Go by Example - Switch

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Go by Example

Go is an open source programming language designed for building simple, fast, and reliable software.

Go by Example is a hands-on introduction to Go using annotated example programs. Check out the first example or browse the full list below.

Go by Example: Switch

golang也有常用的switch语句。

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package main

import "fmt"
import "time"

func main() {
    i := 2
    fmt.Print("Write", i, " as ")
    // 典型的switch结构
    switch i {
        case 1:
            fmt.Println("one")
        case 2:
            fmt.Println("two")
        case 3:
            fmt.Println("three")
    }

    // case后可以跟多个条件，逗号分隔。也有常用的default。
    switch time.Now().Weekday() {
        case time.Saturday, time.Sunday:
            fmt.Println("It's the weekend")
        default:
            fmt.Println("It's a weekday")
    }

    // switch后不跟条件判断语句可以模仿if/else的功能
    t := time.Now()
    switch {
        case t.Hour() < 12:
            fmt.Println("It's before noon")
        default:
            fmt.Println("It's after noon")
    }

    // 变量类型判断的switch语句，其中的type是switch独有的用法。
    // 主要用来判断一个interface值的类型。
    whatAmI := func(i interface{}) {
        switch t := i.(type) {
            case bool:
                fmt.Println("I'm a bool")
            case int:
                fmt.Println("I'm an int")
            default:
                fmt.Println("Don't know type %T\n", t)
        }
    }
    whatAmI(true)
    whatAmI(1)
    whatAmI("hey")
}
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$: go run switch.go
Write 2 as two
It's a weekday
It's after noon
I'm a bool
I'm an int
Don't know type string

原文链接：Go by Example: Switch