Compilare: user.cpp: In member function ‘HN& HN::operator+(const HN&)’: user.cpp:42:12: warning: reference to local variable ‘ans’ returned [-Wreturn-local-addr] HN ans = *this; ^ user.cpp: In function ‘int main()’: user.cpp:59:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("culori3.in", "r", stdin); ^ user.cpp:60:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("culori3.out", "w", stdout); ^ user.cpp:62:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^