control input into TEdit

[hayate]

Hi,

With TEdit, I want to put '-' just before and after numbers like that.
-123 or 123-
NOT like -12-3, 123--, -123-

I wrote the code provided below but this one can control '-' put only before numbers.

(OnKeyPress event)
if (Key = '-') and (Edit1.SelStart <> 0) then
begin
Key := #0;
end;

I want to improve or rewrite the code so that '-' can be put just after numbers too.
Is it possible?

Thank you in advance !

 

[richardchaven]

if (Key = '-') and ((Edit1.SelStart <> 0) and (Edit1.SelStart <> Length(Edit.Text) - 1)) then 
begin
    Key := #0;
end;

Cheers

 

[towerbase]

I think that Richard's code would allow numbers to be entered after a trailing minus sign which is probably not what you want.

So I would suggest that you modify the OnKeyPress event handler to something like:

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
var
  p: integer;
  len: integer;
begin
  if key = #8 then exit;         // Allow Backspace at any time

  p := Pos ( '-', Edit1.Text );
  len := Length(Edit1.Text);

  if ( p > 1 ) and ( len > 0 ) then
    key := #0

  else if key = '-' then begin
    if p > 0 then
      key := #0
    else if ( Edit1.SelStart <> 0 ) and ( Edit1.SelStart <> len ) then
      key := #0
  end
end;

Andrew