Misuse ostringstream.str() ?

[Sai-Jiang]

`void kcp_client::do_recv_udp_packet_in_loop(void)
{

if (ret_recv < 0)
{
    std::ostringstream ostrm;
    std::string err_detail = ostrm.str();
    ostrm << "do_asio_kcp_connect recv error return with errno: " << err << " " << strerror(err);
    std::cerr << err_detail << std::endl;
    return;
}

}`