你可能对switch有这样的印象。

它有case和break语句，除非有失败的语句结束。

1 package main 2  3 import ( 4     "fmt" 5     "runtime" 6 ) 7  8 func main() { 9     fmt.Print("Go runs on ")10     switch os := runtime.GOOS; os {11     case "darwin":12         fmt.Println("OS X.")13     case "linux":14         fmt.Println("Linux.")15     default:16         // freebsd, openbsd,17         // plan9, windows...18         fmt.Printf("%s.", os)19     }20 }

Go runs on Linux. switch 从上到下评估一个case，直到找到一个匹配的case,才停止。

1 package main 2  3 import ( 4     "fmt" 5     "time" 6 ) 7  8 func main() { 9     fmt.Println("When's Saturday?")10     today := time.Now().Weekday()11     switch time.Saturday {12     case today+0:13         fmt.Println("Today.")14     case today+1:15         fmt.Println("Tomorrow.")16     case today+2:17         fmt.Println("In two days.")18     default:19         fmt.Println("Too far away.")20     }21 }

When's Saturday?Too far away. Switch没有条件语句等同于Switch true. 这样的结构可以更清晰的表达一个长的if then else 链式语句 。

package mainimport (    "fmt"    "time")func main() {    t := time.Now()    switch {    case t.Hour() < 12:        fmt.Println("Good morning!")    case t.Hour() < 17:        fmt.Println("Good afternoon.")    default:        fmt.Println("Good evening.")    }}

Good evening.