How to retrieve values from a C++ enum?

In C++, an enumeration is a user-defined data type used to define a set of named integer constants. The values of an enumeration type can be accessed through various methods.

1. Using enumeration constants directly: You can directly use constants defined by an enumeration type to represent values. For example, if there is an enumeration type defined as enum Color { RED, BLUE, GREEN };, you can use Color::RED, Color::BLUE, Color::GREEN to represent the values of the enumeration type.
2. By using an enumeration variable, you can define a variable of an enumerated type and assign it one of the enumerative constants. For example, you can define a variable of type Color as color and then assign it Color::RED: Color color = Color::RED;.
3. Integer values are used in enumeration types, where the values of the enumeration type are actually integer constants. Integer values can be used to represent the values of an enumeration type, such as using 0, 1, and 2 to represent Color::RED, Color::BLUE, and Color::GREEN.

It is important to note that the values of an enumeration type are limited and can only be the values defined in the enumeration constants. Using other integer values will result in warnings or errors by the compiler. Additionally, the values of an enumeration type can be compared, assigned, and manipulated similar to integer types.