edit 只能输入数字

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
  if not (key in ['0'..'9','-',#8]) then
    key:= #0;
  if (key='0') and ((Edit1.Text='') or (Edit1.Text='-')) then
    key:= #0;
  if (key='-') and (Edit1.Text<>'') then
    key:= #0;
end;