name := "我是胡八一"
fmt.Println("name[:4] = ",name[:4])

name[:4] = 我"htmlcode">

nameRune := []rune(name)
fmt.Println("string(nameRune[:4]) = ",string(nameRune[:4]))


运行结果：
string(nameRune[:4]) =  我是胡八
好了弄懂了原理我们来写一个完整的Golang中文字符串截取函数


func SubString(str string, begin, length int) string {
  fmt.Println("Substring =", str)
  rs := []rune(str)
  lth := len(rs)
  fmt.Printf("begin=%d, end=%d, lth=%d\n", begin, length, lth)
  if begin < 0 {
    begin = 0
  }
  if begin >= lth {
    begin = lth
  }
  end := begin + length

  if end > lth {
    end = lth
  }
  fmt.Printf("begin=%d, end=%d, lth=%d\n", begin, length, lth)
  return string(rs[begin:end])
}


实现Golang中文字符串截取函数很简单利用golang原理语句就可实现