Required a number in text box in Inno Setup

Question

I found a code here that I needed. To only allow write numbers in a text box. But I still wanted more, which does not offer up the \"Next\" button without write the number i

Answer 1

There are two flaws in the @TLama's answer:

• A user can bypass the check by using Paste command from edit box context menu (and possibly by other kinds of input methods).

  To fix this, you can introduce a last resort check in NextButtonClick.

  I would also suggest adding the check for an empty input there, instead of MyEditChange, as it allows providing feedback to the user, explaining what is wrong.

• On the other hand, Ctrl+C, Ctrl+V and Ctrl+X keys are not working. Particularly a lack of Ctrl+V is not comfortable.

  To fix this, allow these control characters in the MyEditKeyPress.

[Code]

var
  MyEdit: TNewEdit;
  MyPage: TWizardPage;

procedure ValidateMyEdit;
begin
  { enable the next button if the edit box is not empty; disable otherwise }
  WizardForm.NextButton.Enabled := (MyEdit.Text <> '');
end;  

procedure MyEditChange(Sender: TObject);
begin
  ValidateMyEdit;
end;

function IsDigit(C: Char): Boolean;
begin
  Result := (C >= '0') and (C <= '9')
end;

procedure MyEditKeyPress(Sender: TObject; var Key: Char);
begin
  if not ((Key = #8) or { Tab key }
          (Key = #3) or (Key = #22) or (Key = #24) or { Ctrl+C, Ctrl+V, Ctrl+X }
          IsDigit(Key)) then
  begin
    Key := #0;
  end;
end;

procedure InitializeWizard;
begin
  MyPage := CreateCustomPage(wpWelcome, 'Caption', 'Description');

  MyEdit := TNewEdit.Create(WizardForm);
  MyEdit.Parent := MyPage.Surface;
  MyEdit.Left := 0;
  MyEdit.Top := 0;
  MyEdit.Width := 150;
  MyEdit.OnChange := @MyEditChange;
  MyEdit.OnKeyPress := @MyEditKeyPress;
end;

procedure CurPageChanged(CurPageID: Integer);
begin
  if CurPageID = MyPage.ID then
  begin
    ValidateMyEdit;
  end;
end;

function NextButtonClick(CurPageID: Integer): Boolean;
var
  I: Integer;
begin
  Result := True;

  if CurPageID = MyPage.ID then
  begin
    for I := 1 to Length(MyEdit.Text) do
    begin
      if not IsDigit(MyEdit.Text[I]) then
      begin
        MsgBox('Only numbers are allowed', mbError, MB_OK);
        Result := False;
        Break;
      end;
    end;
  end;
end;