How can I output the value of an enum class in C++11

Question

How can I output the value of an enum class in C++11? In C++03 it\'s like this:

#include 

using namespace std;

enum A {
  a =          


        

Answer 1

It is possible to get your second example (i.e., the one using a scoped enum) to work using the same syntax as unscoped enums. Furthermore, the solution is generic and will work for all scoped enums, versus writing code for each scoped enum (as shown in the answer provided by @ForEveR).

The solution is to write a generic operator<< function which will work for any scoped enum. The solution employs SFINAE via std::enable_if and is as follows.

#include <iostream>
#include <type_traits>

// Scoped enum
enum class Color
{
    Red,
    Green,
    Blue
};

// Unscoped enum
enum Orientation
{
    Horizontal,
    Vertical
};

// Another scoped enum
enum class ExecStatus
{
    Idle,
    Started,
    Running
};

template<typename T>
std::ostream& operator<<(typename std::enable_if<std::is_enum<T>::value, std::ostream>::type& stream, const T& e)
{
    return stream << static_cast<typename std::underlying_type<T>::type>(e);
}

int main()
{
    std::cout << Color::Blue << "\n";
    std::cout << Vertical << "\n";
    std::cout << ExecStatus::Running << "\n";
    return 0;
}