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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
zsh uses env profile
~/.zshrc
, bash use env profile~/.bashrc
.
check version
go version
go version go1.13.1 linux/amd64
uninstall
just delete /usr/local/go
set GOPATH
Create your workspace directory, $HOME/go
.
The
GOPATH
environment variable specifies the location of your workspace. If noGOPATH
is set, it is assumed to be$HOME/go
on Unix systems.
Note that
GOPATH
must not be the same path as your Go installation.
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) ...
Note that
symbolic links
should not be used to link files or directories into your workspace.
An
import path
is a string that uniquely identifies a package.
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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/src
go install github.com/kezunlin/hello/
your first library
stringutil library
mkdir -p $GOPATH/src/github.com/kezunlin/stringutil
cd $GOPATH/src/github.com/kezunlin/stringutil
vim reverse.go
code
// Package stringutil contains utility functions for working with strings.
package stringutil
// Reverse returns its argument string reversed rune-wise left to right.
func Reverse(s string) string {
r := []rune(s)
for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
r[i], r[j] = r[j], r[i]
}
return string(r)
}
package name
where
name
is the package's default name for imports. (All files in a package must use the same name.)
executable commands must always usepackage main
.
build library
go build github.com/kezunlin/stringutil
#This won't produce an output file. Instead it saves
#the compiled package in the local build cache.
use stringutil
in hello.go
package main
import (
"fmt"
"github.com/kezunlin/stringutil"
)
func main() {
fmt.Printf("hello, world\n")
fmt.Println(stringutil.Reverse("!oG ,olleH"))
}
build and install
go build github.com/kezunlin/hello
go install github.com/kezunlin/hello
~/go/bin$ ./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
You write a test by creating a file with a name ending in _test.go
that contains functions named TestXXX
with signature func (t *testing.T)
. The test framework runs each such function; if the function calls a failure function such as t.Error
or t.Fail
, the test is considered to have failed.
- file name: xxx_test.go
- function name: TextXXX
- error:
t.Error
ort.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.
Copyright
- Post author: kezunlin
- Post link: https://kezunlin.me/post/a0fb7f06/
- Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 3.0 unless stating additionally.
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