asked on

onKeypress Event

I would like to have a editbox in which we can only type numbers and the backspace. I think I have to use the onKeypress event and limit the access to ascii codes but the onkeypress event returns a char.

Thanks

JimBob091197

What about trapping the WM_CHAR message?

E.g.
In your component's declaration:
procedure WMChar(var Msg: TMessage); message WM_CHAR;

In your code:
procedure TMyEdit.WMChar(var Msg: TMessage);
begin
// Only allow backspace, ENTER, Escape and 0..9
if (TWMKey(Msg).CharCode in [8, 13, 27, 48..57]) then
inherited;
end;

Cheers,
JB

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Thaddy

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viktornet

Hello all!

I dont like TMaskEdit. It's kinda crappy. I rahter create my own EditBox as deha2228 is going to do. JimBob's solution is prefect for that task and is very easy to implement ;-)

Gotta get back to class ;->

Regards,
Viktor Ivanov

kretzschmar

hi deho2228,

help this codesample

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
const validchars = [#8,'0','1','2','3','4','5','6','7','8','9'];
begin
if not(key in validchars) then key := #0
end;

meikl

viktornet

Here is an easier way...

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if not key in [#8, #13, #27 '.', '0'..'9'] then key := #0;
end;

Regards,
Viktor Ivanov

kretzschmar

hi viktor,

your comment is just the same, but i ask you for what do you use enter and Escapekey in an editfield?

well my const line could like shown as follows

const validchars = [#8,'0'..'9'];

and the point if want to use can be added

meikl

viktornet

My point is that you could use the shorter way instead of writing all the chars like so...
const validchars = [#8,'0','1','2','3','4','5','6','7','8','9'];

I added some other characters indeed