Key Concepts

Review core concepts you need to learn to master this subject

Class Members

class City { // attribute int population; public: // method void add_resident() { population++; } };

A C++ class is comprised of class members:

  • Attributes, also known as member data, consist of information about an instance of the class.
  • Methods, also known as member functions, are functions that can be used with an instance of the class.

Access Control Operators

class City { // attribute int population; public: // method void add_resident() { population++; } };

C++ classes have access control operators that designate the scope of class members:

  • public
  • private

public members are accessible everywhere; private members can only be accessed from within the same instance of the class or from friends classes.

Objects

class City { // attribute int population; public: // method void add_resident() { population++; } };

In C++, an object is an instance of a class that encapsulates data and functionality pertaining to that data.

Constructor

class City { // attribute int population; public: // method void add_resident() { population++; } };

For a C++ class, a constructor is a special kind of method that enables control regarding how the objects of a class should be created. Different class constructors can be specified for the same class, but each constructor signature must be unique.

Destructor

class City { // attribute int population; public: // method void add_resident() { population++; } };

For a C++ class, a destructor is a special method that handles object destruction, generally focused on preventing memory leaks. Class destructors don’t take arguments as input and their names are always preceded by a tilde ~.

Classes and Objects
Lesson 1 of 1
  1. 1
    So far, we’ve used several data types, including int, double, std::string, and bool. When we work with int or std::string, we can create variables with certain properties and methods specific to th…
  2. 2
    An empty class is pretty useless. Classes are designed to bring together related information and functionality — time to add stuff inside! Components of a class are called class members. Just l…
  3. 3
    Now that you have a class, let’s create some objects! To refresh your memory, an object is an instance of a class, which encapsulates data and functionality pertaining to that data. To create (or …
  4. 4
    Let’s circle back to that public keyword. What was that about? By default, everything in a class is private, meaning class members are limited to the scope of the class. This makes it easier to ke…
  5. 5
    Is there a way to give an object some data right when it gets created? We’re so glad you asked! A constructor is a special kind of method that lets you decide how the objects of a class get crea…
  6. 6
    So far, you’ve learned how to create and use objects. But there’s another part of the object lifecycle we need to cover: how to destroy them! Muahahaha. It’s actually far less nefarious than it so…
  7. 7
    Hooray! You’ve learned the basics of classes and objects in C++: - Classes are user-defined types. - Objects are instances of classes. - Class members are the data attributes and functions inside o…

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