How to access label control placed in asp datalist footer template using c#

Hi... using datalist im adding marks of 6 subjects to a database table on button click. i want to display total of all marks entered in textbox placed inside item template of datalist on button click. I used label control in footer template of datalist, on that label i want to display total marks. im getting error as "Object reference not set to an instance of an object".

My code is :

<%@ Page Title="" Language="C#" MasterPageFile="~/SSLC_Board/SSLCMaster.Master" AutoEventWireup="true" CodeBehind="ManageMarks.aspx.cs" Inherits="PUseatAllot.SSLC_Board.ManageMarks" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">

<tr>

<strong style="font-size: medium">MANAGE MARKS</strong></td>

</tr>

<tr>

<td>

</tr>

<tr>

<td>

 </td>

</tr>

<tr>

<tr>

<td>

School Name</td>

<td>

<asp:DropDownList ID="DDLschool" runat="server" Width="300px"

AutoPostBack="True"

onselectedindexchanged="DDLschool_SelectedIndexChanged">

</asp:DropDownList>

</td>

<td>

 </td>

</tr>

</table>

</td>

</tr>

<tr>

<td>

</td>

</tr>

<tr>

<td>

<tr>

<asp:Label ID="lblMsg" runat="server" Font-Bold="True"

style=" background-color:#FFFFCC; color:Red" Width="200px"></asp:Label>

<asp:GridView ID="GVstudents" runat="server" BackColor="White"

BorderColor="#CC9966" BorderStyle="None" BorderWidth="1px" CellPadding="4"

AutoGenerateColumns="False" Width="138px">

<asp:TemplateField HeaderText="Student Name">

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</EditItemTemplate>

<asp:LinkButton ID="LBstudent" runat="server"

CommandArgument='<%# Eval("StudentId") %>' onclick="LBstudent_Click"

Text='<%# Eval("StudentName") %>'></asp:LinkButton>

</ItemTemplate>

</asp:TemplateField>

</Columns>

</asp:GridView>

</td>

<asp:Panel ID="Panel2" runat="server">

<tr>

<td>

<strong style="font-size: large">Subjects</strong></td>

<td>

 </td>

</tr>

<tr>

<td>

</td>

<td>

 </td>

</tr>

<tr>

<td>

<asp:CheckBoxList ID="CBLsubjects" runat="server">

</asp:CheckBoxList>

<asp:Label ID="lblMsg2" runat="server" Font-Bold="True" ForeColor="Red"></asp:Label>

<br />

</td>

<td>

 </td>

</tr>

<tr>

<td>

<asp:Button ID="btnAddMarks" runat="server" Text="Add Marks"

onclick="btnAddMarks_Click" />

</td>

<td>

 </td>

</tr>

</table>

</asp:Panel>

</td>

</tr>

<tr>

 </td>

<asp:Panel ID="Panel1" runat="server" BorderColor="#DA6BB6" BorderWidth="2px">

<tr>

<asp:DataList ID="DLmarks" runat="server" BackColor="White"

BorderColor="#CC9966" BorderStyle="None" BorderWidth="1px" CellPadding="4"

GridLines="Both" Width="350px" >

TOTAL MARKS     :       

<asp:Label ID="lblTotalMarks" runat="server" Text=""></asp:Label>

</FooterTemplate>

MARKS BOARD

</HeaderTemplate>

<tr>

<asp:Label ID="lblSubjectId" runat="server" Text='<%# Eval("SubjectId") %>'

Visible="False"></asp:Label>

&nbsp&nbsp&nbsp

<asp:Label ID="lblSubjectName" runat="server" Text='<%# Eval("SubjectName") %>'></asp:Label>

</td>

<asp:TextBox ID="txtMarks" runat="server"></asp:TextBox>

</td>

<td>

</td>

</tr>

</table>

</ItemTemplate>

</asp:DataList>

</td>

</tr>

<tr>

 </td>

</tr>

<tr>

<asp:ImageButton ID="ImgBtnSubmit" runat="server" Height="33px"

ImageUrl="~/IMG/submit1.jpg" onclick="ImgBtnSubmit_Click" />

</td>

</tr>

</table>

</asp:Panel>

</td>

</tr>

</table>

</td>

</tr>

<tr>

<td>

 </td>

</tr>

</table>

</asp:Content>

aspx.cs code:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

namespace PUseatAllot.SSLC_Board

{

public partial class ManageMarks : System.Web.UI.Page

{

BL b = new BL();

static int Mid;

static int StudId;

static Label label4;

//static string[] StudId2;

protected void Page_Load(object sender, EventArgs e)

{

if (!this.IsPostBack)

{

//label4 = DLmarks.Controls[DLmarks.Controls.Count - 1].FindControl("lblTotalMarks") as Label;

Panel2.Visible = false;

Panel1.Visible = false;

DDLschool.DataSource = b.School_GetAll();

DDLschool.DataTextField = "SchoolName";

DDLschool.DataValueField = "SchoolId";

DDLschool.DataBind();

DDLschool.Items.Insert(0, "- select -");

}

protected void DDLschool_SelectedIndexChanged(object sender, EventArgs e)

{

if (DDLschool.SelectedIndex != 0)

{

DataTable t_stud = b.Student_Get_SchlId(int.Parse(DDLschool.SelectedItem.Value));

if (t_stud.Rows.Count > 0)

{

GVstudents.EmptyDataText = "No Record.";

GVstudents.DataSource = t_stud;

GVstudents.DataBind();

}

else

{

lblMsg.Text = "-- No Record --";

}

protected void LBstudent_Click(object sender, EventArgs e)

{

StudId = int.Parse(((LinkButton)sender).CommandArgument);

Panel2.Visible = true;

//binding subjects to checkboxlist

DataTable t_sub = b.Subject_GetAll();

if (t_sub.Rows.Count > 0)

{

CBLsubjects.DataSource = t_sub;

CBLsubjects.DataTextField = "SubjectName";

CBLsubjects.DataValueField = "SubjectId";

CBLsubjects.DataBind();

}

else

{

lblMsg2.Text = "No Subjects. Please Add Subject details and then proceed.";

}

protected void btnAddMarks_Click(object sender, EventArgs e)

{

DataTable t_Marks = new DataTable();

t_Marks.Columns.Add("SubjectId",typeof(int));

t_Marks.Columns.Add("SubjectName",typeof(string));

string subId = null;

for (int i = 0; i < CBLsubjects.Items.Count; i++)

{

if (CBLsubjects.Items[i].Selected)

subId = subId+CBLsubjects.Items[i].Value+"_"+CBLsubjects.Items[i].Text + ",";

}

if (subId != null)

{

//creating dynamic data table and storing selected subject details

subId = subId.Substring(0, subId.Length - 1);

string [] StudId2 = subId.Split(',');

// checking where 6 subjects are selected or not

if (StudId2.Length == 6)

{

for (int i = 0; i < StudId2.Length; i++)

{

string[] v = StudId2[i].Split('_');

DataRow dt = t_Marks.NewRow();

dt["SubjectId"] = int.Parse(v[0]);

dt["SubjectName"] = v[1];

t_Marks.Rows.Add(dt);

}

//--------------------------------------------------------------

//binding selected subject details to datalist

Panel1.Visible = true;

DLmarks.DataSource = t_Marks;

DLmarks.DataBind();

//--------------------------------------------------------------

}

else

{

Response.Write("<script>alert('Please select 6 subjects.')</script>");

Panel1.Visible = false;

}

else

Response.Write("<script>alert('Please select subjects.')</script>");

}

static int totalMarks;

protected void ImgBtnSubmit_Click(object sender, ImageClickEventArgs e)

{

foreach (DataListItem item in DLmarks.Items)

{

Label lblSubId= (Label)item.FindControl("lblSubjectId");

Label lblSubName = (Label)item.FindControl("lblSubjectName");

TextBox txtMarks = (TextBox)item.FindControl("txtMarks");

Label LbTotalMarks = (Label)item.FindControl("lblTotalMarks");

if (b.Marks_Add(StudId, int.Parse(lblSubId.Text), int.Parse(txtMarks.Text)) == 1)

{

totalMarks += int.Parse(txtMarks.Text);

LbTotalMarks.Text = totalMarks.ToString();

Response.Write("<script>alert('Marks added successfully.')</script>");

}

else

Response.Write("<script>alert('ERROR in adding marks.')</script>");

//if (item.ItemType == ListItemType.Footer)

//{

// Label LbTotalMarks = (Label)item.FindControl("lblTotalMarks");

// LbTotalMarks.Text = totalMarks.ToString();

//}

}

// label4.Text = totalMarks.ToString();

}

//protected void DLmarks_ItemDataBound(object sender, DataListItemEventArgs e)

//{

// //when the item is a footer item (only happens once) put your global into a control

// if (e.Item.ItemType == ListItemType.Footer)

// {

// Label LbTotalMarks = (Label)e.Item.FindControl("lblTotalMarks");

// LbTotalMarks.Text = totalMarks.ToString();

// }

//}

}

Please help me......!

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How to access label control placed in asp datalist footer template using c#

Rashmi S

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