Golang用特殊字符截断字符串而不会破坏数据

Question

I am trying to write a function to truncate strings with special characters in golang. One example is below

"H㐀〾▓朗퐭텟şüöžåйкл¤"

However I am doing it based on the number of characters allowed and cutting it in the middle. This results in data getting corrupted.

The result comes out like

H㐀〾▓朗퐭텟şüöžå�...

The � should not be there. How do we detect these special characters and split it based on the length of these characters?

package main

import (
    "fmt"
    "regexp"
)

var reNameBlacklist = regexp.MustCompile(`(&|>|<|\/|:|
|)*`)
var maxFileNameLength = 30

// SanitizeName sanitizes user names in an email
func SanitizeName(name string, limit int) string {

    result := name
    reNameBlacklist.ReplaceAllString(result, "")
    if len(result) > limit {
        result = result[:limit] + "..."
    }
    return result
}



func main() {
  str := "H㐀〾▓朗퐭텟şüöžåйкл¤"
    fmt.Println(str)

    strsan := SanitizeName(str, maxFileNameLength)
    fmt.Println(strsan)

}

Answer 1

Slicing strings treats them as their underlying byte array; the slice operator operates on indexes of bytes, not of runes (which can be multiple bytes each). However, range over a string iterates on runes - but the index returned is of bytes. This makes it fairly straightforward to do what you're looking for (full playground example here):

func SanitizeName(name string, limit int) string {
    reNameBlacklist.ReplaceAllString(name, "")
    result := name
    chars := 0
    for i := range name {
        if chars >= limit {
            result = name[:i]
            break
        }
        chars++
    }
    return result
}

This is explained in further detail on the Go blog