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) or a cv-qualified version thereof. Provides the member
constant value which is equal to true, if T is a object/function pointer type.
Otherwise, value is equal to false.

The behavior of a program that adds specializations for is_pointer
or is_pointer_v
(since C++17) is undefined.

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
[static] (public static member constant)

Member functions¶

operator bool converts the object to bool, returns value
(public member function)
operator() returns value
(C++14) (public member function)

Member types¶

Type Definition
value_type bool
type std::integral_constant<bool, value>

Possible implementation¶

template<class T>
struct is_pointer : std::false_type {};

template<class T>
struct is_pointer<T*> : std::true_type {};

template<class T>
struct is_pointer<T* const> : std::true_type {};

template<class T>
struct is_pointer<T* volatile> : std::true_type {};

template<class T>
struct is_pointer<T* const volatile> : std::true_type {};

Example¶

// Run this code

#include <type_traits>

int main()
{
class A {};

static_assert(
not std::is_pointer<A>::value
&& not std::is_pointer_v<A> // same thing as above, but in C++17!
&& not std::is_pointer<A>() // same as above, using inherited operator bool
&& not std::is_pointer<A>{} // ditto
&& not std::is_pointer<A>()() // same as above, using inherited operator()
&& not std::is_pointer<A>{}() // ditto
&& std::is_pointer<A *>::value
&& std::is_pointer<A const * volatile>()
&& not std::is_pointer<A &>::value
&& not std::is_pointer<int>::value
&& std::is_pointer<int *>::value
&& std::is_pointer<int **>::value
&& not std::is_pointer<int[10]>::value
&& not std::is_pointer<std::nullptr_t>::value
);
}

See also¶

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