c++ - Explicit DLL function calling any function -


i'm trying make experimental interpreted language based on tutorial http://compilers.iecc.com/crenshaw/ in c++. want implement system calling dll functions @ runtime, i'm trying use explicit linking in c++. type of data , amount of arguments undefined, depends of code processed interpreter, tried use variadic function(because unknown amount of arguments) , void pointers(because unknown type of parameter) still don't works.

the below code test later implemented in project:

typedef void* (winapi *_dllproc)(...); // it's variadic because parameters undefined  // tried using variadic (like this) // void* calldllfunction(lpcwstr dllname, lpcstr funcname, int numargs, ...)  void* calldllfunctiona(lpcwstr dllname, lpcstr funcname, void* val1, void* val2, void* val3, void* val4) {     //va_list ap; // tried use variadic     //     hinstance hinstlib = loadlibrary(dllname);     void* retval;     _dllproc func = (_dllproc)getprocaddress(hinstlib, funcname);      //     //va_start(ap, numargs);     if (hinstlib != null)     {         try         {             retval = (func)(val1, val2, val3, val4);         }         catch (...)         {             throw;         }     }     else     {         cout << "error!" << endl;     }     //va_end(ap);     //     freelibrary(hinstlib);      //     return retval; }  int main( void )  {      calldllfunctiona(l"user32.dll", "messageboxa", 0, "hello", "title", mb_ok);       printf("\n");     system("pause");      return 0; }

the above code show message box:

enter image description here

but displays error message:

enter image description here

probably above error caused because parameters void* wherein correct types (hwnd, lpcstr, lpcstr , uint), values undefined.

so, how can make function call dll function name, type, amount of parameters? possible? how others languages (such python, ruby) during runtime?


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