这是我参与「第三届青训营 -后端场」笔记创作活动的的第1篇笔记。
1. 简介
1.1 什么是Go语言？
- 高性能、高并发
- 语法简单、学习曲线平缓
- 丰富的标准库
- 完善的工具链
- 静态链接
- 快速编译
- 跨平台、交叉编译
- 垃圾回收
1.2 谁在使用？
ByteDance（字节跳动）、Tencent（腾讯）、Facebook 、Google……
2. 入门
2.1 开发环境
-
安装golang
-
配置集成开发环境
-
vs code
-
GoLand
-
基于云的开发环境：
-
2.2 基础语法
2.2.1 Hello World
package main
import {
"fmt"
}
func mian(){
fmt.Pritfln("HelloWorld")
}
2.2.2 变量类型（go是强类型语言）
int float double string(内置类型)……
-
变量的声明
type name = valuename := value
2.2.3 if-else
if 条件 {
****
}else if 条件{
*****
}else{
****
}
2.2.4 for
for{
}
for j:=0;j<n;++j{
}
for i<3 {
}
2.2.5 switch
switch a{
case 1:***
case 2:***
case 3:***
case 4:***
}
每一个case 语句不加break,默认是执行完立即跳switch，这是与其他语言不同的
switch{
case t<12:
default:
}
可代替多重if-else的结构
2.2.6 数组
-
定义
name [size]Type
var a[5]int -
使用
与其他语言的数组使用方式相似
2.2.7 切片
-
定义
变量 :=make([]type,n)s:=make([]string,3) -
使用
s[0]="a" s[1]="b" -
特点
类似可以不断扩容的数组
-
元素添加
//[a,b,c] s=append(s,"s") //[a,b,c,s] -
切片
fmt.printf(s[2:3])//[c,s]
2.2.8 map
-
定义
变量名 :=make(map[KeyType]ValueType)m:=make(map[string]int)//单纯定义 m2:=map[string]int{"one":,1,"two":2}//定义赋值 -
更新
m["a"]=1 -
使用
fmt.printf(m["one"]) r,ok=m["one"] //r：返回值；ok：是否存在信息 -
删除元素
delete(m,"one")
2.2.9 range
快速遍历
//数组
for i,num :=range nums{
sum+=num
if num==2{
fmt.printf("index:",i,"num:",num)
}
}
//map
for k,v:=range m{
fmt.Printf("key",k,"value",v);
}
for k=range m{
fmt.Println("key",k);
}
2.2.10 函数
package main
import "fmt"
func add(a int,b int){
return a+b
}
2.2.11 指针
功能有限，主要是对值进行修改
package main
import "fmt"
func add(n *int){
n+=1;
return n;
}
2.2.12 结构体
带类型的字段的集合
package main
import "fmt"
type user struct {
name string
password string
}
func main() {
a := user{name: "wang", password: "1024"}
b := user{"wang", "1024"}
c := user{name: "wang"}
c.password = "1024"
var d user
d.name = "wang"
d.password = "1024"
fmt.Println(a,b,c,d)
fmt.Println(checkPassword(a,"hah"))
fmt.Println(checkPassword2(&a,"hah"))
}
func checkPassword(u user,password string) bool {
return u.password==password
}
func checkPassword2(u *user,password string) bool {
return u.password==password
}
2.2.13 结构体方法
类似于其他语言类成员函数
package main
import "fmt"
type user struct {
name string
password string
}
func main() {
a:=user{"wang","1024"}
fmt.Println(a.checkPassword2("2048"))
fmt.Println(a.checkPassword("2048"))
}
func (u user)checkPassword(password string) bool {
return u.password==password
}
func (u *user)checkPassword2(password string) bool {
return u.password==password
}
2.2.14 错误处理
package main
import (
"errors"
"fmt"
)
type user struct {
name string
password string
}
func findUser(user []user, name string) (y *user, err error) {
for _, u := range user {
if u.name == name {
return &u, nil
}
}
return nil, errors.New("not found")
}
func main() {
u,err :=findUser([]user{{"wang","1024"}},"wang")
if err != nil {
fmt.Println(u.name)
return
}
fmt.Println(u.name)
if u,err := findUser([]user{{"wang","1024"}},"li");err != nil{
fmt.Println(err)
return
}else{
fmt.Println(u.name)
}
}
2.2.15 字符串操作
package main
import (
"fmt"
"strings"
)
func main() {
a := "hello"
fmt.Println(strings.Contains(a, "ll")) //判断是否包含 true
fmt.Println(strings.Count(a, "l")) //字符串计数 2
fmt.Println(strings.HasPrefix(a, "he")) //
fmt.Println(strings.HasSuffix(a, "llo"))
fmt.Println(strings.Index(a, "ll")) //查找字符串位置
fmt.Println(strings.Join([]string{"he", "llo"}, "-")) //sep分割字符串he-llo
fmt.Println(strings.Repeat(a, 2)) //hellohello
fmt.Println(strings.Replace(a, "e", "E", -1)) //hEllo
fmt.Println(strings.Split("a-b-c", "-")) //sep拆分字符串 [a b c]
fmt.Println(strings.ToLower(a)) //hello
fmt.Println(strings.ToUpper(a)) //HELLO
fmt.Println(len(a)) //5
b := "你好"
fmt.Println(len(b)) //6
}
2.2.16 字符串格式化
package main
import "fmt"
type point struct {
x, y int
}
func main() {
s := "hello"
n := 123
p := point{1, 2}
fmt.Println(s, n)
fmt.Println(p)
fmt.Printf("s=%v\n", s)
fmt.Printf("n=%v\n", n)
fmt.Printf("p=%v\n", p)
fmt.Printf("p=%+v\n", p)
fmt.Printf("p=%#v\n", p)
f := 3.141592653
fmt.Println(f)
fmt.Printf("%.2f\n", f)
}
运行结果
hello 123
{1 2}
s=hello
n=123
p={1 2}
p={x:1 y:2}
p=main.point{x:1, y:2}
3.141592653
3.14
2.2.17 JSON处理
package main
import (
"encoding/json"
"fmt"
)
type userInfo struct {
Name string
Age int `json:"age"`
Hobby []string
}
func main() {
a := userInfo{"wang", 18, []string{"Goland", "TypeScript"}}
buf, err := json.Marshal(a) //序列化
if err != nil {
panic(err)
}
fmt.Println(buf) //打印的是16进制编码
fmt.Println(string(buf))
buf, err = json.MarshalIndent(a, "", "\t")
if err != nil {
panic(err)
}
fmt.Println(buf)
var b userInfo
err = json.Unmarshal(buf, &b)
if err != nil {
panic(err)
}
fmt.Printf("%#v\n", b)
}
2.2.18 时间处理
package main
import (
"fmt"
"time"
)
func main() {
now := time.Now()
fmt.Println(now)
t := time.Date(2022, 3, 27, 1, 25, 36, 0, time.UTC)
t2 := time.Date(2022, 3, 27, 2, 30, 36, 0, time.UTC)
fmt.Println(t)
fmt.Println(t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute())
fmt.Println(t.Format("2006-01-02 15:04:05"))
diff := t2.Sub(t)
fmt.Println(diff)
fmt.Println(diff.Minutes(), diff.Seconds())
t3, err := time.Parse("2006-01-02 15:04:05", "2022-03-27 01:25:36")
if err != nil {
panic(err)
}
fmt.Println(t3)
fmt.Println(now.Unix())
}
//运行结果
2022-05-10 17:06:58.7885904 +0800 CST m=+0.002621601
2022-03-27 01:25:36 +0000 UTC
2022 March 27 1 25
2022-03-27 01:25:36
1h5m0s
65 3900
2022-03-27 01:25:36 +0000 UTC
1652173618
2.2.19 数字解析
package main
import (
"fmt"
"strconv"
)
func main() {
f, _ := strconv.ParseFloat("1.234", 64)
fmt.Println(f)
n, _ := strconv.ParseInt("111", 10, 64)
fmt.Println(n)
n1, _ := strconv.ParseInt("0x1000", 0, 64)
fmt.Println(n1)
n2, _ := strconv.Atoi("123")
fmt.Println(n2)
n3, err := strconv.Atoi("AAA")
fmt.Println(n3, err)
}
//运行结果
1.234
111
4096
123
0 strconv.Atoi: parsing "AAA": invalid syntax
2.2.20 进程信息
package main
import (
"fmt"
"os"
"os/exec"
)
func main() {
// go run example/20-env/main.go a b c d
fmt.Println(os.Args) // [/var/folders/8p/n34xxfnx38dg8bv_x8l62t_m0000gn/T/go-build3406981276/b001/exe/main a b c d]
fmt.Println(os.Getenv("PATH")) // /usr/local/go/bin...
fmt.Println(os.Setenv("AA", "BB"))
buf, err := exec.Command("grep", "127.0.0.1", "/etc/hosts").CombinedOutput()
if err != nil {
panic(err)
}
fmt.Println(string(buf)) // 127.0.0.1 localhost
}
3.实战
3.1 猜数字游戏
/*V5*/
package main
import (
"bufio"
"fmt"
"math/rand"
"os"
"strconv"
"strings"
"time"
)
func main() {
maxNum := 100
rand.Seed(time.Now().UnixNano())
secretNumber := rand.Intn(maxNum)
// fmt.Println("The secret number is ", secretNumber)
fmt.Println("Please input your guess")
reader := bufio.NewReader(os.Stdin)
for {
input, err := reader.ReadString('\n')
if err != nil {
fmt.Println("An error occured while reading input. Please try again", err)
continue
}
input = strings.TrimSuffix(input, "\r\n")
guess, err := strconv.Atoi(input)
if err != nil {
fmt.Println("Invalid input. Please enter an integer value")
continue
}
fmt.Println("You guess is", guess)
if guess > secretNumber {
fmt.Println("Your guess is bigger than the secret number. Please try again")
} else if guess < secretNumber {
fmt.Println("Your guess is smaller than the secret number. Please try again")
} else {
fmt.Println("Correct, you Legend!")
break
}
}
}
3.2 命令行在线词典
代码生成
https://curlconverter.com/#go
json转go
https://oktools.net/json2go
package main
import (
"bytes"
"encoding/json"
"fmt"
"io/ioutil"
"log"
"net/http"
)
type DictRequest struct {
TransType string `json:"trans_type"`
Source string `json:"source"`
UserID string `json:"user_id"`
}
type DictResponse struct {
Rc int `json:"rc"`
Wiki struct {
KnownInLaguages int `json:"known_in_laguages"`
Description struct {
Source string `json:"source"`
Target interface{} `json:"target"`
} `json:"description"`
ID string `json:"id"`
Item struct {
Source string `json:"source"`
Target string `json:"target"`
} `json:"item"`
ImageURL string `json:"image_url"`
IsSubject string `json:"is_subject"`
Sitelink string `json:"sitelink"`
} `json:"wiki"`
Dictionary struct {
Prons struct {
EnUs string `json:"en-us"`
En string `json:"en"`
} `json:"prons"`
Explanations []string `json:"explanations"`
Synonym []string `json:"synonym"`
Antonym []string `json:"antonym"`
WqxExample [][]string `json:"wqx_example"`
Entry string `json:"entry"`
Type string `json:"type"`
Related []interface{} `json:"related"`
Source string `json:"source"`
} `json:"dictionary"`
}
func query(word string) {
client := &http.Client{}
request := DictRequest{TransType: "en2zh", Source: word}
buf, err := json.Marshal(request)
if err != nil {
log.Fatal(err)
}
var data = bytes.NewReader(buf)
req, err := http.NewRequest("POST", "https://api.interpreter.caiyunai.com/v1/dict", data)
if err != nil {
log.Fatal(err)
}
req.Header.Set("Connection", "keep-alive")
req.Header.Set("DNT", "1")
req.Header.Set("os-version", "")
req.Header.Set("sec-ch-ua-mobile", "?0")
req.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36")
req.Header.Set("app-name", "xy")
req.Header.Set("Content-Type", "application/json;charset=UTF-8")
req.Header.Set("Accept", "application/json, text/plain, */*")
req.Header.Set("device-id", "")
req.Header.Set("os-type", "web")
req.Header.Set("X-Authorization", "token:qgemv4jr1y38jyq6vhvi")
req.Header.Set("Origin", "https://fanyi.caiyunapp.com")
req.Header.Set("Sec-Fetch-Site", "cross-site")
req.Header.Set("Sec-Fetch-Mode", "cors")
req.Header.Set("Sec-Fetch-Dest", "empty")
req.Header.Set("Referer", "https://fanyi.caiyunapp.com/")
req.Header.Set("Accept-Language", "zh-CN,zh;q=0.9")
req.Header.Set("Cookie", "_ym_uid=16456948721020430059; _ym_d=1645694872")
resp, err := client.Do(req)
if err != nil {
log.Fatal(err)
}
defer resp.Body.Close()
bodyText, err := ioutil.ReadAll(resp.Body)
if err != nil {
log.Fatal(err)
}
if resp.StatusCode != 200 {
log.Fatal("bad StatusCode:", resp.StatusCode, "body", string(bodyText))
}
var dictResponse DictResponse
err = json.Unmarshal(bodyText, &dictResponse)
if err != nil {
log.Fatal(err)
}
fmt.Println(word, "UK:", dictResponse.Dictionary.Prons.En, "US:", dictResponse.Dictionary.Prons.EnUs)
for _, item := range dictResponse.Dictionary.Explanations {
fmt.Println(item)
}
}
func main() {
// if len(os.Args) != 2 {
// fmt.Fprintf(os.Stderr, `usage: simpleDict WORD
//example: simpleDict hello
// `)
// os.Exit(1)
// }
// word := os.Args[1]
/*这里直接用scanf输入word*/
var word string
fmt.Scanf("%v", &word)
query(word)
}
\
