GO 基础-白红宇

GO 基础

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发布时间：2019-06-24

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安装：

hg clone -u release https://code.google.com/p/gocd go/src./all.bash

下载编译好的安装包

编辑器：

liteIDE

Eclipse --- goeclipse插件

http://code.google.com/p/goclipse/wiki/InstallationInstructions

代码提示+自动完成

go get -u github.com/nsf/gocode

查看源文件可以使用NotePad++

基本命令:

go build test clean fmt get install doc

编译测试清理格式化获取远程代码安装说明

语言基础:

基础类型:

布尔 bool 整型(int8-byte int16 int32-rune int64 uint8 uint16 uint32 uint64) int uint 字符串 string 错误 error

常量 const

表达式:

const PI = 3.141592653

var i int = 1

i := 1

枚举 itoa

const(    x = iota  // x == 0    y = iota  // y == 1    z = iota  // z == 2    w  // 常量声明省略值时，默认和之前一个值的字面相同。这里隐式地说w = iota，因此w == 3。其实上面y和z可同样不用"= iota")

array 数组 slice 不需声明长度的数组 map

a := [3]int{1, 2, 3}c := [...]int{4, 5, 6}slice := []byte {'a', 'b', 'c', 'd'}// 声明一个数组var array = [10]byte{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'}// 声明两个slicevar aSlice, bSlice []byte// 演示一些简便操作aSlice = array[:3] // 等价于aSlice = array[0:3] aSlice包含元素: a,b,caSlice = array[5:] // 等价于aSlice = array[5:9] aSlice包含元素: f,g,h,i,jaSlice = array[:]  // 等价于aSlice = array[0:9] 这样aSlice包含了全部的元素// 从slice中获取sliceaSlice = array[3:7]  // aSlice包含元素: d,e,f,g，len=4，cap=7bSlice = aSlice[1:3] // bSlice 包含aSlice[1], aSlice[2] 也就是含有: e,fbSlice = aSlice[:3]  // bSlice 包含 aSlice[0], aSlice[1], aSlice[2] 也就是含有: d,e,fbSlice = aSlice[0:5] // 对slice的slice可以在cap范围内扩展，此时bSlice包含：d,e,f,g,hbSlice = aSlice[:]   // bSlice包含所有aSlice的元素: d,e,f,g// 声明一个key是字符串，值为int的字典,这种方式的声明需要在使用之前使用make初始化var numbers map[string] int// 另一种map的声明方式numbers := make(map[string]int)numbers["one"] = 1  //赋值numbers["ten"] = 10 //赋值numbers["three"] = 3

make 和 new

make用于内建类型（map、slice 和channel）的内存分配。new用于各种类型的内存分配

new返回指针 make返回初始化后的（非零）值

流程函数:

if goto for switch

func funcName(input1 type1, input2 type2) (output1 type1, output2 type2) {    //这里是处理逻辑代码    //返回多个值    return value1, value2}

变参支持 --- 采用array实现

支持传递指针 * &

defer 关键字，在函数退出之后执行，后进先出的栈原则

struct:

struct支持匿名字段

package mainimport "fmt"type Human struct {    name string    age int    phone string  // Human类型拥有的字段}type Employee struct {    Human  // 匿名字段Human    speciality string    phone string  // 雇员的phone字段}func main() {    Bob := Employee{Human{"Bob", 34, "777-444-XXXX"}, "Designer", "333-222"}    fmt.Println("Bob's work phone is:", Bob.phone)    // 如果我们要访问Human的phone字段    fmt.Println("Bob's personal phone is:", Bob.Human.phone)}

面向对象:

func (r ReceiverType) funcName(parameters) (results)

可以继承和重载

interface

package mainimport "fmt"type Human struct {    name string    age int    phone string}type Student struct {    Human //匿名字段    school string    loan float32}type Employee struct {    Human //匿名字段    company string    money float32}//Human实现Sayhi方法func (h Human) SayHi() {    fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)}//Human实现Sing方法func (h Human) Sing(lyrics string) {    fmt.Println("La la la la...", lyrics)}//Employee重载Human的SayHi方法func (e Employee) SayHi() {    fmt.Printf("Hi, I am %s, I work at %s. Call me on %s\n", e.name,        e.company, e.phone) //Yes you can split into 2 lines here.    }// Interface Men被Human,Student和Employee实现// 因为这三个类型都实现了这两个方法type Men interface {    SayHi()    Sing(lyrics string)}func main() {    mike := Student{Human{"Mike", 25, "222-222-XXX"}, "MIT", 0.00}    paul := Student{Human{"Paul", 26, "111-222-XXX"}, "Harvard", 100}    sam := Employee{Human{"Sam", 36, "444-222-XXX"}, "Golang Inc.", 1000}    Tom := Employee{Human{"Sam", 36, "444-222-XXX"}, "Things Ltd.", 5000}    //定义Men类型的变量i    var i Men    //i能存储Student    i = mike    fmt.Println("This is Mike, a Student:")    i.SayHi()    i.Sing("November rain")    //i也能存储Employee    i = Tom    fmt.Println("This is Tom, an Employee:")    i.SayHi()    i.Sing("Born to be wild")    //定义了slice Men    fmt.Println("Let's use a slice of Men and see what happens")    x := make([]Men, 3)    //T这三个都是不同类型的元素，但是他们实现了interface同一个接口    x[0], x[1], x[2] = paul, sam, mike    for _, value := range x{        value.SayHi()    }}

并发:

go chan select

ch := make(chan type, value)value == 0 ! 无缓冲（阻塞）value > 0 ! 缓冲（非阻塞，直到value 个元素）

package mainimport "fmt"type request struct {	a, b   int	replyc chan int}type binOp func(a, b int) intfunc run(op binOp, req *request) {	reply := op(req.a, req.b)	req.replyc <- reply}func server(op binOp, service chan *request, quit chan bool) {	for {		select {		case req := <-service:			go run(op, req) // don't wait for it		case ok := <-quit:			fmt.Println(ok)			return		}	}}func startServer(op binOp) (service chan *request, quit chan bool) {	service = make(chan *request)	quit = make(chan bool)	go server(op, service, quit)	return service, quit}func test(a, b int) (c int) {	c = a + b	fmt.Println(c)	return c}func main() {	adder, quit := startServer(test)	const N = 100	var reqs [N]request	for i := 0; i < N; i++ {		req := &reqs[i]		req.a = i		req.b = i + N		req.replyc = make(chan int)		adder <- req	}	quit <- true	for i := N - 1; i >= 0; i-- { // doesn't matter what order		if <-reqs[i].replyc != N+2*i {			fmt.Println("fail at", i)		}	}	fmt.Println("done")}

关键字:

break    default      func    interface    selectcase     defer        go      map          structchan     else         goto    package      switchconst    fallthrough  if      range        typecontinue for          import  return       var