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Re^3: Another Pattern Matching Question

by kcott (Canon)
on Oct 12, 2012 at 19:27 UTC ( #998777=note: print w/replies, xml ) Need Help??


in reply to Re^2: Another Pattern Matching Question
in thread Another Pattern Matching Question

Your solution which adds R? to the original regex was on the right track and achieves what you want, albeit poorly:

$ perl -Mstrict -Mwarnings -E 'my $fileName; my $re = qr{3B4[0|1|2]RT\.\d{10}\.\d+R?\.bin}; $fileName = "3B40RT.2000033121.7.bin.gz"; say +($fileName =~ /$re/) ? "match" : "no match"; $fileName = "3B40RT.2000033121.7R.bin.gz"; say +($fileName =~ /$re/) ? "match" : "no match"; ' match match

I don't think you understand character classes or alternation (perhaps both). Where you're trying to match a 0, 1 or 2 in the same position, [0-2] would be far better than [0|1|2] (which is trying to match a 0, pipe, 1, pipe or 2 in the same position) - the 2nd pipe is redundant and the 1st pipe isn't wanted anyway. So, here's an improved version:

$ perl -Mstrict -Mwarnings -E 'my $fileName; my $re = qr{3B4[0-2]RT\.\d{10}\.\d+R?\.bin}; $fileName = "3B40RT.2000033121.7.bin.gz"; say +($fileName =~ /$re/) ? "match" : "no match"; $fileName = "3B40RT.2000033121.7R.bin.gz"; say +($fileName =~ /$re/) ? "match" : "no match"; ' match match

Recommended reading:

-- Ken

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[1nickt]: my $x = $aohoaoh->[0]->{' foo'}->[0]->{'bar' }; should work
[thepkd]: not indexing
[thepkd]: getting data out of the ds
[choroba]: it depends. Give more details, please
[thepkd]: i used a series of {}'s but it dont work
[choroba]: You need square brackets for arrays
[GotToBTru]: you can certainly construct a single expression to access any part of the data structure, without using temp variables. but you might make it easier on yourself and any other poor soul who has to understand your code if you do
[thepkd]: to dereference i mean
LanX .oO( oh tempz, oh moretz)
[thepkd]: @GotToBTru Sure. But.

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