C++

Reference

<type_traits>

class template
<type_traits>

std::is_reference

template <class T> struct is_reference;
Is reference type

Trait class that identifies whether T is a reference type (either an l-value reference or an r-value reference).

It inherits from integral_constant as being either true_type or false_type.

This is a compound type trait defined with the same behavior as:
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template<class T>
struct is_reference : std::integral_constant < bool,
         is_lvalue_reference<T>::value || is_rvalue_reference<T>::value > {};

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:
operator bool
Returns value (public member function)

Example

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

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_reference:" << std::endl;
  std::cout << "int: " << std::is_reference<int>::value << std::endl;
  std::cout << "int&: " << std::is_reference<int&>::value << std::endl;
  std::cout << "int&&: " << std::is_reference<int&&>::value << std::endl;
  return 0;
}

Output:
is_reference:
int: false
int&: true
int&&: true


See also

is_lvalue_reference
Is lvalue reference (class template)
is_rvalue_reference
Is rvalue reference (class template)
is_pointer
Is pointer (class template)