A Tour of Go - Exercise: rot13Reader

Exercise-rot13Reader.go

package main

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

type rot13Reader struct {
	r io.Reader
}

func (reader rot13Reader) Read (b []byte) (int, error) {
	n, e := reader.r.Read(b)
	for i, v := range(b) {
		if v >= 'A' {
			if v < 'A' + 26 {
				b[i] = 'A' + (v - 'A' + 13) % 26
			} else if v < 'a' + 26 {
				b[i] = 'a' + (v - 'a' + 13) % 26
			}
		}
	}
	return n, e
}

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