create subscriber for /turtle1/pose data

edit

i tried to subscribe /turtle1/pose values to the node i created using this :

#include "ros/ros.h"
#include "turtlesim/Pose.h"
#include "std_msgs/Float32.h"
#include <sstream>

void callback(const turtlesim::Pose::ConstPtr& lis)

{

 std_msgs::Float32 m;

m.data=lis.x;

 ROS_INFO("i heard %f \n",m.data);

}

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

turtlesim::Pose lis;


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

ros::NodeHandle n;

ros::Subscriber sub1=n.subscribe("/turtle1/pose",1000,callback);

  ros::spin();

  return 0;
}

but it doesn't seem to work , i guess the problem is with the pointer lis since turtlesim::Pose is multi-dimensional array .