convert Hex to Byte

dalz · Joined: 04 Oct 2007 Posts: 3

Hi,

I'm new in VB6
Anybody knows how to convert Hex to Byte??

Thank you

Archived from group: microsoft>public>vb>syntax

Sinna · Joined: 04 Oct 2007 Posts: 191

dalz wrote:
> Hi,
>
> I'm new in VB6
> Anybody knows how to convert Hex to Byte??
>
> Thank you
>
Perhaps this is not very clean code, but for me it works like a charm:

Dim lData As Long
Dim sHexData As String

sHexData = "FF" 'just initialize to some value

lData = CLng("&H" & sHexData)

Just make sure you check for possible buffer overflows, e.g. passing
"1FFFFFFFF" to the code mentioned above will fail as it is larger than a
Long. Also ensure the string you pass in only contain 0..9 and/or A..F
characters. Look for the Like operator if you want to cope with this.

Sinna

dalz · Joined: 04 Oct 2007 Posts: 3

It works..thanks a lot Sinna

Do u know about set key A or B like A0A1A2A3.... for authentication?
I don't understand about this set key. I'm doing project using smart card
reader
Before we can read the data in the card, we need to do authentication first.
I'm still confuse how to set this key and doing the authentication.

Thank you so much

dalz · Joined: 04 Oct 2007 Posts: 3

dalz wrote:
>It works..thanks a lot Sinna
>
>Do u know about set key A or B like A0A1A2A3.... for authentication?
>I don't understand about this set key. I'm doing project using smart card
>reader
>Before we can read the data in the card, we need to do authentication first.
>I'm still confuse how to set this key and doing the authentication.
>
>Thank you so much

how about hex to dec? for 16bytes
example 3A 25 00 00 C5 DA FF FF 3A 25 00 00 00 FF 00 FF
I use this code
Text1.Text=3A2500C5DAFFFF3A25000FF0FF
Text2.Text =Val("&H"+Text1.Text)

but there's error msg overflow
so what should I do?
Thank you

Tony Proctor · Joined: 04 Oct 2007 Posts: 1051

Try this...

Private Sub Command1_Click()
Dim i As Integer

Text2.Text = ""
For i = 1 To Len(Text1.Text) - 1 Step 2
Text2.Text = Text2.Text & CStr(CByte("&h" & Mid$(Text1.Text, i, 2)))
& " "
Next i
End Sub

Private Sub Form_Load()
Text1.Text = "3A2500C5DAFFFF3A25000FF0FF"
End Sub

Tony Proctor

"dalz" wrote in message @uwe...
> dalz wrote:
> >It works..thanks a lot Sinna
> >
> >Do u know about set key A or B like A0A1A2A3.... for authentication?
> >I don't understand about this set key. I'm doing project using smart card
> >reader
> >Before we can read the data in the card, we need to do authentication
first.
> >I'm still confuse how to set this key and doing the authentication.
> >
> >Thank you so much
>
>
>
>
> how about hex to dec? for 16bytes
> example 3A 25 00 00 C5 DA FF FF 3A 25 00 00 00 FF 00 FF
> I use this code
> Text1.Text=3A2500C5DAFFFF3A25000FF0FF
> Text2.Text =Val("&H"+Text1.Text)
>
> but there's error msg overflow
> so what should I do?
> Thank you
>

Sinna · Joined: 04 Oct 2007 Posts: 191

dalz wrote:
> dalz wrote:
>> It works..thanks a lot Sinna
>>
>> Do u know about set key A or B like A0A1A2A3.... for authentication?
>> I don't understand about this set key. I'm doing project using smart card
>> reader
>> Before we can read the data in the card, we need to do authentication first.
>> I'm still confuse how to set this key and doing the authentication.
>>
>> Thank you so much
>
>
>
>
> how about hex to dec? for 16bytes
> example 3A 25 00 00 C5 DA FF FF 3A 25 00 00 00 FF 00 FF
> I use this code
> Text1.Text=3A2500C5DAFFFF3A25000FF0FF
> Text2.Text =Val("&H"+Text1.Text)
>
> but there's error msg overflow
> so what should I do?
> Thank you
>
What about this?

Dim sText As String: sText = "00 11 AA FC DD EE 34"

Dim sData() As String, bData() As Byte
Dim iByte As Long, lByteCount As Long
sData = Split(Trim(sText), " ")
lByteCount = UBound(sData) + 1

ReDim bData(lByteCount - 1) As Byte

For iByte = 0 To lByteCount - 1
bData(iByte) = CByte("&H" & sData(iByte))
Next iByte

Sinna

dalz via VBMonster.com · Joined: 04 Oct 2007 Posts: 7

Thanks a lot to u both..It's working
I just have to figured out the set key now. Many thanks

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dalz via VBMonster.com · Joined: 04 Oct 2007 Posts: 7

Now I can read the card Serial Number
The problem is the card Serial Number should be 3851693428
but my result is 11636

3851693428 and 11636 are having same Hex = 2D74
What should I do to have the result 3851693428 from 2D74?
Thanks a lot...

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"Rick Rothstein \ · Joined: 04 Oct 2007 Posts: 1584

> Then how to convert this E5942D74 to 3851693428?

You can use this function which will handle up to a 96-bit number...

Function Hex2Dec(ByVal HexString As String) As Variant
Dim X As Integer
Dim BinStr As String
If Left$(HexString, 2) Like "&[hH]" Then
HexString = Mid$(HexString, 3)
End If
If Len(HexString) <= 12 Then
Const BinValues = "0000000100100011" & _
"0100010101100111" & _
"1000100110101011" & _
"1100110111101111"
For X = 1 To Len(HexString)
BinStr = BinStr & Mid$(BinValues, _
4 * Val("&h" & Mid$(HexString, X, 1)) + 1, 4)
Next
For X = 0 To Len(BinStr) - 1
Hex2Dec = Hex2Dec + Val(Mid(BinStr, _
Len(BinStr) - X, 1)) * 2 ^ X
Next
Else
' Number is too big, handle error here
End If
End Function

Rick

Larry Serflaten · Joined: 04 Oct 2007 Posts: 2644

"Rick Rothstein (MVP - VB)" wrote
>
> You can use this function which will handle up to a 96-bit number...

Deja vu, why do two conversions when only one is needed?

LFS

Private Function Hx2Dec(ByRef Hexidecimal As String) As Variant
' Converts up to 24 hexidecimal characters to a decimal value
Dim idx As Long
Dim hx As String
Const code = "123456789ABCDEF"

hx = UCase$(Hexidecimal)

' Remove &H prefix and leading 0's
idx = 1
Do
Select Case Mid(hx, idx, 1)
Case "&", "H", "0"
idx = idx + 1
Case Else
Exit Do
End Select
Loop
hx = Mid$(hx, idx)

' Validate input
If hx Like "*[!0-9A-F]*" Then Exit Function

' Check size
idx = Len(hx)
If idx > 24 Then Exit Function

' Convert
Hx2Dec = CDec(0)
Do While idx > 0
Hx2Dec = (Hx2Dec * 16) + (InStr(code, Mid$(hx, idx, 1)))
idx = idx - 1
Loop

End Function

dalz via VBMonster.com · Joined: 04 Oct 2007 Posts: 7

Rick Rothstein (MVP - VB) wrote:
>> Then how to convert this E5942D74 to 3851693428?
>
>You can use this function which will handle up to a 96-bit number...
>
>Function Hex2Dec(ByVal HexString As String) As Variant
> Dim X As Integer

------------------

Thanks a lot all..It's working

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