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std::is_unbounded_array(3)    C++ Standard Libary   std::is_unbounded_array(3)

NAME
       std::is_unbounded_array - std::is_unbounded_array

Synopsis
	  Defined in header <type_traits>
	  template< class T >		   (since C++20)
	  struct is_unbounded_array;

	  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_un-
       bounded_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	     =
       (since C++20)
	  is_unbounded_array<T>::value;

       Inherited from std::integral_constant

Member constants
	  value	    true if T is an array type of unknown bound	, false	other-
       wise
	  [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_unbounded_array: std::false_type {};

	  template<class T>
	  struct is_unbounded_array<T[]> : std::true_type {};

Notes
	  Feature-test macro: __cpp_lib_bounded_array_traits

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_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
	  is_array	   checks if a type is an array	type
	  (C++11)	   (class template)
	  is_bounded_array checks if a type is an array	type of	known bound
	  (C++20)	   (class template)
	  extent	   obtains the size of an array	type along a specified
       dimension
	  (C++11)	   (class template)

http://cppreference.com		  2022.07.31	    std::is_unbounded_array(3)

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