Inheritance

We closed the previous chapter by talking about to-have relationships, which eventually led us to composition and aggregation relationships. In this section, we are going to talk about to-be or is-a relationships. The inheritance relationship is a to-be relationship.

An inheritance relationship can also be called an extension relationship because it only adds extra attributes and behaviors to an existing object or class. In the following sections, we'll explain what inheritance means and how it can be implemented in C.

There are situations when an object needs to have the same attributes that exist in another object. In other words, the new object is an extension to the other object.

For example, a student has all the attributes of a person, but may also have extra attributes. See Code Box 8-1:

typedef struct {
  char first_name[32];
  char last_name[32];
  unsigned int birth_year;
} person_t;
typedef struct {
  char first_name[32];
  char last_name...