在C ++中的参考初始化 [英] Reference initialization in C++

问题描述

任何人都可以向我解释为什么这两个语句之间有区别。

Can anybody explain to me why there is a difference between these two statements?

class A{};

const A& a = A();         // correct 

A& b = A();               // wrong

它说
类型<$ c的非const引用的无效初始化$ c> A& 从 A

c $ c> const 这里？

Why does const matter here?

推荐答案

非const引用必须初始化为l-值。如果你可以用临时数来初始化它们，那么下面是什么？

Non-const references must be initialised with l-values. If you could initialise them with temporaries, then what would the following do?

int& foo = 5;
foo = 6; // ?!

const 延长裁判员的生命，因为他们是 const ，没有可能性，你会尝试修改不在内存中的东西。例如：

const references have the special property that they extend the life of the referee, and since they are const, there is no possibility that you'll try to modify something that doesn't sit in memory. For example:

const int& foo = 5;
foo = 6; // not allowed, because foo is const.

请记住，引用实际上必须引用某些东西，而不仅仅是临时变量。例如，以下内容有效：

Remember that references actually have to refer to something, not just temporary variables. For example, the following is valid:

int foo = 5;
int& bar = foo;
bar = 6;
assert(foo == 6);

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