根据错误消息，您的 LinkedList 似乎没有 begin（）和 end（）可以在const对象上调用。但是，复制构造函数和赋值运算符的参数是const。您必须添加 begin（）和 end（）的const版本。

Based on the error message, it would seem that your LinkedList does not have variants of begin() and end() that can be called on a const object. The parameters to your copy constructor and assignment operator are const, however. You will have to add const versions of begin() and end().

想必您正在寻找这样的东西：

Presumably, you're looking for something like this:

    ConstIterator begin() const { Iterator(sp_Head); }
    Iterator begin() { Iterator(sp_Head); }

    ConstIterator end() const { ConstIterator(nullptr); }
    Iterator end() { Iterator(nullptr); }

其中 ConstIterator 是您的版本迭代const元素的迭代器类型…

Where ConstIterator is a version of your iterator type that iterates over const elements…