（C++版本）ros2发布者节点publisher示例源代码（改良版）

#include 
#include 
#include 
#include 
#include 
#include "sys/time.h"
 
#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"
 
using namespace std;
using namespace rclcpp;
uint32_t count1=0;
    stringstream ss;
    std_msgs::msg::String message;
     rclcpp::TimerBase::SharedPtr timer_;	
    //define a publisher
//define a ros2 timer_process function
class mynode:public Node
{
public:
std::shared_ptr> ppublisher;
mynode(string str ):Node(str)
{
    std::cout<<"enter mynode structure"<
    ppublisher=this->create_publisher("topicName",10);
    
    timer_=this->create_wall_timer(100ms, bind(&mynode::timer_callback,this) ); 
    std::cout<<"leave mynode structure"<
 
}
void timer_callback()
{
    std::cout<<"enter timer_callback"<
        ss.str()="";
        ss<<"hi im glad to see you"<
        message.data=ss.str();
        cout<
        //publish a topic
  //      Publisher2.publish(message);
  ppublisher->publish(message);
    std::cout<<"leave timer_callback"<
}
};
 
//define a node
//define a publisher
//utility publiser to publish a topic
int main(int argc,char ** argv)
{
    rclcpp::init(argc,argv);
 //   Rate rate(1);
    std::cout<<"before spin"<
    spin(std::make_shared("nodeName"));    //execute the timer_proc//
    std::cout<<"after spin"<
    rclcpp::shutdown();
    return 0;
 
}

说明：上面这个代码里面有个变量看来是没有用的timer_，但是一旦删除整个代码编译时候虽然不会报错，但是代码无法正常运行。