std::is_lvalue_reference

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Defined in header <type_traits>
template< class T >
struct is_lvalue_reference;
 （C++11 起）
T是一个左值的引用类型，提供成员value等于true。对于任何其他类型，value是false.
Original:
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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目录

Inherited from std::integral_constant

Member constants

value
[静态的] </ SPAN></div></div>
true如果 T is an lvalue reference type ，false其他方式
Original:
true if T is an lvalue reference type , false otherwise
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（公共静态成员常量）

Member functions

operator bool
转换的对象bool，返回value
Original:
converts the object to bool, returns value
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（公共成员函数）

Member types

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

</div>

[编辑] 可能的实现

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

[编辑] 为例

#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';
}

Output: 

false
true
false
false
true
false

[编辑] 另请参阅

（C++11）
如果一个类型的检查是“左值引用”或“右值引用'
Original:
checks if a type is either lvalue reference or rvalue reference
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（类模板） [edit]
（C++11）
检查，如果一个类型是“右值引用”
Original:
checks if a type is rvalue reference
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（类模板） [edit]
来自“http://zh.cppreference.com/mwiki/index.php?title=cpp/types/is_lvalue_reference&oldid=27420”