What is the principle and purpose of inheritance in C++?

In object-oriented programming, C++ inheritance allows a class (referred to as a derived class or subclass) to inherit properties and methods from another class (referred to as a base class or parent class).

The principle of inheritance involves creating a new class (derived class) to inherit the properties and methods of an existing class (base class). The derived class can inherit the base class’s public and protected members, but not its private members. Through inheritance, the derived class can reuse the base class’s code while also adding new members and methods, or modifying the inherited members and methods within the derived class.

The benefits of inheritance include:

1. Code reuse: Inheritance allows derived classes to directly use the members and methods of the base class, avoiding the need to repeatedly write similar code and increasing the maintainability and reusability of the code.
2. Polymorphism: Inheritance is the foundation of achieving polymorphism. Through a base class pointer or reference pointing to a derived class object, object-based polymorphism can be achieved, where the same method can exhibit different behaviors based on the type of object.
3. Extended functionality: Derived classes can add new members and methods to the base class, thereby expanding the functionality of the base class.
4. Modeling inheritance relationships: Inheritance can be used to establish hierarchy between classes, allowing for a better description of the relationships and inheritance between objects.