c语言 单向动态链表增删

#include <stdio.h>
#include <stdlib.h>
#define LEN sizeof(struct student)

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

int main() {
	struct student *creat();
	struct student *del(struct student *head, long num);
	struct student *insert(struct student *head, struct student *stud);
	void print(struct student*);
	struct student *head, *stu;
	long del_num;
	printf("请输入数据:\n");
	head = creat();
	print(head);
	printf("输入要删除的学号:\n");
	scanf_s("%ld", &del_num);
	while (del_num!=0)
	{
		head = del(head, del_num);
		print(head);
		printf("输入要删除的学号:\n");
		scanf_s("%ld", &del_num);
	}
	printf("输入要插入的结点:\n");
	stu= (struct student *) malloc(LEN);
	scanf_s("%ld,%f", &stu->num, &stu->score);
	while (stu->num != 0)
	{
		head = insert(head,stu);
		print(head);
		printf("输入要插入的结点:\n");
		stu = (struct student *) malloc(LEN);
		scanf_s("%ld,%f", &stu->num, &stu->score);
	}
	return 0;
}

//创建动态链表函数
struct student *creat() {
	struct student *p1, *p2, *head;
	n = 0;
	p1 = p2 = (struct student *) malloc(LEN);
	scanf_s("%ld,%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_s("%ld,%f", &p1->num, &p1->score);
	}
	p2->next = NULL;
	return(head);
}

//定义删除结点的del函数
struct student *del(struct student *head, long num) {
	struct student *p1, *p2;
	p2 = NULL;
	if (head == NULL)
	{
		printf("该链表是空链表");
		return(head);
	}
	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("已删除:%ld", num);
		n = n - 1;
	}
	else printf("没有找到该数据");
	return(head);
}

//定义插入结点的函数
struct student *insert(struct student *head, struct student *stud) {
	struct student *p0, *p1, *p2;
	p0 = stud;
	p1 =p2= head;
	
	if (head == NULL)
	{
		head = p0;
		p0->next = NULL; }
		//return(head);	}
	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;}
	n = n + 1;
	return(head);
}

//定义输出函数
void print(struct student *head) {
	struct student *p;
	printf("\n现在的链表记录如下：\n");
	p = head;
	if (head != NULL)
		do {
			printf("%ld %3.1f\n", p->num, p->score);
			p = p->next;
		} while (p != NULL);
}