c++ - 如何将元素添加到链表的前面？

Question

节点是这样设置的:

struct Node {
    Node *next;
    Node *prev;
    T datum;
};

这是我的代码

    //MODIFIES: this
    //EFFECTS:  inserts i into the front of the list
    void push_front(const T &datum)
    {
        Node newfirst = first; // set newnode to first
        &first = &datum;
        datum = newfirst;

    }



  Node *first;   // points to first Node in list, or 0 if list is empty
  Node *last;    // points to last Node in list, or 0 if list is empty

出于某种原因，我认为这是不对的。

Answer 1

看来你需要以下内容

//this is my code
    //MODIFIES: this
    //EFFECTS:  inserts i into the front of the list
void push_front(const T &datum)
{
    first = new Node { first, nullptr, datum };

    if ( !last ) last = first;
}

如果您的编译器不支持 operator new 的初始化列表，那么您可以这样写

//this is my code
    //MODIFIES: this
    //EFFECTS:  inserts i into the front of the list
void push_front(const T &datum)
{
    Node *tmp = new Node();

    tmp->datum = datum;
    tmp->next = first;

    first = tmp;

    if ( !last ) last = first;
}