用C++封装双向循环链表（class）

#include<iostream>
using namespace std;

typedef int DataType;

struct Node  //结点
{
Node* _pNext;
Node* _pPre;
DataType _data;

Node(const DataType& data = DataType())  //创造新结点
: _pNext(NULL)
, _pPre(NULL)
, _data(data)
{}
};

class List
{
public:
List()   //构造
: _pHead(new Node)
{
_pHead->_pNext = _pHead;
_pHead->_pPre = _pHead;
}

List(const List& l) //拷贝
:_pHead(new Node)
{
_pHead->_pNext = _pHead;
_pHead->_pPre = _pHead;
Node *pcur = l._pHead->_pNext;
while (pcur != l._pHead)
{
PushBack(pcur->_data);
pcur = pcur->_pNext;
}
}
List& operator=(List& l)//赋值运算符重载   
{
swap(_pHead, l._pHead);
return *this;
}
~List() //析构
{
Node *pcur = _pHead->_pNext;
Node *pre = NULL;
while (pcur != _pHead)
{
pre = pcur;
pcur = pcur->_pNext;
delete[]pre;
}
delete[]pcur;
_pHead = NULL;
}

void PushBack(DataType data) //尾插
{
Node *newnode = new Node(data);//*********必须把空间创造出来，不能直接调用Node中的Node
Node *ptail = NULL;
ptail = _pHead->_pPre;
ptail->_pNext = newnode;
newnode->_pPre = ptail;
_pHead->_pPre = newnode;
newnode->_pNext = _pHead;
}
void PopBack()  //尾删
{
if (Empty())
{
Node *pretail = _pHead->_pPre->_pPre;
free(_pHead->_pPre);
_pHead->_pPre = pretail;
pretail->_pNext = _pHead;
}
return;
}
void PushFront(DataType data)  //头插
{
Node *newnode = new Node(data);
Node *ptail = NULL;
ptail = _pHead->_pNext;
ptail->_pPre = newnode;
_pHead->_pNext = newnode;
newnode->_pPre = _pHead;
newnode->_pNext = ptail;
}
void PopFront() //头删
{
if (Empty())
{
Node *pdel = _pHead->_pNext;
_pHead->_pNext = pdel->_pNext;
pdel->_pNext->_pPre = _pHead;
free(pdel);
}
return;
}
void Insert(Node* pos, DataType data) //任意位置插入
{
Node *newnode = new Node(data);
pos->_pPre->_pNext = newnode;
newnode->_pPre = pos->_pPre;
pos->_pPre = newnode;
newnode->_pNext = pos;
}
void Erase(Node* pos)  //任意位置删除
{
pos->_pPre->_pNext = pos->_pNext;
pos->_pNext->_pPre = pos->_pPre;
free(pos);
}
size_t Size()   //链表大小
{
size_t count = 0;
if (Empty())
{
Node *pcur = _pHead->_pNext;
while (pcur != _pHead)
{
count++;
pcur = pcur->_pNext;
}
return count;
}
return 0;
}
int Empty()const  //链表是否为空
{
if (_pHead->_pNext == _pHead)
{
return 0;
}
return 1;
}

Node *Find(DataType data)
{
Node *pcur = NULL;
pcur = _pHead->_pNext;
while (pcur != _pHead)
{
if (pcur->_data == data)
{
return pcur;
}
pcur = pcur->_pNext;
}
return NULL;
}

void PrintList()
{
Node *pcur = NULL;
pcur = _pHead->_pNext;
while (pcur != _pHead)
{
cout << pcur->_data << "--->";
pcur = pcur->_pNext;
}
cout << "NULL" << endl;
}

private:
Node* _pHead;  
};

int main()
{
List l1;
Node *pos;
size_t size;
l1.PushBack(3);
l1.PushBack(4);
l1.PushBack(5);
l1.PushBack(6);
l1.PushBack(7);

l1.PrintList();

l1.PopBack();
l1.PopBack();
l1.PrintList();

l1.PushFront(2);
l1.PushFront(1);
l1.PrintList();

l1.PopFront();
l1.PopFront();
l1.PrintList();

pos = l1.Find(4);
l1.Insert(pos, 8);
l1.PrintList();

l1.Erase(pos);
l1.PrintList();

size=l1.Size();

List l2(l1);
l2.PrintList();

List l3;
l3 = l1;
l3.PrintList();
return 0;

}

    若是对于双向链表的尾插、尾删等上述操作不明白，可以参照我以前写的博客https://mp.youkuaiyun.com/postedit/80098311

若是对深拷贝不理解的，可以参照我以前写的博客https://mp.youkuaiyun.com/postedit/80075175

希望对大家有所帮助!!!!!!