Re: Faster way to parse binary stream

If the entire string (after the first 'no of strings' byte) is made up length/string pairs, then (subject to using an unenbalmed version of Perl) let unpack take care of it. Ignore/skip the first byte and use the ()repeat pattern to deal with it. Eg:

$count = 3;
$str1 = "First string";
$str2 = "Second string";
$str3 = "Third string";
$bytes = pack("C C A* C A* C A*", $count, length($str1),
   $str1, length($str2), $str2, length($str3), $str3);;

print for unpack 'x(c/a*)*', $bytes;;
First string
Second string
Third string
[download]

If there is other stuff following the strings, then you'll need to unpack the first byte and then generate the pattern:

$n = unpack 'C', $bytes;;

print for unpack 'x (c/a*)' . $n, $bytes;;
First string
Second string
Third string
[download]

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

Comment on Re: Faster way to parse binary stream Select or Download Code

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Re^2: Faster way to parse binary stream by ikegami (Patriarch) on Jun 19, 2007 at 20:29 UTC
You can even combine the two calls to `unpack`: `my @strings = unpack 'c/(c/a*)', $bytes;` [download]	[reply] [d/l] [select]
Re^3: Faster way to parse binary stream by BrowserUk (Patriarch) on Jun 19, 2007 at 21:29 UTC
Cool++ Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^2: Faster way to parse binary stream by Roy Johnson (Monsignor) on Jun 19, 2007 at 20:29 UTC
I hadn't seen the slash template item before. To quote from the docs: The / template character allows packing and unpacking of strings where the packed structure contains a byte count followed by the string itself. You write length-item/string-item. Good solution, BrowserUK. Caution: Contents may have been coded under pressure.	[reply]
Re^3: Faster way to parse binary stream by Anonymous Monk on Jun 19, 2007 at 21:27 UTC
Thanks to all who replied - the "C/(C/A)" looks like the way to go :)	[reply]


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