問題：
Typically the main use of the question mark is for the conditional, x ? "yes" : "no"通常，問號的主要用途是用於條件x ? "yes" : "no" x ? "yes" : "no" . x ? "yes" : "no" 。
But I have seen another use for it but can't find an explanation of this use of the ?但是我已經看到了它的另一種用途，但找不到對? operator, for example.運營商，例如。
public int? myProperty
{
get;
set;
}
解決方案：
參考一： https://en.stackoom.com/question/BI14參考二： https://stackoom.com/question/BI14