my @strings = qw(
    aaaaa
    eeeee
    iiiii
    abcde
    aeiou
    bdfhj
);

my %regexes = (
    alternation => qr/a|A|e|E|i|I|o|O|u|U/,
    class       => qr/[AaEeIiOoUu]/
);

foreach my $string (@strings)
{
    print "$string:\n";
    while (my ($k, $r) = each %regexes)
    {
        print "\t$k - " . ($string =~ /$r/ ? 'YES' : 'NO') . $/;
    }
}
---------------
aaaaa:
        alternation - YES
        class - YES
eeeee:
        alternation - YES
        class - YES
iiiii:
        alternation - YES
        class - YES
abcde:
        alternation - YES
        class - YES
aeiou:
        alternation - YES
        class - YES
bdfhj:
        alternation - NO
        class - NO