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

Dear friends, I am doing a simple exercise using perl array reference. I want to print last element in the array using reference values. code which i written is given below 

#!/usr/bin/perl

@arr_val=(1,2,3,4,5,6,7,8);
$arr_ref=\@arr_val;

print $$arr_ref[-1];
print "\n";
print $$arr_ref[@$arr_ref-1];
print "\n";
print $#arr_val;
print "\n";
print $#arr_ref;

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Actually my doubt here is print $#arr_val is printing 7, at the same time print $#arr_ref is printing -1. What i have to do if i want to get last index i.e 7 using perl reference with the same method like $#arr_val.

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Re: Print last element using perl reference
by kennethk (Abbot) on Apr 29, 2010 at 15:49 UTC
    This is a situation where strictures would have been useful for you. If you run your posted code with strict, Perl gives you the error: 

    Global symbol "@arr_ref" requires explicit package name at fluff.pl li
+ne 12.
Execution of fluff.pl aborted due to compilation errors.

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    When you write #arr_ref, Perl examines the array @arr_ref, which you never defined. Since it is not defined, its highest index is -1. The expression you intended is likely $#$arr_ref, which returns 7 as desired. The following code does what I assume you intended, with strict and warnings thrown in for good measure: 

    #!/usr/bin/perl
use strict;
use warnings;

my @arr_val=(1,2,3,4,5,6,7,8);
my $arr_ref=\@arr_val;

print $$arr_ref[-1];
print "\n";
print $$arr_ref[@$arr_ref-1];
print "\n";
print $#arr_val;
print "\n";
print $#$arr_ref;

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    See perfreftut or perfref for more information on references, and see Use strict warnings and diagnostics or die for a howto and why for use strict; use warnings;.

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Re: Print last element using perl reference
by moritz (Cardinal) on Apr 29, 2010 at 15:42 UTC
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      Thanks friends

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Re: Print last element using perl reference
by ikegami (Patriarch) on Apr 29, 2010 at 15:53 UTC

    at the same time print $#arr_ref is printing -1.

    Of course. You never put anything in @arr_ref. Start by using use strict; use warnings;. 

    @array -> @$ref or @{$ref}

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    so 
    $#array -> $#$ref or $#{$ref}

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Re: Print last element using perl reference
by pemungkah (Priest) on Apr 29, 2010 at 18:44 UTC
    And of course the last actual value is $arr_ref->[-1].
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