https://en.cppreference.com/w/cpp/language/fold Fold expressions(since C++17) - cppreference.com Reduces (folds) a parameter pack over a binary operator. [edit] Syntax ( pack op ... ) (1) ( ... op pack ) (2) ( pack op ... op init ) (3) ( init op ... op pack ) (4) 1) unary right fold 2) unary left fold 3) binary right fold 4) binary left fold op - any en.cppreference.com 이거 활용하기. c++ 17 이상부터 활용이 ..