（C++版）链表（四）——实现双向循环链表创建、插入、删除等简单操作

        链表（四）实现双向循环链表简单操作，代码如下：

#include <iostream>
#include <stdlib.h>
using namespace std;

//结点类
class Node {
public:
	int data;
	Node *pPre, *pNext;
};

//双向循环链表类
class DoubleCircularLinkList {
public:
	DoubleCircularLinkList() {
		head = new Node;
		head->data = 0;
		head->pNext = head;
		head->pPre = head;
	}
	~DoubleCircularLinkList() {delete head;}
	void CreateLinkList(int n);
	void InsertNode(int position, int d);
	void TraverseLinkList();
	bool IsEmpty();
	int GetLength();
	void DeleteNode(int posiiton);
	void DeleteLinkList();
private:
	Node *head;
};

void DoubleCircularLinkList::CreateLinkList(int n) {
	if (n < 0) {
		cout << "输入结点个数错误！" << endl;
		exit(EXIT_FAILURE);
	}
	else {
		int i = 0;
		Node *pnew, *ptemp;
		ptemp = head;
		i = n;

		while (n-- > 0) {
			pnew = new Node;
			cout << "输入第" << i - n << "个结点：";	
			cin >> pnew->data;
			pnew->pNext = head;
			pnew->pPre = ptemp;
			ptemp->pNext = pnew;
			ptemp = pnew;
		}
	}
}

void DoubleCircularLinkList::InsertNode(int position, int d) {
	if (position < 0 || position > GetLength() + 1) {
		cout << "输入位置错误！" << endl;
		exit(EXIT_FAILURE);
	}
	else {
		Node *pnew, *ptemp;
		pnew = new Node;
		pnew->data = d;
		ptemp = head;
		while (position-- > 1)
			ptemp = ptemp->pNext;
		pnew->pNext = ptemp->pNext;
		pnew->pPre = ptemp;
		ptemp->pNext = pnew;
		ptemp = pnew;
	}
}

void DoubleCircularLinkList::TraverseLinkList() {
	Node *ptemp = head->pNext;
	while(ptemp != head) {
		cout << ptemp->data << " ";
		ptemp = ptemp->pNext;
	}
	cout << endl;
}

bool DoubleCircularLinkList::IsEmpty() {
	if (head == head->pNext)
		return true;
	else
		return false;
}

int DoubleCircularLinkList::GetLength() {
	int n = 0;
	Node *ptemp = head->pNext;
	while (ptemp != head) {
		n++;
		ptemp = ptemp->pNext;
	}
	return n;
}

void DoubleCircularLinkList::DeleteNode(int position) {
	if (position < 0 || position > GetLength()) {
		cout << "输入位置错误！" << endl;
		exit(EXIT_FAILURE);
	}
	else {
		Node *pdelete, *ptemp;
		ptemp = head;
		while (position-- > 1)
			ptemp = ptemp->pNext;
		pdelete = ptemp->pNext;
		ptemp->pNext = pdelete->pNext;
		pdelete->pNext->pPre = ptemp;
		delete pdelete;
		pdelete = NULL;
	}
}

void DoubleCircularLinkList::DeleteLinkList() {
	Node *pdelete, *ptemp;
	pdelete = head->pNext;
	while (pdelete != head) {
		ptemp = pdelete->pNext;
		head->pNext = ptemp;
		ptemp->pPre = head;
		delete pdelete;
		pdelete = ptemp;
	}
}

//测试函数
int main() {
	DoubleCircularLinkList dcl;
	int position = 0, value = 0, n = 0;
	bool flag = false;

	cout << "请输入需要创建双向循环链表的结点个数：";
	cin >> n;
	dcl.CreateLinkList(n);

	cout << "打印链表值如下：";
	dcl.TraverseLinkList();

	cout << "请输入插入结点的位置和值：";
	cin >> position >> value;
	dcl.InsertNode(position, value);
	
	cout << "打印链表值如下：";
	dcl.TraverseLinkList();

	cout << "请输入要删除结点的位置：";
	cin >> position;
	dcl.DeleteNode(position);

	cout << "打印链表值如下：";
	dcl.TraverseLinkList();

	dcl.DeleteLinkList();
	flag = dcl.IsEmpty();
	if (flag)
		cout << "删除链表成功！" << endl;
	else
		cout << "删除链表失败！" << endl;

 	return 0;
}