双向链表c++实现

#pragma once
//定义结构体指针
struct node
{
	int date;
	node* prev;
	node* next;
};
class doublelinks
{
public:
	doublelinks();
	~doublelinks();
public:
	int doublelink_insert(doublelinks* ptr, int position, int member);  //插入
	int doublelink_erase(doublelinks* ptr, int position);               //删除
	void doublelink_display(doublelinks* ptr, int num);                 //显示
	int doublelink_getlength(doublelinks* ptr);                         //得到长度
private:
	int length;
	node* root;

};

#include "doublelinks.h"
#include <iostream>
using namespace std;
doublelinks::doublelinks()
{
	root = new node;
	root->prev = NULL;
	root->next = NULL;
	length = 0;
}

doublelinks::~doublelinks()
{
}
//插入
int doublelinks::doublelink_insert(doublelinks *ptr, int position, int member)
{
	node* nodeinsert = new node;
	nodeinsert->date = member;
	if (ptr->doublelink_getlength(ptr) == 0)
	{
		root->next = nodeinsert;
		nodeinsert->prev = nodeinsert;
		nodeinsert->next = nodeinsert;
		ptr->length++;
		return 0;
	}
	else
	{
		if (position == 0)
		{
			nodeinsert->prev = root->next->prev;
			nodeinsert->next = root->next;
			root->next->prev->next = nodeinsert;
			root->next->prev = nodeinsert;
			root->next = nodeinsert;
			ptr->length++;
			return 0;
		}
		else
		{
			node* current = root->next;
			for (int i = 0; i < position; i++)
			{
				current = current->next;
			}
			nodeinsert->next = current;
			nodeinsert->prev = current->prev;
			current->prev->next = nodeinsert;
			current->prev = nodeinsert;
			ptr->length++;
			return 0;
		}
	}
}
//删除
int doublelinks::doublelink_erase(doublelinks* ptr, int position)
{
	if (ptr->doublelink_getlength(ptr) == 0)
	{
		cout << "链表为空，oop！！" << endl;
		return 0;
	}
	else
	{
		if (ptr->doublelink_getlength(ptr) == 1)
		{
			ptr->root->next = NULL;
			ptr->length--;
		}
		else
		{
			node* deletenode = root->next;
			for (int i = 0; i < position; i++)
			{
				deletenode = deletenode->next;
			}
			deletenode->prev->next = deletenode->next;
			deletenode->next->prev = deletenode->prev;
			delete deletenode;
			ptr->length--;
		}
	}
}
int doublelinks::doublelink_getlength(doublelinks* ptr)
{
	return ptr->length;
}
void doublelinks::doublelink_display(doublelinks* ptr, int num)
{
	node* current = root->next;
	for (int i = 0; i < num; i++)
	{
		cout << current->date << " ";
		current = current->next;
	}
	cout << endl;
}

#include <iostream>
#include "doublelinks.h"
using namespace std;

int main()
{
	doublelinks* doublelink_ptr = new doublelinks;
	for (int i = 0; i < 10; i++)
	{
		doublelink_ptr->doublelink_insert(doublelink_ptr, 0, i);
	}
	doublelink_ptr->doublelink_display(doublelink_ptr, 20);
	doublelink_ptr->doublelink_erase(doublelink_ptr, 2);
	doublelink_ptr->doublelink_display(doublelink_ptr, 20);
	return 0;
}

转自http://blog.csdn.net/hongkangwl/article/details/22286469