have the item?

Hello,

How can i check, have the Sw.Item(x) ?
If have not  Sw.Item(x) , i take error message.

(Sw.Item(x) as IWebbrowser2) is, explorer window.


procedure create_array;
var
  x: Integer;
  Sw: IShellWindows;
  begin

  sw := CoShellWindows.Create;
  setlength(dizi1,sw.count,sw.count);

 for x := 0 to SW.Count -1 do
  begin
  dizi1[1,x]:=(Sw.Item(x) as IWebbrowser2).LocationURL ;
  dizi1[2,x]:=inttostr(x);

 end;

 end;