Have an app that requires the user to enter information on 3 tedits
and 1 tcombobox. An equation is then used to calculate the
relationship between the inputs. However, the users request is not to
have a calculate button. They wish the app to calculate the result on
the fly. That as the user enters the information.

This must be possible as I have seen it before but have no idea how to
code such a feature. My guess is using the components "onenter"
"onexit" features but searching has revealed limited code and info for
this.

I am sure this has probably been requested before but have been unable
to access it.

Many thanks in advance.

procedure TForm1.ediPriceWith1TaxExit(Sender: TObject);
begin
  ...
  UpdateOtherValues(Sender);
end;

procedure TForm1.ediPriceWith2TaxExit(Sender: TObject);
begin
  ...
  UpdateOtherValues(Sender);
end;

procedure TForm1.UpdateOtherValues(Sender: TObject);
begin
  if (Sender = ediPriceWith2Tax) then
  ...
  if (Sender = ediPriceWithTax2) then
  ...
  if (Sender = ediPriceWithTax3) then
  ...
end;

The Sender parameter passes the information on which Control the OnExit
event has happened. And the contents of all the other Controls will be
updated accordingly.