C++ Scoped Enumerations

Introduction

The C++11 standard introduces the scoped enumerators.

Unlike the old enumerators, the scoped enumerators do not leak their names into the surrounding scope.

Scoped enums have the following signature: enum class Enumerator_Name {value1, value2 etc} signature.

To define a scoped enum, we write: 

enum class MyEnum 
{ 
    myfirstvalue, 
    mysecondvalue, 
    mythirdvalue 
};

To declare a variable of type enum class (scoped enum) we write: 

enum class MyEnum 
{ 
    myfirstvalue, /*from ww  w . j  av  a  2s.  c  o  m*/
    mysecondvalue, 
    mythirdvalue 
}; 

int main() 
{ 
    MyEnum myenum = MyEnum::myfirstvalue; 
}

To access an enumerator value, we prepend the enumerator with the enum name and a scope resolution operator :: such as MyEnum::myfirstvalue, *MyEnum:: mysecondvalue*, etc.

With these enums, the enumerator names are defined only within the enum internal scope and implicitly convert to underlying types.

We can specify the underlying type for scoped enum: 

enum class MyCharEnum : char 
{ 
    myfirstvalue, 
    mysecondvalue, 
    mythirdvalue 
};

We can also change the initial underlying values of enumerators by specifying the value: 

enum class MyEnum 
{ 
    myfirstvalue = 15, 
    mysecondvalue, 
    mythirdvalue = 30 
};



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