Compilare: user.cpp: In function ‘std::vector<int> multiply(std::vector<int>, std::vector<int>)’: user.cpp:59:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i(0); i < a.size(); i++) ~~^~~~~~~~~~ user.cpp:61:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i(0); i < b.size(); i++) ~~^~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:141:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i(nrbiti * a.size() - 1); i < nrbiti * b.size(); i += nrbiti) ~~^~~~~~~~~~~~~~~~~~~