Compilare: user.cpp: In function ‘bigint operator+(const bigint&, const bigint&)’: user.cpp:46:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (z[i] >= B) ^ user.cpp:48:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (z[0] >= B) ^ user.cpp: In function ‘int main()’: user.cpp:82:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<sum.size();i++) ^