[C++] common_type

개요

• 인자로 전달된 n개의 타입들이 변환할 수 있는 공통 타입으로 변환

예제

• 코드

   #include <iostream>
   #include <string>
   #include <type_traits>
   #include <typeinfo>
      
   using namespace std;
      
   class Base {};
      
   class Derived : public Base {};
      
   template <typename T1, typename T2>
   auto plus_t(T1 t1, T2 t2) -> typename common_type<T1, T2>::type {
   	return t1 + t2;
   }
      
   int main() {
   	cout << typeid(common_type<int, float, double>::type).name() << endl;
   	cout << typeid(common_type<char, int>::type).name() << endl;
   	cout << typeid(common_type<char *, string>::type).name() << endl;
   	cout << typeid(common_type<Base, Derived>::type).name() << endl;
   	cout << typeid(common_type<Base *, Derived *>::type).name() << endl;
      
   	cout << plus_t(1, 1) << endl;
   	cout << plus_t(1, 1.1) << endl;
   	cout << plus_t("a", string("a")) << endl;
      
   	return 0;
   }
  

• 실행 결과

   d
   i
   NSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE
   4Base
   P4Base
   2
   2.1
   aa