独特的方式使用空合并运算符 [英] Unique ways to use the Null Coalescing operator

问题描述

我知道在C＃中使用空合并运算符的标准方法是设置默认值。

I know the standard way of using the Null coalescing operator in C# is to set default values.

string nobody = null;
string somebody = "Bob Saget";
string anybody = "";

anybody = nobody   ?? "Mr. T"; // returns Mr. T
anybody = somebody ?? "Mr. T"; // returns "Bob Saget"

还有什么能 ?? 作？它似乎并不如三元运算符是有用的，除了是更简洁且易于阅读：

But what else can ?? be used for? It doesn't seem as useful as the ternary operator, apart from being more concise and easier to read than:

nobody = null;
anybody = nobody == null ? "Bob Saget" : nobody; // returns Bob Saget

因此​​，考虑较少甚至知道空合并运算符...

So given that fewer even know about null coalescing operator...

• 你有没有使用 ?? 别的东西？

是 ?? 必要的，否则你应该只使用三元运算（即
最熟悉的）

Is ?? necessary, or should you just use the ternary operator (that most are familiar with)

推荐答案

好吧，首先，它比标准的三元更容易链：

Well, first of all, it's much easier to chain than the standard ternary:

string anybody = parm1 ?? localDefault ?? globalDefault;

VS

string anyboby = (parm1 != null) ? parm1 
               : ((localDefault != null) ? localDefault 
               : globalDefault);

这也是行之有效的，如果空可能的对象不是一个变量：

It also works well if null-possible object isn't a variable:

string anybody = Parameters["Name"] 
              ?? Settings["Name"] 
              ?? GlobalSetting["Name"];

VS。

string anybody = (Parameters["Name"] != null ? Parameters["Name"] 
                 : (Settings["Name"] != null) ? Settings["Name"]
                 :  GlobalSetting["Name"];

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