Book Image

C++17 STL Cookbook

By : Jacek Galowicz
Book Image

C++17 STL Cookbook

By: Jacek Galowicz

Overview of this book

C++ has come a long way and is in use in every area of the industry. Fast, efficient, and flexible, it is used to solve many problems. The upcoming version of C++ will see programmers change the way they code. If you want to grasp the practical usefulness of the C++17 STL in order to write smarter, fully portable code, then this book is for you. Beginning with new language features, this book will help you understand the language’s mechanics and library features, and offers insight into how they work. Unlike other books, ours takes an implementation-specific, problem-solution approach that will help you quickly overcome hurdles. You will learn the core STL concepts, such as containers, algorithms, utility classes, lambda expressions, iterators, and more, while working on practical real-world recipes. These recipes will help you get the most from the STL and show you how to program in a better way. By the end of the book, you will be up to date with the latest C++17 features and save time and effort while solving tasks elegantly using the STL.
Table of Contents (18 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Implementing algorithms in terms of iterators


Iterators usually iterate by moving their position from one item of a container to another. But they do not necessarily need to iterate over data structures at all. Iterators can also be used to implement algorithms, in which case, they would calculate the next value when they are incremented (++it) and return that value when they are dereferenced (*it).

In this section, we demonstrate this by implementing the Fibonacci function in form of an iterator. The Fibonacci function is recursively defined like this: F(n) = F(n - 1) + F(n - 2). It starts with the beginning values of F(0) = 0 and F(1) = 1. This leads to the following number sequence:

  • F(0) = 0
  • F(1) = 1
  • F(2) = F(1) + F(0) = 1
  • F(3) = F(2) + F(1) = 2
  • F(4) = F(3) + F(2) = 3
  • F(5) = F(4) + F(3) = 5
  • F(6) = F(5) + F(4) = 8
  • ... and so on

If we implement this in the form of a callable function that returns the Fibonacci value for any number, n, we will end up with a recursive self-calling function, or a loop...