Compilare: user.cpp: In function ‘std::vector<std::complex<double> > fft(const std::vector<std::complex<double> >&, ftype)’: user.cpp:24:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < p.size(); ++i) ~~^~~~~~~~~~ user.cpp:34:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < p.size(); ++i) { ~~^~~~~~~~~~ user.cpp: In function ‘std::vector<int> multiply(std::vector<int>, std::vector<int>)’: user.cpp:46:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a.size() < sz) a.push_back(0); ~~~~~~~~~^~~~ user.cpp:47:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(b.size() < sz) b.push_back(0); ~~~~~~~~~^~~~ user.cpp:58:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); ++i) nc.push_back(va[i] * vb[i]); ~~^~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:88:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < c.size(); ++i) ~~^~~~~~~~~~ user.cpp:70:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bacterii2.in", "r", stdin); ^ user.cpp:71:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bacterii2.out", "w", stdout); ^