class A {
protected:
     A *inner;
public:
    ....
    virtual void doSomething() = 0;
    ....
}

class B: public A {
   ...
   void doSomething() {
       if(inner != NULL)
           inner->doSomething();
   }
   ...
}

当我使用inner-> doSomething()时,我得到了一个分段错误.
我应该怎么做才能在B类中调用inner-> doSomething()？

提前致谢.