Go语言入门教程：基础语法与实践示例

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本资源是一份关于学习Golang（也称为Go）的教程，由Miek Gieben撰写并按照Go Authors和Google的认可进行更新。该教程旨在为初学者提供基础的Go语言语法和示例，以便逐步掌握这个强大的编程语言。在"Learning Go"这一章节，作者列出了多个贡献者，包括Adam J. Gray、Alex Sychev、Andrea Spadaccini等，他们在 alphabetical order 的顺序中被提及。这体现了Go语言社区的开放性与合作精神，每个开发者都在不断推动和完善Go的教育内容。教程遵循Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License，这意味着用户可以自由地分享和学习，但仅限于非商业用途，并且必须保留原作者和版权信息。如果你想查看完整的许可协议，可以从指定的网站<http://creativecommons.org/licenses/by-nc-sa/3.0/>获取，或者通过邮寄方式联系Creative Commons在旧金山的办公室。 Go语言是Google在2007年由Robert Griesemer、Rob Pike和Ken Thompson三位创始人开发的语言，以其简洁、高效和并发能力强而著称。Go的设计理念强调了并发性、内存安全性和模块化，使得它特别适合构建高并发的网络服务和分布式系统。在本教程中，你将学习到的基本Go语法内容可能包括但不限于以下几个方面： 1. **变量声明**：理解基本数据类型如int、float、string以及布尔值的声明方式。 2. **控制流**：学会如何使用if-else语句、for循环、switch-case结构来控制程序流程。 3. **函数和方法**：掌握函数定义、参数传递以及Go特有的接口和方法。 4. **结构体与封装**：理解如何创建自定义的数据结构和访问修饰符。 5. **错误处理**：学习Go的错误处理机制，包括panic和recover的使用。 6. **并发与通道**：探索Go语言内置的goroutine和channel，实现并发执行任务和通信。 7. **包管理**：了解如何组织和导入其他包，以实现模块化的代码结构。随着教程的深入，还将涉及Go的编译器特性、垃圾回收机制、并发安全以及Go在云计算、微服务架构中的应用示例。对于希望进入IT领域或深化对Go语言理解的人来说，这份教程是宝贵的学习资源。随着作者的持续更新，更多实用技巧和最佳实践将被涵盖，确保读者能够逐步提升自己的编程技能。

Hello World

Erlang [7] also shares some of the features of Go. Notable differences between Erlang and

Go is that Erlang borders on being a functional language, where Go is an imperative one.

And Erlang runs in a virtual machine, while Go is compiled. Go also has a much more

Unix-like feel to it.

Hello World

In the Go tutorial, Go is presented to the world in the typical manner: letting it print “Hello

World” (Ken Thompson and Dennis Ritchie started this when they presented the C lan-

guage in the 1970s). We don’t think we can do better, so here it is, “Hello World” in Go.

Listing 2.1. Hello world

1package main

3import "fmt" // Implements formatted I/O.

5/* Print something */

6func main() {

8fmt.Printf("Hello, world; or καληµ´ϵρα κóσµϵ; or こんにちは世界")

Lets look at the program line by line.

This first line is just required. All Go files start with package <something>, package

main is required for a standalone executable;

This says we need fmt in addition to main. A package other than main is commonly

called a library, a familiar concept in many programming languages (see chapter 4).

The line ends with a comment which is started with //;

This is also a comment, but this one is enclosed in /* and */;

Just as package main was required to be first, import may come next. In Go, package

is always first, then import, then everything else. When your Go program is exe-

cuted, the first function called will be main.main(), which mimics the behavior from

C. Here we declare that function;

On line 8 we call a function from the package fmt to print a string to the screen. The

string is enclosed with " and may contain non-ASCII characters. Here we use Greek

and Japanese.

Compiling and running code

The preferred way to build a Go program is to use the go tool. To build helloworld we just

enter:

% go build helloworld.go

This results in an executable called helloworld.

Chapter 2: Basics

% ./helloworld

Hello, world; or καληµ´ϵρα κóσµϵ; or こんにちは世界

Settings used in this book

• Go itself is installed in ˜/go, and $GOROOT is set to GOROOT=˜/go ;

• Go source code we want to compile ourself is placed in ˜/g/src and $GOPATH is set to

GOPATH=˜/g . This variable comes into play when we start using packages (chapter

4).

Variables, types and keywords

In the next few sections we will look at the variables, basic types, keywords and control

structures of our new language. Go has a C-like feel when it comes to its syntax. If you want

to put two (or more) statements on one line, they must be separated with a semicolon (’;’).

Normally you don’t need the semicolon.

Go is different from other languages in that the type of a variable is specified after the

variable name. So not: int a, but a int. When declaring a variable it is assigned the

“natural” null value for the type. This means that after var a int, a has a value of 0. With

var s string, s is assigned the zero string, which is "".

Declaring and assigning in Go is a two step process, but they may be combined. Compare

the following pieces of code which have the same effect.

Listing 2.2. Declaration with =

var a int

var b bool

a = 15

b = false

Listing 2.3. Declaration with :=

a := 15

b := false

On the left we use the var keyword to declare a variable and then assign a value to it.

The code on the right uses := to do this in one step (this form may only be used inside

functions). In that case the variable type is deduced from the value. A value of 15 indicates

an int, a value of false tells Go that the type should be bool. Multiple var declarations

may also be grouped; const and import also allow this. Note the use of parentheses:

var (

x int

b bool

)

Multiple variables of the same type can also be declared on a single line: var x, y int

makes x and y both int variables. You can also make use of parallel assignment:

a, b := 20, 16

Which makes a and b both integer variables and assigns 20 to a and 16 to b.

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Mrizzle

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