Android Question Byte Arrays

[mikimoto]

Good morning,
i am new to B4A and already with a Problem.
I can not find out how Byte Arrays are working, may someone can help ?
I have to convert the parity and find the checksum.
in vb.net i use this function:

Private Function AddParity(ByVal _in As String) As Byte()
Dim item As Byte = &HFF
Dim p_par As Byte = &HD
Dim list As New List(Of Byte)
Dim encoding As New ASCIIEncoding
Dim num2 As Byte
For Each num2 In encoding.GetBytes((_in & Chr(10) & Chr(10) & Chr(10)))
item = CByte((item Xor num2))
list.Add(num2)
Next
item = CByte((item Xor p_par))
list.Add(p_par)
list.Add(item)
Return list.ToArray
End Function
wich is working fine.
in B4A i am struggeling with the this:

Sub AddParity(Inn As String) As Byte()
Dim bconv As ByteConverter
Dim item As Byte
item =0xFF ' &H7F
Dim p_par As Byte = 0x0d
Dim List1() As Byte
Dim encodeing() As Byte
encodeing = (Inn & Chr(10) & Chr(10) & Chr(10)).getbytes("ASCII")
'Dim num2 As Byte
For Each num2 As Byte In encodeing
item = Bit.Xor(item, num2)
List1.Add(num2)
Next
item = Bit.Xor( item , p_par)
List1.Add(p_par)
List1.Add(item)
Return List1
End Sub
the result from this function should send data to a Serial device by

astreams.Write2(buffer,0,buffer.Length )


Thanks for help.

 

[mikimoto]

strange behavior ?
when i read the buffer values have changed ??

Dim buffer() As Byte = Array As Byte (108,68,116,116,10,10,10,13,208)

the last Byte 208 converts to -48 ? Why ??

 

[KitCarlson]

I think the byte type is signed, not unsigned. It is because that is what is used in java. I think an int, might be used since the positive range goes to 32,767, and the byte as positive only to 127. I have not tried myself.

 

[wl]

Yes, bytes are signed which is often bit annoying.

Please look at how to deal with this at: http://www.b4x.com/android/forum/threads/signed-bytes-and-usb.15220/#post-86475