std::is_unsigned
Defined in header <type_traits>
|
||
template< class T > struct is_unsigned; |
(since C++11) | |
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 > inline 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
(C++11) |
checks if a type is a signed arithmetic type (class template) |
(C++11) |
checks if a type is an arithmetic type (class template) |
(C++11) |
makes the given integral type signed (class template) |
(C++11) |
makes the given integral type unsigned (class template) |