Hybrid inheritance with example

Hybrid inheritance is a combination of two or more types of inheritance (single, multilevel, multiple, hierarchical) in one program. A common form is a diamond: hierarchical inheritance followed by multiple inheritance.

          Student
          /     \
       Test    Sports
          \     /
          Result

Test and Sports are derived from Student (hierarchical); Result is derived from both Test and Sports (multiple). Since Result would get two copies of Student, Student is made a virtual base class to avoid ambiguity.

#include <iostream>
using namespace std;

class Student {
protected:
    int roll;
public:
    void getRoll(int r) { roll = r; }
};

class Test : virtual public Student {
protected:
    float m1, m2;
public:
    void getMarks(float a, float b) { m1 = a; m2 = b; }
};

class Sports : virtual public Student {
protected:
    float score;
public:
    void getScore(float s) { score = s; }
};

class Result : public Test, public Sports {
public:
    void display() {
        cout << "Roll no : " << roll << endl;
        cout << "Marks   : " << m1 << ", " << m2 << endl;
        cout << "Sports  : " << score << endl;
        cout << "Total   : " << m1 + m2 + score << endl;
    }
};

int main() {
    Result r;
    r.getRoll(101);
    r.getMarks(70, 80);
    r.getScore(10);
    r.display();
    return 0;
}

Output:

Roll no : 101
Marks   : 70, 80
Sports  : 10
Total   : 160

Here roll is accessed in Result without ambiguity because only one Student sub-object exists.