"Sudarshan Raghavan" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Rob Anderson wrote:
>
> >Hi Jeroen,
> >
> >
> >
> >>while (@values = $lcsr->fetchrow) {
> >>
> >>
> >
> >This is probably the root of your problem every time you go through this
> >loop, you are repopulating your array, put a my before @values.
> >
>
> Why do you think this is a problem? All the my would do is create a new
> lexical @values in every iteration.
> What do you mean by repopulating @values? my @values = ... would also
> populate @values.
> Am I missing something?
>
No it's me, I didn't know you could get a anon ref of a copy of an array
like this.
I do now.
Thanks
> >
> >
> >
> >> $key = shift @values;
> >> $key.= shift @values;
> >>
> >> push @$ref_to_a, [EMAIL PROTECTED];
> >>
> >>
> >
> >I don't recognise this format, I'd have done this line as.
> >push @$ref_to_a, [EMAIL PROTECTED];
> >
>
> [EMAIL PROTECTED] creates an anonymous arrayref by copying the values stored in
> @values. perldoc perlref, perldoc perllol
>
> If you are going use this statement
> push @{$ref_to_a}, [EMAIL PROTECTED];
> your while condition must be while (my @values = ...)
>
That's right, it did.
>
> If you are going to use
> push @{$ref_to_a}, [EMAIL PROTECTED];
> you can leave the while condition as while (@values = ...)
>
>
Yup, I realise that now
>
> Reason: 'shallow copying' vs 'deep copying'
> Read through this link
> http://www.stonehenge.com/merlyn/UnixReview/col30.html
>
Ta
> >
> >
> >
> >
> >> if ($old_key ne $key) {
> >> $hash{$key} = $ref_to_a;
> >> my $ref_to_a = undef;
> >> }
> >> $old_key = $key;
> >>}
> >>
> >>
> >
> >
> >Having made these comments, I haven't really understood your logic or the
> >need for your, old_key values. I'd have done something like the
following.
> >
> >while (my @row_data = $lcsr->fetchrow ) {
> >
>
> while (my ($key1, $key2, @row_data) = $lcsr->fetchrow) {
>
> > $key = shift @row_data;
> > $key.= shift @row_data;
> >
> > # create top level array if this is the first time we've seen this
key
> > if (! defined $data{$key}) {$data{$key} = []}
> >
>
> This is not neccessary, when you assign to a non-existent hash key, perl
> will create the key for you
>
I did need this line because of the way I was explictly getting my array
ref. My solution doesn't work without this line. I didn't realise you can
initialise undefined values to references in this manner.
It the same as this...
my $ref ; # ref to what?
push(@$ref, "1"); # a ref to an array
... which I would never have done. I'd have done the explict...
my $ref = []; # ref to an anon array
push(@$ref, "1");
Having your posts ripped apart is always a learning experience :-$
Cheers,
>
>
> >
> > my $array_ref = $data{$key};
> > push(@$array_ref, [EMAIL PROTECTED]);
> >
> >
>
> You can replace the code inside the while block with
> push (@{$data{$key1 . $key2}}, [EMAIL PROTECTED]);
>
> Your final code will be
> while (my ($key1, $key2, @row_data) = $lcsr->fetchrow) {
> push (@{$data{$key1 . $key2}}, [EMAIL PROTECTED]);
> }
>
> >}
> >
> >
> >Hope this helps
> >
> >Rob Anderson
> >
> >
> >
> >
> >
>
>
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