need to fix reference not defined in soundOff
<pre><code>class Flock{
public:
    Flock(string dogName);
    virtual ~Flock();
    virtual void addSheep(string name);
    virtual void soundOff();

    private:
    Dog *dog;
        vector&lt;Sheep*&gt;sheepList;
};

Flock::Flock(string dogName):dog(new Dog(dogName)){}

void Flock::addSheep(string name){
    Sheep *newSheep = new Sheep("name");
    sheepList.push_back(newSheep);
}

Flock::~Flock(){
    delete dog;

    int size = sheepList.size();
    for (int i=1;i&lt;=size;i++){
        sheepList.pop_back();
    }
}
</code></pre>
