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in reply to Combining multiple =~ s/

Let Perl generate the regular expression from a hash containing the list of words and their replacements: 
my %trans = (zero  => 0,
             one   => 1,
             two   => 2,
             three => 3);

my $words_re = join "|", map quotemeta, keys %trans;
$string =~ s/($words_re)/$trans{lc $1}/ig;

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Re^2: Combining multiple =~ s/
by Corion (Patriarch) on Mar 07, 2021 at 19:10 UTC

    You want to sort the words in the regular expression by descending length :) Or alternatively, use \b to match only whole words:

    my %trans = (zero  => 0,
             one   => 1,
             ones  => 11,
             two   => 2,
             three => 3);

my $words_re = join "|", map quotemeta, sort { length($b) <=> length($
+a) } keys %trans;
$string =~ s/\b($words_re)\b/$trans{lc $1}/ig;

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    Otherwise, it could be that one matches before ones.

    Update: choroba spotted that the length($b) and length($a) were missing

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      It might be worth pointing out the CPAN module Data::Munge which has a function list2re to make a list-matching regex. This line is basically what you need: 

         my $re = join '|', map quotemeta, sort {length $b <=> length $a || 
+$a cmp $b } @_;

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      There is also this, which is what I use.

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Re^2: Combining multiple =~ s/
by LanX (Saint) on Mar 07, 2021 at 20:44 UTC
    Nitpick! :)

    This is semantically not the same, even if sorted.

    Tho probably what the OP wants, if it's really about numbers

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery

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