链表的删除，插入，查找，排序

输入学号，再输入名字，最后输入成绩，实现输入和输出。
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#include <string.h>
#define LEN sizeof(struct Student)

struct Student
{
int num;
char name[20];
float score;
struct Student *next;
};

int n,h;

struct Student *creat(void)/*动态链表的创建。。*/
{
n=0;
struct Student *head,*p1,*p2;
p1=p2=(struct Student *)malloc(LEN);
printf(" ");
scanf("%d%s%f",&p1->num,p1->name,&p1->score);
printf(" ");
head=NULL;
while(p1->num!=0)
{
n=n+1;
if(n==1)/*其判断的是地址是否连接下去。。*/
head=p1;
else
p2->next=p1;/*向下传地址*/
p2=p1;
p1=(struct Student *)malloc(LEN);
scanf("%d%s%f",&p1->num,p1->name,&p1->score);
printf(" ");
}
p2->next=NULL;
return(head);/*返回的是一个指针类的地址，方便main函数的输出。。*/
}

void print(struct Student *head)/*相当于int max(int x,int y),struct Student相当于int,head相当于head。。*//*这个函数即输出(终结者)*/
{
struct Student *p;
p=head;
while(p!=NULL)
{
printf(" %d %s %5.1f\n",p->num,p->name,p->score);
p=p->next;
}
}

struct Student *del(struct Student *head)/*动态链表的节点删除。。*/
{
printf("\n=============================================");
printf("\n |开始删除学号| ");
printf("\n=============================================\n");
printf("请输入：");
scanf("%d",&n);
printf("- - - - - - - - - - - - - - - - - - - - - - -");
struct Student *p1,*p2;
p1=p2=head;
while(p1->num!=n&&p1->next!=NULL)/*这个函数是在找所要的节点位置。。*/
{
p2=p1;
p1=p1->next;
}
if(p1->num==n)
{
if(p1==head)/*当删除的是第一个节点的时候的讨论。。*/
head=p1->next;/*地址的传送(开始改变)，没有赋值，即把它隔了过去。。*/
else
p2->next=p1->next;/*地址的传送(开始改变)，没有赋值，即把它隔了过去。。*/
printf("\n已经删除学号为%d同学的信息.\n=============================================\n",n);
}
else
printf("\n the number has not been found!");
return head;/*返回改变后的头即 head。。*/
}

struct Student *insert(struct Student *head)/*动态链表的节点的增加。。*/
{
int a,i;
printf("\n=============================================\n");
printf(" |请输入你想要插入多少名学生的信息| ");
printf("\n=============================================\n");
printf("开始输入：");
scanf("%d",&a);
printf("- - - - - - - - - - - - - - - - - - - - - - -\n");
printf("开始插入学生信息:\n");
printf("- - - - - - - - - - - - - - - - - - - - - - -\n");
struct Student *p1,*p2,*p0;
for (i=1;i<=a;i++)
{
p0=(struct Student *)malloc(LEN);
printf(" ");
scanf("%d%s%f",&p0->num,p0->name,&p0->score);
p1=p2=head;
if(head==NULL)/*原表是空表*/
{
head=p0;
p0->next=NULL;
}
else
{
while((p0->num>p1->num)&&(p1->next!=NULL))/*这个函数是在找所要的节点位置。。*/
{
p2=p1;
p1=p1->next;
}
if(p0->num<=p1->num)
{
if(head==p1)
head=p0;/*插到第一个之前,找到头就可以全部输出，另一种方法如下。。*/
/*
第二种方法：
p0->next=head;
head=p0;
*/
else
p2->next=p0;/*插到原队中间，p2为暂时保存的节点防止p1的改变而找不到原来的节点值。。*/
p0->next=p1;
}
else
{
p1->next=p0;
p0->next=NULL;/*插到原队最后。。*/
}
}
}
printf("- - - - - - - - - - - - - - - - - - - - - - -\n");
printf("插入之后的学生信息:\n");
printf("=============================================\n");
return head;
}

struct Student *Sort(struct Student *head)/*按照动态链表中输入的成绩进行排序。。*/
{
printf("=============================================\n");
printf(" |开始排序| \n");
printf("=============================================\n");
printf("从大到小：\n");
printf("- - - - - - - - - - - - - - - - - - - - - - -\n");
struct Student *p,*q;
p=head;
char str[20];
float number1;
int number;
while(p!=NULL)
{
q=p->next;
while(q!=NULL)
{
if(p->score<q->score)
{
number1=p->score;
p->score=q->score;
q->score=number1;
number=p->num;
p->num=q->num;
q->num=number;
strcpy(str,p->name);
strcpy(p->name,q->name);
strcpy(q->name,str);
}
q=q->next;
}
p=p->next;
}
return head;
}

struct Student *find(struct Student *head)/*动态链表的节点的查找。。*/
{
int a;
printf("=============================================\n");
printf(" |请输入你想要查找的学生的学号| \n");
printf("=============================================\n");
printf("开始输入：");
scanf("%d",&a);
printf("=============================================\n");
printf(" |查找的结果| \n");
printf("=============================================\n");
struct Student *p1,*p2;
p1=p2=head;
while (p1->num!=a)
{
p2=p1;
p1=p1->next;
}
p1->next=NULL;
head=p1;
return head;
}

int main()/*此函数有种收所有头的作用，让它们所有的都联系起来。。*/
{
printf("=============================================\n");
printf(" |学号| |姓名| |成绩|\n");
printf("=============================================\n 开始输入，以0 0 0结束。\n");
struct Student *head;
head=creat();/*切记它是void类型的所以用()仔细观察它的联系和聚拢作用。。*/
//print(head);
head=del(head);/*它是有返回值的，所以用(head)。。*/
print(head);
head=insert(head);/*增加节点。。*/
print(head);
head=Sort(head);/*按照动态链表中输入的成绩进行排序。。*/
print(head);
head=find(head);/*动态链表的节点的查找。。*/
print(head);
printf("- - - - - - - - - - - - - - - - - - - - - - -\n");
printf(" *【运行结束】* \n");
return 0;
}