Delphi or函数的用法

function GetFlag(a: string): Integer;
var
I: Integer;
begin
Result := 0;
for I := 0 to 3 - 1 do
begin
if a = '0' then
Result := Result or 1
else Result := Result or 2;
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
I: Integer;
begin
I := GetFlag('3');
ShowMessage(IntToStr(I));
end;