#include<ros/ros.h>

int main(int argc, char **argv){

        ros::init(argc, argv, "param_demo");

        ros::NodeHandle nh;

        int parameter1, parameter2, parameter3, parameter4, parameter5;

        //Get Param的三种方法

        //① ros::param::get()获取参数“param1”的value，写入到parameter1上

        bool ifget1 = ros::param::get("param1", parameter1);

        //② ros::NodeHandle::getParam()获取参数，与①作用相同

        bool ifget2 = nh.getParam("param2",parameter2);

        //③ ros::NodeHandle::param()类似于①和②

        //但如果get不到指定的param，它可以给param指定一个默认值(如33333)

        nh.param("param3", parameter3, );

        if(ifget1)

                ROS_INFO("Get param1 = %d", parameter1);

        else

                ROS_WARN("Didn't retrieve param1");

       if(ifget2)

                ROS_INFO("Get param2 = %d", parameter2);

        else

                ROS_WARN("Didn't retrieve param2");

        if(nh.hasParam("param3"))

                ROS_INFO("Get param3 = %d", parameter3);

        else

                ROS_WARN("Didn't retrieve param3");

    //Set Param的两种方法

        //① ros::param::set()设置参数

        parameter4 = ;

        ros::param::set("param4", parameter4);

        //② ros::NodeHandle::setParam()设置参数

        parameter5 = ;

        nh.setParam("param5",parameter5);

        ROS_INFO("Param4 is set to be %d", parameter4);

        ROS_INFO("Param5 is set to be %d", parameter5);

        //Check Param的两种方法

        //① ros::NodeHandle::hasParam()

        bool ifparam5 = nh.hasParam("param5");

        //② ros::param::has()

        bool ifparam6 = ros::param::has("param6");

        if(ifparam5)

                ROS_INFO("Param5 exists");

        else

                ROS_INFO("Param5 doesn't exist");

        if(ifparam6)

                ROS_INFO("Param6 exists");

        else

                ROS_INFO("Param6 doesn't exist");

        //Delete Param的两种方法

        //① ros::NodeHandle::deleteParam()

        bool ifdeleted5 = nh.deleteParam("param5");

        //② ros::param::del()

        bool ifdeleted6 = ros::param::del("param6");

        if(ifdeleted5)

                ROS_INFO("Param5 deleted");

        else

                ROS_INFO("Param5 not deleted");

        if(ifdeleted6)

                ROS_INFO("Param6 deleted");

        else

                ROS_INFO("Param6 not deleted");

        ros::Rate rate(0.3);

        while(ros::ok()){

                int parameter = ;

                ROS_INFO("=============Loop==============");

                //roscpp中尚未有ros::param::getallparams()之类的方法

                if(ros::param::get("param1", parameter))

                        ROS_INFO("parameter param1 = %d", parameter);

                if(ros::param::get("param2", parameter))

                        ROS_INFO("parameter param2 = %d", parameter);

                if(ros::param::get("param3", parameter))

                        ROS_INFO("parameter param3 = %d", parameter);

                if(ros::param::get("param4", parameter))

                        ROS_INFO("parameter param4 = %d", parameter);

                if(ros::param::get("param5", parameter))

                        ROS_INFO("parameter param5 = %d", parameter);

                if(ros::param::get("param6", parameter))

                        ROS_INFO("parameter param6 = %d", parameter);

                rate.sleep();

        }

}

<launch>

    <!--param参数配置-->

    <param name="param1" value="1" />

    <param name="param2" value="2" />

    <!--param name="table_description" command="$(find xacro)/xacro.py $(find gazebo_worlds)/objects/table.urdf.xacro" /-->

    <!--rosparam参数配置-->

    <rosparam>

        param3: 3

        param4: 4

        param5: 5

    </rosparam>

    <!--以上写法将参数转成YAML文件加载，注意param前面必须为空格，不能用Tab，否则YAML解析错误-->

    <!--rosparam file="$(find robot_sim_demo)/config/xbot-u_control.yaml" command="load" /-->

    <node pkg="param_demo" type="param_demo" name="param_demo" output="screen" />

</launch>