[ERROR]
An abstract class is a class that can be used only as a base class of some other class; no objects of an abstract class may be created except as objects representing a base class of a class derived from it.
class A{
public:
virtual void f(void) = 0; //pure virtual function ==> A
//is an abstract class
};
void main(void){
A a;
}
Use a pointer/reference to the object:
void main(void){
A *pa;
}
Use a derived class from abstract class:
class B : public A{
public:
void f(void){}
};
void main(void){
B b;
}