Error when replace template type with specify type as member variable type define

Question

I want to change the variable type of member variable when type parameter is the specific type (ex. int to unsigned char).

The error messages are added in comment.

template <typename T>
class temClass {
private:
    template<typename T>            // typename : declaration of template parameter 'T' shadows template parameter
    struct STR_T {
        typedef T T_IF;
    };

    template<>                      // <> : error: explicit specialization in non-namespace scope 'class temClass<T>'
    struct STR_T<int> {             // STR_T<int> : template parameters not deducible in partial specialization
        typedef unsigned char T_IF;
    };

    typedef typename STR_T<T>::T_IF T_DEF;

    T_DEF abc;

public:
    temClass() {  }
    ~temClass() {  }

    void showMemSize() {
        printf("mem size = %d\n", sizeof(abc));
    }
};

and the main function

int main() {
    temClass<int> temClassInt;
    temClass<unsigned int> temClassUInt;

    temClassInt.showMemSize();
    temClassUInt.showMemSize();

    return 0;
}

The desired result is 1 and 4.

I use eclipse CDT with MinGW GCC. the GCC version is 6.3.0.

Answer 1

i'm so dumb

thanks StoryTeller - Unslander Monica 's comment

just move STR_T to namespace

namespace NS_STR {
    template<typename T2>
    struct STR_T {
        typedef T2 T_IF;
    };

    template<>
    struct STR_T<int> {
        typedef unsigned char T_IF;
    };
}

template <typename T>
class temClass {
private:

    typedef typename NS_STR::STR_T<T>::T_IF T_DEF;

    T_DEF abc;

public:
    temClass() {  }
    ~temClass() {  }

    void showMemSize() {
        printf("mem size = %d\n", sizeof(abc));
    }
};

The result would be 1 and 4