机器人操作系统ROS:从入门到放弃(三)　发布接收不同消息2

int a = 1 , b;
msgs_header.seq = 1; 
//or
b = msg_header.seq;

#include "ros/ros.h"
#include "geometry_msgs/PoseStamped.h" //include posestamp head file

#include <cmath>//for sqrt() function

int main(int argc, char **argv)
{
    ros::init(argc, argv, "talker");

    ros::NodeHandle n;

    ros::Publisher chatter_pub = n.advertise<geometry_msgs::PoseStamped>("chatter", 10); //initialize chatter

    ros::Rate loop_rate(10);

    //generate pose by ourselves.
    double positionX, positionY, positionZ;
    double orientationX, orientationY, orientationZ, orientationW;

    //We just make the robot has fixed orientation. Normally quaternion needs to be normalized, which means x^2 + y^2 + z^2 +w^2 = 1
    double fixedOrientation = 0.1;
    orientationX = fixedOrientation ;
    orientationY = fixedOrientation ;
    orientationZ = fixedOrientation ;
    orientationW = sqrt(1.0 - 3.0*fixedOrientation*fixedOrientation); 

    double count = 0.0;
    while (ros::ok())
    {
        //We just make the position x,y,z all the same. The X,Y,Z increase linearly
        positionX = count;
        positionY = count;
        positionZ = count;

        geometry_msgs::PoseStamped msg; 

        //assign value to poseStamped

            //First assign value to "header".
        ros::Time currentTime = ros::Time::now();
        msg.header.stamp = currentTime;

            //Then assign value to "pose", which has member position and orientation
        msg.pose.position.x = positionX;
        msg.pose.position.y = positionY;
        msg.pose.position.z = positionY;

        msg.pose.orientation.x = orientationX;
        msg.pose.orientation.y = orientationY;
        msg.pose.orientation.z = orientationZ;
        msg.pose.orientation.w = orientationW;

        ROS_INFO("we publish the robot's position and orientaion"); 
        ROS_INFO("the position(x,y,z) is %f , %f, %f", msg.pose.position.x, msg.pose.position.y, msg.pose.position.z);
        ROS_INFO("the orientation(x,y,z,w) is %f , %f, %f, %f", msg.pose.orientation.x, msg.pose.orientation.y, msg.pose.orientation.z, msg.pose.orientation.w);
        ROS_INFO("the time we get the pose is %f",  msg.header.stamp.sec + 1e-9*msg.header.stamp.nsec);

        std::cout<<"\n \n"<<std::endl; //add two more blank row so that we can see the message more clearly

        chatter_pub.publish(msg);

        ros::spinOnce();

        loop_rate.sleep();

        ++count;
    }


  return 0;
}