Código Delphi [-] procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char); begin if not (key in ['A'..'C']) then begin key:=#0; ShowMessage('Carácter inválido.'); end; end;
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char); begin if not (key in ['A'..'C']) then begin key:=#0; ShowMessage('Carácter inválido.'); end; end;