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)

Initialize threads with std::call_once

You may need to run the same code in many threads but must initialize that code only once.

One solution would be to call the initialization code before running the threads. This approach can work but has some drawbacks. By separating the initialization, it may be called when unnecessary, or it may be missed when necessary.

The std::call_once function provides a more robust solution. call_once is in the <mutex> header.

How to do it…

In this recipe, we use a print function for the initialization, so we can clearly see when it's called:

  • We'll use a constant for the number of threads to spawn:
    constexpr size_t max_threads{ 25 };

We also need a std::once_flag to synchronize the std::call_once function:

std::once_flag init_flag;
  • Our initialization function simply prints a string to let us know it's been called:
    void do_init(size_t id) {
        cout << format(&quot...