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Title A VBScript Random Image Selector for use with ASP
Description A small VBScript function that allows random images to be displayed on an Active Server Page (ASP) document
Keywords tutorial, example, vbscript, asp, active server page, random, image, selector, selecting, picture, graphic, selection
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A VBScript Random Image Selector for use with ASP Here is a small function that allows random images to be displayed on an ASP document. Although this is an easy task to achieve in ASP, or even using client-side JavaScript, the VBScript function shown here has the advantage of not needing to know the number of images within the folder it will take account of images being to added or removed from the images folder. An example random image is shown below. Refresh this page to see another:

The RandomImage function is shown below:

%
Function RandomImage(ImagesFolderPath, ImageFileTypes, ImageDescription)

'Declare variables
Dim CompleteImagesFolderPath
Dim FileSystemObject
Dim ImageFolder
Dim Files
Dim i
Dim ImageFiles
Dim File
Dim FileName
Dim FileExtension
Dim RandomNumber

'Find the complete path to image folder by using Server.MapPath
CompleteImagesFolderPath = Server.MapPath(ImagesFolderPath)

'Create an instance of the FileSystemObject which allows ASP to
'access the file system
Set FileSystemObject = Server.CreateObject( Scripting.FileSystemObject )

'Check that the folder containing the images exists
If Not FileSystemObject.FolderExists(CompleteImagesFolderPath) Then
RandomImage = Error 0: Cannot find requested folder
Set FileSystemObject = nothing
Exit Function
End If

'Get the folder containing the images
Set ImageFolder = FileSystemObject.GetFolder(CompleteImagesFolderPath)

'Get a list of all the files within the images folder
Set Files = ImageFolder.Files

'Use a dictionary object to temporarily store the image file names
i = 1
Set ImageFiles = Server.CreateObject( Scripting.Dictionary )

'Loop through the list of files within the images folder.
'If the file has a file extension that is in the list of
'file types specified in the ImageFileTypes function parameter,
'then add the file name to the ImageFiles dictionary object
For Each File in Files

FileName = File.Name
FileExtension = Right(FileName, Len(FileName) - (InStrRev(FileName, . )))

If InStr(1,ImageFileTypes,FileExtension,vbTextCompare) 0 then
ImageFiles.Add i, FileName
i = i + 1
End If

Next

'Destroy objects that are no longer required
Set ImageFolder = nothing
Set Files = nothing
Set FileSystemObject = nothing

'Initialise the random number generator
Randomize

' Check that image file(s) have been found
If ImageFiles.Count = 0 Then
RandomImage = Error 1: Requested folder does not contain any image files
Exit Function
End If

'Generate a random number between 1 and the number of image files
RandomNumber = Int((ImageFiles.Count) * Rnd + 1)

'Return a hyperlink to a random image file
RandomImage = img src= Chr(34) ImagesFolderPath ImageFiles.Item(RandomNumber) Chr(34) alt= Chr(34) ImageDescription Chr(34)

Set ImageFiles = nothing

End Function
%


The function uses the FileSystemObject object to access the file system. It checks that the specified image folder exists, and then extracts a list of files within the folder. A link to one of the images (chosen at random) is then returned.

There is a certain amount of error checking within the script; it will return an error message if it cannot find the images folder, and also if it cannot find any appropriate image files.

The function can be called using the following VBScript:

%Response.Write RandomImage( images/ , gif jpeg , My Image )%

The function has three arguments. The first (ImagesFolderPath) is the name of the folder containing the images, and it should be a sub-folder of the folder that contains the ASP document. The second argument should be a string containing a list of file types to use as images (e.g. jpeg, jpg, gif). Finally, the last argument is a short sentence to describe your image (which is used as the image s ALT tag).

Further Reading Sams Teach Yourself Web Development With ASP in 24 Hours . Start learning ASP with this introductory guide. A JavaScript Banner Ad Rotator . Displays a different image after a specific amount of time. Each image is linked to a different URL. Useful Development Tools ASP Documentation Tool Automatically creates developer documentation for ASP 2.0 and 3.0 web applications written in VBScript and JScript. Documentation for Microsoft Access, SQL Server 7/2000 databases and Visual Basic 6.0 components associated with the web application can also be incorporated into the reports. Documentation is created in HTML, HTML Help and plain text formats. View Sample Output (HTML Help format).
View Sample Output (HTML Format).
Download Trial Version (5.2Mb ZIP file).
ASP.NET Documentation Tool Automatically creates developer documentation for ASP.NET web applications written in C# or VB.NET. Documentation for SQL Server 7/2000 databases and C#/VB.NET components associated with the web application can also be incorporated into the reports. Documentation is created in HTML, HTML Help and plain text formats. View Sample Output (HTML Help format).
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View Sample Output (HTML Format).
Download Trial Version (10.3Mb ZIP file).
Index Server Companion The Index Server Companion is a Windows application that extends the functionality of Microsoft Index Server so that it is able to index content from remote websites and also from ODBC databases. As such it can be used as a low cost alternative to Site Server 3.0 Search. View Product Documentation (119K ZIP file).
Try Sample Search Facility .
Download Trial Version (1.7Mb ZIP file).
The Website Utility The Website Utility examines websites for errors and areas that need to be optimised for search engines by using a built in web crawling engine. Errors checked for include broken or moved hyperlinks, missing page titles and missing meta tags. It also generates HTML for use in creating website site maps (table of contents pages - like this one ), and is able to create both client-side JavaScript Search Engines and server-side ASP Search Engines for a website. View Sample Output (HTML Help format).
View Sample Output (HTML Format).
Download Trial Version (3Mb ZIP file).

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