三、从零学习ros2——demo

徒手攀岩

可以参照博主github上的demo，与官方提供的例子略有不同；
pub

#include <iostream>
#include <string>
#include <memory>
#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

int main(int argc, char* argv[]) {
  rclcpp::init(argc, argv);

  std::shared_ptr<rclcpp::Node> node = std::make_shared<rclcpp::Node>("talker");
  std::shared_ptr<rclcpp::Publisher<std_msgs::msg::String>> publisher =
          node->create_publisher<std_msgs::msg::String>("topic", 10);
  
  rclcpp::WallRate loop_rate(10);   // 表示频率，10HZ
  auto msg = std_msgs::msg::String();
  int count = 0;
  
  while(rclcpp::ok()) {
    msg.data = "hello world: " + std::to_string(count++);
    publisher->publish(msg);
    std::cout << "talker send msg: " << msg.data << "\n";
    loop_rate.sleep();
  }
  rclcpp::shutdown();
  return 0;
}
Sub

#include <iostream>
#include <string>
#include <memory>
#include <functional>
#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

void callback(std::shared_ptr<std_msgs::msg::String> msg) {
  std::cout << "receive: " << msg->data << "\n";
}

int main(int argc, char* argv[]) {
  rclcpp::init(argc, argv);

  std::shared_ptr<rclcpp::Node> node = std::make_shared<rclcpp::Node>("listener");
  auto subscriber = node->create_subscription<std_msgs::msg::String>(
      "topic", 10, std::bind(callback, std::placeholders::_1));
  
  rclcpp::spin(node);
  rclcpp::shutdown();
  return 0;
}CMakeLists.txt

cmake_minimum_required(VERSION 3.5)

project(ros2_demo)

find_package(rclcpp)
find_package(std_msgs)

add_executable(talker talker.cc)
ament_target_dependencies(talker
  rclcpp
  std_msgs
)
add_executable(listener listener.cc)
ament_target_dependencies(listener
  rclcpp
  std_msgs
)