use strict;
use warnings;

my $data_in = '<container><a>bbb</a><b>cccc</b></container><?query?>';
my $data_out;
while ($data_in =~ /<container><a>(.+?)<\/a><b>(.+?)<\/b><\/container>(<\?query\?>)?/ig)  {
    print "1=$1\n";
    print "2=$2\n";
    print "3=$3\n";
    $data_out = "$2, $1$3 ";
}

__END__
1=bbb
2=cccc
3=<?query?>

##</code><code>##

while ($data_in =~ m{<container><a>(.+?)</a><b>(.+?)</b></container>(<\?query\?>)?}ig)  {