Writing a toUpper function for unicode letters

Question

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?

Answer 1

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