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)

Delete items from an unsorted vector in constant time

Using the uniform erasure functions (or the erase-remove idiom) to delete items from the middle of a vector takes O(n) (linear) time. This is because elements must be shifted from the end of the vector to close the gap of the deleted items. If the order of items in the vector is not important, we can optimize this process to take O(1) (constant) time. Here's how.

How to do it…

This recipe takes advantage of the fact that removing an element from the end of a vector is quick and easy.

  • Let's start by defining a function to print out a vector:
    void printc(auto & r) {
        cout << format("size({}) ", r.size());
        for( auto & e : r ) cout << format("{} ", e);
        cout << '\n';
    }
  • In our main() function we define a vector of int and print it using printc():
    int main() {
       ...