Golang break/continue label

break用来结束最里面的for/select/switch的语句，如果这里有标签，那么它必须在for/select/switch的正上面。

http://localhost:6060/ref/spec#Break_statements

这也就是说，假如你有类似如下的代码：

    for i = 0; i < n; i++ {
        for j = 0; j < m; j++ {
            switch a[i][j] {
            case nil:
                state = Error
                break OuterLoop
            case item:
                state = Found
                break
            }
        }
    }

在switch里面使用break，那只是结束switch的语句，并不会跳出for循环。如果想跳出for循环，改为如下：

OuterLoop:
    for i = 0; i < n; i++ {
        for j = 0; j < m; j++ {
            switch a[i][j] {
            case nil:
                state = Error
                break OuterLoop
            case item:
                state = Found
                break OuterLoop
            }
        }
    }

另， continue 也可以配合label，与break对比如下：

package main

import (
    "fmt"
)

func main() {
    FirstNames := []string{"aaa", "bbb", "ccc"}
    LastNames := []string{"111", "222", "333"}

Loop:
    for _, firstName := range FirstNames {
        for _, lastName := range LastNames {
            fmt.Printf("Name: %s %s\n", firstName, lastName)

            if firstName == "bbb" && lastName == "111" {
                break Loop
            }
        }
    }
    println("Over.")
}

输出：

Name: aaa 111
Name: aaa 222
Name: aaa 333
Name: bbb 111
Over.

continue label

func main() {
    FirstNames := []string{"aaa", "bbb", "ccc"}
    LastNames := []string{"111", "222", "333"}

Loop:
    for _, firstName := range FirstNames {
        for _, lastName := range LastNames {
            fmt.Printf("Name: %s %s\n", firstName, lastName)

            if firstName == "bbb" && lastName == "111" {
                continue Loop
            }
        }
    }
    println("Over.")
}

输出：

Name: aaa 111
Name: aaa 222
Name: aaa 333
Name: bbb 111
Name: ccc 111
Name: ccc 222
Name: ccc 333
Over.