I will be very thankful if you can also explain to me the other metacharacters like + , * , (.) and backreferences

perlretut is a good start. For your question:

coacomacommacommmacommmma
/com?a/✔✔✘✘✘
/com*a/✔✔✔✔✔
/com+a/✘✔✔✔✔
/co(mm)?a/✔✘✔✘✘
/co(m|mmm)a/✘✔✘✔✘
/com{2}a/✘✘✔✘✘
/com{0,2}a/✔✔✔✘✘
/com{2,3}a/✘✘✔✔✘
/com{3,}a/✘✘✘✔✔
use warnings;
use strict;
use HTML::Tiny;
 
my @tests = map { 'co'.('m'x$_).'a' } 0..4;
my @regexes = do { no warnings 'qw'; qw/ com?a com*a com+a co(mm)?a
    co(m|mmm)a com{2}a com{0,2}a com{2,3}a com{3,}a / };

my $h = HTML::Tiny->new;
print $h->table( {border=>1,cellpadding=>3,cellspacing=>0},
    [ \'tr',
        [ \'td', '', map { $h->code($_) } @tests ],
        map( { my $r=$_;
            [ \'td', $h->code("/$r/"),
                map( { /$r/
                    ? $h->tag('font', {color=>'green'}, '✔')
                    : $h->tag('font', {color=>'red'}, '✘')
                    } @tests ),
            ]
        } @regexes ),
    ] );

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In reply to Re: Conceptual doubt in metacharacters : Beginner in perl by haukex
in thread Conceptual doubt in metacharacters : Beginner in perl by Perl_Programmer1992

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