c#小知识点

?.表示如果不为空
LoginUserCode = s.Element("LoginUserCode") != null ? s.Element("LoginUserCode").Value:string.Empty,
>> LoginUserCode = s.Element("LoginUserCode")?.Value,

$
string menuStr = string.Format("是否子菜单{0}删除？",SelectedMenu.Text);
等同于
$"是否子菜单{SelectedMenu.Text}删除？"

保留两位小数

(Math.Round(decimal.Parse(moneySmall), 2, MidpointRounding.AwayFromZero).ToString()