SIGFPE Error, Why?

I have the following code:

procedure TForm1.FormCreate(Sender: TObject);
var
  cpic: tcomponent;
  whichcol: integer; // have tried extended types
  whichrow: 开发者_如何学Gointeger; // have tried extended types
begin
  for cpic in form1 do
  begin
    if (cpic.ClassType = timage) and (cpic.Tag = 10) then
    begin
      whichcol := timage(cpic).left - left div gap;
      whichrow := timage(cpic).Top - top div gap;
    end;
  end;
end;

This results in the following error:

Error

Project project1.exe raised exception class 'External: SIGFPE'.

With: as the outlined error:

whichcol := (timage(cpic).left - left) div gap;

Should the equation not just return a number value?

SIGFPE = Floating Point Error.

Sounds like a division by zero. You sure gap is non-zero?