8. 类型声明,方法,接口

1.内置类型2.引用类型3.结构类型4.嵌入类型

1.用户自定义类型

package mainimport (    "fmt")type user struct {    name string    email string    ext int    private bool}func main() {    var a int    a = 100    fmt.Println(a)    var bill user     lisa := user {        name : "lisa",        email : "[e-mail]",        ext : 123,        private : true,    }    fmt.Println(lisa)}

package mainimport (    "fmt")type admin struct {    person user    level string}type user struct {    name string    email string    ext int    private bool}func main() {    fred := admin {        person : user {            name : "Lisa",            email : "[e-mail]",            ext : 123,            private : true,        },        level : "super",    }    fmt.Println(fred)}

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type Duration int64 // 基于 int64 声明一个新类型,相当于 c 语言 typedef，但不是一个类型func main() {    var dur Duration    dur = int64(1000) // 报错，编译器不会对不同类型的值做隐式转换    fmt.Println(dur)}

package mainimport (    "fmt")type Duration int64func main() {    var dur Duration    //报错：.\hello.go:11: cannot use int64(1000) (type int64) as type Duration in assignment    dur = int64(1000)    fmt.Println(dur)}

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1. 方法
   

package mainimport "fmt"type user struct {    name string    email string}func (u user) notify() {    fmt.Printf("Sending User Email To %s<%s>\n", u.email,u.email)}func (u *user) change(email string) {    u.email = email}func main() {    //user 类型的值可以用来调用    //使用值接收者声明的方法    bill := user{"Bill", "[e-mail]"}    bill.notify()    //使用值接收者声明的方法    //使用值接收者声明的方法    lisa := &user{"Lisa", "[e-mail]"}    lisa.notify() // (*lisa).notify() 编译器转换的    //user 类型的值可以用来调用    //使用指针接收者声明的方法    bill.change("[e-mail]") // (&bill).changeEmail ("[e-mail]")    bill.notify()}

值接收者：

指针接收者：

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3.接口

package mainimport (    "fmt")type notifier interface {    notify()}type user struct {    name string    email string}func (u *user) notify() {    fmt.Printf("Sending user email %s<%s>\n",    u.name,    u.email)}func main() {    u := user{"bill","[e-mail]"}    // 报错,.\hello.go:24: cannot use u (type user) as type notifier in argument to sendNotification:    //user does not implement notifier (notify method has pointer receiver)    sendNotification(u)    //sendNotification(&u)}func sendNotification(n notifier) {    n.notify()}

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4.公开或未公开标示符