作业： 编写链表，链表里面随便搞点数据 使用 fprintf 将链表中所有的数据，保存到文件中 使用 fscanf 读取文件中的数据，写入链表中

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
//链表结构体定义
typedef struct link_list
{
	union
	{
		int data;
		int len;
	};
	struct link_list *next;

}link_list,*link_p;

//创建头结点
link_p creat_head()
{
	link_p H = (link_p)malloc(sizeof(link_list));
	if(H==NULL){
		printf("申请空间失败\n");
		return NULL;
	}
	H->len = 0;
	H->next = NULL;
	return H;
}

//创建新结点
link_p new_nod(int data)
{
	link_p new = (link_p)malloc(sizeof(link_list));
	if(new==NULL){
		printf("申请空间失败\n");
		return NULL;
	}
	new->data = data;
	return new;
}

//尾插
void insert_tail(link_p L,int data)
{
	if(L==NULL){
		printf("入参失败\n");
		return;
	}
	link_p p = L;
	link_p new = new_nod(data);
	while(p->next!=NULL){
		p = p->next;
	}
	new->next = p->next;
	p->next = new;
}

//遍历
void out_put(link_p L)
{
	link_p p = L->next;
	while(p!=NULL){
		printf("%d->",p->data);
		p=p->next;
	}
	printf("NULL");
	putchar(10);
}


int main(int argc, const char *argv[])
{
	link_p L = creat_head();
	insert_tail(L,10);
	insert_tail(L,20);
	insert_tail(L,30);
	insert_tail(L,40);
	//out_put(L);
	link_p p = L->next;
	FILE *wfp = fopen("link.txt","w");
	if(wfp==NULL){
		return 1;
	}
	while(p!=NULL){
		int ret = fprintf(wfp,"%d\n",p->data);
		p=p->next;
	}
	fclose(wfp);
	
	FILE *rfp = fopen("link.txt","r");
	link_p L2 = creat_head();	
	int data=0;
	while(1){
		int ret = fscanf(rfp,"%d",&data);
		printf("%d\n",data);
		if(ret!=1){break;}
		insert_tail(L2,data);
			}
		
	out_put(L2);
	fclose(rfp);
	return 0;
}