std::is_unbounded_array
Defined in header <type_traits> |
||
---|---|---|
template< class T > struct is_unbounded_array; |
(since C++20) |
Checks whether T
is an array type of unknown bound. Provides the member constant value
which is equal to true
, if T
is an array type of unknown bound. Otherwise, value
is equal to false
.
The behavior of a program that adds specializations for is_unbounded_array
or is_unbounded_array_v
is undefined.
Template parameters
T | - | a type to check |
Helper variable template
template< class T > inline constexpr bool is_unbounded_array_v = is_unbounded_array<T>::value; |
(since C++20) |
Inherited from std::integral_constant
Member constants
value
[static]
|
true if T is an array type of unknown 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_unbounded_array: std::false_type {}; template<class T> struct is_unbounded_array<T[]> : std::true_type {}; |
Notes
Feature testing macro: __cpp_lib_bounded_array_traits
.
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_unbounded_array_v<A> ); OUT( std::is_unbounded_array_v<A[]> ); OUT( std::is_unbounded_array_v<A[3]> ); OUT( std::is_unbounded_array_v<float> ); OUT( std::is_unbounded_array_v<int> ); OUT( std::is_unbounded_array_v<int[]> ); OUT( std::is_unbounded_array_v<int[3]> ); }
Output:
std::is_unbounded_array_v<A> : false std::is_unbounded_array_v<A[]> : true std::is_unbounded_array_v<A[3]> : false std::is_unbounded_array_v<float> : false std::is_unbounded_array_v<int> : false std::is_unbounded_array_v<int[]> : true std::is_unbounded_array_v<int[3]> : false
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 known bound (class template) |
(C++11)
|
obtains the size of an array type along a specified dimension (class template) |
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