enum class (C++11)

In a Nutshell

Scoped enumerations that resolve the issues of traditional enum types polluting the global namespace and implicitly converting to integers.

Header

No header required (language keyword)

Core API Cheat Sheet

Operation	Signature	Description
Declaration	enum class Name { A, B };	Basic scoped enum; underlying type defaults to int
Specify Underlying Type	enum class Name : type { A, B };	Fixed underlying type to save memory
Access Enumerators	Name::A	Must be accessed via scope operator
Cast to Integer	static_cast<int>(Name::A)	Explicit cast required; no implicit conversion
Opaque Declaration	enum class Name : type;	Forward declaration; underlying type must be specified
using enum	using enum Name;	(C++20) Injects enumerators into the current scope

Minimal Example

enum class Color : uint8_t { Red, Green, Blue };

auto led = Color::Red;

// led = 0;                 // Error: no implicit conversion
if (led == Color::Green) {  // Type-safe comparison
    // ...
}

int value = static_cast<int>(led); // Explicit cast

Embedded Applicability: High

• Specifying the underlying type (e.g., uint8_t, uint32_t) allows precise control over memory usage, which is ideal for protocol parsing and register mapping.
• Zero runtime overhead; fully resolved at compile time.
• Eliminates naming conflicts, making it suitable for modular development in large embedded projects.
• Explicit type conversion prevents accidental integer comparisons, enhancing code safety.

Compiler Support

GCC	Clang	MSVC
4.7	3.1	2010

See Also

• cppreference: Enumeration declaration

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