Как разобраться с TListBox?

   TStringList *list = new TStringList;
 
      list->LoadFromFile("group.txt");
 
    EditCount->Text=IntToStr(list->Count);
 
    if(list->Count>30)
     while(list->Count>30) list->Delete(list->Count-1);
 
   list->SaveToFile("group.txt");
 
   delete list;

void __fastcall TForm2::Button1Click(TObject *Sender)
{
  List->Items->LoadFromFile("group.txt");
  EditCount->Text = List->Count;
  for(int i = List->Count - 1; i > 29; i--)
   List->Items->Delete(i);
  List->Items->SaveToFile("group.txt");
}

   TStringList *SL = new TStringList, *SL2 = new TStringList;
   SL->LoadFromFile("Group.txt");
   EditCount->Text = SL->Count;
   for(int i=0;i<30;i++) SL2->Add(SL->Strings[i]);
   SL2->SaveToFile("Fix.txt");   /*  ("Group.txt") - in old file */
   ListBox1->Items->Assign(SL2);
   delete SL; delete SL2;