PHP取亂數方法

第一種

function random_number2($length) {
    $key = '';
    $pattern = "123456789ABCDEFGHIJKLMNPQRSTUVWXYZ";
    for ($i = 0; $i < $length; $i++) {
        $key .= $pattern{rand(0, 33)};
    }
    return $key;
}

第二種(推薦)

uniqid(prefix, more_entropy)是基於微秒計的當前時間而生成一個唯一ID，

預設返回字串有13個字串長，如果more_entropy為true則有23個字串長。

substr(md5(uniqid(rand(),true)),0 , 15)

第三種

class Code
{
    //密碼字典
    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; //進位制數
        $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; //進位制數
        //鍵值交換
        $dedic = array_flip($dics);
        //去零
        $id = ltrim($ids, $dics[0]);
        //反轉
        $id = strrev($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(time());

$card_pre = '8016';
$card_vc = substr(md5($card_pre . $card_no), 0, 7);
$card_vc = strtoupper($card_vc);
$card_no = $card_vc . $card_no;

echo $card_no;
exit;