C++ code for state machine

Question

This was an interview question to be coded in C++:

Write code for a vending machine: Start with a simple one where it just vends one type of item. So

Answer 1

#include 
#include 

using namespace std;
class State;

enum state{ON=0,OFF};
class Switch {
    private:
        State* offState;
        State* onState;
        State* currState;
    public:
        ~Switch();
        Switch();
        void SetState(int st);
        void on();
        void off();
};
class State{
    public:
        State(){}
        virtual void on(Switch* op){}
        virtual void off(Switch* op){} 
};
class OnState : public State{
    public:
    OnState(){
        cout << "OnState State Initialized" << endl;
    }
    void on(Switch* op);
    void off(Switch* op);
};
class OffState : public State{
    public:
    OffState(){
        cout << "OffState State Initialized" << endl;
    }
    void on(Switch* op);
    void off(Switch* op);
};
Switch::Switch(){
    offState = new OffState();
    onState = new OnState();
    currState=offState;
}
Switch::~Switch(){
    if(offState != NULL)
        delete offState;
    if(onState != NULL)
        delete onState;
}
void Switch::SetState(int newState){
    if(newState == ON)
    {
        currState = onState;
    }
    else if(newState == OFF)
    {
        currState = offState;
    }
}
void Switch::on(){
    currState->on(this);
}
void Switch::off(){
    currState->off(this);
}
void OffState::on(Switch* op){
    cout << "State transition from OFF to ON" << endl;
    op->SetState(ON);
}
void OffState::off(Switch* op){
    cout << "Already in OFF state" << endl;
}
void OnState::on(Switch* op){
    cout << "Already in ON state" << endl;
}
void OnState::off(Switch* op){
    cout << "State transition from ON to OFF" << endl;
    op->SetState(OFF);
}
int main(){
    Switch* swObj = new Switch();
    int ch;
    do{
        switch(ch){
            case 1:     swObj->on();
                    break;
            case 0:     swObj->off();
                    break;
            default :   cout << "Invalid choice"<> ch;  
    }while(true);`enter code here`
    delete swObj;
    return 0;
}