生成随机数

/** *生成随机数 *@param */function randStr($m = 5) {    $new_str = '';    $str = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwsyz0123456789';    for ($i = 1; $i <= $m; ++$i) {        $new_str .=$str[mt_rand(0, 61)];    }    return $new_str;}//测试$str = randStr(6);echo $str;