由于c提供对rvalues的引用,即rvalue引用,其主要用于执行移动语义和其他存储器有效任务.但是在下面的例子中,引用是改变文字的值,但是我们知道文字是只读的,所以引用如何改变某些只读变量的值.右值引用是否分配了它自己的内存,或者它只是更改了文字的值？
#include <iostream>
using namespace std;
int main()
{
int a = 5;
int&& b = 3;
int& c = a;
b++;
c++;
cout << " Value for b " << b << " Value for c " << c << endl;
}
其次,当为临时对象分配引用时,引用将使用该对象的数据.但是根据临时对象的定义,它们会在使用它们的表达式结束时被删除.如果该临时对象内存不足,该引用如何作为该临时对象的别名？
解决方法
数字文字不能绑定到任何引用,既不是右值引用也不是左值引用.从概念上讲,数字文字创建一个从文字值初始化的临时对象,这个临时对象可以绑定到右值引用或const左值引用(int const& r = 17;).文字的相关引用似乎是5.1.1 [expr.prim.general]第1段：
A literal is a primary expression. Its type depends on its form (2.14). A string literal is an lvalue; all other literals are prvalues.
将引用直接绑定到临时引用时,它的生命周期会延长,直到引用超出范围.终身问题的相关部分是12.2 [class.temporary]第5段：
The second context is when a reference is bound to a temporary. The temporary to which the reference is bound or the temporary that is the complete object of a subobject to which the reference is bound persists
for the lifetime of the reference except:
- A temporary bound to a reference member in a constructor’s ctor-initializer (12.6.2) persists until the constructor exits.
- A temporary bound to a reference parameter in a function call (5.2.2) persists until the completion of the full-expression containing the call.
- The lifetime of a temporary bound to the returned value in a function return statement (6.6.3) is not extended; the temporary is destroyed at the end of the full-expression in the return statement.
- A temporary bound to a reference in a new-initializer (5.3.4) persists until the completion of the full-expression containing the new-initializer.
