Compilare: user.cpp:97:2: warning: no newline at end of file user.cpp: In function 'std::istream& operator>>(std::istream&, circle&)': user.cpp:30: warning: no return statement in function returning non-void user.cpp: In function 'std::ostream& operator<<(std::ostream&, circle)': user.cpp:34: warning: no return statement in function returning non-void user.cpp: In function 'std::istream& operator>>(std::istream&, circle&)': user.cpp:30: warning: control reaches end of non-void function