std::is_enum

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

std::is_enum is an UnaryTypeTrait.

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 std::is_enum or std::is_enum_v (since C++17) is undefined.

Template parameters

T - a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants

value
[static]
 true if T is an 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>

Example

#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

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