rot 13 reader from exercise of the tour

rot13reader.go

package main

import (
	"io"
	"os"
	"strings"
)

type rot13Reader struct {
	r io.Reader
}

func (rot *rot13Reader) Read(b []byte) (int, error){
	n, err := rot.r.Read(b)
	for i:=0; i< n ; i++ {
		if (b[i] >= 97 && b[i] <= 122) {
			b[i] = b[i] + 13
			if b[i] > 122 {
				b[i] = b[i] % 122 + 96
			}
		} else if (b[i] >= 65 && b[i] <= 90) {
			b[i] = b[i] + 13
			if b[i] > 90 {
				b[i] = b[i] % 90 + 64
			}
		}
	}
	return n, err
}


func main() {
	s := strings.NewReader("Lbh penpxrq gur pbqr!")
	r := rot13Reader{s}
	io.Copy(os.Stdout, &r)
}