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>


In our previous discussions, we've seen how objects in programming can be thought of as having two main aspects: _**properties**_ and _**behaviors**_.


Properties are like the characteristics or states of an object. We've already learned how to define and use these through variables. For instance, in a game, a character's health or level can be represented as properties using variables like `int Health` or `int Level`.


But what about the actions or behaviors these objects can perform? This is where _**functions**_ come into the picture. Functions are the building blocks that enable our objects to act and interact. They define behaviors by grouping sequences of code to perform specific tasks or actions.


Take the example of a game character again. What kinds of actions might this character need to perform? Perhaps they need to move around, attack enemies, or respond to taking damage. Each of these actions can be encapsulated within a function.


By using functions, we not only organize our code into meaningful blocks but also make it reusable and easier to manage. A well-defined function can be used multiple times, in different contexts, without having to rewrite the same code. This makes our programming more efficient and our code more readable.


In the upcoming sections, we'll learn how to create these functions, how to define their behaviors, and how to invoke them to bring our objects to life.


</Excerpt>


<Ad />


## The `main` Function


You may have realized we're already working with a function in our code - the `main` function:


```c++
int main() {
  // ... code here
}
```


The uniquely named `main` function is the "entry point" to our code.  When we convert our project from code to a runnable application, the compiler looks for a function called `main`.  This is the function that is called when our executable is run.  When the main function ends, our program ends.


However, in our code, we have the freedom to create as many functions as we want.  We're not just limited to the `main` function.


## Creating Functions


Let's start by creating a simple function that modifies some variables.


To create a function, we first need to decide on a name for it. The rules for naming functions are the same as naming variables. Aside from rules like not having any spaces, we can call our functions almost anything.


Just like with variables, we should aim to be descriptive with our function names.


Let's assume we wanted a function to have our monsters take damage.  A good name might simply be `TakeDamage`. We can define a new function above our `main` function like this:


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

void TakeDamage() {

}

int main() {

}
```


Aside from `TakeDamage()` having a different name to our `main` function, we can also see that we have used the `void` prefix rather than `int`.


`void` and `int` refer to the data type that will be _returned_ from the function.  We will discuss return types in more detail a little later in this chapter.


For now, let's just ensure we always have the `int` keyword in our `main` function heading, and `void` in every other function heading we create.


<Ad />


Let's add some variables to our code, and also fill in the _body_ of the `TakeDamage` function. The body is the area between the `{` and `}`.  This is where we make our function perform actions, just like we have with the `main` function in the past.


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

int Health { 150 };//<h>
bool isDead { false };//<h>

void TakeDamage() {
  cout << "Taking Damage";
  Health -= 150;//<h>
  isDead = true;//<h>
}

int main() {

}
```


<Aside>


### White Space and Indenting


Remember, the spacing of our code is not important to the compiler.  When it comes to functions, many people prefer to put the opening `{` on the line after the function name.  That is also valid:


```c++
void TakeDamage()
{
  Health -= 150;
  isDead = true;
}
```


A common pattern that's almost always adopted is _**indenting**_ the code within the body of the function, so it is offset from the left edge.  This has been shown in all our code samples so far.


Like with all white space, this is not important to the compiler, but it makes things easier to read for humans.  Almost all editors will do this indenting for you automatically, as you may have noticed.


This indenting is either done with the spacebar or the tab key - typical choices for indenting are 2 or 4 spaces, or 1 or 2 tabs.


```c++
// Indenting by two spaces
void FunctionA(){
  cout << "Taking Damage";
  Health -= 150;
  isDead = true;
}

// Indenting by four spaces
void FunctionB(){
    cout << "Taking Damage";
    Health -= 150;
    isDead = true;
}
```


You can modify the settings of your editor to specify how big the automated indents should be, and whether they should be done with tabs or spaces.


</Aside>


<Aside>


### Semicolons after Function Definitions


A semicolon after a function definition is **not** needed:


```c++
void SomeFunction(){
  // ...
};//<w>
```


Adding a semicolon here will not change the behavior of the program, but may generate a compiler warning.  The convention is to exclude them:


```c++
void SomeFunction(){
  // ...
}//<h>
```


</Aside>


<Quiz title="Defining Functions">


<Question>


How might we define a function called `LevelUp`?


<Answer isCorrect>
`void LevelUp() {}`
<Feedback>


You got it!


</Feedback>


</Answer>


<Answer>


`function LevelUp {};`


<Feedback>


This syntax doesn't follow C++ conventions. Remember how we structured the `TakeDamage` function and try to apply the same format.


</Feedback>


</Answer>


<Answer>


`def LevelUp:`


<Feedback>


This looks similar to function definition in another programming language. Review the structure of function definitions as shown in the lesson, focusing on the syntax used in C++.


</Feedback>


</Answer>


<Answer>


`LevelUp: {}`


<Feedback>


The format here isn't quite right for defining functions in C++. Think about how we used certain keywords and symbols in our examples.


</Feedback>


</Answer>


</Question>


</Quiz>


<Ad />


## Calling Functions


Just because we have created a function, it doesn't mean the code in that function will ever run.  If we run the previous code (or debug it) we'd see the code in our `TakeDamage` function is never executed.


The only function that we can consider to run automatically is the `main` function.


To execute the code within any other function, we need to **call** that function.  This is sometimes also referred to as **invoking** the function.


To call a function, we use the _**function-call operator**_, which is a set of opening and closing parentheses.  It looks like this:


```c++
TakeDamage();
```


Given that we know the `main` function is going to be run automatically, we can put the code to call our `TakeDamage()` function within the body of the `main` function.  This ensures it is called:


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

int Health { 150 };
bool isDead { false };

void TakeDamage() {
  cout << "Taking Damage";
  Health -= 150;
  isDead = true;
}

int main() {
  TakeDamage();//<h>
}
```


```c++
//<o>
Taking Damage
```


Note, that the `TakeDamage()` function definition must come _**before**_ the `main` function in our code. Were we to switch the order of these functions, putting `main` above `TakeDamage()`, our code would not compile.


The compiler reads our code from top to bottom so, when it sees us trying to call a function that we haven't defined yet, it will fail with an error.


We will soon see techniques that make the order in which we define our functions less important, but for now, let's just order our file such that we're always defining functions before calling them.


<Quiz title="Calling Functions">


<Question>


How might we call a function called `LevelUp`?


<Answer>
It will be called automatically if we define it correctly
<Feedback>


Recall what we discussed about which functions run automatically and which ones don't. Consider how we made the `TakeDamage` function execute.


</Feedback>


</Answer>


<Answer isCorrect>


`LevelUp();`


<Feedback>


Correct!


</Feedback>


</Answer>


<Answer>


`LevelUp;`


<Feedback>


This is close, but something is missing. Look back at how we called the `TakeDamage` function in the lesson for the correct syntax.


</Feedback>


</Answer>


<Answer>


`call LevelUp;`


<Feedback>


This format is not used in C++ for calling functions. Think about the simpler way we used to invoke the `TakeDamage` function.


</Feedback>


</Answer>


</Question>


</Quiz>


## Summary


In this lesson, we've explored the fundamentals of creating and calling functions in C++. Here's a quick recap of what you've learned:

- Functions are blocks of code that perform specific tasks.
- The `main` function serves as the entry point of a C++ program.
- Functions are defined with a return type (for example, `int` or `void`), a name, and a body enclosed in curly braces `{}`.
- We should give our functions descriptive names, and indent their body to keep our code easy to read.
- Functions are invoked using their name followed by parentheses `()`.  The `TakeDamage()` example demonstrated how to call a function within `main`.

<Preview>


### Debugging Functions


In the next lesson, we'll introduce the _**call stack**_, and how it affects our use of the _**debugger.**_  The next lesson will:

- Build on your understanding of functions.
- Introduce how the call stack organizes function calls and how this affects your program's flow.
- Revisit the debugger to learn how to navigate through our function calls and the call stack.

</Preview>

Added note on semicolons after function definitions

Functions

C++ Function (With Examples) - Programiz

Functions in C++ - GeeksforGeeks

C++ Functions - Online Tutorials Library

Functions - Learn C++ - Free Interactive C++ Tutorial

{CPP}Dive into C++ functions - learn how to create and call them in your code. Ideal for beginners seeking a solid foundation in function basics.

Creating and Calling Functions

Understanding the Basics

Practical Applications

Common Mistakes

Next Steps

Additional Resources

Assessment Preparation

Intro to C++ Programming