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std::is_scoped_enum

Defined in header <type_traits>
template< class T >
struct is_scoped_enum;
(since C++23)

Checks whether T is a scoped enumeration type. Provides the member constant value which is equal to true, if T is a scoped enumeration type. Otherwise, value is equal to false.

The behavior of a program that adds specializations for is_scoped_enum or is_scoped_enum_v is undefined.

Template parameters

T - a type to check

Helper variable template

template< class T >
inline constexpr bool is_scoped_enum_v = is_scoped_enum<T>::value;
(since C++23)

Inherited from std::integral_constant

Member constants

value
[static]
true if T is a scoped enumeration type, false otherwise
(public static member constant)

Member functions

operator bool
converts the object to bool, returns value
(public member function)
operator()
(C++14)
returns value
(public member function)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

Notes

Feature-test macro Value Std Comment
__cpp_lib_is_scoped_enum 202011L (C++23) std::is_scoped_enum

Possible implementation

template<typename E>
struct is_scoped_enum : std::bool_constant<requires
{
    requires std::is_enum_v<E>;
    requires !std::is_convertible_v<E, std::underlying_type_t<E>>;
}>
{};

Example

#include <type_traits>
 
class A {};
 
enum E {};
 
enum struct Es { oz };
 
enum class Ec : int {};
 
int main()
{
    static_assert(std::is_scoped_enum_v<A> == false);
    static_assert(std::is_scoped_enum_v<E> == false);
    static_assert(std::is_scoped_enum_v<Es> == true);
    static_assert(std::is_scoped_enum_v<Ec> == true);
    static_assert(std::is_scoped_enum_v<int> == false);
}

See also

(C++11)
checks if a type is an integral type
(class template)
(C++11)
checks if a type is an arithmetic type
(class template)
(C++11)
checks if a type is a scalar type
(class template)
(C++11)
checks if a type is an enumeration type
(class template)

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