Formatting Mac Address in MS Access - ms-access-2010

Question

New to MS Access. Had a question regarding formatting of a MAC Address in one of my Access forms. There is a field I have set up using an input mask aa:aa:aa:aa:aa:aa;;a where users can manually enter a 48 bit hexidecimal address. e.x 11:44:5E:33:53:AF.
However sometimes there are missing values that occur in this data entry e.x 0:A:B:11:22:C (happens from time to time) but I would like be able to automatically fill the missing values with leading zeros to be like 00:0A:0B:11:22:0C.
I realize that this may not be possible through just MS Access Input masks, but all of the VBA codes and after updates code building I have been looking at so far have not lead me to the desired format.
Thanks for your time and appreciate any help in this!
I tried Format(fieldname, "00000000") code, but it just fills from the left-hand side instead of between the colons. e.x 00:00:0A:B1:12:2C instead of the desired 00:0A:0B:11:22:0C.

Answer 1

My function FormatMacAddress is for you:
' Formats a MAC address using one of the four de facto formats used widely.
' Thus, the format can and will be defined by the specified delimiter to use.
' The default is no delimiter and uppercase.
' Optionally, the case of the returned string can be specified as lowercase.
'
' Examples:
' None -> "1234567890AB"
' Dot -> "1234.5678.90AB"
' Dash -> "12-34-56-78-90-AB"
' Colon -> "12:34:56:78:90:AB"
'
' Lowercase -> "1234567890ab"
'
' 2019-09-23, Cactus Data ApS, Gustav Brock
'
Public Function FormatMacAddress( _
ByRef Octets() As Byte, _
Optional Delimiter As IpMacAddressDelimiter, _
Optional TextCase As VbStrConv = VbStrConv.vbProperCase) _
As String
Dim LastFrame As Integer
Dim ThisFrame As Integer
Dim FrameLength As Integer
Dim Index As Integer
Dim Symbol As String
Dim MacAddress As String
' Only accept an array with six octets.
If LBound(Octets) = 0 And UBound(Octets) = OctetCount - 1 Then
' Calculate the frame length.
FrameLength = DigitCount / DelimiterFrameCount(Delimiter)
' Format the octets using the specified delimiter.
For Index = LBound(Octets) To UBound(Octets)
ThisFrame = (Index * OctetLength) \ FrameLength
Symbol = ""
If LastFrame < ThisFrame Then
Symbol = DelimiterSymbol(Delimiter)
LastFrame = ThisFrame
End If
MacAddress = MacAddress & Symbol & Right("0" & Hex(Octets(Index)), OctetLength)
Next
End If
If MacAddress <> "" Then
Select Case TextCase
Case VbStrConv.vbLowerCase
MacAddress = StrConv(MacAddress, TextCase)
Case Else
' Leave MacAddress in uppercase.
End Select
End If
FormatMacAddress = MacAddress
End Function
As it requires a Byte() input, you may need the function MacAddressParse as well:
' Parses a string formatted MAC address and returns it as a Byte array.
' Parsing is not case sensitive.
' Will by default only accept the four de facto standard formats used widely.
'
' Examples:
' "1234567890AB" -> 1234567890AB
' "1234.5678.90AB" -> 1234567890AB
' "12-34-56-78-90-AB" -> 1234567890AB
' "12:34:56:78:90:AB" -> 1234567890AB
'
' If argument Exact is False, a wider variation of formats will be accepted:
' "12-34:56-78:90-AB" -> 1234567890AB
' "12 34 56-78 90 AB" -> 1234567890AB
' "56 78 90 AB" -> 0000567890AB
' "1234567890ABDE34A0" -> 1234567890AB
'
' For unparsable values, the neutral MAC address is returned:
' "1K34567890ABDEA0" -> 000000000000
'
' 2019-09-23, Cactus Data ApS, Gustav Brock
'
Public Function MacAddressParse( _
ByVal MacAddress As String, _
Optional Exact As Boolean = True) _
As Byte()
Dim Octets() As Byte
Dim Index As Integer
Dim Expression As String
Dim Match As Boolean
' Delimiters.
Dim Colon As String
Dim Dash As String
Dim Dot As String
Dim Star As String
' Create neutral MAC address.
ReDim Octets(0 To OctetCount - 1)
' Retrieve delimiter symbols.
Colon = DelimiterSymbol(ipMacColon)
Dash = DelimiterSymbol(ipMacDash)
Dot = DelimiterSymbol(ipMacDot)
Star = DelimiterSymbol(ipMacStar)
If Exact = True Then
' Verify exact pattern of the passed MAC address.
Select Case Len(MacAddress)
Case TotalLength1
' One frame of six octets (no delimiter).
Expression = Replace(Space(DigitCount), Space(1), HexPattern)
Match = MacAddress Like Expression
If Match = True Then
' MAC address formatted as: 0123456789AB.
End If
Case TotalLength3
' Three frames of two octets.
Expression = Replace(Replace(Replace(Space(DigitCount / FrameLength3), Space(1), Replace(Replace(Space(FrameLength3), Space(1), HexPattern), "][", "]" & Star & "[")), "][", "]" & Dot & "["), Star, "")
Match = MacAddress Like Expression
If Match = True Then
' MAC address formatted as: 0123.4567.89AB.
MacAddress = Replace(MacAddress, Dot, "")
End If
Case TotalLength6
' Six frames of one octets.
Expression = Replace(Replace(Replace(Space(DigitCount / FrameLength6), Space(1), Replace(Replace(Space(FrameLength6), Space(1), HexPattern), "][", "]" & Star & "[")), "][", "]" & Colon & "["), Star, "")
Match = MacAddress Like Expression
If Match = True Then
' MAC address formatted as: 01:23:45:67:89:AB.
MacAddress = Replace(MacAddress, Colon, "")
Else
Expression = Replace(Expression, Colon, Dash)
Match = MacAddress Like Expression
If Match = True Then
' MAC address formatted as: 01-23-45-67-89-AB.
MacAddress = Replace(MacAddress, Dash, "")
End If
End If
End Select
Else
' Non-standard format.
' Clean MacAddress and try to extract six octets.
MacAddress = Replace(Replace(Replace(Replace(MacAddress, Colon, ""), Dash, ""), Dot, ""), Space(1), "")
Select Case Len(MacAddress)
Case Is > DigitCount
' Pick leading characters.
MacAddress = Left(MacAddress, DigitCount)
Case Is < DigitCount
' Fill with leading zeros.
MacAddress = Right(String(DigitCount, "0") & MacAddress, DigitCount)
End Select
' One frame of six possible octets.
Expression = Replace(Space(DigitCount), Space(1), HexPattern)
Match = MacAddress Like Expression
If Match = True Then
' MAC address formatted as: 0123456789AB.
End If
End If
If Match = True Then
' Fill array Octets.
For Index = LBound(Octets) To UBound(Octets)
Octets(Index) = Val("&H" & Mid(MacAddress, 1 + Index * OctetLength, OctetLength))
Next
End If
MacAddressParse = Octets
End Function
Full code at GitHub: VBA.MacAddress.