A Tour of Go Exercise: rot13Reader

exercise-rot-reader.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)
	if err != nil {
		return n, err
	}
	for i := range b {
		switch {
		case (b[i] >= 'A' && b[i] < 'N'), (b[i] >='a' && b[i] < 'n'): b[i] += 13
		case (b[i] > 'M' && b[i] <= 'Z'), (b[i] > 'm' && b[i] <= 'z'): b[i] -= 13
		}
	}
	return n, err
}

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