set-param.cpp

// ==================================================================
// program : param.cpp
// author:   Ar-Ray (https://github.com/Ar-Ray-code)
// Date:     2021-08-15
// License:  Apache License 2.0
// ==================================================================
#include <rclcpp/rclcpp.hpp>
#include <std_msgs/msg/int32.hpp>

class param_example:public rclcpp::Node
{
    private:
        rclcpp::Subscription<std_msgs::msg::Int32>::SharedPtr sub;
        int number0, number1, number2, number3;

        void show_log()
        {
            RCLCPP_INFO(this->get_logger(),"get parameter\nnumber0:%3d\nnumber1:%3d\nnumber2:%3d\nnumber3:%3d\n", number0, number1, number2, number3);
            RCLCPP_INFO(this->get_logger(),"end");
        }

    public:
        param_example(const std::string name, const rclcpp::NodeOptions & options):Node(name, options)
        {
            this->declare_parameter("param0", -1);
            this->declare_parameter("param1", -1);
            this->declare_parameter("param2", -1);
            this->declare_parameter("param3", -1);

            number0 = this->get_parameter("param0").as_int();
            number1 = this->get_parameter("param1").as_int();
            number2 = this->get_parameter("param2").as_int();
            number3 = this->get_parameter("param3").as_int();
            show_log();
        }
};

int main(int argc, char** argv)
{
    rclcpp::init(argc, argv);
    rclcpp::NodeOptions options;
    auto node = std::make_shared<param_example>("param_example",options);
	
    rclcpp::spin(node);
    rclcpp::shutdown();
    return 0;
}