KISS. A single regex would not be clever

while (<DATA>)
{
    chomp;
    print "\n$_\n";
    if ( length() < 5 ) {
        print "too short\n"
    }
    elsif ( length() > 8 ) {
        print "too long\n"
    }
    elsif ( not /\d/ ) {
        print "need at least one digit\n"
    }
    elsif ( not /[a-z]/ ) {
        print "need at least one lowercase letter\n"
    }
    elsif ( not /[A-Z]/ ) {
        print "need at least one uppercase letter\n"
    }
}
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