A Tour of Go: Exercise: Stringers, https://go-tour-jp.appspot.com/methods/18

exercise-stringer.go

package main

import "fmt"
import "strings"

type IPAddr [4]byte

// Add a "String() string" method to IPAddr.
func (ipaddr IPAddr) String() string {
	octets := make([]string, 4)
	for i, v := range ipaddr {
		octets[i] = fmt.Sprintf("%v", v)
	}
	return strings.Join(octets, ".")
}

func main() {
	hosts := map[string]IPAddr{
		"loopback":  {127, 0, 0, 1},
		"googleDNS": {8, 8, 8, 8},
	}
	for name, ip := range hosts {
		fmt.Printf("%v: %v\n", name, ip)
	}
}