[lug] perl hash and array assignments in a loop

[Jeffrey Haemer]

Karl,

perl -e '$x{Karl} = ["Marx", "Horlen", "Rove"]; print "@{$x{Karl}}\n"; print
"$x{Karl}[1]\n"; print "$x{Karl}->[1]\n"'

I find the last easier to read than the one before it, but, since it's Perl,
they'll both work.

(Working this stuff out on the command line, in one-liners, is also easier
for me than trying to debug programs I have to edit and run.)

Hope this helps!

On Nov 16, 2007 2:15 AM, karl horlen <horenkarl at yahoo.com> wrote:

> I haven't programmed perl in awhile and can't find the
> answer to what should be a pretty simple operation.
>
> I read file input line by line in a loop.  I split the
> line fields out to an array called @tokens.  I know
> that array is being set correctly via a test print
> statement.
>
> The problem comes in when I try to assign the array to
> a hash key/variable.  After searching for a long time
> it looks like perl requires that I assign an array as
> a
> reference to the hash key.  I believe that part is
> working by debug print statements.
>
> However when it comes time to print the array VALUES
> as output, I either print the array value count or the
> array reference address and never the values
> contained in the array.
>
> 1) How do I output the array values contained in the
> hash key in a single print statement?  Similar to how
> you use 'print @tokens' for a standard array.
>
> 2) I know this will be soon on deck. How do I
> individually print each hash key array value
> separately using a loop?  I can handle the loop, I
> just
> need to know the convoluted syntax  to access the hash
> key array values one by one.
>
> My very simplified code snippet that isn't working
> (stuff left out)
>
> LOOP
>
>  my @tokens = split(' ');
>
>  # this works!
>  #print "@tokens";
>
>  # assign by reference
>  $report{$id}{$dateinfo} = \@tokens;
>
>  # TRY TO PRINT as an array
>  # WRONG! this prints the count of array
>  # values but not the values themselves!
>  print "dateinfo is :" . @{$report{$id}{$dateinfo}} .
> "\n";
>
>  # TRY TO PRINT as a scalar
>  # WRONG!  this prints the array ref not the
> values!!! -> dateinfo is :ARRAY(0x8f865fc)
>  print "dateinfo is :" . $report{$id}{$dateinfo} .
> "\n";
>
> END LOOP
>
> Also.  How would I add a scalar variable that keeps a
> running count of records that have the same date?
>
> This actually works:
>
>  $record{$id}{$dateinfo}++;
>
> But if I assign an array to hold the field values to
> that $dateinfo key as described above and then
> increment a count on it, I will overwrite the array
> stored in the hash key.
>
> That means I need to go with another hash level but
> I'm getting more confused with the perl syntax.  I
> imagine it would look something like this:
>
>  $record{$id}{$dateinfo}$count++;
>  $record{$id}{$dateinfo}@fields;
>
> Any Perl pros out there?
>
>
>
>
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-- 
Jeffrey Haemer <jeffrey.haemer at gmail.com>
720-837-8908 [cell]
http://goyishekop.blogspot.com
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