C++ Primer Plus

Scoped Enumerations

Traditional C++ enumerations provide a way to create named constants. However, they come with a rather low level of type checking. Also the scope for enumeration names is the scope that encloses the enumeration definition, which means that two enumerations defined in the same scope must not have enumeration members with the same name. Finally, enumerations may not be completely portable because different implementations may choose to use different underlying types. C++11 introduces a variant of enumerations that addresses these problems. The new form is indicated by using class or struct in the definition:

enum Old1 {yes, no, maybe};                        // traditional formenum class New1 {never, sometimes, often, always}; ...