# std::is_pointer

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< cpp‎ | types

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

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

### See also

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

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