std::is_scoped_enum

 

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

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 > 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	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 (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)