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std::is_pointer

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

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 >
inline constexpr bool is_pointer_v = is_pointer<T>::value;
 (since C++17)

Inherited from std::integral_constant

Member constants

value
[static]
 true if T is a pointer 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>

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

#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

See also

(C++11)
 checks if a type is a pointer to an non-static member function or object
(class template)
(C++11)
 checks if a type is a pointer to a non-static member object
(class template)
(C++11)
 checks if a type is a pointer to a non-static member function
(class template)
(C++11)
 checks if a type is an array type
(class template)
(C++11)
 checks if a type is a scalar type
(class template)

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