Compilare: user.cpp: In function ‘int main()’: user.cpp:54: warning: operation on ‘X’ may be undefined user.cpp:30: warning: unused variable ‘now’ user.cpp:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:39: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result