how to put subscriber and publisher in one cpp file ?

asked 2011-12-11 04:50:01 -0600

maruchi
155 ●17 ●21 ●26

Hi, I have a limited knowledge in C++ so that feel a difficulty in combining a subscriber and a publisher in one C++ file. Based on the tutorial, http://www.ros.org/wiki/ROS/Tutorials/WritingPublisherSubscriber%28c%2B%2B%29 , could anybody give some directions on making one C++ file which includes a subscriber and a publisher ?

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answered 2011-12-11 10:57:00 -0600

karthik

2831 ●55 ●68 ●96

Hi, Like there is 1 subscriber and 1 publisher in the tutorial. Try to write 2 chatters. i.e each chatter should be able to listen and also talk. In the subscriber of the tutorial add a publisher with different topic. Here is example code. I haven't executed it but it should be simple enough to understand.

#include "ros/ros.h"
#include "std_msgs/String.h"
#include <sstream>

void chatterCallback(const std_msgs::String::ConstPtr& msg)
{
  ROS_INFO("I heard: [%s]", msg->data.c_str());
}

int main(int argc, char **argv)
{

  ros::init(argc, argv, "listener");   
  ros::NodeHandle n;   
  ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback);
  ros::Publisher chatter_pub = n.advertise<std_msgs::String>("different_chatter", 1000);

  ros::Rate loop_rate(10);   

  int count = 0;
  while (ros::ok())
  {

    std_msgs::String msg;

    std::stringstream ss;
    ss << "hello world " << count;
    msg.data = ss.str();

    ROS_INFO("%s", msg.data.c_str());


    chatter_pub.publish(msg);

    ros::spinOnce();

    loop_rate.sleep();
    ++count;
  }


  ros::spin();

  return 0;
}

Now you can write the second chatter listening to "different_chatter" and publishing to "chatter" topics. Hope this helps,

Karthik