Re: How is this conditional able to execute?


"Stephany Young" <noone@localhost> wrote in message
news:uYXW0%23ARFHA.3364@xxxxxxxxxxxxxxxxxxxxxxx
> This is getting scary :)
>
> Lets take this one step at a time.
>
> I'm a bit perplexed as to why a recieve buffer would be such a strange
> size. Could it be that the value of tcpClient.ReceiveBufferSize is
> actually 8192 (8KB)? If so, then the array declaration should be:
>
> Dim bytes(tcpClient.ReceiveBufferSize - 1) As Byte

Yes - it is 8192 after putting in the above code.

>
> In VB.NET, arrays are 0 based and the value specified is the upper bound
> of the array as opposed to the number of elements (as in C#.NET).
>
> Can you dump the first 50 bytes of the array on the first call. Directly
> after the line:
>
> networkStream.Read(bytes, 0, tcpClient.ReceiveBufferSize)
>
> insert:
>
> For _i As Integer = 0 to 48
> Console.Write("{0},", bytes(_i).ToString())
> Next
> Console.WriteLine("{0}", bytes(_i).ToString())
>
> Add another line:
>
> Console.WriteLine()
>
> and place a breakpoint on this line.
>
> Run the code then copy and paste the result into a post to this thread.

When returndata is "", the above code gives this:

0,78,111,116,104,105,110,103,32,116,111,32,87,114,105,116,101,32,102,114,111,109,58,32,68,101,118,101,108,111,112,109,101,110,116,51,0,0,0,0,0,0,0,0,0,0,0,0,0,0

>
> It will be interesting to see just what characters are arriving.
>
> A new byte array is created each time the networkStream object is read so
> there is nothing from the previous red remaining. Therefore the comment
> about the 'values shifting' is a red herring. What you are getting is
> actually what is coming from the networkStream object.
>
> Also, is there any particular reason why you are using UTF8 encoding to
> interpret the data? Is it specified somewhere that the data arriving in
> the networkStream object is actually UTF8 or is just a stab in the dark?

Yes - I read on experts-exchange.com that this would work with Trim but it
didn't. I never removed it because it didn't seem to make a difference.

On the listener, I haven't declared a size that should be 8KB. I do this:

Dim networkStream As NetworkStream =
tcpClientObj.GetStream()
' Read the stream into a byte array
Dim bytes(tcpClientObj.ReceiveBufferSize) As Byte

If networkStream.DataAvailable() Then
networkStream.Read(bytes, 0,
CInt(tcpClientObj.ReceiveBufferSize))

Dim mystring As String = Encoding.UTF8.GetString(bytes)

Dim sendBytes_ As [Byte]() =
Encoding.ASCII.GetBytes(mystring)

networkStream.Write(sendBytes_, 0, sendBytes_.Length)
sendBytes_.Clear(sendBytes_, 0, sendBytes_.GetLength(0))

>
>
> "Brett" <no@xxxxxxxx> wrote in message
> news:%23aS0EDARFHA.2744@xxxxxxxxxxxxxxxxxxxxxxx
>>I tried this but it isn't working either. At one point, the bytes array
>>has non zero elements up to element 35. returndata has the value of ""
>>(or so it seems) and length of 8193, same as the bytes array. Through
>>each pass of the loop, the non zero elements increase in the bytes array.
>>So it goes from element 35 to 36, 37 and so on. The values are shifting
>>so that the first 10 are now zero. Then the first 11, 12, 13 and so on.
>>
>> Any other suggestions?
>>
>> Thanks,
>> Brett
>>
>> "Stephany Young" <noone@localhost> wrote in message
>> news:u1TlDb9QFHA.2680@xxxxxxxxxxxxxxxxxxxxxxx
>>> Sorry, my mistake. Null (Chr(0)) is not treated as whitespace by the
>>> String.Trim Method.
>>>
>>> Instead, you can can use one of the overloaded String.Trim methods.
>>>
>>> Dim returndata As String =
>>> Encoding.UTF8.GetString(bytes).Trim(Char.MinValue)
>>>
>>> Char.MinValue is a constant for 0x00 which equates to Null or Chr(0).
>>>
>>> This overload removes all occurrences of a set of characters specified
>>> in an array from the beginning and end of the string instance.
>>>
>>>
>>> "Brett" <no@xxxxxxxx> wrote in message
>>> news:uPLcAZ6QFHA.3988@xxxxxxxxxxxxxxxxxxxxxxx
>>>>
>>>> "Stephany Young" <noone@localhost> wrote in message
>>>> news:%23hNf834QFHA.3988@xxxxxxxxxxxxxxxxxxxxxxx
>>>>> What test are you using to determine that returndata.ToString = ""?
>>>>>
>>>>> Are you , for example, executing a:
>>>>>
>>>>> Console.Writeline("returndata.ToString = " & returndata.ToString)
>>>>>
>>>>> and getting the result:
>>>>>
>>>>> returndata.ToString =
>>>>>
>>>>> Your comment about returndata 'always' being 8193 bytes gives us the
>>>>> clue as what is happening.
>>>>>
>>>>> I suspect that returndata is padded with null characters (chr(0)).
>>>>>
>>>>> The Trim function (aka Microsoft.VisualBasic.Trim) only 'trims'
>>>>> leading and trailing Space characters.
>>>>>
>>>>> The String.Trim Method 'trims' leading and trailing whitespace
>>>>> characters. 'whitespace' comprises a number of characters including
>>>>> the null character (chr(0)).
>>>>>
>>>>> I think that if you change the line:
>>>>>
>>>>> Dim returndata As String = Trim(Encoding.UTF8.GetString(bytes))
>>>>>
>>>>> to
>>>>>
>>>>> Dim returndata As String = Encoding.UTF8.GetString(bytes).Trim()
>>>>>
>>>>> then the test will work correctly.
>>>>
>>>> That doesn't work either. In some cases, bytes will come in as a zero
>>>> byte array with length 8193. Every element in that array will be zero.
>>>> returndata is assigned and its length becomes 8193 as well.
>>>>
>>>>
>>>
>>>
>>
>>
>
>


.

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