std::is_member_pointer - cppreference.com

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`template< class T > struct is_member_pointer;`		(since C++11)

std::is_member_pointer is a UnaryTypeTrait.

If T is pointer to non-static member object or a pointer to non-static member function, provides the member constant value equal true. For any other type, value is false.

If the program adds specializations for std::is_member_pointer or std::is_member_pointer_v, the behavior is undefined.

Template parameters

Helper variable template

`template< class T > constexpr bool is_member_pointer_v = is_member_pointer<T>::value;`		(since C++17)

Inherited from std::integral_constant

Member constants

true if T is a member pointer type, false otherwise
(public static member constant)

Member functions

	converts the object to `bool`, returns `value` (public member function)
	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_member_pointer_helper : std::false_type {};

template<class T, class U>
struct is_member_pointer_helper<T U::*> : std::true_type {};

template<class T>
struct is_member_pointer : is_member_pointer_helper<typename std::remove_cv<T>::type> {};

Example

#include <cassert>
#include <type_traits>

static_assert(!std::is_member_pointer_v<int*>);

struct S
{
    int i{42};
    int foo() { return 0xF00; }
};
using mem_int_ptr_t = int S::*;
using mem_fun_ptr_t = int (S::*)();
static_assert(std::is_member_pointer_v<mem_int_ptr_t>);
static_assert(std::is_member_pointer_v<mem_fun_ptr_t>);

int main()
{
    S s;

    mem_int_ptr_t pm = &S::i;
    assert(s.i == s.*pm);

    mem_fun_ptr_t pmf = &S::foo;
    assert((s.*pmf)() == s.foo());
}