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Re^2: How to match last character of string, even if it happens to be a newline?

by Allasso (Monk)
on May 12, 2019 at 15:58 UTC ( #1233654=note: print w/replies, xml ) Need Help??


in reply to Re: How to match last character of string, even if it happens to be a newline?
in thread How to match last character of string, even if it happens to be a newline?

Not quite:
$text_1 = "abc\nd"; $text_1 =~ m/.*(.|\n)/; print("----------\n>" . $1 . "<\n");
Prints:
---------- > <
Should print d

Replies are listed 'Best First'.
Re^3: How to match last character of string, even if it happens to be a newline?
by AnomalousMonk (Chancellor) on May 12, 2019 at 17:58 UTC
    $text_1 = "abc\nd";
    $text_1 =~ m/.*(.|\n)/;
    ...
    Should print d

    A narration of  m/.*(.|\n)/ might be:

    1. .*     From the start of the string, grab as much as possible of anything that's not a newline (no /s modifier for dot);
    2. (.|\n) Then match and capture the first thing that's either not-a-newline or a newline.
    Looked at this way, the only thing that could possibly be captured in the given string would be a newline.

    Indeed, if your regex has no operator introduced after Perl version 5.6, this kind of narration is what YAPE::Regex::Explain will give you:

    c:\@Work\Perl\monks>perl -wMstrict -le "use YAPE::Regex::Explain; print YAPE::Regex::Explain->new(qr/.*(.|\n)/)->explain(); " The regular expression: (?-imsx:.*(.|\n)) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- .* any character except \n (0 or more times (matching the most amount possible)) ---------------------------------------------------------------------- ( group and capture to \1: ---------------------------------------------------------------------- . any character except \n ---------------------------------------------------------------------- | OR ---------------------------------------------------------------------- \n '\n' (newline) ---------------------------------------------------------------------- ) end of \1 ---------------------------------------------------------------------- ) end of grouping ----------------------------------------------------------------------
    (There are newer and better regex parser/explainers around, but I like this one, limited as it is, for its explanatory style.)


    Give a man a fish:  <%-{-{-{-<

Re^3: How to match last character of string, even if it happens to be a newline?
by LanX (Archbishop) on May 12, 2019 at 16:20 UTC
    > Not quite: ... "abc\nd"

    in this case two options with /s modifier

    DB<11> m/.*(.|\n)/s,print "<$1>" for "123","abc\n","abc\nd" <3>< ><d> DB<12> m/.*(.)/s,print "<$1>" for "123","abc\n","abc\nd" <3>< ><d> DB<13>

    HTH!

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

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