Go 1.27

A hands-on introduction to Go,
one annotated example at a time.

Each example is a complete program. The comments explain the code next to them, and the output underneath is what the program really prints. Start at the top for the language basics, or jump to the part of the standard library you need.

Start with Hello World Clone the repo

Examples

Topics

Standard library packages

Lines of Go

6,178

Basics01–07

01Hello World 02Values 03Variables 04Constants 05For 06If/Else 07Switch

Collections08–11

08Arrays 09Slices 10Maps 11Range over Built-in Types

Functions12–16

12Functions 13Multiple Return Values 14Variadic Functions 15Closures 16Recursion

Types and methods17–24

17Pointers 18Strings and Runes 19Structs 20Methods 21Interfaces 22Enums 23Struct Embedding 24Type Assertions

Generics and iterators25–26

25Generics 26Range over Iterators

Errors27–31

27Errors 28Custom Errors 29Panic 30Defer 31Recover

Sorting52–53

52Sorting 53Sorting by Functions

Text54–57

54String Functions 55String Formatting 56Text Templates 57Regular Expressions

Encoding58–63

58JSON 59XML 60CSV 61Base64 Encoding 62SHA256 Hashes 63URL Parsing

Time and numbers64–68

64Time 65Epoch 66Time Formatting / Parsing 67Random Numbers 68Number Parsing

Files and I/O69–76

69Readers and Writers 70Reading Files 71Writing Files 72Line Filters 73File Paths 74Directories 75Temporary Files and Directories 76Embed Directive

Command line77–81

77Command-Line Arguments 78Command-Line Flags 79Command-Line Subcommands 80Environment Variables 81Logging

Networking82–84

82HTTP Client 83HTTP Server 84TCP Server

Processes and signals85–88

85Spawning Processes 86Exec'ing Processes 87Signals 88Exit

Testing and packages89–91

89Testing and Benchmarking 90Packages and Modules 91Reflection

A hands-on introduction to Go, one annotated example at a time.