#Inheritance
Inheritance and Different Types of Inheritance in English 2020
Inheritance in C++
The capability of a class to derive properties and characteristics from another class is called Inheritance. Inheritance is one of the most important feature of Object Oriented Programming.
Sub Class: The class that inherits properties from another class is called Sub class or Derived Class.
Super Class:The class whose properties are inherited by sub class is called Base Class or Super class.
The article is divided into following subtopics:
Why and when to use inheritance?
Modes of Inheritance
Types of Inheritance
Why and when to use inheritance?
Consider a group of vehicles. You need to create classes for Bus, Car and Truck. The methods fuelAmount(), capacity(), applyBrakes() will be same for all of the three classes. If we create these classes avoiding inheritance then we have to write all of these functions in each of the three classes as shown in below figure:
You can clearly see that above process results in duplication of same code 3 times. This increases the chances of error and data redundancy. To avoid this type of situation, inheritance is used. If we create a class Vehicle and write these three functions in it and inherit the rest of the classes from the vehicle class, then we can simply avoid the duplication of data and increase re-usability. Look at the below diagram in which the three classes are inherited from vehicle class:
Modes of Inheritance
Public mode: If we derive a sub class from a public base class. Then the public member of the base class will become public in the derived class and protected members of the base class will become protected in derived class.
Protected mode: If we derive a sub class from a Protected base class. Then both public member and protected members of the base class will become protected in derived class.
Private mode: If we derive a sub class from a Private base class. Then both public member and protected members of the base class will become Private in derived class.
TYPES OF INHERITANCE
Single inheritance
Multi-level inheritance
Multiple inheritance
Multipath inheritance
Hierarchical Inheritance
Hybrid Inheritance
Single inheritance
In this inheritance, a derived class is created from a single base class.
In the given example, Class A is the parent class and Class B is the child class since Class B inherits the features and behavior of the parent class A.
Multi-level inheritance
In this inheritance, a derived class is created from another derived class.
In the given example, class c inherits the properties and behavior of class B and class B inherits the properties and behavior of class B. So, here A is the parent class of B and class B is the parent class of C. So, here class C implicitly inherits the properties and behavior of class A along with Class B i.e there is a multilevel of inheritance.
Multiple inheritance
In this inheritance, a derived class is created from more than one base class. This inheritance is not supported by .NET Languages like C#, F# etc. and Java Language.
In the given example, class c inherits the properties and behavior of class B and class A at same level. So, here A and Class B both are the parent classes for Class C.
Multipath inheritance
In this inheritance, a derived class is created from another derived classes and the same base class of another derived classes. This inheritance is not supported by .NET Languages like C#, F# etc.
In the given example, class D inherits the properties and behavior of class C and class B as well as Class A. Both class C and class B inherits the Class A. So, Class A is the parent for Class B and Class C as well as Class D. So it's making it Multipath inheritance.
Hierarchical Inheritance
In this inheritance, more than one derived classes are created from a single base class and futher child classes act as parent classes for more than one child classes.
In the given example, class A has two childs class B and class D. Further, class B and class C both are having two childs - class D and E; class F and G respectively.
Hybrid inheritance
This is combination of more than one inheritance. Hence, it may be a combination of Multilevel and Multiple inheritance or Hierarchical and Multilevel inheritance or Hierarchical and Multipath inheritance or Hierarchical, Multilevel and Multiple inheritance.
Since .NET Languages like C#, F# etc. does not support multiple and multipath inheritance. Hence hybrid inheritance with a combination of multiple or multipath inheritances is not supported by .NET Languages.