【ROS2】publisher和subscriber和延时编写规则

1、publisher

节点名 auto node = rclcpp::Node::make_shared(“publisher”);
消息类型和话题 auto pub = node->create_publisher<std_msgs::msg::String>(“/pub_sub”, 10);
发送消息 pub->publish(myMessage); //注意用->

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"using namespace std::chrono_literals;int main(int argc, char * argv[])
{rclcpp::init(argc, argv);auto node = rclcpp::Node::make_shared("publisher");auto pub = node->create_publisher<std_msgs::msg::String>("/pub_sub", 10);std_msgs::msg::String myMessage;size_t counter{0};rclcpp::WallRate loop_rate(500ms);while (rclcpp::ok()){myMessage.data = "Hello, ros2 world! " + std::to_string(counter++);RCLCPP_INFO(node->get_logger(), "Publishing: '%s'", myMessage.data.c_str());try{pub->publish(myMessage);rclcpp::spin_some(node);} catch (const rclcpp::exceptions::RCLError & e){RCLCPP_ERROR(node->get_logger(), "Errore type : %s", e.what());}loop_rate.sleep();}rclcpp::shutdown();return 0;
}

2、subscriber

节点名 node = std::make_sharedrclcpp::Node(“subscriber”);
消息类型和话题 auto sub = node->create_subscription<std_msgs::msg::String>(“/pub_sub”, 10, TopicCallback);
回调函数 void TopicCallback(const std_msgs::msg::String::SharedPtr msg) //注意用::SharedPtr
回调函数消息 msg->data //注意用->

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"std::shared_ptr<rclcpp::Node> node = nullptr;void TopicCallback(const std_msgs::msg::String::SharedPtr msg)
{RCLCPP_INFO(node->get_logger(), "I heard the message : '%s'", msg->data.c_str());
}int main(int argc, char *argv[])
{rclcpp::init(argc, argv);node = std::make_shared<rclcpp::Node>("subscriber");auto sub = node->create_subscription<std_msgs::msg::String>("/pub_sub", 10, TopicCallback);rclcpp::spin(node);rclcpp::shutdown();return 0;
}

3、rqt_graph

4、延时sleep

  rclcpp::WallRate loop_rate(500ms);	//1s=1000ms,1ms=1000um,1um=1000nmwhile (rclcpp::ok()){......loop_rate.sleep();}