How to Retrieve Hidden/System Files Using Dir[$]() Function

- Microsoft Visual Basic programming system for Windows,

  versions 2.0 and 3.0

SUMMARY

This article shows by example how to use the Dir[$]() function in conjunction with the GetAttr() function to retrieve read-only, hidden, or system files.

MORE INFORMATION

The Dir[$] functions take a filespec and an attrmask as optional arguments.

If the attrmask argument specifies the volume label, the Dir[$] functions ignores all other attributes. If the attrmask argument is ATTR_HIDDEN, ATTR_SYSTEM, or ATTR_DIRECTORY, the functions also return the files that do not have any special attributes.

If the filespec argument is used, the functions return files that do not have any hidden, system, or directory attributes and meet the filespec requirements.

To retrieve only read-only, hidden, or system files, use the Dir[$]() functions in conjunction with the GetAttr() function. The following shows by example how to retrieve only hidden files (files that have the HIDDEN or ATTR_HIDDEN+ATTR_ARCHIVE attributes) by using the Dir() function in conjunction with the GetAttr() function.

Step-by-Step Example

1. Start Visual Basic or begin a new project if Visual Basic is already running. Form1 is created by default.

2. Place the following code in the general declarations area for Form1:

   Const ATTR_NORMAL = 0 Const ATTR_READONLY = 1 Const ATTR_HIDDEN = 2 Const ATTR_SYSTEM = 4 Const ATTR_VOLUME = 8 Const ATTR_DIRECTORY = 16 Const ATTR_ARCHIVE = 32

3. Add a List box and a command button to Form1.

4. Add the following code to the command button's click event procedure:

      Sub Command1_Click ()
         Dim filename As String
         Dim attr As Integer
         ' retrieve hidden and normal files
         filename = Dir$("c:\", ATTR_HIDDEN)
         Do Until filename = ""
            attr = GetAttr("c:\" & filename)
            ' if the file has the hidden attribute
            If (attr And ATTR_HIDDEN) Then
               ' select it
               List1.AddItem filename
            End If
            filename = Dir$
         Loop
   
      End Sub
   
   

5. Run the program and click the command button to see any existing hidden files in the root directory.