C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class testpage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
     protected void Page_PreInit(object sender, EventArgs e)
    {
        List<string> keys = Request.Form.AllKeys.Where(key => key.Contains("txtDynamic")).ToList();
        int i = 1;
        foreach (string key in keys)
        {
            this.CreateTextBox("txtDynamic" + i);
            i++;
        }
    }

    protected void AddTextBox(object sender, EventArgs e)
    {
        int index = pnlTextBoxes.Controls.OfType<TextBox>().ToList().Count + 1;
        this.CreateTextBox("txtDynamic" + index);
    }

    private void CreateTextBox(string id)
    {
        TextBox txt = new TextBox();
        txt.ID = id;
        pnlTextBoxes.Controls.Add(txt);

        Literal lt = new Literal();
        lt.Text = "<br />";
        pnlTextBoxes.Controls.Add(lt);
    }

    protected void GetTextBoxValues(object sender, EventArgs e)
    {
        string message = "";
        foreach (TextBox textBox in pnlTextBoxes.Controls.OfType<TextBox>())
        {
            message += textBox.ID + ": " + textBox.Text + "\\n";
        }
        ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('" + message + "');", true);
    }
}

public static void GZSerialize<T>(T instance, string baseFolderPath, string filename1)
{
    dcs = new DataContractSerializer(typeof(T));

    string fullfilename = baseFolderPath + "/" + filename1 + (usegzip + @".gz";

    //if (File.Exists(fullfilename ))
    //{
        //File.Delete(fullfilename );
    //}

    string fullfilename = @"C:\Users\Win-Ten\Desktop\fordata\test4.gz";

    // fails here
    using (FileStream compressedFileStream = new FileStream(fullfilename, FileMode.OpenOrCreate, FileAccess.Write))
    {
        using (GZipStream compressionStream =
               new GZipStream(compressedFileStream, CompressionLevel.Optimal, true))
        {
            dcs.WriteObject(compressionStream, instance);
            compressionStream.Close();
        }
    }
}