std::is_unsigned (3) - Linux Man Pages

std::is_unsigned: std::is_unsigned

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 arithmetic type, provides the member constant value equal 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.

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 arithmetic type , false otherwise
         (public static member constant)
[static]

Member functions


              converts the object to bool, returns value
operator bool (public member function)


operator() returns value
              (public member function)
(C++14)

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
              (class template)
(C++11)


is_arithmetic checks if a type is an arithmetic type
              (class template)
(C++11)


make_signed makes the given integral type signed
              (class template)
(C++11)


make_unsigned makes the given integral type unsigned
              (class template)
(C++11)