Chap#3/<asp:listbox>Control p.83

goran1 · September 8th, 2004, 07:29 PM

I need some help people!
I typed the code on p. 83 exactly as it is and I get the same error msg every time:
Compiler Error Message: BC30451: Name 'msg' is not declared
<%@ Page Language="vb" %>
<script runat="server">

    Sub Page_Load()
        If Page.IsPostBack Then Dim msg As String
            If list1.Items(0).Selected Then msg = msg & list1.Items(0).Text & "<br />";
                If list1.Items(1).Selected Then msg = msg & list1.Items(1).Text & "<br />"
                If list1.Items(2).Selected Then msg = msg & list1.Items(2).Text & "<br />"
                If msg <> "" then
                    Message.Text = "You have selected: <bt />" & msg
                    Else
                    message.text = ""
            End if
        End if
    End Sub

</script>
<html>
<head>
    <title>List Box Example</title>
</head>
<body>
    <asp:Label id="Message" runat="server"></asp:Label>
    <br />
    Which city do you wish to look at hotels for?<br />
    <form runat="server">
        <asp:listbox id="list1" runat="server" selectionmode="multiple">
            <asp:listitem>Madrid</asp:listitem>
            <asp:listitem>Oslo</asp:listitem>
            <asp:listitem>Lisabon</asp:listitem>
        </asp:listbox>
        <br />
        <input type="submit" value="Submit Query" />
    </form>
</body>
</html>

Now, I have a vague idea what it means but I have no clue how to fix it. I checked my code, retyped it three times, and still the same error msg. When I click on the Design/Preview tab in ASP.NET Web Matrix everything looks normal and I can see the drop down box and everything else but when I try to open the file through the browser the compiler brings the compilation error. Any ideas?

gkelley091565 · September 8th, 2004, 11:02 PM

Found two things wrong, syntax errors both.

1.) Move 'Dim msg As String' down from line 5 to 6:
If Page.IsPostBack Then
        Dim msg As String

2.) Remove the semicolon (;) from line 7 (line 6 if you haven't already performed step 1 above! )

Your complete working code is:

<%@ Page Language="vb" %>
<script runat="server">

    Sub Page_Load()
        If Page.IsPostBack Then
        Dim msg As String
            If list1.Items(0).Selected Then msg = msg & list1.Items(0).Text & "<br />"
                If list1.Items(1).Selected Then msg = msg & list1.Items(1).Text & "<br />"
                If list1.Items(2).Selected Then msg = msg & list1.Items(2).Text & "<br />"
                If msg <> "" then
                    Message.Text = "You have selected: <bt />" & msg
                    Else
                    message.text = ""
            End if
        End if
    End Sub

</script>
<html>
<head>
    <title>List Box Example</title>
</head>
<body>
    <asp:Label id="Message" runat="server"></asp:Label>
    <br />
    Which city do you wish to look at hotels for?<br />
    <form runat="server">
        <asp:listbox id="list1" runat="server" selectionmode="multiple">
            <asp:listitem>Madrid</asp:listitem>
            <asp:listitem>Oslo</asp:listitem>
            <asp:listitem>Lisabon</asp:listitem>
        </asp:listbox>
        <br />
        <input type="submit" value="Submit Query" />
    </form>
</body>
</html>

Gene Kelley
BizFlowDesigns.com
Arlington, Texas, USA

gkelley091565 · September 8th, 2004, 11:06 PM

.... also, on line 11: try <br /> instead of <bt />.:)

Gene Kelley
BizFlowDesigns.com
Arlington, Texas, USA

gkelley091565 · September 9th, 2004, 08:59 PM

Well, I'll have to be quite honest with you and say that "I don't know why." it doesn't like it being on the same line. I just know that when you do, the code doesn't run correctly. When and if I find a better answer for us, I will certainly post it here.

Gene Kelley
BizFlowDesigns.com
Arlington, Texas, USA

Kateract · September 6th, 2005, 10:54 AM

The problem appears to be that if you put arguments on the same line as the if...then statement, it treats it as a one line declaration instead of a multiple line if...then. Really, if the form is not a postback, then it should skip to the last end if statement. That is why there are two end if's at the end of the sub, one for [If Page.IsPostBack] and one for [If msg <> ""].