Array Deferencing Question

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Fellow Monks please forgive my lack of knowledge in this matter:
I have an array reference with only one value in it (this is from inherited code).
It seems silly to run a loop in this manner:

foreach( @$res ) {
  print "$_->[0]\n";
}
[download]

when in this case there is only one row/value to pull out. going the loop route obvioulsy works, but I would think that you should be able to do this in a one-liner so I did this:

print "$res->[0]\n";
[download]

But got this result instead:
ARRAY(0x1bcfa60)
The is apparently some subtle piece of wisdom that I am missing. Any help that you can provide is greatly appreciated. Thanks in Advance!

Comment on Array Deferencing Question Select or Download Code

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Re: Array Deferencing Question by davido (Cardinal) on Oct 01, 2004 at 16:09 UTC
The subtile piece of wisdom is that you are dealing with an array of arrays. In other words, it's two levels deep. You would dereference it like `$res->[0][0]`, for example. Dave	[reply] [d/l]
Re:Array Deferencing Question by ikegami (Patriarch) on Oct 01, 2004 at 16:15 UTC
foreach is often used with single element as a convenient method of both setting `$_` and providing a block in which `last` can be used. As for your problem, the code is equivalent to: `foreach --+ +-- first iteration \| \| v v print( (@$res)[0]->[0], "\n"); ---------- \| +-- What $_ contained` [download] or just: `print "$res->[0][0]\n";`	[reply] [d/l] [select]
Re: Array Deferencing Question by periapt (Hermit) on Oct 01, 2004 at 19:47 UTC
Since this is an AoA, $res->[0]->[0] will also work consider `perl -e"$a=[['ref']];print q\|$a\n$a->[0]\n$a->[0]->[0]\n$$a[0]\n$a->[0 +][0]\n$a->[0]->[0]\|; " __END__ ARRAY(0x183f0d4) ARRAY(0x183efd8) ref ARRAY(0x183efd8) ref ref` [download] PJ use strict; use warnings; use diagnostics; (if needed)	[reply] [d/l]
Re: Array Deferencing Question by Scarborough (Hermit) on Oct 01, 2004 at 16:14 UTC
This seems to work for me `$ar = [1]; print $ar; #prints Array(*****) print $$ar[0]; #prints 1` [download] Or am I just being simple again? 80% of success is just turning up - Woody Allen*	[reply] [d/l]

use strict; use warnings; use diagnostics; (if needed)