Final answer:
In C++, this concept is called composition, where a class can have an attribute whose data type is an existing class and independent of it. It allows you to combine simpler objects or classes to create more complex objects.
Step-by-step explanation:
In C++, the concept that refers to the fact that a class can have an attribute whose data type is an existing class and independent of it is called composition. Composition allows you to create complex objects by combining simpler objects or classes. In this case, a class can have a member variable that is an instance of another class.
For example, let's say we have two classes, Car and Engine. The Car class can have a member variable of type Engine to represent the engine of the car.
Here's an example:
class Engine {
// engine implementation
};
class Car {
Engine engine; // Composition
};
In this example, the Car class has an attribute called engine of type Engine. This attribute is independent of the Car class, meaning it exists on its own and can be used by other classes as well.