Programming/C++ / STL2016.07.01 10:04

cpp이랑은 안친한데 크윽 ㅠㅠ

컴파일러나 Cxx 적용 버전의 차이겠지만


$ g++ --version

g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3

Copyright (C) 2011 Free Software Foundation, Inc.

This is free software; see the source for copying conditions.  There is NO

warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


g++ 4.6.3 에서는 scope 인식을 하긴 하는데

$ cat enum.cpp

#include <iostream>


class A

{

public:

        int a;

        enum

        {

                A_1,

                A_2,

                A_3

        };

};


class B

{

public:

        int b;

        enum

        {

                B_1,

                B_2,

                B_3

        };


};


int main()

{

        A a;

        B b;


        a.a = B_1;

        a.a = A_1;


        b.b = A_1;

        b.b = B_1;

        return 0;

}


$ g++ enum.cpp

enum.cpp: In function ‘int main()’:

enum.cpp:33:8: error: ‘B_1’ was not declared in this scope

enum.cpp:34:8: error: ‘A_1’ was not declared in this scope 


clang에서는 scope를 조금더 정밀하게 따지는 듯?

$ clang --analyze enum.cpp

enum.cpp:33:8: error: use of undeclared identifier 'B_1'

        a.a = B_1;

              ^

enum.cpp:34:8: error: use of undeclared identifier 'A_1'

        a.a = A_1;

              ^

enum.cpp:36:8: error: use of undeclared identifier 'A_1'

        b.b = A_1;

              ^

enum.cpp:37:8: error: use of undeclared identifier 'B_1'

        b.b = B_1;

              ^

4 errors generated. 


scope만 잡아주면.. public에서 선언한거라 문제없이 되는건가?

$ cat enum.cpp

#include <iostream>


class A

{

public:

        int a;

        enum

        {

                A_1,

                A_2,

                A_3

        };

};


class B

{

public:

        int b;

        enum

        {

                B_1,

                B_2,

                B_3

        };


};


int main()

{

        A a;

        B b;


        a.a = B::B_1;

        a.a = A::A_1;


        b.b = A::A_1;

        b.b = B::B_1;

        return 0;


$ g++ enum.cpp

$ clang --analyze enum.cpp 



enum 자체에 private를 줘보니..

에러 뿜뿜!

$ cat enum.cpp

#include <iostream>


class A

{

public:

        int a;


private:

        enum

        {

                A_1,

                A_2,

                A_3

        };

};


class B

{

public:

        int b;


private:

        enum

        {

                B_1,

                B_2,

                B_3

        };


};


int main()

{

        A a;

        B b;


        a.a = B::B_1;

        a.a = A::A_1;


        b.b = A::A_1;

        b.b = B::B_1;

        return 0;


$ g++ enum.cpp

enum.cpp: In function ‘int main()’:

enum.cpp:25:3: error: ‘B::<anonymous enum> B::B_1’ is private

enum.cpp:37:11: error: within this context

enum.cpp:11:3: error: ‘A::<anonymous enum> A::A_1’ is private

enum.cpp:38:11: error: within this context

enum.cpp:11:3: error: ‘A::<anonymous enum> A::A_1’ is private

enum.cpp:40:11: error: within this context

enum.cpp:25:3: error: ‘B::<anonymous enum> B::B_1’ is private

enum.cpp:41:11: error: within this context


$ clang --analyze enum.cpp

enum.cpp:37:11: error: 'B_1' is a private member of 'B'

        a.a = B::B_1;

                 ^

enum.cpp:25:3: note: declared private here

                B_1,

                ^

enum.cpp:38:11: error: 'A_1' is a private member of 'A'

        a.a = A::A_1;

                 ^

enum.cpp:11:3: note: declared private here

                A_1,

                ^

enum.cpp:40:11: error: 'A_1' is a private member of 'A'

        b.b = A::A_1;

                 ^

enum.cpp:11:3: note: declared private here

                A_1,

                ^

enum.cpp:41:11: error: 'B_1' is a private member of 'B'

        b.b = B::B_1;

                 ^

enum.cpp:25:3: note: declared private here

                B_1,

                ^

4 errors generated.


결론 

public일 경우 당연히(!) 다른 클래스에서도 사용 가능,

private일 때는 당연히(!) 다른 클래스에서는 사용 불가

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