std::is_object

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

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

a type to check

Helper variable template

template< class T >
inline constexpr bool is_object_v = is_object<T>::value;

(since C++17)

Inherited from std::integral_constant

Member constants

value

[static]

true if T is an object 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_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

#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

is_scalar (C++11)	checks if a type is a scalar type (class template)
is_array (C++11)	checks if a type is an array type (class template)
is_union (C++11)	checks if a type is an union type (class template)
is_class (C++11)	checks if a type is a non-union class type (class template)