In C enumerators have type int . Thus any integer value can be assigned to an object of the enumeration type.
From the C Standard (6.7.2.2 Enumeration specifiers)
3 The identifiers in an enumerator list are declared as constants that
have type int and may appear wherever such are permitted.
In C++ enumerators have type of the enumeration that defines it. In C++ you should either expliicitly to specify the underlaying type or the compiler calculates itself the maximum allowed value.
From the C++ Standard (7.2 Enumeration declarations)
5 Each enumeration defines a type that is different from all other types. Each enumeration also has an underlying type. The underlying type can be explicitly specified using enum-base; if not explicitly specified, the underlying type of a scoped enumeration type is int. In these cases, the underlying type is said to be fixed. Following the closing brace of an enum-specifier, each enumerator has the type of its enumeration.
Thus in C any possible value of a enum is any integer value. The compiler may not optimize a switch removing the default label.
