std::is_array

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Defined in header <type_traits>
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

T - a type to check

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

value
[static]
 true if T is an array 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>

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

Run this code
#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

(C++20)
 checks if a type is an array type of known bound
(class template)
(C++20)
 checks if a type is an array type of unknown bound
(class template)
(C++11)
 obtains the number of dimensions of an array type
(class template)
(C++11)
 obtains the size of an array type along a specified dimension
(class template)
(C++11)
 removes one extent from the given array type
(class template)
(C++11)
 removes all extents from the given array type
(class template)
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