C#截取字符串的方法

#region 得到字符串的长度
    /// <summary>
    /// 得到字符串的长度
    /// </summary>
    /// <param name="strData"></param>
    /// <returns></returns>
    public static int GetStrLen(string strData)
    {
        System.Text.Encoding encoder5 = System.Text.Encoding.GetEncoding("GB2312");
        return encoder5.GetByteCount(strData);
    }
    #endregion

    #region 切割字符串
    /// <summary>
    /// 切割字符串
    /// </summary>
    /// <param name="s">需要切割的字符串</param>
    /// <param name="i">需要切割的字符串长度</param>
    /// <param name="smore">切割后字符串后面添加的字符串</param>
    /// <returns></returns>
    public static string SubStr(string s, int i, string smore)
    {
        int intResult = 0;
        int j = 0;
        string s1 = s;
        if (GetStrLen(s) > i)
        {
            foreach (char Char in s)
            {
                if (intResult < i)
                {
                    j++;
                    if ((int)Char > 127)
                        intResult = intResult + 2;
                    else
                        intResult++;
                }
                else
                    break;
            }
            s1 = s.Substring(0, j);
        }
        else
        {
            return s1;
        }
        string temp = s1 + smore;
        if (GetStrLen(s) <= GetStrLen(temp))//增加这一步的判断，避免刚好的字符被切掉
        {
            return s;
        }
        return temp;
    }
    #endregion