Numericupdown强制千位密码器更新每个按键的文本

 private void numericUpDown1_KeyUp(object sender, KeyEventArgs e)
        {
            numericUpDown1.Focus();
            //Edit:
            numericUpDown1.Select(desiredPosition,0)
        }

public class NumericUpDownExt : NumericUpDown
{
    private static FieldInfo upDownEditField;
    private static PropertyInfo selectionStartProperty;
    private static PropertyInfo selectionLengthProperty;

    static NumericUpDownExt()
    {
        upDownEditField = (typeof(UpDownBase)).GetField("upDownEdit", BindingFlags.Instance | BindingFlags.NonPublic);
        Type upDownEditType = upDownEditField.FieldType;
        selectionStartProperty = upDownEditType.GetProperty("SelectionStart");
        selectionLengthProperty = upDownEditType.GetProperty("SelectionLength");
    }

    public NumericUpDownExt() : base()
    {
    }

    public int SelectionStart
    {
        get
        {
            return Convert.ToInt32(selectionStartProperty.GetValue(upDownEditField.GetValue(this), null));
        }
        set
        {
            if (value >= 0)
            {
                selectionStartProperty.SetValue(upDownEditField.GetValue(this), value, null);
            }
        }
    }

    public int SelectionLength
    {
        get
        {
            return Convert.ToInt32(selectionLengthProperty.GetValue(upDownEditField.GetValue(this), null));
        }
        set
        {
            selectionLengthProperty.SetValue(upDownEditField.GetValue(this), value, null);
        }
    }

    protected override void OnTextChanged(EventArgs e)
    {
        int pos = SelectionStart;
        string textBefore = this.Text;
        ParseEditText();
        string textAfter = this.Text;
        pos += textAfter.Length - textBefore.Length;
        SelectionStart = pos;
        base.OnTextChanged(e);
    }
}