用C语言写一个代码，实现链表的建立、输出、输出和插入。

代码：

#include<stdio.h>
#include<malloc.h>
#define LEN sizeof(struct student)
struct student{
	long num;
	float score;
	struct student * next;
};
int n;
int main(){
	struct student * head,stu;
	long del_num;
	struct student *creat();
	void print(struct student *);
	struct student * del(struct student *,long);
	struct student * insert(struct student *,struct student *);
	
	printf("input record :\n");
	head=creat();
	print(head);
	printf("input the deleted number:");
	scanf("%ld",&del_num);
	head=del(head,del_num);
	printf("input the insert number:");
	scanf("%ld,%f",&stu.num,&stu.score);
	head=insert(head,&stu);
	print(head);
	return 0;

}
//创建链表
struct student * creat(void)
{
	struct student *head;
	struct student *p1,*p2;
	n=0;
	p1=p2=(struct student *)malloc(LEN);//开辟一个新单元
	scanf("%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);//开辟动态存储区，把起始地址赋给p1
		scanf("%ld,%f",&p1->num,&p1->score);
	}
	p2->next=NULL;
	return head;
}
//输出链表
void print(struct student * head){
	struct student *p;
	p=head;
	if(head!=NULL)
		do{
			printf("num:%1d score:%5.1f\n",p->num,p->score);
			p=p->next;}
		while(p!=NULL);
}
//删除del函数
struct student * del(struct student * head,long num){
	struct student *p1,*p2;
	if(head==NULL)
	{printf("\nlist null!\n");
	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("delete:%ld\n",num);
		n=n-1;//结点数减一
	}
	else printf("%ld not been found!",num);
	return head;
}
//插入insert函数
struct student * insert(struct student * head,struct student * stud){
	struct student *p0,*p1,*p2;
	p1=head;
	p0=stud;
	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;//插到最后的结点之后
			}
	}
	n=n+1;//结点数加一；
	return head;
}

运行结果：