The System.IO.Directory.GetFiles method lets you easily search for files in a directory that match a pattern. Unfortunately it can only search for files that match a single pattern. For example, if you want to find files that match the patterns *.bmp, *.gif, *.jpg, and *.png, you're out of luck.

The FindFiles method shown in the following code searches for files that match multiple patterns.

' Search for files matching the patterns.
Private Function FindFiles(ByVal dir_name As String, ByVal _
    patterns As String, ByVal search_subdirectories As _
    Boolean) As List(Of String)
    ' Make the result list.
    Dim files As New List(Of String)()

    ' Get the patterns.
    Dim pattern_array() As String = patterns.Split(";"c)

    ' Search.
    Dim search_option As SearchOption = _
        SearchOption.TopDirectoryOnly
    If search_subdirectories Then search_option = _
        SearchOption.AllDirectories
    For Each pattern As String In pattern_array
        For Each filename As String In _
            Directory.GetFiles(dir_name, pattern, _
            search_option)
            If Not files.Contains(filename) Then _
                files.Add(filename)
        Next filename
    Next pattern

    ' Sort.
    files.Sort()

    ' Return the result.
    Return files
End Function