Std::is_object (3) Linux Manual Page

std::is_object – std::is_object

Synopsis

Defined in header<type_traits>

    template <class T>
    (since C++ 11)

        struct is_object;

If T is an object_type (that is any possibly cv-qualified type other than function, reference, or void types), provides the member constant value equal true. For any other type, value is false.

Template parameters

T – a type to check

Helper variable template

template< class T > (since C++17)
inline constexpr bool is_object_v = is_object<T>::value;

Inherited from std::integral_constant

Member constants

value true if T is an object type , false otherwise
(public static member constant)
[static]

Member functions

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

operator() returns value
(public member function)
(C++14)

Member types

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

Possible implementation

  template< class T>
  struct is_object : std::integral_constant<bool,
                       std::is_scalar<T>::value ||
                       std::is_array<T>::value ||
                       std::is_union<T>::value ||
                       std::is_class<T>::value> {};

Example

// Run this code

#include <iostream>

#include <type_traits>
int main()
{
    class cls
    {
    };
    std::cout << std::boolalpha;
    std::cout << std::is_object<int>::value << '\n';
    std::cout << std::is_object<int &>::value << '\n';
    std::cout << std::is_object<cls>::value << '\n';
    std::cout << std::is_object<cls &>::value << '\n';
}

Output:

  true
  false
  true
  false

std::is_object (3) Linux Manual Page