Compilare: user.cpp: In function ‘void operator+=(big&, big)’: user.cpp:37:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (a.s.size() == i) a.s.push_back(t%base); ^ user.cpp: In function ‘void operator-=(big&, big)’: user.cpp:56:9: warning: unused variable ‘len1’ [-Wunused-variable] int len1 = a.s.size(),len2 = b.s.size(); ^ user.cpp: In function ‘int main()’: user.cpp:75:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aladdin2.out","w",stdout); ^