c++ - 什么是常数引用？ (不是对常量的引用)

Question

为什么常量引用的行为方式与常量指针不同，以便我可以实际更改它们指向的对象？它们真的看起来像是另一个简单的变量声明。为什么我会使用它们？

这是我运行的一个简短示例，它编译并运行没有错误:

int main (){
    int i=0;
    int y=1;    
    int&const icr=i;
    icr=y;          // Can change the object it is pointing to so it's not like a const pointer...
    icr=99;         // Can assign another value but the value is not assigned to y...
    int x=9;
    icr=x;
    cout<<"icr: "<<icr<<", y:"<<y<<endl; 
}

Answer 1

最清楚的答案。 Does “X& const x” make any sense?

No, it is nonsense

To find out what the above declaration means, read it right-to-left:“x is a const reference to a X”. But that is redundant — referencesare always const, in the sense that you can never reseat a referenceto make it refer to a different object. Never. With or without theconst.

In other words, “X& const x” is functionally equivalent to “X& x”.Since you’re gaining nothing by adding the const after the &, youshouldn’t add it: it will confuse people — the const will make somepeople think that the X is const, as if you had said “const X& x”.