ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null
brew install nlohmann_json
brew install curlpp

CMakeLists.txt

cmake_minimum_required(VERSION 3.12)
project(netq)
 
set(CMAKE_CXX_STANDARD 17)
# find_package(nlohmann_json 3.2.0 REQUIRED)
 
link_directories(/usr/local/Cellar/curlpp/0.8.1)
link_directories(/usr/local/Cellar/nlohmann-json/3.7.0)
 
find_package(nlohmann_json REQUIRED PATHS /usr/local/Cellar/nlohmann-json/3.7.0/ NO_DEFAULT_PATH)
 
add_executable(netq main.cpp)
target_link_libraries(netq LINK_PUBLIC curl curlpp nlohmann_json::nlohmann_json)
# target_link_libraries(netq PRIVATE nlohmann_json::nlohmann_json)

main.cpp

#include <iostream>
#include <sstream>
#include <math.h>
#include <curlpp/cURLpp.hpp>
#include <curlpp/Easy.hpp>
#include <curlpp/Options.hpp>
#include <nlohmann/json.hpp>
 
#define copt curlpp::options
 
using json = nlohmann::json;
 
std::string getNames() {
    json j;
    j["addr"] = nullptr;
    j["port"] = 8887;
 
    json t;
    t["port"] = "/dev/cu.Bluetooth-Incoming-Port";
    t["bandwidth"] = 115200;
    j["arduino"] = t;
 
    return  j.dump();
}
 
std::string dump_state() {
    json j;
    j["pi"] = 3.14159265359;
    j["hello"] = "World";
    std::stringstream s;
    for (int i=0; i<3; i++) {
        s.str("");
        s << "loore " << i;
        j["manage"][i] = (std::string) s.str();
        j["vote"][s.str()] = i;
    }
    return j.dump();
}
 
std::string get(const std::string url) {
    curlpp::Cleanup myCleanup;
    std::ostringstream os;
    os << curlpp::options::Url(std::string(url));
    return os.str();
}
 
std::string post(std::string url, std::string json) {
    std::list<std::string> header;
    header.push_back("Content-Type: application/json");
    curlpp::Cleanup clean;
    curlpp::Easy re;
    re.setOpt(new copt::Url(url));
    re.setOpt(new copt::HttpHeader(header));
    re.setOpt(new copt::PostFields(json));
    re.setOpt(new copt::PostFieldSize(json.length()));
 
    std::ostringstream os;
    re.setOpt(new curlpp::options::WriteStream(&os));
 
    re.perform();
 
    return std::string(os.str());
}
 
void names() {
    std::vector<std::string> names;
    std::string name;
    while (1) {
        std::cout << "What is your name? ";
        getline(std::cin, name);
        if (name.length()) {
            names.push_back(name);
        } else {
            break;
        }
    }
    for (std::string name : names) {
        std::cout << "Hello, " << name << "!" << std::endl;
    }
}
 
int main() {
 
    std::string m = getNames();
    if (m.length()) {
        std::cout << m << std::endl;
        return 0;
    }
 
    // std::string ts = get("https://raw.githubusercontent.com/nlohmann/json/develop/test/data/json.org/1.json");
    std::string s = dump_state();
    try {
        s = post("http://localhost/post2echo.php", s);
    } catch( const std::exception & ex ) {
        std::cerr << ex.what() << std::endl;
    };
    std::cout << s << std::endl;
    return 0;
}