type fbstr
  pzData as zstring ptr
  iLen as integer
  iSize as integer
end type

#define MidConstString(_sSrc,_iStart,_iLen) *cast(string ptr,@(type<fbstr>(cast(zstring ptr,cast(fbstr ptr,@(str(_sSrc))))+(_iStart),_iLen,_iLen)))

print MidConstString("Hello World",4,6)