注释语句:

ROS/ros_learn_cpp.md

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+# 1.通信机制
+## 1-1.话题通信
+1. 话题通信基本操作
+    * 发布数据
+```cpp
+    #include "ros/ros.h"
+    #include "std_msgs/String.h"//普通文本类型的消息
+    #include <sstream>
+    int main(int argc, char *argv[]){
+        setlocale(LC_ALL, "");
+        ros::init(argc, argv, "talker");
+        ros::NodeHandle nh;
+        ros::Publisher pub = nh.advertise<std_msgs::String>("chatter",10);
+        std_msgs::String msg;
+        std::string msg_front = "hello";   
+        int count = 0;
+        ros::Rate r(1);
+        while (ros::ok()){
+            std::stringstream ss;//使用stringstream拼接字符串和编号
+            ss << msg_front << count;
+            msg.data = ss.str();
+            //发布消息
+            pub.publish(msg);
+            ROS_INFO("发送的消息:%s",msg.data.c_str());
+            r.sleep()//休眠时间 = 1/频率
+            count++;
+            ros::spinOnce();
+        }
+        return 0;
+    }
+```      
+    * 接收数据
+```cpp
+      #include "ros/ros.h"
+      #include "std_msgs/String.h"
+      #include <sstream>
+      /*
+          訂約方实现：
+          1.包含头文件：
+              ROS中文本类型-->std_msgs/String.h
+          2.初始化节点
+          3.创建节点句柄
+          4.创建訂閱者对象
+          5.處理訂閱數據
+
+      */
+      void doMsg(const std_msgs::String::ConstPtr &msg){//发布类型为std_msgs下的常量指針的引用
+          //通過msg獲取並操作訂库閱到的數據
+          ROS_INFO("翠花订阅的数据%s", msg->data.c_str());//因为msg是指针的引用，所以需要用->调用，c_str()指的是c风格的字符串
+      }
+
+      int main(int argc, char *argv[])
+      {
+          //2.初始化ROS节点
+          ros::init(argc, argv, "subscriber");
+          //3.创建节点句柄
+          ros::NodeHandle nh;
+          //4.创建订阅者对象
+          ros::Subscriber sub = nh.subscribe<std_msgs::String>("fangzi", 10, doMsg);
+          //5.处理订阅的消息
+          //6.回旋函数
+          ros::spin();//循环执行main()
+          return 0; 
+      }
+```
+---
+    * 调整cmake文件
+  ```cmake
+  add_executable(Hello_pub
+    src/Hello_pub.cpp
+  )
+  add_executable(Hello_sub
+    src/Hello_sub.cpp
+  )
+
+  target_link_libraries(Hello_pub
+    ${catkin_LIBRARIES}
+  )
+    ${catkin_LIBRARIES}
+  )
+  ```
+
+2. 话题通信自定义msg调用
+    * 2-1.流程：
+      * 1. 修改xml文件和cmake文件：
+        * 在cmake中:
+        ```cmake 
+        add_executable(person_talker src/person_talker.cpp)
+        add_executable(person_listener src/person_listener.cpp)
+
+        add_dependencies(person_talker ${PROJECT_NAME}_generate_messages_cpp)
+        add_dependencies(person_listener ${PROJECT_NAME}_generate_messages_cpp)
+        
+        target_link_libraries(person_talker
+        ${catkin_LIBRARIES}
+        )
+        target_link_libraries(person_listener
+        ${catkin_LIBRARIES}
+        )
+        ```
+        * 在xml中：message_generation+message_runtime<--->build_depend+build_export_depend+exec_depend
+      ```xml
+        <build_depend>roscpp</build_depend>
+        <build_depend>rospy</build_depend>
+        <build_depend>std_msgs</build_depend>
+        <build_depend>message_generation</build_depend>
+        <build_depend>message_runtime</build_depend>
+        <build_export_depend>roscpp</build_export_depend>
+        <build_export_depend>rospy</build_export_depend>
+        <build_export_depend>std_msgs</build_export_depend>
+        <build_export_depend>message_generation</build_export_depend>
+        <build_export_depend>message_runtime</build_export_depend>
+        <exec_depend>roscpp</exec_depend>
+        <exec_depend>rospy</exec_depend>
+        <exec_depend>std_msgs</exec_depend>
+        <exec_depend>message_runtime</exec_depend>
+        <exec_depend>message_generation</exec_depend>
+      ```
+      * 2. 发布方的实现
+      ```cpp
+      #include "ros/ros.h"
+      #include "demo02_talker_listener/Person.h"
+
+      int main(int argc, char *argv[])
+      {
+          setlocale(LC_ALL,"");
+
+          //1.初始化 ROS 节点
+          ros::init(argc,argv,"talker_person");
+
+          //2.创建 ROS 句柄
+          ros::NodeHandle nh;
+
+          //3.创建发布者对象
+          ros::Publisher pub = nh.advertise<demo02_talker_listener::Person>("chatter_person",1000);
+
+          //4.组织被发布的消息，编写发布逻辑并发布消息
+          demo02_talker_listener::Person p;
+          p.name = "sunwukong";
+          p.age = 2000;
+          p.height = 1.45;
+          ros::Rate r(1);
+          while (ros::ok())
+          {
+              pub.publish(p);
+              p.age += 1;
+              ROS_INFO("我叫:%s,今年%d岁,高%.2f米", p.name.c_str(), p.age, p.height);
+
+              r.sleep();
+              ros::spinOnce();
+          }
+          return 0;
+      }
+      ```
+      * 3.订阅方的实现
+        ```cpp
+        #include "ros/ros.h"
+        #include "demo02_talker_listener/Person.h"
+        
+        void doPerson(const demo02_talker_listener::Person::ConstPtr& person_p){
+            ROS_INFO("订阅的人信息:%s, %d, %.2f", person_p->name.c_str(), person_p->age, person_p->height);
+        }
+
+        int main(int argc, char *argv[])
+        {   
+            setlocale(LC_ALL,"");
+
+            //1.初始化 ROS 节点
+            ros::init(argc,argv,"listener_person");
+            //2.创建 ROS 句柄
+            ros::NodeHandle nh;
+            //3.创建订阅对象
+            ros::Subscriber sub = nh.subscribe<demo02_talker_listener::Person>("chatter_person",10,doPerson);
+
+            //4.回调函数中处理 person
+
+            //5.ros::spin();
+            ros::spin();    
+            return 0;
+        }
+        ```