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C++ Fundamentals

You're reading from   C++ Fundamentals Hit the ground running with C++, the language that supports tech giants globally

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Product type Paperback
Published in Mar 2019
Publisher
ISBN-13 9781789801491
Length 350 pages
Edition 1st Edition
Languages
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Authors (2):
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Antonio Mallia Antonio Mallia
Author Profile Icon Antonio Mallia
Antonio Mallia
Francesco Zoffoli Francesco Zoffoli
Author Profile Icon Francesco Zoffoli
Francesco Zoffoli
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Table of Contents (9) Chapters Close

C++ Fundamentals
Preface
1. Getting Started FREE CHAPTER 2. Functions 3. Classes 4. Generic Programming and Templates 5. Standard Library Containers and Algorithms 6. Object-Oriented Programming 7. Appendix

std::optional


optional<T> is a that's used to contain a value that might be present or not.

The class takes a template parameter, T, which represents the type that the std::optional template class might contain. Value type means that the instance of the class contains the value. Copying optional will create a new copy of the contained data.

At any point in the execution of the program, optional<T> either contains nothing, when it's empty, or contains a value of type T.

Optional is defined in the <optional> header.

Let's imagine our application is using a class named User for managing registered users. We would like to have a function that gets us the information of a user from their email: User getUserByEmail(Email email);.

But what happens when a user is not registered? That is, when we can determine that our system does not have the associated User instance?

Some would suggest throwing an exception. In C++, exceptions are used for exceptional situations, ones that should almost...

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