Searching By File Extensions VB.NET [duplicate] - vb.net

Question

This question already has answers here:
What is a NullReferenceException, and how do I fix it?
(27 answers)
Closed 5 years ago.
Hi all i have been trying to search a specified directory and all sub directories for all files that have the specified file extension. However the inbuilt command is useless as it errors up and dies if you dont have access to a directory. So here's what i have at the moment:
Private Function dirSearch(ByVal path As String, Optional ByVal searchpattern As String = ".exe") As String()
Dim di As New DirectoryInfo(path)
Dim fi As FileInfo
Dim filelist() As String
Dim i As Integer = 0
For Each fi In di.GetFiles
If System.IO.Path.GetExtension(fi.FullName).ToLower = searchpattern Then
filelist(i) = fi.FullName
i += 1
End If
Next
Return filelist
End Function
However i get an "System.NullReferenceException: Object reference not set to an instance of an object." when i try to access the data stored inside the filelist string array.
Any idea's on what im doing wrong?

Answer 1

You didn't instantiate the Dim filelist() As String array. Try di.GetFiles(searchPattern)
Dim files() as FileInfo = di.GetFiles(searchPattern)
Use static method Directory.GetFiles that returns an array string
Dim files = Directory.GetFiles(Path,searchPattern,searchOption)
Demo:
Dim files() As String
files = Directory.GetFiles(path, "*.exe", SearchOption.TopDirectoryOnly)
For Each FileName As String In files
Console.WriteLine(FileName)
Next
Recursive directory traversal:
Sub Main()
Dim path = "c:\jam"
Dim fileList As New List(Of String)
GetAllAccessibleFiles(path, fileList)
'Convert List<T> to string array if you want
Dim files As String() = fileList.ToArray
For Each s As String In fileList
Console.WriteLine(s)
Next
End Sub
Sub GetAllAccessibleFiles(path As String, filelist As List(Of String))
For Each file As String In Directory.GetFiles(path, "*.*")
filelist.Add(file)
Next
For Each dir As String In Directory.GetDirectories(path)
Try
GetAllAccessibleFiles(dir, filelist)
Catch ex As Exception
End Try
Next
End Sub

Answer 2

Use System.IO.Directory.EnumerateFiles method and pass SearchOption.AllDirectories in to traverse the tree using a specific search pattern. Here is an example:
foreach (var e in Directory.EnumerateFiles("C:\\windows", "*.dll", SearchOption.AllDirectories))
{
Console.WriteLine(e);
}