C#按照指定長度分割中英文字符串

private void GetSubStringList(string str,int length,List<string> list)
{
     string content = "";
     string nextSub = "";
     byte[] content    = System.text.Encoding.Unicode.GetBytes(str);
     if (length>content.Length)
    {
        contentSub = str;
        if (contentSub != "")
        {
            list.Add(contentSub);
        }
    }
    else
    {
        int index = 0;
        for (int i = 0;i<length*2 &&i<str.Length*2;i++   )
        {
            if ( i%2 != 0 && content[i] == 0)
            {
                index++;
            }
        }
        index += (int)Math.floor((double)(length - index)/2f); //漢字數*2+字符數=length
        if ( index >str.Length)
        {
            index = str.Length;
        }
        contentSub = str.Substring(0,index);
        nextSub = str.Substring(index);
        list.Add(contentSub);
        
        GetSubStringList(nextSub,length,list);
    }
}