为什么不能运行
void borrow()       //借阅图书
{
 if(borrowb>=Maxb)
  throw  "error";                                                           
 int x=Maxb-borrowb;
 cout<<endl;
 cout<<"你还能借"<<x<<"本图书"<<endl;
 cout<<endl;
 ifstream in("data1.txt",ios::in|ios::binary);
 if(!in)  cout<<"can not open file"<<endl;
 for(int i=0;i<Bnum;i++)
    in.read((char *)&b[i],sizeof(b[i]));
   in.close();
 ofstream  out("data1.txt",ios::out|ios::binary);
       if(!out)  cout<<"can not open file"<<endl;
  
 char *bna;
 
 int bid;
 char *auth;
 char *pub;
 
 cout<<"输入你要借的图书的信息:"<<endl;
 cout<<"书名    书号    作者     出版社     "<<endl;
 cin>>bna>>bid>>auth>>pub;
 
           for( i=0;i<Bnum;i++)
           {  
   
                  if(b[i].BID != bid)
                  {  
                    continue;
                    if(i==Bnum-1)
                    cout<<"该图书不存在或已不在架!"<<endl;
                  }
                  else
                  {
                        for(int j=i;j<Bnum-1;j++)
                        {b[j]=b[j+1];}
      
                         bookMax--;
                           Bnum--;
                         b[i].booknum --;
                        borrowb++;
                      cout<<"借阅成功!"<<endl;break;
          if(b[i].booknum ==0)
          {
            for(j=0;j<Bnum;j++)
            out.write((char *)&b[j],sizeof(b[j]));                        
            out.close();
            cout<<"asd";
          }
           }
  
  
 cout<<"是否继续借书(Y/N)?"<<endl;
 char z;
 cin>>z;
 if(z=='y'||z=='Y')
  borrow();
 else
  exit;
}