C++ Primer Plus

Scoped Enumerations (C++11)

Traditional enumerations have some problems. One is that enumerators from two different enum definitions can conflict. Suppose you were working on a project involving eggs and T-shirts. You might try something like this:

enum egg {Small, Medium, Large, Jumbo};enum t_shirt {Small, Medium, Large, Xlarge};

This won’t fly because the egg Small and the t_shirt Small would both be in the same scope, and the names conflict. C++11 provides a new form of enumeration that avoids this problem by having class scope for its enumerators. The declarations for this form look like this:

enum class egg {Small, Medium, Large, Jumbo};enum class t_shirt {Small, Medium, Large, Xlarge};

Alternatively, you can use the keyword struct instead ...