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std::is_null_pointer(3) C++ Standard Libary std::is_null_pointer(3) NAME std::is_null_pointer - std::is_null_pointer Synopsis Defined in header <type_traits> template< class T > (since C++14) struct is_null_pointer; std::is_null_pointer is a UnaryTypeTrait. Checks whether T is the type std::nullptr_t. Provides the member constant value that is equal to true, if T is the type std::nullptr_t, const std::nullptr_t, volatile std::nullptr_t, or const volatile std::nullptr_t. Otherwise, value is equal to false. If the program adds specializations for std::is_null_pointer or std::is_null_pointer_v (since C++17), the behavior is undefined. Template parameters T - a type to check Helper variable template template< class T > (since C++17) inline constexpr bool is_null_pointer_v = is_null_pointer<T>::value; Inherited from std::integral_constant Member constants value true if T is the type std::nullptr_t (possibly cv-quali- fied), false [static] otherwise (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_null_pointer : std::is_same<std::nullptr_t, std::re- move_cv_t<T>> {}; Notes std::is_pointer is false for std::nullptr_t because it is not a built-in pointer type. Feature-test macro Value Std Feature __cpp_lib_is_null_pointer 201309L (C++14) std::is_null_pointer Example // Run this code #include <type_traits> static_assert(std::is_null_pointer_v<decltype(nullptr)>); static_assert(!std::is_null_pointer_v<int*>); static_assert(!std::is_pointer_v<decltype(nullptr)>); static_assert(std::is_pointer_v<int*>); int main() { } See also is_void checks if a type is void (C++11) (class template) is_array checks if a type is an array type (C++11) (class template) is_pointer checks if a type is a pointer type (C++11) (class template) is_enum checks if a type is an enumeration type (C++11) (class template) is_union checks if a type is a union type (C++11) (class template) is_class checks if a type is a non-union class type (C++11) (class template) is_function checks if a type is a function type (C++11) (class template) is_object checks if a type is an object type (C++11) (class template) http://cppreference.com 2024.06.10 std::is_null_pointer(3)
NAME | Synopsis | Template parameters | Member constants | Member functions | Member types | Possible implementation | Notes | Example | See also
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