my $re = qr/beer=(\d{2}).*(?:vodka=(\d{2}))?.*chips=(\d{3})/;

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

my @strs = (
    "beer=10&otherstuff&vodka=20&otherstuff&chips=100",
    "beer=10&otherstuff&juice=20&otherstuff&chips=100"
);

my @targets = qw/beer vodka chips/;

for ( @strs ) {
    my @matched;
    for my $target ( @targets ) {
        push @matched, $1 if ( /$target=(\d+)/ );
    }
    if ( @matched ) {
        print "matched: @matched\n";
    }
}

##</code><code>##

my @targets = qw/beer=(\d{2}) (vodka=(\d{2})) chips=(\d{3})/;

for ( @strs ) {
    my @matched;
    for my $target ( @targets ) {
        push @matched, ( /$target/ );
    }
    if ( @matched ) {
        print "matched: @matched\n";
    }
}