ElektroStudios - 1 month ago 9x
Vb.net Question

# Generic File Size Calculator

I'm trying to code a generic function to convert between filesizes, bytes to kb, gb to mb, etc...

The problem begins when "ToSize" value is lower than "FromSize", I don't get the correct values.

Someone can help me to fix the problems and maybe to simplify all the code?

``````#Region " Convert Between Sizes "

Enum FromSize As Long
bytes = 1L
kilobyte = 1024L
megabyte = 1048576L
gigabyte = 1073741824L
terabyte = 1099511627776L
petabyte = 1125899906842624L
End Enum

Enum ToSize As Long
bytes = 1L
kilobyte = 1024L
megabyte = 1048576L
gigabyte = 1073741824L
terabyte = 1099511627776L
petabyte = 1125899906842624L
End Enum

Private Function Size_To_Size(ByVal Size As Long, _
ByVal FromSize As FromSize, _
ByVal ToSize As ToSize, _
Optional ByVal decimals As Integer = 2 _
) As Double

Dim bytes As Double = Convert.ToDouble(Size * FromSize)
Dim Kbs As Double = bytes * FromSize.kilobyte
Dim mbs As Double = bytes * FromSize.megabyte
Dim gbs As Double = bytes * FromSize.gigabyte
Dim tbs As Double = bytes * FromSize.terabyte
Dim pbs As Double = bytes * FromSize.petabyte

If ToSize < FromSize Then

Select Case ToSize
Case ToSize.bytes : Return bytes
Case ToSize.kilobyte : Return Kbs.ToString("n" & decimals)
Case ToSize.megabyte : Return mbs.ToString("n" & decimals)
Case ToSize.gigabyte : Return gbs.ToString("n" & decimals)
Case ToSize.terabyte : Return tbs.ToString("n" & decimals)
Case ToSize.petabyte : Return pbs.ToString("n" & decimals)
Case Else : Return -1
End Select

ElseIf ToSize > FromSize Then

Select Case ToSize
Case ToSize.bytes : Return bytes
Case ToSize.kilobyte : Return (Kbs / ToSize.kilobyte / 1024L).ToString("n" & decimals)
Case ToSize.megabyte : Return (mbs / ToSize.megabyte / 1024L / 1024L).ToString("n" & decimals)
Case ToSize.gigabyte : Return (gbs / ToSize.gigabyte / 1024L / 1024L / 1024L).ToString("n" & decimals)
Case ToSize.terabyte : Return (tbs / ToSize.terabyte / 1024L / 1024L / 1024L / 1024L).ToString("n" & decimals)
Case ToSize.petabyte : Return (pbs / ToSize.petabyte / 1024L / 1024L / 1024L / 1024L / 1024L).ToString("n" & decimals)
Case Else : Return -1
End Select

Else ' ToSize = FromSize
Return Size.ToString("n" & decimals)

End If

End Function

#End Region
``````

UPDATE:

This gives the correct result:

``````    MsgBox(Size_To_Size(50, FromSize.gigabyte, ToSize.bytes).ToString("n2"))
' Result: 53,687,091,200
``````

This DON'T gives the correct result:

``````    msgbox(Size_To_Size(50, FromSize.gigabyte, ToSize.kilobyte).ToString("n2"))
' Result: 54.975.581.388.800,00
' Expected result: 52,428,800
' As shown here: http://www.t1shopper.com/tools/calculate/file-size/result/?size=50&unit=gigabytes
``````

As an extension

``````Imports System.Runtime.CompilerServices

Module UnitExtension

Public Enum Units
B = 0
KB = 1 'kilo
MB = 2 'mega
GB = 3 'giga
TB = 4 'tera
PB = 5 'peta
EB = 6 'exa
ZB = 7 'zetta
YB = 8 'yotta
Auto = -1
End Enum
'compute max value of enum
Private ReadOnly maxU As Integer = [Enum].GetValues(GetType(Units)).Cast(Of Integer)().Max

'kFactor should be set according to your use
'see
'http://physics.nist.gov/cuu/Units/prefixes.html
'and
'http://physics.nist.gov/cuu/Units/binary.html
Private ReadOnly Kfactor As Integer = 1024 'or 1000

<Extension()>
Public Function ToUnit(ByVal theNumberToConvert As Object, _
Optional ByVal precision As Integer = 0, _
Optional ByVal whichUnit As Units = Units.Auto) As String

Dim _aNumber As Double = CType(theNumberToConvert, Double) 'the number being converted
Dim _fmt As String = "n" & precision.ToString 'format string

Dim _unit As Integer
If whichUnit = Units.Auto Then 'auto unit
_unit = CInt(Math.Floor(Math.Log(_aNumber, Kfactor))) 'yes
If _unit > maxU Then '> max unit
_unit = maxU 'use max unit
End If
Else
_unit = whichUnit 'no, force unit
End If

Dim _numberOfUnits As Double = _aNumber / (Kfactor ^ _unit) 'calculate number of units

Return String.Format("{0} {1}", _numberOfUnits.ToString(_fmt), CType(_unit, Units))
End Function

End Module
``````

edit:

An overload for unit to unit conversion

``````<Extension()>
Public Function ToUnit(ByVal theNumberToConvert As Object, _
fromUnit As Units, _
Optional ByVal precision As Integer = 0, _
Optional ByVal whichUnit As Units = Units.Auto) As String

Dim _aNumber As Double = CType(theNumberToConvert, Double) * (Kfactor ^ fromUnit) 'the number being converted
Dim _fmt As String = "n" & precision.ToString 'format string

Dim _unit As Integer
If whichUnit = Units.Auto Then 'auto unit
_unit = CInt(Math.Floor(Math.Log(_aNumber, Kfactor))) 'yes
If _unit > maxU Then '> max unit
_unit = maxU 'use max unit
End If
Else
_unit = whichUnit 'no, force unit
End If

Dim _numberOfUnits As Double = _aNumber / (Kfactor ^ _unit) 'calculate number of units

Return String.Format("{0} {1}", _numberOfUnits.ToString(_fmt), CType(_unit, Units))
End Function
``````
Source (Stackoverflow)