C++ virtual base classes
so in the last pages we discuss a situation which would require the use of both multiple and multilevel inheritance, consider a situation where all the three kinds of inheritance, namely,multilevel, multiple, and hierarchical inheritance, are involved, This is illustrated in this figure. The child has two direct base class parent1 and parent2 which themselves have a common base class grandparent. the child inheits the traits of grandparent via two separate paths, it can also inherit directly as shown by the broken line.
The grandparent is sometimes reffered to as indirect base class.