irrlicht/source/lib/json/docs/examples/basic_json__copyassignment.cpp

#include <iostream>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main()
{
    // create JSON values
    json a = 23;
    json b = 42;

    // copy-assign a to b
    b = a;

    // serialize the JSON arrays
    std::cout << a << '\n';
    std::cout << b << '\n';
}