C++

Reference

<type_traits>

class template
<type_traits>

std::add_rvalue_reference

template <class T> struct add_rvalue_reference;
Add rvalue reference
Obtains the rvalue reference type that refers to T.

The transformed type is aliased as member type add_rvalue_reference::type as follows:

  • If T is an object or function type, this is T&&.
  • Otherwise (i.e., T is void or an lvalue reference or already an rvalue reference), it is T unchanged.

Notice that this class merely obtains a type using another type as model, but it does not transform values or objects between those types.

Template parameters

T
A type.

Member types

member typedefinition
typeIf T is an object or function type: T&&
Otherwise: T

Example

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// add_rvalue_reference
#include <iostream>
#include <type_traits>

int main() {
  typedef std::add_rvalue_reference<int>::type A;    // int&&
  typedef std::add_rvalue_reference<int&>::type B;   // int&  (no change)
  typedef std::add_rvalue_reference<int&&>::type C;  // int&& (no change)
  typedef std::add_rvalue_reference<int*>::type D;   // int*&&

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

  return 0;
}

Output:
typedefs of int&&:
A: true
B: false
C: true
D: false


See also

remove_reference
Remove reference (class template)
add_lvalue_reference
Add lvalue reference (class template)
add_pointer
Add pointer (class template)
add_const
Add const qualification (class template)