std::is_pointer (3) - Linux Manuals

std::is_pointer: std::is_pointer

NAME

std::is_pointer - std::is_pointer

Synopsis

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

Checks whether T is a pointer_to_object or a pointer to function (but not a pointer to member/member function). Provides the member constant value which is equal to true, if T is a object/function pointer 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_pointer_v = is_pointer<T>::value;

Inherited from std::integral_constant

Member constants

value true if T is a pointer 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_pointer_helper : std::false_type {};
  template< class T > struct is_pointer_helper<T*> : std::true_type {};
  template< class T > struct is_pointer : is_pointer_helper<typename std::remove_cv<T>::type> {};

Example

// Run this code

  #include <iostream>
  #include <type_traits>

  class A {};

  int main()
  {
      std::cout << std::boolalpha;
      std::cout << std::is_pointer<A>::value << '\n';
      std::cout << std::is_pointer<A *>::value << '\n';
      std::cout << std::is_pointer<A &>::value << '\n';
      std::cout << std::is_pointer<int>::value << '\n';
      std::cout << std::is_pointer<int *>::value << '\n';
      std::cout << std::is_pointer<int **>::value << '\n';
      std::cout << std::is_pointer<int[10]>::value << '\n';
      std::cout << std::is_pointer<std::nullptr_t>::value << '\n';
  }

Output:

  false
  true
  false
  false
  true
  true
  false
  false