模拟实现容器List（迭代器）

#include <iostream>using namespace std;template<class T>struct ListNode{ListNode(const T& data = T()): _pPre(0), _pNext(0), _data(data){}ListNode* _pPre;ListNode* _pNext;T _data;};//迭代器template <class T,class Ref,class Pointer>class ListIterator{typedef ListIterator Self;public:ListIterator(): _pCur(0){}ListIterator(ListNode<T>* pCur): _pCur(pCur){}ListIterator(const Self& s): _pCur(s._pCur){}Ref operator*(){return _pCur->_data;}Ref operator->(){/*return &(operator*());*/return &(_pCur->_data); }Self& operator++()//前置++{_pCur = _pCur->_pNext;return*this;}Self operator++(int)//后置++{Self temp(*this);_pCur = _pCur->_pNext;return temp;}Self& operator--()//前置--{_pCur = _pCur->_pPre;return*this;}Self operator--(int)//后置--{Self temp(*this);_pCur = _pCur->_pPre;return temp;}bool operator!=(const Self& s){return _pCur != s._pCur;}bool operator==(const Self& s){return _pCur == s._pCur;}ListNode<T>* _pCur;};template <class T>class List{public:typedef ListIterator<T,T&,T*> Iterator;typedef ListNode<T>* Node;public:List(): _pHead(new ListNode<T>){_pHead->_pNext = _pHead;//头结点_pHead->_pPre = _pHead;}List(const T* array, size_t size):_pHead(new ListNode<T>){_pHead->_pNext = _pHead;//头结点_pHead->_pPre = _pHead;for (size_t i = 0; i < size; ++i){PushBack(array[i]);}}List(const List& l)//拷贝构造:_pHead(new ListNode<T>){_pHead->_pNext = _pHead;//头结点_pHead->_pPre = _pHead;Node first = l._pHead->_pNext;while (first != l._pHead->_pPre){PushBack(first->_data);first = first->_pNext;}}List& operator=(const List& l){if (this != &l){_pHead = l._pHead;Iterator it = Begin();while (it != End()){Insert(it);it++;}}}~List(){Clear();delete _pHead;_pHead = NULL;}///////////////////////////////////////////////////////Iterator Begin(){return Iterator(_pHead->_pNext);}Iterator End(){return Iterator(_pHead);}/////////////////////Modify////////////////////////// void PushBack(const T& data){Node pTail = _pHead->_pPre;//尾指针Node pNewNode = new ListNode<T>(data);if (Empty())//空链表{_pHead->_pNext = pNewNode;pNewNode->_pNext = _pHead;_pHead->_pPre = pNewNode;pNewNode->_pPre = _pHead;}else//链表非空{Node pTail = _pHead->_pPre;//尾指针pTail->_pNext = pNewNode;pNewNode->_pPre = pTail;_pHead->_pPre = pNewNode;pNewNode->_pNext = _pHead;}}void PopBack(){if (Empty())return;else{Node pTail = _pHead->_pPre;//尾指针pTail = _pHead->_pPre->_pPre;delete pTail->_pNext;pTail->_pNext = _pHead;_pHead->_pPre = pTail; }}void PushFront(const T& data){Node pTail = _pHead->_pPre;//尾指针Node pNewNode = new ListNode<T>(data);pNewNode->_pNext = _pHead->_pNext;pNewNode->_pPre = _pHead;_pHead->_pNext->_pPre = pNewNode;_pHead->_pNext = pNewNode;}void PopFront(){if (Empty())return;else{Node tmp = _pHead->_pNext;_pHead->_pNext = tmp->_pNext;tmp->_pNext->_pPre = _pHead;delete tmp;}}Iterator Insert(Iterator pos, const T& data){Node pNewNode = new ListNode<T>(data);pNewNode->_pNext = pos._pCur;pNewNode->_pPre = pos._pCur->_pPre;pos._pCur->_pPre->_pNext = pNewNode;pos._pCur->_pPre = pNewNode;return Iterator(pNewNode);}Iterator Erase(Iterator pos){Node next = pos._pCur->_pNext;pos._pCur->_pPre->_pNext = pos._pCur->_pNext;pos._pCur->_pNext->_pPre = pos._pCur->_pPre;delete pos._pCur;return Iterator(next);}bool Empty()const{if (_pHead->_pNext == _pHead)return true;elsereturn false;}size_t Size()const{int cout = 0;Node pnext = _pHead;Node pTail = _pHead->_pPre;while (pnext != pTail){cout++;pnext = pnext->_pNext;}}T& Front(){return _pHead->_pNext->_data;}const T& Front()const{return _pHead->_pNext->_data;}T& Back(){return _pHead->_pPre->_data;}const T& Back()const{return _pHead->_pPre->_data;}void Clear(){Iterator it = Begin();while (it != End()){it = Erase(it);}_pHead->_pNext = _pHead;_pHead->_pPre = _pHead;}private:ListNode<T>* _pHead;};

测试函数

#include "List.h"void test(){int array[] = { 0, 1, 2, 3, 4 };List<int> l(array, sizeof(array) / sizeof(array[0]));l.PushBack(0);l.PushBack(1);l.PushBack(2);List<int>::Iterator it = l.Begin();while (it != l.End()){cout << *it << "->";++it;}cout << endl;l.PopFront();it = l.Begin();while (it != l.End()){cout << *it << "->";++it;}cout << endl;l.PopBack();it = l.Begin();while (it != l.End()){cout << *it << "->";++it;}cout << endl;l.PopFront();it = l.Begin();while (it != l.End()){cout << *it << "->";++it;}cout << endl;}void test2(){List<int> l;l.PushBack(1);l.PushBack(1);l.PushBack(1);l.PushBack(1);l.PushBack(1);List<int> L1(l);List<int>::Iterator it = L1.Begin();while (it != L1.End()){cout << *it << "->";++it;}cout << endl;List<int> L2 = L1;it = L1.Begin();while (it != L1.End()){cout << *it << "->";++it;}cout << endl;}int main(){test2();system("pause:");return 0;}