Book Image

Modern C++ Programming Cookbook - Second Edition

By : Marius Bancila
Book Image

Modern C++ Programming Cookbook - Second Edition

By: Marius Bancila

Overview of this book

C++ has come a long way to be one of the most widely used general-purpose languages that is fast, efficient, and high-performance at its core. The updated second edition of Modern C++ Programming Cookbook addresses the latest features of C++20, such as modules, concepts, coroutines, and the many additions to the standard library, including ranges and text formatting. The book is organized in the form of practical recipes covering a wide range of problems faced by modern developers. The book also delves into the details of all the core concepts in 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. It goes into the performance aspects of programming in depth, teaching developers how to write fast and lean code with the help of best practices. Furthermore, the book explores useful patterns and delves into the implementation of many idioms, including pimpl, named parameter, and attorney-client, teaching techniques such as avoiding repetition with the factory pattern. There is also a chapter dedicated to unit testing, where you are introduced to three of the most widely used libraries for C++: Boost.Test, Google Test, and Catch2. By the end of the book, you will be able to effectively leverage the features and techniques of C++11/14/17/20 programming to enhance the performance, scalability, and efficiency of your applications.
Table of Contents (16 chapters)
13
Bibliography
14
Other Books You May Enjoy
15
Index

Creating immediate functions

Constexpr functions enable the evaluation of functions at compile time, provided that all their inputs, if any, are also available at compile time. However, this is not a guarantee and constexpr functions may also execute at runtime, as we have seen in the previous recipe, Creating compile-time constant expressions. In C++20, a new category of functions has been introduced: immediate functions. These are functions that are guaranteed to always be evaluated at compile time; otherwise, they produce errors. Immediate functions are useful as replacements for macros and may be important in the possible future development of the language with reflection and meta-classes.

How to do it…

Use the consteval keyword when you want to:

  • Define non-member functions or function templates that must be evaluated at compile time:
    consteval unsigned int factorial(unsigned int const n)
    {
      return n > 1 ? n * factorial(n-1) : 1;
    }
    
    ...