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Modern C++ Programming Cookbook - Third Edition

You're reading from  Modern C++ Programming Cookbook - Third Edition

Product type Book
Published in Feb 2024
Publisher Packt
ISBN-13 9781835080542
Pages 816 pages
Edition 3rd Edition
Languages
Author (1):
Marius Bancila Marius Bancila
Profile icon Marius Bancila

Table of Contents (15) Chapters

Preface 1. Learning Modern Core Language Features 2. Working with Numbers and Strings 3. Exploring Functions 4. Preprocessing and Compilation 5. Standard Library Containers, Algorithms, and Iterators 6. General-Purpose Utilities 7. Working with Files and Streams 8. Leveraging Threading and Concurrency 9. Robustness and Performance 10. Implementing Patterns and Idioms 11. Exploring Testing Frameworks 12. C++ 20 Core Features 13. Other Books You May Enjoy
14. Index

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 can’t store multiple types of a value in a single variable like it is possible to with the type Object in .NET and Java or natively in JavaScript. Developers have long used void* for that purpose, but this only helps us 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...
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