I think ur notation is what's confusing u. I don't think it's making a copy
but it would be better to write the $num construct as:
$nums->{$i} = $numbernames[$i];
HTH.
At 09:51 AM 3/2/2011 -0800, Barry Brevik wrote:
>I have a subroutine to which I want to pass a hash by reference. In the
>real program, the hash in the caller starts out empty, and the
>subroutine adds values to it.
>
>The hash eventually becomes quite large, so I want the subroutine to add
>values to the caller's hash. The following sample code does this, BUT I
>have a concern that the subroutine might be making a local copy of the
>caller's hash.
>
>The code below shows how I am doing it now. It appears to work as
>intended, but how can I ensure that the sub is not making a local copy
>of the hash??
>
>Thanks in advance:
>
>use strict;
>use warnings;
>
>my %numbers = ();
>
>makeNumbers(\%numbers);
>
>foreach my $key (keys(%numbers))
>{
> print "$key $numbers{$key}\n";
>}
>
>#-------------------------------
>sub makeNumbers
>{
> my @numbernames = qw(zero one two three four five);
>
> if (my $nums = shift)
> {
> for (my $i = 0; $i < 6; $i++)
> {
> ${%{$nums}}{$i} = $numbernames[$i];
> }
> }
>}
>
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