Inheritance

Inheritance allows the combination of one or more classes. Let's look at an example of inheritance:

class Vehicle {
  public:
    TankLevel getTankLevel() const;
    void turnOn();
};

class Car : public Vehicle {
  public:
    bool isTrunkOpen();
};

In this example, the Car class inherits from the Vehicle class, or, we can say Car derives from Vehicle. In C++ terminology, Vehicle is the base class, and Car is the derived class.

When defining a class, we can specify the classes it derives from by appending :, followed by one or more classes, separated by a comma:

class Car : public Vehicle, public Transport {
}

When specifying the list of classes to derive from, we can also specify the visibility of the inheritance – private, protected, or public.

The visibility modifier specifies who can know about the inheritance relationship between the classes.

The methods of the base class can be accessed as methods of the derived class based on the following rules:

Car car;
car.turnOn();

When the...