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std::is_lvalue_reference

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C++
 
Утилиты библиотеки
 
Поддержка типов
Основные типы
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Basic types
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Основные типы
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С числовым ограничивает интерфейс
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(C++11)
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is_move_assignable
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(C++11)
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(C++11)
(C++11)
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Введите черта констант
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Type trait constants
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integral_constant(C++11)
 
Заголовочный файл <type_traits>
template< class T >
struct is_lvalue_reference;
 (начиная с C++11)
Если T является тип именующее ссылки, обеспечивает постоянный член value равных true. Для любого другого типа, value является false.
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If T is an lvalue reference type, provides the member constant value equal true. For any other type, value is false.
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Содержание

Унаследован от std::integral_constant

Member constants

value
[static]
true если T is an lvalue reference type , false иначе
Original:
true if T is an lvalue reference type , false otherwise
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(public static константа-член)

Member functions

operator bool
преобразует объект в bool, возвращает value
Original:
converts the object to bool, returns value
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(public функция-член)

Member types

Type
Original:
Type
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 Definition
value_type bool
type std::integral_constant<bool, value>

[править] Возможная реализация

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

[править] Пример

#include <iostream>
#include <type_traits>
 
class A {};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_lvalue_reference<A>::value << '\n';
    std::cout << std::is_lvalue_reference<A&>::value << '\n';
    std::cout << std::is_lvalue_reference<A&&>::value << '\n';
    std::cout << std::is_lvalue_reference<int>::value << '\n';
    std::cout << std::is_lvalue_reference<int&>::value << '\n';
    std::cout << std::is_lvalue_reference<int&&>::value << '\n';
}

Вывод: 

false
true
false
false
true
false

[править] См. также

(C++11)
проверяет, является ли тип либо именующее ссылкой или' RValue ссылки
Original:
checks if a type is either lvalue reference or rvalue reference
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(шаблон класса) [edit]
(C++11)
проверяет, является ли тип RValue ссылкой
Original:
checks if a type is rvalue reference
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(шаблон класса) [edit]
Источник — «http://ru.cppreference.com/mwiki/index.php?title=cpp/types/is_lvalue_reference&oldid=31413»