Error reporting in C++

Name: Error reporting in C++
Rating: 4.5 (15 reviews)

Facilitate robust and expressive error handling with your software design

Created byDimitris Platis

Last updated 2/2024

English

What you'll learn

Understand the importance of error reporting in C++
Analyze the different error reporting techniques
Understand the risks of ambiguity when reporting errors
Evaluate the different error reporting techniques in regards to complexity
Write C++ that is easy to use correctly and hard to get wrong

Coding Exercises

This course includes our updated coding exercises so you can practice your skills as you learn.

Course content

3 sections • 15 lectures • 38m total length

Introduction to the course4:51
Design functions that normally return a value but may fail, choosing safe signatures to prevent misuse. Explore error reporting principles with file-reading examples and [[nodiscard]] in C++17 and beyond.
Introduction to the coding exercises1:41
Develop practical error reporting skills in C++ by completing coding exercises that require modifying run_test function to handle readFile output, check errors, and report results with tester.reportResult.
Sample lab

Exceptions4:44
Explore how exceptions report errors by exiting scopes and unwinding the stack to keep APIs simple and focus on the happy path, with custom exception types and strategic catching.
Exceptions lab
Empty values1:44
Explore reporting errors with empty values by returning an empty or default value on error and the actual value otherwise, noting that this simple approach cannot distinguish errors.
Empty values lab
Invalid values2:46
Explore reporting errors by returning invalid values. Distinguish between different kinds of errors, while noting the risks of using the same type for both contents and errors.
Invalid values lab
Optional values2:37
Learn how std::optional, introduced in C++17, reports errors by returning an empty optional on failure, forcing callers to check for a value before accessing contents.
Optional values lab
Boolean values1:39
Use booleans to report file read success or failure, with true signaling success and false signaling error. They cannot distinguish error types and require content as an out-parameter.
Boolean values lab
Error codes1:39
Explore how error codes—integers in C and C++—report different errors, enable cross-process communication and bitwise operations, and reveal payload handling and protection flaws shown by readFile and switch use.
Error codes lab
Pairs of Booleans and content1:36
Return a boolean and the file contents as a single pair to signal errors and supply the payload as a constant, while noting you cannot distinguish error types.
Pairs of Booleans and content lab
Pairs of error codes and content1:08
Return a pair of an error code and the file contents to report errors, enabling differentiation of error types and access to contents as a constant, while noting potential misuse.
Pairs of error codes and content lab
Custom classes of Booleans and content1:42
Compare a custom class that holds a boolean and file content with the pair approach, using success and content members, and note its expressive benefits and the same drawbacks.
Custom classes of Booleans and content lab
Custom classes of error codes and content0:51
Compare this final alternative to the pair approach by returning a custom class that holds an error code and file contents, offering clearer readability and differentiated errors.
Custom classes of error codes and content lab
Variants3:10
Explore std::variant as a type-safe union that may hold either an error code or file contents. Use std::holds_alternative and std::get to handle errors and access contents safely.
Variant values lab
Expected5:26
explains std::expected, a type that holds two types for error reporting in C++, showing expected and unexpected types, has_value, value, error, and monadic operations to build readable pipelines.
Expected values lab

Requirements

Familiarity with basic C++ syntax
Familiarity with common standard library containers and types (e.g. std::vector, std::string)

Description

Let's explore how to report errors in C++ for software that's both expressive and hard to misuse.

In this course, you will explore various error reporting mechanisms and essential best practices for creating robust and reliable software.
Error reporting is a crucial part of software development. It increases the correctness of software and makes it more maintainable. The goal of error reporting is simple: When returning from a function that may fail, make correct code easy to write and incorrect code hard to miss.

We will look at different ways to report errors in C++ and evaluate each technique based on its simplicity, expressiveness, and robustness. The techniques we will examine range from the most basic, essentially writing C, to the most modern, using C++23 features. The focus will be on functions that return some value, such as the contents of a file, and may fail.
The challenge is finding an ideal way to report an error if one occurs, while also returning the value if everything goes well.

Errors should be unignorable and unambiguous. If a function returns a value, we want to ensure that the caller cannot accidentally access that value if an error has occurred. Additionally, we would like the caller to know what went wrong in case of a mishap. All this, expressively and simply.

We will look at different ways to achieve this, from using exceptions to returning empty or invalid values, error codes, and more. The lectures are code-centric and concise. They are accompanied by interactive labs to help you practice what you have learned. In the coding exercises, you will get some starter code, and your task is to handle the output of a function that may fail. This will allow you to practice all the different error reporting techniques while exploring their advantages and disadvantages.

Join me in this course to learn how to report errors by writing code that's hard to misuse and wrong code hard to get away with.

Who this course is for:

Beginner C++ developers who want to avoid common beginner pitfalls
Intermediate C++ developers who want to architect maintainable modules
C++ developers from all levels who want to get a good grasp of error reporting

Error reporting in C++

What you'll learn

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Coding Exercises

Course content

Introduction2 lectures • 7min