[c-prog] Calling a virtual function from another virtual function in a derived class

[sowmya]

Hello,
   I wanted to know if calling a virtual function from another 
virtual function is valid or not.I was working on an assignmnet where 
the functions are pure in the base class and have definitions in the 
derived class.
   I used g++ to compile the code and I was getting a runtime error 
saying "pure virtual function called. aborted".
   The program executes fine when the declaration is removed in the 
base class.Can anyone please tell me the reason? 

I have included the brief structure of the code
class base
{
    public:
    virtual void abc();
    virtual void efg();
};

class derived: public base
{
    public:
    virtual void abc(){  }
    virtual void efg(){  ...
    abc();
   ...
   }
};


Regards,
Sowmya