Getting our machines set up for C++ development, and introducing the fundamental building blocks of programming - variables.

Getting our computer set up so we can create and build C++ programs. Then, creating our very first application

Setting up a C++ Development Environment

An introduction to the building blocks of our software - objects, and the variables that can be associated with them.

Objects, Variables and Types

Creating variables to store and update the data that describes our objects.  We also introduce comments, allowing us to describe our code in plain language.

Creating Variables

An introduction to the different types of numbers in C++, and how we can do basic math operations on them.

Numbers

An overview of the fundamental true or false data type, how we can create them, and how we can combine them.

Booleans - `true` and `false` values

Explore how C++ programs store and manage numbers in computer memory, including integer and floating-point types, memory allocation, and overflow handling.

Types and Literals

Creating a tiny program using numbers and booleans, then adding some breakpoints so we can step through our code in a debugger.

Introduction to Debugging

Types and Variables

Discover how we can package our code into reusable functions that we can easily call.  Then, learn how we can use conditionals and loops to control the flow of our program.

An introduction to functions - reusable blocks of code that we can use to break our application into smaller pieces.

Creating and Calling Functions

An introduction to how our function calls create a call stack, and how we can navigate it in a debugger.

The Call Stack and Debugging Functions

Use booleans and if statements to make our functions and programs more dynamic, choosing different execution paths.

Conditional Logic

Learn an alternative way to write conditionals, which is often used when we want to take different paths based on a specific value

Switch Statements

Allow our functions to communicate with their caller by returning values when they complete

Function `return` Statements

Going into more depth on what is happening when a variable is used as a different type

Implicit Conversions and Narrowing Casts

Making our functions more useful and dynamic by providing them with additional values to use in their execution

Function Arguments and Parameters

Learn more about how and when we can access variables, by understanding the importance of the scope in which they exist.

Scope

Understand what function prototypes are, and learn how we can use them to let us order our code any way we want.

Forward Declarations

Learn how we can use loops to iterate over a block of code, executing it as many times as needed.

Loops

Learn how we can use the modulus operator to get the remainder of integer division, and some common use cases.

The Modulus Operator (`%`)

Put everything we've learned in this chapter to the test by creating a C++ version of the Fizz Buzz game.

Fizz Buzz

Learn how the `&&` and `||` operators are optimized with short-circuit evaluation, only evaluating expressions when necessary

Short-circuit Evaluation

Functions, Conditionals and Loops

Classes and structs are the fundamental feature of object oriented programming.  In this chapter, we will see how we can set them up, and how we can use them to create the custom types our program needs.

Learn how to define, instantiate, and utilize classes, understanding how they form the backbone of object-oriented programming.

Abstraction and Classes

A guide to encapsulation, class invariants, and controlling data access with `public` and `private` specifiers.

Encapsulation and Access Specifiers

Learn about special functions we can add to our classes, control how our objects get created and destroyed.

Constructors and Destructors

Discover the role of structs, how they differ from classes, and how to initialize them without requiring a constructor.

Structs and Aggregate Initialization

This lesson introduces operator overloading, a fundamental concept to create more intuitive and readable code by customizing operators for user-defined types

Operator Overloading

This lesson introduces Structured Binding, a handy tool for unpacking simple data structures

Structured Binding

Classes and Structs

See how we can use inheritance to organise our classes into a hierarchy, unlocking a massive range of possibilities for building more complex software

In this lesson, we explore C++ inheritance, guiding you through creating and managing class hierarchies to streamline your code

Inheritance

Learn about `protected` class members in C++, including how and when to use them in your code, especially in the context of inheritance and class design

Protected Class Members

This lesson introduces Member Initializer Lists, focusing on their advantages for performance and readability, and how to use them effectively

Member Initializer Lists

This lesson provides an in-depth exploration of using inherited methods and variables in C++, covering constructor calls, variable modification, and function shadowing

Working with Inherited Members

An introduction to working with memory, and how we represent memory locations using references and pointers

This lesson introduces references, explaining how they work, their benefits, and their role in performance and data manipulation

References

This lesson provides a thorough introduction to pointers in C++, covering their definition, usage, and the distinction between pointers and references

Pointers

Learn about the `this` pointer in C++ programming, focusing on its application in identifying callers, chaining functions, and overloading operators.

The `this` Pointer

Learn about an important consideration when returning pointers and references from functions

Dangling Pointers and References

Memory, References and Pointers

An introduction to polymorphism - the key tool that let us build more complex programs whilst keeping our code simple.

This lesson provides an in-depth look at function overloading in C++, covering its importance, implementation, and best practices

Function Overloading

Explore the concept of static casting in C++, including examples and best practices for converting data types at compile time

Static Casting

This lesson provides an introduction to virtual functions and overrides, focusing on their role in enabling runtime polymorphism

Virtual Functions and Overrides

Get to grips with downcasting in C++, including static and dynamic casts. This lesson provides clear explanations and practical examples for beginners

Downcasting

Polymorphism

Go deeper on what is happening when we build our software.  Learn how we can use the preprocessor to automatically modify our source code before it is compiled, and how the linker connects our program together.

Explore the essential concepts of C++ preprocessing, from understanding directives to implementing macros

Preprocessor Definitions

Discover how the `#include` directive helps us include library features and split our project across multiple files.

The `#include` Directive

Explore how header files and linkers streamline C++ programming, learning to organize and link our code effectively

Header Files

The Preprocessor and the Linker

Discover additional methods and techniques to keep our data and code organised.

Learn the essentials of using namespaces to organize your code and handle large projects with ease

Namespaces

Learn about Enums and how they offer an efficient way to handle predefined values in your code

Enums

This lesson introduces the `using` keyword in C++, focusing on namespaces, enums, and type aliasing

The `using` Keyword

Namespaces and Enums

Learn how to store collections of objects, and take control of how memory is managed

Explore the fundamentals of dynamic arrays with an introduction to `std::vector`

Dynamic Arrays using `std::vector`

Learn how to manage dynamic memory using unique pointers and the concept of memory ownership

Memory Ownership and Smart Pointers

Explore advanced techniques for managing object copying and resource allocation

Copy Constructors and Operators

Learn the techniques and pitfalls of manual memory management in C++

Managing Memory Manually

Arrays and Dynamic Memory

Techniques to simplify our code, making it easier to understand and maintain

This lesson covers how we can ask the compiler to infer what types we are using through the `auto` keyword

Automatic Type Deduction using `auto`

Learn the intricacies of using `const` and how to apply it in different contexts

Constants and `const`-Correctness

This lesson provides an overview of effective commenting strategies, including Javadoc style commenting for automated documentation

Effective Comments and Javadoc

This lesson introduces the concept of Style Guides and ClangFormat, focusing on how to achieve consistency in our code

Style Guides and Automatic Code Formatting

An introduction to static analysis tools, and how they can help beginners learn faster and improve code quality

Static Analysis

Explore the fundamentals of attributes, including `[[nodiscard]]`, `[[likely]]`, and `[[deprecated]]`

Attributes

Clean Code

A collection of lessons covering a variety of topics worth learning as a beginner

This lesson covers the basics of using randomness, with practical applications

Random Number Generation

Learn the basics of the chrono library and discover how to effectively manage durations, clocks, and time points

Dates, Times and Durations

A detailed guide to string formatting using C++20's `std::format()`, and C++23's `std::print()`

String Interpolation

Learn how to overload the `<<` operator, so our custom types can stream information directly to the console using `std::cout`

Overloading the `<<` Operator

This lesson introduces system calls, and how to use them to clear the terminal

System Calls and Terminal Management

This lesson introduces the fundamentals of capturing user input, using `std::cin` and `std::getline()`

User Input in the Terminal

Unravel the fundamentals of bitwise operators and bit flags in this practical lesson

Bitwise Operators and Bit Flags

Odds and Ends

This course is designed for beginners. We'll take you from the fundamentals and lay a solid foundation for creating real-world programs and learning more advanced concepts.

Become a software engineer with C++.  Starting from the basics, we guide you step by step along the way

This course teaches the fundamentals of C++ while instilling habits used by real-world developers. You'll gain practical experience with concepts that are the foundation of all modern programming.

No previous programming experience is needed - we start from the basics.

Start your Journey

We explain every line of code we're using, so you understand exactly what is happening.

Understand Every Line of Code

Everything we create is organised and implemented using modern, professional practices.

Use Professional Best Practices

We don't just explain what we're doing, but also why. This builds transferrable skills, so you can take what you've learnt and apply them to your own projects.

Focus on Transferrable Skills

No paywalls, no ads - the course is completely free with unlimited access

Free and Unrestricted Access

We break complex concepts into manageable steps, making even advanced topics feel approachable.

Step-by-Step Learning

What You'll Learn

Comprehensive course covering advanced concepts, and how to use them on large-scale projects.

Professional C++

If you're already familiar with the basics of C++ and object oriented programming, you may want to skip to the advanced course.  It starts with a quick summary of everything we cover here.

Already Familiar with Programming?

Intro to C++ Programming

<Excerpt>


Polymorphism is a principle in programming where the same expression can have multiple forms, based on the context in which it is used, or the data types it is used with.


This approach can keep our code simple and readable, even as our program gets more and more complex.


## Types of Polymorphism


In C++, polymorphism manifests mainly in three forms:


### Overloading


This includes both operator and function overloading.

- **Operator Overloading**: Previously, we discussed how operator overloading allows operators to have different behaviors based on their arguments.  For example, expressions like `A + B` will do different things based on the types of `A` and `B`.
- **Function Overloading**: Function overloading allows multiple functions to have the same name but different parameter lists (either in the number of parameters or their type).  This enables an expression like `CalculateArea(MyObject)` to behave differently based on the type of `MyObject`.

### Templates


Templates allow us to define recipes for blocks of code.  The compiler can then use these recipes to generate functions or entire classes that adapt to our needs.


We cover templates in more detail in the next course.


### Run Time Polymorphism


Run Time Polymorphism, which we will cover later in this chapter, interacts with the inheritance trees, pointers, and references we introduced earlier.  It allows our code to behave much more dynamically, without introducing excessive complexity. 


</Excerpt>


## Overloading Functions


To overload functions, we simply define functions within the same scope, that have the same name, but have a different parameter list.


Below, we define a `Rectangle` and `Circle` type.  Alongside each class, we provide standalone `CalculateArea()` functions:


```c++
struct Rectangle {
  float Width;
  float Height;
};

float CalculateArea(const Rectangle& R){
  return R.Width * R.Height;
}
```


```c++
struct Circle {
  float Radius;
};

float PI{3.14};

float CalculateArea(const Circle& C){
  return PI * C.Radius * C.Radius;
}
```


When these functions are both available, they're considered _**overloaded**_.


Elsewhere, in code that uses our classes, we can use a consistent syntax to calculate the area of things.  We just write `CalculateArea(SomeObject)` and, behind the scenes, the compiler chooses which `CalculateArea()` function to call based on the type of `SomeObject`.


From the perspective of the consumer, it doesn't look like they're calling two different functions.  It just looks like there is a single `CalculateArea()` function that adapts depending on how it's used.  In other words, it's behaving **polymorphically**:


```c++
#include <iostream>
using namespace std;

//<c title="Rectangle, Circle, and CalculateArea">
struct Rectangle {
  float Width;
  float Height;
};

float CalculateArea(const Rectangle& R){
  return R.Width * R.Height;
}

struct Circle {
  float Radius;
};

float PI{3.14};

float CalculateArea(const Circle& C){
  return PI * C.Radius * C.Radius;
}
//</c>

int main(){
  Circle MyCircle{2};
  cout << "Circle Area: "
    << CalculateArea(MyCircle);

  Rectangle MyRectangle{3, 4};
  cout << "\nRectangle Area: "
    << CalculateArea(MyRectangle);
}
```


```c++
//<o>
Circle Area: 12.56
Rectangle Area: 12
```


<Quiz title="Function Overloading">


<Question>


After running the following code, what is the value of `MyBool`?


```c++
bool IsFloat(float Number) { return true; }
bool IsFloat(int Number) { return false; }

bool MyBool { IsFloat(5) };
```


<Answer>


This code is invalid


<Feedback>


Review how function overloading works with different data types and consider how `IsFloat(5)` is interpreted by the compiler.


</Feedback>


</Answer>


<Answer>


The boolean value `true`


<Feedback>


Consider the data type of the literal **`5`** and how it matches the function parameters.


</Feedback>


</Answer>


<Answer isCorrect>


The boolean value `false`


<Feedback>


Great job! Remember, in function overloading, the data type of the argument is crucial in determining which function is called.


</Feedback>


</Answer>


</Question>


</Quiz>


<Ad />


## Overloading Member Functions


Member functions can also be overloaded in the same way.  Let's imagine we have the following situation, where our `Character` objects can equip weapons:


```c++
class Weapon{};

class Character {
 public:
  void Equip(Weapon* Weapon){//<h>
    mWeapon = Weapon;//<h>
  }//<h>

 private:
  Weapon* mWeapon{nullptr};
};

int main(){
  Character Player;
  Weapon WoodenSword;
  Player.Equip(&WoodenSword);//<h>
}
```


We'd like to be able to equip other items too.  Our first instinct to accommodate this might be to rename our existing `Equip()` function to `EquipWeapon()`, and then add new functions called `EquipArmor()`, `EquipShield()`, and so on.


But we don't need to - we can just overload the `Equip()` function, keeping our class friendly to use:


```c++
class Weapon {};

class Shield {};

class Character {
public:
  void Equip(Weapon* Weapon){//<h>
    mWeapon = Weapon;//<h>
  }//<h>

  void Equip(Shield* Shield){//<h>
    mShield = Shield;//<h>
  }//<h>

private:
  Weapon* mWeapon{nullptr};
  Shield* mShield{nullptr};
};

int main(){
  Character Player;
  Weapon WoodenSword;
  Player.Equip(&WoodenSword);//<h>

  Shield WoodenShield;
  Player.Equip(&WoodenShield);//<h>
}
```


## Ambiguous Function Calls


When we're working with overloaded functions, we may see the compiler report errors, claiming our function calls are ambiguous.


In these scenarios, we often need to be more explicit about our data types.


An example of a simple program that falls foul of this rule is below:


```c++
void Func(int Arg){}
void Func(float Arg){}

int main(){
  Func(1.5);//<e>
}
```


```c++
//<o>
'Func': ambiguous call to overloaded function
```


In an earlier note covering the concepts of **literals**, we pointed out that a literal like `1.5` is interpreted as a `double`, rather than a `float`.  Float literals append an `f`, as in `1.5f`.


So far, we have omitted the `f` to make our code easier to read for beginners, and because it generally doesn't matter.  Doubles can be implicitly converted to floats anyway.


However, doubles can be implicitly converted to integers, too, which causes a problem in this context.


Without the `f`, our code is ambiguous.  Should the compiler convert the `double` to an `int` and call `Func(int)`?  Or should it convert it to a `float` and call `Func(float)`?


Rather than guessing our intentions, it asks us to clarify.  In this example, it's quite easy to provide that clarification.  We just update our literal to be either an `int` or a `float`:


```c++
void Func(int Arg){}
void Func(float Arg){}

int main(){
  // Call Func(int)
  Func(1);//<h>

  // Call Func(float)
  Func(1.5f);//<h>
}
```


But it's not always that simple.  What if our argument was stored in a variable, whose type we do not control?


```c++
void Func(int Arg){}
void Func(float Arg){}

// Assume we can't change this
double SomeValue{1.5};

int main(){
  // How do we convert SomeValue to an int or float?
  Func(SomeValue);//<e>
}
```


In the next lesson, we'll see how we can solve problems like this by directly specifying the conversions we want to make.


<Quiz title="Function Overloading">


<Question>


After running the following code, what is the value of `MyBool`?


```c++
bool IsDouble(double Number) { return true; }
bool IsDouble(float Number) { return false; }

bool MyBool { IsDouble(5) };
```


<Answer isCorrect>


This code is invalid


<Feedback>


You got it!  `5` is an `int`.  An `int` can be converted into either a `double` or a `float`.


Because of this, the compiler is unclear on what function it should call.  It throws an error so we can disambiguate our code


If we wanted to use the function that accepted a `double`, we could update our call to this:


```c++
//<qa>
bool MyBool { IsDouble(5.0) };
```


If we wanted to use the function that accepted a `float`, we could update the call to be:


```c++
//<qa>
bool MyBool { IsDouble(5.0f) };
```


</Feedback>


</Answer>


<Answer>


The boolean value `true`


<Feedback>


Reflect on which types an `int` can be converted to, and how this affects function overloading.


</Feedback>


</Answer>


<Answer>


The boolean value `false`


<Feedback>


Think about the data type of the number **`5`** can be converted to, and how the compiler can use that information to select an overloaded function.


</Feedback>


</Answer>


</Question>


</Quiz>


## Summary


In this lesson, we explored several key concepts:

- **Understanding Polymorphism and Overloading**: We started by exploring polymorphism and explaining the main ways we can implement it in C++.
- **Function Overloading with Different Types**: We learned how to overload functions by creating functions with the same name but different parameters
- **Overloading Member Functions**: The concept was further extended to member functions in classes, illustrating a **`Character`** class that can equip different items like weapons and shields.
- **Resolving Ambiguities in Overloaded Functions**: We addressed potential ambiguities that arise with overloaded functions and how to resolve them

<Preview>


### Casting


In our upcoming lesson on casting, we will explore type conversion in more depth.  Here's what you can expect:

- **Introduction to Casting**: We'll start by defining what casting is
- **Static Casting**: We'll explore the different types of casting available in C++, specifically focusing on static casting.
- **C-Style Casting**: We will introduce an older casting syntax, sometimes referred to as C-style casting.
- **Best Practices and Pitfalls**: Finally, we will cover some shortcomings of C-style casting, explaining why we should prefer alternative approaches

</Preview>

Function Overloading

Understanding the Basics

Practical Applications

Common Mistakes

Next Steps

Additional Resources

Assessment Preparation

Intro to C++ Programming