程序代码：

#include<stdio.h>
#include<malloc.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);//这个地方，和一般定义变量有什么不同？//
    scanf("%ld,%f",&p1->num,&p1->score);
    head=NULL;
    while(p1->num!=0)
    {
        n=n+1;
        if(n==1)head=p1;
        else p2->next=p1;
        p2=p1;
        p1=(struct Student *)malloc(LEN);
        scanf("%ld,%f",&p1->num,&p1->score);
    }
    p2->next=NULL;
    return(head);
}


int a=b=1这个样子不是错的么，为什么上面那个p1=p2=是对的