Re: Simplify perl -e '$a = [1,2,3,4,7]; print $a->[$#{@$a}]'

[Wiggins d'Anconia]

Larsen, Errin M HMMA/IT wrote:
-----Original Message-----
From: Wiggins d'Anconia [mailto:[EMAIL PROTECTED] 
Sent: Thursday, March 10, 2005 8:55 AM
To: Marcos Rebelo
Cc: Perl Beginners
Subject: Re: Simplify perl -e '$a = [1,2,3,4,7]; print $a->[EMAIL PROTECTED]'

Marcos Rebelo wrote:
This is correctly printing '7' but '$a->[EMAIL PROTECTED]' seems to be 
encripted code.

Can I write this in a cleaner way?

$a->[-1]; ???
 Hi Wiggins,
  for those of us tryin' to keep up at home, can you walk us through
that bit a little?
  Here's what I spot:
  $a = [1,2,3,4,7] # this is initializing a scalar, $a, with a reference
to an array, [1,2,3,4,7]
 # $a-> this is dereferencing the array
 # as I understand it, and I really don't, the $#ARRAYNAME will give you
the number of elements, minus one, of an array?
 #  if that is the case, and then [EMAIL PROTECTED] ALSO derefernces the array, 
so
then
 #  [EMAIL PROTECTED] will be the number of elements in the array referenced by
$a, minus one (or, '4', in this example)
Actually I wasn't quite convinced about the [EMAIL PROTECTED] construct. Because 
theoretically @$a has already dereferenced the array, but it appears 
Perl will just do the right thing (amazing how it does that).  It could 
be written as $#{$a} or even!! $#$a, but I am not entirely sure where to 
hunt in the docs to find that one, probably under the $# construct, but 
not sure what that is called. possibly in perlvar but I don't have the 
time to check, and I suspect John Krahn or somebody will chime in with 
something brilliant :-).

 # so
 print $a->[EMAIL PROTECTED]
 # is equivelant to
 print $a->[4]
 # or, since [EMAIL PROTECTED] will always be the index of the last element of 
the
array:
 print $a->[-1]
Did I get it right?  That looks like homework to me ... Why would you
ever do that in a practical script?
--Errin
I think you got it. Ever want the last item in a list, I can think of 
lots of reasons to want that...

http://danconia.org
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