std::is_array (3) - Linux Manuals

std::is_array: std::is_array

NAME

std::is_array - std::is_array

Synopsis

Defined in header <type_traits>
template< class T > (since C++11)
struct is_array;

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.

Template parameters

T - a type to check

Helper variable template

template< class T > (since C++17)
inline constexpr bool is_array_v = is_array<T>::value;

Inherited from std::integral_constant

Member constants

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

Member functions

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

operator() returns value
              (public member function)
(C++14)

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 <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