Simple strategy pattern example

gistfile1.cpp

class base_iterator
{
private:
    int * pointer;
    
protected:
    virtual void advance(int *& pointer) = 0;
    
public:
    base_iterator & operator++()
    {
        advance(pointer);
    }
};

class iterator : base_iterator
{
    virtual void advance(int *& pointer)
    {
        ++pointer;
    }
};

class reverse_iterator : base_iterator 
{
    virtual void advance(int *& pointer)
    {
        --pointer;
    }
};