Playing with the C stack

Parameters on the stack appear in memory with the leftmost item at the lowest memory location. Thus you can get a pointer to your functions stack frame, and walk the parameter list, or even cast your stackframe to a struct that can be passed to other functions.

The first sample demonstrates how to retrieve the pointer to any variable parameters passed to the function.

int __cdecl printf(char const* pszFmt,...)

 { 

    char buf[1024];

    return wvsprintf(buf,pszFmt,&pszFmt+1);

 }

This sample demonstrates how the functions passed to a function can be passed to another function.

BOOL InvalidateRect( 

 HWND hwnd, 

 LONG left, 

 LONG top, 

 LONG right, 

 LONG bottom, 

 BOOL fErase)

 {

   return InvalidateRect(hwnd,(LPRECT)&left,fErase); 

 }