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

NAME
       std::is_unsigned	- std::is_unsigned

Synopsis
	  Defined in header <type_traits>
	  template< class T >		   (since C++11)
	  struct is_unsigned;

	  If  T	 is an integral	type, provides the member constant value equal
       to true if T(0) <
	  T(-1): this results in true for the unsigned integer types  and  the
       type bool and in
	  false	for the	signed integer types and the floating-point types.

	  For any other	type, value is false.

	  The behavior of a program that adds specializations for is_unsigned
	  or is_unsigned_v
	  (since C++17)	is undefined.

Template parameters
	  T - a	type to	check

	 Helper	variable template

	  template< class T >						(since
       C++17)
	  inline constexpr bool	is_unsigned_v =	is_unsigned<T>::value;

       Inherited from std::integral_constant

Member constants
	  value	   true	if T is	an unsigned integral type , 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
	  namespace detail {
	  template<typename T,bool = std::is_arithmetic<T>::value>
	  struct is_unsigned : std::integral_constant<bool, T(0) < T(-1)> {};

	  template<typename T>
	  struct is_unsigned<T,false> :	std::false_type	{};
	  } // namespace detail

	  template<typename T>
	  struct is_unsigned : detail::is_unsigned<T>::type {};

Example
       // Run this code

	#include <iostream>
	#include <type_traits>

	class A	{};
	enum B : unsigned {};
	enum class C : unsigned	{};

	int main()
	{
	    std::cout << std::boolalpha;
	    std::cout << std::is_unsigned<A>::value << '\n';
	    std::cout << std::is_unsigned<float>::value	<< '\n';
	    std::cout << std::is_unsigned<signed int>::value <<	'\n';
	    std::cout << std::is_unsigned<unsigned int>::value << '\n';
	    std::cout << std::is_unsigned<B>::value << '\n';
	    std::cout << std::is_unsigned<C>::value << '\n';
	}

Output:
	false
	false
	false
	true
	false
	false

See also
	  is_signed	checks if a type is a signed arithmetic	type
	  (C++11)	(class template)
	  is_arithmetic	checks if a type is an arithmetic type
	  (C++11)	(class template)
	  make_signed	makes the given	integral type signed
	  (C++11)	(class template)
	  make_unsigned	makes the given	integral type unsigned
	  (C++11)	(class template)

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

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