NAME¶

std::is_fundamental - std::is_fundamental

Synopsis¶

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

std::is_fundamental is a UnaryTypeTrait.

If T is a fundamental type (that is, arithmetic type, void, or nullptr_t), provides
the member constant value equal true. For any other type, value is false.

If the program adds specializations for std::is_fundamental or
std::is_fundamental_v, the behavior is undefined.

Template parameters¶

T - a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants¶

value true if T is a fundamental 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_fundamental
: std::integral_constant<
bool,
std::is_arithmetic<T>::value ||
std::is_void<T>::value ||
std::is_same<std::nullptr_t, typename std::remove_cv<T>::type>::value
// you can also use 'std::is_null_pointer<T>::value' instead in C++14
> {};

Example¶

// Run this code

#include <type_traits>

static_assert(std::is_fundamental_v<int> == true);
static_assert(std::is_fundamental_v<int&> == false);
static_assert(std::is_fundamental_v<int*> == false);
static_assert(std::is_fundamental_v<void> == true);
static_assert(std::is_fundamental_v<void*> == false);
static_assert(std::is_fundamental_v<float> == true);
static_assert(std::is_fundamental_v<float&> == false);
static_assert(std::is_fundamental_v<float*> == false);
static_assert(std::is_fundamental_v<std::nullptr_t> == true);
static_assert(std::is_fundamental_v<std::is_fundamental<int>> == false);

class A {};
static_assert(std::is_fundamental_v<A> == false);
static_assert(std::is_fundamental_v<std::is_fundamental<A>::value_type>);

int main() {}

See also¶

is_compound checks if a type is a compound type
(C++11) (class template)
is_arithmetic checks if a type is an arithmetic type
(C++11) (class template)
is_void checks if a type is void
(C++11) (class template)
is_null_pointer checks if a type is std::nullptr_t
(C++14) (class template)