Modern C++ for Absolute Beginners.pdf

Modern C++ for Absolute Beginners A Friendly Introduction to C++ Programming Language and C++11 to C++20 Standards — Slobodan Dmitrović  Modern C++ for Absolute Beginners A Friendly Introduction to C++ Programming Language and C++11 to C++20 Standards Slobodan...

Modern C++ for Absolute Beginners A Friendly Introduction to C++ Programming Language and C++11 to C++20 Standards — Slobodan Dmitrović  Modern C++ for Absolute Beginners A Friendly Introduction to C++ Programming Language and C++11 to C++20 Standards Slobodan Dmitrović Modern C++ for Absolute Beginners: A Friendly Introduction to C++ Programming Language and C++11 to C++20 Standards Slobodan Dmitrović Belgrade, Serbia ISBN-13 (pbk): 978-1-4842-6046-3 ISBN-13 (electronic): 978-1-4842-6047-0 https://doi.org/10.1007/978-1-4842-6047-0 Copyright © 2020 by Slobodan Dmitrović This work is subject to copyright. 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For information on translations, please e-mail [email protected]; for reprint, paperback, or audio rights, please email [email protected]. Apress titles may be purchased in bulk for academic, corporate, or promotional use. eBook versions and licenses are also available for most titles. For more information, reference our Print and eBook Bulk Sales web page at http://www.apress.com/bulk-sales. Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the book’s product page, located at www.apress.com/9781484260463. For more detailed information, please visit http://www.apress.com/source-code. Printed on acid-free paper To M. R., whose work is an inspiration to me. Table of Contents About the Author xv About the Technical Reviewer xvii Acknowledgments xix Chapter 1: Introduction 1 Chapter 2: What is C++? 3 2.1 C++ Standards 3 Chapter 3: C++ Compilers 5 3.1 Installing C++ Compilers 5 3.1.1 On Linux 5 3.1.2 On Windows 6 Chapter 4: Our First Program 7 4.1 Comments 8 4.2 Hello World Example 8 Chapter 5: Types 11 5.1 Fundamental Types 11 5.1.1 Boolean 11 5.1.2 Character Type 12 5.1.3 Integer Types 14 5.1.4 Floating-Point Types 15 5.1.5 Type void 16 5.2 Type Modifiers 16 5.3 Variable Declaration, Definition, and Initialization 17 v Table of Contents Chapter 6: Exercises 19 6.1 Hello World and Comments 19 6.2 Declaration 19 6.3 Definition 20 6.4 Initialization 20 Chapter 7: Operators 21 7.1 Assignment Operator 21 7.2 Arithmetic Operators 21 7.3 Compound Assignment Operators 23 7.4 Increment/Decrement Operators 24 Chapter 8: Standard Input 25 Chapter 9: Exercises 27 9.1 Standard Input 27 9.2 Two Inputs 27 9.3 Multiple Inputs 28 9.4 Inputs and Arithmetic Operations 28 9.5 Post-Increment and Compound Assignment 29 9.6 Integral and Floating-point Division 29 Chapter 10: Arrays 31 Chapter 11: Pointers 33 Chapter 12: References 37 Chapter 13: Introduction to Strings 39 13.1 Defining a String 39 13.2 Concatenating Strings 40 13.3 Accessing Characters 41 13.4 Comparing Strings 41 13.5 String Input 42 vi  Table of Contents 13.6 A Pointer to a String 43 13.7 Substrings 43 13.8 Finding a Substring 44 Chapter 14: Automatic Type Deduction 47 Chapter 15: Exercises 49 15.1 Array Definition 49 15.2 Pointer to an Object 49 15.3 Reference Type 50 15.4 Strings 50 15.5 Strings from Standard Input 51 15.6 Creating a Substring 51 15.7 Finding a single Character 52 15.8 Finding a Substring 52 15.9 Automatic Type Deduction 53 Chapter 16: Statements 55 16.1 Selection Statements 55 16.1.1 if Statement 55 16.1.2 Conditional Expression 57 16.1.3 The Logical Operators 58 16.1.4 switch Statement 63 16.2 Iteration Statements 64 16.2.1 for Statement 64 16.2.2 while Statement 65 16.2.3 do Statement 66 Chapter 17: Constants 67 Chapter 18: Exercises 69 18.1 A Simple if-statement 69 18.2 Logical Operators 69 18.3 The switch-statement 70 vii Table of Contents 18.4 The for-loop 71 18.5 Array and the for-loop 72 18.6 The const Type Qualifier 72 Chapter 19: Functions 75 19.1 Introduction 75 19.2 Function Declaration 75 19.3 Function Definition 76 19.4 Return Statement 79 19.5 Passing Arguments 80 19.5.1 Passing by Value/Copy 80 19.5.2 Passing by Reference 81 19.5.3 Passing by Const Reference 82 19.6 Function Overloading 83 Chapter 20: Exercises 85 20.1 Function Definition 85 20.2 Separate Declaration and Definition 85 20.3 Function Parameters 86 20.4 Passing Arguments 87 20.5 Function Overloads 87 Chapter 21: Scope and Lifetime 89 21.1 Local Scope 89 21.2 Block Scope 89 21.3 Lifetime 90 21.4 Automatic Storage Duration 90 21.5 Dynamic Storage Duration 90 21.6 Static Storage Duration 91 21.7 Operators new and delete 91 viii  Table of Contents Chapter 22: Exercises 93 22.1 Automatic Storage Duration 93 22.2 Dynamic Storage Duration 93 22.3 Automatic and Dynamic Storage Durations 94 Chapter 23: Classes - Introduction 95 23.1 Data Member Fields 96 23.2 Member Functions 96 23.3 Access Specifiers 99 23.4 Constructors 102 23.4.1 Default Constructor 102 23.4.2 Member Initialization 104 23.4.3 Copy Constructor 104 23.4.4 Copy Assignment 107 23.4.5 Move Constructor 109 23.4.6 Move Assignment 111 23.5 Operator Overloading 112 23.6 Destructors 118 Chapter 24: Exercises 121 24.1 Class Instance 121 24.2 Class with Data Members 121 24.3 Class with Member Function 122 24.4 Class with Data and Function Members 122 24.5 Class Access Specifiers 123 24.6 User-defined Default Constructor and Destructor 124 24.7 Constructor Initializer List 125 24.8 User-defined Copy Constructor 126 24.9 User-defined Move Constructor 127 24.10 Overloading Arithmetic Operators 128 ix Table of Contents Chapter 25: Classes – Inheritance and Polymorphism 131 25.1 Inheritance 131 25.2 Polymorphism 135 Chapter 26: Exercises 141 26.1 Inheritance 141 Chapter 27: The static Specifier 145 Chapter 28: Templates 149 Chapter 29: Enumerations 155 Chapter 30: Exercises 159 30.1 Static variable 159 30.2 Static data member 160 30.3 Static member function 160 30.4 Function Template 161 30.5 Class Template 162 30.6 Scoped Enums 163 30.7 Enums in a switch 164 Chapter 31: Organizing code 165 31.1 Header and Source Files 165 31.2 Header Guards 166 31.3 Namespaces 166 Chapter 32: Exercises 171 32.1 Header and Source Files 171 32.2 Multiple Source Files 172 32.3 Namespaces 173 32.4 Nested Namespaces 174 x  Table of Contents Chapter 33: Conversions 175 33.1 Implicit Conversions 175 33.2 Explicit Conversions 178 Chapter 34: Exceptions 183 Chapter 35: Smart Pointers 189 35.1 Unique Pointer 189 35.2 Shared Pointer 191 Chapter 36: Exercises 193 36.1 static_cast Conversion 193 36.2 A Simple Unique Pointer: 194 36.3 Unique Pointer to an Object of a Class 194 36.4 Shared Pointers Exercise 195 36.5 Simple Polymorphism 195 36.6 Polymorphism II 196 36.7 Exception Handling 198 36.8 Multiple Exceptions 198 Chapter 37: Input/Output Streams 201 37.1 File Streams 201 37.2 String Streams 204 Chapter 38: C++ Standard Library and Friends 209 38.1 Containers 209 38.1.1 std::vector 210 38.1.2 std::array 212 38.1.3 std::set 212 38.1.4 std::map 213 38.1.5 std::pair 216 38.1.6 Other Containers 217 38.2 The Range-Based for Loop 217 38.3 Iterators 219 xi Table of Contents 38.4 Algorithms and Utilities 220 38.4.1 std::sort 221 38.4.2 std::find 222 38.4.3 std::copy 224 38.4.4 Min and Max Elements 225 38.5 Lambda Expressions 226 Chapter 39: Exercises 233 39.1 Basic Vector 233 39.2 Deleting a Single Value 233 39.3 Deleting a Range of Elements 234 39.4 Finding Elements in a Vector 235 39.5 Basic Set 236 39.6 Set Data Manipulation 236 39.7 Set Member Functions 237 39.8 Search for Data in a Set 237 39.9 Basic Map 238 39.10 Inserting Into Map 239 39.11 Searching and Deleting From a Map 240 39.12 Lambda Expressions 241 Chapter 40: C++ Standards 243 40.1 C++11 243 40.1.1 Automatic Type Deduction 244 40.1.2 Range-based Loops 244 40.1.3 Initializer Lists 245 40.1.4 Move Semantics 245 40.1.5 Lambda Expressions 246 40.1.6 The constexpr Specifier 247 40.1.7 Scoped Enumerators 247 40.1.8 Smart Pointers 248 40.1.9 std::unordered_set 249 xii  Table of Contents 40.1.10 std::unordered_map 250 40.1.11 std::tuple 252 40.1.12 static_assert 253 40.1.13 Introduction to Concurrency 254 40.1.14 Deleted and Defaulted Functions 259 40.1.15 Type Aliases 262 40.2 C++14 262 40.2.1 Binary Literals 263 40.2.2 Digits Separators 264 40.2.3 Auto for Functions 264 40.2.4 Generic Lambdas 265 40.2.5 std::make_unique 265 40.3 C++17 266 40.3.1 Nested Namespaces 266 40.3.2 Constexpr Lambdas 267 40.3.3 Structured Bindings 267 40.3.4 std::filesystem 269 40.3.5 std::string_view 272 40.3.6 std::any 273 40.3.7 std::variant 275 40.4 C++20 278 40.4.1 Modules 278 40.4.2 Concepts 281 40.4.3 Lambda Templates 285 40.4.4 [likely] and [unlikely] Attributes 286 40.4.5 Ranges 287 40.4.6 Coroutines 291 40.4.7 std::span 291 40.4.8 Mathematical Constants 292 xiii Table of Contents Summary and Advice 295 The go-to Reference 295 StackOverflow 295 Other Online Resources 296 Other C++ Books 296 Advice 296 Index 297 xiv About the Author Slobodan Dmitrović is a software development consultant and an author from Serbia. He specializes in C++ training, technical analysis, and software architecture. He is a highly visible member of the SE European C++ community and a StackOverflow contributor. Slobodan has gained international experience working as a software consultant in Denmark, Poland, Croatia, China, and the Philippines. Slobodan maintains a website at www.cppandfriends.com. xv About the Technical Reviewer Chinmaya Patnayak is an embedded software developer at NVIDIA and is skilled in C++, CUDA, deep learning, Linux, and file systems. He has been a speaker and instructor for deep learning at various major technology events across India. Chinmaya holds an M.Sc. degree in physics and B.E. in electrical and electronics engineering from BITS Pilani. He has previously worked with Defence Research and Development Organization (DRDO) on encryption algorithms for video streams. His current interest lies in neural networks for image segmentation and applications in biomedical research and self-driving cars. Find more about him at ­chinmayapatnayak.github.io. xvii Acknowledgments I would like to thank my friends and fellow C++ peers who have supported me in writing this book. I owe my gratitude to outstanding professionals at Apress for their amazing work and support during the entire writing and production process. I am thankful to the StackOverflow and the entire C++ community for their help and feedback. My deepest appreciation goes to S. Antonijević, Jovo Arežina, and Saša Popović for their ongoing support. xix CHAPTER 1 Introduction Dear Reader, Congratulations on choosing to learn the C++ programming language, and thank you for picking up this book. My name is Slobodan Dmitrović, I am a software developer and a technical writer, and I will try to introduce you to a beautiful world of C++ to the best of my abilities. This book is an effort to introduce the reader to a C++ programming language in a structured, straightforward, and friendly manner. We will use the “just enough theory and plenty of examples” approach whenever possible. To me, C++ is a wonderful product of the human intellect. Over the years, I have certainly come to think of it as a thing of beauty and elegance. C++ is a language like no other, surprising in its complexity, yet wonderfully sleek and elegant in so many ways. It is also a language that cannot be learned by guessing, one that is easy to get wrong and challenging to get right. In this book, we will get familiar with the language basics first. Then, we will move onto standard-library. Once we got these covered, we will describe the modern C++ standards in more detail. After each section, there are source code exercises to help us adopt the learned material more efficiently. Let us get started! 1 © Slobodan Dmitrović 2020 S. Dmitrović, Modern C++ for Absolute Beginners, https://doi.org/10.1007/978-1-4842-6047-0_1 CHAPTER 2 What is C++? C++ is a programming language. A standardized, general-purpose, object-oriented, compiled language. C++ is accompanied by a set of functions and containers called the C++ Standard-Library. Bjarne Stroustrup created C++ as an extension to a C programming language. Still, C++ evolved to be a completely different programming language. Let us emphasize this: C and C++ are two different languages. C++ started as “C with classes,” but it is now a completely different language. So, C++ is not C; C++ is not C with classes; it is just C++. And there is no such thing as a C/C++ programming language. C++ is widely used for the so-called systems programming as well as application programming. C++ is a language that allows us to get down to the metal where we can perform low-level routines if needed, or soar high with abstraction mechanisms such as templates and classes. 2.1 C++ Standards C++ is governed by the ISO C++ standard. There are multiple ISO C++ standards listed here in chronological order: C++03, C++11, C++14, C++17, and the upcoming C++20 standard. Every C++ standard starting with the C++11 onwards is referred to as “Modern C++.” And modern C++ is what we will be teaching in this book. 3 © Slobodan Dmitrović 2020 S. Dmitrović, Modern C++ for Absolute Beginners, https://doi.org/10.1007/978-1-4842-6047-0_2 CHAPTER 3 C++ Compilers C++ programs are usually a collection of C++ code spread across one or multiple source files. The C++ compiler compiles these files and turns them into object files. Object files are linked together by a linker to create an executable file or a library. At the time of the writing, some of the more popular C++ compilers are: –– The g++ frontend (as part of the GCC) –– Visual C++ (as part of the Visual Studio IDE) –– Clang (as part of the LLVM) 3.1 Installing C++ Compilers The following sections explain how to install C++ compilers on Linux and Windows and how to compile and run our C++ programs. 3.1.1 On Linux To install a C++ compiler on Linux, type the following inside the terminal: sudo apt-get install build-essential To compile the C++ source file source.cpp, we type: g++ source.cpp This command will produce an executable with the default name of a.out. To run the executable file, type:./a.out 5 © Slobodan Dmitrović 2020 S. Dmitrović, Modern C++ for Absolute Beginners, https://doi.org/10.1007/978-1-4842-6047-0_3 Chapter 3 C++ Compilers To compile for a C++11 standard, we add the -std=c++11 flag: g++ -std=c++11 source.cpp To enable warnings, we add the -Wall flag: g++ -std=c++11 -Wall source.cpp To produce a custom executable name, we add the -o flag followed by an executable name: g++ -std=c++11 -Wall source.cpp -o myexe The same rules apply to the Clang compiler. Substitute g++ with clang++. 3.1.2 On Windows On Windows, we can install a free copy of Visual Studio. Choose Create a new project, make sure the C++ language option is selected, and choose - Empty Project – click Next and click Create. Go to the Solution Explorer panel, right-click on the project name, choose Add – New Item – C++ File (.cpp), type the name of a file (source.cpp), and click Add. Press F5 to run the program. We can also do the following: choose Create a new project, make sure the C++ language option is selected, and choose – Console App – click Next and click Create. If a Create a new project button is not visible, choose File – New – Project and repeat the remaining steps. 6 CHAPTER 4 Our First Program Let us create a blank text file using the text editor or C++ IDE of our choice and name it source.cpp. First, let us create an empty C++ program that does nothing. The content of the source.cpp file is: int main(){} The function main is the main program entry point, the start of our program. When we run our executable, the code inside the main function body gets executed. A function is of type int (and returns a result to the system, but let us not worry about that just yet). The reserved name main is a function name. It is followed by a list of parameters inside the parentheses () followed by a function body marked with braces {}. Braces marking the beginning and the end of a function body can also be on separate lines: int main() { } This simple program does nothing, it has no parameters listed inside parentheses, and there are no statements inside the function body. It is essential to understand that this is the main program signature. There is also another main function signature accepting two different parameters used for manipulating the command line arguments. For now, we will only use the first form. 7 © Slobodan Dmitrović 2020 S. Dmitrović, Modern C++ for Absolute Beginners, https://doi.org/10.1007/978-1-4842-6047-0_4 Chapter 4 Our First Program 4.1 Comments Single line comments in C++ start with double slashes // and the compiler ignores them. We use them to comment or document the code or use them as notes: int main() {     // this is a comment } We can have multiple single-line comments: int main() {     // this is a comment     // this is another comment } Multi-line comments start with the. They are also known as C-style comments. Example: int main() {      } 4.2 Hello World Example Now we are ready to get the first glimpse at our “Hello World” example. The following program is the simplest “Hello World” example. It prints out Hello World. in the console window: #include int main() {     std::cout