Improve this function to get recursively all files inside a directory

Question

I need is to implement the file recursivity in this function to get all the files inside the subdirectories.

I want to preserve the efficiency of the function (I mean to avoid the using of large loops inside folders)

How I can do it?

EDIT: Also I need to put a Boolean arg to let me select if I want enable recursivity or not.

' For Each file In Get_Files("C:\Windows", {".dll", ".ini"}) : MsgBox(file.Name) : Next

Private Function Get_Files(ByVal Path As String, ParamArray exts() As String) As List(Of IO.FileInfo)
    Return New IO.DirectoryInfo(Path).GetFiles.Where(Function(o) exts.Contains(o.Extension)).ToList
End Function

UPDATE

I need to preserve in the dotINSolution modification the eficiency of the original code which returns a list of IO.FileInfo instead a list of string:

Private Function Get_Files(ByVal Path As String, ByVal Recursive As Boolean, ParamArray exts() As String) As List(Of String) ' As List(Of IO.FileInfo)
    Select Case Recursive
        Case True : Return IO.Directory.GetFiles(Path, "*.*", IO.SearchOption.AllDirectories).Where(Function(o) exts.Contains(IO.Path.GetExtension(o))).ToList
        Case False : Return IO.Directory.GetFiles(Path, "*.*", IO.SearchOption.TopDirectoryOnly).Where(Function(o) exts.Contains(IO.Path.GetExtension(o))).ToList
    End Select
End Function

Is this possibly without doing major changes or without converting the result more than one time?

Answer 1

Finally this is my generic function with two additional overloads to improve the usage of the function, thanks to @Andrew Morton and @dotINSolution modifications:

#Region " Get Files "

    ' [ Get Files Function ]
    '
    ' Examples :
    '
    ' For Each file In Get_Files("C:\Windows", False) : MsgBox(file.Name) : Next
    '
    ' For Each file In Get_Files("C:\Windows", True, "dll")   : MsgBox(file.Name) : Next
    ' For Each file In Get_Files("C:\Windows", True, ".dll")  : MsgBox(file.Name) : Next
    ' For Each file In Get_Files("C:\Windows", True, "*.dll") : MsgBox(file.Name) : Next
    '
    ' For Each file In Get_Files("C:\Windows", False, {"dll", "ini"})     : MsgBox(file.Name) : Next
    ' For Each file In Get_Files("C:\Windows", False, {".dll", ".ini"})   : MsgBox(file.Name) : Next
    ' For Each file In Get_Files("C:\Windows", False, {"*.dll", "*.ini"}) : MsgBox(file.Name) : Next

    ' Get Files {directory} {recursive}
    Private Function Get_Files(ByVal directory As String, ByVal recursive As Boolean) As List(Of IO.FileInfo)
        Dim searchOpt As IO.SearchOption = If(recursive, IO.SearchOption.AllDirectories, IO.SearchOption.TopDirectoryOnly)
        Return IO.Directory.GetFiles(directory, "*", searchOpt).Select(Function(p) New IO.FileInfo(p)).ToList
    End Function

    ' Get Files {directory} {recursive} {ext}
    Private Function Get_Files(ByVal directory As String, ByVal recursive As Boolean, ext As String) As List(Of IO.FileInfo)

        If ext.StartsWith("*") Then
            ext = ext.Substring(1, ext.Length - 1)
        ElseIf Not ext = "*" AndAlso Not ext.StartsWith(".") Then
            ext = ("." & ext)
        ElseIf ext = "*" Then
            ext = Nothing
        End If

        Dim searchOpt As IO.SearchOption = If(recursive, IO.SearchOption.AllDirectories, IO.SearchOption.TopDirectoryOnly)
        Return IO.Directory.GetFiles(directory, "*" & ext, searchOpt).Select(Function(p) New IO.FileInfo(p)).ToList

    End Function

    ' Get Files {directory} {recursive} {exts()}
    Private Function Get_Files(ByVal directory As String, ByVal recursive As Boolean, ParamArray exts() As String) As List(Of IO.FileInfo)

        Dim FileExtensions(exts.Count) As String

        Dim ExtCount As Int64 = 0

        For Each ext In exts
            If ext.StartsWith("*") Then
                FileExtensions(ExtCount) = ext.Substring(1, ext.Length - 1)
            ElseIf Not ext = "*" AndAlso Not ext.StartsWith(".") Then
                FileExtensions(ExtCount) = ("." & ext)
            ElseIf Not ext = "*" AndAlso ext.StartsWith(".") Then
                FileExtensions(ExtCount) = ext
            ElseIf ext = "*" Then
                FileExtensions(ExtCount) = Nothing
            End If
            ExtCount += 1
        Next

        Dim searchOpt As IO.SearchOption = If(recursive, IO.SearchOption.AllDirectories, IO.SearchOption.TopDirectoryOnly)
        Dim filenameExtComparer As New FilenameExtensionComparer
        Return IO.Directory.GetFiles(directory, "*.*", searchOpt).Where(Function(o) FileExtensions.Contains(IO.Path.GetExtension(o), filenameExtComparer)).Select(Function(p) New IO.FileInfo(p)).ToList

    End Function

    ' FilenameExtensionComparer
    Public Class FilenameExtensionComparer : Implements IEqualityComparer(Of String)

        Public Function Equals1(s As String, t As String) As Boolean Implements IEqualityComparer(Of String).Equals
            Return String.Compare(s, t, StringComparison.OrdinalIgnoreCase) = 0
        End Function

        Public Function GetHashCode1(s As String) As Integer Implements IEqualityComparer(Of String).GetHashCode
            Return s.GetHashCode()
        End Function

    End Class

#End Region

Answer 2

All you need to do get a list of FileInfo instead of filenames is create a new FileInfo for each file, like this:

Private Function Get_Files(ByVal rootDirectory As String, ByVal recursive As Boolean, ParamArray exts() As String) As List(Of IO.FileInfo)
    Dim searchOpt As IO.SearchOption = If(recursive, IO.SearchOption.AllDirectories, IO.SearchOption.TopDirectoryOnly)
    Return IO.Directory.GetFiles(rootDirectory, "*.*", searchOpt).Where(Function(o) exts.Contains(IO.Path.GetExtension(o))).Select(Function(p) New IO.FileInfo(p)).ToList
End Function

And if you use Imports System.IO at the top of your code, you don't need to type IO. so much and it will look tidier.

EDIT:

For a case-sensitive test of the extension, you could implement the comparer in the Enumerable.Contains method:

Public Class FilenameExtensionComparer
    Implements IEqualityComparer(Of String)

    Public Function Equals1(s As String, t As String) As Boolean Implements IEqualityComparer(Of String).Equals
        Return String.Compare(s, t, StringComparison.OrdinalIgnoreCase) = 0
    End Function

    Public Function GetHashCode1(s As String) As Integer Implements IEqualityComparer(Of String).GetHashCode
        Return s.GetHashCode()
    End Function

End Class

Private Function Get_Files(ByVal rootDirectory As String, ByVal recursive As Boolean, ParamArray exts() As String) As List(Of IO.FileInfo)
    Dim searchOpt As IO.SearchOption = If(recursive, IO.SearchOption.AllDirectories, IO.SearchOption.TopDirectoryOnly)
    Dim filenameExtComparer As New FilenameExtensionComparer
    Return IO.Directory.GetFiles(rootDirectory, "*.*", searchOpt).Where(Function(o) exts.Contains(IO.Path.GetExtension(o), filenameExtComparer)).Select(Function(p) New IO.FileInfo(p)).ToList
End Function

I sense feature-creep in this question ;) You should have a look at the documentation for the .NET methods which are used and see if they have overloads which are useful to you.

EDIT 2: Oops, I see you wanted case-insensitivity. I adjusted the comparer appropriately.

Answer 3

This should do the trick for you :)

Private Function Get_Files(ByVal Path As String, ParamArray exts() As String) As List(Of IO.FileInfo)
    Return Directory.GetFiles(Path, "*.*", SearchOption.AllDirectories).Where(Function(o) exts.Contains(Path.GetExtension(o))).ToList
End Function

Edit, With Optional recursivity:

Private Function Get_Files(ByVal Path As String, Byval searchOption As System.IO.SearchOption, ParamArray exts() As String) As List(Of IO.FileInfo)
    Return Directory.GetFiles(Path, "*.*", searchOption).Where(Function(o) exts.Contains(Path.GetExtension(o))).ToList
End Function

To search in Top Directory only:

For Each file In Get_Files("C:\Windows", SearchOption.TopDirectoryOnly, {".dll", ".ini"}) : MsgBox(file.Name) : Next

To do a recursive search:

For Each file In Get_Files("C:\Windows", SearchOption.AllDirectories, {".dll", ".ini"}) : MsgBox(file.Name) : Next