C ++从基类调用派生类函数

Question

I'm not sure how to call a derived class function from the base class without getting some sort of error, here's a skeleton of the code I'm trying to work with...

class DiceGame{
public:
    virtual void play(){
        // Trying to call the derived class
        // Knockout's play function in here
        // I've been trying this

        DiceGame *game = new Knockout;
        game->play();

        // But it gives me a memory error
    }

class Knockout : public DiceGame{
    void play(){
        // This has the stuff I want to call
    }

main(){
    DiceGame *game = new DiceGame();
    game->play();
}

I have tried forward declaration of the Knockout class, but that gives me an incomplete forward declaration error as well, any advice?

Answer 1

class DiceGame{
public:
    virtual void play() = 0;
};

class Knockout : public DiceGame{
public:
    virtual void play() { // Replace "virtual" with "override" here if your compiler supports "override" keyword.
        // This has the stuff I want to call
    }
};

int main()
{
    DiceGame *game = new Knockout();
    game->play();
    return 0;
}