How do I use FileSystemObject in VBA?

Is there something that I need to reference? How do I use this:

Dim fso As New FileSystemObject
Dim fld As Folder
Dim ts As TextStream

I am getting an error because it does not recognize these objects.

Within Excel you need to set a reference to the VB script run-time library. The relevant file is usually located at \Windows\System32\scrrun.dll

• To reference this file, load the Visual Basic Editor (ALT+F11)
• Select Tools > References from the drop-down menu
• A listbox of available references will be displayed
• Tick the check-box next to 'Microsoft Scripting Runtime'
• The full name and path of the scrrun.dll file will be displayed below the listbox
• Click on the OK button.

This can also be done directly in the code if access to the VBA object model has been enabled.

Access can be enabled by ticking the check-box Trust access to the VBA project object model found at File > Options > Trust Center > Trust Center Settings > Macro Settings

To add a reference:

Sub Add_Reference()

    Application.VBE.ActiveVBProject.References.AddFromFile "C:\Windows\System32\scrrun.dll"
'Add a reference

End Sub

To remove a reference:

Sub Remove_Reference()

Dim oReference As Object
    
    Set oReference = Application.VBE.ActiveVBProject.References.Item("Scripting")
    
    Application.VBE.ActiveVBProject.References.Remove oReference
'Remove a reference

End Sub

In excel 2013 the object creation string is:

Dim fso
Set fso = CreateObject("Scripting.FileSystemObject")

instead of the code in the answer above:

Dim fs,fname
Set fs=Server.CreateObject("Scripting.FileSystemObject")

These guys have excellent examples of how to use the filesystem object http://www.w3schools.com/asp/asp_ref_filesystem.asp

<%
dim fs,fname
set fs=Server.CreateObject("Scripting.FileSystemObject")
set fname=fs.CreateTextFile("c:\test.txt",true)
fname.WriteLine("Hello World!")
fname.Close
set fname=nothing
set fs=nothing
%> 

After adding the reference, I had to use

Dim fso As New Scripting.FileSystemObject

After importing the scripting runtime as described above you have to make some slighty modification to get it working in Excel 2010 (my version). Into the following code I've also add the code used to the user to pick a file.

Dim intChoice As Integer
Dim strPath As String

' Select one file
Application.FileDialog(msoFileDialogOpen).AllowMultiSelect = False

' Show the selection window
intChoice = Application.FileDialog(msoFileDialogOpen).Show

' Get back the user option
If intChoice <> 0 Then
	strPath = Application.FileDialog(msoFileDialogOpen).SelectedItems(1)
Else
	Exit Sub
End If

Dim FSO As New Scripting.FileSystemObject
Dim fsoStream As Scripting.TextStream
Dim strLine As String

Set fsoStream = FSO.OpenTextFile(strPath)

Do Until fsoStream.AtEndOfStream = True
    strLine = fsoStream.ReadLine
	' ... do your work ...
Loop

fsoStream.Close
Set FSO = Nothing

Hope it help!

Best regards

Fabio