Virendra Virendra - 3 months ago 9
Vb.net Question

What’s the best way to calculate the size of a directory in VB .NET?

I need to calculate the directory size in VB .Net

I know the following 2 methods

Method 1: from MSDN http://msdn.microsoft.com/en-us/library/system.io.directory.aspx

' The following example calculates the size of a directory
' and its subdirectories, if any, and displays the total size
' in bytes.
Imports System
Imports System.IO

Public Class ShowDirSize

Public Shared Function DirSize(ByVal d As DirectoryInfo) As Long
Dim Size As Long = 0
' Add file sizes.
Dim fis As FileInfo() = d.GetFiles()
Dim fi As FileInfo
For Each fi In fis
Size += fi.Length
Next fi
' Add subdirectory sizes.
Dim dis As DirectoryInfo() = d.GetDirectories()
Dim di As DirectoryInfo
For Each di In dis
Size += DirSize(di)
Next di
Return Size
End Function 'DirSize

Public Shared Sub Main(ByVal args() As String)
If args.Length <> 1 Then
Console.WriteLine("You must provide a directory argument at the command line.")
Else
Dim d As New DirectoryInfo(args(0))
Dim dsize As Long = DirSize(d)
Console.WriteLine("The size of {0} and its subdirectories is {1} bytes.", d, dsize)
End If
End Sub 'Main


End Class 'ShowDirSize

Method 2: from http://stackoverflow.com/questions/468119/whats-the-best-way-to-calculate-the-size-of-a-directory-in-net

Dim size As Int64 = (From strFile In My.Computer.FileSystem.GetFiles(strFolder, _
FileIO.SearchOption.SearchAllSubDirectories) _
Select New System.IO.FileInfo(strFile).Length).Sum()

Both these methods work fine. However they take lot of time to calculate the directory size if there are lot of sub-folders. e.g i have a directory with 150,000 sub-folders. The above methods took around 1 hr 30 mins to calculate the size of the directory. However, if I check the size from windows it takes less than a minute.

Please suggest better and faster ways to calculate the size of the directory.

Answer

Though this answer is talking about Python, the concept applies here as well.

Windows Explorer uses system API calls FindFirstFile and FindNextFile recursively to pull file information, and then can access the file sizes very quickly through the data that's passed back via a struct, WIN32_FIND_DATA: http://msdn.microsoft.com/en-us/library/aa365740(v=VS.85).aspx.

My suggestion would be to implement these API calls using P/Invoke, and I believe you will experience significant performance gains.