C++ error: cannot declare field to be of abstract type
<p>This is the situation:</p>

<pre><code>class Base {  
    virtual void methodA() = 0;  
    virtual void methodB() = 0;  
};

class Base_A : public Base {  
    void methodA(); 
    void methodB();  
};

class Base_B : public Base {  
    void methodA();  
    void methodB();  
};

class MyClass {
    private:  
        Base * b;   
};
</code></pre>

<p>When I compile it gives the error message:</p>

<p><code>
error: cannot declare field MyClass::b to be of abstract type because the following  virtual functions are pure within Base:<br />
    Base::methodA()<br />
    Base::methodB()
</code></p>

<p>How to solve this?</p>

<p><strong>UPDATE</strong>
It compiles now. I dont'know what I have changed</p>
