asp.net display code with c# | try-catch-finally in asp.net

In this article i have shown to display value in to database using c# using gridview

           try
            {
               con.Open();
               string query = "select * from feesentry_tb";
               SqlCommand cmd = new SqlCommand(query, con);
               SqlDataAdapter da = new SqlDataAdapter(cmd);
               DataTable dt = new DataTable();
               da.Fill(dt);
               grdvw.DataSource = dt;
               grdvw.DataBind();
              
            }
            catch (Exception ex)
            {
                Response.Write(ex);
            }
            finally
            {
                con.Close();
            }
      

Perfect number program source code in vb.net | login

How to write  Perfect number program code in vb.net using for loop and next
 Dim sum As Integer = 0
        Dim i As Integer
        For i = 1 To Convert.ToInt16(TextBox1.Text) - 1
            If (Convert.ToInt16(TextBox1.Text) Mod i = 0) Then
                sum += i
            End If
        Next
        If sum = Convert.ToInt16(TextBox1.Text) Then
            MsgBox("It is perfect no")
        Else
            MsgBox("It is no perfect no")
        End If

Login form validation in vb.net using username and password field

Onbutton_click()
{
If (UsernameTextBox.Text = "" And PasswordTextBox.Text = "") Then
            MsgBox("Enter username & password")
        Else

            If (UsernameTextBox.Text = "") Then
                MsgBox("Enter username")
            Else
                If (PasswordTextBox.Text = "") Then
                    MsgBox("Enter password")
                Else
                    If (UsernameTextBox.Text = "scott" And PasswordTextBox.Text = "tiger") Then
                        ProgressBar1.Visible = True
                        ProgressBar1.Value = 0
                        Dim i As Integer = 100000
                        While (i >= ProgressBar1.Value)
                            ProgressBar1.Value = ProgressBar1.Value + 10
                        End While
                        Form1.Show()
                        Me.Hide()

                    Else
                        MsgBox("Enter correct username & password")
                    End If
}

checkbox.checked | listbox.item | radiobutton.cheked in vb.net

How to write vb.net code to check check box and select listItem item and add them.
    Private Sub Buttonon_Click() Handles Button1.Click

        listboxvalue.Items.Add("First Name=" + TextBoxvalue1.Text + " Last Name=" + TextBoxvalue2.Text + " Address=" + TextBoxvalue3.Text + " City="
        + ComboBox1.Text + "\nSex=")

        If (radiobuttonvalue.Checked = True) Then
            listboxvalue.Items.Add("Male")
        Else
            listboxvalue.Items.Add("Female")
        End If

        listboxvalue.Items.Add(" Age=" + NumericUpDown1.Value.ToString() + " Hobbies are=")

        If (chkvalue1.Checked = True) Then
            listboxvalue.Items.Add(" Cricket")
        End If

        If (chkvalue2.Checked = True) Then
            listboxvalue.Items.Add(" Football")
        End If

        If (chkvalue3.Checked = True) Then
            listboxvalue.Items.Add(" Tennis")
        End If

        If (chkvalue4.Checked = True) Then
            listboxvalue.Items.Add(" BasketBall")
        End If
    End Sub
End Class

while | if | dropdownlist in javascript

while | if | dropdownlist in javascript
        int i = 0;
        int indx = drpdwn.SelectedIndex;
        int var = 3;
        while (i <= var)
        {
            if (i == indx)
            {
              //  lbl.Text = "you have selected" + indx;
                one.Text =Convert.ToString(indx * 8);
                break;
            }
            else
            {
                i++;
            }
        }

 <table>
    <tr><td>
    <asp:DropDownList ID="drpdwn" runat="server" AutoPostBack="True"
            ontextchanged="drpdwn_TextChanged">
    <asp:ListItem Value="1">Java Programming</asp:ListItem>
    <asp:ListItem Value="2">C Programming</asp:ListItem>
    <asp:ListItem Value="3">Asp Programming</asp:ListItem>
    <asp:ListItem Value="4">c++ Programming</asp:ListItem>
    </asp:DropDownList>
    </td></tr>
    <tr><td>
    <asp:Label runat="server" ID="lbl"></asp:Label>
   
    </td></tr>
    </table>