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::variant as a type-safe union

In C++, a union type is a special class type that, at any point, holds a value of one of its data members. Unlike regular classes, unions cannot have base classes, nor can they be derived, and they cannot contain virtual functions (that would not make sense anyway). Unions are mostly used to define different representations of the same data. However, unions only work for types that are Plain Old Data (POD). If a union contains values of non-POD types, then these members require explicit construction with a placement new and explicit destruction, which is cumbersome and error-prone. In C++17, a type-safe union is available in the form of a standard library class template called std::variant. In this recipe, you will learn how to use it to model alternative values.

Getting ready

The std::variant type implements a type-safe discriminated union. Although discussing these in detail is beyond the scope of this recipe, we will introduce them...