NAME¶

std::is_enum - std::is_enum

Synopsis¶

Defined in header <type_traits>
template< class T > (since C++11)
struct is_enum;

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

The behavior of a program that adds specializations for is_enum
or is_enum_v
(since C++17) is undefined.

Template parameters¶

T - a type to check

Helper variable template

template< class T > (since C++17)
inline constexpr bool is_enum_v = is_enum<T>::value;

Inherited from std::integral_constant

Member constants¶

value true if T is an 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>

Example¶

// Run this code

#include <iostream>
#include <type_traits>

struct A { enum E { }; };

enum E {};

enum class Ec : int {};

int main()
{
std::cout
<< std::boolalpha
<< std::is_enum<A>::value << '\n'
<< std::is_enum<E>::value << '\n'
<< std::is_enum<A::E>() << '\n'
<< std::is_enum_v<int> << '\n' // Uses helper variable template (C++17)
<< std::is_enum_v<Ec> << '\n'; // Uses helper variable template (C++17)
}

Output:¶

false
true
true
false
true

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_scoped_enum checks if a type is a scoped enumeration type
(C++23) (class template)