How to pass GridView SortExpression to GridViewPageIndexChanging Event in ASP.Net

protected void Sorting(object sender, GridViewSortEventArgs e)
        {
            string[] SortOrder = ViewState["SortExpr"].ToString().Split(' ');
            if (SortOrder[0] == e.SortExpression)
            {
                if (SortOrder[1] == "ASC")
                {
                    ViewState["SortExpr"] = e.SortExpression + " " + "DESC";
                }
                else
                {
                    ViewState["SortExpr"] = e.SortExpression + " " + "ASC";
                }
            }
            else
            {
                ViewState["SortExpr"] = e.SortExpression + " " + "ASC";
            }
            GridVwPagingSorting.DataSource = Getdata();
            GridVwPagingSorting.DataBind();     

protected void PageIndexChanging(object sender, GridViewPageEventArgs e)
        {

protected void Page_Load(object sender, EventArgs e);

GridVwPagingSorting.PageIndex = e.NewPageIndex; DataView dvEmployee = Getdata(); GridVwPagingSorting.DataSource = dvEmployee; GridVwPagingSorting.DataBind(); }

 how to pass ??