求解答,这是为什么,链表问题有点难

我看不懂为什么可以使pTain永远指向尾结点,这一步是是什意思pTain =pNew,还有这一步 PNODE pTail = pHead;
pTail->pNext = NULL;
总的代码是:

include

include

include

typedef struct Node
{
int data; //数据域
struct Node * pNext; //指针域
}NODE, *PNODE; //NODE 等价于struct node , PNODE等价于struct node *

//函数声明
PNODE create_list(void);
void traverse_list(PNODE pHead);

int main(void)
{
PNODE pHead = NULL;
pHead = create_list(); //创建一个非循环单链表,并将该链表的头节点的地址赋给phead
traverse_list(pHead); //

return 0;

}

PNODE create_list(void)
{
int len; //用来存放有效结点个数
int i;
int val; //用来临时存放用户输入的节点的值

//创建一个不存放数据的头节点 
PNODE pHead = (PNODE)malloc(sizeof(NODE));

if (NULL == pHead)
{
    printf("分配失败!\n");
    exit(-1);
}

PNODE pTail = pHead;
pTail->pNext = NULL;

printf("请输入您要输入的链表节点个数:len =");
scanf("%d", &len);

for (i=0; i"请输入第%d个节点的值", i+1);
    scanf("%d", &val);
    
    PNODE pNew = (PNODE)malloc(sizeof(NODE));
    if (NULL == pNew)
    {
        printf("分配失败!\n");
        exit(-1);
    }
    pNew->data = val;
    pTail->pNext = pNew;
    pNew->pNext = NULL;
    pTail = pNew;
}

return pHead;

}

void traverse_list(PNODE pHead)
{
PNODE p = pHead->pNext;
while (NULL != p)
{
printf("%d", p->data);
p = p->pNext;
printf("\n");
}
printf("\n");

include

include

include

typedef struct Node
{
int data; //数据域
struct Node * pNext; //指针域
}NODE, *PNODE; //NODE 等价于struct node , PNODE等价于struct node *

//函数声明
PNODE create_list(void);
void traverse_list(PNODE pHead);

int main(void)
{
PNODE pHead = NULL;
pHead = create_list(); //创建一个非循环单链表,并将该链表的头节点的地址赋给phead
traverse_list(pHead); //

return 0;

}

PNODE create_list(void)
{
int len; //用来存放有效结点个数
int i;
int val; //用来临时存放用户输入的节点的值

//创建一个不存放数据的头节点 
PNODE pHead = (PNODE)malloc(sizeof(NODE));

if (NULL == pHead)
{
    printf("分配失败!\n");
    exit(-1);
}

PNODE pTail = pHead;
pTail->pNext = NULL;

printf("请输入您要输入的链表节点个数:len =");
scanf("%d", &len);

for (i=0; i"请输入第%d个节点的值", i+1);
    scanf("%d", &val);

}

自己手动画一个链表插入流程图就明白了