switch

Compared to other programming languages (such as C), Go‘s switch-case statement doesn’t need explicit “break“, and not have fall-though characteristic. Take the following code as an example: 

  1. package main
  3. import (
  4.     "fmt"
  5. )
  7. func checkSwitch(val int) {
  8.     switch val {
  9.     case 0:
  10.     case 1:
  11.         fmt.Println("The value is: ", val)
  12.     }
  13. }
  14. func main() {
  15.     checkSwitch(0)
  16.     checkSwitch(1)
  17. }

The output is: 

  1. The value is:  1

Your real intention is the “fmt.Println("The value is: ", val)“ will be executed when val is 0 or 1, but in fact, the statement only takes effect when val is 1. To fulfill your request, there are 2 methods:

(1) Use fallthrough: 

  1. func checkSwitch(val int) {
  2.     switch val {
  3.     case 0:
  4.         fallthrough
  5.     case 1:
  6.         fmt.Println("The value is: ", val)
  7.     }
  8. }

(2) Put 0 and 1 in the same case: 

  1. func checkSwitch(val int) {
  2.     switch val {
  3.     case 0, 1:
  4.         fmt.Println("The value is: ", val)
  5.     }
  6. }

switch can also be used as a better if-else, and you may find it may be more clearer and simpler than multiple if-else statements.E.g.: 

  1. package main
  3. import (
  4.     "fmt"
  5. )
  7. func checkSwitch(val int) {
  8.     switch {
  9.     case val < 0:
  10.         fmt.Println("The value is less than zero.")
  11.     case val == 0:
  12.         fmt.Println("The value is qual to zero.")
  13.     case val > 0:
  14.         fmt.Println("The value is more than zero.")
  15.     }
  16. }
  17. func main() {
  18.     checkSwitch(-1)
  19.     checkSwitch(0)
  20.     checkSwitch(1)
  21. }

The output is: 

  1. The value is less than zero.
  2. The value is qual to zero.
  3. The value is more than zero.