Tour of Go 2.0

Switch evaluation order

Switch cases are evaluated top to bottom, and evaluation stops the moment a case matches. Cases that come after a match are never evaluated.

This matters when your cases have side effects. For example:

switch i {
case 0:
case f():
}

If i == 0, the first case matches immediately — f() is never called. Keep that in mind when putting function calls in your cases.

main.go ▶ Run in Playground 
package main

import (
	"fmt"
	"time"
)

func main() {
	fmt.Println("When's Saturday?")
	today := time.Now().Weekday()
	switch time.Saturday {
	case today + 0:
		fmt.Println("Today.")
	case today + 1:
		fmt.Println("Tomorrow.")
	case today + 2:
		fmt.Println("In two days.")
	default:
		fmt.Println("Too far away.")
	}
}