Defined in header <type_traits> | ||
|---|---|---|
template< class T > struct is_array; | (since C++11) |
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.
The behavior of a program that adds specializations for is_array or is_array_v (since C++17) is undefined.
| T | - | a type to check |
template< class T > inline constexpr bool is_array_v = is_array<T>::value; | (since C++17) |
| value
[static] | true if T is an array 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> |
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 {}; |
#include <array>
#include <iostream>
#include <type_traits>
class A {};
int main()
{
std::cout << std::boolalpha;
std::cout << std::is_array<A>::value << '\n';
std::cout << std::is_array<A[]>::value << '\n';
std::cout << std::is_array<A[3]>::value << '\n';
std::cout << std::is_array<float>::value << '\n';
std::cout << std::is_array<int>::value << '\n';
std::cout << std::is_array<int[]>::value << '\n';
std::cout << std::is_array<int[3]>::value << '\n';
std::cout << std::is_array<std::array<int, 3>>::value << '\n';
}Output:
false true true false false true true false
|
(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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