Need to build a foreach statement from a hash array of variable elements in Perl

Question

I'm using XML::Simple in Perl to parse through an XML file and I'm stuck on how to build a loop to go through all the possible elements of an array within the hash.

Here's how to print the 0th element of the array:

print $book_info->{BookList}->{BookData}->{Prices}->{Price}[0]->{is_new};

My terminology might be off when using the words hash vs. array, but I'm trying to loop through all of the elements within {Price}[$ref]

I tried:

my @refs = $book_info->{BookList}->{BookData}->{Prices}->{Price};
foreach(@refs)
{
    print $book_info->{BookList}->{BookData}->{Prices}->{Price}[$_]->{store_id};
    print "\n";
}

and

foreach my $key (keys (%{$book_info->{BookList}->{BookData}->{Prices}->{Price}}))
{
    print $key."\n";
}

This next print statement returns a value of "ARRAY(0x159a57c)"

   print [$book_info->{BookList}->{BookData}->{Prices}->{Price}];

---

This works for the foreach, but I can't access the elements correctly:

 foreach (@{$book_info->{BookList}->{BookData}->{Prices}->{Price}}) { print $book_info->{BookList}->{BookData}->{Prices}->{Price}[$_]; #this line is wrong } 

Any suggestions? There are multiple {Price} elements within the {Prices} element, and each {Price} element has [x] attributes in the XML.

Answer 1

People aren't quite getting it right for you. If I understand you correctly, you want:

foreach my $element ( @{ $book_info->{BookList}->{BookData}->{Prices}->{Price} } ) {
    print $element->{store_id};
    print "\n";
}

Helpful advice for dealing with nested data structures can be found at http://perlmonks.org/?node=References+quick+reference

Answer 2

Marginally extending ysth 's answer:

foreach my $elem_ref (@{$book_info->{BookList}->{BookData}->{Prices}->{Price}})
{
    foreach my $key (sort keys %{$elem_ref})
    {
        print $elem_ref->{$key};
    }
    print "\n";
}

In part, this uses the recommendation from Perl Best Practices to denote references with the suffix _ref .

Answer 3

您是否尝试过使用Data :: Dumper转储$ book_info的内容（使用Data :: Dumper; print Dumper（$ book_info）？）它应该为您提供有关如何进行操作的线索。