c++ - 错误 c2440 '=' 无法从 int * 转换为 Type *

Question

我在 VS2015 中遇到以下错误。对我来说，我搞砸模板的事情并不明显。

非常感谢任何指点!

错误 C2440“=”:无法从“int *”转换为“DNode *”

    template<class Type>
    class DNode <- *** THIS IS THE TYPE ***
    {
    public:
        Type *next;
        Type *previous;
        Type value;

        DNode(Type valueParam)
        {
            value = valueParam;
            next = previous = NULL;
        }
    };

    template<class T>
    class DLinkedList
    {
        DNode<T> *head;
        DNode<T> *tail;

    public:
        DLinkedList()
        {
            head = tail = NULL;
        }

        T pop_tail()
        {
            if (tail == NULL) return -1;
            T value;
            if (head == tail)
            {
                value = tail->value;
                free(tail);
                head = tail = NULL;
                return value;
            }
            else
            {
                DNode<T> *ptr = tail;
                value = tail->value;
                tail = tail->previous;   <-- *** THIS LINE THROWS ERR ***
                tail->next = NULL;
                free(ptr);
                return value;
            }
        }
    }

Answer 1

DNode::previous类型为 Type* , 不是 DNode<Type>* .

您可能希望同时声明 DNode::next和 DNode::previous作为类型 DNode<Type>* .