Re: finding the last element in a referenced array

From: Rhesa Rozendaal (perl&nntp_at_rhesa.com)
Date: 10/05/04 

Date: Tue, 05 Oct 2004 18:05:42 +0200
To: ".rhavin" <rhavin@shadowtec.de>

.rhavin wrote:
> i want to access the last elemt of an array... sounds like $#array, i
> know, but in my case, the array is stored as a reference in a
> construction like this:
>
> $hash{'%1'}{'%2'}=[1,2,3];
>
> i can access the last element by
>
> $hash{'%1'}{'%2'}[2]
>
> cos i know it is the second, but i need a way to access the last
> element without knowing whether it is the first, or the zeroth or
> whatever.

luckily for you, perl can count backwards too:

        @a = (1,2,3);
        print $a[-1]; # prints 3
        print $a[-2]; # prints 2

> i tried
>
> $hash{'%1'}{'%2'}[$#hash{'%1'}{'%2'}]

Look, the array is dereferenced by

        @{ $hash{'%1'}{'%2'} }

so the last element index would be

        $#{ $hash{'%1'}{'%2'} }

so you'd get at the last element with

        $hash{'%1'}{'%2'}[ $#{ $hash{'%1'}{'%2'} } ];

Of course,

        $hash{'%1'}{'%2'}[ -1 ]

is a bit more readable...

You could also have assigned the reference to a new variable:

        $r = $hash{'%1'}{'%2'};
        $last = $r->[ -1 ];
or
        $last = $r->[ $#$r ];
        

Rhesa

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