Read unicode characters with bufio scanner in Go

Question

I'm trying to read a plain text file that contains names like this: "CASTAÑEDA"

The code is basically like this:

file, err := os.Open("C:/Files/file.txt")
defer file.Close()
if err != nil {
    log.Fatal(err)
}
scanner := bufio.NewScanner(file)
for scanner.Scan() {
    fmt.Println(scanner.Text())
}

Then, when "CASTAÑEDA" is read it prints "CASTA�EDA"

There's any way to handle that characters when reading with bufio?

Thanks.

Answer 1

Your file is, most propably, non UTF-8. Because of that (go expects all strings to be UTF-8) your console output looks mangled. I would advise usage of the packages golang.org/x/text/encoding/charmap and golang.org/x/text/transform in your case, to convert the file's data to UTF-8. As I might presume, looking at your file path, you are on Windows. So your character encoding might be Windows1252 (if you have edited it e.g. with notepad.exe).

Try something like this:

package main

import (
    "bufio"
    "fmt"
    "log"
    "os"

    "golang.org/x/text/encoding/charmap"
    "golang.org/x/text/transform"
)

func main() {
    file, err := os.Open("C:/temp/file.txt")
    defer file.Close()
    if err != nil {
        log.Fatal(err)
    }

    dec := transform.NewReader(file, charmap.Windows1252.NewDecoder()) <- insert your enconding here

    scanner := bufio.NewScanner(dec)
    for scanner.Scan() {
        fmt.Println(scanner.Text())
    }
}

You can find more encodings in the package golang.org/x/text/encoding/charmap, that you can insert into my example to your liking.

Answer 2

The issue you're encountering is that your input is likely not UTF-8 (which is what bufio and most of the Go language/stdlib expect). Instead, your input probably uses some extended-ASCII codepage, which is why the unaccented characters are passing through cleanly (UTF-8 is also a superset of 7-bit ASCII), but that the 'Ñ' is not passed through intact.

In this situation, the bit-representation of the accented character is not valid UTF-8, so the unicode replacement character (U+FFFD) is being produced. You've got a few options:

1. Convert your input files to UTF-8 before passing them to Go. There are many utilities that can do this, and editors often have this feature.
2. Try using golang.org/x/text/encoding/charmap together with NewReader from golang.org/x/text/transform to transform your input to UTF-8. Pass the resulting Reader to bufio.NewScanner
3. Change the line in the loop to os.Stdout.Write(scanner.Bytes()); fmt.Println(); This might avoid the bytes being interpreted as UTF-8 beyond newline splitting. Writing the bytes directly to os.Stdout will further avoid any (mis)interpretation of the contents.