尝试从C＃调用非托管函数时出现'System.EntryPointNotFoundException'

Question

I finally have a completed C++ DLL but I'm having trouble calling it from C#. It is definitely finding the DLL as when I remove it from the folder I get a different exception, 'DLLNotFoundException'. The full error description is "Unable to find an entry point named 'GetNewInstance' in DLL 'CComms.dll'". The functions are all exported in C++ like so

__declspec(dllexport) DWORD __stdcall GetNewInstance();

and I call it from C# like so

[DllImport("CComms.dll")]
private static extern uint GetNewInstance();
// ... and in main
uint inst = GetNewInstance();

When I use 'dumpbin /exports CComms.dll' I get some wierd output I'm not sure whether the function name is being mangled and that's why it cant find an entry point

7    6 00002FB0 ?GetNewInstance@@YGKXZ = ?GetNewInstance@@YGKXZ (unsigned long
__stdcall GetNewInstance(void))   

I've tried using __cdecl instead of __stdcall, and had the same result. I'm so close to being done with this project, which I've loated all the way through, hopefully this is the last thing in my way.

Thanks.

Answer 1

Has the same problem with VB.NE Didn't get this exception if function declared without __stdcall but had Managed Debugging Assistant 'PInvokeStackImbalance' warning.

in the library function declared

extern "C"  _declspec(dllexport)
int __stdcall GetLine(HWND hwnd, int iLine, TCHAR *buff)

Adde exports.def file to the dll project

EXPORT
  GetLine

and to the linker Additional Options

/DEF:"exports.def"

problem solved

Answer 2

You have 2 ways of creating a DLL.

One is by getting the addresses of the functions (the oldschool way), and the second is by parameters and name (the "new" way, used by .net for example).

I imagine you are not using your C++ dll correctly

Maybe you should be using GetProcAddress GetProcAddress Msdn

Here is some documentation concerning Dll exportation which might come in useful