学步园

type
  PStringArray = array of String;

// before you use the method,
// the objects you will search have to be sort ascending
function BinarySearch(Strs: PStringArray; Count: Integer;
            const str: String): Integer;
var
  Left, Right, Middle: Integer;
  ResultValue: Integer;
begin
  Left := 0;
  Right := pred(Count);
  while (Left <= Right) do
  begin
    Middle := (Left + Right) div 2;
    ResultValue := CompareText(Strs[Middle], str);
    if (ResultValue = 0) then
    begin
      Result := Middle;
      Exit;
    end
    else if (ResultValue < 0)then
      Left := Middle + 1
    else
      Right := Middle - 1;
  end;
  Result := -1;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  str: String;
  value: Integer;
  i: Integer;
  PStringArr: PStringArray;
begin
  str := Edit1.Text;
  SetLength(PStringArr, ListBox1.Items.Count);
  for i := 0 to ListBox1.Items.Count - 1 do
  begin
    PStringArr[i] := ListBox1.Items[i];
  end;
  //value := SequenSearch(PStringArr, ListBox1.Items.Count, str);
  value := BinarySearch(PStringArr, ListBox1.Items.Count, str);
  if value <> -1 then
    ShowMessage('Congregate you! You find it')
  else
    ShowMessage('Sorry, you don''t find it!');
end;