title: Errors while building my ROS node
body: <p>I am new to ROS...and trying to create a simple random number generator, which will publish the randomly generated values. For this I created a Position class :</p>
  
  <pre><code>include "stdlib.h"
  
  namespace RandomPositionGenerator {
  
  
  class Position {
  private:
  double x;
  double y;
  double z;
  public:
  Position();
  void setPosition();
  void getPosition(double &amp;a, double &amp;b, double &amp;c);
  };
  
  Position::Position(){}
  
  void Position::setPosition() {
  x = rand();
  y = rand();
  z = rand();
  }
  
  void Position::getPosition(double &amp;a, double &amp;b, double &amp;c) {
   a=x;
   b=y;
   c=z;
  
  }
  
  }
  </code></pre>
  
  <p>and used this class to create my publisher :</p>
  
  <pre><code>include "ros/ros.h"
  include "std_msgs/String.h"
  include "sstream"
  include "Position.cpp"
  
  /**
   * This method generates position coordinates at random.
  **/
  int main(int argc, char **argv)
  {
      ros::init(argc, argv, "talker");
  
      ros::NodeHandle n;
      ros::Publisher position_pub = n.advertise&lt;RandomPositionGenerator:: Position&gt;      ("position", 50);
      ros::Rate loop_rate(10);
  
      double pos_x=0;
      double pos_y=0;
      double pos_z=0;
  
      while (ros::ok())
      {
     RandomPositionGenerator:: Position pos;
     pos.setPosition();
     pos.getPosition(pos_x,pos_y,pos_z);
  
         ROS_INFO("The co-ordinates are : x=",pos_x);
  
         position_pub.publish(pos);
         ros::spinOnce();
         loop_rate.sleep();
  
      }
  
  
     return 0;
  }
  </code></pre>
  
  <p>And now I get the following errors:</p>
  
  <ol>
  <li>‘__s_getDataType’ is not a member of ‘RandomPositionGenerator::Position’ </li>
  <li>‘__s_getMD5Sum’ is not a member of ‘RandomPositionGenerator::Position’   </li>
  <li>‘const class RandomPositionGenerator::Position’ has no member named ‘__getDataType’  </li>
  </ol>
  
  <p>and some more similar errors...Please correct me...I am not sure where am I going wrong, or if there is anything that I did right in this small bit of code !</p>