{
StrToInt example
This example uses two edit boxes and a button on a form. When the user clicks 
the button, the code converts the values in the edit boxes to numbers, adds them, 
and displays a message indicating the sum:
} 
procedure TForm1.Button1Click(Sender: TObject);
var
  I: Integer;
  J: Integer;
begin
  I := StrToInt(Edit1.Text);
  J := StrToInt(Edit2.Text);
  ShowMessage(IntToStr(I + J));
end; 
