package main import ( "flag" "fmt" "log" "strconv" ) func main() { isDecode := flag.Bool("d", false, "decode") flag.Parse() str := flag.Arg(0) if *isDecode { n, err := strconv.ParseUint(str, 36, 64) if err != nil { log.Fatal(err) } fmt.Println(str, n) } else { n, err := strconv.ParseUint(str, 10, 64) if err != nil { log.Fatal(err) } out := strconv.FormatUint(n, 36) fmt.Println(str, out) } }