有一段不明白的代码，麻烦帮我看一下

悬赏园豆：5 [已关闭问题]

    public class Excel
    {
        /// <summary>
        /// 将指定excel文件中读取第一张工作表的名称
        /// </summary>
        /// <param name="filepath">Excel的文件路径</param>
        /// <returns>第一张工作表的名称</returns>
        ///

        public static string GetSheetName(string filePath)
        {
            string sheetName = "";

            FileStream tmpStream = File.OpenRead(filePath);
            byte[] fileByte = new byte[tmpStream.Length];
            tmpStream.Read(fileByte, 0, fileByte.Length);
            tmpStream.Close();

//下面这段，定义这个tmByte数组的作用是什么？为什么这样定义

            byte[] tmByte = new byte[]{Convert.ToByte(11),Convert.ToByte(0),Convert.ToByte(0),Convert.ToByte(0),Convert.ToByte(0)
            ,Convert.ToByte(0),Convert.ToByte(0),Convert.ToByte(0),Convert.ToByte(11),Convert.ToByte(0),Convert.ToByte(30),Convert.ToByte(16)
            ,Convert.ToByte(0),Convert.ToByte(0)};

            int index = GetSheetIndex(fileByte, tmByte);
            if (index > -1)
            {
                index += 16 + 12;　　//这里也不明白+１６+１２什么意思
                System.Collections.ArrayList sheetNameList = new System.Collections.ArrayList();

                for(int i=index;i<fileByte.Length-1;i++)
                {
                    byte temp=fileByte[i];
                    if(temp!=Convert.ToByte(0))
                        sheetNameList.Add(temp);
                    else
                        break;
                }
                byte[] sheetNameByte=new byte [sheetNameList.Count];
                for(int i=0;i<sheetNameList.Count;i++)
                    sheetNameByte[i]=Convert.ToByte(sheetNameList[i]);
                sheetName=System.Text.Encoding.Default.GetString(sheetNameByte);
            }
            return sheetName;
        }

        /// <summary>
        /// 只供方法GetSheetName()使用
        /// </summary>
        ///
        private static int GetSheetIndex(byte[] findTagrget, byte[] findItem)
        {
            int index = -1;
            int findItemLength = findItem.Length;
            if (findItemLength < 1)
                return -1;
            int findTargetLength = findTagrget.Length;
            if ((findTargetLength - 1) < findItemLength)
                return -1;
            for (int i = findTargetLength - findItemLength - 1; i > -1; i--)
            {
                System.Collections.ArrayList tmpList = new System.Collections.ArrayList();
                int find = 0;
                for (int j = 0; j < findItemLength; j++)
                {
                    if (findTagrget[i + j] == findItem[j])
                        find += 1;
                }
                if (find == findItemLength)
                {
                    index = i;
                    break;
                }
            }
            return index;
        }

        /// <summary>
        /// 将指定html字符串的数据转换成datatable对象——根据“<tr><td>”等特殊字符进行处理
        /// </summary>
        /// <param name="tmphtml">Html字符串</param>
        ///
        public static DataTable GetDataTableFromString(string tmphtml)
        {
            string tmpStr = tmphtml;
            DataTable dt = new DataTable();
            //先处理一下这个字符串，删除第一个<tr>之前和最后一个</tr>之后的部分
            int index = tmpStr.IndexOf("<tr");
            if (index > -1)
                tmpStr = tmpStr.Substring(index);
            else
                return dt;

            index = tmpStr.LastIndexOf("</td>");
            if (index > -1)
                tmpStr = tmpStr.Substring(0, index + 5);
            else
                return dt;

bool existsSparator = false;
char separator = Convert.ToChar("^");

            //如果原字符串中包含分隔符"^"则先把它替换掉
            if (tmpStr.IndexOf(separator.ToString()) > -1)
            {
                existsSparator = true;
                tmpStr = tmpStr.Replace("^", "^$&^");
            }
            //先根据"</tr>"分拆
            string[] tmpRow = tmpStr.Replace("</tr>", "^").Split(separator);

            for (int i = 0; i<tmpRow.Length - 1; i++)
            {
                DataRow newRow = dt.NewRow();

                string tmpStri = tmpRow[i];
                if (tmpStri.IndexOf("<tr") > -1)
                {
                    tmpStri = tmpStri.Substring(tmpStri.IndexOf("<tr"));
                    if (tmpStri.IndexOf("display:none") < 0 || tmpStri.IndexOf("display:none") > tmpStri.IndexOf(">"))
                    {
                        tmpStri = tmpStri.Replace("</td>", "^");
                        string[] tmpField = tmpStri.Split(separator);

                        for (int j = 0; j < tmpField.Length - 1; j++)
                        {
                            tmpField[j] = RemoveString(tmpField[j], "<font>"); ;
                            index = tmpField[j].LastIndexOf(">") + 1;
                            if (index>0)
                            {
                                string field = tmpField[j].Substring(index, tmpField[j].Length - index);
                                if (existsSparator)
                                    field = field.Replace("^$&^", "^");
                                if (i == 0)
                                {
                                    string tmpFieldName = field;
                                    int sn = 1;
                                    while (dt.Columns.Contains(tmpFieldName))
                                    {
                                        tmpFieldName = field + sn.ToString();
                                        sn += 1;
                                    }
                                    dt.Columns.Add(tmpFieldName);
                                }
                                else
                                {
                                    newRow[j] = field;
                                }
                            }//end of if(index>0)
                        }
                    }
                    if (i > 0)
                        dt.Rows.Add(newRow);
                }
            }
            dt.AcceptChanges();
            return dt;
        }

        /// <summary>
        /// 从指定的html字符串中剔除指定的对象
        /// </summary>
        /// <param name="tmpHtml">Html字符串</param>
        /// <param name="remove">需要剔除的对象——例如输入"<font>"则剔除"<font???????>"和"</font>>"</param>
        /// <retuns></retuns>
        ///
        public static string RemoveString(string tmpHtml, string remove)
        {
            tmpHtml = tmpHtml.Replace(remove.Replace("<", "</"), "");
            tmpHtml = RemoveStringHead(tmpHtml, remove); ;
            return tmpHtml;
        }

        /// <summary>
        /// 只供方法RemoveString()使用
        /// </summary>
        /// <param name="tmpHtml"></param>
        /// <param name="remove"></param>
        /// <returns></returns>
        private static string RemoveStringHead(string tmpHtml, string remove)
        {

            //为了方便注释，假设输入参数remove="<font>"
            if (remove.Length < 1)
                return tmpHtml; //参数remove为空：不处理返回
            if((remove.Substring(0,1)!="<"||(remove.Substring(remove.Length-1)!=">")))
                return tmpHtml; //参数remove不是<????>:不处理返回
            int indexs=tmpHtml.IndexOf(remove.Replace(">","")); //查找"<font"的位置
            int indexe=-1;
            if(indexs>-1)
            {
                string tmpRight=tmpHtml.Substring(indexs,tmpHtml.Length-indexs);
                indexe=tmpRight.IndexOf(">");
                if(indexe>-1)
                    tmpHtml=tmpHtml.Substring(0,indexs)+tmpHtml.Substring(indexs+ indexe+1);
                if(tmpHtml.IndexOf(remove.Replace(">",""))>-1)
                    tmpHtml=RemoveStringHead(tmpHtml,remove);
            }
            return tmpHtml;
        }