g++ 컴파일시에 오류문

./make_suggest_word_list/main.cpp: In function `int read_word(FILE*, char*, int*)':
./make_suggest_word_list/main.cpp:44: warning: converting to non-pointer type `char' from NULL
./make_suggest_word_list/main.cpp: In function `int make_suggest_word_list()':
./make_suggest_word_list/main.cpp:193: warning: converting to non-pointer type `char' from NULL
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h: In function `const _Tp& std::__median(const _Tp&, const _Tp&, const _Tp&, _Compare) [with _Tp = DSBL_WORD, _Compare = bool (*)(DSBL_WORD&, DSBL_WORD&)]':
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h:2519: instantiated from `void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator > >, _Size = int, _Compare = bool (*)(DSBL_WORD&, DSBL_WORD&)]'
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h:2589: instantiated from `void std::sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator > >, _Compare = bool (*)(DSBL_WORD&, DSBL_WORD&)]'
./make_suggest_word_list/main.cpp:102: instantiated from here
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h:124: error: invalid initialization of reference of type 'DSBL_WORD&' from expression of type 'const DSBL_WORD'
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h:125: error: invalid initialization of reference of type 'DSBL_WORD&' from expression of type 'const DSBL_WORD'
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h:127: error: invalid initialization of reference of type 'DSBL_WORD&' from expression of type 'const DSBL_WORD'
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h:131: error: invalid initialization of reference of type 'DSBL_WORD&' from expression of type 'const DSBL_WORD'
/usr/local/lib/gcc/i386-pc-solaris2.10/3.4.6/../../../../include/c++/3.4.6/bits/stl_algo.h:133: error: invalid initialization of reference of type 'DSBL_WORD&' from expression of type 'const DSBL_WORD'
make: *** [make_suggest.exe] Error 1

이런오류가 나는데 -_-무슨소린지 잘모르겠네요;;