typedef int DATA;

struct SNode

{

    DATA data;

    SNode* pNext;

};

SNode* g_head=NULL;//全局变量

//从头部添加

void AddHead(DATA nNum)

{

    SNode* p = (SNode*)malloc(sizeof(SNode));//C语言的方式

    //SNode* p = new SNode;//C++ 方式

    p->data = nNum;

    p->pNext = g_pHead;

    g_pHead = p;

}

//从尾部添加

void AddTail(DATA nNum)

{

    SNode* p = (SNode*)malloc(sizeof(SNode));//C语言的方式

    pNew->data = nNum;

    pNew->pNext = NULL;

    if (!g_pHead)

    {

        g_pHead = pNew;

        return;

    }

    SNode* p = g_pHead;

    SNode* p1 = NULL;

    while (p)

    {

        p1 = p;

        p= p->pNext;

    }

    //跳出循环时，p1记录的时最后一个节点,让最后一个节点的pNext指向新创建的节点

    p = p1;

    p->pNext = pNew;

    //另一种写法

    //while(p->pNext != NULL)//循环遍历，当下一个节点为空说明到尾部了

    //    p=p->pNext;

        //p->pNext = pNew;

}

//找到，返回找节点位置;失败返回-1

int FindNodeIndex(DATA nNum)

{

    SNode* p = g_pHead;

    int i =;

    while(p)

    {

        if (p->data == nNum)

        {

            return i;

        }

        p = p->pNext;

        ++i;

    }

    return -;

}

//删除成功返回-1;失败返回0

int DeleteNode(DATA nNum)

{

    SNode* p = g_pHead;

    SNode* p1 = NULL;//记录前一个节点

    if (p == NULL)//当前链表为空

    {

        return -;

    }

    //头节点没有前一个节点，要特殊处理

    if (p->data == nNum)

    {

        g_pHead = p->pNext;

        delete p;

        return ;

    }

    while(p)

    {

        if (p->data == nNum)

        {

            //删除当前节点时，让当前节点的前一个节点的pNext指向当前节点的后一个节点

            p1->pNext = p->pNext;

            delete p;

            return ;

        }

        p1= p;//记录前节点

        p = p->pNext;

    }

    return -;

}

//修改指定节点的值

void ModifyNode(DATA oldNum,DATA newNum)

{

    SNode* p = g_pHead;

    while(p)//

    {

        if (p->data == oldNum)

        {

            p->data = newNum;

        }

            p = p->pNext;

    }

}

//打印所有节点

void PrintALL()

{

    SNode* p = g_pHead;

    if (p == NULL)

    {

        printf("当前链表为空\n");

        return;

    }

    while(p)//

    {

        printf("%d\n",p->data);

        p = p->pNext;

    }

}

//成功返回0；失败返回-1

int FindNode(DATA nNum)

{

    SNode* p = g_pHead;

    while (p)

    {

        if (p->data == nNum)

        {

            return ;

        }

        p=p->pNext;

    }

    return -;

}

//在某个节点之后插入新节点;成功返回0;失败返回-1

int InsertNode(DATA npos,DATA nNum)

{

    SNode* pNew = new SNode;//C++ 方式

    pNew->data = nNum;

    pNew->pNext = NULL;

   SNode* p = g_pHead;

    //if (p->data == npos)//头结点

    //{

    //    pNew->pNext=p->pNext;//头节点指向的下一个节点指针放到新节点的pNext

    //    p->pNext=pNew;//头节点pNext指向新节点

    //    return 0;

    //}

    while(p)

    {

        if (p->data == npos)

        {

            pNew->pNext = p->pNext;

            p->pNext=pNew;

            return ;

        }

            p = p->pNext;

    }

    return -;

}

void DeleteAll()

{

    SNode* p = g_pHead;

    SNode* p1 = NULL;

    while(p)

    {

        p1=p;

        p= p->pNext;

        delete p1;

    }

    g_pHead = NULL;

}

int main()

{

    DeleteNode();//链表为空的时候，删除要加判断

    lAddHead();

    lAddHead();

    AddHead();

    puts("修改前");

    PrintALL();

    ModifyNode(,-);

    puts("修改后");

    lPrintALL();

    int i = FindNodeIndex(-);

    if (i >= )

    {

        cout << "第" << i+ << "个节点找到" <<endl;

    }

    //删除节点

    i = DeleteNode();//头部删除要特殊处理

    if (i == )

    {

        cout << "删除节点成功!" << endl;

    }

    else

    {

        cout << "删除节点失败!" << endl;

    }

    PrintALL();

    puts("尾部添加");

    AddTail();

    PrintALL();

    //修改节点

    ModifyNode(-,);

    puts("插入节点3");

    //插入节点

    i = list.InsertNode(,);

    list.PrintALL();

    puts("清空链表");

    DeleteAll();

    PrintALL();

  return ;

}