OOP allows objects to have relationships with each other, like inheritance and aggregation. In this tutorial, we’ll explore the differences between inheritance and aggregation, examine their advantages and disadvantages, and discuss the appropriate use cases for each.

The difference is typically expressed as the difference between "is a" and "has a". Inheritance, the "is a" relationship, is summed up nicely in the Liskov Substitution Principle. Aggregation, the "has a" relationship, is just that - it shows that the aggregating object has one of the aggregated objects.

Today we'll take a closer look at one principle of Object Oriented Programming (OOP): Inheritance. We'll also study other types of relationships between classes: composition and aggregation.

Why aggregation is better then inheritance: 1) You can hide methods (or change names) with inheritance all the methods are available by default. 2) You can use class with no-virtual destructor (std::string and all stl containers).

Choosing between Inheritance and Aggregation. Figure 6.6 is a UML class diagram, showing several aggregation relationships and one inheritance relationship. The class diagram shows a queue defined by aggregation, and a stack defined by inheritance. Both are based on linked lists.