Rumeel Hussain and Maryam Zulfiqar

Beginning Go Programming

Build Reliable and Efficient Applications with Go

Rumeel Hussain
Dubai, United Arab Emirates
Maryam Zulfiqar
Lahore, Pakistan
ISBN 978-1-4842-8857-3e-ISBN 978-1-4842-8858-0
https://doi.org/10.1007/978-1-4842-8858-0
© Rumeel Hussain and Maryam Zulfiqar 2022
Apress Standard
The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.
The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made.

This Apress imprint is published by the registered company APress Media, LLC, part of Springer Nature.

The registered company address is: 1 New York Plaza, New York, NY 10004, U.S.A.

This book is dedicated to Rumeel’s late mother and Abdullah Hassan.

Preface

Google designed the Go language to be comprehensive yet be powerful enough to tackle big problems. It is a multi-paradigm programming language with built-in features for concurrent programming. It enables developers to easily build software that is simple, reliable, and efficient. This book is designed to provide knowledge to beginners and help them start developing great Go-based applications.

In this book, we cover the basics of the Go programming language and provide you with hands-on working experience through clear examples and recipes. From basic syntax formulation to providing insights into using the Go language to build concurrent programs and applications like HTTP servers and communication with REST APIs, this book covers it all.

This is a practical hands-on guide through which you will learn how to write Go code using clear examples that demonstrate the language in action. You’ll also learn tips and tricks about the Go programming language for an efficient use.

Table of Contents
Chapter 1:​ Introduction1
Is GoLang Static-Typed or Compiled?​1
Compiled Programming Language2
Statically-Typed Language2
Is Go an Object-Oriented Programming Language?​3
Features that Make GoLang the Premium Choice for Programming3
Intentionally Excluded Features from GoLang4
Go Programs5
Summary5
Chapter 2:​ Go Basics7
Ancestors of Go7
Go Syntax7
Installing Go11
Go Playground12
Developing Go Applications Using IDEs13
Getting Started Programming Go Applications14
Let’s Print Hello World!14
How to Execute a Go Program16
Keywords17
Variables18
Variable Data Types18
Variable Naming Conventions20
Declaring Variables20
Taking User Input22
Using scanf23
Using Scanln24
Using bufio25
Math Operators and Packages26
The Math Package31
Dates and Times33
Operators Precedence in Go35
Memory Management and Reference Values36
New vs Make37
Incorrect Memory Allocation Example37
Correct Memory Allocation Example38
Memory Deallocation39
Pointers Data Type39
What Is a Pointer?​39
Declaring Pointers in Go40
Comparison with Java and C-Style Languages43
Ordered Values in Arrays and Slices43
Arrays in Go44
Slices in Go48
Maps57
Defining Maps57
Adding Entries to a Map Object57
Deleting Entries from a Map Object58
Iterating Over Stored Values in a Map Object58
Structs Data Type62
Defining a Structure63
Accessing Members of a Structure63
Passing Structures as Function Arguments65
Pointers to Structures67
Program Flow70
If Statement70
Switch Statement72
For Statement75
The goto Statement78
Functions79
Defining a Function80
Doing Function Calls in Go82
Return More than One Value from Functions84
Passing Arguments to Functions85
Methods88
Write/​Read Text Files91
Write Text Files91
Read Text Files93
HTTP Package95
JSON97
Summary102
Chapter 3:​ Go Recipes:​ Programming Fundamentals and Basics103
Numbers and Slices in Go103
Working with Maps in Go106
Go’s Catch of Error Handling107
Defer and Panic Recovery110
Hands-on Challenge114
Solution114
Summary116
Chapter 4:​ Working with Text117
Go String Formatting and Working with Unicode117
Case-Insensitive Comparisons in Go119
Regular Expressions and Reading Text Files with Go121
Hands-on Challenge129
Solution130
Summary132
Chapter 5:​ Structs, Methods, and Interfaces133
Go Structs, Methods, and Interfaces133
Structs134
Methods140
Interfaces142
Empty Interface and Working with IOTA in Go148
JSON Encoding/​Decoding148
Generics151
Hands-on Challenge153
Solution153
Summary158
Chapter 6:​ Working with JSON159
JSON Package159
Unmarshalling JSON with GO160
Parsing Complex JSON with Go163
Marshalling JSON with Go167
Handling Missing Values and Zeros in JSON169
Using mapstructure to Handle Arbitrary JSON172
Summary176
Chapter 7:​ HTTP177
Go and HTTP Calls177
Authentication and Writing an HTTP Server in Go182
REST with gorilla/​mux187
Hands-on Challenge191
Solution192
Summary203
Chapter 8:​ Concurrency205
Understanding Goroutines206
Converting Sequential Code into Concurrent Code207
Using Goroutines with Shared Resources217
Seeing the Impact of Shared Resources on Goroutines217
Accessing Shared Resources Using Mutual Exclusion220
Modifying Shared Resources Using Atomic Counters223
Synchronizing Goroutines225
sync.​WaitGroup and sync.​Once226
Timeouts in Go230
Pooling Goroutines233
Hands-On Challenge236
Solution236
Summary239
Chapter 9:​ Tricks and Handy Tips241
Importing Packages241
Check What Packages Are Being Imported by Your Application242
Use goimports Instead of gofmt243
Code Organization243
To Use or Not to Use:​ Custom Constructors243
Modularizing and Organizing Code into Packages244
Dependency Package Management245
Compiler Optimizations245
Using Git’s SHA to Set the Build ID248
The Case of Elegant Constants, aka IOTA248
Auto Increment250
Custom Types250
Skipping Values253
Expressions253
Tricky Constants254
Summary255
Index257
About the Authors
Rumeel Hussain

A photo of Rumeel Hussain.

has a bachelor’s degree in computer science and is presently working as a Blockchain Solution Architect at BNB Chain, supporting the development and growth of the BNB Chain ecosystem. He is an information technology enthusiast with more than five years of experience leading and implementing blockchain applications and architectures, analyzing and refactoring modern programming languages like Go, troubleshooting cloud infrastructure, and assessing security risks. His current work is focused on leveraging blockchain technology and crypto to achieve the full potential of Web3 applications.
 
Maryam Zulfiqar

has four years of research experience and has a master’s degree in computer science. She is currently working as a Tech Martian at BNB Chain. She also works as a senior researcher and developer. She is passionate about developer education, especially about sharing her knowledge on topics that are “the talk of the town” in the technology field. She has also worked in researcher and teamlead roles for HEC-funded projects targeted at community growth and welfare.

 
About the Technical Reviewer
Fabio Claudio Ferracchiati

is a senior consultant and a senior analyst/developer using Microsoft technologies. He works for BluArancio (www.bluarancio.com). He is a Microsoft Certified Solution Developer for .NET, a Microsoft Certified Application Developer for .NET, a Microsoft Certified Professional, and a prolific author and technical reviewer. Over the past ten years, he’s written articles for Italian and international magazines and coauthored more than ten books on a variety of computer topics.

 
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