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 transform_if using std::accumulate and lambdas


Most developers who have used std::copy_if and std::transform may have asked themselves already, why there is no std::transform_if. The std::copy_if function copies items from a source range to a destination range, but skips the items that are not selected by a user-defined predicate function. The std::transform unconditionally copies all items from a source range to a destination range but transforms them in between. The transformation is provided by a user-defined function, which might do simple things, such as multiplying numbers or transforming items to completely different types.

Such functions have been there for a long time now, but there is still no std::transform_if function. In this section, we are going to implement this function. It would be easy to do this by just implementing a function that iterates over the ranges while copying all the items that are selected by a predicate function and transforming them in between...