C++ is a general-purpose programming language that combines different paradigms such as object-oriented, imperative, generic, and functional programming. C++ is designed for efficiency and is the primary choice in applications where performance is key. Over the last few decades, C++ has been one of the most widely used programming languages in industry, academia, and elsewhere. The language is standardized by the International Organization for Standardization (ISO), which is currently working on the next version of the standard, called C++20, due to be completed in 2020.
With the standard covering almost 1500 pages, C++ is not the simplest language to learn and master. Skills are not acquired only by reading about them or watching others exercising them, but by practicing them again and again. Programming is no different; we developers do not learn new languages or technologies just by reading books, articles, or watching video tutorials. Instead, we need practice to sediment and develop the new things we learn so that we can eventually master them. Many a times, however, finding good exercises to put our knowledge to test is a difficult task. Although there are many websites that feature problems for different programming languages, most of these are mathematical problems, algorithms, or problems for student competitions. These kinds of problems do not help you exercise a large variety of a programming language functionalities. That is where this book steps in.
This book is a collection of 100 real-world problems designed for you to practice a large variety of the C++ language and standard library features as well as many third-party, cross-platform libraries. Yet, a few of these problems are C++ specific and, in general, can be solved in many programming languages. Of course, the intention is to help you master C++ and therefore you are expected to solve them in C++. All the solutions provided in the book are in C++. However, you can use the book as a reference for its collection of proposed problems when you learn other programming languages, although in this case, you will not benefit from the solutions.
The problems in this book are grouped into 12 chapters. Each chapter contains problems on similar or related topics. The problems have different levels of difficulty; some of them are easy, some are moderate, and some are difficult. The book has a relatively equal number of problems for each difficulty level. Each chapter starts with the description of the proposed problems. The solutions to these problems ensue with recommendations, explanations, and source code. Although you can find the solutions in the book, it is recommended that you try to implement them by yourself first, and only afterward—or if you have difficulties completing them—look at the proposed solutions. There is only one thing that is missing in the source code presented in the book—the headers you have to include. This was left out on purpose so that you figure those out by yourself. On the other hand, the source code provided with the book is complete, and you can find all the required headers there.
At the time of writing this book, the C++20 version of the standard is in progress and will continue for the next couple of years. However, some features have already been voted in, and one of these features is the extension to the chrono library with calendars and time zones. There are several problems in the fifth chapter on this topic, and although no compiler supports these yet, you can solve them using the date library, based on which the new standard additions have been designed. Many other libraries are used for solving problems in the book. The list includes Asio, Crypto++, Curl, NLohmann/json, PDF-Writer, PNGWriter, pugixml, SQLite, and ZipLib. Also, as an alternative to the std::optional and the filesystem libraries used throughout the book, you can use Boost with compilers where these are not available. All these libraries are open source and cross-platform. They were chosen for reasons that include performance, good documentation, and wide use within the community. However, you are free to use any other libraries you would like to solve the problems.
