这种C ++类声明是什么意思？ [英] What does this kind of C++ class declaration mean?

问题描述

我下载了Ogre3D源代码，并发现了这种类声明：

I downloaded Ogre3D source code, and found this kind of class declaration:

class _OgreExport TimeIndex
{ ...

我知道 TimeIndex是类名，但是 _OgreExport在中间？ CPP参考不包括此类的类声明表单。这是什么？

I know "TimeIndex" is the class name, but what is the "_OgreExport" in the middle? CPP reference doesn't include this kind of class declaration form. What is this?

推荐答案

_OgreExport 是预处理器指令，可扩展为要么

_OgreExport is a preprocessor directive that expands to either

__declspec(dllimport)

文件包含在其模块之外或

when the file is included outside its module or

__declspec(dllexport)

否则。在Windows下，您必须指定要导出/导入的类/方法，以便可以在二进制文件中使用它们。

otherwise. Under Windows, you have to specify which classes/methods you want exported/imported so that they can be used across binaries.

从技术上讲，正如James在评论中指出的那样，宏名称是非法的，因为它以下划线开头。这些名称是为实现保留的。

Technically, as James pointed out in the comments, the macro name is illegal, since it begins with an underscore. These names are reserved for the implementation.

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