How can I allow only 0 or 1 to be entered in a TextBox?

Question

How can I limit the TextBox control to only allow the values 0 and 1?

Thanks. And I have one more question: How can I disable put text from clipboard in my textbox c

Answer 1

By using the event KeyPress

private void NumericOnlyKeyBox_KeyPress(object sender, KeyPressEventArgs e)
{
    var validKeys = new[] { Keys.Back, Keys.D0, Keys.D1 };

    e.Handled = !validKeys.Contains((Keys)e.KeyChar);
}

Setting e.Handled to true / false indicates if the character should be accepted to the box or not.

You can read more about KeyPressEventArgs on MSDN.

Note

Keys.Delete should cover Keys.Delete, Keys.Backspace and other "Back" buttons.