C++循环链表问题，调试的时候一直显示*****是nullptr，求问怎么解决

Question

代码如下

#ifndef _LinkedList_H_
#define _LinkedList_H_
using namespace std;
template <class T>
class LinkedList
{
private:
    struct node
    {
        T data;
        node*next;
        node(const T& x, node* n = NULL) :data(x), next(n) {};
        node() :next(NULL) { data = 0; };

    };
    node* head;
    int size;
protected:
    node* get(int i)const
    {
        if (i < 0)return head;
        node* p = head->next;
        for (int j = 0; j < i; j++)
            p = p->next;
        return p;
    }
public:
    LinkedList() :size(0)
    {
        head = new node;
    }
    ~LinkedList()
    {
        clear();
        delete head;
    }
    int length()
    {
        return size;
    }
    void clear()
    {
        while (length() > 0) remove(0);
    }
    void insert(int i, const T&x)
    {
        node* p = get(i - 1);
        p->next = new node(i, p->next);
        size++;
    }
    void remove(int i)
    {
        node* p = get(i - 1);
        node* q = p->next;
        p->next = q->next;
        delete q;
        --size;
    }
    int search(const T& x)const
    {
        node* p = head->next;
        for (int i = 0; p; ++i)
        {
            if (x == p->data)
                return i;
            p = p->next;
        }
        return -1;
    }
    T visit(int i)const
    {
        return get(i)->data;
    }

    void traverse()const
    {
        node* p = head->next;
        while (p)
        {
            cout << p->data << endl;
            p = p->next;
        }
    }
    void erase(int x, int y)
    {
        int i;
        node* p = get(x - 1);
        node* q = p->next;
        for (i = x; i <= y; i++)
        {
            p->next = q->next;
            delete q;
            q = p->next;
        }
    }

};
#endif

#include <iostream>
#include "LinkedList.h"
using namespace std;
int main()
{
    LinkedList <int> list;
    int n;
    cout << "input n" << endl;
    cin >> n;
    int *arr = new int[n];
    for (int i = 0; i < n; i++)
    {
        arr[i] = i;
    }
    for (int i = 0; i < n; i++)
    {
        list.insert(i,arr[i]);
    }
    cout<<list.search(2);
    list.erase(1,3);
    list.traverse();
    delete[]arr;
    return 0;
}

Answer 1

你的

 void erase(int x, int y)

实现有问题，没有删除元素后把列表长度减一；应改为

    void erase(int x, int y)
    {
        int i;
        node* p = get(x - 1);
        node* q = p->next;
        for (i = x; i <= y; i++)
        {
            p->next = q->next;
            delete q;
            q = p->next;
                         --size;
        }
    }