Chap 4 List Controls

Workmad · November 19th, 2012, 06:57 AM

The results of my Try It Out exercise on Chap 4 are not like that in the book. I am getting the printout of what was checked and/or selected only once so it is giving me only the last item checked instead of all the items selected/checked.

This makes sense because I am only printing it out to one label. Is this really the way you designed this exercise to work?

Here is my code.

Code:

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="ListControls.aspx.vb" Inherits="Demos_ListControls" %>

<!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></title>
</head>
<body>
  <form id="form1" runat="server">
  <div>
    <asp:DropDownList ID="DropDownListLanguage" runat="server" AutoPostBack="True">
      <asp:ListItem>C#</asp:ListItem>
      <asp:ListItem>Visual Basic</asp:ListItem>
      <asp:ListItem>CSS</asp:ListItem>
    </asp:DropDownList>
    <asp:CheckBoxList ID="CheckBoxListLanguage" runat="server">
      <asp:ListItem>C#</asp:ListItem>
      <asp:ListItem>Visual Basic</asp:ListItem>
      <asp:ListItem>CSS</asp:ListItem>
    </asp:CheckBoxList>
    <asp:Button ID="ButtonDone" runat="server" Text="Done" />
    <br />
    <br />
    <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
  </div>
  </form>
</body>
</html>

Code:

Partial Class Demos_ListControls
  Inherits System.Web.UI.Page

  Protected Sub ButtonDone_Click(sender As Object, e As System.EventArgs) Handles ButtonDone.Click
    Label1.Text = "In the DDL you selected " & DropDownListLanguage.SelectedValue & "<br />"

    For Each item As ListItem In CheckBoxListLanguage.Items
      If item.Selected Then
        Label1.Text = "In the CBL you selected " & item.Value & "<br />"
      End If

    Next
  End Sub
End Class

Imar · November 20th, 2012, 03:35 AM

Hi there,

>> Is this really the way you designed this exercise to work?

Yes, that's how it's supposed to work. What you forgot was an additional plus symbol. You have this:

Code:

Label1.Text = "In the CBL you selected " & item.Value & "<br />"

This overrides the Text property of the Label on each iteration. What you need instead is this:

Code:

 
Label1.Text += "In the CBL you selected " & item.Value & "<br />"

Notice the += instead of the =. This appends the new text to the text that was already there on the label.

Chapter 5 has more examples and an explanation of this concatenation operator.

Cheers,

Imar

rajendersingh10 · December 4th, 2012, 12:29 AM

i am unable to understand what you both are trying to explain through these codewords

Imar · December 4th, 2012, 03:33 AM

In that case, you may want to get a copy of this book as it discusses this stuff in detail.

Cheers,

Imar