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INTRODUCTION

PART I: Introduction to Professional C++

“The development of C plus plus | C++ started in 1982 by Bjarne Stroustrup, a Danish computer scientist, as the successor of C with Classes. In 1985, the first edition of The C Plus Plus Programming Language book | The C++ Programming Language book was released. The first C plus plus standardized | standardized version of C++ was released in 1998, called C plus plus 98 | C++98. In 2003, C plus plus 03 | C++03 came out and contained a few small updates. After that, it was silent for a while, but traction slowly started building up, resulting in a major update of the language in 2011, called C plus plus 11 | C++11. From then on, the C plus plus Standard Committee | C++ Standard Committee has been on a three-year cycle to release updated versions, giving us C plus plus 14 | C++14, C plus plus 17 | C++17, and now C plus plus 20 | C++20. All in all, with the release of C plus plus 20 | C++20 in 2020, C++ is almost 40 years old and still going strong. In most rankings of programming languages in 2020, C++ is in the top four. It is being used on an extremely wide range of hardware, going from small devices with embedded microprocessors all the way up to multirack supercomputers. Besides wide C plus plus hardware support | hardware support, C++ can be used to tackle almost any programming job, be it C plus plus games | games on C plus plus mobile | mobile platforms, C plus plus performance | performance-critical C plus plus artificial intelligence | artificial intelligence (C plus plus AI | AI) and C plus plus machine learning | machine learning (C plus plus ML | ML) software, C plus plus real-time | real-time 3-D C plus plus graphics | graphics engines, low-level C plus plus hardware drivers | hardware drivers, entire C plus plus operating systems | operating systems, and so on. The performance of C plus plus | performance of C++ programs is hard to match with any other programming language, and as such, it is the de facto language for writing C plus plus fast | fast, C plus plus powerful | powerful, and enterprise-class C plus plus object-oriented | object-oriented programs. As C plus plus popular | popular as C plus plus | C++ has become, the language is surprisingly difficult to grasp in full. There are simple, but powerful, C plus plus techniques | techniques that professional C plus plus programmers | C++ programmers use that don't show up in traditional C plus plus texts | C++ texts, and there are useful parts of C++ that remain a mystery even to experienced C++ programmers.”

“Too often, C plus plus programming books | programming books focus on the C plus plus syntax | syntax of the language instead of its C plus plus real-world use | real-world use. The typical C plus plus text | C++ text introduces a major part of the language in each chapter, explaining the C plus plus syntax | syntax and providing an C plus plus examples | example. Professional C++ does not follow this C plus plus pattern | pattern. Instead of giving you just the C plus plus nuts and bolts | nuts and bolts of the language with little practical context, this book will teach you how to use C plus plus in the real world | C++ in the real world. It will show you the little-known C plus plus features | features that will make your life easier, as well as the C plus plus programming techniques | programming techniques that separate C plus plus novices | novices from C plus plus professional programmers | professional programmers.”

“Even if you have used the language for years, you might still be unfamiliar with the more C plus plus advanced features | advanced features of C++, or you might not be using the full capabilities of the language. Perhaps you write competent C plus plus code | C++ code, but would like to C plus plus learn | learn more about C plus plus design | design and good programming C plus plus style | style in C++. Or maybe you're relatively new to C plus plus | new to C++ but want to learn C plus plus | learn the C Plus Plus Core Guidelines (CG) by Bjarne Stroustrup and Herb Sutter | “right” way to program C++ from the start. This book will meet those needs and bring your C plus plus skills | C++ skills to the professional level.”

“Because this book focuses on advancing from C plus plus basic | basic or C plus plus intermediate | intermediate knowledge of C++ to becoming a C plus plus professional | professional C plus plus programmer | C++ programmer, it assumes that you have some knowledge about programming. Chapter 1, “A C plus plus Crash Course | Crash Course in C++ and the C plus plus Standard Library | Standard Library,” covers the basics of C plus plus | basics of C++ as a C plus plus refresher | refresher, but it is not a substitute for actual C plus plus training | training in programming. If you are just starting with C++ but you have significant experience in another programming language such as C, Java, or C Sharp | C, you should be able to pick up most of what you need from Chapter 1.”

“In any case, you should have a solid C plus plus foundation | foundation in programming fundamentals. You should know about C plus plus loops | loops, C plus plus functions | functions, and C plus plus variables | variables. You should know how to C plus plus program structure | structure a program, and you should be familiar with fundamental techniques such as C plus plus recursion | recursion. You should have some knowledge of common C plus plus data structures | data structures such as C plus plus queues | queues, and useful C plus plus algorithms | algorithms such as C plus plus sorting algorithms | sorting and C plus plus searching algorithms | searching. You don't need to know about C plus plus object-oriented programming | object-oriented programming just yet—that is covered in Chapter 5, “C plus plus Designing with Objects | Designing with Objects.””

“You will also need to be familiar with the C plus plus compiler | compiler you will be using to C plus plus compile | compile your code. Two compilers, Microsoft Visual C Plus Plus compiler | Microsoft Visual C++ compiler and GCC compiler | GCC, are introduced later in this C plus plus introduction | introduction. For other compilers, refer to the C plus plus documentation | documentation that came with your compiler.”

“Professional C++ uses an approach to C plus plus programming | C++ programming that will both increase the C plus plus quality | quality of your code and improve your programming C plus plus efficiency | efficiency. You will find discussions on new C plus plus 20 features | C++20 features throughout this fifth edition. These features are not just isolated to a few chapters or sections; instead, C plus plus examples | examples have been updated to use new features when appropriate.”

“Professional C++ teaches you more than just the C plus plus syntax | syntax and C plus plus language features | language features of C++. It also emphasizes C plus plus programming methodologies | programming methodologies, C plus plus reusable design patterns | reusable design patterns, and good C plus plus programming style | programming style. The Professional C++ C plus plus methodology | methodology incorporates the entire C plus plus software development | software development process, from C plus plus designing | designing and C plus plus writing code | writing code to C plus plus debugging | debugging and working in groups. This approach will enable you to C plus plus master | master the C++ language and its C plus plus idiosyncrasies | idiosyncrasies, as well as take advantage of its C plus plus powerful capabilities | powerful capabilities for C plus plus large-scale | large-scale C plus plus software development | software development.”

“Imagine users who have learned all of the syntax of C++ without seeing a single example of its use. They know just enough to be dangerous! Without examples, they might assume that all code should go in the main() function of the program or that all variables should be global—practices that are generally not considered hallmarks of good programming.”

“Professional C++ programmers understand the correct way to use the language, in addition to the syntax. They recognize the importance of good design, the theories of object-oriented programming, and the best ways to use existing libraries. They have also developed an arsenal of useful code and reusable ideas.”

“By reading and understanding this book, you will become a professional C++ programmer. You will expand your knowledge of C++ to cover lesser known and often misunderstood language features. You will gain an appreciation for object-oriented design and acquire top-notch debugging skills. Perhaps most important, you will finish this book armed with a wealth of reusable ideas that you can actually apply to your daily work.”

“There are many good reasons to make the effort to be a professional C++ programmer as opposed to a programmer who knows C++. Understanding the true workings of the language will improve the quality of your code. Learning about different programming methodologies and processes will help you to work better with your team. Discovering reusable libraries and common design patterns will improve your daily efficiency and help you stop reinventing the wheel. All of these lessons will make you a better programmer and a more valuable employee. While this book can't guarantee you a promotion, it certainly won't hurt.”

This book is made up of five parts.

“Part I, “Introduction to Professional C++,” begins with a crash course in C++ basics to ensure a foundation of C++ knowledge. Following the crash course, Part I goes deeper into working with strings, because strings are used extensively in most examples throughout the book. The last chapter of Part I explores how to write readable C++ code.”

“Part II, “Professional C++ Software Design,” discusses C++ design methodologies. You will read about the importance of design, the object-oriented methodology, and the importance of code reuse.”

“Part III, “C++ Coding the Professional Way,” provides a technical tour of C++ from the professional point of view. You will read about the best ways to manage memory in C++, how to create reusable classes, and how to leverage important language features such as inheritance. You will also learn techniques for input and output, error handling, string localization, how to work with regular expressions, and how to structure your code in reusable components called modules. You will read about how to implement operator overloading, how to write templates, how to put restrictions on template parameters using concepts, and how to unlock the power of lambda expressions and function objects. This part also explains the C++ Standard Library, including containers, iterators, ranges, and algorithms. You will also read about some additional libraries that are available in the standard, such as the libraries to work with time, dates, time zones, random numbers, and the filesystem.”

“Part IV, “Mastering Advanced Features of C++,” demonstrates how you can get the most out of C++. This part of the book exposes the mysteries of C++ and describes how to use some of its more advanced features. You will read about how to customize and extend the C++ Standard Library to your needs, advanced details on template programming, including template metaprogramming, and how to use multithreading to take advantage of multiprocessor and multicore systems.”

“Part V, “C++ Software Engineering,” focuses on writing enterprise-quality software. You'll read about the engineering practices being used by programming organizations today; how to write efficient C++ code; software testing concepts, such as unit testing and regression testing; techniques used to debug C++ programs; how to incorporate design techniques, frameworks, and conceptual object-oriented design patterns into your own code; and solutions for cross-language and cross-platform code.”

“The book concludes with a useful chapter-by-chapter guide to succeeding in a C++ technical interview, an annotated bibliography, a summary of the C++ header files available in the standard, and a brief introduction to the Unified Modeling Language (UML).”

“This book is not a reference of every single class, method, and function available in C++. The book C++17 Standard Library Quick Reference by Peter Van Weert and Marc Gregoire (Apress, 2019. ISBN: 978-1-4842-4923-9) is a condensed reference to all essential data structures, algorithms, and functions provided by the C++ Standard Library up until the C++17 standard. Appendix B lists a couple more references. Two excellent online references are:”

• cppreference.com: You can use this reference online or download an offline version for use when you are not connected to the Internet.

• cplusplus.com/reference

When I refer to a “Standard Library Reference” in this book, I am referring to one of these detailed C++ references.

The following are additional excellent online resources:

• https://github.com/isocpp/CppCoreGuidelines: The CPP CG | C++ Core Guidelines are a collaborative effort led by Bjarne Stroustrup, inventor of the C++ language itself. They are the result of many person-years of discussion and design across a number of organizations. The aim of the guidelines is to help people to use modern C++ effectively. The guidelines are focused on relatively higher-level issues, such as interfaces, resource management, memory management, and concurrency.

• https://github.com/Microsoft/GSL: This is an implementation by Microsoft of the Guidelines Support Library (GSL) containing functions and types that are suggested for use by the C++ Core Guidelines. It's a header-only library.

• isocpp.org/faq: This is a large collection of frequently asked C++ questions.

• stackoverflow.com: Search for answers to common programming questions, or ask your own questions.

All you need to use this book is a computer with a C++ compiler. This book focuses only on parts of C++ that have been standardized, and not on vendor-specific compiler extensions.

• Any C++ Compiler

You can use whichever C++ compiler you like. If you don't have a C++ compiler yet, you can download one for free. There are a lot of choices. For example, for Windows, you can download Microsoft Visual Studio Community Edition, which is free and includes Visual C++. For Linux, you can use GCC or Clang, which are also free.

The following two sections briefly explain how to use Visual C++ and GCC. Refer to the documentation that came with your compiler for more details.

This book discusses new features introduced with the C++20 standard. At the time of this writing, no compilers were fully C++20 compliant yet. Some new features were only supported by some compilers and not others, while other features were not yet supported by any compiler. Compiler vendors are hard at work to catch up with all new features, and I'm sure it won't take long before there will be fully C++20-compliant compilers available. You can keep track of which compiler supports which features at en.cppreference.com/w/cpp/compiler_support.

At the time of this writing, there was no compiler available yet that fully supported C++20 modules. There was experimental support in some of the compilers, but it was still incomplete. This book uses modules everywhere. We did our best to make sure all sample code would compile once compilers fully support modules, but since we were not able to compile and test all examples, some errors might have crept in. When you use a compiler with support for modules and you encounter problems with any of the code samples, double-check the list of errata for the book at www.wiley.com/go/proc++5e to see if it's a known issue. If your compiler does not yet support modules, you can convert modularized code to non-modularized code, as explained briefly in Chapter 11, “Odds and Ends.”

Example: Microsoft Visual C++ 2019

First, you need to create a project. Start Visual C++ 2019, and on the welcome screen, click the Create A New Project button. If the welcome screen is not shown, select File ➪ New ➪ Project. In the Create A New Project dialog, search for the Console App project template with tags C++, Windows, and Console, and click Next. Specify a name for the project and a location where to save it, and click Create.

Once your new project is loaded, you can see a list of project files in the Solution Explorer. If this docking window is not visible, select View ➪ Solution Explorer. A newly created project will contain a file called <projectname>.cpp. You can start writing your C++ code in that .cpp file, or if you want to compile source code files from the downloadable source archive for this book, select the <projectname>.cpp file in the Solution Explorer and delete it. You can add new files or existing files to a project by right-clicking the project name in the Solution Explorer and then selecting Add ➪ New Item or Add ➪ Existing Item.

At the time of this writing, Visual C++ 2019 did not yet automatically enable C++20 features. To enable C++20 features, in the Solution Explorer window, right-click your project and click Properties. In the Properties window, go to Configuration Properties ➪ C/C++ ➪ Language, and set the C++ Language Standard option to ISO C++20 Standard or Preview - Features from the Latest C++ Working Draft, whichever is available in your version of Visual C++. These options are accessible only if your project contains at least one .cpp file.

Finally, select Build ➪ Build Solution to compile your code. When it compiles without errors, you can run it with Debug ➪ Start Debugging.

Module Support At the time of this writing, Visual C++ 2019 did not yet have full support for modules. Authoring and consuming your own modules usually works just fine, but importing Standard Library headers such as the following did not yet work out of the box:

import <iostream>; To make such import declarations work, for the time being you need to add a separate header file to your project, for example called HeaderUnits.h, which contains an import declaration for every Standard Library header you want to import. Here's an example:

// HeaderUnits.h

1. pragma once

import <iostream>; import <vector>; import <optional>; import <utility>; // …

Next, right-click the HeaderUnits.h file in the Solution Explorer and click Properties. In Configuration Properties ➪ General, set Item Type to C/C++ Compiler and click Apply. Next, in Configuration Properties ➪ C/C++ ➪ Advanced, set Compile As to Compile as C++ Header Unit (/exportHeader) and click OK.

When you now recompile your project, all import declarations that have a corresponding import declaration in your HeaderUnits.h file should compile fine.

If you are using module implementation partitions (see Chapter 11), also known as internal partitions, then right-click all files containing such implementation partitions, click Properties, go to Configuration Properties ➪ C/C++ ➪ Advanced, and set the Compile As option to Compile as C++ Module Internal Partition (/internalPartition) and click OK.

Example: GCC Create your source code files with any text editor you prefer and save them to a directory. To compile your code, open a terminal and run the following command, specifying all your .cpp files that you want to compile:

g++ -std=c++2a -o <executable_name> <source1.cpp> [source2.cpp …] The -std=c++2a option is required to tell GCC to enable C++20 support. This option will change to -std=C++20 once GCC is fully C++20 compliant.

At the time of this writing, GCC only had experimental support for modules through a special version of GCC (branch devel/c++-modules). When you are using such a version of GCC, module support is enabled with the -fmodules-ts option, which might change to -fmodules in the future.

Unfortunately, import declarations of Standard Library headers such as the following were not yet properly supported:

import <iostream>; If that's the case, simply replace such import declarations with corresponding #include directives:

1. include <iostream>

For example, the AirlineTicket example from Chapter 1 uses modules. After having replaced the imports for Standard Library headers with #include directives, you can compile the AirlineTicket example by changing to the directory containing the code and running the following command:

g++ -std=c++2a -fmodules-ts -o AirlineTicket AirlineTicket.cppm AirlineTicket.cpp AirlineTicketTest.cpp When it compiles without errors, you can run it as follows:

./AirlineTicket std::format Support Many code samples in this book use std::format(), introduced in Chapter 1. At the time of this writing, there was no compiler yet that had support for std::format(). However, as long as your compiler doesn't support std::format() yet, you can use the freely available {fmt} library as a drop-in replacement:

Download the latest version of the {fmt} library from https://fmt.dev/ and extract the code on your machine. Copy the include/fmt and src directories to fmt and src subdirectories in your project directory, and then add fmt/core.h, fmt/format.h, fmt/format-inl.h, and src/format.cc to your project. Add a file called format (no extension) to the root directory of your project and add the following code to it:

1. pragma once
2. define FMT_HEADER_ONLY
3. include “fmt/format.h”

namespace std {

   using fmt::format;
   using fmt::format_error;
   using fmt::formatter;

Finally, add your project root directory (the directory containing the format file) as an additional include directory for your project. For example, in Visual C++, right click your project in the Solution Explorer, click Properties, go to Configuration Properties ➪ C/C++ ➪ General, and add $(ProjectDir); to the front of the Additional Include Directories option.“

NOTE Don't forget to undo these steps once your compiler supports the standard std::format().”

Companion Download Files: https://www.wiley.com/go/proc++5e.