程序代码：

typedef struct book_ifo{        
    int num;
    char writer[CHAR];
    char name[CHAR];
    double price;
    struct book_ifo *next;
}BOOK;

BOOK *store(BOOK *head)                          //存储
{
    FILE *fp;
    BOOK *ptr, *p;
    p = head;

    if((fp = fopen("bookinfo.txt","w")) == NULL){
        printf("File open error!\n");
        exit(0);
    }
                                                         
    for(ptr = head;ptr;ptr = ptr->next)
    fprintf(fp,"%d   %s   %s %6.2lf\n",ptr->num,ptr->writer,ptr->name,ptr->price);
    if(fclose(fp)){
        printf("Can not close the file!\n");
        exit(0);
    }

    return head;
}