Delphi6如何用程序判断机器有几个COM口？

Question

最好不用读注册表，因为有些用户受权限控制。API行吗？谢谢！

Answer 1

procedure TForm1.Button1Click(Sender: TObject);
var
  hCommFile : THandle;
  I: Integer;
begin
  I := 0;
  repeat
    hCommFile := CreateFile(PChar(Format('COM%d', [I + 1])),
                          GENERIC_READ,
                          0,
                          nil,
                          OPEN_EXISTING,
                          FILE_ATTRIBUTE_NORMAL,
                          0);
    if hCommFile = INVALID_HANDLE_VALUE then Break;
    CloseHandle(hCommFile);
    Inc(I);
  until False;
  Caption := IntToStr(I);
end;