We often use the term “Inheritance” in a programming context. It’s a feature practised in programming to make the best reuse of the codes. If you recall the concept of “IS-A” in OOP (Object Oriented Programming), you will find it’s based on the Inheritance feature. The implementation of inheritances will help you gain advanced project ideas in C++.
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What is Inheritance?
In the process of Inheritance, the objects of one class acquire the properties and behaviour of another class. Here a new class is derived from the existing base class. The member class derived is usually called a child class and the base class member of the parent class. After the child class is derived, it inherits all the properties and methods from the parent class.
Additionally, the child class can have its exclusive properties and methods intended for a purpose. The additional features added locally to an existing class will not affect the properties it inherited from the parent class. Thus, the new class will have combined features of both classes.
Inheritance in C++
Often, in reality, a programmer needs to develop an object that has to:
1) possess all qualities of its parent, and additionally,
2) in some aspects, persistence is special.
Coding such exceptional properties in the main class may not necessarily be practical and economical. In that case, a new class is derived by extending the base class. Also, deriving it from another class having additional qualities. In this manner, you can reuse, extend, or modify attributes and behaviours which are defined in other classes. Thus the child class derived from multiple classes gives an object that is easy to maintain and port. The derived class is the specialized class for the base class.
Technically, the keyword “extends” is used to inherit a class. C++ uses the colon (“:”) symbol to inherit from a class.
Types of Inheritances
The use of a combination of inheritances and implementation differ for a purpose the classes are derived. There are different types of inheritances available in C++, as listed below:
- Single Inheritance is where a derived class inherits properties and behaviour from a single base class. Example: Class A → Class B.
- Hierarchical Inheritance is where more than one derived class is created from a single base class. Example: Class A → Class B → Class C.
- Multiple Inheritance is for deriving a class from multiple base classes. Here, the child objects programmers create will have combined aspects of characteristics and features from multiple parent classes. These objects do follow their hierarchies of base classes.
- Multilevel Inheritance is where a child class is derived from another derived class. This feature carries combined aspects of multiple classes and follows their hierarchies.
- Hybrid Inheritance is a heterogeneous feature of using multiple inheritances. Here a child class is derived from one or more combinations of single, hierarchical, and multilevel inheritances. This inheritance is adopted for programs to mix different types of inheritance; for example, when mixing a single inheritance with multiple inheritances or maybe a situation when multiple inheritances are mixed within a single program.
Here Class B and Class C both are derived from the base class, Class A.
A hierarchical classification of Cars shows two classes. Both “Petrol Cars” and “Electric Cars” are derived from the base Class ‘Cars.
Hybrid Inheritance In C++
There could be situations where we need to apply two or more types of inheritance combined to design a program. When a program involves more than one type of inheritance, it is called Hybrid Inheritance.
Hybrid inheritance is a combination of simple, multiple inheritance and hierarchical inheritance. Usually, in multiple inheritances, a class is derived from two classes where one of the parent classes is also a derived class and not a base class.
Hybrid inheritance in C++ is the inheritance where a class is derived from more than one form or combinations of any inheritance. The hybrid inheritance in C++ is also called multipath inheritance, where one derived class can inherit properties of the base class in different paths. Sometimes also called multipath inheritance. For example, it can be achieved with a combination of both multilevel and hierarchical inheritance.
In short, hybrid inheritance is a combination of two or more types of inheritance. For example, by implementing single and multilevel inheritances in the same program.
Block Diagram of Hybrid Inheritance
The diagram represents the hybrid combination of two inheritances; the single inheritance and the multiple inheritances. Here, in single inheritance, class B is derived from class A. Similarly, in multiple inheritances, Class D is inherited from multiple classes. Here class B and class C. So, a mix of single inheritance and multiple inheritances forms a hybrid inheritance.
Hybrid inheritance is applicable in the scenarios where we are required to apply more than one inheritance in a program.
Syntax of Hybrid Inheritance In C++
A typical syntax and semantic for hybrid inheritance in C++ will follow as illustrated below:
Examples of Hybrid Inheritance In C++
Example 1: Single + Multiple Inheritance
Let’s see how single and multiple inheritances are implemented.
Each block in this diagram represents a class, and the corresponding arrow the inheritance of a class.
Example 2: Single + Multilevel Inheritance
We can also implement other types of inheritance to constitute hybrid inheritances.
Let’s consider a Real-time example.
We derive a car subclass from the class Vehicle. Another class characterizes Racing. When we derive a final entity, both from the Car class and the Racing class, it will give a combined output. This derivative is Ferrari – the racing car.
Here is a simple program to illustrate the concept of hybrid inheritance in C++.
The Sample Code
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