procedure TForm1.Button2Click(Sender: TObject);
begin
Assignfile(f,'student.dat');
Reset(f);
num:=StrToInt(numEdit.Text);
seek(f,num-1);
?????? //删除第num行
CloseFile(f);
end;
begin
Assignfile(f,'student.dat');
Reset(f);
num:=StrToInt(numEdit.Text);
seek(f,num-1);
?????? //删除第num行
CloseFile(f);
end;
xx.delete(i);