The Chernotes #2
Your handy study guide and review sheet


Classes in C++ (8 min - medium)


      • Object oriented programming is a style you can adopt. Some languages like ____ and _____ are meant to be object oriented.

      • ____ doesn't have classes, but it was added in C++.

Player Example

      • Why don't we just make loose variables in our code to represent a player?

      • Syntax: What do we need after the closing curly brace when defining a type?

      • A variable made from a class type is called an ______.

      • Creating a new ______ of a class it is called instantiation.

      • Why can't we access "x" directly via the dot operator?

      • How is the default access level for a class different in C++ relative to Java?

Moving the Player

      • Cherno writes a move function. It goes pretty quick - pause it and make sure you understand this. Why pass by reference?

      • How do you move the function into the player class?

Classes vs. Structs (8 min - medium)

What is the difference?

      • What is the default visibility of a class?

      • What is the default visibility of a struct?

      • Are there any other differences between the two?


      • Why do structs exist in C++?

      • The difference comes down to ______.

Cherno's Style Guide

      • When does he use structs?

      • Will Cherno use inheritance with structs? Why or why not?

      • Note: Cherno's guide is a pretty good set of guidelines. There's no absolute rule in industry on this, but what he's suggesting is pretty conventional.

Topic (11 min - medium)


      • Why is he writing a logging system as an example class?

      • What are his goals / features he plans to write for the log class?


      • Follow his example

      • What is the purpose of the m_ convention?

      • Why does he have public written twice?

      • How does the log level system work?


Topic (7 min - easy)


      • Define a constructor

      • Entity example

        1. When we instaniate the entity, what values did it have for x and Y? Why?
          Vocab: These are called garbage values.

        2. First solution is an "init" method. What's the problem with this solution?

Using Constructors

      • Follow Cherno's syntax for creating a constructor. This should look very familiar from Java.

      • What happens if you don't specify a constructor?

      • In Java, primitive types are automatically initialized and set to zero. How is this different in C++?

      • Note: Notice that Cherno doesn't use the new keyword when creating the object. In C++, you only need to use that when you're manually putting it on the heap. But when you use new, you'll need to remove it manually too, using a destructor.

Topic (5 min - medium)

Using Destructors

      • Define Destructor

      • What syntax do we use to designate a destructor?

      • In the entity class, we don't need to manually remove the X and Y, since we didn't manually create it using new.

      • Why would you use a destructor?

      • What is a memory leak? (Google it!)


Topic (8 min - easy)


      • What does inheritance allow us to do?

      • Why is this useful?

Entity Example

      • Why not just copy the code from Entity into Player?

      • What is the syntax to make Player a subclass of Entity in C++?

      • Watch his example of inheritance in use. This should be familiar, it's the same as Java.

      • What is polymorphism?

      • How does Cherno show that Player is a superset of entity?


Arrays (18 min - medium)

The Basics

      • What is an array and why are they useful?

      • How do you declare an array of 5 integers?
        Notice that this is different from Java!

      • How do you access an element of an array?

      • What happens when you try to output the array itself, rather than an index of the array?

      • How might you cause a MemoryAccessViolation with an array?

        • Why is this extremely dangerous?

      • How do you use a for loop to go through an entire array?

      • Why is there a performance hit for using a <= in a for loop?


      • What does Cherno mean when he says that arrays data is stored contiguously?

      • Be able to describe how indexing works.

      • Note: You won't need to replicate the pointer arithmetic on a quiz, but it's interesting to see the wild stuff you can do in C++ with pointers.

Arrays on the Heap

      • Cherno creates two arrays: one on the stack and one on the heap. Be able to briefly describe the difference in their lifetime.

      • How do you get rid of an array created on the heap?

      • Why would you allocate dynamically using the new keyword?

Standard Array in C++ 11

      • Why might someone want to use the "new" std array in C++ 11?

        • Note: C++ 11 came out in 2011. So it's not that new.

      • What basic feature we take for granted in Java is missing from the default array in C++?

      • How might you try to work around this limitation?

        • Example #1: sizeof

        • Example #2: constant

      • How do you create a std::array?

      • What's Cherno's take on raw arrays vs. std arrays?