Chapter Summary

Classes are the most fundamental feature in C++. Classes let us define new types that are tailored to our own applications, making our programs shorter and easier to modify.

Data abstractionthe ability to define both data and function membersand encapsulationthe ability to protect class members from general accessare fundamental to classes. Member functions define the interface to the class. We encapsulate the class by making the data and functions used by the implementation of a class private.

Classes may define constructors, which are special member functions that control how objects of the class are initialized. Constructors may be overloaded. Every constructor should initialize every data member. Constructors should use a constructor initializer list to initialize the data members. Initializer lists are lists of namevalue pairs where the name is a member and the value is an initial value for that member.

Classes may grant access to their nonpublic members to other classes or functions. A class grants access by making the class or function a friend.

Classes may also define mutable or static members. A mutable member is a data member that is never const; its value may be changed inside a const member function. A static member can be either function or data; static members exist independently of the objects of the class type.