CODEWITHSUNDEEP
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user3165438
user3165438

Reputation: 2661

Initialize enum c++

I create an enum called Types: 

enum  Types {Int,Double,String};

When I create an object and initialize it with one of the enum allowed values I get the following error: "Error: type name is not allowed". 

Types ty = Types.Double;

Any ideas?

Upvotes: 10

Views: 40657

Answers (3)

Columbo
Columbo

Reputation: 60979

In C++, there are two different types of enumerations - scoped and unscoped ones (the former was introduced with C++11). For unscoped ones the names of the enumerators are directly introduced into the enclosing scope.

N3337 §7.2/10

Each enum-name and each unscoped enumerator is declared in the scope that immediately contains the enum-specifier. Each scoped enumerator is declared in the scope of the enumeration. These names obey the scope rules defined for all names in (3.3) and (3.4).

Your enumeration is unscoped, therefore it suffices to write 

Types ty = Double;

For scoped enumerations, as the name suggests, the enumerators are declared in the enumeration scope and have to be qualified with the enumeration-name:

enum class ScopedTypes {Int,Double,String}; 
enum UnscopedTypes     {Int,Double,String}; 

ScopedTypes a = ScopedTypes::Double;
//ScopedTypes b = Double; // error

UnscopedTypes c = UnscopedTypes::Double;
UnscopedTypes d = Double;

Upvotes: 15

Vlad from Moscow
Vlad from Moscow

Reputation: 310990

Either use

Types ty = Double;

or

enum  class Types {Int,Double,String};  
Types ty = Types::Double;

Upvotes: 8

Code-Apprentice
Code-Apprentice

Reputation: 83527

The compiler is complaining about the attempt at qualifying the value Double which is Java's way to do this.

Just do

Types ty = Double;

Upvotes: 4

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