# std::is_enum

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< 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

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

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