std::is_unsigned

 

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is_default_constructibleis_trivially_default_constructibleis_nothrow_default_constructible (C++11)(C++11)(C++11)
is_copy_constructibleis_trivially_copy_constructibleis_nothrow_copy_constructible (C++11)(C++11)(C++11)
is_move_constructibleis_trivially_move_constructibleis_nothrow_move_constructible (C++11)(C++11)(C++11)
is_assignableis_trivially_assignableis_nothrow_assignable (C++11)(C++11)(C++11)
is_copy_assignableis_trivially_copy_assignableis_nothrow_copy_assignable (C++11)(C++11)(C++11)
is_move_assignableis_trivially_move_assignableis_nothrow_move_assignable (C++11)(C++11)(C++11)
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Defined in header <type_traits>
template< class T > struct is_unsigned;		(since C++11)

If T is an unsigned arithmetic type, provides the member constant value equal true. For any other type, value is false.

Template parameters

T

-

a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants

value [static]

true if T is an unsigned arithmetic type , 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

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 (C++11)	checks if a type is signed arithmetic type (class template)
is_floating_point (C++11)	checks if a type is floating-point type (class template)
is_integral (C++11)	checks if a type is integral type (class template)
make_signed (C++11)	makes the given integral type signed (class template)
make_unsigned (C++11)	makes the given integral type unsigned (class template)
std::experimental::is_unsigned_v (library fundamentals TS)	variable template alias of std::is_unsigned::value (variable template)