enum

The section to enumerations has eight rules. Since C++11, we have scoped enumerations which overcome a lot of the drawbacks of classical enumerations. 

Plain Old Data (POD) obeys the C standard layout. Therefore, you directly can apply the fast C functions memcopy, memmove, memset, or memcmp.

Enumerations are a convenient way to define integer constants with names. This integer constants are called enumerators. Sadly, classical enums have a few drawbacks.