Compilare: user.cpp: In function ‘int back()’: user.cpp:41: warning: no return statement in function returning non-void user.cpp: In function ‘int main()’: user.cpp:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result