I have a hash structure that I'd like to keep intact after a subroutine call. I've tried several things, but nothing works. There's got to be something simple I've overlooked: 
my %myhash;
build_hash(\%myhash);
print Dumper(\%myhash);  ## shows %myhash to be empty

sub build_hash {
   my $href = shift;
   my %results;
   my $sth = $dbh->prepare( $query );
   $sth->execute();
   my $ct = 0;
   while (my $tmp_href = $sth->fetchrow_hashref) {
      $ct++;
      $results{$ct} = $tmp_href;
   }
   %{ $href } = %results;
   ## also tried Storable's dclone(), but same results
   ## $href = dclone(\%results);
   print Dumper($href); ## prints desired results
}

[download]
The resulting structure looks like this (it's exactly the way I want it): <code> $VAR1 = { '1' => { 'f1' => undef, 'f2' => 'bleep@hotmail.com', 'f3' => 'OTH', 'f4' => 'N',

In reply to Preserving hash structure after subroutine call by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.