member function as callback function problem

[yccheok]

i try to pass the following global function pointer to a c library function (cvcamSetProperty) which required the third parameter as callback function pointer. --------------------------------------------- BOOL CXFaceRecognitionDlg::OnInitDialog() { // // some code had been eliminated // // making call the the c library function cvcamSetProperty(0, CVCAM_PROP_CALLBACK, callback2); } void callback2(IplImage* image) { } --------------------------------------------- the compilation stage works fine and no problem at all. however, when i try to pass the member function pointer, it failed :( --------------------------------------------- BOOL CXFaceRecognitionDlg::OnInitDialog() { // // some code had been eliminated // // making call the the c library function cvcamSetProperty(0, CVCAM_PROP_CALLBACK, &CXFaceRecognitionDlg::callback); } void CXFaceRecognitionDlg::callback(IplImage* image) { } --------------------------------------------- here is the error message which i obtain when i try to compile the above code: D:\Documents and Settings\Administrator\Desktop\XFaceRecognition\XFaceRecognitionDlg.cpp(144) : error C2664: 'cvcamSetProperty' : cannot convert parameter 3 from 'void (__thiscall CXFaceRecognitionDlg::*)(struct _IplImage *)' to 'void *' There is no context in which this conversion is possible may i now how can i solve this problem? thank you. regards yccheok

[AlexO]

I think it should be static function, if it is a member of a class(plus check the actual signature it might need to be __cdecl)

[csc]

Declare the callback function as static function of the class class CXFaceRecognitionDlg:: ....... { : static void callback(IplImage* image); : } and i think you should not use the & for the call, just use the static function name : cvcamSetProperty(0, CVCAM_PROP_CALLBACK, CXFaceRecognitionDlg::callback);