NAME¶

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.

The behavior of a program that adds specializations for is_object
or is_object_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_object_v = is_object<T>::value;

Inherited from std::integral_constant

Member constants¶

value true if T is an object 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_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

See also¶

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