Go语言pointer及switch fallthrough实战详解

n := 18
// 取地址
fmt.Println(&n)
fmt.Println(*&n)

p := &n
// 根据地址取值
fmt.Printf("%T\n", p) // 打印结果是*int，即int类型的指针
m := *p
fmt.Println(m) //根据地址取值

var a1 *int     //nil pointer
fmt.Println(a1) //<nil>

var a2 = new(int)
fmt.Println(a2)  //内存地址 0xc000108010
fmt.Println(*a2) //0 根据内存地址取值 没有值返回0

*a2 = 100        //根据内存地址赋值
fmt.Println(*a2) //100

finger :=2
if finger==1 {
   fmt.Println("大拇指")
}else if finger==2 {
   fmt.Println("食指")
}else if finger==5 {
   fmt.Println("小拇指")
}else {
   fmt.Println("无效")
}

finger := 2
switch finger {
case 1:
   fmt.Println("大拇指")
case 2:
   fmt.Println("食指")
case 5:
   fmt.Println("小拇指")
default:
   fmt.Println("无效")
}

switch n := 3; n {
case 1, 3, 5, 7, 9:
   fmt.Println("奇数")
case 2, 4, 6, 8, 10:
   fmt.Println("偶数")
}

age := 29
switch {
case age < 18:
   fmt.Println("好好学习Z")
case age > 18 && age < 60:
   fmt.Println("好好上班")
case age > 60:
   fmt.Println("希望不用继续上班了，哈哈")
default:
   fmt.Println(age)
}

package main

import "fmt"

func main() {

    switch {
    case false:
            fmt.Println("false1")
            fallthrough
    case true:
            fmt.Println("true1")
            fallthrough
    case false:
            fmt.Println("false2")
            fallthrough
    case true:
            fmt.Println("true2")
    case false:
            fmt.Println("false3")
            fallthrough
    default:
            fmt.Println("default case")
    }
}