std:: is_member_object_pointer

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

std::is_member_object_pointer is a UnaryTypeTrait .

Checks whether T is a non-static member object pointer. Provides the member constant value which is equal to true , if T is a non-static member object pointer type. Otherwise, value is equal to false .

If the program adds specializations for std::is_member_object_pointer or std::is_member_object_pointer_v , the behavior is undefined.

Template parameters

T - a type to check

Helper variable template

template < class T >
constexpr bool is_member_object_pointer_v = is_member_object_pointer < T > :: value ;
(since C++17)

Inherited from std:: integral_constant

Member constants

value
[static]
true if T is a pointer to member object, 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_member_object_pointer : std::integral_constant<
                                      bool,
                                      std::is_member_pointer<T>::value &&
                                      !std::is_member_function_pointer<T>::value
                                  > {};

Example

Run this code 
#include <iostream>
#include <type_traits>
 
int main()
{
    class C {};
    std::cout << "Is member object pointer?\n" << std::boolalpha
              << std::is_member_object_pointer_v<int(C::*)>
              << ": int(C::*)\n"
              << std::is_member_object_pointer_v<int(C::*)()>
              << ": int(C::*)()\n";
}

Output: 

Is member object pointer?
true: int(C::*)
false: int(C::*)()

See also

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