#include <iostream>


#include <nlohmann/json.hpp>
using json = nlohmann::json;


int
main( int argc, char *argv[] )
{
    json foo = R"({"key1": "value1"})"_json;


    std::cerr << "key1:" << foo["key1"] << ", size()=" << foo.size() << "\n";
    std::cerr << "key2:" << foo["key2"] << ", size()=" << foo.size() << "\n";
}


//
/*
$ g++ nloh.cpp
$ ./a.out
key1:"value1", size()=1
key2:null, size()=2
$
*/