how to publish int8,float ...and function ? [closed]

edit

i can't publish int8 .. can you help me?

  #include "ros/ros.h"
#include "std_msgs/Int8.h"

#include <sstream>


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

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

  ros::NodeHandle n;


  ros::Publisher chatter_pub = n.advertise<std_msgs::Int8>("mytopic", 1000);

  ros::Rate loop_rate(10);

    int8_t count = 0;
  while (ros::ok())
  {

    std_msgs::Int8 msg;


    msg.data = count++;

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


    chatter_pub.publish(msg);

    ros::spinOnce();

    loop_rate.sleep();

  }


  return 0;
}

display : NULL