我的重载运算符有什么问题＆lt;＆lt;功能？

Question

ostream & operator<<(ostream &out, const IntList &rhs)
{
    IntNode *i = rhs.head;
    out << rhs.head;
    while (rhs.head != 0)
    {
        out << " " << i;
        i = rhs.head->next;
    }

    return out;
}

程序编译成功，但不打印任何内容。可能是什么问题？

Answer 1

I assume that the input list is empty, therefore rhs.head != 0 condition fails? Otherwise it would actually result into infinite loop because rhs.head is tested instead of i. I suppose it should have been:

IntNode *i = rhs.head;
out << rhs.head;
while (i != 0) // note the i here
{
    out << " " << i;
    i = i->next; // again i here
}

The second question is what is out stream because at least head pointer should be printed there...

Answer 2

您需要使用i代替rhs.head

 while (i != 0)
 {
   out << " " << i;
   i = i->next;
 }

rhs.head != 0不能被循环中的内容改变，所以如果它是假的，循环将永远不会运行，如果它是真的，它将永远循环。

同样i = rhs.head->next;将始终将i设置为第二个节点（头部后面的节点），而不是i之后的节点。