A Tour of Go - Methods and Interfaces - Exercise: rot13Reader (23/26)

exercise-rot-reader.go

package main

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

type rot13Reader struct {
	r io.Reader
}

func Rot13(b byte) byte {
	if ((b < 'm' && b >= 'a' ) || (b < 'M' && b >= 'A')) {
		b += 13 
	} else if ((b > 'm' && b <= 'z') || ( b > 'M' && b <= 'Z')) {
		b -= 13
	}
	return b
}

func (rot rot13Reader) Read(p []byte) (n int, err error) {
	n, err = rot.r.Read(p)
	for i:=0;i<len(p);i++ {
		p[i] = Rot13(p[i])
	}
	return n, err
}

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