Compilare: user.cpp: In function ‘std::vector<std::complex<double> > RecursiveFFT::DFT(std::vector<std::complex<double> >, double)’: user.cpp:19:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < A.size(); i++) ^ user.cpp: In function ‘std::vector<std::complex<double> > RecursiveFFT::FFT(std::vector<std::complex<double> >, std::vector<std::complex<double> >)’: user.cpp:47:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); i++) ^ user.cpp:51:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ans.size(); i++) ^ user.cpp: In function ‘std::vector<std::complex<double> > RecursiveFFT::getArray()’: user.cpp:61:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &K); ^ user.cpp:65:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^ user.cpp: In function ‘void IterativeFFT::getArray(std::vector<std::complex<double> >&)’: user.cpp:149:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &K); ^ user.cpp:153:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^ user.cpp: In function ‘int main()’: user.cpp:175:40: 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:176:42: 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); ^ user.cpp:180:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &T); ^