在标签之间删除它不会删除

Question

我已经询问如何删除标签之间的值，我得到了解决方案，我必须修改以满足我的需求，但现在问题是它不删除标签之间的值，我调试看到错误但没有发现错误。当我检查已创建的文件时，我仍然可以看到标签内的值。请帮帮我

在新按钮下复制文件

            XmlReadMode omode = oDataSet.ReadXml(PathSelection);
            for (int i = 0; i < oDataSet.Tables[2].Rows.Count; i++)
            {
                string comment = oDataSet.Tables["data"].Rows[i][2].ToString();

                string font = DeleteBetween(comment, "[Font]", "[/Font]");
                string datestamp = DeleteBetween(comment, "[DateStamp]", "[/DateStamp]");
                string commentVal = DeleteBetween(comment, "[Comment]", "[/Comment]");

                string[] row = new string[] 
                {
                    oDataSet.Tables["data"].Rows[i][0].ToString(),
                    oDataSet.Tables["data"].Rows[i][1].ToString(),
                    font, 
                    datestamp, 
                    commentVal
                };
                File.Copy(txtInputfile.Text, txtInputfile.Text.Replace("string-en.resx", "string-lan.resx"));
                Gridview_Output.Rows.Add(row);
           }

功能

     public string DeleteBetween(string STR, string FirstString, string LastString)
    {
        string regularExpressionPattern1 = @"(?:\" + FirstString + @")([^[]+)\[\/" + LastString;
        Regex regex = new Regex(regularExpressionPattern1, RegexOptions.Singleline);
        MatchCollection collection = regex.Matches(STR.ToString());
        var val = string.Empty;
        foreach (Match m in collection)
        {
            val = m.Groups[1].Value;
        }
        return val;
    }