DroneControl/class_model/src/json.cpp

#include <iostream>
#include <nlohmann/json.hpp>
#include <std_msgs/String.h>
#include <string>
#include <ros/ros.h>

using json = nlohmann::json;


void callBack(const std_msgs::String::ConstPtr &data){

    json j_data = json::parse(data->data);
    std::cout <<"original message"<< data->data << std::endl;
    // std::cout <<"parse message"<< j_data << std::endl;
    // std::cout <<"parse message"<< j_data["lat"] << std::endl;

    std::string k = j_data["lat"] , q = j_data["lon"];
    int lat = std::stoi(k) ,lon = std::stoi(q);
    std::cout <<"lat:"<< j_data["lat"] << std::endl;
    std::cout <<"lon:"<< j_data["lon"] << std::endl;

}

int main(int argc ,char **argv)
{
    // create JSON arrays
    std::string j,q,k;
    std_msgs::String mes;
    std::string data ="{\"lat\": \"241218859\", \"lon\": \"1206743161\", \"alt\": \"8489\", \"heading\": \"128\"}";
    // std::string data = "{'lat': 241217244, 'lon': '1206741391', 'alt': '8937', 'heading': 8800}";
    // std::string data ='"{"lat": "241218859", "lon": "1206743161", "alt": "8489", "heading": "128"}"';
    
    // Init ROS node
    ros::init(argc, argv, "ros_node");
    ros::NodeHandle json_node;
    // reate Assync spiner
    ros::AsyncSpinner spinner(0);
	spinner.start();   

    std::string rostopicName = "/uav_message";
    // ros::Publisher data_pub = json_node.advertise<std_msgs::String>(rostopicName,100);
    ros::Subscriber data_receive = json_node.subscribe<std_msgs::String>(rostopicName,100,callBack); 
    //ros::Subscriber data_receive1 = json_node.subscribe<std_msgs::String>("/uav_message",100,callBack);

    mes.data = data;
    // while(ros::ok()){
    // data_pub.publish(mes);
    // }
    // json j_no_init_list = json::array();
    // json j_empty_init_list = json::array({});
    // json j_nonempty_init_list = json::array({1, 2, 3, 4});
    // json j_list_of_pairs = json::array({ {"one", 1}, {"two", 2} });
    // json j_data_list = json::parse(data) ;

    // j = j_data_list["lat"];
    // q = j_data_list["lon"];
    // k = j_data_list["alt"];
    

    // serialize the JSON arrays
    // std::cout << j_no_init_list << '\n';
    // std::cout << j_empty_init_list << '\n';
    // std::cout << j_nonempty_init_list << '\n';
    // std::cout << j_list_of_pairs << '\n';
    // while(true){
    // std::cout << j_data_list << '\n';
    // std::cout << j_data_list["lat"] << '\n';
    // std::cout << std::stoi(j)<< std::stoi(q)<< std::stoi(k) << "\n";
    // }

    ros::waitForShutdown();

    return 0;
}