Example

class Abstract {
public:
virtual void fnc() = 0;
};

class Derived: public Base {
public:
virtual void fnc(){}
};

void callDerivedFunction(Abstract *ptr){

Derived *dp = (Derived*) ptr;
dp->fnc();

}

Solution

Do not down cast a pointer of an abstract class to a class that inherits from it.

class Abstract {
public:
virtual void fnc() = 0;
};

class Derived: public Abstract{
public:
virtual void fnc(){}
};

void callDerivedFunction(Abstract *ptr){

ptr->fnc();

}