C / C++ / MFC

char *pStart = "codeproject";
char *p = pStart;

int nFound = 0;

for (int i=0;i<file_length;i++)
{
	if (*p == NULL)     // 'codeproject' was found
	{
		nFound++;
		p = pStart;
		continue;
	}
	if (*p == pData[i])
		p++;
	else
		p = pStart;
}

class CXFaceRecognitionDlg : public CDialog
{
// Construction
public:
CXFaceRecognitionDlg(CWnd* pParent = NULL); // standard constructor
static void callback(IplImage* image);
static CXFaceRecognitionDlg* m_pThis; 
};

static CXFaceRecognitionDlg::m_pThis = NULL;

// Somewhere in one of your member function
{
    ...
    m_pThis = this;
    ...
    // call the function that need the callback function
    FunctionThatNeedCallback(callback);
    ...
}

void CXFaceRecognitionDlg::callback(IplImage* image)
{
DetectAndDrawFaces( image ); // c function lib

// Here you can use the static pointer to this

this->DoSomeMemberFunction(...); // must be public

}

void CXFaceRecognitionDlg::callback(IplImage* image)
{
    DetectAndDrawFaces( image ); // c function lib
    //????but how to update CXFaceRecognitionDlg GUI????
}

DetectAndDrawFaces(callback);