Find location of a short sequence of bytes in byte array

Question

How can I efficiently find the location of the first instance of a four byte sequence within a byte array? Is there something more efficient than looping through the whole array, or a built-in method?

I'm searching through a byte array for a pair of CrLF. I can't convert it to string for an InStr first because I need the position of it in the original byte array.

I am trying to figure out the location of this, as it delimits between a string portion and a binary portion, similar (well, exactly like for this part of it) to an HTTP header. There is a string portion, and two CrLf before the content begins.

You'll need to convert some examples to vb (or just use them in a referenced C# project), but some good alternatives are here: http://stackoverflow.com/questions/283456/byte-array-pattern-search. — rsenna, Jan 15 '11 at 22:19

score 1 · Answer 1 · answered Jan 15 '11 at 22:05

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Assuming nothing about the data set (sorted/special ordering) the best you can do is an O(n) algorithm, which means looking through the whole array once.

answered Jan 15 '11 at 22:05

helloworld922

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Ok, that answers my question. Thank you! – Brad Jan 15 '11 at 22:10

score 1 · Accepted Answer · edited Jun 20 '20 at 09:12

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You may use Boyer-Moore's algorithm, which is better than linear in the average.

HTH!

edited Jun 20 '20 at 09:12

Community

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answered Jan 15 '11 at 22:20

Dr. belisarius

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Find location of a short sequence of bytes in byte array

2 Answers2