An Enumeration is a unique type whose value consists of a set of enumerators. Enumerators are named constants of the type int. They can have an identifier as well as a value. If no values are declared, the values of the corresponding constants begin at 0 and increase by increments of 1. For example, a basic enumeration looks like this:

By default, the value of const1 is 0, const2 is 1, and so on. You can also give each constant an explicit value like this:

In this instance, the value of const1 is now 4, const2 is 7, and const3 is 22. Each constant’s identifier must be unique. For instance, you cannot have 2 constants named const1 in the same enumeration.