C++ How can I access to an inner enum class?

Question

I am facing a problem in c++:

#include <iostream>
 class Apple{
public:
    int price = 100;
    enum class color {
    red =1, green, yellow
    };



};
int main() {
 Apple apple;
 std::cout << Apple::color::green << std::endl;

}

When I try to compile this code following message appears:

[Error] 'Apple::color' is not a class or namespace

Answer 1

1. Looks like you're using a pre C++11 compiler or c++11 flag is not enabled.

2. After using correct c++11 flag, you will have to overload operator <<

   friend std::ostream& operator <<( std::ostream& os, const color& c )
   {
     /* ... */
     return os;
   }