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std::is_enum

From cppreference.com
< cpp‎ | types
 
 
Metaprogramming library
Type traits
Type categories
(C++11)
(C++14)  
(C++11)
(C++11)
is_enum
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++14)
(C++11)
(C++11)(until C++20*)
(C++11)(deprecated in C++20)
(C++11)
Type trait constants
Metafunctions
(C++17)
Supported operations
Relationships and property queries
Type modifications
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(C++11)(until C++20*)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
 
Defined in header <type_traits>
template< class T >
struct is_enum;
(since C++11)

std::is_enum is a 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.

If the program adds specializations for std::is_enum or std::is_enum_v, the behavior is undefined.

Contents

[edit] Template parameters

T - a type to check

[edit] 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>

[edit] Example

#include <type_traits>
 
struct A { enum E {}; };
static_assert(std::is_enum_v<A> == false);
static_assert(std::is_enum_v<A::E> == true);
 
enum E {};
static_assert(std::is_enum_v<E> == true);
 
enum class Ec : int {};
static_assert(std::is_enum_v<Ec> == true);
 
static_assert(std::is_enum_v<int> == false);
 
int main() {}

[edit] See also

checks if a type is an integral type
(class template) [edit]
checks if a type is an arithmetic type
(class template) [edit]
(C++11)
checks if a type is a scalar type
(class template) [edit]
checks if a type is a scoped enumeration type
(class template) [edit]