Re: hashref to arrayref

You're starting with a hash, not a hash ref, so you never declared $errors.

my $errors = {}; #or my $errors=\%existing_hash;
my $array_ref=[%$errors];
my $csvout = new IO::File "> csvoutput.csv";
my $status = $csv->print ($csvout, [%$errors])
[download]

my %errors = ();
my $array_ref=[%errors];
my $csvout = new IO::File "> csvoutput.csv";
my $status = $csv->print ($csvout, [%$errors])
[download]

should work.

Edit: this was a block copy to show what changed. I did not test it, and the last line in each case should be

my $status = $csv->print ($csvout, $array_ref);
[download]

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Re^2: hashref to arrayref by mcarthey (Novice) on Jul 31, 2009 at 13:34 UTC
Thanks much for clarifying the use of the brackets and the references. I found part of my problem was my understanding of the square brackets. I thought they were also returning a reference (which they are) but only as evaluated at the time of the creation. I was using %errors before the hash was populated. I expected that the array reference would point to the populated list, but it did not. I guess it makes sense considering the brackets evaluate in list context and then return the reference. It seems to be working now, and I appreciate all your time! Thanks!	[reply]
Re^2: hashref to arrayref by mcarthey (Novice) on Jul 31, 2009 at 15:54 UTC
Regarding creating the array reference, is it possible to completely output the contents of the hash rather than the reference value? The hash is being accessed like this: `$errors{$key}{'date'} $errors{$key}{'time'}` [download] If I do the following I get a hash reference followed by the key value. `my $array_ref = [%errors]` [download] If I do this, `my $array_ref = [keys %errors]` [download] then I get only the keys, as you'd expect. Is there a way to generate the array to contain each element or will I have to resort to a looping construct? Thanks again!	[reply] [d/l] [select]
Re^3: hashref to arrayref by ssandv (Hermit) on Jul 31, 2009 at 16:09 UTC
I'm not clear on what you want the array to contain. Just the bottom-level values? If I understand correctly, your structure looks like `%errors=(key1 => { date => 'some date', time => 'some time', }, key2 => { date => 'some other date', time => 'some other time', }, ... );` [download] so when you read it in list context, you get a list of keys and hashrefs. What exactly are you trying to get back?	[reply] [d/l]
Re^4: hashref to arrayref by mcarthey (Novice) on Jul 31, 2009 at 17:46 UTC
I ended up doing the following to get what I needed: `my @values = map { ( $errors{$_}{'date'}, $errors{$_}{'time'}, $errors{$_}{'cnt' +}, $_ ) } keys %errors; my $value_ref = [@values]; my $file_ref = new IO::File "> csvoutput.csv"; my $status = $csv->print ($file_ref, $value_ref)` [download] The problem was that in my original code I was returning array references to the elements in the @values array. I simply had to remove the brackets and all is good. Thanks again for all your time!	[reply] [d/l]