C++

Reference

<type_traits>

class template
<type_traits>

std::make_unsigned

template <class T> struct make_unsigned;
Make unsigned
Obtains the unsigned type corresponding to T, keeping any cv-qualifiers.

The transformed type is aliased as member type make_unsigned::type as follows:
  • If T is a signed integral type, this is the corresponding unsigned type.
  • If T is already an unsigned integral type, this is T unchanged.
  • If T is an enumeration type, this is the smallest unsigned integer type with the same size as T (as per sizeof operator).

Notice that this class merely obtains a type using another type as model, but it does not transform values or objects between those types. To explicitly cast an integral type to its unsigned equivalent, you can use static_cast.

Template parameters

T
An integer type (except bool), or an enumeration type.

Member types

member typedefinition
typeUnsigned type corresponding to T.

Example

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// make_unsigned
#include <iostream>
#include <type_traits>

enum ENUM1 {a,b,c};
enum class ENUM2 : char {a,b,c};

int main() {
  typedef std::make_unsigned<int>::type A;                // unsigned int
  typedef std::make_unsigned<unsigned>::type B;           // unsigned int
  typedef std::make_unsigned<const unsigned>::type C;     // const unsigned int
  typedef std::make_unsigned<ENUM1>::type D;              // unsigned int
  typedef std::make_unsigned<ENUM2>::type E;              // unsigned char

  std::cout << std::boolalpha;
  std::cout << "typedefs of unsigned int:" << std::endl;
  std::cout << "A: " << std::is_same<unsigned,A>::value << std::endl;
  std::cout << "B: " << std::is_same<unsigned,B>::value << std::endl;
  std::cout << "C: " << std::is_same<unsigned,C>::value << std::endl;
  std::cout << "D: " << std::is_same<unsigned,D>::value << std::endl;
  std::cout << "E: " << std::is_same<unsigned,E>::value << std::endl;

  return 0;
}

Output:
typedefs of unsigned int:
A: true
B: true
C: false
D: true
E: false


See also

make_signed
Make signed (class template)
is_unsigned
Is unsigned type (class template)
add_const
Add const qualification (class template)