Code for grid view sorting by clicking on the image button which is kept beside the column name in the same column

an empty aspx page

in source................

form id="form1" runat="server">
div
asp:Label ID="Label1" runat="server" Font-Bold="True" Font-Size="X-Large" Style="z-index: 100;
left: 187px; position: absolute; top: 30px" Text="Sample Sortable GridView"
asp:Label
asp:GridView ID="gvHours" runat="server" AllowSorting="True" AutoGenerateColumns="False"
CellPadding="4" ForeColor="#333333" GridLines="None" OnRowCreated="gvHours_RowCreated"
OnSorting="gvHours_Sorting" Style="z-index: 102; left: 65px; position: absolute;
top: 84px" Width="513px"
FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White"
RowStyle BackColor="#EFF3FB"
Columns
asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name"
asp:BoundField DataField="Hours" HeaderText="Hours" SortExpression="Hours"
ItemStyle HorizontalAlign="Center"
asp:BoundField
asp:BoundField DataField="Date" DataFormatString="{0:d}" HeaderText="Date" SortExpression="Date"
ItemStyle HorizontalAlign="Center"
asp:BoundField
Columns
PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center"
SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333"
HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White"
EditRowStyle BackColor="#2461BF"
AlternatingRowStyle BackColor="White"
asp:GridView

div
form


Note: Please keep all the above source code in the their respective formats

in code .cs file/////////////////


using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
HoursDAL hoursDAL = new HoursDAL();
ArrayList hourList = hoursDAL.GetHours();
ViewState["HourList"] = hourList;
gvHours.DataSource = hourList;
gvHours.DataBind();
}

private int GetSortColumnIndex()
{
// Iterate through the Columns collection to determine the index
// of the column being sorted.
foreach (DataControlField field in gvHours.Columns)
{
if (field.SortExpression == (string)ViewState["SortExpression"])
{
return gvHours.Columns.IndexOf(field);
}
}
return -1;
}

// This is a helper method used to add a sort direction
// image to the header of the column being sorted.
private void AddSortImage(int columnIndex, GridViewRow headerRow)
{
// Create the sorting image based on the sort direction.
Image sortImage = new Image();
if (GridViewSortDirection == SortDirection.Ascending)
{
sortImage.ImageUrl = "~/images/uparrow.gif";
sortImage.AlternateText = "Ascending Order";
}
else
{
sortImage.ImageUrl = "~/images/downarrow.gif";
sortImage.AlternateText = "Descending Order";
}
// Add the image to the appropriate header cell.
headerRow.Cells[columnIndex].Controls.Add(sortImage);
}


private SortDirection GridViewSortDirection
{
get
{
if (ViewState["sortDirection"] == null)
ViewState["sortDirection"] = SortDirection.Ascending;
return (SortDirection)ViewState["sortDirection"];
}
set { ViewState["sortDirection"] = value; }
}

private void SortGridView(string sortExpression, string direction)
{
ArrayList hourList = (ArrayList)ViewState["HourList"];
DataTable dt = new DataTable();
dt.Columns.Add("Name");
dt.Columns.Add("Hours");
dt.Columns["Hours"].DataType = System.Type.GetType("System.Double");
dt.Columns.Add("Date");
dt.Columns["Date"].DataType = System.Type.GetType("System.DateTime");

foreach (HoursBE hours in hourList)
{
DataRow dr = dt.NewRow();
dr["Name"] = hours.Name;
dr["Hours"] = hours.Hours;
dr["Date"] = hours.Date;
dt.Rows.Add(dr);
}

DataView dv = new DataView(dt);
dv.Sort = sortExpression + direction;
gvHours.DataSource = dv;
gvHours.DataBind();
}

private const string ASCENDING = " ASC";
private const string DESCENDING = " DESC";
protected void gvHours_Sorting(object sender, GridViewSortEventArgs e)
{
string sortExpression = e.SortExpression;
ViewState["SortExpression"] = sortExpression;

if (GridViewSortDirection == SortDirection.Ascending)
{
GridViewSortDirection = SortDirection.Descending;
SortGridView(sortExpression, DESCENDING);
}
else
{
GridViewSortDirection = SortDirection.Ascending;
SortGridView(sortExpression, ASCENDING);
}
}

protected void gvHours_RowCreated(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.Header)
{
int sortColumnIndex = GetSortColumnIndex();
if (sortColumnIndex != -1)
{
AddSortImage(sortColumnIndex, e.Row);
}
}
}
}