class template
<type_traits>

std:: is_unsigned

template <class T> struct is_unsigned;
Is unsigned type

Trait class that identifies whether T is an unsigned arithmetic type.

It inherits from integral_constant as being either true_type or false_type, depending on whether T is considered unsigned.

A type, T, is considered unsigned by this class if it's an arithmetic type (i.e., a fundamental integral or floating point type) and the following is true:
 
T(0) < T(-1)


Template parameters

T
A type.

Member types

Inherited from integral_constant:
member typedefinition
value_typebool
typeeither true_type or false_type

Member constants

Inherited from integral_constant:
member constantdefinition
valueeither true or false

Member functions

Inherited from integral_constant:

Example

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// is_unsigned example
#include <iostream>
#include <type_traits>

struct A { };
enum class B : int { x,y,z };

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_unsigned:" << std::endl;
  std::cout << "int: " << std::is_unsigned<int>::value << std::endl;
  std::cout << "unsigned long: " << std::is_unsigned<unsigned long>::value << std::endl;
  std::cout << "A: " << std::is_unsigned<A>::value << std::endl;
  std::cout << "B: " << std::is_unsigned<B>::value << std::endl;
  return 0;
}


Output:
is_signed:
int: false
unsigned long: true
A: false
B: false

See also

<type_traits>