这个c ++类声明是什么意思？ [英] What does this c++ class declaration mean?

问题描述

我在阅读的文章中看到了这段代码。

I saw this piece of code in an article I am reading.

class EXAMPLEUNMANAGEDDLL_API CUnmanagedTestClass
{
public:
    CUnmanagedTestClass();
    virtual ~CUnmanagedTestClass();
}; 

EXAMPLEUNMANAGEDDLL_API有什么作用？

What does EXAMPLEUNMANAGEDDLL_API do?

谢谢预先

推荐答案

这是为了将类的功能导出或导入DLL。

This is for the purpose of exporting or importing the functions of a class into a DLL.

在MSDN上阅读此文章以获取更多信息：在C ++类中使用dllimport和dllexport

Read this article on MSDN for additional information: Using dllimport and dllexport in C++ Classes

常见的做法是在类的标头中使用条件编译，以便相同标头可用于生成DLL或使用DLL：

The common practice is to use conditional compilation in the headers of the class, so that the same header can be used for producing the DLL or consuming the DLL:

#ifdef EXAMPLEUNMANAGEDDLL_EXPORTS 
    #define EXAMPLEUNMANAGEDDLL_API __declspec(dllexport) 
#else 
    #define EXAMPLEUNMANAGEDDLL_API __declspec(dllimport) 
#endif 

在此示例中，您库的代码或构建脚本将定义符号 EXAMPLEUNMANAGEDDLL_EXPORTS 。

In this example, the code or the buildscripts of your library would define symbol EXAMPLEUNMANAGEDDLL_EXPORTS.

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