Book Image

Modern C++ Programming Cookbook

By : Marius Bancila
Book Image

Modern C++ Programming Cookbook

By: Marius Bancila

Overview of this book

C++ is one of the most widely used programming languages. Fast, efficient, and flexible, it is used to solve many problems. The latest versions of C++ have seen programmers change the way they code, giving up on the old-fashioned C-style programming and adopting modern C++ instead. Beginning with the modern language features, each recipe addresses a specific problem, with a discussion that explains the solution and offers insight into how it works. You will learn major concepts about the core programming language as well as common tasks faced while building a wide variety of software. You will learn about concepts such as concurrency, performance, meta-programming, lambda expressions, regular expressions, testing, and many more in the form of recipes. These recipes will ensure you can make your applications robust and fast. By the end of the book, you will understand the newer aspects of C++11/14/17 and will be able to overcome tasks that are time-consuming or would break your stride while developing.
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Using std::any to store any value


C++ does not have a hierarchical type system like other languages (such as C# or Java) and, therefore, it does not have a possibility to store multiple types of value in a single variable like it is possible with type Object in .NET and Java or natively in JavaScript. Developers have long time used void* for that purpose, but this only helps store pointers to anything and is not type-safe. Depending on the end goal, alternatives can include templates or overloaded functions. However, C++17 has introduced a standard type-safe container, called std::any, that can hold a single value of any type.

Getting ready

std::any has been designed based on boost::any and is available in the <any> header. If you are familiar with boost::any and have used it in your code, you can migrate it seamlessly to std::any.

How to do it...

Use the following operations to work with std::any:

  • To store values, use the constructor or assign them directly to a std::any variable:
    ...