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
.
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 <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'; }
Output:
false true true false false true true
(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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