HEX char -- > its comlement

[pamelafluente]

Hi
what is the smartest function that maps the char on the left to
the char on the right (I want to complement an hexadecimal string,
like making a negative color).

0 -f
1 -e
2 -d
3 -c
4 -b
5 -a
6 -9
7 -8
8 -7
9 -6
a or A -5
b or B -4
c or C -3
d or D -2
e or E -1
f or F -0

If there is something able to map in one shot a whole string
to its "complement" would be even better.

-Pam

[Branco Medeiros]

pa***********@libero.it wrote:

Hi
what is the smartest function that maps the char on the left to
the char on the right (I want to complement an hexadecimal string,
like making a negative color).

0 -f
1 -e
2 -d
3 -c
4 -b
5 -a
6 -9
7 -8
8 -7
9 -6
a or A -5
b or B -4
c or C -3
d or D -2
e or E -1
f or F -0

If there is something able to map in one shot a whole string
to its "complement" would be even better.

You can use the Not operator (which complements the bits of a given
integer) or Xor the integer value with -1, whichever you prefer.
Anyway, you must convert back and forth, from hex to integer to hex
again...

Function NegHex(ByVal Hex As String) As String
'Converts the hex value to integer
Dim V As Int32 = Convert.ToInt32(Hex, 16)

'Defines a mask to the minimum number of chars expected
Dim S As Integer = Hex.Length
Dim Mask As String = String.Format("x{0}", S)

'Inverts the value and converts it back to hex, extracting just
'the number of chars presented in the original string
Return Right((V Xor -1).ToString(Mask), S)

'The above might as well be the following
'Return Right((Not V).ToString(Mask), S)

End Function

HTH.

Regards,

Branco.

[Martin Honnen]

pa***********@libero.it wrote:

0 -f
1 -e
2 -d
3 -c
4 -b
5 -a
6 -9
7 -8
8 -7
9 -6
a or A -5
b or B -4
c or C -3
d or D -2
e or E -1
f or F -0

If there is something able to map in one shot a whole string
to its "complement" would be even better.

One way is like this

Dim S As String = "0123456789ABCDEF"
Console.WriteLine(S)
For Each C As Char In S
Console.Write("{0:X}", (Not Integer.Parse(C.ToString(),
Globalization.NumberStyles.AllowHexSpecifier) And 15))
Next

if I understand what you want correctly.

--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/

[pamelafluente]

Dim S As String = "0123456789ABCDEF"

Console.WriteLine(S)
For Each C As Char In S
Console.Write("{0:X}", (Not Integer.Parse(C.ToString(),
Globalization.NumberStyles.AllowHexSpecifier) And 15))
Next

Function NegHex(ByVal Hex As String) As String
'Converts the hex value to integer
Dim V As Int32 = Convert.ToInt32(Hex, 16)

....

Beautiful. Thanks you very much, Branco and Martin. Both these solution
look very smart. I like them.

-P