Isbn checkdigits

isbn.go

package main

import "fmt"
import "strings"
import "strconv"

func isbn10(s string) string {
  ss := strings.Split(s, "")
  sum := 0

  for i := 0; i < 9; i++ {
    n, _ := strconv.Atoi(ss[i])
    n = (10 - i) * n
    sum += n
  }

  r := 11 - (sum % 11)

  if (r == 10) {
    return "X"
  }

  t := strconv.Itoa(r)
  return t
}

func isbn13(s string) string {
  ss := strings.Split(s, "")
  sum := 0

  for i := 0; i < 12; i++ {
    n, _ := strconv.Atoi(ss[i])

    if (i % 2 != 0) {
      sum += n * 3
    } else {
      sum += n
    }
  }

  r := 10 - (sum % 10)

  if (r == 10) {
    return "0"
  }

  t := strconv.Itoa(r)
  return t
}

func main() {
  s := isbn10("061826941")
  t := isbn10("831312744")
  u := isbn10("830332744")

  fmt.Println(s)
  fmt.Println(t)
  fmt.Println(u)

  x := isbn13("978316148410")
  y := isbn13("978030640615")
  z := isbn13("978316148442")

  fmt.Println(x)
  fmt.Println(y)
  fmt.Println(z)
}