NAME¶

std::is_scoped_enum - std::is_scoped_enum

Synopsis¶

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

std::is_scoped_enum is a UnaryTypeTrait.

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.

If the program adds specializations for std::is_scoped_enum or
std::is_scoped_enum_v, the behavior is undefined.

Template parameters¶

T - a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants¶

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

Member functions¶

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

Member types¶

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

Notes¶

Feature-test macro Value Std Feature
__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¶

// Run this code

#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¶

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