C++实现单链表

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#include<iostream>#include<errno.h>using namespace std;typedef int DataType;//定义链表结点的结构体struct LinkNode{DataType _data;LinkNode* _next;//错误，此处的类型为LinkNode* 而不是 LinkNodeLinkNode(DataType data):_data(data) ,_next(NULL){}};class LinkedList{public :LinkedList()//默认无参构造函数:_head(NULL), _tail(NULL), _size(NULL){}LinkedList(const LinkedList& linkedList)//可以允许:_head(NULL), _tail(NULL){if(&linkedList == NULL)return;LinkNode *cur = linkedList._head;//为什么通过该类对象可以访问到私有成员while(cur!=NULL){this->PushBack(cur->_data);cur = cur->_next;}}LinkedList &operator=(const LinkedList& linkedList){if(&linkedList != this){this->~LinkedList();LinkNode *cur = linkedList._head;while(cur!=NULL){this->PushBack(cur->_data);cur = cur->_next;}}return *this;}~LinkedList()//析构函数{while(_head){this->PopFront();}}public :LinkNode* getHead();void PushBack(const DataType& data);//向链表尾部插入一个元素void Popback();//删除链表尾部的元素void PushFront(const DataType& data);//向链表头部插入一个元素void PopFront();//删除链表头部的元素void Reverse();//将链表逆置void Print();//打印链表的元素private :LinkNode* _head;//指链表头的指针LinkNode* _tail;//指向链表尾的指针int _size;};//错误，类结束有分号LinkNode* LinkedList::getHead(){return _head;}void LinkedList::PushBack(const DataType& data){//当链表中为空时if(_head == NULL){_head = new LinkNode(data);if(_head == NULL)//若内存分配失败则终止程序{perror("Memory distribute fail!");exit(-1);}_tail = _head;_size = 1;}else{//链表不为空时不用初始化链表的头结点LinkNode* newNode = new LinkNode(data);if(newNode == NULL)//若内存分配失败则终止程序{perror("Memory distribute fail!");exit(-1);}_tail->_next = newNode;_tail = _tail->_next;_size++;}}void LinkedList::Popback(){if(_tail == NULL)//当链表为空时{printf("LinkedList is empty,don't Pop!\n");}else if(_head == _tail){//当链表中只有一个元素delete _head;_head = NULL;_tail = NULL;_size = 0;}else{//当链表有一个以上的元素时LinkNode* cur = _head;//定义一个游标指针//使用循环将该游标指针指向尾结点的前一个结点while(cur->_next != _tail){cur = cur->_next;}cur->_next = NULL;delete _tail;_tail = cur;_size--;}}void LinkedList::PushFront(const DataType& data){if(_head == NULL){_head = new LinkNode(data);_tail = _head;_size = 1;}else{LinkNode* newNode = new LinkNode(data);newNode->_next = _head;_head = newNode;_size++;}}void LinkedList::PopFront(){if(_head == NULL){cout<<"LinkedList is empty,don't Pop!"<<endl;}else if(_head == _tail){delete _head;_head = NULL;_tail = NULL;_size = 0;}else{LinkNode* temp = _head;_head = _head->_next;_size--;delete temp;temp = NULL;}}void LinkedList::Reverse(){if(_head == NULL){cout<<"LinkedList is empty, don't reverse!"<<endl;}if(_size > 1){LinkNode* prior = _head;//表示逆置过程中的链表头LinkNode* next = _head->_next;//表示每次进行逆置的节点LinkNode* temp = NULL;//记录每次进行逆置节点的下一个位置，即为未进行逆置链表的第一个位置_tail = _head;//链表逆置后，当前的头结点将变为尾节点_tail->_next = NULL;//尾节点的下一个位置为空//使用前插的思想依次对各个节点进行逆置while(next != NULL){temp = next->_next;next->_next = prior;prior = next;next = temp;}//最后一个进行前插的节点为逆置后链表的头节点_head = prior;}}void LinkedList::Print(){if(_head == NULL){cout<<"LinkedList is empty!"<<endl;return;}LinkNode* cur = _head;while(cur != NULL){cout<<cur->_data<<" ";cur = cur->_next;}cout<<endl;}
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