Compilare: user.cpp: In function ‘void mult()’: user.cpp:45:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<A.size();i++) C[i] = A[i] * B[i]; ~^~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:56:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<A.size();i++) A[i] = B[i] = 0; ~^~~~~~~~~ user.cpp:71:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<C.size();i++) if ((int)(C[i].real() + 0.5)) g<<i<<' '<<(int)(C[i].real() + 0.5)<<'\n'; ~^~~~~~~~~