package main

import (
    "fmt"
    "os"
)

func init() {
    // 每个包中第一个执行的函数，import时自动执行，不能被用户调用
    // 没有参数，没有返回值
    // 包中包含多个init时，调用顺序不确定
    fmt.Println("Hello Init")
}

func main() {
    //switchTest()
    //gotoTest()
    //enumTest()
    //structTest()
    p1 := Person{name: "小明", age: 10, gender: "男"}
    p1.Eat()
    fmt.Println(p1.name)
    s1 := Student{
        p: Person{
            name:   "小新",
            age:    12,
            gender: "男",
        },
        score:  100,
        school: "实验一小",
    }
    fmt.Println(s1)
    t1 := Teacher{}
    t1.name = "周老师"
    t1.subject = "Python"
    t1.age = 40
    t1.gender = "男"
    fmt.Println(t1)
}

func interfaceTest() {
    // 接口可以接收任意类型的数据
    array := make([]interface{}, 3)
    array[0] = 1
    array[1] = "hello world!"
    array[2] = true
}


type Person struct {
    // 成员属性
    name   string
    age    uint8
    gender string
}

type Student struct {
    // 类的嵌套
    p      Person
    school string
    score  float32
}

type Teacher struct {
    // 类的继承
    Person
    subject string
}

func (p *Person) Eat() {
    // 使用指针可以修改属性值，无指针无法修改属性值
    fmt.Println(p.name + "在吃东西！")
    p.name = "Tom"
}

func deferTest() {
    // 延迟关键字，确保语句在当前栈退出时执行
    // lock.Lock()
    // defer lock.Unlock()
}

func structTest() {
    p := Person{name: "zj", age: 18, gender: "M"}
    fmt.Println(p)
}

func enumTest() {
    const (
        _ = iota
        MONDAY
        TUESDAY
        WEDNESDAY
        THURSDAY
        FRIDAY
        SATURDAY
        SUNDAY
    )
    fmt.Println(MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY)
}

func gotoTest() {
    s := 0
    // LAB 标签
    // goto Lab 下次进入时，不记录循环内的数据
    // continue Lab 下次进入时，记录循环内的数据
    // break Lab 直接跳出指定位置
LAB1:
    s += 1
    for i := 1; i < 10; i++ {
        for j := 1; j <= i; j++ {
            fmt.Print(i, "x", j, "=", i*j, " ")
        }
        fmt.Println()
    }
    if s < 3 {
        goto LAB1
    }
}

func switchTest() {
    cmds := os.Args
    for key, cmd := range cmds {
        fmt.Println(key, cmd)
    }
    // golang中的switch默认自带break
    switch cmds[1] {
    case "-a":
        fmt.Println("all")
        // 关键字fallthrough可以向下穿透
        fallthrough
    case "-b":
        fmt.Println("boss")
    case "-c":
        fmt.Println("Class")
    default:
        fmt.Println("No command")
    }
}