链表的简单操作

#include<stdio.h>
#include<malloc.h>
#define NULL 0
#define LEN sizeof(struct student)
struct student
{
long num;
float score;
struct student * next;
};

int n;
struct student * creat(void)
{
struct student * head;
struct student *p1,*p2;
n=0;
p1=p2=(struct student *)malloc(LEN);
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("%d,%f",&p1->num,&p1->score);
}
p2->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,%5.1f\n",p->num,p->score);
p=p->next;
}
while(p!=NULL);
}
}
struct student * del(struct student *head,long num)
{
struct student *p1,*p2;
if(head==NULL)
{
printf("\nlist null! \n"); goto end;
}
p1=head;
while(num!=p1->num&&p1->next!=NULL)
{
p2=p1;p1=p1->next;
}
if(num==p1->num)
{
if(p1==head) head=p1->next;
else p2->next=p1->next;
printf("delete:%d\n",num);
n=n-1;
}
else printf("%ld not been found! \n",num);
end:
return (head);
}

struct student * insert(struct student * head,struct student * stud)
{
struct student *p0,*p1,*p2;
p1=head;
p0=stud;
if(head==NULL)
{
head=p0;p0->next=NULL;
}
else
{
while((p0->num>p1->num)&&(p1->next!=NULL))
{
p2=p1;
p1=p1->next;
}
if(p0->num<=p1->num)
{
if(head==p1)head=p0;
else p2->next=p0;
p0->next=p1;
}
else
{
p1->next=p0;p0->next=NULL;
}
n=n+1;
return(head);
}
}

void main()
{
struct student p;long n;\
int d;
struct student *st1=creat();
print(st1);
printf("2:del,3:insert,4:stop:");
while(scanf("%d",&d)!=NULL)
{
if(d==2)
{
scanf("%d",&n);
print(del(st1,n));
}
if(d==3)
{
scanf("%ld,%f",&p.num,&p.score);
print(insert(st1,&p));
}
if(d==4)
{
break;
}
printf("2:del,3:insert,4:stop:");
}

}