Get in-water target bins out of target data

iwt_consumer.cpp

void publish_subscribe_example()
{
  /////////////////////////////////////////////
  // ZeroMQ pattern: Publish-subscribe
  /////////////////////////////////////////////
  zmq::context_t context(1);
  zmq::socket_t subscr_target_data(context, ZMQ_SUB);
  std::string address = "tcp://" + kHost + ":";
  std::string port = "61502";

  subscr_target_data.connect(address + port);
  subscr_target_data.set(zmq::sockopt::subscribe, "");
  while (true)
  {
    zmq::message_t update;
    if (subscr_target_data.recv(update, zmq::recv_flags::dontwait))
    {
      proto::nav_api::TargetData target_data;
      if (target_data.ParseFromArray(update.data(), update.size()))
      {
        printf("Got TargetData!\n");
        printf("Sonar serial number: %s\n", target_data.serial().c_str());
        int num_groups = target_data.groups_size();
        printf("There are %d groups in this ping.\n", num_groups);
        for (size_t i = 0; i < num_groups; ++i) {
          proto::nav_api::Group iwt_group = target_data.groups().at(i);
          int num_bins_in_group =  iwt_group.bins_size();
          printf("  There are %d bins in this group.\n", num_bins_in_group);
          for (size_t j = 0; j < num_bins_in_group; ++j) {
            proto::nav_api::Bin bin = iwt_group.bins().at(j); 
            printf("    iwt detection at: %.2fm crossrange, %.2fm downrange\n",
              bin.cross_range(), bin.down_range());
          }
        }
      }
    }
  }
}