C++: 자료형 출력

개요

• 기본적으로는 typeid(T).name()를 이용
• 직관적인 출력을 원하는 경우 아래의 템플릿 함수 사용

  • // C++98
    template <typename T> string type_name_of_98() {
        const string s = __PRETTY_FUNCTION__;
        const int prefixSize = s.find("[with T = ") + strlen("[with T = ");
    
        return string(s.data() + prefixSize, s.find(';') - prefixSize);
    }
    
    // C++11
    template <typename T> constexpr string type_name_of_11() {
        const string s = __PRETTY_FUNCTION__;
        const int prefixSize = s.find("[with T = ") + strlen("[with T = ");
    
        return string(s.data() + prefixSize, s.find(';') - prefixSize);
    }
    
    // C++17
    template <typename T> constexpr string_view type_name_of_17() {
        const string s = __PRETTY_FUNCTION__;
        const int prefixSize = s.find("[with T = ") + strlen("[with T = ");
    
        return string_view(s.data() + prefixSize, s.find(';') - prefixSize);
    }
    

예제

• 코드

  • #include <cstring>
    #include <iostream>
    #include <string>
    #include <string_view>
    #include <typeinfo>
    
    using namespace std;
    
    class Test {};
    
    // C++98
    template <typename T> string type_name_of_98() {
        const string s = __PRETTY_FUNCTION__;
        const int prefixSize = s.find("[with T = ") + strlen("[with T = ");
    
        return string(s.data() + prefixSize, s.find(';') - prefixSize);
    }
    
    // C++11
    template <typename T> constexpr string type_name_of_11() {
        const string s = __PRETTY_FUNCTION__;
        const int prefixSize = s.find("[with T = ") + strlen("[with T = ");
    
        return string(s.data() + prefixSize, s.find(';') - prefixSize);
    }
    
    // C++17
    template <typename T> constexpr string_view type_name_of_17() {
        const string s = __PRETTY_FUNCTION__;
        const int prefixSize = s.find("[with T = ") + strlen("[with T = ");
    
        return string_view(s.data() + prefixSize, s.find(';') - prefixSize);
    }
    
    template <typename T> void type_name_test() {
        cout << typeid(T).name() << endl;
        cout << type_name_of_98<T>() << endl;
        cout << type_name_of_11<T>() << endl;
        cout << type_name_of_17<T>() << endl;
    }
    
    int main() {
        type_name_test<int>();
    
        cout << "------" << endl;
    
        type_name_test<int *>();
    
        cout << "------" << endl;
    
        type_name_test<double>();
    
        cout << "------" << endl;
    
        type_name_test<char *>();
    
        cout << "------" << endl;
    
        type_name_test<string>();
    
        cout << "------" << endl;
    
        type_name_test<Test>();
    
        return 0;
    }
    

• 실행 결과

  • i
    int
    int
    int
    ------
    Pi
    int*
    int*
    int*
    ------
    d
    double
    double
    double
    ------
    Pc
    char*
    char*
    char*
    ------
    NSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE
    std::__cxx11::basic_string<char>
    std::__cxx11::basic_string<char>
    std::__cxx11::basic_string<char>
    ------
    4Test
    Test
    Test
    Test