How to trap invalid point operation

[pierrotsc]

I have a procedure that if the user does not input any values, it will generate an invalid point operation. Is there a way I can trap that and just display a requester instead of a program crash.
It crashes when it reach c:=b/a; if b and a equal zero, then I get the error. I just want to display a nice error message.
Thanks for any help.
Pierrotsc

 

[DjangMan]

if a = 0 then begin
  ShowNiceMessage;
   c := 0;
end
else
  c := b/a;