网络上找到了以下代码 然后发现总会丢失一些字符

string MID(string str, string str1, string str2)
            {
                int i1 = str.IndexOf(str1);
                int i2 = -1;
                string strok = "";
                if (i1 != -1)
                {
                    i2 = str.IndexOf(str2, i1);
                }
                if (i2 != -1)
                {
                    strok = str.Substring(i1 + 12, i2 - i1 - 12);
                }
                return strok;
            }

之后还是自己写了一段很实用的取出文本中间代码

    /// <summary>
    /// 截取字符串值
    /// </summary>
    /// <param name="sourse"></param>
    /// <param name="startstr"></param>
    /// <param name="endstr"></param>
    /// <returns></returns>
    string MidStrEx(string sourse, string startstr, string endstr)
    {
        string result = string.Empty;
        int startindex, endindex;
        try
        {
            startindex = sourse.IndexOf(startstr);
            if (startindex == -1)
                return result;
            string tmpstr = sourse.Substring(startindex + startstr.Length);
            endindex = tmpstr.IndexOf(endstr);
            if (endindex == -1)
                return result;
            result = tmpstr.Remove(endindex);
        }
        catch (Exception ex)
        {
        }
        return result;
    }