（进阶篇）PHP生成唯一会员卡号

class Code { 
    //密码字典 
    private $dic = array( 
        0=>'0',    1=>'1', 2=>'2', 3=>'3', 4=>'4', 5=>'5', 6=>'6', 7=>'7', 8=>'8',     
        9=>'9', 10=>'A',  11=>'B', 12=>'C', 13=>'D', 14=>'E', 15=>'F',  16=>'G',  17=>'H',     
        18=>'I',19=>'J',  20=>'K', 21=>'L',  22=>'M',  23=>'N', 24=>'O', 25=>'P', 26=>'Q',     
    27=>'R',28=>'S',  29=>'T',  30=>'U', 31=>'V',  32=>'W',  33=>'X', 34=>'Y', 35=>'Z' 
    ); 
 
 
    public function encodeID($int, $format=8) { 
        $dics = $this->dic; 
        $dnum = 36; //进制数 
        $arr = array (); 
        $loop = true; 
        while ($loop) { 
            $arr[] = $dics[bcmod($int, $dnum)]; 
            $int = bcdiv($int, $dnum, 0); 
            if ($int == '0') { 
                $loop = false; 
            } 
        } 
        if (count($arr) < $format) 
            $arr = array_pad($arr, $format, $dics[0]); 
 
        return implode('', array_reverse($arr)); 
    } 
 
    public function decodeID($ids) { 
        $dics = $this->dic; 
        $dnum = 36; //进制数 
        //键值交换 
        $dedic = array_flip($dics); 
        //去零 
        $id = ltrim($ids, $dics[0]); 
        //反转 
        $id = strrev($id); 
        $v = 0; 
        for ($i = 0, $j = strlen($id); $i < $j; $i++) { 
            $v = bcadd(bcmul($dedic[$id { 
                $i } 
            ], bcpow($dnum, $i, 0), 0), $v, 0); 
        } 
        return $v; 
    } 
 
}

$code = new Code(); 
$card_no = $code->encodeID(888888,5);

$card_pre = '755'; 
$card_vc = substr(md5($card_pre.$card_no),0,2); 
$card_vc = strtoupper($card_vc); 
echo $card_pre.$card_no.$card_vc;