공식 문서는 아래. https://en.cppreference.com/w/cpp/utility/variant std::variant - cppreference.com template class variant; (since C++17) The class template std::variant represents a type-safe union. An instance of std::variant at any given time either holds a value of one of its alternative types, or in the case of error - no value (th en.cppreference.com 쉽게 말하자면, 우리가 알고 있던 union 이라는..