注意：如果不知道topic的名字，可以用rostopic list查看

新建cpp文件

gedit xx.cpp

修改Cmakelists文件

• find_package(catkin REQUIRED COMPONENTS)里面的依赖
• 添加可执行文件声明

    add_executable(ABC src/xxx.cpp)  //rosrun package_name ABC，文件路径要对
    target_link_libraries(ABC ${catkin_LIBRARIES})
  

  ---

  修改packgae.xml文件

    <build_depend>xxx</build_depend>
    <run_depend>xxx</run_depend>
  

  ---

  编写源码（格式如下）

  ``` #include <ros/ros.h> #include <geometry_msgs/Twist.h> #include

void callback(const geometry_msgs::Twist & msg)//回调函数名字随意
{
	ROS_INFO_STREAM(std::setprecision(2) << std::fixed << "velocity  = " << msg.linear.x << "," << msg.angular.z );
}

int main (int argc, char  ** argv){
	ros::init(argc, argv, "listen");//节点的名字
	ros::NodeHandle nh;//将节点交给master

	ros::Subscriber sub = nh.subscribe ( "turtle1/cmd_vel", 1000, &callback);//和上面一致

	ros::spin();//关于ros::spin和ros::spinOnce的区别，看浅谈70页
} ```