获取随机编码

if (!function_exists('get_random_str')) {

    /**
     * 生成随机字符串
     * @param int $length 生成长度
     * @param int $type 生成类型：0-小写字母+数字，1-小写字母，2-大写字母，3-数字，4-小写+大写字母，5-小写+大写+数字
     * @return string 返回结果
     */
    function get_random_str($length = 8, $type = 0)
    {
        $a = 'abcdefghijklmnopqrstuvwxyz';
        $A = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $n = '0123456789';

        switch ($type) {
            case 1:
                $chars = $a;
                break;
            case 2:
                $chars = $A;
                break;
            case 3:
                $chars = $n;
                break;
            case 4:
                $chars = $a . $A;
                break;
            case 5:
                $chars = $a . $A . $n;
                break;
            default:
                $chars = $a . $n;
        }

        $str = '';
        for ($i = 0; $i < $length; $i++) {
            $str .= $chars[mt_rand(0, strlen($chars) - 1)];
        }
        return $str;
    }

}

if (!function_exists('get_random_code')) {

    /**
     * 获取指定位数的随机码
     * @param int $num 随机码长度
     * @return string 返回字符串
     */
    function get_random_code($num = 12)
    {
        $codeSeeds = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        $codeSeeds .= "abcdefghijklmnopqrstuvwxyz";
        $codeSeeds .= "0123456789_";
        $len = strlen($codeSeeds);
        $code = "";
        for ($i = 0; $i < $num; $i++) {
            $rand = rand(0, $len - 1);
            $code .= $codeSeeds[$rand];
        }
        return $code;
    }
}