Book Image

C++20 STL Cookbook

By : Bill Weinman
Book Image

C++20 STL Cookbook

By: Bill Weinman

Overview of this book

Fast, efficient, and flexible, the C++ programming language has come a long way and is used in every area of the industry to solve many problems. The latest version C++20 will see programmers change the way they code as it brings a whole array of features enabling the quick deployment of applications. This book will get you up and running with using the STL in the best way possible. Beginning with new language features in C++20, this book will help you understand the language's mechanics and library features and offer insights into how they work. Unlike other books, the C++20 STL Cookbook takes an implementation-specific, problem-solution approach that will help you overcome hurdles quickly. You'll learn core STL concepts, such as containers, algorithms, utility classes, lambda expressions, iterators, and more, while working on real-world recipes. This book is a reference guide for using the C++ STL with its latest capabilities and exploring the cutting-edge features in functional programming and lambda expressions. By the end of the book C++20 book, you'll be able to leverage the latest C++ features and save time and effort while solving tasks elegantly using the STL.
Table of Contents (13 chapters)

Leverage existing algorithms: gather

gather() is an example of an algorithm that leverages existing algorithms.

The gather() algorithm takes a pair of container iterators and moves the elements that satisfy a predicate toward a pivot position within the sequence, returning a pair of iterators that contains the elements that satisfy the predicate.

For example, we could use a gather algorithm to sort all the even numbers to the mid-point of a vector:

vector<int> vint{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
gather(vint.begin(), vint.end(), mid(vint), is_even);
for(const auto& el : vint) cout << el;

Our output is:


Notice that the even numbers are all in the middle of the output.

In this recipe, we will implement a gather algorithm using standard STL algorithms.

How to do it…

Our gather algorithm uses the std::stable_partition() algorithm to move items before the pivot iterator and again to move items past the pivot.

  • We put the...