PHP 工具：递归，检查手机号，长度

    /**
     * 递归获取当前id下所有子id
     *
     * @param [type] $party_id
     * @return void
     */
    public function _getPartyIds($party_id)
    {
        $where['parent_id'] = $party_id;
        $ids = '';
        $list = db('party')->where($where)->field('id')->select();

        if ($list) {
            foreach ($list as $item) {
                $ids .= ',' . $item['id'];
                $ids .= $this->_getPartyIds($item['id']);
            }
        }
        return $ids;
    }
    
/**
 * 检查是否超过指定长度

 * 长度返回true
 *
 * @param [type] $str
 * @param integer $length
 * @return void
 */
function check_max_length($str, $length = 10)
{
    $strLength = mb_strlen($str, "utf-8");
    if ($strLength > $length) {
        return true;
    }
    return false;
}

/**
 * 判断是否是手机号
 *
 * @param [type] $str
 * @param integer $length
 * @return boolean
 */
function is_mobile($str)
{
    if (preg_match("/^1[34578]\d{9}$/", $str)) {
        return true;
    } else {
        return false;
    }
}