std::is_bounded_array
From cppreference.com
| Defined in header <type_traits>
|
||
| template< class T > struct is_bounded_array; |
(since C++20) | |
std::is_bounded_array is a UnaryTypeTrait.
Checks whether T is an array type of known bound. Provides the member constant value which is equal to true, if T is an array type of known bound. Otherwise, value is equal to false.
If the program adds specializations for std::is_bounded_array or std::is_bounded_array_v, the behavior is undefined.
Template parameters
| T | - | a type to check |
Helper variable template
| template< class T > constexpr bool is_bounded_array_v = is_bounded_array<T>::value; |
(since C++20) | |
Inherited from std::integral_constant
Member constants
| value [static] |
true if T is an array type of known bound, 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_bounded_array : std::false_type {}; template<class T, std::size_t N> struct is_bounded_array<T[N]> : std::true_type {}; |
Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_bounded_array_traits |
201902L |
(C++20) | std::is_bounded_array, std::is_unbounded_array
|
Example
Run this code
#include <iostream> #include <type_traits> #define OUT(...) std::cout << #__VA_ARGS__ << " : " << __VA_ARGS__ << '\n' class A {}; int main() { std::cout << std::boolalpha; OUT(std::is_bounded_array_v<A>); OUT(std::is_bounded_array_v<A[]>); OUT(std::is_bounded_array_v<A[3]>); OUT(std::is_bounded_array_v<float>); OUT(std::is_bounded_array_v<int>); OUT(std::is_bounded_array_v<int[]>); OUT(std::is_bounded_array_v<int[3]>); }
Output:
std::is_bounded_array_v<A> : false std::is_bounded_array_v<A[]> : false std::is_bounded_array_v<A[3]> : true std::is_bounded_array_v<float> : false std::is_bounded_array_v<int> : false std::is_bounded_array_v<int[]> : false std::is_bounded_array_v<int[3]> : true
See also
| (C++11) |
checks if a type is an array type (class template) |
| (C++20) |
checks if a type is an array type of unknown bound (class template) |
| (C++11) |
obtains the size of an array type along a specified dimension (class template) |