#include
#include
#include
struct book
{
    FILE *fp;
    int num;
    char name[30];
    char author[30];
    int classnum;
    char pub[30];
    long int time;
    float price;
    struct book *next;
};
void new_book(struct book *head);
void main()
{
    struct book *head=NULL;
    int select;
    printf("是否建立新的图书表单？1·是\t2·否\n");
    scanf("%d",&select);
    if(select==1)
        new_book(head);
    else
    {
        printf("请导入原有的表单？输入文件名称");

    }
}
void new_book(struct book *head)
{
    FILE *fp;
    struct book *s,*last=NULL;
    float x;
    if((fp=fopen("book.txt","wb"))==NULL)
    {
        printf("创立表单失败");
        exit(0);
    }
    do
    {
        printf("输入书号");
        scanf("%d",&s->num);
        getchar();
        if(s->num!=1)
        {
            printf("输入书名");
            gets(s->name);
            printf("输入作者");
            gets(s->author);
            printf("输入分类号");
            scanf("%d",s->classnum);
            getchar();
            printf("输入出版社");
            gets(s->pub);
            printf("输入出版时间");
            scanf("%d",s->time);
            getchar();
            printf("输入价格");
            scanf("%f",&s->price);
            getchar();
            s->next=NULL;
            if(head==NULL)
            {
                head=s;
                last=s;
            }
            else
            {
                last->next=s;
                last=s;
            }
            fwrite(&s,sizeof(book),1,fp);
        }
        else
            break;
    }while(1);
}

两个问题
1。为什么编译的时候会提示error C2065: 'exit' : undeclared identifier
2.我把exit(0)；这一句删了后可以编译链接，运行程序后
运行到输入书号这一步
当我输入一个书号后，就会跳出一个框   unhandled exception in txst..exe:0x0000005:access violation
点击确定后就回去弹出一个标题为find source的文件选择框  
然后   没然后了  不知道怎么办了