Book Image

Modern C++ Programming Cookbook - Third Edition

By : Marius Bancila
Book Image

Modern C++ Programming Cookbook - Third Edition

By: Marius Bancila

Overview of this book

The updated third edition of Modern C++ Programming Cookbook addresses the latest features of C++23, such as the stack library, the expected and mdspan types, span buffers, formatting library improvements, and updates to the ranges library. It also gets into more C++20 topics not previously covered, such as sync output streams and source_location. The book is organized in the form of practical recipes covering a wide range of real-world problems. It gets into the details of all the core concepts of modern C++ programming, such as functions and classes, iterators and algorithms, streams and the file system, threading and concurrency, smart pointers and move semantics, and many others. You will cover the performance aspects of programming in depth, and learning to write fast and lean code with the help of best practices. You will explore useful patterns and the implementation of many idioms, including pimpl, named parameter, attorney-client, and the factory pattern. A chapter dedicated to unit testing introduces you to three of the most widely used libraries for C++: Boost.Test, Google Test, and Catch2. By the end of this modern C++ programming book, you will be able to effectively leverage the features and techniques of C++11/14/17/20/23 programming to enhance the performance, scalability, and efficiency of your applications.
Table of Contents (15 chapters)
13
Other Books You May Enjoy
14
Index

Using std::expected to return a value or an error

We often need to write a function that returns both some data and an indication of success or failure (either as a bool for the simplest case or an error code for more complex cases). Typically, this can be solved either by returning a status code and using a parameter passed by reference for returning the data or by returning the actual data but throwing exceptions in the case of failure. In recent times, the availability of std::optional and std::variant gave way to new solutions for this problem. However, the C++23 standard provides a new approach with the std::expected type, a sort of combination of the two types previously mentioned. Such a type is present in other programming languages, such as Result in Rust and Either in Haskell. In this recipe, we will learn how to use this new std::expected class.

Getting ready

In the examples shown in this recipe, we will use the data types defined here:

enum class Status
{
...