你的首个golang语言详细入门教程 | your first golang tutorial 原

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your first golang tutorial

go tutorial

versions:

go: 1.13.1

install

wget https://dl.google.com/go/go1.13.1.linux-amd64.tar.gz
sudo tar -C /usr/local -xzf go1.13.1.linux-amd64.tar.gz
ll /usr/local/go
vim ~/.bashrc
export PATH=$PATH:/usr/local/go/bin
source ~/.bashrc

~/.zshrc~/.bashrc

check version

go version
go version go1.13.1 linux/amd64

uninstall

 /usr/local/go

set GOPATH

$HOME/go

GOPATHGOPATH$HOME/go

GOPATH

issue the commands

vim .bashrc
# for golang
export GOPATH=$HOME/go
export PATH=/usr/local/go/bin:$GOPATH:$PATH
source .bashrc
#go env -w GOPATH=$HOME/go
$ echo $GOPATH
/home/kezunlin/go
$ go env GOPATH
/home/kezunlin/go

code organization

Go programmers typically keep all their Go code in a single workspace.
A workspace contains many version control repositories (managed by Git, for example).
Each repository contains one or more packages.
Each package consists of one or more Go source files in a single directory.
The path to a package's directory determines its import path.

like this

bin/
hello # command executable
outyet # command executable
src/
github.com/golang/example/
.git/ # Git repository metadata
hello/
hello.go # command source
outyet/
main.go # command source
main_test.go # test source
stringutil/
reverse.go # package source
reverse_test.go # test source
golang.org/x/image/
.git/ # Git repository metadata
bmp/
reader.go # package source
writer.go # package source
... (many more repositories and packages omitted) ...

symbolic links

import path

go example

your first program

mkdir -p $GOPATH/src/github.com/kezunlin/hello
cd $GOPATH/src/github.com/kezunlin/hello
vim hello.go

with code

package main
import "fmt"
func main() {
fmt.Printf("hello, world\n")
}

build and run

go build
./hello
hello, world

install and clean binary files

# install hello to $HOME/go/bin
go install 

# clean $HOME/go/bin/*
go clean -i

go build github.com/kezunlin/hello/go install github.com/kezunlin/hello/

your first library

stringutil library

mkdir -p $GOPATH/src/github.com/kezunlin/stringutil
cd $GOPATH/src/github.com/kezunlin/stringutil
vim reverse.go

code

// Package stringutil contains utility functions for working with strings.
package stringutil
// Reverse returns its argument string reversed rune-wise left to right.
func Reverse(s string) string {
r := []rune(s)
for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
r[i], r[j] = r[j], r[i]
}
return string(r)
}

package name

namepackage main

build library

go build github.com/kezunlin/stringutil
#This won't produce an output file. Instead it saves 
#the compiled package in the local build cache.

stringutilhello.go

package main
import (
"fmt"
"github.com/kezunlin/stringutil"
)
func main() {
fmt.Printf("hello, world\n")
fmt.Println(stringutil.Reverse("!oG ,olleH"))
}

build and install

go build github.com/kezunlin/hello
go install github.com/kezunlin/hello
~/go/bin$ ./hello
hello, world
Hello, Go!

folder structure

 tree .
.
├── bin
│   └── hello
└── src
└── github.com
└── kezunlin
├── hello
│   └── hello.go
└── stringutil
└── reverse.go
6 directories, 3 files

testing

_test.goTestXXX(t *testing.T)t.Errort.Fail

t.Errort.Fail

package stringutil
import "testing"
func TestReverse(t *testing.T) {
cases := []struct {
in, want string
}{
{"Hello, world", "dlrow ,olleH"},
{"Hello, 世界", "界世 ,olleH"},
{"", ""},
}
for _, c := range cases {
got := Reverse(c.in)
if got != c.want {
t.Errorf("Reverse(%q) == %q, want %q", c.in, got, c.want)
}
}
}

test ok

 $ go test github.com/kezunlin/stringutil
ok github.com/kezunlin/stringutil 0.165s

test error

--- FAIL: TestReverse (0.00s)
reverse_test.go:16: Reverse("Hello, 世界2") == "2界世 ,olleH", want "界世 ,olleH"
FAIL
exit status 1
FAIL github.com/kezunlin/stringutil 0.003s

remote packages

$ go get github.com/golang/example/hello
$ $GOPATH/bin/hello
Hello, Go examples!

go commands

go help gopath
go help importpath
go help test
go build
go install
go clean
go get # fetch,build and install

Reference History

20191011: created.

Post author: kezunlin
Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 3.0 unless stating additionally.