#include "ros/ros.h"

#include "std_msgs/String.h"

#include <sstream>

/**

 * This tutorial demonstrates simple sending of messages over the ROS system.

 */

int main(int argc, char **argv)

{

  /**

   * The ros::init() function needs to see argc and argv so that it can perform

   * any ROS arguments and name remapping that were provided at the command line. For programmatic

   * remappings you can use a different version of init() which takes remappings

   * directly, but for most command-line programs, passing argc and argv is the easiest

   * way to do it.  The third argument to init() is the name of the node.

   *

   * You must call one of the versions of ros::init() before using any other

   * part of the ROS system.

   */

  ros::init(argc, argv, "talker");

  /**

   * NodeHandle is the main access point to communications with the ROS system.

   * The first NodeHandle constructed will fully initialize this node, and the last

   * NodeHandle destructed will close down the node.

   */

  ros::NodeHandle n;

  /**

   * The advertise() function is how you tell ROS that you want to

   * publish on a given topic name. This invokes a call to the ROS

   * master node, which keeps a registry of who is publishing and who

   * is subscribing. After this advertise() call is made, the master

   * node will notify anyone who is trying to subscribe to this topic name,

   * and they will in turn negotiate a peer-to-peer connection with this

   * node.  advertise() returns a Publisher object which allows you to

   * publish messages on that topic through a call to publish().  Once

   * all copies of the returned Publisher object are destroyed, the topic

   * will be automatically unadvertised.

   *

   * The second parameter to advertise() is the size of the message queue

   * used for publishing messages.  If messages are published more quickly

   * than we can send them, the number here specifies how many messages to

   * buffer up before throwing some away.

   */

  ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", );

  ros::Rate loop_rate();

  /**

   * A count of how many messages we have sent. This is used to create

   * a unique string for each message.

   */

  int count = ;

  while (ros::ok())

  {

    /**

     * This is a message object. You stuff it with data, and then publish it.

     */

    std_msgs::String msg;

    std::stringstream ss;

    ss << "hello world " << count;

    msg.data = ss.str();

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

    /**

     * The publish() function is how you send messages. The parameter

     * is the message object. The type of this object must agree with the type

     * given as a template parameter to the advertise<>() call, as was done

     * in the constructor above.

     */

    chatter_pub.publish(msg);

    ros::spinOnce();

    loop_rate.sleep();

    ++count;

  }

  return ;

}

#include "ros/ros.h"

#include "std_msgs/String.h"

/**

 * This tutorial demonstrates simple receipt of messages over the ROS system.

 */

void chatterCallback(const std_msgs::String::ConstPtr& msg)

{

  ROS_INFO("I heard: [%s]", msg->data.c_str());

}

int main(int argc, char **argv)

{

  /**

   * The ros::init() function needs to see argc and argv so that it can perform

   * any ROS arguments and name remapping that were provided at the command line. For programmatic

   * remappings you can use a different version of init() which takes remappings

   * directly, but for most command-line programs, passing argc and argv is the easiest

   * way to do it.  The third argument to init() is the name of the node.

   *

   * You must call one of the versions of ros::init() before using any other

   * part of the ROS system.

   */

  ros::init(argc, argv, "listener");

  /**

   * NodeHandle is the main access point to communications with the ROS system.

   * The first NodeHandle constructed will fully initialize this node, and the last

   * NodeHandle destructed will close down the node.

   */

  ros::NodeHandle n;

  /**

   * The subscribe() call is how you tell ROS that you want to receive messages

   * on a given topic.  This invokes a call to the ROS

   * master node, which keeps a registry of who is publishing and who

   * is subscribing.  Messages are passed to a callback function, here

   * called chatterCallback.  subscribe() returns a Subscriber object that you

   * must hold on to until you want to unsubscribe.  When all copies of the Subscriber

   * object go out of scope, this callback will automatically be unsubscribed from

   * this topic.

   *

   * The second parameter to the subscribe() function is the size of the message

   * queue.  If messages are arriving faster than they are being processed, this

   * is the number of messages that will be buffered up before beginning to throw

   * away the oldest ones.

   */

  ros::Subscriber sub = n.subscribe("chatter", , chatterCallback);

  /**

   * ros::spin() will enter a loop, pumping callbacks.  With this version, all

   * callbacks will be called from within this thread (the main one).  ros::spin()

   * will exit when Ctrl-C is pressed, or the node is shutdown by the master.

   */

  ros::spin();

  return ;

}