enumerated

Enumerated, as an adjective, means listed or counted in a sequence. In mathematics and computer science, enumeration refers to listing the elements of a set. The term is used in several related concepts, including enumerated types in programming, which constrain a value to a finite set of named constants.

Enumerated type, or enum, is a data type that defines a fixed set of named values called enumerators. Enums are used to represent discrete categories or states and to improve code readability and safety by restricting variables to valid values.

Implementation varies by language. In C and C++, enums define integral constants; the underlying type is typically int, with values starting at 0 by default unless overridden. C++11 introduces scoped enums (enum class) that are strongly typed and do not implicitly convert to integers. In Java and C#, enums are full-fledged types that behave like classes with methods and fields and are type-safe. In Python, the enum module provides classes such as Enum for defining named constants. In Rust and Swift, enums are algebraic data types that can carry additional data with each variant.

Beyond programming, enumeration is a common process of counting and listing items. It underpins data modeling, user interface choices, and algorithms that require finite, named options.