#include<stdio.h>
#include<malloc.h>
#define len sizeof(struct student)
struct student
{
long num;
float score;
struct student *next;
};
int n;

//创建链表
struct student*creat()
{
 struct student *p1,*p2;
 struct student *head=NULL;
 n=0;
 p1=p2=(struct student*)malloc(len);
 scanf("%ld%f",&p1->num,&p1->score);
 while(p1->num!=0)
 {
     n++;
 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);
}

//打印链表
void print(struct student *head)
{
struct student *p;
p=head;
while(p!=NULL)
{printf("%ld %f\n",p->num,p->score);
p=p->next;
}
}

//删除链表
struct student * del(struct student *head)
{
long _num,i;
struct student *p,*p1;
printf("输入要删除的数：");
back: scanf("%ld",&_num);

p=head;
if(_num==head->num)  head=head->next;
else
{
    while(p->num!=_num)
{
p1=p;
p=p->next;
}
p1->next=p->next;
}
printf("还要删除吗？要按1,不要按0\n");
scanf("%d",&i);
if(i==1)  goto back;
else
return(head);
}


//插入链表
struct student *insert(struct student *head)
{
struct student *p,*p1,*p2;
p=p1=p2=(struct student*)malloc(len);
printf("要插入的数：");
scanf("%ld%f",&p->num,&p->score);
p1=head;
if(p->num<=p1->num)    { head=p;  p->next=p1;}
 else
 {
   while(p1->num<p->num&&p2->next!=NULL)
     {p2=p1;   p1=p1->next;}
  if  (p2->next=NULL)   {p2->next=p;}
 else {p->next=p1;p2->next=p;}
 
 return (head);
 }
}


main()
{
//print(creat());
//print(del(creat()));
    print(insert(creat()));
}

//链表只有插入有问题，当输入：
1 1
2 2
3 3

结果出现
要插的数
4 4
编译出错。

问题就是插不进尾数。