void enumA(){

    //using namespace std;

    enum MACHINE_STATE {
        INITIAL_STATE,
        STANDBY_STATE,
        RUNNING_STATE,
        EXIT_STATE };

    cout<<"MACHINE_STATE::STANDBY_STATE = "<<static_cast<int>(MACHINE_STATE::STANDBY_STATE)<<endl;

    int state = INITIAL_STATE;  //INITIAL_STATE=0 IS DEFINED ALREADY in struc MACHINE_STATE

    while( EXIT_STATE != state ) {
        cout << "state code = " << state << ": ";
        switch( state ) {
        case INITIAL_STATE:
            cout << "INITIAL_STATE" << endl;
            state = STANDBY_STATE;
            break;
        case STANDBY_STATE:
            cout << "STANDBY_STATE" << endl;
            state = RUNNING_STATE;
            break;
        case RUNNING_STATE:
            cout << "RUNNING_STATE" << endl;
            state = EXIT_STATE;
            break;
        case EXIT_STATE:
            cout << "EXIT_STATE" << endl;
            state = EXIT_STATE;
            break;
        }
    }
}