table of contents
std::is_enum(3) | C++ Standard Libary | std::is_enum(3) |
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)
2022.07.31 | http://cppreference.com |