Page 199 - DCAP404 _Object Oriented Programming

Object-oriented Programming

Notes inheritance by the child might cause some problems. All the public and protected members of
‘grandparent’ are inherited into ‘child’ twice, first via ‘parent1’ and again via ‘parent2’. So, there
occurs a duplicacy which should be avoided.
The duplication of the inherited members can be avoided by making common base class as the
virtual base class: for e.g.

class g_parent
{
//Body
};
class parent1: virtual public g_parent
{

// Body
};
class parent2: public virtual g_parent
{
// Body
};
class child : public parent1, public parent2
{
// body

};
When a class is virtual base class, C++ takes necessary care to see that only one copy of that class
is inherited, regardless of how many inheritance paths exists between virtual base class and
derived class.

Notes Note that keywords ‘virtual’ and ‘public’ can be used in either order.

//Program to show the virtual base class
# include < iostream.h>

# include < conio.h>
class student // Base class declaration
{
protected:
int r_no;
public:
void get_n (int a)
{ r_no = a;}
void put_n (void)

192 LOVELY PROFESSIONAL UNIVERSITY