To define a set of named constants that improve code readability and type safety by restricting a variable to a predefined set of values.

To communicate a fixed set of related constant values within a program's type system, enabling self-documenting code and compile-time safety.

When a variable can only take on a limited set of known values, such as days of the week, status codes, or configuration options.

Used in programming languages that support enumerated types (e.g., C, C++, Java, C#, Rust, Swift) to model discrete state spaces, options, or categories.

enum Identifier { Enumerator1, Enumerator2, ... }

The enum keyword followed by an identifier, braces enclosing a comma-separated list of enumerators.

Identifier (enum name), EnumeratorList (comma-separated enumerator names, optionally with explicit values)

• class
• struct
• switch
• match
• enum class
• scoped enum
• underlying type

• struct
• class
• typedef
• #define (in C)
• const variables

Treating enum values as plain integers without casting, forgetting to handle all enum cases in switch statements, assuming enum values start at zero, using enums for large or dynamic sets of values.

struct (groups data), class (behavior + data), typedef (type alias), #define macro (untyped constants), option type / algebraic data type (more expressive)

Coming from C: may treat enum values as plain integers without explicit casting → In strongly typed languages like Rust or Scala, enum variants are not interchangeable with integers and require explicit conversion or pattern matching.

• enum
• bitmask
• option type
• algebraic data type

Do not use enums for large or dynamic sets of values; prefer maps or databases; Enums are compile‑time constants with zero runtime overhead in most languages; Adding, removing, or reordering enum members can break binary or serialization compatibility.

Using enums improves code readability, prevents invalid states, and enables compiler exhaustiveness checking in pattern matching.

Think of an enum as a restaurant menu: only the listed dishes can be ordered, preventing you from asking for something that isn’t offered.

Some languages provide scoped enums (enum class) to avoid name pollution and support forward declarations.

Learn about scoped enums (enum class) and bitmask patterns for flag combinations.