Inheritance in C++ programming

Inheritance in C++ programming

Introduction

What is Inheritance in C++

Advantages of Inheritance in C++

Types of Inheritance in c++

• Single Inheritance
• Multiple Inheritance
• Hierarchical Inheritance
• Multilevel Inheritance
• Hybrid Inheritance

Single Inheritance

Example

#include <iostream>
using namespace std;
 class Account
 {
   public:
   float salary = 75000;
 };
   class Programmer: public Account
   {
   public:
   float bonus = 10000;
   };
int main(void)
{
     Programmer p1;
     cout<<"Salary: "<<p1.salary<<endl;
     cout<<"Bonus: "<<p1.bonus<<endl;
    return 0;
}

Output

Salary: 75000
Bonus: 10000

Example

#include <iostream>
using namespace std;
class A
{
    protected:
     int a;
    public:
    void get_a(int n)
    {
        a = n;
    }
};
class B
{
    protected:
    int b;
    public:
    void get_b(int n)
    {
        b = n;
    }
};
class C : public A,public B
{
   public:
    void display()
    {
        std::cout << "The value of a is : " <<a<< std::endl;
        std::cout << "The value of b is : " <<b<< std::endl;
        cout<<"The addition of a and b is : "<<a+b;
    }
};
int main()
{
   C c;
   c.get_a(120);
   c.get_b(80);
   c.display();
    return 0;
}

Output

The value of a is : 120
The value of b is : 80
The addition of a and b is : 200

Hierarchical Inheritance

Example

#include <iostream>
using namespace std;
class Shape // Declaration of base class.
{
    public:
    int X;
    int Y;
    void get_data(int n,int m)
    {
        X= n;
        Y= m;
    }
};
class Rectangle : public Shape // inheriting Shape class
{
    public:
    int rect_area()
    {
        int result = X*Y;
        return result;
    }
};
class Triangle : public Shape // inheriting Shape class
{
    public:
    int triangle_area()
    {
        float result = 0.5*X*Y;
        return result;
    }
};
int main()
{
    Rectangle r;
    Triangle t;
    int length,breadth,base,height;
    std::cout << "Enter the length and breadth of a rectangle: " << std::endl;
    cin>>length>>breadth;
    r.get_data(length,breadth);
    int m = r.rect_area();
    std::cout << "Area of the rectangle is : " <<m<< std::endl;
    std::cout << "Enter the base and height of the triangle: " << std::endl;
    cin>>base>>height;
    t.get_data(base,height);
    float n = t.triangle_area();
    std::cout <<"Area of the triangle is : " << n<<std::endl;
    return 0;
}

Output

Enter the length and breadth of a rectangle:
24
20
Area of the rectangle is : 480
Enter the base and height of the triangle:
2
5
Area of the triangle is : 5

Multilevel Inheritance

Example

#include <iostream>
using namespace std;
 class Animal
{
   public:
 void eat()
 {
    cout<<"Eating..."<<endl;
 }
};
   class Dog: public Animal
   {
       public:
     void bark()
     {
    cout<<"Barking..."<<endl;
     }
   };
   class BabyDog: public Dog
   {
       public:
     void sleep()
     {
    cout<<"Sleeping...";
     }
   };
int main(void)
{
    BabyDog d1;
    d1.eat();
    d1.bark();
    d1.sleep();
     return 0;
}

Output

Eating...
Barking...
Sleeping...

Hybrid Inheritance

Example

#include <iostream>
using namespace std;
class A
{
    protected:
    int a;
    public:
    void get_a()
    {
       std::cout << "Enter the value of 'a' : " << std::endl;
       cin>>a;
    }
};
class B : public A
{
    protected:
    int b;
    public:
    void get_b()
    {
        std::cout << "Enter the value of 'b' : " << std::endl;
       cin>>b;
    }
};
class C
{
    protected:
    int c;
    public:
    void get_c()
    {
        std::cout << "Enter the value of c is : " << std::endl;
        cin>>c;
    }
};
class D : public B, public C
{
    protected:
    int d;
    public:
    void mul()
    {
         get_a();
         get_b();
         get_c();
         std::cout << "Multiplication of a,b,c is : " <<a*b*c<< std::endl;
    }
};
int main()
{
    D d;
    d.mul();
    return 0;
}

Output

Enter the value of 'a' :
120
Enter the value of 'b' :
20
Enter the value of c is :
310
Multiplication of a,b,c is : 744000

Visibility mode in Inheritance in C++

• Public- if the member is declared as a public member then it is accessible to all the functions of c++ program
• Private- if the member is declared as a private member the it is only accessible by some particular class
• Protected- if the member is declared as a protected member then only its own class and the derived class can only access them

Visibility of the inherited member

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