Function variant_example4

examples/src/json_traits_variant_examples.cpp:312–343

}

void variant_example4()
{
    using variant_type = std::variant<std::nullptr_t, int, double, bool, std::string>;
    
    std::vector<variant_type> v = {nullptr, 10, 5.1, true, std::string("Hello World")}; 

    std::string buffer;
    jsoncons::encode_json_pretty(v, buffer);
    std::cout << "(1)\n" << buffer << "\n\n";

    auto v2 = jsoncons::decode_json<std::vector<variant_type>>(buffer);

    auto visitor = [](auto&& arg) {
            using T = std::decay_t<decltype(arg)>;
            if constexpr (std::is_same_v<T, std::nullptr_t>)
                std::cout << "nullptr " << arg << '\n';
            else if constexpr (std::is_same_v<T, int>)
                std::cout << "int " << arg << '\n';
            else if constexpr (std::is_same_v<T, double>)
                std::cout << "double " << arg << '\n';
            else if constexpr (std::is_same_v<T, bool>)
                std::cout << "bool " << arg << '\n';
            else if constexpr (std::is_same_v<T, std::string>)
                std::cout << "std::string " << arg << '\n';
        };

    std::cout << "(2)\n";
    for (const auto& item : v2)
    {
        std::visit(visitor, item);
    }
}

void distinguish_by_type()
{