Using an array to sequence a series of images.

[mxo]

Hi All

Please help me with my code I keep getting an error as follow: Object reference not set to an instance of an object.

Here is whole code:

<SCRIPT Runat="Server">
Sub Page_Load

If Not Page.IsPostBack Then

'-- Load an array with image urls and save to View State
Dim ImageArray(3) As String
ImageArray(0) = "aspnet2.gif"
ImageArray(1) = "xhtml.gif"
ImageArray(2) = "jsdhtml.gif"
ViewState("PictureArray") = ImageArray

'-- Establish a counter to keep track of the array index
ViewState("Counter") = 0
MyImage.ImageURL = ImageArray(ViewState("Counter"))
Index.Text = ViewState("Counter")

End If

End Sub

Sub Get_Next_Image (Src As Object, Args As EventArgs)

'-- Retrieve the array from view state
Dim ImageArray() As String
ImageArray = ViewState("PictureArray")

'-- Increment the image counter
ViewState("Counter") += 1
If ViewState("Counter") > 2 Then
ViewState("Counter") = 0
End If

'-- Assign the next image to the control
MyImage.ImageURL = ImageArray(ViewState("Counter"))
Index.Text = ViewState("Counter")

End Sub

</SCRIPT>

<form Runat="Server">

<asp:Image id="MyImage" ImageAlign="AbsMiddle" Runat="Server"/>
<asp:Button Text="Next Image" OnClick="Get_Next_Image" Runat="Server"/>
<p>Array index: <asp:Label id="Index" Runat="Server"/></p>

</form>

 

[jbenson001]

What line does the error occur on?
Also

ImageArray = ViewState("PictureArray")

You should cast the viewstate object to an array.

 

[jbenson001]

Also, don't use inline code as you are doing. This is classic ASP style coding. Use the code-behind page instead.

 

[mxo]

Hi Jbenson001

the error occurs on the following line:
MyImage.ImageURL = ImageArray(ViewState("Counter"))

I do not know if iam aswering your question

 

[jbenson001]

I am not able to replicate the error you are getting. You will have to step through your code while debugging.