Язык программирования Go

A Tutorial for the Go Programming Language

Introduction

Hello, World

Compiling

Echo

An Interlude about Types

An Interlude about Allocation

An Interlude about Constants

An I/O Package

Rotting cats

Sorting

Printing

Prime numbers

Multiplexing

Introduction[Top]

This document is a tutorial introduction to the basics of the Go programming language, intended for programmers familiar with C or C++. It is not a comprehensive guide to the language; at the moment the document closest to that is the language specification. After you've read this tutorial, you might want to look at Effective Go, which digs deeper into how the language is used. Also, slides from a 3-day course about Go are available: Day 1, Day 2, Day 3.

The presentation here proceeds through a series of modest programs to illustrate key features of the language. All the programs work (at time of writing) and are checked into the repository in the directory /doc/progs/.

Program snippets are annotated with the line number in the original file; for cleanliness, blank lines remain blank.

Hello, World[Top]

Let's start in the usual way:

05 package main

07 import fmt "fmt" // Package implementing formatted I/O.

09 func main() { 10 fmt.Printf("Hello, world; or Καλημέρα κόσμε; or こんにちは 世界\n"); 11 }

Every Go source file declares, using a package statement, which package it's part of. It may also import other packages to use their facilities. This program imports the package fmt to gain access to our old, now capitalized and package-qualified, friend, fmt.Printf.

Functions are introduced with the func keyword. The main package's main function is where the program starts running (after any initialization).

String constants can contain Unicode characters, encoded in UTF-8. (In fact, Go source files are defined to be encoded in UTF-8.)

The comment convention is the same as in C++:

/* ... */

// ...

Later we'll have much more to say about printing.

Compiling[Top]

Go is a compiled language. At the moment there are two compilers. Gccgo is a Go compiler that uses the GCC back end. There is also a suite of compilers with different (and odd) names for each architecture: 6g for the 64-bit x86, 8g for the 32-bit x86, and more. These compilers run significantly faster but generate less efficient code than gccgo. At the time of writing (late 2009), they also have a more robust run-time system although gccgo is catching up.