The authoritative resource to writing clear and idiomatic Go to solve real-world problems Google’s Go team member Alan A. A. Donovan and Brian Kernighan, co-author of The C Programming Language, provide hundreds of interesting and practical examples of well-written Go code to help programmers learn this flexible, and fast, language. It is designed to get you started programming with Go right away and then to progress on to more advanced topics. Basic components : an opening tutorial provides information and examples to get you off the ground and doing useful things as quickly as possible. This includes: command-line arguments gifs URLs web servers Program structure : simple examples cover the basic structural elements of a Go program without getting sidetracked by complicated algorithms or data structures. Data types: Go offers a variety of ways to organize data, with a spectrum of data types that at one end match the features of the hardware and at the other end provide what programmers need to conveniently represent complicated data structures. Composite types : arrays slices maps structs JSON test and HTML templates Functions : break a big job into smaller pieces that might well be written by different people separated by both time and space. Methods : declarations with a pointer receiver struct embedding values and expressions Interfaces : write functions that are more flexible and adaptable because they are not tied to the details of one particular implementation. Concurrent programming : Goroutines, channels, and with shared variables. Packages : use existing packages and create new ones. Automated testing : write small programs that check the code. Reflection features : update variables and inspect their values at run time. Low-level programming : step outside the usual rules to achieve the highest possible performance, interoperate with libraries written in other languages, or implement a function that cannot be expressed in pure Go. Each chapter has exercises to test your understanding and explore extensions and alternatives. Source code is freely available for download and may be conveniently fetched, built, and installed using the go get command.

Table of Contents:
Preface xi Chapter 1: Tutorial 1 1.1 Hello, World 1 1.2 Command-Line Arguments 4 1.3 Finding Duplicate Lines 8 1.4 Animated GIFs 13 1.5 Fetching a URL 15 1.6 Fetching URLs Concurrently 17 1.7 A Web Server 19 1.8 Loose Ends 23 Chapter 2: Program Structure 27 2.1 Names 27 2.2 Declarations 28 2.3 Variables 30 2.4 Assignments 36 2.5 Type Declarations 39 2.6 Packages and Files 41 2.7 Scope 45 Chapter 3: Basic Data Types 51 3.1 Integers 51 3.2 Floating-Point Numbers 56 3.3 Complex Numbers 61 3.4 Booleans 63 3.5 Strings 64 3.6 Constants 75 Chapter 4: Composite Types 81 4.1 Arrays 81 4.2 Slices 84 4.3 Maps 93 4.4 Structs 99 4.5 JSON 107 4.6 Text and HTML Templates 113 Chapter 5: Functions 119 5.1 Function Declarations 119 5.2 Recursion 121 5.3 Multiple Return Values 124 5.4 Errors 127 5.5 Function Values 132 5.6 Anonymous Functions 135 5.7 Variadic Functions 142 5.8 Deferred Function Calls 143 5.9 Panic 148 5.10 Recover 151 Chapter 6:. Methods 155 6.1 Method Declarations 155 6.2 Methods with a Pointer Receiver 158 6.3 Composing Types by Struct Embedding 161 6.4 Method Values and Expressions 164 6.5 Example: Bit Vector Type 165 6.6 Encapsulation 168 Chapter 7: Interfaces 171 7.1 Interfaces as Contracts 171 7.2 Interface Types 174 7.3 Interface Satisfaction 175 7.4 Parsing Flags with flag.Value 179 7.5 Interface Values 181 7.6 Sorting with sort.Interface 186 7.7 The http.Handler Interface 191 7.8 The error Interface 196 7.9 Example: Expression Evaluator 197 7.10 Type Assertions 205 7.11 Discriminating Errors with Type Assertions 206 7.12 Querying Behaviors with Interface Type Assertions 208 7.13 Type Switches 210 7.14 Example: Token-Based XML Decoding 213 7.15 A Few Words of Advice 216 Chapter 8: Goroutines and Channels 217 8.1 Goroutines 217 8.2 Example: Concurrent Clock Server 219 8.3 Example: Concu rent Echo Server 222 8.4 Channels 225 8.5 Looping in Parallel 234 8.6 Example: Concurrent Web Crawler 239 8.7 Multiplexing with select 244 8.8 Example: Concurrent Directory Traversal 247 8.9 Cancellation 251 8.10 Example: Chat Server 253 Chapter 9: Concurrency with Shared Variables 257 9.1 Race Conditions 257 9.2 Mutual Exclusion: sync.Mutex 262 9.3 Read/Write Mutexes: sync.RWMutex 266 9.4 Memory Synchronization 267 9.5 Lazy Initialization: sync.Once 268 9.6 The Race Detector 271 9.7 Example: Concurrent Non-Blocking Cache 272 9.8 Goroutines and Threads 280 Chapter 10: Packages and the Go Tool 283 10.1 Introduction 283 10.2 Import Paths 284 10.3 The Package Declaration 285 10.4 Import Declarations 285 10.5 Blank Imports 286 10.6 Packages and Naming 289 10.7 The Go Tool 290 Chapter 11: Testing 301 11.1 The go test Tool 302 11.2 Test Functions 302 11.3 Coverage 318 11.4 Benchmark Functions 321 11.5 Profiling 323 11.6 Example Functions 326 Chapter 12: Reflection 329 12.1 Why Reflection? 329 12.2 reflect.Type and reflect.Value 330 12.3 Display, a Recursive Value Printer 333 12.4 Example: Encoding S-Expressions 338 12.5 Setting Variables with reflect.Value 341 12.6 Example: Decoding S-Expressions 344 12.7 Accessing Struct Field Tags 348 12.8 Displaying the Methods of a Type 351 12.9 A Word of Caution 352 Chapter 13: Low-Level Programming 353 13.1 unsafe.Sizeof, Alignof, and Offsetof 354 13.2 unsafe.Pointer 356 13.3 Example: Deep Equivalence 358 13.4 Calling C Code with cgo 361 13.5 Another Word of Caution 366 Index 367