#include<stdio.h>
#include<stdlib.h>
#define LEN sizeof(struct student)
struct student
{
    long num;
    float score;
    struct student *next;
};
int n;
struct student *creat()
{
    struct student *head;
    struct student *p1,*p2;
    n=0;
    p1=p2=(struct student*)malloc(LEN);
    scanf("%ld,%f",&p1->num,&p2->score);
    head=NULL;
    while (p1->num!=0)
    {
        n=n+1;
        if(n==1)head=p1;
        else p2->next=p1;////////
        p2=p1;//////////////////问题（1）想不通程序怎么通过p2对该链表进行扩增的
        p1=(struct student *)malloc(LEN);
        scanf("%ld,%f",&p1->num,&p1->score);
    }
    p1->next=NULL;
    return (head);
}
void print(struct student *head)
{
    struct student *p;
    printf("\nNow,These %d records are :\n",n);
    p=head;
    if(head!=NULL)
        do
        {
            printf("%ld %5.1lf\n",p->num,p->score);
            p=p->next;
        }while(p!=NULL);
}
void main()
{
    struct student *head;
    head=creat();
    print(head);
}
这是谭老先生编的书上的程序，不过我有一个问题！问题在上面了，请各位多多帮助！

请大家都发表点意见！

p2->next=p1;//p2的后缀指向p1,则p2,p1连起来了。(1)
 p2=p1;//p2指针向后走，指向原本p1指向的单元。(2)
p1=(struct student *)malloc(LEN);//p1指向新生成的单元。现在跳到第一步(1)。