的含义是什么?操作员? [英] What is the meaning of the ? operator?

问题描述

可能重复:
C#使用问题在类型后标记，例如:int? myVariable;这是做什么用的?

Possible Duplicate:
C# using the question mark after a type, for example: int? myVariable; what is this used for?

我看到?运算符在很多地方都使用过，并尝试使用Google和StackOverflow，但两个搜索引擎都将其从查询中排除，并且未返回任何好的答案.

I saw the ? operator used in many places and tried to Google and StackOverflow it but both search engine exclude it from the query and does not return any good answers.

该运算符的含义是什么?我通常会在类型声明后看到它，例如:

What is the meaning of this operator? I usually see it after the type declaration like:

int? x;
DateTime? t;

例如，以下两个int声明之间有什么区别:

What is the difference between the two following declaration of an int for example:

int? x;
// AND
int x;

推荐答案

此运算符不是运算符，而只是

This operator is not an operator, but merely the syntactic sugar for a Nullable type:

int? x;

与

Nullable<int> x;

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