOMDhoG2YLrI";

    private $key, $length, $codelen, $codenums, $codeext;

    function __construct($length = 9, $key = 2543.5415412812)
    {

        $this->key = $key;

        $this->length = $length;

        $this->codelen = substr($this->strbase, 0, $this->length);

        $this->codenums = substr($this->strbase, $this->length, 10);

        $this->codeext = substr($this->strbase, $this->length + 10);

    }


    public function encode($nums)
    {

        $rtn = "";

        $numslen = strlen($nums);

        //密文第一位标记数字的长度

        $begin = substr($this->codelen, $numslen - 1, 1);

        //密文的扩展位

        $extlen = $this->length - $numslen - 1;

        $temp = str_replace('.', '', $nums / $this->key);

        $temp = substr($temp, -$extlen);


        $arrextTemp = str_split($this->codeext);

        $arrext = str_split($temp);

        foreach ($arrext as $v) {

            $rtn .= $arrextTemp[ $v ];

        }


        $arrnumsTemp = str_split($this->codenums);

        $arrnums = str_split($nums);

        foreach ($arrnums as $v) {

            $rtn .= $arrnumsTemp[ $v ];

        }

        return $begin . $rtn;

    }


    public function decode($code)
    {


        $begin = substr($code, 0, 1);

        $rtn = '';

        $len = strpos($this->codelen, $begin);

        if ($len !== false) {

            $len++;

            $arrnums = str_split(substr($code, -$len));

            foreach ($arrnums as $v) {

                $rtn .= strpos($this->codenums, $v);

            }

        }

        return $rtn;

    }

}