Compilare: user.cpp: In function ‘std::ostream& operator<<(std::ostream&, bigint&)’: user.cpp:44:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<x.size();i++) ^ user.cpp: In function ‘bigint operator-(const bigint&, const bigint&)’: user.cpp:90:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < x.size(); i++){ ^ user.cpp:100:17: warning: unused variable ‘p’ [-Wunused-variable] int p=z[i-1]; ^