{
UpperCase example
This example uses a list box and a button on a form. Use the Items property editor in the Object Inspector to enter a list of strings in the list box. When the application runs and the button is clicked, the strings in the list box become uppercase.
} 
procedure TForm1.Button1Click(Sender: TObject);
var
  I: Integer;
begin
  for I := 0 to ListBox1.Items.Count -1 do
    ListBox1.Items[I] := UpperCase(ListBox1.Items[I]);
end; 
