VB.NET Recursive Files

Page: lines of text

A program needs to recurse through all directories. It starts at a certain point. It then lists all the file paths in those directories. We can use an efficient and bug-free VB.NET Function for this purpose.

Function

Example

First, this is the code for the VB.NET Function that traverses through all subdirectories and then all further subdirectories. It returns a List(Of String), which is often used for file paths.

StringsPath
Program that recurses directories: VB.NET

Imports System.IO

''' <summary>
''' This class contains directory helper method(s).
''' </summary>
Public Class FileHelper

    ''' <summary>
    ''' This method starts at the specified directory, and traverses all subdirectories.
    ''' It returns a List of those directories.
    ''' </summary>
    Public Shared Function GetFilesRecursive(ByVal initial As String) As List(Of String)
	' This list stores the results.
	Dim result As New List(Of String)

	' This stack stores the directories to process.
	Dim stack As New Stack(Of String)

	' Add the initial directory
	stack.Push(initial)

	' Continue processing for each stacked directory
	Do While (stack.Count > 0)
	    ' Get top directory string
	    Dim dir As String = stack.Pop
	    Try
		' Add all immediate file paths
		result.AddRange(Directory.GetFiles(dir, "*.*"))

		' Loop through all subdirectories and add them to the stack.
		Dim directoryName As String
		For Each directoryName In Directory.GetDirectories(dir)
		    stack.Push(directoryName)
		Next

	    Catch ex As Exception
	    End Try
	Loop

	' Return the list
	Return result
    End Function

End Class

Module Module1

    ''' <summary>
    ''' Entry point that shows usage of recursive directory function.
    ''' </summary>
    Sub Main()
	' Get recursive List of all files starting in this directory.
	Dim list As List(Of String) = FileHelper.GetFilesRecursive("C:\Users\Sam\Documents\Perls")

	' Loop through and display each path.
	For Each path In list
	    Console.WriteLine(path)
	Next

	' Write total number of paths found.
	Console.WriteLine(list.Count)
    End Sub

End Module
Path type

We see the actual function that you will want in your project. It uses Stack to build up a list of paths it needs to process. It then processes each directory path in the stack individually, adding all the files each time.

StackMain method

Note:The Main sub here shows how to call FileHelper.GetFilesRecursive and specify a path string.

Tip:The path string must specify an absolute path, or one relative to the program. Here, we specify a C:\ path on my computer.

Output

Question

The output of the above program on my computer is a list of 677 file paths. Each path is fully specified and absolute. They are ordered alphabetically. The sample next shows three of the first several lines printed.

Note:I checked the directory in Windows Explorer by right-clicking on the folder and selecting Properties.

And:The dialog shows that there are 677 files in the folder. Further inspection shows all file paths are accurate.

Example output

C:\Users\Sam\Documents\Perls\Category1.txt
...
C:\Users\Sam\Documents\Perls\Style\all.css
...
C:\Users\Sam\Documents\Perls\Main\2D-Array-IEnumerable.html
...
677
Properties dialog

Summary

The VB.NET programming language

Here we saw a powerful and efficient recursive directory and subdirectory traversing function. It works reliably in programs. It is tested. The function provides accurate results.

Review:It demonstrates an excellent use of Stack and List. It is highly useful in many projects.

List

VB.NET: File