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Topic: C question, loops

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WDef

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Joined: Sep. 2005

Posted: Jan. 18 2008,17:11

if (($max ge 3) && ($result =~ /$c{3}$/)) {

should have been (I think)

if (($max >= 3) && ($result =~ /$c{3,}$/)) {

[EDIT: classic mistake confusing string and numeric comparisons ]

If that didn't work would have applied a regex somewhere like:

=~ /(.)\1\1/

which would match any string containing 3 or more identical adjacent chars.

You might notice the similarity to sed syntax. Perl regex's are much easier and more intuitive and you do a lot less escaping of backslashes and brackets and other hassles.

curaga

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Posted: Jan. 18 2008,17:24

Is the new algorithm guaranteed to try every combination?

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Windows is not a virus. A virus does something!

WDef

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Posted: Jan. 18 2008,17:31

AKAIK - it's taken from the Algorithm::Permute man page, basically just put in a loop to do all string lengths between 1 and the number of elements in @set.

There's also benchmarks on the man page comparing speeds to other implementations.

There may possibly be a faster way of using the module via the callback interface but I'll have to think and maybe post somewhere about that. [ EDIT I doubt it . The callback thing won't take a perm length argument, and the man page warns against trying to change the array mid execution. ]

EDIT: I've updated the above to allow for setting desired string length ranges.

WDef

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Posted: Jan. 20 2008,12:26

Yesterday I had a crack at a version using threads, but there were segfaults - I think Algorithm::Permute is probably not thread-safe. Googling reveals this is likely since (a) any module that does not explicitly state it is thread-safe should be assumed not to be, and (b) it's written in XS code and XS code modules are less likely to be thread-safe.

Anyway I have some other improvements in mind for speed increases.

curaga

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Joined: Feb. 2007

Posted: Jan. 29 2008,18:32

The smaller ones have run through - aka all under 7 chars. That proved my pass isn't 7 chars or less. Oh well.

Then I did a quick reschedule - new dial is:
8-9, 10-11, 12-13, 14-15, 16-17, 18-19, 20-21, 22-23; that is, one process goes through two lengths, instead of one going from 8 to 23. These are all running on the main lappy - load averages have floated above 15 for some time now

I haven't yet applied the fix for adjacent chars, maybe I should have? Haven't had time.

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There's no such thing as life. Those mean little jocks invented it ;)
-
Windows is not a virus. A virus does something!

64 replies since Jan. 12 2008,13:35

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Damn Small Linux Board » Non-DSL Topics » Programming and Scripting » C question