数据结构(链表)

#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) /*创建链表*/
{
    struct student *head;
    struct student *p1,*p2;
    n=0;
    p1=p2=(struct student*)malloc(LEN);/*开辟一个新单元*/
    scanf("%1d,%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("%1d,%f",&p1->num,&p1->score);
    }
    p2->next=NULL;
    return head;
}

void print(struct student *head) /*输出链表*/
{
   struct student *p;
   printf("\nNow,These %d records are:\n",n);
   p=head;
   if(head!=NULL)
       do 
       {
           printf("%1d %5.1f\n",p->num,p->score);
           p=p->next;
       } while (p!=NULL);
}

struct student *del(struct student *head,long num) /*链表的删除操作*/
{
    struct student *p1,*p2;
    if(head==NULL)
    {
        printf("\nlist is null! \n");
        return NULL;
    }
    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:%1d\n",num);
       n=n-1;
    }
    else
    {
        printf("%1d not been found! \n",num);
    }
    return head;
}

struct student * insert(struct student *head,struct student *stud) /*链表的插入*/
{
  struct student *p0,*p1,*p2;
  p1=head;//链表的头结点
  p0=stud;//待插入的结点
  if(head==NULL) //之前的链表是一张空表
  {
      head=p0;
      p0->next=NULL;
  }
  else
  {
      while ((p0->num>p1->num) && (p1->next!=NULL))//待插入结点的值比较大，那么就往后面挪
      {
          p2=p1;
          p1=p1->next;
          if(p0->num<=p1->num)//找到要插入的位置了
          {
             if(head==p1)
             {
                 head=p0;
             }
             else
             {
                p2->next=p0;
             }
             p0->next=p1;
          }
          else//插到链表尾
          {
              p1->next=p0;
              p1->next=NULL;

          }
          n=n+1;
          return head;
      }
  }
}

void main()
{
   struct student *head,*stu;//stu
   long del_num;
   printf("input records:\n");
   head=creat();
   print(head);
   printf("\ninput the deleted number:");
   scanf("%1d",&del_num);

   /*head=del(head,del_num);
   print(head);
   printf("\ninput the inserted record:");
   scanf("%1d,%f",&stu.num,&stu.score);
   head=insert(head,&stu);
   print(head);*/

   while(del_num != 0)
   {
       head=del(head,del_num);
       print(head);
       printf("input the deleted number:");
       scanf("%1d",&del_num);
   }
   printf("\ninput the inserted record:");
   stu=(struct student *)malloc(LEN);
   scanf("%1d,%f",&stu->num,&stu->score);
   while(stu->num!=0)
   {
     head=insert(head,stu);
     print(head);
     printf("input the inserted record:");
     stu=(struct student*)malloc(LEN);
     scanf("%1d,%f",&stu->num,&stu->score);
   }
}