Re: Finding a pattern in a stream?

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From: Jay B. Harlow [MVP - Outlook] (Jay_Harlow_MVP_at_msn.com)
Date: 11/03/04 

Date: Wed, 3 Nov 2004 09:11:57 -0600

Terry,
You would need to check each read to see if it contains the characters you
are looking for. Be careful, depending on how you defined the "Read" your
characters may be spread across two reads.

InStr allows you to find a fixed set of characters a "word".

RegEx allows you to find a pattern (a variable set of characters), the Like
operator is a simplified form of RegEx.

For example: The "^\d+$" RegEx pattern says to find the beginning of the
line/string "^" followed by one or more "+" digits "\d", followed by the end
of the line/string "$"

A tutorial & reference on using regular expressions:
http://www.regular-expressions.info/

The MSDN's documentation on regular expressions:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/cpconRegularExpressionsLanguageElements.asp

Hope this helps
Jay

"Terry Olsen" <tolsen64@hotmail.com> wrote in message
news:%23t2yQ6awEHA.2540@TK2MSFTNGP09.phx.gbl...
> Just doing a quick read of the page it looks as though Regex functions
> similarly to the InStr() function. Is Regex actually faster and more
> efficient than using InStr?
>
> Also, how would I find my pattern if it is broken up into two "reads"?
> For example, I wait for a DataArrival event, read from the serial port and
> pass the data out the TCP port. Say the string i'm looking for is
> "+++ATH". So I read the serial port and receive "<other data>+++A" and
> then on the next read of the serial port I get "TH<more data>". Or maybe
> it could conceivably be broken up into 3 or more reads. Is this a
> situation where I just have to concatenate the current read with the
> previous read and then look for the pattern? Or is there a better way?
>
> Thanks for the help.
> Terry
>
> "Ken Tucker [MVP]" <vb2ae@bellsouth.net> wrote in message
> news:OS2b0jZwEHA.2540@TK2MSFTNGP09.phx.gbl...
>> Hi,
>>
>> Regular expression are the best way to find patterns.
>> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconCOMRegularExpressions.asp
>>
>> Ken
>> -----------------------------
>> "Terry Olsen" <tolsen64@hotmail.com> wrote in message
>> news:%239qzs1WwEHA.2192@TK2MSFTNGP14.phx.gbl...
>> Is there a good way to find a pattern of bytes/chars in a stream? I've
>> got
>> a serial port connected to a tcp port. I need to be able to catch a
>> unique
>> character string in the stream so that I can perform certain functions.
>> For
>> example, I have a telnet client connected to an Apple II through the
>> serial
>> port. The user at the telnet terminal is using the BBS running on the
>> Apple
>> II just like the good ole days of dialup BBS's. I need to be able to
>> catch
>> a "command string" sent out from the Apple II (like the "+++ATH") that
>> tells
>> my app to disconnect the telnet client (in lieu of the modem hanging up).
>> Is there a good way to do this?
>>
>>
>>
>
>

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