Inheritance.md

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C++ Inheritance

In C++, inheritance is a process in which one object acquires all the properties and behaviors of its parent object automatically. In such way, you can reuse, extend or modify the attributes and behaviors which are defined in other class.

In C++, the class which inherits the members of another class is called derived class and the class whose members are inherited is called base class. The derived class is the specialized class for the base class.

Advantage of C++ Inheritance

Code reusability: Now you can reuse the members of your parent class. So, there is no need to define the member again. So less code is required in the class.

Types Of Inheritance

C++ supports five types of inheritance:

1- Single inheritance
2- Multiple inheritance
3- Hierarchical inheritance
4- Multilevel inheritance
5- Hybrid inheritance

C++ Single Inheritance

Single inheritance is defined as the inheritance in which a derived class is inherited from the only one base class.

C++ Single Level Inheritance Example: Inheriting Fields

#include <iostream>  
using namespace std;  
 class Account {  
   public:  
   float salary = 60000;   
 };  
   class Programmer: public Account {  
   public:  
   float bonus = 5000;    
   };       
int main(void) {  
     Programmer p1;  
     cout<<"Salary: "<<p1.salary<<endl;    
     cout<<"Bonus: "<<p1.bonus<<endl;    
    return 0;  
}  

Output

Salary: 60000
Bonus: 5000

---

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

Output

Eating...
Barking...

---

C++ Multilevel Inheritance

#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 weep() {  
    cout<<"Weeping...";   
     }    
   };   
int main(void) {  
    BabyDog d1;  
    d1.eat();  
    d1.bark();  
     d1.weep();  
     return 0;  
}  

Output

Eating...
Barking...
Weeping...

---

C++ Multiple Inheritance

#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<<"Addition of a and b is : "<<a+b;  
    }  
};  
int main()  
{  
   C c;  
   c.get_a(10);  
   c.get_b(20);  
   c.display();  
  
    return 0;  
}  

Output

The value of a is : 10
The value of b is : 20
Addition of a and b is : 30

---

Ambiquity Resolution in Inheritance

Ambiguity can be occurred in using the multiple inheritance when a function with the same name occurs in more than one base class.

Let's understand this through an example:

#include <iostream>  
using namespace std;  
class A  
{  
    public:  
    void display()  
    {  
        std::cout << "Class A" << std::endl;  
    }  
};  
class B  
{  
    public:  
    void display()  
    {  
        std::cout << "Class B" << std::endl;  
    }  
};  
class C : public A, public B  
{  
    void view()  
    {  
        display();  
    }  
};  
int main()  
{  
    C c;  
    c.display();  
    return 0;  
}  

Output

error: reference to 'display' is ambiguous
        display();

---

C++ Hybrid Inheritance

#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' :
10              
Enter the value of 'b' :    
20      
Enter the value of c is :   
30  
Multiplication of a,b,c is : 6000

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