std::is_reference - cppreference.com

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Elemento definito nell'header `<type_traits>`

`template< class T > struct is_reference;`		(dal C++11)

Se T è un tipo di riferimento (lvalue riferimento o rvalue di riferimento), fornisce il membro costante value true uguali. Per qualsiasi altro tipo, è value false.

Original:

If T is a reference type (lvalue reference or rvalue reference), provides the member constant value equal true. For any other type, value is false.

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Inherited from std::integral_constant

Member constants


	`true` se `T` is a reference type , `false` altrimenti Original: `true` if `T` is a reference type , `false` otherwise The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (pubblico membro statico costante)

Member functions


	converte l'oggetto in `bool`, restituisce `value` Original: converts the object to `bool`, returns `value` The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)

Member types


Tipo Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition

`value_type`	`bool`

`type`	`std::integral_constant<bool, value>`

Possibile implementazione

template <class T> struct is_reference      : std::false_type {};
template <class T> struct is_reference<T&>  : std::true_type {};
template <class T> struct is_reference<T&&> : std::true_type {};

Esempio

#include <iostream>
#include <type_traits>

class A {};

int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_reference<A>::value << '\n';
    std::cout << std::is_reference<A&>::value << '\n';
    std::cout << std::is_reference<A&&>::value << '\n';
    std::cout << std::is_reference<int>::value << '\n';
    std::cout << std::is_reference<int&>::value << '\n';
    std::cout << std::is_reference<int&&>::value << '\n';
}

Output:

false
true
true
false
true
true

Vedi anche


	controlla se un tipo è' lvalue riferimento Original: checks if a type is lvalue reference The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe template) [modifica]

	controlla se un tipo è' rvalue riferimento Original: checks if a type is rvalue reference The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe template) [modifica]