C++ GetProcAddress不工作

Question

我有以下代码：

typedef int (WINAPI* fnEngineStart)();


int __stdcall EngineStart()
{
BOOL FreeResult = 0, RunTimeLinkSuccess = 0; //variables for later use
HMODULE LibraryHandle = 0; //Here the handle to API module/dll will be stored.
fnEngineStart fn = 0;

LibraryHandle = AfxLoadLibrary(L"FlowEngine.dll"); //get the handle of our API module
//so it will now be loaded.
if (LibraryHandle != NULL) //if the library loading was successfull..
{
    fn = (fnEngineStart)GetProcAddress(LibraryHandle,
        "fnEngineStart");
    if (RunTimeLinkSuccess = (fn != NULL)) //if operation was successful...
    {
        int ReturnValue = fn(); //call messageboxa function
        //from user32.dll
    }
    else
    {
        MessageBox(0, L"Error", 0, 0);
    }
    FreeResult = FreeLibrary(LibraryHandle);
    //from this process...
    return FreeResult; //routine was successful
}
return EXIT_FAILURE; //else, it failed
}

这段代码对于user32.dll和MessageBoxA来说工作得很好，但我自己的dll却不行……

int __declspec(dllexport) __stdcall fnEngineStart()
{
   MessageBox(0, L"Succes!", 0, 0);
   return 0;
}

我如何让它也适用于我自己的dll？提前谢谢。

Answer 1

您正在处理的问题是Name Mangling。使用extern "C"，这样编译器就不会破坏名称。示例：

extern "C" int __declspec(dllexport) __stdcall fnEngineStart()
{
   MessageBox(0, L"Succes!", 0, 0);
   return 0;
}

注意：__stdcall函数的名称用前导下划线修饰，后跟@，然后是传递到堆栈的参数数量(以字节为单位)。在32位对齐的计算机上，此数字始终是4的倍数。Source

如果您的编译器支持它，您可以在您的dll中执行此操作，并且一切都应该以您现在拥有的方式工作。

extern "C" int __declspec(dllexport) __stdcall fnEngineStart()
{
   #pragma comment(linker, "/EXPORT:" __FUNCTION__ "=" __FUNCDNAME__)
   MessageBox(0, L"Succes!", 0, 0);
   return 0;
}