Get all topic and type from ROS in c++ !

ros_topic_list.cpp

#include <ros/ros.h>

int main(int argc, char** argv)
{
  ros::init(argc, argv, "ros_something");
  ros::start();
  XmlRpc::XmlRpcValue params("ros_topic_list");
  XmlRpc::XmlRpcValue results;
  XmlRpc::XmlRpcValue r;

  if(ros::master::execute("getTopicTypes", params, results, r, false) == true)
  {
    if(results.getType() == XmlRpc::XmlRpcValue::TypeArray)
    {
      int32_t i = 2;
      if(results[i].getType() == XmlRpc::XmlRpcValue::TypeArray)
      {
        for (int32_t j = 0; j < results[i].size(); ++j)
        {
          if(results[i][j].getType() == XmlRpc::XmlRpcValue::TypeArray)
          {
            if(results[i][j].size() == 2)
            {
              if(results[i][j][0].getType() == XmlRpc::XmlRpcValue::TypeString
                 && results[i][j][1].getType() == XmlRpc::XmlRpcValue::TypeString)
              {
                std::string topic = static_cast<std::string>(results[i][j][0]);
                std::string type = static_cast<std::string>(results[i][j][1]);
                std::cout<<"Topic : "<<topic<<" -> "<<type<<std::endl;
              }
            }
          }
        }
      }
    }
  }
  ros::shutdown();
  return 0;
}

How do you set the URI? When I use the command line to list topics, I get five or six separate topics, but I have no luck when running the code in C++.

ros::master::V_TopicInfo master_topics;
ros::master::getTopics(master_topics);

for (ros::master::V_TopicInfo::iterator it = master_topics.begin() ; it != master_topics.end(); it++) {
    const ros::master::TopicInfo& info = *it;
    std::cout << "Topic : " << it - master_topics.begin() << ": " << info.name << " -> " << info.datatype <<       std::endl;
}

achieves same result as above cleaner code. found this at http://stackoverflow.com/questions/26785675/ros-get-current-available-topic-in-code-not-command

Only get published topic