ASP.NET

public int PageIndex
    {

        get
        {
            if (Session["DGApplicationPageIndex"] != null)
            {
                return (int)Session["DGApplicationPageIndex"];
            }
            else
            {
                return 0;
            }
        }
        set
        {
            if (value != -1)
            {
                Session["DGApplicationPageIndex"] = value;
            }
            else
            {
                Session["DGApplicationPageIndex"] = null;
            }

        }

    }

protected void DGApplication_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        DoSearch(TextBox1.Text);
        DGApplication.PageIndex = e.NewPageIndex;
        PageIndex = DGApplication.PageIndex;
    }

protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            DoSearch("-1");
        }
        DGApplication.PageIndex = PageIndex;
        PageIndex = -1;

    }