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

#define LEN sizeof(struct student) //student结构的大小

struct student *creat();//创建链表

struct student *del( struct student *head ,int num); //del函数是用于删除结点，*head是链表的头指针，num是要删除的结点num。

struct student *insert( struct student *head ,struct student *stu_2);//第一个参数是需要被插入的链表
void print(struct student *head);//打印链表 //第二个参数是带插入的结构的地址

struct student {
int num;
float score;
struct student *next;
} ;
int n;//全局变量，用来记录存放了多少数据。

int main() {
struct student *str,*p,stu_2;
int n;

str = creat();
p = str;
print(p);

printf("请输入被删除的学号:\n");
scanf("%d",&n);
str = del(p,n); 
print(str);

printf("请输入要插入的学号:\n");
scanf("%d",&stu_2.num);
printf("Please input the score: ");
scanf("%f",&stu_2.score);

p = insert(str,&stu_2);
print(p);

printf("\n\n");
system("pause");

}
struct student *insert( struct student *head ,struct student *stu_2) {
struct student *p0,*p1,*p2;
p1 = head;
p0 = stu_2;
if( NULL == head) {
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 {			//p0的num最大插入到尾部 
		p1->next = p0;
		p0->next = NULL;
	}
}
n = n+1;

return head; 

}

struct student *del( struct student *head ,int num) {
struct student *p1,*p2;
if( head == NULL) {
printf(“这是个空链表”);
goto END;
}
p1 = head;
while( p1->num!=num && p1->next!=NULL) {
p2 = p1;
p1 = p1->next;
}
if(p1->num == num) {
if(p1 == head) {
head = p1->next;
} else {
p2->next = p1->next;
}
printf("\nDelete No: %d succeed!\n",num);
n = n-1;
} else {
printf(“无法查询到需要删除的数据”);
}

END:
return head;
}

struct student *creat() {
struct student *head;
struct student *p1,*p2;

p1 = p2 = (struct student *)malloc(LEN); //LEN是student结构的大小
printf("Please enter the num :");
scanf("%d",&p1->num);
printf("Please enter the score :");
scanf("%f",&p1->score);

head = NULL;
n = 0;

while(p1->num) {
	n++;
	if( 1 == n) {
		head = p1;
	} else {
		p2->next = p1;
	}

	p2 = p1;
	p1 = (struct student *)malloc(LEN);

	printf("\nPlease enter the num :");
	scanf("%d",&p1->num);
	printf("Please enter  the score :");
	scanf("%f",&p1->score);
}
p2->next = NULL;

return head;

}

void print(struct student *head) {
struct student *p;
printf("\nThere are %d records!\n",n);

p = head;
if(head) {
	do {
		printf("学号为 %d 的成绩是：%f\n",p->num,p->score);
		p = p->next;
	} while(p);
}

}