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Filter GetFiles() by file name and select one random file.

Posted on 2010-08-25
Last Modified: 2012-05-10
I am reading the contents of a Directory using VB.net and the FileInfo() and GetFiles commmands.

Dim DirectoryLocation As New IO.DirectoryInfo("c:\somedir")
Dim FileArray As IO.FileInfo() = DirectoryLocation.GetFiles("*.jpg")
Dim FilesInFolder As IO.FileInfo

This code will return several results:

I want to eliminate the files starting with "thumb_" from the list  and then select one random file from those results.

I am trying to select a random background image for a webpage from a folder on the server.

I have spent all day on this so far. this code will select a random item from the GetFiles() Array
FileArray(RandString.[Next](0, FileArray.Length)) but before i do that i need to remove the files that contain "thumb" in the file name.

I have tried the FILTER command on the GetFiles() array but i throws an error due to the array type.

any help you can throw my way would be greatly appreciated!

Question by:ronayers
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 33525502
If you're using .NET 3.x or above, you could throw in some Linq:
Dim DirectoryLocation As New IO.DirectoryInfo("c:\somedir")
Dim FileArray As IO.FileInfo() = DirectoryLocation.GetFiles("*.jpg")
Dim FilesInFolder As IO.FileInfo

FileArray = (From item As IO.FileInfo In FileArray _
            Where Not item.Name.StartsWith("thumb_") _
            Select item).ToArray()

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LVL 11

Accepted Solution

ladarling earned 500 total points
ID: 33525516
Try something like...

For Each f As IO.FileInfo In FileArray
            If f.Name.StartsWith("thumb") Then
            End If

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LVL 75

Expert Comment

by:käµfm³d 👽
ID: 33525530

I think he mean "eliminate" the files from the list, not delete the image file entirely.
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Expert Comment

ID: 33525549

Try something like this ...

Dim RandomFileName as String = ""


     RandomFileName = FileArray(RandString.[Next](0, FileArray.Length))

Loop While(RandomFileName.ToLower().StartsWith("thumb_"))

If RandomFileName <> "" Then
     ' use the random file name here
End If

LVL 17

Expert Comment

ID: 33525570
Try this:

        Dim DirectoryLocation As New IO.DirectoryInfo("c:\somedir")
        Dim FileArray As IO.FileInfo() = DirectoryLocation.GetFiles("*.jpg")
        Dim newFileArray As IO.FileInfo() = Nothing
        Dim count As Integer
        For Each oInfo As FileInfo In FileArray
            If oInfo.Name.StartsWith("thumb_", System.StringComparison.CurrentCultureIgnoreCase) = False Then
                count += 1
                Array.Resize(newFileArray, count)
                newFileArray(count - 1) = oInfo
            End If

Now newFileArray will hold the files without "thumb_".

LVL 11

Expert Comment

ID: 33525580
@kaufmed..... Oh, ok... gotcha...
Then, a non-Linq way would be:

    Dim FileArray As IO.FileInfo()
        Dim GoodFiles As New List(Of IO.FileInfo)
        For Each f As IO.FileInfo In FileArray
            If Not f.Name.StartsWith("thumb") Then
            End If
 FileArray = GoodFiles.ToArray

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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 33525821
Love all the ways to do it...here's another one:
        Dim Files As New List(Of IO.FileInfo)
        Files.AddRange(New IO.DirectoryInfo("c:\somedir").GetFiles("*.jpg"))
        Files.RemoveAll(Function(fi As IO.FileInfo) fi.Name.ToLower.StartsWith("thumb_"))
        Dim RandomFile As String = Files(New Random().Next(0, Files.Count)).FullName

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Author Closing Comment

ID: 33537198

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