Compilare: user.cpp: In function ‘int main()’: user.cpp:164:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bifo.in", "r", stdin); ^ user.cpp:165:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bifo.out", "w", stdout); ^ user.cpp:166:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s%s%d", s1, s2, &m); ^ user.cpp: In member function ‘void BigNumber::read()’: user.cpp:38:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", v); ^