A Tour of Go Exercise: Stringers

exercise-stringer.go

package main

import (
	"fmt"
	"strings"
	"strconv"
)

type IPAddr [4]byte

func (ip IPAddr) String() string {
	s := make([]string, len(ip))
	for i, val := range ip {
		s[i] = strconv.Itoa(int(val))
	}	
	return strings.Join(s, ".")
}

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)
	}
}

I'm using append instead of concat string

package main

import (
	"fmt"
	"strings"
	"strconv"
)

type IPAddr [4]byte

func (ip IPAddr) String() string {
	s := make([]string, len(ip))
	
	for _, v := range ip {
		s = append(s, strconv.Itoa(int(v)))
	} 
	
	return strings.Join(s, ".")
}

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)
	}
}

I think it'd be better to declare the slice s like make([]string, 0, len(ip)). Otherwise, the output would be like "....127.0.0.1" as the append will add the digit from index 4.