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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

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);
}

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