Effects: Calls str.setf(ios_base::dec, ios_base::basefield).
Effects: Calls str.setf(ios_base::hex, ios_base::basefield).
Returns: str.
Effects: Calls str.setf(ios_base::oct, ios_base::basefield).
Returns: str.
The function signature dec(ios_base&) can be called by the function signature basic_ostream& stream::operator<<(ios_base& (*)(ios_base&)) to permit expressions of the form cout << dec to change the format flags stored in cout.