参见英文答案 > What does the question mark in member access mean in C#?                                    2个
>            What do two question marks together mean in C#?                                    17个
>            What is the purpose of a question mark after a type (for example: int? myVariable)?                                    8个
>            Benefits of using the conditional ?: (ternary) operator                                    17个
我见过类似以下不相关的代码：

 Console.Write(myObject?.ToString());
 return isTrue ? "Valid" : "Lie";
 return myObject ?? yourObject;
 int? universalAnswer = 42;

问号的所有用法是相关的还是不同的？他们每个人的意思是什么？

解决方法:

问号在C#中具有不同的含义,具体取决于上下文.

空条件运算符(MSDN,What does the question mark in member access mean in C#?)

Console.Write(myObject?.Items?[0].ToString());

条件运算符/三元运算符(MSDN,Benefits of using the conditional ?: (ternary) operator)

return isTrue ? "Valid" : "Lie";

Null Coalescing Operator(MSDN,What do two question marks together mean in C#?)

return myObject ?? yourObject;

可空类型(MSDN,What is the purpose of a question mark after a type (for example: int? myVariable)?)

int? universalAnswer = 42;