convert.cpp: In function `int main()': convert.cpp:11: warning: passing NULL used for non-pointer argument 3 of ` std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::get(_CharT*, int, _CharT) [with _CharT = char, _Traits = std::char_traits<char>]' convert.cpp:12: warning: NULL used in arithmetic convert.cpp:7: warning: unused variable `int i' convert.cpp:7: warning: unused variable `int j'