Strongly typed enums

Classical C++ enumerators do not have their own scope. Therefore each name can only be used once:

enum Colors {Green, Yellow, Orange};
enum Fruits {Apple, Banana, Orange};  // error: redefinition of enumerator 'Orange'

With strongly typed enumerators, this is no longer an issue, since each enumerator has a separate namespace:

enum class Colors {Green, Yellow, Orange};
enum class Fruits {Apple, Banana, Orange}; // no problem

Another disadvantage of classical enumerators is that they allow comparison of the elements in two different enums. This can cause strange and unwanted behaviour:

if(Banana == Yellow) cout << "This is apples and oranges, but it works!!" << endl;
// warning: comparison of two values with different enumeration

For strongly typed enumerators this would result in a compiler error:

if(Fruits::Banana == Colors::Yellow) cout << "I will not compile this nonsense!" << endl;
//error: invalid operands to binary expression

Since C++11 it is also possible to specify the underlying type of the (classical and strongly typed) enums:

enum Letters : char { A, B, C };
enum class Numbers : int { A, B, C };