C语言逆序输出单链表

C语言输入若干个正整数（输入-1为结束标志），要求按输入数据的逆序建立单链表并输出。

/*
开发者：慢蜗牛
程序功能：逆序建立链表，顺序输出
*/
 
#include<stdio.h>
#include<malloc.h>
#define LEN sizeof(struct once)
 
struct once//建立结构
{
int a;
 
struct once* next;
};
 
struct once* out()//建立头插法逆序建立链表
{
int n = 0;
 
struct once* p1, * p2;
 
printf("请输入：");
 
p1 = p2 = (struct once*)malloc(LEN);
 
scanf_s("%d", &p1->a);
 
p2->next = NULL;
 
while (p1->a != -1)
{
    if (n == 0) p1->next = p2->next;
 
    else p1->next = p2;
 
    p2 = p1;
 
    p1 = (struct once*)malloc(LEN);
 
    scanf_s("%d", &p1->a);
 
    n = n + 1;
}
return(p2);
}
 
void print(struct once* head)//输出链表
{
 
struct once* p1, * p2, * p3, * p;
 
p3 = p1 = p2 = (struct once*)malloc(LEN);
 
p1->next = head; head = p1;
 
p1 = head->next;
 
do//反转
{
    p3 = head->next; p2 = p1->next;
 
    head->next = p2; p1->next = p2->next;
 
    p2->next = p3;
} while (p1->next != NULL);
 
p = head->next;
 
do//输出头节点链表
{
    printf("--%d", p->a);
 
    p = p->next;
 
} while (p != NULL);
}
 
void main()//调用函数
{
 
struct once* head;
 
head = out();
 
print(head);
 
}