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.
| T | - | a type to check |
template< class T > inline constexpr bool is_object_v = is_object<T>::value; | (since C++17) |
| value
[static] | true if T is an object type , false otherwise (public static member constant) |
| operator bool | converts the object to bool, returns value (public member function) |
| operator()
(C++14) | returns value (public member function) |
| Type | Definition |
|---|---|
value_type | bool |
type | std::integral_constant<bool, value> |
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> {}; |
#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
|
(C++11) | checks if a type is a scalar type (class template) |
|
(C++11) | checks if a type is an array type (class template) |
|
(C++11) | checks if a type is an union type (class template) |
|
(C++11) | checks if a type is a non-union class type (class template) |
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