链表的插入

# include <stdio.h>
# include <stdlib.h>

typedef struct node
{
    int date;
    struct node *pNext;
}NODE, *PNODE;

PNODE init_list(int *len)//初始化链表
{
    PNODE pHead, pRecord, pTemp;
    int i;
   
    pHead = NULL;
    printf("请输入链表的长度： ");
    scanf("%d", len);
    for (i=0; i<*len; i++)
    {
        pTemp = (PNODE) malloc(sizeof(NODE));
        if (NULL == pTemp)
        {
            printf("分配失败，程序终止！\n");
            exit(-1);
        }
        pTemp->pNext = NULL;
        printf("节点的值 ： ");
        scanf("%d", &pTemp->date);
        if (NULL == pHead)
        {
            pHead = pTemp;
            pRecord = pHead;
        }
        else
        {
            pRecord->pNext = pTemp;
            pRecord = pTemp;
        }
    }
   
    return pHead;
}

void  traverse_list(PNODE pHead)//遍历链表
{
    PNODE pTemp = pHead;
   
    while (NULL != pTemp)
    {
        printf("%d ", pTemp->date);
        pTemp = pTemp->pNext;
    }
    printf("\n");
}

bool insert_list(PNODE pHead, int pos, int len, int e)//插入元素
{
    if (pos<1 || pos>len+1)
    {
        printf("pos 输入错误！\n");
        return false;
    }
   
    PNODE pTemp;
    PNODE pRecord = pHead;

    pTemp = (PNODE) malloc(sizeof(NODE));
    if (NULL == pTemp)
    {
        printf("分配失败，程序终止！\n");
        exit(-1);
    }
    pTemp->pNext = NULL;
    pTemp->date = e;
    if (1 == pos)
    {
        pHead = pTemp;
        pTemp->pNext = pRecord;
    }
    else
    {
        for (int i=1; i<=pos; i++)
        {
            if (pos-1 == i)
            {
                pTemp->pNext = pRecord->pNext;
                pRecord->pNext = pTemp;
                break;
            }
            pRecord = pRecord->pNext;
        }
    }
    return true;
   
}

int main()
{
    PNODE pHead = NULL;
    int length = 0;
    int e, pos;
   
    pHead = init_list(&length);
    printf("未处理的链表 : \n");
    traverse_list(pHead);
   
    printf("输入插入的位置及元素 : ");
    scanf("%d %d", &pos, &e);
    insert_list(pHead, pos, length, e);
    printf("插入后的链表 : \n");
    traverse_list(pHead);
    return 0;

 }