Writing a toUpper function for unicode letters

From here http://blog.golang.org/slices (it's right before the Capacity section)

type path []byte

func (p path) ToUpper() {
    for i, b := range p {
        if 'a' <= b && b <= 'z' {
            p[i] = b + 'A' - 'a'
        }
    }
}

func main() {
    pathName := path("/usr/bin/tso")
    pathName.ToUpper()
    string1 := string(pathName)
    fmt.Printf("%s\n", string1)
}

Was reading on slices and stuff in golang. This is a function to convert ascii characters. How would you go about turning this function to handle unicode as well?

You should use rune when you use unicode. The unicode package in golang has a toUpper function.

package main

import (
    "unicode"
    "fmt"
)

type path []rune

func (p path) ToUpper() {
    for i, b := range p {
        p[i] = unicode.ToUpper(b)
    }
}

func main() {
    pathName := path("/usr/bin/tso")
    pathName.ToUpper()
    string1 := string(pathName)
    fmt.Printf("%s\n", string1)
}

in the playground: example