Home Original page

std::is_array - cppreference.com

From cppreference.com

template< class T > struct is_array;

 (since C++11)

std::is_array is a UnaryTypeTrait.

Checks whether T is an array type. Provides the member constant value which is equal to true, if T is an array type. Otherwise, value is equal to false.

If the program adds specializations for std::is_array or std::is_array_v, the behavior is undefined.

Template parameters

Helper variable template

template< class T > constexpr bool is_array_v = is_array<T>::value;

 (since C++17)

Inherited from std::integral_constant

Member constants

true if T is an array type, false otherwise
(public static member constant)

Member functions

converts the object to bool, returns value
(public member function)
returns value
(public member function)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

Possible implementation

template<class T>
struct is_array : std::false_type {};

template<class T>
struct is_array<T[]> : std::true_type {};

template<class T, std::size_t N>
struct is_array<T[N]> : std::true_type {};

Example

#include <array>
#include <type_traits>

class A {};
static_assert(std::is_array<A>::value == false);
static_assert(std::is_array<A[]>::value == true);
static_assert(std::is_array<A[3]>::value == true);

static_assert(std::is_array<float>::value == false);
static_assert(std::is_array<int>::value == false);
static_assert(std::is_array<int[]>::value == true);
static_assert(std::is_array<int[3]>::value == true);
static_assert(std::is_array<std::array<int, 3>>::value == false);

int main() {}

See also

checks if a type is an array type of known bound
(class template) [edit]
checks if a type is an array type of unknown bound
(class template) [edit]

(C++11)

 obtains the number of dimensions of an array type
(class template) [edit]

(C++11)

 obtains the size of an array type along a specified dimension
(class template) [edit]
removes one extent from the given array type
(class template) [edit]
removes all extents from the given array type
(class template) [edit]