std::is_array

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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.

Contents

[edit] Template parameters

T - a type to check

[edit] 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>

[edit] 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 {};

[edit] Example

#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[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[3]>::value << '\n';
}

Output:

false
true
false
false
true

[edit] See also

(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)
removes one extent from the given array type
(class template)
removes all extents from the given array type
(class template)
(library fundamentals TS)
variable template alias of std::is_array::value
(variable template)