sample_ROS_talker.cpp

#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", 1000);

  ros::Rate loop_rate(10);

  /**
    * A count of how many messages we have sent. This is used to create
    * a unique string for each message.
    */
  int count = 0;
  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 Erle! " << 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 0;
}