定义这两个类typedef map<C, B::iterator>一种 ;typedef list<D, A::iterator>乙“? [英] To define these two class &quot; typedef map&lt;C, B::iterator&gt; A ; typedef list&lt;D, A::iterator&gt; B &quot;?

问题描述

定义这两个类

typedef map<C, B::iterator> A;
typedef list<D, A::iterator> B;

A 类和 B 类相互包含彼此的迭代器.编译器抱怨上述语句.如何解决问题?

The class A and B mutual contain each other's iterator. The compiler complains about above statement. How to solve the problem ?

iammilind 说这是不可能的.但是这个逻辑关系就出现了，比如一个优先级队列.那么有人有解决方法吗?

iammilind says it is impossible. but this logic relationship appears, for example a priority queue. So any one have workaround?

推荐答案

很遗憾，不可能.
A 和 B 是相互依赖的，因此必须至少向前声明其中一个以支持另一个.
但是typedef 类型不能被前向声明为class/struct.

Unfortunately, it's not possible.
A and B are interdependent, so at least one of them has to be forward declared to support the other.
But the typedef types cannot be forward declared as class/struct.

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