#!/usr/bin/perl
use strict;
use warnings;

my @strings = qw/aaa_gjh1_dfgdf_0009 aaa_gjh_0000 00000 aaa_fdsfs_000 aaa_sdf_jdsh_01111/;

print is_valid($_) ? '' : "no ", "match: $_\n" for @strings;

sub is_valid {
    my $test = shift;
    return $test =~ /\Aaaa_\w{1,24}(?<=\D)\d{4}\z/;
}