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std::is_bounded_array

From cppreference.com
< cpp‎ | types
 
 
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Defined in header <type_traits>
template< class T >
struct is_bounded_array;
(since C++20)

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.

The behavior of a program that adds specializations for is_bounded_array or is_bounded_array_v is undefined.

Contents

[edit] Template parameters

T - a type to check

[edit] Helper variable template

template< class T >
inline 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>

[edit] 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 {};

[edit] Notes

Feature testing macro: __cpp_lib_bounded_array_traits

[edit] Example

#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

[edit] See also

(C++11)
checks if a type is an array type
(class template) [edit]
checks if a type is an array type of unknown bound
(class template) [edit]
(C++11)
obtains the size of an array type along a specified dimension
(class template) [edit]