Compilare: user.cpp: In function ‘void afis(std::vector<std::vector<double> >)’: user.cpp:26:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.size();i++) ^ user.cpp:28:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<a[i].size(); j++) ^ user.cpp: In function ‘void afissol(std::vector<double>)’: user.cpp:39:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v.size(); i++) ^ user.cpp: In function ‘void sters(std::vector<std::vector<double> >&)’: user.cpp:49:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a.size();i++) ^