新建包(后面跟着的是依赖)当然，也可以在已有的包里写，一个包含有多个节点
catkin_create_pkg listen rospy roscpp std_msgs geometry_msgs sensor_msgs turtlesim
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})
include_directories(
include
${catkin_INCLUDE_DIRS}
) ``` ------ ### 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 <std_msgs/String.h>
#include <begin/Vel.h>
#include <geometry_msgs/Twist.h>
#include <sstream>
#include <iomanip>
int main(int argc, char ** argv){
ros::init(argc, argv, "give_out");//节点的名字
ros::NodeHandle n;
ros::Publisher my_pub = n.advertise<begin::Vel> ("my_Vel", 1000);
//my_Vel是话题的名字
ros::Rate loop_rate(1);
int cnt = 1;
begin::Vel msg; //定义一个Vel类型的数据
while(ros::ok())
{
if((cnt%2) == 0) msg.linear.x = 1.0;
else msg.linear.x = 2.0;
ROS_INFO_STREAM(std::setprecision(2) << std::fixed<< "velocity = " << msg.linear.x );
my_pub.publish(msg);//发布消息到话题
loop_rate.sleep();//这边的loop_rate要和上面的一致。
cnt = cnt * 3+ 1;
}
return 0;
} ```
