要完整的插入，删除，查找。。。

#include <stdio.h>
#include <malloc.h>

#define LEN sizeof (struct student)

struct student
{
int num;
float score;
struct student *next;
};

int n;/* n是节点个数 */

struct student *creat(); /* 创建链表 */
struct student *del(struct student *head, int del_num);/* 删除 */
void print(struct student *head); /* 打印 */
struct student *insert(struct student *head,struct student *stu);

main()
{
struct student *head, *stu;
int del_num;

head = creat();
print(head);

printf("del_num:");
scanf("%d",&del_num);
while(del_num != 0)
{
head=del(head,del_num);
print(head);
printf("del_num:");
scanf("%d",&del_num);
}

printf("input:");
stu = (struct student* ) malloc (LEN);
scanf("%d,%f",&stu->num,&stu->score);
while(stu->num != 0)
{
head=insert(head,stu);
print(head);
printf("input:");
stu = (struct student* ) malloc (LEN);
scanf("%d,%f",&stu->num,&stu->score);
}

}

struct student *creat()/*函数返回一个指针值,*/
{
struct student *head,*p1,*p2;

n = 0;
p1 =p2 =(struct student* ) malloc (LEN);/*开辟1个长度为LEN的内存*/

printf("input records:\n");
scanf("%d,%f",&p1->num,&p1->score);

head=NULL;
while(p1->num != 0)
{
n++;
if(n == 1)
head= p2= p1;/*把p1所指的结点作为第一个结点*/
else
{
p2->next = p1;/*把p1所指的结点连接表尾*/
p2 = p2->next;
}
p1 = (struct student* ) malloc (LEN);/*开辟新结点，使p1指向它*/
scanf("%d,%f",&p1->num,&p1->score);
p1->next = NULL;
}
return head;
}

void print(struct student *head)
{
struct student *p;

p=head;
printf("output:\n");
if(head != NULL)
do
{
printf("%d,%5.1f\n",p->num,p->score);
p = p->next; /* 将p原来所指的结点中next的值赋予p */
}while(p != NULL);
}

struct student *del(struct student *head, int del_num)
{
struct student *p1,*p2;

if(head == NULL)
printf("\nlist null!!!\n"); /* 空表的情况 */
else
{
p1 = head;
while(del_num != p1->num && p1->next != NULL)
{
p2 = p1;
p1 = p1->next; /* p1后移1个结点 */
}

if(del_num == p1->num) /* 找到 */
{
if(p1 == head) /* 若p1指向的是首结点 */
head = p1->next; /* 把第二个结点的地址赋予head */
else
p2->next = p1->next; /*将下一结点地址富裕前一结点地址 */
}
else
printf("\n not found!!!\n");
}
return(head);
}

struct student *insert(struct student *head,struct student *stu)
{
struct student *p0,*p1,*p2;
p1 = head; p0 = stu;

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;
}
}
}
return(head);
}