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Selecting a Random File from a Directory and Outputting its Contents


By Avi N.

Hello! For my Web site I have a number of directories that contain a number of text files with various bits of information that I wanted to display on my ASP pages. Ideally, I wanted to be able to call a function specifying the path to one of these folders; the function, then, would randomly choose one of the text files in the specified folder and return its contents. Therefore, to display the contents of a random text file in, say, the /MyFiles directory, from my ASP page I could simply do:

Response.Write(ReadDir(Server.MapPath("/MyFiles")))

Note that the ReadDir function's sole parameter expects the folder's physical path. So I used Server.MapPath to convert the Web path (/MyFiles) to a physical path (C:\Inetpub\wwwroot\MyFiles). To learn more about Server.MapPath be sure to read: Using Server.MapPath.

The code for the ReadDir function can be found below. There are numerous comments (and links) in the code, so hopefully those comments and links will help clarify any doubts you may have. (If you expect to use this function on a number of ASP pages it would make sense to place this function in a server-side include file and simply include the file in the ASP pages that need it. For more information on server-side includes be sure to read: To Low-Down on #include.)

There is also a live demo that you can try out.

Happy Programming!

Function ReadDir(FolderName)
  'Start by creating an instance of the FileSystemObject
  'For mpre info on FSO see the related FAQ category
  Dim objFSO
  Set objFSO = Server.CreateObject("Scripting.FileSystemObject")

  'Make sure the specified folder exists
  If Not objFSO.FolderExists(FolderName) Then
    ReadDir = "Folder does not exist. 
This can be changed to " & _ "a default message or nothing." Exit Function End If 'Create a Folder object for the folder path we are interested in Dim objFolder Set objFolder = objFSO.GetFolder(FolderName) 'Here we want to populate an array with all of the file names for text 'files in our folder object. Note that we incrementally resize the 'array for perf reasons (see this user tip for 'an explanation on why we want to do it this way... Dim I : I = -1 ReDim arrFile(20) Dim objFile 'Loop through each file in the folder For Each objFile In objFolder.Files 'Since we only want to work with text files... If Right(objFile, 4) = ".txt" Then I = I + 1 'Do we need to redim our array? if I > UBound(arrFile) then ReDim Preserve arrFile(I + 20) arrFile(I) = objFile.Path End If Next 'Make sure arrFile is the right size Redim Preserve arrFile(I) 'What if we didn't find any files in the directory? If I = -1 Then ReadDir = "No text files in this directory. <br><b>This can be " & _ "changed to a default message or nothing.</b>" Exit Function End If 'Choose a random file from the array Randomize Dim RanFile : RanFile = Int((UBound(arrFile) - 1 + 1) * Rnd + 1) Dim strOutput : strOutput = "" Dim strFileName : strFileName = arrFile(RanFile) If objFSO.FileExists(strFileName) Then 'Open the file and dump its contents into the strOutput variable Dim objTextStream Set objTextStream = objFSO.OpenTextFile(strFileName, 1) Do While Not objTextStream.AtEndOfStream strOutput = strOutput & objTextStream.ReadLine Loop objTextStream.Close Else ReadDir = "File does not exist. <br><b>This can be changed " & _ "to a default message or nothing.</b>" Exit Function End If ReadDir = strOutput 'Finally we have the file's output! Return it 'Clean up... Set objTextStream = Nothing Set objFolder = Nothing Set objFile = Nothing Set objFSO = Nothing End Function

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Article Information
Article Title: 4GuysFromRolla.com - User Tips: Selecting a Random File from a Directory and Outputting its Contents
Article Author: Avi N.
Article URL: http://www.4GuysFromRolla.com/webtech/tips/t053101-1.shtml


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