How to avoid name conflicts for two enum values with the same name in C++?

Question

Enums in C++ have one major problem: You can\'t have one name in two different enums like this:

enum Browser
{
    None = 0,
    Chrome = 1,
    Firefox = 2
         


        

Answer 1

Either wrap them in namespaces or in classes:

namespace Browser {
  enum BrowserType
  {
    None = 0,
    Chrome = 1,
    Firefox = 2
  }
}

namespace OS {
   enum OSType  {
      None = 0,
      XP = 1,
      Windows7 = 2
  }
}

Answer 2

You can use enum class (scoped enums) which is supported in C++11 on up. It is strongly typed and indicates that each enum type is different.

Browser::None != OS::None   

enum class Browser
{
    None = 0,
    Chrome = 1,
    Firefox = 2
}

enum class OS
{
    None = 0,
    XP = 1,
    Windows7 = 2
}

Answer 3

In C++03 you can enclose enum inside a struct:

struct Browser
{
  enum eBrowser
  {
    None = 0,
    Chrome = 1,
    Firefox = 2
  };
};

In C++11 make it an enum class:

enum class Browser
{
    None = 0,
    Chrome = 1,
    Firefox = 2
};

In C++03 namespace also can be wrapped, but personally I find wrapping struct/class better because namespace is more broader. e.g.

// file1.h
namespace X
{
  enum E { OK };
}

// file2.h
namespace X
{
  enum D { OK };
}

Answer 4

One option is to put each enum in a different namespace:

namespace Foo {
  enum Browser {
      None = 0,
      Chrome = 1,
      Firefox = 2
  }
}

namespace Bar {
  enum OS {
      None = 0,
      XP = 1,
      Windows7 = 2
  }
}

A better option, if available with your compiler, is to use C++11 enum classes:

enum class Browser { ... }
enum class OS { ... }

See here for a discussion on enum classes.

Answer 5

How about using scoped vs. unscoped enumeration? c++11 now offers scoped enumeration. An example would be:

enum class Browser : <type> {

};

enum class OS : <type> {

};

Access the enumerated types via an object of the Browser or an object of OS.