As I'm only seeing C++ code ...
According to the "ISO 14882 - C++ 98" standards document NULL is a
MACRO and may be define in any of these standard includes -
<clocal>, <cstddef>, <cstdio>, <cstdlib>, <cstring>, <ctime>
or <wchar>
None of which you seem to have included within the code of these
screen captures.