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(C++) enum class

An enum class is a C++11 type-safe enumeration. Prefer class enums over plain enums to minimize surprise [1].

Example

Download the Qt Creator project 'CppEnumClass' (zip)

An enum class is a conversion-safe enum:


enum class Color { red  , orange };

enum class Fruit { apple, orange };



int main()

{

  Color c = Color::orange;

  Fruit a = Fruit::orange;

  Fruit b = Color::orange; //Fails

}

Screen output:


cannot convert 'Color' to 'Fruit' in initialization

Technical note: the code shown is compiled successfully using the G++ 4.4.5 compiler, which is supplied with the Qt Creator 2.0.0 IDE.

Advice

Prefer enum classes to enums [1,2]

References

Bjarne Stroustrup. The C++ Programming Language (4th edition). 2013. ISBN: 978-0-321-56384-2. Chapter 8.5. Advice. page 224: '[6] Prefer class enums over "plain" enums to minimize surprises'
Scott Meyers. C++ And Beyond 2012 session: 'Initial thoughts on Effective C++11'. 2012. ' Prefer enum classes to enums'

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.