std:: is_fundamental

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C++
Metaprogramming library
Type traits
Type categories
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
is_fundamental
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++11)
(C++11)
(C++14)
(C++11)
(C++17)
(C++23)
(C++11) (deprecated in C++26)
(C++11)
(C++11)
(C++11) ( until C++20* )
(C++11) (deprecated in C++20)
(C++11)
(C++11)
(C++20)
(C++20)
(C++23)
(C++17)
Type trait constants
(C++11) (C++17) (C++11) (C++11)
Metafunctions
(C++17)
(C++17)
(C++17)
Supported operations
Relationships and property queries
Type modifications
Type transformations
(C++11) (deprecated in C++23)
(C++11) (deprecated in C++23)
(C++11)
(C++20)
(C++11)
(C++17)

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

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

Inherited from std:: integral_constant

Member constants

value
[static]
true if T is a fundamental type, false otherwise
(public static member constant)

Member functions

operator bool
converts the object to bool , returns value
(public member function)
operator()
(C++14)
returns value
(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

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