小编Cht*_*cas的帖子

我想基于dll导出的类定义派生类.基类在项目A中定义,派生类在项目B中定义.

首先,在项目A中,定义了预处理器MYDLL_BUILD.我使用头文件来指定导出/导入:

    #if !defined(MYDLL_BUILD)
    #   pragma comment(lib, "myDll.lib")
    #endif

    #if defined(MYDLL_BUILD)
    #   define MYDLL_API __declspec(dllexport)
    #else
    #   define MYDLL_API __declspec(dllimport)
    #endif

然后我定义基类:

class MYDLL_API DllObject
{
public:
    virtual ~DllObject() {}
protected:
    DllObject() { m_count = 3; }
private:
    int m_count;
};

在项目B中,未定义预处理器MYDLL_BUILD.这是派生类:

class MyClass : public DllObject
{
public:
    ~MyClass(){}
    MyClass() { m_data = 20; }
private:
    int m_data;
}; 

我已经包含了dll和lib文件,但仍然得到了未解析的外部符号错误:

2>Test_Entry.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall ADAI::DllObject::~DllObject(void)" (__imp_??1DllObject@ADAI@@UAE@XZ) referenced in function "public: virtual __thiscall …