c++实现双向循环链表

#pragma once
#include
#include
using namespace std;
template
struct ListNode
{
ListNode(T x):data(x),front(this),back(this){}
T data;
ListNode *front;
ListNode *back;
};

template
class List_double
{
public:
List_double();
List_double(const List_double& other);
List_double& operator = (const List_double& other);
~List_double();

public:
void InsertNode(T x, ListNode *temp = NULL);
T DeleteNode(ListNode *del = NULL);
ListNode* Find(T x);
void PrintFront();
void PrintBack();
public:
ListNode *head;
};

template
List_double::List_double()
{
head = NULL;
}

template
List_double::List_double(const List_double& other)
{
head = NULL;
ListNode *cur = other.head;
while (cur)
{
InsertNode(cur->data);
cur = cur->front;
if (cur == other.head)
break;
}
}

template
void List_double::InsertNode(T x, ListNode *ins = NULL)//在节点ins之后插入，默认插入表后
{
ListNode *temp = new ListNode(x);
if (head == NULL)
{
head = temp;
return;
}
if (ins == NULL)
{
temp->front = head->front;
temp->back = head;
temp->back->front = temp;
temp->front->back = temp;
}
else
{
temp->front = ins;
temp->back = ins->back;
temp->back->front = temp;
temp->front->back = temp;
}
}

template
List_double& List_double::operator = (const List_double& other)
{
head = NULL;
ListNode *cur = other.head;
while (cur)
{
InsertNode(cur->data);
cur = cur->front;
if (cur == other.head)
break;
}
}

template
List_double::~List_double()
{
while (head->front != head)
{
DeleteNode();
}
delete head;
}

template
T List_double::DeleteNode(ListNode *del = NULL)//默认删除表后数据，删除del所指位置
{
assert(head != NULL);
T ret;
if (head->front == head)
{
ret = head->data;
delete head;
head = NULL;
return ret;
}
if (del == NULL)
{
head->front = head->front->front;
ret = head->front->back->data;
delete head->front->back;
head->front->back = head;
return ret;
}
else
{
del->front->back = del->back;
del->back->front = del->front;
ret = del->data;
delete del;
return ret;
}
}

template
ListNode* List_double::Find(T x)
{
ListNode *p = head->front;
while (p)
{
if (p == head)
{
if (p->data == x)
return p;
else
return NULL;
}
if (p->data == x)
{
return p;
}
else
{
p = p->front;
}
}
}

template
void List_double::PrintFront()
{
ListNode *p = head;
while (p)
{
if (p == head->front)
{
cout << p->data << ' ';
return;
}
else
{
cout << p->data << ' ';
p = p->back;
}
}
}

template
void List_double::PrintBack()
{
ListNode *p = head->front;
while (p)
{
if (p == head)
{
cout << p->data << ' ';
return;
}
else
{
cout << p->data << ' ';
p = p->front;
}
}
}

#include
#include
#include "List.h"
using namespace std;
int main()
{
int n;
cout << "操作：增加（1），删除（2），从前往后输出（3），从后往前输出（4），查找（5）" << endl;
List_double list;
while (cin >> n)
{
if (n == 0)
break;
switch (n)
{
case 1:
int tt;
cout << "请输入增加的数据int：" << endl;
cin >> tt;
list.InsertNode(tt);
break;
case 2:
cout << "删除的数据为" << list.DeleteNode() << endl;;
break;
case 3:
list.PrintFront();
break;
case 4:
list.PrintBack();
break;
case 5:
int ttt;
cout << "请输入查找的数据int：" << endl;
cin >> ttt;
if (list.Find(ttt) == NULL)
cout << "没有此数据" << endl;
else
cout << "存在此数据" << endl;
break;
}
cout << "操作：增加（1），删除（2），从前往后输出（3），从后往前输出（4），查找（5）" << endl;
}
getchar();
getchar();
return 0;
}