use warnings;
use strict;

while (my $address = <DATA>) {
    my ($street, $number)
        = ( $address =~ /  \A                             # start of string
                           ( \w{3} \. \s \w{3} \s \w{3} ) # 'aaa. bbb ccc'
                           \s                             # followed by a space
                           (?:nr\. \s )?                  # optional 'nr. '
                           \w{3}                          # 'ddd'
                           (\d+)                          # 'ddd...'
                        /ix
          );
    print "Street: $street, Number: $number\n";
}
exit;
__DATA__
aaa. bbb ccc nr. ddd23-56