Go by Example: Switch

Switch statements express conditionals across many branches.

 
package main
 
import (
    "fmt"
    "time"
)
 
func main() {

Here’s a basic switch.

 
    i := 2
    fmt.Print("Write ", i, " as ")
    switch i {
    case 1:
        fmt.Println("one")
    case 2:
        fmt.Println("two")
    case 3:
        fmt.Println("three")
    }

You can use commas to separate multiple expressions in the same case statement. We use the optional default case in this example as well.

 
    switch time.Now().Weekday() {
    case time.Saturday, time.Sunday:
        fmt.Println("It's the weekend")
    default:
        fmt.Println("It's a weekday")
    }

switch without an expression is an alternate way to express if/else logic. Here we also show how the case expressions can be non-constants.

 
    t := time.Now()
    switch {
    case t.Hour() < 12:
        fmt.Println("It's before noon")
    default:
        fmt.Println("It's after noon")
    }

A type switch compares types instead of values. You can use this to discover the type of an interface value. In this example, the variable t will have the type corresponding to its clause.

 
    whatAmI := func(i interface{}) {
        switch t := i.(type) {
        case bool:
            fmt.Println("I'm a bool")
        case int:
            fmt.Println("I'm an int")
        default:
            fmt.Printf("Don't know type %T\n", t)
        }
    }
    whatAmI(true)
    whatAmI(1)
    whatAmI("hey")
}
 
$ go run switch.go 
Write 2 as two
It's a weekday
It's after noon
I'm a bool
I'm an int
Don't know type string

Next example: Arrays.

by Mark McGranaghan and Eli Bendersky | source | license