ERROR:-System.NullReferenceException:Object reference not set to an instance of an object.
public partial class PoQuestion : System.Web.UI.Page
{
SqlConnection con;
SqlCommand cmd;
int correct_ans = 0;
int wrong_ans = 0;
int select_no = 0;
int count = 0;
protected void Button1_Click(object sender, EventArgs e)
{
foreach (GridViewRow row in GridView1.Rows)
{
Label l6 = row.FindControl("Question_Id") as Label;
RadioButton r1 = row.FindControl("ans1") as RadioButton;
RadioButton r2 = row.FindControl("ans2") as RadioButton;
RadioButton r3 = row.FindControl("ans3") as RadioButton;
RadioButton r4 = row.FindControl("ans4") as RadioButton;
if (r1.Checked)
{
select_no = 1;
}
else if (r2.Checked)
{
select_no = 2;
}
else if (r3.Checked)
{
select_no = 3;
}
else if (r4.Checked)
{
select_no = 4;
}
con.Close();
check_number(l6.Text); // In this line I have got an error
}
Response.Write("Correct ans is" + correct_ans.ToString());
}
}
This is my html coding sir please reply to me sir
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="PoQuestion.aspx.cs" Inherits="PoQuestion" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:GridView ID="GridView1" runat="server" ShowHeader="false" AutoGenerateColumns="False" DataKeyNames="Question_Id"
DataSourceID="SqlDataSource1" Style="z-index: 100; left: 30px; position: absolute;
top: 82px" GridLines="None" Height="413px" Width="1250px">
<Columns>
<asp:BoundField DataField="Question_Id" HeaderText="Question_Id" InsertVisible="False"
ReadOnly="True" SortExpression="Question_Id" />
<asp:BoundField DataField="Question" HeaderText="Question" SortExpression="Question" />
<asp:TemplateField>
<ItemTemplate>
<asp:RadioButton GroupName="a" runat="server" ID="ans1" Text='<%Eval("ans1") %>' /><br />
</ItemTemplate>
</asp:TemplateField>
</Columns>
<Columns>
<asp:BoundField DataField="ans1" HeaderText="ans1" SortExpression="ans1" />
<asp:TemplateField>
<ItemTemplate>
<asp:RadioButton GroupName="a" runat="server" ID="ans2" Text='<%Eval("ans2") %>' /><br />
</ItemTemplate>
</asp:TemplateField>
</Columns>
<Columns>
<asp:BoundField DataField="ans2" HeaderText="ans2" SortExpression="ans2" />
<asp:TemplateField>
<ItemTemplate>
<asp:RadioButton GroupName="a" runat="server" ID="ans3" Text='<%Eval("ans3") %>' /><br />
</ItemTemplate>
</asp:TemplateField>
</Columns>
<Columns>
<asp:BoundField DataField="ans3" HeaderText="ans3" SortExpression="ans3" />
<asp:TemplateField>
<ItemTemplate>
<asp:RadioButton GroupName="a" runat="server" ID="ans4" Text='<%Eval("ans4") %>' /><br />
</ItemTemplate>
</asp:TemplateField>
</Columns>
<Columns>
<asp:BoundField DataField="ans4" HeaderText="ans4" SortExpression="ans4" />
</Columns>
</asp:GridView>
<asp:ImageButton ID="ImageButton1" runat="server" Height="50px" ImageUrl="~/images/111645-glowing-green-neon-icon-media-a-media31-back.png"
PostBackUrl="~/course.aspx" Style="z-index: 101; left: 700px; position: absolute;
top: 544px" Width="54px" />
<asp:ImageButton ID="ImageButton2" runat="server" Height="50px" ImageUrl="~/images/111646-glowing-green-neon-icon-media-a-media32-forward.png"
Style="z-index: 102; left: 780px; position: absolute; top: 544px" Width="54px" />
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:examConnectionString13 %>"
SelectCommand="SELECT [Question_Id], [Question], [ans1], [ans2], [ans3], [ans4] FROM [question]">
</asp:SqlDataSource>
<asp:Button ID="Button1" runat="server" Style="z-index: 104; left: 403px; position: absolute;
top: 551px" Text="Submit" OnClick="Button1_Click" />
</div>
</form>
</body>
</html>