Defined in header <type_traits> | ||
|---|---|---|
template< class T > struct is_enum; | (since C++11) |
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.
| T | - | a type to check |
template< class T > inline constexpr bool is_enum_v = is_enum<T>::value; | (since C++17) |
| value
[static] | true if T is an enumeration type, false otherwise (public static member constant) |
| operator bool | converts the object to bool, returns value (public member function) |
| operator()
(C++14) | returns value (public member function) |
| Type | Definition |
|---|---|
value_type | bool |
type | std::integral_constant<bool, value> |
#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
|
(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) |
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