请问如何删除指定的某一行~我弄了很久的没弄出~
我这是一个书籍管理的程序，现在我想输入某书号，然后删除该书的信息，但我这程序运行完之后并没有删除信息，请高手帮忙看看。 fdat.seekg(0,ios::beg);
book *a ;
int n , i , bh ,flag = 0;
cout<<"需要删除的书号\n";
cin>>bh;
fdat.seekg( 0, ios::end );
long posend = fdat.tellg( );
n = posend/sizeof(book);
a = new book [n];
fdat.seekg( 0, ios::beg);
i = 0;
do
{
fdat.read( (char *) & a[i], sizeof(book));
i++;
}
while ( posend!=fdat.tellp() );
i=0;
do
{
if( a[i].num == bh)
{ cout << "该记录为:" << endl ;
cout << "编号：" << a[i].num << endl;
cout << "书名:"<< a[i].name << endl ;
cout << "出版社：" << a[i].publish << endl ;
cout << "作者:"<< a[i].author << endl ;
cout << "价格：" << a[i].price << endl ;
flag=1;
goto L;
}
fdat.write((char*)&a[i],sizeof(book));
L: i++;
} while (i != n );
fdat.close();
fdat.open ( fileDat , ios::binary | ios::in | ios::out ) ;
delete []a;
break;
