switch.md

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:

package main

import (
	"fmt"
)

func checkSwitch(val int) {
	switch val {
	case 0:
	case 1:
		fmt.Println("The value is: ", val)
	}
}
func main() {
	checkSwitch(0)
	checkSwitch(1)
}

The output is:

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:

func checkSwitch(val int) {
	switch val {
	case 0:
		fallthrough
	case 1:
		fmt.Println("The value is: ", val)
	}
}

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

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

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.:

package main

import (
	"fmt"
)

func checkSwitch(val int) {
	switch {
	case val < 0:
		fmt.Println("The value is less than zero.")
	case val == 0:
		fmt.Println("The value is qual to zero.")
	case val > 0:
		fmt.Println("The value is more than zero.")
	}
}
func main() {
	checkSwitch(-1)
	checkSwitch(0)
	checkSwitch(1)
}

The output is:

The value is less than zero.
The value is qual to zero.
The value is more than zero.