Go中的switch fallthrough

 

 

• Go基础

switch sExpr {
case expr1:
    some instructions
case expr2: some other instructions case expr3: some other instructions default: other code } 

sExpr和expr1、expr2、expr3的类型必须一致。Go的switch非常灵活，表达式不必是常量或整数，执行的过程从上至下，直到找到匹配项；而如果switch没有表达式，它会匹配true。 Go里面switch默认相当于每个case最后带有break，匹配成功后不会自动向下执行其他case，而是跳出整个switch, 但是可以使用fallthrough强制执行后面的case代码。

http://play.golang.org/p/LySjbnt53q

package main

import "fmt"

func main() { switch { case false: fmt.Println("The integer was <= 4") fallthrough case true: fmt.Println("The integer was <= 5") fallthrough case false: fmt.Println("The integer was <= 6") fallthrough case true: fmt.Println("The integer was <= 7") case false: fmt.Println("The integer was <= 8") fallthrough default: fmt.Println("default case") } } 

运行结果：

The integer was <= 5

The integer was <= 6

The integer was <= 7

从本例可以看出：switch人第一个expr为true的case开始执行，如果case带有fallthrough，程序会继续执行下一条case,不会再判断下一条case的expr,如果之后的case都有fallthrough,default出会被执行。