Compilare: user.cpp: In function ‘int main()’: user.cpp:22: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:23: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘long int tabela(const long int&, const long int&)’: user.cpp:17: warning: control reaches end of non-void function