#include <iostream>
 #include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;
 
main() int main()
 {
     // create a JSON object
     json j =
     {
         {"pi", 3.141},
         {"happy", true},
         {"name", "Niels"},
         {"nothing", nullptr},
         {
             "answer", {
                 {"everything", 42}
             }
         },
         {"list", {1, 0, 2}},
         {
             "object", {
                 {"currency", "USD"},
                 {"value", 42.99}
             }
         }
     };
 
     // add new values
     j["new"]["key"]["value"] = {"another", "list"};
 
     // count elements
     auto s = j.size();
     j["size"] = s;
 
     // pretty print with indent of 4 spaces
     std::cout << std::setw(4) << j << '\n';
 }
 

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{
    "answer": {
        "everything": 42
    },
    "happy": true,
    "list": [
        1,
        0,
        2
    ],
    "name": "Niels",
    "new": {
        "key": {
            "value": [
                "another",
                "list"
            ]
        }
    },
    "nothing": null,
    "object": {
        "currency": "USD",
        "value": 42.99
    },
    "pi": 3.141,
    "size": 8
}