< cpp‎ | types
Metaprogramming library
Type traits
Type categories
Type properties
(C++11)(until C++20*)
(C++11)(deprecated in C++20)
Type trait constants
Supported operations
Relationships and property queries
Type modifications
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)

(C++11)(until C++20*)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
Defined in header <type_traits>
template< class T >
struct is_final;
(since C++14)

std::is_final is a UnaryTypeTrait.

If T is a final class, provides the member constant value equal true. For any other type, value is false.

If T is an incomplete class type, the behavior is undefined.

If the program adds specializations for std::is_final or std::is_final_v(since C++17), the behavior is undefined.


[edit] Template parameters

T - a type to check

[edit] Helper variable template

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

Inherited from std::integral_constant

Member constants

true if T is a final class type, false otherwise
(public static member constant)

Member functions

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

Member types

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

[edit] Notes

std::is_final is introduced by the resolution of LWG issue 2112.

A union can be declared final (and std::is_final will detect that), even though unions cannot be used as bases in any case.

Feature-test macro Value Std Feature
__cpp_lib_is_final 201402L (C++14) std::is_final

[edit] Example

#include <type_traits>
class A {};
static_assert(std::is_final_v<A> == false);
class B final {};
static_assert(std::is_final_v<B> == true);
union U final
    int x;
    double d;
static_assert(std::is_final_v<U> == true);
int main()

[edit] See also

checks if a type is a non-union class type
(class template) [edit]
checks if a type is a polymorphic class type
(class template) [edit]