c++实现单链表

#include<iostream>
#include<assert.h>
using namespace std;
typedef int DataType;

struct LinkNode   //创建一个节点
{
    DataType _data;
    LinkNode* _next;

    LinkNode(const DataType &x) :_data(x), _next(NULL)
    {}
};
class SList
{
public:
    SList(LinkNode* head = NULL, LinkNode* tail = NULL) 
        :_Head(head), _Tail(tail) 
    {}
    void Swap( SList &s)
    {
        swap(_Head, s._Head);
        swap(_Tail, s._Tail);
    }
    SList(const SList &s)
         :_Head(NULL)
        , _Tail(NULL)
    {
        if (s._Head == NULL)
        {
            return;
        }
        LinkNode* begin = s._Head;
        do{
            PushBack(begin->_data);
            begin = begin->_next;
        } while (begin != s._Head);
    }
    ~SList()
    {
        while (_Head)
        {
            if (_Head == _Tail)
            {
                delete _Head;
                _Head = NULL;
                _Tail = NULL;
            }
            else
            {
                LinkNode *del = _Head;
                _Head = _Head->_next;
                delete del;
                _Tail->_next = _Head;
            }
        }
    }
    SList operator= ( SList& s)
    {
        SList tmp(s);
        Swap(tmp);
        return *this;
    }
public:
    void Destory()
    {
        if (_Head == NULL)
        {
            return;
        }
        //先不管_Head和_Tail等全部删完将_Head和_Tail置为NUL
        LinkNode* begin = _Head;
        do{
            LinkNode* del = begin;
            begin = begin->_next;
            delete del;
        } while (begin != _Head);
        _Head = NULL;
        _Tail = NULL;
    }
    void Print()
    {
        //1.没有节点
        //2.多个节点
        if (_Head == NULL)
        {
            return;
        }
        LinkNode *begin = _Head;
        do{
            cout << begin->_data<< "->";
            begin = begin->_next;
        } while (begin != _Head);
        cout<< endl;
    }
    void PushBack(const DataType& x)//尾插
    {//1.没有节点
     //2.有多个节点
        if (_Head == NULL)
        {
            _Head = new LinkNode(x);
            _Tail = _Head;
            _Tail->_next = _Head;
        }
        else
        {
            LinkNode *tmp = new LinkNode(x);
            _Tail->_next = tmp;
            tmp->_next = _Head;
            _Tail = tmp;
        }
    }
    void PopBack()//尾删
    {
        if (_Head == NULL) //没有节点
        {
            cout << "SList is empty" << endl;
            return;
        }
        else if (_Head == _Tail) //有一个节点
        {
            delete _Head;
            _Head = NULL;
            _Tail = NULL;
        }
        else    //有多个节点
        {
            LinkNode *prev = _Head;
            while (prev->_next != _Tail)
            {
                prev = prev->_next;
            } 
            prev->_next = _Head;
            delete _Tail;
            _Tail = prev;
        }
    }

    void PopFront()//头删
    {
        if (_Head == NULL) //没有节点
        {
            cout << "SList is empty" << endl;
            return;
        }
        else if (_Head == _Tail) //有一个节点
        {
            delete _Head;
            _Head = NULL;
            _Tail = NULL;
        }
        else
        {
            LinkNode* del = _Head;
            _Head = _Head->_next;
            delete del;
            _Tail->_next = _Head;
        }
    }

    void PushFront(DataType x)//头插
    {
        if (_Head == NULL)  //没有节点
        {
            _Head = new LinkNode(x);
            _Tail = _Head;
            _Tail->_next = _Head;
        }
        else    //有多个节点
        {
            LinkNode* tmp = new LinkNode(x);
            tmp->_next = _Head;
            _Head = tmp;
            _Tail->_next = _Head;
        }
    }

    LinkNode* Find(DataType x)
    {
        if (_Head == NULL) //没有节点
        {
            cout << "SList is empty" << endl;
            return NULL;
        }
        LinkNode* begin = _Head;
        do{
            if (begin->_data == x)
            {
                cout << "find " << x << endl;
                return begin;
            }
            begin = begin->_next;
        } while (begin != _Head);
        cout << "not find " << x << endl;
        return NULL;
    }

    bool Remove(LinkNode * n)
    {
        assert(n);
        if (_Head == NULL) //没有节点
        {
            cout << "SList is empty" << endl;
            return false;
        }
        if (n == _Head)  //n是头指针
        {
            _Head = _Head->_next;
            delete n;
            _Tail->_next = _Head;
            return true;
        }

        LinkNode* prev = _Head;
        do{
            if (prev->_next == n)  //n是中间指针
            {
                prev->_next = n->_next;
                delete n;
                if (n == _Tail)    //n是尾指针
                {
                    _Tail = prev;
                    _Tail->_next = _Head;
                }
                return true;
            }
            prev = prev->_next;

        } while (prev != _Head);
        return false;
    }
    void Insert(LinkNode * n, DataType x) //先找到节点n，在n后面插一个节点
    {
        assert(n);
        if (_Head == NULL) //没有节点
        {
            cout << "SList is empty" << endl;
            return ;
        }
        LinkNode* begin = _Head;
        do{
            if (begin == n)
            {
                LinkNode* tmp = new LinkNode(x);
                tmp->_next = n->_next;
                n->_next = tmp;
                if (n == _Tail)
                {
                    _Tail = tmp;
                    _Tail->_next = _Head;
                }
                return;
            }
            begin = begin->_next;
        } while (begin != _Head);
        cout << "not find " << n << endl;
    }
    void Reverse()  //翻转
    {
        if (_Head == NULL) //没有节点
        {
            cout << "SList is empty" << endl;
            return;
        }
        if (_Head == _Tail)
        {
            cout << "只有一个节点" << endl;
            return;
        }
        LinkNode* tmp = _Head;
        LinkNode* newhead = tmp, *newtail = tmp;
        do{
            LinkNode* prev = tmp;
            tmp = tmp->_next;
            prev->_next = newhead;
            newhead = prev;
        } while (tmp != _Head);
        newtail->_next = newhead;
        _Head = newhead;
    }
private:
    LinkNode* _Head;
    LinkNode* _Tail;
};

void test()
{
    SList s1;
    s1.PushBack(1);
    s1.PushBack(2);
    s1.PushBack(3);
    s1.Print();
    SList s2 = s1;
    /*s2.PushBack(4); s2.PushBack(5); s2.PushBack(6);*/
    s2.Print();
    /*s1 = s2; s1.Print();*/
    //s1.PopBack();
    //s1.PopBack();
    //s1.PopBack();
    //s1.PopBack(); //没有节点的时候删除
    //s1.Print();
}

void test2()
{
    SList s1;
    s1.PushFront(1);
    s1.PushFront(2);
    s1.PushFront(3);
    s1.Print();
    /*s1.Reverse(); s1.Print();*/
    LinkNode* node = s1.Find(1); 
    s1.Insert(node, 4);
    /*s1.Remove(node);*/
    s1.Print();
    /*s1.PopFront(); s1.PopFront(); s1.PopFront(); s1.PopFront(); s1.Find(2); s1.Print();*/

}


int main()
{
    test();
    getchar();
    return 0;
}