How to search a folder with its subfolders and save the results to an array VB.NET - vb.net

Question

I am trying to execute a search on a folder and get an array of every result back. I found this code but it doesn't go into subfolders:
Dim Results As New List(Of String)
For Each strFileName As String In IO.Directory.GetFiles("pathToSearch")
If strFileName.Contains("searchTerm") Then
Results.Add(strFileName)
End If
Next
How can I do exactly this, but also look into the subfolders?
I'm not very knowledgeable about the search options in VB.NET yet, so I apologize in advance if this seems stupid. I have tried searching online but haven't found anything. I can't have a single string, it needs to be an array (this needs to be interpreted by the machine later in the program)
Thanks for any help

Answer 1

No recursion required. There is already an overload for this. You just need to call it with appropriate search option.
e.g. To list all txt files in the directory as well as the subdirectories you can do:
Dim foundFiles() As String = System.IO.Directory.GetFiles("path/to/dir", "*.txt", System.IO.SearchOption.AllDirectories)

Answer 2

In order to get the subfolders you might try some recursive function

Answer 3

Unless there's a file system search API with which I'm unfamiliar, this is going to involve a recursive method to perform the searching into sub-directories.
Helpfully, Microsoft even has a complete example of something very similar available. In VB it might look something like this (my VB is very rusty and this is free-hand code, by the way...):
Function FindFiles(ByVal dir As String, ByVal searchTerm As String) As List(Of String)
Dim Results As New List(Of String)
' search files in this directory
For Each strFileName As String In IO.Directory.GetFiles(dir)
If strFileName.Contains(searchTerm) Then
Results.Add(strFileName)
End If
Next
' recurse into child directories
For Each strDirectoryName As String In IO.Directory.GetDirectories(dir)
Results = Results.AddRange(FindFiles(strDirectoryName, searchTerm)
Next
Return Results
End Function

Answer 4

Make a recursive function that keeps calling itself until all subdirectories are checked:
Private Function GetAllFileNamesFromDirectory(ByVal strPath As String, ByVal strSearchTerm As String) As List(Of String)
Dim lstFileNames As New List(Of String)
Dim lstSubDirectories As List(Of String) = IO.Directory.GetDirectories(strPath).ToList()
Dim lstFilesToAdd As List(Of String) = IO.Directory.GetFiles(strPath).ToList()
For Each strFileToAdd As String In lstFilesToAdd
If strFileToAdd.Contains(strSearchTerm) Then
'Additional logic would be required to filter out the directory name.
lstFileNames.Add(strFileToAdd)
End If
Next
If lstSubDirectories.Count > 0 Then
lstSubDirectories.ForEach(Sub(strDirectoryPath As String)
Dim lstSubDirectoryFilesToAdd As List(Of String) = GetAllFileNamesFromDirectory(strDirectoryPath, strSearchTerm)
If lstSubDirectoryFilesToAdd.Count > 0 Then
lstFileNames.AddRange(lstSubDirectoryFilesToAdd)
End If
End Sub)
End If
Return lstFileNames
End Function