类别未被识别

Class not being recognised

本文关键字：识别      更新时间：2023-10-16

这是我的代码：

template <class a, class b>
class LinkedListIter{
    public:
        LinkedListIter(b* iterable){
            this->iterable = iterable;
            this->head = this->iterable->head;
            this->curr = this->iterable->curr;
            this->iter_pos = 0;
        };
        void operator++(int dummy){
            this->iter_pos++;
        };
        friend std::ostream& operator<< (std::ostream& o, LinkedListIter const& lli);
    private:
        a* head;
        a* curr;
        b* iterable;
        int iter_pos; //The current position if the iterator
    };
std::ostream& operator<< (std::ostream& o, LinkedListIter const& lli){ 
    return o << lli.get(lli.iter_pos); 
}

在我声明std::ostream& operator<< (std::ostream& o, LinkedListIter const& lli)的那一行，我得到了一个错误，说LinkedListIter没有命名类型。为什么会这样？

LinkedListIter是一个类模板，而不是一个类。所以你的操作员也需要成为一个模板。

template<typename a, typename b>
std::ostream& operator<< (std::ostream& o, LinkedListIter<a,b> const & lli){
...

#include <iostream>
template <class a, class b>
class LinkedListIter;
template <class a, class b>
std::ostream& operator<< (std::ostream& o, LinkedListIter<a, b> const& lli);
template <class a, class b>
class LinkedListIter{
    public:
        LinkedListIter(b* iterable) {
            this->iterable = iterable;
            this->head = this->iterable->head;
            this->curr = this->iterable->curr;
            this->iter_pos = 0;
        };
        void operator++(int dummy) {
            this->iter_pos++;
        };
        friend std::ostream& operator<< <a, b> (std::ostream& o, LinkedListIter const& lli);
    private:
        a* head;
        a* curr;
        b* iterable;
        int iter_pos; //The current position if the iterator
};
template <class a, class b>
std::ostream& operator<< (std::ostream& o, LinkedListIter<a, b> const& lli) { 
    return o << lli.get(lli.iter_pos); 
}

这段代码可以编译得很好，希望得到帮助。

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