Go语言基础--命令式编程 ｜ 青训营笔记

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 Go语言基础--命令式编程

1. 格式化输出

• fmt.Print
• fmt.Println
• fmt.Printf

package main
import "fmt"
// main 是所有程序的起始函数
func main() {
    fmt.Print("My weight on the surface of Mars is ")
    fmt.Print(149.0 * 0.3783)
    fmt.Print(" lbs, and I would be ")
    fmt.Print(41 * 365 / 687)
    fmt.Print(" years old.")
} 

fmt.Println("My weight on the surface of Mars is", 149.0*0.3783, "lbs, and I would be",
41*365.2425/687, "years old.")

fmt.Printf("My weight on the surface of Mars is %v lbs,", 149.0*0.3783)//单个变量
fmt.Printf(" and I would be %v years old.\n", 41*365/687)
fmt.Printf("My weight on the surface of %v is %v lbs.\n", "Earth", 149.0)//多个变量

2. 变量

• const:常量
• var:变量 声明：

const hoursPerDay = 24
var distance = 56000000
var speed = 100800
var (
    distance = 56000000
    speed = 100800
)
var distance, speed = 56000000, 100800

注：支持i++ 不支持++i

• 随机数： 引包："math/rand" 使用：rand.Intn(10)

package main
import (
    "fmt"
    "math/rand"
)
func main() {
    var num = rand.Intn(10) + 1
    fmt.Println(num)
    num = rand.Intn(10) + 1
    fmt.Println(num)
}

3. 循环和分支

• 布尔

var a = true
var b = false

var command = "walk outside"
var exit = strings.Contains(command, "outside")

• if

if strs == "abd" {
   fmt.Println("sss")
} else {
   fmt.Println("asdad")
}

• switch

var command = "1"
switch command {
    case "1":
        fmt.Println("You head further up the mountain.")
    case "2":
        fmt.Println("You find yourself in a dimly lit cavern.")
    case "3":
        fmt.Println("The sign reads 'No Minors'.")
    default:
        fmt.Println("Didn't quite get that.")
}

fallthrough关键字：

var room = "lake"
switch {
case room == "cave":
   fmt.Println("You find yourself in a dimly lit cavern.")
case room == "lake":
   fmt.Println("The ice seems solid enough.")
   fallthrough//跳到下一个选择
case room == "underwater":
   fmt.Println("The water is freezing cold.")
}

• for

var count = 10
for count > 0 {
    fmt.Println(count)
    time.Sleep(time.Second)
    count--
}
fmt.Println("Liftoff!")

for count := 10; count > 0; count-- {
    fmt.Println(count)
}