Does a break statement break from a switch/select?

Question

I know that switch/select statements break automatically after every case. I am wondering, in the following code:

for {
    switch          


        

Answer 1

this should explain it.

for{
    x := 1
    switch {
    case x >0:
        fmt.Println("sjus")
    case x == 1:
        fmt.Println("GFVjk")
    default:
        fmt.Println("daslkjh")
    }
}
}

Runs forever

for{
    x := 1
    switch {
    case x >0:
        fmt.Println("sjus")
        break
    case x == 1:
        fmt.Println("GFVjk")
    default:
        fmt.Println("daslkjh")
    }
}
}

Again, runs forever

BUT

package main

import "fmt"

func main() {
d:
for{
x := 1
    switch {
    case x >0:
        fmt.Println("sjus")
        break d
    case x == 1:
        fmt.Println("GFVjk")
    default:
        fmt.Println("daslkjh")
    }
}
}

will print sjus ... clear ?

http://play.golang.org/p/GOvnfI67ih

Answer 2

Just from a switch block. There's plenty of examples in Golang own code you can examine (compare inner break with outer break).

Answer 3

It only exits the switch block.

Answer 4

A hopefully illustrative example:

loop:
for {
        switch expr {
        case foo:
                if condA {
                        doA()
                        break // like 'goto A'
                }

                if condB {
                        doB()
                        break loop // like 'goto B'                        
                }

                doC()
        case bar:
                // ...
        }
A:
        doX()
        // ...
}

B:
doY()
// ....

Answer 5

This question might be too old already but I still think label makes our code become harder to read. Instead of breaking the for inside select, just set a flag for the loop and handle it inside select-case before invoking break. For example:

loop := true
for loop {
    select {
    case <-msg:
        // do your task here
    case <-ctx.Done():
        loop = false
        break
    }
}

Answer 6

Break statements, The Go Programming Language Specification.

A "break" statement terminates execution of the innermost "for", "switch" or "select" statement.

BreakStmt = "break" [ Label ] .

If there is a label, it must be that of an enclosing "for", "switch" or "select" statement, and that is the one whose execution terminates (§For statements, §Switch statements, §Select statements).

L:
  for i < n {
      switch i {
      case 5:
          break L
      }
  }

Therefore, the break statement in your example terminates the switch statement, the "innermost" statement.