This example obtains the pointer conversion procedure of the window class, given that we have an anchor-block handle.

#define INCL_WINWINDOWMGR
#define INCL_WINTHUNKAPI
#include <OS2.H>
HWND hwnd;
/* . */
PFN pfn;
char *classname;


WinQueryClassName(hwnd,
                  sizeof(classname),
                  classname);


pfn = WinQueryClassThunkProc(classname);