std::is_bounded_array(3) | C++ Standard Libary | std::is_bounded_array(3) |
NAME¶
std::is_bounded_array - std::is_bounded_array
Synopsis¶
Defined in header <type_traits>
template< class T > (since C++20)
struct is_bounded_array;
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 >
inline constexpr bool is_bounded_array_v = (since C++20)
is_bounded_array<T>::value;
Inherited from std::integral_constant
Member constants¶
value true if T is an array type of known bound, 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_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¶
is_array checks if a type is an array type
(C++11) (class template)
is_unbounded_array checks if a type is an array type of unknown bound
(C++20) (class template)
extent obtains the size of an array type along a specified dimension
(C++11) (class template)
2024.06.10 | http://cppreference.com |