39multi-level.cpp

#include <iostream>
using namespace std;

class student
{
protected:
    int roll_no;

public:
    void setRoll_no(int);
    void getRoll_no(void);
};
void student ::setRoll_no(int num)
{
    roll_no = num;
}
void student ::getRoll_no()
{
    cout << "Student Roll Number : " << roll_no << endl;
}
class exam : public student
{
protected:
    float maths, physics;

public:
    void setMarks(float m, float p)
    {
        maths = m;
        physics = p;
    }
    void getMarks(void)
    {
        cout << "Math marks : " << maths << endl;
        cout << "Physics marks : " << physics << endl;
    }
};
class result : public exam
{
private:
    float percentage;

public:
    void display()
    {
        getRoll_no();
        cout << "Your percentage is : " << ((maths + physics) / 2 )<<"%"<<endl;
    }
};
int main()
{
    /*NOTE
    The follow of inheritance is Student(A) --> Exam(B) --> Result(C)
    A is the base for B and B is the base for C
    ABC / A-->B-->C is called the inheritance path
    */
    result kid1;
    kid1.setRoll_no(24);
    kid1.setMarks(86.8, 67.45);
    kid1.display();

    return 0;
}