http://go-tour-zh.appspot.com/methods/7

exercise-stringer-work.go

package main

import (
	"fmt"
	"strings"
)

type IPAddr [4]byte

// TODO: Add a "String() string" method to IPAddr.
func (ipAddr IPAddr) String()string {
	var ipStr string
	for i := 0; i < len(ipAddr) ; i++ {
		ip := fmt.Sprintf("%d", ipAddr[i])
		ipStr += ip + "."
	}
	ipStr = strings.Trim(ipStr, ".")
	return ipStr
}

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