C++中的_In_是什么？
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What is _In_ in C++?
提问by Infinity James
I have searched this up rather a lot, but come up with no helpful results.
我已经搜索了很多，但没有找到有用的结果。
I am currently trying to program simple DirextX game for Windows 8 Metro, and have come across _In_rather a lot. I'm just wondering what it is.
我目前正在尝试为 Windows 8 Metro 编写简单的 DirextX 游戏，并且遇到_In_了很多。我只是想知道它是什么。
Also, I have seen a lot of the use of ^as the pointer *which I found odd. On top of this, some classes have an interface of ref class MyClass, which I believe is for C# legibility.
此外，我已经看到了很多我觉得奇怪^的指针的使用*。最重要的是，一些类有一个 的接口ref class MyClass，我认为这是为了 C# 的易读性。
Anyway, any help would be brilliant.
无论如何，任何帮助都会很棒。
回答by James McNellis
It is a SAL annotation, used for code analysis. The annotations themselves are defined as macros that, in normal builds, expand to nothing.
它是一个SAL 注释，用于代码分析。注释本身被定义为宏，在正常构建中，这些宏不会扩展到任何内容。
The ^and ref classare features of C++/CX, a set of language extensions developed to make it easier to build Metro style apps for Windows 8 in C++. Neither is a part of standard C++. The documentation (linked previously) has links to tutorials and references describing the language extensions.
在^和ref class有特色C ++ / CX，集开发，使其更容易打造下的Windows 8 Metro风格应用++语言扩展。两者都不是标准 C++ 的一部分。文档（先前链接）包含指向描述语言扩展的教程和参考资料的链接。
回答by Max
I think (from a quick google) that the _in_is there to indicate if a parameter is an input or output (_out_) to a function/method.
我认为（从一个快速的谷歌）_in_那里表明一个参数是_out_一个函数/方法的输入还是输出（）。
The ^is a managed pointer (garbage collected pointer, related to C++/CLI).
的^是一个托管指针（垃圾收集指针，与C ++ / CLI）。
回答by Diptendu
_Out_means argument passed as reference. _In_means the opposite. (_Out_ x)and (&x)are similar.
_Out_表示作为参考传递的参数。_In_意思相反。(_Out_ x)并且(&x)是相似的。
