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Re^2: Parsing/regex help required

by Anonymous Monk
on Sep 27, 2021 at 14:02 UTC ( #11137040=note: print w/replies, xml ) Need Help??

in reply to Re: Parsing/regex help required
in thread Parsing/regex help required

Thanks, how to make this conditional, either hyphen (-) or I want to say en dash()? \s+-\s+    # some space, a hyphen and more space

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Re^3: Parsing/regex help required
by kcott (Archbishop) on Sep 28, 2021 at 07:50 UTC
    "how to make this conditional, either hyphen (-) or I want to say en dash()?"

    Just replace the single hyphen in your regex with a character class containing all possible dashes, hyphens, etc. In the character class, always put an ASCII hyphen as the last character or you'll generate a range. See perlrecharclass and, in particular, the "Bracketed Character Classes" section for much more detailed information.

    An example script follows but, first, some notes:

    • The open pragma indicates that output to stdout should use UTF-8. This also avoids the "Wide character in print ..." warning.
    • I've used a mix of \x{...} and \N{...} to show some alternatives. Don't do this in your real code as it's likely to be confusing: pick one format and stick with that.
    #!/usr/bin/env perl use strict; use warnings; use open OUT => qw{:encoding(UTF-8) :std}; my ($en_dash, $em_dash) = ("\x{2013}", "\N{EM DASH}"); my $str = "a-b${en_dash}c${em_dash}d"; my $re = qr{[\N{EN DASH}\x{2014}-]}; print "Original string: $str\n"; print "Parts separated by some dash:\n"; print "$_\n" for split $re, $str;


    Original string: a-bcd Parts separated by some dash: a b c d

    Because the hyphen and dashes are not easily distinguishable, here's the same output piped through cat -vet. Don't worry too much if you don't understand the codes; just notice that they are different.

    $ ./ | cat -vet Original string: a-bM-bM-^@M-^ScM-bM-^@M-^Td$ Parts separated by some dash:$ a$ b$ c$ d$

    See also these Unicode® resources: the PDF "Code Chart: General Punctuation -- Range: 2000206F"; and, for characters referenced therein but not in that range, "Unicode 14.0 Character Code Charts" (note the "Find chart by hex code:" near the top of the page).

    — Ken

Re^3: Parsing/regex help required
by Marshall (Canon) on Sep 28, 2021 at 02:07 UTC
    Perhaps you mean "em dash" instead of "en dash"?
    This is called "em" because it is similar to the with of "M" in a variable width font.
    An en dash is shorter, like the width of the letter "n"

    In any event, you will have to be reading using UTF-8 encoding. My dev environment for Perl only can do ASCII. I cannot easily write code for this.

    As far as regex goes:
    You need to group an or'd expression something like this (-|em_dash)
    To make it "non capturing", (?:-|em_dash);

    The question is what "em_dash" should be and how that relates to how the data decoding that was used during the read.

    update: under some coding scenarios an em dash is \x{2014}.
    I think you need "use utf8;" for that to work, but I am not sure.

    Some Monks here are quite experienced with utf8 encoding.
    Bring it on!

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